title: Combretastatin A-4 induces p53 mitochondrial-relocalisation independent-apoptosis in non-small lung cancer cells.
abstract: Combretastatin A-4 (CA-4) is one of the most effective agents used in chemotherapy. Nevertheless, the contribution of p53 and Bim proteins in the CA-4-induced apoptosis in non-small lung cancer cells (NSCLC) remains unresolved, specifically on involving of p53 in the mitochondrial pathway activation by a transcription-independent mechanism. In this context, the p53-null H1299 and wt-p53 H460 NSCLC cells, in the absence and presence of pifithrin-µ (PFTµ), an inhibitor of p53 mitochondrial-translocation, were treated with CA-4 and different cellular endpoints were analysed. In contrast to previous observations in H460 cells, CA-4 failed in the activation of an apoptotic response in H1299 cells, thus indicating an involvement of p53 in the cell death induced by the drug. We found that CA-4 led to p53 cellular re-localisation in H460 cells; in particular, p53 was released from the microtubular network and accumulated at mitochondria where it interacts with Bim protein and other proteins of the Bcl-2 (B-cell leukaemia-2) family, leading to cytochrome c release, alteration in the mitochondrial membrane polarisation, cell cycle arrest at the G2/M-phase, and cell death. Interestingly, the cytosolic and the mitochondrial accumulation of protein Bim was strictly dependent on p53 status. The extent of cell death was not reduced in H460 after combined treatment of PFTµ with CA-4. Overall, the data support a model of CA-4-induced apoptosis in NSCLC, for which the expression of p53 protein is essential, but its mitochondrial function, linked to p53-transcription independent apoptosis pathway, is negligible.
authors.affiliation: Departament of Science University 'Roma Tre', V.le G. Marconi 446, 00146, Rome, Italy; Universidad de Ciencias Aplicadas y Ambientales, Calle 222, 55-37, Bogotá, Colombia.
authors.forename: Gina Marcela
authors.initials: GM
authors.lastname: Méndez-Callejas
authors.forename: Stefano
authors.initials: S
authors.lastname: Leone
authors.forename: Caterina
authors.initials: C
authors.lastname: Tanzarella
authors.forename: Antonio
authors.initials: A
authors.lastname: Antoccia
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001632:Bibenzyls / Q000494:pharmacology*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D001632:Bibenzyls; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C040105:combretastatin; D045304:Cytochromes c
keywords: Bim protein; apoptosis; combretastatin A-4; mitochondrial p53; non-small-cell lung carcinoma