Dicer Inhibits Hepatocellular Carcinoma by Inhibiting the Interleukin 6 Pathway

Background: Inflammatory cytokines are related to the occurrence and development of hepatocellular carcinoma (HCC). Objectives: Interleukin 6 (IL-6) is associated with the occurrence and prognosis of HCC, while Dicer inhibits HCC; accordingly, we checked whether Dicer regulates HCC by modulating the IL-6 pathway. Methods: The HCC cells of SMMC-7721 transfected with Dicer overexpression (pCMV-Dicer) and control (pCMV-NC) lentivirus were divided into 3 groups: The SMMC-7721, pCMV-NC, and pCMV-Dicer groups. The assays of cell proliferation, migration, and invasion were performed using cell counting, wound scratch, and transwell chamber assay. The IL-6 level was measured by flow cytometry bead-based immunoassays. All statistical analyses were analyzed using SPSS version 21 by the student t test and 1-way analysis of variance (ANOVA). Results: Dicer inhibited the secretion of IL-6 from HCC cells, as well as the growth of HCC related to proliferation, migration, and invasion. IL-6 incubation with pCMV-NC cells increased proliferation (from 24 hours to 72 hours; P < 0.05), migration (P = 0.008), and invasion (P = 0.85). In addition, IL-6 could reverse the inhibitory effect of Dicer on HCC cells related to proliferation (P < 0.01) and migration (P = 0.006) when incubated with pCMV-Dicer cells, whereas an IL-6 blocker of tocilizumab could enhance the Dicer-induced inhibition related to proliferation (P < 0.05), migration (P = 0.007), and invasion (P = 0.001) when incubated with pCMV-Dicer cells. Furthermore, Dicer could increase the inhibition efficiency of apatinib on HCC treatment by their cooperation in IL-6 downregulation. Conclusions: Dicer could inhibit HCC by the IL-6 pathway, which would be a potential target for HCC treatment. The Dicer inducer might be an enhancer of apatinib for HCC treatment.