EXPRESSION OF A NOVEL BCL-2 RELATED GENE, BFL-1, IN VARIOUS HUMAN CANCERS AND CANCER CELL-LINES

The expression of Bfl-1 gene, a novel Bcl-2 related gene, was determin ed by Northern blot analysis using a radiolabeled cDNA specific for Bf l-1 gene in 82 surgically resected tissue specimens of 28 gastric canc ers, 15 colon cancers, nine breast cancers, eight bone and soft tissue sarcomas, five ovarian cancers, nine colon adenomas and eight gastric adenomas. A high rate of expression was observed in gastric and colon cancer, at 86 and 93%, respectively. In breast cancer, bone and soft tissue sarcoma and ovarian cancer the expression rare was 33, 25 and 4 0%, respectively. In stomach cancer, the expression rate of Bfl-1 gene in metastatic lymph nodes was 82%, which was higher than 50% of the p rimary sites (p <0.02). The intensity of RNA bands of the gastric canc er specimens was compared according to the stage, demonstrating that t here was no difference in the expression levels of Bfl-1 gene between the stages in both primary sites and metastatic lymph nodes. Bfl-1 gen e was expressed in three (33%) out of nine adenomas of the colon, whil e it was not detected in all eight gastric adenomas. We also examined the RNA expression of Bfl-1 gene in 22 human cancer cell lines consist ing of five stomach cancer, four squamous cell carcinoma, three lung c ancer three cervical cancer; two colon cancel; two brain cancer, two l eukemia and one osteosarcoma cell lines. Bfl-1 gene band was detected in one (5%) cervical cancer cell line, SiHa. The results of cancel tis sue specimens indicate that Bfl-1 gene may play an important role in c arcinogenesis of human cancers and may be involved in a relatively ear ly phase of the adenoma-carcinoma sequence in colon cancel-development . However, the mechanism responsible for the very low rate of expressi on in established cell lines is not clearly understood and further inv estigation is necessary to clarify the mechanism involved.