Aberrant promoter methylation of NOTCH1 and NOTCH3 and its association with cervical cancer risk factors in North Indian population

摘要

Cervical cancer is the fourth most common type of cancer in women worldwide, and associated mortality is highest in developing countries like India. Limited studies are available on the role of NOTCH signaling pathway and promoter methylation in cervical cancer. In the current study, we investigated the promoter methylation status of NOTCH receptor genes (mainly NOTCH1, NOTCH2 , and NOTCH3 ) and its correlation with gene expression, clinicopathological factors, and prognosis of cervical cancer. A total cohort of 110 cervical cancer patients of North Indian origin was enrolled in the study. From 28 of these patients, biopsies from adjacent non-cancerous tissue were available to serve as healthy controls. Promoter methylation status and mRNA expression level of NOTCH1, NOTCH2 , and NOTCH3 were determined by methylation-specific PCR (MSP) and real-time quantitative (RT-qPCR), respectively. NOTCH1 and NOTCH3 promoters were methylated in 92% (P0.0001), and 61% (P0.001) of the cervical cancer biopsies. We did not observe a statistically significant change in the promoter methylation level of NOTCH2 . Further, NOTCH1, NOTCH2 , and NOTCH3 were down-regulated in cervical cancer biopsies, but the differential expression of only NOTCH1 was found statistically significant. The promoter methylation levels of all three genes also showed a statistically significant association with clinicopathological factors and HPV infection (Type 16 and 18) but we did not observe a statistically significant relationship between their methylation status and gene expression. Overall our results provide evidence of the altered methylation and expression status of NOTCH1 and NOTCH3 receptor genes in cervical cancer. This study of NOTCH gene promoter methylation may provide a new perspective for early screening and diagnosis of cervical cancer.