MODULATION OF COLONIC-CANCER CELL ADHESIVENESS BY HEMATOPORPHYRIN DERIVATIVE PHOTODYNAMIC THERAPY

Haematoporphyrin derivative photodynamic therapy (HPD-PDT) induces dam age of plasma membranes and other cellular targets. This damage could modify the adhesiveness of cancer cells, which is an important paramet er in cancer metastasis. We studied the effect of HPD alone and HPD in cubation followed by argon laser light on the adhesiveness of progress ive (PROb) or regressive (REGb) cancer cells of the same colonic origi n. Adhesiveness was studied on plastic or endothelial cell monolayers (ECMs). In the absence of treatment, both PROb and REGb cells adhered better on plastic than on ECs. HPD alone and HPD-PDT induced toxicity proportional to the HPD dose. HPD-PDT increased the adhesiveness rate of both cell lines on plastic and decreased adhesiveness to ECs. HPD-P DT of ECMs increased adhesiveness but only for HPD doses giving at lea st 50% cell death. HPD alone and HPD-PDT of culture media led to an in significant decrease in the cell adhesiveness to ECMs. As cells which are more metastatic are also more adherent, a decreased adhesiveness t o ECMs after HPD-PDT suggests that PDT is a safe treatment considering metastasis.