title: The synergistic effect of combination temozolomide and chloroquine treatment is dependent on autophagy formation and p53 status in glioma cells.
abstract: Temozolomide (TMZ) is an alkylating agent used for the treatment of glioblastoma. The late autophagy inhibitor chloroquine (CQ) inhibits glioblastoma tumors in a p53-independent and p53-dependent manner. We addressed a possible beneficial effect of combination treatment with TMZ and CQ by examining the molecular and cellular mechanism of co-treatment. Combination treatment of U87 cell (wild type p53) with TMZ and CQ synergistically reduced cell proliferation and enhanced apoptosis, with increased sub-G1 hypodiploid cells and caspase activation. This effect was abolished by a pan-caspase inhibitor, Z-VAD-FMK. TMZ induced autophagy, and the addition of CQ further increased autophagic vacuoles. Inhibition of early stages of autophagy by Beclin 1 knockdown and 3-methyladenine pretreatment prevented the enhanced effect of the combination treatment. The combination treatment also upregulated p53 and phospho-p53 levels, whereas p53 knockdown or overexpression of mutant p53 abolished the combination effect. In contrast, combination therapy had no enhanced effect on U373 cell (mutant p53) proliferation and apoptosis within 3 d, although TMZ induced autophagy and co-treatment with CQ increased autophagic vacuole accumulation. However, long term combination treatment for 9-10 d effectively decreased clonal and cellular growth with increased G2-M arrest. This effect was also abolished by Beclin 1 knockdown. Our data support the beneficial effect of combination treatment with TMZ and CQ in glioma via differential autophagy-associated mechanisms, depending on p53 status.
authors: Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea.
authors: Seung Woo
authors: SW
authors: Lee
authors: Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea.
authors: Hyun-Kyung
authors: HK
authors: Kim
authors: Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea.
authors: Na-Hyeon
authors: NH
authors: Lee
authors: Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea.
authors: Hee-Yeon
authors: HY
authors: Yi
authors: Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea.
authors: Hong-Sug
authors: HS
authors: Kim
authors: Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, 215-4, Gongneung-Dong, Nowon-Gu, Seoul 139-706, Republic of Korea.
authors: Sung Hee
authors: SH
authors: Hong
authors: Department of Neuro-Surgery, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea.
authors: Yong-Kil
authors: YK
authors: Hong
authors: Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea. Electronic address: youngjoe@catholic.ac.kr.
authors: Young Ae
authors: YA
authors: Joe
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects / Q000502:physiology; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D002738:Chloroquine / Q000008:administration & dosage / Q000494:pharmacology*; D003606:Dacarbazine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D004357:Drug Synergism; D005909:Glioblastoma / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D000077204:Temozolomide; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D003606:Dacarbazine; D002738:Chloroquine; D000077204:Temozolomide
keywords: Autophagy; Chloroquine; Glioma; Temozolomide; p53