Mutation analysis of hBUB1, human mitotic checkpoint gene in multiple carcinomas.

hBUB1 is a human homolog of yeast mitotic check point gene that plays an important role in chromosome segregation. Recently mutations of hBUB1 were reported in colorectal cancer cell lines, indicating that inactivation of this gene could be directly involved in aneuploidy in human carcinoma cells. To obtain information of the magnitude of hBUB1 inactivation in multiple carcinomas, we examined mutations in 59 multiple carcinoma cell lines showing single base alteration, however, there was no mutation of hBUB1 with amino acid change in these carcinomas. There were four silent mutations at codon 93, codon 735, codon 430 and codon 98 in KYSE190, TE8 esophageal carcinoma cells, KATOIII gastric carcinoma cells and 697 B cell leukemia cells, respectively. Two candidates of mutation were identified in TE3 esophageal carcinoma cells and 697 B cell leukemia cell line at codon 9 and codon 285, respectively. This result suggests that the inactivation of hBUB1 may be very rare in human carcinomas, or restricted to certain cell lines of colorectal carcinomas.