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.     

NEAT1 contributes to ox-LDL-induced inflammation and oxidative stress in macrophages through inhibiting miR-128

Long noncoding RNAs (lncRNA) have been recognized as significant regulators in the progression of atherosclerosis (AS). Oxidized low-density lipoprotein (ox-LDL) can induce macrophage inflammation and oxidative stress, that serves important roles in AS. However, the exact function of lncRNA NEAT1 and its possible molecular mechanism in AS remain unclear. Here, we concentrated on the roles and molecular mechanisms of NEAT1 in AS development. In our current study, we observed that NEAT1 was elevated by ox-LDL in a dose-dependent and time-dependent manner. RAW264.7 cell survival was greatly enhanced, and cell apoptosis was significantly inhibited by LV-shNEAT1 transfection. In addition, knockdown of NEAT1 in RAW264.7 cells repressed CD36 expression and foam cell formation while NEAT1 overexpression shown an opposite process. Moreover, NEAT1 downregulation inhibited inflammation molecules including IL-6, IL-1β, and TNF-α. Meanwhile, silencing of NEAT1 can also suppress reactive oxygen species (ROS) and malondialdehyde (MDA) levels with an enhancement of superoxide dismutase (SOD) activity in RAW264.7 cells. MicroRNAs are some short RNAs, and they can regulate multiple biological functions in many diseases including AS. Here, we found that miR-128 expression was remarkably decreased in ox-LDL-incubated RAW264.7 cells. Interestingly, miR-128 mimics was able to reverse AS-correlated events induced by overexpression of NEAT1. By using bioinformatics analysis, miR-128 was predicted as a target of NEAT1 and the correlation between them was validated in our study. Taken these together, it was implied that NEAT1 participated in ox-LDL-induced inflammation and oxidative stress in AS development through sponging miR-128.     

lncRNA NEAT1 facilitates melanoma cell proliferation,migration, and invasion via regulating miR-495-3p and E2F3

Melanoma contributes a lot to skin cancer-related deaths. lncRNAs are implicated in various diseases, including melanoma. lncRNA NEAT1 is frequently dysregulated and can play important roles in multiple cancers. Nevertheless, little has been studied about the function of NEAT1 in melanoma progression. In our present research, we displayed NEAT1 was overexpressed in melanoma cells. A series of functional assays showed that overexpression of NEAT1 promoted the proliferation, migration, and invasion of melanoma cells. By contrast, NEAT1 knockdown obviously restrained melanoma cell progression. Mechanistically, it was revealed that NEAT1 could directly bind with miR-495-3p, which led to a negative effect on miR-495-3p levels. In addition, miR-495-3p was significantly decreased in melanoma cells. Furthermore, E2F3 was postulated as the target of miR-495-3p and overexpression of this miR could suppress the levels of E2F3. Meanwhile, it was exhibited that melanoma cell proliferation, migration, and invasion induced by E2F3 silence was abrogated by miR-495-3p. Moreover, an in vivo xenograft nude mice model was established using A375 cells and it was indicated that NEAT1 promoted melanoma progression in vivo via regulating the miR-495-3p/E2F3 axis. In conclusion, we suggest that NEAT1 exerts an oncogenic effect on melanoma development via inhibition of miR-495-3p and induction of E2F3. NEAT1 might serve as a crucial prognostic biomarker of melanoma.     

NEAT1 promotes colon cancer progression through sponging miR-495-3p and activating CDK6 in vitro and in vivo

Recently, increasing evidence has indicated lncRNAs are powerful regulators in the progression of multiple tumors. Dysregulation of lncRNA NEAT1 has been recognized in many cancer types. Meanwhile, the studies on NEAT1 function have suggested that NEAT1 can serve as a crucial oncogene. Nevertheless, the investigation of NEAT1 in colon cancer is still few. In our study, the function of NEAT1 was studied in colon cancer. As we observed, NEAT1 level was obviously elevated in colon cancer cells. Then, HCT-116 and SW620 cells were stably infected with shRNA-NEAT1 for 48 hr. As exhibited, silence of NEAT1 could greatly repress colon cancer cell progression. Apoptosis of colon cancer cells was triggered and the cell cycle progression was remarkably inhibited by downregulation of NEAT1. Interestingly, as exhibited, miR-495-3p was obviously decreased in colon cancer cells and it significantly suppressed colon cancer progression. Subsequently, miR-495-3p was predicted as a target of NEAT1. CDK6 was speculated as the target of miR-495-3p and miR-495-3p modulated its expression negatively. Finally, it was indicated that NEAT1 promoted colon cancer development through modulating miR-495-3p and CDK6 in vivo. Taken these together, we reported that NEAT1 could sponge miR-495-3p to contribute to colon cancer progression through activating CDK6.     

Involvement of NEAT1/miR-133a axis in promoting cervical cancer progression via targeting SOX4

NEAT1 is an important tumor oncogenic gene in various tumors. Nevertheless, its involvement remains poorly studied in cervical cancer. Our study explored the functional mechanism of NEAT1 in cervical cancer. NEAT1 level in several cervical cancer cells was quantified and we found NEAT1 was greatly upregulated in vitro. NEAT1 knockdown inhibited cervical cancer development through repressing cell proliferation, colony formation, capacity of migration, and invasion and also inducing the apoptosis. For another, microRNA (miR)-133a was downregulated in cervical cancer cells and NEAT1 negatively modulated miR-133a expression. Subsequently, we validated that miR-133a functioned as a potential target of NEAT1. Meanwhile, SOX4 is abnormally expressed in various cancers. SOX4 was able to act as a downstream target of miR-133a and silencing of SOX4 can restrain cervical cancer progression. In addition, in vivo assays were conducted to prove the role of NEAT1/miR-133a/SOX4 axis in cervical cancer. These findings implied that NEAT1 served as a competing endogenous RNA to sponge miR-133a and regulate SOX4 in cervical cancer pathogenesis. To sum up, it was implied that NEAT1/miR-133a/SOX4 axis was involved in cervical cancer development.     

Unusual semi‐extractability as a hallmark of nuclear body‐associated architectural noncoding RNAs

NEAT1_2 long noncoding RNA (lncRNA) is the molecular scaffold of paraspeckle nuclear bodies. Here, we report an improved RNA extraction method: extensive needle shearing or heating of cell lysate in RNA extraction reagent improved NEAT1_2 extraction by 20‐fold (a property we term “semi‐extractability”), whereas using a conventional method NEAT1_2 was trapped in the protein phase. The improved extraction method enabled us to estimate that approximately 50 NEAT1_2 molecules are present in a single paraspeckle. Another architectural lncRNA, IGS16, also exhibited similar semi‐extractability. A comparison of RNA‐seq data from needle‐sheared and control samples revealed the existence of multiple semi‐extractable RNAs, many of which were localized in subnuclear granule‐like structures. The semi‐extractability of NEAT1_2 correlated with its association with paraspeckle proteins and required the prion‐like domain of the RNA‐binding protein FUS. This observation suggests that tenacious RNA–protein and protein–protein interactions, which drive nuclear body formation, are responsible for semi‐extractability. Our findings provide a foundation for the discovery of the architectural RNAs that constitute nuclear bodies.     

Long noncoding RNA NEAT1 sponges miR-495-3p to enhance myocardial ischemia-reperfusion injury via MAPK6 activation

The biological function of long noncoding RNA NEAT1 has been revealed in a lot of diseases. Nevertheless, it is still not yet clear whether NEAT1 can modulate the process of myocardial ischemia–reperfusion injury (M-I/R). Here, we reported that NEAT1 was able to sponge miR-495-3p to contribute to M-I/R injury through activating mitogen-activated protein kinase 6 (MAPK6). First, elevated expression of NEAT1 was revealed in M-I/R injury mice, meanwhile, lactate dehydrogenase (LDH) and creatine kinase-muscle/brain (CK-MB) were also upregulated in the serum. Meanwhile, as previously reported, miR-495 serves as a tumor suppressor or an oncogenic miRNA in different types of cancer. Currently, we found miR-495-3p was remarkably reduced in M-I/R mice. Additionally, NEAT1 was significantly induced whereas miR-495-3p was greatly reduced by H₂O₂ treatment in H9C2 cells. Moreover, loss of NEAT1 in H9C2 cells could repress the viability and proliferation of cells. For another, overexpression of NEAT1 exhibited an opposite phenomenon. Furthermore, LDH release and caspase-3 activity were obviously triggered by upregulation of NEAT1 while suppressed by NEAT1 knockdown. miR-495-3p was indicated and validated as a target of NEAT1 using the analysis of bioinformatics. Interestingly, we observed that miR-495-3p mimics repressed tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-18 protein expression while their levels were enhanced by the inhibition of miR-495-3p in H9c2 cells. Subsequently, it was manifested that MAPK6 was a target of miR-495-3p, which could exert a lot in the NEAT1/miR-495-3p-mediated M-I/R injury. Overall, our results implied that NEAT1 contributed to M-I/R injury via the modulation of miR-495-3p and MAPK6.     

LncRNA NEAT1 promotes docetaxel resistance in prostate cancer by regulating ACSL4 via sponging miR-34a-5p and miR-204-5p

Docetaxel resistance remains one of the main problems in clinical treatment of metastatic prostate cancer (PCa). Previous studies identified differently expressed lncRNAs in docetaxel-resistant PCa cell lines, while the potential mechanisms were still unknown. In the present study, we found NEAT1 was expressed at high levels in docetaxel-resistant PCa clinical samples and related cell lines. When knockdown NEAT1, cell proliferation and invasion in docetaxel-resistant PCa cells in vitro and in vivo were downregulated. Our further researches explained that NEAT1 exerts oncogenic function in PCa by competitively ‘sponging’ both miR-34a-5p and miR-204-5p. Inhibition of miR-34a-5p or miR-204-5p expression mimics the docetaxel-resistant activity of NEAT1, whereas ectopic expression of miR-34a-5p or miR-204-5p attenuates the anti-drug function of NEAT1 in PCa cells. Besides, we also found ACSL4 is a target of both miR-34a-5p and miR-204-5p, and ACSL4 was also inhibited by miR-34a-5p and miR-204-5p. Moreover, suppression of miR-34a-5p or/and miR-204-5p greatly restrained the expression of ACSL4 upon NEAT1 overexpression. Joint expression of miR-34a-5p and miR-204a-5p synergistically decreased the expression of ASCL4, indicating miR-34a-5p and miR-204a-5p collaboratively inhibit the expression of ACSL4. Innovatively, we concluded that NEAT1 contributes to the docetaxel resistance by increasing ACSL4 via sponging miR-34a-5p and miR-204-5p in PCa cells.     

Blockade of NEAT1 represses inflammation response and lipid uptake via modulating miR-342-3p in human macrophages THP-1 cells

Atherosclerosis has been recognized as a chronic inflammation process induced by lipid of the vessel wall. Oxidized low-density lipoprotein (ox-LDL) can drive atherosclerosis progression involving macrophages. Recently, long noncoding RNAs (lncRNAs) have been reported to play critical roles in atherosclerosis development. In our current study, we focused on the biological roles of lncRNA NEAT1 in atherosclerosis progress. Here, we found that ox-LDL was able to trigger human macrophages THP-1 cells, a human monocytic cell line, apoptosis in a dose-dependent and time-dependent course. In addition, we observed that NEAT1 was significantly increased in THP-1 cells incubated with ox-LDL and meanwhile miR-342-3p was greatly decreased. Then, NEAT1 was silenced by transfection of small interfering RNA (siRNA) of NEAT1 into THP-1 cells. As exhibited, CD36, oil-red staining levels, total cholesterol (TC), total cholesterol (TG) levels and THP-1 cell apoptosis were obviously repressed by knockdown of NEAT1. Furthermore, inhibition of NEAT1 contributed to the repression of inflammation in vitro. Interleukin 6 (IL-6), IL-1β, cyclooxygenase-2 (COX-2) and tumour necrosis factor-alpha (TNF-α) protein levels were remarkably depressed by NEAT1 siRNA in THP-1 cells. By using bioinformatics analysis, miR-342-3p was predicted as a downstream target of NEAT1 and the correlation between them was confirmed in our study. Moreover, overexpression of miR-342-3p could also greatly suppress inflammation response and lipid uptake in THP-1 cells. Knockdown of NEAT1 and miR-342-3p mimics inhibited lipid uptake in THP-1 cells. In conclusion, we implied that blockade of NEAT1 repressed inflammation response through modulating miR-342-3p in human macrophages THP-1 cells and NEAT1 may offer a promising strategy to treat atherosclerotic cardiovascular diseases.     

RELA/NEAT1/miR-302a-3p/RELA feedback loop modulates pancreatic ductal adenocarcinoma cell proliferation and migration

Pancreatic ductal adenocarcinoma (PDAC) remains a challenging malignancy due to distant metastasis. RELA, a major component of the NF-κB pathway, could serve as an oncogene through activating proliferation or migration-related gene expression, including NEAT1, a well-known oncogenic long noncoding RNA. In the current study, the expression and function of RELA and NEAT1 in PDAC were examined. The potential upstream regulatory microRNAs of RELA were screened and verified for their correlation with RELA and NEAT1. The expression and function of the selected miR-302a-3p were evaluated. RELA and NEAT1 expression were upregulated in PDAC tissues, particularly in PDAC tissues with lymph node metastasis, and their expression correlated with clinical parameters. RELA overexpression promoted PDAC cell proliferation and migration, which could be partially attenuated by the NEAT1 knockdown. By binding to RELA, miR-302a-3p inhibited RELA expression, as well as PDAC cell proliferation and migration. RELA downstream NEAT1 expression was negatively regulated by miR-302a-3p; the suppressive effect of NEAT1 knockdown on PDAC cell proliferation and migration was partially attenuated by miR-302a-3p inhibition. Moreover, through direct binding, the expression of miR-302a-3p was also negatively regulated by NEAT1. The expression of miR-302a-3p was downregulated and negatively correlated with RELA or NEAT1 in tissue samples, indicating that rescuing miR-302a-3p expression may inhibit PDAC cell proliferation and migration through RELA/NEAT1. In summary, RELA, NEAT1, and miR-302a-3p form a feedback loop in PDAC to modulate PDAC cell proliferation and migration.     

LncRNA NEAT1 promotes extracellular matrix accumulation and epithelial-to-mesenchymal transition by targeting miR-27b-3p and ZEB1 in diabetic nephropathy

Diabetic nephropathy (DN) is a kind of microvascular complications of diabetes. Long noncoding RNAs (lnRNAs) can participate in the development of various diseases, including DN. However, the function of lncRNA NEAT1 is unclear. In our present study, we reported that NEAT1 was significantly increased in streptozotocin-induced DN rat models and high-glucose-induced mice mesangial cells. We observed that knockdown of NEAT1 greatly inhibited renal injury of DN rats. Meanwhile, downregulation of NEAT1-modulated extracellular matrix (ECM) proteins (ASK1, fibronectin, and TGF-β1) expression and epithelial–mesenchymal transition (EMT) proteins (E-cadherin and N-cadherin) in vitro. Previously, miR-27b-3p has been reported to be involved in diabetes. Here, miR-27b-3p was decreased in DN rats and high-glucose-induced mice mesangial cells. The direct correlation between NEAT1 and miR-27b-3p was validated using the dual-luciferase reporter assay and RNA immunoprecipitation experiments. In addition, zinc finger E-box binding homeobox 1 (ZEB1), which has been identified in the process of EMT clearly contributes to EMT progression. ZEB1 was predicted as a target of miR-27b-3p and overexpression of miR-27b-3p dramatically repressed ZEB1 expression. Therefore, our data implied the potential role of NEAT1 in the fibrogenesis and EMT in DN via targeting miR-27b-3p and ZEB1.