Dual targeting of tumor angiogenesis and chemotherapy by endostatin-cytosine deaminase-uracil phosphoribosyltransferase

Advances in monotherapy and combination therapy of S-1 for patients with advanced non-small cell lung cancer: a narrative review

Background and Objective

Both domestically and worldwide, non-small cell lung cancer (NSCLC) remain the leading cause of cancer-related death. As a fluorouracil derivative, S-1 which shows good efficacy and with few adverse effects have been widely confirmed in many solid tumors that it can provide a glimmer of hope for advanced NSCLC patients. We performed a review to explore the results of previous clinical studies of S-1 monotherapy as well as combined therapy involving S-1 in patients with advanced NSCLC.

Methods

A literature search was conducted in Medline and PubMed databases using the keywords "S-1" AND "Advanced lung cancer" OR "Pharmacological mechanism".

Key Content and Findings

A number of phase II clinical studies have reported on the favorable efficacy and excellent safety profiles of S-1 monotherapy in first-line or in posterior-line treatment for advanced NSCLC. In regard to S-1 in combination with chemotherapy, a number of phase II/III clinical studies have found the objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) of these regimens are similar to or better than immunological monotherapy with fewer adverse effects. In the case of S-1 combined with anti-vascular therapy, a number of phase II single-arm clinical studies have found that S-1 combined with bevacizumab, anlotinib and apatinib in advanced NSCLC, exhibits higher antitumor activity, less adverse effects for patients with advanced NSCLC. A phase II single-arm clinical study of gefitinib combined with S-1 had the ORR of 85.7% in the first-line treatment of advanced NSCLC. As for the combination of S-1 and immunotherapy, preliminary results of a phase II retrospective clinical trial demonstrated that the ORR was significantly better with S-1 sequential after immune checkpoint inhibitors (ICIs) than with S-1 alone.

Conclusions

The findings indicate promising effectiveness and minimal toxicity with S-1 monotherapy and S-1 containing combined therapy in patients with advanced NSCLC to provide a potential treatment option for advanced NSCLC.

Mechanisms of Myocardial Ischemia in Cancer Patients: A State-of-the-Art Review of Obstructive Versus Non-Obstructive Causes

In patients with cancer, myocardial infarction (MI) has distinct features and mechanisms compared to the non-oncology population. Triggers of myocardial ischemia specific to the oncology population have been increasingly identified. Coronary plaque disruption, coronary vasospasm, coronary microvascular dysfunction, spontaneous coronary artery dissection, and coronary oxygen supply-demand mismatch are all causes of MI that have been shown to have specific triggers related to either the treatments or complications of cancer. MI can occur in the presence or absence of atherosclerotic coronary artery disease (CAD). MI with nonobstructive CAD (MINOCA) is a heterogeneous syndrome that has distinct pathophysiology and different epidemiology from MI with significant CAD (MI-CAD). Recognition and differentiation of MI-CAD and MINOCA is essential in the oncology population, due to unique etiology and impact on diagnosis, management, and overall outcomes. There are currently no reports in the literature concerning MINOCA as a unified syndrome in oncology patients. The purpose of this review is to analyze the literature for studies related to known triggers of myocardial ischemia in cancer patients, with a focus on MINOCA. We propose that certain cancer treatments can induce MINOCA-like states, and further research is warranted to investigate mechanisms that may be unique to certain cancer states and types of treatment.

Gene-Directed Enzyme/Prodrug Therapy of Rat Brain Tumor Mediated by Human Mesenchymal Stem Cell Suicide Gene Extracellular Vesicles In Vitro and In Vivo

Simple Summary

Extracellular vesicles— exosomes—secreted by human mesenchymal stem/stromal cells are able to cross the blood–brain barrier and internalize glioblastoma cells. We prepared exosomes possessing a gene message, the product of which is able to convert nontoxic 5-fluorocytosine to cytotoxic drug 5-fluorouracil. Such therapeutic exosomes administered intranasally, intraperitoneally, or subcutaneously to rats bearing intracerebral glioblastoma cells inhibited their growth. The treatment cured a significant number of animals.

Abstract

MSC-driven, gene-directed enzyme prodrug therapy (GDEPT) mediated by extracellular vesicles (EV) represents a new paradigm—cell-free GDEPT tumor therapy. In this study, we tested the efficacy of yeast cytosine deaminase::uracilphosphoribosyl transferase (yCD::UPRT-MSC)-exosomes, in the form of conditioned medium (CM) to inhibit the growth of C6 glioblastoma cells both in vitro and in vivo. MSCs isolated from human adipose tissue, umbilical cord, or dental pulp engineered to express the yCD::UPRT gene secreted yCD::UPRT-MSC-exosomes that in the presence of the prodrug 5-fluorocytosine (5-FC), inhibited the growth of rat C6 glioblastoma cells and human primary glioblastoma cells in vitro in a dose-dependent manner. CM from these cells injected repeatedly either intraperitoneally (i.p.) or subcutaneously (s.c.), applied intranasally (i.n.), or infused continuously by an ALZET osmotic pump, inhibited the growth of cerebral C6 glioblastomas in rats. A significant number of rats were cured when CM containing yCD::UPRT-MSC-exosomes conjugated with 5-FC was repeatedly injected i.p. or applied i.n. Cured rats were subsequently resistant to challenges with higher doses of C6 cells. Our data have shown that cell-free GDEPT tumor therapy mediated by the yCD::UPRT-MSC suicide gene EVs for high-grade glioblastomas represents a safer and more practical approach that is worthy of further investigation.

Expression and purification of a recombinant ELRL-MAP30 with dual-targeting anti-tumor bioactivity

MAP30 (Momordica antiviral protein 30kD) is a single-chain Ⅰ-type ribosome inactivating protein with a variety of biological activities, including anti-tumor ability. It was reported that MAP30 would serve as a novel and relatively safe agent for prophylaxis and treatment of liver cancer. To determine whether adding two tumor targeting peptides could improve the antitumor activities of MAP30, we genetically modified MAP30 with an RGD motif and a EGFRi motif, which is a ligand with high affinity for αvβ3 integrins and with high affinity for EGFR. The recombinant protein ELRL-MAP30 (rELRL-MAP30) containing a GST-tag was expressed in E. coli. The rELRL-MAP30 was highly expressed in the soluble fraction after induction with 0.15 mM IPTG for 20 h at 16 °C. The purified rELRL-MAP30 appeared as a band on SDS-PAGE. It was identified by western blotting. Cytotoxicity of recombinant protein to HepG2, MDA-MB-231, HUVEC and MCF-7 cells was detected by MTT analysis. Half maximal inhibitory concentration (IC₅₀) values were 54.64 μg/mL, 70.13 μg/mL, 146 μg/mL, 466.4 μg/mL, respectively. Proliferation inhibition assays indicated that rELRL-MAP30 could inhibit the growth of Human liver cancer cell HepG2 effectively. We found that rELRL-MAP30 significantly induced apoptosis in liver cancer cells, as evidenced by nuclear staining of DAPI. In addition, rELRL-MAP30 induced apoptosis in human liver cancer HepG2 cells by up-regulation of Bax as well as down-regulation of Bcl-2. Migration of cell line were markedly inhibited by rELRL-MAP30 in a dose-dependent manner compared to the recombinant MAP30 (rMAP30). In summary, the fusion protein displaying extremely potent cytotoxicity might be highly effective for tumor therapy.

Natural products remodel cancer-associated fibroblasts in desmoplastic tumors

Desmoplastic tumors have an abundance of stromal cells and the extracellular matrix which usually result in therapeutic resistance. Current treatment prescriptions for desmoplastic tumors are usually not sufficient to eliminate the malignancy. Recently, through modulating cancer-associated fibroblasts (CAFs) which are the most abundant cell type among all stromal cells, natural products have improved chemotherapies and the delivery of nanomedicines to the tumor cells, showing promising ability to improve treatment effects on desmoplastic tumors. In this review, we discussed the latest advances in inhibiting desmoplastic tumors by modeling CAFs using natural products, highlighting the potential therapeutic abilities of natural products in targeting CAFs for cancer treatment.

Mechanical Cues Affect Migration and Invasion of Cells From Three Different Directions

Cell migration and invasion is a key driving factor for providing essential cellular functions under physiological conditions or the malignant progression of tumors following downward the metastatic cascade. Although there has been plentiful of molecules identified to support the migration and invasion of cells, the mechanical aspects have not yet been explored in a combined and systematic manner. In addition, the cellular environment has been classically and frequently assumed to be homogeneous for reasons of simplicity. However, motility assays have led to various models for migration covering only some aspects and supporting factors that in some cases also include mechanical factors. Instead of specific models, in this review, a more or less holistic model for cell motility in 3D is envisioned covering all these different aspects with a special emphasis on the mechanical cues from a biophysical perspective. After introducing the mechanical aspects of cell migration and invasion and presenting the heterogeneity of extracellular matrices, the three distinct directions of cell motility focusing on the mechanical aspects are presented. These three different directions are as follows: firstly, the commonly used invasion tests using structural and structure-based mechanical environmental signals; secondly, the mechano-invasion assay, in which cells are studied by mechanical forces to migrate and invade; and thirdly, cell mechanics, including cytoskeletal and nuclear mechanics, to influence cell migration and invasion. Since the interaction between the cell and the microenvironment is bi-directional in these assays, these should be accounted in migration and invasion approaches focusing on the mechanical aspects. Beyond this, there is also the interaction between the cytoskeleton of the cell and its other compartments, such as the cell nucleus. In specific, a three-element approach is presented for addressing the effect of mechanics on cell migration and invasion by including the effect of the mechano-phenotype of the cytoskeleton, nucleus and the cell's microenvironment into the analysis. In precise terms, the combination of these three research approaches including experimental techniques seems to be promising for revealing bi-directional impacts of mechanical alterations of the cellular microenvironment on cells and internal mechanical fluctuations or changes of cells on the surroundings. Finally, different approaches are discussed and thereby a model for the broad impact of mechanics on cell migration and invasion is evolved.

A pH-Sensitive Prodrug Nanocarrier Based on Diosgenin for Doxorubicin Delivery to Efficiently Inhibit Tumor Metastasis

BACKGROUND

The metastasis, one of the biggest barriers in cancer therapy, is the leading cause of tumor deterioration and recurrence. The anti.-metastasis has been considered as a feasible strategy for clinical cancer management. It is well known that diosgenin could inhibit tumor metastasis and doxorubicin (DOX) could induce tumor apoptosis. However, their efficient delivery remains challenging.

PURPOSE

To address these issues, a novel pH-sensitive polymer-prodrug based on diosgenin nanoparticles (NPs) platform was developed to enhance the efficiency of DOX delivery (DOX/NPs) for synergistic therapy of cutaneous melanoma, the most lethal form of skin cancer with high malignancy, early metastasis and high mortality.

METHODS AND RESULTS

The inhibitory effect of DOX/NPs on tumor proliferation and migration was superior to that of NPs or free DOX. What is more, DOX/NPs could combine mitochondria-associated metastasis and apoptosis with unique internalization pathway of carrier to fight tumors. In addition, biodistribution experiments proved that DOX/NPs could efficiently accumulate in tumor sites through enhancing permeation and retention (EPR) effect compared with free DOX. Importantly, the data from in vivo experiment revealed that DOX/NPs without heart toxicity significantly inhibited tumor metastasis by exerting synergistic therapeutic effect, and reduced tumor volume and weight by inducing apoptosis.

CONCLUSION

The nanocarrier DOX/NPs with satisfying pharmaceutical characteristics based on the establishment of two different functional agents is a promising strategy for synergistically enhancing effects of cancer therapy.

Speckle-Tracking Echocardiography for Cardioncological Evaluation in Bevacizumab-Treated Colorectal Cancer Patients

Angiogenesis inhibitor Bevacizumab (BVZ) may lead to the development of adverse effects, including hypertension and cardiac ischemia. Whether assessment of changes in myocardial strain by two-dimensional speckle-tracking echocardiography (2D-STE) can be of value in detecting BVZ-mediated cardiotoxicity at an earlier stage is not known. We investigated whether 2D-STE can non-invasively detect early evidence of cardiotoxicity in metastatic colorectal cancer (mCRC) patients treated with BVZ. Between January and June 2019, 25 consecutive patients (71.8 ± 7.5 year/old, 17 males) with mCRC were prospectively enrolled. Patients underwent physical examination, blood tests, and conventional 2D-transthoracic echocardiography implemented with 2D-STE analysis, at baseline and at 3 and 6 months following treatment with BVZ (15 mg/kg every 15 days) + 5-fluorouracil/folinic acid plus oxaliplatin (FOLFOX i.v.). At 6-month follow-up, we assessed occurrence of global longitudinal strain (GLS) impairment (> 15% decrease in GLS compared with baseline) as primary end-point and a new-onset systemic hypertension (secondary end-point). On average, GLS showed a progressive significant impairment after BVZ, from - 17.4 ± 3.2% at baseline to - 16 ± 2.9% (p = 0.003) at 6-month follow-up; > 15% decrease in GLS (primary end-point) was detected in 9 patients (36%). All other strain parameters remained unchanged. New-onset systemic hypertension (secondary end-point) was diagnosed in five patients (20%). No significant changes were observed in serial high-sensitivity cardiac troponin I measurements. No patient developed significant changes in LV size or LV ejection fraction; no case of clinically symptomatic HF was observed during BVZ-treatment. Measurement of GLS by 2D-STE analysis can effectively detect BVZ-mediated cardiotoxicity at an early stage.

Functional Interplay Between Collagen Network and Cell Behavior Within Tumor Microenvironment in Colorectal Cancer

Colorectal cancer is the second most common cancer diagnosed in men and the third most commonly occurring in women worldwide. Interactions between cells and the surrounding extracellular matrix (ECM) are involved in tumor development and progression of many types of cancer. The organization of the ECM molecules provides not only physical scaffoldings and dynamic network into which cells are embedded but also allows the control of many cellular behaviors including proliferation, migration, differentiation, and survival leading to homeostasis and morphogenesis regulation. Modifications of ECM composition and mechanical properties during carcinogenesis are critical for tumor initiation and progression. The core matrisome consists of five classes of macromolecules, which are collagens, laminins, fibronectin, proteoglycans, and hyaluronans. In most tissues, fibrillar collagen is the major component of ECM. Cells embedded into fibrillar collagen interact with it through their surface receptors, such as integrins and discoidin domain receptors (DDRs). On the one hand, cells incorporate signals from ECM that modify their functionalities and behaviors. On the other hand, all cells within tumor environment (cancer cells, cancer-associated fibroblasts, endothelial cells, and immune cells) synthesize and secrete matrix macromolecules under the control of multiple extracellular signals. This cell-ECM dialog participates in a dynamic way in ECM formation and its biophysical and biochemical properties. Here, we will review the functional interplay between cells and collagen network within the tumor microenvironment during colorectal cancer progression.

Role of renin-angiotensin system antagonists in the prevention of bevacizumab- and sunitinib-mediated cardiac dysfunction

Although anticancer systemic therapy agents clearly lead to improved survival in patients with cancer, these can come at the cost of serious complications including cardiotoxicity. Two types of targeted systemic therapies currently in use for colorectal cancer (CRC) and renal cell cancer (RCC), respectively, include the vascular endothelial growth factor inhibitor bevacizumab (BVZ) and the tyrosine kinase inhibitor sunitinib (SNT). Despite the beneficial effects of BVZ and SNT in improving clinical outcomes in the settings of CRC and RCC, there is an increased risk of cardiac dysfunction. The aim of the present study was to determine whether prophylactic administration of renin-angiotensin system (RAS) inhibitors would attenuate the cardiotoxic side effects of BVZ or SNT in a chronic in vivo murine model. A total of 194 wild-type C57Bl/6 male mice received: 1) 0.9% saline, 2) BVZ (10 mg·kg−1·wk−1), or 3) SNT (40 mg·kg−1·day−1) for 4 wk. Within each arm, mice received daily prophylactic treatment with hydralazine (0.05 mg/ml), aliskiren (50 mg/kg), perindopril (4 mg/kg), or valsartan (2 mg/kg). Although hydralazine effectively lowered blood pressure in BVZ- or SNT-treated mice, it did not prevent left ventricular systolic dysfunction. Prophylactic administration of aliskiren, perindopril, or valsartan prevented adverse cardiovascular remodeling in mice treated with either BVZ or SNT. The addition of RAS antagonists also downregulated expression of phosphorylated p38 and Bcl-2-like 19-kDa interacting protein 3 in SNT-treated mice. In our chronic in vivo murine model, RAS antagonists partially attenuated the development of BVZ- or SNT-mediated cardiac dysfunction. Future clinical studies are warranted to investigate the cardioprotective effects of prophylactic treatment with RAS inhibitors in the settings of CRC and RCC.

NEW & NOTEWORTHY In the evolving field of cardio-oncology, bevacizumab and sunitinib improve clinical outcomes in the settings of metastatic colorectal cancer and renal cell cancer, respectively. These anticancer drugs, however, are associated with an increased risk of cardiotoxicity. The prophylactic administration of renin-angiotensin system antagonists is partially cardioprotective against bevacizumab- and sunitinib-mediated cardiac dysfunction.

Conjugation of gold nanoparticles and recombinant human endostatin modulates vascular normalization via interruption of anterior gradient 2-mediated angiogenesis

Several studies have revealed the potential of normalizing tumor vessels in anti-angiogenic treatment. Recombinant human endostatin is an anti-angiogenic agent which has been applied in clinical tumor treatment. Our previous research indicated that gold nanoparticles could be a nanoparticle carrier for recombinant human endostatin delivery. The recombinant human endostatin-gold nanoparticle conjugates normalized vessels, which improved chemotherapy. However, the mechanism of recombinant human endostatin-gold nanoparticle-induced vascular normalization has not been explored. Anterior gradient 2 has been reported to be over-expressed in many malignant tumors and involved in tumor angiogenesis. To date, the precise efficacy of recombinant human endostatin-gold nanoparticles on anterior gradient 2-mediated angiogenesis or anterior gradient 2-related signaling cohort remained unknown. In this study, we aimed to explore whether recombinant human endostatin-gold nanoparticles could normalize vessels in metastatic colorectal cancer xenografts, and we further elucidated whether recombinant human endostatin-gold nanoparticles could interrupt anterior gradient 2-induced angiogenesis. In vivo, it was indicated that recombinant human endostatin-gold nanoparticles increased pericyte expression while inhibit vascular endothelial growth factor receptor 2 and anterior gradient 2 expression in metastatic colorectal cancer xenografts. In vitro, we uncovered that recombinant human endostatin-gold nanoparticles reduced cell migration and tube formation induced by anterior gradient 2 in human umbilical vein endothelial cells. Treatment with recombinant human endostatin-gold nanoparticles attenuated anterior gradient 2-mediated activation of MMP2, cMyc, VE-cadherin, phosphorylation of p38, and extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) in human umbilical vein endothelial cells. Our findings demonstrated recombinant human endostatin-gold nanoparticles might normalize vessels by interfering anterior gradient 2-mediated angiogenesis in metastatic colorectal cancer.

A tumor vessel-targeting fusion protein elicits a chemotherapeutic bystander effect in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease characterized by a prominent desmoplastic stroma that may constrain tumor progression but also limit the access of therapeutic drugs. In this study, we explored a tumor-targeting strategy that enlists an engineered anti-angiogenic protein consisting of endostatin and cytosine deaminase linked to uracil phosphoribosyltransferase (EndoCD). This protein selectively binds to tumor vessels to compromise tumor angiogenesis and converts the non-toxic 5-fluorocytosine (5-FC) to the cytotoxic 5-fluorouracil to produce a chemotherapeutic bystander effect at the pancreatic tumor site. We found that resveratrol increased the protein stability of EndoCD through suppression of chymotrypsin-like proteinase activity and synergistically enhances EndoCD-mediated 5-FC-induced cell killing. In various PDAC mouse models, the EndoCD/5-FC/resveratrol regimen decreased intratumoral vascular density and stroma formation and enhances apoptosis in tumors cells as well as in surrounding endothelial, pancreatic stellate, and immune cells, leading to reduced tumor growth and extended survival. Thus, the EndoCD/5-FC/resveratrol combination may be an effective treatment option for PDAC.

Targeted antitumor prodrug therapy using CNGRC-yCD fusion protein in combination with 5-fluorocytosine

Background

The enzyme-prodrug system is considered a promising tool for tumor treatment when conjugated with a targeting molecule. The asparagine-glycine-arginine (NGR) motif is a developing and interesting targeting peptide that could specifically bind to aminopeptidase N (APN), which is an NGR receptor expressed on the cell membrane of angiogenic endothelial cells and a number of tumor cells within the tumor tissues. The objective of this study was to develop a novel targeted enzyme-prodrug system using 5-fluorocytosine (5-FC) and an NGR-containing peptide fused with yeast cytosine deaminase (yCD), i.e. CNGRC-yCD fusion protein, to target APN-expressing cells within the tumor tissues and to convert 5-FC into 5-fluorouracil (5-FU) to kill tumors.

Results

Both yCD and CNGRC-yCD proteins were cloned into the pET28a vector and expressed by an Escherichia coli host. Both yCD and CNGRC-yCD proteins were purified and the yields were approximately 20 mg/L with over 95 % purity. The binding assay demonstrated that the CNGRC-yCD fusion protein had specific binding affinity toward purified APN recombinant protein and high-APN-expressing cells, including human endothelial cells (HUVECs) and various types of human tumor cell lines, but not low-APN-expressing tumor cell lines. Moreover, the enzyme activity and cell viability assay showed that the CNGRC-yCD fusion protein could effectively convert 5-FC into 5-FU and resulted in significant cell death in both high-APN-expressing tumor cells and HUVECs.

Conclusions

This study successfully constructs a new targeting enzyme-prodrug system, CNGRC-yCD fusion protein/5-FC. Systematic experiments demonstrated that the CNGRC-yCD protein retained both the APN-binding affinity of NGR and the enzyme activity of yCD to convert 5-FC into 5-FU. The combined treatment of the CNGRC-yCD protein with 5-FC resulted in the significantly increased cell death of high-APN-expressing cells as compared to that of low-APN-expressing cells.

Carglumic acid promotes apoptosis and suppresses cancer cell proliferation in vitro and in vivo

Drug repurposing is a therapeutic strategy that applies drugs to treat different diseases based on new therapeutic function. Carglumic acid (Carbaglu; Orphan Europe) is an orphan drug approved by the FDA for hyperammonemia. Administration of carglumic acid for treatment of hyperammonemia has few side effects and has been used for 10 years to effectively treat hyperammonemia symptoms of both adult and pediatric patients. Here, we tested the potential of carglumic acid to be repurposed as an anticancer agent and showed that carglumic acid promotes apoptosis and inhibits cancer cell growth ina wide variety of human cancers, including pancreatic ductal adenocarcinoma, triple-negative breast cancer (TNBC), hepatoma, and lung cancer. Our data from in vivo models indicates that orally taking 10% of the carglumic acid dose currently used for the treatment of hyperammonemia ise ffective to suppress the growth of pancreatic ductal adenocarcinomaand TNBC. If given intravenously, only 5% of the carglumic acid doseis needed to be effective against TNBC. These findings suggest that carglumic acid may serve as a safe and effective therapeutic to treat both TNBC and pancreatic cancer.

The utility of cardiac biomarkers and echocardiography for the early detection of bevacizumab- and sunitinib-mediated cardiotoxicity

The recent introduction of novel anticancer therapies, including bevacizumab (BVZ) and sunitinib (SNT), is associated with an increased risk of cardiotoxicity. However, early identification of left ventricular (LV) systolic dysfunction may facilitate dose modification and avoid the development of advanced heart failure. Using a murine model of BVZ- and SNT-mediated cardiotoxicity, we investigated whether cardiac biomarkers and/or tissue velocity imaging (TVI) using echocardiography can detect early changes in cardiac function, before a decrease in LV ejection fraction is identified. A total of 75 wild-type C57Bl/6 male mice were treated with either 0.9% saline, BVZ, or SNT. Serial monitoring of blood pressure, high-sensitivity troponin I, and echocardiographic indexes were performed over a 14-day study period, after which the mice were euthanized for histological and biochemical analyses. Mice treated with either BVZ or SNT developed systemic hypertension as early as day 7, which increased by day 14. Cardiac biomarkers, specifically high-sensitivity troponin I, were not predictive of early LV systolic dysfunction. Although conventional LV ejection fraction values decreased at day 13 in mice treated with either BVZ or SNT, TVI confirmed early LV systolic dysfunction at day 8. Histological and biochemical analysis demonstrated loss of cellular integrity, increased oxidative stress, and increased cardiac apoptosis in mice treated with BVZ or SNT therapy at day 14. In a murine model of BVZ- or SNT-mediated cardiomyopathy, noninvasive assessment by TVI detected early LV systolic dysfunction before alterations in conventional echocardiographic indexes.

Genetically engineered endostatin-lidamycin fusion proteins effectively inhibit tumor growth and metastasis

Background

Endostatin (ES) inhibits endothelial cell proliferation, migration, invasion, and tube formation. It also shows antiangiogenesis and antitumor activities in several animal models. Endostatin specifically targets tumor vasculature to block tumor growth. Lidamycin (LDM), which consists of an active enediyne chromophore (AE) and a non-covalently bound apo-protein (LDP), is a member of chromoprotein family of antitumor antibiotics with extremely potent cytotoxicity to cancer cells. Therefore, we reasoned that endostatin-lidamycin (ES-LDM) fusion proteins upon energizing with enediyne chromophore may obtain the combined capability targeting tumor vasculature and tumor cell by respective ES and LDM moiety.

Methods

In this study, we designed and obtained two new endostatin-based fusion proteins, endostatin-LDP (ES-LDP) and LDP-endostatin (LDP-ES). In vitro, the antiangiogenic effect of fusion proteins was determined by the wound healing assay and tube formation assay and the cytotoxicity of their enediyne-energized analogs was evaluated by CCK-8 assay. Tissue microarray was used to analyze the binding affinity of LDP, ES or ES-LDP with specimens of human lung tissue and lung tumor. The in vivo efficacy of the fusion proteins was evaluated with human lung carcinoma PG-BE1 xenograft and the experimental metastasis model of 4T1-luc breast cancer.

Results

ES-LDP and LDP-ES disrupted the formation of endothelial tube structures and inhibited endothelial cell migration. Evidently, ES-LDP accumulated in the tumor and suppressed tumor growth and metastasis. ES-LDP and ES show higher binding capability than LDP to lung carcinoma; in addition, ES-LDP and ES share similar binding capability. Furthermore, the enediyne-energized fusion protein ES-LDP-AE demonstrated significant efficacy against lung carcinoma xenograft in athymic mice.

Conclusions

The ES-based fusion protein therapy provides some fundamental information for further drug development. Targeting both tumor vasculature and tumor cells by endostatin-based fusion proteins and their enediyne-energized analogs probably provides a promising modality in cancer therapy.

Beyond anti-VEGF: dual-targeting antiangiogenic and antiproliferative therapy

Antiangiogenesis is a promising antitumor strategy that inhibits tumor vascular formation to suppress tumor growth. Specifically, targeting VEGF has shown therapeutic benefits in many cancer types, leading to its approval as the first antiangiogenic drug by the Food and Drug Administration in the United States. It is known, however, that patients will experience unfavorable side effects as the VEGF and/or VEGF receptor signaling pathway is also required for homeostasis in normal tissues. Moreover, due to the cytostatic nature of antiangiogenic, cancer cells that are not killed by these drugs later develop an even more malignant phenotype, resulting in tumor invasion and metastasis. Although there have been many attempts to reduce drug resistance and increase therapeutic efficacy by combining antiangiogenic drugs with chemotherapy, the cumulative toxicity of antiangiogenic combinations limits their feasibility as treatments, as chronic angiogenesis inhibition typically reduces the antitumor effect of the co-administered chemotherapeutics. To overcome these problems, it is critical to explore new strategies that limit tumor resistance and side effects and also increase the exposure of chemotherapy drugs at the tumor site. Here, we review current understanding of antiangiogenic drugs and introduce a new combination strategy that links direct antiangiogenic protein and enzyme prodrug system with dual-targeting antiangiogenic and antiproliferative therapeutic effect in tumor microenvironment. This strategy has the potential to overcome these clinical hindrances and may serve as a paradigm for the next generation of antiangiogenic drugs.

5-Fluorocytosine combined with Fcy-hEGF fusion protein targets EGFR-expressing cancer cells

Human epithelial cancers account for approximately 50% of all cancer deaths. This type of cancer is characterized by excessive activation and expression of the epidermal growth factor receptor (EGFR). The EGFR pathway is critical for cancer cell proliferation, survival, metastasis and angiogenesis. The EGF-EGFR signaling pathway has been validated as an important anticancer drug target. Increasing numbers of targeted therapies against this pathway have been either approved or are currently under development. Here, we adopted a prodrug system that uses 5-fluorocytosine (5-FC) and human EGF (hEGF) fused with yeast cytosine deaminase (Fcy) to target EGFR-overexpressing cancer cells and to convert 5-FC to a significantly more toxic chemotherapeutic, 5-fluorouracil (5-FU). We cloned and purified the Fcy-hEGF fusion protein from Pichia pastoris yeast. This fusion protein specifically binds to EGFR with a similar affinity as hEGF, approximately 10 nM. Fcy-hEGF binds tightly to A431 and MDA-MB-468 cells, which overexpress EGFR, but it binds with a lower affinity to MDA-MB-231 and MCF-7, which express lower levels of EGFR. Similarly, the viability of EGFR-expressing cells was suppressed by Fcy-hEGF in the presence of increasing concentrations of 5-FC, and the IC(50) values for A431 and MDA-MB-468 were approximately 10-fold lower than those of MDA-MB-231 and MCF-7. This novel prodrug system, Fcy-hEGF/5-FC, might represent a promising addition to the available class of inhibitors that specifically target EGFR-expressing cancers.

Suicide gene therapy in cancer: where do we stand now?

Suicide gene therapy is based on the introduction into tumor cells of a viral or a bacterial gene, which allows the conversion of a non-toxic compound into a lethal drug. Although suicide gene therapy has been successfully used in a large number of in vitro and in vivo studies, its application to cancer patients has not reached the desirable clinical significance. However, recent reports on pre-clinical cancer models demonstrate the huge potential of this strategy when used in combination with new therapeutic approaches. In this review, we summarize the different suicide gene systems and gene delivery vectors addressed to cancer, with particular emphasis on recently developed systems and associated bystander effects. In addition, we review the different strategies that have been used in combination with suicide gene therapy and provide some insights into the future directions of this approach, particularly towards cancer stem cell eradication.

Targeted endostatin-cytosine deaminase fusion gene therapy plus 5-fluorocytosine suppresses ovarian tumor growth

There are currently no effective therapies for cancer patients with advanced ovarian cancer, therefore developing an efficient and safe strategy is urgent. To ensure cancer-specific targeting, efficient delivery, and efficacy, we developed an ovarian cancer-specific construct (Survivin-VISA-hEndoyCD) composed of the cancer specific promoter survivin in a transgene amplification vector (VISA; VP16-GAL4-WPRE integrated systemic amplifier) to express a secreted human endostatin-yeast cytosine deaminase fusion protein (hEndoyCD) for advanced ovarian cancer treatment. hEndoyCD contains an endostatin domain that has tumor-targeting ability for anti-angiogenesis and a cytosine deaminase domain that converts the prodrug 5-fluorocytosine (5-FC) into the chemotherapeutic drug, 5-fluorouracil. Survivin-VISA-hEndoyCD was found to be highly specific, selectively express secreted hEndoyCD from ovarian cancer cells, and induce cancer-cell killing in vitro and in vivo in the presence of 5-FC without affecting normal cells. In addition, Survivin-VISA-hEndoyCD plus 5-FC showed strong synergistic effects in combination with cisplatin in ovarian cancer cell lines. Intraperitoneal (i.p.) treatment with Survivin-VISA-hEndoyCD coupled with liposome attenuated tumor growth and prolonged survival in mice bearing advanced ovarian tumors. Importantly, there was virtually no severe toxicity when hEndoyCD is expressed by Survivin-VISA plus 5-FC compared with CMV plus 5-FC. Thus, the current study demonstrates an effective cancer-targeted gene therapy that is worthy of development in clinical trials for treating advanced ovarian cancer.

Antiangiogenic and anticancer molecules in cartilage

Cartilage is one of the very few naturally occurring avascular tissues where lack of angiogenesis is the guiding principle for its structure and function. This has attracted investigators who have sought to understand the biochemical basis for its avascular nature, hypothesising that it could be used in designing therapies for treating cancer and related malignancies in humans through antiangiogenic applications. Cartilage encompasses primarily a specialised extracellular matrix synthesised by chondrocytes that is both complex and unique as a result of the myriad molecules of which it is composed. Of these components, a few such as thrombospondin-1, chondromodulin-1, the type XVIII-derived endostatin, SPARC (secreted protein acidic and rich in cysteine) and the type II collagen-derived N-terminal propeptide (PIIBNP) have demonstrated antiangiogenic or antitumour properties in vitro and in vivo preclinical trials that involve several complicated mechanisms that are not completely understood. Thrombospondin-1, endostatin and the shark-cartilage-derived Neovastat preparation have also been investigated in human clinical trials to treat several different kinds of cancers, where, despite the tremendous success seen in preclinical trials, these molecules are yet to show success as anticancer agents. This review summarises the current state-of-the-art antiangiogenic characterisation of these molecules, highlights their most promising aspects and evaluates the future of these molecules in antiangiogenic applications.