Gibson C A, Baumrucker C R
Department of Dairy and Animal Science, Pennsylvania State University, University Park 16802, USA.
Comp Biochem Physiol A Physiol. 1996 Feb;113(2):195-204. doi: 10.1016/0300-9629(95)02052-7.
A subcloned mouse mammary epithelial cell line (COMMA-D/MME) was cultured on Engelbreth-Holm-Swarm (EHS) tumor cell matrix with lactogenic hormones (insulin, cortisol, prolactin) to stimulate differentiation and challenged with growth factors to interpret the relationship between the signals for growth and differentiation. After 21 days of pretreatment to promote differentiation, cells were capable of growth, but were always less responsive than cells that did not receive lactogenic pretreatment. Although the cells failed to express beta-casein mRNA, droplets of neutral lipids were present in the cell cytoplasm regardless of treatment. Lactogenic hormones induced the appearance of larger droplets that occurred in intracytoplasmic lumens and lipid synthesis rates were initially increased. However, the glycerol incorporation pattern of these lipids only reached 53% of the changes expected for lactating tissue. Furthermore, because secretion of the lipid was inhibited, the accumulation eventually inhibited synthetic capacity. The cellular expression of acetyl Co-A carboxylase message was increased by growth, but not by lactogenic treatments. It is concluded that the COMMA-D/MME are capable of partial and transient differentiation to synthesize milk lipids, but are inhibited by the accumulation of material due to inability to secrete.
将亚克隆的小鼠乳腺上皮细胞系（COMMA-D/MME）接种于恩格尔布雷特-霍尔姆-斯旺（EHS）肿瘤细胞基质上，添加生乳激素（胰岛素、皮质醇、催乳素）以刺激其分化，并用生长因子进行刺激，以阐释生长信号与分化信号之间的关系。在进行21天的预处理以促进分化后，细胞能够生长，但与未接受生乳预处理的细胞相比，其反应性始终较低。尽管这些细胞未能表达β-酪蛋白mRNA，但无论处理方式如何，细胞质中均存在中性脂质滴。生乳激素诱导出现更大的脂质滴，这些脂质滴出现在胞质内腔中，脂质合成速率最初有所增加。然而，这些脂质的甘油掺入模式仅达到泌乳组织预期变化的53%。此外，由于脂质分泌受到抑制，其积累最终抑制了合成能力。生长可增加乙酰辅酶A羧化酶信息的细胞表达，但生乳处理则无此作用。结论是，COMMA-D/MME能够进行部分和短暂的分化以合成乳脂，但由于无法分泌而导致物质积累，从而受到抑制。
