SHIMOMURA Yoshiharu Nagoya Institute of Technology, Professor, 工学部, 教授 (30162738)
NIWA Yasumasa School of Medicine, Assistant, 医学部, 助手 (20283442)
ARISAWA Tomiyasu School of Medicine, Assistant, 医学部, 助手 (50273230)
|Budget Amount *help
¥3,500,000 (Direct Cost : ¥3,500,000)
Fiscal Year 1998 : ¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1997 : ¥1,900,000 (Direct Cost : ¥1,900,000)
A protooncogene c-myc is a transcription factor, which regulates expression of other genes important for cell proliferation and differentiation. An isozyme of branched-chain aminotransferase (BCAT), cytosolic BCAT (BCATc), was reported as one of the target genes of c-myc and it was reported that overexpression of c-myc are observed in 30-90% gastric cancer tissues. From these background, we investigated a correlation between expression of c-myc and BCATc in human gastric cancer cells and tissues. Expression of another isoenzyme of BCAT, mitochondrial BCAT (BCATm), was also examined in the cells and tissues. We first examined the expression of c-myc and two BCATs in two gastric cancer cell lines, MKN45 and KATO III, by the polymerase-chain reaction method. In MKN45, overexpression of c-myc, but not BCATc, was detected. On the other hand, c-myc expression was lower in KATO III than in MKN45, but BCATc expression was at the greater extent and BCATm expression was suppressed. We second examined their expression in gastric mucosal tissues with cancer obtained from 9 patients and mucosal tissues with gastritis from 8 patients as control. In the 4 cases of gastric cancer, BCATc overexpression was detected and c-myc overexpression was observed in 5 cases. However, there is no correlation between expression of c-myc and BCATc in these cases. These results suggest that expression of BCATc in gastric cancer cells is regulated in a manner independent of expression of c-myc.