Abstract 4009: Comparative microRNA profiling of prostate carcinomas with increasing tumor stage by deep-sequencing

Abstract

Abstract Background: MicroRNAs (miRNAs) are short, non-coding RNAs that post-transcriptionally regulate gene expression and play an important role in tumorigenesis. Previous deep-sequencing identified the microRNA profile of prostate carcinoma (PCa) vs. non-malignant prostate tissue. As an extension of our recent analyses, we now compared organ-confined prostate tumors (pT2), tumors with extra capsular growth (pT3, pN0), and lymph node metastasizing (pN1) PCa relative to corresponding non-malignant prostate tissue and healthy prostate tissue. Material and Methods: We performed comparative miRNA expression profiling using deep sequencing of cDNA libraries. Potential target genes of deregulated miRNAs were identified by database analysis and subsequently validated in vitro using reporter gene constructs. miRNA and mRNA expression was determined using quantitative real-time PCR. Results: The miRNA expression from the healthy and non-malignant tissue is consistent with our previous findings, indicating a high fidelity of the method employed. Some miRNAs (miR-375, miR-148a, miR-141 and miR-21) are expressed at increasing levels with increasing tumor stage, while other miRNAs (miR-200b/c, miR-25, miR-17 or miR-93) are up-regulated only from organ-confined tumors (pT2) to tumors with extra-capsular growth (pT3) but then expressed at lower levels after the transition to lymph node metastasizing tumors (pN0 vs. pN1). The same trend was seen in qRT-PCR analysis but due to the limited sample number, no significance was reached. Interestingly, miR-375, found to be up-regulated in tumor vs. normal tissue, and miR-15a, found induced by sequencing in T2 and T3 tumors but not in lymph node metastasizing tumors, target the phosphatases PHLPP1 and PHLPP2, respectively. PHLPP1 and PHLPP2 dephosphorylate members of the AKT-family of signal transducers thereby inhibiting cell growth. Co-expression of miR-15a and miR-375 resulted in down-regulation of PHLPP1/2 and a strongly increased PCa cell growth. Conclusion: miRNA profiling of pT2 (pN0), pT3 (pN0), and lymph node metastasizing prostate carcinoma (pN1) by deep sequencing revealed clearly changed miRNA levels. Citation Format: Elke Nolte, Martin Hart, Sven Wach, Jaroslaw Szczyrba, Helge Taubert, Tilman Rau, Arndt Hartmann, Friedrich A. Grässer, Bernd Wullich. Comparative microRNA profiling of prostate carcinomas with increasing tumor stage by deep-sequencing. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4009. doi:10.1158/1538-7445.AM2015-4009