Investigation of Adverse Cancer Related DNA Methylation Variation in the Human Telomerase Reverse Transcriptase (hTERT) Promotor in Follicular Fluid Cells of Women Subjected to Ovarian Stimulation for In Vitro Fertilization (IVF)

Abstract

Purpose: To determine the variability in DNA methylation of the human telomerase reverse transcriptase (hTERT) promotor in cells of follicular fluid of patients receiving ovarian stimulation for treatment with in vitro fertilization (IVF), in connection with possible cancer related health risk in offspring. Materials and method: The pilot study analysed the variability in DNA methylation of five cancer related CpG biomarkers in the hTERT promoter by bisulfite pyrosequencing in cells of follicular fluid of 8 patients treated by IVF, each one originating from one ovary. Results: The absolute promoter methylation levels of individual CpG dinucleotides in the hTERT promoter region in cells of follicular fluid of patients undergoing ovarian stimulation for IVF varied between 2 and 15%. Although the mean hTERT promoter methylation did not significantly differ from levels observed in healthy control samples, maximal DNA methylation levels of one tumour specific CpC methylation biomarker were close to levels detected in hepatocellular cancer and in paediatric brain tumours. Conclusion: Bisulfite pyrosequencing allows for highly sensitive detection of CpG specific DNA methylation of the five dinucleotides of the hTERT promoter region in cells of follicular fluid of patients treated by ovarian stimulation for IVF. The occasional observation of tumorigenic DNA methylation at GpC motifs strongly associated with hepatocellular carcinoma and sporadic malignant paediatric brain tumours, suggests that offspring of IVF pregnancies may be at increased risk of adverse cancer outcomes. In order to reduce the possible cancer risk in the offspring related to hTERT hypermethylation and oxidative DNA damage, nutraceutical food supplementation during conception and early pregnancy may warrant further investigation, aiming at the reduction of the homocysteine concentration and the hTERT promoter methylation in follicular fluid and cells during ovarian stimulation.