Abstract PD15-08: The role of purinergic signaling in the chemotherapy response of triple negative breast cancer

Abstract

Abstract Triple negative breast cancer (TNBC) affects women worldwide with a higher incidence in minority populations. Patients with TNBCs often have poorer prognoses in comparison to other breast cancer sub-types due to a lack of effective therapeutic options. Chemotherapy and immunotherapy are the only effective treatments, but these modalities generally result in short-term response. Therefore, there is a need to identify additional therapies to intensify the chemotherapeutic response in TNBC. When cancer cells are exposed to chemotherapy, they release adenosine triphosphate (ATP) into the extracellular space. Extracellular ATP is degraded by CD39 (E-NTPDase) to adenosine diphosphate (ADP) and then adenosine monophosphate (AMP), and AMP is broken down to adenosine by CD73. We examined the potential role of extracellular ATP in chemotherapy- induced cancer cell death. We hypothesized that extracellular ATP sensitizes TNBC cells to chemotherapy and that ATP degrading enzymes such as CD39 and CD73 attenuate this effect. TNBC MDA-MB 231, MDA-MB 468, and Hs 578t cell lines were treated with the chemotherapeutic agent paclitaxel for different time courses. Extracellular ATP was measured via the ATPlite 1step luminescence assay, and cell viability was assessed by applying PrestoBlue HS cell viability reagent. Paclitaxel-treated TNBC cell lines revealed a dose-dependent increase in extracellular ATP release in the presence of an inhibitor of CD39 (POM-1), accompanied by a dose-dependent decrease in cell viability. In addition, the general P2X receptor (P2RX) inhibitor iso-PPADS and the P2RX7 specific inhibitor (A438079) were added separately to observe if the P2X receptors are necessary for the release of ATP upon paclitaxel treatment. After paclitaxel treatment, TNBC cell lines showed a decline in the amount of ATP released with the addition of the inhibitors iso-PPADS and A438079. Treatment of non-tumorigenic immortalized MCF-10A mammary epithelial cells with paclitaxel in the presence and absence of the inhibitors iso-PPADS and A438079 did not result in a significant increase in extracellular ATP or a decrease in cell viability. These results indicate that P2RX7 is necessary for ATP release in TNBC cell lines exposed to chemotherapy. Furthermore, when TNBC cell lines were treated with increasing concentrations of ATP, there was a dose-dependent decrease in cell viability. Overall, these findings suggest that extracellular ATP may impact the chemotherapeutic response in TNBC cell lines through the activation of the ATP-gated channel P2RX7. Citation Format: Jasmine Manouchehri, Jharna Datta, Mathew Cherian. The role of purinergic signaling in the chemotherapy response of triple negative breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD15-08.