title: Gene expression profiling predicts response to temozolomide in malignant gliomas.
abstract: Malignant gliomas are highly lethal neoplasms that cannot be cured with currently available therapies. Temozolomide (TMZ) is a recently introduced alkylating agent that has yielded significant benefits and become a key agent in the treatment of high-grade gliomas. However, its survival benefit remains unsatisfactory. Understanding the molecular basis of TMZ sensitivity/resistance is necessary for improving the treatment outcome by devising strategies that are able to circumvent primary drug resistance. We therefore combined the in vitro TMZ response with microarray gene expression data to identify genes that could potentially be used to predict the response of malignant gliomas to TMZ therapy. We first obtained the individual IC50 values for TMZ in seven malignant glioma cell lines (A-172, AM-38, T98G, U-87MG, U-138MG, U-251MG and YH-13) and then identified the genes whose expression correlated most highly with TMZ sensitivity employing a cDNA microarray. We present here a list of the most highly up-regulated and down-regulated genes which may be involved in conferring TMZ sensitivity/resistance in malignant gliomas, although most of the genes have not been implicated as a causal factor in the TMZ response except MGMT. We also demonstrated and confirmed the MGMT methylation status, quantitative MGMT mRNA levels, and MGMT protein expression levels in TMZ resistant glioma cells in vitro. Our results are thus consistent with previous studies and suggest that a dominant mechanism conferring sensitivity/resistance to TMZ exists in malignant glioma cells. Although the present study dose have several limitations, our reported candidate genes could represent not only potential molecular markers for TMZ sensitivity/resistance but also chemotherapy targets. Furthermore, the present study could provide a foundation for alternative therapeutic strategies including novel combination treatments that incorporate additional reagents directed at overcoming resistance to TMZ.
authors.affiliation: Department of Neurological Surgery, Nihon University School of Medicine, Itabashi-ku, Tokyo 173-8610, Japan. ayoshino@med.nihon-u.ac.jp
authors.forename: Atsuo
authors.initials: A
authors.lastname: Yoshino
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Ogino
authors.forename: Kazunari
authors.initials: K
authors.lastname: Yachi
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohta
authors.forename: Takao
authors.initials: T
authors.lastname: Fukushima
authors.forename: Takao
authors.initials: T
authors.lastname: Watanabe
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Katayama
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Norio
authors.initials: N
authors.lastname: Naruse
authors.forename: Emiko
authors.initials: E
authors.lastname: Sano
authors.forename: Kouhei
authors.initials: K
authors.lastname: Tsumoto
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use*; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000188:drug therapy / Q000235:genetics*; D045744:Cell Line, Tumor; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics; D045643:DNA Repair Enzymes / Q000235:genetics; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D020869:Gene Expression Profiling; D005910:Glioma / Q000188:drug therapy / Q000235:genetics*; D006801:Humans; D020128:Inhibitory Concentration 50; D020411:Oligonucleotide Array Sequence Analysis; D011379:Prognosis; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000077204:Temozolomide; D025521:Tumor Suppressor Proteins / Q000235:genetics
chemical_list: D018906:Antineoplastic Agents, Alkylating; D012333:RNA, Messenger; D025521:Tumor Suppressor Proteins; D003606:Dacarbazine; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes; D000077204:Temozolomide