Self-assembled albumin nanoparticles for combination therapy in prostate cancer

Resistance to regular treatment strategies is a big challenge in the treatment of castration-resistant prostate cancer. Combination of photothermal and photodynamic therapy (PTT/PDT) with chemotherapy offers unique advantages over monotherapy alone. However, free drugs, such as photosensitizers and chemotherapeutic agents, lack tumor-targeted accumulation and can be easily eliminated from the body. Moreover, most of the PTT drugs are hydrophobic and their organic solvents have in vivo toxicity, thereby limiting their potential in clinical translation. Herein, simple multifunctional nanoparticles (NPs) using IR780 (a near-infrared dye) and docetaxel (DTX)-loaded nanoplatform based on human serum albumin (HSA) (HSA@IR780@DTX) was developed for targeted imaging and for PTT/PDT with chemotherapy for the treatment of castration-resistant prostate cancer treatment. In this platform, HSA is a biocompatible nanocarrier that binds to both DTX and IR780. DTX and IR780, as hydrophobic drug, can induce the self-assembly of HSA proteins. Transmission electron microscopic imaging showed that NPs formed by self-assembly are spherical with a smooth surface with a hydrodynamic diameter of 146.5±10.8 nm. The cytotoxicity of HSA@IR780@DTX NPs with or without laser irradiation in prostate cancer cells (22RV1) was determined via CCK-8 assay. The antitumor effect of HSA@IR780@DTX plus laser irradiation was better than either HSA@IR780@DTX without laser exposure or single PTT heating induced by HSA@IR780 NPs under near-infrared laser, suggesting a significant combined effect in comparison to monotherapy. Near-infrared fluorescence imaging showed that HSA@IR780@DTX NPs could preferentially accumulate in tumors. In vivo therapeutic efficacy experiment showed that xenografted prostate tumors on mice treated with HSA@IR780@DTX plus near-infrared laser irradiation were completely inhibited, whereas tumors on mice treated with chemotherapy alone (HSA@DTX and HSA@IR780@DTX without laser) or PTT/PDT alone (HSA@IR780 with laser) showed moderate growth inhibition. Overall, HSA@IR780@DTX NPs showed notable targeting and theranostic potential for the treatment of castration-resistant prostate cancer.