Fluid shear stress regulates osteoblast proliferation and apoptosis via the lncRNA TUG1/miR-34a/FGFR1 axis

LncRNAs and microRNAs play critical roles in osteoblast differentiation and bone formation. However, their exact roles in osteoblasts under fluid shear stress (FSS) and the possible mechanisms remain unclear. The aim of this study was to explore whether and how miR-34a regulates osteoblast proliferation and apoptosis under FSS. In this study, FSS down-regulated miR-34a levels of MC3T3-E1 cells. MiR-34a up-regulation attenuated FSS-induced promotion of proliferation and suppression of apoptosis. Luciferase reporter assay revealed that miR-34a directly targeted FGFR1. Moreover, miR-34a regulated osteoblast proliferation and apoptosis via FGFR1. Further, we validated that lncRNA TUG1 acted as a competing endogenous RNA (ceRNA) to interact with miR-34a and up-regulate FGFR1 protein expression. Furthermore, lncRNA TUG1 could promote proliferation and inhibit apoptosis. Taken together, our study revealed the key role of the lncRNA TUG1/miR-34a/FGFR1 axis in FSS-regulated osteoblast proliferation and apoptosis and may provide potential therapeutic targets for osteoporosis.     

MicroRNA-34A inhibits the growth,invasion and metastasis of gastric cancer by targeting PDGFR and MET expression

Within the family of RTKs (receptor tyrosine kinases), PDGFR (platelet-derived growth factor receptor) has been implicated in carcinogenesis and tumour development. miRNAs (microRNAs), which can target the mRNAs (messenger RNAs) of cancer-associated genes, are abnormally expressed in various cancers. In this study, our aim was to identify the miRNAs that target PDGFR-α/β and to study the functions of these miRNAs. miR-34a was predicted to target PDGFR, and luciferase reporter assays showed that miR-34a could directly target PDGFR. Meanwhile, we found that miR-34a was down-regulated in gastric cancer tissues and was associated with metastasis. Our findings showed that miR-34a could inhibit gastric cancer cell migration, invasion and proliferation, but these tumourigenic properties were only partially restored when PDGFR-α/β was overexpressed. In subsequent experiments, we found that the overexpression of both PDGFR and MET could completely restore the gastric cancer tumourigenic properties. Moreover, the cancer-associated cell signalling pathway was studied, and we found that miR-34a could inhibit Akt [PKB (protein kinase B)] phosphorylation, which was restored by the overexpression of both PDGFR and MET. In conclusion, miR-34a may act as a potential tumour suppressor in gastric cancer and is associated with the mechanisms of gastric cancer metastasis; miR-34a can inhibit gastric cancer tumourigenesis by targeting PDGFR and MET through the PI3K (phosphoinositide 3-kinase)/Akt pathway.     

Long noncoding RNA NEAT1-modulated miR-506 regulates gastric cancer development through targeting STAT3

Accumulating evidence has indicated that long noncoding RNA NEAT1 exerts critical roles in cancers. So far, the detailed biological role and mechanisms of NEAT1, which are responsible for human gastric cancer (GC), are still largely unknown. Here, we observed that NEAT1 and STAT3 expressions were significantly upregulated in human GC cells including BGC823, SGC-7901, AGS, MGC803, and MKN28 cells compared with normal gastric epithelial cells GES-1, while miR-506 was downregulated. We inhibited NEAT1 and observed that NEAT1 inhibition was able to repress the growth, migration, and invasion of GC cells. Conversely, overexpression of NEAT1 exhibited an increased ability of GC progression in BGC823 and SGC-7901 cells. Bioinformatics analysis, dual luciferase reporter assays, RIP assays, and RNA pull-down tests validated the negative binding correlation between NEAT1 and miR-506. In addition, it was found that miR-506 can modulate the expression of NEAT1 in vitro. STAT3 was predicted as a messenger RNA (mRNA) target of miR-506, and miR-506 mimics can suppress STAT3 mRNA expression. Subsequently, it was observed that downregulation of NEAT1 can restrain GC development by decreasing STAT3, which can be reversed by miR-506 inhibitors. Therefore, it was hypothesized in our study that NEAT1 can be recognized as a competing endogenous RNA to modulate STAT3 by sponging miR-506 in GC. In conclusion, we implied that NEAT1 can serve as an important biomarker in GC diagnosis and treatment.     

miR-148a promoted cell proliferation by targeting p27 in gastric cancer cells

Accumulating evidence has shown that miRNAs are aberrantly expressed in human gastric cancer and crucial to tumorigenesis. Herein, we identified the role of miR-148a in gastric cell proliferation. miR-148a knockdown inhibited cell proliferation in gastric cancer cell lines. Conversely, miR-148a overexpression promoted cell proliferation and cell cycle progression. p27, a key inhibitor of cell cycle, was verified as the target of miR-148a, indicating miR-148a might downregulate p27 expression to promote gastric cell proliferation. Moreover, we confirmed that miR-148a expression was frequently and dramatically downregulated in human advanced gastric cancer tissues, and observed a good inverse correlation between miR-148a and p27 expression in tumor samples. Thus, our results demonstrated that miR-148a downregulation might exert some sort of antagonistic function in cell proliferation, rather than promote cell proliferation in gastric cancer.     

lncRNA RPL34-AS1 inhibits cell proliferation and invasion while promoting apoptosis by competitively binding miR-3663-3p/RGS4 in papillary thyroid cancer

Papillary thyroid cancer (PTC) accounts for 80% of all thyroid cancers and seriously impacts the quality of people's lives. Long noncoding RNAs (lncRNAs) play an important role in PTC. In previous studies, thousands of lncRNAs were screened to study their potential relationships with PTC. The aim of this study was to investigate the effect of RPL34-AS1 in PTC and to explore its potential mechanisms. Bioinformatic analyses were performed to characterize the possible function and biological features of RPL34-AS1. Apoptosis, proliferation, and invasion were detected to assess the effect of RPL34-AS1. Cell proliferation was measured using a Cell Counting Kit-8 assay. Western blot analysis was used to assess the apoptosis proteins Bax and Bcl-2. Cell invasion was measured using a Transwell assay. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis was performed to examine RPL34-AS1, miR-3663-3P, and RGS4 expression. Dual-luciferase assay was performed to assess the binding of miR-3663-3P by RPL34-AS1. RIP experiment was used to verify the combination between miR-3663-3p and RGS4. We found that overexpression of RPL34-AS1 could inhibit proliferation and invasion while promoting apoptosis in PTC cell lines. Moreover, RPL34-AS1 could also competitively bind miR-3663-3p and exert its function by regulating the miR-3663-3p/RGS4 in PTC cell lines. We found a previously uncharacterized lncRNA, RPL34-AS1, and studied its function and mechanism in PTC. Our research will provide new insights into PTC and new clues for its clinical treatment.     

Chaperone-mediated autophagy regulates proliferation by targeting RND3 in gastric cancer

LAMP2A is the key protein of chaperone-mediated autophagy (CMA), downregulation of LAMP2A leads to CMA blockade. CMA activation has been implicated in cancer growth, but the exact mechanisms are unclear. Elevated expression of LAMP2A was found in 8 kinds of tumors (n=747), suggesting that LAMP2A may have an important role in cancer progression. Unsurprisingly, LAMP2A knockdown in gastric cancer (GC) cells hindered proliferation, accompanied with altered expression of cell cycle-related proteins and accumulation of RND3/RhoE. Interactomic and KEGG analysis revealed that RND3 was a putative CMA substrate. Further study demonstrated that RND3 silencing could partly rescue the proliferation arrest induced by LAMP2A knockdown; RND3 was increased upon lysosome inhibition via both chemicals and LAMP2A-shRNA; Furthermore, RND3 could interact with CMA components HSPA8 and LAMP2A, and be engulfed by isolated lysosomes. Thus, constant degradation of RND3 by CMA is required to sustain rapid proliferation of GC cells. At last, the clinical significance of LAMP2A was explored in 593 gastric noncancerous lesions and 173 GC tissues, the results revealed that LAMP2A is a promising biomarker for GC early warning and prognosis of female GC patients.     

SATB1 3′-UTR and lncRNA-UCA1 competitively bind to miR-495-3p and together regulate the proliferation and invasion of gastric cancer

High expression of special AT-rich-binding protein 1 (SATB1) correlates with the advanced TNM stage and short overall and recurrence-free survival of gastric cancer (GC). A bioinformatic analysis revealed that SATB1 3′-untranslated region (3′-UTR) and long noncoding RNA UCA1 (lncRNA-UCA1) might competitively bind to microRNA-495-3p (miR-495-3p). Interestingly, lncRNA-UCA1 is also an important contributor to GC. The current study aimed to demonstrate the potential interaction among SATB1/miR-495-3p/lncRNA-UCA1 network and their effects on GC proliferation and invasion. The expression in GC and paracancerous normal tissues were assessed using real-time polymerase chain reaction and Western blot analysis. Luciferase reporter, RNA pull-down, and transfection assays were performed to determine the interaction among SATB1/miR-495-3p/lncRNA-UCA1 network in GC cells. GC proliferation and invasion were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, transwell invasion, and colony formation assays. Results showed higher expression of SATB1 and lncRNA-UCA1 but lower miR-495-3p expression in GC than in the normal tissues. In luciferase reporter assay, miR-495-3p bound to three seed sequences in SATB1 3′-UTR but only one in lncRNA-UCA1. SATB1 knockdown increased the combination of miR-495-3p with lncRNA-UCA1 but decreased lncRNA-UCA1 expression. Decreased lncRNA-UCA1 was also observed with the mimics increased miR-495-3p. These data suggested that SATB1 3′-UTR functions as a competing endogenous RNA of miR-495-3p and positively regulates lncRNA-UCA1. LncRNA-UCA1 knockdown only decreased SATB1 expression in MKN-45 cells but not in BGC-823 cells, which suggested that the regulatory effect of lncRNA-UCA1 on SATB1 by sponging miR-495-3p is cell-dependent. This study further identified that SATB1/miR-495-3p/lncRNA-UCA1 network is implicated in GC proliferation and invasion. The current study firstly revealed that SATB1 interacts with miR-495-3p/lncRNA-UCA1 network, whereby enhancing GC proliferation and invasion.     

Long noncoding RNA ZEB1-AS1 attenuates ferroptosis of gastric cancer cells through modulating miR-429/BGN axis

Gastric cancer (GC) is the fifth utmost common malignant cancer type globally, in which ferroptosis acts a critical function in the progress of GC. Long noncoding RNA ZEB1-AS1 has been recognized in numerous cancers, but the role of ZEB1-AS1 in ferroptosis remains obscure. Hence, we investigated the efficacy of ZEB1-AS1 on ferroptosis of GC cells. The cell growth and viability were analyzed via cell counting kit assay and xenograft tumor model in vivo and in vitro, respectively. The RNA and protein expression were measured by qRT-PCR and western blot analysis assay, respectively. The levels of Fe²⁺, malondialdehyde (MDA), and lipid reactive oxygen species (ROS) were tested to determine ferroptosis. The erastin and RSL3 were used to induce ferroptosis. The mechanism was analyzed via luciferase reporter gene and RIP assays. The treatment of ferroptosis inducer Erastin and RSL3 suppressed the viability of GC cells and the ZEB1-AS1 overexpression rescued the phenotype in the cells. The levels of Fe²⁺, MDA, and ROS were enhanced through the depletion of ZEB1-AS1 in Erastin/RSL3 treated GC cells. ZEB1-AS1 directly sponged miR-429 in GC cells and miR-429 targeted BGN in GC cells, and the inhibition of miR-429 rescued ZEB1-AS1 depletion-inhibited BGN expression. We validated that miR-429 induced and BGN-repressed ferroptosis in cancer cells. The BGN overexpression and miR-429 suppression could reverse the efficacy of ZEB1-AS1 on proliferation and ferroptosis in cancer cells. The expression of ZEB1-AS1 and BGN was enhanced and miR-429 expression was decreased in clinical GC tissues. ZEB1-AS1 attenuated ferroptosis of cancer cells by modulating miR-429/BGN axis.     

METTL16 promotes cell proliferation by up-regulating cyclin D1 expression in gastric cancer

N6-methyladenosine (m6A) is a well-known modification of RNA. However, as a key m6A methyltransferase, METTL16 has not been thoroughly studied in gastric cancer (GC). Here, the biological role of METTL16 in GC and its underlying mechanism was studied. Immunohistochemistry was used to detect the expression of METTL16 and relationship between METTL16 level and prognosis of GC was analysed. CCK8, colony formation assay, EdU assay and xenograft mouse model were used to study the effect of METTL16. Regulatory mechanism of METTL16 in the progression of GC was studied through flow cytometry analysis, RNA degradation assay, methyltransferase inhibition assay, RT-qPCR and Western blotting. METTL16 was highly expressed in GC cells and tissues and was associated with prognosis. In vitro and in vivo experiments confirmed that METTL16 promoted proliferation of GC cells and tumour growth. Furthermore, down-regulation of METTL16 inhibited proliferation by G1/S blocking. Significantly, we identified cyclin D1 as a downstream effector of METTL16. Knock-down METTL16 decreased the overall level of m6A and the stability of cyclin D1 mRNA in GC cells. Meanwhile, inhibition of methyltransferase activity reduced the level of cyclin D1. METTL16-mediated m6A methylation promotes proliferation of GC cells through enhancing cyclin D1 expression.