Studies on function of P-glycoprotein in photodynamic therapy of endometriosis
Maria Wołuń-Cholewa1, Krzysztof Szymanowski, Mirosław Andrusiewicz
1Department of Cell Biology, Poznan University of Medical Sciences, Poznań, Poland. doskon@amp.edu.pl
Objective:
The aim of the present study was to examine whether the effects of endometriosis-targeted photodynamic therapy (PDT), dependent on 5-aminolevulinic acid (ALA), rely on the presence of P-glycoprotein (P-gp), which is regarded as constituting one of the causes of multidrug resistance phenomenon.
Background:
The significance of the undertaken studies reflects the complete absence of reports related to the modulation of P-gp activity and efficacy of PDT in patients with endometriosis.
Materials And Methods:
Tissue samples of normal endometria were obtained from eight women after hysterectomy who were diagnosed with cervical intra-epithelial neoplasia. Fragments of ovarian endometriosis were obtained from 15 women. Epithelial cells were isolated from the material and in in vitro conditions were preincubated with P-gp blocker-verapamil-before ALA-PDT. The cytotoxicity was evaluated using the XTT test, allowing us to estimate cell growth inhibition. Statistical analysis of the results involved the nonparametric Wilcoxon paired rank test and the Mann-Whitney U-test using the Statistica v5 software (p < 0.05). In parallel, P-gp presence in the analyzed material was evaluated using immunohistochemistry.
Results:
In normal endometrial epithelium, verapamil was shown to intensify phototoxic effects at 2 and 4 mmol/L ALA (p < 0.05). In endometriotic epithelium, such intensification was noted in all examined concentrations of ALA (p < 0.001). Moreover, the ectopic epithelial cells were more sensitive than eutopic epithelial cells to PDT upon ALA alone, as well as after preincubation with verapamil. Immunohistohemical analysis allowed us to demonstrate the absence of glycoprotein P in normal endometrium. In endometriosis, P-gp was localised in both the epithelium and the stroma of the examined material.
Conclusion:
Phototoxic effects could be amplified in epithelial cells of endometriotic foci by appropriate action of verapamil and 5-aminolevulinic acid.
Insights
Photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA) shows enhanced efficacy in endometriosis treatment. Verapamil, a P-glycoprotein (P-gp) blocker, amplifies PDT effects by increasing sensitivity of endometriotic cells.
Area of Science:
- Gynecology
- Photodynamic Therapy
- Cancer Biology
Background:
- Endometriosis is a condition with limited treatment options.
- P-glycoprotein (P-gp) is implicated in multidrug resistance.
- The role of P-gp in endometriosis PDT efficacy is unexplored.
Purpose of the Study:
- To investigate if P-glycoprotein (P-gp) presence affects 5-aminolevulinic acid (ALA)-based photodynamic therapy (PDT) for endometriosis.
- To determine if P-gp blockers can enhance PDT efficacy in endometriosis treatment.
Main Methods:
- Endometrial and endometriosis tissue samples were collected.
- Epithelial cells were isolated and preincubated with verapamil (P-gp blocker) before ALA-PDT.
- Cytotoxicity was assessed using the XTT test; P-gp presence was evaluated via immunohistochemistry.
Main Results:
- Verapamil intensified phototoxic effects in normal endometrial cells at specific ALA concentrations.
- In endometriosis, verapamil enhanced PDT effects across all tested ALA concentrations.
- Ectopic endometriotic cells were more sensitive to PDT than normal endometrial cells, both with and without verapamil.
- P-gp was absent in normal endometrium but present in endometriosis epithelium and stroma.
Conclusions:
- Photodynamic therapy (PDT) efficacy for endometriosis can be amplified.
- Verapamil, in combination with 5-aminolevulinic acid (ALA), enhances phototoxic effects in endometriotic epithelial cells.
- The presence of P-gp in endometriosis contributes to differential sensitivity to PDT.
