Expression of programmed cell death 4 (PDCD4) related to tumor differentiation in human cancers of digestive system

OBJECTIVE:To examine the expression of PDCD4 protein in some digestive cancers including gastric, colorectal and pancreatic cancers, and investigated the correlation between the expression of PDCD4 protein and the clinicopathological backgrounds. METHODS: PDCD4 protein expression in fresh cancer specimens and adjuvant non-cancerous tissues was detected by Western blot with PDCD4 specific antibody. Immunohistochemistry was used to examine the expression of PDCD4 protein in the paraffin embedded ones including the corresponding non-cancerous tissues. The correlations of PDCD4 expression with clinicopathological data were analyzed. RESULTS: The expression of PDCD4 protein was significantly lower in cancers than that in non-cancerous tissues detected by Western blot and immunohistochemistry examination. Furthermore, even in tumor tissues, the expression of PDCD4 in well differentiated cancers was significantly elevated compared with the moderately or poorly differentiated ones, indicating that PDCD4 may be associated with the carcinogenesis and cancer development. There was no relationship between PDCD4 expression and other clinicopathological parameters including sex, age and clinical stage status. CONCLUSIONS: The expression of PDCD4 protein is down regulated in cancers in comparison with the non-cancerous tissues, and is associated with tumor differentiation, up-regulating PDCD4 expression may induce the differentiation and apoptosis of tumor cells to inhibit tumorigenesis and tumor progression.