Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0027627 (metastases)
103,950 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Aberrant cell survival and resistance to apoptosis are hallmarks of tumor invasion and progression to metastatic disease, but the mechanisms involved are poorly understood. The epithelial-mesenchymal transition (EMT), a process that facilitates progression to invasive cancer, provides a superb model for studying such survival mechanisms. Here, we used a unique spheroid culture system that recapitulates the structure of the colonic epithelium and undergoes an EMT in response to cytokine stimulation to study this problem. Our data reveal that the EMT results in the increased expression of both VEGF and Flt-1, a tyrosine kinase VEGF receptor, and that the survival of these cells depends on a VEGF/Flt-1 autocrine pathway. Perturbation of Flt-1 function by either a blocking antibody or adenoviral expression of soluble Flt-1, which acts in a dominant-negative fashion, caused massive apoptosis only in cells that underwent EMT. This pathway was critical for the survival of other invasive colon carcinoma cell lines, and we observed a correlative upregulation of Flt-1 expression linked to in vivo human cancer progression. A role for Flt-1 in cell survival is unprecedented and has significant implications for Flt-1 function in tumor progression, as well as in other biological processes, including angiogenesis and development.
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PMID:Flt-1-dependent survival characterizes the epithelial-mesenchymal transition of colonic organoids. 1452 39

Angiogenesis is necessary for the growth of primary tumors and the formation of metastases. It is well known that vascular endothelial growth factor (VEGF) and its receptors play a major role in this process. To date, the formation of bone metastases has been poorly understood. Tumor cells must interact with the microenvironment of the bone and new blood vessels must spread. The ET/ET(A) (endothelin) receptor system seems to play an important role in this process. Specimens from metastatic bone lesions and non-malignant bone tissue were analyzed by histological and immunohistochemical staining. Sections were stained with antibodies against CD31, Flt-1, KDR, endothelin-1 (ET-1) and endothelin receptor A (ET(A)). Our studies show that there is an increased microvessel density (MVD) in metastatic bone lesions from different primary tumors in contrast to normal bone tissue. In nearly all tumor formations of the bone, ET-1 and its receptor ET(A) was found by immunohistochemistry. We also performed immunohistochemical staining for the VEGF-receptors Flt-1 and KDR. In conclusion, there is an increased vessel density in metastatic bone lesions in contrast to normal bone tissue. The ET/ET(A) system can be detected in nearly all bone specimens and is upregulated in metastatic bone lesions in contrast to healthy bone tissue.
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PMID:Angiogenesis and the ET-1/ETA receptor system: immunohistochemical expression analysis in bone metastases from patients with different primary tumors. 1504 98

The number of effective cytotoxic agents for the treatment of patients with metastatic adult soft tissue sarcoma is limited, especially when patients have failed anthracycline- and ifosfamide-based chemotherapy. For the subgroup of patients with inoperable gastrointestinal stromal tumour (GIST), progress has been made via the rapid development and approval of the targeted therapy imatinib. Small round cell tumours (SRCTs), such as Ewing's sarcoma/primitive neuroectodermal tumour, desmoplastic SRCT and rhabdomyosarcoma, are chemotherapy-sensitive and potentially curable malignancies, which are treated with multimodality, dose-intensive, neoadjuvant protocols regardless of size or overt metastatic disease. Most other high-grade (grading >I), so-called 'adult type', soft tissue sarcomas such as fibrosarcoma, liposarcoma, pleomorphic and synovial sarcomas are treated with an anthracycline-based regimen with or without ifosfamide as front-line therapy. In relapsed 'adult type' soft tissue sarcomas, trofosfamide, gemcitabine and trabectedin (ecteinascidin 743) appear to be drugs associated with some activity and an acceptable toxicity profile. A high activity has been reported for the taxanes, in particular for paclitaxel, in vascular sarcomas located in the scalp or face and in Kaposi's sarcoma. It is interesting to note that the different drugs have particular effects in distinct subtypes of soft tissue sarcoma; however, it should be taken into account that the number of patients included in the phase II trials is limited. The role of the newer agents (e.g. epothilones, brostallicin) is currently undefinable. Targeted therapy inhibiting vascular endothelial growth factor receptor, epidermal growth factor receptor, RAF kinase, c-KIT or platelet-derived growth factor receptors will continue to be tested in GIST patients refractory to imatinib and in other sarcoma histologies.
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PMID:Recent developments in salvage chemotherapy for patients with metastatic soft tissue sarcoma. 1563 40

Vascular endothelial growth factor (VEGF) is a proangiogenic cytokine that is expressed highly in many solid tumours often correlating with a poor prognosis. In this study, we investigated the expression of VEGF and its receptors in bone metastases from primary human breast tumours and further characterised its effects on osteoclasts in vitro. Breast cancer metastases to bone were immunohistochemically stained for VEGF, its receptors VEGFR1 and 2 (vascular endothelial growth factor receptor 1 and 2), demonstrating that breast cancer metastases express VEGF strongly and that surrounding osteoclasts express both VEGFR1 and VEGFR2. RAW 264.7 cells (mouse monocyte cell line) and human peripheral blood mononuclear cells (PBMCs) were cultured with VEGF, RANKL and M-CSF. VEGF and RANKL together induced differentiation of multinucleated, tartrate-resistant acid phophatase (TRAP)-positive cells in similar numbers to M-CSF and RANKL. The PBMCs were also able to significantly stimulate resorption of mineralised matrix after treatment with M-CSF with RANKL and VEGF with RANKL. We have shown that VEGF in the presence of RANKL supports PBMC differentiation into osteoclast-like cells, able to resorb substrate. Vascular endothelial growth factor may therefore play a role in physiological bone resorption and in pathological situations. Consequently, VEGF signalling may be a therapeutic target for osteoclast inhibition in conditions such as tumour osteolysis.
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PMID:Vascular endothelial growth factor acts as an osteolytic factor in breast cancer metastases to bone. 1581 59

During embryonic development, epithelial cells must escape the structural constraints imposed by tissue architecture and adopt a phenotype more amenable to cell movement, a process known as the epithelial-mesenchymal transition (EMT). The progression of carcinomas to invasive and metastatic disease may also involve localized occurrences of EMT. However, data that support the actual occurrence of EMT in specific carcinomas and the relevance of this process to the progression of these tumors had been scant. This review highlights recent studies that substantiate the importance of the EMT to colorectal carcinoma. Specifically, a novel model for studying the EMT of colorectal carcinoma has been used to gain insight into the nature of the EMT itself and to identify molecular events that contribute to disease progression. Although loss of E-cadherin function is a primal event for the EMT, the expression of specific integrins such as alpha(v)beta6 as a consequence of the EMT enables invasive cells to interact with interstitial matrices and to sustain activation of TGF-beta. Of note, alpha(v)beta6 expression in tumors is a marker of cells that have undergone an EMT and it is prognostic for tumors that will progress more rapidly to terminal disease. The EMT also induces autocrine signaling involving VEGF and Flt-1 that enable invasive cells to become 'self-sufficient' for survival. Thus, the EMT appears to be an integral component of colorectal cancer progression and its analysis can yield novel targets for prognosis and therapy.
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PMID:The epithelial-mesenchymal transition (EMT) and colorectal cancer progression. 1584 61

Some markers of angiogenic endothelial cells are emerging as targets of cancer therapy. The present study compares the expression of CD105 with that of other endothelial markers in all tissue layers during the development of colon cancer. We immunohistochemically analyzed the expression of the colon adenoma-carcinoma sequence by endothelial cells using a panel of eight endothelial markers. We examined sections from endoscopic mucosal resection and surgical resection of tubular adenoma (n=31), carcinoma in adenoma (n=11), and adenocarcinoma (n=34). Cylindrical cores were punched out from donor paraffin blocks of normal mucosa adjacent to tumors, from tumor lesions of mucosa, submucosa, muscularis propria, subserosa, and serosa, and from lymph node metastases. CD31 (PECAM-1) was universally expressed in the blood vessels of adenoma-carcinoma lesions as well as in normal mucosal vessels (80-95%), with no significant differences. In contrast, cancer-associated blood vessels (up to 80%) and cancer cells themselves expressed high levels of CD105. In normal mucosa, CD105 was weakly expressed in endothelial cells of capillaries (< or =21%), and significant differences in its expression in endothelial cells between the normal mucosa and adenoma, carcinoma in adenoma, and adenocarcinoma were found. Flt-1, Flk-1, transforming growth factor-beta1, transforming growth factor-beta receptor II, and CD44 were strongly expressed in the cancer cells but were not expressed in the blood vessels. Vascular endothelial growth factor was expressed at <30% in the blood vessels of adenoma, carcinoma in adenoma, and carcinoma. Moreover, this study provided evidence that CD105 was expressed exclusively in endothelial blood vessels by double immunostaining of CD105 and D2-40. The present study shows that de novo blood vessels of colon cancer specifically express CD105. These findings provide the basis for novel antiangiogenic cancer therapies.
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PMID:Endoglin (CD105) expression in angiogenesis of colon cancer: analysis using tissue microarrays and comparison with other endothelial markers. 1617 81

Angiogenesis is essential for solid tumor growth. Although successful antiangiogenic therapies have been demonstrated in animal models, a systematic comparison of the efficacy of different antiangiogenic factors has not been described in the hepatic environment. To address this issue, CT26 murine colon carcinoma cells were transfected with retroviral vectors encoding murine endostatin (mEndostatin), human angiostatin (hAngiostatin), murine-soluble vascular endothelial growth factor receptor-2, (msFlk-1), or murine-soluble Tie2 (msTie2). The transfected cells were then subjected to another round of transfection with a luciferase cDNA-encoding retroviral vector. Expression of these putative antiangiogenic proteins inhibited the proliferation of human umbilical vein endothelial cells in vitro but not tumor cells. To examine effects on tumor growth in vivo, modified cells were delivered via intrasplenic injection into BALB/c mice to induce liver metastases. Tumor burden was measured weekly by bioluminescence. Growth of hepatic metastases in vivo was significantly reduced in mice that were administered cells expressing msTie2 (76% reduction compared with control cells 21 days after intrasplenic inoculation; P < 0.05). Similar results were observed with cells that expressed msFlk-1 and hAngiostatin. However, expression of mEndostatin had no significant effect on the growth of liver metastases compared with control animals. These findings indicate that multiple antiangiogenic pathways are necessary for the growth of hepatic metastases, and each of these pathways is a potential clinically relevant antiangiogenic target for the treatment of this disease.
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PMID:A comparison of antiangiogenic therapies for the prevention of liver metastases. 1624 20

Dissemination to draining lymph nodes is a frequent first step in prostate cancer metastasis. Although tumors metastasize to lymph nodes via the lymphatics, the importance of lymphangiogenesis in mediating the process remains controversial. Here, we inhibit intratumoral lymphangiogenesis in s.c. and surgical orthotopic implantation mouse models of human prostate cancer using several strategies. Stable expression of small interfering RNAs (siRNA) targeted against human vascular endothelial growth factor-C (VEGF-C) in PC-3 cells reduced intratumoral lymphatics by 99% in s.c. tumors, indicating that tumor-secreted VEGF-C is necessary for lymphangiogenesis. Expression of siRNAs against human VEGF-A somewhat reduced tumor lymphangiogenesis. Secretion of a soluble VEGF receptor-3/Flt4 fusion protein by PC-3 cells reduced intratumoral lymphatics by 100% in s.c. tumors. Combination of soluble Flt4 and VEGF-C siRNA yielded >92% reduction of intratumoral lymphatics in orthotopic prostate tumors. However, metastasis to lymph nodes was not significantly affected regardless of intratumoral lymphatic vessel density. The abundance of marginal lymphatics at the tumor-stromal interface was unchanged in orthotopic tumors whose intratumoral lymphatics were inhibited, suggesting that these marginal vessels could be sufficient for lymph node metastasis. Hematogenous metastasis (blood tumor burden, lung metastasis) correlated with degree of lymph node invasion. We also analyzed the lymphatics in spontaneous transgenic adenocarcinomas of the mouse prostate which metastasize to lymph nodes. Progression from well-differentiated prostate intraepithelial neoplasia to metastatic, undifferentiated adenocarcinoma was accompanied by loss of lymphatics. These results suggest that tumor-secreted VEGF-C and, to a lesser extent, VEGF-A, are important for inducing prostate cancer intratumoral lymphangiogenesis but are unnecessary for lymph node metastasis.
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PMID:Tumor-secreted vascular endothelial growth factor-C is necessary for prostate cancer lymphangiogenesis, but lymphangiogenesis is unnecessary for lymph node metastasis. 1626

Prostate cancer frequently metastasizes to bone resulting in the formation of osteoblastic metastases through unknown mechanisms. Vascular endothelial growth factor (VEGF) has been shown recently to promote osteoblast activity. Accordingly, we tested if VEGF contributes to the ability of prostate cancer to induce osteoblast activity. PC-3, LNCaP, and C4-2B prostate cancer cell lines expressed both VEGF-165 and VEGF-189 mRNA isoforms and VEGF protein. Prostate cancer cells expressed the mRNA for VEGF receptor (VEGFR) neuropilin-1 but not the VEGFRs Flt-1 or KDR. In contrast, mouse pre-osteoblastic cells (MC3T3-E1) expressed Flt-1 and neuropilin-1 mRNA but not KDR. PTK787, a VEGFR tyrosine kinase inhibitor, inhibited the proliferation of human microvascular endothelial cells but not prostate cancer proliferation in vitro. C4-2B conditioned medium induced osteoblast differentiation as measured by production of alkaline phosphatase and osteocalcin and mineralization of MC3T3-E1. PTK787 blocked the C4-2B conditioned medium-induced osteoblastic activity. VEGF directly induced alkaline phosphatase and osteocalcin but not mineralization of MC3T3-E1. These results suggest that VEGF induces initial differentiation of osteoblasts but requires other factors, present in C4-2B, to induce mineralization. To determine if VEGF influences the ability of prostate cancer to develop osteoblastic lesions, we injected C4-2B cells into the tibia of mice and, after the tumors grew for 6 weeks, administered PTK787 for 4 weeks. PTK787 decreased both intratibial tumor burden and C4-2B-induced osteoblastic activity as measured by bone mineral density and serum osteocalcin. These results show that VEGF contributes to prostate cancer-induced osteoblastic activity in vivo.
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PMID:Vascular endothelial growth factor contributes to prostate cancer-mediated osteoblastic activity. 1632 39

The VEGF/VPF (vascular endothelial growth factor/vascular permeability factor) ligands and receptors are crucial regulators of vasculogenesis, angiogenesis, lymphangiogenesis and vascular permeability in vertebrates. VEGF-A, the prototype VEGF ligand, binds and activates two tyrosine kinase receptors: VEGFR1 (Flt-1) and VEGFR2 (KDR/Flk-1). VEGFR1, which occurs in transmembrane and soluble forms, negatively regulates vasculogenesis and angiogenesis during early embryogenesis, but it also acts as a positive regulator of angiogenesis and inflammatory responses, playing a role in several human diseases such as rheumatoid arthritis and cancer. The soluble VEGFR1 is overexpressed in placenta in preeclampsia patients. VEGFR2 has critical functions in physiological and pathological angiogenesis through distinct signal transduction pathways regulating proliferation and migration of endothelial cells. VEGFR3, a receptor for the lymphatic growth factors VEGF-C and VEGF-D, but not for VEGF-A, regulates vascular and lymphatic endothelial cell function during embryogenesis. Loss-of-function variants of VEGFR3 have been identified in lymphedema. Formation of tumor lymphatics may be stimulated by tumor-produced VEGF-C, allowing increased spread of tumor metastases through the lymphatics. Mapping the signaling system of these important receptors may provide the knowledge necessary to suppress specific signaling pathways in major human diseases.
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PMID:Signal transduction by VEGF receptors in regulation of angiogenesis and lymphangiogenesis. 1633 62


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