Role of PTEN/PI3K pathway in endothelial cells

Muscone abrogates breast cancer progression through tumor angiogenic suppression via VEGF/PI3K/Akt/MAPK signaling pathways

BACKGROUND

Angiogenesis strongly reflects poor breast cancer outcome and an important contributor to breast cancer (BC) metastasis; therefore, anti-angiogenic intervention is a potential tool for cancer treatment. However, currently used antibodies against vascular endothelial growth factor A (VEGFA) or inhibitors that target the VEGFA receptor are not effective due to weak penetration and low efficiency. Herein, we assessed the anti-BC angiogenic role of muscone, a natural bioactive musk constituent, and explored possible anti-cancer mechanisms of this compound.

METHODS

CCK-8, EdU, scratch and Transwell assessments were employed to detect the muscone-mediated regulation of breast cancer (BC) and human umbilical vein endothelial cells (HUVECs) proliferation and migration. Tube formation, matrigel plug assay and zebrafish assay were employed for assessment of regulation of tumor angiogenesis by muscone. In vivo xenograft mouse model was constructed to compare microvessel density (MVD), vascular leakage, vascular maturation and function in muscone-treated or untreated mice. RNA sequencing was performed for gene screening, and Western blot verified the effect of the VEGFA-VEGFR2 pathway on BC angiogenic inhibition by muscone.

RESULTS

Based on our findings, muscone suppressed BC progression via tumor angiogenic inhibition in cellular and animal models. Functionally, muscone inhibited BC cell proliferation and migration as well as tumor cell-conditioned medium-based endothelial cell proliferation and migration. Muscone exhibited a strong suppressive influence on tumor vasculature in cellular and animal models. It abrogated tumor cell growth in a xenograft BC mouse model and minimized tumor microvessel density and hypoxia, and increased vascular wall cell coverage and perfusion. Regarding the mechanism of action, we found that muscone suppressed phosphorylation of members of the VEGF/PI3K/Akt/MAPK axis, and it worked synergistically with a VEGFR2 inhibitor, an Akt inhibitor, and a MAPK inhibitor to further inhibit tube formation.

CONCLUSION

Overall, our results demonstrate that muscone may proficiently suppress tumor angiogenesis via modulation of the VEGF/PI3K/Akt/MAPK axis, facilitating its candidacy as a natural small molecule drug for BC treatment.

SiRNA-HIF-1α delivered by attenuated Salmonella enhances the efficacy of Lenvatinib against hepatocellular carcinoma

The treatment of hepatocellular carcinoma (HCC) remains a major challenge in the medical field. Lenvatinib, a multi-target tyrosine kinase inhibitor, has demonstrated anti-HCC effects by targeting and inhibiting pathways such as vascular endothelial growth factor receptor 1-3 (VEGFR1-3). However, the therapeutic efficacy of Lenvatinib is subject to various influences, with the hypoxic microenvironment of the tumor being a pivotal factor. Consequently, altering the hypoxic milieu of the tumor emerges as a viable strategy to augment the efficacy of Lenvatinib. Hypoxia-inducible factor-1α (HIF-1α), synthesized by tumor cells in response to oxygen-deprived conditions, regulates the expression of resistance genes, promotes tumor angiogenesis and cell proliferation, enhances tumor cell invasion, and confers resistance to radiotherapy and chemotherapy. Thus, we constructed a self-designed siRNA targeting HIF-1α to suppress its expression and improve the efficacy of Lenvatinib in treating HCC. The therapeutic efficacy of siRNA-HIF-1α in combination with Lenvatinib on HCC were evaluated through in vivo and in vitro experiments. The results showed that the recombinant Salmonella delivering siRNA-HIF-1α in combination with Lenvatinib effectively inhibited tumor growth and prolonged the survival of tumor-bearing mice. This treatment approach reduced cell proliferation and angiogenesis in HCC tissues while promoting tumor cell apoptosis. Additionally, this combined therapy significantly increased the infiltration of T lymphocytes and M1 macrophages within the tumor microenvironment, as well as elevated the proportion of immune cells in the spleen, thereby potentiating the host's immune response against the tumor.

Ligusticum chuanxiong promotes the angiogenesis of preovulatory follicles (F1-F3) in late-phase laying hens

Ligusticum chuanxiong (CX) is a traditional Chinese medicine that is widely planted throughout the world. CX is one of the most important and commonly used drugs to enhance blood circulation. The preovulatory follicles in laying hens have a large number of blood arteries and meridians that feed the follicles' growth and maturation with nutrients, hormones, and cytokines. With the extension of laying time, preovulatory follicles angiogenesis decreased gradually. In this study, we studied the mechanism of CX on preovulatory follicles angiogenesis in late-phase laying hens. The results show that CX extract can increase the angiogenesis of preovulatory follicles (F1-F3) of late-phase laying hens. CX extract can promote vascular endothelial growth factor receptor 2 (VEGFR2) phosphorylation in preovulatory follicles theca layers, promote the proliferation, invasion and migration through PI3K/AKT and RAS/ERK signaling pathways in primary follicle microvascular endothelial-like cells (FMECs). In addition, CX extract can up-regulate the expression of hypoxia inducible factor α (HIF1α) in granulosa cells (GCs) and granulosa layers through PI3K/AKT and RAS/ERK signaling pathways, thereby promoting the secretion of vascular endothelial growth factor A (VEGFA). In conclusion, the current study confirmed the promoting effect of CX extract on the preovulatory follicles angiogenesis, which sets the stage for the design of functional animal feed for late-phase laying hens.

siRNA targeting PD-L1 delivered with attenuated Salmonella enhanced the anti-tumor effect of lenvatinib on mice bearing Hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a primary liver cancer representing serious harm to human health. The effective treatment of HCC is challenging. Lenvatinib is an inhibitor of polytyrosine kinase that exerts an effect against HCC by blocking the VEGF signaling pathway. However, its efficacy in most patients remains unsatisfactory. The factors influencing tumorigenesis are diverse; thus, combined treatment is an important strategy against tumors. Programmed death ligand-1 (PD-L1), which binds to programmed death-1 (PD-1), significantly compromises the anti-tumor effect of T cells. Therefore, we designed a siRNA-PD-L1 and delivered it using attenuated Salmonella, and its synergistic effects with Lenvatinib against HCC were evaluated. The results showed that the combination of Lenvatinib and siRNA-PD-L1 inhibited tumor growth in H22 tumor-bearing mice, arrested cell proliferation, and increased cell apoptosis in the tumor. The combination treatment synergistically inhibited the expression of VEGF and PD-L1 and contributed to the increase in T-cell infiltration in the tumor tissues and the ratio of T cells in the spleen. Furthermore, the combination treatment increased the number of granzyme B⁺ T cells, indicating a significantly improved anti-tumor immunity in mice. Therefore, this combination might be a potential novel strategy for HCC treatment.

Molecular Regulation of Sprouting Angiogenesis

The term angiogenesis arose in the 18th century. Several studies over the next 100 years laid the groundwork for initial studies performed by the Folkman laboratory, which were at first met with some opposition. Once overcome, the angiogenesis field has flourished due to studies on tumor angiogenesis and various developmental models that can be genetically manipulated, including mice and zebrafish. In addition, new discoveries have been aided by the ability to isolate primary endothelial cells, which has allowed dissection of various steps within angiogenesis. This review will summarize the molecular events that control angiogenesis downstream of biochemical factors such as growth factors, cytokines, chemokines, hypoxia-inducible factors (HIFs), and lipids. These and other stimuli have been linked to regulation of junctional molecules and cell surface receptors. In addition, the contribution of cytoskeletal elements and regulatory proteins has revealed an intricate role for mobilization of actin, microtubules, and intermediate filaments in response to cues that activate the endothelium. Activating stimuli also affect various focal adhesion proteins, scaffold proteins, intracellular kinases, and second messengers. Finally, metalloproteinases, which facilitate matrix degradation and the formation of new blood vessels, are discussed, along with our knowledge of crosstalk between the various subclasses of these molecules throughout the text. Compr Physiol 8:153-235, 2018.

Tipping the balance from angiogenesis to fibrosis in CKD

Chronic progressive renal fibrosis leads to end-stage renal failure many patients with chronic kidney disease (CKD). Loss of the rich peritubular capillary network is a prominent feature, and seems independent of the specific underlying disease. The mechanisms that contribute to peritubular capillary regression include the loss of glomerular perfusion, as flow-dependent shear forces are required to provide the survival signal for endothelial cells. Also, reduced endothelial cell survival signals from sclerotic glomeruli and atrophic or injured tubule epithelial cells contribute to peritubular capillary regression. In response to direct tubular epithelial cell injury, and the inflammatory reaction that ensues, capillary pericytes dissociate from their blood vessels, also reducing endothelial cell survival. In addition, direct inflammatory injury of capillary endothelial cells, for instance in chronic allograft nephropathy, also contributes to capillary dropout. Chronic tissue hypoxia, which ensues from the rarefaction of the peritubular capillary network, can generate both an angiogenic and a fibrogenic response. However, in CKD, the balance is strongly tipped toward fibrogenesis. Understanding the underlying mechanisms for failed angiogenesis in CKD and harnessing endothelial-specific survival and pro-angiogenic mechanisms for therapy should be our goal if we are to reduce the disease burden from CKD.

MiR-92a regulates viability and angiogenesis of endothelial cells under oxidative stress

Oxidative stress contributes to endothelial cell (EC) dysfunction, which is prevalent in ageing and atherosclerosis. MicroRNAs (miRs) are small, non-coding RNAs that post-transcriptionally regulate gene expression and play a key role in fine-tuning EC functional responses, including apoptosis and angiogenesis. MiR-92a is highly expressed in young endothelial cells in comparison with senescent endothelial cells, which exhibit increased oxidative stress and apoptosis. However, the impact of miR-92a treatment on EC viability and angiogenesis under oxidative stress is unknown. Hydrogen peroxide (H2O2) was used to induce oxidative stress in human umbilical vein endothelial cells (HUVEC). Pre-miR-92a treatment decreased H2O2-induced apoptosis of HUVEC as determined by TUNEL assay. Pre-miR-92a treatment enhanced capillary tube formation by HUVEC under oxidative stress, which was blocked by LY294002, an inhibitor of Akt phosphorylation. Interestingly, we also observed that inhibition of miR-92a by anti-miR-92a antisense can also enhance angiogenesis in HUVEC with and without oxidative stress exposure. Our results show that perturbation of miR-92a levels outside of its narrow "homeostatic" range may trigger endothelial cell angiogenesis, suggesting that the role of miR-92a in regulating angiogenesis is controversial and may vary depending on the experimental model and method of regulating miR-92a.

VEGFA and tumour angiogenesis

In this review we summarize the current understanding of signal transduction downstream of vascular endothelial growth factor A (VEGFA) and its receptor VEGFR2, and the relationship between these signal transduction pathways and the hallmark responses of VEGFA, angiogenesis and vascular permeability. These physiological responses involve a number of effectors, including extracellular signal-regulated kinases (ERKs), Src, phosphoinositide 3 kinase (PI3K)/Akt, focal adhesion kinase (FAK), Rho family GTPases, endothelial NO and p38 mitogen-activated protein kinase (MAPK). Several of these factors are involved in the regulation of both angiogenesis and vascular permeability. Tumour angiogenesis primarily relies on VEGFA-driven responses, which to a large extent result in a dysfunctional vasculature. The reason for this remains unclear, although it appears that certain aspects of the VEGFA-stimulated angiogenic milieu (high level of microvascular density and permeability) promote tumour expansion. The high degree of redundancy and complexity of VEGFA-driven tumour angiogenesis may explain why tumours commonly develop resistance to anti-angiogenic therapy targeting VEGFA signal transduction.

PI3K/AKT/PTEN Signaling as a Molecular Target in Leukemia Angiogenesis

PI3K/AKT/PTEN pathway is important in the regulation of angiogenesis mediated by vascular endothelial growth factor in many tumors including leukemia. The signaling pathway is activated in leukemia patients as well as leukemia cell lines together with a decrease in the expression of PTEN gene. The mechanism by which the signaling pathway regulates angiogenesis remains to be further elucidated. However, it has become an attractive target for drug therapy against leukemia, because angiogenesis is a key process in malignant cell growth. In this paper, we will focus on the roles and mechanisms of PI3K/AKT/PTEN pathway in regulating angiogenesis.

Resolving cell-cell junctions: lumen formation in blood vessels

Formation of a patent vascular lumen is essential for the transport of oxygen, nutrients and waste products to and from tissues. No matter whether the blood vessel arises from vasculogenesis or angiogenesis, endothelial cells (EC) first have to form a cord, which subsequently lumenizes, in order to generate a functional vessel. During these processes, cellular junctions rearrange between adjacent ECs and are involved in EC polarization as a prerequisite for lumen formation. Here we review the role of EC junctions in vascular lumen formation within different vascular beds.

Faithfull modeling of PTEN loss driven diseases in the mouse

A decade of work has indisputably defined PTEN as a pivotal player in human health and disease. Above all, PTEN has been identified as one of the most commonly lost or mutated tumor suppressor genes in human cancers. For this reason, the generation of a multitude of mouse models has been an invaluable strategy to dissect the function and consequences-of-loss of this essential, evolutionary conserved lipid phosphatase in tumor initiation and progression.In this chapter, we will summarize the mouse models that have allowed us to faithfully recapitulate features of human cancers and to highlight the network of connections between the PTEN signaling cascade and other oncogenic or tumor suppressive pathways.Notably, PTEN represents one of the most extensively modeled genes involved in human cancer and exemplifies the strength of genetic mouse modeling as an approach to gain information aimed to improve our understanding of and ability to alleviate human disease.

PI3K/PTEN signaling in angiogenesis and tumorigenesis

Phosphatidylinositol 3-kinase (PI3K) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) signaling pathway play an important role in multiple cellular functions such as cell metabolism, proliferation, cell-cycle progression, and survival. PI3K is activated by growth factors and angiogenesis inducers such as vascular endothelial growth factor (VEGF) and angiopoietins. The amplification and mutations of PI3K and the loss of the tumor suppressor PTEN are common in various kinds of human solid tumors. The genetic alterations of upstream and downstream of PI3K signaling molecules such as receptor tyrosine kinases and AKT, respectively, are also frequently altered in human cancer. PI3K signaling regulates tumor growth and angiogenesis by activating AKT and other targets, and by inducing HIF-1 and VEGF expression. Angiogenesis is required for tumor growth and metastasis. In this review, we highlight the recent studies on the roles and mechanisms of PI3K and PTEN in regulating tumorigenesis and angiogenesis, and the roles of the downstream targets of PI3K for transmitting the signals. We also discuss the crosstalk of these signaling molecules and cellular events during tumor growth, metastasis, and tumor angiogenesis. Finally, we summarize the potential applications of PI3K, AKT, and mTOR inhibitors and their outcome in clinical trials for cancer treatment.

The roles of PTEN in development, physiology and tumorigenesis in mouse models: a tissue-by-tissue survey

In 1997, PTEN (phosphatase and tensin homologue deleted on chromosome 10, 10q23.3) was identified as an important tumor suppressor gene that is inactivated in a wide variety of human cancers. Ever since, PTEN's function has been extensively studied, and huge progress has been made in understanding PTEN's role in normal physiology and disease. In this review, we will systematically summarize the important data that have been gained from gene inactivation studies in mice and will put these data into physiological context using a tissue-by-tissue approach. We will cover mice exhibiting complete and constitutive inactivation of Pten as well as a large number of strains in which Pten has been conditionally deleted in specific tissues. We hope to highlight not only the tumor suppressive function of Pten but also its roles in embryogenesis and in the maintenance of the normal physiological functions of many organ systems.

Advances in PTEN and hepatic diseases

Role of PTEN in tumorigenesis has been a hotspot of research in tumor domain. Researchers have recently been concerned about its additional role in non-tumor diseases. For liver diseases, apart from researches of PTEN effects on hepatic cellular cancer pathogenesis, there have been some other studies on relationship between PTEN and other liver diseases. This paper reviewed relationship between PTEN and liver diseases as well as its identification, structure and function.

Suppressing PTEN activity by tobacco smoke plus interleukin-1beta modulates dissociation of VE-cadherin/beta-catenin complexes in endothelium

OBJECTIVE

Tobacco smoke (TS) interacts with inflammatory cytokines to produce endothelial dysfunction. We hypothesized that interleukin-1beta (IL-1beta) plus TS (TS/IL-1beta) induces disassembly of endothelial junctional complexes of VE-cadherin/beta-catenin by suppression of PTEN activity and investigated molecular mechanisms that modulate PTEN-deactivation in this situation.

METHODS AND RESULTS

TS/IL-1beta exposure, which disrupted adherens junctions and induced nuclear beta-catenin accumulation, increased tyrosine phosphorylation (p-Tyr) of VE-cadherin and beta-catenin, and reduced PTEN activity. Overexpression or silencing of PTEN modulated p-Tyr of both VE-cadherin and beta-catenin, changed assembly of adherens junction complexes, and altered nuclear beta-catenin accumulation. In addition, inhibiting ROS production stimulated by TS/IL-1beta decreased activation of Src, EGFR and p38MAPK, phosphorylation of PTEN, VE-cadherin and beta-catenin, and abrogated the effect of TS/IL-1beta to disorganize adherens junctions, resulting in reduced endothelial permeability and decreased nuclear beta-catenin accumulation. Finally, exposure of ApoE(-/-) mice to cigarette smoke-induced phosphorylation of Src, EGFR, p-38MAPK, PTEN, and beta-catenin, and disrupted VE-cadherin/beta-catenin complexes in cardiovascular tissue.

CONCLUSIONS

TS interaction with IL-1beta modulates PTEN activity though the ROS/Src/EGFR-p38MAPK pathway. PTEN deactivation is essential to increase VE-cadherin and beta-catenin p-Tyr and to disassemble VE-cadherin/beta-catenin membrane complexes, events that lead to accumulation of beta-catenin within the nucleus.