Apoptosis in female genital organs-the relation between bcl-2 protein and hormone receptor

月经通常被认为是螺旋动脉收缩引起的功能层缺血性坏死，视性激素水平而定。然而，最近的电镜研究表明，凋亡小体主要存在于分泌后期。众所周知，bcl-2在多种细胞系中具有阻断细胞凋亡的能力。因此，子宫内膜是研究bcl-2蛋白在组织重建中的作用以及激素对bcl-2表达调控的理想组织。本研究旨在通过与雌激素受体（ER）和孕激素受体（PgR）分布的比较，阐明bcl-2蛋白在月经周期中人子宫样本中的分布，以及bcl-2蛋白在月经周期中调节细胞凋亡中的作用。21例经知情同意接受子宫切除术的妇女，从子宫腔底取子宫标本，通过免疫组化和Western blot检测bcl-2蛋白、ER和PgR。人子宫内膜腺细胞、间质细胞和子宫内膜平滑肌细胞中均可见Bcl-2蛋白。特别是，腺体细胞在早期分泌期增殖表达bcl-2蛋白，而在月经期分泌后期不表达bcl-2蛋白。bcl-2的循环表达与ER或PgR相似；Bcl-2在腺细胞中的表达可能受卵巢激素的调控。分泌后期腺细胞中bcl-2表达的消失与同期凋亡细胞的出现一致。因此，bcl-2蛋白可能在月经期间细胞凋亡的调节中发挥重要作用。

Menses is generally regarded as ischemic necrosis of functional layr caused by contraction of spiral arteries, depending on sexual hormone levels. The recent electron-microscopic study, however, demonstrated the presence of apoptotic bodies mainly in the late secretory phase. It is well known that bcl-2 has an ability to block apoptosis in various cell lineages. Therefore, uterine endometrium is an attractive tissue for studying roles of bcl-2 protein during tissue reconstruction and also regulation of bcl-2 expression by hormones. This study was designed to clarify the distribution of bcl-2 protein in human uterine samples throughout menstrual cycle, in comparison with the distribution of estrogen receptor (ER) and progesterone receptor (PgR), and a role of bcl-2 protein in the modulation of apoptosis during menstruation. Uterine samples were collected from 21 women undergoing hysterectomy with informed consent and were obtained from the fundus within the uterine cavity and examined via immunohistochemistry and Western blot analysis for bcl-2 protein, ER and PgR.Bcl-2 protein was observed in human endometrial glandular, stromal and myometrial smooth muscle cells. Especially, glandular cells expressed bcl-2 protein at proliferative through early secretory phases but not at late secretory through menstrual phases. This cyclic expression of bcl-2 was similar to that of ER or PgR ; bcl-2 expression in glandular cells may be regulated by ovarian hormones. The disappearance of bcl-2 expression in glandular cells at late secretory phase was ocnsistent with the appearance of apoptotic cells at the same phase. Therefore, bcl-2 protein may play an important role in the modulation of apoptosis during menstruation.