The Challenges of Recombinant Endostatin in Clinical Application: Focus on the Different Expression Systems and Molecular Bioengineering

Inhibitory effect of Endostar on HIF-1 with upregulation of MHC-I in lung cancer cells

Endostar is a human recombinant endostatin which is an attractive anti-angiogenesis protein. Because inefficient antigen presenting MHC class I expression (which can be downregulated by HIF-1) is an important strategy for cancer immune evasion, besides its anti-angiogenesis effect, it remains unclear whether Endostar has an inhibitory effect on HIF-1 expression by upregulating MHC class I expression in cancer cells to facilitate immunotherapies, including PD-1/PD-L1 inhibitors. In this study, A549 and NCI-H1299 lung cancer cells were treated with Endostar (6.25 μg/ml, 12.5 μg/ml, and 25 μg/ml, respectively). HIF-1 expression was detected by Immunocytochemistry and Western blot. Proteins of the MHC class I α-heavy chain and β2 m light chain, STAT3 and pSTAT3 were detected by Western blot. The mRNAs of MHC class I α-heavy chain and β2 m light chain were detected by RT-qPCR. It was shown that decreased expression of HIF-1 and promotion of β2-microglobulin were observed after Endostar treatment. In addition, elevated levels of MHC class I α-heavy chain mRNA and protein, as well as downregulation of STAT3 and pSTAT3, were also observed following Endostar treatment. Endostar inhibited HIF-1 expression in A549 and NCI-H1299 lung cancer cells, upregulated expression of MHC class I α-heavy chain and β2 m light chain, with the upregulation of STAT3 and pSTAT3, suggesting involvement of STAT3 pathway. It is important because only in combination with MHC class I on target cells can tumor antigenic peptides be recognized by CD8+ CTLs which destroy target cells. However, MHC class I is frequently deficient in cancer cells.

Decastatin, a Novel Non-Collagenous 1 Domain From Collagen Type X, Harbors a Specific Fragment With Antiangiogenic Properties

ABSTRACT

The NC1 domains of collagens have been shown to possess antiangiogenic potential and, therefore, are of therapeutic interest for cancer. However, endostatin and other NC1 domains have not been successful in clinical tests. Therefore, we used evolutionary conservation to perform molecular deconstruction of the domains to further understand their structure-activity relationship, thereby deciphering their antiangiogenic potential. Homology exploration revealed that collagen type X contains a highly interesting NC1 domain (decastatin), with several sequences showing significant homology with vastatin, which is a known collagen type VIII-derived NC1 domain. For comparison, endostatin and vastatin were split into fragments, some of which contained highly conserved regions. The testing of these peptides revealed that the peptides containing conserved regions induced signaling, and fragment 4 of decastatin showed the highest potency of all fragments, with a calculated inhibitory concentration value of 2.7 μM in the human umbilical vein endothelial cell-based tube formation assay, which is like that of an intact NC1 domain. Notably, the corresponding fragment from vastatin (V4) also inhibited tube formation, suggesting that this region is of therapeutic interest. In summary, we used evolutionary conservation to identify a novel NC1 domain of collagen type X, a collagen playing a role in angiogenesis of the growth plate. Furthermore, we provided data indicating that the antiangiogenic activity of NC1 domain-derived peptides reside within their conserved domains. As a result, we identified a fragment called Decastatin fragment 4 (D4) derived from the NC1 domain of collagen type X, and which has potent antiangiogenic activity.

Decoding Tumor Angiogenesis for Therapeutic Advancements: Mechanistic Insights

Tumor angiogenesis, the formation of new blood vessels within the tumor microenvironment, is considered a hallmark of cancer progression and represents a crucial target for therapeutic intervention. The tumor microenvironment is characterized by a complex interplay between proangiogenic and antiangiogenic factors, regulating the vascularization necessary for tumor growth and metastasis. The study of angiogenesis involves a spectrum of techniques, spanning from biomarker assessment to advanced imaging modalities. This comprehensive review aims to provide insights into the molecular intricacies, regulatory dynamics, and clinical implications of tumor angiogenesis. By delving into these aspects, we gain a deeper understanding of the processes driving vascularization in tumors, paving the way for the development of novel and effective antiangiogenic therapies in the fight against cancer.

Pre-clinical Efficacy and Safety Pharmacology of PEGylated Recombinant Human Endostatin

INTRODUCTION

This study aimed to outline the pre-clinical efficacy and safety pharmacology of PEGylated recombinant human endostatin (M2ES) according to the requirements of new drug application.

METHODS

The purity of M2ES was evaluated by using silver staining. Transwell migration assay was applied to detect the bioactivity of M2ES in vitro. The antitumor efficacy of M2ES was evaluated in an athymic nude mouse xenograft model of pancreatic cancer (Panc-1) and gastric cancer (MNK45). BALB/C mice were treated with different doses of M2ES (6, 12 and 24 mg/kg) intravenously, both autonomic activity and cooperative sleep were monitored before and after drug administration.

RESULTS

The apparent molecular weight of M2ES was about 50 kDa, and the purity was greater than 98%. Compared with the control group, M2ES significantly inhibits human micro-vascular endothelial cells (HMECs) migration in vitro. Notably, weekly administration of M2ES showed a significant antitumor efficacy when compared with the control group. Treatment of M2ES (24mg/kg or below) showed no obvious effect on both autonomic activity and hypnosis.

CONCLUSION

On the basis of the pre-clinical efficacy and safety pharmacology data of M2ES, M2ES can be authorized to carry out further clinical studies.

Combination Therapy in Cancer: Doxorubicin in Combination with an N-terminal Peptide of Endostatin Suppresses Angiogenesis and Stimulates Apoptosis in the Breast Cancer

The combination of chemotherapy drugs with angiogenesis inhibitors improves response and survival and reduces the cytotoxic side effects and drug resistance in patients compared to chemotherapy alone. Here, we investigated the efficacy of the concomitant administration of doxorubicin and a peptide derived from the N-terminal domain of Endostatin (called ES-SS) in the 4T1 mammary carcinoma tumor model. Tumor-bearing mice were divided into the control and three treatment groups, including ES-SS, doxorubicin, and the combination. Injections were performed daily for two weeks and tumor volumes were measured during the treatment. Immunohistochemical analysis of Ki-67, CD31, CD34, Bcl-2, p53 expression, and TUNEL assay were performed on tumor tissues at the end of treatment. Besides, molecular dynamics and docking simulations were performed. It was demonstrated that tumor growth was inhibited in mice treated with peptide plus doxorubicin more significantly than in each treatment alone (P<0.05). No weight loss or adverse effects were observed. Moreover, combination therapy was more effective in tumor angiogenesis suppression and apoptosis stimulation (P<0.05). Docking simulations by ClusPro server demonstrated that ES-SS binds to integrin α5β1, Transglu-taminase 2, and Matrix metalloproteinase 2 with more negative binding energy and hydrogen bonds compared to the native peptide. Generally, we proposed that ES-SS can augment the therapeutic efficacy of doxorubicin through angiogenesis prevention and apoptosis induction in breast tumor. Owing to the advantages of peptides to recombinant proteins or monoclonal antibodies, further preclinical and clinical evaluations of this combination strategy are worth taking into consideration.

Tolerance and Pharmacokinetics of Recombinant Human Endostatin Administered as Single-Dose or Multiple-Dose Infusions in Patients With Advanced Solid Tumors: A Phase I Clinical Trial

Objective: This study aimed to investigate the tolerance and pharmacokinetic characteristics of recombinant human endostatin (rh-endostatin) administered as single-dose or multiple-dose infusions in patients with advanced solid tumors. Methods: This phase I trial was designed as a single-center, single-arm, nonrandomized, open-label, dose-escalation study. The trial consisted of 2 parts: a single-dose part and a multiple-dose part, each with 3 dose comparison groups. Rh-endostatin was administered as an intravenous injection only once at a dose of 5 mg/m², 7.5 mg/m², or 10 mg/m² in the single-dose part and as a daily intravenous injection for 14 days at the same doses in the multiple-dose part. The serum pharmacokinetics, toxicity and immunogenicity of rh-endostatin were evaluated. Results: Dose-limiting toxicity (DLT) was not observed in any group. A few patients developed cardiotoxicity, such as QT prolongation or narrow arrhythmia. Other adverse events were slight coagulation abnormalities and haematological abnormalities. For rh-endostatin doses of 5 mg/m², 7.5 mg/m², and 10 mg/m², the mean C_max values in the single-dose part were 344 ± 38.7 ng/mL, 524 ± 157 ng/mL, and 800 ± 201 ng/mL, respectively, and the average AUC_0-t values were 3290 ± 3790 ng•h/mL, 4940 ± 4380 ng•h/mL, and 5050 ± 3980 ng•h/mL, respectively. The C_{max ss} values of the 3 doses in the multiple-dose part were 575 ± 270 ng/mL, 531 ± 106 ng/mL, and 864 ± 166 ng/mL, respectively, and the AUC_0-τ values were 3610 ± 1040 ng•h/mL, 3290 ± 1090 ng•h/mL, and 5180 ± 1210 ng•h/mL, respectively. The C_max of a single-dose regimen showed linear kinetic characteristics. The patients in the single-dose group were negative for serum antibodies against rh-endostatin, while one patient in the multiple-dose group was positive. Conclusions: Rh-endostatin as a daily intravenous injection for 14 days in patients with advanced solid tumors is safe and well tolerated, without DLT, at doses of 5 mg/m², 7.5 mg/m², and 10 mg/m². Serum antibodies against rh-endostatin were very low after multiple infusions. For phase II trials, the recommended rh-endostatin dose is 10 mg/m² as a daily intravenous injection for 14 days.

Inducing Angiogenesis, a Key Step in Cancer Vascularization, and Treatment Approaches

Angiogenesis is a term that describes the formation of new blood and lymphatic vessels from a pre-existing vasculature. This allows tumour cells to acquire sustenance in the form of nutrients and oxygen and the ability to evacuate metabolic waste. As one of the hallmarks of cancer, angiogenesis has been studied extensively in animal and human models to enable better understanding of cancer biology and the development of new anti-cancer treatments. Angiogenesis plays a crucial role in the process of tumour genesis, because solid tumour need a blood supply if they are to grow beyond a few millimeters in size. On the other hand, there is growing evidence that some solid tumour exploit existing normal blood supply and do not require a new vessel formation to grow and to undergo metastasis. This review of the literature will present the current understanding of this intricate process and the latest advances in the use of angiogenesis-targeting therapies in the fight against cancer.

Involvement of haptoglobin phenotypes and genotypes in non-muscle invasive bladder cancer: A possible prognostic marker for risk stratification

The association of haptoglobin (Hp) with various cancers has been reported and also it has been documented that the Hp phenotypes/genotypes have different functional ability. So, we examined phenotypes/genotypes of Hp in newly diagnosed, untreated non-muscle invasive bladder cancer (NMIBC) patients and investigated its prognostic value for risk stratification of the cancer. In eighty NMIBC patients and 80 healthy individuals the Hp genotypes and phenotypes were analyzed using polymerase chain reaction (PCR) and two-dimensional gel electrophoresis (2D-GE), respectively. Besides, the presence of the Hpα1, α2, and β chains in the sera was confirmed by Mass Spectrometry (MS). The frequencies of the 1-1 and 2-2 genotypes/phenotypes were respectively higher and lower in healthy subjects compared to the patients. Our results revealed that the 2-2 genotype/phenotype could increase the risk of NMIBC. There was a positive association between the 2-2 genotype/phenotype with the T category/grade of cancer (p<0.05). The present study implied a strong association between the Hp phenotypes and genotypes with NMIBC. It was found that the 2-2 genotype and phenotype could be a risk factor for NMIBC incidence, as well as, progression. This study introduced Hp genotyping as a possible cost-effective and precise method for prognosis of individuals at the risk of NMIBC.

Validation of an enzyme-linked immunosorbent assay (ELISA) for quantification of endostatin levels in mice as a biomarker of developing glomerulonephritis

Endostatin, the C-terminal fragment of type XVIII collagen, was shown to be one of the most potent endothelial cell-specific inhibitors of angiogenesis. As altered circulating endostatin concentration is associated with impaired kidney function, new tools for measuring endostatin in rodents may be helpful to further investigate and understand its role within kidney disease progression. A novel and commercially available ELISA for the quantification of mouse and rat endostatin was developed and validated according to international quality guidelines including the parameters specificity, robustness, accuracy, dilution linearity, precision, limit of detection (LOD) and lower limit of quantification (LLOQ). Endostatin and blood urea nitrogen (BUN) concentration were measured in mice with a glomerulonephritis phenotype. The validation revealed that within the range of 0.5–32 nmol/L the immunoassay is robust and highly specific for the measurement of rodent endostatin with high sensitivity (LOD 0.24 nmol/L, LLOQ 0.5 nmol/L) and good reproducibility (intra- and inter-assay CV <10%). Also accuracy and dilution linearity were within the range of acceptance. BCL2 transgenic and ETV6/RUNX1;BCL2 double transgenic mice develop a glomerulonephritis phenotype over time, which was displayed by staining of kidney sections. Even before full manifestation of disease serum endostatin concentration rises significantly, whereas BUN levels just slightly increase. This newly developed and commercially available ELISA provides a reliable and accurate tool for the quantification of mouse and rat endostatin and may give new perspectives in the investigation of the role of endostatin as an important and early biomarker for reduced kidney function. Measurement of endostatin concentration is recommended to be used as a superior biomarker for chronic kidney disease compared to BUN.

Are Integrins Still Practicable Targets for Anti-Cancer Therapy?

Correlative clinical evidence and experimental observations indicate that integrin adhesion receptors, in particular those of the αV family, are relevant to cancer cell features, including proliferation, survival, migration, invasion, and metastasis. In addition, integrins promote events in the tumor microenvironment that are critical for tumor progression and metastasis, including tumor angiogenesis, matrix remodeling, and the recruitment of immune and inflammatory cells. In spite of compelling preclinical results demonstrating that the inhibition of integrin αVβ3/αVβ5 and α5β1 has therapeutic potential, clinical trials with integrin inhibitors targeting those integrins have repeatedly failed to demonstrate therapeutic benefits in cancer patients. Here, we review emerging integrin functions and their proposed contribution to tumor progression, discuss preclinical evidence of therapeutic significance, revisit clinical trial results, and consider alternative approaches for their therapeutic targeting in oncology, including targeting integrins in the other cells of the tumor microenvironment, e.g., cancer-associated fibroblasts and immune/inflammatory cells. We conclude that integrins remain a valid target for cancer therapy; however, agents with better pharmacological properties, alternative models for their preclinical evaluation, and innovative combination strategies for clinical testing (e.g., together with immuno-oncology agents) are needed.

Successful treatment of brain radiation necrosis resulting from triple-negative breast cancer with Endostar and short-term hyperbaric oxygen therapy: a case report

Radiation necrosis (RN) is one of the complications of radiotherapy. Angiogenesis is a key factor underlying the development of RN, and Endostar, a safe and well-tolerated recombinant human endostatin, has been used to treat a variety of tumors. Thus far, however, no definitive reports on the use of Endostar for RN treatment have been reported. Here, we report the successful treatment of one patient with symptomatic brain radiation necrosis (BRN) using Endostar in combination with short-term hyperbaric oxygen therapy (HBO). One triple-negative breast cancer patient with recurrent brain metastatic lesions after standard chemoradiotherapy was referred to a specialty center outside our hospital for stereotaxic radiotherapy. Two months later, the patient showed deteriorating clinical symptoms, and magnetic resonance imaging (MRI) showed radiation necrosis with significant surrounding edema. The patient had a poor response to mannitol and steroids. After diagnosing this patient with BRN, we began short-term HBO therapy and intravenously administered Endostar for 4 cycles. The patient responded well to this strategy, showing rapidly and dramatically improved MRI findings and clinical symptoms. No tumor progression was observed at 10 months after treatment. Endostar in combination with short-term HBO therapy had marked effects on symptomatic BRN. However, additional large-scale, double-blinded, controlled trials are necessary to confirm the clinical effect of Endostar in combination with a short-term HBO therapy regimen on BRN.

A simple and high-throughput luciferase immunosorbent assay for both qualitative and semi-quantitative detection of anti-HIV-1 antibodies

In this study, we described an ultrasensitive and high-throughput luciferase immunosorbent assay (LISA) for qualitative and quantitative detection of anti-HIV-1 antibody. Anti-HIV antibody in serum or plasma samples was captured by protein A/G-coated microtiter plate and detected with crude cell lysates expressing Nanoluc luciferase (Nluc) enzyme fused with HIV-1 p24 or gp41 antigen without the need of protein purification. After the addition of furimazine substrate, anti-HIV antibodies were quantitatively measured as luciferase light units. LISA showed a wide linear range of detection and was about 10⁴-fold more sensitive than ELISA. For the detection of both anti-p24 and anti-gp41, LISA showed extraordinary sensitivity (99.5% and 100%, respectively) and equivalent specificity (100%). LISA could also monitor the change in the anti-HIV-1 antibody response over time in antiretroviral therapy (ART) treated individuals, and can sufficiently distinguish between recent and long-term HIV-1 infections. Our preliminary results indicate that LISA may provide a novel universal immunoassay platform for simultaneous HIV-1 detection, quantitative measurement of anti-HIV antibodies as well as the differentiation of HIV-1 infection stages.

Gene therapy of renal cancer using recombinant adeno-associated virus encoding human endostatin

Renal cell carcinoma (RCC) is characterized by robust angiogenesis during tumor development. Various therapies are not able completely eradicated tumor relapse. The present study targeted angiogenesis and developed a recombinant adeno-associated virus (rAAV) vector containing human endostatin gene for human kidney cancer gene therapy. Prophylactic and therapeutic RCC models were established in nude mice by subcutaneous inoculation of RCC cells and intra-muscular or intra-tumor injection of rAAV-Endostatin. The growth of xenograft tumors was evaluated by tumor volume and weight. The microvessel density (MVD) was used to measure the anti-angiogenesis effect of rAAV-Endostatin. The toxic effect of rAAV-Endostatin was also examined. In the therapeutic model, tumor-bearing mice with rAAV-Endostatin intra-tumor injection demonstrated slow tumor growth (32.63±9.75) compared with control groups with intratumoral rAAV-enhanced yellow florescent protein (EYFP) injections (21.50±11.42) and the RPMI-1640 group (21.75±10.48 days, for tumors to reach ~300 mm³). MVD of the xenografts treated with rAAV-Endostatin was 8.30±3.14/0.739 mm² whereas that of control groups was 13.87±4.09/0.739 mm² (rAVV-EYFP) and 13.76±3.50/0.739 mm² (RPMI-1640). No significant side effects associated with rAAV-endostatin use were identified in the vital organs. rAAV-Endostatin demonstrated significant anti-angiogenesis and antitumor activities. It may serve as an effective agent for renal cancer gene therapy.

A fusion antitumor peptide regulates proliferation and apoptosis of endothelial cells

The present research has been carried out to elicit the mechanism of antiangiogenic activity of a fusion peptide P2. Peptide P2 was designed by the connection of a heptapeptide MMP inhibitor to ES-2, a fragment of Endostatin. In a previous study, P2 demonstrated strong antiangiogenic and antitumor effect, and the current work explains the antiangiogenic mechanism of P2 through endothelial cell proliferation and apoptosis. In our study, it was shown that P2 inhibited HUVECs proliferation at a low serum concentration and this effect might be achieved through arresting cell cycle by decreasing the expression level of Cyclin D1. In addition, P2 was found to induce apoptosis of HUVECs. Using Western blot, it was indicated that P2 induced the cleavage of Caspase-3, the hallmark protease of apoptosis. The activation and expression of the upstream regulator Caspase-9 can also be affected by P2 treatment. Furthermore, P2 reduced the protein level of antiangiogenic factors Bcl-xL and Bcl-2. These results revealed that P2 regulates endothelial cell apoptosis through intrinsic apoptotic pathway.

The role of VEGF in the diagnosis and treatment of malignant pleural effusion in patients with non‑small cell lung cancer (Review)

Malignant pleural effusion (MPE) is a severe medical condition, which can result in breathlessness, pain, cachexia and reduced physical activity. It can occur in almost all types of malignant tumors; however, lung cancer is the most common cause of MPE, accounting for ~1/3 of clinical cases. Although there are numerous therapeutic approaches currently available for the treatment of MPE, none are fully effective and the majority can only alleviate the symptoms of the patients. Vascular endothelial growth factor (VEGF) has now been recognized as one of the most important regulatory factors in tumor angiogenesis, which participates in the entire process of tumor growth through its function to stimulate tumor angiogenesis, activate host vascular endothelial cells and promote malignant proliferation. Novel drugs targeting VEGF, including endostar and bevacizumab, have been developed and approved for the treatment of various tumors. Data from recent clinical studies have demonstrated that drugs targeting VEGF are effective and safe for the clinical management of MPE. Therefore, VEGF‑targeting represents a promising novel strategy for the diagnosis and treatment of MPE. The present review summarized recent advances in the role of VEGF in the pathogenesis, diagnosis and clinical management of MPE in patients with non‑small cell lung cancer.

Efficient targeted tumor imaging and secreted endostatin gene delivery by anti-CD105 immunoliposomes

BACKGROUND

Anti-CD105 mAb-conjugated immunoliposomes, loaded with secreted mouse endostatin gene, were developed for targeted tumor imaging and antiangiogenic gene therapy.

METHODS

The liposomes were investigated for size, zeta-potential, lipid content, antibody binding ability, and pcDNA loading capacity. The ability of immunoliposomes to target tumor-derived endothelial cells and perform gene transfer in vitro was measured and their basic biocompatibility was evaluated. A nude mouse/breast cancer xenograft model was used to examine the tumor internalization of fluorescent-labeled liposomes and the clinical potential of immnuoliposomes loaded with pcDNA3.1-CSF1-endostatin.

RESULTS

Loaded immunoliposomes were homogenously distributed with a well-defined spherical shape and bilayer, diameter of 122 ± 11 nm, and zeta potential + 1.40 mV. No significant differences were observed in body weight, liver index, oxidative stress, or liver and kidney function in mice after liposomes exposure. The addition of CD105 mAb to liposomes conferred the ability to target tumor-derived endothelial cells in vitro and in vivo. Systemic intravenous administration of fluorescent immunoliposomes in the xenograft model resulted in selective and efficient internalization in tumor vasculature. Treatment of mice with pcDNA3.1-CSF1-endostatin-loaded immunoliposomes suppressed tumor growth by 71%.

CONCLUSIONS

These data demonstrate the advantages of using anti-CD105 mAb-conjugated immunoliposomes to enhance tumor targeting, imaging, and gene transfer applications.

Exploring three different expression systems for recombinant expression of globins: Escherichia coli, Pichia pastoris and Spodoptera frugiperda

Globins are among the best investigated proteins in biological and medical sciences and represent a prime tool for the study of the evolution of genes and the structure-function relationship of proteins. Here, we explore the recombinant expression of globins in three different expression systems: Escherichia coli, Pichia pastoris and the baculovirus infected Spodoptera frugiperda. We expressed two different human globin types in these three expression systems: I) the well-characterized neuroglobin and II) the uncharacterized, circular permutated globin domain of the large chimeric globin androglobin. It is clear from the literature that E.coli is the most used expression system for expression and purification of recombinant globins. However, the major disadvantage of E. coli is the formation of insoluble aggregates. We experienced that, for more complex multi-domain globins, like the chimeric globin androglobin, it is recommended to switch to a higher eukaryotic expression system.