The Jun kinase/stress-activated protein kinase pathway functions to regulate DNA repair and inhibition of the pathway sensitizes tumor cells to cisplatin.
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 microM), modified to express a nonphosphorylatable dominant negative c-Jun (termed dnJun) exhibit decreased viability following treatment with cisplatin, but not transplatin, in proportion (rPearson = 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.
Potapova
O
O
Sidney Kimmel Cancer Center, San Diego, California 92121, USA.
Haghighi
A
A
Bost
F
F
Liu
C
C
Birrer
M J
MJ
Gjerset
R
R
Mercola
D
D
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics* / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology*; D004260:DNA Repair; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005909:Glioblastoma / Q000235:genetics* / Q000473:pathology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D015398:Signal Transduction / Q000235:genetics
D000970:Antineoplastic Agents; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D002945:Cisplatin