Mycophenolate mofetil modulates adhesion receptors of the beta1 integrin family on tumor cells: Impact on tumor recurrence and malignancy

Abstract

Background: Tumor development remains one of the major obstacles following organ transplantation. Immunosuppressive drugs such as cyclosporine and tacrolimus directly contribute to enhanced malignancy, whereas the influence of the novel compound mycophenolate mofetil (MMF) on tumor cell dissemination has not been explored. We therefore investigated the adhesion capacity of colon, pancreas, prostate and kidney carcinoma cell lines to endothelium, as well as their beta 1 integrin expression profile before and after MMF treatment. Methods: Tumor cell adhesion to endothelial cell monolayers was evaluated in the presence of 0.1 and 1 μM MMF and compared to unstimulated controls. beta1 integrin analysis included alpha 1 beta 1 (CD49a), alpha2beta 1 (CD49b), alpha3beta 1 (CD49c), alpha4beta 1 (CD49d), alpha5beta 1 (CD49e), and alpha6beta 1 (CD49f) receptors, and was carried out by reverse transcriptase-polymerase chain reaction, confocal microscopy and flow cytometry. Results: Adhesion of the colon carcinoma cell line HT-29 was strongly reduced in the presence of 0.1 μM MMF. This effect was accompanied by down-regulation of alpha3beta 1 and alpha6beta 1 surface expression and of alpha3beta 1 and alpha6beta 1 coding mRNA. Adhesion of the prostate tumor cell line DU-145 was blocked dose-dependently by MMF. In contrast to MMF's effects on HT-29 cells, MMF dose-dependently up-regulated alpha 1 beta 1, alpha2beta 1, alpha3beta 1, and alpha5beta 1 on DU-145 tumor cell membranes. Conclusion: We conclude that MMF possesses distinct anti-tumoral properties, particularly in colon and prostate carcinoma cells. Adhesion blockage of HT-29 cells was due to the loss of alpha3beta 1 and alpha6beta 1 surface expression, which might contribute to a reduced invasive behaviour of this tumor entity. The enhancement of integrin beta 1 subtypes observed in DU-145 cells possibly causes re-differentiation towards a low-invasive phenotype. © 2005 Engl et al; licensee BioMed Central Ltd.