Effects of sulforaphane association to standard therapy for treating triple-negative breast cancer

Author(s)

Leandro de Lima Coutinho

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD)
• Defense date: 2022-12-12

Examining board members

Tharcisio Citrangulo Tortelli Junior; Lusania Maria Greggi Antunes; Maria Del Pilar Estevez Diz

• Advisor: Maria Cristina Rodrigues Rangel; Tharcisio Citrangulo Tortelli Junior

Abstract

Most tumors are comprised of functionally heterogeneous cells, and within the tumor bulk only a limited, but highly dynamic subpopulation of cells known as cancer stem cells (CSCs) can self-renew and initiate tumors at a high frequency. The triple-negative breast cancer (TNBC) subtype shows a significantly higher number of CSCs when compared to non-TNBC tumors. This characteristic contributes to the aggressive phenotype exhibited by TNBC and impacts the treatment of patients harboring these tumors since CSCs participate in the acquisition of resistance to conventional antineoplastic therapies. The embryonic signaling pathway Cripto-1(CR-1)/NODAL is known to be increased in TNBC, especially in the CSCs population contributing to the maintenance of their stemness phenotype. Also, studies have shown that the REDOX molecules Nitric Oxide (NO) and one of the enzymes involved on its synthesis, Nitric Oxide Synthase 2 (NOS2), are able to induce carcinogenesis through different processes, including the promotion of stem-like properties in TNBC cells. In this project, we sought to sensitize TNBC cells to conventional chemotherapy by negatively modulating CR-1 and NOS2/NO using sulforaphane (SFN), a nutraceutical known to especially target the CSCs population. Interestingly, this natural isothiocyanate compound found in cruciferous vegetables, e.g., broccoli and cauliflower, has also been shown to interfere in both CR-1 and NO activity in pathological conditions, such as TNBC and H. pylori infection, respectively. To address our hypothesis that SFN would sensitize cells to chemotherapy, we used in this study four cell lines representing the TNBC subtypes reported in the literature. Initially, we tested the response of all cell lines to doxorubicin (DOX) and cisplatin (CIS). We found that all of them, MDA-MB-468, HCC70, MDA-MB-453, and MDA-MB-231 were sensitive to DOX, displaying significant reduction in cell viability at low doses. On the other hand, only the basal-like subtype MDA-MB-468 and HCC70 cells responded to CIS at low doses. The luminal androgen receptor MDA-MB-453 and mesenchymal subtype MDA-MB-231 cells exhibited resistance to CIS treatment, with slight decrease on cell viability only at higher doses. However, when SFN was associated with CIS treatment, both cell lines exhibited significant reduction on cell viability accompanied by cell death, further characterized by early apoptosis activation. Additionally, we observed that MDA-MB-231 cells treated with CIS exhibited increased expression of the pluripotency genes CR-1 and Oct-4, and the epithelial-to-mesenchymal transition marker N-cadherin, however the combination therapy CIS-SFN was able to revert this effect. Finally, our results revealed that SFN treatment alone was able to impair cytokine-induced CR-1, NOS2, and COX2 overexpression in MDA-MB-231 cells and decrease DETANO(NO-donor)-induced HIF-1 stabilization in the same cells. Therefore, SFN is a potential candidate for combined therapy with CIS or as a coadjutant agent in patients who overexpress NOS2/COX2 (AU)

• FAPESP's process: 20/04007-3 - Sensitization of triple-negative breast cancer to chemotherapy by the inhibition cancer stem cells self-renewal
• Grantee: Leandro de Lima Coutinho
• Support Opportunities: Scholarships in Brazil - Master