Growth Factor Signaling Cascades Research Articles

FoxO and rotund form a binding complex governing wing polyphenism in planthoppers

Wing polyphenism is found in a variety of insects and offers an attractive model system for studying the evolutionary significance of dispersal. The Forkhead box O (FoxO) transcription factor (TF) acts as a wing-morph switch that directs wing buds developing into long-winged (LW) or short-winged morphs in wing-dimorphic planthoppers, yet the regulatory mechanism of the FoxO module remains elusive. Here, we identified the zinc finger TF rotund as a potential wing-morph regulator via transcriptomic analysis and phenotypic screening in the brown plathopper, Nilaparvata lugens. RNA interference-mediated knockdown of rotund antagonized the LW development derived from in the context of FoxO depletion or the activation of the insulin/insulin-like growth factor signaling cascade, reversing long wings into intermediate wings. Invitro binding assays indicated that rotund physically binds to FoxO to form the FoxO combinatorial code. These findings broaden our understanding of the complexity of transcriptional regulation governing wing polyphenism in insects.

Comprehensive analysis of culture conditions governing differentiation of MSCs into articular chondrocytes.

Treatment of osteoarthritic patients requires the development of morphologically and mechanically complex hyaline cartilage at the injury site. A tissue engineering approach toward differentiating mesenchymal stem cells into articular chondrocytes has been developed to overcome the drawbacks of conventional therapeutic and surgical procedures. To imitate the native micro and macro environment of articular chondrocytes, cell culture parameters such as oxygen concentration, mechanical stress, scaffold design, and growth factor signalling cascade regulation must be addressed. This review aims to illuminate the path toward developing tissue engineering approaches, accommodating these various parameters and the role these parameters play in regulating chondrogenesis for better articular cartilage development to treat osteoarthritis effectively.

The Role of Insulin Receptor Substrate Proteins in Bronchopulmonary Dysplasia and Asthma: New Potential Perspectives.

Insulin receptor substrates (IRSs) are proteins that are involved in signaling through the insulin receptor (IR) and insulin-like growth factor (IGFR). They can also interact with other receptors including growth factor receptors. Thus, they represent a critical node for the transduction and regulation of multiple signaling pathways in response to extracellular stimuli. In addition, IRSs play a central role in processes such as inflammation, growth, metabolism, and proliferation. Previous studies have highlighted the role of IRS proteins in lung diseases, in particular asthma. Further, the members of the IRS family are the common proteins of the insulin growth factor signaling cascade involved in lung development and disrupted in bronchopulmonary dysplasia (BPD). However, there is no study focusing on the relationship between IRS proteins and BPD yet. Unfortunately, there is still a significant gap in knowledge in this field. Thus, in this review, we aimed to summarize the current knowledge with the major goal of exploring the possible roles of IRS in BPD and asthma to foster new perspectives for further investigations.

Subtype of Neuroblastoma Cells with High KIT Expression Are Dependent on KIT and Its Knockdown Induces Compensatory Activation of Pro-Survival Signaling.

Neuroblastoma (NB) is a pediatric cancer with high clinical and molecular heterogeneity, and patients with high-risk tumors have limited treatment options. Receptor tyrosine kinase KIT has been identified as a potential marker of high-risk NB and a promising target for NB treatment. We investigated 19,145 tumor RNA expression and molecular pathway activation profiles for 20 cancer types and detected relatively high levels of KIT expression in NB. Increased KIT expression was associated with activation of cell survival pathways, downregulated apoptosis induction, and cell cycle checkpoint control pathways. KIT knockdown with shRNA encoded by lentiviral vectors in SH-SY5Y cells led to reduced cell proliferation and apoptosis induction up to 50%. Our data suggest that apoptosis induction was caused by mitotic catastrophe, and there was a 2-fold decrease in percentage of G2-M cell cycle phase after KIT knockdown. We found that KIT knockdown in NB cells leads to strong upregulation of other pro-survival growth factor signaling cascades such as EPO, NGF, IL-6, and IGF-1 pathways. NGF, IGF-1 and EPO were able to increase cell proliferation in KIT-depleted cells in an ERK1/2-dependent manner. Overall, we show that KIT is a promising therapeutic target in NB, although such therapy efficiency could be impeded by growth factor signaling activation.

Post-Transcriptional Regulation of Molecular Determinants during Cardiogenesis.

Cardiovascular development is initiated soon after gastrulation as bilateral precardiac mesoderm is progressively symmetrically determined at both sides of the developing embryo. The precardiac mesoderm subsequently fused at the embryonic midline constituting an embryonic linear heart tube. As development progress, the embryonic heart displays the first sign of left-right asymmetric morphology by the invariably rightward looping of the initial heart tube and prospective embryonic ventricular and atrial chambers emerged. As cardiac development progresses, the atrial and ventricular chambers enlarged and distinct left and right compartments emerge as consequence of the formation of the interatrial and interventricular septa, respectively. The last steps of cardiac morphogenesis are represented by the completion of atrial and ventricular septation, resulting in the configuration of a double circuitry with distinct systemic and pulmonary chambers, each of them with distinct inlets and outlets connections. Over the last decade, our understanding of the contribution of multiple growth factor signaling cascades such as Tgf-beta, Bmp and Wnt signaling as well as of transcriptional regulators to cardiac morphogenesis have greatly enlarged. Recently, a novel layer of complexity has emerged with the discovery of non-coding RNAs, particularly microRNAs and lncRNAs. Herein, we provide a state-of-the-art review of the contribution of non-coding RNAs during cardiac development. microRNAs and lncRNAs have been reported to functional modulate all stages of cardiac morphogenesis, spanning from lateral plate mesoderm formation to outflow tract septation, by modulating major growth factor signaling pathways as well as those transcriptional regulators involved in cardiac development.

Crk adaptor proteins are necessary for the development of the zebrafish retina.

The development of the central nervous system (CNS) requires critical cell signaling molecules to coordinate cell proliferation and migration in order to structure the adult tissue. Chicken tumor virus #10 Regulator of Kinase (CRK) and CRK-like (CRKL) are adaptor proteins with pre-metazoan ancestry and are known to be required for patterning laminated structures downstream of Reelin (RELN), such as the cerebral cortex, cerebellum, and hippocampus. CRK and CRKL also play crucial roles in a variety of other growth factor and extracellular matrix signaling cascades. The neuronal retina is another highly laminated structure within the CNS that is dependent on migration for proper development, but the cell signaling mechanisms behind neuronal positioning in the retina are only partly understood. We find that crk and crkl have largely overlapping expression within the developing zebrafish nervous system. We find that their disruption results in smaller eye size and loss of retinal lamination. Our data indicate that Crk adaptors are critical for proper development of the zebrafish neural retina in a crk/crkl dose-dependent manner.

Bevacizumab Augments the Antitumor Efficacy of Infigratinib in Hepatocellular Carcinoma.

The fibroblast growth factor (FGF) signaling cascade is one of the key signaling pathways in hepatocellular carcinoma (HCC). FGF has been shown to augment vascular endothelial growth factor (VEGF)-mediated HCC development and angiogenesis, as well as to potentially lead to resistance to VEGF/VEGF receptor (VEGFR)-targeted agents. Thus, novel agents targeting FGF/FGF receptor (FGFR) signaling may enhance and/or overcome de novo or acquired resistance to VEGF-targeted agents in HCC. Mice bearing high- and low-FGFR tumors were treated with Infigratinib (i.e., a pan-FGFR kinase inhibitor) and/or Bevacizumab (i.e., an angiogenesis inhibitor). The antitumor activity of both agents was assessed individually or in combination. Tumor vasculature, intratumoral hypoxia, and downstream targets of FGFR signaling pathways were also investigated. Infigratinib, when combined with Bevacizumab, exerted a synergistic inhibitory effect on tumor growth, invasion, and lung metastasis, and it significantly improved the overall survival of mice bearing FGFR-dependent HCC. Infigratinib/Bevacizumab promoted apoptosis, inhibited cell proliferation concomitant with upregulation of p27, and reduction in the expression of FGFR2-4, p-FRS-2, p-ERK1/2, p-p70S6K/4EBP1, Cdc25C, survivin, p-Cdc2, and p-Rb. Combining Infigratinib/Bevacizumab may provide therapeutic benefits for a subpopulation of HCC patients with FGFR-dependent tumors. A high level of FGFR-2/3 may serve as a potential biomarker for patient selection to Infigratinib/Bevacizumab.

Balanced Wnt/Dickkopf-1 signaling by mesenchymal vascular progenitor cells in the microvascular niche maintains distal lung structure and function.

The well-described Wnt inhibitor Dickkopf-1 (DKK1) plays a role in angiogenesis as well as in regulation of growth factor signaling cascades in pulmonary remodeling associated with chronic lung diseases (CLDs) including emphysema and fibrosis. However, the specific mechanisms by which DKK1 influences mesenchymal vascular progenitor cells (MVPCs), microvascular endothelial cells (MVECs), and smooth muscle cells (SMCs) within the microvascular niche have not been elucidated. In this study, we show that knockdown of DKK1 in Abcg2pos lung mouse adult tissue resident MVPCs alters lung stiffness, parenchymal collagen deposition, microvessel muscularization and density as well as loss of tissue structure in response to hypoxia exposure. To complement the in vivo mouse modeling, we also identified cell- or disease-specific responses to DKK1, in primary lung chronic obstructive pulmonary disease (COPD) MVPCs, COPD MVECs, and SMCs, supporting a paradoxical disease-specific response of cells to well-characterized factors. Cell responses to DKK1 were dose dependent and correlated with varying expressions of the DKK1 receptor, CKAP4. These data demonstrate that DKK1 expression is necessary to maintain the microvascular niche whereas its effects are context specific. They also highlight DKK1 as a regulatory candidate to understand the role of Wnt and DKK1 signaling between cells of the microvascular niche during tissue homeostasis and during the development of chronic lung diseases.

Abstract 5280: Kinase fusions drive endocrine resistance in estrogen receptor-positive breast cancer

Abstract Oncogenic kinase activation by gene fusions can promote cancer development and tumor progression, however, kinase fusions have not been characterized extensively in breast cancer. In this study, we characterized kinase fusions in a large cohort of 4854 breast cancer patients using clinical DNA and/or RNA next generation sequencing platforms. Twenty-seven cases harboring kinase fusions were identified, including 11 FGFR (5 FGFR2, 3 FGFR3, 3 FGFR1), 5 BRAF, 4 NTRK1, 2 RET, 2 ROS1, 1 ALK, 1 ERBB2, and 1 MET. Eight patients with a history of endocrine therapy had available pre-treatment samples, of which six were negative for kinase fusion, and ESR1 hotspot mutations were not observed in any of these kinase fusion-positive samples. These findings suggest a potential role for kinase fusions in endocrine therapy resistance and prompted us to model the kinase fusions in human breast cancer cell lines. Ectopic expression of LMNA-NTRK1 fusion kinase activated growth factor signaling cascades, including PI3K-AKT and MAPK-ERK pathways, and promoted hormone-independent growth in MCF7 and T47D cells. Enforced expression of the LMNA-NTRK1 fusion conferred resistance to the ER antagonist fulvestrant and combined treatment of fulvestrant and the Trk inhibitor larotrectinib completely blocked the growth of LMNA-NTRK+ breast cancer cells. Similarly, expression of the EML4-ALK fusion also activated growth factor signaling pathways and caused resistance to estrogen depletion and induced sensitivity to the ALK inhibitor, Ceritinib. Treatment of xenografted LMNA-NTRK1 expressing tumors confirmed the efficacy of the combined treatment of antiestrogen and NTRK1 inhibition in vivo. Two patients with acquired LMNA-NTRK1 fusions and metastatic disease received larotrectinib and demonstrated clinical benefit. Overall, our findings demonstrate that kinase fusions promote endocrine resistance in ER-positive breast cancer, and suggest that fusion screening in advanced breast cancer, particularly those with ER-positive breast cancer at progression on hormone therapy can identify rare tumors harboring targetable kinase fusions. Citation Format: Bo Liu, Dara S. Ross, Alison M. Schram, Pedram Razavi, Stephen M. Lagana, Yanming Zhang, Maurizio Scaltriti, Jacqueline F. Bromberg, Marc Ladanyi, David M. Hyman, Alexander Drilon, Ahmet Zahir, Ryma Benayed, Jaclyn F. Hechtman, Sarat Chandarlapaty. Kinase fusions drive endocrine resistance in estrogen receptor-positive breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5280.

Combinations of growth factors for human mesenchymal stem cell proliferation and osteogenic differentiation.

AimsHere we introduce a wide and complex study comparing effects of growth factors used alone and in combinations on human mesenchymal stem cell (hMSC) proliferation and osteogenic differentiation. Certain ways of cell behaviour can be triggered by specific peptides – growth factors, influencing cell fate through surface cellular receptors.MethodsIn our study transforming growth factor β (TGF-β), basic fibroblast growth factor (bFGF), hepatocyte growth factor (HGF), insulin-like growth factor 1 (IGF-1), and vascular endothelial growth factor (VEGF) were used in order to induce osteogenesis and proliferation of hMSCs from bone marrow. These cells are naturally able to differentiate into various mesodermal cell lines. Effect of each factor itself is pretty well known. We designed experimental groups where two and more growth factors were combined. We supposed cumulative effect would appear when more growth factors with the same effect were combined. The cellular metabolism was evaluated using MTS assay and double-stranded DNA (dsDNA) amount using PicoGreen assay. Alkaline phosphatase (ALP) activity, as early osteogenesis marker, was observed. Phase contrast microscopy was used for cell morphology evaluation.ResultsTGF-β and bFGF were shown to significantly enhance cell proliferation. VEGF and IGF-1 supported ALP activity. Light microscopy showed initial extracellular matrix mineralization after VEGF/IGF-1 supply.ConclusionA combination of more than two growth factors did not support the cellular metabolism level and ALP activity even though the growth factor itself had a positive effect. This is probably caused by interplay of various messengers shared by more growth factor signalling cascades.Cite this article: Bone Joint Res 2020;9(7):412–420.

Precision medicine for human cancers with Notch signaling dysregulation (Review).

NOTCH1, NOTCH2, NOTCH3 and NOTCH4 are transmembrane receptors that transduce juxtacrine signals of the delta-like canonical Notch ligand (DLL)1, DLL3, DLL4, jagged canonical Notch ligand (JAG)1 and JAG2. Canonical Notch signaling activates the transcription of BMI1 proto-oncogene polycomb ring finger, cyclin D1, CD44, cyclin dependent kinase inhibitor 1A, hes family bHLH transcription factor 1, hes related family bHLH transcription factor with YRPW motif 1, MYC, NOTCH3, RE1 silencing transcription factor and transcription factor 7 in a cellular context-dependent manner, while non-canonical Notch signaling activates NF-κB and Rac family small GTPase 1. Notch signaling is aberrantly activated in breast cancer, non-small-cell lung cancer and hematological malignancies, such as T-cell acute lymphoblastic leukemia and diffuse large B-cell lymphoma. However, Notch signaling is inactivated in small-cell lung cancer and squamous cell carcinomas. Loss-of-function NOTCH1 mutations are early events during esophageal tumorigenesis, whereas gain-of-function NOTCH1 mutations are late events during T-cell leukemogenesis and B-cell lymphomagenesis. Notch signaling cascades crosstalk with fibroblast growth factor and WNT signaling cascades in the tumor microenvironment to maintain cancer stem cells and remodel the tumor microenvironment. The Notch signaling network exerts oncogenic and tumor-suppressive effects in a cancer stage- or (sub)type-dependent manner. Small-molecule γ-secretase inhibitors (AL101, MRK-560, nirogacestat and others) and antibody-based biologics targeting Notch ligands or receptors [ABT-165, AMG 119, rovalpituzumab tesirine (Rova-T) and others] have been developed as investigational drugs. The DLL3-targeting antibody-drug conjugate (ADC) Rova-T, and DLL3-targeting chimeric antigen receptor-modified T cells (CAR-Ts), AMG 119, are promising anti-cancer therapeutics, as are other ADCs or CAR-Ts targeting tumor necrosis factor receptor superfamily member 17, CD19, CD22, CD30, CD79B, CD205, Claudin 18.2, fibroblast growth factor receptor (FGFR)2, FGFR3, receptor-type tyrosine-protein kinase FLT3, HER2, hepatocyte growth factor receptor, NECTIN4, inactive tyrosine-protein kinase 7, inactive tyrosine-protein kinase transmembrane receptor ROR1 and tumor-associated calcium signal transducer 2. ADCs and CAR-Ts could alter the therapeutic framework for refractory cancers, especially diffuse-type gastric cancer, ovarian cancer and pancreatic cancer with peritoneal dissemination. Phase III clinical trials of Rova-T for patients with small-cell lung cancer and a phase III clinical trial of nirogacestat for patients with desmoid tumors are ongoing. Integration of human intelligence, cognitive computing and explainable artificial intelligence is necessary to construct a Notch-related knowledge-base and optimize Notch-targeted therapy for patients with cancer.

Infigratinib Mediates Vascular Normalization, Impairs Metastasis, and Improves Chemotherapy in Hepatocellular Carcinoma.

The fibroblast growth factor (FGF) signaling cascade is a key signaling pathway in hepatocarcinogenesis. We report high FGF receptor (FGFR) expression in 17.7% (11 of 62) of hepatocellular carcinoma (HCC) models. Infigratinib, a pan‐FGFR inhibitor, potently suppresses the growth of high‐FGFR‐expressing and sorafenib‐resistant HCCs. Infigratinib inhibits FGFR signaling and its downstream targets, cell proliferation, the angiogenic rescue program, hypoxia, invasion, and metastasis. Infigratinib also induces apoptosis and vessel normalization and improves the overall survival of mice bearing FGFR‐driven HCCs. Infigratinib acts in synergy with the microtubule‐depolymerizing drug vinorelbine to promote apoptosis, suppress tumor growth, and improve the overall survival of mice. Increased expression levels of FGFR‐2 and FGFR‐3 through gene amplification correlate with treatment response and may serve as potential biomarkers for patient selection. Conclusion: Treatments with Infigratinib alone or in combination with vinorelbine may be effective in a subset of patients with HCC with FGFR‐driven tumors.

Substantial Dysregulation of miRNA Passenger Strands Underlies the Vascular Response to Injury.

Vascular smooth muscle cell (VSMC) dedifferentiation is a common feature of vascular disorders leading to pro-migratory and proliferative phenotypes, a process induced through growth factor and cytokine signaling cascades. Recently, many studies have demonstrated that small non-coding RNAs (miRNAs) can induce phenotypic effects on VSMCs in response to vessel injury. However, most studies have focused on the contribution of individual miRNAs. Our study aimed to conduct a detailed and unbiased analysis of both guide and passenger miRNA expression in vascular cells in vitro and disease models in vivo. We analyzed 100 miRNA stem loops by TaqMan Low Density Array (TLDA) from primary VSMCs in vitro. Intriguingly, we found that a larger proportion of the passenger strands was significantly dysregulated compared to the guide strands after exposure to pathological stimuli, such as platelet-derived growth factor (PDGF) and IL-1α. Similar findings were observed in response to injury in porcine vein grafts and stent models in vivo. In these studies, we reveal that the miRNA passenger strands are predominantly dysregulated in response to vascular injury.

Low expression of c-Myc protein predicts poor outcomes in patients with hepatocellular carcinoma after resection

BackgroundEmbryonic Liver Fodrin (ELF) is an adaptor protein of transforming growth factor (TGF-β) signaling cascade. Disruption of ELF results in mislocalization of Smad3 and Smad4, leading to compromised TGF-β signaling. c-Myc is an important oncogenic transcription factor, and the disruption of TGF-β signaling promotes c-Myc-induced hepatocellular carcinoma (HCC) carcinogenesis. However, the prognostic significance of c-Myc in HCC is less understoodMethodsThe expression of c-Myc protein and mRNA were measured by immunohistochemistry (IHC) and qRT- PCR, respectively. IHC was performed to detect TGF-β1 and ELF expression in HCC tissues. Their relationship with clinicopathological factors and overall survival (OS) and disease free survival (DFS) were examined.ResultsThe expression of c-Myc protein and mRNA in HCC tissues were significantly higher in HCC area than those in normal liver tissues. However, the expression were low compared with those adjacent to HCC area. c-Myc protein was independently predictive of DFS and OS, and it was negatively correlated with tumor size (P = 0.031), tumor number (P = 0.038), and recurrence (P = 0.001). Low c-Myc expression was associated with short-term recurrence and poor prognosis. The predictive value of c-Myc combined with TGF-β1 or/and ELF was higher than that of any other single marker. Low c-Myc, high TGF-β1 or/and low ELF expression was associated with the worst DFS and OS.ConclusionsLow expression of c-Myc protein predicts poor outcomes in patients with HCC with hepatectomy. The combination of the expression of c-Myc, TGF-β1, and ELF can be used to accurately predict outcomes of patients with HCC.

Dihydroartemisinin enhances VEGFR1 expression through up-regulation of ETS-1 transcription factor.

Angiogenesis is required for tumor growth. Dihydroartemisinin (DHA), a the effective anti-malarial derivative of artemisinin, demonstrated potent anti-angiogenic activities that closely related to the regulation of vascular endothelial growth factor (VEGF) signaling cascade. VEGF receptor 1 (VEGFR1), a receptor in endothelial cells (ECs), coordinately regulate angiogenic activity triggered by ligand-receptor binding. Here we aimed to explore the effects of DHA on VEGFR1 expression in ECs. We found that DHA significantly increases VEGFR1 expression in human umbilical vein endothelial cells (HUVECs). In addition, DHA significantly upregulates the level of V-Ets Avian Erythroblastosis Virus E26 Oncogene Homolog 1 (ETS-1), a transcriptional factor which binds to the human VEGFR1 promoter. ChIP assay showed that DHA increases ETS-1 binding to the -52 ETS motif on the VEGFR1 promoter. Knockdown of ETS-1 by RNA interference abolished DHA-induced increase of VEGFR1 expression. Taken together, we demonstrated that DHA elevates VEGFR1 expression via up-regulation of ETS-1 transcription in HUVECs.

Abstract 3831: Oncogenic BRAF and concomitant RAS or PTEN/PI3K mutations determine together the response to RAS/RAF/PI3K signaling network inhibition

Abstract Background: BRAF is key component in the growth factor signaling cascade that is often impaired in tumors. Although oncogenic BRAF mutation is considered to be the driver mutation in a variety of malignancies, the response to RAS/RAF/PI3K signaling network inhibition is not uniform among BRAF mutant tumors. Accordingly, we investigated the in vitro effect of RAS/RAF/PI3K signaling network inhibitors (panRAF, mutant BRAF specific, MEK and PI3K/mTOR inhibitors) in relation with BRAF concomitant RAS or PTEN/PI3K mutations in a panel of human cancer cell lines. Methods: Altogether 12 human cancer cell lines were investigated in vitro to assess the effect of inhibitors acting at the different levels of the RAS/RAF signaling network. The seven melanoma, two colon, two lung and one breast cancer cell lines were divided into 3 groups according to their mutational status: BRAF-mutant with no PTEN/PI3K/RAS mutations (A375, WM35, SK-MEL-28, CRL5885), BRAF + PTEN-PI3K (A2058, WM239, HT29, SW1417) and BRAF + RAS double mutant (WM3629, WM3670, MDA-MB-231, CRL5922). Effect of inhibitors on proliferation, clonogenic potential and migration were investigated SRB and clonogenic assays and videomicroscopy measurements, respectively. Both single agent and combination treatments were applied. Results: In single agent treatments panRAF and PI3K/mTOR inhibitors did not show mutation dependent differences in proliferation, however, mutant-BRAF and MEK specific inhibitors were more effective in cells without concomitant PTEN/PI3K or RAS mutations. Interestingly, not only the combination of BRAF and MEK inhibitors but the combination of PI3K/mTOR and MEK inhibition showed additive inhibitory effect on proliferation in all subgroups. Importantly, a distinct pattern emerged for the mutational subgroup specific migration inhibitory effects in comparison to the inhibition of proliferation. Conclusion: BRAF mutant cells carrying various concomitant PTEN/PI3K/RAS alterations display distinct response to RAS/RAF/PI3K network inhibition in terms of proliferation as well as migration. Our data suggests that combination treatments acting concurrently on different targets of the RAS/RAF/PI3K network can be more effective as single therapies. Citation Format: Tamas M. Garay, Eszter Molnar, Dominika Rittler, Walter Berger, Balazs Döme, Jozsef Timar, Balazs Hegedus. Oncogenic BRAF and concomitant RAS or PTEN/PI3K mutations determine together the response to RAS/RAF/PI3K signaling network inhibition. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3831.

Dysfunction of Insulin‐like Growth Factor Signaling in Skeletal Muscles of Low Birth Weight Neonatal Pigs

Low birth weight (LBWT) neonates experience restricted fetal muscle development and impaired postnatal muscle growth. Our previous data suggest that protein synthesis is lower while protein degradation is not different in skeletal muscle of LBWT compared to normal birth weight (NBWT) neonatal pigs. We hypothesized that decreased protein synthesis in skeletal muscle of LBWT pigs is a consequence of dysfunction of insulin‐like growth factor (IGF) signaling cascade. Twenty four LBWT and NBWT male pigs were euthanized to collect blood and longissimus dorsi (LD) muscle samples. Plasma IGF‐I concentration was measured using a commercial ELISA kit, mRNA expression by real‐time PCR and protein expression and phosphorylation by western blot. Plasma IGF‐I concentration and mRNA expression of IGF‐I and IGF binding protein 5 (IGFBP 5) were lower in LD muscle of LBWT pigs (P < 0.05). However, mRNA and protein expression of IGF‐I receptor was higher in the LD muscle of LBWT compared to NBWT pigs (P < 0.05). Protein expression of eukaryotic initiation factor 4E binding protein 1 (4EBP1) and phosphorylation of ribosomal protein S6 kinase 1 (S6K1) were lower in LD muscle of LBWT compared to their NBWT siblings (P < 0.05). These results suggest that in spite of the increased abundance of IGF‐I receptor in muscles of LBWT pigs, there is a reduction in the expression of downstream effectors of IGF‐I. As a result, IGF signaling is compromised and could contribute to impaired postnatal muscle growth in LBWT compared to NBWT neonatal pigs.Support or Funding InformationVirginia Agricultural Experiment Station and the Hatch Program of the National Institute of Food and Agriculture, U.S. Department of Agriculture (S.W. El‐Kadi)

Rnd3/RhoE Modulates Hypoxia-Inducible Factor 1α/Vascular Endothelial Growth Factor Signaling by Stabilizing Hypoxia-Inducible Factor 1α and Regulates Responsive Cardiac Angiogenesis.

The insufficiency of compensatory angiogenesis in the heart of patients with hypertension contributes to heart failure transition. The hypoxia-inducible factor 1α-vascular endothelial growth factor (HIF1α-VEGF) signaling cascade controls responsive angiogenesis. One of the challenges in reprograming the insufficient angiogenesis is to achieve a sustainable tissue exposure to the proangiogenic factors, such as HIF1α stabilization. In this study, we identified Rnd3, a small Rho GTPase, as a proangiogenic factor participating in the regulation of the HIF1α-VEGF signaling cascade. Rnd3 physically interacted with and stabilized HIF1α, and consequently promoted VEGFA expression and endothelial cell tube formation. To demonstrate this proangiogenic role of Rnd3 in vivo, we generated Rnd3 knockout mice. Rnd3 haploinsufficient (Rnd3(+/-)) mice were viable, yet developed dilated cardiomyopathy with heart failure after transverse aortic constriction stress. The poststress Rnd3(+/-) hearts showed significantly impaired angiogenesis and decreased HIF1α and VEGFA expression. The angiogenesis defect and heart failure phenotype were partially rescued by cobalt chloride treatment, a HIF1α stabilizer, confirming a critical role of Rnd3 in stress-responsive angiogenesis. Furthermore, we generated Rnd3 transgenic mice and demonstrated that Rnd3 overexpression in heart had a cardioprotective effect through reserved cardiac function and preserved responsive angiogenesis after pressure overload. Finally, we assessed the expression levels of Rnd3 in the human heart and detected significant downregulation of Rnd3 in patients with end-stage heart failure. We concluded that Rnd3 acted as a novel proangiogenic factor involved in cardiac responsive angiogenesis through HIF1α-VEGFA signaling promotion. Rnd3 downregulation observed in patients with heart failure may explain the insufficient compensatory angiogenesis involved in the transition to heart failure.

Tumour initiating cells and IGF/FGF signalling contribute to sorafenib resistance in hepatocellular carcinoma

ObjectiveSorafenib is effective in hepatocellular carcinoma (HCC), but patients ultimately present disease progression. Molecular mechanisms underlying acquired resistance are still unknown. Herein, we characterise the role of tumour-initiating cells (T-ICs)...

The combination of sorafenib and everolimus shows antitumor activity in preclinical models of malignant pleural mesothelioma.

BackgroundMalignant Pleural Mesothelioma (MPM) is an aggressive tumor arising from mesothelial cells lining the pleural cavities characterized by resistance to standard therapies. Most of the molecular steps responsible for pleural transformation remain unclear; however, several growth factor signaling cascades are known to be altered during MPM onset and progression. Transducers of these pathways, such as PIK3CA-mTOR-AKT, MAPK, and ezrin/radixin/moesin (ERM) could therefore be exploited as possible targets for pharmacological intervention. This study aimed to identify ‘druggable’ pathways in MPM and to formulate a targeted approach based on the use of commercially available molecules, such as the multikinase inhibitor sorafenib and the mTOR inhibitor everolimus.MethodsWe planned a triple approach based on: i) analysis of immunophenotypes and mutational profiles in a cohort of thoracoscopic MPM samples, ii) in vitro pharmacological assays, ii) in vivo therapeutic approaches on MPM xenografts. No mutations were found in ‘hot spot’ regions of the mTOR upstream genes (e.g. EGFR, KRAS and PIK3CA).ResultsPhosphorylated mTOR and ERM were specifically overexpressed in the analyzed MPM samples. Sorafenib and everolimus combination was effective in mTOR and ERM blockade; exerted synergistic effects on the inhibition of MPM cell proliferation; triggered ROS production and consequent AMPK-p38 mediated-apoptosis. The antitumor activity was displayed when orally administered to MPM-bearing NOD/SCID mice.ConclusionsERM and mTOR pathways are activated in MPM and ‘druggable’ by a combination of sorafenib and everolimus. Combination therapy is a promising therapeutic strategy against MPM.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1363-1) contains supplementary material, which is available to authorized users.