PLOD3 Promotes Tumor Progression and is Related to Poor Prognosis in Colorectal Cancer via SOX4/Wnt/β-Catenin Signaling Pathway

Abstract

Background: Colorectal cancer (CRC) is the main cause of cancer-related mortality globally. Thus, it is critical to find new therapeutic targets for CRC. This study aimed to evaluate the role and potential mechanism of procollagen-lysine, 2-oxoglutarate 5-dioxygenase 3 (PLOD3) on CRC cells. Methods: PLOD3 expression was identified by immunohistochemistry (IHC) and Western blot (WB) assay in CRC tissue and cells. PLOD3 roles in HCT116 (PLOD3 knockdown) and RKO (PLOD3 overexpression) cells were evaluated. In vitro by Cell Counting Kit-8 (CCK-8) assay, colony formation, transwell, and wound healing assays, and in vivo by xenograft and hepatic metastasis model. RNAseq was conducted between PLOD3 knockdown and control in HCT116 cells. The key genes β-catenin, c-myc and Sex-determining region Y-box 4 (SOX4) in CRC were determined by WB assay in vitro. Immunofluorescence assay was used to assess PLOD3 effect on the expression and location of β-catenin. Results: PLOD3 was screened as one of the main proliferative factors in CRC. In addition, CRC cell lines and clinical CRC tissues overexpressed PLOD3. In individuals with CRC, overexpressed PLOD3 was positively related with poor prognosis and metastasis. It was found that PLOD3 increased CRC cell proliferation, colony formation, migration, and invasion in vitro by gain- and loss-of-function tests. Additionally, a xenograft mouse model and a hepatic metastasis mouse model were used to show that PLOD3 ablation decreased CRC outgrowth and metastasis in vivo. In contrast, PLOD3 overexpression had the opposite effect. PLOD3 upregulated SOX4 in a mechanism that enhanced c-myc and β-catenin expression. Immunofluorescence assay indicated that PLOD3 expression was positively related to β-catenin in CRC cells. Conclusions: PLOD3 promotes tumor progression and poor prognosis through SOX4/Wnt/β-catenin signaling pathway in CRC.