LncRNA SNHG4 promotes the proliferation, migration, invasiveness, and epithelial-mesenchymal transition of lung cancer cells by regulating miR-98-5p

Long noncoding RNA small nucleolar RNA host gene 4 (SNHG4) is usually up-regulated in cancer and regulates the malignant behavior of cancer cells. However, its role in lung cancer remains elusive. In this study, we silenced the expression of SNHG4 in NCI-H1437 and SK-MES-1, two representative non-small-cell lung cancer cell lines, by transfecting them with siRNA (small interfering RNA) that specifically targets SNHG4. We observed significantly inhibited cell proliferation in vitro and reduced tumor growth in vivo after SNHG4 silencing. SNHG4 knockdown also led to cell cycle arrest at the G1 phase, accompanied with down-regulation of cyclin-dependent kinases CDK4 and CDK6. The migration and invasiveness of these two cell lines were remarkably inhibited after SNHG4 silencing. Moreover, our study revealed that the epithelial-mesenchymal transition (EMT) of lung cancer cells was suppressed by SNHG4 silencing, as evidenced by up-regulated E-cadherin and down-regulated SALL4, Twist, and vimentin. In addition, we found that SNHG4 silencing induced up-regulation of miR-98-5p. MiR-98-5p inhibition abrogated the effect of SNHG4 silencing on proliferation and invasion of lung cancer cells. In conclusion, our findings demonstrate that SNHG4 is required by lung cancer cells to maintain malignant phenotype. SNHG4 probably exerts its pro-survival and pro-metastatic effects by sponging anti-tumor miR-98-5p.