Impact of Mutations in the D-loop Region in Ovarian Cancer in Senegalese Women

Abstract

In Senegal, ovarian cancer is the 3rd most common cancer in women with an incidence of 5.0/100,000 women. Thirty-five cancerous tissues, twenty-seven healthy tissues were included in this study. Due to the anatomical position of the ovary, the removal of a sample of suspicious tissue from each patient involves surgery through laparotomy or laparoscopy after obtaining consent. DNA extraction, polymerase chain reaction (PCR) and sequencing were performed to obtain sequences. BioEdit version 7.0.5.3 2005, Harlequin version 3.0, DnaSP version 5.10.01, MEGA 6 were used to perform the analyses. The results show a higher percentage of transition in cancerous tissues (91.45) than in healthy tissues (75.19) in contrast to transversions which are greater in healthy tissues (24.84) than in cancerous tissues (8.54), and the mutation rate (R) is also higher in cancerous tissues (10.712) than in healthy tissues (3.079). Analysis of the polymorphism revealed high values of haplotypic diversity in both cancerous tissues (0.662±0.085) and healthy tissues (0.997±0.011), and low nucleotide diversity values in both tissues (cancerous tissues=0.00922±0.00175; healthy tissues=0.01539±0.00175), these results show us that the genetic evolution of mutations in ovarian cancer has a strong polymorphism. It was also found that the value of the genetic distance between healthy tissues (0.016) was higher than that observed between cancerous tissues (0.009). The genetic distance between healthy and cancerous tissues is 0.015 closer than that observed between healthy tissues. The value of genetic differentiation between healthy and cancerous tissues is significant; this demonstrates a much faster proliferation of cancer cells. The objective of this study is, on the one hand, to better understand the target population by clearly identifying demographic parameters and on the other hand, to evaluate the involvement of somatic mutations and mitochondrial DNA gene expression in the occurrence of ovarian cancer in women in Senegal. The specific objectives are to search for mutations of interest by sequencing mtDNA genes with quasi-maternal inheritance and the impact of these mutations in the D-loop region in healthy and diseased tissues in the patient, but also to learn about the diversity, differentiation and genetic evolution of ovarian cancer in Senegalese women.