Triple negative breast cancer (TNBC) overexpresses sirtuins (SIRTs), a class III HDACs, which induces epithelial-to-mesenchymal (EMT) transition and facilitates Cisplatin (CIS) resistance. We hypothesized that Sulforaphane (SFN), an HDAC inhibitor, when combined with CIS, could potentiate CIS efficacy against TNBC metastasis and overcome its resistance.
Material and Methods:
The effect of SFN and CIS combination on cellular proliferation and apoptosis of two TNBC cell lines, MDA-MB-231 and MDA-MB-468 were assessed by MTT assay and Annexin and PI method followed by FACS analysis respectively. The anti-metastatic capabilities of the compounds were evaluated using wound healing assay, invasion assay, chemotaxis assay, colony formation and tumorsphere assay. The regulation of key proteins involved in sirtuin-mediated EMT signaling and metastasis was determined by zymography and western blot analysis.
The results revealed that SFN in combination with CIS synergistically inhibited TNBC cells through inhibition of cellular proliferation, induction of apoptosis, in-silico and in-vitro modulation of SIRTs (1-7) expression. Anti-metastatic capabilities of the combinatorial treatment regimen were associated with inhibition of migratory, invasive, mammosphere forming potential and downregulation of matrix metallopeptidase (MMP-9 and MMP-2) activity of TNBC cells. When TNBC cells were treated with SFN, the expression of epithelial marker, E-cadherin was up-regulated, while the expression of mesenchymal markers, ZEB1, SNAIL, TWIST and associated SIRTs were down-regulated. In contrast, when the cells were treated with CIS, the expressions of mesenchymal markers were up-regulated. Interestingly, the combinatorial treatment of SFN and CIS synergistically inhibited EMT transition in TNBC cells. In-vivo studies are warranted to confirm our results.
Collectively our findings demonstrated a SIRTs-mediated EMT-suppression leading to synergistic antitumor effect by combination of SFN and CIS in TNBC cells. This combination therapy may serve as a novel therapeutic strategy for TNBC management.
Citation Format: SONAM SINHA, Neeta Shrivastava. Synergistic anticancer effect of sulforaphane and cisplatin on sirtuins-mediated epithelial-to-mesenchymal signaling in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4190.