Chk1/2 inhibitor AZD7762 blocks the growth of preantral follicles by inducing apoptosis, suppressing proliferation, and interfering with the cell cycle in granulosa cells.

Abstract

Checkpoint kinases 1/2 (Chk1/2) have an important role in somatic cell development and oocyte meiotic maturation. However, the role of Chk1/2 in folliculo-genesis has not been fully elucidated. The aim of this study was to assess the effects of Chk1/2 inhibition on ovarian folliculogenesis and granulosa cell development in mice. Preantral follicles (100-120 μm) and granulosa cells from pre-ovulatory follicles (pre-GCs) of mice were isolated and cultured with or without Chk1/2 inhibitor AZD7762. Preantral follicles were cultured for 96h. Then, follicle morphology and fol-licular growth were assessed every 48h. Granulosa cells were cultured for 48h with or without AZD7762, after which cell apoptosis, cell proliferation, and cell cycle analysis were assessed; meanwhile, the mRNA expression of PCNA and Bax were measured by real-time RT-PCR, and PCNA and Bax protein were measured by Western blot. Compared with control follicles, AZD7762 inhibited growth of preantral folli-cles (P<0.05). Furthermore, inhibition of Chk1/2 significantly induced apoptosis (P<0.05) and inhibited the proliferation of granulosa cells (P<0.01), arrested cell cycle at S and G2/M phases, and decreased G1 phase fraction (P<0.001). Also, the expres-sion of PCNA mRNA and protein were reduced (P<0.01), while Bax mRNA and pro-tein were increased (P<0.05) post AZD7762 treatment in granulosa cells. This study revealed that Chk1 and Chk2 have a crucial role during preantral follicular development by regulating the proliferation and apoptosis of granu-losa cells.