VEGF stimulation enhances livin protein synthesis through mTOR signaling

Ang-1 and VEGF: central regulators of angiogenesis

Angiopoietin-1 (Ang-1) and Vascular Endothelial Growth Factor (VEGF) are central regulators of angiogenesis and are often inactivated in various cardiovascular diseases. VEGF forms complexes with ETS transcription factor family and exerts its action by downregulating multiple genes. Among the target genes of the VEGF-ETS complex, there are a significant number encoding key angiogenic regulators. Phosphorylation of the VEGF-ETS complex releases transcriptional repression on these angiogenic regulators, thereby promoting their expression. Ang-1 interacts with TEK, and this phosphorylation release can be modulated by the Ang-1-TEK signaling pathway. The Ang-1-TEK pathway participates in the transcriptional activation of VEGF genes. In summary, these elements constitute the Ang-1-TEK-VEGF signaling pathway. Additionally, Ang-1 is activated under hypoxic and inflammatory conditions, leading to an upregulation in the expression of TEK. Elevated TEK levels result in the formation of the VEGF-ETS complex, which, in turn, downregulates the expression of numerous angiogenic genes. Hence, the Ang-1-dependent transcriptional repression is indirect. Reduced expression of many target genes can lead to aberrant angiogenesis. A significant overlap exists between the target genes regulated by Ang-1-TEK-VEGF and those under the control of the Ang-1-TEK-TSP-1 signaling pathway. Mechanistically, this can be explained by the replacement of the VEGF-ETS complex with the TSP-1 transcriptional repression complex at the ETS sites on target gene promoters. Furthermore, VEGF possesses non-classical functions unrelated to ETS and DNA binding. Its supportive role in TSP-1 formation may be exerted through the VEGF-CRL5-VHL-HIF-1α-VH032-TGF-β-TSP-1 axis. This review assesses the regulatory mechanisms of the Ang-1-TEK-VEGF signaling pathway and explores its significant overlap with the Ang-1-TEK-TSP-1 signaling pathway.

Comprehensive analysis of tissue proteomics in patients with papillary thyroid microcarcinoma uncovers the underlying mechanism of lymph node metastasis and its significant sex disparities

Background

Lymph node metastasis (LNM) in papillary thyroid microcarcinoma (PTMC) is associated with an increased risk of recurrence and poor prognosis. Sex has been regarded as a critical risk factor for LNM. The present study aimed to investigate the molecular mechanisms underlying LNM and its significant sex disparities in PTMC development.

Methods

A direct data-independent acquisition (DIA) proteomics approach was used to identify differentially expressed proteins (DEPs) in PTMC tumorous tissues with or without LNM and from male and female patients with LNM. The functional annotation of DEPs was performed using bioinformatics methods. Furthermore, The Cancer Genome Atlas Thyroid Carcinoma (TCGA-THCA) dataset and immunohistochemistry (IHC) were used to validate selected DEPs.

Results

The proteomics profile in PTMC with LNM differed from that of PTMC without LNM. The metastasis-related DEPs were primarily enriched in categories associated with mitochondrial dysfunction and may promote tumor progression by activating oxidative phosphorylation and PI3K/AKT signaling pathways. Comparative analyses of these DEPs revealed downregulated expression of specific proteins with well-established links to tumor metastasis, such as SLC25A15, DIRAS2, PLA2R1, and MTARC1. Additionally, the proteomics profiles of male and female PTMC patients with LNM were dramatically distinguishable. An elevated level of ECM-associated proteins might be related to more LNM in male PTMC than in female PTMC patients. The upregulated expression levels of MMRN2 and NID2 correlated with sex disparities and showed a positive relationship with unfavorable variables, such as LNMs and poor prognosis.

Conclusions

The proteomics profiles of PTMC show significant differences associated with LNM and its sex disparities, which further expands our understanding of the functional networks and signaling pathways related to PTMC with LNM.

Identification of VEGFA-centric temporal hypoxia-responsive dynamic cardiopulmonary network biomarkers

AIMS

Hypoxia, a pathophysiological condition, is profound in several cardiopulmonary diseases (CPD). Every individual's lethality to a hypoxia state differs in terms of hypoxia exposure time, dosage units and dependent on the individual's genetic makeup. Most of the proposed markers for CPD were generally aim to distinguish disease samples from normal samples. Although, as per the 2018 GOLD guidelines, clinically useful biomarkers for several cardio pulmonary disease patients in stable condition have yet to be identified. We attempt to address these key issues through the identification of Dynamic Network Biomarkers (DNB) to detect hypoxia induced early warning signals of CPD before the catastrophic deterioration.

MATERIALS AND METHODS

The human microvascular endothelial tissues microarray datasets (GSE11341) of lung and cardiac expose to hypoxia (1% O₂) for 3, 24 and 48 h were retrieved from the public repository. The time dependent differentially expressed genes were subjected to tissue specificity and promoter analysis to filtrate the noise levels in the networks and to dissect the tissue specific hypoxia induced genes. These filtered out genes were used to construct the dynamic segmentation networks. The hypoxia induced dynamic differentially expressed genes were validated in the lung and heart tissues of male rats. These rats were exposed to hypobaric hypoxia (simulated altitude of 25,000 or PO₂ - 282 mm of Hg) progressively for 3, 24 and 48 h.

KEY FINDINGS

To identify the temporal key genes regulated in hypoxia, we ranked the dominant genes based on their consolidated topological features from tissue specific networks, time dependent networks and dynamic networks. Overall topological ranking described VEGFA as a single node dynamic hub and strongly communicated with tissue specific genes to carry forward their tissue specific information. We named this type of VEGFAcentric dynamic networks as "V-DNBs". As a proof of principle, our methodology helped us to identify the V-DNBs specific for lung and cardiac tissues namely V-DNB^L and V-DNB^C respectively.

SIGNIFICANCE

Our experimental studies identified VEGFA, SLC2A3, ADM and ENO2 as the minimum and sufficient candidates of V-DNB^L. The dynamic expression patterns could be readily exploited to capture the pre disease state of hypoxia induced pulmonary vascular remodelling. Whereas in V-DNB^C the minimum and sufficient candidates are VEGFA, SCL2A3, ADM, NDRG1, ENO2 and BHLHE40. The time dependent single node expansion indicates V-DNB^C could also be the pre disease state pathological hallmark for hypoxia-associated cardiovascular remodelling. The network cross-talk and expression pattern between V-DNB^L and V-DNB^C are completely distinct. On the other hand, the great clinical advantage of V-DNBs for pre disease predictions, a set of samples during the healthy condition should suffice. Future clinical studies might further shed light on the predictive power of V-DNBs as prognostic and diagnostic biomarkers for CPD.

Identification and Validation of Six Autophagy-related Long Non-coding RNAs as Prognostic Signature in Colorectal Cancer

Colorectal cancer (CRC) is a commonly occurring tumour with poor prognosis. Autophagy-related long non-coding RNAs (lncRNAs) have received much attention as biomarkers for cancer prognosis and diagnosis. However, few studies have focused on their prognostic predictive value specifically in CRC. This research aimed to construct a robust autophagy-related lncRNA prognostic signature for CRC. Autophagy-related lncRNAs from The Cancer Genome Atlas database were screened using univariate Cox, LASSO, and multivariate Cox regression analyses, and the resulting key lncRNAs were used to establish a prognostic risk score model. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) analysis was performed to detect the expression of several lncRNAs in cancer tissues from CRC patients and in normal tissues adjacent to the cancer tissues. A prognostic signature comprising lncRNAs AC125603.2, LINC00909, AC016876.1, MIR210HG, AC009237.14, and LINC01063 was identified in patients with CRC. A graphical nomogram based on the autophagy-related lncRNA signature was developed to predict CRC patients' 1-, 3-, and 5-year survival. Overall survival in patients with low risk scores was significantly better than in those with high risk scores (P < 0.0001); a similar result was obtained in an internal validation sample. The nomogram was shown to be suitable for clinical use and gave correct predictions. The 1- and 3-year values of the area under the receiver operating characteristic curve were 0.797 and 0.771 in the model sample, and 0.656 and 0.642 in the internal validation sample, respectively. The C-index values for the verification samples and training samples were 0.756 (95% CI = 0.668-0.762) and 0.715 (95% CI = 0.683-0.829), respectively. Gene set enrichment analysis showed that the six autophagy-related lncRNAs were greatly enriched in CRC-related signalling pathways, including p53 and VEGF signalling. The qRT-PCR results showed that the expression of lncRNAs in CRC was higher than that in adjacent tissues, consistent with the expression trends of lncRNAs in the CRC data set. In summary, we established a signature of six autophagy-related lncRNAs that could effectively guide clinical prediction of prognosis in patients with CRC. This lncRNA signature has significant clinical implications for improving the prediction of outcomes and, with further prospective validation, could be used to guide tailored therapy for CRC patients.

Resistance of melanoma cells to anticancer treatment: a role of vascular endothelial growth factor

Melanoma is one of the most aggressive and resistant to treatment neoplasms. There are still many challenges despite many promising advances in anticancer treatment. Currently, the main problem for all types of treatment is associated with heterogeneity. Due to heterogeneity of cancer cells, "precise" targeting of a medicine against a single phenotype limits the efficacy of treatment and affects resistance to applied therapy. Therefore it is important to understand aetiology and reasons for heterogeneity in order to develop effective and long-lasting treatment. This review summarises roles of vascular endothelial growth factor (VEGF) that may stimulate growth of a melanoma tumour irrespective of its proangiogenic effects, contributing to cancer heterogeneity. VEGF triggers processes associated with extracellular matrix remodelling, cell migration, invasion, angiogenesis, inhibition of immune responses and favours phenotypic plasticity and epithelial-mesenchymal transition. Consequently, it participates in mechanisms of interactions between melanoma cancer cells and microenvironment and it can modify sensitivity to therapeutic factors.

Expression of Livin and PlGF in human osteosarcoma is associated with tumor progression and clinical outcome

Baculoviral IAP repeat containing 7 (BIRC7/Livin/ML-IAP/KIAP; referred to as Livin throughout the present study) and placental growth factor (PlGF) are not detectable in the majority of normal differentiated tissues, but are present in a number of types of cancer, including hepatocellular carcinoma, ovarian cancer and renal cell carcinoma. The aim of the present study was to assess the expression levels of Livin and PlGF in human osteosarcoma specimens and cell lines, and to analyze the functions of Livin and PIGF in the prognosis of osteosarcoma. The expression levels of Livin and PlGF in 48 osteosarcoma specimens and three osteosarcoma cells were determined using immunohistochemistry and reverse transcription-quantitative polymerase chain reaction. The positivity rates of Livin and PlGF in osteosarcoma specimens were 58.3 and 60.4%, respectively, but were 0% in normal bone tissues. The expression levels of Livin and PlGF were increased in MG-63 cells, compared with those in the other cell lines evaluated in the present study. In addition, the expression levels of Livin and PlGF were significantly associated with tumor diameter and Enneking staging, but were independent of tumor site, age and sex of patients. The expression level of Livin was not associated with PlGF. Furthermore, the 5-year overall survival rate was decreased in the Livin or PlGF expression group, compared with that in the non-expression group (P=0.034 and P=0.012, respectively). The expression levels of Livin and PlGF were independent prognostic factors for patients with osteosarcoma. The results of the present study demonstrated that Livin and PlGF may participate in the pathogenesis of osteosarcoma. Therefore, pharmacological inhibition of Livin or PlGF may provide a novel strategy for osteosarcoma treatment.

Chromodomain Helicase/ATPase DNA-Binding Protein 1-Like Gene (CHD1L) Expression and Implications for Invasion and Metastasis of Breast Cancer

Background

Chromodomain helicase/ATPase DNA-binding protein 1-like gene (CHD1L), also known as ALC1 (amplified in liver cancer 1 gene), is a new oncogene amplified in many solid tumors. Whether this gene plays a role in invasion and metastasis of breast cancer is unknown.

Methods

Immunohistochemistry was performed to detect the expression of CHD1L in patients with invasive ductal carcinoma and normal mammary glands. Chemotaxis, wound healing, and Transwell invasion assays were also performed to examine cell migration and invasion. Western blot analysis was conducted to detect the expression of CHD1L, MMP-2, MMP-9, pAkt/Akt, pARK5/ARK5, and pmTOR/mTOR. Moreover, ELISA was carried out to detect the expression levels of MMP-2 and MMP-9. Nude mice xenograft model was used to detect the invasion and metastasis of breast cancer cell lines.

Results

CHD1L overexpression was observed in 112 of 268 patients (41.8%). This overexpression was associated with lymph node metastasis (P = 0.008), tumor differentiation (P = 0.020), distant metastasis (P = 0.026), MMP-2 (P = 0.035), and MMP-9 expression (P = 0.022). In the cell experiment, reduction of CHD1L inhibited the invasion and metastasis of breast cancer cells by mediating MMP-2 and MMP-9 expression. CHD1L knockdown via siRNA suppressed EGF-induced pAkt, pARK5, and pmTOR. This knockdown inhibited the metastasis of breast cancer cells into the lungs of SCID mice.

Conclusions

CHD1L promoted the invasion and metastasis of breast cancer cells via the PI3K/Akt/ARK5/mTOR/MMP signaling pathway. This study identified CHD1L as a potential anti-metastasis target for therapeutic intervention in breast cancer.

Silencing of Livin inhibits tumorigenesis and metastasis via VEGF and MMPs pathway in lung cancer

Livin, an inhibitor of apoptosis protein (IAP), is overexpressed in various cancers and decreases tumor sensitivity to chemotherapy and radiotherapy. However, the effect of Livin on lung adenocarcinoma metastasis and the specific mechanism involved remain unclear. RNAi technology was used to stably silence Livin in A549 cells in the present study. The effect of Livin on tumor growth and invasion was investigated in lung cancer cells in vitro and animal models were established to determine the anti-metastasis ability of Livin silencing in vivo. The results indicated that Livin knock-down suppressed cell proliferation and inhibited cell invasion, accompanied by downregulation of VEGF and MMP-2/-9. Silencing of Livin resulted in the prevention of xenograft tumor formation. Seventy-five immunodeficient male BALB/C nude mice were randomly divided into three groups, the relative ratio of the areas with pulmonary nodules in the experimental group decreased from 46.71±7.27% to 11.07±2.94% compared with the negative control group (P<0.001), indicating the interaction between Livin, VEGF and MMPs. The xenograft tumor model of intravenous injection of tumor cells were successfully established and applied for the analysis of lung cancer tumorigenesis and metastasis in a time-dependent manner for the first time. Based on the reliable and reproducible animal model, our findings indicate that knock-down of Livin inhibits cell growth and invasion through blockade of the VEGF and MMPs pathways in lung cancer cells in vitro, and inhibits tumorigenesis and metastasis of lung cancer in vivo, suggesting that Livin is a promising antitumor target.

EBP50 inhibits the migration and invasion of human breast cancer cells via LIMK/cofilin and the PI3K/Akt/mTOR/MMP signaling pathway

The scaffold protein ezrin-radixin-moesin-binding phosphoprotein 50 (EBP50, also known as NHERF1 or NHERF) inhibits epidermal growth factor (EGF)-induced breast cancer cell proliferation after 3 days by blocking EGF receptor (EGFR) phosphorylation. The loss of EBP50 stimulates EGFR activity and induces the appearance of epithelial-to-mesenchymal transition phenotypic features in biliary cancer cells. However, the involvement of EBP50 in breast cancer migration and invasion remains unknown. We report that EBP50 inhibits the migration and invasion of breast cancer cells by inhibiting the phosphorylation of LIN-11, Isl1, and MEC-3 protein domain kinase, as well as cofilin. This phosphorylation is a critical step in cofilin recycling and actin polymerization mediating cytoskeletal rearrangement. Additionally, EGF-induced phosphorylation of Akt and mTOR was suppressed by upregulation of EBP50. Our results indicate that EBP50 is significantly involved in breast cancer invasion/metastasis via LIMK/cofilin and the PI3K/Akt/mTOR/MMP signaling pathway.

Livin expression is an independent factor in rectal cancer patients with or without preoperative radiotherapy

BACKGROUND

This study was aimed to investigate the expression significance of Livin in relation to radiotherapy (RT), clinicopathological and biological factors of rectal cancer patients.

METHODS

This study included 144 primary rectal cancer patients who participated in a Swedish clinical trial of preoperative radiotherapy. Tissue microarray samples from the excised primary rectal cancers, normal mucosa and lymph node metastases were immunostained with Livin antibody. The proliferation of colon cancer cell lines SW620 and RKO was assayed after Livin knock-down.

RESULTS

The expression of Livin was significantly increased from adjacent (P = 0.051) or distant (P = 0.028) normal mucosa to primary tumors. 15.4% (2/13) and 39.7% (52/131) patients with Livin-negative and positive tumors died at 180 months after surgery, and the difference tended to be statistically significant (P = 0.091). In multivariate analyses, the difference achieved statistical significance, independent of TNM stage, local and distant recurrence, grade of differentiation, gender, and age (odds ratio = 5.09, 95% CI: 1.01-25.64, P = 0.048). The in vitro study indicated colon cancer cells with Livin knock-down exhibited decreased proliferation compared with controls after RT.

CONCLUSIONS

The expression of Livin was was independently related to survival in rectal cancer patients, suggesting Livin as a useful prognostic factor for rectal cancer patients.

Gab2 expression in glioma and its implications for tumor invasion

Gliomas are characterized by high invasiveness and poor prognosis. Better understanding of the mechanism of invasion in glioma cells is essential to the design of effective therapy. Recently Grb2-associated binder 2 (Gab2), a member of the DOS/Gab family of scaffolding adapters, has been reported to play important roles in the development and progression of human cancers. However, it is not known whether Gab2 has any role in the migration and invasion of gliomas. This study attempts to investigate the association between Gab2 expression and progression of gliomas and the molecular mechanism of Gab2 in the glioma cell invasion. Methods. The expression of Gab2 in pairs of matched glioma tissues and their normal brain tissues was detected by Western blot. Immunohistochemistry was applied to evaluate the expression of Gab2 in 163 cases of histologically diagnosed gliomas. The invasive character of Gab2 decreased glioma cells and control glioma cells were investigated in vitro and in vivo in SCID mice brain. Results. Gab2 is found to be high expressed in gliomas and a subset of cancer cell lines. Statistical analysis suggested that the up-regulation of Gab2 correlated with the WHO grade of gliomas (p < 0.01) and that patients with high Gab2 expression levels exhibited shorter survival time (p < 0.01). In an animal experiment, knockdown of Gab2 through siRNA inhibited invasive ability of glioma cells into the brain of SCID mice. In cell research, reduction of Gab2 by siRNA inhibits the migration and invasion of glioma cells by mediating cytoskeleton rearrangement and MMPs expression. Additionally, IGF-1-induced pAkt and pmTOR phosphorylation was suppressed by the knockdown of Gab2. Conclusion. Gab2 may be a useful prognostic marker for gliomas and a novel therapeutic target for glioma invasion intervention.

Anti-apoptotic proteins on guard of melanoma cell survival

Apoptosis plays a pivotal role in sustaining proper tissue development and homeostasis. Evading apoptosis by cancer cells is a part of their adaption to microenvironment and therapies. Cellular integrity is predominantly maintained by pro-survival members of Bcl-2 family and IAPs. Melanoma cells are characterized by a labile and stage-dependent phenotype. Pro-survival molecules can protect melanoma cells from apoptosis and mediate other processes, thus enhancing aggressive phenotype. The essential role of Bcl-2, Mcl-1, Bcl-X(L), livin, survivin and XIAP was implicated for melanoma, often in a tumor stage-dependent fashion. In this review, the current knowledge of pro-survival machinery in melanoma is discussed.

Upregulation of the antiapoptotic factor Livin contributes to cisplatin resistance in colon cancer cells

The antiapoptotic factor Livin has been considered critical for tumor progression and poor prognosis for variant types of tumors. However, there are only limited reports regarding its expression and biological functions in colon cancer. Here, we examined Livin expression in four colon cancer cell lines (HCT116, RKO, KM12C, and SW620) in the presence or absence of cisplatin that was used as a model reagent. We found the different response to cisplatin was related to endogenous Livin expression level. From among a panel of apoptosis-related factors (p53, Bcl-2, Bcl-XL, BAX, and survivin), the expression of Livin was upregulated after cisplatin treatment in a dose-dependent manner. Both immunocytochemistry and nuclear cytoplasmic fractionation indicated Livin remained in the cytoplasm after treatment with cisplatin. In an attempt to explore the mechanism, we found the elevated expression of Livin was not due to the decreased degradation by proteosome but was enhanced at the mRNA level. Besides, cisplatin treatment activated the mammalian target of rapamycin (mTOR) pathway as shown by increased phosphorylation of Akt1, mTOR, S6K, and 4E-BP1, together with the elevated Livin. The PI3K inhibitor LY294002 inhibited both the phosphorylation of mTOR and upregulation of Livin. The stable overexpression of Livin inhibited the activation of caspase-3 and led to resistance to cisplatin, while the knockdown of Livin by siRNA rendered colon cancer cells more sensitive to cisplatin. Our study, along with others, highlighted the potential of Livin for cancer therapy in colon cancer.

Alteration of TEAD1 expression levels confers apoptotic resistance through the transcriptional up-regulation of Livin

Background

TEA domain (TEAD) proteins are highly conserved transcription factors involved in embryonic development and differentiation of various tissues. More recently, emerging evidences for a contribution of these proteins towards apoptosis and cell proliferation regulation have also been proposed. These effects appear to be mediated by the interaction between TEAD and its co-activator Yes-Associated Protein (YAP), the downstream effector of the Hippo tumour suppressor pathway.

Methodology/Principal Findings

We further investigated the mechanisms underlying TEAD-mediated apoptosis regulation and showed that overexpression or RNAi-mediated silencing of the TEAD1 protein is sufficient to protect mammalian cell lines from induced apoptosis, suggesting a proapoptotic function for TEAD1 and a non physiological cytoprotective effect for overexpressed TEAD1. Moreover we show that the apoptotic resistance conferred by altered TEAD1 expression is mediated by the transcriptional up-regulation of Livin, a member of the Inhibitor of Apoptosis Protein (IAP) family. In addition, we show that overexpression of a repressive form of TEAD1 can induce Livin up-regulation, indicating that the effect of TEAD1 on Livin expression is indirect and favoring a model in which TEAD1 activates a repressor of Livin by interacting with a limiting cofactor that gets titrated upon TEAD1 up-regulation. Interestingly, we show that overexpression of a mutated form of TEAD1 (Y421H) implicated in Sveinsson's chorioretinal atrophy that strongly reduces its interaction with YAP as well as its activation, can induce Livin expression and protect cells from induced apoptosis, suggesting that YAP is not the cofactor involved in this process.

Conclusions/Significance

Taken together our data reveal a new, Livin-dependent, apoptotic role for TEAD1 in mammals and provide mechanistic insight downstream of TEAD1 deregulation in cancers.

In vitro and in vivo antitumoral action of metformin on hepatocellular carcinoma

AIMS

  Metformin is a biguanide that has been widely used to treat type 2 diabetes. Several studies have shown that metformin is also effective in treating cancer, including hepatocellular carcinoma (HCC). The objective of this study was to evaluate the antitumor effects of metformin in HCC, and to investigate the potential molecular target(s) of metformin-mediated antitumor activity.

METHODS

  The antiproliferative effects of metformin were assessed in human HCC cell lines and normal human liver cells at various concentrations. Orthotopic xenograft tumors were established in athymic nude mice, and tumor growth was monitored after metformin treatment. Western blot analysis and cell cycle regulation were performed to determine the involvement of various mediators of apoptosis.

RESULTS

  Metformin specifically inhibited the growth of HCC cells without affecting the growth of normal liver cells both in vitro and in vivo. Metformin caused cell cycle arrest in HCC cells, which resulted in caspase-3 activation. Livin levels decreased in a dose-dependent manner upon metformin treatment. Metformin activated 5'-adenosine monophosphate-activated protein kinase, inhibited the mammalian target of rapamycin pathway and downregulated Livin protein expression.

CONCLUSION

  Our findings indicate that metformin is effective at initiating apoptosis and inhibiting key survival signaling pathways in HCC cells. These data provide a foundation for further studies to evaluate metformin in the clinic either as a single agent or in combination with other first-line agents as a treatment option for HCC.