Evidence has shown that m-THPC and verteporfin (VP) are promising sensitizers in photodynamic therapy (PDT). In addition, autophagy can act as a tumor suppressor or a tumor promoter depending on the photosensitizer (PS) and the cancer cell type. However, the role of autophagy in m-THPC- and VP-mediated PDT in in vitro and in vivo models of human colorectal cancer (CRC) has not been reported. In this study, m-THPC-PDT or VP-PDT exhibited significant phototoxicity, inhibited proliferation, and induced the generation of large amounts of reactive oxygen species (ROS) in CRC cells. From immunoblotting, fluorescence image analysis, and transmission electron microscopy, we found extensive autophagic activation induced by ROS in cells. In addition, m-THPC-PDT or VP-PDT treatment significantly induced apoptosis in CRC cells. Interestingly, the inhibition of m-THPC-PDT-induced autophagy by knockdown of ATG5 or ATG7 substantially inhibited the apoptosis of CRC cells. Moreover, m-THPC-PDT treatment inhibited tumorigenesis of subcutaneous HCT116 xenografts. Meanwhile, antioxidant treatment markedly inhibited autophagy and apoptosis induced by PDT in CRC cells by inactivating JNK signaling. In conclusion, inhibition of autophagy can remarkably alleviate PDT-mediated anticancer efficiency in CRC cells via inactivation of the ROS/JNK signaling pathway. Our study provides evidence for the therapeutic application of m-THPC and VP in CRC.

Colorectal cancer (CRC) is one of the most common cancers worldwide. MicroRNAs (miRNAs) play a vital role in a variety of biology processes. Our previous work identified miR-139-5p as a tumor suppressor gene overexpressed in CRC that assisted in inhibiting progression of cancer. The main challenge of miRNAs as therapeutic agents is their rapid degradation in plasma, poor uptake, and off-target effects. Therefore, the development of miRNA-based therapies is necessary. In this study, we developed a cationic liposome-based nanoparticle loaded with miR-139-5p (miR-139-5p-HSPC/DOTAP/Chol/DSPE-PEG2000-COOH nanoparticles, MNPs) and surface-decorated with epithelial cell adhesion molecule (EpCAM) aptamer (Apt) (miR-139-5p-EpCAM Apt-HSPC/DOTAP/Chol/DSPE-PEG2000-COOH nanoparticles, MANPs) for the targeted treatment of CRC. The size of MANPs was 150.3 ± 8.8 nm, which had a round-shaped appearance and functional dispersion capabilities. It also showed negligible hemolysis in the blood. MANPs markedly inhibited the proliferation, migration, and invasion of one or more CRC cell lines in vitro. Furthermore, we demonstrated the uptake and targeting ability of MANPs in vivo and in vitro. MANPs inhibit the growth of HCT8 cells in vitro and have a significant tumor suppressive effect on subcutaneous HCT8 colorectal tumor mice. Our results demonstrated that MANPs were an effective carrier approach to deliver therapeutic miRNAs to CRC.

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