Dietary isothiocyanates for cancer combination therapy: Synergistic anticancer activity of phenethyl isothiocyanate and dasatinib

Abstract

Combination therapies exploit multiple drugs to synergistically target key pathways to reduce tumour growth and metastatic potential. Isothiocyanates (ITCs) have been shown to have anticancer capabilities and may complement the anticancer activity of clinically approved chemotherapeutic agents. Hepatocellular carcinoma (HCC) is the most common type of liver cancer, which is second most lethal tumour. Thus, there is a continuous need for the development of new therapeutic solutions, and the use of ITCs in combination therapy seems to be a promising strategy for treatment of HCC progression. The research presented in this thesis aimed to assess the potential of phenethyl isothiocyanate (PEITC) to improve the activity of dasatinib in HCC. A murine syngeneic subcutaneous model was used to assess the combination efficacy in vivo and the MTT cell viability assay was used to assess the anticancer effect in vitro . Furthermore, the effect on HCC metastatic potential and angiogenesis was assessed using adhesion, scratch wound healing, invasion, colony formation, chorioallantoic membrane (CAM), and yolk sac membrane assays. Flow cytometry, RT-qPCR, HPLC and Western blot were used to elucidate the mechanism of action of the drug combination. PEITC and dasatinib showed a synergistic anticancer effect in vitro and in vivo. By inducing oxidative stress, through the production of reactive oxygen species (ROS), PEITC and dasatinib combination promoted the formation of a premature CDK1-Cyclin B1 complex, leading to mitotic catastrophe and activating oxeiptosis, a novel programmed cell death. Furthermore, the inhibition of FAK/STAT3 signalling led to increased E-cadherin expression and diminished secretion of pro-angiogenic factors, reducing HCC metastatic potential. Phenethyl isothiocyanate can complement dasatinib's action in treating HCC, inducing cell cycle arrest and oxeiptosis and decreasing metastatic potential and tumour-induced angiogenesis. This thesis highlights the role of ITCs in cancer therapy to complement clinically approved chemotherapeutic drugs