Epigenetic dysregulation of the death-associated protein kinase/p14/HDM2/p53/Apaf-1 apoptosis pathway in multiple myeloma.
OBJECTIVE
To study the role of gene promoter hypermethylation of the putative tumour suppressor genes involved in the death-associated protein (DAP) kinase/p14/HDM2/p53/Apaf-1 apoptosis pathway in multiple myeloma (MM).


METHODS
DNAs from 55 primary MM marrow samples and myeloma cell lines were analysed for aberrant promoter methylation of DAP kinase, p14 and Apaf-1 genes by methylation-specific polymerase chain reaction (MSP).


RESULTS
In the methylated positive control, the sensitivity of M-MSP for DAP kinase was 1 x 10(-3). Aberrant hypermethylation of DAP kinase was found in 29/55 (52.7%) primary MM samples, whereas hypermethylation of p14 or Apaf-1 was undetectable in any of the samples tested. 5-Azacytidine treatment of two myeloma cell lines, WL2 and HS-Sultan, led to de-methylation and re-expression of DAP kinase, thereby confirming gene silencing associated with promoter hypermethylation. Hypermethylation of DAP kinase did not correlate with age, sex, paraprotein subtype or Durie-Salmon stage, but negatively affected the overall survival.


CONCLUSIONS
Of the putative tumour suppressor genes in the DAP kinase/p14/HDM2/p53/Apaf-1 apoptosis pathway, only DAP kinase is frequently methylated in MM, which is associated with gene silencing and might be of prognostic significance. p14 and Apaf-1 were not methylated in MM.
Chim
Chor-Sang
CS
University Department of Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong, Hong Kong. jcschim@hku.hk
Liang
Raymond
R
Fung
Tsz-Kin
TK
Choi
Chi-Lung
CL
Kwong
Yok-Lam
YL
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D051017:Apoptosis Regulatory Proteins / Q000235:genetics*; D053477:Apoptotic Protease-Activating Factor 1 / Q000235:genetics; D001374:Azacitidine / Q000494:pharmacology; D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000235:genetics*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects; D004273:DNA, Neoplasm / Q000235:genetics; D064550:Death-Associated Protein Kinases; D044127:Epigenesis, Genetic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009101:Multiple Myeloma / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D009363:Neoplasm Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D011379:Prognosis; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D016019:Survival Analysis; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics
C506592:APAF1 protein, human; D000964:Antimetabolites, Antineoplastic; D051017:Apoptosis Regulatory Proteins; D053477:Apoptotic Protease-Activating Factor 1; D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D001374:Azacitidine