miR-7112-3p targets PERK to regulate the endoplasmic reticulum stress pathway and apoptosis induced by photodynamic therapy in colorectal cancer CX-1 cells.

Background: Colorectal cancer (CRC) is the third most common malignant tumor worldwide. Photodynamic therapy (PDT) is an emerging modality for the treatment of solid tumors. Sinoporphyrin sodium (DVDMS) is a new photosensitizer with good therapeutic killing effects on cancer cells. Recent findings have shown that microRNAs play important roles in many biological processes. However, the functions of microRNAs in DVDMS-induced PDT remain largely unclear.

Materials And Methods: Proteins involved in endoplasmic reticulum (ER) stress and apoptosis of CX-1 cells treated with DVDMS-PDT were examined by Western blotting and cell viability assays. 15 candidate miRNAs targeting RNA-dependent protein kinase-like ER kinase (PERK) were screened and verified using the TargetScan, miRWalk and miRDB databases. The downstream pathways of candidate miRNAs with high scores were studied by cell transfection, qRT-PCR, Western blotting and dual-luciferase reporter assays. The subcellular location of DVDMS was confirmed by laser confocal microscopy.

Results: DVDMS-PDT induced apoptosis via elevated ER stress and activation of the PERK/ATF4/CHOP/caspase cascade pathway in CX-1 cells. The endoplasmic reticulum was involved in the subcellular accumulation of DVDMS in CX-1 cells. Dual-luciferase reporting experiment confirmed that a direct crosslinking between miR-7112-3p and PERK. In addition, miR-7112-3p was highly expressed in CRC tissues compared with peripheral tissues.

Conclusion: Our work showed that miR-7112-3p directly targeted PERK and further regulated PERK/ATF4/CHOP/caspase cascade pathway, resulting in enhanced apoptosis in CX-1 cells treated with DVDMS-PDT.