Aim: Since atherosclerosis was recognized as an inflammatory disease in 1990, the infiltration of macrophages and T lymphocytes has been reported to be predominant in human atherosclerotic lesions. Although adventitis accompanying atherosclerosis was also described in many reports, it is still unclear whether T lymphocytes or B lymphocytes are predominant in the adventitis. In this study, the authors immunohistochemically investigated the correlation between the transition of infiltrating inflammatory cells in the adventitia with atherosclerosis and the type of coronary atherosclerosis. Methods: Sixty-four coronary atherosclerotic lesions from a surgical specimen and 47 autopsy cases were used for immunohistochemical study of CD45RO, CD20, CD68 and others. Atherosclerosis was classified into type , , , according to the 1995 AHA classification.

Caspase-8 and caspase-9 play crucial roles in the extrinsic and intrinsic apoptotic pathways, respectively. The nuclear translocation of apoptosis-inducing factor (AIF) is involved in caspase-independent apoptosis. Microtubule-associated protein 1 light chain 3 (LC3) plays a pivotal role in autophagy. In the present study, we analyzed the expression of cleaved caspase-8 (CC8), cleaved caspase-9 (CC9), AIF, and LC3 in 160 gastrointestinal adenocarcinomas. The nuclear expression of AIF was rare. The expression of CC8 in gastric and colorectal adenocarcinomas did not differ, whereas the percentage of CC9-positive tumors in gastric adenocarcinomas was significantly higher than in colorectal adenocarcinomas. In contrast, the percentage of LC3-positive tumors in gastric adenocarcinomas was significantly lower than in colorectal adenocarcinomas. CC8 and CC9 occasionally co-existed in the same tumor cells in gastric adenocarcinoma. However, LC3-positive tumor cells in colorectal adenocarcinomas were constantly negative for CC8. No correlation was identified between the expression of any markers and clinicopathological parameters. These results suggest that different cell death pathways are activated in a manner that depends upon the primary site and cell type. The extrinsic and intrinsic apoptotic pathways may be mutually regulated in gastric adenocarcinomas. Also, autophagy may function as a cellular guardian to avoid apoptosis in colorectal adenocarcinomas.

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Lack of apoptosis is a key factor in carcinogenesis and tumor progression. Survivin is a member of the inhibitor of apoptosis protein (IAP) family. Second mitochondria-derived activator of caspases/direct inhibitor of apoptosis-binding protein with low pI (Smac/DIABLO) is an antagonist of IAPs. Recently, Smac/DIABLO was identified as a potent therapeutic target. However, the clinical significance of Smac/DIABLO in gastrointestinal carcinomas remains unclear. In the present study, Smac/DIABLO expression was analyzed by immunohistochemistry in 72 gastric adenocarcinomas and 78 colorectal adenocarcinomas. The expression of Smac/DIABLO was significantly higher in colorectal carcinoma than in gastric carcinoma. Additionally, a correlation was found between the expression of Smac/DIABLO and nuclear survivin in well- to moderately-differentiated colorectal adenocarcinomas (r=0.245; P<0.01). Based on these results, it was hypothesized that gastric and colorectal carcinomas differ in the level of Smac/DIABLO expression. Our previous studies revealed that the expression of cleaved caspase-9 was significantly lower in colorectal carcinoma than in gastric carcinoma (P<0.0001). Conversely, the expression levels of microtubule-associated protein 1 light chain 3 (LC3), an autophagy marker, and survivin were significantly higher in colon cancer than in gastric cancer (P<0.0001 and P<0.01, respectively). Taken together, these results indicate that not only LC3 and survivin expression, but also Smac/DIABLO expression, are significantly higher in colorectal carcinoma than in gastric carcinoma. We hypothesize that the analysis of Smac/DIABLO, survivin and LC3 expression in colorectal carcinoma is likely to aid cancer therapy due to the involvement of these markers in apoptosis and/or autophagy.