CircRNA circ_0124554 blocked the ubiquitination of AKT promoting the skip lymphovascular invasion on hepatic metastasis in colorectal cancer.

Colorectal cancer (CRC) is the fourth most common cancer in men and the third most common cancer in women worldwide. The incidence and mortality of CRC was increasing rapidly in China. Lymph node-negative colorectal cancer patients with synchronous liver metastasis (LNLM1) was defined as "skip" lymph vascular invasion on hepatic metastasis, who presenting poor prognosis. We aiming to investigate the potential mechanism for the "skip" lymph vascular invasion on hepatic metastasis in colorectal cancer. The microarray was applied for screening the transcription landscape of circRNA in lymph node negative CRC patients with synchronous liver metastasis (LNLM1) or without liver metastasis (LNLM0). We identified the aberrant increased circRNA circ_0124554 (also entitled as circ-LNLM) in tumor tissues of LNLM1 patients comparing with either the tumor tissues of LNLM0 or adjacent tissues of LNLM1. Circ-LNLM1 expression was highly correlated with liver metastasis and vascular invasion. Ectopic expression of cytoplasmic located circ-LNLM could promote invasion of CRC cells and induced the liver metastasis in animal models through the direct binding with AKT. The phosphorylation of AKT (T308/S473) was activated due to the blocked ubiquitination site of Lys in 0-52aa peptide of circ-LNLM. Endogenous plasma expression of circ-LNLM induced poor prognosis of LNLM1 and could distinguish LNLM1 patients from LNLM0. In conclusion, the circ-LNLM blocked the ubiquitination of AKT could promote the early metastasis especially for the lymph node-negative colorectal cancer patients with synchronous liver metastasis. The circ-LNLM might be prognosis and diagnosis biomarker for LNLM1 patients.