This work is supported by grants from (1) the National Key R&#38;D Program of China (2020YFE0201600); (2) the National Nature Science Foundation (81973877 and 82174408); (3) Shanghai Collaborative Innovation Center of Industrial Transformation of Hospital TCM Preparation; (4) Research Projects within Budget of Shanghai University of Traditional Chinese Medicine (2021LK047).
&#160;&#160;&#160;&#160;

See the Table of Materials for details of all materials, reagents, and instruments used in this protocol. Figure 1 shows the overall protocol for RNA FISH; Table 1 contains the composition of all solutions and Table 2 contains the primer sequences used in this protocol.
1. Probe preparation
<ol>
	<li>Identify and acquire the FASTA sequence of a target lncRNA of interest, for example, from GenBan...

FISH for Long Non-Coding RNA Localization in Human Osteosarcoma Cells

<ol>
	<li>Djebali, 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=Landscape+of+transcription+in+human+cells.">Landscape of transcription in human cells.</a> Nature. 489 (7414), 101-108 (2012).</li><li>Li, C. H., Chen, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insight+into+the+role+of+long+noncoding+RNA+in+cancer+development+and+progression.">Insight into the role of long noncoding RNA in cancer development and progression.</a> International Review of Cell and Molecular Biology. 326, 33-65 (2016).</li><li>Pan, 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=lncRNA+FBXL19-AS1+regulates+osteosarcoma+cell+proliferation,+migration+and+invasion+by+sponging+miR-346.">lncRNA FBXL19-AS1 regulates osteosarcoma cell proliferation, migration and invasion by sponging miR-346.</a> OncoTargets and Therapy. 11, 8409-8420 (2018).</li><li>Jia, D., Niu, Y., Li, D., Liu, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=lncRNA+C2dat1+promotes+cell+proliferation,+migration,+and+invasion+by+targeting+miR-34a-5p+in+osteosarcoma+cells.">lncRNA C2dat1 promotes cell proliferation, migration, and invasion by targeting miR-34a-5p in osteosarcoma cells.</a> Oncology Research. 26 (5), 753-764 (2018).</li><li>Liu, Y., Wang, D., Ji, Q., Yan, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=LncRNA+MATN1-AS1+for+prediction+of+prognosis+in+osteosarcoma+patients+and+its+cellular+function.">LncRNA MATN1-AS1 for prediction of prognosis in osteosarcoma patients and its cellular function.</a> Molecular Biotechnology. 64 (1), 66-74 (2022).</li><li>Luo, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+to+study+long+noncoding+RNA+biology+in+cancer.">Methods to study long noncoding RNA biology in cancer.</a> Advances in Experimental Medicine and Biology. 927, 69-107 (2016).</li><li>Zhao, 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=lncRNA+TUSC7+inhibits+osteosarcoma+progression+through+the+miR-181a/RASSF6+axis.">lncRNA TUSC7 inhibits osteosarcoma progression through the miR-181a/RASSF6 axis.</a> International Journal of Molecular Medicine. 47 (2), 583-594 (2021).</li><li>Tong, C. 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=LncRNA+RUSC1-AS1+promotes+osteosarcoma+progression+through+regulating+the+miR-340-5p+and+PI3K/AKT+pathway.">LncRNA RUSC1-AS1 promotes osteosarcoma progression through regulating the miR-340-5p and PI3K/AKT pathway.</a> Aging. 13 (16), 20116-20130 (2021).</li><li>Qi, X., 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=ceRNA+in+cancer:+possible+functions+and+clinical+implications.">ceRNA in cancer: possible functions and clinical implications.</a> Journal of Medical Genetics. 52 (10), 710-718 (2015).</li><li>Tripathi, V., Fei, J., Ha, T., Prasanth, K. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+fluorescence+in+situ+hybridization+in+cultured+mammalian+cells.">RNA fluorescence in situ hybridization in cultured mammalian cells.</a> Methods in Molecular Biology. 1206, 123-136 (2015).</li><li>Femino, A. M., Fay, F. S., Fogarty, K., Singer, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+single+RNA+transcripts+in+situ.">Visualization of single RNA transcripts in situ.</a> Science. 280 (5363), 585-590 (1998).</li><li>Thomsen, R., Nielsen, P. S., Jensen, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dramatically+improved+RNA+in+situ+hybridization+signals+using+LNA-modified+probes.">Dramatically improved RNA in situ hybridization signals using LNA-modified probes.</a> RNA. 11 (11), 1745-1748 (2005).</li><li>Player, A. N., Shen, L. P., Kenny, D., Antao, V. P., Kolberg, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-copy+gene+detection+using+branched+DNA+(bDNA)+in+situ+hybridization.">Single-copy gene detection using branched DNA (bDNA) in situ hybridization.</a> The Journal of Histochemistry and Cytochemistry. 49 (5), 603-612 (2001).</li><li>Hazra, R., Spector, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+visualization+of+RNA+transcripts+and+proteins+in+whole-mount+mouse+preimplantation+embryos+using+single-molecule+fluorescence+in+situ+hybridization+and+immunofluorescence+microscopy.">Simultaneous visualization of RNA transcripts and proteins in whole-mount mouse preimplantation embryos using single-molecule fluorescence in situ hybridization and immunofluorescence microscopy.</a> Frontiers in Cell and Developmental Biology. 10, 986261 (2022).</li><li>Xu, 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=lncRNA+SNHG6+regulates+EZH2+expression+by+sponging+miR-26a/b+and+miR-214+in+colorectal+cancer.">lncRNA SNHG6 regulates EZH2 expression by sponging miR-26a/b and miR-214 in colorectal cancer.</a> Journal of Hematology &amp; Oncology. 12 (1), 3 (2019).</li><li>Yan, K., Tian, J., Shi, W., Xia, H., Zhu, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=LncRNA+SNHG6+is+associated+with+poor+prognosis+of+gastric+cancer+and+promotes+cell+proliferation+and+EMT+through+epigenetically+silencing+p27+and+sponging+miR-101-3p.">LncRNA SNHG6 is associated with poor prognosis of gastric cancer and promotes cell proliferation and EMT through epigenetically silencing p27 and sponging miR-101-3p.</a> Cellular Physiology and Biochemistry: International Journal of Experimental Cellular Physiology, Biochemistry, and Pharmacology. 42 (3), 999-1012 (2017).</li><li>Zhu, X., Yang, G., Xu, J., Zhang, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Silencing+of+SNHG6+induced+cell+autophagy+by+targeting+miR-26a-5p/ULK1+signaling+pathway+in+human+osteosarcoma.">Silencing of SNHG6 induced cell autophagy by targeting miR-26a-5p/ULK1 signaling pathway in human osteosarcoma.</a> Cancer Cell International. 19, 82 (2019).</li><li>Birgani, M. 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=Long+non-coding+RNA+SNHG6+as+a+potential+biomarker+for+hepatocellular+carcinoma.">Long non-coding RNA SNHG6 as a potential biomarker for hepatocellular carcinoma.</a> Pathology Oncology Research: POR. 24 (2), 329-337 (2018).</li><li>Nielsen, B. 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=Detection+of+lncRNA+by+LNA-based+in+situ+hybridization+in+paraffin-embedded+cancer+cell+spheroids.">Detection of lncRNA by LNA-based in situ hybridization in paraffin-embedded cancer cell spheroids.</a> Methods in Molecular Biology. 2348, 123-137 (2021).</li><li>Li, 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=Long+noncoding+RNA+SNHG6+regulates+p21+expression+via+activation+of+the+JNK+pathway+and+regulation+of+EZH2+in+gastric+cancer+cells.">Long noncoding RNA SNHG6 regulates p21 expression via activation of the JNK pathway and regulation of EZH2 in gastric cancer cells.</a> Life Sciences. 208, 295-304 (2018).</li><li>Traylor-Knowles, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+hybridization+techniques+for+paraffin-embedded+adult+coral+samples.">In situ hybridization techniques for paraffin-embedded adult coral samples.</a> Journal of Visualized Experiments: JoVE. (138), e57853 (2018).</li><li>Wang, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+molecule+RNA+FISH+(smFISH)+in+whole-mount+mouse+embryonic+organs.">Single molecule RNA FISH (smFISH) in whole-mount mouse embryonic organs.</a> Current Protocols in Cell Biology. 83 (1), 79 (2019).</li></ol>

This RNA FISH protocol can not only detect the localization of lncRNAs in cells, but also detect the colocalization of other RNAs, DNA, or proteins in cells, which can also be used to detect the location of lncRNAs in paraffin-embedded tissues. However, the specific protocol in such cases is different because the paraffin-embedded tissues need to be dewaxed21. This experimental procedure can be applied in 48- or 96-well plates, but 384-well plates are too small to be used here.
<p class="jove_...

Our understanding of the human genome has been greatly expanded by recent advances in whole-genome technology. About 93% of the human genome can be transcribed into RNAs, but only 2% of the RNAs can be translated into proteins; the remaining 98% of RNAs that have no protein translation function are called non-coding RNA (ncRNA)1. As a class of noncoding RNAs (ncRNAs), long ncRNAs (lncRNAs), containing over 200 nucleotides2, have attracted increasing attention due to their involvement in many physiological and pathological processes of the cells, such as differentiation, cycle control, apoptosis, migration, and invasion3,4,5. LncRNAs play their roles through various mechanisms, such as regulating chromatin structure and nuclear gene expression, controlling the mRNA splicing process, and posttranscriptional modification6. LncRNAs regulate the occurrence, development, and metastasis of malignancies at both the transcriptional and posttranscriptional levels. Transcriptional regulation is realized in the nucleus by affecting RNA transcription via binding to the chromosomal structures, while posttranscriptional regulation is realized in the cytoplasm by controlling the target genes via an endogenous competitive RNA (ceRNA) mechanism5, 7, 8. CeRNA has revealed a new mechanism of RNA interaction, namely that lncRNAs can act as a sponge to adsorb miRNAs and inhibit the miRNA-mediated degradation of related target genes9. Therefore, the information regarding the subcellular localization of lncRNAs, whether a specific lncRNA is located in the cytoplasm or nucleus, is important to help identify their biological functions.
At present, lncRNA localization is mainly detected by two methods, one is by nucleus/cytoplasm fraction isolation assay, and the other is by RNA FISH. In the former, RNAs in the cytoplasmic and the nuclear fractions are extracted respectively, and then PCR amplification is performed with specific lncRNA primers to detect the ratio of lncRNAs in the cytoplasm and nucleus. The advantage of this method is time efficiency, while the disadvantage is that the actual lncRNA localization is not directly reflected by the relative proportion of lncRNAs in the cytoplasm and nucleus. RNA FISH can detect lncRNA localization in cells through the design of lncRNA-specific antisense chain sequences followed by labeling with fluorescent dyes10. The RNA FISH methods have been improved with advances in probe techniques and detection methods, including fluorophore-labeled multiple oligo probe sets11, LNA probes12, and branched-DNA (bDNA) probes13. RNA FISH can not only detect the localization of lncRNA, but also detect the colocalization of other RNAs, DNA, or proteins by using double-color or multicolor immunofluorescence14.
In this work, we have included the detailed intracellular localization detection protocol of lncRNA small nucleolar RNA host gene 6 (SNHG6) in osteosarcoma cells (143B) by RNA FISH as an example. SNHG6 is a 600-730 nucleotide lncRNA in its mature spliced form and identified as a novel oncogene in diverse human cancers, including colorectal cancer, gastric cancer, ovarian clear cell carcinoma, osteosarcoma, and hepatocellular carcinoma15,16,17,18. Studies have confirmed the involvement of SNHG6 in biological behaviors of cancer cells, such as proliferation, EMT, and autophagy, and shown the cytoplasmic localization of SNHG6 where it may affect the target genes by binding (sponging) the miRNAs15,16,17. This detailed detection protocol of SNHG6 intracellular localization by RNA FISH is presented herein.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Automatic cell counter</td>
			<td>Shanghai Simo Biological Technology Co., Ltd</td>
			<td>IC1000</td>
			<td>Counting cells</td>
		</tr>
		<tr>
			<td>Cell culture plate-12</td>
			<td>Shanghai YueNian Biotechnology Co., Ltd</td>
			<td>3513,corning</td>
			<td>Place the coverslips in the plate</td>
		</tr>
		<tr>
			<td>&#160;Cell line (143B)</td>
			<td>Cell Bank of Chinese Academy of Sciences</td>
			<td>CRL-8303</td>
			<td>osteosarcoma cancer cell line</td>
		</tr>
		<tr>
			<td>Centrifuge tube (15 mL, 50 mL)</td>
			<td>Shanghai YueNian Biotechnology Co., Ltd</td>
			<td>&#160;430790, Corning</td>
			<td>Centrifuge the cells</td>
		</tr>
		<tr>
			<td>Coverslips</td>
			<td>Shanghai YueNian Biotechnology Co., Ltd</td>
			<td>abs7026</td>
			<td>The cells are seeded on the coverslips</td>
		</tr>
		<tr>
			<td>Cy3 label-SNHG6 DNA probe</td>
			<td>Shanghai GenePharma Co.,Ltd</td>
			<td>A10005</td>
			<td>Detect SNHG6 location</td>
		</tr>
		<tr>
			<td>DMEM media</td>
			<td>Shanghai YueNian Biotechnology Co., Ltd</td>
			<td>LM-E1141</td>
			<td>Cell culture medium</td>
		</tr>
		<tr>
			<td>Dry Bath Incubator</td>
			<td>Haimen Kylin-Bell Lab Instruments Co.,Ltd.</td>
			<td>DKT200-2&#160;</td>
			<td>Incubation at different high temperatures</td>
		</tr>
		<tr>
			<td>Ethanol 100%&#160;</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>10009218</td>
			<td>dehydration</td>
		</tr>
		<tr>
			<td>Fluorescence microscope</td>
			<td>Shanghai Waihai Biotechnology Co., LTD</td>
			<td>Olympus BX43 equipped with a camera of Olympus U-TV0.5XC-3(SN:5J01719),olympus</td>
			<td>Observation and positioning</td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>Shanghai Yiheng Scientific Instrument Co., LTD</td>
			<td>DHP-9051</td>
			<td>The samples were incubated at 37 &#176;C.</td>
		</tr>
		<tr>
			<td>Mounting Medium</td>
			<td>Sangon Biotech (Shanghai) Co., Ltd.</td>
			<td>E675004</td>
			<td>Attach the coverslips to the slide</td>
		</tr>
		<tr>
			<td>Shaker</td>
			<td>Haimen Kylin-Bell Lab Instruments Co.,Ltd.</td>
			<td>TS-8S</td>
			<td>Washing sample</td>
		</tr>
		<tr>
			<td>Slide</td>
			<td>Shanghai YueNian Biotechnology Co., Ltd</td>
			<td>188105</td>
			<td>The coverslips is placed on the slide</td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sangon Biotech (Shanghai) Co., Ltd.</td>
			<td>A600198</td>
			<td>Permeable membrane and nuclear membrane</td>
		</tr>
		<tr>
			<td>&#160;Trypsin (0.25%)</td>
			<td>Shanghai YueNian Biotechnology Co., Ltd</td>
			<td>25200056, Gibco</td>
			<td>trypsin treatment of cells</td>
		</tr>
		<tr>
			<td>Tween-20</td>
			<td>Sangon Biotech (Shanghai) Co., Ltd.</td>
			<td>A600560</td>
			<td>detergent</td>
		</tr>
	</tbody>
</table>

rna fluorescence in situ hybridization for long non-coding rna localization in human osteosarcoma cells

The important roles of long non-coding RNAs (lncRNAs) in cancer have been studied, such as regulating the proliferation, epithelial-mesenchymal transition (EMT), migration, infiltration, and autophagy of cancer cells. Localization detection of lncRNAs in cells can provide insight into their functions. By designing the lncRNA-specific antisense chain sequence followed by labeling with fluorescent dyes, RNA fluorescence in situ hybridization (FISH) can be applied to detect the cellular localization of lncRNAs. Together with the development of microscopy, the RNA FISH techniques now even allow for visualization of the poorly expressed lncRNAs. This method can not only detect the localization of lncRNAs alone, but also detect the colocalization of other RNAs, DNA, or proteins by using double-color or multicolor immunofluorescence. Here, we have included the detailed experimental operation procedure and precautions of RNA FISH by using lncRNA small nucleolar RNA host gene 6 (SNHG6) in human osteosarcoma cells (143B) as an example, to provide a reference for researchers who want to perform RNA FISH experiments, especially lncRNA FISH.

Author Spotlight: RNA FISH for Locating lncRNA-SNHG6 in Osteosarcoma Cells 

RNA Fluorescence In Situ Hybridization for Long Non-Coding RNA Localization in Human Osteosarcoma Cells

The scope of our research is to provide a detailed RNA FISH protocol that's providing a reference for scientists who want to perform RNA FISH experiments. Our research has established that RNA FISH can be used to localize lncRNA in human osteosarcoma cells. Our protocol provided a comprehensive experimental procedure and the precautions for RNA FISH using lncRNA-SNHG6 in human osteosarcoma cells as a reference.

Representative images of SNHG6 FISH in human osteosarcoma cells are shown (Figure 2). The negative control is treated with the negative Ctrl probe; positive control is treated with U6 probe 20. SNHG6 probe and U6 probe are labeled with Cy3, which emits red fluorescence. DAPI is a dye that stains the DNA, which emits blue fluorescence. This result shows that SNHG6 is mainly localized in the cytoplasm, and this information can provide an important direction for further ...

Watch this Scientific Journal Video about RNA FISH for Locating lncRNA-SNHG6 in Osteosarcoma Cells at JoVE.com

The present protocol describes a method of RNA fluorescence in situ hybridization to localize the lncRNAs in human osteosarcoma cells.

The important roles of long non-coding RNAs (lncRNAs) in cancer have been studied, such as regulating the proliferation, epithelial-mesenchymal transition ...