lncRNA TUG1 Promotes Cell Proliferation, Migration, and Invasion in Hepatocellular Carcinoma via Regulating miR-29c-3p/COL1A1 Axis

Current understanding of functional peptides encoded by lncRNA in cancer

Dysregulated gene expression and imbalance of transcriptional regulation are typical features of cancer. RNA always plays a key role in these processes. Human transcripts contain many RNAs without long open reading frames (ORF, > 100 aa) and that are more than 200 bp in length. They are usually regarded as long non-coding RNA (lncRNA) which play an important role in cancer regulation, including chromatin remodeling, transcriptional regulation, translational regulation and as miRNA sponges. With the advancement of ribosome profiling and sequencing technologies, increasing research evidence revealed that some ORFs in lncRNA can also encode peptides and participate in the regulation of multiple organ tumors, which undoubtedly opens a new chapter in the field of lncRNA and oncology research. In this review, we discuss the biological function of lncRNA in tumors, the current methods to evaluate their coding potential and the role of functional small peptides encoded by lncRNA in cancers. Investigating the small peptides encoded by lncRNA and understanding the regulatory mechanisms of these functional peptides may contribute to a deeper understanding of cancer and the development of new targeted anticancer therapies.

LncRNA taurine upregulated gene 1 in liver disease

Long non-coding RNAs (lncRNAs) are RNA sequences exceeding 200 nucleotides in length that lack protein-coding capacity and participate in diverse biological processes in the human body, particularly exerting a pivotal role in disease surveillance, diagnosis, and progression. Taurine upregulated gene 1 (TUG1) is a versatile lncRNA, and recent studies have revealed that the aberrant expression or function of TUG1 is intricately linked to the pathogenesis of liver diseases. Consequently, we have summarized the current understanding of the mechanism of TUG1 in liver diseases such as liver fibrosis, fatty liver, cirrhosis, liver injury, hepatitis, and liver cancer. Moreover, mounting evidence suggests that interventions targeting TUG1 or its downstream pathways may hold therapeutic promise for liver diseases. This review elucidates the characteristics, mechanisms, and targets of TUG1 in liver diseases, offering a theoretical basis for the prevention, diagnosis, treatment, and prognostic biomarkers of liver diseases.

Differentially expressed non-coding RNAs and their regulatory networks in liver cancer

The vast majority of human transcriptome is represented by various types of small RNAs with little or no protein-coding capability referred to as non-coding RNAs (ncRNAs). Functional ncRNAs include microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), which are expressed at very low, but stable and reproducible levels in a variety of cell types. ncRNAs regulate gene expression due to miRNA capability of complementary base pairing with mRNAs, whereas lncRNAs and circRNAs can sponge miRNAs off their target mRNAs to act as competitive endogenous RNAs (ceRNAs). Each miRNA can target multiple mRNAs and a single mRNA can interact with several miRNAs, thereby creating miRNA-mRNA, lncRNA-miRNA-mRNA, and circRNA-miRNA-mRNA regulatory networks. Over the past few years, a variety of differentially expressed miRNAs, lncRNAs, and circRNAs (DEMs, DELs, and DECs, respectively) have been linked to cancer pathogenesis. They can exert both oncogenic and tumor suppressor roles. In this review, we discuss the recent advancements in uncovering the roles of DEMs, DELs, and DECs and their networks in aberrant cell signaling, cell cycle, transcription, angiogenesis, and apoptosis, as well as tumor microenvironment remodeling and metabolic reprogramming during hepatocarcinogenesis. We highlight the potential and challenges in the use of differentially expressed ncRNAs as biomarkers for liver cancer diagnosis and prognosis.

Transcriptomic analysis of the cerebral hippocampal tissue in spontaneously hypertensive rats exposed to acute hypobaric hypoxia: associations with inflammation and energy metabolism

We evaluated the effect of acute hypobaric hypoxia (AHH) on the hippocampal region of the brain in early-stage spontaneously hypertensive male rats. The rats were classified into a control (ground level; ~ 400 m altitude) group and an AHH experimental group placed in an animal hypobaric chamber at a simulated altitude of 5500 m for 24 h. RNA-Seq analysis of the brains and hippocampi showed that differentially expressed genes (DEGs) were primarily associated with ossification, fibrillar collagen trimer, and platelet-derived growth factor binding. The DEGs were classified into functional categories including general function prediction, translation, ribosomal structure and biogenesis, replication, recombination, and repair. Pathway enrichment analysis revealed that the DEGs were primarily associated with relaxin signaling, PI3K-Akt signaling, and amoebiasis pathways. Protein-protein interaction network analysis indicated that 48 DEGs were involved in both inflammation and energy metabolism. Further, we performed validation experiments to show that nine DEGs were closely associated with inflammation and energy metabolism, of which two (Vegfa and Angpt2) and seven (Acta2, Nfkbia, Col1a1, Edn1, Itga1, Ngfr, and Sgk1) genes showed up and downregulated expression, respectively. Collectively, these results indicated that inflammation and energy metabolism-associated gene expression in the hippocampus was altered in early-stage hypertension upon AHH exposure.

Functional roles of lncRNA-TUG1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) or hepatoma is malignant cancer that starts from the main liver cells. Although various classical methods have been used for patients with HCC, various molecular mechanisms involved in HCC progression should be invested. Previous studies demonstrated that abnormal expression of long non-coding RNAs (lncRNAs) presented important roles in the pathogenesis of HCC cells. LncRNA TUG1 was found to mediate HCC cell growth, EMT, and metastasis. Therefore, targeting TUG1 and its downstream genes may be a suitable approach for patients with HCC. In this review, we summarized the potential roles of TUG1 in HCC.

COL1A1: A novel oncogenic gene and therapeutic target in malignancies

Collagen type I alpha 1 (COL1A1), a member of the collagen family, is involved in epithelial-mesenchymal transition, which is closely linked to malignant tumorigenesis. COL1A1 is highly expressed in various cancers and regulates various cellular processes, including cell proliferation, metastasis, apoptosis, and cisplatin resistance. COL1A1 is also associated with cancer progression and prognosis; elevated COL1A1 expression is associated with poor prognosis in cancer patients. However, the main role of COL1A as a cancer-promoting factor in specific tumors has not been reported. Additionally, the protein levels and mechanisms of action of this protein differ among tumor types. This review discusses current research progress concerning COL1A1 in different tumor types, and then summarizes its contributions to cancer progression, thus providing a basis for follow-up research and potential targets for cancer treatment.

LncRNA LINC00511 promotes COL1A1-mediated proliferation and metastasis by sponging miR-126-5p/miR-218-5p in lung adenocarcinoma

Background

Lung adenocarcinoma (LUAD) is currently the leading cause of cancer-related death worldwide. Long noncoding RNAs (lncRNAs) play key roles in tumor occurrence and development as crucial cancer regulators. The present study aimed to explore the molecular mechanism and regulatory network of Linc00511 in LUAD and to identify new potential therapeutic targets for LUAD.

Methods

Real-time quantitative polymerase chain reaction (RT–qPCR) was performed to determine the relative Linc00511 levels in LUAD tissues and cells. The proliferation, apoptosis, migration, and invasion abilities of LUAD cells were assessed by a Cell Counting Kit-8 (CCK-8) assay, a colony formation assay, flow cytometry, and a Transwell assay. Changes in hsa_miR-126-5p, hsa_miR-218-5p, and COL1A1 expression were analyzed using western blotting and RT–qPCR. Targeted binding between miR-126-5p/miR-218-5p and Linc00511 or COL1A1 was verified with a luciferase reporter system and confirmed by an RNA pulldown assay. The participation of the PI3K/AKT signaling pathway was confirmed via western blotting. Xenograft animal experiments were performed to detect the impact of Linc00511 on LUAD tumor growth in vivo.

Results

In the present work, we observed that Linc00511 was upregulated in LUAD tissues and cells. Loss/gain-of-function experiments indicated that knockdown of Linc00511 significantly inhibited LUAD cell proliferation, migration and invasion and promoted LUAD cell apoptosis, whereas overexpression of Linc00511 showed the opposite effects. In addition, we determined that Linc00511 promoted COL1A1-mediated cell proliferation and cell motility by sponging miR-126-5p and miR-218-5p. Moreover, Linc00511 activated the PI3K/AKT signaling pathway through upregulation of COL1A1. Finally, silencing of Linc00511 inhibited LUAD tumor growth in vivo.

Conclusions

Linc00511 acts as a competing endogenous RNA to regulate COL1A1 by targeting miR-126-5p and miR-218-5p, thereby promoting the proliferation and invasion of LUAD cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02070-3.

Long Noncoding RNA TUG1 Inhibits Tumor Progression through Regulating Siglec-15-Related Anti-Immune Activity in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death, and its biology remains poorly understood, especially in regards to the immunosuppression induced by immune checkpoints, such as Siglec-15. Most cancer treatments composed of immune checkpoint inhibitors and oncogene-targeted drugs display a better therapeutic effect in the clinic, including tumor progression inhibition and immunosuppression breaks. However, two or more drugs will result in a greater possibility of adverse effects. Thus, a double-function target is necessary for developing antitumor drugs, such as RNAi therapy.

Methods

The expression of TUG1, Siglec-15, and miRNAs was evaluated by qPCR, and protein expression was analyzed by western blotting. The immune responses were evaluated by a Jurkat-reporter gene assay, a T cell-induced cytotoxicity assay, and IFN-γ/IL-2 release. The interactions among TUG1, Siglec-15, and miRNAs were verified by dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays. CCK-8 and Transwell assays were used to determine tumor cell proliferation, migration, and invasion.

Results

In HCC patients and cells, increased TUG1 levels were observed, positively regulating Siglec-15 expression. TUG1-induced Siglec-15 upregulation resulted in the suppression of the immune response of HCC cells. hsa-miR-582-5p directly targeted TUG1 and Siglec-15 mRNA, and ihsa-miR-582-5p knockout prevented the regulation of Siglec-15 induced by THU1. Changes in hsa-miR-582-5p expression negatively regulated Siglec-15 levels and immunosuppression but had no influence on TUG1 levels. siRNA knockdown of TUG1 effectively led to tumor progression inhibition and immune response improvement in HCC cells both in vitro and in vivo.

Conclusion

TUG1 increases the Siglec-15 level in HCC cells as a sponge to hsa-miR-582-5p, resulting in enhanced immunosuppression. TUG1 knockdown induced by siRNA not only reduces immunosuppression but also suppresses tumor progression both in vitro and in vivo. These novel findings may provide a potential and appropriate target for RNAi therapy to develop drugs with dual antitumor activity.

Solamargine inhibits the growth of hepatocellular carcinoma and enhances the anticancer effect of sorafenib by regulating HOTTIP-TUG1/miR-4726-5p/MUC1 pathway

Hepatocellular carcinoma (HCC) is one of the most common primary malignancies. Drug resistance has significantly prevented the clinical application of sorafenib (SF), a first‐line targeted medicine for the treatment of HCC. Solamargine (SM), a natural alkaloid, has shown potential antitumor activity, but studies about antitumor effect of SM are obviously insufficient in HCC. In the present study, we found that SM significantly inhibited the growth of HCC and enhanced the anticancer effect of SF. In brief, SM significantly inhibited the growth of HepG2 and Huh‐7 cells. The combination of SM and SF showed a synergistic antitumor effect. Mechanistically, SM downregulated the expression of long noncoding RNA HOTTIP and TUG1, followed by increasing the expression of miR‐4726‐5p. Moreover, miR‐4726‐5p directly bound to the 3′‐UTR region of MUC1 and decreased the expression of MUC1 protein. Overexpression of MUC1 partially reversed the inhibitory effect of SM on HepG2 and Huh‐7 cells viability, which suggested that MUC1 may be the key target in SM‐induced growth inhibition of HCC. More importantly, the combination of SM and SF synergistically restrained the expression of MUC1 protein. Taken together, our study revealed that SM inhibited the growth of HCC and enhanced the anticancer effect of SF through HOTTIP‐TUG1/miR‐4726‐5p/MUC1 signaling pathway. These findings will provide potential therapeutic targets and strategies for the treatment of HCC.

Non-coding RNAs as biomarkers for hepatocellular carcinoma-A systematic review

Hepatocellular carcinoma (HCC) is the sixth most common malignancy in the world and the fourth leading cause of cancer-related death, and its incidence is increasing globally. Despite significant advances in treatment strategies for HCC, the prognosis is still poor due to its high recurrence rate. Therefore, there is an urgent need to understand the pathogenesis of HCC and further develop new therapies to improve the prognosis and quality of life of HCC patients. MicroRNAs (miRNAs, miRs) are small non-coding RNAs involved in post-transcriptional regulation of gene expression that is abnormally expressed in cancer-associated genomic regions or vulnerable sites. More and more findings have shown that miRNAs are important regulatory factors of mRNA expression in HCC, and they are receiving more and more attention as a possible key biomarker of HCC. This review mainly summarizes the potential applied value on miRNAs as diagnostic, drug resistant, prognostic, and therapeutic biomarkers in the diagnosis, therapy, and prognosis of HCC. Also, we summarize the research value of long non-coding RNA (lncRNAs), circular RNAs (circRNAs), and miRNAs network in HCC as novel biomarkers, aiming at providing some references for the therapy of HCC.

Snail Upregulates Transcription of FN, LEF, COX2, and COL1A1 in Hepatocellular Carcinoma: A General Model Established for Snail to Transactivate Mesenchymal Genes

SNA is one of the essential EMT transcriptional factors capable of suppressing epithelial maker while upregulating mesenchymal markers. However, the mechanisms for SNA to transactivate mesenchymal markers was not well elucidated. Recently, we demonstrated that SNA collaborates with EGR1 and SP1 to directly upregulate MMP9 and ZEB1. Remarkably, a SNA-binding motif (TCACA) upstream of EGR/SP1 overlapping region on promoters was identified. Herein, we examined whether four other mesenchymal markers, lymphoid enhancer-binding factor (LEF), fibronectin (FN), cyclooxygenase 2 (COX2), and collagen type alpha I (COL1A1) are upregulated by SNA in a similar fashion. Expectedly, SNA is essential for expression of these mesenchymal genes. By deletion mapping and site directed mutagenesis coupled with dual luciferase promoter assay, SNA-binding motif and EGR1/SP1 overlapping region are required for TPA-induced transcription of LEF, FN, COX2 and COL1A1. Consistently, TPA induced binding of SNA and EGR1/SP1 on relevant promoter regions of these mesenchymal genes using ChIP and EMSA. Thus far, we found six of the mesenchymal genes are transcriptionally upregulated by SNA in the same fashion. Moreover, comprehensive screening revealed similar sequence architectures on promoter regions of other SNA-upregulated mesenchymal markers, suggesting that a general model for SNA-upregulated mesenchymal genes can be established.

LncRNATUG1 Facilitates Th2 Cell Differentiation by Targeting the miR-29c/B7-H3 Axis on Macrophages

The role of long non-coding RNAs (lncRNA) in asthma remains unclear. In this study, we examined the role of long non-coding RNA taurine upregulated 1 (lncRNA TUG1) in asthma. We found that lncRNA TUG1 is one of the differentially expressed lncRNAs in the monocytes of asthmatic children and is associated with Th cell differentiation. LncRNA TUG1 and miR-29c are mainly distributed in the cytoplasm of macrophages. Our data suggested that lncRNA TUG1 increased in macrophages stimulated by House Dust Mite in a dose-dependent manner. Using loss- and gain of function strategy, we found that miR-29c might regulate Th2 cell differentiation by directly targeting co-stimulatory molecule B7-H3. Furthermore, down-regulation of lncRNA TUG1 decreased the level of GATA3 in CD4+T cells and was associated with miR-29c/B7-H3 axis. Moreover, the dual-luciferase reporter assay confirmed that lncRNA TUG1 serves as a competing endogenous RNA to sponge miR-29c. According to the rescue experiment, lncRNA TUG1 regulated Th2 cell differentiation via miR-29c. These data suggest that lncRNA TUG1 in macrophages regulates Th2 cell differentiation via miR-29c/B7-H3 axis.

Role of long noncoding RNA taurine-upregulated gene 1 in cancers

Long non-coding RNAs (lncRNAs) are a group of non-protein coding RNAs with a length of more than 200 bp. The lncRNA taurine up-regulated gene 1 (TUG1) is abnormally expressed in many human malignant cancers, where it acts as a competitive endogenous RNA (ceRNA), regulating gene expression by specifically sponging its corresponding microRNAs. In the present review, we summarised the current understanding of the role of lncRNA TUG1 in cancer cell proliferation, metastasis, angiogenesis, chemotherapeutic drug resistance, radiosensitivity, cell regulation, and cell glycolysis, as well as highlighting its potential application as a clinical biomarker or therapeutic target for malignant cancer. This review provides the basis for new research directions for lncRNA TUG1 in cancer prevention, diagnosis, and treatment.

Long non-coding RNA TUG1/microRNA-187-3p/TESC axis modulates progression of pituitary adenoma via regulating the NF-κB signaling pathway

The molecule mechanisms of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in human diseases have been broadly studied recently, therefore, our research aimed to assess the effect of lncRNA taurine upregulated gene 1 (TUG1)/miR-187-3p/tescalcin (TESC) axis in pituitary adenoma (PA) by regulating the nuclear factor-kappa B (NF-κB) signaling pathway. We observed that TUG1 was upregulated in PA tissues and was associated with invasion, knosp grade and tumor size. TUG1 particularly bound to miR-187-3p. TUG1 knockdown inhibited cell proliferation, invasion, migration, and epithelial–mesenchymal transition, promoted apoptosis, and regulated the expression of NF-κB p65 and inhibitor of κB (IκB)-α in PA cells lines in vitro, and also inhibited tumor growth in vivo, and these effects were reversed by miR-187-3p reduction. Similarly, miR-187-3p elevation inhibited PA cell malignant behaviors and modulated the expression of NF-κB p65 and IκB-α in PA cells, and reduced in vivo tumor growth as well. TUG1 inhibition downregulated TESC, which was targeted by miR-187-3p. In conclusion, this study suggests that TUG1 sponges miR-187-3p to affect PA development by elevating TESC and regulating the NF-κB signaling pathway.