Enhancement of the cytotoxic effect of anticancer agent by cytochrome C functionalised hybrid nanoparticles in hepatocellular cancer cells

Treatment of hepatocellular cancer with chemotherapeutic agents has limited success in clinical practice and their efficient IC50 concentration would require extremely high doses of drug administration which could not be tolerated due to systemic side effects. In order to potentiate the efficacy of anticancer agents we explored the potential of co-treatment with pro-apoptotic Cytochrome c which activates the apoptotic pathway downstream of p53 that is frequently mutated in cancer. To this end we used hybrid iron oxide-gold nanoparticles as a drug delivery system to facilitate the internalisation of Cytochrome c into cultured HepG2 hepatocellular carcinoma cells. Our results showed that Cytochrome c can be easily conjugated to the gold shell of the nanoparticles which are readily taken up by the cells. We used Cytochrome c in concentration (0.2µgmL-1) below the threshold required to induce apoptosis on its own. When the conjugate was administered to cells treated by doxorubicin, it significantly reduced its IC50 concentration from 9µgmL-1 to 3.5µgmL-1 as detected by cell viability assay, and the efficiency of doxorubicin on decreasing viability of HepG2 cells was significantly enhanced in the lower concentration range between 0.01µgmL-1 to 5µgmL-1. The results demonstrate the potential of the application of therapeutic proteins in activating the apoptotic pathway to complement conventional chemotherapy to increase its efficacy. The application of hybrid iron oxide-gold nanoparticles can also augment the specificity of drug targeting and could serve as a model drug delivery system for pro-apoptotic protein targeting and delivery.