McAndrew J, Fernig D G, Rudland P S, Smith J A
Department of Biochemistry, University of Liverpool, UK.
Growth Factors. 1994;10(4):281-7. doi: 10.3109/08977199409010994.
The secretion of transforming growth factor alpha (TGF alpha) and the expression of cell-surface receptors for epidermal growth factor (EGF) were measured in a series of human mammary cell lines. The amount of TGF alpha secreted by the cells did not correlate with the phenotype of the cells (epithelial or myoepithelial), the mechanism of immortalization of the cells (SV40 or spontaneous) or the source of the cells (normal mammary gland, benign hyperplastic lesion, malignant tumour). The level of expression of cell-surface receptors for EGF was markedly increased as a consequence of SV40-immortalization of mammary cells, but otherwise did not correlate with the phenotype of the cells or the source of the cells. Much of the increase was accounted for by the appearance of a large number of low-affinity receptors for EGF in the SV40-immortalized cells. It is suggested that one of the mechanisms whereby SV40-immortalization suppresses the senescence of primary cultures of human mammary epithelial cells involves increasing the level of expression of receptors for EGF. In contrast the level of secretion of TGF alpha by cells in culture is probably a consequence of the mechanisms of adaptation of each cell line to culture conditions, and does not reflect the level of secretion of TGF alpha by cells in vivo.
在一系列人乳腺细胞系中，对转化生长因子α（TGFα）的分泌以及表皮生长因子（EGF）细胞表面受体的表达进行了测定。细胞分泌的TGFα量与细胞的表型（上皮或肌上皮）、细胞永生化的机制（SV40或自发）或细胞来源（正常乳腺、良性增生性病变、恶性肿瘤）均无关联。由于乳腺细胞经SV40永生化，EGF细胞表面受体的表达水平显著增加，但除此之外，其与细胞表型或细胞来源均无关联。这种增加很大程度上是由于SV40永生化细胞中出现了大量低亲和力EGF受体。提示SV40永生化抑制人乳腺上皮细胞原代培养衰老的机制之一涉及增加EGF受体的表达水平。相比之下，培养细胞中TGFα的分泌水平可能是每个细胞系适应培养条件机制的结果，并不反映体内细胞TGFα的分泌水平。
