The Effect of Altered Mucin1, FGF2, and HBEGF Gene Expression at The Ectopic Implantation Site and Endometrial Tissues in The Tubal Pregnancy Pathogenesis: A Case-Control Study.

Background: Ectopic pregnancy (EP) is defined as implantation and development of an embryo outside of the uterine tissue. Women undergoing assisted reproductive technologies (ART), particularly frozen embryo transfer (FET), are in high-risk populations for EP. Mucin1 (MUC1), fibroblast growth factor-2 (FGF2), and Heparin-binding epidermal growth factor (HBEGF) genes are involved in the endometrial receptivity pathway, leading to normal eutopic implantation; Although, their relevance in the tubal pregnancy after FET is unknown. We aimed evaluation of Mucin1, FGF2, and HBEGF expression fold as endometrial receptive markers in the EP patients following the FET cycle.

Materials and methods: A case-control study was conducted on ten patients (five EP patients and five women in the pseudo-pregnancy group, as the control samples). Pseudo-pregnancy group was established in women who were candidates for hysterectomy for benign diseases. Fallopian tube biopsies and corresponding endometrial tissues from these patients were taken during the hysterectomy. However, the fallopian tube and endometrial tissues of EP patients were obtained during salpingectomy. The mRNA expressions of Mucin1, FGF2, and HBEGF genes in the fallopian tube and endometrial tissues were measured by real-time polymerase chain reaction (PCR) assay.

Results: MUC1 mRNA expression level in the endometrium of the case group was higher than in the control group (P=0.04); however, its mRNA expression in the fallopian samples of the case group in comparison with the control group was significantly decreased (P=0.001). The HBEGF mRNA expression level was not significantly different between the case and control endometrium, whereas its expression was significantly increased in the case fallopian samples compared with the control ones (P=0.001). The same pattern was observed for FGF2 mRNA expression level in the fallopian samples of the case group but was significantly reduced in the endometrial samples in comparison with the control samples (P=0.03).

Conclusion: Mucin1, FGF2, and HBEGF gene mRNA expression changes may explain the embryo rejection from the uterus and the establishment of a receptive phenotype in fallopian cells.