Photodamage induced by zinc(II)-phthalocyanine to microtubules, actin, alpha-actinin and keratin of HeLa cells

We have studied the photosensitizing effects of zinc(II)-phthalocyanine (Zn Pc) on the cytoskeleton of HeLa cells using sublethal (10(-7) M, followed b y 1 or 3 min of red light to induce 20%, LD20, or 60%, LD60, cell death, re spectively) or lethal (5 x 10(-6) M and 15 min of irradiation, LD100) exper imental conditions. The immunofluorescent analysis of the cytoskeleton show ed a variable photodamage to microtubules (MT), actin microfilaments (AF) a nd intermediate filaments of keratin (KF), as well as on alpha -actinin, wh ich was dependent on treatment conditions. Both sublethal treatments induce d deep alterations on interphase and mitotic MT. The mitotic index increase d with time with the maximum at 18 h (12%) or 24 h (14%) after LD20 or LD60 , respectively. The alterations on AF and alpha -actinin were much more sev ere than those observed on KF at any evaluated time. With the exception of the KF, which remained partially organized, the MT and AF network was sever ely damaged by the lethal treatment. Western blot analysis for alpha -tubul in, G-actin and alpha -actinin from soluble and insoluble fractions confirm ed the results observed by immunofluorescence, thus indicating that these c ytoskeletal components are involved in cell damage and death by ZnPc photos ensitization.