O'Connor T J, Neufeld E, Bechberger J, Fujita D J
Department of Medical Biochemistry, University of Calgary, Health Sciences Center, Alberta, Canada.
Cell Growth Differ. 1992 Jul;3(7):435-42.
Elevated levels of pp60c-src tyrosine kinase activity have been implicated in both tumorigenesis and cell differentiation. We have found a 2- to 4-fold elevation in pp60c-src specific activity in certain human melanoma cell lines compared to human foreskin fibroblasts. This activation of pp60c-src did not appear to be related to melanoma tumor progression, because when normal human epidermal melanocytes were examined, it was found that they contained pp60c-src having a 7-fold elevation in specific activity compared to pp60c-src from human fibroblasts. It was determined that pp60c-src from melanocytes was not the neuronal form, pp60c-src+. Melanocyte pp60c-src exhibited a reduced level of phosphorylation on its carboxyl-terminal regulatory site, tyrosine 530, which might be responsible for its elevated specific activity. These results suggest that, in melanocytes, regulation of tyrosine 530 phosphorylation-dephosphorylation favors activation of pp60c-src. This activation may be involved in the growth, differentiation, or function of human melanocytes.
pp60c-src酪氨酸激酶活性升高与肿瘤发生和细胞分化均有关联。我们发现，某些人类黑色素瘤细胞系中pp60c-src的比活性相较于人类包皮成纤维细胞升高了2至4倍。pp60c-src的这种激活似乎与黑色素瘤肿瘤进展无关，因为在检查正常人表皮黑素细胞时发现，它们所含的pp60c-src比活性相较于人类成纤维细胞中的pp60c-src升高了7倍。经测定，黑素细胞中的pp60c-src并非神经元形式的pp60c-src+。黑素细胞pp60c-src在其羧基末端调节位点酪氨酸530上的磷酸化水平降低，这可能是其比活性升高的原因。这些结果表明，在黑素细胞中，酪氨酸530磷酸化-去磷酸化的调节有利于pp60c-src的激活。这种激活可能参与人类黑素细胞的生长、分化或功能。
