Lerner A A, Salamone D F, Chiappe M E, Barañao J L
Instituto de Biología y Medicina Experimental-CONICET, Buenos Aires, Argentina.
J Cell Physiol. 1995 Aug;164(2):395-403. doi: 10.1002/jcp.1041640220.
A bovine granulosa cell line (BGC-1) has been obtained by spontaneous immortalization of primary cultures. BGC-1 cells have retained some characteristics of primary cultures, such as the hormonal regulation of fibronectin biosynthesis. In the present study we have compared BGC-1 cells and primary cultures of bovine granulosa cells in terms of protein secretion, steroid metabolism, and mitogenic responses to growth factors. The pattern of protein secretion in BGC-1 cells was qualitatively similar to that of primary cultures. The main differences were a higher proportion of fibronectin and the relative amounts of several other unidentified proteins. Progesterone levels in BGC-1 cultures were undetectable. When BGC-1 cells and primary cultures were incubated with [3H]-pregnenolone, the former showed a lower conversion rate to progesterone. In contrast, the conversion rate of [3H]-progesterone to 5 alpha-reduced metabolites was markedly increased in BGC-1 cells. We also examined the effects of epidermal growth factor (EGF), insulin like growth factor-I (IGF-I), and transforming growth factor-beta (TGF-beta) on DNA synthesis under serum-free conditions. Both primary cultures and BGC-1 cells exhibited a stimulatory response to EGF and IGF-I on [3H]-thymidine incorporation. Neither BGC-1 cells nor primary cultures showed a significant response to TGF-beta when added alone. However, in the presence of a combination of EGF and IGF-I, TGF-beta displayed an inhibitory effect on primary cultures while it stimulated DNA synthesis in BGC-1 cells even further. The addition of conditioned medium from BGC-1 cells (BGC-1-CM) stimulated DNA synthesis on primary cultures to a greater extent than the addition of conditioned medium from primary cultures. These results suggest that BGC-1 cells may be a useful model to study the regulation of granulosa cell function during the period previous to the preovulatory stage of follicular development. The differential responses of the immortalized cells to growth regulators may offer some clues on the mechanisms that control cell proliferation in normal tissues.
通过原代培养的自发永生化获得了一种牛颗粒细胞系（BGC-1）。BGC-1细胞保留了原代培养的一些特性，如纤连蛋白生物合成的激素调节。在本研究中，我们比较了BGC-1细胞和牛颗粒细胞原代培养物在蛋白质分泌、类固醇代谢以及对生长因子的促有丝分裂反应方面的差异。BGC-1细胞中的蛋白质分泌模式在质量上与原代培养物相似。主要差异在于纤连蛋白的比例较高以及其他几种未鉴定蛋白质的相对含量。在BGC-1培养物中未检测到孕酮水平。当BGC-1细胞和原代培养物与[3H]-孕烯醇酮一起孵育时，前者向孕酮的转化率较低。相反，在BGC-1细胞中，[3H]-孕酮向5α-还原代谢物的转化率明显增加。我们还研究了在无血清条件下表皮生长因子（EGF）、胰岛素样生长因子-I（IGF-I）和转化生长因子-β（TGF-β）对DNA合成的影响。原代培养物和BGC-1细胞对EGF和IGF-I在[3H]-胸苷掺入方面均表现出刺激反应。单独添加时，BGC-1细胞和原代培养物对TGF-β均未表现出明显反应。然而，在EGF和IGF-I联合存在的情况下，TGF-β对原代培养物显示出抑制作用，而它甚至进一步刺激了BGC-1细胞中的DNA合成。添加来自BGC-1细胞的条件培养基（BGC-1-CM）比添加来自原代培养物的条件培养基更能刺激原代培养物中的DNA合成。这些结果表明，BGC-1细胞可能是研究卵泡发育排卵前期之前颗粒细胞功能调节的有用模型。永生化细胞对生长调节剂的不同反应可能为控制正常组织中细胞增殖的机制提供一些线索。
