Expression of beclin-1, an autophagy-related protein, in gastric and colorectal cancers.
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.
Ahn
Chang Hyeok
CH
Department of Pathology, College of Medicine, The Catholic Unviersity of Korea, Seoul, Korea.
Jeong
Eun Goo
EG
Lee
Jong Woo
JW
Kim
Min Sung
MS
Kim
Sung Hee
SH
Kim
Sung Soo
SS
Yoo
Nam Jin
NJ
Lee
Sug Hyung
SH
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
D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; D008565:Membrane Proteins