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.

Fibronectin expression is decreased in metastatic renal cell carcinoma following endostatin gene therapy.

Tumor cells induce the disruption of homeostasis between cellular and extracellular compartments to favor tumor progression. The expression of fibronectin (FN), a matrix glycoprotein, is increased in several carcinoma cell types, including renal cell carcinoma (RCC). RCC are highly vascularized tumors and are often amenable to antiangiogenic therapy. Endostatin (ES) is a fragment of collagen XVIII that possesses antiangiogenic activity. In this study, we examined the modulation of FN gene expression by ES gene therapy in a murine metastatic renal cell carcinoma (mRCC) model. Balb/C mice bearing Renca cells were treated with NIH/3T3-LXSN cells or NIH/3T3-LendSN cells. At the end of the experiment, the ES serum levels were measured, and the FN gene expression was assessed using real-time PCR. The tissue FN was evaluated by western blotting and by immunofluorescence analysis. The ES serum levels in treated mice were higher than those in the control group (P<0.05). ES treatment led to significant decreases at the FN mRNA (P<0.001) and protein levels (P<0.01). Here, we demonstrate the ES antitumor effect that is mediated by down-regulation of FN expression in mRCC.

Endostatin gene therapy stimulates upregulation of ICAM-1 and VCAM-1 in a metastatic renal cell carcinoma model.

One of the greatest challenges in urological oncology is renal cell carcinoma (RCC), which is the third leading cause of death in genitourinary cancers. RCCs are highly vascularized and respond positively to antiangiogenic therapy. Endostatin (ES) is a fragment of collagen XVIII that possesses antiangiogenic activity. In this study, we examined the potential of ES-based antiangiogenic therapy to activate tumor-associated endothelial cells in metastatic RCC (mRCC). Balb/c-bearing Renca cells were treated with NIH/3T3-LendSN or, as a control, with NIH/3T3-LXSN cells. The T-cell subsets and lymphocyte populations of tumors, mediastinal lymph nodes and the spleen were assessed by flow cytometry. The expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was assessed by real-time PCR, flow cytometry and immunohistochemistry analysis. ES gene therapy led to an increase in the percentage of infiltrating CD4-interferon (IFN)-γ cells (P<0.05), CD8-IFN-γ cells (P<0.01) and CD49b-tumor necrosis factor-α cells (P<0.01). In addition, ES therapy caused an increase at the mRNA level of ICAM-1 (1.4-fold; P<0.01) and VCAM-1 (1.5-fold) (control vs treated group; P<0.001). Through flow cytometry, we found a significant increase in the CD34/ICAM-1 cells (8.1-fold; P<0.001) and CD34/VCAM-1 cells (1.6-fold; P<0.05). ES gene therapy induced a significant increase in both T CD4 and CD8 cells in the lymph nodes and the spleen, suggesting that ES therapy may facilitate cell survival or clonal expansion. CD49b cells were also present in increased quantities in all of these organs. In this study, we demonstrate an antitumor inflammatory effect of ES in an mRCC model, and this effect is mediated by an increase in ICAM-1 and VCAM-1 expression in tumor-associated endothelial cells.

Clinical study on the recombinant human endostatin regarding improving the blood perfusion and hypoxia of non-small-cell lung cancer.

OBJECTIVE: To observe the dynamic changes of blood perfusion and hypoxic status with CT perfusion imaging and hypoxia imaging in patients of non-small-cell lung cancer (NSCLC) who were treated with recombinant human endostatin (RHES). METHODS: Fifteen previously untreated patients with histologically or cytologically confirmed NSCLC were enrolled. They were randomly divided into research group (n=10) and negative control group (n=5). The patients of the research group continuously used RHES for ten days, and simultaneously had CT perfusion imaging and hypoxia imaging performed on days 1, 5 and 10, respectively. The remaining 5(control) only had CT perfusion imaging and hypoxia imaging, without using RHES, on days 1, 5 and 10, respectively. According to the above results, we could obtain a "time window" during which RHES improves blood perfusion and hypoxia of lung cancer. RESULTS: In the research group, after using RHES, capillary permeability surface (PS) and tumour to normal tissue (T/N) decreased at first, and then increased. Their lowest points occurred on about the fifth day with statistical significance compared with the first day (T/N, p=0.00; PS, p<0.01). Blood flow (BF) was first increased and then decreased. Its highest point occurred on about the fifth day with statistical significance compared with the first and tenth day (all p<0.01). The PS, BF and T/N peaked on the fifth day in the research group with statistical significance compared with the negative control group as well (all p<0.01). The above results suggested that RHES's "time window" was within about one week after administration. CONCLUSION: RHES's "time window" is within about one week after administration, which provides an important experimental basis for combining RHES with radiotherapy in human tumours.

Preliminary clinical study of weekly recombinant human endostatin as a hypoxic tumour cell radiosensitiser combined with radiotherapy in the treatment of NSCLC.

OBJECTIVE: To investigate the clinical effects and adverse effects of weekly recombinant human endostatin (RHES) as a hypoxic tumour cell radiosensitiser combined with radiotherapy in the treatment of non-small-cell lung cancer (NSCLC). METHODS: Fifty hypoxia-positive cases of pathology-diagnosed NSCLC (stage I-III) were randomly divided into a RHES+radiotherapy group (25 cases) and a radiotherapy alone group (25 cases). Intensity-modulated radiotherapy (IMRT) with a total dose of 60 Gy/30F/6W was adopted in the two groups. Target area included primary foci and metastatic lymph nodes. In the RHES+radiotherapy group, RHES (15 mg/day) was intravenously given during the first week. The therapeutic effects and adverse reactions were evaluated after treatment. RESULTS: In the RHES+radiotherapy and radiotherapy alone groups, the total effective rates (CR+PR) were 80% and 44% (χ(2)=6.87, p=0.009), respectively. The one-year and two-year local control rates were (78.9±8.4)% and (68.1±7.8)% (p=0.027), and (63.6±7.2)% and (43.4±5.7)% (p=0.022), respectively. The median progression-free survival was (21.1±0.97) and (16.5±0.95) months, respectively. The one-year and two-year overall survival rates were (83.3±7.2)% and (76.6±9.3)% (p=0.247), and (46.3±2.4)% and (37.6±9.1)% (p=0.218), respectively. CONCLUSION: RHES combined with radiotherapy within the first week has better short-term therapeutic effects and local control rate, and no severe adverse reactions in treatment of NSCLC. However, it failed to significantly improve the one-year and two-year overall survival rates.

Anti-tumor therapy with macroencapsulated endostatin producer cells.

BACKGROUND: Theracyte is a polytetrafluoroethylene membrane macroencapsulation system designed to induce neovascularization at the tissue interface, protecting the cells from host's immune rejection, thereby circumventing the problem of limited half-life and variation in circulating levels. Endostatin is a potent inhibitor of angiogenesis and tumor growth. Continuous delivery of endostatin improves the efficacy and potency of the antitumoral therapy. The purpose of this study was to determine whether recombinant fibroblasts expressing endostatin encapsulated in Theracyte immunoisolation devices can be used for delivery of this therapeutic protein for treatment of mice bearing B16F10 melanoma and Ehrlich tumors. RESULTS: Mice were inoculated subcutaneously with melanoma (B16F10 cells) or Ehrlich tumor cells at the foot pads. Treatment began when tumor thickness had reached 0.5 mm, by subcutaneous implantation of 107 recombinant encapsulated or non-encapsulated endostatin producer cells. Similar melanoma growth inhibition was obtained for mice treated with encapsulated or non-encapsulated endostatin-expressing cells. The treatment of mice bearing melanoma tumor with encapsulated endostatin-expressing cells was decreased by 50.0%, whereas a decrease of 56.7% in tumor thickness was obtained for mice treated with non-encapsulated cells. Treatment of Ehrlich tumor-bearing mice with non-encapsulated endostatin-expressing cells reduced tumor thickness by 52.4%, whereas lower tumor growth inhibition was obtained for mice treated with encapsulated endostatin-expressing cells: 24.2%. Encapsulated endostatin-secreting fibroblasts failed to survive until the end of the treatment. However, endostatin release from the devices to the surrounding tissues was confirmed by immunostaining. Decrease in vascular structures, functional vessels and extension of the vascular area were observed in melanoma microenvironments. CONCLUSIONS: This study indicates that immunoisolation devices containing endostatin-expressing cells are effective for the inhibition of the growth of melanoma and Ehrlich tumors.Macroencapsulation of engineered cells is therefore a reliable platform for the refinement of innovative therapeutic strategies against tumors.

Continuous and high-level in vivo delivery of endostatin from recombinant cells encapsulated in TheraCyte immunoisolation devices.

Endostatin (ES) is a potent inhibitor of angiogenesis and tumor growth. Continuous ES delivery of ES improves the efficacy and potency of the antitumoral therapy. The TheraCyte system is a polytetrafluoroethylene (PTFE) semipermeable membrane macroencapsulation system for implantation of genetically engineered cells specially designed for the in vivo delivery of therapeutic proteins, such as ES, which circumvents the problem of limited half-life and variation in circulating levels. In order to enable neovascularization at the tissues adjacent to the devices prior to ES secretion by the cells inside them, we designed a scheme in which empty TheraCyte devices were preimplanted SC into immunodeficient mice. Only after healing (17 days later) were Chinese hamster ovary cells expressing ES injected into the preimplanted devices. In another model for device implantation, the cells expressing ES where loaded into the immunoisolation devices prior to implantation into the animals, and the TheraCyte were then immediately implanted SC into the mice. Throughout the 2-month study, constant high ES levels of up to 3.7 microg/ml were detected in the plasma of the mice preimplanted with the devices, while lower but also constant levels of ES (up to 2.1 microg/ml plasma) were detected in the mice that had received devices preloaded with the ES-expressing cells. Immunohistochemistry using anti-ES antibody showed reaction within the device and outside it, demonstrating that ES, secreted by the confined recombinant cells, permeated through the membrane and reached the surrounding tissues.