Quantitative analysis of the relationship between microRNA‑124a, -34b and -203 gene methylation and cervical oncogenesis

Abstract

Abstract. cervical cancer is a leading cause of mortality in women. Molecular and epidemiological data have unequivocally confirmed that high-risk human papillomaviruses (HPVs) are a major etiological agent of this malignancy, as host epigenetic alterations are induced in response to viral infection. The present study evaluated the methylation status of cpG islands surrounding miR-124a, miR-34b and miR-203 in 29 cervical cancer precursor lesions, 31 cervical tumors and 30 normal control samples, with the aim of identifying potential markers of cervical cancer. Direct quantitative methylation-specific PCR (qMSP) was used to evaluate the degree of methylation in the samples. HPV DNA was detected and genotyped using the Linear Array HPV Genotyping Test. Data were statistically analyzed using the Kruskal-Wallis test. Differences in miRNA hypermethylation between the tumor and control samples were highly significant for all the genes tested (p<0.0001). Significant results were also obtained regarding the hypermethylation of miR-124a and miR-203 in the precursor lesions compared to the control samples. among the 29 patients with precursor lesions, 68.97% (20/29) presented high risk (hr)-HPV genotypes and 31.03% (9/29) were diagnosed with low risk (lr)-HPV. Significant results (p=0.0266) were obtained for miR-124a (hr-HPV group, mean 41.32; lr-HPV group, mean 6.74), revealing a strong association between the methylation process and the hr-HPV genotype. Borderline results (p=0.058) were obtained for miR-203 (hr-HPV group, mean 44.05; lr-HPV group, mean 3.33). These results confirm the involvement of epigenetic alterations in cervical oncogenesis. The lr-HPV precursor lesions had a methylation percent pattern similar to that of the normal samples, while the results for the hr-HPV precursor lesions and tumors indicate a possible involvement of the hr-HPV genotype in the miRNA methylation process.

Aberrant Expression of miR-20a and miR-203 in Cervical Cancer

“…miR-20a could also be affected by DNA methylation (Lee et al, 2012). Botezatu found the results for the high risk-HPV precursor lesions and tumors indicate a possible involvement of the high risk HPV genotype in the miRNA methylation process (Botezatu et al, 2011). A Series of works demonstrated the direct correlation between miRNAs and epigenetic mechanisms in cancer which could be an important mechanism for the transcriptional regulation of miRNAs.…”

Clinical implications of (epi)genetic changes in HPV-induced cervical precancerous lesions

“…in cervical cancers has been linked to increased promoter methylation of respective genes 73,74,83,84 . These data are fully in line with the concept that an increase in specific genetic and epigenetic alterations reflects a longer duration of existence of the underlying lesion.…”

Human Papillomaviruses Oncoproteins

“…Another cause of miR-203 down-regulation is due to methylation of CpG islands in the promoter region. Hypermethylation of miR203 as well as miR-34b and miR-124 was correlated with CIN III and cervical cancer [95].…”