Abstract B208: Reduction in P2X7 receptor expression is a marker of resistance to ATP treatment in human cervical carcinoma cell line.

Abstract

Abstract Cervical cancer is the third most commonly diagnosed malignancy and the fourth leading cause of cancer death in females worldwide. The high mortality rate is largely due to the lack of effective therapies for eliminating disease in women with high-grade cervical cancer and the lack of response to chemotherapy of inoperable disease. Thus, to understand the mechanisms involved on cervical cancer development and find a molecular target to prevent it is strongly desirable. Until now, researchers show that HPV infection and suppression of cell death mechanisms like apoptosis are the most important factors involving of cervical carcinogenesis. Anyway, the mechanism that leads cells infected by HPV escape to apoptosis remains unknown. A role for purinergic signaling on control of cell growth and death, mainly through P2X7 receptor activation by extracellular ATP, has been described. We hypothesized that a disruption in this signaling could be involved with cervical cancer resistance to apoptosis and development. Previous work, using human carcinoma cell line SiHa, showed that ATP 5mM induces cell death through apoptosis by P2X7 activation. However, the mechanism involved in this cytotoxic effect remained unclear. To answers this question, we investigate the role of P2X7 on ATP induce cell death. We started analyzing P2X7 protein expression in cells resistant to ATP treatment. In this case, SiHa cells were treated with ATP 5mM for 24, 48, and 72h, and the adherent survival cells were removed and analyzed by Western Blot. After, we knockdown P2X7 receptor in SiHa cell line and evaluate this effect on cell viability after ATP treatment. In addition, we studied the mechanistic way involved in this cell death pathway using EGTA and caspase-3 inhibitor previous to ATP treatment. Unexpectedly, SiHa wild type (WT) cells that remained adherent after treatment with ATP showed less expression of P2X7, suggesting a defense way to apoptosis. Corroborating with this, SiHa cells knockdown (KD) for P2X7 showed increased cell viability when compared to SiHa WT and SiHa KD control, after exposure to ATP 5mM for 24, 48, and 72h. The mechanism of ATP induces apoptosis through P2X7 don't seems to be by increase intracellular calcium and caspase-3 activation, but in an independent caspase way. These findings suggest that P2X7 receptor could be involved with death and resistance cell mechanisms, indicating a possible new target on therapeutical research in cervical cancer and on tumor aggressiveness. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B208. Citation Format: Paola de Andrade Mello, Eduardo Cremonese Filippi-Chiela, Jessica Nascimento, Franciele Cristina Kipper, Aline Beckenkamp, Danielle Bertodo Santana, Alessandra Nejar Bruno, Guido Lenz, Andréia Buffon. Reduction in P2X7 receptor expression is a marker of resistance to ATP treatment in human cervical carcinoma cell line. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B208.