[Biochemical study on interstitial proteins of human gastric cancer tissue with special reference to cross-linking amino acids of collagen and elastin].

The present study was undertaken to examine malignant alterations of collagen and elastin in human stomach cancer. Results of the study are as follows: 1. Content of hydroxyproline which in characteristic amino acid in collagen was elevated in stomach cancer tissues of Bormann types I to IV as compared to that of the uninvolved stomach. 2. When hydroxyproline content in stomach cancer of type IV (scirrhous) was compared to that in other types (I to III) of the cancer, the content in scirrhous was significantly elevated compared with that in cancers of other types, in terms of dry weight of whole tissue, number of cancer cells, and of insoluble proteins which are rich in collagen and elastin. However, when hydroxyproline was determined on two histological layers (mucosa plus submucosa layer and muscular plus serosa layer) separated from the involved and uninvolved stomach tissues, no significant difference in hydroxyproline content was observed between the scirrhous and non-scirrhous cancers. These observations may imply that an increased collagen synthesis in the scirrhous occurs in many layers of stomach tissue but is not restricted in a particular layer. 3. Non-reducing cross-link amino acids of collagen, pyridinoline and histidinoalanine, were assayed on the involved and uninvolved tissues. Pyridinoline content was higher in stomach cancers of Bormann types I to IV, while no significant difference of histidinoalanine content was found. These observations suggest that there is an increased cross-linking of collagen in stomach cancer. 4. Elastin concentration in stomach cancer was determined through the assay of desmosine and isodesmosine which are specific cross-link amino acids in elastin. The contents of these amino acids was increased in stomach cancer tissues of types I to IV as compared with that in the uninvolved tissue. 5. A ratio of desmosine plus isodesmosine to hydroxyproline was higher in the involved stomach than was in the uninvolved, suggesting that increased elastinosis exceeds collagenosis in stomach cancer.