[High expression of SURF4 promotes migration, invasion and proliferation of gastric cancer cells by inhibiting tight junction proteins].

OBJECTIVES

To study the impact of SURF4 expression level on long-term prognosis of gastric cancer (GC) and biological behaviors of GC cells.

METHODS

SURF4 expression level in GC and its association with long-term patient prognosis were analyzed using publicly available databases and in 155 GC patients with low and high SURF4 expressions detected immunohistochemically. The Cox proportional hazard model and Kaplan-Meier survival curves were used to analyze independent prognostic predictors of GC and the 5-year survival rate of the patients with different SURF4 expression levels. Informatics analyses were conducted to explore the correlation of SURF4 expression level with immune cell infiltration in GC, SURF4-related differential genes and their associated pathways. In cultured GC cell line HGC-27, the effects of SURF4 knockdown and overexpression on proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) were investigated.

RESULTS

Analysis of GEPIA dataset and immunohistochemical results suggested significant SURF4 overexpression in GC (P<0.05), which was associated with shortened 5-year survival time of the patients (χ2=38.749, P<0.001). The prognosis of GC was closely related to tumor stage T3-4, N2-3, CEA≥5 μg/L and CA19-9≥37 kU/L (P<0.05). SURF4 expression level was negatively correlated with activated B cells, NK cells and CD8+ effector memory T cells (P<0.05) and positively correlated with CD4+ T cells (P<0.05). GO and KEGG enrichment analysis suggested that SUFR4 may participate in GC carcinogenesis by promoting EMT through the tight junction pathway. In HGC-27 cells, SURF4 overexpression significantly decreased E-cadherin expression, increased N-cadherin expression, inhibited ZO-1 and claudin-1 expressions, and promoted cell proliferation, migration and invasion.

CONCLUSIONS

SURF4 is highly expressed in GC, and its overexpression is associated with a shortened 5-year survival of the patients possibly by enhancing tumor cell proliferation, migration and invasion via inhibiting tight junction proteins and promoting EMT.