Prostate cancer is the most common cancer in men in the western world. Although early stage prostate cancer is treatable late stage, more specifically, metastatic and drug resistant prostate cancers are mostly incurable. The failure of current treatments obligates the research community to explore novel areas in prostate cancer biology and find better therapeutic targets. Emerging evidences show that non-coding RNAs specifically long non-coding RNAs (lncRNAs) play regulatory roles in various cellular processes and are frequently dysregulated in cancer including prostate cancer. These aberrantly expressed lncRNAs mostly with unexplored genetic information may drive cancer progression. Previous studies done in our laboratory showed a tumor suppressor role of a cluster of small non-coding RNAs or microRNA (miRNA) miR-17-92a in PC-3 prostate cancer cells. To learn the underlying mechanism, transcriptome analysis with or without expression of miR-17-92a was conducted in our laboratory. RNA-sequencing data analysis identified reduced expression of a set of lncRNAs and oncogenes, and up regulation of several tumor suppressor genes upon expression of miR-17-92a cluster miRNAs. One of the down regulated intergenic lncRNAs, PAINT (Prostate Cancer Associated Intergenic Non-coding Transcript) (LINC00888), was selected for determining its functional role in prostate cancer. TCGA and GEO profiles analyses revealed up regulation of PAINT in prostate tumors with higher Gleason Scores, in highly aggressive metastatic prostate cancer cell lines, and upon androgen deprivation therapy of prostate cancer cells. This observation was supported by our studies on expression analysis of PAINT in prostate tumor tissues using RNA in-situ hybridization in tissue microarrays (TMA) containing tissues from different stages of prostate cancer and normal prostate tissues, which showed higher expression of PAINT in prostate cancer tissues compared to normal tissues. Furthermore, late stage (stage III and stage IV) prostate tumors showed significant overexpression of PAINT compared to early stage (stage II) prostate cancer tissues. We examined the functional relevance of PAINT in promoting tumor progression next using different prostate cancer cell lines. Silencing of PAINT using siRNAs showed decreased cell proliferation, reduced S-phase progression and activation of pro-apoptotic proteins PARP and Caspase-3. Silencing of PAINT also showed decreased cell migration and increased expression of the epithelial marker, E-cadherin while reduced expression of mesenchymal markers Slug and Vimentin. Ectopic expression of PAINT reversed the effects observed upon silencing of PAINT. Increased cell proliferation, cell cycle progression and cell migration were noted in prostate cancer cells overexpressing PAINT. Additionally, cancer promoting phenotype such as larger colony formation and higher expression of mesenchymal marker Slug, was detected upon overexpression of PAINT. Our study also determined the therapeutic benefit of inhibition of expression showing an increased sensitivity of metastatic prostate cancer cells to the chemotherapeutic agent docetaxel (DTX) and selective Aurora kinase inhibitor VX-680. Taken together, our study establishes an oncogenic function of PAINT, its clinical relevance as a marker for advanced stage prostate cancer and its potential as a therapeutic target for metastatic prostate cancer.
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Master of Science (M.S.)
College of Medicine
Length of Campus-only Access
Masters Thesis (Campus-only Access)
Hasan, Md Faqrul, "Identification and Functional Characterization of a Long Non-coding RNA associated with Prostate Cancer" (2019). Electronic Theses and Dissertations. 6384.