Novel cationic dimethylaminopyridine derivatives of pentacyclic triterpenes were previously described to promote mitochondrial depolarization and cell death in breast and melanoma cell lines. The objective of this work was to further investigate in detail the mechanism of mitochondrial perturbations, correlating those effects with breast cancer cell responses to those same agents. Initially, a panel of tumor and non-tumor cell lines was grown in high-glucose or glucose-free glutamine-containing media, the later forcing cells to synthesize ATP by oxidative phosphorylation only. Cell proliferation, cell cycle, cell death and mitochondrial membrane polarization were evaluated. Inhibition of cell proliferation was observed, accompanied by an arrest in the G1-cell cycle phase, and importantly, by loss of mitochondrial membrane potential. On a later time-point, caspase-9 and 3 activation were observed, resulting in cell death. For the majority of test compounds, we determined that cell toxicity was augmented in the galactose media. To investigate direct evidences on mitochondria isolated rat liver mitochondria were used. The results showed that the compounds were strong inducers of the permeability transition pore. Confirming our previous results, this work shows that the novel DMAP derivatives strongly interact with mitochondria, resulting in pro-apoptotic signaling and cell death.
Bibliographical noteFunding Information:
This study was funded by the Portuguese Foundation for Science and Technology (FCT) , Portugal, and cofinanced by: COMPETE-Programa Operacional Factores de Competitividade , QREN and European Union (FEDER-Fundo Europeu de Desenvolvimento Regional) Research Grant PTDC/QUI-QUI/101409/2008 . T.L.S. supported by the FCT Doctoral Fellowship SFRH/BD/38067/2007 , G.C.P. Doctoral Fellowship SFRH/BD/36938/2007 both co-financed by POPH Programa Operacional Potencial Humano , QREN and European Union . This study was supported by a Grant from the Whiteside Institute for Clinical Research to J.H. and P.A.K., a Research Grant from the University of Minnesota —Duluth to P.A.K.
© 2014 Elsevier Ltd. All rights reserved.
- Breast cancer
- Cell death
- Lupane triterpenoids derivatives
- Mitochondrial physiology