Long intergenic non-coding RNA 01126 activates IL-6/JAK2/STAT3 pathway to promote periodontitis pathogenesis.

OBJECTIVES: Periodontitis seriously affects oral-related quality of life and overall health. Long intergenic non-coding RNA 01126 (LINC01126) is aberrantly expressed in periodontitis tissues. This study aimed to explore the possible pathogenesis of LINC01126 in periodontitis. METHODS: Inflammatory model of human gingival fibroblasts (HGFs) was established. Cell Counting Kit-8 (CCK-8), wound healing assay, and flow cytometry were utilized to detect biological roles of LINC01126. Binding site of miR-655-3p to LINC01126 and IL-6 was predicted. Then, subcellular localization of LINC01126 and the binding ability of miR-655-3p to LINC01126 and IL-6 in HGFs were verified. Hematoxylin-Eosin (H&E) staining and immunohistochemistry (IHC) staining were utilized to detect tissue morphology and proteins expression of clinical samples. RESULTS: LINC01126 silencing can alleviate cell inflammation induced by lipopolysaccharide derived from Porphyromonas gingivalis, reduce cell apoptosis, and promote cell migration. As a "sponge" for miR-655-3p, LINC01126 inhibits its binding to mRNA of IL-6, thereby promoting inflammation progression and JAK2/STAT3 pathway activation. Quantitative real-time PCR, Western Blot, and IHC results of clinical tissue samples further confirmed that miR-655-3p expression was down-regulated and IL-6/JAK2/STAT3 was abnormally activated in periodontitis tissues. CONCLUSIONS: In summary, serving as an endogenous competitive RNA of miR-655-3p, LINC01126 promotes IL-6/JAK2/STAT3 pathway activation, thereby promoting periodontitis pathogenesis.

Breast cancer cell secretome analysis to decipher miRNA regulating the tumor microenvironment and discover potential biomarkers.

MicroRNA (miRNA/miR) 526 b- and miR655-overexpressed tumor cell-free secretions regulate the breast cancer tumor microenvironment (TME) by promoting tumor-associated angiogenesis, oxidative stress, and hypoxic responses. Additionally, premature miRNA (pri-miR526b and pri-miR655) are established breast cancer blood biomarkers. However, the mechanisms of how these miRNAs regulate the TME has yet to be investigated. Mass spectrometry analysis of miRNA-overexpressed cell lines MCF7-miR526b, MCF7-miR655, and miRNA-low MCF7-Mock cell-free secretomes identified 34 differentially expressed proteins coded by eight genes. In both miRNA-high cell secretomes, four markers are upregulated: YWHAB, SFN, TXNDC12, and MYL6B, and four are downregulated: PEA15, PRDX4, PSMB6, and FN1. All upregulated marker transcripts are significantly high in both total cellular RNA pool and cell-free secretions of miRNA-high cell lines, validated with quantitative RT-PCR. Bioinformatics tools were used to investigate these markers' roles in breast cancer. These markers' top gene ontology functions are related to apoptosis, oxidative stress, membrane transport, and motility supporting oncogenic miR526b- and miR655-induced functions. Gene transcription factor analysis tools were used to show how these miRNAs regulate the expression of each secretory marker. Data extracted from the Human Protein Atlas showed that YWHAB, SFN, and TXNDC12 expression could distinguish early and late-stage breast cancer in various breast cancer subtypes and are associated with poor patient survival. Additionally, immunohistochemistry analysis showed the expression of each marker in breast tumors. A stronger correlation between miRNA clusters and upregulated secretory markers gene expression was found in the luminal A tumor subtype. YWHAB, SFN, and MYL6B are upregulated in breast cancer patient's blood, showing biomarker potential. Of these identified novel miRNA secretory markers, SFN and YWHAB successfully passed all validations and are the best candidates to further investigate their roles in miRNA associated TME regulation. Also, these markers show the potential to serve as blood-based breast cancer biomarkers, especially for luminal-A subtypes.

Human umbilical cord mesenchymal stem cell-derived extracellular vesicles carrying miR-655-3p inhibit the development of esophageal cancer by regulating the expression of HIF-1α via a LMO4/HDAC2-dependent mechanism.

OBJECTIVE: This study clarified the function of human umbilical cord mesenchymal stem cell (hUCMSC)-derived extracellular vesicle (EV)-enclosed miR-655-3p in esophageal squamous cell carcinoma (ESCC). METHODS: A Chi-square test and the Kaplan-Meier estimator were used to analyze the prognosis of ESCC in relation to the expression of miR-655-3p. ESCC cells were incubated with PBS or hUCMSC-derived EVs (hUCMSC-EVs) in the conditions of gene modification, after which the malignant behaviors of ESCC cells were assessed and the molecular interactions were determined. The effect of hUCMSC-derived EV-miR-655-3p was also investigated in a nude mouse model of ESCC. RESULTS: Low expression of miR-655-3p indicated poor prognosis of ESCC. hUCMSC-EVs suppressed the malignant behaviors of ESCC cells and the growth and liver metastasis of transplanted tumors. Inhibition of miR-655-3p in hUCMSCs impaired the therapeutic effect of hUCMSC-EVs. LMO4, targeted by miR-655-3p, activated the transcription of HIF-1α by sequestering HDAC2 from HIF-1α promoter. Knockdown of LMO4 suppressed ESCC cell activities, while overexpression of HIF-1α counteracted the tumor suppressive effect of LMO4 knockdown. CONCLUSION: miR-655-3p enclosed in hUCMSC-derived EVs inhibits ESCC progression partially by inactivating HIF-1α via the LMO4/HDAC2 axis.

LncRNA XIST from the bone marrow mesenchymal stem cell derived exosome promotes osteosarcoma growth and metastasis through miR-655/ACLY signal.

BACKGROUND: Long non-coding RNA X-inactive specific transcript (XIST) regulates the progression of a variety of tumors, including osteosarcoma. Bone marrow mesenchymal stem cells (BMSCs) can be recruited into osteosarcoma tissue and affect the progression by secreting exosomes. However, whether BMSCs derived exosomes transmit XIST to regulate the growth and metastasis of osteosarcoma and the related mechanism are still unclear. METHOD: In this study, BMSCs derived exosomes were used to treat human osteosarcoma cells MG63 and 143B, and the level of XIST in BMSCs was intervened by siRNA. CCK-8, EdU, transwell assays were used to analyze the changes of cell proliferation, migration and invasion. Bioinformatics analysis, RNA pulldown and dual-luciferase reporter gene assays validated the targeted relationship of XIST with miR-655 and the interaction between miR-655 and ACLY 3'-UTR. 143B/LUC cell line was used to establish an animal model of in situ osteosarcoma to verify the found effects of XIST on osteosarcoma. Oil Red O staining, Western blot and so on were used to detect the changes of lipid deposition and protein expression. RESULTS: It was found that BMSCs derived exosomes promoted the proliferation, migration and invasion of osteosarcoma cells, and the down-regulation of XIST inhibited this effect. miR-655 mediated the role of BMSCs derived exosomal XIST in promoting the progression of osteosarcoma and down-regulation of miR-655 could reverse the effects of inhibiting XIST on the proliferation, migration and invasion of osteosarcoma cells. Meanwhile, animal level results confirmed that BMSCs derived exosomal XIST could promote osteosarcoma growth and lung metastasis by combining with miR-655. In-depth mechanism study showed that BMSCs derived exosomal XIST combined with miR-655 to increase the protein level of ACLY, which led to lipid deposition and activate ß-catenin signal to promote the proliferation, migration and invasion of osteosarcoma cells. CONCLUSION: This study showed that BMSCs derived exosomal XIST could enter osteosarcoma cells, bind and down-regulates the level of miR-655, resulting in an increase in the level of ACLY, thus increasing the lipid deposition and the activity of ß-catenin signal to promote the growth and metastasis of osteosarcoma.

CCN2 Facilitates IL-17 Production and Osteoclastogenesis in Human Osteoarthritis Synovial Fibroblasts by Inhibiting miR-655 Expression.

Osteoarthritis (OA) is associated with extensive upregulation of osteoclastogenesis and subsequent bone breakdown. The CCN family protein connective tissue growth factor (CCN2, also called CCN2) enhances inflammatory cytokine production in OA disease. The cytokine interleukin (IL)-17 is known to induce osteoclastogenesis and bone erosion in arthritic disease. Our retrieval of data from the Gene Expression Omnibus (GEO) data set and clinical tissues exhibited higher CCN2 and IL-17 expression in OA synovial sample than in normal healthy samples. We observed the same phenomenon in synovial tissue from rats with anterior cruciate ligament transaction (ACLT)-elicited OA compared with synovial tissue from control healthy rats. We also found that CCN2 facilitated increases in IL-17 synthesis in human OA synovial fibroblasts (OASFs) and promoted osteoclast formation. CCN2 affected IL-17 production by reducing miR-655 expression through the ILK and Syk signaling cascades. Our findings improve our understanding about the effect of CCN2 in OA pathogenesis and, in particular, IL-17 production and osteoclastogenesis, which may help with the design of more effective OA treatments. © 2022 American Society for Bone and Mineral Research (ASBMR).

The biological function of the long non-coding RNA endogenous born avirus-like nucleoprotein in lung adenocarcinoma is mediated through the microRNA-655-3p/B-cell lymphoma-2 axis.

Lung adenocarcinoma (LUAD) is a subtype of lung cancer, and therapy remains a great challenge. A growing body of evidence shows that long-chain non-coding RNAs (lncRNAs) play an important role in the occurrence and development of LUAD. This study investigated the roles and mechanisms of action of EBLN3P in LUAD. The bioinformatics software starBase and TargetScan were used to predict the binding sites of the lncRNA endogenous born avirus-like nucleoprotein (EBLN3P) and microRNA (miR)-655-3p in LUAD. The regulatory role of EBLN3P and miR-655-3p in cell proliferation was verified through the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2 H-tetrazolium bromide (MTT) assay. The binding sites between EBLN3P, miR-655-3p, and B-cell lymphoma-2 (Bcl-2) were assessed using dual-luciferase reporter assay, western blotting, and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Flow cytometry (FCM) was performed to analyze the apoptotic rates of A549 cells after transfection. The results revealed that EBLN3P was upregulated, whereas miR-655-3p was downregulated in LUAD cell lines (A549 and NCI-H23). Bioinformatics analysis and dual-luciferase reporter assays indicated that EBLN3P interacted with miR-655-3p. Knockdown of EBLN3P notably inhibited the bioactivity and induced apoptosis in A549 cells by upregulating miR-655-3p. Mechanistically, miR-655-3p inhibits cell viability and induces apoptosis by inhibiting Bcl-2 expression. The high expression of Bcl-2 reversed the impact of miR-655-3p on the inhibition of cell bioactivity and induction of apoptosis in A549 cells. In conclusion, this study demonstrated that EBLN3P silencing inhibits bioactivity and induces apoptosis via the miR-655-3p/Bcl-2 axis, providing a potential therapeutic target for lung adenocarcinoma.

Long noncoding RNA endogenous bornavirus-like nucleoprotein acts as an oncogene by regulating microRNA-655-3p expression in T-cell acute lymphoblastic leukemia.

Acute lymphocytic leukemia (ALL) is the most common malignant tumor in children with T-cell ALL (T-ALL), accounting for approximately 15% of all cases. Long noncoding RNAs (lncRNAs) are involved in the pathogenesis and progression of T-ALL. The present study aimed to explore the role and mechanism of action of lncRNA EBLN3P in T-ALL. We used quantitative reverse transcription-PCR (qRT-PCR) to determine the expression of lncRNA endogenous bornavirus-like nucleoprotein (EBLN3P), microRNA (miR)-655-3p, and the transcription level of matrix metalloproteinase-9 (MMP-9), and Western blot assay to quantify the protein expression level of cleaved-caspase3, caspase3, proliferating cell nuclear antigen (PCNA), and MMP-9. The potential binding sites between lncRNA EBLN3P and miR-655-3p were predicted using StarBase, and the interaction was further verified by dual-luciferase reporter assay and RNA pull-down assay. The proliferation ability of Jurkat cells was detected using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and their invasion and migration ability using transwell assay. Cell apoptosis was determined using flow cytometry (FCM) assay. The expression of lncRNA EBLN3P was upregulated while that of miR-655-3p was downregulated in human T-ALL cell lines and lncRNA EBLN3P negatively regulated miR-655-3p. LncRNA EBLN3P knockdown significantly inhibited proliferation, invasion, and migration of Jurkat cells and induced their apoptosis. Downregulating miR-655-3p reversed the effects of lncRNA EBLN3P knockdown on Jurkat cells. In conclusion, we confirmed for the first time that lncRNA EBLN3P is dysregulated in T-ALL cell lines, and lncRNA EBLN3P knockdown inhibited the malignant biological behaviors of T-ALL cells by up-regulating miR-655-3p.

circRNA circMED27 acts as a prognostic factor and mediator to promote lenvatinib resistance of hepatocellular carcinoma.

Circular RNAs (circRNAs) have been proven to play key roles in the development and progression of various types of cancers. However, there were no reported studies on the roles of circRNA mediator complex subunit 27 (circMED27) in tumors including hepatocellular carcinoma (HCC). In this study, we found that circMED27 was significantly increased in HCC serum and that higher levels of circMED27 were correlated with bad clinical characteristics and poor prognoses of patients with HCC. Furthermore, upregulated circMED27 promoted HCC resistance to lenvatinib. Our mechanistic investigations revealed that circMED27 functions as a competing endogenous RNA (ceRNA) for miR-655-3p to upregulate ubiquitin-specific peptidase 28 (USP28) expression. Thus, we are led to conclude that circMED27 acts as a potential therapeutic target for HCC patients receiving lenvatinib therapy and may represent a promising molecular biomarker for forecasting lenvatinib-resistant HCC.

Circular RNA circ_0001955 promotes hepatocellular carcinoma tumorigenesis by up-regulating alkaline ceramidase 3 expression through microRNA-655-3p.

The involvement of certain circular RNAs (circRNAs) in the development of hepatocellular carcinoma (HCC) has been reported. Herein, this study aimed to investigate the function and mechanism of circ_0001955 in HCC tumorigenesis. Expression of circ_0001955, miR-655-3p, and alkaline ceramidase 3 (ACER3) was evaluated by quantitative real-time PCR and Western blot. Cell counting kit-8, colony formation, transwell, tube formation, flow cytometry and tumor xenograft assays were adopted to perform in vitro and in vivo experiments. The direct interaction between miR-655-3p and circ_0001955 or ACER3 was verified using dual-luciferase reporter and RNA immunoprecipitation assays. Circ_0001955 was highly expression in HCC tissues and cells. Functionally, circ_0001955 deletion suppressed HCC tumorigenesis in vitro by suppressing cell growth, metastasis and angiogenesis. Mechanistically, circ_0001955 could competitively sponge miR-655-3p, which targeted ACER3. Besides that, miR-655-3p silencing abolished the anticancer action of circ_0001955 silencing on HCC cells. Moreover, miR-655-3p overexpression inhibited HCC cell oncogenic phenotypes mentioned above, which were attenuated by ACER3 up-regulation. Additionally, circ_0001955 knockdown also impeded HCC growth in a mouse model. In all, this study suggested a novel circ_0001955/miR-655-3p/ACER3 pathway in HCC progression.

lncRNA MALAT1 regulated ATAD2 to facilitate retinoblastoma progression via miR-655-3p.

Long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) was reported as an oncogene in many tumors including retinoblastoma (RB). This research mainly focused on the functions and mechanism of MALAT1 in RB. MALAT1 was upregulated in RB tissues and cells, and it served as a competing endogenous RNA (ceRNA) and inhibited miRNA-655-3p (miR-655-3p) expression, which eventually regulated the expression of miR-655-3p downstream target ATPase Family AAA Domain Containing 2 (ATAD2). The level of ATAD2 significantly increased, while that of miR-655-3p remarkably decreased in RB tissues and cells. MALAT1 depletion inhibited cell proliferation, metastasis, and epithelial-mesenchymal transition (EMT), but promoted apoptosis in vitro and blocked xenograft tumor growth in vivo. MALAT1 exerted its oncogenic functions in RB by regulating miR-655-3p/ATAD2 axis.

The VIM-AS1/miR-655/ZEB1 axis modulates bladder cancer cell metastasis by regulating epithelial-mesenchymal transition.

BACKGROUND: Invasive bladder tumors cause a worse prognosis in patients and remain a clinical challenge. Epithelial-mesenchymal transition (EMT) is associated with bladder cancer metastasis. In the present research, we attempted to demonstrate a novel mechanism by which a long noncoding RNA (lncRNA)-miRNA-mRNA axis regulates EMT and metastasis in bladder cancer. METHODS: Immunofluorescence (IF) staining was used to detect Vimentin expression. The protein expression of ZEB1, Vimentin, E-cadherin, and Snail was investigated by using immunoblotting assays. Transwell assays were performed to detect the invasive capacity of bladder cancer cells. A wound healing assay was used to measure the migratory capacity of bladder cancer cells. RESULTS: Herein, we identified lncRNA VIM-AS1 as a highly- expressed lncRNA in bladder cancer, especially in metastatic bladder cancer tissues and high-metastatic bladder cancer cell lines. By acting as a ceRNA for miR-655, VIM-AS1 competed with ZEB1 for miR-655 binding, therefore eliminating the miR-655-mediated suppression of ZEB1, finally promoting EMT in both high- and low-metastatic bladder cancer cells and enhancing cancer cell metastasis. CONCLUSIONS: In conclusion, the VIM-AS1/miR-655/ZEB1 axis might be a promising target for improving bladder cancer metastasis via an EMT-related mechanism.

Linc00963 Promote Cell Proliferation and Tumor Growth in Castration-Resistant Prostate Cancer by Modulating miR-655/TRIM24 Axis.

Previous studies have shown that both long intergenic non-coding RNA 00963 (Linc00963) and tripartite motif containing 24 (TRIM24) are activators of the PI3K/AKT pathway, and both are involved in the carcinogenesis and progression of prostate cancer. However, the regulatory mechanisms between Linc00963 and TRIM24 are still unclear. In this study, we aimed to elucidate the underlying relationship between Linc00963 and TRIM24 in castration-resistant prostate cancer (CRPC). We found that TRIM24, an established oncogene in CRPC, was positively correlated with Linc00963 in prostate cancer tissues. In addition, TRIM24 was positively regulated by Lin00963 in CRPC cells. Mechanistically, TRIM24 was the direct target of microRNA-655 (miR-655) in CRPC cells, and Linc00963 could competitively bind miR-655 and upregulate TRIM24 expression. Using gain- and loss-of- function assays and rescue assays, we identified that miR-655 inhibits TRIM24 expression and cell proliferation and colony forming ability in CRPC, and that Linc00963 promotes TRIM24 expression, cell proliferation, and colony forming ability of CRPC cells by directly suppressing miR-655 expression. We further identified that Linc00963 could promote tumor growth of CRPC cells by inhibiting miR-655 and upregulating TRIM24 axis in vivo. Taken together, our study reveals a new mechanism for the Linc00963/miR-655/TRIM24 competing endogenous RNA (ceRNA) network in accelerating cell proliferation in CRPC in vitro and in vivo, and suggests that Linc00963 could be considered a novel therapeutic target for CRPC.

lncRNA SNHG5 promotes cell proliferation, migration and invasion in oral squamous cell carcinoma by sponging miR-655-3p/FZD4 axis.

Recently, previous studies have shown that long non-coding RNA (lncRNA) can act as a tumor promoter or inhibitor in the pathogenesis of oral squamous cell carcinoma (OSCC). However, the regulatory mechanism of lncRNA SNHG5 is unknown in OSCC. Therefore, the functional mechanism of lncRNA SNHG5 in OSCC was initially revealed in this study. Here, RT-qPCR and western blot analysis were used to assess mRNA and protein expression. The functional mechanism of SNHG5 was investigated by MTT, Transwell and luciferase reporter assays. The results showed that SNHG5 expression was upregulated in OSCC and promoted the viability, migration and invasion of OSCC cells. In addition, SNHG5 is the sponge of miR-655-3p in OSCC. And miR-655-3p was found to play an inhibitory effect in OSCC by interacting with SNHG5. Moreover, miR-655-3p directly targets FZD4 and negatively regulates its expression in OSCC. Functionally, FZD4 promoted the progression of OSCC by interacting with the SNHG5/miR-655-3p axis. In conclusion, lncRNA SNHG5 promotes cell proliferation, migration and invasion in OSCC by regulating miR-655-3p/FZD4 axis.

LncRNA NFIA-AS2 promotes glioma progression through modulating the miR-655-3p/ZFX axis.

Long non-coding RNAs (lncRNAs) are closely associated with tumorigenesis of various malignancies, including glioma. However, the roles of most lncRNAs in glioma remain undiscovered. The present study for the first time explored the roles of NFIA-AS2 in glioma. Based on informatic analyses by online database, lncRNA NFIA-AS2 in glioma tissues was overexpressed and further confirmed in glioma tissues and cells by quantitative real-time PCR (qRT-PCR). High expression of NFIA-AS2 was closely correlated with poor prognosis and might be an independent prognostic factor for PFS and OS. Functionally, silenced NFIA-AS2 could remarkably hinder glioma cell proliferation, migration and invasion, and cause the apoptosis. Mechanistic investigation disclosed that NFIA-AS2 interacted with miR-655-3p and inversely connected with miR-655-3p in glioma. Additionally, miR-655-3p was proved to regulate the expression of ZFX. Final rescue assay demonstrated that ZFX overexpression or miR-655-3p downregulation could neutralize the suppressive effects of NFIA-AS2 knockdown on glioma progression. In conclusion, this study firstly reported that NFIA-AS2 could promote the progression of glioma by targeting the miR-665-3p/ZFX axis, which highlighted that NFIA-AS2 could be a novel biomarker and therapeutic target for glioma patients.

Chemically Induced Hypoxia Enhances miRNA Functions in Breast Cancer.

In aggressively growing tumors, hypoxia induces HIF-1α expression promoting angiogenesis. Previously, we have shown that overexpression of oncogenic microRNAs (miRNAs, miRs) miR526b/miR655 in poorly metastatic breast cancer cell lines promotes aggressive cancer phenotypes in vitro and in vivo. Additionally, miR526b/miR655 expression is significantly higher in human breast tumors, and high miR526b/miR655 expression is associated with poor prognosis. However, the roles of miR526b/miR655 in hypoxia are unknown. To test the relationship between miR526b/miR655 and hypoxia, we used various in vitro, in silico, and in situ assays. In normoxia, miRNA-high aggressive breast cancer cell lines show higher HIF-1α expression than miRNA-low poorly metastatic breast cancer cell lines. To test direct involvement of miR526b/miR655 in hypoxia, we analyzed miRNA-high cell lines (MCF7-miR526b, MCF7-miR655, MCF7-COX2, and SKBR3-miR526b) compared to controls (MCF7 and SKBR3). CoCl2-induced hypoxia in breast cancer further promotes HIF-1α mRNA and protein expression while reducing VHL expression (a negative HIF-1α regulator), especially in miRNA-high cell lines. Hypoxia enhances oxidative stress, epithelial to mesenchymal transition, cell migration, and vascular mimicry more prominently in MCF7-miR526b/MCF7-miR655 cell lines compared to MCF7 cells. Hypoxia promotes inflammatory and angiogenesis marker (COX-2, EP4, NFκB1, VEGFA) expression in all miRNA-high cells. Hypoxia upregulates miR526b/miR655 expression in MCF7 cells, thus observed enhancement of hypoxia-induced functions in MCF7 could be attributed to miR526b/miR655 upregulation. In silico bioinformatics analysis shows miR526b/miR655 regulate PTEN (a negative regulator of HIF-1α) and NFκB1 (positive regulator of COX-2 and EP4) expression by downregulation of transcription factors NR2C2, SALL4, and ZNF207. Hypoxia-enhanced functions in miRNA-high cells are inhibited by COX-2 inhibitor (Celecoxib), EP4 antagonist (ONO-AE3-208), and irreversible PI3K/Akt inhibitor (Wortmannin). This establishes that hypoxia enhances miRNA functions following the COX-2/EP4/PI3K/Akt pathways and this pathway can serve as a therapeutic target to abrogate hypoxia and miRNA induced functions in breast cancer. In situ, HIF-1α expression is significantly higher in human breast tumors (n = 96) compared to non-cancerous control tissues (n = 20) and is positively correlated with miR526b/miR655 expression. In stratified tumor samples, HIF-1α expression was significantly higher in ER-positive, PR-positive, and HER2-negative breast tumors. Data extracted from the TCGA database also show a strong correlation between HIF-1α and miRNA-cluster expression in breast tumors. This study, for the first time, establishes the dynamic roles of miR526b/miR655 in hypoxia.

Long noncoding RNA LINC01194 enhances the malignancy of laryngeal squamous cell carcinoma by sponging miR-655 to increase SOX18 expression.

Long noncoding RNAs (lncRNAs) have undergone a comprehensive study for their involvements in tumor treatments. The purpose of our study was to explore the biological effects and regulatory mechanisms of lncRNA LINC01194 (LINC01194) in laryngeal squamous cell carcinoma (LSCC). The levels of LINC01194 in 105 LSCC patients were detected by RT-qPCR. The diagnostic and prognostic value of LINC01194 in LSCC patients were statistically analyzed. The potential functions of LINC01194 in proliferation, apoptosis, and metastasis of LSCC cells were evaluated. The interaction among LINC01194, miR-655 and SOX18 was explored by bioinformatics analysis, luciferase reporter assays and biotinylated RNA pull-down. We found that the expression levels of LINC01194 were highly expressed in LSCC, which was negatively correlated with the clinical outcome of LSCC patients. The area under the ROC curve for LINC01194 was up to 0.8388. Functional assays indicated that LINC01194 knockdown distinctly inhibited LSCC cells proliferation, induced apoptosis, and also attenuated LSCC cells migration and invasion in vitro. Furthermore, we elucidated that LINC01194 promoted SOX18 expression in LSCC cells via functioning as a molecular sponge for miR-655. Overall, based on our findings, LINC01194 served as a tumor promoter and potentially represents a novel prognostic indicator and therapeutic target in LSCC.

miR-655: A promising regulator with therapeutic potential.

miR-655 is a widely studied non-coding small RNA molecule. miR-655 is down-regulated in at least 15 cancers and up-regulated in acute myeloid leukemia (AML) and breast cancer (BC) cell lines. The expression level of miR-655 is closely related to the prognosis of cancer patients. In addition, we summarize all genes that can be down-regulated by miR-655 in cancer. In breast cancer, we also found the upstream regulatory pathway of miR-655. Here, we systematically analyze biological pathways and molecular functions of the miR-655-related genes. Our results indicate that miR-655-related genes are involved in cancer cell proliferation, migration, invasion, and apoptosis, and various biological processes such as angiogenesis, EMT, and oxidative stress. miR-655 may also affect the efficacy of many drugs through its targeted genes. This review summarizes the related research of miR-655 in various diseases and evaluates its potential application as a molecular marker for diagnosis and prognosis.

MiR-655-3p inhibits the progression of osteoporosis by targeting LSD1 and activating BMP-2/Smad signaling pathway.

Osteoporosis (OP) is one of the most common chronic metabolic bone diseases in the seniors and postmenopausal women. Plenty of microRNAs (miRNAs) have been confirmed to be involved in OP progression. However, the role of miR-655-3p in osteogenic differentiation and bone formation was still unclear. In this study, we aimed to investigate the cellular function of miR-655-3p and its underlying mechanism in OP. We found that miR-655-3p expression was downregulated in both ovariectomized (OVX) mice bone tissues and MC3T3-E1 cells treated with simulated microgravity (MG). MiR-655-3p overexpression facilitated cell differentiation but suppressed cell apoptosis of MC3T3-E1 cells induced by simulated MG. Mechanistically, we confirmed that lysine-specific histone demethylase 1 (LSD1) is a downstream target gene of miR-655-3p. Furthermore, overexpression of miR-655-3p activated the bone morphogenetic protein 2 (BMP-2)/decapentaplegic homolog (Smad) signaling pathway by suppressing LSD1 expression. Moreover, LSD1 knockdown accelerated osteogenic differentiation and inhibited apoptosis in MC3T3-E1 cells under simulated MG. Additionally, the OVX mouse model was established to investigate the role of miR-655-3p/LSD1 axis in vivo. The results demonstrated that LSD1 could reverse the effects triggered by the injection of adeno-associated virus-miR-655-3p on OP development. Further investigations revealed that miR-655-3p boosted osteogenic differentiation through LSD1/BMP-2/Smad signaling pathway. In summary, these findings implied a potential value of miR-655-3p in OP therapy.

MicroRNA-212 targets SIRT2 to influence lipogenesis in bovine mammary epithelial cell line.

In this research paper we filter and verify miRNAs which may target silent information regulator homolog 2 (SIRT2) gene and then describe the mechanism whereby miRNA-212 might regulate lipogenic genes in mammary epithelial cell lines via targeting SIRT2. Bioinformatics analysis revealed that the bovine SIRT2 gene is regulated by three miRNAs: miR-212, miR-375 and miR-655. The three miRNAs were verified and screened by qRT-PCR, western blot, and luciferase multiplex verification techniques and only miR-212 was shown to have a targeting relationship with SIRT2. The results of co-transfecting miR-212 and silencing RNA (siRNA) showed that by targeting SIRT2, miR-212 can regulate the expression of fatty acid synthetase (FASN) and sterol regulatory element binding factor 1 (SREBP1) but not peroxisome proliferator-activated receptor gamma (PPARγ). Measurement of triglyceride (TAG) content showed that miR-212 increased the fat content of mammary epithelial cell lines. The study indicates that miR-212 could target and inhibit the expression of the SIRT2 gene to promote lipogenesis in mammary epithelial cell lines.

miR526b and miR655 Induce Oxidative Stress in Breast Cancer.

In eukaryotes, overproduction of reactive oxygen species (ROS) causes oxidative stress, which contributes to chronic inflammation and cancer. MicroRNAs (miRNAs) are small, endogenously produced RNAs that play a major role in cancer progression. We established that overexpression of miR526b/miR655 promotes aggressive breast cancer phenotypes. Here, we investigated the roles of miR526b/miR655 in oxidative stress in breast cancer using in vitro and in silico assays. miRNA-overexpression in MCF7 cells directly enhances ROS and superoxide (SO) production, detected with fluorescence assays. We found that cell-free conditioned media contain extracellular miR526b/miR655 and treatment with these miRNA-conditioned media causes overproduction of ROS/SO in MCF7 and primary cells (HUVECs). Thioredoxin Reductase 1 (TXNRD1) is an oxidoreductase that maintains ROS/SO concentration. Overexpression of TXNRD1 is associated with breast cancer progression. We observed that miR526b/miR655 overexpression upregulates TXNRD1 expression in MCF7 cells, and treatment with miRNA-conditioned media upregulates TXNRD1 in both MCF7 and HUVECs. Bioinformatic analysis identifies two negative regulators of TXNRD1, TCF21 and PBRM1, as direct targets of miR526b/miR655. We validated that TCF21 and PBRM1 were significantly downregulated with miRNA upregulation, establishing a link between miR526b/miR655 and TXNRD1. Finally, treatments with oxidative stress inducers such as H2O2 or miRNA-conditioned media showed an upregulation of miR526b/miR655 expression in MCF7 cells, indicating that oxidative stress also induces miRNA overexpression. This study establishes the dynamic functions of miR526b/miR655 in oxidative stress induction in breast cancer.