Abstract
OBJECTIVE: The study explored the molecular mechanism of circNOLC1 influencing Testicular Germ Cell Tumor (TGCT) progression. METHODS: The study used TGCT tissue samples and cell lines for investigations. The circNOLC1 and miR-140-5p expression in TGCT tissues were done through RT-qPCR. Analysis of the association of circNOLC1 with TGCT clinic-pathological features was also done. Transfections of circNOLC1, miR-140-5p or Insulin-like GrowthFfactor 1 Receptor (IGF1R)-related sequences or plasmids into TCAM-2 and NCCIT TGCT cells were done. The circNOLC1, miR-140-5p, and IGF1R mRNA expression in cells were done through RT-qPCR. Interaction between miR-140-5p, circNOLC1, and IGF1R was examined using a dual-luciferase reporter assay. MTT assay and colony-forming assay were used to investigate cell proliferation. Apoptosis was determined by flow cytometry. Transwell assay was used to investigate cell invasion. IGF1R protein expression was determined through a western blot. RESULTS: Increased circNOLC1 in TGCT tissues was correlated with lymph node metastasis, clinical stage, and pathological grade of TGCT patients. CircNOLC1 knock-down inhibited TGCT cell proliferation, colony formation, and invasion, and promotedapoptosis. MiR-140-5p was reduced while IGF1R was upregulated in TGCT tissues and cell lines. Moreover, miR-140-5p mimic could reverse the effect of circNOLC1 knock-down on malignant behaviors of TGCT cells. The authors demonstrated that elevated IGF1R reversed the negative effect of miR-140-5p mimic on TGCT cell proliferation, colony formation, and invasion. CircNOLC1 can act as a sponge of miR-140-5p to up-regulate the IGF1R expression level. CONCLUSION: The study highlights that circNOLC1 promotes the progression of TGCT by regulating the miR-140-5p/IGF1R axis.