Loss of expression of a new member of the DNAJ protein family confers resistance to chemotherapeutic agents used in the treatment of ovarian cancer.
Differential display-PCR between ovarian tumor cell lines and short-term cultures of normal ovarian epithelial cell brushings was used to isolate a differentially expressed transcript and its corresponding gene. The gene, which mapped to 13q14.1, has partial homology in the DNAJ domain to a number of proteins with a similar domain and was designated as methylation-controlled J protein (MCJ). MCJ has the highest similarity to a functionally undefined protein from Caenorhabditis elegans. MCJ is expressed as a 1.2-kb transcript in several adult tissues, with testis showing the highest level of expression. Expression of MCJ was absent in three of seven ovarian cancer cell lines. Similarly, expression analysis using semiquantitative reverse transcription-PCR indicated that 12 of 18 primary ovarian tumors examined had either a complete absence or lower levels of expression of this gene. 5-Aza-2'-deoxycytidine treatment of the OV202 cell line induced MCJ expression in a dose-dependent manner, implicating methylation in this induction. Loss of heterozygosity and methylation-specific PCR analysis revealed that the loss of MCJ expression in primary tumors and cell lines was attributable to deletion of one allele and methylation of the other. To assess the potential functional significance of MCJ down-regulation, the sensitivity of parental (MCJ-nonexpressing) and MCJ-transfected OV167 cells to antineoplastic agents was evaluated. MCJ expression was associated with enhanced sensitivity to paclitaxel, topotecan, and cisplatin, suggesting that MCJ loss may play a role in de novo chemoresistance in ovarian carcinoma. These observations raise the possibility that MCJ loss may: (a) have potential prognostic significance in ovarian cancer; and (b) contribute to the malignant phenotype by conferring resistance to the most commonly used chemotherapeutic agents for ovarian cancer.
Shridhar
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Division of Experimental Pathology, Mayo Clinic/Foundation, 200 First Street SW, Rochester, MN 55905, USA. shridhar.viji@mayo.edu
Bible
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Staub
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Avula
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Lee
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Kalli
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Huang
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Hartmann
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Kaufmann
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Smith
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D000595:Amino Acid Sequence; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001483:Base Sequence; D002874:Chromosome Mapping; D002945:Cisplatin / Q000494:pharmacology; D003001:Cloning, Molecular; D004273:DNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D000077209:Decitabine; D015536:Down-Regulation; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019008:Drug Resistance, Neoplasm; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D019656:Loss of Heterozygosity; D008969:Molecular Sequence Data; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism; D010091:Oximes; D017239:Paclitaxel / Q000494:pharmacology; D010879:Piperazines; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D019772:Topotecan / Q000494:pharmacology; D014162:Transfection; D014407:Tumor Cells, Cultured
D004273:DNA, Neoplasm; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D010091:Oximes; D010879:Piperazines; C070706:MCI 727; D000077209:Decitabine; D019772:Topotecan; D001374:Azacitidine; D017239:Paclitaxel; D002945:Cisplatin