Dicer Enhances Bevacizumab-Related Inhibition of Hepatocellular Carcinoma via Blocking the Vascular Endothelial Growth Factor Pathway

Dicer Suppresses Hepatocellular Carcinoma via Interleukin-8 Pathway

Background

Elevated level of interleukin-8 (IL-8) promotes hepatocellular carcinoma (HCC) development and contributes to poor prognosis. Previously, we have proved that Dicer inhibits HCC progression. In this study, we evaluated the potential interaction between IL-8 and Dicer as well as their influence on HCC.

Methods

Hepatocellular carcinoma cells of SMMC-7721 were divided into 2 groups for subsequent analysis: pCMV-Dicer group for Dicer-overexpressing lentivirus transfected cells (pCMV-Dicer cells) and pCMV-NC group for empty lentivirus transfected cells (pCMV-NC cells). Cell Counting kit-8 (CCK8), wound healing, and transwell were used to evaluate the inhibitory effect of Dicer overexpression on proliferation, migration, and invasion of HCC cells. The level of IL-8 was measured by flow cytometry bead-based immunoassays. Male nude BALB/c mice injected with pCMV-Dicer or pCMV-NC cell suspensions was used for transplant of HCC tumor.

Results

We found that the secretion of IL-8 was reduced in the medium of pCMV-Dicer cells (P = .027). Recombinant human IL-8 (rhIL-8) reversed the inhibitory effect of Dicer on proliferation (P < .01), migration (P = .003), and invasion (P = .001), whereas IL-8 inhibitor of reparixin enhanced inhibitory effect of Dicer on proliferation (P < .05), migration (P = .008), and invasion (P = .000). Lenvatinib downregulated the IL-8 level of HCC cells (P = .000) as well as promote Dicer-induced inhibition for HCC cells referring to proliferation (P < .05), migration (P = .000), and invasion (P = .000). Animal experiments also demonstrated that Dicer cooperated with lenvatinib to inhibit the growth of HCC tumors (P < .05).

Conclusions

Dicer cooperated with lenvatinib to inhibit HCC growth via downregulating IL-8, and Dicer displayed its potential capability to enhance the anti-tumor effect of lenvatinib.

Dicer-mediated miR-200b expression contributes to cell migratory/invasive abilities and cancer stem cells properties of breast cancer cells

Distant metastasis is the leading cause of death in patients with breast cancer. Despite considerable treatment advances, the clinical outcomes of patients with metastatic breast cancer remain poor. CSCs can self-renew, enhancing cancer progression and metastasis. Dicer, a microRNA (miRNA) processing–related enzyme, is required for miRNA maturation. Imbalanced Dicer expression may be pivotal in cancer progression. However, whether and how Dicer affects the stemness of metastatic breast cancer cells remains unclear. Here, we hypothesized that Dicer regulates the migration, invasion, and stemness of breast cancer cells. We established highly invasive cell lines (MCF-7/I-3 and MDA-MB-231/I-3) and observed that Dicer expression was conspicuously lower in the highly invasive cells than in the parental cells. The silencing of Dicer significantly enhanced the cell migratory/invasive abilities and CSCs properties of the breast cancer cells. Conversely, the overexpression of Dicer in the highly invasive cells reduced their migration, invasion, and CSCs properties. Our bioinformatics analyses demonstrated that low Dicer levels were correlated with increased breast cancer risk. Suppression of Dicer inhibited miR-200b expression, whereas miR-200b suppression recovered Dicer knockdown–induced migration, invasion, and cancer stem cells (CSCs) properties of the breast cancer cells. Thus, our findings reveal that Dicer is a crucial regulator of the migration, invasion, and CSCs properties of breast cancer cells and is significantly associated with poor survival in patients with breast cancer.