Expression and clinical significance of Beclin-1 in gastric cancer tissues of various clinical stages.

Autophagy is a common phenomenon in cancer metabolism. However the mechanism and guiding significance of autophagy in the development of gastric cancer has remained to be elucidated. In the present study, 75 gastric cancer tissue specimens were collected at The China Japan Union Hospital of Jilin University (Changchun, China). Of these samples, 16 cases were stage 1, 40 stage 2 and 19 stage 3. Polymerase chain reaction and western blotting were used to detect the messenger RNA and protein expression of Beclin-1, a significant protein associated with cellular autophagy. It was found that expression of Beclin-1 in cancer tissues from stages 1 and 2 was higher, while in stage 3 cases levels were significantly lower than that of adjacent normal tissues. In addition, the infiltration of inflammatory cytokines was also increased in stage 1 and 2 cases. In vitro studies revealed that following stimulation with interferon-γ (IFN-γ), autophagy-associated proteins Beclin-1 and microtubule-associated protein light chain 3 were activated. Furthermore, activation of autophagy inhibited xenograft growth in nude mice. The results of these in vivo and in vitro experiments indicated that in gastric cancer tissues, autophagy was downregulated following the development of cancer tissue and that inflammation may be a significant factor in this process. IFN-γ may be involved in the mediation of this process and thus present a novel target for the treatment of gastric cancer.