δ-Aminolaevulinic acid-induced photodynamic therapy inhibits protoporphyrin IX biosynthesis and reduces subsequent treatment efficacy in vitro

Abstract

Summary Recently, considerable interest has been given to photodynamic therapy of cancer using δ-aminolaevulinic acid to induce protoporphyrin IX as the cell photosensitizer. One advantage of this modality is that protoporphyrin IX is cleared from tissue within 24 h after δ-aminolaevulinic acid administration. This could allow for multiple treatment regimens because of little concern regarding the accumulation of the photosensitizer in normal tissues. However, the haem biosynthetic pathway would have to be fully functional after the first course of therapy to allow for subsequent treatments. Photosensitization of cultured R3230AC rat mammary adenocarcinoma cells with δ-aminolaevulinic acid-induced protoporphyrin IX resulted in the inhibition of porphobilinogen deaminase, an enzyme in the haem biosynthetic pathway, and a concomitant decrease in protoporphyrin IX levels. Cultured R3230AC cells exposed to 0.5 mM δ-aminolaevulinic acid for 27 h accumulated 6.07 × 10 -16 mol of protoporphyrin IX per cell and had a porphobilinogen deaminase activity of 0.046 fmol uroporphyrin per 30 min per cell. Cells cultured under the same incubation conditions but exposed to 30 mJ cm -2 irradiation after a 3-h incubation with δ-aminolaevulinic acid showed a significant reduction in protoporphyrin IX, 2.28 × 10 -16 mol per cell, and an 80% reduction in porphobilinogen deaminase activity to 0.0088 fmol uroporphyrin per 30 min per cell. Similar effects were evident in irradiated cells incubated with δ-aminolaevulinic acid immediately after, or following a 24 h interval, post-irradiation. There was little gain in efficacy from a second treatment regimen applied within 24 h of the initial treatment, probably a result of initial metabolic damage leading to reduced levels of protoporphyrin IX. These findings suggest that a correlation may exist between the δ-aminolaevulinic acid induction of porphobilinogen deaminase activity and the increase in intracellular protoporphyrin IX accumulation.

Genetic Rescue of Leishmania Deficiency in Porphyrin Biosynthesis Creates Mutants Suitable for Analysis of Cellular Events in Uroporphyria and for Photodynamic Therapy

“…However, these mutants develop porphyria of modest levels with "background noises" apparently because of feedback regulation and transcriptional and allosteric control of their endogenous heme biosynthesis pathway. This observation was especially notable when ALA was used in attempt to increase porphyrin levels of tumor cells for photodynamic therapy (31)(32)(33). In contrast, xenotransgenic Leishmania with dysregulated expression of alad and pbgd responded proportionally to increasing levels of exogenous ALA. As a result, uroporphyria was developed in these cells, making it possible to follow the emergence, progression, and consequence of this event at the cellular level (Figs.…”

Fluorescence spectroscopy study of protoporphyrin IX metabolism level in cells

“…Protoporphyrin IX (PpIX) is an intermediate in the biosynthesis of heme, and it can be amassed because the conversion process into heme is slow 1, 2. The factors that control the biosynthesis and accumulation of PpIX are not yet completely understood 3, 4. Much of what we know on this topic came from studies of cancer cells, where the control of cell proliferation is disrupted.…”

In Vivo Pharmacokinetics of δ-Aminolevulinic Acid-Induced Protoporphyrin IX During Pre- and Post-Photodynamic Therapy in 7,12-Dimethylbenz(a)nthracene-Treated Skin Carcinogenesis in Swiss Mice: A Comparison by Three-Compartment Model†¶

“…In conclusion, Gibson et al observed a decreased rate of PpIX production after photoirradiation, and it was reported to be because of the decreased activity of porphobilinogen deaminase after photoirradiation (49). He et al reported increased levels of PpIX in two cell lines after PDT (50,51).…”