CKAP2 Regulated by TFDP1 Promotes Metastasis and Proliferation of Colorectal Cancer through Affecting the Tumor Microenvironment

The current pathological and physiological evaluation system for colorectal cancer (CRC) is limited; thus, effective biological targets to diagnose and treat this disease are urgently needed. In this study, we used qRT-PCR for detecting mRNA levels of genes. The levels of protein were identified by western blot, immunohistochemistry, and immunofluorescence assays. In addition, functional experiments were used to evaluate the role of cytoskeleton associated protein (CKAP) 2 in CRC cells and human umbilical vein endothelial cells (HUVECs). Bioinformatics analysis was employed to predict the binding relationship of CKAP2 and TFDP1, which was confirmed through dual luciferase reporter assay and immunoprecipitation assay. Furthermore, we injected human colorectal carcinoma HCT116 cells into mice flanks, and we injected Luciferase-labeled HCT116 cells into mice tail vein. HE staining was used to detect tumor nodules. As a result, high CKAP2 expression was found in CRC cells and tissues. CKAP2 silencing reduced CRC cell migration, invasion, proliferation, and epithelial-mesenchymal transition. Moreover, CKAP2 expression was positively associated with M2 macrophage levels. CKAP2 promoted protein expression of CD86, CD206, IL-1β, and CCL17. Moreover, CKAP2 promoted the proliferation of HUVECs and angiogenesis via affecting the tumor microenvironment (TME). We also found that CKAP2 could interact with TFDP1. The inhibitory impacts of TFDP1 downregulation on CRC cell' proliferation, migration, and invasion were reversed via CKAP2 overexpression. In vivo silencing of CKAP2 repressed tumor growth and metastasis. Overall, CKAP2 was positively regulated by TFDP1, which promoted tumorigenesis and metastasis in CRC.