Alkaline Phosphatase Isoenzymes in Carcinoma Tissue of Gastro‐intestinal Tract

Abstract

The enzymological and immunological properties of alkaline phosphatase (ALP) isoenzymes in carcinoma tissues of the gastro‐intestinal tract were compared with those of purified human intestinal, placental and hepatic ALP's to investigate the gene expression of gastro‐intestinal cancer cells. The results were as follows: ALP obtained from carcinoma tissues of 77 patients was separated into 6 bands (ALPa, ALPb, ALPc, ALPd, ALPe and ALPf) by polyacrylamide‐gel disc electrophoresis. It was concluded that ALPa was similar in its enzymological and immunological properties to hepatic‐type ALP, ALPb was similar to placental‐type ALP (Regan ALP or Nagao ALP), ALPc to intestinal‐type ALP (metaplasia ALP), ALPd to hepatoma‐type ALP (Warnock's variant ALP), ALPe to intestinal‐type ALP except for electrophoretic mobility, and ALPf was similar to hepatic‐type ALP except for neuraminidase sensitivity. ALPb appeared in 16 out of 55 cases (29%) of gastric carcinoma, and 2 out of 21 cases (10%) of colonic carcinoma. ALPd appeared in 4 out of 55 cases (7%). ALPe appeared in 2 out of 55 cases (4%) of gastric, and 3 out o 21 cases (14%) of colonic carcinoma. ALPf appeared in 1 out of 55 cases (2%) of gastric, and 1 out of 21 cases (5%) of colonic carcinoma. These ALP isoenzymes (ALPb, ALPd, ALPe and ALPf) probably originate from the cancer cells themselves and may represent an abnormal gene expression of cancer cells in the process of onco‐developmental differentiation.