title: Inhibition of p38 MAPK-dependent excision repair cross-complementing 1 expression decreases the DNA repair capacity to sensitize lung cancer cells to etoposide.
abstract: Etoposide (VP-16), a topoisomerase II inhibitor, is an effective anticancer drug currently used for the treatment of a wide range of cancers. Excision repair cross-complementary 1 (ERCC1) is a key protein involved in the process of nucleotide excision repair. High level of ERCC1 expression in cancers is associated with resistance to DNA damage-based chemotherapy. In this study, the effects of p38 mitogen-activated protein kinase (MAPK) signal on the ERCC1 expression induced by etoposide in non-small cell lung cancer (NSCLC) cell lines was investigated. Etoposide increased phosphorylated MAPK kinase 3/6 (MKK3/6)-p38 MAPK and ERCC1 protein and mRNA levels in A549 and H1975 cells. Moreover, SB202190, a p38 inhibitor, or knockdown of p38 expression by specific short interfering RNA (siRNA) significantly decreased the etoposide-induced ERCC1 protein levels and DNA repair capacity in etoposide-exposed NSCLC cells. Enhancement of p38 activation by constitutively active MKK6 (MKK6E) increased ERCC1 protein levels. Specific inhibition of ERCC1 by siRNA significantly enhanced the etoposide-induced cytotoxicity and hypoxanthine guanine phosphoribosyltransferase (hprt) gene mutation rate. Moreover, the Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) could decrease the etoposide-induced p38 MAPK-mediated ERCC1 expression and augment the cytotoxic effect and growth inhibition by etopsoside. 17-AAG and etoposide-induced synergistic cytotoxic effect and DNA repair capacity decrease could be abrogated in lung cancer cells with MKK6E or HA-p38 MAPK expression vector transfection. Our results suggest that in human NSCLC cells, ERCC1 is induced by etoposide through the p38 MAPK pathway, and this phenomenon is required for NSCLC survival and resistant DNA damage.
authors: Molecular Oncology Laboratory, Department of Biochemical Science and Technology, National Chiayi University, Chiayi, Taiwan.
authors: Min-Shao
authors: MS
authors: Tsai
authors: Shao-Hsing
authors: SH
authors: Weng
authors: Huang-Jen
authors: HJ
authors: Chen
authors: Yu-Fan
authors: YF
authors: Chiu
authors: Yu-Ching
authors: YC
authors: Huang
authors: Sheng-Chieh
authors: SC
authors: Tseng
authors: Ya-Hsun
authors: YH
authors: Kuo
authors: Yun-Wei
authors: YW
authors: Lin
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D016227:Benzoquinones / Q000494:pharmacology; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004720:Endonucleases / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D016227:Benzoquinones; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D007093:Imidazoles; D047029:Lactams, Macrocyclic; D011725:Pyridines; C112765:tanespimycin; D005047:Etoposide; D048051:p38 Mitogen-Activated Protein Kinases; C071447:ERCC1 protein, human; D004720:Endonucleases; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole