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Double gene siRNA knockdown of mutant p53 and TNF induces apoptosis in triple-negative breast cancer cells.

ABSTRACT: Apoptosis is the major downregulated pathway in cancer. Simultaneous inhibition using specific small interfering RNA (siRNA) of two key player genes, p53 and TNF, is an interesting and feasible strategy when it comes to investigating various molecular pathways and biological processes in triple-negative breast cancer (TNBC), which is one of the most aggressive and therapeutically unresponsive forms of breast cancers. Our present research focuses on evaluating the impact of double p53-siRNA and TNF-siRNA knockdown at a cellular level, and also evaluating cell proliferation, apoptosis, induction of autophagy, and gene expression by using reverse transcription polymerase chain reaction array approaches. Simultaneous inhibition of p53 and TNF in Hs578T TNBC human cell line revealed a panel of up- and downregulated genes involved in apoptosis. Furthermore, the effects of double gene knockdown were validated in a second TNBC cell line, MDA-MB-231, by using reverse transcription polymerase chain reaction TaqMan assay. All our findings help in understanding the functional mechanisms of extrinsic apoptosis, cell signaling pathways, and the mechanisms involved in tumor cell survival, growth, and death in TNBC.

SUBMITTER: Pileczki V

PROVIDER: S-EPMC5113913 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Double gene siRNA knockdown of mutant p53 and TNF induces apoptosis in triple-negative breast cancer cells.

Pileczki Valentina V Pop Laura L Braicu Cornelia C Budisan Livia L Bolba Morar Gabriela G Del C Monroig-Bosque Paloma P Sandulescu Robert V RV Berindan-Neagoe Ioana I

OncoTargets and therapy 20161111

Apoptosis is the major downregulated pathway in cancer. Simultaneous inhibition using specific small interfering RNA (siRNA) of two key player genes, p53 and TNF, is an interesting and feasible strategy when it comes to investigating various molecular pathways and biological processes in triple-negative breast cancer (TNBC), which is one of the most aggressive and therapeutically unresponsive forms of breast cancers. Our present research focuses on evaluating the impact of double p53-siRNA and T ...[more]

PMID: 27956838

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Project description:Triple-negative breast cancer (TNBC; estrogen receptor-negative, progesterone receptor-negative and Her-2-negative) is often accompanied by a higher frequency of p53 gene mutations. Therefore, TNBC is challenging to treat due to a lack of biological targets and a poor sensitivity to conventional therapies. Curcumol is a monomer composition isolated from the ethanol extracts of Curcuma wenyujin, a Chinese medicinal herb traditionally used as a cancer remedy. Previous studies have revealed that curcumol is able to block proliferation in various human tumor cell lines. However, the underlying mechanisms have yet to be elucidated. The present study aimed to investigate the anticancer effects of curcumol in the human p53 mutant TNBC MDA-MB-231 cell line and its underlying mechanisms. Cell viability and growth were determined by MTT and a mice xenograft model assay, respectively. Cell cycle distribution was examined by flow cytometry. Apoptosis was evaluated by apoptotic morphology analysis with DAPI staining and flow cytometric analysis following Annexin V/propidium iodide staining. The protein expression in cells was evaluated by immunoblotting. Treatment of MDA-MB-231 cells with curcumol resulted in a significant inhibition of cell proliferation in vitro [half maximal inhibitory concentration (IC50)=240.7±85.0 µg/ml for 48 h and IC50=100.2±13.5 µg/ml for 72 h]. Curcumol treatment also resulted in the suppression of xenograft growth in vivo (100 or 200 µg/kg for 21 days), as well as G1 phase arrest and an apoptotic response, which were accompanied by the upregulation of p73 expression and the activation of the expression of p53 upregulated modulator of apoptosis (PUMA) and Bcl-2 antagonistic killer (Bak). No cleavage of poly (ADP-ribose) polymerase was detected. To the best of our knowledge, the present data demonstrate for the first time that curcumol inhibits the growth of MDA-MB-231 cells and triggers p53-independent apoptosis, which may be mediated by the p73-PUMA/Bak signaling pathway. Curcumol may, therefore, be a potential compound for use in the development of novel TNBC therapeutics.

Project description:We recently established c-Abl as a potent suppressor of triple-negative breast cancer (TNBC) progression through its reactivation of a p53:p21 signaling axis coupled to senescence. Moreover, we observed co-expression of p53 and c-Abl to be essential for normal mammary epithelial cell physiology, as this relationship is lost upon breast cancer progression. Cytoplasmic c-Abl activity is markedly increased in some TNBCs and contributes to disease progression; however, the mechanisms underlying these events remain largely unknown. In addressing this question, we show here that c-Abl is predominantly restricted to the cytoplasm of human MDA-MB-231 TNBC cells, and to the nucleus of human MCF-7 luminal A cells. TTK is a mitotic protein kinase that phosphorylates c-Abl on Thr735, thereby creating a recognition binding motif for 14-3-3 adaptor proteins in response to oxidative stress. By interrogating the METABRIC database, we observed a significant correlation between p53 expression and that of c-Abl and TTK in basal-like breast cancers. Moreover, heterologous expression of TTK in MCF-7 cells significantly stimulated their growth in part via a c-Abl-dependent mechanism. Conversely, depleting TTK expression in MDA-MB-231 cells not only inhibited their organoid growth in 3D-cultures, but also sensitized them to the tumor suppressing activities of c-Abl independent of its subcellular localization. Moreover, we show that mutant p53 forms cytoplasmic complexes with c-Abl, thereby dictating the subcellular localization of c-Abl and the sensitivity of MDA-MB-231 cells to Imatinib. In response to nutrient deprivation, c-Abl:p53 complexes readily accumulate in the nucleus, resulting in the hyperactivation of c-Abl and initiation of its anti-tumor activities. Collectively, we identified a novel mutant p53:c-Abl cytoplasmic signaling complex that promotes MDA-MB-231 cell growth and highlights the contextual cues that confer oncogenic activity to c-Abl in breast cancer.

Dataset Information

Double gene siRNA knockdown of mutant p53 and TNF induces apoptosis in triple-negative breast cancer cells.

Publications

Double gene siRNA knockdown of mutant p53 and TNF induces apoptosis in triple-negative breast cancer cells.

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