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Expression of Ly-6, a marker for highly malignant murine tumor cells, is regulated by growth conditions and stress

Authors :
Isaac P. Witz
Rinat Eshel
Tzipora Meshel
Romema Anavi
Orit Sagi-Assif
Orlie Kahana
Ben-Zion Katz
Itshak Golan
Alexandra Treister
Nechama I. Smorodinsky
Michal Entin Meer
Ethan M. Shevach
Source :
International Journal of Cancer. 77:306-313
Publication Year :
1998
Publisher :
Wiley, 1998.

Abstract

Ly-6E.1 is highly expressed in murine tumor cells with a high malignancy phenotype and may serve as a marker for such a phenotype. In this study, we examined the effects of various growth conditions and stress on the expression levels of Ly-6E.1 by tumor cells. Previous preliminary results have shown that murine DA3 mammary tumor cells expressing high levels of Ly-6E.1 (Ly-6(hi)) are more highly tumorigenic than the same tumor cells expressing low levels of this membrane protein (Ly-6(lo)). In this study, we demonstrate that mice bearing Ly-6(hi) DA3 tumors have a significantly higher burden of spontaneous pulmonary metastasis than mice bearing Ly-6(lo) DA3 tumors. Furthermore, the survival time of the former mice was significantly shorter than that of the latter ones. We further show that certain other members of the Ly-6 gene family such as Ly-6C.1 and Ly-6G.1 are coregulated with Ly-6E.1. This was shown to occur with respect to both DA3 cells as well as A3 tumor cells which are of fibroblast origin. However, these 2 cells differ with respect to regulation of Sca-2 (TSA1, another member of the Ly-6 family) expression on these cells. Levels of Sca-2 on A3 cells appear to be coregulated with Ly-6E.1 (i.e., Ly-6(hi) A3 cells express high levels of Sca-2 and Ly-6(lo) A3 cells express low levels of Sca-2). These 2 Ly-6 proteins were, however, not coregulated on DA3 cells. Both Ly-6(hi) as well as Ly-6(lo) DA3 cells express equal levels of Sca-2. Levels of Thy-1, another glycosylphosphatidylinositol (GPI)-anchored protein expressed by A3 tumor cells, were equally expressed by both Ly-6(hi) and Ly-6(lo) A3 tumor cells. Levels of Ly-6 (but not those of CD44) on A3 tumor cells were upregulated on cells from dense cultures but were not influenced by the position of the cells in the cell cycle. Stress conditions such as serum starvation or heat shock upregulated the expression of Ly-6 by the 2 types of tumor cells but did not induce apoptosis in these cells. The kinetics of the stress-dependent upregulation of Ly-6 expression differed, however, between the epithelial and fibroblastic tumor cells.

Details

ISSN :
10970215 and 00207136
Volume :
77
Database :
OpenAIRE
Journal :
International Journal of Cancer
Accession number :
edsair.doi.dedup.....08c9fba83697456a71109cd832d1683c
Full Text :
https://doi.org/10.1002/(sici)1097-0215(19980717)77:2<306::aid-ijc22>3.0.co;2-7