Abstract 2971: Methylation-mediated silencing of microRNAs during cervical carcinogenesis.

Abstract

Abstract Deregulated expression of microRNAs (miRNAs) is common and biologically relevant in cervical carcinogenesis and appears only partly related to chromosomal changes. We recently identified 34 miRNAs showing decreased expression in cervical high-grade precursor lesions and carcinomas not associated with a chromosomal loss, 6 of which were located within a CpG island. This study aimed to investigate to what extent these miRNAs are subject to DNA methylation-mediated silencing in cervical carcinogenesis. Methylation-specific PCR (MSP) analysis on a cell line panel representing different stages of human papillomavirus (HPV) induced transformation revealed an increase in methylation of hsa-miR-149, -203, and -375 with progression to malignancy, whereas expression of these miRNAs was restored upon treatment with a demethylating agent. All three miRNAs showed significantly increased levels of methylation in cervical carcinomas, whereas methylation levels of hsa-miR-203 and -375 were also significantly increased in high-grade cervical intraepithelial neoplasia (CIN). A pilot analysis showed that increased hsa-miR-203 methylation was also detectable in HPV-positive cervical scrapes of women with high-grade CIN compared to controls. Similar to recent findings on hsa-miR-375, ectopic expression of hsa-miR-203 in cervical cancer cells decreased both the proliferation rate and anchorage independent growth. We found evidence for methylation-mediated silencing of hsa-miR-149, -203 and -375 in cervical cancer. Methylation of the latter two was already apparent in precancerous lesions and represent functionally relevant events in HPV-mediated transformation. In addition, as demonstrated for hsa-miR-203, these methylated miRNAs may provide valuable markers for assessment of the presence of (pre)cancerous cervical lesions in HPV-positive women. Citation Format: Saskia Marije Wilting, Wina Verlaat, Annelieke Jaspers, Nour A. Makazaji, Reuven Agami, Chris JLM Meijer, Peter JF Snijders, Renske DM Steenbergen. Methylation-mediated silencing of microRNAs during cervical carcinogenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2971. doi:10.1158/1538-7445.AM2013-2971