Ginsenoside Rh2 attenuates the progression of non-small cell lung cancer by sponging miR-28-5p/STK4 axis and inactivating Wnt/β-catenin signaling

Abstract

Background: Ginsenoside Rh2 (G-Rh2) exerts anti-tumor activity in non-small cell lung cancer (NSCLC). microRNAs (miRNAs, miRs) play pivotal roles in NSCLC. We aimed to investigate whether G-Rh2 inhibited NSCLC progression by targeting miRNA.

Methods: Cell viability, apoptosis and cycle were determined by Cell Counting Kit-8, 6-diamidino-2-phenylindole (DAPI) staining and flow cytometry. The potential target miRNAs of G-Rh2 were screened by real-time quantitative polymerase chain reaction (RT-qPCR). The difference in miR-28-5p expression between lung adenocarcinoma (LUAD) tissues and normal tissues or lung squamous cell carcinoma (LUSC) tissues and normal tissues was retrieved from TCGA-LUAD and TCGA-LUSC, respectively. Kaplan-Meier Plotter was conducted to analyze the survival rate for different serine/threonine-protein kinase 4 (STK4) expressions with different prognostic risks. immunohistochemistry of STK4 expression in non-tumor and tumor tissues was analyzed from the HPA database. RT-qPCR and Western blot were adopted for detecting mRNA and protein expression. TargetScan V7.2, miRanda and PITA were adopted for predicting targets of miR-28-5p, overlapped genes were subjected to GO analysis. The interactions of miR-28-5p-Wnt and miR-28-5p-STK4 were detected by TOP/FOP luciferase reporter assay and dual luciferase reporter assay, respectively.

Results: Current study observed that G-Rh2 reduced miR-28-5p expression in NSCLC cells dose-dependently. miR-28-5p was upregulated in NSCLC tissues and cells. The target genes of miR-28-5p were enriched in negative regulation of Wnt signaling. miR-28-5p inhibitor inactivated Wnt signaling, inhibited cell viability and cell cycle, while enhanced cell apoptosis of NSCLC cells by targeting STK4. G-Rh2 exerted the similar effects with miR-28-5p inhibitor by reducing miR-28-5p. G-Rh2 and miR-28-5p inhibitor exerted a synergistic effect on inhibiting NSCLC tumor growth.

Conclusion: In conclusion, G-Rh2 attenuates NSCLC development by affecting miR-28-5p/STK4 axis and inactivating Wnt signaling. Taken together, we project out a novel therapeutic target for NSCLC.

Keywords: Wnt/β-catenin signaling; ginsenoside Rh2 (G-Rh2); miR-28-5p/STK4 axis; non-small cell lung cancer (NSCLC); tumor growth.