Photosensitization of Wi26-VA4 transformed human fibroblasts by low density lipoprotein loaded with the anticancer porphyrin mixture photofrin II: evidence for endoplasmic reticulum alteration.

Wi26 VA4 cells (SV40-transformed human lung fibroblasts) were incubated with low density lipoprotein (LDL) loaded with the anticancer porphyrin mixture photofrin II (P2). After labelling with 51Cr sodium chromate, cells were exposed to near UV light. After light exposure, kinetics of 51Cr release by cells were studied as a probe of cell damage. The activity of acyl-coenzyme A:cholesterol-O-acyltransferase, a key enzyme of cholesterol metabolism localized in endoplasmic reticulum (ER), was decreased as a function of the irradiation time in cells pre-incubated with P2-LDL. This result suggests that ER alteration occurred during cell photosensitization by P2-LDL.