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Friday, December 28, 2018

Publication in Clinical Cancer Research

 2018 Dec 26. pii: clincanres.3230.2018. doi: 10.1158/1078-0432.CCR-18-3230. [Epub ahead of print]

Epigenetic silencing of miRNA-338-5p and miRNA-421 drives SPINK1-positive prostate cancer.

Author information

1
Biological Sciences & Bioengineering, Indian Institute of Technology Kanpur.
2
Henry Ford Health System.
3
Pathology, Henry Ford Health System.
4
Department of Urology,, King George's Medical University.
5
Urology, Henry Ford Health System.
6
Biological Sciences & Bioengineering, Indian Institute of Technology Kanpur bushra@iitk.ac.in.

Abstract

PURPOSE:

Serine Peptidase Inhibitor, Kazal type-1 (SPINK1) overexpression defines the second most recurrent and aggressive prostate cancer (PCa) subtype. However, the underlying molecular mechanism and pathobiology of SPINK1 in PCa remains largely unknown.

EXPERIMENTAL DESIGN:

MicroRNA-prediction tools were employed to examine the SPINK1-3'UTR for miRNAs binding. Luciferase reporter assays were performed to confirm the SPINK1-3'UTR binding of shortlisted miR-338-5p/miR-421. Further, miR-338-5p/-421 overexpressing cancer cells (SPINK1-positive) were evaluated for oncogenic properties using cell-based functional assays and mice xenograft model. Global gene expression profiling was performed to unravel the biological pathways altered by miR-338-5p/-421. Immunohistochemistry and RNA in-situ hybridization was carried-out on PCa patients' tissue microarray for SPINK1 and EZH2 expression respectively. Chromatin immunoprecipitation assay was performed to examine EZH2 occupancy on the miR-338-5p/-421 regulatory regions. Bisulfite sequencing and methylated DNA-immunoprecipitation was performed on PCa cell lines and patients' specimens.

RESULTS:

We established a critical role of miRNA-338-5p/-421 in post-transcriptional regulation of SPINK1. Ectopic expression of miRNA-338-5p/-421 in SPINK1-positive cells abrogate oncogenic properties including cell-cycle progression, stemness and drug resistance, and show reduced tumor burden and distant metastases in mice model. Importantly, we show SPINK1-positive PCa patients exhibit increased EZH2 expression, suggesting its role in epigenetic silencing of miRNA-338-5p/-421. Furthermore, presence of CpG dinucleotide DNA methylation marks on the regulatory regions of miR-338-5p/-421 in SPINK1-positive PCa cells and patients' specimens confirms epigenetic silencing.

CONCLUSION:

Our findings revealed that miRNA-338-5p/-421 are epigenetically silenced in SPINK1-positive PCa, while restoring the expression of these miRNAs using epigenetic drugs or synthetic mimics could abrogate SPINK1-mediated oncogenesis.
PMID:
 
30587549
 
DOI:
 
10.1158/1078-0432.CCR-18-3230

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