Influence of Transforming Growth Factor-α on Expression of Matrix Metalloproteinase-2, Matrix Metalloproteinase-9, and Epidermal Growth Factor Receptor Gene in the Mouse Blastocysts

Purpose: This study was carried out to investigate the influence of transforming growth factor-α (TGF-α) on the expression of mRNA for matrix metalloproteinase-2 (MMP-2), MMP-9, and epidermal growth factor receptor (EGFR) in mouse blastocysts and the effect on the production and activation of MMP-2 and MMP- 9 during blastocyst outgrowth. Methods: Two-cell mouse embryos were cultured for 96 h in the presence or absence of various concentrations of TGF-α. Reverse transcription–polymerase chain reaction (RT-PCR) was used to examine the expression of mRNA for MMP-2, MMP-9, and EGFR in in vitro cultured blastocysts. To investigate the effect on the production and activation of MMP-2 and MMP-9 during blastocyst outgrowth, the conditioned medium collected after 3 and 5 days of embryo culture were assayed for MMP activity by gelatin zymography. Results: The relative mRNA levels of MMP-2 and MMP-9 in blastocysts treated with TGF-α were higher than that of the control in a concentration-dependent manner. The relative mRNA level of EGFR in blastocysts treated with TGF-α was higher than that of the control. In conditioned medium collected after 3 days of embryo culture, TGF-α induced the gelatinase activities of proMMP-9 in all groups and activated MMP-2 in the 10 and 100 ng/mL TGF-α treated groups. In conditioned medium collected after 5 days, TGF-α induced the gelatinase activities of proMMP-9 in all groups and activated MMP-9 in the TGF-α treated group. TGF-α also induced the gelatinase activities of activated MMP-2 in the 1 and 10 ng/mL TGF-α treated groups and the control. Conclusions: These results suggest that the addition of TGF-α to in vitro culture medium is proper to create a favorable environment for preimplantation embryo development and implantation.