Molecular analyses of the mitotic checkpoint components hsMAD2, hBUB1 and hBUB3 in human cancer.
During the metaphase-anaphase transition, the spindle checkpoint prevents segregation of chromosomes if the spindle assembly is perturbed. Critical components of this checkpoint are the MAD and BUB families of proteins, which prevent the proteolysis of Pds1 and B cyclins, producing mitotic arrest. In the present study, we first intended to resolve the role of the hsMAD2 gene in human cancer by determining the potential presence of hsMAD2 mutations in 44 primary bladder tumors, 42 soft-tissue sarcomas and 10 hepatocellular carcinomas. The entire coding region of the hsMAD2 gene was analyzed using PCR-SSCP and sequencing. One of the bladder tumor samples showed a point mutation consisting of a transition, ATC-->GTC (Ile-->Val) in codon 190 of hsMAD2. However, no differences were found in the mitotic arrest between cells transfected with mutant and wild-type MAD2 cDNA. We also identified mobility shifts in hsMAD2 in both normal and tumor DNA in 3 bladder tumors, 3 soft-tissue sarcomas and 1 hepatocellular carcinoma, consistent with a polymorphism at codon 143, CCA-->CCG (Pro-->Pro). Another polymorphism was identified in a hepatocellular carcinoma case at codon 22, GAG-->GAA (Glu-->Glu). In addition, a subgroup of 67 primary tumors was analyzed by Southern blot hybridization. No deletion or visible re-arrangements were detected by comparing tumor and normal DNA band signals. Two other important components of the spindle mitotic checkpoint, hBUB1 and hBUB3, were also screened for mutations: hBUB1 in 43 bladder tumors and 9 bladder cell lines and hBUB3 only in the cell lines. Two polymorphisms were found in hBUB1 at positions 144, CAG-->CAA (Gln-->Gln) in 1 primary tumor and 1 bladder cell line, and 913 (ATC-->ATT, Ile-->Ile) in 1 primary tumor. We did not find sequence alterations in hBUB3. These results suggest that mutations of the hsMAD2, hBUB1 and hBUB3 genes are very rare in bladder tumors and that hsMAD2 alterations are also infrequent in soft-tissue sarcomas and hepatocellular carcinomas.
Hernando
E
E
Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
Orlow
I
I
Liberal
V
V
Nohales
G
G
Benezra
R
R
Cordon-Cardo
C
C
D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000235:genetics*; D017353:Gene Deletion; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics; D064246:Mad2 Proteins; D009154:Mutation; D000075223:Poly-ADP-Ribose Binding Proteins; D011110:Polymorphism, Genetic; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins; D012509:Sarcoma / Q000235:genetics; D012983:Soft Tissue Neoplasms / Q000235:genetics; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000235:genetics
C489444:BUB3 protein, human; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D004273:DNA, Neoplasm; C577697:MAD2L1 protein, human; D064246:Mad2 Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D011506:Proteins; D012097:Repressor Proteins; D011494:Protein Kinases; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases