Induction of thrombospondin-1 partially mediates the anti-angiogenic activity of dexrazoxane

Dexrazoxane inhibits the growth of esophageal squamous cell carcinoma by attenuating SDCBP/MDA-9/syntenin-mediated EGFR-PI3K-Akt pathway activation

Syndecan-binding protein (SDCBP) was reported to stimulate the advancement of esophageal squamous cell carcinoma (ESCC) and could potentially be a target for ESCC treatment. There is a growing corpus of research on the anti-tumor effects of iron chelators; however, very few studies have addressed the involvement of dexrazoxane in cancer. In this study, structure-based virtual screening was employed to select drugs targeting SDCBP from the Food and Drug Administration (FDA)-approved drug databases. The sepharose 4B beads pull-down assay revealed that dexrazoxane targeted SDCBP by interacting with its PDZ1 domain. Additionally, dexrazoxane inhibited ESCC cell proliferation and anchorage-independent colony formation via SDCBP. ESCC cell apoptosis and G2 phase arrest were induced as measured by the flow cytometry assay. Subsequent research revealed that dexrazoxane attenuated the binding ability between SDCBP and EGFR in an immunoprecipitation assay. Furthermore, dexrazoxane impaired EGFR membrane localization and inactivated the EGFR/PI3K/Akt pathway. In vivo, xenograft mouse experiments indicated that dexrazoxane suppressed ESCC tumor growth. These data indicate that dexrazoxane might be established as a potential anti-cancer agent in ESCC by targeting SDCBP.

Thrombospondin-1 in drug activity and tumor response to therapies

Thrombospondins (TSPs) have numerous different roles in cancer, regulating the behavior of cancer cells and non-neoplastic cells, and defining the responses of tumor cells to environmental changes, thorough their ability to orchestrate cellular and molecular interactions in the tumor microenvironment (TME). As a result of these activities, TSPs can also control drug delivery and activity, tumor response and resistance to therapies, with different outcomes depending on the nature of TSP-interacting cell types, receptors, and ligands, in a highly context-dependent manner. This review, focusing primarily on TSP-1, discusses the effects of TSPs on tumor response to chemotherapy, antiangiogenic, low-dose metronomic chemotherapy, immunotherapy, and radiotherapy, by analyzing TSP activity on different cell compartments - tumor cells, vascular endothelial cells and immune cells. We review evidence of the value of TSPs, specifically TSP-1 and TSP-2, as biomarkers of prognosis and tumor response to therapy. Finally, we examine possible approaches to develop TSP-based compounds as therapeutic tools to potentiate the efficacy of anticancer therapy.

Exploring the impact of naltrexone on the THBS1/eNOS/NO pathway in osteoporotic bile duct-ligated rats

Hepatic osteodystrophy, a prevalent manifestation of metabolic bone disease, can arise in the context of chronic liver disease. The THBS1-eNOS-NO signaling pathway plays a pivotal role in the maturation of osteoclast precursors. This study aimed to investigate the impact of Naltrexone (NTX) on bone loss by examining the THBS1-eNOS-NO signaling pathways in bile duct ligated (BDL) rats. Male Wistar rats were randomly divided into five groups (n = 10 per group): control, sham-operated + normal saline, BDL + normal saline, sham-operated + NTX (10 mg/kg), and BDL + NTX. Parameters related to liver injury were measured at the study's conclusion, and Masson-trichrome staining was employed to evaluate collagen deposition in liver tissue. Bone THBS-1 and endothelial nitric oxide synthase (eNOS) expression levels were measured using real-time PCR, while the level of bone nitric oxide (NO) was assessed through a colorimetric assay. NTX treatment significantly attenuated the BDL-induced increase in circulating levels of liver enzymes and bilirubin. THBS-1 expression levels, elevated after BDL, were significantly suppressed following NTX administration in the BDL + NTX group. Despite no alterations in eNOS expression between groups, the bone NO level, significantly decreased in the BDL group, was significantly reduced by NTX in the BDL + NTX group. This study partly provides insights into the possible molecular mechanisms in BDL-induced osteoporosis and highlights the modulating effect of NTX on these pathways. Further research is needed to establish the impact of NTX on histomorphometric indexes.

Human papillomavirus E7 binds Oct4 and regulates its activity in HPV-associated cervical cancers

Octamer binding transcription factor-4 (Oct4), is highly expressed in stem cells and has indispensable roles in pluripotency and cellular reprogramming. In contrast to other factors used for cellular reprogramming, a role for Oct4 outside embryonic stem cells has been elusive and highly controversial. Emerging evidence implicates Oct4 in the carcinogenic process, but the mechanism through which Oct4 may be functioning in cancers is not fully appreciated. Here, we provide evidence that Oct4 is expressed in human cervical cancer and this expression correlates with the presence of the human papillomavirus (HPV) oncogenes E6 and E7. Surprisingly, the viral oncogenes can complement exogenously provided Oct4 in reprogramming assays, providing functional validation for their ability to activate Oct4 transcription in Mouse Embryonic Fibroblasts (MEFs). To interrogate potential roles of Oct4 in cervical cancers we knocked-down Oct4 in HPV(+) (HeLa & CaSki) and HPV(-) (C33A) cervical cancer cell lines and found that Oct4 knockdown attenuated clonogenesis, only in the HPV(+) cells. More unexpectedly, cell proliferation and migration, were differentially affected in HPV(+) and HPV(-) cell lines. We provide evidence that Oct4 interacts with HPV E7 specifically at the CR3 region of the E7 protein and that introduction of the HPV oncogenes in C33A cells and human immortalised keratinocytes generates Oct4-associated transcriptional and phenotypic patterns, which mimic those seen in HPV(+) cells. We propose that a physical interaction of Oct4 with E7 regulates its activity in HPV(+) cervical cancers in a manner not seen in other cancer types.

Engineering a vascularised 3D in vitro model of cancer progression

The hallmark of tumours is the ability of cancerous cells to promote vascular growth, to disseminate and invade to distant organs. The metastatic process is heavily influenced by the extracellular matrix (ECM) density and composition of the surrounding tumour microenvironment. These microenvironmental cues, which include hypoxia, also regulate the angiogenic processes within a tumour, facilitating the spread of cancer cells. We engineered compartmentalized biomimetic colorectal tumouroids with stromal surrounds that comprised a range of ECM densities, composition and stromal cell populations. Recapitulating tissue ECM composition and stromal cell composition enhanced cancer cell invasion. Manipulation of ECM density was associated with an altered migration pattern from glandular buds (cellular aggregates) to epithelial cell sheets. Laminin appeared to be a critical component in regulating endothelial cell morphology and vascular network formation. Interestingly, the disruption of vascular networks by cancer cells was driven by changes in expression of several anti-angiogenic genes. Cancer cells cultured in our biomimetic tumouroids exhibited intratumoural heterogeneity that was associated with increased tumour invasion into the stroma. These findings demonstrate that our 3D in vitro tumour model exhibits biomimetic attributes that may permit their use in studying microenvironment clues of tumour progression and angiogenesis.

Normalization of the vasculature for treatment of cancer and other diseases

New vessel formation (angiogenesis) is an essential physiological process for embryologic development, normal growth, and tissue repair. Angiogenesis is tightly regulated at the molecular level. Dysregulation of angiogenesis occurs in various pathologies and is one of the hallmarks of cancer. The imbalance of pro- and anti-angiogenic signaling within tumors creates an abnormal vascular network that is characterized by dilated, tortuous, and hyperpermeable vessels. The physiological consequences of these vascular abnormalities include temporal and spatial heterogeneity in tumor blood flow and oxygenation and increased tumor interstitial fluid pressure. These abnormalities and the resultant microenvironment fuel tumor progression, and also lead to a reduction in the efficacy of chemotherapy, radiotherapy, and immunotherapy. With the discovery of vascular endothelial growth factor (VEGF) as a major driver of tumor angiogenesis, efforts have focused on novel therapeutics aimed at inhibiting VEGF activity, with the goal of regressing tumors by starvation. Unfortunately, clinical trials of anti-VEGF monotherapy in patients with solid tumors have been largely negative. Intriguingly, the combination of anti-VEGF therapy with conventional chemotherapy has improved survival in cancer patients compared with chemotherapy alone. These seemingly paradoxical results could be explained by a "normalization" of the tumor vasculature by anti-VEGF therapy. Preclinical studies have shown that anti-VEGF therapy changes tumor vasculature towards a more "mature" or "normal" phenotype. This "vascular normalization" is characterized by attenuation of hyperpermeability, increased vascular pericyte coverage, a more normal basement membrane, and a resultant reduction in tumor hypoxia and interstitial fluid pressure. These in turn can lead to an improvement in the metabolic profile of the tumor microenvironment, the delivery and efficacy of exogenously administered therapeutics, the efficacy of radiotherapy and of effector immune cells, and a reduction in number of metastatic cells shed by tumors into circulation in mice. These findings are consistent with data from clinical trials of anti-VEGF agents in patients with various solid tumors. More recently, genetic and pharmacological approaches have begun to unravel some other key regulators of vascular normalization such as proteins that regulate tissue oxygen sensing (PHD2) and vessel maturation (PDGFRβ, RGS5, Ang1/2, TGF-β). Here, we review the pathophysiology of tumor angiogenesis, the molecular underpinnings and functional consequences of vascular normalization, and the implications for treatment of cancer and nonmalignant diseases.

Cardioprotective effect of dexrazoxane in a rat model of myocardial infarction: anti-apoptosis and promoting angiogenesis

OBJECTIVES

Dexrazoxane (DZR) is a clinically approved agent for preventive treatment of doxorubicin-induced cardiotoxicity. The objective of this study was to investigate the cardioprotective effects of DZR in a rat model of myocardial infarction (MI).

METHODS

Sprague-Dawley rats were randomly divided into four groups: MI (n = 16), MI + DZR (n = 16), SHAM-operated (n = 14) and DZR-only (n = 9). MI animals were subjected to left anterior descending coronary artery ligation. DZR was administered as a single dose at 125 mg/kg intraperitoneally. Four weeks after treatment, cardiac function by echocardiography, infarct size, capillary density in the infarct border zone, bone marrow-derived endothelial progenitor cells (EPCs), and cardiac expression of Bax were measured.

RESULTS

Our results demonstrated that MI animals had compromised heart parameters. DZR treatment in MI animals resulted in reduction in infarct size (P = 0.013) and improved cardiac functions in terms of fractional shortening (P = 0.004) and ejection fraction (P = 0.004). The capillary density (P = 0.008) and bone marrow-derived EPCs (P < 0.05) were higher in the MI + DZR group than those in the untreated MI group. Bax expression was down-regulated in heart tissues of MI + DZR animals (P = 0.043).

CONCLUSIONS

Our study demonstrated that DZR exerted a cardioprotective effect in the rat model of MI, and the mechanism might be associated with anti-apoptosis and increased neovascularization.

Tasquinimod (ABR-215050), a quinoline-3-carboxamide anti-angiogenic agent, modulates the expression of thrombospondin-1 in human prostate tumors

Background

The orally active quinoline-3-carboxamide tasquinimod [ABR-215050; CAS number 254964-60-8), which currently is in a phase II-clinical trial in patients against metastatic prostate cancer, exhibits anti-tumor activity via inhibition of tumor angiogenesis in human and rodent tumors. To further explore the mode of action of tasquinimod, in vitro and in vivo experiments with gene microarray analysis were performed using LNCaP prostate tumor cells. The array data were validated by real-time semiquantitative reversed transcriptase polymerase chain reaction (sqRT-PCR) and protein expression techniques.

Results

One of the most significant differentially expressed genes both in vitro and in vivo after exposure to tasquinimod, was thrombospondin-1 (TSP1). The up-regulation of TSP1 mRNA in LNCaP tumor cells both in vitro and in vivo correlated with an increased expression and extra cellular secretion of TSP1 protein. When nude mice bearing CWR-22RH human prostate tumors were treated with oral tasquinimod, there was a profound growth inhibition, associated with an up-regulation of TSP1 and a down- regulation of HIF-1 alpha protein, androgen receptor protein (AR) and glucose transporter-1 protein within the tumor tissue. Changes in TSP1 expression were paralleled by an anti-angiogenic response, as documented by decreased or unchanged tumor tissue levels of VEGF (a HIF-1 alpha down stream target) in the tumors from tasquinimod treated mice.

Conclusions

We conclude that tasquinimod-induced up-regulation of TSP1 is part of a mechanism involving down-regulation of HIF1α and VEGF, which in turn leads to reduced angiogenesis via inhibition of the "angiogenic switch", that could explain tasquinimods therapeutic potential.