Nm23‐H1 inhibits lung cancer bone‐specific metastasis by upregulating miR‐660‐5p targeted SMARCA5

BACKGROUND: Nm23-H1 gene has been found to be an inhibitor of tumor metastasis in lung cancer. MicroRNAs (miRNAs) play key roles in tumor metastasis through multiple signaling pathways. This study explored whether the nm23-H1 gene could inhibit invasion and metastasis of lung cancer cells by regulating miRNA-660-5p targets. METHODS: Quantitative real-time PCR (qRT-PCR) and western blots were used to measure the expression of nm23-H1 and miR-660-5p of various human lung cancer cell lines. Cell counting kit-8 (CCK-8), wound-healing and transwell assay were carried out to assess cell proliferation, migration and invasion of each cell line. Xenograft were applied to determine in vivo effects of miR-660-5p among nude mice. Luciferase assay and western blot were performed to determine the target gene of miR-660-5p. RESULTS: We found that high expression of nm23-H1 correlated with decreased miRNA-660-5p expression. Inhibiting miR-660-5p suppressed lung cancer cells progression significantly in vitro, whereas overexpression of miR-660-5p facilitated tumor growth and bone metastasis in vivo. In addition, as the potential target gene of miR-660-5p, SMARCA5 overexpression in vitro suppressed tumor progression and osteolytic metastasis associated RANKL signaling, which is congruent with the effect of nm23-H1 on the lung cancer cells. CONCLUSION: Nm23-H1 inhibits tumor progression and bone-specific metastasis of lung cancer by regulating miR-660-5p/SMARCA5/RANKL axis, which indicates the related genes may serve as potential targets for the treatment of human lung cancer. KEY POINTS: Significant findings of the study High expression of nm23-H1 correlated with decreased miRNA-660-5p expression. Further, downregulation of miR-660-5p significantly suppressed the tumor progression and bone-specific metastasis of lung cancer cells. What this study adds This is the first study to show an inverse association between nm23-H1 and miR-660-5p, and confirm that nm23-H1 inhibits tumor progression and bone-specific metastasis of lung cancer by regulating miR-660-5p/SMARCA5/RANKL axis.