Deregulated expression of
microRNAs (
miRNAs) is common and biologically relevant in cervical
carcinogenesis and appears only partly related to chromosomal changes. We recently identified 32
miRNAs showing decreased expression in high-grade
cervical intraepithelial neoplasia (CIN) 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 transcriptional repression 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 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 with 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 transcriptional repression 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. Increased
hsa-miR-203 methylation was detectable in scrapes of women with high-grade CIN, indicating that methylated
miRNAs may provide putative markers to assess the presence of (pre)cancerous lesions.