Signaling Pathways Involved In Apoptosis-Resistance Against Doxorubicin Analogues In Murine Mammary Cells; Role Of Protein Kinase C Delta (Pkc Delta)

In this work we have analyzed whether the overexpression of PKCΔ in murine mammary cells (NMuMG) is able to alter cell death susceptibility to two chemotherapeutic drugs derived from doxorubicin (AD198 and AD288), and evaluate the signaling pathways involved in this process. Similarly to doxorubicin, the mechanism of action of AD288 involves the generation of DNA damage whereas, it has been proposed that AD198 induces apoptosis by activating PKC isoforms, in particular PKCΔ. By western blot we could determine that NMuMG-PKCΔ cells showed an increase in the activation and/or expression of different molecules and signaling pathways involved in cell survival such as Bcl-2, pBad, PI3K/Akt y NFκB. Therefore PKCΔ overexpression induced an increase in cell death resistance against both ADs (survival: AD198: 80±10% vs. 41±8% and AD288: 90±15% vs. 60±10% in NMuMG-PKCΔ and NMuMG-vector cells respectively). In order to evaluate the role of PI3K/Akt pathway in cell death resistance induced by both ADs, cells were treated with LY294002, a PI3K inhibitor. The inhibition of this signaling pathway in NMuMG-PKCΔ cells increased 3-fold AD198 cytotoxic effect, whereas did not alter AD288 effect. The role of NFκB signaling pathway in the resistance against cell death induced by each AD was determined by transient transfection with a variant of its repressor IκB. The inhibition of this signaling pathway significantly increased cell death susceptibility to both drugs (P In this work we have demonstrated that the anti-apoptotic signals generated by PKCΔ in NMuMG mammary cells could be reverted by inhibiting PI3K/Akt and/or NFκB signaling pathways. In addition, it was shown that the pathway involved was dependent on the mechanism of action of the cytotoxic drug used. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2142. doi:10.1158/1538-7445.AM2011-2142