The mechanism of rh-endostatin-induced cardiotoxicity and its protection by dihydromyricetin[in vivo/in vitro, C57BL/6 mice, AC16 and hiPSC-CMs].

Recombinant human endostatin (rh-endostatin) is an anti-angiogenic drug, which is used for the treatment of advanced non-small-cell lung cancer (NSCLC) and other cancers. However, its side effects, especially the cardiotoxicity with unclear mechanisms limit its wide application in clinical practice. In this study, human cardiomyocyte cell line AC16 and human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) treated with different doses of rh-endostatin were used to analyze its effect on cardiac cell toxicity. The results revealed that rh-endostatin dose-dependently enhanced cardiomyocyte apoptosis through Apaf-1 apoptotic factor and apoptosis-related proteins such as p53. rh-endostatin-induced changes of mitochondrial function and mitophagy were involved in rh-endostatin-mediated cardiac cell toxicity. Rh-endostatin-induced cardiotoxicity was further verified in vivo in mice. Interestingly, Rh-endostatin-induced cardiotoxicity was inhibited by dihydromyricetin (DHM) both in cultured cells in vitro and in mouse hearts in vivo. The study provides new inside into rh-endostatin-induced cardiotoxicity and identified a novel potential medication DHM to overcome the serious adverse effect.

[Evaluation of tumor vascular normalization in colorectal cancer mouse mode induced by recombinant human endostatin by intravoxel incoherent motion diffusion-weighted magnetic resonance imaging].

Objective: To evaluate the feasibility of intravoxel incoherent motion diffusion-weighted magnetic resonance imaging (IVIM-DWI MRI) in the evaluation of tumor vascular normalization in a mouse model of colorectal cancer induced by recombinant human endostatin (rhES). Methods: The CT26 colorectal cancer xenograft model of BALB/c mice were established and divided into rhES group and control group, with 20 mice in each group. The mice of rhES group were intravenously injected with rhES 5 mg·kg(-1)·d(-1) once daily for 12 days, while the mice of the control group were intravenously injected with the same volume of 0.9% saline. 5 mice of rhES group and control group were randomly selected to perform IVIM-DWI MRI as following times: before treatment and four, eight, twelve days after treatment. The parameters of IVIM-DWI were recorded, including true diffusion coefficient(D), pseudo-diffusion coefficient (D(*)) and perfusion fraction (f). Meanwhile, microvessel density (MVD), pericyte coverage and tumor perfusion in tumor tissues were detected by immunofluorescence, respectively. Results: The tumor volumes of control group and rhES group before treatment were (154.42±24.65) mm(3) and (174.24±28.27)mm(3,) respectively, without statistically significant difference (P=0.440). From day 2 to day 12 after treatment, the tumor volume of rhES group was significantly smaller than that of control group (all P<0.05). There were no statistical significances of D value between the rhES group and control group before and after treatment (all P>0.05). The D(*) values of the rhES group were (10.940±2.834)×10(-3)mm(2)/s and (12.940±2.801)×10(-3)mm(2)/s in day 4 and 8 after treatment respectively, significantly higher than (6.980±1.554)×10(-3)mm(2)/s and (7.898±1.603)×10(-3)mm(2)/s of control group (P<0.05). Moreover, compared with control group, the D(*) value of rhES group was significantly lower in day 12 (6.848±1.460)×10(-3)mm(2)/s vs (9.950±2.596)×10(-3)mm(2)/s, (P<0.05). The f value of rhES group in day 8 was (0.226±0.021)%, significantly higher than (0.178±0.016)% of control group (P<0.01). The MVD of rhES group was significantly lower than that of control group (P<0.05), while the pericyte coverage and tumor perfusion of rhES group were significantly higher than those of control group in day 4 and 8 after treatment (all P<0.05). In addition, we found D(*) value of IVIM-DWI in rhES group was significantly related with MVD, pericyte coverage and tumor perfusion (r=-0.354, r=0.555, r=0.559, all P<0.05). Meanwhile, the f value in rhES group was also significantly related with MVD, pericyte coverage and tumor perfusion (r=-0.391, r=0.538, r=0.315, all P<0.05). Conclusions: IVIM-DWI MRI can effectively evaluate the vascular normalization in rhES-induced CT26 colorectal tumor.The parameters D(*) and f are closely related to intratumorally microvessel density, pericyte coverage and perfusion, which can effectively monitor the occurrence of tumor vascular normalization time.

Characterization, bioactivity and pharmacokinetic study of a novel carbohydrate-peptide polymer: Glycol-split heparin-endostatin2 (GSHP-ES2).

Endostatin (ES) has attracted considerable attention for the treatment of anti-angiogenesis-related disorders. An 11-amino-acid peptide (ES2, IVRRADRAAVP) from the amino terminal of ES is of interest because it is the main active fragment of ES. However, both ES and ES2 have a poor stability and a short half-life, and other disadvantages need to be further resolved. Thus, we conjugated ES2 to glycol-split heparin derivatives (GSHPs) to yield the polymer-peptide conjugate, GSHP-ES2. This study showed that GSHP-ES2 exhibited increased stability, a wider pH activity range, better inhibition of endothelial cell proliferation, migration and tube formation in vitro, better anti-angiogenic activity and a longer half-life in vivo compared with ES2. These results also indicate that GSHP-ES2 has good potential for the treatment of angiogenesis-related diseases, either alone or in combination with other chemicals.

Quality, bioactivity study, and preclinical acute toxicity, safety pharmacology evaluation of PEGylated recombinant human endostatin (M2 ES).

Endostar, a potent endogenous antiangiogenic factor, is wildly used in clinics. However, it was easily degraded by enzymes and rapidly cleared by the kidneys. To overcome these shortcomings, PEGylated recombinant human endostatin was developed. In this study, the purity of M2 ES was evaluated by silver stain and reversed-phase high-performance liquid chromatography. Ultraviolet spectrum was used to examine the structural of M2 ES and endostar. The bioactivity and antitumor efficacy of M2 ES were evaluated using an in vitro endothelial cell migration model and athymic nude mouse xenograft model of a heterogeneous lung adenocarcinoma, respectively. A preclinical study was performed to evaluate the acute toxicity and safety pharmacology in rhesus monkeys. The purity of M2 ES was more than 98%; PEG modification has no effect on endostatin structure. Compared with the control group, M2 ES dramatically retards endothelial cell migration and tumor growth. After intravenous (IV) infusions of M2 ES at a dose level of three and 75 mg/kg in rhesus monkeys, there was no observable serious adverse event in both acute toxicity and safety pharmacology study. On the basis of the quality and bioactivity study data of M2 ES and the absence of serious side effect in rhesus monkeys, M2 ES was authorized to initiate a phase I clinical trial.

A pre-clinical safety study of PEGylated recombinant human endostatin (M2ES) in Sprague Dawley rats.

PEGylated recombinant human endostatin (M2ES) exhibited prolonged serum half-life and enhanced antitumor activity when compared with endostatin. A pre-clinical study was performed to evaluate the safety of M2ES in rats. After intravenous (IV) infusions of M2ES at a dose level of 3, 15 and 75 mg/kg in Sprague Dawley (SD) rats, M2ES was well tolerated in animals, with no observable changes in clinical observation, body weight, food consumption, urine analysis, hematology and serum biochemical analysis. The increase of kidney weights, and slight to severe vacuolation and necrosis of proximal tubule epithelial cells in kidney were observed in 15 and 75 mg/kg M2ES groups, but this adverse-effect was reversible. In summary, the major toxicity target organ of M2ES might be kidney, and the no observed adverse effect level (NOAEL) of M2ES in rats was 3 mg/kg in this study. These pre-clinical safety data contribute to the initiation of the ongoing clinical study.

Improving the therapeutic potential of endostatin by fusing it with the BAX BH3 death domain.

Endostatin (ES) inhibits angiogenesis, reducing tumor growth in animal models. However, it has low therapeutic effect in human clinical trials. BAX is a member of the BCL-2 family of proteins; its proapoptotic (BH3) domain interacts with other members of the family in the cytoplasm, to induce apoptosis. Here, we fused the BAX BH3 domain with murine ES, to enhance ES potency. Endothelial cells specifically internalize the fusion protein ES-BAX. The presence of the BAX domain enhances endothelial cell death by apoptosis by 1.8-fold and diminishes microvessel outgrowth in the rat aortic ring assay by 6.5-fold. Daily injections of 15 µg of ES-BAX/g in tumor-bearing mice reduce tumor weight by 86.9% as compared with ES-treated animals. Co-immunoprecipitation assays confirmed that ES-BAX interacts with members of the BCL-2 family. Also, ES interacts with BCL-2, BCL-XL, and BAK in endothelial cell lysates, suggesting a potential new mechanism for the apoptosis induction by ES. The superiority of the ES-BAX antiangiogenic effect indicates that this fusion protein could be a promising therapeutic alternative to treat cancer.

Improvement in the standard treatment for experimental glioma by fusing antibody Fc domain to endostatin.

OBJECT: Brain tumors pose many unique challenges to treatment. The authors hypothesized that Fc-endostatin may be beneficial. It is a newly synthesized recombinant human endostatin conjugated to the Fc domain of IgG with a long half-life (weeks) and unknown toxicity. The authors examined the efficacy of Fc-endostatin using various delivery methods. METHODS: Efficacy was assessed using the intracranial 9L gliosarcoma rat model treated with Fc-endostatin for use in rodents (mFc-endostatin), which was administered either systemically or locally via different delivery methods. Oral temozolomide (TMZ) was administered in combination with mFc-endostatin to determine if there was a beneficial synergistic effect. RESULTS: Intracranial delivery of mFc-endostatin via a polymer or convection-enhanced delivery 5 days after tumor implantation increased median survival, compared with the control group (p = 0.0048 and 0.003, respectively). Animals treated weekly with subcutaneous mFc-endostatin (started 5 days post-tumor implantation) also had statistically improved survival as compared with controls (p = 0.0008). However, there was no statistical difference in survival between the local and systemic delivery groups. Control animals had a median survival of 13 days. Animals treated either with subcutaneous mFc-endostatin weekly or with polymer had a median survival of 18 and 15 days, respectively, and those treated with oral TMZ for 5 days (Days 5-9) had a median survival of 21 days. Survival was further increased with a combination of oral TMZ and mFc-endostatin polymer, with a median survival of 28 days (p = 0.029, compared with TMZ alone). Subcutaneous mFc-endostatin administered every week starting 18 days before tumor implantation significantly increased median survival when compared with controls (p = 0.0007), with 12.5% of the animals ultimately becoming long-term survivors (that is, survival longer than 120 days). The addition of TMZ to either weekly or daily subcutaneous mFc-endostatin and its administration 18 days before tumor implantation significantly increased survival (p = 0.017 and 0.0001, respectively, compared with TMZ alone). Note that 12.5% of the animals treated with weekly subcutaneous mFc-endostatin and TMZ were long-term survivors. CONCLUSIONS: Systemically or directly (local) delivered mFc-endostatin prolonged the survival of rats implanted with intracranial 9L gliosarcoma. This benefit was further enhanced when mFc-endostatin was combined with the oral chemotherapeutic agent TMZ.