Contribution of microRNA-30d to the prevention of the thyroid cancer occurrence and progression: mechanism and implications.

Thyroid cancer is a major endocrine tumor and represents an emerging health problem worldwide. MicroRNAs (miRNAs) have been addressed to participate in the pathogenesis and progression of thyroid cancer. However, it remains largely unknown what functions miR-30d may exert on thyroid cancer. This study, herein, aimed to identify the functional significance and machinery of miR-30d in the progression of thyroid cancer. MiR-30b presented aberrant low expression and ubiquitin-specific protease 22 (USP22) exhibited aberrant high expression in thyroid cancer tissues and cells. The current study proposed the possible machinery that miR-30d could target and negatively regulate USP22. Additionally, USP22 could enhance the stability of SIRT1 by inducing deubiquitination which consequently contributed to FOXO3a deacetylation-induced PUMA repression. Responding to the gain- or loss-of-function of miR-30d and/or USP22, behaviors of thyroid cancer cells were altered. Accordingly, miR-30d inhibited proliferation and promoted apoptosis of thyroid cancer cells by suppressing USP22 through SIRT1/FOXO3a/PUMA axis. The effects of miR-30d and USP22-mediated SIRT1/FOXO3a/PUMA axis on thyroid tumorigenesis were finally validated in murine models. We ultimately confirmed the anti-proliferative and pro-apoptotic effect of miR-30d via suppressing USP22 through in vivo findings. Conclusively, our findings highlight that the occurrence and progression of thyroid cancer can be suppressed by miR-30d-mediated inhibition of USP22 via the SIRT1/FOXO3a/PUMA axis, which provides a attractive therapeutic target for thyroid cancer treatment.

LncRNA TP73-AS1 promotes the development of Epstein-Barr virus associated gastric cancer by recruiting PRC2 complex to regulate WIF1 methylation.

BACKGROUND: Epstein-Barr virus associated gastric cancer (EBVaGC) become a growing health problem. TP73-AS1 showed high expression in EBVaGC cells. However, the function role and underlying mechanism of TP73-AS1 need further exploration. METHODS: The expressions of TP73-AS1, WIF1, EZH2, ß-catenin and epithelial-mesenchymal transition (EMT)-related proteins were detected using qRT-PCR and Western blotting. Cell proliferation, apoptosis, migration and invasion were measured by CCK-8, colony formation, flow cytometry, wound healing and transwell assays, respectively. WIF1 promoter methylation was analyzed by MS-PCR (MSP). RNA immunoprecipitation assay (RIP) and Chromatin immunoprecipitation assay (ChIP) measured the interactions of TP73-AS1/EZH2 and EZH2/WIF1. Subcutaneous tumor growth was monitored in nude mice and immunohistochemistry (IHC) detected proliferation marker Ki-67 expression. RESULTS: TP73-AS1 was increased while WIF1 was decreased in EBVaGC cells. Silencing of TP73-AS1 or overexpression of WIF1 repressed the growth and migration while promoted apoptosis of EBVaGC cells. Knockdown of WIF1 reversed the anticancer effect of TP73-AS1 silencing. TP73-AS1 promoted the binding of EZH2 to the WIF1 promoter by directly binding to EZH2, and thus inhibiting the expression of WIF1 by enhancing H3K27me3 level of WIF1 promoter. Moreover, TP73-AS1 activated Wnt/ß-catenin signaling pathway and promoted EMT by down-regulating WIF1. TP73-AS1 silencing inhibited the progression of EBVaGC in nude mice by epigenetically regulating WIF1. CONCLUSION: TP73-AS1 regulated the promoter methylation of WIF1 by recruiting PRC2 complex to WIF1 promoter region, thereby promoting the progression of EBVaGC. These observations provided a novel theoretical basis to investigate more effective therapies of EBVaGC.

Knockdown of circPUM1 impedes cell growth, metastasis and glycolysis of papillary thyroid cancer via enhancing MAPK1 expression by serving as the sponge of miR-21-5p.

BACKGROUND: Circular RNAs (circRNAs) are a crucial class of regulatory RNAs in cancer procession, including papillary thyroid cancer (PTC). Circ-Pumilio 1 (circPUM1) is a novel circRNA with the oncogenic function in ovarian cancer and lung cancer. However, the role of circPUM1 in PTC is undiscovered. OBJECTIVE: This study was performed to investigate the biological function and molecular mechanism of circPUM1 in PTC. METHODS: CircPUM1 and microRNA-21-5p (miR-21-5p) levels were analyzed via quantitative real-time polymerase chain reaction (qRT-PCR). Cellular viability and metastasis were measured using Cell Counting Kit 8 (CCK-8) and transwell migration/invasion assay. Glycolysis was evaluated by glucose uptake and lactate production. Associated proteins were examined applying with western blot. Dual-luciferase reporter assay and RNA pull-down assay were used to analyze the interaction between circPUM1 or mitogen-activated protein kinase 1 (MAPK1) and miR-21-5p. Moreover, the role of circPUM1 in vivo was explored by xenograft tumor experiment. RESULTS: Significantly, circPUM1 was upregulated in PTC tissue samples and cells. Cell growth, metastasis and glycolytic process of PTC cells were all inhibited after downregulation of circPUM1. Besides, circPUM1 could sponge miR-21-5p and MAPK1 was a target gene of miR-21-5p. Furthermore, we found that the anti-cancer effect of circPUM1 knockdown on PTC was partly ascribed to MAPK1 downregulation by upregulating miR-21-5p. Silencing circPUM1 also impeded tumorigenesis of PTC in vivo via miR-21-5p/MAPK1 axis. CONCLUSION: These findings suggested that circPUM1 knockdown inhibited MAPK1 expression by targeting miR-21-5p, consequently leading to the repressive effect on PTC progression. CircPUM1 might be a promising target to improve the diagnosis and treatment of PTC.

The FENDRR/miR-214-3P/TET2 axis affects cell malignant activity via RASSF1A methylation in gastric cancer.

To explore the effect of fetal-lethal non-coding developmental regulatory RNA (FENDRR) in the initiation and progression of gastric cancer (GC). We detected the levels of FENDRR, microRNA-214-3p (miR-214-3p), and ten-eleven-translocation (TET2) in GC tissues and GC cell lines. In addition, we evaluated the location of FENDRR in GC cell lines by fluorescence in situ hybridization (FISH). Cell proliferation and apoptosis were measured by CCK-8 and Hoechst staining assays. Methylation-specific PCR assay (MSP) was used to evaluate the methylation status of ras-association domain family 1A (RASSF1A). We also observed the direct binding of miR-214-3p on FENDRR by dual-luciferase activity assay in GC cells. FENDRR and TET2 expressions were significantly down-regulated and miR-214-3p was up-regulated in gastric cancer tissues compared to adjacent unaffected tissues. In addition, RASSF1A was hypermethylated in gastric cancer tissues compared to adjacent tissues. The expressions of all the three indicators were influenced by differentiation of tumor, TNM stage of tumors, and lymph node metastasis in patients with GC. A gastric cancer cell line with low FENDRR expression compared to a high FENDRR expressing cell line showed again increased miR-214-3p expression, decreased TET2 and RASSF1A expressions, and RASSF1A hypermethylation, resulting in decreased apoptosis and increased proliferation. Furthermore, we observed a negative correlation between FENDRR and miR-214-3p in GC. The FENDRR/miR-214-3P/TET2 axis plays a critical role in GC progress via methylation of RASSF1A.

Epigenetic silencing of olfactomedin-4 enhances gastric cancer cell invasion via activation of focal adhesion kinase signaling.

Downregulation of olfactomedin-4 (OLFM4) is associated with tumor progression, lymph node invasion and metastases. However, whether or not downregulation of OLFM4 is associated with epigenetic silencing remains unknown. In this study, we investigate the role of OLFM4 in gastric cancer cell invasion. We confirm the previous result that OLFM4 expression is increased in gastric cancer tissues and decreases with an increasing number of metastatic lymph nodes, which are associated with OLFM4 promoter hypermethylation. Overexpression of OLFM4 in gastric cancer cells had an inhibitory effect on cell invasion. Furthermore, we found that focal adhesion kinase (FAK) was negatively correlated with OLFM4 in regards to lymph node metastasis in gastric cancer tissues. Also, inhibition of FAK induced by OLFM4 knockdown resulted in a decrease in cell invasion. Thus, our study demonstrates that epigenetic silencing of OLFM4 enhances gastric cancer cell invasion via activation of FAK signaling.