Epigenetic Repression of microRNA-129-2 Leads to Overexpression of SOX4 Oncogene in Endometrial Cancer

• Published in: Cancer research (Chicago, Ill.) Vol. 69; no. 23; pp. 9038 - 9046
• Main Authors: HUANG, Yi-Wen, LIU, Joseph C, DEATHERAGE, Daniel E, JINGQIN LUO, MUTCH, David G, GOODFELLOW, Paul J, MILLER, David S, HUANG, Tim H-M
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01.12.2009
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Antineoplastic agents; Base Sequence; Biological and medical sciences; Carcinoma, Endometrioid - genetics; Carcinoma, Endometrioid - metabolism; CpG Islands; DNA Methylation; Endometrial Neoplasms - genetics; Endometrial Neoplasms - metabolism; Female; Female genital diseases; Gene Expression Regulation, Neoplastic; Gene Silencing; Gynecology. Andrology. Obstetrics; Humans; Medical sciences; MicroRNAs - genetics; Microsatellite Instability; Molecular Sequence Data; MutL Protein Homolog 1; Nuclear Proteins - genetics; Pharmacology. Drug treatments; SOXC Transcription Factors - biosynthesis; SOXC Transcription Factors - genetics; Tumors; Endometrium cancer; RNA interference; Micro RNA; Gene overexpression; Malignant tumor; Repression; Female genital diseases; Gene silencing; Regulation(control); Uterine diseases; Epigenetics; Onc gene; Cancer
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/0008-5472.CAN-09-1499

Genetic amplification, mutation, and translocation are known to play a causal role in the upregulation of an oncogene in cancer cells. Here, we report an emerging role of microRNA, the epigenetic deregulation of which may also lead to this oncogenic activation. SOX4, an oncogene belonging to the SRY-related high mobility group box family, was found to be overexpressed (P < 0.005) in endometrial tumors (n = 74) compared with uninvolved controls (n = 20). This gene is computationally predicted to be the target of a microRNA, miR-129-2. When compared with the matched endometria, the expression of miR-129-2 was lost in 27 of 31 primary endometrial tumors that also showed a concomitant gain of SOX4 expression (P < 0.001). This inverse relationship is associated with hypermethylation of the miR-129-2 CpG island, which was observed in endometrial cancer cell lines (n = 6) and 68% of 117 endometrioid endometrial tumors analyzed. Reactivation of miR-129-2 in cancer cells by pharmacologic induction of histone acetylation and DNA demethylation resulted in decreased SOX4 expression. In addition, restoration of miR-129-2 by cell transfection led to decreased SOX4 expression and reduced proliferation of cancer cells. Further analysis found a significant correlation of hypermethylated miR-129-2 with microsatellite instability and MLH1 methylation status (P < 0.001) and poor overall survival (P < 0.039) in patients. Therefore, these results imply that the aberrant expression of SOX4 is, in part, caused by epigenetic repression of miR-129-2 in endometrial cancer. Unlike the notion that promoter hypomethylation may upregulate an oncogene, we present a new paradigm in which hypermethylation-mediated silencing of a microRNA derepresses its oncogenic target in cancer cells.