Abstract 1840: Repurposing of valproic acid and simvastatin in pancreatic cancer: in vitro and in vivo synergistic antitumor interaction and sensitization to gemcitabine/nab-paclitaxel via inhibition of TGFβ-EMT signaling pathway

Abstract

Abstract INTRODUCTION: Metastatic pancreatic ductal adenocarcinoma (PDAC) represents an unmet clinical need because the lack of effective treatment strategies and a very poor prognosis. Here we propose a novel therapeutic strategy, based on the repurposing of valproic acid (VPA), a safe and generic drug with epigenetic modulating activity, and simvastatin (SIM), a widely used generic cholesterol lowering drug, in combination with the standard gemcitabine/nab-paclitaxel (GEM/NP) treatment in metastatic PDAC setting. METHODS: Synergistic anti-tumor effect of the combined treatment was assessed in PANC1, ASPC1, PANC28 and BxPC3 PDAC cell lines in vitro by evaluating combination index, apoptosis, clonogenic capability, tumor spheroids and fibroblasts/tumor cells microtissues growth. Antitumor effect was confirmed in vivo on heterotopic and orthotropic xenograft PANC1 models in athymic mice. Expression and functional role of TGF-β and downstream epithelial-to-mesenchymal-transition (EMT) markers were studied by Ingenuity pathway analysis (IPA), mRNA and protein expression and by cell migration scratch assay. RESULTS: We showed, both in vitro and in vivo, the ability of VPA/SIM combination, used at low dosages, to synergistically improve the anti-proliferative and pro-apoptotic effect of chemotherapy (GEM/NP). Mechanistically, VPA/SIM treatment, alone or in combination with chemotherapy, induced e-Cadherin and impaired vimentin and ZEB-1 expression, functionally linked to the synergistic inhibition of cell migration. In line, IPA highlighted a protein network connecting HDACs and HMGCR, the targets of VPA and SIM respectively, with the two main EMT markers. Notably, the most significantly cancer enriched features associated with this network were “migration of tumor cell lines”, “fibrosis” and “invasion of tumor cell lines”, and TGFβ emerged as a hierarchical dominant network- node. Indeed, VPA/SIM inhibited TGFβ transcription and TGFβ-regulated EMT gene expression in PDAC cells. Consistently we also observed a significant reduction of circulating TGFβ1 levels in mice treated with VPA/SIM in combination with GEM/NP, paralleled by a reduced fibrosis on PDAC xenograft tumor sections, confirming the involvement of TGFβ functional down-modulation in the mechanism of VPA/SIM antitumor synergistic interaction and chemo-sensitization. CONCLUSIONS: Overall, we proposed a novel combination strategy, based on two safe and generic drugs, able to sensitize a widely employed regimen in metastatic PDAC patients, that warrant further clinical evaluation. Citation Format: Maria Serena Roca, federica iannelli, maria rita milone, veronica barile, cristina testa, tania moccia, carlo vitagliano, fabiana tatangelo, di gennaro elena, antonio avallone, francesca bruzzese, alessandra leone, alfredo budillon. Repurposing of valproic acid and simvastatin in pancreatic cancer: in vitro and in vivo synergistic antitumor interaction and sensitization to gemcitabine/nab-paclitaxel via inhibition of TGFβ-EMT signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1840.