Long non-coding RNA Linc00662 promotes cell invasion and contributes to cancer stem cell-like phenotypes in lung cancer cells

Association between lncRNAs with stem cells in cancer; a particular focus on lncRNA-CSCs axis in cancer immunopathogenesis

A unique population of cells known as cancer stem cells (CSCs) is essential to developing and spreading cancer. Cancer initiation, maintenance, and progression are all believed to be significantly impacted by the distinct characteristics these cells exhibit regarding self-renewal, proliferation, and differentiation. Transcriptional, post-transcriptional, and translational processes are the only steps of gene expression that lncRNAs can affect. As a result, these proteins participate in numerous biological processes, including the repair of DNA damage, inflammatory reactions, metabolic control, the survival of cells, intercellular communication, and the development and specialization of cells. Studies have indicated that lncRNAs are important for controlling the increase in the subset of CSCs contributing to cancer development. The knowledge that is currently available about lncRNAs and their critical role in maintaining the biological properties of CSCs is highlighted in this study.

LINC00662 Promotes Aggressive Traits by Modulating OCT4 Expression through miR-335-5p in Gallbladder Cancer Cells

Long non-coding RNAs (lncRNAs) are nucleotide sequences that participate in different biological processes and are associated with different pathologies, including cancer. Long intergenic non-protein-coding RNA 662 (LINC00662) has been reported to be involved in different cancers, including colorectal, prostate, and breast cancer. However, its role in gallbladder cancer has not yet been described. In this article, we hypothesize that LINC00662 has an important role in the acquisition of aggressiveness traits such as a stem-like phenotype, invasion, and chemoresistance in gallbladder cancer. Here, we show that LINC00662 is associated with larger tumor size and lymph node metastasis in patients with gallbladder cancer. Furthermore, we show that the overexpression of LINC00662 promotes an increase in CD133+/CD44+ cell populations and the expression of stemness-associated genes. LINC00662 promotes greater invasive capacity and the expression of genes associated with epithelial-mesenchymal transition. In addition, the expression of LINC00662 promotes resistance to cisplatin and 5-fluorouracil, associated with increased expression of chemoresistance-related ATP-binding cassette (ABC) transporters in gallbladder cancer (GBC) cell lines. Finally, we show that the mechanism by which LINC00662 exerts its function is through a decrease in microRNA 335-5p (miR-335-5p) and an increase in octamer-binding transcription factor 4 (OCT4) in GBC cells. Thus, our data allow us to propose LINC00662 as a biomarker of poor prognosis and a potential therapeutic target for patients with GBC.

RNA epigenetics in pulmonary diseases: Insights into methylation modification of lncRNAs in lung cancer

Long non-coding RNAs (lncRNAs) are pivotal controllers of gene expression through epigenetic mechanisms, Methylation, a prominent area of study in epigenetics, significantly impacts cellular processes. Various RNA base methylations, including m6A, m5C, m1A, and 2'-O-methylation, profoundly influence lncRNA folding, interactions, and stability, thereby shaping their functionality. LncRNAs and methylation significantly contribute to tumor development, especially in lung cancer. Their roles encompass cell differentiation, proliferation, the generation of cancer stem cells, and modulation of immune responses. Recent studies have suggested that dysregulation of lncRNA methylation can contribute to lung cancer development. Furthermore, methylation modifications of lncRNAs hold potential for clinical application in lung cancer. Dysregulated lncRNA methylation can promote lung cancer progression and may offer insights into potential biomarker or therapeutic target. This review summarizes the current knowledge of lncRNA methylation in lung cancer and its implications for RNA epigenetics and pulmonary diseases.

Long non-coding RNAs in cancer: multifaceted roles and potential targets for immunotherapy

Cancer remains a major global health concern with high mortality rates mainly due to late diagnosis and poor prognosis. Long non-coding RNAs (lncRNAs) are emerging as key regulators of gene expression in human cancer, functioning through various mechanisms including as competing endogenous RNAs (ceRNAs) and indirectly regulating miRNA expression. LncRNAs have been found to have both oncogenic and tumor-suppressive roles in cancer, with the former promoting cancer cell proliferation, migration, invasion, and poor prognosis. Recent research has shown that lncRNAs are expressed in various immune cells and are involved in cancer cell immune escape and the modulation of the tumor microenvironment, thus highlighting their potential as targets for cancer immunotherapy. Targeting lncRNAs in cancer or immune cells could enhance the anti-tumor immune response and improve cancer immunotherapy outcomes. However, further research is required to fully understand the functional roles of lncRNAs in cancer and the immune system and their potential as targets for cancer immunotherapy. This review offers a comprehensive examination of the multifaceted roles of lncRNAs in human cancers, with a focus on their potential as targets for cancer immunotherapy. By exploring the intricate mechanisms underlying lncRNA-mediated regulation of cancer cell proliferation, invasion, and immune evasion, we provide insights into the diverse therapeutic applications of these molecules.

A pan-cancer analysis of the prognostic value of long non-coding RNA LINC00662 in human cancers

Background: Numerous studies have revealed that the long non-coding RNA LINC00662 is irregularly expressed in various cancers, as well as is correlated with cancer development and progression. Nevertheless, the clinical value of LINC00662 remains controversial. Hence, we explored the correlation of LINC00662 with cancer prognosis through meta-analysis and bioinformatics analysis. Methods: From the beginning through 12 March 2022, we searched for correlational studies on Web of Science, Embase, PubMed and The Cochrane Library. We used pooled hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) to determine the significance of studies on survival outcomes and clinicopathological aspects in human cancers. Additionally, the Gene Expression Profiling Interactive Analysis (GEPIA) database was employed to confirm our findings. Results: Our meta-analysis of 14 studies comprising a total of 960 cancer patients revealed that LINC00662 overexpression was correlated with poor overall survival (HR = 1.91, 95% CI 1.49-2.45, p < 0.001) in cancer patients and relapse-free survival (HR = 2.12, 95% CI 1.19-3.76, p = 0.010) in hepatocellular carcinoma patients. The correlation between LINC00662 and OS was further supported by the results of subgroup analyses according to cancer type, follow-up time, HR availability, and NOS score. In addition, LINC00662 overexpression predicted advanced tumor stage (OR = 4.23, 95% CI 2.50-7.17, p < 0.001), larger tumor size (OR = 1.49, 95% CI 1.11-1.99, p = 0.008), earlier lymph node metastasis (OR = 2.40, 95% CI 1.25-4.59, p = 0.008), and earlier distant metastasis (OR = 4.78, 95% CI 2.57-8.88, p < 0.001). However, there were no statistically significant differences in age (OR = 1.16, 95% CI 0.90-1.51, p = 0.246), gender (OR = 1.10, 95% CI 0.79-1.53, p = 0.578), or differentiation grade (OR = 1.53, 95% CI 0.71-3.33, p = 0.280). Conclusion: LINC00662 expression upregulation is associated with poor prognosis and advanced clinicopathological features in patients with multiple tumors. LINC00662 may serve as a biomarker for the diagnosis and treatment of patients with tumors.

LINC00662 enhances cell progression and stemness in breast cancer by MiR-144-3p/SOX2 axis

BACKGROUND

Breast cancer (BC) is one of the most prevalent malignancies among women globally. Emerging evidence indicates that long non-coding RNAs (lncRNAs) are associated with BC carcinogenesis. In the current study, we explored the mechanism by which LINC00662 regulates BC.

METHODS

Quantitative real-time PCR (qRT-PCR) assessed RNA expressions while western blot for protein levels. Kaplan Meier analysis evaluated overall survival (OS). Cytoplasmic/nuclear fractionation, RNA binding protein immunoprecipitation (RIP) and luciferase reporter assays probed into the underlying molecular mechanism of LINC00662 in BC. Xenograft model was established to explore the influence of LINC00662 on BC progression in vivo. R square graphs were utilized to represent RNA relationships.

RESULTS

LINC00662 is overtly overexpressed in BC tissues and cell lines. LINC00662 knockdown hampers cell proliferation, migration, invasion and stemness. LINC00662 expression is negatively correlated with OS of BC patients. LINC00662 up-regulates SOX2 expression by competitively binding to miR-144-3p, thereby modulating BC cell progression. Xenograft experiments verified that LINC00662 promotes BC tumor growth and cell stemness in vivo.

CONCLUSION

LINC00662 enhances cell proliferation, migration, invasion and stemness in BC by targeting miR-144-3p/SOX2 axis. The findings in the present study suggested that LINC00662 could be a potential therapeutic target for BC treatment.

LINC00662 Promotes Proliferation and Invasion and Inhibits Apoptosis of Glioma Cells Through miR-483-3p/SOX3 Axis

LINC00662 plays a prominent role in the carcinogenesis and progression of diverse cancers. However, its biological functions in glioma are still unclear. LINC00662 expression in glioma tissue samples and cell lines was examined by quantitative real-time polymerase chain reaction. The correlation between LINC00662 expression and the clinical characteristics of 50 patients with glioma was analyzed. LINC00662 knockdown and overexpression cell lines were constructed, and the effects of LINC00662 on the proliferation, invasion, and apoptosis of glioma cells were evaluated by cell counting kit-8, 5-ethynyl-2'-deoxyuridine, Transwell, and flow cytometry assays, respectively. Besides, the relationships among LINC00662, miR-483-3p, and sex-determining region Y-box 3 (SOX3) were assessed by dual-luciferase reporter assay and RNA immunoprecipitation assay. Western blot was used to detect the regulatory effects of LINC00662 and miR-483-3p on SOX3 expression in glioma cells. LINC00662 expression level was elevated in glioma tissues and cell lines compared to that in normal tissues and cell lines. LINC00662 high expression was associated with the adverse prognosis of patients with glioma. Knockdown of LINC00662 repressed the proliferation and invasion of glioma cells, and promoted apoptosis. Additionally, it was revealed that LINC00662 acted as the molecular sponge of miR-483-3p, and SOX3 was verified as a direct target of miR-483-3p. The inhibition of miR-483-3p expression and SOX3 overexpression reversed the biological effects of LINC00662 knockdown on glioma cells. This study reports the key regulatory role of LINC00662/miR-483-3p/SOX3 axis in the tumorigenesis and progression of glioma, bringing novel insights into the underlying mechanisms of glioma.

Knockdown of lncRNA LINC00662 suppresses malignant behaviour of osteosarcoma cells via competition with miR-30b-3p to regulate ELK1 expression

Purpose

Osteosarcoma is a type of bone malignancy that mainly occurred in teenagers. This investigation is aimed to clarify the effect of long non-coding RNA (lncRNA) LINC00662 on the proliferation, migration, and invasion in osteosarcoma and explore the underlying action mechanisms.

Methods

The mRNA expression of LINC00662 was determined by real-time quantitative polymerase chain reaction. Cell proliferation, migration, and invasion were evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, wound healing, and transwell assays, respectively. A dual-luciferase reporter assay was used to validate the target relationships Between microRNA (miR)-30b-3p and LINC00662/ ETS domain-containing protein 1 (ELK1). Western blotting was performed to determine the protein expression of ELK1. Xenograft model was established to evaluate the effects of LINC00662 silencing on tumor growth in vivo.

Results

LncRNA LINC00662 and ELK1 were significantly increased, while miR-30b-3p was reduced in osteosarcoma tissues. The results of functional experiments indicated that transfection of small hairpin (sh)-LINC00662 and miR-30b-3p mimics repressed the migration, invasion, and proliferation of osteosarcoma cells. LncRNA LINC00662 also appeared to sponge miR-30b-3p in order to affect the expression of ELK1. Simultaneously, there were weak negative correlations between the expression of miR-30b-3p and LINC00662/ELK1 in osteosarcoma tissues. Rescue experiments suggested that ELK1 overexpression and downregulation of miR-30b-3p reversed the suppressive effects of sh-LINC00662 on the cell migration, invasion, and proliferation in osteosarcoma.

Conclusions

The current study indicated that knockdown of LINC00662 repressed cell migration, invasion, and proliferation through sponging miR-30b-3p to regulate the expression of ELK1 in osteosarcoma. These results may uncover a promising target for the treatment of osteosarcoma.

LINC00665 up-regulates SIN3A expression to modulate the progression of colorectal cancer via sponging miR-138-5p

Background

Colorectal cancer (CRC) is a malignant tumor affecting people worldwide. Long noncoding RNAs (lncRNAs) is a crucial factor modulating various cancer progression, including CRC. Long intergenic non-protein coding RNA 665 (LINC00665) has been proven as an oncogene in several cancers, but its function in CRC is still unclear.

Methods

QRT-PCR was performed for RNA quantification. Functional assays were designed and carried to test cell phenotype while mechanism experiments were adopted for detecting the interaction of LINC00665, microRNA-138-5p (miR-138-5p) and SIN3 transcription regulator family member A (SIN3A). In vivo experiments were conducted to test LINC00665 function on modulating CRC tumor progression.

Results

LINC00665 displayed high expression in CRC tissues and cells, and promoted tumor progression in vivo. MiR-138-5p displayed abnormally low expression in CRC, and was verified to be sponged by LINC00665. Furthermore, SIN3A, as the downstream mRNA of miR-138-5p, exerted promoting impacts on CRC cells. Rescue experiments certified that overexpressed SIN3A or silenced miR-138-5p could offset the repressed function of LINC00665 knockdown on CRC progression.

Conclusions

LINC00665 could sponge miR-138-5p to up-regulate SIN3A expression, thus accelerating CRC progression.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02176-4.

Identification of Circulating lncRNAs Associated with Gallbladder Cancer Risk by Tissue-Based Preselection, Cis-eQTL Validation, and Analysis of Association with Genotype-Based Expression

Long noncoding RNAs (lncRNAs) play key roles in cell processes and are good candidates for cancer risk prediction. Few studies have investigated the association between individual genotypes and lncRNA expression. Here we integrate three separate datasets with information on lncRNA expression only, both lncRNA expression and genotype, and genotype information only to identify circulating lncRNAs associated with the risk of gallbladder cancer (GBC) using robust linear and logistic regression techniques. In the first dataset, we preselect lncRNAs based on expression changes along the sequence "gallstones → dysplasia → GBC". In the second dataset, we validate associations between genetic variants and serum expression levels of the preselected lncRNAs (cis-lncRNA-eQTLs) and build lncRNA expression prediction models. In the third dataset, we predict serum lncRNA expression based on individual genotypes and assess the association between genotype-based expression and GBC risk. AC084082.3 and LINC00662 showed increasing expression levels (p-value = 0.009), while C22orf34 expression decreased in the sequence from gallstones to GBC (p-value = 0.04). We identified and validated two cis-LINC00662-eQTLs (r² = 0.26) and three cis-C22orf34-eQTLs (r² = 0.24). Only LINC00662 showed a genotyped-based serum expression associated with GBC risk (OR = 1.25 per log2 expression unit, 95% CI 1.04-1.52, p-value = 0.02). Our results suggest that preselection of lncRNAs based on tissue samples and exploitation of cis-lncRNA-eQTLs may facilitate the identification of circulating noncoding RNAs linked to cancer risk.

Long Non-Coding RNAs in Lung Cancer: The Role in Tumor Microenvironment

The development of various therapeutic interventions, particularly immune checkpoint inhibitor therapy, have effectively induced tumor remission for patients with advanced lung cancer. However, few cancer patients can obtain significant and long-lasting therapeutic effects for the limitation of immunological nonresponse and resistance. For this case, it’s urgent to identify new biomarkers and develop therapeutic targets for future immunotherapy. Over the past decades, tumor microenvironment (TME)-related long non-coding RNAs (lncRNAs) have gradually become well known to us. A large number of existing studies have indicated that TME-related lncRNAs are one of the major factors to realize precise diagnosis and treatment of lung cancer. Herein, this paper discusses the roles of lncRNAs in TME, and the potential application of lncRNAs as biomarkers or therapeutic targets for immunotherapy in lung cancer.

Long intergenic non-protein coding RNA 662 accelerates the progression of gastric cancer through up-regulating centrosomal protein 55 by sponging microRNA-195-5p

Long non-coding RNAs (lncRNAs) are important players in regulating diverse human diseases, including cancers. Nonetheless, the function of long intergenic non-protein coding RNA 662 (LINC00662) in gastric cancer (GC) carcinogenesis and progression remains to be delineated. In the present study, LINC00662, microRNA-195-5p (miR-195-5p) and centrosomal protein 55 (CEP55) mRNA expression levels were quantified by qRT-PCR. GC cell proliferation, migration and invasion were analyzed by CCK-8, BrdU and Transwell assays. Besides, dual-luciferase reporter and RNA pull-down assays were conducted for verifying the targeting relationships of LINC00662, miR-195-5p and CEP55. The regulatory functions of LINC00662 and miR-195-5p on CEP55 were examined utilizing Western blot. In this study, it was revealed that LINC00662 expression level was elevated in GC tissues and cells. LINC00662 overexpression facilitated the malignant biological behaviors of GC cells whereas knockdown of LINC00662 worked oppositely. In terms of mechanism, LINC00662 targeted miR-195-5p to modulate CEP55 expression. In conclusion, LINC00662 facilitates the malignant biological behaviors of GC cells via miR-195-5p/CEP55 axis, and therefore, it may be a promising target for GC treatment.

The molecular mechanism of long non-coding ribonucleic acid (lncRNA) RUNX1-IT1 promotes the proliferation and stemness of lung cancer cells

BACKGROUND

This study sought to explore the role of long non-coding ribonucleic acid (lncRNA) RUNX1-IT1 in lung cancer proliferation and cell stemness and clarify its molecular mechanism.

METHODS

Quantitative reverse transcription polymerase chain reaction was used to detect the expression levels of lncRNA RUNX1-IT1 in lung cancer cell lines and tissues. Cell Counting Kit 8, a plate cloning experiment, a cell suspension sphere-forming assay and a Transwell assay were used to identify the effects of lncRNA RUNX1-IT1 overexpression or down-expression on clone formation, cell progression, cell stemness, and invasion. Western blot was used to detect the expression of associated proteins that regulate cell invasion and stemness.

RESULTS

Low expression levels of lncRNA RUNX1-IT1 were detected in the cancerous lung cells and tissues. The overexpression of lncRNA RUNX1-IT1 significantly restricted the ability of cells to proliferate, produce clones, form spheres, and invade lung cancer cells, while the knockdown of lncRNA RUNX1-IT1 had the opposite effect. The findings of the Western blot assessment showed that the overexpression or knockdown of lncRNA RUNX1-IT1 significantly affected the expression of cluster of differentiation 44, cluster of differentiation 133, sex-determining region Y-box 2, octamer-binding transcription factor 4, and Nanog, and regulated the sphere-forming ability of cells. Additionally, the overexpression or knockdown of lncRNA RUNX1-IT1 regulated the invasion ability of cells by affecting expressions of E-cadherin, N-cadherin, and Vimentin.

CONCLUSIONS

The poor expression, overexpression, or knockdown of lncRNA RUNX1-IT1 affects the stemness and invasion ability of lung cancer cells.

LncRNA ASAP1-IT1 enhances cancer cell stemness via regulating miR-509-3p/YAP1 axis in NSCLC

Background

Non-small cell lung cancer (NSCLC) is a major cause of cancer-related death worldwide, and cancer stem cell is responsible for the poor clinical outcome of NSCLC. Previous reports indicated that long noncoding RNAs (lncRNAs) play important roles in maintaining cancer stemness, however, the underlying mechanisms remain unclear. This study investigates the role of ASAP1 Intronic Transcript 1 (ASAP1-IT1) in cancer cell stemness of NSCLC.

Methods

The expression of ASAP1-IT1, microRNA-509-3p (miR-509-3p) and apoptosis-/stemness-related genes was analyzed by qRT-PCR in NSCLC tissues, cancer cells and spheres of cancer stem cells. Knockdown of ASAP1-IT1 or overexpression of miR-509-3p in NSCLC cells by infection or transfection of respective plasmids. Sphere formation and colony formation were used to detect NSCLC stem cell-like properties and tumor growth in vitro. Luciferase reporter assays, RNA immunoprecitation (RIP) and qRT-PCR assays were used to analyze the interaction between lncRNA and miRNA. The expression of expression of regulated genes of ASAP1-IT1/miR-509-3p axis was evaluated by qRT-PCR and Western blot. The NSCLC xenograft mouse model was used to validate the role of ASAP1-IT1 in NSCLC stemness and tumor growth in vivo.

Results

ASAP1-IT1 was up-regulated in NSCLC tissues, cancer cells, and in spheres of A549-derived cancer stem cells. Downregulation of ASAP1-IT1 or overexpression of miR-509-3p significantly decreased cell colony formation and stem cell-like properties of A549-dereived stem cells with decreased expression of stem cell biomarkers SOX2, CD34, and CD133, and suppressing the expression of cell growth-related genes, Cyclin A1, Cyclin B1, and PCNA. Furthermore, knockdown of ASAP1-IT1 or overexpression of miR-509-3p repressed tumor growth in nude mice via reducing expression of tumorigenic genes. ASAP1-IT1 was found to interact with miR-509-3p. Moreover, overexpression of ASAP1-IT1 blocked the inhibition by miR-509-3p on stem cell-like properties and cell growth of A549-dereived stem cells both in vitro and in vivo. Finally, the level of YAP1 was regulated by ASAP1-IT1 and miR-509-3p.

Conclusions

YAP1-involved ASAP1-IT1/miR-509-3p axis promoted NSCLC progression by regulating cancer cell stemness, and targeting this signaling pathway could be is a promising therapeutic strategy to overcome NSCLC stemness.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02270-7.

The Emerging Roles of Long Noncoding RNAs as Hallmarks of Lung Cancer

Noncoding ribonucleic acids (ncRNAs) are closely associated with tumor initiation, growth, and progress in lung cancer. Long ncRNAs (lncRNAs), as one of the three subclasses of ncRNAs, play important roles in chromatin modification, transcription, and post-transcriptional processing. Various lncRNAs have recently been reported to be dysfunctional or dysregulated in cancers and have pro- or anti-tumor potential. Importantly, as a new class of cancer biomarkers, studies have demonstrated the plausibility of using certain subsets of lncRNAs as promising diagnostic, therapeutic, or prognostic strategies to manage cancers. This review focuses on lncRNAs associated with hallmarks of lung cancer, especially those discovered in the last five years. The expression levels of these lncRNAs in tumor samples are discussed, alongside their mechanisms of action, drug resistance, and potential as diagnostic and prognostic markers for lung cancer.

Long non‑coding RNA HHIP‑AS1 inhibits lung cancer epithelial‑mesenchymal transition and stemness by regulating PCDHGA9

The aim of the present study was to investigate the effect of hedgehog‑interacting protein antisense RNA 1 (HHIP‑AS1) on epithelial‑mesenchymal transition (EMT) and cellular stemness of human lung cancer cells by regulating the microRNA (miR)‑153‑3p/PCDHGA9 axis. Reverse transcription‑quantitative PCR was used to compare the expression of HHIP‑AS1 in lung cancer and adjacent normal lung tissues. In addition, the correlation of HHIP‑AS1 with E‑cadherin, Vimentin, N‑cadherin and Twist1 was analyzed. HHIP‑AS1 overexpression vector was transfected into lung cancer A549 and NCI‑H1299 cell lines. Cell Counting Kit‑8 and Transwell and clonogenic assays were used to detect the proliferation, invasion and clonogenesis of the lung cancer cells, respectively. The associations among HHIP‑AS1, miR‑153‑3p and PCDHGA9 were predicted by bioinformatics analysis and verified by a dual‑luciferase reporter system. The results showed that the expression of HHIP‑AS1 in lung cancer tissues was significantly lower than that in normal tissues (P<0.001). HHIP‑AS1 was positively correlated with E‑cadherin and negatively correlated with Vimentin, N‑cadherin and Twist1. HHIP‑AS1 overexpression inhibited the proliferation, invasion and clonal formation of the A549 and NCI‑H1299 cells. The luciferase reporter system verified that HHIP‑AS1 could adsorb miR‑153‑3p and that PCDHGA9 was the target gene of miR‑153‑3p. A549 cells were transfected with HHIP‑AS1 overexpression vector and miR‑153‑3p mimic, and the miR‑153‑3p mimic had a mitigating effect on HHIP‑AS1 inhibition (P<0.001). In conclusion, HHIP‑AS1 inhibits the EMT and stemness of lung cancer cells by regulating the miR‑153‑3p/PCDHGA9 axis. Thus, HHIP‑AS1 may be a new potential target for lung cancer treatment.

LINC00662: A new oncogenic lncRNA with great potential

LINC00662 is located on chromosome 19q11 and is 2085 bp long. It is a long noncoding RNA (lncRNA) newly discovered. LINC00662 expression is upregulated in at least 14 tumors. In addition, the upregulation of LINC00662 expression is also closely related to the poor prognosis of cancer patients and resistance to radiotherapy and chemotherapy. LINC00662 can act as a ceRNA of at least 8 miRNAs. By regulating these miRNAs and their downstream genes, LINC00662 participates in the regulation of four signaling pathways, including the extracellular signal-regulated kinase (ERK) signaling pathway, the Wnt/β-catenin signaling pathway, the Hippo signaling pathway, and the SMD signaling pathway. In addition, the abnormal upregulation of LINC00662 can promote the stem-like features of lung cancer cells. LINC00662 can reduce the promoter methylation level of s-adenosylmethionine (SAM)-dependent hepatocellular carcinoma (HCC)-promoting genes by regulating the MAT1A/SAM and AHCY/SAH axes, thereby promoting the activation of oncogenes. This article summarizes the molecular regulation mechanism of LINC00662 in cancer and the diagnostic and prognostic value of LINC00662 in cancer.

LncRNA LINC00662 Exerts an Oncogenic Effect on Osteosarcoma by the miR-16-5p/ITPR1 Axis

Background

Osteosarcoma (OS) is one of the most malignant bone tumors and has a high metastatic rate. Increasing research has demonstrated the vital roles of long noncoding RNAs (lncRNAs) in human cancers, including OS. LncRNA LINC00662 has been revealed to act as an oncogene involved in multiple tumor progression. This study aimed to investigate the expression pattern, function, and regulatory mechanism of LINC00662 in OS.

Methods

Patients who underwent OS surgery were involved in this study. Experiments including RT-qPCR, MTT, western blot, FISH, RNA pull-down, luciferase reporter, colony formation, transwell invasion and migration, and sphere formation assay were performed to investigate the regulatory role of LINC00662 in OS.

Results

In the present study, our findings demonstrated the upregulation of LINC00662 expression in OS tissues and cells, and high expression of LINC00662 predicted a poor clinical prognosis of patients' iNOS. Through a series of in vivo assays, LINC00662 knockdown suppressed OS cell proliferation, invasion, migration, and stemness property maintenance. Further mechanistical investigations indicated that LINC00662 functioned as a competing endogenous RNA (ceRNA) for sponging microRNA-16-5p (miR-16-5p) to upregulate the expression of IP receptor type 1 (ITPR1) in OS cells. Restoration assays validated the involvement of ITPR1 in LINC00662-mediated regulation of cell functions in OS.

Conclusion

LINC00662 exerts oncogenic functions in OS by targeting the miR-16-5p/ITPR1 axis.

Hidden Treasures: Macrophage Long Non-Coding RNAs in Lung Cancer Progression

Ever since RNA sequencing of whole genomes and transcriptomes became available, numerous RNA transcripts without having the classic function of encoding proteins have been discovered. Long non-coding RNAs (lncRNAs) with a length greater than 200 nucleotides were considered as "junk" in the beginning, but it has increasingly become clear that lncRNAs have crucial roles in regulating a variety of cellular mechanisms and are often deregulated in several diseases, such as cancer. Lung cancer is the leading cause of cancer-related deaths and has a survival rate of less than 10%. Immune cells infiltrating the tumor microenvironment (TME) have been shown to have a great effect on tumor development with macrophages being the major cell type within the TME. Macrophages can inherit an inflammatory M1 or an anti-inflammatory M2 phenotype. Tumor-associated macrophages, which are predominantly polarized to M2, favor tumor growth, angiogenesis, and metastasis. In this review, we aimed to describe the complex roles and functions of lncRNAs in macrophages and their influence on lung cancer development and progression through the TME.

The Vital Roles of LINC00662 in Human Cancers

Long non-coding RNAs (lncRNAs) play crucial roles in many human diseases, particularly in tumorigenicity and progression. Although lncRNA research studies are increasing rapidly, our understanding of lncRNA mechanisms is still incomplete. The long intergenic non-protein coding RNA 662 (LINC00662) is a novel lncRNA, and accumulating evidence suggests that it is related to a variety of tumors in multiple systems, including the respiratory, reproductive, nervous, and digestive systems. LINC00662 has been shown to be upregulated in malignant tumors and has been confirmed to promote the development of malignant tumors. LINC00662 has also been reported to facilitate a variety of cellular events, such as tumor-cell proliferation, invasion, and migration, and its expression has been correlated to clinicopathological characteristics in patients with tumors. In terms of mechanisms, LINC00662 regulates gene expression by interacting with both proteins and with RNAs, so it may be a potential biomarker for cancer diagnosis, prognosis, and treatment. This article reviews the expression patterns, biological functions, and underlying molecular mechanisms of LINC00662 in tumors.

A positive feedback loop of LINC00662 and STAT3 promotes malignant phenotype of glioma

BACKGROUND

Long noncoding RNAs (lncRNAs) have been reported to be associated with tumorigenesis and development of glioma. LINC00662 has been involved in the pathogenesis of various human cancers. However, the mechanism underlying which LINC00662 exerts its role in glioma needs further exploration. In addition, regulation mechanism of LINC00662 expression in glioma remains unknown.

METHODS AND MATERIALS

RT-qPCR was performed to evaluate the expression levels of LINC00662, miR-340-5p in glioma tissues and cell lines. The effect of LINC00662 and miR-340-5p in cell proliferation and invasion was assessed by Cell Counting Kit-8(CCK-8), clone colony formation and Transwell assay. Luciferase reporter assays and RNA immunoprecipitation assay validated the miR-340-5p-target relationships with LINC00662 or STAT3. CHIP-qPCR and Luciferase reporter assays were used to demonstrate the interaction between STAT3 and the promoter region of LINC00662. A tumor xenografts model was implemented to verify the effect of LINC00662 on glioma development in vivo.

RESULTS

We found that LINC00662 was frequently highly expressed and related to the malignant phenotype of glioma. LINC00662 knockdown inhibited the proliferation, invasion and glioma genesis of glioma. LINC00662 acted as a ceRNA sponging miR-340-5p to protect the expression of STAT3. In addition, STAT3 was forced to the promoter region of LINC00662 and promoted its transcription. In vivo experiments demonstrated that targeting LINC00662 may be a potential strategy in glioma therapy.

CONCLUSION

There was a positive regulation loop between LINC00662 and STAT3 in glioma. LINC00662 might be an oncogene in glioma. Targeting LINC00662 was a potential strategy in glioma therapy.

Glioblastoma Primary Cells Retain the Most Copy Number Alterations That Predict Poor Survival in Glioma Patients

Gliomas are solid tumors that originate from glial cells in the brain or spine and account for 74.6% of malignant primary central nervous system tumors worldwide. As patient-derived primary cells are important tools for drug screening and new therapy development in glioma, we aim to understand the genomic similarity of the primary cells to their parental tumors by comparing their whole-genome copy number variations and expression profile of glioma clinicopathologic factors. We found that the primary cells from grade II/III gliomas lost most of the gene copy number alterations (CNAs), which were mainly located on chromosome 1p and 19q in their parental tumors. The glioblastoma (GBM) primary cells preserved 83.7% of the gene CNAs in the parental GBM tumors, including chromosome 7 gain and 10q loss. The CNA gains of LINC00226 and ADAM6 and the chromosome 16p11 loss were reconstituted in primary cells from both grade II/III gliomas and GBMs. Interestingly, we found these CNAs were correlated to overall survival (OS) in glioma patients using the Merged Cohort LGG and GBM dataset from cBioPortal. The gene CNAs preserved in glioma primary cells often predicted poor survival, whereas the gene CNAs lost in grade II/III primary cells were mainly associated to better prognosis in glioma patients. Glioma prognostic factors that predict better survival, such as IDH mutations and 1p/19q codeletion in grade II/III gliomas, were lost in their primary cells, whereas methylated MGMT promoters as well as TERT promoter mutations were preserved in GBM primary cells while lost in grade II/III primary cells. Our results suggest that GBM primary cells tend to preserve CNAs in their parental tumors, and these CNAs are correlated to poor OS and predict worse prognosis in glioma patients.

Functional Prediction of Long Noncoding RNAs in Cutaneous Melanoma Using a Systems Biology Approach

Cutaneous melanoma is the most aggressive type of skin cancer which its incidence has significantly increased in recent years worldwide. Thus, more investigations are required to identify the underlying mechanisms of melanoma malignant transformation and metastasis. In this context, long noncoding RNAs (lncRNAs) are a new type of noncoding transcripts that their dysregulations are associated with almost all cancers including melanoma. However, the precise functional roles of most of the significantly altered lncRNAs in melanoma have not yet been fully inspected. In this study, a comprehensive list of lncRNAs was interrogated across cutaneous melanoma samples to identify the significantly altered/dysregulated lncRNAs. To this end, lncRNAs were filtered in several steps and the selected lncRNAs projected to a bioinformatic and systems biology analysis using several publicly available databases and tools such as GEPIA and cBioPortal. According to our results, 30 lncRNAs were notably altered/dysregulated in cutaneous melanoma most of which were co-expressed with each other. Also, co-expression/alteration and differential expression analyses led to the selection of 12 out of these 30 lncRNAs as cutaneous melanoma key lncRNAs. Furthermore, functional demonstrated that these 12 lncRNAs might be involved in melanoma-relevant biological processes and pathways. In addition, the end result of our analyses demonstrated that these lncRNAs are associated with the clinicopathological features of melanoma patients. These 12 lncRNAs need to be further investigated in future studies to characterize their exact roles in melanoma development and to identify their potential for being used as drug targets and/or biomarkers for cutaneous melanoma.

Exosomal long non-coding RNA LINC00662 promotes non-small cell lung cancer progression by miR-320d/E2F1 axis

Non-small cell lung cancer (NSCLC) is the most common tumor affecting modern people and is associated with severe morbidity and high mortality. Exosomal long non-coding RNAs as crucial regulators are involved in cancer progression. However, the role of exosomal lncRNA LINC00662 in the development of NSCLC remains unclear. Here, we aimed to explore the impact of exosomal lncRNA LINC00662 on the NSCLC progression and the underlying mechanism. Significantly, we revealed that the expression of lncRNA LINC00662 was elevated in the plasma exosome of NSCLC patients. Exosomal LINC00662 promoted proliferation, invasion, and migration, and inhibited apoptosis and cell cycle arrest of NSCLC cells. Mechanically, LINC00662 was able to serve as a miR-320d sponge in NSCLC cells. MiR-320d could target E2F1 in NSCLC cells. Exosomal LINC00662 contributed to the progression of NSCLC by miR-320d/E2F1 axis in vitro. Remarkably, exosomal LINC00662 enhanced the tumor growth of NSCLC in vivo. Thus, we conclude that exosomal lncRNA LINC00662 promotes NSCLC progression by modulating miR-320d/E2F1 axis. Our finding provides new insights into the mechanism by which exosomal lncRNA LINC00662 contributes to the development of NSCLC. LncRNA LINC00662, miR-320d, and E2F1 may serve as potential targets for NSCLC therapy.

Non-coding RNAs regulation of macrophage polarization in cancer

Noncoding RNA (ncRNA) transcripts that did not code proteins but regulate their functions were extensively studied for the last two decades and the plethora of discoveries have instigated scientists to investigate their dynamic roles in several diseases especially in cancer. However, there is much more to learn about the role of ncRNAs as drivers of malignant cell evolution in relation to macrophage polarization in the tumor microenvironment. At the initial stage of tumor development, macrophages have an important role in directing Go/No-go decisions to the promotion of tumor growth, immunosuppression, and angiogenesis. Tumor-associated macrophages behave differently as they are predominantly induced to be polarized into M2, a pro-tumorigenic type when recruited with the tumor tissue and thereby favoring the tumorigenesis. Polarization of macrophages into M1 or M2 subtypes plays a vital role in regulating tumor progression, metastasis, and clinical outcome, highlighting the importance of studying the factors driving this process. A substantial number of studies have demonstrated that ncRNAs are involved in the macrophage polarization based on their ability to drive M1 or M2 polarization and in this review we have described their functions and categorized them into oncogenes, tumor suppressors, Juggling tumor suppressors, and Juggling oncogenes.

HNRNPH1-stabilized LINC00662 promotes ovarian cancer progression by activating the GRP78/p38 pathway

Numerous studies suggest an important role for copy number alterations (CNAs) in cancer progression. However, CNAs of long intergenic noncoding RNAs (lincRNAs) in ovarian cancer (OC) and their potential functions have not been fully investigated. Here, based on analysis of The Cancer Genome Atlas (TCGA) database, we identified in this study an oncogenic lincRNA termed LINC00662 that exhibited a significant correlation between its CNA and its increased expression. LINC00662 overexpression is highly associated with malignant features in OC patients and is a prognostic indicator. LINC00662 significantly promotes OC cell proliferation and metastasis in vitro and in vivo. Mechanistically, LINC00662 is stabilized by heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1). Moreover, LINC00662 exerts oncogenic effects by interacting with glucose-regulated protein 78 (GRP78) and preventing its ubiquitination in OC cells, leading to activation of the oncogenic p38 MAPK signaling pathway. Taken together, our results define an oncogenic role for LINC00662 in OC progression mediated via GRP78/p38 signaling, with potential implications regarding therapeutic targets for OC.

LncRNA DHRS4-AS1 Inhibits the Stemness of NSCLC Cells by Sponging miR-224-3p and Upregulating TP53 and TET1

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death. This study aimed to examine the roles of DHRS4-AS1/miR-224-3p signaling in the cancer cell stemness of NSCLC. Real-time PCR showed that DHRS4-AS1 was downregulated in cancerous tissues, and bioinformatics analysis revealed that high DHRS4-AS1 expression indicated a good prognosis for NSCLC patients. Sphere and colony formation assays showed that DHRS4-AS1 overexpression significantly suppressed NSCLC cell colony formation and stem cell-like properties. DHRS4-AS1 also abrogated the expression of OCT4, SOX2, CD34, and CD133, markedly inhibited the expression of epithelial-mesenchymal transition (EMT)-related factors, N-cadherin, ZEB1, and Vimentin, and increased E-cadherin expression in spheres. Furthermore, luciferase reporter assays and real-time PCR analysis demonstrated that DHRS4-AS1 and miR-224-3p were antagonistically repressed in NSCLC cells. RNA immunoprecipitation (RIP) analysis revealed that DHRS4-AS1 interacted with miR-224-3p. DHRS4-AS1 partially reversed the miR-224-3p-decreased TP53 and TET1, resulting in the inhibition of tumor growth in vivo. Finally, TP53 and TET1 were antagonistically regulated by DHRS4-AS1 and miR-224-3p in NSCLC cells. In conclusion, TP53- and TET1-associated DHRS4-AS1/miR-224-3p axis is an essential mechanism by which NSCLC modulates cancer cell stemness.

Silencing linc00662 inhibits cell proliferation and colony formation of lung cancer cells via regulating the miR-145-5p-PAFAH1B2 axis

Lung cancer is the most common cause of cancer-related death in the world. Long non-coding RNAs (lncRNAs) are longer than 200 nucleotide transcripts, and are not translated into protein. The lncRNA linc00662 is overexpressed in lung cancer; however, its role in lung cancer is still unknown. In our study, by analyzing the TCGA data, we found that linc00662 was overexpressed in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). We knocked-down the expression of linc00662 using siRNA, and found that silencing linc00662 significantly inhibited the proliferation and colony formation of the lung cancer cell lines A549 and H460. We also found that knockdown of linc00662 increased the expression of the microRNA miR-145-5p and decreased the expression of the platelet-activating factor acetylhydrolase IB subunit beta (PAFAH1B2) gene. We further show that linc00662 binds with miR-145-5p, and that miR-145-5p binds to the 3'UTR of PAFAH1B2. miR-145-5p negatively regulates PAFAH1B2 both at the mRNA and the protein level. Loss of miR-145-5p abolished the inhibitory effects of silencing linc00662 on the proliferation and colony formation of A549 and H460 cells. These findings indicate that linc00662 functions as an oncogene by acting as a competing endogenous RNA (ceRNA) and sponges and regulates miR-145-5p in lung cancer, and thus may provide a potential target for treating lung cancer.

Long Non-Coding RNA LINC00662 Regulated Proliferation and Migration by Targeting miR-34a-5p/LMAN2L Axis in Glioma

Background

Numerous studies suggest that long non-coding RNAs (lncRNAs) participate in the biological process of diverse malignancies, including glioma. Although many differentially expressed lncRNAs have been identified in glioma, to our best knowledge, the role of LINC00662 and its potential underlying mechanism in glioma progression remains unclear. This study aimed to explore the function and regulatory network of LINC00662 in glioma.

Methods

Expressions of LINC00662, miR-34a-5p and lectin mannose-binding 2-like (LMAN2L) in glioma tissues were analyzed using The Cancer Genome Atlas Program (TCGA) and the Chinese Glioma Genome Atlas (CGGA) databases. Colony formation, Celltiter-Glo and BrdU (5-bromo-2'-deoxyuridine) incorporation assays were used to detect cell proliferation in vitro. Xenograft mouse models were established to determine cell proliferation in vivo. Transwell and wound healing assay was used to detect cell migration. In addition, epithelial-mesenchymal transition (EMT) markers were detected by Western blot. Annexin V and 7-AAD were used to stain apoptotic cells. Interactions between miR-34a-5p and LINC00662 or the 3'-UTR of LMAN2L were predicted and determined by bioinformatics analysis, luciferase reporter assay and RNA immunoprecipitation (RIP) assays.

Results

High LINC00662 level predicted poor overall survival of glioma patients. Functional studies revealed that suppression of LINC00662 remarkably inhibited cell proliferation, clonogenicity and EMT pathway. Mechanistically, LINC00662 sponged miR-34a-5p to regulate LMAN2L expression. Furthermore, miR-34a-5p inhibitor reversed the anti-proliferation and anti-migration effect of LINC00662 knockdown, which could be rescued by downregulation of LMAN2L in glioma cells.

Conclusion

Our study was the first to report that LINC00662 acted as a competing endogenous RNA (ceRNA) to regulate glioma progression by targeting miR-34a-5p/LMAN2L axis, providing a new therapeutic target for glioma.

LINC00662 contributes to the progression and the radioresistance of cervical cancer by regulating miR-497-5p and CDC25A

It is reported that long intergenic non-coding RNA 00662 (LINC00662) plays an oncogenic role in tumours. However, the mechanism of LINC00662 in regulating the progression and radiosensitivity of cervical cancer (CC) is not clear. In this study, quantitative real-time polymerase chain reaction (qRT-PCR) was adopted to detect LINC00662 and miR-497-5p expressions in CC tissues and cells. The expression of cell division cycle 25 A (CDC25A) in CC cells was examined by Western blot. CC cell proliferation was determined by cell counting kit-8 (CCK-8) and BrdU assays. The survival rate of CC cells was evaluated by colony formation assay under different doses of X-ray irradiation. CC cell migration and invasion were probed by Transwell assay. Besides, the interactions between miR-497-5p and LINC00662, and miR-497-5p and the 3'UTR of CDC25A were verified by dual-luciferase reporter assay, RIP assay, and RNA pull-down experiments. We demonstrated that, LINC00662 expression was remarkably raised in CC tissues and cell lines. LINC00662 overexpression promoted proliferation, migration, invasion and radioresistance of CC cells, and LINC00662 knockdown inhibited the above malignant phenotypes of CC cells. In terms of mechanism, LINC00662 facilitated CC progression and radioresistance by adsorbing miR-497-5p and indirectly up-regulating CDC25A expression. In a word, the LINC00662/miR-497-5p/CDC25A axis boosts proliferation and metastasis of CC cells and enhances the radioresistance of cancer cells. SIGNIFICANCE OF THE STUDY: CC poses a threat to the health of women all over the world. In this study, we demonstrated for the first time that LINC00662 expression was remarkably raised in CC tissues and cells. Cellular experiments confirmed that LINC00662 facilitated cell proliferation, migration, invasion and radiation resistance through the miR-497-5p/CDC25A axis, which might be a promising target for CC treatments.

LINC00662 Long Non-Coding RNA Knockdown Attenuates the Proliferation, Migration, and Invasion of Osteosarcoma Cells by Regulating the microRNA-15a-5p/Notch2 Axis

Purpose

Osteosarcoma (OS) is a frequently occurring malignancy in children and adolescents. In this study, we aimed to investigate the effects of the long non-coding RNA (lncRNA) LINC00662 (LINC00662) in OS and the underlying molecular mechanism.

Methods

The expression of LINC00662, microRNA-15a-5p (miR-15a-5p), and Notch2 in OS was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The proliferation, migration, and invasion of OS cells were analyzed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), wound-healing, and transwell assay. The interactions among LINC00662, miR-15a-5p, and Notch2 were determined by dual-luciferase reporter assays. A tumor xenograft model was established in mice for evaluating tumor growth in vivo.

Results

The expression of LINC00662 and Notch2 was found to be upregulated in OS, but the expression of miR-15a-5p was downregulated. The results demonstrated that LINC00662 knockdown attenuated the proliferation, migration, and invasion of OS cells and suppressed tumor growth in mice. The study further demonstrated that LINC00662 directly interacted with miR-15a-5p, and that Notch2 was a target of miR-15a-5p. The inhibition of miR-15a-5p or Notch2 overexpression markedly reversed the suppressive effect of sh-LINC00662 on the proliferation, migration, and invasion of OS cells.

Conclusion

The study demonstrated that LINC00662 could be a potential biomarker for OS therapy, and LINC00662 knockdown suppressed the proliferation, migration, and invasion of OS cells by regulating the miR-15a-5p/Notch2 axis.

Knockdown of LINC00662 represses AK4 and attenuates radioresistance of oral squamous cell carcinoma

Background

LncRNAs play crucial roles in the development of carcinomas. However, the investigation of LINC00662 in Oral squamous cell carcinoma (OSCC) is still elusive.

Methods

qRT-PCR assay tested the expression levels of LINC00662, hnRNPC and AK4. With exposure to irradiation, CCK-8, colony formation, flow cytometry and western blot experiments, respectively determined the function of LINC00662 in the radiosensitivity of OSCC cells. Then RIP and western blot assays affirmed the interaction between hnRNPC protein and LINC00662 or AK4. Finally, rescue assays validated the regulation mechanism of LINC00662 in the radioresistance of OSCC.

Results

In the present report, LINC00662 was overexpressed in OSCC and its silencing could alleviate radioresistance of OSCC. Furthermore, the interaction between hnRNPC protein and LINC00662 or AK4 was uncovered. Besides, LINC00662 regulated AK4 mRNA stability through binding to hnRNPC protein. To sum up, LINC00662 modulated the radiosensitivity of OSCC cells via hnRNPC-modulated AK4.

Conclusion

The molecular mechanism of the LINC00662/hnRNPC/AK4 axis was elucidated in OSCC, which exhibited a promising therapeutic direction for patients with OSCC.

TRA2A-induced upregulation of LINC00662 regulates blood-brain barrier permeability by affecting ELK4 mRNA stability in Alzheimer's microenvironment

The blood-brain barrier (BBB) plays a pivotal role in the maintenance and regulation of the neural microenvironment. The BBB breakdown is a pathological change in early Alzheimer's disease (AD). RNA-binding proteins (RBPs) and long non-coding RNAs (lncRNAs) are involved in the regulation of BBB permeability. Our study demonstrates the role of TRA2A/LINC00662/ELK4 axis in regulating BBB permeability in AD microenvironment. In Aβ_1-42-incubated microvascular endothelial cells (ECs) of the BBB model in vitro, TRA2A and LINC00662 were enriched. TRA2A increased the stability of LINC00662 by binding with it. The knockdown of either TRA2A or LINC00662 decreased BBB permeability due to increased expression of tight junction-related proteins. ELK4 was less expressed in the BBB model in AD microenvironment in vitro. LINC00662 mediated the degradation of ELK4 mRNA by SMD pathway. Downregulation of ELK4 increased BBB permeability by increasing the tight junction-related protein expression.TRA2A/LINC00662/ELK4 axis plays a crucial role in the regulation of BBB permeability in AD microenvironment, which may provide a novel target for the therapy of AD.

Post-transcriptional regulations of cancer stem cell homeostasis

PURPOSE OF REVIEW

Although extensively studied for over a decade, gene expression programs established at the epigenetic and/or transcriptional levels do not fully characterize cancer stem cells (CSC). This review will highlight the latest advances regarding the functional relevance of different key post-transcriptional regulations and how they are coordinated to control CSC homeostasis.

RECENT FINDINGS

In the past 2 years, several groups have identified master post-transcriptional regulators of CSC genetic programs, including RNA modifications, RNA-binding proteins, microRNAs and long noncoding RNAs. Of particular interest, these studies reveal that different post-transcriptional mechanisms are coordinated to control key signalling pathways and transcription factors to either support or suppress CSC homeostasis.

SUMMARY

Deciphering molecular mechanisms coordinating plasticity, survival and tumourigenic capacities of CSCs in adult and paediatric cancers is essential to design new antitumour therapies. An entire field of research focusing on post-transcriptional gene expression regulation is currently emerging and will significantly improve our understanding of the complexity of the molecular circuitries driving CSC behaviours and of druggable CSC weaknesses.

Long non-coding RNAs: How to regulate the metastasis of non-small-cell lung cancer

Non–small‐cell lung cancer (NSCLC) has become the most lethal human cancer because of the high rate of metastasis. Hence, clarifying the molecular mechanism underlying NSCLC metastasis is very important to improve the prognosis of patients with NSCLC. Long non‐coding RNAs (LncRNAs) are a class of RNA molecules longer than 200 nucleotides, which can participate in diverse biological processes. About 18% of human LncRNAs were recently found to be associated with tumours. Many studies indicated that aberrant expression of LncRNAs played key roles in the progression and metastasis of NSCLC. According to the function in tumours, LncRNAs can be divided into two classes: oncogenic LncRNAs and tumour‐suppressor LncRNAs. In this review, we summarized the main molecular mechanism of LncRNAs regulating NSCLC metastasis, including three aspects: (a) LncRNAs interact with miRNAs as ceRNAs; (b) LncRNAs bind with target proteins; and (c) LncRNAs participate in the transduction of different signal pathways. Then, LncRNAs can exert their function to regulate the metastasis of NSCLC through influencing the progression of epithelial‐mesenchymal transition (EMT) and the properties of cancer stem cell (CSC). But, it is necessary to do some further research to demonstrate the LncRNAs particular regulatory mechanism of inhibiting the metastasis of NSCLC and explore new drugs targeting LncRNAs.

LINC00662 promotes hepatocellular carcinoma progression via altering genomic methylation profiles

The identification of viability-associated long noncoding RNAs (lncRNAs) is a means of uncovering therapeutic approaches for hepatocellular carcinoma (HCC). In addition, aberrant genome-wide hypomethylation has been implicated in HCC initiation and progression. However, the relationship between lncRNA dysregulation and genome-wide hypomethylation in hepatocarcinogenesis has not been fully elucidated. A novel lncRNA named LINC00662 was previously demonstrated to play a role in gastrointestinal cancer. In this study, we demonstrated that this lncRNA was correlated with survival and exhibited oncogenic properties, both in vitro and in vivo. Moreover, we determined that LINC00662 could lead to genome-wide hypomethylation and alter the genomic methylation profile by synchronously reducing the S-adenosylmethionine (SAM) level and enhancing the S-adenosylhomocysteine (SAH) level. Mechanistically, LINC00662 was determined to regulate the key enzymes influencing SAM and SAH levels, namely, methionine adenosyltransferase 1A (MAT1A) and S-adenosylhomocysteine hydrolase (AHCY), by RNA-RNA and RNA-protein interactions. In addition, we demonstrated that some SAM-dependent HCC-promoting genes could be regulated by LINC00662 by altering the methylation status of their promoters via the LINC00662-coupled axes of MAT1A/SAM and AHCY/SAH. Taken together, the results of this this study indicate that LINC00662 could be a potential biomarker for HCC therapy. More importantly, we proposed a new role of lncRNA in regulating genomic methylation to promote oncogene activation.

LncRNA LINC00662 promotes colon cancer tumor growth and metastasis by competitively binding with miR-340-5p to regulate CLDN8/IL22 co-expression and activating ERK signaling pathway

BACKGROUND

LncRNA LINC00662 is closely related to the occurrence and development of cancer. This study aims to explore the effect of LINC00662 on colon cancer tumor growth and metastasis and its molecular mechanism.

METHODS

CCK8, colony formation, transwell, scratch wound, TUNEL, flow cytometry, RT-PCR, western blotting and immunohistochemistry assays were used to detect the proliferation, apoptosis, invasion and migration of colon cancer cell and mRNA and protein expressions. Luciferase reporter and RNA pull down assays were used to detect the combination of LINC00662 and miR-340-5p or IL22 and the combination of miR-340-5p and CLDN8/IL22. Co-immunoprecipitation were used to detect the co-expression of CLDN8 and IL22 in colon cell lines. The targets of LINC00662 were predicated by Starbase v2.0. The target genes of miR-340-5p were predicated by miRDB and TargetScan. GO and KEGG enrichment analysis were performed by DAVID website.

RESULTS

LINC00662 was up-regulation in colon cancer tissues and cell lines. Univariate Cox regression analysis showed that the LINC00662 expression level was related to the poor prognosis. LINC00662-WT and miR-340-5p mimics co-transfection depressed luciferase activity and IL22/CLDN8-WT and miR-340-5p inhibitors co-transfection memorably motivated luciferase activity. LINC00662 overexpression promoted cell proliferation, invasion and migration, and inhibited cell apoptosis in colon cancer. In vivo xenograft studies in nude mice manifested that LINC00662 overexpression prominently accelerate tumor growth. There was an opposite reaction in the biological functions of colon cells and tumor growth between LINC00662 overexpression and LINC00662 inhibition in vitro and in vivo. The functions of miR-340-5p mimics regulating the biological functions of colon cells and tumor growth were consistent with those of LINC00662 inhibition. CLDN8 and IL22, as target genes of miR-340-5p, reversed the functions of LINC00662 affecting the biological functions of colon cells and the protein levels of Bax, Bcl-2, XIAP, VEGF, MMP-2, E-cadherin and N-cadherin. Co-immunoprecipitation experiments indicated that CLDN8 directly interact with IL22 in colon cell lines. LINC00662 regulated CLDN8 and IL22 expressions and the activation of ERK signaling pathway via targeting miR-340-5p.

CONCLUSION

LINC00662 overexpression promoted the occurrence and development of colon cancer by competitively binding with miR-340-5p to regulate CLDN8/IL22 co-expression and activating ERK signaling pathway.

Long noncoding RNA LINC00662 promotes M2 macrophage polarization and hepatocellular carcinoma progression via activating Wnt/β-catenin signaling

Tumor-associated macrophages have important roles in hepatocellular carcinoma (HCC) initiation and progression. Long noncoding RNAs (lncRNAs) have also been reported to be involved in HCC. In this study, we explored how lncRNA LINC00662 may influence HCC progression through both tumor cell-dependent and macrophage-dependent mechanisms. LINC00662 was found to be upregulated in HCC, and high LINC00662 levels correlated with poor survival of HCC patients. LINC00662 upregulated WNT3A expression and secretion via competitively binding miR-15a, miR-16, and miR-107. Through inducing WNT3A secretion, LINC00662 activated Wnt/β-catenin signaling in HCC cells in an autocrine manner and further promoted HCC cell proliferation, cell cycle, and tumor cell invasion, while repressing HCC cell apoptosis. In addition, acting through WNT3A secretion, LINC00662 activated Wnt/β-catenin signaling in macrophages in a paracrine manner and further promoted M2 macrophage polarization. Via activating Wnt/β-catenin signaling and M2 macrophages polarization, LINC00662 significantly promoted HCC tumor growth and metastasis in vivo. Hence, targeting LINC00662 may provide novel therapeutic strategy against HCC.

Long non-coding RNA MEG3 regulates migration and invasion of lung cancer stem cells via miR-650/SLC34A2 axis

Long non-coding RNA maternally expressed gene 3 (MEG3) is related to the occurrence and development of non-small cell lung cancer (NSCLC). However, the function and underlying molecular mechanisms of MEG3 in lung cancer stem cells (LCSCs) are still unclear. LCSCs were determined in lung cancer cells using fluorescence-activated cell sorting (FACS). qRT-PCR and western blot were performed to examine the expressions of MEG3, miR-650, solute carrier family 34 member 2 (SLC34A2), octamer-binding transcription factor 4 (Oct4), and CD133. Sphere assay was employed to evaluate sphere-forming ability. Cell migration and invasion were analyzed by Transwell assay. The relationships among MEG3, miR-650, and SLC34A2 were validated by luciferase reporter, RIP, and RNA pulldown assays. We found MEG3 was downregulated in LCSCs. MEG3 depletion strengthened stem cell-like characteristics and sphere-forming ability in LCCs. Upregulation of MEG3 suppressed migration and invasion in LCCs and LCSCs. miR-650 was bound to MEG3 and upregulated in LCSCs. miR-650 inhibitor alleviated si-MEG3-induced promotion of stem cell-like characteristics in lung cancer cells (LCCs) H1299. Furthermore, miR-650 mimic attenuated the MEG3 upregulation-mediated inhibition of migration and invasion. In addition, SLC34A2 was a target of miR-650 and downregulated in LCSCs. miR-650 mimic induced stem cell-like characteristics in LCCs, which was weakened by overexpression of SLC34A2. In contrast, the repression of SLC34A2 mitigated the miR-650 silencing-induced inhibition of migration and invasion in LCCs and LCSCs. Besides, MEG3 regulated SLC34A2 expression by sponging miR-650. Importantly, SLC34A2 weakened MEG3-mediated stem cell-like state and cell metastasis. Our data suggested MEG3 was involved in stem cell-like state of LCCs and curbed migration and invasion through miR-650/SLC34A2 axis in NSCLC.

High expression of long intergenic non-coding RNA LINC00662 contributes to malignant growth of acute myeloid leukemia cells by upregulating ROCK1 via sponging microRNA-340-5p

Long non-coding RNAs (lncRNAs) have emerged as crucial regulatory factors in diverse pathological processes, especially in tumorigenesis. Accumulating evidence has demonstrated that long intergenic non-coding RNA 00662 (LINC00662) is overexpressed in multiple cancers and facilitates cancer development and progression. However, whether LINC00662 is involved in acute myeloid leukemia (AML) remains unknown. This study was aimed to explore the expression, biological function and regulatory mechanism of LINC00662 in AML. Here, we found that LINC00662 was significantly increased in AML tissues and cell lines. Knockdown of LINC00662 significantly reduced the growth of AML cells and upregulated AML cell apoptosis. In contrast, overexpression of LINC00662 promoted AML cell growth. MicroRNA-340-5p (miR-340-5p) was predicted as a target of LINC00662. Luciferase reporter assays and RNA pull-down assays confirmed that LINC00662 directly interacted with miR-340-5p. Expression of miR-340-5p was downregulated in AML and silencing of LINC00662 upregulated miR-340-5p expression in AML cells. Moreover, overexpression of miR-340-5p inhibited cell growth and increased apoptosis in AML cells. Inhibition of miR-340-5p significantly reversed the inhibitory effect of LINC00662 silencing on AML cell growth. In addition, Rho-associated protein kinase 1 (ROCK1) was verified as a target gene of miR-340-5p in AML cells. Restoration of ROCK1 expression partially reversed LINC00662 silencing or miR-340-5p overexpression-mediated inhibitory effect on AML cell growth. Overall, our results demonstrate that LINC00662 contributes to the malignant growth of AML cells by upregulating ROCK1 via sponging miR-340-5p, highlighting the important role of the LINC00662/miR-340-5p/ROCK1 axis in regulating the malignant behavior of AML cells.

Linc00662 Promotes Tumorigenesis and Progression by Regulating miR-497-5p/AVL9 Axis in Colorectal Cancer

BACKGROUND

Recently, multiple lines of evidence have demonstrated that linc00662 serves as an oncogene in various cancers. However, the exact mechanism of oncogenesis mediated by linc00662 in colorectal cancer (CRC) remains unknown. In this study, we aimed to explore the biological role of linc00662 in the regulation of CRC progression.

METHODS

Both gene expression omnibus (GEO) and the cancer genome atlas (TCGA) datasets were used to evaluate the expression of linc00662. RT-qPCR was used to analyze the expression of linc00662, miR-497-5p, and AVL9 in CRC clinical samples and cell lines. Cell Counting Kit-8 (CCK-8), flow cytometry, transwell assay, and xenograft model were used to investigate the effect of linc00662 on CRC cell proliferation, cell cycle, and metastasis. Western blot analysis was used to analyze the expression of the epithelial-mesenchymal transition (EMT)-associated markers. Furthermore, bioinformatics analysis and mechanism assays were used to elucidate the underlying mechanism. Dual-luciferase reporter assays were used to analyze the regulatory relationships among linc00662, miR-497-5p, and AVL9.

RESULTS

In this study, we found that the expression of linc00662 was significantly upregulated in CRC tissues compared to normal tissues and positively correlated with tissue differentiation, T stage, and lymphatic metastasis. Further, our data showed that the expression of linc00662 was positively associated with lymph node metastasis, TMN stage, and poor-moderate differentiation. Patients with higher linc00662 expression level were more likely to have poorer overall survival. Knockdown of linc00662 inhibited CRC cell growth, induced cell apoptosis, triggered cell cycle arrest at G2/M phase, and suppressed cell migration and invasion through regulating the EMT pathway. Further, mechanistic studies revealed that knockdown of linc00662 significantly reduced the expression of AVL9, a direct target of miR-497-5p.

CONCLUSIONS

Linc00662 was significantly upregulated in CRC, and mediated CRC progression and metastasis by competing with miR-497-5p to modulate the expression of AVL9. Therefore, our result sheds light on the potential application of linc00662 in CRC diagnosis and therapy.