title: Expression of beclin-1, an autophagy-related protein, in gastric and colorectal cancers.
abstract: Autophagy plays important roles in both cell death and cell survival. Beclin-1, a key regulator of autophagy formation, has been considered as a haploinsufficient tumor suppressor. Loss of expression or point mutation could serve as a mechanism of loss of beclin-1 tumor suppressor function in cancers. However, our recent study revealed that point mutation of the beclin-1 gene is a rare event in common human cancers. In this study we investigated beclin-1 protein expression in 103 colorectal and 60 gastric carcinoma tissues by immunohistochemistry using a tissue microarray approach. In the cancers, expression of beclin-1 was detected in 95% of the colorectal carcinomas and 83% of the gastric carcinomas. In contrast, normal mucosal cells of both stomach and colon showed no or very weak expression of beclin-1. There was no significant association of beclin-1 expression with clinocopathologic characteristics, including invasion, metastasis and stage. The beclin-1 expression of colorectal and gastric cancers in the present study is quite in contrast to that of the breast cancers in the previous study, which showed a decreased beclin-1 expression in breast cancer cells compared to normal breast cells. Our data indicate that beclin-1 inactivation by loss of expression may not occur in colorectal and gastric cancers. Rather, increased expression of beclin-1 in the malignant colorectal and gastric epithelial cells compared to their normal mucosal epithelial cells suggests that neo-expression of beclin-1 may play a role in both colorectal and gastric tumorigenesis.
authors.affiliation: Department of Pathology, College of Medicine, The Catholic Unviersity of Korea, Seoul, Korea.
authors.forename: Chang Hyeok
authors.initials: CH
authors.lastname: Ahn
authors.forename: Eun Goo
authors.initials: EG
authors.lastname: Jeong
authors.forename: Jong Woo
authors.initials: JW
authors.lastname: Lee
authors.forename: Min Sung
authors.initials: MS
authors.lastname: Kim
authors.forename: Sung Hee
authors.initials: SH
authors.lastname: Kim
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Kim
authors.forename: Nam Jin
authors.initials: NJ
authors.lastname: Yoo
authors.forename: Sug Hyung
authors.initials: SH
authors.lastname: Lee
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis*; D001343:Autophagy / Q000502:physiology; D000071186:Beclin-1; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000096:biosynthesis*; D013274:Stomach Neoplasms / Q000378:metabolism* / Q000473:pathology; D046888:Tissue Array Analysis
chemical_list: D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; D008565:Membrane Proteins