Promoter hypermethylation analysis in myelodysplastic syndromes: diagnostic & prognostic implication.
OBJECTIVE
Myelodysplastic syndromes (MDS) are a heterogenous group of haematopoietic stem cell disorders that are multifactorial in their aetiology. Unique genetic alterations in combinations or in isolation account for a small fraction of MDS suggesting the epigenetic hypermethylation as a possible leading cause for MDS and its transformation to acute myelocytic leukaemia (AML). Therefore, in this study, promoter hypermethylation status of key cell cycle regulators was assessed as markers in MDS patients and association of hypermethylation with clinical progression of disease was also studied.


METHODS
Promoter hypermethylation analysis of five tumour associated genes namely p16, p15, MGMT, hMLH1 and E-cadherin were done for 41 MDS patient samples with its various subtype. The hypermethylation analysis was done by using semi-nested multiplex PCR.


RESULTS
Eighty per cent of (33/41) of the MDS samples were found to be methylated in any one of the four genes (p16, p15, MGMT and E-cadherin). The p15 methylation was found to be the most frequent 61 per cent (25/41), E-cadherin was methylated in 39 per cent (16/41) and p16 in 37 per cent (15/41) of the cases. MGMT gene showed a low 5 per cent (2/41) methylation whereas hMLH1 gene was not methylated in any one of the samples analysed.


CONCLUSIONS
Differential rate of methylation of the four genes (p16, p15, MGMT and E-cadherin) was observed in MDS samples. All the samples analysed showed the absence of a methylator phenotype in MDS. The methylation frequency of all these genes increased with the clinical severity of the MDS subtypes. Therefore, hypermethylation may be used as a diagnostic and prognostic tool in ascertaining the clinical severity of MDS.
Solomon
P R
PR
Department of Biochemistry, Centre for Advanced Studies in Functional Genomics, School of Biological Sciences, Madurai Kamaraj University, Madurai, India.
Munirajan
A K
AK
Tsuchida
Nobuo
N
Muthukumarasamy
Kottampatti
K
Rathinavel
Andiappan
A
Selvam
G S
GS
Shanmugam
G
G
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D018899:CpG Islands; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics; D045643:DNA Repair Enzymes / Q000235:genetics; D006801:Humans; D000070957:MutL Protein Homolog 1; D009190:Myelodysplastic Syndromes / Q000175:diagnosis / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D016133:Polymerase Chain Reaction; D011379:Prognosis; D011401:Promoter Regions, Genetic; D025521:Tumor Suppressor Proteins / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D000070957:MutL Protein Homolog 1; D045643:DNA Repair Enzymes