Annexin A9 promotes invasion and metastasis of colorectal cancer and predicts poor prognosis.

Annexin A9 (ANXA9), a member of annexin family, has been reported be associated with colorectal cancer (CRC) carcinogenesis. However, the clinical significance of ANXA9 in CRC, particularly its correlation to invasion and metastasis remains ambiguous. The aim of the present study was to investigate the significance of ANXA9 in CRC and understand the molecular mechanism of ANXA9 in CRC invasion and metastasis. Expression levels of the ANXA9 protein in CRC tissues were detected using immunohistochemistry (IHC), and the clinical and prognostic value of ANXA9 was investigated. ANXA9­siRNA was utilized to investigate the effect and molecular mechanism of ANXA9 in HCT116 cells. The IHC result demonstrated that the positivity rate of the ANXA9 protein in CRC tissue was significantly higher than that in adjacent mucosa (P<0.05), which was consistent with the western blot results. ANXA9 protein expression levels are associated with invasion depth and lymphatic metastasis. Furthermore, patients with ANXA9­positive expression demonstrated a poor prognosis and ANXA9 was an independent risk factor for survival (P<0.05). After inhibiting ANXA9 in HCT116 cells, the activity and metastatic and invasion capacity of cells decreased significantly, and expression levels of ADAM metallopeptidase domain 17 and matrix metallopeptidase 9 were significantly downregulated, while the expression levels of tissue inhibitors of metalloproteinases­1 and E­cadherin were upregulated (P<0.05). Thus, positive ANXA9 expression may present as a novel marker for predicting poor prognosis in CRC patients, and ANXA9 may promote the invasion and metastasis of CRC by regulating invasion and metastasis­associated genes.