Decreased expression of P2X 7 in endometrial epithelial pre-cancerous and cancer cells

Abstract

Objectives To understand the potential role of P2X 7 as biomarker of endometrial cancer, and the molecular mechanisms by which cancerous epithelial cells maintain low expression of P2X 7. Methods Feasibility clinical experimental study. Normal (28), simple or complex hyperplasia (7), complex hyperplasia with atypia (6) and cancer endometrial discarded tissues (40) were obtained from a total of 81 women, ages 25–75. Endpoint for P2X 7 protein was average pixel signal density of tissue immunoreactivity with anti-P2X 7 antibody. Endpoint for P2X 7 mRNA was one-step quantitative Real-Time PCR. Experiments in-vitro included normal (hEVEC) and cancerous cervical epithelial cells (HeLa) transfected with reporter plasmid containing luciferase-3′ untranslated region (3′UTR)-P2X 7 cDNA, using as endpoint steady-state luciferase mRNA levels. Results Levels of P2X 7 protein and mRNA were significantly lower in vivo, in tissues of complex hyperplasia with atypia or endometrial adenocarcinoma, than in tissues of normal endometrium, simple hyperplasia or complex hyperplasia tissues (sensitivity and specificity of 89–100%, p < 0.0001–0.01). Steady-state levels of luciferase mRNA increased over a 6 h incubation period in hEVEC cells transfected with the 3′UTR-P2X 7-luciferase vector, but decreased in HeLa cells transfected with the reporter plasmid. Conclusions Tissue levels of P2X 7 protein and mRNA can differentiate effectively and accurately between normal and benign hyperplastic endometrial tissues from pre-cancerous and cancer tissues. Cancerous epithelial cells degrade P2X 7 mRNA by activation of instability domains located at the 3′UTR of the P2X 7.