Quantitation of CDC6 and MCM5 mRNA in cervical intraepithelial neoplasia and invasive squamous cell carcinoma of the cervix.

ABSTRACT

CDC6 and MCM5 play essential roles in eukaryotic DNA replication. Several studies have highlighted the potential of these proteins as molecular markers of dysplastic and malignant cells in histopathological diagnosis. The mode of expression of CDC6 and MCM5 mRNA and their significance in normal, dysplastic and malignant cervical cells remains to be elucidated. Using a quantitative real-time RT PCR assay, we compared CDC6 and MCM5 mRNA expression in normal cervical epithelium, cervical intraepithelial neoplasia and invasive squamous cell carcinoma of the cervix. Our study cohort comprised 20 normal cervical biopsies, 20 CIN3 and eight invasive squamous cell carcinomas. All samples were formalin fixed and paraffin embedded. Total RNA was extracted and analysed for expression of GAPDH, CDC6 and MCM5 using real-time quantitative TaqMan RT-PCR. A linear increase in MCM5 and CDC6 mRNA expression is observed in normal cervix, CIN3 and invasive cervical carcinoma. The overall difference in MCM5 mRNA expression in the normal cervix, CIN3 and invasive cohort groups is highly statistically significant (P=0.001). An increase in CDC6 mRNA expression in CIN3 and invasive cervical squamous cell carcinoma was observed; however, the overall difference between cohort groups was not found to be statistically significant (P=0.104). Increased transcription of MCM5 and CDC6 occurs as a consequence of cervical neoplastic progression. This pattern of increased mRNA expression in CIN3 and invasive cervical carcinoma directly correlates with findings at the phenotypic protein expression level. This study further confirms the importance of MCM5 and CDC6 in malignant transformation and in the pathogenesis of cervical dysplasia.