Systemic administration of mesenchymal stem cells loaded with a novel oncolytic adenovirus carrying IL-24/endostatin enhances glioma therapy

Oncolytic adenovirus-mediated gene therapy shows promise for cancer treatment; however, the systemic delivery of oncolytic adenovirus to tumors remains challenging. Recently, mesenchymal stem cells (MSCs) have emerged as potential vehicles for improving delivery. Yet, because the oncolytic adenovirus replicates in MSCs, balancing MSC viability with viral load is key to achieving optimal therapeutic effect. We thus developed an all-in-one Tet-on system that can regulate replication of oncolytic adenovirus. Then, we loaded the novel oncolytic adenovirus carrying interleukin (IL)-24 and/or Endostatin in human umbilical cord blood-mesenchymal stem cells (hUCB-MSCs) for glioma therapy. In vitro assays demonstrated that this novel oncolytic adenovirus could efficiently replicate and kill glioma cells while sparing normal cells. Moreover, doxycycline effectively regulated oncolytic adenovirus replication in the hUCB-MSCs. The doxycycline induction group with dual expression of IL-24 and Endostatin exhibited significantly greater antitumor effects than other groups in a xenograft model of glioma. Thus, this strategy for systemic delivery of oncolytic adenovirus with its oncolytic activity controlled by a Tet-on system is a promising method for achieving antitumor efficacy in glioma, especially for metastatic tumors.

[Suppression of colon cancer in murine model by recombinant human endostatin adenovirus and cisplatin]

OBJECTIVE

To investigate the efficacy, side effect and anti-tumor mechanism of recombinant human endostatin adenovirus (Ad-hE) and cisplatin on murine colon cancer.

METHODS

Mice with CT26 colon cancer were randomly divided into 5 groups, being given Ad-hE via tail vein, cisplatin (Cis) intraperitoneally, Ad-hE plus cisplatin (Ad-hE+Cis), empty adenovirus (Ad-N), and saline (NS), respectively. The therapeutic effect and side effect of the treatments and the angiogenesis and apoptosis of tumor cells were observed.

RESULTS

Ad-hE + Cis suppressed the growth of lung metastatic tumor and prolonged survival time of the murine CT26 colon cancer model. The anti-tumor activity was associated with decreased microvessel density and increased apoptosis of tumor cells.

CONCLUSION

Recombinant human endostatin adenovirus enhances the anti-tumor activity of cisplatin without increasing toxicity.

[Antitumor effect by combination of shRNA interfering plasmid targeting PKM2 with recombinant endostatin]

OBJECTIVE

To investigate the enhancement effect of the combination of shRNA interfering plasmid targeting PKM2 with recombinant Endostatin in the treatment of lung cancer.

METHODS

Twenty five BABL/nu/nu mice bearing A549 lung cancer were divided into 5 groups (NS control, psh-Control, psh-PKM2 treated group, Endostar treated group, psh-PKM2+Endostar treated group) and treated with shRNA interfering plasmid targeting PKM2 and recombinant Endostatin respectively or in combination. The expression of PKM2 in A549 detected with immunofluorescent assay. The interference effect of psh-PKM2 was determined by Western blot. The tumor volume, microvessel density (MVD), apoptosis index (AI) and side effects were observed.

RESULTS

The combination treatment of RNA interfering plasmid targeting PKM2 with recombinant Endostatin inhibited tumor growth obviously (P < 0.05); The combination group revealed a decreased MVD and an increased AI (P < 0.05).

CONCLUSION

The combination of shRNA interfering plasmid targeting PKM2 with recombinant Endostatin might enhance anti-tumor effect by increasing the apoptosis of the cancer cell.

Endostatin gene therapy enhances the efficacy of IL-2 in suppressing metastatic renal cell carcinoma in mice

We investigated whether the administration of IL-2 combined with endostatin gene therapy was able to produce additive or even synergistic immunomodulatory activity in a mouse model of metastatic renal carcinoma. Renca cells were injected into the tail vein of BALB/c mice. After 24 h, the animals were randomly divided into four groups (5 mice/group). One group of mice was the control, the second group received treatment with 100,000 UI of Recombinant IL-2 (Proleukin, Chiron) twice a day, 1 day per week during 2 weeks (IL-2), the third group received treatment with a subcutaneous inoculation of 3.6 x 10(6) endostatin-producing cells, and the fourth group received both therapies (IL-2 + ES). Mice were treated for 2 weeks. In the survival studies, 10 mice/group daily, mice were monitored daily until they died. The presence of metastases led to a twofold increase in endostatin levels. Subcutaneous inoculation of NIH/3T3-LendSN cells resulted in a 2.75 and 2.78-fold increase in endostatin levels in the ES and IL-2 + ES group, respectively. At the end of the study, there was a significant decrease in lung wet weight, lung nodules area, and microvascular area (MVA) in all treated groups compared with the control group (P < 0.001). The significant difference in lung wet weight and lung nodules area between groups IL-2 and IL-2 + ES revealed a synergistic antitumor effect of the combined treatment (P < 0.05). The IL-2 + ES therapy Kaplan-Meier survival curves showed that the probability of survival was significantly higher for mice treated with the combined therapy (log-rank test, P = 0.0028). Conjugated therapy caused an increase in the infiltration of CD4, CD8 and CD49b lymphocytes. An increase in the amount of CD8 cells (P < 0.01) was observed when animals received both ES and IL-2, suggesting an additive effect of ES over IL-2 treatment. A synergistic effect of ES on the infiltration of CD4 (P < 0.001) and CD49b cells (P < 0.01) was also observed over the effect of IL-2. Here, we show that ES led to an increase in CD4 T helper cells as well as cytotoxic lymphocytes, such as NK cells and CD8 cells, within tumors of IL-2 treated mice. This means that ES plays a role in supporting the actions of T cells.

[Antitumor effect by combination of recombinant endostatin adenovirus with carboplatin]

OBJECTIVE

To investigate the antitumor effect of recombinant Endostatin adenovirus (Ad-E) with carboplatin in mice with Lewis lung cancer.

METHODS

C57BL/6 mice bearing Lewis lung cancer received Ad-E and carboplatin respectively or in combination. The tumor volume, tumor net weight, survival time and side effects were observed. Histological analysis was conducted to assess microvessel density (MVD) within tumor tissue and apoptotic cells were identified using the TUNEL assay.

RESULTS

Compared with the control groups, the combination treatment significantly suppressed the tumor growth and prolonged survival time of the mice without obvious side-effects. The histological analysis revealed the combination treatment led to a decreased MVD and increased percent apoptosis in LL/2 tumors.

CONCLUSION

Our studies indicate that a combination of Ad-E with carboplatin can present better antitumor effects without obvious side-effect.

[Inhibitory effects of recombinant adenovirus carrying human endostatin gene on the growth of human pancreatic carcinoma xenograft in nude mice]

OBJECTIVE

To evaluate the inhibitory effect of recombinant adenovirus carrying human endostatin gene (Ad-endo) on the growth of human pancreatic carcinoma xenograft in nude mice.

METHODS

The expression of endostatin in human pancreatic carcinoma Capan-2 cells was examined by RT-PCR after infection with Ad-endo. The supernatants of Capan-2 cells were collected after 48 h of infection with Ad-endo as the conditioned medium for human umbilical vein endothelial cells (HUVECs), whose proliferation in vitro was assayed. Capan-2 cell xenografts were established to determine the antitumoral effects of Ad-endo in vivo. The intratumoral microvessel density (MVD) was evaluated using CD31 staining.

RESULTS

The expression of endostatin gene was detected by PT-PCR in infected Capan-2 cells. The conditioned medium from Ad-endo-infected cells significantly inhibited HUVEC proliferation (P<0.05). Ad-endo significantly suppressed the growth of Capan-2 tumor xenografts in nude mice (P<0.05), and the MVD decreased significantly in the treated tumor (P<0.05) as compared with that in the control group.

CONCLUSION

Adenovirus carrying human endostatin gene produces inhibitory effects on the growth of human pancreatic carcinoma tumors in nude mice.

Mesalamine restores angiogenic balance in experimental ulcerative colitis by reducing expression of endostatin and angiostatin: novel molecular mechanism for therapeutic action of mesalamine

Mesalamine (5-aminosalicylate acid, 5-ASA) is an effective treatment for ulcerative colitis (UC). The mechanisms of its actions are not fully understood. Because angiogenesis is critical for healing UC, we examined whether 5-ASA alters the angiogenic balance between angiogenic factors [e.g., vascular endothelial growth factor (VEGF)] and antiangiogenic factors (e.g., endostatin and angiostatin) in the colon in experimental UC. Rats were treated with saline or 5-ASA (100 mg/kg) twice daily and euthanized 3 or 7 days after iodoacetamide-induced UC. Clinical signs (e.g., lethargy, diarrhea) and UC lesions were measured. Expression of VEGF, endostatin, angiostatin, tissue necrosis factor alpha (TNF-alpha), and matrix metalloproteinases (MMPs) 2 and 9 was determined by Western blots, enzyme-linked immunosorbent assay, and zymography in the distal colon. 5-ASA treatment reduced lethargy and diarrhea and significantly decreased colonic lesions (by approximately 50%) compared with saline treatment in UC (both, P < 0.05). 5-ASA did not reverse the increased levels of VEGF, but it significantly reduced expression of endostatin and angiostatin in UC compared with vehicle treatment (both, P < 0.05). Furthermore, 5-ASA treatment significantly diminished increased activity of TNF-alpha and MMP9 in UC. This is the first demonstration that 5-ASA treatment reverses an imbalance between the angiogenic factor VEGF and antiangiogenic factors endostatin and angiostatin in experimental UC. The effect of 5-ASA in UC may be caused by the down-regulation of expression of endostatin and angiostatin by modulation of MMP2 and MMP9 via inhibition of TNFalpha. The inhibition of antiangiogenic factors may represent a novel molecular mechanism of the therapeutic action of 5-ASA.

Increased endostatin generation and decreased angiogenesis via MMP-9 by tamoxifen in hormone dependent ovarian cancer

There are several similarities between breast and ovarian cancer but anti-estrogen treatment is rarely used in ovarian cancer. We have previously shown that the most widely used anti-estrogen tamoxifen increased MMP-9 activity and endostatin generation in breast cancer. Here, we show that tamoxifen exposure of highly hormone responsive ovarian cancer cells decreased proliferation, and increased MMP-9 activity leading to increased levels of endostatin both in cell culture in vitro and in solid tumors of nude mice. Tamoxifen exposed tumors also exhibited significantly decreased tumor growth and vascularisation. Moreover, in ascites from ovarian cancer patients, MMP-9 was undetectable in majority of cases but a significant correlation of MMP-2 and endostatin was found. The effects on MMPs and endostatin generation are previously unknown mechanisms of estradiol and tamoxifen in ovarian cancer, which may have therapeutic implications in future anti-cancer options of hormone dependent ovarian cancer.

Tumoristatic effects of endostatin in prostate cancer is dependent on androgen receptor status

BACKGROUND

Although anti-angiogenic therapy is a promising new line of therapy for prostate cancer, we recently reported that stable expression of endostatin arrested the progression of prostate cancer to poorly differentiated state and distant metastasis in TRAMP mice. However, the same therapy failed to provide any benefit when given either during or after the onset of metastatic switch. The present study determined the possible mechanisms behind the selective advantage of endostatin therapy in early-stage disease.

METHODS

Angiogenesis-related gene expression analysis was performed to identify target genes and molecular pathways involved in the therapy effects. Based on the results from in vivo studies, and recapitulation of the in vivo data in vitro using tumorigenic and non-tumorigenic human prostate cancer cells that are either androgen-sensitive or androgen-independent, analyses of possible mechanisms of the selective advantage of early treatment were performed using assays for cell proliferation, apoptosis, migration, and cell signaling. The identified mechanisms were further confirmed in vivo.

RESULTS

Results indicated that cells with high androgen receptor (AR) expression were more sensitive to endostatin treatment than androgen-independent cells with low or no AR expression. Endostatin was found to significantly downregulate the expression of growth factors, receptor tyrosine kinases, proteases, and AR both in vitro and in vivo only when the cells express high-levels of AR. Cell proliferation was not influenced by endostatin treatment but migration was significantly affected only in androgen-sensitive cells. Targeted downregulation of AR prior to endostatin treatment in androgen-sensitive cells and overexpression of AR in androgen-independent cells indicated that the effect of endostatin via AR downregulation is mediated by a non-genotropic mechanism on Ras and RhoA pathways, and independently of AR on MAPK/ERK pathway.

CONCLUSIONS

These data indicate that systemically stable endostatin expression delays the onset of metastatic switch by acting on multiple pathways involving AR.

Suppression of lung cancer in murine model: treated by combination of recombinant human endostsatin adenovirus with low-dose cisplatin

BACKGROUND

The sustained growth of tumors necessitates neovascularization. As one of the potent endogenous vascular inhibitors, endostatin has been widely used in antiangiogenesis therapy for tumor. Cisplatin is normally administered in chemotherapy for lung cancer but accompanied with serious side effects. In the current study, we investigated a novel chemo-antiangiogenesis therapeutic strategy to both improve toxic effects on lung cancer cells and reduce damages to normal cells in the anti-tumor therapy.

METHODS

In vitro, we transduced LLC cells with Ad-hEndo and collected supernatants. Western blotting analysis of the supernatants revealed expression of endostatin. In vivo, to fully investigate the suppression effect on murine lung cancer of the combination therapy, we injected recombinant human endostatin adenovirus intratumorally plus a low dose of cisplatin intraperitoneally routinely. The tumor volume and survival time were observed. Angiogenesis was apparently inhibited within the tumor tissues and on the alginate beads. Assessment of apoptotic cells by the TUNEL assay was conducted in the tumor tissues.

RESULTS

The combination treatment significantly suppressed the tumor growth and prolonged survival time of the murine LLC tumor model. This anti-tumor activity was associated with decreased microvessel density and increased apoptotic index of tumor cells.

CONCLUSION

According to the results in this study, recombinant human endostatin adenovirus in combination with a low dose of cisplatin demonstrated apparent synergistic anti-tumor activity without marked toxicity. Thus, these observations may provide a rational alternative for lung cancer treatment.

Association of cathepsin E with tumor growth arrest through angiogenesis inhibition and enhanced immune responses

Cathepsin E (CE) is an intracellular aspartic proteinase implicated in various physiological and pathological processes, yet its actual roles in vivo remain elusive. To assess the physiological significance of CE expression in tumor cells, human CE was stably expressed in human prostate carcinoma ALVA101 cells expressing very little CE activity. Tumor growth in nude mice with xenografted ALVA101/hCE cells was slower than with control ALVA101/mock cells. Angiogenesis antibody array and ELISA assay showed that this was partly due to the increased expression of some antiangiogenic molecules including interleukin 12 and endostatin in tumors induced by CE expression. In vitro studies also demonstrated that, among the cathepsins tested, CE most efficiently generated endostatin from the non-collagenous fragment of human collagen XVIII at mild acidic pH. Histological examination revealed that tumors formed by ALVA101/hCE cells were partitioned by well-developed membranous structures and covered with thickened, well-stratified hypodermal tissues. In addition, both the number and extent of activation of tumor-infiltrating macrophages were more profound in ALVA101/hCE compared to ALVA101/mock tumors. The chemotactic response of macrophages to ALVA101/hCE cells was also higher than that to ALVA/mock cells. These results thus indicate that CE expression in tumor cells induces tumor growth arrest via inhibition of angiogenesis and enhanced immune responses.

Chinese medicinal compound delisheng has satisfactory anti-tumor activity, and is associated with up-regulation of endostatin in human hepatocellular carcinoma cell line HepG2 in three-dimensional culture

AIM: To investigate the multicellular resistance of human hepatocellular carcinoma HepG2 cells in three-dimensional culture to delisheng, 5-fluorouracil and adriamycin, and the possible molecular mechanisms of delisheng.

METHODS: Human hepatocellular carcinoma HepG2 cells were cultured with a liquid overlay technique. After the formation of multicellular spheroids, morphology was analyzed by phase contrast microscopy, scanning electron microscopy and transmission electron microscopy. Sensitivity of HepG2 cells to delisheng, 5-fluorouracil and adriamycin was investigated by MTT assay in multicelluar spheroids and monolayers. Vascular endothelial growth factor (VEGF) and endostatin expression were analyzed in multicellular spheroids treated with delisheng, 5-fluorouracil, adriamycin and negative control PBS, with immunohistochemical staining.

RESULTS: Multicellular spheroids exhibited structural characteristics somewhat different to those in monolayers. The cells in three-dimensional cell culture turned out to be less sensitive to delisheng, 5-fluorouracil and adriamycin than the cells cultured in monolayer. This showed that delisheng had a satisfactory cells inhibition ratio compared to 5-fluorouracil and adriamycin. Immunohistochemical staining showed that VEGF and endostatin expression was positive during growth as multicellular spheroids, and endostatin expression in spheroids with treatment of delisheng was higher than that with 5-fluorouracil, adriamycin and PBS (139.35 ± 7.83, 159.23 ± 10.34, 162.83 ± 3.47 and 148.48 ± 11.06, P < 0.05).

CONCLUSION: Chinese medicine compound delisheng has satisfactory anti-tumor activity in HepG2 cells in three-dimensional culture, and the effects are associated with up-regulation of endostatin.

Endostatin gene therapy enhances the efficacy of paclitaxel to suppress breast cancers and metastases in mice

Chemotherapy combined with antiangiogenic therapy is more effective than chemotherapy alone. The aim of this study was to investigate whether endostatin, a potent anti-angiogenic agent, could enhance the efficacy of paclitaxel to combat breast cancer. An expression plasmid encoding mouse endostatin (End-pcDNA3.1) was constructed, which produced intense expression of endostatin and inhibited angiogenesis in the chorioallantoic membrane assay. 4T1 breast tumors were established in BALB/c mice by subcutaneous injection of 1 x 10(5) 4T1 cells. The End-pcDNA3.1 plasmid diluted in the transfection reagent FuGENE was injected into the tumors (around 100 mm(2)), and paclitaxel was injected i.p. into the mice. Endostatin gene therapy synergized with paclitaxel in suppressing the growth of 4T1 tumors and their metastasis to the lung and liver. Both endostatin and paclitaxel inhibited tumor angiogenesis and induced cell apoptosis. Despite the finding that endostatin was superior to paclitaxel at inhibiting tumor angiogenesis, paclitaxel was nevertheless more effective at inducing tumor apoptosis. The combination of paclitaxel and endostatin was more effective in suppressing tumor growth, metastases, angiogenesis, and inducing apoptosis than the respective monotherapies. The combinational therapy with endostatin and paclitaxel warrants future investigation as a therapeutic strategy to combat breast cancer.

Effect of CDT6 on factors of angiogenic balance in tumour cell lines

BACKGROUND

Cornea-derived transcript 6 (CDT6, also known as AngX) is an angiopoietin-related factor resulting in anti-tumour effect in vivo. However, a recent abstract reported that CDT6 can also induce angiogenesis and promotes tumour growth. In our previous work, CDT6 had failed to show pro- or anti-angiogenic effects. It is unknown if CDT6 expression occurs in human cancer.

MATERIALS AND METHODS

An array of human tumour cell lines and tumour tissues was tested for CDT6-gene expression using RT-PCR. To address the controversial role of CDT6 on angiogenesis in different tumour models, the expression levels of four factors of the angiogenic balance (VEGF, endostatin, TIMP-1 and PAI-1) were determined in CDT6-transfected and control cells of the human and murine melanoma cell lines BLM and B16-F10. Endostatin was significantly up-regulated by CDT6 expression in the human model and significantly down-regulated in the mouse model. None of 18 cell lines or 23 tumours expressed CDT6.

CONCLUSION

This contradictory effect on endostatin expression in human and mouse models may be an explanation for the conflicting results for the effect of CDT6 expression on angiogenesis.

Expression of endostatin in merkel cell carcinoma

BACKGROUND

The aim of this study was to examine the expression of endostatin in Merkel cell carcinoma (MCC) and to correlate the expression with tumour growth and the development of metastasis.

PATIENTS AND METHODS

The study comprised 19 patients treated for MCC at the Helsinki University Hospital, Helsinki, Finland between 1987 and 2003. Endostatin expression was studied by immunohistochemistry. The correlations between the quantitative expression of endostatin and tumour parameters were analysed statistically.

RESULTS

The expression of endostatin was documented in only 40% of the samples. Endostatin correlated negatively with tumour size, and was expressed in 30% of the large and 56% of the small tumours. There was no difference in expression between tumours expanding to metastases and tumours with more indolent behaviour. The simultaneous expression of vascular endothelial growth factor receptor-2 and endostatin was distinguished in small-sized tumours.

CONCLUSION

This study showed a correlation between endostatin expression and small tumour size in Merkel cell carcinoma. This finding was further confirmed by the finding that tumours positive for VEGFR-2, but not for endostatin, seemed to be larger than tumours that showed simultaneous expression of VEGFR-2 and endostatin.

Lowering homocysteine decreases levels and expression of VEGF(165) and endostatin

BACKGROUND

Homocysteine, vascular endothelial growth factor (VEGF), and endostatin have been implicated in angiogenesis and in the development and progression of atherothrombotic vascular disease. We sought to determine whether homocysteine modulates plasma levels of VEGF and endostatin and their expression in leukocytes in patients with peripheral arterial disease (PAD) or diabetes mellitus (DM).

MATERIALS AND METHODS

Ten patients with PAD and 15 patients with type 2 DM were evaluated before and 6 wk after oral administration of folic acid and B vitamins. Evaluation included measurements of plasma levels of homocysteine, VEGF, and endostatin by enzyme-linked immunosorbent assay and the expression of VEGF and endostatin mRNAs in leukocytes using RT-PCR. The measurements were compared with baseline findings in 12 healthy subjects.

RESULTS

Basal homocysteine (P < 0.001) and VEGF (P < 0.01) levels were elevated in all patients versus healthy subjects. Basal endostatin levels were lower in patients with PAD but were higher in patients with DM compared with healthy subjects (P < 0.001). In patients with PAD or DM, folic acid and B vitamins administration resulted in significant reduction (P < 0.001) of plasma levels of homocysteine (20.9% and 26.2%), VEGF (29.7% and 40.4%) and endostatin (9.4% and 5.7%), respectively. Moreover, VEGF and endostatin mRNA expression in leukocytes was down-regulated in all patients after B vitamins and folate treatment.

CONCLUSION

These findings demonstrate that lowering of homocysteine with B vitamins and folic acid resulted in substantial reduction of plasma levels of VEGF but minimal reduction of endostatin and in down-regulation of their expression in leukocytes in patients with PAD or DM.

Modulation of angiogenic phenotype alters tumorigenicity in rat ovarian epithelial cells

Vascular endothelial growth factor (VEGF) expression correlates with microvessel density, stage, malignant ascites, metastasis, and survival in ovarian cancer. By transducing VEGF165 into a nontumorigenic rat ovarian surface epithelial cell line (ROSE199), we investigated the direct effect of an angiogenic phenotype on tumor development. The neu oncogene, which is overexpressed in >30% of ovarian cancers, was used in comparison. Neu-transfected ROSE199 cells showed phenotypic characteristics of transformation in vitro with an abundance of focus-forming units in monolayer cultures and anchorage-independent growth in soft agar. In contrast, VEGF-secreting ROSE199 cells (VR) retained normal morphology and in vitro growth characteristics (e.g., proliferation rate) compared with parental ROSE199 cells. Interestingly, injection of VR cells into athymic mice formed malignant ascites in 100% of the animals when injected into the peritoneum and developed vascularized tumors in 85% of the mice when injected s.c. Furthermore, blocking VEGF-mediated signaling by the Flk-1/KDR receptor kinase inhibitor SU5416 significantly inhibited the growth of VR tumors. To validate that the proangiogenic switch is responsible for tumor development, the angiogenic phenotype was balanced by the inducible coexpression of endostatin under the control of Tet-activated promoter. Coexpression of endostatin along with VEGF reversed the tumorigenic phenotype of VR cells. These studies show that alterations in the angiogenic characteristics of ovarian surface epithelium may play an important role in the etiology of ovarian cancer, and that inhibition of angiogenesis can be effective in the treatment of epithelial ovarian cancer.

[Effect of the in vitro culture and cryopreservation on the growth of the microencapsulated recombinant cell and endostatin production]

Microencapsulated recombinant cells technology is a novel approach to tumors therapy. It is necessary to prepare a plenty of the microcapsules with better cell viability and higher endostatin production in order to bring this technology into the clinic. The in vitro culture and cryopreservation are very important parameters in the preparation of microencapsulated cells. In this work, we studied the effect of the in vitro culture and cryopreservation on microencapsulated recombinant cells growth and endostatin production and the effect of the in vitro culture on the cryopreservation of microencapsulated recombinant cells. The results showed that the time of in vitro culture potently affected microencapsulated recombinant CHO cells growth in vivo, endostatin production and the microcapsule stability. The microcapsule kept intact after 36 days of implantation when the in vitro culture time was under 4 days. The thawed microencapsulated recombinant CHO cells had better cell growth and higher endostatin production after 40 days of cryopreservation when the in vitro culture time was 4 days and 8 days. Therefore, the best in vitro culture time was 4 days according to the results of the in vivo culture and cryopreservation and the cryopreservation did not affect microencapsulated recombinant CHO cells growth in vivo, endostatin production and the microcapsule stability.

Generation of endostatin by matrix metalloproteinase and cathepsin from human limbocorneal epithelial cells cultivated on amniotic membrane

PURPOSE

Cultured human limbocorneal epithelial (HLE) cells secrete endostatin-related molecules that are augmented when the cells are cultivated on denuded amniotic membrane (DAM). This study is to identify mechanisms for enhanced endostatin production by HLE cells cultivated on AM.

METHODS

HLE cells were cultured on dish, on intact AM (IAM) or on DAM. Collagen XVIII alpha1 mRNA was analyzed by real-time quantitative PCR. In HLE/DAM cultures, inhibitors of MMPs (GM-6001; 1,10-phenanthroline), cathepsins (E64; cathepsin B inhibitor II), elastase (elastatinal), and serine proteases (AEBSF; aprotinin) were added. Endostatin in the conditioned medium (CM) was detected by Western blot. MMP-7; MMP-9; and cathepsins B, K, L, and V in the CM were quantitated by ELISA. Exogenous cathepsin B or V was added to the concentrated HLE/DAM CM to see the effect on endostatin production.

RESULTS

The expression of collagen XVIII alpha1 mRNA in the three groups was similar. Elastatinal, AEBSF, and aprotinin had no effect on endostatin generation. MMP inhibitors inhibited the generation of all the 20- and 28- to 30-kDa endostatin-related fragments, while cathepsin inhibitors inhibited only the 20-kDa endostatin. The level of MMP-7 and cathepsin B but not cathepsin V increased as the culture time increased, and paralleled with endostatin production. However, cathepsins K and L were absent in the CM. Exogenous cathepsins B and V further augmented the generation of endostatin.

CONCLUSIONS

MMP-7 and cathepsins B and V are involved in the generation of endostatin by HLE cells. Facilitating endostatin generation may be a novel physiological function of the cornea-specific cathepsin V.

The level of synthesis and secretion of Gaussia princeps luciferase in transfected CHO cells is heavily dependent on the choice of signal peptide

There is a great demand for the improvement of mammalian cell production systems such that they can compete economically with their prokaryotic counterparts. Of a number of parameters that need to be explored to accomplish this we have tested the effects of different signal peptides on the synthesis and secretion of Gaussia princeps luciferase in mammalian cells. A series of plasmids were transfected into CHO cells where the coding region for the marine luciferase was fused to the signal peptide coding regions derived from different sources. Both cell extracts and medium samples were analysed for luciferase activity. When the native Gaussia luciferase signal sequence in the vector was substituted by that from human interleukin-2 or albumin then the amount of active recombinant protein produced was substantially reduced, both in transiently and stably transfected cells. Western blotting showed that enzyme activity and protein levels mirrored one another. The major decrease in luciferase activity was shown not to be a result of decreased mRNA levels, indicating the involvement of a post-transcriptional event. When the coding region of human endostatin was fused to that of the Gaussia luciferase signal peptide then an elevated level of secreted endostatin was observed compared to when that of the albumin signal peptide was used. Stable transfection of HepG2 cells with the different signal peptide constructs gave essentially the same results as seen in CHO cells. The overall results indicate that the choice of signal peptide can be imperative to ensure an optimal synthesis and secretion of a recombinant protein in a mammalian cell culture system.

Optimization of microencapsulated recombinant CHO cell growth, endostatin production, and stability of microcapsulein vivo

Microencapsulation of recombinant cells secreting endostatin offers a promising approach to tumor gene therapy in which therapeutic protein is delivered in a sustainable and long-term fashion by encapsulated recombinant cells. However, the studies of cell growth and protein production in vivo are very limited. In this study, the effects of microencapsulation parameters on in vivo cell growth, endostatin production, and microcapsule stability after implantation in the peritoneal cavity of mice were for the first time investigated. Microcapsules with liquid core reached higher cell density and endostatin production at day 18 than microcapsules with solid core. There was no significant difference in stability whether the core of the microcapsule was solid or liquid. Decrease in microcapsule size increased the stability of microcapsule. The microcapsules kept intact in the peritoneal cavity of mice after 36 days of implantation when the microcapsules size was 240 microm in diameter, which gave rise to high endostatin production as well. The optimized microencapsulation conditions for in vivo implantation are liquid core and 240 microm in diameter. This study provides useful information for antiangiogenic gene therapy to tumors using microencapsulated recombinant cells.

[Construction of a recombinant adenoviral vector expressing human endostatin]

OBJECTIVE

To construct the recombinant adenovirus vector expressing human endostatin.

METHODS

Human endostatin gene extracted from pGEM-T Easy vector containing the target gene fragment was successfully amplified using PCR and cloned into pShuttle2 vector. The target gene was subcloned into an adenovirus vector and the resulted recombinant adenovirus (Ad-hEndo) was linearized before transfected into HEK 293 packaging cells. The Ad-hEndo recombinant adenovirus was efficiently amplified in 293T cells and purified by CsCl density centrifugation, and the titer of the virus was determined.

RESULTS

The amplified hEndostatin cDNA was verified by PCR and sequencing, and the resulted virus titer reached 5.2 x 10(9) pfu/ml.

CONCLUSION

The recombinant adenovirus containing human endostatin gene has been successfully constructed, which may provide important basis for gene therapy research for angiogenesis-dependent diseases.

[Construction recombinant adenovirus vector expressing murine endostatin and inhibition of blood endothelial cells growth]

We constructed recombinant adenovirus vector expressing murine endostatin and evaluated the Inhibition of human umbilical vein endothelial cells (HUVEC). We proved that endostatin significantly suppressed the S phase fraction, inhibited proliferation and increased the apoptotic index of HUVEC.

[Two incompatible plasmids coexpress the human endostatin and predigested human plasminogen kringle 5 in E. coli]

OBJECTIVE

To construct the recombinant plasmid pET28a/hES and coexpress the human endostatin (hES) and predigested human plasminogen kringle 5 (predhPK-5) in E. coli.

METHODS

The mRNA was extracted from human liver tissue, and the endostatin gene was amplified by RT-PCR, which then was cloned into pET-28a(+). Under screening pressure by ampicillin and kanamycin simultaneously, E. coli BL21 (DE3) was cotransformed with pET28a/hES and pGEX-1lambdaT/predhPK-5 and induced with IPTG to express the recombinant proteins. The stability of cotransformants existing in E. coli was measured through two aspects in the serial culture time and passage number of bacterium.

RESULTS

The two incompatible plasmids could be coexisted under the pressure of two antibiotics (ampicillin and kanamycin). After induced with IPTG, both human endostation and predhPK-5 gene were coexpressed, and the recombinant proteins comprised about 20% and 21% of total cell proteins, respectively. The two incompatible plasmids could still be maintained in over 75% E. coli cells for at least 16 hours or after 120 passages under the pressure of two antibiotics.

CONCLUSION

The two incompatible plasmids pET28a/hES and pGEX-1lambda T/predhPK-5 may coexpress the recombinant proteins in E. coli. A new method for coexpression of proteins in E. coli containing two incompatible plasmids is proved to be feasible.

Surgical Results in T2N0M0 Nonsmall Cell Lung Cancer Patients With Large Tumors 5 cm or Greater in Diameter: What Regulates Outcome?

BACKGROUND

We assessed the surgical results along with the clinical and biological features of nonsmall-cell lung cancer (NSCLC) patients with localized large tumors.

METHODS

The study population consisted of 86 NSCLC patients who underwent complete resection of tumors 5 cm or larger in diameter in stage IB (T2N0M0). We immunohistochemically assessed the expression of angiostatin and endostatin.

RESULTS

The median tumor size was 6.0 cm (range, 5 to 14 cm). The operative procedures used were lobectomy in 71 cases, bilobectomy in 8 cases, and pneumonectomy in 11 cases. Fifty patients (58.1%) relapsed during the mean follow-up period of 33.6 +/- 4.5 months. The median disease-free interval was 9 months. Of 44 recurrent patients whose disease-free interval could be identified, 25 patients (56.8%) relapsed within 12 months after the operation. The overall 5- and 10-year survival rates were 42.0% and 24.2%, respectively. Multivariate analysis showed that the degree of pleural involvement and angiostatin expression within the tumor were independent prognostic indicators. The endostatin expression within tumors also had a weaker relationship with outcome.

CONCLUSIONS

Long-term surgical results were poor and early relapse was common in this cohort. In addition to pleural involvement, the tumor-induced expression of angiostatin and endostatin merit further investigation to gain possible insights into selection of patients who will benefit from surgery as the first line treatment.

[Fusion expression and identification of angiostatin and endostatin in E. coli BL21(DE3)]

Angiostatin(AS) and endostatin(ES) are both potent endogenous angiogenesis inhibitors, and the combination of AS and ES has been shown to have synergistic antiangiogenic effects. Here we report the fusion protein AS-ES expressed in E. coli which has antiangiogenic effects. At first, AS and ES genes were cloned respectively through RT-PCR, then fusion gene was made through gene splicing ,finally pET-42 (b)/AS-ES expression plasmid was constructed and transduced in E. coli BL21 (DE3). Target protein was in form of inclusion body,the rate of expression was about 14%, and MW about 65KD. Western blotting assay showed expressed protein had specific immune reaction to both the antibodies of AS and ES. The expressed protein which was refolded and purified through heparin affinity chromatography had antiangiogenic effect to vessels on chicken embryo chorioallantoic membrane. The results show that fusion protein AS-ES was expressed successfully in E. coli, and the expressed protein,which was renatured and purified, had immuno-reactivity to anti-AS and anti-ES in Western blotting and angiogenesis inhibition activity.

Hypercholesterolemia impairs the myocardial angiogenic response in a swine model of chronic ischemia: role of endostatin and oxidative stress

BACKGROUND

Recent studies have shown that angiogenesis is regulated by a balance between activators and inhibitors. We investigated the effects of hypercholesterolemia on the functional angiogenic response and collateral formation induced by chronic myocardial ischemia and the expression of angiogenic mediators.

METHODS

Twelve Yucatan miniswine, fed either a normal (NORM, n = 6) or high cholesterol (HCHO, n = 6) diet for 13 weeks, underwent ameroid constrictor placement around the circumflex artery. Three weeks later, myocardial perfusion was quantified using isotope-labeled microspheres. Seven weeks after ameroid placement, coronary microvascular responses and myocardial perfusion were assessed. Vascular density was evaluated by PECAM-1 (CD-31) staining, and vascular endothelial growth factor, endothelial nitric oxide synthase, endostatin, and angiostatin protein levels were determined. Myocardial protein oxidation was quantified.

RESULTS

Coronary microvessels from HCHO pigs showed significant endothelial dysfunction. Baseline-adjusted myocardial flow at 7 weeks was significantly reduced in the HCHO animals (-0.002 +/- 0.06 versus +0.23 +/- 0.09 mL/min/g, HCHO versus NORM, p = 0.04). Endostatin expression was significantly increased in the HCHO pigs (2.2-fold, p = 0.001 versus NORM). There was a mild reduction in myocardial vascular endothelial growth factor expression (-29% +/- 14%, p = 0.09) in HCHO animals, but no difference in expression of endothelial nitric oxide synthase and angiostatin. The HCHO animals demonstrated increased myocardial protein oxidation compared with the NORM group (+155% +/- 21%, p = 0.03 versus NORM).

CONCLUSIONS

Ischemia-induced angiogenesis is inhibited in hypercholesterolemic pigs with a concomitant increase in endostatin expression and oxidative stress. These findings suggest that under conditions of hypercholesterolemia, coronary collateral development may be regulated by endogenous angiogenesis inhibitors such as endostatin as well as reactive oxygen species.

High-dose atorvastatin improves hypercholesterolemic coronary endothelial dysfunction without improving the angiogenic response

BACKGROUND

Although 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) can restore endothelial function in coronary disease, in vitro and murine studies have shown their effects on myocardial angiogenesis to be biphasic and dose dependent. We investigated the functional and molecular effects of high-dose atorvastatin on the endogenous angiogenic response to chronic myocardial ischemia in hypercholesterolemic swine.

METHODS AND RESULTS

Yucatan pigs were fed either a normal (NORM group; n=7) or high-cholesterol diet, with (CHOL-ATR group; n=7) or without (CHOL group; n=6) atorvastatin (3 mg/kg per day) for 13 weeks. Chronic ischemia was induced by ameroid constrictor placement around the circumflex artery. Seven weeks later, microvessel relaxation responses, myocardial perfusion, and myocardial protein expression were assessed. The CHOL group demonstrated impaired microvessel relaxation to adenosine diphosphate (29+/-3% versus 61+/-6%, CHOL versus NORM; P<0.05), which was normalized in the CHOL-ATR group (67+/-2%; P=NS versus NORM). Collateral-dependent myocardial perfusion, adjusted for baseline, was significantly reduced in the CHOL group (-0.27+/-0.07 mL/min per gram versus NORM; P<0.001) as well as the CHOL-ATR group (-0.35+/-0.07 mL/min per gram versus NORM; P<0.001). Atorvastatin treatment was associated with increased phosphorylation of Akt (5.7-fold increase versus NORM; P=0.001), decreased vascular endothelial growth factor expression (-68+/-8%; P<0.001 versus NORM), and increased expression of the antiangiogenic protein endostatin (210+/-48%; P=0.004 versus NORM).

CONCLUSIONS

Atorvastatin improves hypercholesterolemia-induced endothelial dysfunction without appreciable changes in collateral-dependent perfusion. Increased myocardial expression of endostatin, decreased expression of vascular endothelial growth factor, and chronic Akt activation associated with atorvastatin treatment may account for the diminished angiogenic response.

[Relationship between endostatin and vascular cell adhesion molecule-1 expressions on bone marrow stromal cells in BMT-mice]

This study was aimed to investigate the relationship between endostatin and vascular cell adhesion molecule-1 (VCAM-1) expressions on bone marrow stromal cells (BMSC) in mice after bone marrow transplantation (BMT) and effect of ligustrazine on their expressions. The mice were randomly divided into 3 groups: normal group (without treatment), saline group (control of BMT) and ligustrazine group (BMT + ligustrazine). BMT mouse models were established. The normal group was not treated, the saline group was given normal saline (0.2 ml/mouse, twice a day) through gastric tube, while the ligustrazine group was given ligustrazine (0.2 ml/mouse, twice a day) also through gastric tube. On day 7, 14, 21 and 28 after BMT, mice were killed by euthanasia. The expression levels of endostatin and VCAM-1 in bone marrow stromal cells were detected by immunohistochemistry and RT-PCR analysis respectively. The results showed that the endostatin protein mainly expressed in nuclei of BMSCs, the VCAM-1 protein mainly expressed in plasma of BMSCs. On day 7, 14, 21 after BMT the expression levels of endostatin mRNA and protein in ligustrazine and saline groups were significantly lower than that in normal group (P < 0.01 or P < 0.05), while their expression levels in ligustrazine group were lower than that in saline group. On day 28 the expression levels in saline group returned to normal, while the expression levels in ligustrazine group not were normalized. On day 7, 14, 21 after BMT the expression levels of VCAM-1 mRNA and protein in ligustrazine and saline groups were significantly lower than that in normal group (P < 0.01 or P < 0.05), but their expression levels in ligustrazine group were significantly lighter than that in saline group (P < 0.01 or P < 0.05). On day 28 the VCAM-1 expression level in ligustrazine group returned to normal, while its expression level in saline group not were normalized. The difference between these two groups was significant (P < 0.01). Correlation analysis revealed that there was a negative correlation between endostatin and VCAM-1 expression in saline group, there was a positive correlation between endostatin and VCAM-1 expression in ligustrazine group. It is concluded that the endostatin can influence hematopoiesis in bone marrow by affecting VCAM-1 expression on BMSC and hindering connection between stromal cells and hematopoietic cells as well as extracellular stroma and hematopoietic cells, while ligustrazine can enhance the adhesion molecule expression on stromal cell surface of bone marrow in BMT-mice, accelerate the homing and proliferation of HSPC in bone marrow after BMT, meanwhile can promote the repair of bone marrow microenvironment, accelerate hematopoietic reconstitution of bone marrow after BMT through feedback regulation of endostatin expression of BMSC in BMT-mice.

[Antisense oligonucleotide targeting endostatin enhances hematopoiesis reconstitution in BMT mice]

OBJECTIVE

To explore the effect of antisense oligonucleotide targeting endostatin (endostatin-ASON) transfecting bone marrow stromal cells ( BMSC) on hematopoiesis reconstitution in BMT mice.

METHODS

Inhibition of endostatin / VCAM-1 protein and mRNA expression was investigated by transfection of antisense oligonucleotide targeting endostatin with confocal microscopy, Western blot and RT-PCR. Bone marrow stromal cells were cultured and divided into 4 groups: group (1) without any treatment; group (2) BMT only; group (3) BMT + endostatin-ASON transfection; group (4) BMT + endostatin scrambled sequence transfection.

RESULTS

(1) Endostatin-ASON was successfully introduced into BMSC in vitro, and the transfecting rate was 86% ;(2) After Endostatin-ASON transfected into BMSC, the expression of Endostatin mRNA and its protein on the BMSC was signficantly inhibited at different time point after BMT [the grey value of Endostatin was (0.09 +/- 0.03) - (1.44 +/- 1.19) and (0.02 + 0.02) - (0.14 +/- 0.05), respectively] (P < 0.01 and P < 0.05); (3) Transfecting with Endostatin-ASON effectively promoted the expression of VCAM-1 mRNA and its protein on the BMSC [the gray value of VCAM-1 was (1.60 +/- 0. 92) - (8.05 +/- 0.87) and (0.07 +/- 0.02) - (0.67 +/- 0.09) , respectively] (P <0.01 and P <0.05) ; (4) There was no effects of transfecting Endostatin scrambled sequence on the expression of Endostatin and VCAM-1 on the BMSC (P > 0.05).

CONCLUSION

Endostatin-ASON could inhibit Endostatin expression and enhance VCAM-1 expression in BMSC after syngeneic-BMT in mice, which might be one of the mechanisms underlying the endostatin-ASON accelerating hematopoiesis reconstitution after allogeneic-BMT.

Enhanced antiangiogenic therapy with antibody-collagen XVIII NC1 domain fusion proteins engineered to exploit matrix remodeling events

Antiangiogenic therapy is nowadays one of the most active fields in cancer research. The first strategies, aimed at inhibiting tumor vascularization, included upregulation of endogenous inhibitors and blocking of the signals delivered by angiogenic factors. But interaction between endothelial cells and their surrounding extracellular matrix also plays a critical role in the modulation of the angiogenic process. This study introduces a new concept to enhance the efficacy of antibody-based antiangiogenic cancer therapy strategies, taking advantage of a key molecular event occurring in the tumor context: the proteolysis of collagen XVIII, which releases the endogenous angiogenesis inhibitor endostatin. By fusing the collagen XVIII NC1 domain to an antiangiogenic single-chain antibody, a multispecific agent was generated, which was efficiently processed by tumor-associated proteinases to produce monomeric endostatin and fully functional trimeric antibody fragments. It was demonstrated that the combined production in the tumor area of complementary antiangiogenic agents from a single molecular entity secreted by gene-modified cells resulted in enhanced antitumor effects. These results indicate that tailoring recombinant antibodies with extracellular matrix-derived scaffolds is an effective approach to convert tumor progression associated processes into molecular clues for improving antibody-based therapies.

Endostatin/Collagen XVIII Accumulates in Patients with Traumatic Brain Injury

In patients with traumatic brain injury (TBI), hypoperfusion contributes to ongoing and expanding areas of neuronal damage long after the initial trauma has ceased. In order to evaluate whether the antiangiogenic protein endostatin may play a role in this process, we analyzed its spatial distribution in brains of 18 patients with TBI. We observed an increase of endostatin/collagen XVIII(+) macrophages/microglial cells but not astrocytes up to day 14 and a consequent decrease to day 16 post-TBI. In addition, paracellular endostatin/collagen XVIII deposits were detected. In vitro experiments revealed that microglial endostatin release is induced predominantly by hypoxia and, to a lesser extent, by reactive oxygen intermediates. Common NO synthase inhibitor pharmacotherapy with aminoguanidine and L-NAME completely abolished endostatin release from microglial cells, raising hopes of altering endostatin release in vivo.

[Expression and role of endostatin in the retina of oxygen-induced retinopathy mouse model]

OBJECTIVE

To investigate the effect of endostatin on the pathogenesis and development of retinal neovascula animal model of oxygen-induced retinopathy.

METHODS

The animal model of oxygen-induced retinopathy was made by subjecting postnatal mice to hyperoxic conditions (5 days) followed by normoxic conditions. Retinal angiogram was taken by using high molecular weight fluorescein-dextran. The degree of hyperoxia-induced neovascularization in serial paraffin cross-sections was quantified by counting the number of vascular cell nuclei on vitreal side of the internal limiting membrane. The expression of ES and VEGF in the oxygen-induced retina was observed by immunohistochemistry.

RESULTS

We successfully constructed the oxygen-induced retinopathy mouse model. FITC-dextran retinal angiography indicated that hyperoxia could produce constriction of retinal vasculature and vaso-obliteration or irreversible closure of many capillary channels and eventually result in non-perfused area in the post-area of retina surrounding the optic disk. Relatively, hypoxia could lead to dilation and torsion of retinal vessels. There were averagely 22 neovascular nuclei per cross-section of eyes in the hyperoxia group and less than 3 nuclei per cross-section of eyes in the control group (P < 0.05). The expressions of ES and VEGF in the retina under hyperoxia were stronger than those under normoxia, expecially the expression of VEGF.

CONCLUSION

Taking measures to up-regulate the expression of endogenetic endostatin may have the potential for effective treatment of retinal ischemic neovascularization.

Moderate antiangiogenic activity by local, transgenic expression of endostatin in Rip1Tag2 transgenic mice

Many previous reports have demonstrated that systemic administration of endostatin (ES), a proteolytic cleavage product of collagen type XVIII and an endogenous angiogenesis inhibitor, represses tumor angiogenesis in different preclinical tumor models with varying efficacy. For example, systemic delivery of recombinant ES to rat insulin promoter 1 (Rip1)T-antigen 2 (Tag2)-transgenic mice, a mouse model of pancreatic beta-cell carcinogenesis, has repressed tumor angiogenesis efficiently and with it, tumor growth. Here, we report that the transgenic expression of ES in Rip1ES-transgenic mice only interferes moderately with tumor growth in Rip1Tag2;Rip1ES double-transgenic mice. Tumor incidence is not reduced by the local expression of ES, and tumor outgrowth and progression to tumor malignancy are only retarded slightly. A significant effect of local ES expression on tumor angiogenesis is only apparent during the early stages of tumor development, where less angiogenic hyperplastic lesions are observed. Although efficiently produced and secreted by transgenic beta cells, locally expressed ES appears to be sequestered in the microenvironment, and its systemic levels are not increased. The results indicate that the antiangiogenic functions of ES critically depend on the mode of delivery and the site of expression: although its systemic application represses tumor angiogenesis and tumor growth efficiently, locally expressed ES appears to be less effective, and hence, additional mechanisms of solubilization or activation of latent ES seem to be required. These results have important implications about the modes of delivery used in antiangiogenic, therapeutic strategies, which are based on the antiangiogenic activities of ES.

Adeno-associated virus-mediated delivery of a mutant endostatin in combination with carboplatin treatment inhibits orthotopic growth of ovarian cancer and improves long-term survival

A human ovarian cancer cell line, which migrates to mouse ovaries and establishes peritoneal carcinomatosis, was used to evaluate the cooperative effect of an antiangiogenic gene therapy combined with chemotherapy. The ovarian carcinoma cell line MA148 was genetically modified by "Sleeping Beauty" transposon-mediated delivery of DsRed2 fluorescent protein. Stable, high-level expression of DsRed protein enabled in vivo imaging of peritoneal dissemination of ovarian cancer. Both external and internal imaging, along with histopathology, showed migration of i.p. injected human ovarian cancer cell line to mouse ovaries. Using this model, we evaluated the effect of adeno-associated virus (AAV)-mediated expression of a mutant endostatin either alone or in combination with carboplatin treatment. A single i.m. injection of recombinant AAV (rAAV)-mutant human endostatin with P125A substitution (P125A-endostatin) showed sustained expression of mutant endostatin. Antiangiogenic gene therapy inhibited orthotopic growth of ovarian cancer and resulted in 33% long-term tumor-free survival. A single cycle of carboplatin treatment combined with mutant endostatin gene therapy resulted in 60% of the animals remaining tumor free for >200 days, which was significantly better than rAAV-LacZ and/or carboplatin. Combination treatment delayed tumor appearance in 40% of the animals, wherein the residual tumors were smaller in size with limited or no peritoneal metastasis. These studies suggest that AAV-mediated gene therapy of P125A-endostatin in combination with carboplatin is a useful method to inhibit peritoneal dissemination of ovarian carcinoma.

Estradiol and Tamoxifen Regulate Endostatin Generation via Matrix Metalloproteinase Activity in Breast CancerIn vivo

Matrix metalloproteinases (MMP) are important regulators of tumor progression and angiogenesis. MMPs generate both proangiogenic and antiangiogenic fragments, such as vascular endothelial growth factor and endostatin. The in vivo activation of MMPs and endostatin generation occur mainly in the extracellular environment by interactions of different cell types. Therefore, these processes are necessary to study in the extracellular space in vivo. Sex steroids play a dominant role in breast carcinogenesis, by largely unknown mechanisms. In the present study, we used in vivo microdialysis to directly quantify MMP-2 and MMP-9 activity and sample endostatin from both stroma (murine) and tumor (human) cells in vivo in solid MCF-7 tumors in nude mice. We found that tamoxifen in combination with estradiol increased tumor MMP-2/MMP-9 in vivo activity, endostatin levels, and decreased tumor vascularization compared with estradiol treatment only. The stroma-derived endostatin was three to five times higher than cancer cell-generated endostatin. After inhibition of MMP-2/MMP-9, endostatin levels decreased, providing evidence that these proteases are highly involved in the generation of endostatin. Our results support the previously reported concept that MMPs may serve as negative regulators of angiogenesis. The regulation of endostatin generation by modulation of MMP-2/MMP-9 activities suggests a previously unrecognized mechanism of estradiol and tamoxifen, which may have implications for the pathogenesis of breast cancer.

Endostatin-cytosine deaminase fusion protein suppresses tumor growth by targeting neovascular endothelial cells

Endostatin, an angiogenesis inhibitor tested in multiple clinical trials, selectively targets neovascular endothelial cells, suppressing tumor growth. To enhance the therapeutic efficacy of endostatin, we fused endostatin with cytosine deaminase, which converts a prodrug 5-flucytosine into a cytotoxic 5-fluorouracil. This therapeutic strategy was developed based on the observation that the endostatin-green fluorescence protein gene and endostatin-luciferase gene selectively target to endothelial cells in vitro and to the tumor site in vivo, respectively. When we used the endostatin-cytosine deaminase fusion protein to treat s.c. grafted tumors or experimental metastasis tumors, our results showed that endostatin-cytosine deaminase treatment provided stronger tumor growth suppression and increased mean survival time of the mice compared with the treatments of endostatin alone, cytosine deaminase alone, or endostatin plus cytosine deaminase. The endostatin-cytosine deaminase protein significantly inhibited the growth of endothelial cells and preferentially induced tumor cell apoptosis. This endostatin-cytosine deaminase fusion approach opens an avenue for cancer-targeting therapy.

Hypoxia-induced increase of endostatin in murine aorta and lung

In the lung, hypoxia induces pulmonary hypertension caused by vasoconstriction and vascular remodeling. Additionally, hypoxia is an inducer of angiogenesis, which is assumed to counteract pulmonary hypertension. We asked whether the anti-angiogenic factor endostatin--a cleavage product of collagen XVIII--participates in the vascular alterations induced by hypoxia. By employing Western blotting of tissue extracts of murine brain, liver and heart an endostatin fragment of 22 kDa was detectable, whereas in lung and aorta additional bands of 24 and 26 kDa were found. The amount of these larger fragments was increased in tissues obtained from mice housed for 4 days or 3 weeks at hypobaric hypoxia. By immunohistochemistry endostatin was detected in association with elastic fibers and in close neighborhood to smooth muscle cells of intrapulmonary vessels and the aorta. In the lung, the activity of matrix metalloproteinases (MMP) known to generate endostatin by cleavage of collagen XVIII was increased (MMP-2) and decreased (proMMP-9), respectively, by hypoxia. Elevated amounts of endostatin within the aortic wall of mice exposed to hypobaric hypoxia may stabilize the vascular wall by inhibition of microvascular sprouting. The surprising finding of increased endostatin in the lung presumably contributes to the development of pulmonary hypertension by reduction of angiogenesis.

[The effect of glutamine on the growth, metabolism and endostatin production of microencapsulated rCHO cells]

Cell transplantation is a promising technology in cancer therapy, however, immunological rejection is the major problem of cell transplantation. Based on the permselective property of microcapsule membrane, encapsulated cells can be immuno-protected. The normal physiological state and function expression of cells can be maintained so as to realize allo- or xenotransplantation. The microencapsulated cells grow in three dimensions, giving a more biologically representative in vivo model, which hints difference in characters of growth and metabolism compared to the monolayer cells. Therefore, characterization of growth and metabolism of microencapsulated recombinant CHO cells is essential for further large-scale culture. In present study, the effect of concentration of glutamine on the growth, metabolism and endostatin production of microencapsulated cells was investigated. In the experimental range of initial glutamine concentrations from 2.69mmol/L to 9.05mmol/L in the culture of microencapsulated recombinant CHO cells, the maximum density of active cells and multiplication ratios almost kept constant. The specific consumption rate of glucose increased with lower initial glutamine concentration (2.69mmol/L). When initial glutamine concentration was much higher (7.91mmol/L to approximately 9.05mmol/L), the specific consumption rates of both glucose and glutamine increased while the efficiencies of glucose and glutamine decreased. The highest efficiencies of glucose and glutamine utilization were observed with initial glutamine concentration of 4.97mmol/L. It was also demonstrated that glutamine had significant effect on the accumulation of endostatin. The accumulative concentration of endostain reached its peak of 546.36 ng/mL with the initial glutamine concentration of 4.97mmol/L.

[Human endostatin gene transfected adult skin melanoma cells]

OBJECTIVE

To study the biological characteristics of human endostatin (hEndo) gene transfected adult skin melanoma cells in vitro and in vivo.

METHODS

The plasmid pcDNA3.1 (-)-hEndo was transfected into adult skin melanoma cells by electroporation, and then the stable clones were selected with G418. The transcription and expression of hEndo gene in the transfected melanoma cells were verified by RT-PCR and agarose gel electrophoresis analysis and Western blot. The biological activities of hEndo protein were investigated by MTT in vitro. Stable clones expressing endostatin were subcutaneously injected into the right flank of BALB/c-nu/nu mice of 4 to approximately 6 weeks old. Then the growth of transduced tumors in vivo was investigated.

RESULTS

The bands of 624 bp and 5.4 kb were identified from digested plasmid pcDNA3.1 (-)-hEndo. The stable clones were selected with G418 after the eletroporation, the expression of hEndo mRNA was verified by RT-PCR, and Western blot displayed the expression product of hEndo was about 20 kD in the transfected melanoma cells. MTT showed that the conditioned medium of melanoma cells transduced with recombination human endostatin expression vector could inhibit the proliferation of human umbilical vein endothelial cells in vitro. The growth of transduced cells in vivo showed that transfected melanoma cells grew in vivo at a slower rate than the control cells (P < 0.05). RT-PCR showed that endostatin expressed in the transduced tumors.

CONCLUSION

Adult skin melanoma cells in vitro transfected with exogenetic hEndo gene can express and secrete active hEndo, and inhibit the growth of transduced tumors in vivo.

Expression of soluble, biologically active recombinant human endostatin in Escherichia coli

Endostatin, a 20kDa C-terminal fragment of collagen XVIII, is a potent anti-angiogenic protein and inhibitor of tumor growth. Recombinant endostatin was prepared from Escherichia coli deposited as insoluble, inactive inclusion bodies. In the present study, we produced soluble and biologically active recombinant human endostatin (rhEndostatin) in E. coli by employing both co-expression of the molecular chaperones and lower temperature fermentation. Two groups of chaperones Trigger factor and GroEL-GroES (GroEL/ES), DnaK-DnaJ-GrpE and GroEL/ES, were co-expressed, respectively, with rhEndostatin at different temperatures (37, 25, and 16 degrees C). It revealed that low temperature or molecular chaperones alone could enhance the production of active rhEndostatin; meanwhile, combinational employment of low temperature cultivation (16 degrees C) together with co-expression of DnaK-DnaJ-GrpE and GroEL/ES was more effective to prevent aggregation of rhEndostatin. The production of soluble rhEndostatin was about 36 mg/L, and at least 16 mg of rhEndostatin was purified from 1L flask culture. The purified rhEndostatin specifically inhibited the proliferation of endothelial cell-bovine capillary endothelial cell in a dose-dependent manner, and it showed potent anti-angiogenic capability on the chorioallantoic membrane of chick embryo in vivo. Our study provides a feasible and convenient approach to produce soluble and biologically active rhEndostatin.

[Expression and clinical significance of endostatin and vascular endothelial growth factor in ovarian carcinoma]

BACKGROUND & OBJECTIVE

Vascular endothelial growth factor (VEGF) can induce angiogenesis, tumorigenesis, invasion, and metastasis of tumors; while endostatin has opposite functions. This study was designed to explore the expression of endostatin and VEGF in epithelial ovarian cancer, and investigate their correlations to oncogenesis and progression of ovarian cancer.

METHODS

The mRNA and protein levels of endostatin and VEGF in 63 samples of epithelial ovarian cancer and 19 samples of normal ovarian tissue were detected with reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry.

RESULTS

The mRNA levels and positive rates of endostatin and VEGF proteins were significantly higher in epithelial ovarian cancer than in normal ovarian tissue (P<0.05), and were significantly higher in stage III-IV ovarian cancer than in stage I-II ovarian cancer (P<0.05). Positive rate of endostatin protein was significantly lower in endostatin mRNA level of < or =0.5 group than in endostatin mRNA level of >0.5 group (29.4% vs. 77.8%, P<0.05); positive rate of VEGF protein was significantly lower in VEGF mRNA level of < or =0.5 group than in VEGF mRNA level of >0.5 group (25.0% vs. 72.0%, P<0.05).

CONCLUSIONS

The changes in mRNA levels of endostatin and VEGF in epithelial ovarian cancer are accordant to the changes in positive rates of the proteins. The imbalance between VEGF and endostatin may be related with tumorigenesis and development of epithelial ovarian cancer.

[Optimization of fermentation of recombinant human Endostatin (rh-Endostatin) expression in Escherichia coli]

The fermentation process of recombinant human Endostatin expression in Escherichia coli BL21 (DE3) was studied. The effects of factors such as concentration of IPTG, induction time, cultivation temperature and feeding strategies were investigated. Beside that, by changing the temperature to 40 degrees C after induction, the high-density cultivation finished in a much shorter period. After 9 hours cultivation, the optical density (OD) at 600 nm reached 140 and the yield of inclusion body was 3 g/L. While E. coli system was used, protein with better activity and stability was obtained. The cost was much lower and the producing process was much steadier. It will meet the demands of the industrial production.

[Angiogenesis and regulatory factors in rats with BPH induced by testosterone]

OBJECTIVE

To study angiogenesis and regulatory factors in the proliferated prostatic tissues of Sprague Dawley (SD) rats with BPH induced by testosterone.

METHODS

Sixteen castrated SD rats, aged 8 weeks and weighing 200 approximately 250 g, were equally randomized into a model group and a control group, and the BPH model was established by subcutaneous injection of testosterone. Immunohistochemistry and MIAS (micro-image analysis system) were used to test the manifestations of MVD (microvessel density), VEGF (vascular endothelium growth factor), flk-1, endostatin, MMP-2 (matrix metalloproteinase-2) and TIMP-2 (tissue inhibitor of metalloproteinase-2) in the prostatic tissues of both the model and the control groups. Multiple linear regression with the stepwise method was adopted to analyze the data.

RESULTS

The manifestations of MVD, VEGF, flk-1, MMP-2, MMP-2/TIMP-2 and VEGF/endostatin in the model group were higher, while that of endostatin was lower than in the control group (P < 0.01), and the manifestation of TIMP-2 showed no statistical difference between the two groups. The regression analysis indicated that MVD was positively correlated to VEGF, VEGF/endostatin and MMP-2/TIMP-2 (r = 0.974, 0.986, 0.982, P < 0.05) and negatively correlated to endostatin (r = - 0.975, P < 0.05) .

CONCLUSION

Testosterone could induce BPH in SD rats by increasing MVD and promoting the multiplication of vascular endothelial cells after regradation of basement membrane.

[Adeno-associated virus-mediated expression of human endostatin and its biological activity in vitro]

OBJECTIVE

To construct the recombinant adeno-associated viral vector containing human endostatin gene (rAAV-hEndo) and observe the biological activity of the expressed human endostatin in vitro.

METHODS

rAAV-hEndo was prepared using a helper virus-free packaging system. The rAAV viral genome titer was quantified by Taqman real-time PCR, and the endostatin expressed in human umbilical vein endothelial cell line ECV304 was detected by immunofluorescence staining. The effects of endostatin on ECV340 cells were evaluated by MTT cell proliferation assay, cell cycle analysis and terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL) technique.

RESULTS

The viral titer of rAAV-hEndo prepared was 2 x 10(12) vg/ml and the vector had an infection efficiency of 98%. Immunofluorescence staining showed that the human endostatin protein was expressed mainly in the cytoplasm of ECV304 cells, and the proliferation of the cells was obviously inhibited by the supernatant of rAAV-hEndo, with a inhibition rate of 67.3% 72 h after the addition of the supernatant. ECV304 cells infected with rAAV-hEndo were obviously arrested in G(1) phase, and the G(1)-phase cell percentage of treatment group were significantly higher than that of control group [(72.5+/-4.0)% vs (52.1+/-2.1)%, P<0.01]. ECV304 cells infected with rAAV-hEndo demonstrated markedly enhanced apoptosis, with a significantly greater apoptotic index than that of the control cells [(32.6+/-3.2)% vs (4.2+/-1.9)%, P<0.01].

CONCLUSION

rAAV-hEndo can effectively mediate the expression of biologically active human endostatin, which may facilitate further study of antiangiogenic gene therapy with endostatin for cancers.

Oncolytic herpesvirus with secretable angiostatic proteins in the treatment of human lung cancer cells

BACKGROUND

The wild-type herpes simplex virus type 1 (HSV-1) has strong infectivity and cytolytic effect on almost all types of mammalian cells. Genetic engineering can now restrict this cytolysis to only malignant cells. G207 is an oncolytic HSV-1 vector developed based on this strategy.

MATERIALS AND METHODS

We used G207 as the backbone and integrated the exogenous endostatin-angiostatin fusion protein gene to generate a new vector, AE618.

RESULTS

Marked expressions of fusion protein in A549 and H460 lung cancer cells and culture medium were found 24 hours after treatment with AE618. In comparison with the G207 treatment group, the secreted protein from H460 cells treated with AE618 significantly inhibited the growth of human umbilical vein endothelial cells (HUVEC). AE618 also significantly inhibited the growth of xenografted tumors in vivo.

CONCLUSION

We propose that AE618 has the potential to be a novel anticancer agent with both oncolytic and anti-angiogenesis effects.

[Cloning, expression, purification and characterization of human endostatin gene]

OBJECTIVE

To procure biologically active human endostatin.

METHODS

Human endostatin gene was acquired by means of reverse transcriptase (RT)-PCR and cloned into PGEM-T vector with subsequent sequence identification. The gene fragment was inserted into the prokaryotic expression vector pBV220 and transformed into E.coli DH5alpha strain. Endostatin expression in the E.coli was identified and the inclusion body isolated, purified and its activity analyzed.

RESULTS

The obtained gene fragment 552 bp in length was identified as the functional section of human endostatin gene by sequence analysis, and SDS-PAGE analysis showed that the expressed product was the target protein with biological activity.

CONCLUSION

Human endostatin gene was expressed in E.coli and the protein obtained can inhibit the proliferation of ECV 304 cells.

Endostatin's heparan sulfate-binding site is essential for inhibition of angiogenesis and enhances in situ binding to capillary-like structures in bone explants

The functional role of endostatin's affinity for heparan sulfates was addressed using an ex vivo bone angiogenesis model. Capillary-like sprouts showed prominent expression of collagen XVIII/endostatin. Outgrowth of endothelial cells was not altered in the absence of collagen XVIII but inhibited by the addition of recombinant endostatin. Mutant non-heparan sulfate binding endostatin and the collagen XV endostatin homologue were ineffective. The ability of mutant endostatin to bind to capillary structures was reduced when compared to endostatin. Endostatin-XV completely failed to bind to endothelial cells. Our data indicate that endostatin's angiostatic function is heparan sulfate-dependent, and that in situ-binding of endostatin to endothelial cells is increased by heparan sulfates.

Rapid, in vivo, evaluation of antiangiogenic and antineoplastic gene products by nonviral transfection of tumor cells

Using a nonviral, electroporation-based gene transfection approach, we demonstrate the efficient and consistent transfection of two poorly immunogenic tumor cell lines: B16F10 melanoma and renal carcinoma (RENCA). Three genes, IL-12, angiostatin (AS), and an endostatin:angiostatin fusion protein (ES:AS) were subcloned into a DNA plasmid containing EBNA1-OriP, which was then transfected into B16F10 and RENCA cells. Significant levels of protein were secreted into the culture supernatants of transfected cells in vitro. Transfected tumor cells were injected subcutaneously into mice. All the three transgenes were capable of significantly delaying and reducing the formation of primary B16F10 and RENCA tumors, as well as B16F10 lung metastases. By day 11 post-injection, all control mice that received either mock-transfected or empty vector DNA-transfected B16F10 tumor cells had developed large primary tumors. In contrast, mice that received IL-12-transfected B16F10 cells did not develop appreciable tumors until day 17, and these were significantly smaller than controls. Similar results were observed for the RENCA model, in which only one of the IL-12 mice had developed tumors out to day 31. Expression of AS or ES:AS also significantly delayed and reduced primary tumors. Overall, ES:AS was more effective than AS alone. Furthermore, 25% of the AS mice and 33% of the ES:AS mice remained tumor-free at day 17, by which point all control mice had significant tumors. Mouse survival rates also correlated with the extent of tumor burden. Importantly, no lung metastases were detected in the lungs of mice that had received either AS or ES:AS-transfected B16F10 tumor cells and significantly fewer metastases were found in the IL-12 group. The consistency of our transfection results highlight the feasibility of directly electroporating tumor cells as a means to screen, identify, and validate in vivo potentially novel antiangiogenic and/or antineoplastic genes.