The authors are thankful to G. Q. Daley for providing the BaF3 and WEHI cells and T. Reya for the MSCV-BCR-ABL-Ires-YFP constructs. The authors are thankful to M. Carroll for providing the patient samples from the CML blast crisis. This study was supported by grants to M.A. from the NCI (1RO1CA155091), the Leukemia Research Foundation and V Foundation, and from the NHLBI (R21HL114074-01).

All animal experiments were carried out according to the guidelines of the Institutional Animal Care and Use Committee (IACUC) at Cincinnati Children&#39;s Hospital Medical Center (CCHMC). Human specimens (Normal BM and that from CML (p210-BCR-ABL+) leukemia) were obtained through Institutional Review Board-approved protocols (Institutional Review Board: Federalwide Assurance #00002988 Cincinnati Children&#39;s Hospital Medical Center) and donor-informed consent from CCHMC and the University of Cincinnati.
<p class="...

<ol>
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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=Human+chronic+myeloid+leukemia+stem+cells+are+insensitive+to+imatinib+despite+inhibition+of+BCR-ABL+activity.">Human chronic myeloid leukemia stem cells are insensitive to imatinib despite inhibition of BCR-ABL activity.</a> The Journal of Clinical Investigation. 121, 396-409 (2011).</li><li>Straussman, R., 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=Tumour+micro-environment+elicits+innate+resistance+to+RAF+inhibitors+through+HGF+secretion.">Tumour micro-environment elicits innate resistance to RAF inhibitors through HGF secretion.</a> Nature. 487, 500-504 (2012).</li><li>Wilson, T. 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For the bulk of cancer cells, the therapeutic response to TKI is mediated by a blockade of tyrosine-kinase-oncoprotein signals to which the tumor is addicted. However, relatively little is known about how a minority of cancer cells contributing to MRD escape the oncogene dependence and therapy4. Recent studies revealed that growth factor signaling mediates drug resistance in both leukemia and solid organ tumors. This suggests that various molecular mechanisms might underlie intrinsic resistance<su...

Constitutive tyrosine kinase activity of BCR-ABL1 fusion oncogene causes CML, which provides a rationale to target the kinase activity by small molecule inhibitors. The success of TKIs in treating CML patients revolutionized the concept of targeted therapy1,2. Subsequently, anti-kinase therapy as precision medicine was developed for several other malignancies, including solid tumors. So far, more than thirty kinase inhibitors have been approved by the United State FDA for treating various malignancies. While TKI treatment is very effective in suppressing the disease, it is not curative. Besides, a small population of cancer cells persists during the treatment: the MRD3,4,5. Even patients who showed complete remission are left with MRD, which eventually results in relapse if not continuously suppressed. Therefore, the eradication of MRD cells is needed to achieve a durable or curative response. CML represents a valuable paradigm for defining the concept of precision medicine, mechanisms of oncogenesis, rational target-directed therapeutics, disease progression, and drug resistance. However, even today, the mechanism driving TKI-induced cell death in cancer cells is not fully understood, nor why MRD cells (comprised of leukemic stem cells [LSCs]) are intrinsically resistant to TKIs4,6. Nonetheless, the phenomenon of &#34;oncogene dependence&#34; to mutant kinase oncoprotein is implicated in TKI efficacy where the acute inhibition of targeted oncogene by TKIs causes an oncogenic shock that leads to a massive proapoptotic response or quiescence in cell context-dependent manner6,7,8,9. However, the mechanistic underpinning of oncogene dependence is lacking. Recent studies have implicated that growth factor signaling abrogates oncogene dependence and consequently confers resistance to TKI therapy10,11,12. Therefore, to gain insight into the mechanism of oncogene dependence, we performed whole-genome expression profiling from BCR-ABL1 addicted and nonaddicted cells (grown with growth factors), which revealed that c-Fos and Dusp1 are critical mediators of oncogene addiction13. The genetic deletion of c-Fos and Dusp1 is synthetic lethal to BCR-ABL1-expressing cells and the mice used in the experiment did not develop leukemia. Moreover, the inhibition of c-Fos and DUSP1 by small molecule inhibitors cured BCR-ABL1-induced CML in mice. The results show that the expression levels of c-Fos and Dusp1 define the apoptotic threshold in cancer cells, such that lower levels confer drug sensitivity while higher levels cause resistance to therapy13.
To identify the genes driving the oncogene dependence, we performed several whole-genome expression profiling experiments in the presence of growth factor and a TKI (imatinib) using both mouse- and CML patient-derived cells (K562). These data were analyzed in parallel with CML patient data sets obtained from CD34+ hematopoietic stem cells before and after treatment with imatinib. This analysis revealed three genes (a transcription factor [c-Fos], dual specificity phosphatase 1 [Dusp1], and an RNA-binding protein [Zfp36]) which are commonly upregulated in TKI-resistant cells. To validate the significance of these genes in conferring drug resistance, we carried out step-by-step in vitro and in vivo analysis. The expression levels of these genes were confirmed by real-time qPCR (RT-qPCR) and western blotting in drug-resistant cells. Further, cDNA overexpression and knockdown by shRNA hairpins of c-Fos, Dusp1, and Zfp36 revealed that elevated c-Fos and Dusp1 expressions are sufficient and necessary to confer TKI resistance. Therefore, we performed an in vivo validation using mouse models with c-Fos and Dusp1 only. For the genetic validation of c-Fos and Dusp1, we created ROSACreERT-inducible c-Fosfl/fl mice (conditional knockout)14 and crossed them with Dusp1-/- (straight knockout)15 to make ROSACreERT2-c-Fosfl/flDusp1-/- double-transgenic mice. Bone marrow-derived c-Kit+ cells (from c-Fosfl/fl-, Dusp1-/--, and c-Fosfl/flDusp1-/-) expressing BCR-ABL1 were analyzed in vitro in a colony-forming unit (CFU) assay, and in vivo by bone marrow transplantation in lethally irradiated mice, to test the requirement of c-Fos and Dusp1 alone or together in leukemia development. Likewise, the chemical inhibitions of c-Fos by DFC (difluorinated curcumin)16 and Dusp1 by BCI (benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one)17 were tested in vitro and in vivo using BCR-ABL1-expressing, bone marrow-derived c-Kit+ cells from the wild-type (WT) mouse. To confirm the requirement of c-Fos and Dusp1 in leukemic stem cells, we utilized a CML mouse model where BCR-ABL1 was specifically induced in its stem cells by doxycycline (Tet-transactivator expresses under murine stem cell leukemia (SCL) gene 3&#39; enhancer regulation)18,19. We used bone marrow Lin-Sca+c-Kit+ (LSK) cells from these mice in an in vivo transplant assay. Furthermore, we established phopsho-p38 levels and the expression of IL-6 as pharmaco-dynamic biomarkers for Dusp1 and c-Fos inhibition, respectively, in vivo. Finally, to extend the study for human relevance, patient-derived CD34+ cells (equivalent to the c-Kit+ cells from mice) were subjected to long-term in vitro culture-initiating cell assays (LTCIC) and an in vivo humanized mouse model of CML20,21. The immunodeficient mice were transplanted with CML CD34+ cells, followed by drug treatment and analysis of human leukemic cell survival.
In this project, we develop methods for target identification and validations using both genetic and chemical tools, using different preclinical models. These methods can be successfully applied to validate other targets developing chemical modalities for therapeutic development.

<table border="0" cellpadding="0" cellspacing="0" style="width:948px;" width="946">
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		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:424px;">Biological Materials</td>
			<td style="width:247px;"></td>
			<td style="width:147px;"></td>
			<td style="width:131px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RPMI</td>
			<td>Cellgro (corning)</td>
			<td>15-040-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMEM</td>
			<td>Cellgro (corning)</td>
			<td>15-013-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">IMDM</td>
			<td>Cellgro (corning)</td>
			<td>15-016-CVR</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RetroNectin Recombinant Human Fibronectin Fragment</td>
			<td>Takara</td>
			<td>T100B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MethoCult GF M3434 (Methylcellulose for Mouse CFU)</td>
			<td>Stem Cell</td>
			<td>3434</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MethoCult H4434 Classic (Methylcellulose for Human CFU)</td>
			<td>Stem Cell</td>
			<td>4434</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">4-Hydroxytamoxifen</td>
			<td>Sigma</td>
			<td>H6278</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Recombinant Murine SCF</td>
			<td>Prospec</td>
			<td>CYT-275</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Recombinant Murine Flt3-Ligand</td>
			<td>Prospec</td>
			<td>CYT-340</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Recombinant Murine IL-6</td>
			<td>Prospec</td>
			<td>CYT-350</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Recombinant Murine IL-7</td>
			<td>Peprotech</td>
			<td>217-17</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DFC</td>
			<td>LKT Laboratories Inc.</td>
			<td>D3420</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BCI</td>
			<td>Chemzon Scientific</td>
			<td>NZ-06-195</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Imatinib</td>
			<td>LC Laboratory</td>
			<td>I-5508</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Curcumin</td>
			<td>Sigma</td>
			<td>458-37-7</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NDGA</td>
			<td>Sigma</td>
			<td>500-38-9</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Penn/Strep</td>
			<td>Cellgro (corning)</td>
			<td>30-002-CI</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FBS</td>
			<td>Atlanta biological</td>
			<td>S11150</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypsin EDTA 1X</td>
			<td>Cellgro (corning)</td>
			<td>25-052-CI</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1XPBS</td>
			<td>Cellgro (corning)</td>
			<td>21-040-CV</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">L-Glutamine</td>
			<td>Cellgro (corning)</td>
			<td>25-005-CL</td>
			<td style="width:131px;">5mg/ml stock in water</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Puromycin</td>
			<td>Gibco (life technologies)</td>
			<td>A11138-03</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HEPES</td>
			<td>Sigma</td>
			<td>H7006</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Na2HPO4.7H2O</td>
			<td>Sigma</td>
			<td>S9390</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Protamine sulfate</td>
			<td>Sigma</td>
			<td>P3369</td>
			<td style="width:131px;">5mg/ml stock in water</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypan Blue solution (0.4%)</td>
			<td>Sigma</td>
			<td>T8154</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMSO</td>
			<td>Cellgro (corning)</td>
			<td>25-950-CQC</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">WST-1</td>
			<td>Roche</td>
			<td>11644807001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">0.45uM acro disc filter</td>
			<td>PALL</td>
			<td>2016-10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">70um nylon cell stariner</td>
			<td>Becton Dickinson</td>
			<td>352350</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FICOL (Histopaque 1083) (polysucrose)</td>
			<td>Simga</td>
			<td>1083</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PBS</td>
			<td>Corning</td>
			<td>21040CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">LS Columns</td>
			<td>Miltenyi</td>
			<td>130-042-401</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Protease Inhibitor Cocktail</td>
			<td>Roche</td>
			<td>CO-RO</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphatase Inhibitor Cocktail 2</td>
			<td>Sigma</td>
			<td>P5762</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nitrocullulose Membrane</td>
			<td>Bio-Rad</td>
			<td>1620115</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:424px;">SuperSignal West Dura Extended Duration Substrate ( chemiluminiscence substrate)</td>
			<td>Thermo Scientific</td>
			<td>34075</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CD5</td>
			<td>eBioscience</td>
			<td>13-0051-82</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CD11b</td>
			<td>eBioscience</td>
			<td>13-0112-75</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CD45R (B220)</td>
			<td>BD biosciences</td>
			<td>553092</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CD45.1-FITC</td>
			<td>eBioscience</td>
			<td>11-0453-85</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CD45.2-PE</td>
			<td>eBioscience</td>
			<td>12-0454-83</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">hCD45-FITC</td>
			<td>BD Biosciences</td>
			<td>555482</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-Biotin-FITC</td>
			<td>Miltenyi</td>
			<td>130-090-857&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-7-4</td>
			<td>eBioscience</td>
			<td>MA5-16539</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-Gr-1 (Ly-6G/c)</td>
			<td>eBioscience</td>
			<td>13-5931-82</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-Ter-119</td>
			<td>eBioscience</td>
			<td>13-5921-75</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ly-6 A/E (Sca1) PE Cy7</td>
			<td>BD&#160;</td>
			<td>558612</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CD117 APC&#160;</td>
			<td>BD&#160;</td>
			<td>553356</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BD Pharm Lyse</td>
			<td>BD&#160;</td>
			<td>555899</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BD Cytofix/Cytoperm (Fixing and permeabilization solution)</td>
			<td>BD&#160;</td>
			<td>554714</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:424px;">BD Perm/Wash&#160; (permeabilization and wash solution for phospho flow)</td>
			<td>BD&#160;</td>
			<td>554723</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">phospho p38</td>
			<td>Cell Signaling Technologies</td>
			<td>4511S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">total p38</td>
			<td>Cell Signaling Technologies</td>
			<td>9212</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse IgG control</td>
			<td>BD&#160;</td>
			<td>554121</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Alexa Flour 488 conjugated&#160;</td>
			<td>Invitrogen</td>
			<td>A-11034</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Calcium Chloride</td>
			<td>Invitrogen</td>
			<td>K278001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2X HBS</td>
			<td>Invitrogen</td>
			<td>K278002</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EDTA</td>
			<td>Ambion</td>
			<td>AM9261</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BSA</td>
			<td>Sigma</td>
			<td>A7906</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Blood Capillary Tubes</td>
			<td>Fisher</td>
			<td>22-260-950</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Blood Collection Tube</td>
			<td>Giene Bio-One</td>
			<td>450480</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Newborn Calf Serum</td>
			<td>Atlanta biological</td>
			<td>S11295</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Erythropoiein</td>
			<td>Amgen</td>
			<td>5513-267-10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">human SCF</td>
			<td>Prospec</td>
			<td>CYT-255</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Human IL-3</td>
			<td>Prospec</td>
			<td>CYT-210</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">G-SCF</td>
			<td>Prospec</td>
			<td>CYT-220</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">GM-CSF</td>
			<td>Prospec</td>
			<td>CYT-221</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MyeloCult (media for LTCIC assay)</td>
			<td>Stem Cell Technologies</td>
			<td>5100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hydrocortisone Sodium Hemisuccinate</td>
			<td>Stem Cell Technologies</td>
			<td>7904</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MEM alpha</td>
			<td>Gibco</td>
			<td>12561-056</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1/2cc Lo-Dose u-100 insulin syringe 28 G1/2</td>
			<td>Becton Dickinson</td>
			<td>329461</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mortor pestle</td>
			<td>Coor tek&#160;</td>
			<td>60316 and 60317</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Isoflorane (Isothesia TM)</td>
			<td>Butler Schien</td>
			<td>29405</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SOC</td>
			<td>New England Biolabs</td>
			<td>B90920s</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Ampicillin</td>
			<td>Sigma</td>
			<td>A0166</td>
			<td style="width:131px;">100mg/ml stock in water</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bacto agar (agar)</td>
			<td>Difco</td>
			<td>214050</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Terrific broth</td>
			<td>Becton Dickinson</td>
			<td>243820</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Agarose</td>
			<td>Genemate</td>
			<td>E-3119-500</td>
			<td></td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;">Doxycycline chow</td>
			<td>TestDiet.com</td>
			<td>52662</td>
			<td style="width:131px;">modified RMH1500, Autoclavable 5LK8&#160; with 0.0625% Doxycycline&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tamoxifen</td>
			<td>Sigma</td>
			<td>T5648</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Iodonitrotetrazolium chloride&#160;</td>
			<td>Sigma</td>
			<td>I10406</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Kits</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dneasy Blood &#38; tissue kit</td>
			<td>Qiagen</td>
			<td>69506</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">GoTaq Green (taq polymerase with Green loadign dye)</td>
			<td>Promega</td>
			<td>M1722</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">miRNeasy Mini Kit&#160; (RNA isolation kit)</td>
			<td>Qiagen</td>
			<td>217084</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DNA Free Dnase Kit (DNAse treatment for RT PCR)</td>
			<td>Ambion, Life Technologies</td>
			<td>AM1906</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:424px;">Superscript III First Strand Synthesis (reverse transcriptase for cDNA synthesis)</td>
			<td>Invitrogen</td>
			<td>18080051</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:424px;">SYBR Green (taq polymerase mix with green interchalating dye for qPCR)</td>
			<td>Bio-Rad</td>
			<td>1725270</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CD117 MicroBead Kit</td>
			<td>Miltenyi</td>
			<td>130-091-224</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Human Long-Term Culture Initiating Cell Assay</td>
			<td>Stemp Cell Technologies</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Instruments</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NAPCO series 8000 WJ CO2 incubator</td>
			<td>Thermo scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Swing bucket rotor cetrifuge 5810R</td>
			<td>Eppendorf</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TC-10 automated cell counter</td>
			<td>Bio-RAD</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">C-1000 Thermal cycler</td>
			<td>Bio-RAD</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mastercycler Real Plex 2</td>
			<td>Eppendorf</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:424px;">ChemiDoc Imaging System (imaging system for gels and western blots)</td>
			<td>Bio-RAD</td>
			<td>17001401</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hemavet ( boold counter)</td>
			<td>Drew-Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">LSR II ( FACS analyzer)</td>
			<td>BD&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fortessa I ( FACS analyzer)</td>
			<td>BD&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FACSAriaII ( FACS Sorter)</td>
			<td>BD&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Magnet Stand</td>
			<td>Miltenyi</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Irradiator</td>
			<td style="width:247px;">&#160;J.L. Shepherd and Associates, San Fernando CA</td>
			<td>Mark I Model 68A</td>
			<td>source Cs 137</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mice</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ROSACreERT2</td>
			<td>Jackson Laboratory</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Scl-tTA&#160;</td>
			<td>Dr. Claudia Huettner&#8217;s lab</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BoyJ&#160;</td>
			<td>mouse core facility at CCHMC</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">C57Bl/6&#160;</td>
			<td>Jackson Laboratory</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NSGS</td>
			<td>mouse core facility at CCHMC</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">ROSACreERT2/c-Fosfl/fl Dusp1-/-&#160;</td>
			<td>Made in house</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ROSACreERT2/c-Fosfl/fl</td>
			<td>Made in house</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cells</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">BaF3</td>
			<td style="width:247px;">Gift from George Daley, Harvard Medical School, Boston</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">WEHI</td>
			<td style="width:247px;">Gift from George Daley, Harvard Medical School, Boston</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">CML-CD34+ and Normal CD34+ cells</td>
			<td style="width:247px;">University Hospital, University of Cincinnati</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

methods for evaluating the role of c-fos and dusp1 in oncogene dependence

The demonstration of tyrosine kinase inhibitors (TKIs) in treating chronic myeloid leukemia (CML) has heralded a new era in cancer therapeutics. However, a small population of cells does not respond to TKI treatment, resulting in minimal residual disease (MRD); even the most potent TKIs fail to eradicate these cells. These MRD cells serve as a reservoir to develop resistance to therapy. Why TKI treatment is ineffective against MRD cells is not known. Growth factor signaling is implicated in supporting the survival of MRD cells during TKI treatment, but a mechanistic understanding is lacking. Recent studies demonstrated that an elevated c-Fos and Dusp1 expression as a result of convergent oncogenic and growth factor signaling in MRD cells mediate TKI resistance. The genetic and chemical inhibition of c-Fos and Dusp1 renders CML exquisitely sensitive to TKIs and cures CML in both genetic and humanized mouse models. We identified these target genes using multiple microarrays from TKI-sensitive and -resistant cells. Here, we provide methods for target validation using in vitro and in vivo mouse models. These methods can easily be applied to any target for genetic validation and therapeutic development.

Oncogene addiction has been implicated in the therapeutic efficacy of TKIs. However, the mechanisms driving the oncogene dependence are not understood. We performed multiple unbiased gene expression analyses to identify the genetic component involved in orchestrating the addiction. These analyses revealed the upregulation of three genes, c-Fos, Dusp1, and Zfp36, in cancer cells that are not dependent on oncogenic signaling for survival and, thus, are insensitive to TKI treatment. The down...

Watch this Scientific Journal Video about Methods for Evaluating the Role of c-Fos and Dusp1 in Oncogene Dependence at JoVE.com

Methods for Evaluating the Role of c-Fos and Dusp1 in Oncogene Dependence

Here, we describe protocols for the genetic and chemical validation of c-Fos and Dusp1 as a drug target in leukemia using in vitro and in vivo genetic and humanized mouse models. This method can be applied to any target for genetic validation and therapeutic development.

The demonstration of tyrosine kinase inhibitors (TKIs) in treating chronic myeloid leukemia (CML) has heralded a new era in cancer therapeutics. However, ...

This method can help answer key questions in cancer therapeutics fields, such as identification of key genes involved in oncogene dependence. The main advantage of this technique is that it utilizes the oncogene dependence that is common to many kinase driven cancers therefore it is applicable to multiple tumor types. Though this method can provide insight into leukemia, it can also be applied to other systems, like solid tumors such as lung cancer, brain tumors, and pancreatic tumors.Generally, individuals new to this method will struggle due to lack of experience in molecular biology and cellular physiology. To begin, harvest the leg bones from a euthanized mouse. Clean the tissues from the bones with a scalpel.Then place the bones in cold PBS on ice and crush the bones with a pestle. After this, filter the cell suspension through a 70 micrometer cell strainer into a 50 milliliter screw cap tube with a 10 milliliter pipette. Wash the mortar and pestle multiple times with cold PBS and add the cell suspension to the 50 milliliter tube.Next centrifuge the bone marrow and remove the supernatant with vacuum and glass pipette. Resuspend the cell pellet in 5 milliliters of PBS. Using a pipette, slowly add the suspended bone marrow to the top of room temperature poly-sucrose.After this, spin the poly-sucrose at 400 Gs for 20 minutes with the brake turned off. After centrifugation, collect the cloudy total mono-nuclear cell interface with a pipette and transfer it to a new 15 milliliter tube. Bring the volume to 10 milliliters with PBS and remove 20 microliters for counting.After centrifugation, discard the supernatant and place the pellet on ice. Next, resuspend the cell pellet in PBS with EDTA and BSA. Add CD117 microbeads to the cell suspension, and vortex to mix.After this, incubate the suspension for 10 minutes at 4 degrees Celsius. Then bring the volume up to 10 milliliters with more PBS with EDTA and BSA and centrifuge at 1200 G's at 4 degrees Celsius for 5 minutes. Use a vacuum to remove the supernatant and suspend the cell pellet in PBS with EDTA and BSA.Then add 3 milliliters of PBS with EDTA and BSA to a magnet stand with a magnetic column and allow it to flow into a collection tube. After the buffer finishes flowing through the column, add the cell suspension and allow it to flow through the column into the collection tube. Next add 5 more milliliters of PBS with EDTA and BSA to the column and flush it immediately with the plunger.Remove the plunger and repeat the flush before counting the cells. After centrifuging the cells, remove the supernatant and suspend the cell pellet in complete IMDM for culture. Culture the cells overnight at 37 degrees Celsius with 5%carbon dioxide.First, combine the retroviral plasmid DNA with the packaging plasmid, calcium chloride and water in a 1.5 milliliter tube. Then add 500 microliters of HBS to another 1.5 milliliter tube. Add the transfection mixture drop-wise to the tube containing HBS while simultaneously mixing with the vortexer set to the lowest setting.Incubate the transfection mixture at room temperature for 20 to 30 minutes. During the incubation period, add chloroquine to the HEK cells and keep them in the incubator. After adding the transfection mix, incubate the cells for 8 hours in a 37 degrees Celsius 5%CO2 incubator changing the cell media by adding 14 milliliters of fresh DMEM10 media very slowly.Pipetting slowly against the wall of the dish helps to prevent any stripping of HEK cells. Then incubate the cells overnight in the 37 degrees Celsius 5%CO2 incubator. Use a 10 milliliter syringe to collect the viral supernatant.Then attach a 0.45 micrometer syringe filter to the syringe. Plunge the viral supernatant into a new collection tube. Collect the viral supernatant approximately 16 hours later.After this, add two milliliters of recombinant human fibronectin fragment in PBS to untreated 6 well culture plates. The next day, use a pipette to remove the fibronectin from the plates. Block the plates with 2%BSA in PBS and incubate the plates at room temperature for 30 minutes.Use a vacuum to remove BSA and wash the plates with PBS before removing it with a vacuum. After this, immediately add the filtered viral supernatant and centrifuge the plate for two hours. Use a vacuum to remove the supernatant and spin the plate again.Next remove the supernatant with a vacuum and wash the viral coated wells with PBS. Remove the PBS with a vacuum, add the previously cultured c-Kip plus mouse cells to the viral coated wells. After centrifugation, incubate the cells at 37 degrees Celsius and 5%carbon dioxide.48 hours after transduction, pellet the cells via centrifugation and resuspend them in FACS buffer 1. First thaw the methyl cellulose with cytokines for mice at room temperature. Then aliquot 3 milliliters of methyl cellulose in a FACS tube.Add 100 microliters of the cell suspension with the appropriate inhibitors to 3 milliliters of methyl cellulose. Then vortex the suspension on high for 10 to 30 seconds. After most of the air bubbles escape, use a 1 milliliter syringe to plate 1 milliliter of the media in three replicate plates.Place the plates in a large Petri dish along with one open dish containing sterile water. Then cover the large Petri dish and incubate the cells at 37 degrees Celsius. Prepare iodonitrotetrazolium chloride stain by dissolving 10 milligrams of the iodonitrotetrazolium chloride in 10 milliliters of water.Filter sterilize the staining solution with a Luer lock syringe equipped with a 0.2 micrometer filter. In the tissue culture hood, add 100 microliters of the staining solution drop-wise around the CFU plate. Then incubate the plates overnight at 37 degrees Celsius in a cell culture incubator.Finally, after the colonies have turned a dark red brown color, use a white background in the sterile tissue culture hood to take photos of the stained CFU plate. In this protocol, multiple unbiased gene expression analyses were used to identify the genetic component that orchestrates oncogene addiction. To validate the role of c-Fos and and Dusp1 as the therapeutic target in leukemia, their overexpression was confirmed with cells expressing the BCR-ABL1 oncogene.Analysis via RT-qPCR and western blotting confirmed that both were induced by BCR-ABL1 and that their expression is augmented by growth factor IL-3. YFP plus expressing cells were sorted via FACS for further in vitro and in vivo assays. The results demonstrated that deletion of c-Fos and Dusp1 alone inhibited CFU numbers.Cells lacking both c-Fos and Dusp1 were significantly compromised in their ability to form colonies and Imatinib treatment wiped out all of the CFUs indicating that the loss of c-Fos and Dusp1 is synthetically lethal to BCR-ABL1 expression. After this development, this technique paved the way for researchers in the field of cancer to explore the genetic networks and genes driving oncogene dependence and how these genes affect their particular response in mouse models and human patients. Don't forget that working with retroviruses and patient samples can be extremely hazardous and safe laboratory practices should be observed while performing this procedure.

methods-for-evaluating-role-c-fos-dusp1-oncogene

Research

JoVE Journal

Cancer Research

8.1K vues.  Cincinnati Children's Hospital Medical Center. Cette méthode peut aider à répondre à des questions clés dans les domaines thérapeutiques du cancer, tels que l’identification des gènes clés impliqués dans la dépendance oncogène. Le principal avantage de cette technique est qu’elle utilise la dépendance oncogène qui est commune à beaucoup de cancers entraînés par kinase donc il est applicable aux types multiples de tumeur. Bien que cette méthode puisse fournir un aperçu de la leucémie, elle peut également être appli...