Mono-(2-ethylhexyl) phthalate induces apoptosis through miR-16 in human first trimester placental cell line HTR-8/SVneo

Phthalates have been linked to adverse pregnancy complications. Mono-(2-ethylhexyl) phthalate, an active metabolite of di-(2-ethylhexyl) phthalate and an endocrine disruptor, has been shown to induce apoptosis in various cell types including placental cells. However, the mechanism of action of MEHP induced apoptosis is still unknown. We hypothesized that apoptosis may be mediated in part through altered microRNA(s) in placenta under MEHP exposure. In the present study, we report that MEHP increases miR-16 expression in a time- and dose-dependent manner (p < 0.05), while inducing apoptosis in HTR-8/SVneo. Cells treated with MEHP showed a dose-dependent increase in cytotoxicity and reactive oxygen species along with decreased cell viability. Consistent with significant increase in apoptosis analyzed by flow cytometry, we detected decreased anti-apoptotic BCL-2 at transcriptional and translational levels with MEHP (p < 0.05). Knockdown of miR-16 did not decrease the BCL-2/BAX protein expression ratio in the presence of MEHP when compared to negative control demonstrating that MEHP induces apoptosis directly through miR-16. In conclusion, our study demonstrates for the first time that MEHP induces miR-16, which in turn, alters BCL-2/BAX ratio leading to increased apoptosis. This study provides a novel insight into MEHP induced epigenetic regulation in placental apoptosis which may lead to pregnancy complications.