Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0598934 (tumor growth)
 58,965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The turnover of endothelium in a normal adult male is very low. Angiogenesis, the formation of new blood vessels, involves a high turnover of endothelial cells. It takes place during embryogenesis, ovulation and many pathological conditions, e.g. tumor growth. Soluble polypeptide growth factors for endothelial cells have been biochemically characterized. They are able to induce angiogenesis in vivo. Inhibitors of angiogenesis can inhibit tumor vascularization and the growth of solid tumors in mice. Tumor metastasis involves the migration of malignant tumor cells through endothelial cells. The organ and tissue specificity of these and other invasive migrations through vascular endothelium may be related to the heterogeneity and organ specificity of endothelial cells.
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PMID:[Endothelium, angiogenesis and metastasis]. 244 11

Two immunogenic, syngeneic murine tumors were used to analyze the immunopathological processes associated with the immune rejection of primary intraocular tumors. Intracameral inoculation of P91 mastocytoma, an immunogenic variant of P815 mastocytoma, into DBA/2 mice resulted in progressive tumor growth for several weeks before immune rejection eradicated the intraocular neoplasm. The histopathologic characteristics of the tumor rejection included: a) destruction of the vascular endothelium of the microvasculature feeding the tumor; b) ischemic bulk necrosis; c) extensive innocent bystander damage to normal ocular structures; and d) absence of direct inflammatory cell-to-tumor cell contact. Thus, the immunopathological features resembled a delayed-type hypersensitivity (DTH) lesion. A second intraocular tumor model was similarly studied. UV5C25 fibrosarcoma grew slowly in the eyes of syngeneic BALB/c hosts. In sharp contrast to P91 tumors, a mononuclear cellular infiltrate was prominent within the tumor. After 5 wk, the intraocular tumors were completely rejected without detectable damage to normal ocular structures. The rejection of UV5C25 tumors did not produce scar tissue, damage to vascular endothelium, bulk necrosis, or atrophy of the globe. Although tumor-specific cytotoxic T lymphocytes (CTL) and DTH responses were readily detected, there was no histological evidence for DTH-mediated tumor rejection. Moreover, in situ immunoperoxidase staining indicated that the majority of the infiltrating lymphocytes were CTL, based on their characteristic phenotype: Thy-1+, Lyt-2+. Furthermore, the growth of UV5C25 fibrosarcoma in athymic, natural killer (NK) cell competent BALB/c nude mice demonstrated progressive tumor growth without infiltrating host cells. Collectively, the results indicate that immunogenic intraocular tumors can undergo strikingly different patterns of immune rejection with profoundly different pathological consequences. In one case (P91), tumor rejection occurs by a process that strongly resembles DTH and produces extensive nonspecific damage to normal tissues, resulting in irrevocable loss of vision. In contrast, the second intraocular tumor undergoes an immune rejection that is characterized by precision and a notable absence of damage to normal ocular tissues. The weight of evidence presented here strongly supports the hypothesis that the latter form of tumor rejection is mediated by CTL. Thus, the immunologic pathway invoked for tumor rejection in the eye has a profound effect on the fate of this delicate organ and the preservation of vision.
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PMID:Destructive and nondestructive patterns of immune rejection of syngeneic intraocular tumors. 310 94

The process of tumor growth and metastasis is a complex cascade of events relating many factors. The adhesion molecules relate to the cell-cell adhesion, adhesion to the extracellular matrix or the vascular endothelium and are thought to play important roles in the invasion and metastasis of the cancer. Integrins are known as extracellular matrix receptors. The change in the expression of integrins in the cancer cells has been reported. Recent information on the role of integrins in tumor progression and metastasis is reviewed here.
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PMID:[Integrins involved in tumor invasion and metastasis]. 763

A total of 22 surgical specimens, 16 astrocytomas with various malignancy, 3 brains adjacent to tumor and 3 brains with non-neoplastic lesion, was investigated immunohistochemically for the expression of thrombomodulin (TM). This membrane protein is localized on the vascular endothelium of nearly every human tissue and plays a crucial role in the maintenance of antithrombotic property of the endothelial cells. Although the normal cerebral vessels were negative for TM, the tumor vessels were positive for TM. The increased expression of TM was, however, demonstrated not only in glioblastomas but also in low-grade astrocytomas. Furthermore, the vessels in the brains adjacent to tumor and gliotic brains were also positive for TM. Those observations suggested that the tendency of intratumoral bleeding, which is rather characteristic of glioblastomas, is not simply explained by the altered expression of vascular endothelial TM. In two cases of glioblastoma, not only the blood vessels but also the tumor cells were positive. Considering the mitogenic activity of thrombin, a ligand for TM, the increased expression of TM might be related to the tumor neovascularization and also the tumor growth.
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PMID:Expression of thrombomodulin in astrocytomas of various malignancy and in gliotic and normal brains. 796 91

Epithelial ovarian cancer is an aggressive malignancy with a generally poor outcome. To improve survival, novel therapeutic strategies for this disease are needed and require elucidation of the biological events that underlie transformation and tumor growth. Vascular permeability factor (VPF), also known as vascular endothelial growth factor, is a homodimeric glycoprotein that acts on vascular endothelium as a potent permeability-inducing agent and mitogen. The present study demonstrates for the first time the constitutive gene expression of VPF in normal and neoplastic human ovaries. Abundant levels of VPF have been identified by an immunoassay in the ascites of patients with epithelial ovarian cancer (K-T. Yeo et al., Cancer Res., 53: 2912-2918, 1993). We have identified the malignant epithelium as one source of VPF in the ascites. Reverse transcription-polymerase chain reaction has demonstrated the expression of the two secreted isoforms, VPF121 and VPF165, in normal and neoplastic ovaries. Western blotting and an endothelial cell proliferation assay confirmed secretion of a biologically active product. VPF may be an important mediator of ascites formation and tumor metastasis observed in neoplastic conditions of the ovary.
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PMID:Vascular permeability factor gene expression in normal and neoplastic human ovaries. 826 52

The therapy of solid tumors with conventional chemotherapeutics, drug delivery preparations and immunomodulatory agents directed against the tumor cells is corrupted by a major barrier presented by the tumor vasculature. Permeability of the tumor blood vessels for transport of small molecules and macromolecular drug-carrier conjugates is only sufficient in the blood vessels at the tumor-host interface. Downregulation of the expression of adhesion molecules, required for the facilitation of immune cell recruitment, by the tumor vascular endothelium results in an escape of the tumor from host defence. New therapeutic approaches for the treatment of solid tumors are aimed at the tumor vasculature, either at the endothelial cells themselves or at basement membrane or tumor stroma components. Angiogenesis can be directly blocked with angiogenesis inhibitors, while angiogenesis related factors can serve as tumor vasculature specific epitopes for drug delivery strategies. Some glycoproteins expressed by tumor endothelial cells or present in the basement membrane and tumor stroma are also potential tumor selective targets. Therapeutic modalities that are suitable for site specific delivery are agents that increase tumor accumulation of (targeted) chemo/radiotherapeutics through increasing tumor vascular permeability. The observation that for tumor growth the blood supply is a limiting factor, led to the development of strategies to inhibit angiogenesis or block the tumor blood flow. Manipulation of the expression of endothelial cell adhesion molecules by selectively delivering modulatory agents at or in the tumor vascular endothelial cells may induce (bispecific antibody mediated) host defense activity directed against the tumor cells.
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PMID:Tumor vascular endothelium: barrier or target in tumor directed drug delivery and immunotherapy. 903 14

Tumor-derived vascular endothelial growth factor (VEGF)/ vascular permeability factor (VPF) plays an important role in neovascularization and the development of tumor stroma. Furthermore, VEGF receptors are over-expressed in the endothelial cells of tumor vasculature and almost non-detectable in the vascular endothelium of adjoining normal tissues. The differential expression of receptor offers a selective advantage for targeting cytotoxic toxin polypeptides. We have prepared a vascular targeting reagent by chemically linking recombinant VEGF to a truncated form of diphtheria toxin. The VEGF-toxin conjugate was selectively toxic to endothelial cell lines and inhibited experimental neovascularization of the chick chorioallantoic membrane. In the present study, we examined the effects of VEGF-toxin conjugate on solid tumor growth. Athymic nude mice with established subcutaneous tumors were treated with daily intraperitoneal injections of the VEGF-toxin conjugate or free toxin. When compared with control animals treated with the toxin polypeptide alone, the conjugate-treated animals displayed a significant inhibition of tumor growth. Histological analysis of tumors from conjugate-treated animals revealed hemorrhagic necrosis consistent with a vascular-mediated injury. In contrast, highly vascularized normal tissues from conjugate-treated animals demonstrated no evidence of hemorrhage or tissue injury. The conjugate was well tolerated without apparent toxicities. Our results illustrate the anti-tumor activity of a VEGF-toxin conjugate selectively targeting the tumor neovasculature.
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PMID:Targeting the tumor vasculature: inhibition of tumor growth by a vascular endothelial growth factor-toxin conjugate. 939 67

The ability of a tumor cell to survive is critical for successful dissemination to sites distant from the primary tumor. Tumor cells must enter blood circulation, resist hemodynamic shear stress of the blood circulation, successfully extravasate, and then migrate through dense tissue stroma to a site favorable for tumor growth. Some tumor cells must therefore be endowed with peculiar abilities to successfully metastasize, whereas others, although capable of forming tumor in specific organs, cannot metastasize. This property has often been associated with the homing ability of a given tumor cell, likely through the expression of organ-specific homing receptors that are critical for the extravasation process. The present work was aimed at establishing the point at which metastatic and nonmetastatic lymphoma cells diverge. Although 164T2 and 267T2 lymphoma cell lines can successfully form thymic lymphoma when injected intrathymically, only the 164T2 clone can efficiently form tumor in kidneys, spleen, and liver after intravenous inoculation. Using the indium-labeling technique to monitor the homing kinetic of both cell lines, we showed that the critical step for the successful metastasis of the lymphoma cell was determined in the final steps of the disseminating process, namely after homing. These results indicate that, whereas binding of tumor cells to vascular endothelium through specific adhesion mechanisms is a prerequisite for dissemination of tumor cells, the resistance of a tumor cell to the antagonist action of the host and/or its ability to grow tumor occurs only after homing to the target organ.
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PMID:The metastatic characteristics of murine lymphoma cell lines in vivo are manifested after target organ invasion. 942 18

We demonstrated previously that selective thrombosis of the blood vessels of solid tumors in mice can be achieved by targeting the extracellular domain of tissue factor by means of an antibody to an experimentally induced marker on tumor vascular endothelium. In the present study, we extend this finding to a naturally occurring marker of tumor vascular endothelium, vascular cell adhesion molecule-1 (VCAM-1). VCAM-1 is expressed by vascular endothelial cells in Hodgkin's disease and various solid tumors in mice and humans. It is absent from vascular endothelial cells in normal tissues in mice, with the exception of the heart and lungs, where it is present on venules. A monoclonal antibody to murine VCAM-1 was covalently linked to the extracellular domain of human tissue factor to create a "coaguligand." After i.v. administration to severe combined immunodeficient mice bearing human Hodgkin's tumors, the coaguligand localized selectively to VCAM-1-expressing vessels, caused thrombosis of those vessels, and retarded tumor growth. The coaguligand also localized to VCAM-1-expressing vessels in the heart and lungs of the mice but did not induce thrombosis in these sites. An immunohistochemical evaluation of the distribution of a monoclonal anti-phosphatidylserine (PS) antibody in the mice showed that the VCAM-1-expressing vessels in the tumor expressed PS, whereas the VCAM-1-expressing vessels in the heart and lungs lacked PS. The lack of thrombotic effect of the coaguligand on heart and lung vessels may be because PS is needed to provide the procoagulant surface upon which coagulation complexes can assemble. The requirement for coincident expression of the targeted marker and PS on tumor endothelium probably contributes to the selectivity of thrombotic action and the safety of coaguligands.
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PMID:Infarction of solid Hodgkin's tumors in mice by antibody-directed targeting of tissue factor to tumor vasculature. 978 17

In the present study, we developed an antitumor immunoconjugate that appears to be promising as a novel curative antitumor agent against a variety of human solid tumors. We generated a new antihuman endoglin (EDG) monoclonal antibody (mAb) K4-2C10 (or termed SN6f) that cross-reacts with mouse endothelial cells. Such cross-reactive anti-EDG mAbs have not been reported previously. This mAb was used to target tumor-associated vasculature in SCID mice inoculated with human tumors. No anti-EDG mAb or its immunoconjugates have previously been successfully used for targeting vasculature in vivo. In this study, MCF-7 human breast cancer cells were inoculated s.c. into SCID mice. K4-2C10 did not react with the MCF-7 cells but showed a weak reactivity with mouse endothelial cells. The mAb reacted with the proliferating endothelial cells more strongly than with the quiescent endothelial cells. The mAb exhibited much stronger reactivity (>10-fold) with human endothelial cells than with mouse endothelial cells and reacted strongly with vascular endothelium of tumor-associated blood vessels in a variety of human malignant tissues. Conjugates of K4-2C10 with ricin A chain (RA) and deglycosylated ricin A chain (dgRA) showed a weak but specific cytotoxic activity against murine endothelial cells in vitro; the 50% inhibitory dose of the RA and dgRA conjugates was 54 nm and 29 nm, respectively. Remarkable antitumor efficacy was observed when a small amount (a total of 60 microgram corresponding to 24% of the LD50 dose) of the dgRA conjugate was administered i.v. into SCID mice that had been inoculated s.c. with MCF-7. Unconjugated mAb K4-2C10 was not significantly effective in the inhibition of the tumor growth. The immunotoxin (IT) completely inhibited growth of the tumor in all of the treated mice (n = 8). Furthermore, similar antitumor efficacy was observed when the IT was administered i.v. into the tumor-inoculated SCID mice that had been pretreated with unconjugated K4-2C10 to block the potentially available weak binding sites of normal tissues. The strong therapeutic effects of the IT were reproduced in another set of therapeutic experiments. No significant side effects were observed in the mice. The differences in the tumor growth between the control group and the IT-treated groups were statistically significant. The IT showed antiangiogenic activity in the dorsal air sac method. The results indicate that K4-2C10 IT effectively treated the tumor-bearing mice by selectively inhibiting the tumor-associated blood vessels and by disrupting tumor-associated angiogenesis. The strong antitumor efficacy of the K4-2C10 IT is remarkable in view of the fact that K4-2C10 and its IT showed only a weak reactivity with mouse endothelial cells, and a relatively small amount of the IT was administered i.v. to treat s.c. tumors. We anticipate that the K4-2C10 IT will show much stronger antitumor efficacy and antiangiogenic activity in patients with solid tumors and other angiogenesis-associated diseases. The present results demonstrate for the first time that an anti-EDG mAb or its immunoconjugate can effectively target tumor-associated vasculature in vivo.
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PMID:Long-lasting complete inhibition of human solid tumors in SCID mice by targeting endothelial cells of tumor vasculature with antihuman endoglin immunotoxin. 981 81


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