Protein Kinase C isozymes in colon carcinogenesis

Decreased expression of protein kinase C (PKC)-δ can induce colonic tumours, but the effect of increased expression and the underlying molecular mechanisms remain unknown. In June Gastroenterology Sonia Cerda and colleagues from the University of Chicago show that increased expression of PKC-δ inhibits anchorage-dependent and -independent growth, while inducing cellular differentiation and limiting survival in human colon cancer cell lines.

Cerda et al used CaCo-2 colon cancer cells and established stable transfectants with cDNA coding for full length PKC-δ. They employed 2 different Zn2⁺-inducible metallothionein eukaryotic expression vectors and observed the effect of alterations in the expression of PKC-δ on the neoplastic cells. Results showed that increased expression of PKC-δ decreased anchorage-dependent growth and induced arrest in the G0/G1 phase of the cell cycle. In addition, overexpression of PKC-δ caused a 2-fold increase in apoptosis of CaCo-2 cells (Gastroenterology 2001, 120:1700-1712).

This suggests that alterations in...