Overexpression of XIST facilitates cell proliferation, invasion and suppresses cell apoptosis by reducing radio-sensitivity of glioma cells via miR-329-3p/CREB1 axis

Dexmedetomidine attenuates hippocampal neuroinflammation in postoperative neurocognitive disorders by inhibiting microRNA-329-3p and activating the CREB1/IL1RA axis

RATIONALE

Due to its anti-inflammatory effect, dexmedetomidine (DEX) can confer neuroprotection in postoperative neurocognitive disorders (NCD). Here, the mechanism responsible for this effect of DEX is rarely ascertained.

OBJECTIVES

Our research was implemented to figure out mechanism governing the protection of DEX against hippocampal neuroinflammation in postoperative NCD.

METHODS

Exploratory laparotomy was applied for generating a postoperative NCD mouse model before bilateral hippocampal injection with microRNA (miR)-329-3p-agomir and intraperitoneal injection with DEX. Cognitive function of mice was evaluated by water maze test and fear conditioning test. Immunofluorescence was performed to assess microglial activation in hippocampus. After cell transfection and DEX treatment, mouse microglial cells (BV-2) were stimulated by lipopolysaccharide (LPS). IL-1β, IL-6, and TNF-α levels and the number of phagocytes were assessed by ELISA and flow cytometry. Dual-luciferase reporter assay was adopted to assess the relationship between miR-329-3p and CREB1.

RESULTS

miR-329-3p expression was reduced in the postoperative NCD mice after DEX treatment. DEX treatment or miR-329-3p downregulation caused attenuated cognitive dysfunction and microglia activation as well as reduced IL-1β, IL-6, and TNF-α levels in the hippocampus of the postoperative NCD mice. Mechanistically, miR-329-3p inversely targeted CREB1 that activated IL1RA in LPS-induced BV-2 cells. DEX treatment, miR-329-3p inhibition, or CREB1 or IL1RA upregulation curtailed the release of proinflammatory proteins and the number of phagocytes in LPS-induced BV-2 cells.

CONCLUSIONS

Collectively, our data provided the novel insight of the neuroprotective mechanism of DEX in postoperative NCD pertaining to the miR-329-3p/CREB1/IL1RA axis.

The Mechanism of Long Non-coding RNA in Cancer Radioresistance/Radiosensitivity: A Systematic Review

Background and purpose: Radioresistance remains a significant challenge in tumor therapy. This systematic review aims to demonstrate the role of long non-coding RNA (lncRNA) in cancer radioresistance/radiosensitivity.

Material and methods: The electronic databases Pubmed, Embase, and Google Scholar were searched from January 2000 to December 2021 to identify studies addressing the mechanisms of lncRNAs in tumor radioresistance/sensitivity, each of which required both in vivo and in vitro experiments.

Results: Among the 87 studies identified, lncRNAs were implicated in tumor radioresistance/sensitivity mainly in three paradigms. 1) lncRNAs act on microRNA (miRNA) by means of a sponge, and their downstream signals include some specific molecular biological processes (DNA repair and chromosome stabilization, mRNA or protein stabilization, cell cycle and proliferation, apoptosis-related pathways, autophagy-related pathways, epithelial-mesenchymal transition (EMT), cellular energy metabolism) and some signaling mediators (transcription factors, kinases, some important signal transduction pathways) that regulate various biological processes. 2) lncRNAs directly interact with proteins, affecting the cell cycle and autophagy to contribute to tumor radioresistance. 3) lncRNAs act like transcription factors to initiate downstream signaling pathways and participate in tumor radioresistance.

Conclusion: lncRNAs are important regulators involved in tumor radioresistance\sensitivity. Different lncRNAs may participate in the radioresistance with the same regulatory paradigm, and the same lncRNAs may also participate in the radioresistance in different ways. Future research should focus more on comprehensively characterizing the mechanisms of lncRNAs in tumor radioresistance to help us identify corresponding novel biomarkers and develop new lncRNA-based methods to improve radioresistance.

Downregulation of lncRNA FOXD2-AS1 Confers Radiosensitivity to Gastric Cancer Cells via miR-1913/SETD1A Axis

Long noncoding RNA FOXD2 adjacent opposite strand RNA1 (FOXD2-AS1) plays an oncogenic role in various cancers, including gastric cancer (GC). However, the function of FOXD2-AS1 in regulating radiosensitivity of GC cells and its underlying molecular mechanisms have not been elucidated. This study aimed to figure out the potential mechanisms of FOXD2-AS1 in regulating GC cell radiosensitivity. RT-qPCR revealed upregulation of FOXD2-AS1 in GC cells exposed to radiation. Subcellular fractionation assay was used to localize FOXD2-AS1 in GC cells. Colony formation, MTT, EdU, and flow cytometry assays were performed to investigate the role of FOXD2-AS1 in regulating cell proliferation, cell cycle progression, and cell apoptosis. Western blotting was used to assess protein levels of apoptosis-associated markers and SET domain containing 1A (SETD1A). Homologous recombination reporter assay was conducted to explore the effect of FOXD2-AS1 on DNA damage repair. The downstream molecules of FOXD2-AS1 were identified with RNA pulldown, luciferase reporter, and RNA immunoprecipitation assays. The results showed that FOXD2-AS1 knockdown suppressed cell proliferation and cell cycle progression and promoted cell apoptosis and radiosensitivity of GC. FOXD2-AS1 could bind with miR-1913 in GC cells. In addition, miR-1913 targeted SETD1A, which was highly expressed in GC cells. Overexpression of SETD1A reversed FOXD2-AS1 silencing-induced effects on proliferation, apoptosis, and radiosensitivity of GC cells. In conclusion, knocking down FOXD2-AS1 enhances the radiosensitivity of GC cells by sponging miR-1913 to upregulate SETD1A expression.

MicroRNA Alterations Induced in Human Skin by Diesel Fumes, Ozone, and UV Radiation

Epigenetic alterations are a driving force of the carcinogenesis process. MicroRNAs play a role in silencing mutated oncogenes, thus defending the cell against the adverse consequences of genotoxic damages induced by environmental pollutants. These processes have been well investigated in lungs; however, although skin is directly exposed to a great variety of environmental pollutants, more research is needed to better understand the effect on cutaneous tissue. Therefore, we investigated microRNA alteration in human skin biopsies exposed to diesel fumes, ozone, and UV light for over 24 h of exposure. UV and ozone-induced microRNA alteration right after exposure, while the peak of their deregulations induced by diesel fumes was reached only at the end of the 24 h. Diesel fumes mainly altered microRNAs involved in the carcinogenesis process, ozone in apoptosis, and UV in DNA repair. Accordingly, each tested pollutant induced a specific pattern of microRNA alteration in skin related to the intrinsic mechanisms activated by the specific pollutant. These alterations, over a short time basis, reflect adaptive events aimed at defending the tissue against damages. Conversely, whenever environmental exposure lasts for a long time, the irreversible alteration of the microRNA machinery results in epigenetic damage contributing to the pathogenesis of inflammation, dysplasia, and cancer induced by environmental pollutants.

The lncRNAs at X Chromosome Inactivation Center: Not Just a Matter of Sex Dosage Compensation

Non-coding RNAs (ncRNAs) constitute the majority of the transcriptome, as the result of pervasive transcription of the mammalian genome. Different RNA species, such as lncRNAs, miRNAs, circRNA, mRNAs, engage in regulatory networks based on their reciprocal interactions, often in a competitive manner, in a way denominated “competing endogenous RNA (ceRNA) networks” (“ceRNET”): miRNAs and other ncRNAs modulate each other, since miRNAs can regulate the expression of lncRNAs, which in turn regulate miRNAs, titrating their availability and thus competing with the binding to other RNA targets. The unbalancing of any network component can derail the entire regulatory circuit acting as a driving force for human diseases, thus assigning “new” functions to “old” molecules. This is the case of XIST, the lncRNA characterized in the early 1990s and well known as the essential molecule for X chromosome inactivation in mammalian females, thus preventing an imbalance of X-linked gene expression between females and males. Currently, literature concerning XIST biology is becoming dominated by miRNA associations and they are also gaining prominence for other lncRNAs produced by the X-inactivation center. This review discusses the available literature to explore possible novel functions related to ceRNA activity of lncRNAs produced by the X-inactivation center, beyond their role in dosage compensation, with prospective implications for emerging gender-biased functions and pathological mechanisms.

Long non-coding RNA XIST: a novel oncogene in multiple cancers

Long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) is an important lncRNA derived from the XIST gene in mammals. XIST is abnormally expressed in numerous tumors, in most of which XIST functions as an oncogene. XIST is involved in multiple aspects of carcinogenesis, including tumor onset, progression, and prognosis. In our review, we collected and analyzed the recent studies on the impact of XIST in human tumor development. The multilevel molecular functions of XIST in human tumors are comprehensively reviewed to clarify the pathologic mechanisms and to offer a novel direction for further study.

Long Non-Coding RNAs in Diagnosis, Treatment, Prognosis, and Progression of Glioma: A State-of-the-Art Review

Glioma is the most common malignant central nervous system tumor with significant mortality and morbidity. Despite considerable advances, the exact molecular pathways involved in tumor progression are not fully elucidated, and patients commonly face a poor prognosis. Long non-coding RNAs (lncRNAs) have recently drawn extra attention for their potential roles in different types of cancer as well as non-malignant diseases. More than 200 lncRNAs have been reported to be associated with glioma. We aimed to assess the roles of the most investigated lncRNAs in different stages of tumor progression and the mediating molecular pathways in addition to their clinical applications. lncRNAs are involved in different stages of tumor formation, invasion, and progression, including regulating the cell cycle, apoptosis, autophagy, epithelial-to-mesenchymal transition, tumor stemness, angiogenesis, the integrity of the blood-tumor-brain barrier, tumor metabolism, and immunological responses. The well-known oncogenic lncRNAs, which are upregulated in glioma, are H19, HOTAIR, PVT1, UCA1, XIST, CRNDE, FOXD2-AS1, ANRIL, HOXA11-AS, TP73-AS1, and DANCR. On the other hand, MEG3, GAS5, CCASC2, and TUSC7 are tumor suppressor lncRNAs, which are downregulated. While most studies reported oncogenic effects for MALAT1, TUG1, and NEAT1, there are some controversies regarding these lncRNAs. Expression levels of lncRNAs can be associated with tumor grade, survival, treatment response (chemotherapy drugs or radiotherapy), and overall prognosis. Moreover, circulatory levels of lncRNAs, such as MALAT1, H19, HOTAIR, NEAT1, TUG1, GAS5, LINK-A, and TUSC7, can provide non-invasive diagnostic and prognostic tools. Modulation of expression of lncRNAs using antisense oligonucleotides can lead to novel therapeutics. Notably, a profound understanding of the underlying molecular pathways involved in the function of lncRNAs is required to develop novel therapeutic targets. More investigations with large sample sizes and increased focus on in-vivo models are required to expand our understanding of the potential roles and application of lncRNAs in glioma.

The Roles Played by Long Non-Coding RNAs in Glioma Resistance

Glioma originates in the central nervous system and is classified based on both histological features and molecular genetic characteristics. Long non-coding RNAs (lncRNAs) are longer than 200 nucleotides and are known to regulate tumorigenesis and tumor progression, and even confer therapeutic resistance to glioma cells. Since oncogenic lncRNAs have been frequently upregulated to promote cell proliferation, migration, and invasion in glioma cells, while tumor-suppressive lncRNAs responsible for the inhibition of apoptosis and decrease in therapeutic sensitivity in glioma cells have been generally downregulated, the dysregulation of lncRNAs affects many features of glioma patients, and the expression profiles associated with these lncRNAs are needed to diagnose the disease stage and to determine suitable therapeutic strategies. Accumulating studies show that the orchestrations of oncogenic lncRNAs and tumor-suppressive lncRNAs in glioma cells result in signaling pathways that influence the pathogenesis and progression of glioma. Furthermore, several lncRNAs are related to the regulation of therapeutic sensitivity in existing anticancer therapies, including radiotherapy, chemotherapy and immunotherapy. Consequently, we undertook this review to improve the understanding of signaling pathways influenced by lncRNAs in glioma and how lncRNAs affect therapeutic resistance.

X-Inactive-Specific Transcript: Review of Its Functions in the Carcinogenesis

X-inactive-specific transcript (XIST) is one of the firstly discovered long non-coding RNAs with prominent roles in the process of X inactivation. Moreover, this transcript contributes in the carcinogenic process in different tissues. In addition to interacting with chromatin modifying molecules, XIST can be served as a molecular sponge for miRNAs to modulate expression of miRNA targets. Most of the studies have indicated an oncogenic role for XIST. However, in prostate cancer, a single study has indicated a tumor suppressor role for this lncRNA. Similar result has been reported for XIST in oral squamous cell carcinoma. In hepatocellular carcinoma, breast cancer, ovarian cancer, osteosarcoma, and renal cell carcinoma, different studies have reported inconsistent results. In the present manuscript, we review function of XIST in the carcinogenesis.

Competing Endogenous RNA Networks in Glioma

Gliomas are the most common and malignant primary brain tumors. Various hallmarks of glioma, including sustained proliferation, migration, invasion, heterogeneity, radio- and chemo-resistance, contribute to the dismal prognosis of patients with high-grade glioma. Dysregulation of cancer driver genes is a leading cause for these glioma hallmarks. In recent years, a new mechanism of post-transcriptional gene regulation was proposed, i.e., "competing endogenous RNA (ceRNA)." Long non-coding RNAs, circular RNAs, and transcribed pseudogenes act as ceRNAs to regulate the expression of related genes by sponging the shared microRNAs. Moreover, coding RNA can also exert a regulatory role, independent of its protein coding function, through the ceRNA mechanism. In the latest glioma research, various studies have reported that dysregulation of certain ceRNA regulatory networks (ceRNETs) accounts for the abnormal expression of cancer driver genes and the establishment of glioma hallmarks. These achievements open up new avenues to better understand the hidden aspects of gliomas and provide new biomarkers and potential efficient targets for glioma treatment. In this review, we summarize the existing knowledge about the concept and logic of ceRNET and highlight the emerging roles of some recently found ceRNETs in glioma progression.

Correlation analysis of microribonucleic acid-155 and microribonucleic acid-29 with type 2 diabetes mellitus, and the prediction and verification of target genes

AIMS/INTRODUCTION

Microribonucleic acid-155 (microRNA155) and microRNA29 are reported to inhibit glucose metabolism in some cell and animal models, but no evidence from susceptible populations that examines the relationship between microRNA155 or microRNA29 and type 2 diabetes mellitus currently exists. Furthermore, target genes regulated by microRNA155 and microRNA29 that affect glucose and lipid metabolism remain unknown.

MATERIALS AND METHODS

Human participants were divided into normal weight (n = 72), obesity (n = 120) and type 2 diabetes (n = 59) groups. The contents of microRNA155 and microRNA29 abundance in serum were measured, and candidate genes potentially related to glucose and lipid metabolism targeted by either microRNA155 or microRNA29 were screened. Overexpression of microRNA155 and microRNA29 in HepG2 cells was used to verify candidate gene expression, and measure the effects on glucose and lipid metabolism.

RESULTS

Serum levels of microRNA155 and microRNA29 show a significant increase in individuals with obesity and type 2 diabetes compared with normal weight individuals. Identified target genes for microRNA155 were MAPK14, MAP3K10, DUSP14 and PRKAR2B. Identified target genes for microRNA29 were PEX11A and FADS1. Overexpression of microRNA155 or microRNA29 in HepG2 cells was found to downregulate the expression of identified target genes, and result in inhibition of triglyceride synthesis and glucose incorporation.

CONCLUSIONS

MicroRNA155 and microRNA29 were significantly higher in type 2 diabetes patients compared with the control patients, their levels were also positively correlated with fasting plasma glucose levels, and over-expression of microRNA155 or microRNA29 were found to downregulate glucose and lipid metabolism target genes, and reduce lipid synthesis and glucose incorporation in HepG2 cells.

Silencing long non-coding RNA XIST suppresses drug resistance in acute myeloid leukemia through down-regulation of MYC by elevating microRNA-29a expression

Background

Long non-coding RNAs (lncRNAs) are biomarkers participating in multiple disease development including acute myeloid leukemia (AML). Here, we investigated molecular mechanism of X Inactive-Specific Transcript (XIST) in regulating cellular viability, apoptosis and drug resistance in AML.

Methods

XIST, miR-29a and myelocytomatosis oncogene (MYC) expression in AML bone marrow cells collected from 62 patients was evaluated by RT-qPCR and Western blot analysis. Besides, the relationship among XIST, miR-29a and MYC was analyzed by dual luciferase reporter assay, RIP, and RNA pull down assays. AML KG-1 cells were treated with anti-tumor drug Adriamycin. The role of XIST/miR-29a/MYC in cellular viability, apoptosis and drug resistance in AML was accessed via gain- and loss-of-function approaches. At last, we evaluated role of XIST/miR-29a/MYC on tumorigenesis in vivo.

Results

XIST and MYC were up-regulated, and miR-29a was down-regulated in AML bone marrow cells. Silencing XIST inhibited cellular activity and drug resistance but promoted cellular apoptosis of KG-1 cells by down-regulating MYC. XIST inhibited miR-29a expression to up-regulate MYC. Moreover, silencing XIST inhibited tumorigenesis of AML cells in vivo.

Conclusions

Overall, down-regulation of XIST decreased MYC expression through releasing the inhibition on miR-29a, thereby reducing drug resistance, inhibiting viability and promoting apoptosis of AML cells.

CREB1 Suppresses Transcription of microRNA-186 to Promote Growth, Invasion and Epithelial-Mesenchymal Transition of Gastric Cancer Cells Through the KRT8/HIF-1α Axis

Background

The cAMP response element-binding protein 1 (CREB1) was initiated as a potential target for cancer treatment. This research was conducted to probe the effect of CREB1 in the progression of gastric cancer (GC) and the molecules involved.

Materials and Methods

CREB1 expression in GC tissues and cell lines (AGS and MKN-45) as well as that in normal tissues and in gastric mucosa cell line (GES-1) was detected. The correlation between CREB1 expression and prognosis of GC patients was determined. Artificial silencing of CREB1 was introduced to evaluate its effect on biological behaviors of GC cells. The target microRNA (miRNA) of CREB1 and the target mRNA of miR-186 were predicted and validated. Altered expression of miR-186, KRT8 and HIF-1α was introduced to confirm their functions in GC progression.

Results

CREB1 was abundantly expressed in GC tissues and cells and linked to dismal prognosis in patients. Silencing of CREB1 or upregulation of miR-186 suppressed the malignant behaviors such as growth, epithelial-mesenchymal transition (EMT) and invasion of GC cells, while artificial overexpression of KRT8 led to reversed trends. KRT8 was a target mRNA of miR-186, and CREB1 transcriptionally suppressed miR-186 expression to further up-regulate KRT8. KRT8 was also found to increase HIF-1α expression. Upregulation of HIF-1α was found to block the suppressing role of CREB1 silencing in GC cell malignancy.

Conclusion

This study evidenced that silencing of CREB1 inhibits growth, invasion, EMT and resistance to apoptosis of GC cells involving the upregulation of miR-186 and the following downregulation of KRT8 and HIF-1α.