title: Preferential loss of mismatch repair function in refractory and relapsed acute myeloid leukemia: potential contribution to AML progression.
abstract: Acute myeloid leukemia (AML) is an aggressive hematological cancer. Despite therapeutic regimens that lead to complete remission, the vast majority of patients undergo relapse. The molecular mechanisms underlying AML development and relapse remain incompletely defined. To explore whether loss of DNA mismatch repair (MMR) function is involved in AML, we screened two key MMR genes, MSH2 and MLH1, for mutations and promoter hypermethylation in leukemia specimens from 53 AML patients and blood from 17 non-cancer controls. We show here that whereas no amino acid alteration or promoter hypermethylation was detected in all control samples, 18 AML patients exhibited either mutations in MMR genes or hypermethylation in the MLH1 promoter. In vitro functional MMR analysis revealed that almost all the mutations analyzed resulted in loss of MMR function. MMR defects were significantly more frequent in patients with refractory or relapsed AML compared with newly diagnosed patients. These observations suggest for the first time that the loss of MMR function is associated with refractory and relapsed AML and may contribute to disease pathogenesis.
authors.affiliation: Department of Toxicology, University of Kentucky College of Medicine, Lexington, KY 40536, USA.
authors.forename: Guogen
authors.initials: G
authors.lastname: Mao
authors.forename: Fenghua
authors.initials: F
authors.lastname: Yuan
authors.forename: Kimberly
authors.initials: K
authors.lastname: Absher
authors.forename: C Darrell
authors.initials: CD
authors.lastname: Jennings
authors.forename: Dianna S
authors.initials: DS
authors.lastname: Howard
authors.forename: Craig T
authors.initials: CT
authors.lastname: Jordan
authors.forename: Liya
authors.initials: L
authors.lastname: Gu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D019175:DNA Methylation; D053843:DNA Mismatch Repair; D005260:Female; D006801:Humans; D007223:Infant; D015470:Leukemia, Myeloid, Acute / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein / Q000096:biosynthesis / Q000235:genetics*; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012008:Recurrence
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein