Beclin-1 [E8]

Beclin-1 is an essential protein for the initiation of autophagy, the type II programmed cell death pathway. This 60 kDa protein is induced during autophagy, binds with additional autophagic proteins to regulate the formation of the autophagosome. While Beclin-1 is broadly expressed in most normal tissues, its expression was found to be weak in the normal gastric and colonic mucosa. In contrast, Beclin-1 was monoallelically deleted in approximately 40-75% of human breast, cervical, ovarian, and prostate cancers. Further, lower Beclin-1 mRNA levels were detected in glioblastoma compared to normal brain tissue from the same subject. Beclin-1 expression is correlative with protein immunoreactivity, and variable loss of beclin-1 expression was observed in cancer cells when compared with adjacent normal tissue, with notable exceptions in gastric and colorectal cancers. In 68% of hepatocellular carcinomas and 33% of esophageal squamous cell carcinomas, beclin-1 immunoreactivity was lost. Multiple studies have determined beclin-1 as an independent prognostic marker, where high expression of beclin-1 is associated with positive prognosis including higher disease-free and overall survival rates.