Expression of the E2F family in human gastrointestinal carcinomas.

The E2F family of transcription factors plays a key role in the control of cell-cycle progression. Some family members may act as oncogenes, others as tumor-suppressor genes. The genetic changes and the expression of E2F-1 and -3 were examined in human gastric and colorectal carcinomas by Southern, Northern and Western blots. Gene amplification of E2F-1 was detected in 4% (1/23) of gastric carcinomas and 25% (3/12) of the colorectal carcinomas. Increased expression of E2F-1 mRNA was observed in 40% (12/30) of the gastric carcinomas and in 60% (3/5) of the colorectal carcinomas in comparison with the corresponding non-neoplastic mucosa. Over-expression of E2F-1 protein was confirmed in many of the gastric carcinomas. In contrast, expression levels of E2F-3 mRNA were lower in 70% (21/30) of the gastric carcinomas and in 20% (1/5) of the colorectal carcinomas than in their corresponding normal counterparts, while gross alteration of the E2F-3 gene was not detected. These results suggest that gene amplification and anomalous expression of the E2F gene may permit development of gastrointestinal carcinomas.