OVER-EXPRESSION OF ICAM-1, VCAM-1 AND ELAM-1 MIGHT INFLUENCE TUMOR PROGRESSION IN COLORECTAL-CANCER

Adhesion molecules might play a role in tumor progression, We investig ated expression of the adhesion molecules ICAM-1, VCAM-1 and ELAM-1 in 24 primary colorectal carcinomas using immuno-histochemistry and Nort hern blot analysis, Normal colonic tissue from the same patients serve d as controls, ICAM-1 immunostaining was restricted to the intercellul ar matrix and vascular endothelial cells. The vast majority of normal tissue samples revealed only faint ICAM-1 immunoreactivity. However, m oderate to strong immunostaining was found in 86% of cancerous section s, The ICAM-1 immunoreaction was more intense in well-differentiated c arcinomas as well as in the adenomatous parts and transition zones of cancers, Similarly, the cancers exhibited markedly enhanced VCAM-1 and ELAM-1 immunostaining in the endothelial cells of small blood vessels . The intense vascular immunostaining by ICAM-1 and YCAM-1 was associa ted with a strong presence of CD3-positive T lymphocytes, whereas ELAM -1 immunoreactivity did not correlate with round cell infiltration. On Northern blot analysis, ICAM-1, VCAM-1 and ELAM-1 mRNA Bevels were in creased in 67%, 57% and 63% of carcinomas, respectively, in comparison with normal tissue samples, Densitometric analysis of Northern blots revealed an increase in ICAM-1 by 2.1-fold, an increase in VCAM-1 by 3 .4-fold and an increase in ELAM-1 by 2.2-fold in cancerous :issues com pared to normal controls, Over-expression of ICAM-1 might prevent cell -cell disruption and, hence, tumor dissemination, Furthermore, over-ex pression of ICAM-1 and VCAM-1, but not ELAM-1, might favor host anti-t umor defense by trafficking of lymphocytes. (C) 1998 Wiley-Liss, Inc.