lncRNA NR2F1‐AS1 promotes breast cancer angiogenesis through activating IGF‐1/IGF‐1R/ERK pathway

Long non‐coding RNAs (lncRNAs) take various effects in cancer mostly through sponging with microRNAs (miRNAs). lncRNA NR2F1‐AS1 is found to promote tumour progression in hepatocellular carcinoma, endometrial cancer and thyroid cancer. However, the role of lncRNA NR2F1‐AS1 in breast cancer angiogenesis remains unknown. In this study, we found lncRNA NR2F1‐AS1 was positively related with CD31 and CD34 in breast cancer through Pearson's correlation analysis, while lncRNA NR2F1‐AS1 transfection promoted human umbilical vascular endothelial cell (HUVEC) tube formation. In breast cancer cells, lncRNA NR2F1‐AS1 enhanced the HUVEC proliferation, tube formation and migration ability through tumour‐conditioned medium (TCM). In zebrafish model, lncRNA NR2F1‐AS1 increased the breast cancer cell‐related neo‐vasculature and subsequently promoted the breast cancer cell metastasis. In mouse model, lncRNA NR2F1‐AS1 promoted the tumour vessel formation, increased the micro vessel density (MVD) and then induced the growth of primary tumour. Mechanically, lncRNA NR2F1‐AS1 increased insulin‐like growth factor‐1 (IGF‐1) expression through sponging miRNA‐338‐3p in breast cancer cells and then activated the receptor of IGF‐1 (IGF‐1R) and extracellular signal‐regulated kinase (ERK) pathway in HUVECs. These results indicated that lncRNA NR2F1‐AS1 could promote breast cancer angiogenesis through IGF‐1/IGF‐1R/ERK pathway.     

LBX2-AS1 promotes ovarian cancer progression by facilitating E2F2 gene expression via miR-455-5p and miR-491-5p sponging

LBX2-AS1 is a long non-coding RNA that facilitates the development of gastrointestinal cancers and lung cancer, but its participation in ovarian cancer development remained uninvestigated. Clinical data retrieved from TCGA ovarian cancer database and the clinography of 60 ovarian cancer patients who received anti-cancer treatment in our facility were analysed. The overall cell growth, colony formation, migration, invasion, apoptosis and tumour formation on nude mice of ovarian cancer cells were evaluated before and after lentiviral-based LBX2-AS1 knockdown. ENCORI platform was used to explore LBX2-AS1-interacting microRNAs and target genes of the candidate microRNAs. Luciferase reporter gene assay and RNA pulldown assay were used to verify the putative miRNA-RNA interactions. Ovarian cancer tissue specimens showed significant higher LBX2-AS1 expression levels that non-cancerous counterparts. High expression level of LBX2-AS1 was significantly associated with reduced overall survival of patients. LBX2-AS1 knockdown significantly down-regulated the cell growth, colony formation, migration, invasion and tumour formation capacity of ovarian cancer cells and increased their apoptosis in vitro. LBX2-AS1 interacts with and thus inhibits the function of miR-455-5p and miR-491-5p, both of which restrained the expression of E2F2 gene in ovarian cancer cells via mRNA targeting. Transfection of miRNA inhibitors of these two miRNAs or forced expression of E2F2 counteracted the effect of LBX2-AS1 knockdown on ovarian cancer cells. LBX2-AS1 was a novel cancer-promoting lncRNA in ovarian cancer. This lncRNA increased the cell growth, survival, migration, invasion and tumour formation of ovarian cancer cells by inhibiting miR-455-5p and miR-491-5p, thus liberating the expression of E2F2 cancer-promoting gene.     

LncRNA CRNDE promotes the progression and angiogenesis of pancreatic cancer via miR-451a/CDKN2D axis

BackgroundThe lncRNA colorectal neoplasia differentially expressed (lncRNA CRNDE) has been reported to play a pivotal role in various cancers. However, the expression and function of CRNDE in pancreatic cancer remain unclear. The objective of this study was to investigate the effects of CRNDE on pancreatic cancer and the underlying mechanisms.MethodsThe expression of CRNDE in pancreatic cancer tissues and cell lines was determined by RT-qPCR. Proliferation and angiogenesis were detected by MTT, colony formation, transwell and tube formation assays in vitro and in vivo. ELISA assay was used to detect the secretion of VEGFA. IHC was performed to test the expression levels of Ki67 and CD31. The binding sites between CRNDE, CDKN2D and miR-451a were predicted by bioinformatics analysis. Dual luciferase reporter and RNA immunoprecipitation assays were conducted to confirm the interaction with each other.ResultsThe results showed that CRNDE was significantly up-regulated in pancreatic cancer tissues as well as cell lines. CRNDE overexpression promoted the progression and angiogenesis of pancreatic cancer cells in vitro and in vivo. Moreover, we identified that CRNDE functioned as a sponge for miR-451a and CRNDE overexpression inhibited the expression of miR-451a. Furthermore, we confirmed that miR-451a directly interacted with CDKN2D and negatively regulated CDKN2D expression. In addition, CRNDE was found to positively regulate CDKN2D expression and mediate pancreatic cancer cell proliferation and angiogenesis through miR-451a/CDKN2D axis.ConclusionCRNDE modulates cell proliferation and angiogenesis via miR-451a/CDKN2D axis in pancreatic cancer, which provides a potential therapeutic target for pancreatic cancer treatment.     

EYA4 serves as a prognostic biomarker in hepatocellular carcinoma and suppresses tumour angiogenesis and metastasis

Eye absent homolog 4 (EYA4) has been demonstrated to be down‐regulated in hepatocellular carcinoma (HCC), but its biological function and the mechanism in HCC angiogenesis and metastasis remain largely unknown. Herein, we showed that EYA4 expression was frequently low in HCC tissue samples compared with matched adjacent non‐tumourous tissues. In the analysis of 302 HCC specimens, we revealed that decreased expression of EYA4 correlated with tumour differentiation status. Univariate and multivariate analyses identified EYA4 as an independent risk factor for recurrence‐free survival (RFS) and overall survival (OS) among the 302 patients. Functional assays showed that forced expression of EYA4 suppressed HCC cell migration, invasion and capillary tube formation of endothelial cells in vitro, as well as in vivo tumour angiogenesis and metastasis in a mouse model. Furthermore, mechanism study exhibited that EYA4 could inhibit HCC angiogenesis and metastasis by inhibiting c‐JUN/VEGFA pathway. Together, we provide proof that EYA4 is a novel tumour suppressor in HCC and a new prognostic biomarker and therapeutic target in HCC.     

Long non‐coding RNA H19 is responsible for the progression of lung adenocarcinoma by mediating methylation‐dependent repression of CDH1 promoter

Lung adenocarcinoma is a common histologic type of lung cancer with a high death rate globally. Increasing evidence shows that long non‐coding RNA H19 (lncRNA H19) and CDH1 methylation are involved in multiple tumours. Here, we tried to investigate whether lncRNA H19 or CDH1 methylation could affect the development of lung adenocarcinoma. First, lung adenocarcinoma tissues were collected to detect CDH1 methylation. Then, the regulatory mechanisms of lncRNA H19 were detected mainly in concert with the treatment of overexpression of lncRNA H19, siRNA against lncRNA H19, overexpression of CDH1 and demethylating agent A‐5az in lung adenocarcinoma A549 cell. The expression of lncRNA H19 and epithelial‐mesenchymal transition (EMT)‐related factors as well as cell proliferation, sphere‐forming ability, apoptosis, migration and invasion were detected. Finally, we observed xenograft tumour in nude mice so as to ascertain tumorigenicity of lung adenocarcinoma cells. LncRNA H19 and methylation of CDH1 were highly expressed in lung adenocarcinoma tissues. A549 cells with silencing of lncRNA H19, overexpression of CDH1 or reduced CDH1 methylation by demethylating agent 5‐Az had suppressed cell proliferation, sphere‐forming ability, apoptosis, migration and invasion, in addition to inhibited EMT process. Silencing lncRNA H19 could reduce methylation level of CDH1. In vivo, A549 cells with silencing lncRNA H19, overexpression of CDH1 or reduced CDH1 methylation exhibited low tumorigenicity, reflected by the smaller tumour size and lighter tumour weight. Taken together, this study demonstrates that silencing of lncRNA H19 inhibits EMT and proliferation while promoting apoptosis of lung adenocarcinoma cells by inhibiting methylation of CDH1 promoter.     

LncRNA POU3F3 promotes proliferation and inhibits apoptosis of cancer cells in triple-negative breast cancer by inactivating caspase 9

It has been reported that lncRNA POU3F3 was upregulated in esophageal squamous-cell carcinomas, indicating its role as an oncogene in this disease. However, the mechanism of its function and its involvement in other malignancies is unknown. In the present study we found that expression levels of lncRNA POU3F3 were higher in tumor tissues than in adjacent healthy tissues of triple negative breast cancer (TNBC) patients and were significantly and inversely correlated with levels of cleaved caspase 9 only in tumor tissues. In addition, plasma levels of lncRNA POU3F3 were higher in TNBC patients than in healthy controls and were significantly and inversely correlated with levels of cleaved caspase 9 only in TNBC patients. In addition, treatment of exogenous Cleaved Caspase-9 significantly attenuated the effects of lncRNA POU3F3 overexpression on cancer cell proliferation and apoptosis. lncRNA POU3F3 may promote proliferation and inhibit apoptosis of cancer cells in triple-negative breast cancer.     

Aquaporin‐1 inhibition reduces metastatic formation in a mouse model of melanoma

Aquaporin‐1 (AQP1) is a proangiogenic water channel protein promoting endothelial cell migration. We previously reported that AQP1 silencing by RNA interference reduces angiogenesis‐dependent primary tumour growth in a mouse model of melanoma. In this study, we tested the hypothesis that AQP1 inhibition also affects animal survival and lung nodule formation. Melanoma was induced by injecting B16F10 cells into the back of C57BL6J mice. Intratumoural injection of AQP1 siRNA and CTRL siRNA was performed 10 days after tumour cell implantation. Lung nodule formation was analysed after the death of the mice. Western blot was used to quantify HIF‐1α, caspase‐3 (CASP3) and metalloproteinase‐2 (MMP2) protein levels. We found that AQP1 knock‐down (KD) strongly inhibited metastatic lung nodule formation. Moreover, AQP1 siRNA‐treated mice showed a twofold survival advantage compared to mice receiving CTRL siRNAs. The reduced AQP1‐dependent tumour angiogenesis caused a hypoxic condition, evaluated by HIF‐1α significant increase, in turn causing an increased level of apoptosis in AQP1 KD tumours, assessed by CASP3 quantification and DNA fragmentation. Importantly, a decreased level of MMP2 after AQP1 KD indicated a decreased activity against extracellular matrix associated with reduced vascularization and metastatic formation. In conclusion, these findings highlight an additional role for AQP1 as an important determinant of tumour dissemination by facilitating tumour cell extravasation and metastatic formation. This study adds knowledge on the role played by AQP1 in tumour biology and supports the view of AQP1 as a potential drug target for cancer therapy.     

Vascular endothelial growth factor A is a potential prognostic biomarker and correlates with immune cell infiltration in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related deaths among cancer patients. Vascular endothelial growth factor A (VEGFA) is involved in regulating biological processes, such as angiogenesis and vascular permeability, and is very closely related to the pathogenesis of various tumours, especially vascular-rich, solid tumours. Clinical data of patients with HCC and other tumours were analysed through public databases, such as the TCGA database, Gene Expression Omnibus database, Human Protein Atlas database, STRING, Tumour Immune Estimation Resource and Kaplan–Meier Plotter. The tumour tissues and adjacent normal tissues of patients with HCC from Hunan Provincial People's Hospital were collected to verify the expression of VEGFA by immunohistochemistry, immunofluorescence, Western blotting and qPCR. VEGFA expression is elevated in multiple tumour types and correlates with the prognosis of tumour patients. VEGFA is involved in regulating the tumour microenvironment and immune cell function in tumour development. Inhibition of VEGFA reduces proliferation, invasion, and migration and promotes apoptosis in HCC cells. VEGFA is a potential predictive biomarker for the diagnosis and prognosis of HCC.     

LncRNA CASC2 inhibits proliferation and migration of adenocarcinoma cells via miR-4735-3p and mTOR

Lung adenocarcinoma is a major form of non–small-cell lung cancer that frequently strikes nonsmokers. The disease is often diagnosed at a late stage and the 5-year survival rate is very low. Although previous studies found many somatic alterations associated with lung adenocarcinoma, the molecular basis of the development and progression of the disease is not well understood. We found that long noncoding RNA (lncRNA) cancer susceptibility candidate 2 (CASC2), a putative tumor suppressor, was downregulated in both patient adenocarcinoma tissues and cultured lung cancer cells. Its tumor suppression function seemed to be dependent on its binding to miR-4735-5p. Changing the levels of CASC2 and miR-4735-3p in the cultured adenocarcinoma cells could affect the malignant phenotypes as well as growth of tumors derived from the cells injected into nude mice. Furthermore, the lncRNA and miR-4735-3p interplay likely the suppressed tumor growth through the downstream mammalian target of rapamycin signaling pathway. The results have revealed molecular details that may be critical for the development of lung adenocarcinoma, opening opportunities for the development of novel, and therapeutic tools.     

A novel lncRNA PLK4 up‐regulated by talazoparib represses hepatocellular carcinoma progression by promoting YAP‐mediated cell senescence

A growing number of studies recognize that long non‐coding RNAs (lncRNAs) are essential to mediate multiple tumorigenic processes, including hepatic tumorigenesis. However, the pathological mechanism of lncRNA‐regulated liver cancer cell growth remains poorly understood. In this study, we identified a novel function lncRNA, named polo‐like kinase 4 associated lncRNA (lncRNA PLK4, GenBank Accession No. RP11‐50D9.3), whose expression was dramatically down‐regulated in hepatocellular carcinoma (HCC) tissues and cells. Interestingly, talazoparib, a novel and highly potent poly‐ADP‐ribose polymerase 1/2 (PARP1/2) inhibitor, could increase lncRNA PLK4 expression in HepG2 cells. Importantly, we showed that talazoparib‐induced lncRNA PLK4 could function as a tumour suppressor gene by Yes‐associated protein (YAP) inactivation and induction of cellular senescence to inhibit liver cancer cell viability and growth. In summary, our findings reveal the molecular mechanism of talazoparib‐induced anti‐tumor effect, and suggest a potential clinical use of talazoparib‐targeted lncRNA PLK4/YAP‐dependent cellular senescence for the treatment of HCC.     

LncRNA HSPC324 plays role in lung development and tumorigenesis

Lung cancer is a leading cause of cancer-related death in the world. Therefore, identifying the genes and molecular pathways involved in lung development and tumorigenesis can help us improve the therapeutic strategies of lung cancer. Accumulating evidence confirms that long noncoding RNAs, as a novel layer of regulatory RNA molecules, play an important role in various aspects of the cells. Here, using available high throughput gene expression data, we identified an lncRNA (HSPC324) with high expression level in lung tissue that is distinctly expressed in lung tumor tissues relative to normal. Using GO enrichment and KEGG pathway analyses, we further analyzed the functions and pathways involving the HSPC324-correlated genes. Ectopic expression of lncRNA HSPC324 significantly inhibited proliferation, cell cycle and migration; on the other hand, increased apoptosis and ROS production in lung adenocarcinoma cells. Overall, this study introduces HSPC324 as a new player in the development of lung cancer.     

Colon cancer metastasis in mouse liver is not affected by hypercoagulability due to Factor V Leiden mutation

Clinical trials have shown life-prolonging effects of antithrombotics in cancer patients, but the molecular mechanisms remain unknown due to the multitude of their effects. We investigated in a mouse model whether one of the targets of antithrombotic therapy, fibrin deposition, stimulates tumour development. Fibrin may provide either protection of cancer cells in the circulation against mechanical stress and the immune system, or form a matrix for tumours and/or angiogenesis in tumours to develop. Mice homozygous for Factor V Leiden (FVL), a mutation in one of the coagulation factors that facilitates fibrin formation, were used to investigate whether hypercoagulability affects tumour development in an experimental metastasis model. Liver metastases of colon cancer were induced in mice with the FVL mutation and wild-type littermates. At day 21, number and size of tumours at the liver surface, fibrin/fibrinogen distribution, vessel density and the presence of newly formed vessels in tumours were analysed. Number and size of tumours did not differ between mice with and without the FVL mutation. Fibrin/fibrinogen was found in the cytoplasm of hepatocytes and cancer cells, in blood vessels in liver and tumour tissue and diffusely distributed outside vessels in tumours, indicating leaky vessels. Vessel density and angiogenesis varied widely between tumours, but a pre-dominance for vessel-rich or vessel-poor tumours or vessel formation could not be found in either genotype. In conclusion, the FVL mutation has no effect on the development of secondary tumours of colon cancer in livers of mice. Fibrin deposition and thus inhibition of fibrin formation by anticoagulants do not seem to affect tumour development in this model.     

Enhanced metastasis in RNF13 knockout mice is mediated by a reduction in GM-CSF levels

RING finger protein 13 (RNF13) is a novel E3 ubiquitin ligase whose expression is associated with cancer development. However, its specific role in cancer progression and metastasis remains unclear. Here, a B16F10/LLC experimental pulmonary metastatic model was developed to examine the formation of metastatic foci in the lung. A greater number of tumor colonies were observed in the lungs of RNF13-knockout (KO) mice than in their wild-type (WT) littermates, whereas no significant differences in tumor size were observed between the two groups. In short-term experiments, the number of fluorescently-labeled B16F10 cells increased remarkably in RNF13-KO lungs at early time points, whereas clearance of tumor cells from the blood was not affected. These results indicated that RNF13 may inhibit the colonization of B16F10 cells in the lung. Assessment of the concentration of various cytokines in tumor bearing lungs and blood did not detect significant differences between the blood of RNF13-KO and WT mice; however the levels of GM-CSF were significantly reduced in RNF13-KO tumor bearing lungs, which may have guided more B16F10 cells to migrate to the lungs. This was confirmed by lower GM-CSF concentrations in conditioned media from the culture of RNF13-KO lung slices. Collectively, our results suggest that host RNF13 affects the concentration of GM-CSF in tumor-bearing lungs, leading to a reduction in the colonization of metastatic tumor cells in the lung.     

SNAIL Induces EMT and Lung Metastasis of Tumours Secreting CXCL2 to Promote the Invasion of M2-Type Immunosuppressed Macrophages in Colorectal Cancer

Background: There is increasing evidence that tumour-associated macrophages (TAMs) are critical in the formation of lung metastases. However, the molecular mechanisms of tumour interactions with TAMs via EMT are largely unknown.Methods: The mechanism of lung metastasis was studied in patient tissues. The mechanism of SNAIL regulation of the interaction between mesenchymal cells and M2 macrophages was elucidated using coculture of M2 macrophages and Transwell assays in vitro and in vivo in nude mice and NOD-SCID mice.Results: We demonstrated for the first time that SNAIL and CXCL2 were abnormally overexpressed in colorectal cancer, especially lung metastasis, and were associated with poor prognosis in colorectal cancer patients. We demonstrated that SNAIL promoted the secretion of CXCL2 by mesenchymal cells and induced the activation of M2 macrophages. We found that CXCL2 attracted M2-type macrophages to infiltrate and promote tumour metastasis.Conclusion: These findings suggest that SNAIL promotes epithelial tumour transformation, and that transformed mesenchymal cells secrete CXCL2, which promotes M2 macrophage infiltration and tumour cell metastasis. These findings elucidate the tumour-TAM interaction in the metastatic microenvironment, which is mediated by tumour-derived CXCL2 and affects lung metastasis. This study also provides a theoretical basis for the occurrence of secondary lung cancer.     

Silencing of long noncoding RNA LEF1-AS1 prevents the progression of hepatocellular carcinoma via the crosstalk with microRNA-136-5p/WNK1

Long noncoding RNAs (lncRNAs) have been recognized as cancer-associated biological molecules, favoring hepatocellular carcinoma (HCC) progression. This study was conducted to elucidate the effects lncRNA lymphoid enhancer-binding Factor 1 antisense RNA (LEF1-AS1) on the pathological development of HCC, along with the crosstalk involving microRNA-136-5p (miR-136-5p) and with-no-K (lysine) kinase 1 (WNK1). The study recruited primary HCC tissues and their corresponding nonneoplastic liver tissues. The gain- and loss-of-function studies were performed in HCC cells HuH-7 and tumor xenografts in nude mice. The dual luciferase reporter gene assay system, RNA pull-down, and radioimmunoprecipitation assays were applied to detect their interactions among lncRNA LEF1-AS1, miR-136-5p, and WNK1. 5-Ethynyl-2′-deoxyuridine staining, scratch test, Transwell assays, and in vitro tube formation assays were conducted to examine HCC cell proliferation, migration, and invasion and HUVEC angiogenesis. HCC tissues and cells contained high lncRNA LEF1-AS1 expression. LncRNA LEF1-AS1 upregulation triggered markedly increased HCC cell proliferation, migration, and invasion and human umbilical vein endothelial cell angiogenesis. In vivo silencing lncRNA LEF1-AS1 resulted in reduced tumor cell vitality and matrix metalloproteinase-9 and the vascular endothelial growth factor expression. Additionally, the role of lncRNA LEF1-AS1 was found to be largely dependent on WNK1. Association of lncRNA LEF1-AS1 with WNK1 blocked the inhibitory effect of miR-136-5p on WNK1, which was confirmed by in vivo experiments. Altogether, our results revealed an important role of lncRNA LEF1-AS1 in regulating the HCC progression by regulating WNK1, providing a potential biomarker for the therapeutic modalities regarding HCC.     

Enhancement of vaccinia virus based oncolysis with histone deacetylase inhibitors

Histone deacetylase inhibitors (HDI) dampen cellular innate immune response by decreasing interferon production and have been shown to increase the growth of vesicular stomatitis virus and HSV. As attenuated tumour-selective oncolytic vaccinia viruses (VV) are already undergoing clinical evaluation, the goal of this study is to determine whether HDI can also enhance the potency of these poxviruses in infection-resistant cancer cell lines. Multiple HDIs were tested and Trichostatin A (TSA) was found to potently enhance the spread and replication of a tumour selective vaccinia virus in several infection-resistant cancer cell lines. TSA significantly decreased the number of lung metastases in a syngeneic B16F10LacZ lung metastasis model yet did not increase the replication of vaccinia in normal tissues. The combination of TSA and VV increased survival of mice harbouring human HCT116 colon tumour xenografts as compared to mice treated with either agent alone. We conclude that TSA can selectively and effectively enhance the replication and spread of oncolytic vaccinia virus in cancer cells.