Photosensitivity of DNA Replication and Respiration to Haematoporphyrin Derivative (Photofrin II) in Mammalian CV-1 Cells

Summary

DNA synthesis, as well as respiration, has been studied in CV-1 cells incubated with 5 or 25 µg/cm³ haematoporphyrin derivative Photofrin II (PF II) for 1, 24 or 48 h and then irradiated with various doses of UVA light (365 nm). The impairments of DNA synthesis increased with the duration of incubation with the porphyrin, its concentration and the dose of irradiation. The cellular consumption of oxygen is also inhibited by the treatment, but less severely.

In the case of the higher PF II concentration (25 µg/cm³), the impairment of DNA synthesis after illumination seems to be mainly due to ³HTdR transport inhibition. This effect can be related to plasma membrane damage as shown by lactate dehydrogenase leakage. At 5 µg/cm³ PF II, DNA synthesis inhibition is observed even after short exposure to PF II and light without ³HTdR transport impairment. In that case, DNA and/or mitochondrial photodamage may explain the inhibition.