期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1984
卷号：81
期号：14
页码：4280-4284
DOI：10.1073/pnas.81.14.4280
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A number of recent studies have indicated that the expression of keratins is altered upon malignant transformation of human epithelial cells. We have shown that the altered expression of 67-kDa and 40-kDa keratins in established squamous cell carcinoma lines from tongue and epidermis stems largely from a difference in their sensitivity to vitamin A apparently acquired during tumorigenesis. When the vitamin A concentration in the medium is raised, the 40-kDa keratin is produced at increased levels. Conversely, when the amount of vitamin is reduced, the 67-kDa keratin is synthesized and the cells undergo stratification and terminal differentiation. However, even when vitamin A is quantitatively removed from the medium, the maximal degree of differentiation attained by each squamous cell carcinoma cell as judged by the synthesis of 67-kDa keratin was still less than that of the normal keratinocytes. These findings suggest that the altered patterns of keratins observed for some tissues upon malignant transformation arise from a complex mixture of intracellular changes in the differentiative pathway in addition to changes in the responsiveness of cells to extracellular regulators of keratin gene expression.
