Up‐regulation of Na+,K+‐ATPase α3‐isoform and down‐regulation of the α1‐isoform in human colorectal cancer

摘要

>We investigated expression levels of Na+,K+-ATPase α-isoforms and their ATPase activities in human colorectal cancer tissue and the accompanying normal mucosa. A decrease in expression of the α1-isoform protein was observed in all sampled cancer tissues compared with the normal mucosae. The level of ouabain (5 μM)-sensitive Na+,K+-ATPase activity in carcinomas was 81±5% that of in the normal mucosae. The mRNA expression of α2- and α4-isoforms was decreased in almost all the carcinoma samples. Interestingly, the expression level of the α3-isoform protein in the cancer tissue was higher than that of the normal mucosa. These results indicate that a decrease in the α1-isoform expression and an increase in the α3-isoform expression may be associated with colorectal cancer.