The Effects of 5-Aminolevulinic Acid Esters on Protoporphyrin IX Production in Human Adenocarcinoma Cell Lines¶

Abstract

Photodynamic diagnosis (PDD) and photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PPIX) is an interesting approach to detect and treat dysplasia and early cancers in the gastrointestinal tract. Because of low lipophilicity resulting in poor penetration across cell membranes, high doses of ALA should be administered in order to reach clinically relevant levels of PPIX. One way of increasing PPIX accumulation is derivatization of ALA into a more lipophilic molecule. In our in vitro study, different esterifications of ALA were investigated to analyze the effects on PPIX accumulation in human adenocarcinoma cell lines. For systematic analysis of cell type-specific PPIX accumulation, three human adenocarcinoma cell lines (SW480, HT29 and CaCo2) and a fibroblast cell line (CCD18) were tested. 3-(4,5-Dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) assays were performed to ensure that the ALA esters showed no cellular dark toxicity. Different concentrations (ranging from 0.012 to 0.6 mmol/L, 3 h) and incubation times (5, 10, 30, 180 min; 0.12 mmol/L) were examined. PPIX accumulation was measured using flow cytometry. ALA esters, especially ALA-hexylester and ALA-benzylester, induced significant higher PPIX levels in adenocarcinoma cell lines when compared with ALA and may be promising candidates for PDT and PDD.

Influence of protoporphyrin IX amino acid substituents on affinity to human breast adenocarcinoma MCF-7 cells

“…Our data concerning accumulation of PP(Arg)2 after longer periods are consistent with data obtained using other human adenocarcinoma cell lines from different human (colonic) cell lines (Brunner et al 2001). Furthermore, accumulation in colonic cell lines was studied using flow cytometry, which has some limitations.…”

“…Based on this result, we can state that accumulation begins during first 3 min and that it originates from the cell membranes. In an earlier report, Brunner et al (2001) showed that PP IX is present within the cells incubated for 5 min. In our experiments, confocal microscopy allowed us to determine the time more precisely.…”

Efficacy of 5-aminolevulinic acid-mediated photodynamic therapy using light-emitting diodes in human colon cancer cells

“…In dermatology, multicenter randomized controlled studies have demonstrated the high efficacy of topical ALA-PDT for actinic keratosis, Bowen’s disease and superficial basal cell carcinoma (17–19). Although certain reports have addressed the efficacy of ALA-PDT in CRC cells (20,21), these were limited to in vitro studies. Therefore, the objective of this study was to investigate the antitumor effect of ALA-PDT using LEDs for the treatment of CRC cells in a xenograft mouse model.…”

Anticancer Drugs Acting via Radical Species

“…This compound is normally employed in the form of ester prodrugs, which have an improved absorption when administered as creams. 147 Some of these esters include methyl 5-aminolevulinate (MAOP), Metvix ® , and hexyl 5-aminolevulinate (Hexvix ® , Cysview ® ). Protoporphyrin IX thus generated is selectively accumulated in some tumors because of their accelerated metabolism, which includes a faster processing of ALA.…”