Studies on function of P-glycoprotein in photodynamic therapy of endometriosis.
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.


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.


CONCLUSIONS
Phototoxic effects could be amplified in epithelial cells of endometriotic foci by appropriate action of verapamil and 5-aminolevulinic acid.
Department of Cell Biology, Poznan University of Medical Sciences, Poznań, Poland. doskon@amp.edu.pl
Maria
M
Wołuń-Cholewa
Krzysztof
K
Szymanowski
Mirosław
M
Andrusiewicz
Wojciech
W
Warchoł
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000622:Aminolevulinic Acid; D002121:Calcium Channel Blockers / Q000494:pharmacology; D004715:Endometriosis / Q000188:drug therapy / Q000378:metabolism*; D004717:Endometrium / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D010778:Photochemotherapy; D017319:Photosensitizing Agents; D014591:Uterine Diseases / Q000188:drug therapy / Q000378:metabolism*; D014700:Verapamil / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002121:Calcium Channel Blockers; D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid; D014700:Verapamil