Background: Thyroid cancer is a frequent endocrine tumor in women. It is of great significance to investigate the molecular mechanism of progression of thyroid cancer.Methods: Gene expression data set and clinical data were downloaded from The Cancer Genome Atlas database for differential expression analysis. The triplet of downstream transcription factors (TFs) and modulatory genes of target lncRNA in thyroid cancer was predicted by the lncMAP database. mRNA and protein expression of lncRNA LBX2-AS1, RARα, and FSTL3 were detected by qRT-PCR and western blot. The localization of lncRNA LBX2-AS1 in cells was tested by Fluorescence in situ hybridization assay. The RNA immunoprecipitation assay was applied to verify the binding relationship between lncRNA LBX2-AS1 and FSTL3. ChIP and dual-luciferase assays were used to prove the binding relationship between RARα and FSTL3. Cell function experiments were used to test cell proliferation, migration and invasion in each treatment group. The role of lncRNA LBX2-AS1 in thyroid cancer progression was also confirmed in nude mice.Results: Bioinformatics analysis indicated that lncRNA LBX2-AS1, RARα, FSTL3 were remarkably fostered in thyroid cancer tissue, and LBX2-AS1 was evidently correlated with clinical features. The LncMAP triplet prediction showed that LBX2-AS1 recruited TF RARα to modulate FSTL3. RIP assay confirmed that LBX2-AS1 was prominently enriched on RARα. ChIP and dual-luciferase report assays unveiled that RARα bound to the promoter region of FSTL3 and functioned as a TF. Cell function experiments uncovered that LBX2-AS1 boosted the progression of thyroid cancer. The rescue experiments showed that LBX2-AS1 recruited the TF RARα to hasten the transcription activity of FSTL3 and thus promoted the development of thyroid cancer.Conclusion: The integrative results demonstrated that LBX2-AS1 activated FSTL3 by binding to TF RARα to hasten proliferation, migration and invasion of thyroid cancer.
Background Our preliminary experiments confirmed that follistatin-like 3 (FSTL3) expression is elevated in colorectal cancer (CRC) cells following CoCl 2 treatment. In this study, we investigated the regulatory role of FSTL3 in CRC progression and the molecular mechanisms underlying its high expression. Methods CoCl 2 (150 µM) was used to mimic hypoxia. Cell proliferation was measured by colony formation assay, wound healing assays were performed to assess cell migration, and Transwell assays were performed to evaluate invasion. The glucose metabolism pathways were assessed by detecting extracellular acidification rate, oxygen consumption rate, glucose uptake, and lactate production. The binding sites of zinc finger protein 454 (ZNF454) and FSTL3 gene promoter were analyzed by JASPAR databases, and were confirmed by chromatin immunoprecipitation (ChIP) and luciferase reporter assay. The expression levels of molecules at mRNA and protein levels were determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot, respectively. Results We found that both FSTL3 and hypoxia-inducible factor 1α (HIF-1α) were upregulated in CRC tissues and in CRC cells under hypoxic conditions, with a positive correlation between their expression in clinical samples. Silencing FSTL3 reduced HIF-1α expression and suppressed the expression of glycolytic enzymes (glucose transporter 1, hexokinase 2, lactate dehydrogenase A, and pyruvate kinase muscle isozyme M2). Knockdown of FSTL3 increased oxygen consumption while decreasing extracellular acidification, glucose uptake, and lactate production. Moreover, FSTL3 downregulation markedly inhibited the proliferation, migration, and invasion of CoCl 2 -treated CRC cells. We further identified ZNF454 as a potential transcription factor for FSTL3 and confirmed its binding to the FSTL3 promoter. Upregulation of ZNF454 significantly suppressed CRC cell proliferation, migration, invasion, and glycolysis, effects that were reversed by FSTL3 overexpression. In vivo , ZNF454 overexpression effectively inhibited tumor growth and reduced HIF-1α and glycolytic enzyme expression, whereas these effects were rescued by FSTL3 overexpression. Conclusions Collectively, our findings demonstrate that ZNF454 suppresses CRC development by inhibiting FSTL3/HIF-1α-mediated glycolysis through transcriptional repression of FSTL3. This study is the first to reveal the molecular mechanism responsible for FSTL3 overexpression in CRC, providing a novel perspective for CRC treatment.
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