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Differential sensitivity of normal and H-ras oncogene-transformed rat kidney epithelial cells to okadaic acid-induced apoptosis.

Abstract：

:H-ras oncogenes have been identified in greater than 50% of the most common forms of human neoplasia. Ras-related proteins have been postulated to mediated signal transduction pathways involving mitogen-activated protein (MAP) kinases and nuclear responses that may be involved in the induction of apoptosis. We examined whether expression of H-ras oncogene conferred resistance or susceptibility to the morphologic effects of the protein phosphatase inhibitor, okadaic acid, using a tumorigenic H-ras-transformed normal rat kidney epithelial cell line, NRK-H/6.1. We also examined whether okadaic acid induced apoptosis correlated with a differential effect on kinase activity in H-Ras-transformed cells as compared to the nontransformed NRK-52E cells. Treatment with various concentrations of okadaic acid produced rapid and extensive morphologic changes characteristic of apoptosis in both cell types. Equimolar okadaic acid concentrations for 2 or 4 hr resulted in cell detachment and loss of membrane integrity (as measured by propidium iodide uptake) in 74% (0.5 microM) and 78% (1.0 microM) of the H-Ras-transformed cells as compared to 8 and 25%, respectively, in the non-transformed cells. Furthermore, a higher basal level of kinase activity was observed in the H-Ras-transformed cells as compared to the nontransformed cells. Okadaic acid-induced apoptosis correlated with activation of members of the MAP kinase family, raf-1 and protein kinase C (PKC). These studies show that H-ras oncogene expression imparts selective susceptibility to cell death induced by phosphatase inhibition. The observed increase in susceptibility to okadaic acid-induced apoptosis appears to involve the modulation of raf-1, PKC, and MAP kinase activities. These findings may be significant in the elucidation of mechanisms for selective induction of cell death in tumor cells expressing H-ras oncogene.

journal_name

Toxicol Appl Pharmacol

journal_title

Toxicology and applied pharmacology

authors

Davis MA,Chang SH,Trump BF

doi

10.1006/taap.1996.0264

subject

Has Abstract

pub_date

1996-11-01 00:00:00

pages

93-101

issue

eissn

0041-008X

issn

1096-0333

pii

S0041-008X(96)90264-1

journal_volume

141

pub_type

杂志文章

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Differential sensitivity of normal and H-ras oncogene-transformed rat kidney epithelial cells to okadaic acid-induced apoptosis.