Effect of Human Colorectal Carcinogenesis on the Neural Cell Adhesion Molecule Expression and Polysialylation

Abstract

Objective: Although downregulation of neural cell adhesion molecule (NCAM) has been correlated with poor prognosis in colorectal cancer (CRC), it is also possible that colon cancer spreading comes from reducing tumor cell adhesion through NCAM polysialylation, as occurs in lung carcinoma or Wilms’ tumor. Methods: To prove this hypothesis, we have performed a prospective study on tumor and control specimens from 39 CRC patients, which were immunostained for NCAM and PSA (polysialic acid) expression. Results: Tumor versus control expression of NCAM and PSA epitopes in tissue specimens, as well as correlation between tumor expression and clinicopathological features, were statistically analyzed. Results showed a low constitutive expression of NCAM and PSA (PSA-NCAM) in control tissue, which reached a statistically significant increase in the tumor tissue. Likewise, the presence and number of lymph node metastases at surgery were correlated with NCAM expression and PSA/NCAM coexpression. Conclusions: These data highlight the importance of taking into account PSA-associated epitopes when dealing with NCAM cell expression studies in tumor development and progression. The analysis of PSA and NCAM expression in CRC suggests a new way, other than downregulation of NCAM, in order to escape contact inhibition and promote cell tumor spreading in colorectal cancer.