Modulation of colonic cancer cell adhesiveness by haematoporphyrin derivative photodynamic therapy.

Haematoporphyrin derivative photodynamic therapy (HPD-PDT) induces damage of plasma membranes and other cellular targets. This damage could modify the adhesiveness of cancer cells, which is an important parameter in cancer metastasis. We studied the effect of HPD alone and HPD incubation followed by argon laser light on the adhesiveness of progressive (PROb) or regressive (REGb) cancer cells of the same colonic origin. 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-PDT of ECMs increased adhesiveness but only for HPD doses giving at least 50% cell death. HPD alone and HPD-PDT of culture media led to an insignificant decrease in the cell adhesiveness to ECMs. As cells which are more metastatic are also more adherent, a decreased adhesiveness to ECMs after HPD-PDT suggests that PDT is a safe treatment considering metastasis.