We propose that a novel cluster of microRNAs (miRNAs) in the most frequently deleted genomic region associated with prostate cancer (PCa) repress epithelial-mesenchymal transition (EMT) and PCa progression and metastasis. EMT, a complex cellular program whereby epithelial tumor cells lose their epithelial polarity and gain mesenchymal phenotypes, is considered a critical step in invasion and metastases. The role of miRNAs in prostate cancer EMT and metastasis is largely unknown. We first identified that miR-203 represses EMT and PCa metastasis by directly targeting ZEB2 and other EMT regulators. Our recent data suggests that a cluster of miRNA genes on chromosome 8p21 (miR-3622a, 3622b, 4287, 4288) act as critical negative regulators of EMT in PCa. Loss of chromosome 8p21 is a frequent alteration in the prostate oncogenome, particularly in advanced PCa suggesting its role in PCa progression. It has been postulated that this region harbors alternative tumor suppressor genes, the identity of which have largely remained elusive. We have identified a cluster of novel miRNA genes (miR-3622a, 3622b, 4287, 4288) that are located in this region that have never been explored. Our analysis suggests that these miRNAs regulate EMT and PCa progression and metastasis by directly targeting key EMT regulators including the SNAIL and ZEB family of transcription factors. In view of this, we propose that a cluster of miRNA genes at the frequently deleted chromosome 8p21 region function coordinately to repress the EMT program by directly targeting EMT inducing factors, thereby preventing prostate cancer progression and metastasis. We hypothesize that these miRNAs inhibit EMT by maintaining the epithelial phenotype through a direct inhibition of transcriptional repressors of E-cadherin including members of the SNAIL and ZEB family and thereby inhibit PCa progression and metastasis. We will test this hypothesis, under the following specific aims - Specific Aim I: Investigate the role of proposed miRNAs in frequently deleted genomic region in regulation of EMT and PCa progression and metastasis using both in vitro and in vivo models.
Specific Aim II : Determine whether expression profiling of proposed EMT-regulating miRNAs in chromosome 8p21 region have associated prognostic and diagnostic potential in prostate cancer.
Specific Aim III : Investigate the molecular basis of repression of EMT regulating miRNAs in prostate cancer. This project is highly novel and significant as it will potentially integrate the impact of common genomic deletions observed in prostate cancer with the EMT and metastatic program, an aspect that has never been explored. In particular, characterization of miRNA genes at chromosome 8p21 region will be a highly significant step forward in the field of prostate cancer Accomplishment of this project will uncover novel miRNA-mediated molecular pathways that drive PCa progression and metastasis with potential clinical implications in design of better prognostic and therapeutic strategies for advanced prostate cancer.

Public Health Relevance

The main goal of this project is to define the role of novel microRNA genes located at frequently deleted genomic region in EMT and prostate cancer progression and metastasis. We hypothesize that a cluster of microRNA genes in the frequently deleted loci associated with prostate cancer coordinately repress the EMT program by direct targeting of transcriptional repressors of E-cadherin, including members of the SNAIL and ZEB family, thereby inhibiting prostate cancer progression and metastasis. This project is highly novel and significant and will examine the impact of common genomic deletions that have been consistently reported in prostate cancer with the EMT and metastatic programs. This project will potentially identify novel 'anti- metastatic'microRNAs as targets for therapeutic intervention in prostate cancer.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Tumor Progression and Metastasis Study Section (TPM)
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Mckee, Tawnya C
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Northern California Institute Research & Education
San Francisco
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Bhagirath, Divya; Yang, Thao Ly; Bucay, Nathan et al. (2018) microRNA-1246 Is an Exosomal Biomarker for Aggressive Prostate Cancer. Cancer Res 78:1833-1844
Bucay, N; Sekhon, K; Yang, T et al. (2017) MicroRNA-383 located in frequently deleted chromosomal locus 8p22 regulates CD44 in prostate cancer. Oncogene 36:2667-2679
Bucay, Nathan; Bhagirath, Divya; Sekhon, Kirandeep et al. (2017) A novel microRNA regulator of prostate cancer epithelial-mesenchymal transition. Cell Death Differ 24:1263-1274
Saini, Sharanjot (2016) PSA and beyond: alternative prostate cancer biomarkers. Cell Oncol (Dordr) 39:97-106
Bucay, Nathan; Sekhon, Kirandeep; Majid, Shahana et al. (2016) Novel tumor suppressor microRNA at frequently deleted chromosomal region 8p21 regulates epidermal growth factor receptor in prostate cancer. Oncotarget 7:70388-70403
Sekhon, Kirandeep; Bucay, Nathan; Majid, Shahana et al. (2016) MicroRNAs and epithelial-mesenchymal transition in prostate cancer. Oncotarget 7:67597-67611
Bucay, Nathan; Shahryari, Varahram; Majid, Shahana et al. (2015) miRNA Expression Analyses in Prostate Cancer Clinical Tissues. J Vis Exp :
Saini, Sharanjot; Majid, Shahana; Shahryari, Varahram et al. (2014) Regulation of SRC kinases by microRNA-3607 located in a frequently deleted locus in prostate cancer. Mol Cancer Ther 13:1952-63