Long noncoding RNA TTN-AS1 enhances the malignant characteristics of osteosarcoma by acting as a competing endogenous RNA on microRNA-376a thereby upregulating dickkopf-1

Prognostic significance of long noncoding RNA TTN-AS1 in various malignancies

BACKGROUND

Increasing evidence has demonstrated that high TTN-AS1 expression is highly related to poor prognosis in diverse human cancers. However, the findings concerning the prognostic value of TTN-AS1 were inconsistent, as these conclusions were usually drawn with relatively small sample sizes. Hence, this meta-analysis proposes to investigate the prognostic significance of TTN-AS1 in multiple malignancies systematically.

METHODS

Web of Science, Springer, Embase, PubMed, Cochrane Library, and Scopus databases were comprehensively searched to retrieve studies related to the TTN-AS1 expression with the prognosis of malignancies. The significance of the TTN-AS1 in cancers was estimated by hazard ratios (HRs) or odds ratios (ORs). Additionally, the Gene Expression Profiling Interactive Analysis (GEPIA) analysis tool was used to strengthen our results further.

RESULTS

Twenty studies involving 17 different cancers and 1330 patients were recruited into this meta-analysis. The research revealed that high TTN-AS1 expression was remarkably associated with unfavorable overall survival (OS) (HR = 2.07, 95%CI [1.78, 2.41], p < .00001) when compared with low TTN-AS1 expression in malignancies. Additionally, elevated TTN-AS1 expression significantly contributed to lymph node metastasis (OR = 4.09, 95%CI [3.08, 5.44], p < .0001), larger tumor size (OR = 2.42, 95%CI [1.56, 3.77], p < .0001), worse tumor differentiation (OR = 0.36, 95%CI [0.22, 0.59], p < .0001) and more advanced tumor stage (OR = 0.29, 95%CI [0.22, 0.38], p < .0001) with low or no heterogeneity existing. Moreover, high TTN-AS1 expression  was connected with worse disease-free survival in five different cancers based on the GEPIA online database.

CONCLUSIONS

The results of this meta-analysis support that high TTN-AS1 expression significantly correlates with worse prognosis in various cancers. Therefore, TTN-AS1 may be considered as a novel biomarker for malignancies.

Retraction Note: Long non-coding RNA PTPRG-AS1 promotes cell tumorigenicity in epithelial ovarian cancer by decoying microRNA-545-3p and consequently enhancing HDAC4 expression

This article has been retracted. Please see the Retraction Notice for more detail: https://doi.org/10.1186/s13048-020-00723-7.

Single-Cell Profiling of Tumor Microenvironment Heterogeneity in Osteosarcoma Identifies a Highly Invasive Subcluster for Predicting Prognosis

Osteosarcoma is the most common malignant bone tumor in adolescents, and metastasis is the key reason for treatment failure and poor prognosis. Once metastasis occurs, the 5-year survival rate is only approximately 20%, and assessing and predicting the risk of osteosarcoma metastasis are still difficult tasks. In this study, cellular communication between tumor cells and nontumor cells was identified through comprehensive analysis of osteosarcoma single-cell RNA sequencing (scRNA-seq) and bulk RNA-seq data, illustrating the complex regulatory network in the osteosarcoma microenvironment. In line with the heterogeneity of osteosarcoma, we found subpopulations of osteosarcoma cells that highly expressed COL6A1, COL6A3 and MIF and were closely associated with lung metastasis. Then, BCDEG, a reliable risk regression model that could accurately assess the metastasis risk and prognosis of patients, was established, providing a new strategy for the diagnosis and treatment of osteosarcoma.

Long non-coding RNA titin-antisense RNA1 contributes to growth and metastasis of cholangiocarcinoma by suppressing microRNA-513a-5p to upregulate stratifin

Cholangiocarcinoma (CCA) is one of the most common histological types of primary hepatic malignancy and is associated with poor overall prognosis, causing a ponderous burden on human life. Hence, it is necessary to elucidate the pathogenesis of CCA. The objective of our research was to shed light on the mechanism through which long non-coding RNA titin-antisense RNA1 (lncRNA TTN-AS1) is involved in the development of CCA. Reverse transcription quantitative polymerase chain reaction was used to detect TTN-AS1 expression in CCA samples and cells. Functional experiments were performed using the Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine, transwell, and in vivo tumor growth assays. The relationship between TTN-AS1, miR-513a-5p, and stratifin (SFN) was explored using a dual luciferase reporter assay, RNA immunoprecipitation (RIP) experiment, and Pearson correlation analysis. The result showed that TTN-AS1 and SFN are highly expressed in CCA tissues. Bioinformatics analysis, luciferase reporter and RIP experiments revealed the correlation between TTN-AS1, miR-513a-5p, and SFN. In addition, silencing TTN-AS1 mitigated CCA cell proliferation and migration. Mechanistically, miR-513a-5p is sponged by TTN-AS1. The miR-513a-5p inhibitor abolished the effect of TTN-AS1 silencing on the aggressive behaviors of CCA cells. Furthermore, we showed that miR-513a-5p is a regulator of CCA by targeting SFN. TTN-AS1 induced CCA cell growth and metastasis via the miR-513a-5p/SFN pathway, which offers a new strategy for therapeutic interventions for CCA.

The pro-angiogenesis effect of miR33a-5p/Ets-1/DKK1 signaling in ox-LDL induced HUVECs

Objective: Angiogenesis is involved in multiple biological processes, including atherosclerosis (AS) and cancer. Dickkopf1 (DKK1) plays many roles in both tumors and AS and has emerged as a potential biomarker of cancer progression and prognosis. Targeting DKK1 is a good choice for oncological treatments. Many anticancer therapies are associated with specific cardiovascular toxicity. However, the effects of DKK1 neutralizing therapy on AS are unclear. We focused on how DKK1 affected angiogenesis in AS and ox-LDL-induced human umbilical vein endothelial cells (HUVECs).

Methods: ApoE-/- mice were fed a high-fat diet and then injected with DKK1i or DKK1 lentivirus to study the effects of DKK1. In vitro, promoter assays, protein analysis, database mining, dual-luciferase reporter assay (DLR), electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (ChIP), and coimmunoprecipitation (co-IP) were used to study the mechanism of DKK1 biogenesis. Cell migration and angiogenesis assays were performed to investigate the function and regulatory mechanisms of DKK1.

Results: DKK1 participated in angiogenesis both in the plaques of ApoE-/- mice by knockdown or overexpression of DKK1 and ox-LDL-induced HUVECs. DKK1 induced angiogenesis (increasing migration and capillary formation, inducing expression of VEGFR-2/VEGF-A/MMP) via the CKAP4/PI3K pathway, independent of Wnt/β-catenin. ox-LDL increased the expression and nuclear transfer of Ets-1 and c-jun, and induced the transcriptional activity of DKK1 in HUVECs. Ets-1, along with c-jun and CBP, could bind to the promoter of DKK1 and enhance DKK1 transcription. MiR33a-5p was downregulated in ox-LDL induced HUVECs and aortic artery of high-fat diet ApoE-/- mice. Ets-1 was a direct target of miR33a-5p. MiR33a-5p/Ets-1/ DKK1 axis contributed to angiogenesis.

Conclusions: MiR33a-5p/Ets-1/DKK1 signaling participated in ox-LDL-induced angiogenesis of HUVECs via the CKAP4/PI3K pathway. These new findings provide a rationale and notable method for tumor therapy and cardiovascular protection.

LncRNA TTN-AS1 acts as a tumor promoter in gallbladder carcinoma by regulating miR-107/HMGA1 axis

Background

The incidence of gallbladder carcinoma (GBM) in China has increased in recent years. Here, the functional mechanism of lncRNA TTN-AS1 in GBC was preliminary elucidated.

Methods

The expression levels of lncRNA TTN-AS1, miR-107, and HMGA1 in tissues and cell lines were assessed by RT-qPCR. Cell proliferation was measured by MTT assays. Cell invasion and migration abilities were evaluated by Transwell assays. The relationship between miR-107 and lncRNA TTN-AS1 or HMGA1 was confirmed by luciferase reporter assay.

Results

Upregulation of lncRNA TTN-AS1 and downregulation of miR-107 were detected in GBC. Furthermore, the expressions between TTN-AS1 and miR-107 were mutually inhibited in GBC. Functionally, lncRNA TTN-AS1 promoted cell viability and motility in GBC by sponging miR-107. In addition, miR-107 directly targets HMGA1. And HMGA1 can be positively regulated by lncRNA TTN-AS1 in GBC. Furthermore, HMGA1 promoted GBC progression by interacting with lncRNA TTN-AS1/miR-107 axis.

Conclusion

LncRNA TTN-AS1 acted as a tumor promoter in GBC by sponging miR-107 and upregulating HMGA1.

Silencing of the Long Non-Coding RNA TTN-AS1 Attenuates the Malignant Progression of Osteosarcoma Cells by Regulating the miR-16-1-3p/TFAP4 Axis

Objectives

Osteosarcoma (OS) is a type of bone malignancy. This study attempted to explore the effect of long non-coding RNA TTN-AS1 (TTN-AS1) on OS and to determine its molecular mechanisms.

Methods

The expression of TTN-AS1, microRNA-16-1-3p (miR-16-1-3p), and transcription factor activating enhancer binding protein 4 (TFAP4) in OS was assessed using qRT-PCR. The OS cell proliferation, migration, and invasion were measured using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), wound-healing, and transwell assays. N-cadherin and MMP-2 protein level was determined with western blot. Interactions between TTN-AS1 and miR-16-1-3p or TFAP4 and miR-16-1-3p were confirmed using the dual-luciferase reporter assay. Additionally, an OS xenograft tumor model was constructed to assess the effect of TTN-AS1 on tumor growth.

Results

TTN-AS1 and TFAP4 expression was increased in OS, while miR-16-1-3p expression was decreased. TTN-AS1 silencing restrained OS cell proliferation, migration, invasion, N-cadherin and MMP-2 protein expression, and hindered tumor growth. MiR-16-1-3p overexpression retarded the malignant behavior of OS cells. TTN-AS1 played a carcinostatic role by down-regulating miR-16-1-3p in the OS cells. Moreover, miR-16-1-3p inhibition or TFAP4 elevation weakened the suppressive effect of TTN-AS1 silencing on OS cell tumor progression.

Conclusion

TTN-AS1 promoted the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of OS cells via mediating the miR-16-1-3p/TFAP4 axis. TTN-AS1 may be a critical target for improving OS.

TTN-AS1 as a potential diagnostic and prognostic biomarker for multiple cancers

The long noncoding RNAs (lncRNAs) are non-coding RNAs that are more than 200 nucleotides in length, and one of several types of non-coding RNAs (ncRNAs). The lncRNAs function in diverse biological processes in normal cells, such as cellular differentiation and cell cycle regulation. There is also evidence that some aberrantly regulated lncRNAs function as oncogenes or tumor suppressor genes in various cancers. For example, TTN-AS1 is a lncRNA that binds to titin mRNA (TTN) and has pro-oncogenic effects in many cancers. Overexpression of TTN-AS1 correlates with poor prognosis in breast cancer, lung cancer, digestive system neoplasms, reproductive system cancers, and other cancers. Furthermore, increased TTN-AS1 expression correlates with more advanced pathology and tumor malignancy. In this review, we comprehensively summarize recent studies on the molecular mechanisms of TTN-AS1 regulation and the role of TTN-AS1 in the carcinogenesis and progression of numerous tumors.

Diagnosis Accuracy and Prognostic Significance of the Dickkopf-1 Protein in Gastrointestinal Carcinomas: Systematic Review and Network Meta-analysis

Objective: To evaluate the diagnosis accuracy and prognostic significance of bio-marker dickkopf-1(DKK-1) protein in GIC, and also sub-type of hepatocellular carcinoma (HCC), pancreas carcinomas (PC), oesophageal carcinoma (EPC) and Adenocarcinoma of esophago-gastric junction (AEGJ), etc.

Methods: Electronic databases were searched from inception to May 2020. Patients were diagnosed with gastrointestinal carcinomas, and provided data on the correlation between high and low DKK-1 expression and diagnosis or prognosis.

Results: Forty-three publications involving 9318 participants were included in the network meta-analysis, with 31 of them providing data for diagnosis value and 18 records were eligible for providing prognosis value of DKK-1. DKK-1 has a moderate diagnostic value for overall GIC, HCC and PC. In addition, for the combined diagnosis value of DKK-1 +AFP, high diagnostic accuracy value could be determined in HCC and early HCC group, respectively. Whereas, diagnosis efficiency of DKK-1+CA19-9 was also better than that of DKK-1 alone with AUC value is above 0.95. For the prognosis meta-analysis of histopathological stratification, we found that EPC and AEGJ ranked the best for the histopathological stratification of prognosis from network meta-analysis. This systematic review protocol was registered with the PROSPERO registry (No.CRD42020167910).

Conclusion: DKK-1 has good diagnostic accuracy, especially combination of DKK-1+AFP in HCC and DKK-1+CA19-9 in PC, whereas modest prognostic significant in GIC. Future head-to-head researches are warranted for DKK-1 expression in HCC and PC tissue.

An update on the roles of circular RNAs in osteosarcoma

Osteosarcoma is the most common primary bone malignancy and is a neoplasm thought to be derived from the bone‐forming mesenchymal stem cells. Aberrant activation of oncogenes and inactivation of tumour suppressor genes by somatic mutations and epigenetic mechanisms play a pivotal pathogenic role in osteosarcoma. Aside from alterations in these protein‐coding genes, it has now been realized that dysregulation of non‐coding RNAs (ncRNAs), including microRNAs (miRNAs), long non‐coding RNAs (lncRNAs) and the recently discovered circular RNAs (circRNAs), is crucial to the initiation and progression of osteosarcoma. CircRNAs are single‐stranded RNAs that form covalently closed loops and function as an important regulatory element of the genome through multiple machineries. Recently, an increasing number of studies suggested that circRNAs also played critical roles in osteosarcoma. This review summarizes recent development and progression in circRNA transcriptome analysis and their functions in the modulation of osteosarcoma progression.

lncRNA TTN‑AS1 upregulates RUNX1 to enhance glioma progression via sponging miR‑27b‑3p

Long non-coding RNAs (lncRNAs) contribute to the tumorigeneses of numerous types of cancer, including glioma. The present study was designed to unveil a novel lncRNA functioning in glioma and explore the underlying mechanisms. lncRNA titin-antisense RNA1 (TTN-AS1), miR-27b-3p and Runt-related transcription factor 1 (RUNX1) expression in glioma tissues and cell lines was estimated by RT-qPCR. Si-TTN-AS1 was transfected into glioma cell lines (U251 and LN229), and CCK-8 assay, flow cytometry, wound healing and Transwell assays were applied to estimate the function of TTN-AS1 in glioma cells. miR-27b-3p inhibitor was used to explore the mechanisms. The results revealed that TTN-AS1 was highly expressed in glioma specimens and cell lines. Downregulation of TTN-AS1 inhibited the proliferation, migration and invasion of the glioma cells, as well as increased the rate of apoptosis. In vivo, the tumor growth was also inhibited by TTN-AS1 depletion in nude mice. Furthermore, we revealed that TTN-AS1 exerted oncogenic effects via sponging miR-27b-3p and thereby positively regulating RUNX1 expression. In conclusion, the present study supported that TTN-AS1 acts as an oncogene in glioma by targeting miR-27b-3p to release RUNX1. This finding may contribute to gene therapy of glioma.

LncRNA TTN-AS1 acts as sponge for miR-15b-5p to regulate FBXW7 expression in ovarian cancer

Emerging evidence showed that long noncoding RNA (lncRNA) plays crucial roles in regulating various cancer biological behaviors. Titin-antisense RNA1 (TTN-AS1) has been reported to have crucial roles in cancers but its role in ovarian cancer remains unknown. The levels of TTN-AS1, microNRA-15b-5p (miR-15b-5p), and F-box and WD repeat domain containing 7 (FBXW7) in ovarian cancer cells were measured by quantitative reverse-transcription PCR. Targets for TTN-AS1 and miR-15b-5p were predicted by bioinformatic tools, and validated by luciferase activity reporter assay. Cell proliferation, colony formation, and cell apoptosis were analyzed with cell counting kit-8 assay, colony formation assay, and flow cytometry. Correlation of TTN-AS1 and FBXW7 was analyzed at gene expression profiling interactive analysis. TTN-AS1 was found decreased expression in ovarian cancer tissues and cells. Dual-luciferase activity validated TTN-AS1 and FBXW7 shared binding site in miR-15b-5p. Functional assays showed TTN-AS1 overexpression inhibits ovarian cancer cell proliferation, colony formation but promotes apoptosis. Rescue experiments showed that knockdown of FBXW7 could partially counteracted the effects of TTN-AS1 overexpression on ovarian cancer cell behaviors. Our results indicated that the TTN-AS1/miR-15b-5p/FBXW7 axis identified in this work could help to identify treatment biomarkers for ovarian cancer.

DDX11-AS1 contributes to osteosarcoma progression via stabilizing DDX11

Increasing evidence has uncovered that long noncoding RNAs (lncRNAs) play extremely important roles in numerous steps of gene regulation concerning the progression of tumors. Defined as a kind of lncRNA, DDX11-AS1 has been considered to be closely related to the tumorigenesis of malignancies. Nevertheless, the underlying regulatory role of it in osteosarcoma remains to be analyzed and elucidated. In this research, a dramatically upregulated expression of DDX11-AS1 was detected in osteosarcoma cells. Loss-of-function assays revealed that decreased expression of DDX11-AS1 impaired osteosarcoma cell proliferation, metastasis as well as epithelial-mesenchymal transition (EMT) process. Afterwards, molecular mechanism tests validated that DDX11-AS1 could sponge miR-873-5p to upregulate DDX11 expression in osteosarcoma. Additionally, functional tests delineated that upregulation of miR-873-5p inhibited cell proliferation, metastasis as well as EMT process in osteosarcoma progression. Further, DDX11-AS1 was verified to regulate the mRNA stability of DDX11 through binding with IGF2BP2 in osteosarcoma. Final rescue tests in vitro and in vivo further elucidated that DDX11 overexpression could reversed the DDX11-AS1 downregulation-mediated effect on osteosarcoma progression. To sum up, DDX11-AS1 contributes to osteosarcoma progression via stabilizing DDX11.

CircAGFG1 promotes cervical cancer progression via miR-370-3p/RAF1 signaling

Background

In past decades, circular RNAs (circRNAs) have achieved increasing attention because of its regulatory role in different kinds of cancers. However, how circAGFG1 regulates cervical cancer (CC) is still largely undiscovered. This study aims to evaluate the role of a novel circRNAs and related molecular mechanism in CC cells.

Methods

High or low level of circAGFG1 was detected in CC cells or normal cell line with qRT-PCR. The proliferative and migratory abilities of CC cells were assessed with loss-of function assays. The downstream miRNA and mRNA of circAGFG1 were searched out and proved by using bioinformatics analysis and mechanism experiments. Recue assays were designed to confirm the role of circAGFG1/miR-370-3p/RAF1 axis in CC cell activities.

Results

The levels of circAGFG1 was abundant in CC cells in comparison with normal cervical cell End1/E6E7. The inhibitory effect of decreased circAGFG1 level on the proliferative and migratory abilities of CC cells was assessed. CircAGFG1 and miR-370-3p were localized in the cytoplasm and they can interact with each other. Moreover, miR-370-3p was downregulated in CC cells. We also determined the negative effect of miR-370-3p on RAF1. CircAGFG1 could promote RAF1 expression by absorbing miR-370-3p, thereby activating RAF/MEK/ERK pathway. circAGFG1 promoted proliferation and migration of CC cells via enhancing the activity of RAF/MEK/ERK pathway by sponging miR-370-3p and further regulating RAF1.

Conclusion

The results of this study provided new evidence that circAGFG1 acted as a vital regulator in cervical cancer proliferation and migration, giving great promise to apply it as a potential biomarker for diagnosis and therapy in CC treatment.