Abstract 2745: Drug repositioning for triple negative breast and colorectal cancers treatment: Exploring the use of metformin and propranolol
Authors: Baglioni M Virginia , Anselmino Luciano E. , Laluce Nahuel Cesatti , Malizia Florencia , Chapo Gustavo F. , Mainetti Leandro E. , Rozados Viviana R. , Scharovsky O Graciela , Rico M. José , Márquez Mauricio A. Menacho 
Published: September 2020

Abstract
According to new global cancer data, breast and colorectal cancer (CRC) are part of the 5 types of tumors with the highest incidence and mortality. Triple negative breast cancer (TNBC) is a particularly aggressive type of breast cancer, associated with younger age, recurrence, high metastatic rate, poor prognosis and limited therapeutic options. Regarding CRC, this type of tumor is often diagnosed at advanced stages, when probability of development of distal or local recurrence due to chemotherapy resistance (usually 5-FU) is higher. For both types of tumors, the available treatment modalities are expensive and produce severe side effects. Drug repositioning refers to new uses outside the scope of the original medical indications for existing drugs or compounds; this approach fastens the process of drug development and offers more effective, cheaper and safer drugs with less side effects. We studied the effect of combining Metformin (M; antidiabetic drug) and Propranolol (P; antihypertensive agent) on in vitro and in vivo models of TNBC and CRC. We performed an in vitro screening of drugs under reposition on different TNBC and CCR cell lines and determined that M+P combination was particularly efficient in reducing proliferation in all cell lines tested. Indeed, M+P showed synergistic effect on proliferation, affecting significantly clonogenicity, apoptosis, migration and invasion. In order to explore the mechanisms associated with tumor growth/metastasis development involved in the treatment we evaluated the impact of M+P on cell signaling after proliferative stimuli and epithelial/mesenchymal transition. M+P combination reduced Erk phosphorylation levels after serum induction and promoted the expression of epithelial markers as β-catenin and E-cadherin. In vivo models (4T1, M-406, HCT116 and CT26 cells) demonstrated that M+P [M(2g/l)+P(25mg/l)] was effective reducing tumor growth and metastasis development. To further characterize the cellular events associated to these processes, we evaluated in 4T1 TNBC model the impact of M+P on different steps associated to tumor progression. The treatment affected intravasation (P=0.06), survival (P&lt;0.05) and extravasation (P&lt;0.05). Indeed, we developed an adjuvant model (M+P treatment after tumor excision) in which the drugs combination was effective preventing metastasis development (P&lt;0.05). Interestingly, regarding CCR we found in vitro that M+P reduced proliferation and clonogenicity of 5-FU-resistant CRC cells compared to non-resistant cells (P&lt;0.01). To conclude, M+P treatment decreased tumor and metastasis growth of TNBC and CRC, involving effects in several steps of tumor signaling and tumor dissemination. Our data suggest that M+P could be useful for adjuvant therapy and treatment of resistant tumors.
Citation Format: M Virginia Baglioni, Luciano E. Anselmino, Nahuel Cesatti Laluce, Florencia Malizia, Gustavo F. Chapo, Leandro E. Mainetti, Viviana R. Rozados, O Graciela Scharovsky, M. José Rico, Mauricio A. Menacho Márquez. Drug repositioning for triple negative breast and colorectal cancers treatment: Exploring the use of metformin and propranolol [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2745.