Abstract: Objective To analyze the expression of rhythmic molecules timeless interacting protein (TIPIN) in hepatocellular carcinoma (HCC) tissues and its relationship with the prognosis of patients, and to explore the effect of TIPIN on the proliferation of HCC cells and its possible biological mechanism. Methods The expression of TIPIN in HCC and its relationship with the prognosis of HCC patients were explored through the UALCAN database. The siTIPIN and its negative control sequence were transfected into liver cancer MHCC⁃97H cells, respectively, and the expression of TIPIN was detected by qRT⁃PCR and Western blot. The effect of TIPIN expression on cells proliferation was detected by the MTS assay and the plate cell clone formation assay. The GO and KEGG enrichment analysis of TIPIN and its association with Timeless (TIM) and TP53 were performed using UALCAN database. Results UALCAN database analysis showed that the expression of TIPIN in HCC tissues was significantly higher than that in normal liver tissues (P<0.01). The overall survival and disease⁃free survival in patients with high TIPIN expression were significantly lower than those of patients with low TIPIN expression (P=0.037, 0.021). Compared with normal liver cells HL7702, the mRNA and protein expression of TIPIN in MHCC⁃97H, MHCC⁃97L, HepG2 and BEL⁃7402 were significantly increased (all P<0.01). MTS and plate cell clonal formation experiments showed that the proliferation and clonogenesis of MHCC⁃97H cells were significantly inhibited after silencing the expression of TIPIN (all P<0.05). GO and KEGG analysis showed that TIPIN might promote the malignant process of HCC by regulating the interaction pathways of cell division, DNA replication and cell cycle. Pearson correlation analysis showed that TIPIN was positively correlated with TIM expression (r=0.67, P<0.01). The expression of TIPIN in TP53 mutant HCC patients was significantly higher than that in TP53 wild type HCC patients (P<0.01). Conclusions The expression of TIPIN is up⁃regulated in liver cancer and is closely related to poor prognosis. Silencing TIPIN can inhibit the proliferation of liver cancer cells. TIPIN may play a biological role in liver cancer cells by forming complex with TIM or regulating TP53 signal pathway.

Key words: Liver cancer, TIPIN, Circadian rhythm, Proliferation, Prognosis