[Immunohistochemical study of collagen in gastric cancer tissue]

The distribution and localization of collagen types were studied immunohistochemically in resected tissues obtained from gastric cancer patients. The expression of transforming growth factor (TGF) -alpha, TGF-beta 1 and TGF-beta 2 on cancer cells as well as the aggregation of T lymphocytes in the cancer tissue were also studied, in order to determine the differences between differentiated and undifferentiated type cancer. The interstitial tissues of differentiated type cancer showed intense staining for types I and III collagen, while those of undifferentiated type cancer showed intense staining for types I and III collagen, in addition to the stronger staining for types IV, V and VI collagen. Characteristically, type IV collagen was intensely stained in the interstitium in 18 of 20 undifferentiated type cancer (90%), but was stained in only one of 15 differentiated type cancer (6%). CD 3+ T lymphocytes were aggregated in the interstitial tissue of both the tumors, where the density of CD 4+ cells and the ratio of CD 4 to CD 8 were significantly higher in undifferentiated type cancer than in differentiated type cancer. TGF-alpha was detected in cancer cells in 80% of the differentiated cases and in 45% of the undifferentiated cases. The staining of TGF-beta 1 was also detected in 80% of the undifferentiated cases, which was significantly higher than 47% in differentiated cases. There were no differences in the incidences of staining for TGF-beta 2 between differentiated (33%) and undifferentiated type cancer (40%). These results suggest that there exist different mechanisms in the regulation of collagen production between differentiated and undifferentiated types of gastric cancer.