Construction of a Multifunctional Upconversion Nanoplatform Based on Autophagy Inhibition and Photodynamic Therapy Combined with Chemotherapy for Antitumor Therapy

Inhibition of autophagy increases the sensitivity of tumor cells to radiotherapy and chemotherapy and improves the therapeutic effect on tumors. Recently, photodynamic therapy (PDT) combined with chemotherapy has been proven to further improve the efficiency of cancer treatment. As such, combining autophagy inhibition with PDT and chemotherapy may represent a potentially effective new strategy for cancer treatment. However, currently widely studied autophagy inhibitors inevitably produce various toxic side effects due to their inherent pharmacological activity. To overcome this constraint, in this study, we designed an ideal multifunctional upconversion nanoplatform, UCNP-Ce6-EPI@mPPA + NIR (MUCEN). Control, UCNP-EPI@mPPA (MUE), UCNP-EPI@mPPA + NIR (MUEN), Ce6-EPI@mPPA (MCE), Ce6-EPI@mPPA + NIR (MCEN), and UCNP-Ce6-EPI@mPPA (MUCE) groups were set up separately as controls. Based on a combination of autophagy inhibition and PDT, the average particle size of MUCEN was 197 nm, which can simultaneously achieve the double encapsulation of chlorine e6 (Ce6) and epirubicin (EPI). In vitro tests revealed that MUCE was efficiently endocytosed by 4T1 cells under near-infrared light irradiation. Further, in vivo tests revealed that MUCE dramatically inhibited tumor growth. Immunohistochemistry results indicated that MUCE efficiently increased the expression of autophagy inhibitors p62 and LC3 in tumor tissues. The synergistic effect of autophagy inhibition and PDT with MUCE exhibited superior tumor suppression, providing an innovative approach to cancer treatment.