title: Integrative genomic analysis of temozolomide resistance in diffuse large B-cell lymphoma.
abstract: OBJECTIVE
  Despite advances, there is an urgent need for effective therapeutics for relapsed diffuse large B-cell lymphoma, particularly in elderly patients and primary central nervous system (CNS) lymphoma. Temozolomide (TMZ), an oral DNA-alkylating agent routinely used in the therapy of glioblastoma multiforme, is active in patients with primary CNS lymphoma but the response rates are low. The mechanisms contributing to TMZ resistance are unknown.
  
  
  METHODS
  We undertook an unbiased and genome-wide approach to understand the genomic methylation and gene expression profiling differences associated with TMZ resistance in diffuse large B-cell lymphoma cell lines and identify mechanisms to overcome TMZ resistance.
  
  
  RESULTS
  TMZ was cytotoxic in a subset of diffuse large B-cell lymphoma cell lines, independent of MGMT promoter methylation or protein expression. Using Connectivity Map (CMAP), we identified several compounds capable of reversing the gene expression signature associated with TMZ resistance. The demethylating agent decitabine (DAC) is identified by CMAP as capable of reprogramming gene expression to overcome TMZ resistance. Treatment with DAC led to increased expression of SMAD1, a transcription factor involved in TGF-β/bone morphogenetic protein (BMP) signaling, previously shown to be epigenetically silenced in resistant diffuse large B-cell lymphoma. In vitro and in vivo treatment with a combination of DAC and TMZ had greater antilymphoma activity than either drug alone, with complete responses in TMZ-resistant diffuse large B-cell lymphoma murine xenograft models.
  
  
  CONCLUSIONS
  Integrative genome-wide methylation and gene expression analysis identified novel genes associated with TMZ resistance and demonstrate potent synergy between DAC and TMZ. The evidence from cell line and murine experiments supports prospective investigation of TMZ in combination with demethylating agents in diffuse large B-cell lymphoma.
authors.affiliation: Authors' Affiliations: Albert Einstein Cancer Center, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York.
authors.forename: Violetta V
authors.initials: VV
authors.lastname: Leshchenko
authors.forename: Pei-Yu
authors.initials: PY
authors.lastname: Kuo
authors.forename: Zewei
authors.initials: Z
authors.lastname: Jiang
authors.forename: Venu K
authors.initials: VK
authors.lastname: Thirukonda
authors.forename: Samir
authors.initials: S
authors.lastname: Parekh
mesh_terms: D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology* / Q000627:therapeutic use; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics / Q000378:metabolism; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D000077209:Decitabine; D004195:Disease Models, Animal; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D004357:Drug Synergism; D015870:Gene Expression; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D023281:Genomics; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy / Q000235:genetics*; D011401:Promoter Regions, Genetic; D000077204:Temozolomide; D014157:Transcription Factors / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: D018906:Antineoplastic Agents, Alkylating; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D000077209:Decitabine; D003606:Dacarbazine; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes; D001374:Azacitidine; D000077204:Temozolomide