Matsuo H, Maruo T, Samoto T
Department of Obstetrics and Gynecology, Kobe University School of Medicine, Japan.
J Clin Endocrinol Metab. 1997 Jan;82(1):293-9. doi: 10.1210/jcem.82.1.3650.
Uterine leiomyoma is the most common benign smooth muscle cell tumor of the myometrium. Although Bcl-2 protein is known to be an apoptosis-inhibiting gene product and to prevent apoptotic cell death in a variety of cells, there are no published data regarding whether human leiomyomas express Bcl-2 protein. In the present study, we examined the expression of Bcl-2 protein in leiomyomas in comparison with that in the normal myometrium using an immunohistochemical method and immunoblot analysis with a monoclonal antibody to human Bcl-2 protein. Furthermore, we investigated whether sex steroid hormones could influence the levels of Bcl-2 protein expression in leiomyoma cells cultured in vitro under serum-free, phenol red-free conditions. Immunohistochemical staining for Bcl-2 protein was prominent in leiomyoma cells, but was scarcely present in normal myometrial smooth muscle cells. The expression of Bcl-2 protein in leiomyoma cells was most abundant in the secretory, progesterone-dominated, phase of the menstrual cycle, but was less abundant in the proliferative phase of the menstrual cycle. Western blot analyses of leiomyoma and myometrium tissue extracts revealed that Bcl-2 protein, with a molecular mass estimated at approximately 26 kDa, was abundantly present in leiomyoma tissue extracts, but was undetectable in normal myometrial tissue extracts. In monolayer cultures of uterine leiomyoma cells under a serum-free condition, the addition of progesterone (100 ng/mL) resulted in a striking increase in Bcl-2 protein expression in the cultured leiomyoma cells relative to that in control cultures, whereas the addition of 17 beta-estradiol (10 ng/mL) resulted in a reduction in Bcl-2 protein expression in the cells. The concentrations of sex steroids used were within the physiological tissue concentrations found in leiomyomas and myometrium. The present results suggest that the abundant expression of Bcl-2 protein may have a molecular basis characteristic of leiomyomas in the human uterus and that progesterone may play a vital role in the enhanced expression of Bcl-2 protein in human uterine leiomyoma cells.
子宫平滑肌瘤是子宫肌层最常见的良性平滑肌细胞肿瘤。虽然已知Bcl-2蛋白是一种抑制细胞凋亡的基因产物，可防止多种细胞发生凋亡性细胞死亡，但关于人类平滑肌瘤是否表达Bcl-2蛋白，尚无已发表的数据。在本研究中，我们使用免疫组织化学方法和针对人类Bcl-2蛋白的单克隆抗体进行免疫印迹分析，比较了平滑肌瘤与正常子宫肌层中Bcl-2蛋白的表达情况。此外，我们研究了在无血清、无酚红条件下体外培养的平滑肌瘤细胞中，性类固醇激素是否会影响Bcl-2蛋白的表达水平。Bcl-2蛋白的免疫组织化学染色在平滑肌瘤细胞中很明显，但在正常子宫肌层平滑肌细胞中几乎不存在。平滑肌瘤细胞中Bcl-2蛋白的表达在月经周期的分泌期（以孕酮为主导）最为丰富，但在月经周期的增殖期则较少。对平滑肌瘤和子宫肌层组织提取物的蛋白质印迹分析显示，分子量估计约为26 kDa的Bcl-2蛋白大量存在于平滑肌瘤组织提取物中，但在正常子宫肌层组织提取物中无法检测到。在无血清条件下对子宫平滑肌瘤细胞进行单层培养时，添加孕酮（100 ng/mL）导致培养的平滑肌瘤细胞中Bcl-2蛋白表达相对于对照培养物显著增加，而添加17β-雌二醇（10 ng/mL）则导致细胞中Bcl-2蛋白表达减少。所使用的性类固醇激素浓度在平滑肌瘤和子宫肌层中发现的生理组织浓度范围内。目前的结果表明，Bcl-2蛋白的丰富表达可能具有人类子宫平滑肌瘤的分子基础特征，并且孕酮可能在人类子宫平滑肌瘤细胞中Bcl-2蛋白的增强表达中起重要作用。
