This study was supported by NCI (R01-94160 and R01-155086), IU Simon Cancer Center and Wells Center for Pediatric Research.

This study has been approved by the IACUC Committee at Indiana University School of Medicine.
1. Generate Mice with Correct Genotypes
<ol>
	<li>Establish a mouse model of BCCs. Mate K14-CreER mice (Jackson laboratory stock number 005107) with R26-SmoM2YFP mice (Jackson laboratory stock number 005130) (18) to generate K14-creER+ and R26-SmoM2YFP+ mice.</li>
	<li>Perform genotyping. Immerse tail specimens (0.5 cm long) in directPCR tail lysis solution with 1 mg/ml proteinase K at 55 &deg;C overnight with shaking. The next day, remove tissue debris by centrifugation at top speed in a micro-centrifuge (to keep the supernatant for genotyping). Use 1 &mu;l of the supernatant for each PCR reaction with the primers and conditions recommended by the vendor. Select the mice with the right genotypes (at age of 3-6 weeks, buprenorphine at 0.05-0.1 mg/kg will be applied via SQ every 8-12 hr for 2-3 days after tail snip) for step 2.</li>
</ol>
2. Induce Expression of SmoM2 in Skin Keratinocytes
Induce SmoM2 expression in keratinocytes by oral administration of tamoxifen (5 &mu;g/kg body weight in 50 ml of vegetable oil in each feeding) for 5 consecutive days via oral gavage with a feeding needle (curved 20 gauge).
3. Preparing Skin Specimens
In general, phenotypes are more severe on the ear and the tail in K14creER/R26SmoM2GFP mice. To prepare for cell analyses, we first harvest the mouse skin after animal sacrifice with an institutional approved procedure (CO2 plus cervical dislocation).
4. Isolating Epidermis
<ol>
	<li>After sacrifice mice with an approved procedure (see step 3), remove fur using a trimmer. Immerse skin specimens in dispase solution (5 mg/ml in DMEM with 10% FBS) at 37 &deg;C for 1-2 hr (1 hr for mice less than 8 weeks old and 2 hr for mice old than 8 weeks).</li>
	<li>Following dispase treatment, separate epidermis from dermis by forceps.</li>
</ol>
5. Generate Single Cells
<ol>
	<li>To obtain single cell population, mince epidermis by scissors and then immerse in collagenase IV solution (1 mg/ml in DMEM with 10% FBS) for 1-2 hr at 37 &deg;C in a 50 ml tube. Try to gently swirl the tubes every 20 min to help cell disassociation.</li>
	<li>Inspect cell disassociation under microscope. When single cells can be detected in the collagenase medium, incubate the specimen for an additional 30 min to increase the cell yield. In general, the epidermis from one mouse can yield up to 107 cells.</li>
	<li>Filter the tissue mixture through cell strainer (pore size 70 &mu;m), spin cells down at 1,500 rpm via bench top centrifugation, and wash once time with PBS.</li>
</ol>
6. Label Cells and Perform Flow Cytometry Analyses
<ol>
	<li>Resuspend the cells in 10% FBS in PBS at 2.5 x 106 cells/ml to block non-specific binding (on ice for 30 min)</li>
	<li>Take an aliquot of cells to each of 1.5 ml microtubes for specific antibody labeling. Add different antibodies to each tube at a final concentration of 2 &mu;g/ml. Mix antibodies with cells via a gentle vertex for several seconds and leave them on ice for 30 min, then wash with 1 ml PBS. For BCC specimens, we used the antibodies for following biomarkers: CD11b-PE plus Gr1-APC (myeloid cells or myeloid-derived suppressor cells); vimentin-FITC (fibroblast) (see reagents for details).</li>
	<li>For intracellular staining, we use a kit and follow the vendor's manual (see Reagents for details). We use fresh cells to analyze cell surface markers. After surface marker staining, wash cells, and resuspend them in PBS. Add DAPI to the cell mixture at a final concentration of 1 &mu;g/ml. DAPI will stain dead cells that will be gated out from further analyses.</li>
	<li>Analyze the data with specific software. We first select single cells based on the FSC vs. SSC plot, and use DAPI negative population (live cells) for further analysis.</li>
</ol>

<ol>
	<li>Rogers, H. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Incidence+estimate+of+nonmelanoma+skin+cancer+in+the+United+States.">Incidence estimate of nonmelanoma skin cancer in the United States.</a> Arch. Dermatol. 146, 283-287 (2006).</li><li>Epstein, E. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basal+cell+carcinomas:+attack+of+the+hedgehog.">Basal cell carcinomas: attack of the hedgehog.</a> Nat. Rev. Cancer. 8, 743-754 (2008).</li><li>Yang, L., Xie, G., Fan, Q., Xie, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activation+of+the+hedgehog-signaling+pathway+in+human+cancer+and+the+clinical+implications.">Activation of the hedgehog-signaling pathway in human cancer and the clinical implications.</a> Oncogene. 29, 469-481 (2010).</li><li>Johnson, R. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+homolog+of+patched,+a+candidate+gene+for+the+basal+cell+nevus+syndrome.">Human homolog of patched, a candidate gene for the basal cell nevus syndrome.</a> Science. 272, 1668-1671 (1996).</li><li>Hahn, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+mammalian+patched+homolog+is+expressed+in+target+tissues+of+sonic+hedgehog+and+maps+to+a+region+associated+with+developmental+abnormalities.">A mammalian patched homolog is expressed in target tissues of sonic hedgehog and maps to a region associated with developmental abnormalities.</a> J. Biol. Chem. 271, 12125-12128 (1996).</li><li>Hahn, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mutations+of+the+human+homolog+of+Drosophila+patched+in+the+nevoid+basal+cell+carcinoma+syndrome.">Mutations of the human homolog of Drosophila patched in the nevoid basal cell carcinoma syndrome.</a> Cell. 85, 841-851 (1996).</li><li>Xie, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activating+Smoothened+mutations+in+sporadic+basal-cell+carcinoma.">Activating Smoothened mutations in sporadic basal-cell carcinoma.</a> Nature. 391, 90-92 (1998).</li><li>Reifenberger, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Missense+mutations+in+SMOH+in+sporadic+basal+cell+carcinomas+of+the+skin+and+primitive+neuroectodermal+tumors+of+the+central+nervous+system.">Missense mutations in SMOH in sporadic basal cell carcinomas of the skin and primitive neuroectodermal tumors of the central nervous system.</a> Cancer Res. 58, 1798-1803 (1998).</li><li>Lam, C. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+frequent+activated+smoothened+mutation+in+sporadic+basal+cell+carcinomas.">A frequent activated smoothened mutation in sporadic basal cell carcinomas.</a> Oncogene. 18, 833-836 (1999).</li><li>Nilsson, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+basal+cell+carcinomas+and+trichoepitheliomas+in+mice+overexpressing+GLI-1.">Induction of basal cell carcinomas and trichoepitheliomas in mice overexpressing GLI-1.</a> Proc. Natl. Acad. Sci. U.S.A. 97, 3438-3443 (2000).</li><li>Sheng, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissecting+the+oncogenic+potential+of+Gli2:+deletion+of+an+NH(2)-terminal+fragment+alters+skin+tumor+phenotype.">Dissecting the oncogenic potential of Gli2: deletion of an NH(2)-terminal fragment alters skin tumor phenotype.</a> Cancer Res. 62 (2), 5308-5316 (2002).</li><li>Reifenberger, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Somatic+mutations+in+the+PTCH,+SMOH,+SUFUH+and+TP53+genes+in+sporadic+basal+cell+carcinomas.">Somatic mutations in the PTCH, SMOH, SUFUH and TP53 genes in sporadic basal cell carcinomas.</a> Br. J. Dermatol. 152, 43-51 (2005).</li><li>Guha, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hedgehog+inhibitor+gets+landmark+skin+cancer+approval,+but+questions+remain+for+wider+potential.">Hedgehog inhibitor gets landmark skin cancer approval, but questions remain for wider potential.</a> Nat. Rev. Drug Discov. 11, 257-258 (2012).</li><li>Sekulic, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficacy+and+safety+of+vismodegib+in+advanced+basal-cell+carcinoma.">Efficacy and safety of vismodegib in advanced basal-cell carcinoma.</a> N. Engl. J. Med. 366, 2171-2179 (2012).</li><li>Tang, J. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibiting+the+hedgehog+pathway+in+patients+with+the+basal-cell+nevus+syndrome.">Inhibiting the hedgehog pathway in patients with the basal-cell nevus syndrome.</a> N. Engl. J. Med. 366, 2180-2188 (2012).</li><li>Aszterbaum, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultraviolet+and+ionizing+radiation+enhance+the+growth+of+BCCs+and+trichoblastomas+in+patched+heterozygous+knockout+mice.">Ultraviolet and ionizing radiation enhance the growth of BCCs and trichoblastomas in patched heterozygous knockout mice.</a> Nat. Med. 5, 1285-1291 (1999).</li><li>Pazzaglia, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+patched-associated+susceptibility+to+radiation+induced+tumorigenesis+by+genetic+background.">Modulation of patched-associated susceptibility to radiation induced tumorigenesis by genetic background.</a> Cancer Res. 64, 3798-3806 (2004).</li><li>Athar, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+smoothened+signaling+prevents+ultraviolet+B-induced+basal+cell+carcinomas+through+regulation+of+Fas+expression+and+apoptosis.">Inhibition of smoothened signaling prevents ultraviolet B-induced basal cell carcinomas through regulation of Fas expression and apoptosis.</a> Cancer Res. 64, 7545-7552 (2004).</li><li>Mancuso, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basal+cell+carcinoma+and+its+development:+insights+from+radiation-induced+tumors+in+Ptch1-deficient+mice.">Basal cell carcinoma and its development: insights from radiation-induced tumors in Ptch1-deficient mice.</a> Cancer Res. 64, 934-941 (2004).</li><li>Ellis, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patched+1+conditional+null+allele+in+mice.">Patched 1 conditional null allele in mice.</a> Genesis. 36, 158-161 (2003).</li><li>Mao, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+somatic+mouse+model+to+survey+tumorigenic+potential+applied+to+the+Hedgehog+pathway.">A novel somatic mouse model to survey tumorigenic potential applied to the Hedgehog pathway.</a> Cancer Res. 66, 10171-10178 (2006).</li><li>Wang, G. Y., Wang, J., Mancianti, M. L., Epstein, E. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basal+cell+carcinomas+arise+from+hair+follicle+stem+cells+in+Ptch1(+/-)+mice.">Basal cell carcinomas arise from hair follicle stem cells in Ptch1(+/-) mice.</a> Cancer Cell. 19, 114-124 (2011).</li><li>Grachtchouk, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basal+cell+carcinomas+in+mice+arise+from+hair+follicle+stem+cells+and+multiple+epithelial+progenitor+populations.">Basal cell carcinomas in mice arise from hair follicle stem cells and multiple epithelial progenitor populations.</a> J. Clin. Invest. 121, 1768-1781 (2011).</li><li>Kasper, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wounding+enhances+epidermal+tumorigenesis+by+recruiting+hair+follicle+keratinocytes.">Wounding enhances epidermal tumorigenesis by recruiting hair follicle keratinocytes.</a> Proc. Natl. Acad. Sci. U.S.A. 108, 4099-4104 (2011).</li><li>Youssef, K. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+the+cell+lineage+at+the+origin+of+basal+cell+carcinoma.">Identification of the cell lineage at the origin of basal cell carcinoma.</a> Nat Cell Biol. 12, 299-305 (2010).</li><li>Yauch, R. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Smoothened+mutation+confers+resistance+to+a+Hedgehog+pathway+inhibitor+in+medulloblastoma.">Smoothened mutation confers resistance to a Hedgehog pathway inhibitor in medulloblastoma.</a> Science. 326, 572-574 (2009).</li><li>Buonamici, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interfering+with+resistance+to+smoothened+antagonists+by+inhibition+of+the+PI3K+pathway+in+medulloblastoma.">Interfering with resistance to smoothened antagonists by inhibition of the PI3K pathway in medulloblastoma.</a> Sci. Transl. Med. 2, 51ra70 (2010).</li><li>Dijkgraaf, G. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+molecule+inhibition+of+GDC-0449+refractory+smoothened+mutants+and+downstream+mechanisms+of+drug+resistance.">Small molecule inhibition of GDC-0449 refractory smoothened mutants and downstream mechanisms of drug resistance.</a> Cancer Res. 71, 435-444 (2011).</li><li>Guo, Z., Draheim, K., Lyle, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+culture+of+adult+epithelial+stem+cells+from+human+skin.">Isolation and culture of adult epithelial stem cells from human skin.</a> J. Vis. Exp. (49), e2561 (2011).</li><li>Li, L., Fukunaga-Kalabis, M., Herlyn, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+three-dimensional+human+skin+reconstruct+model:+a+tool+to+study+normal+skin+and+melanoma+progression.">The three-dimensional human skin reconstruct model: a tool to study normal skin and melanoma progression.</a> J. Vis. Exp. (54), e2937 (2011).</li><li>Anacker, D., Moody, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+organotypic+raft+cultures+from+primary+human+keratinocytes.">Generation of organotypic raft cultures from primary human keratinocytes.</a> J. Vis. Exp. (60), e3668 (2012).</li></ol>

The authors declare that they have no competing financial interests.

We have described a method for cell population analysis in BCCs. Tumor tissues are consistent of many cell types, and each cell type behaves differently at a given time of carcinogenesis, which is very hard to recapture even under the best in vitro conditions. Using this protocol, we showed that development of basal cell carcinoma is accompanied by expansion of epidermal stem cells as well as recruitment of myeloid cells. In comparison with immunohistochemistry or immunofluorescent analyses, cell population analyses give a more quantitative assessment of cell population changes since specific antibodies to a variety of cell types are now available.
For this protocol, 10 weeks are needed to complete the study because phenotypic change from gene induction requires time. It is thus important to plan the experiment ahead of time. For cell isolation and analyses, two whole days may be needed. Because live cells are used for analyses, it is important to reserve a FACSCalibur ahead of time. We have also listed common problems when working with this protocol (see below).
In our experience, below are common problems we encountered:
<ol>
	<li>Poor separation of epidermis: This may be caused by incomplete dispase treatment (Please increase the time of diapase treatment) or insufficient dispase solution (The skin needs to be totally immersed in dispase solution). We use at least 5 ml of dispase solution for one mouse. The volume may vary based on the size of skin.</li>
	<li>Low yield of cell number: This may due to incomplete digestion with collagenase IV. Please first check collagenase concentration or expiration date. This can also be caused by insufficient amount of epidermis used. Furthermore, enzyme digestion should be performed at to 37 &deg;C with shaking (please adjust temperature before perform digestion).</li>
	<li>Cell clumps: This is very common for skin cells (pipette cells a few times after going through strainer (before centrifugation), or existence of Mg2+ and Ca2+ in the solution (please use Mg2+ and Ca2+-free PBS for cell wash).</li>
	<li>Too many dead cells: This may be a result of degraded tissues (please use fresh tissues), or over-digestion (avoid extended incubation with dispase and collagenase IV).</li>
</ol>
This protocol can be combined with bone marrow transplantation or tissue transplantation to examine the cell origin. For example, transplantation of GFP-expressing bone marrow cells into lethally irradiated mice will allow us to examine the contribution of bone marrow cells to tumor-associated fibroblasts and myeloid cells. Similarly, skin tumors can be transplanted into a new mouse host to examine tumor-host interactions.
In addition to examine cell population changes during carcinogenesis, this protocol will also allow researchers to examine effects of drug treatments to the cells in the tumor environment. Although this protocol is designed to use for cell population analyses during skin carcinogenesis, slight modifications can be made for other cancer types.
In summary, cell population analyses in mouse models of skin cancer can give us the dynamic cellular changes during carcinogenesis, leading to a better understanding of cell biology in neoplastic transformation and different cellular events in the transformation process.

As the most common type of human cancer, basal cell carcinoma (BCC) affects about 2 million Americans per year 1. Accumulating evidence indicate that abnormal activation of hedgehog (Hh) signaling is the driving force underlying BCC development (Reviewed in 2,3). Alterations of Hh signaling in BCCs include inactivating mutations of PTCH1 4-6, gain-of-function mutations of SMO 7-9, and aberrant expression of Hh pathway transcription factors GLI1 10 and GLI2 11 or rare inactivated mutations of negative regulator Su(Fu)12. Through all these and other studies, Federal Drug Administration (FDA) has recently approved the use of Hh signaling inhibitor Vismodegib to treat metastatic and locally advanced BCCs13-15.
Despite all these achievements 16, we still do not understand the molecular and cellular mechanisms by which Hh signaling drives carcinogenesis. Establishing animal models using tissue-specific activation of Hh signaling is still important for these studies and for our understanding of drug resistance. In mice, wild-type mice do not develop BCCs, even under heavy doses of carcinogens, UV or ionizing radiation. In contrast, Ptch1+/- mice are susceptible to BCC development 17,18. The penetrance of BCC development in Ptch1+/- mice is over 50% 18,19 although Ptch1+/- mice rarely develop full-grown BCCs if kept under normal conditions. Due to the embryonic lethality of Ptch1-/-, tissue-specific knockout of PTCH1 is generally used for the study 20. In addition, conditional skin-specific expression of oncogenic SmoM2YFP (Krt14-creER:R26-SmoM2YFP or Krt14-cre:R26-SmoM2YFP) leads to formation of multiple microscopic BCCs at a very early age, providing an easy genetic assay for Hh signaling downstream of SMO 21.
There are three major issues in our knowledge of BCC biology. First, the cellular origin of BCCs is not entirely clear. While some studies support the budge of hair follicle as the stem cell site 22-24, Youssef et al. 25 localized the murine cell of origin of cutaneous Hh-driven tumors to be in the inter-follicular epidermis region, not in the hair follicle, by using cell-specific Cre to activate expression of a ROSA26-driven transgenic mutant SMO. Second, cellular interactions during BCC development are not well understood. It is known that keratinocytes with activated Hh signaling can lead to formation of BCCs, but other cellular changes are not well-understood. Furthermore, treatment of Smo antagonists in mice can lead to drug resistance 26-28. Thus novel targets for BCC are greatly needed. Understanding these three issues requires analyses of cellular changes in mice during carcinogenesis. While several methods have been published for keratinocyte culture, flow cytometry and skin stem cell isolation 29-31, there are currently no comprehensive procedures for cell analyses in mouse BCCs. By combining methods for mouse model of BCCs, separation of epidermis, generation of single cells from tissue and cell analyses, we will provide readers with a set of procedures to study cell signaling, cellular and molecular interactions during BCC development. We believe that this protocol will allow readers to see how each procedure is accomplished. In addition, we provided some data to illustrate what the results should look like, and troubleshooting to help readers to overcome difficulties during performing these procedures.

<table border="1">
 <tbody>
 <tr>
 <td>Reagents</td>
 <td> Company</td>
 <td> Cat#</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>directPCR lysis reagent (tail) </td>
 <td>Viagen Biotech </td>
 <td>102-T </td>
 <td>store @ 4 &deg;C</td>
 </tr>
 <tr>
 <td>proteinase K </td>
 <td> Sigma </td>
 <td>P2308 </td>
 <td>store @ -20 &deg;C</td>
 </tr>
 <tr>
 <td>ApliTag 360 taq polymerase </td>
 <td>Applied biosystems </td>
 <td>N8080155 </td>
 <td> store @ -20 &deg;C</td>
 </tr>
 <tr>
 <td>Tamoxifen </td>
 <td>Sigma </td>
 <td>T5648 </td>
 <td> store @ 4 &deg;C</td>
 </tr>
 <tr>
 <td>Feeding needle (20 gauge) </td>
 <td>Fisher scientific </td>
 <td>01-290-9B</td>
 <td></td>
 </tr>
 <tr>
 <td>Dispase </td>
 <td>Roche Diagnostic </td>
 <td>04942078001</td>
 <td>store @ 4 &deg;C</td>
 </tr>
 <tr>
 <td>Collagenase IV </td>
 <td>Worthington </td>
 <td>LS004189</td>
 <td>store @ -20 &deg;C</td>
 </tr>
 <tr>
 <td>Cell strainer </td>
 <td>Fisher scientific </td>
 <td>08-771-2</td>
 <td></td>
 </tr>
 <tr>
 <td>Anti-CD11b-PE </td>
 <td>eBioscience </td>
 <td> 12-0112-81</td>
 <td>store @ 4 &deg;C</td>
 </tr>
 <tr>
 <td>Anti-Gr1-APC </td>
 <td>eBioscience </td>
 <td> 17-5931-81</td>
 <td>store @ 4 &deg;C</td>
 </tr>
 <tr>
 <td>Anti-vimentin-FITC </td>
 <td>eBioscience </td>
 <td>11-9897-80 </td>
 <td>store @ 4 &deg;C</td>
 </tr>
 </tbody>
</table>

cell population analyses during skin carcinogenesis

Cancer development is a multiple-step process involving many cell types including cancer precursor cells, immune cells, fibroblasts and endothelial cells. Each type of cells undergoes signaling and functional changes during carcinogenesis. The current challenge for many cancer researchers is to dissect these changes in each cell type during the multiple-step process in vivo. In the last few years, the authors have developed a set of procedures to isolate different cell populations during skin cancer development using K14creER/R26-SmoM2YFP mice. The procedure is divided into 6 parts: 1) generating appropriate mice for the study (K14creER+ and R26-SmoM2YFP+ mice in this protocol); 2) inducing SmoM2YFP expression in mouse skin; 3) preparing mouse skin biopsies; 4) isolating epidermis from skin; 5) preparing single cells from epidermis; 6) labeling single cell populations for flow cytometry analysis. Generation of sufficient number of mice with the right genotype is the limiting step in this protocol, which may take up to two months. The rest of steps take a few hours to a few days. Within this protocol, we also include a section for troubleshooting. Although we focus on skin cancer, this protocol may be modified to apply for other animal models of human diseases.

It is known that mice do not develop basal cell carcinomas except with Hh signaling activation. Figure 1 shows the skin phenotype following induced expression of oncogenic smoothened, SmoM2YFP. Figure 2 shows analysis of myeloid cells in normal and tumor-bearing mice. CD11b+ Gr1+ cells are derived from myeloid cells, and some of them are myeloid derived suppressor cells. In normal situation, the CD11b+Gr1+ cell population is hardly detectable, but will increase in response to inflammation or tumor development. We showed that induced expression of SmoM2YFP in skin results in an increase in CD11b+Gr1+ cells. Currently, the molecular mechanisms underlying this change in BCCs are not clear.
<img alt="Figure 1" src="/files/ftp_upload/50311/50311fig1.jpg" /> 
Figure 1. Morphological changes after SmoM2YFP induction in mouse skin. The top shows a diagram of mouse genotypes. The middle panel: the K14creER+ and R26-SmoM2YFP+ mouse treated with tamoxifen showed grossly abnormality in the skin (right) as well as skin tumors in the H&amp;E section (left). The bottom panel: the mouse without SmoM2YFP induction showed normal looking skin (right) and no abnormal morphology in the H&amp;E section (left).
<img alt="Figure 2" src="/files/ftp_upload/50311/50311fig2.jpg" /> 
Figure 2. Flow analysis of CD11b+Gr1+ cells. To examine the change of CD11b+Gr1+ cells during skin cancer development, we isolated single cells and stained with fluorescence-labeled antibodies to CD11b and Gr1. After analysis with FlowJo, we noticed an increase of this cell population in skin tissues from tamoxifen-treated mice.

Watch this Scientific Journal Video about Cell Population Analyses During Skin Carcinogenesis at JoVE.com

Cell Population Analyses During Skin Carcinogenesis

Carcinogenesis is a process involving interactions between cancer cells and the cancer microenvironment. To dissect the molecular events, one needs to isolate different cell populations at different stages during cancer development. Using a mouse model for basal cell carcinoma, we describe a protocol for cell analyses during carcinogenesis.

Cancer development is  a multiple-step process involving many cell types including cancer precursor  cells, immune cells, fibroblasts and endothelial ...

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12.3K Views.  Indiana University. Carcinogenesis is a process involving interactions between cancer cells and the cancer microenvironment. To dissect the molecular events, one needs to isolate different cell populations at different stages during cancer development. Using a mouse model for basal cell carcinoma, we describe a protocol for cell analyses during carcinogenesis.

Video: Cell Population Analyses During Skin Carcinogenesis

Accurate and Simple Measurement of the Pro-inflammatory Cytokine IL-1&beta; using a Whole Blood Stimulation Assay

Inflammatory processes resulting from the secretion of soluble mediators by immune cells, lead to various manifestations in skin, joints and other tissues as well as altered cytokine homeostasis. The innate immune system plays a crucial role in recognizing pathogens and other endogenous danger stimuli. One of the major cytokines released by innate immune cells is Interleukin (IL)-1. Therefore, we utilize a whole blood stimulation assay in order to measure the secretion of inflammatory cytokines and specifically of the pro-inflammatory cytokine IL-1&beta; 1, 2, 3.
Patients with genetic dysfunctions of the innate immune system causing autoinflammatory syndromes show an exaggerated release of mature IL-1&beta; upon stimulation with LPS alone. In order to evaluate the innate immune component of patients who present with inflammatory-associated pathologies, we use a specific immunoassay to detect cellular immune responses to pathogen-associated molecular patterns (PAMPs), such as the gram-negative bacterial endotoxin, lipopolysaccharide (LPS). These PAMPs are recognized by pathogen recognition receptors (PRRs), which are found on the cells of the innate immune system 4, 5, 6, 7. A primary signal, LPS, in conjunction with a secondary signal, ATP, is necessary for the activation of the inflammasome, a multiprotein complex that processes pro-IL-1&beta; to its mature, bioactive form 4, 5, 6, 8, 9, 10.
The whole blood assay requires minimal sample manipulation to assess cytokine production when compared to other methods that require labor intensive isolation and culturing of specific cell populations. This method differs from other whole blood stimulation assays; rather than diluting samples with a ratio of RPMI media, we perform a white blood cell count directly from diluted whole blood and therefore, stimulate a known number of white blood cells in culture 2. The results of this particular whole blood assay demonstrate a novel technique useful in elucidating patient cohorts presenting with autoinflammatory pathophysiologies.

Accurate and Simple Measurement of the Pro-inflammatory Cytokine IL-1&#946; using a Whole Blood Stimulation Assay

We describe a simple immunoassay to measure the production of pro-inflammatory cytokines, such as IL-1 beta production, in patients presenting with autoinflammatory phenotypes. By activating cells in whole blood cultures with pathogen-associated molecular patterns, specifically with lipopolysaccharide, cytokine secretion can be conveniently evaluated in whole blood supernatants.

Inflammatory processes resulting from the secretion of soluble mediators by immune cells, lead to various manifestations in skin, joints and other tissues ...

Renal Capsule Xenografting and Subcutaneous Pellet Implantation for the Evaluation of Prostate Carcinogenesis and Benign Prostatic Hyperplasia

New therapies for two common prostate diseases, prostate cancer (PrCa) and benign prostatic hyperplasia (BPH), depend critically on experiments evaluating their hormonal regulation. Sex steroid hormones (notably androgens and estrogens) are important in PrCa and BPH; we probe their respective roles in inducing prostate growth and carcinogenesis in mice with experiments using compressed hormone pellets. Hormone and/or drug pellets are easily manufactured with a pellet press, and surgically implanted into the subcutaneous tissue of the male mouse host. We also describe a protocol for the evaluation of hormonal carcinogenesis by combining subcutaneous hormone pellet implantation with xenografting of prostate cell recombinants under the renal capsule of immunocompromised mice. Moreover, subcutaneous hormone pellet implantation, in combination with renal capsule xenografting of BPH tissue, is useful to better understand hormonal regulation of benign prostate growth, and to test new therapies targeting sex steroid hormone pathways.

We describe the manufacture of compressed hormone pellets, as well as subcutaneous surgical implantation into mice. This strategy can be combined with the growth of cell and tissue xenografts under the renal capsule of athymic nude mice to evaluate hormonal carcinogenesis and regulation of benign prostate growth.

New therapies for two common prostate diseases,  prostate cancer (PrCa) and benign prostatic hyperplasia (BPH), depend  critically on experiments ...

Dried Blood Spot Collection of Health Biomarkers to Maximize Participation in Population Studies

Biomarkers are directly-measured biological indicators of disease, health, exposures, or other biological information. In population and social sciences, biomarkers need to be easy to obtain, transport, and analyze. Dried Blood Spots meet this need, and can be collected in the field with high response rates. These elements are particularly important in longitudinal study designs including interventions where attrition is critical to avoid, and high response rates improve the interpretation of results. Dried Blood Spot sample collection is simple, quick, relatively painless, less invasive then venipuncture, and requires minimal field storage requirements (i.e.&#160;samples do not need to be immediately frozen and can be stored for a long period of time in a stable freezer environment before assay). The samples can be analyzed for a variety of different analytes, including cholesterol, C-reactive protein, glycosylated hemoglobin, numerous cytokines, and other analytes, as well as provide genetic material. DBS collection is depicted as employed in several recent studies.

Biomarkers are directly-measured biological indicators of disease or health. In population and social sciences, biomarkers need to be easy to obtain, transport, and analyze. Dried Blood Spot (DBS) collection meets this need, can be collected in the field with high response rates&#160;and analyzed for a variety of biomarkers.

Biomarkers are directly-measured biological indicators of disease, health, exposures, or other biological information. In population and social sciences, ...

Sequential In vivo Imaging of Osteogenic Stem/Progenitor Cells During Fracture Repair

Bone turns over continuously and is highly regenerative following injury. Osteogenic stem/progenitor cells have long been hypothesized to exist, but in vivo demonstration of such cells has only recently been attained. Here, in vivo imaging techniques to investigate the role of endogenous osteogenic stem/progenitor cells (OSPCs) and their progeny in bone repair are provided. Using osteo-lineage cell tracing models and intravital imaging of induced microfractures in calvarial bone, OSPCs can be directly observed during the first few days after injury, in which critical events in the early repair process occur. Injury sites can be sequentially imaged revealing that OSPCs relocate to the injury, increase in number and differentiate into bone forming osteoblasts. These methods offer a means of investigating the role of stem cell-intrinsic and extrinsic molecular regulators for bone regeneration and repair.

Sequential In vivo Imaging of Osteogenic Stem/Progenitor Cells During Fracture Repair

Quantitative measurement of bone progenitor function in fracture healing requires high resolution serial imaging technology. Here, protocols are provided for using intravital microscopy and osteo-lineage tracking to sequentially image and quantify the migration, proliferation and differentiation of endogenous osteogenic stem/progenitor cells in the process of repairing bone fracture.

Bone turns over continuously and is highly regenerative following injury. Osteogenic stem/progenitor cells have long been hypothesized to exist, but in ...

Murine Endoscopy for In Vivo Multimodal Imaging of Carcinogenesis and Assessment of Intestinal Wound Healing and Inflammation

Mouse models are widely used to study pathogenesis of human diseases and to evaluate diagnostic procedures as well as therapeutic interventions preclinically. However, valid assessment of pathological alterations often requires histological analysis, and when performed ex vivo, necessitates death of the animal. Therefore in conventional experimental settings, intra-individual follow-up examinations are rarely possible. Thus, development of murine endoscopy in live mice enables investigators for the first time to both directly visualize the gastrointestinal mucosa and also repeat the procedure to monitor for alterations. Numerous applications for in vivo murine endoscopy exist, including studying intestinal inflammation or wound healing, obtaining mucosal biopsies repeatedly, and to locally administer diagnostic or therapeutic agents using miniature injection catheters. Most recently, molecular imaging has extended diagnostic imaging modalities allowing specific detection of distinct target molecules using specific photoprobes. In conclusion, murine endoscopy has emerged as a novel cutting-edge technology for diagnostic experimental in vivo imaging and may significantly impact on preclinical research in various fields.

Murine Endoscopy for In Vivo Multimodal Imaging of Carcinogenesis and Assessment of Intestinal Wound Healing and Inflammation

Small animal imaging techniques allow serial diagnostic examinations and therapeutic interventions in vivo. Recently, the scope of applications has significantly widened and currently includes assessment of colonic tumor development, wound healing and monitoring of inflammation. This protocol illustrates these diverse potential applications of murine endoscopy.

Mouse models are widely used to study pathogenesis of human diseases and to evaluate diagnostic procedures as well as therapeutic interventions ...

A Mouse Fetal Skin Model of Scarless Wound Repair

Early in utero, but not in postnatal life, cutaneous wounds undergo regeneration and heal without formation of a scar. Scarless fetal wound healing occurs across species but is age dependent. The transition from a scarless to scarring phenotype occurs in the third trimester of pregnancy in humans and around embryonic day 18 (E18) in mice. However, this varies with the size of the wound with larger defects generating a scar at an earlier gestational age. The emergence of lineage tracing and other genetic tools in the mouse has opened promising new avenues for investigation of fetal scarless wound healing. However, given the inherently high rates of morbidity and premature uterine contraction associated with fetal surgery, investigations of fetal scarless wound healing in vivo require a precise and reproducible surgical model. Here we detail a reliable model of fetal scarless wound healing in the dorsum of E16.5 (scarless) and E18.5 (scarring) mouse embryos.

During mammalian development, early gestational skin wounds heal without a scar. Here we detail a reliable and reproducible model of fetal scarless wound healing in the cutaneous dorsum of E16.5 (scarless) and E18.5 (scarring) mouse embryos.

Early in utero, but not in postnatal life, cutaneous wounds undergo regeneration and heal without formation of a scar. Scarless fetal wound healing occurs ...

miRNA Expression Analyses in Prostate Cancer Clinical Tissues

A critical challenge in prostate cancer (PCa) clinical management is posed by the inadequacy of currently used biomarkers for disease screening, diagnosis, prognosis and treatment. In recent years, microRNAs (miRNAs) have emerged as promising alternate biomarkers for prostate cancer diagnosis and prognosis. However, the development of miRNAs as effective biomarkers for prostate cancer heavily relies on their accurate detection in clinical tissues. miRNA analyses in prostate cancer clinical specimens is often challenging owing to tumor heterogeneity, sampling errors, stromal contamination etc. The goal of this article is to describe a simplified workflow for miRNA analyses in archived FFPE or fresh frozen prostate cancer clinical specimens using a combination of quantitative real-time PCR (RT-PCR) and in situ hybridization (ISH). Within this workflow, we optimize the existing methodologies for miRNA extraction from FFPE and frozen prostate tissues and expression analyses by Taqman-probe based miRNA RT-PCR. In addition, we describe an optimized method for ISH analyses formiRNA detection in prostate tissues using locked nucleic acid (LNA)- based probes. Our optimized miRNA ISH protocol can be applied to prostate cancer tissue slides or prostate cancer tissue microarrays (TMA).

Here we describe a simplified protocol for microRNA (miRNA) expression analyses in archived Formalin-Fixed, Paraffin-Embedded (FFPE) or fresh frozen prostate cancer (PCa) clinical tissues employing quantitative real-time PCR (RT-PCR) and in situ hybridization (ISH).

A critical challenge in prostate cancer (PCa) clinical management is posed by the inadequacy of currently used biomarkers for disease screening, ...

A Method of Trigonometric Modelling of Seasonal Variation Demonstrated with Multiple Sclerosis Relapse Data

This report describes a novel Stata-based application of trigonometric regression modelling to 55 years of multiple sclerosis relapse data from 46 clinical centers across 20 countries located in both hemispheres. Central to the success of this method was the strategic use of plot analysis to guide and corroborate the statistical regression modelling. Initial plot analysis was necessary for establishing realistic hypotheses regarding the presence and structural form of seasonal and latitudinal influences on relapse probability and then testing the performance of the resultant models. Trigonometric regression was then necessary to quantify these relationships, adjust for important confounders and provide a measure of certainty as to how plausible these associations were. Synchronization of graphing techniques with regression modelling permitted a systematic refinement of models until best-fit convergence was achieved, enabling novel inferences to be made regarding the independent influence of both season and latitude in predicting relapse onset timing in MS. These methods have the potential for application across other complex disease and epidemiological phenomena suspected or known to vary systematically with season and/or geographic location.

Combining plot analysis with trigonometric regression is a robust method for exploring complex, cyclical phenomena such as relapse onset timing in multiple sclerosis (MS). This method enabled unbiased characterisation of seasonal trends in relapse onset permitting novel inferences around the influence of seasonal variation, ultraviolet radiation (UVR) and latitude.

This report describes a novel Stata-based application of trigonometric regression modelling to  55 years of multiple sclerosis relapse data from 46 ...

Cutaneous Surgical Denervation:  A Method for Testing the Requirement for Nerves in Mouse Models of Skin Disease

Cutaneous somatosensory nerves function to detect diverse stimuli that act upon the skin. In addition to their established sensory roles, recent studies have suggested that nerves may also modulate skin disorders including atopic dermatitis, psoriasis and cancer. Here, we describe protocols for testing the requirement for nerves in maintaining a cutaneous mechanosensory organ, the touch dome (TD). Specifically, we discuss methods for genetically labeling, harvesting and visualizing TDs by whole-mount staining, and for performing unilateral surgical denervation on mouse dorsal back skin. Together, these approaches can be used to directly compare TD morphology and gene expression in denervated as well as sham-operated skin from the same animal. These methods can also be readily adapted to examine the requirement for nerves in mouse models of skin pathology. Finally, the ability to repeatedly sample the skin provides an opportunity to monitor disease progression at different stages and times after initiation.

This article includes detailed protocols for genetic labeling of mouse skin, surgical denervation, skin biopsy and visualizing labeled epithelia by whole-mount &#946;-galactosidase staining. These methods can be used to test the requirement for nerves in mouse models of normal and pathological skin.

Cutaneous somatosensory nerves function to detect diverse stimuli that act upon the skin. In addition to their established sensory roles, recent studies ...

Assessment of Child Anthropometry in a Large Epidemiologic Study

A high proportion of children have overweight and obesity in the United States and other countries. Accurate assessment of anthropometry is essential to understand health effects of child growth and adiposity. Gold standard methods of measuring adiposity, such as dual X-ray absorptiometry (DXA), may not be feasible in large field studies. Research staff can, however, complete anthropometric measurements, such as body circumferences and skinfold measurements, using inexpensive portable equipment. In this protocol we detail how to obtain manual anthropometric measurements from children, including standing and sitting height, weight, waist circumference, hip circumference, mid-upper arm circumference, triceps skinfold thickness, and subscapular skinfold thickness, and procedures to assess the quality of these measurements. To demonstrate accuracy of these measurements, among 1,110 school-aged children in the pre-birth cohort Project Viva we calculated Spearman correlation coefficients comparing manual anthropometric measurements with a gold standard measure of body fat, DXA fat mass1. To address reliability, we evaluate intra-rater technical error of measurement at a quality control session conducted on adult female volunteers.

In epidemiologic studies of children, well-trained research staff can accurately and precisely assess weight, height, sitting height, skinfold thicknesses, and body circumferences.

A high proportion of children have overweight and obesity in the United States and other countries. Accurate assessment of anthropometry is essential to ...