The Jun Kinase/Stress-activated Protein Kinase Pathway Functions to Regulate DNA Repair and Inhibition of the Pathway Sensitizes Tumor Cells to Cisplatin*
- Olga Potapova,
- Ali Haghighi,
- Frédéric Bost,
- Chaoting Liu,
- Michael J. Birrer‡,
- Ruth Gjerset and
- Dan Mercola§¶
- From the Sidney Kimmel Cancer Center, San Diego, California 92121, the §Center for Molecular Genetics, University of California at San Diego, La Jolla, California 92093, and the ‡Division of Biomarkers and Prevention Research Branch, National Institutes of Health, Rockville, Maryland 20850
Abstract
We have studied the role of Jun/stress-activated protein kinase (JNK/SAPK) pathway in DNA repair and cisplatin resistance in T98G glioblastoma cells. JUN/SAPK is activated by DNA damage and phosphorylates serines 63 and 73 in the N-terminal domain of c-Jun, which is known to increase its transactivation properties. We show that treatment of T98G glioblastoma cells with cisplatin but not the transplatin isomer activates JNK/SAPK about 10-fold. T98G cells, which are highly resistent to cisplatin (IC50 = 140 ± 13 μm), modified to express a nonphosphorylatable dominant negative c-Jun (termed dnJun) exhibit decreased viability following treatment with cisplatin, but not transplatin, in proportion (r Pearson = 0.98) to the level of dnJun expressed leading to a 7-fold decreased IC50. Similar effects are observed in U87 cells, PC-3 cells, and MCF-7 cells, as well as in T98G cells modified to express TAM-67, a known inhibitor of c-Jun function. In contrast, no sensitization effect was observed in cells modified to express wild-type c-Jun. Furthermore, through quantitative polymerase chain reaction-stop assays, we show that dnJun expressing cells were inhibited in repair of cisplatin adducts (p = 0.55), whereas repair is readily detectable (p = 0.003) in parental cells. These observations indicate that the JNK/SAPK pathway is activated by cisplatin-induced DNA damage and that this response is required for DNA repair and viability following cisplatin treatment. Regulation of DNA repair following genotoxic stress may be a normal physiological role of the JNK/SAPK pathway.
Footnotes
-
↵* This work was supported by Grant CA 63783 from the National Cancer Institute (to D. A. M.), by La Ligue Nationale Contre le Cancer (to F. B. and D. A. M.), by the Tobacco-Related Diseases Research Program of California (to R. G.), by the U. S. Army Breast Cancer Research Project (to R. G.), by Introgen Therapeutics, Inc. (to R. G.), and by the Fellowship Program of the Sidney Kimmel Cancer Center.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
-
↵¶ To whom correspondence should be addressed: Sidney Kimmel Cancer Center, 3099 Science Park Rd., San Diego, CA 92121. Tel.: 619-450-5990; Fax: 619-450-3251; E-mail:74361.2163{at}compuserve.com.
- Received January 6, 1997.
- Revision received April 1, 1997.
