MODIFICATION OF CHEMOTHERAPEUTIC EFFECTS ON L1210-CELLS USING HEMATOPORPHYRIN AND LIGHT

  • 1 January 1983
    • journal article
    • research article
    • Vol. 43  (11) , 5252-5257
Abstract
Tissue culture experiments were done to evaluate the possibility of modifying the response curves of phenylalanine mustard (LPAM) and actinomycin D on L1210 cells, using moderately toxic levels of photodynamic injury provided by light and hematoporphyrin (HP). Cells were incubated with HP at concentrations of 1-50 .mu.M for up to 48 h. Illumination was provided by fluorescent light (4 millwatts/cm2), filtered to remove all wavelengths outside of the range of 400-800 nm. When cells were incubated with 25 .mu.M HP in the dark for 24 h and then exposed to light for 1 h, there were reductions in cloning efficiencies of 30-80% compared to the dark-HP-treated controls. When LPAM (1-30 .mu.M) or actinomycin D (0.04-2.0 ng/ml) was incubated with cells for 1 h following HP treatment, with or without light exposure, the LPAM response curves indicated a synergistic response of photodynamic toxicity and chemotherapeutic toxicity (1 additional log). HP in the dark prior to and during LPAM exposure did not modify the LPAM response curve. The actinomycin D response curve was modified by prior HP and light treatment to indicate an additive effect of 1 additional log; a synergistic effect may be present in the range of 100-10% cloning efficiencies. The L1210-HP-light system offers possibilities for investigating the modification of chemotherapy effects.

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