Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0677930 (primary tumor)
 20,210 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The insulin receptor substrate (IRS) proteins are cytoplasmic adaptors that organize signaling complexes downstream of activated cell surface receptors. Here, we show that IRS-1 and IRS-2, despite significant homology, play critical yet distinct functions in breast cancer, and we identify specific signaling pathways that are influenced by IRS-1 using the polyoma virus middle-T (PyV-MT) transgenic mouse model of mammary carcinoma and Irs-1 null (Irs1(-/-)) mice. The absence of Irs-1 expression enhanced metastatic spread significantly without a significant effect on primary tumor growth. Orthotopic transplant studies revealed that the increased metastatic potential of Irs1-deficient tumor cells is cell autonomous. Mammary tumors that developed in PyV-MT::Irs1(-/-) mice exhibited elevated Irs-2 function and enhanced phosphatidylinositol 3-kinase/Akt/mTor activity, suggesting that one mechanism by which Irs-1 impedes metastasis is to suppress Irs-2-dependent signaling. In support of this mechanism, reduction of Irs-2 expression in Irs1(-/-) tumor cells restored mTor signaling to wild-type levels. PyV-MT::Irs1(-/-) tumors also exhibited a significant increase in vascular endothelial growth factor expression and microvessel density, which could facilitate their dissemination. The significance of our findings for human breast cancer is heightened by our observation that Irs-1 is inactivated in wild-type, metastatic mammary tumors by serine phosphorylation. Collectively, our findings reveal that inactivation of IRS-1 enhances breast cancer metastasis and support the novel hypothesis that IRS-1 has metastasis suppressor functions for breast cancer.
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PMID:Suppression of insulin receptor substrate 1 (IRS-1) promotes mammary tumor metastasis. 1703 Jun 5

Bevacizumab, a monoclonal antibody to vascular endothelial growth factor, was approved in 2004 for use in combination with intravenous 5-fluorouracil-based chemotherapy for the treatment of metastatic colorectal cancer. Bevacizumab is the first approved agent that targets tumor angiogenesis. The pivotal phase III trial showed significantly greater overall and progression-free survival with the addition of bevacizumab to irinotecan, 5-fluorouracil, and leucovorin. These outcomes were observed irrespective of patients' pretreatment characteristics (age >/=65 years, >/=1 site of metastasis, or location of primary tumor). Furthermore, there was a significant survival benefit regardless of pretreatment biomarkers, including plasma vascular endothelial growth factor level, tumor thrombospondin and p53 expression, and mutational status in k-ras, b-raf, and p53. Analysis of data in responders and nonresponders showed a response-independent survival benefit, indicating that even those in whom there was not an objective tumor response by standard criteria benefited from the addition of bevacizumab. Preliminary data on the addition of bevacizumab to oxaliplatin- and capecitabine-based regimens for the first-line treatment of metastatic colorectal cancer show that these regimens are well tolerated, with consistent increases in objective response rates, time to progression, and overall survival. The survival advantages in patients with metastatic colorectal cancer with the addition of bevacizumab to chemotherapy support the use of this agent in first-line treatment.
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PMID:Bevacizumab in combination with chemotherapy: first-line treatment of patients with metastatic colorectal cancer. 1714 25

We investigated the expression of CXC chemokine receptor 4 (CXCR4), vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP)-9 to elucidate whether these markers could predict lymph node metastasis in human breast cancer. Higher rates of CXCR4 (61%), VEGF (68%), and MMP-9 (63%) expression were found in breast cancer tissues than in normal and atypical hyperplasia tissues. The expression of these markers was significantly associated with primary tumor progression, histological grade, and lymph node status. We found there were significant correlations between the expressions of any two of the three markers (P<0.001). Furthermore, our studies indicated that concomitant expression of CXCR4/VEGF (P=0.007), CXCR4/MMP-9 (P<0.001) or VEGF/MMP-9 (P=0.003) had stronger correlation with lymph node metastasis than did each alone and that combined expression of all three makers strongly correlated with lymph node metastasis (P<0.001). Thus, simultaneously examining the expression of CXCR4, VEGF, and MMP-9 in cancer tissues of breast cancer will provide valuable prognostic diagnosis of lymph node metastasis.
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PMID:Recombination of CXCR4, VEGF, and MMP-9 predicting lymph node metastasis in human breast cancer. 1730 24

Bevacizumab is the first U.S. Food and Drug Association-approved vascular endothelial growth factor-targeted agent that greatly increases progression-free and overall survival in combination with standard chemotherapy regimens in patients with metastatic colorectal cancer. Although bevacizumab is generally well tolerated, some serious adverse events have occurred in some patients in clinical trials, including arterial thromboembolism and gastrointestinal (GI) perforation. GI perforation was first observed in the pivotal phase 3 trial, in which six events occurred in bevacizumab group (1.5%), compared with no events in the control group. Since then, similar rates of GI perforation have been observed in other large trials. Typical presentation was abdominal pain associated with constipation and vomiting. Such events occurred throughout treatment and were not correlated with duration of exposure. No difference in rate of GI perforations was found in patients who did and did not have a baseline history of peptic ulcer disease, diverticulosis, and history of chronic use of nonsteroidal anti-inflammatory drugs. However, the incidence of GI perforation seemed to be higher in patients with primary tumor intact, recent history of sigmoidoscopy or colonoscopy, or previous adjuvant radiotherapy, but it is necessary to confirm these preliminary findings by multivariate analyses. The mechanism responsible for causing GI perforation is not known and may be multifactorial. Bevacizumab should be permanently discontinued in patients who develop GI perforation. This article reviews the incidence, presentation, pathogenesis, risk factors, and management of GI perforation in patients with colorectal cancer who are treated with bevacizumab.
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PMID:Gastrointestinal perforation due to bevacizumab in colorectal cancer. 1735 52

Sunitinib (SU-11248, Sutent) inhibits at least eight receptor protein-tyrosine kinases including vascular endothelial growth factor receptors 1-3 (VEGFR1-VEGFR3), platelet-derived growth factor receptors (PDGFRalpha and PDGFRbeta), stem cell factor receptor (Kit), Flt-3, and colony-stimulating factor-1 receptor (CSF-1R). VEGFR1 and VEGFR2 play key roles in vasculogenesis and angiogenesis. PDGFRbeta, which is found in pericytes that surround capillary endothelial cells, plays a pivotal role in stabilizing the vascular endothelium. Sunitinib inhibits angiogenesis by diminishing signaling through VEGFR1, VEGFR2, and PDGFRbeta. Renal cell cancers that have metastasized, or spread from the primary tumor, exhibit extensive vascularity, and sunitinib is approved for the treatment of these neoplasms. Activating Kit mutations occur in about 85% of gastrointestinal stromal tumors and activating PDGFRalpha mutations occur in about 5% of these tumors. Sunitinib is approved for the treatment of those tumors that are resistant to imatinib (STI-571, Gleevec), another Kit and PDGFRalpha protein-tyrosine kinase inhibitor. Both sunitinib and imatinib bind reversibly to the ATP binding site of their target kinases and thereby inhibit their catalytic activity.
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PMID:Sunitinib: a VEGF and PDGF receptor protein kinase and angiogenesis inhibitor. 1736 63

Intratumoral hypoxia is an independent indicator of poor patient outcome and increasing evidence supports a role for hypoxia in the development of metastatic disease. Studies suggest that the acquisition of the metastatic phenotype is not simply the result of dysregulated signal transduction pathways, but instead is achieved through a stepwise selection process driven by hypoxia. Hypoxia facilitates disruption of tissue integrity through repression of E-cadherin expression, with concomitant gain of N-cadherin expression which allows cells to escape anoikis. Through upregulation of urokinase-type plasminogen activator receptor (uPAR) expression, hypoxia enhances proteolytic activity at the invasive front and alters the interactions between integrins and components of the extracellular matrix, thereby enabling cellular invasion through the basement membrane and the underlying stroma. Cell motility is increased through hypoxia-induced hepatocyte growth factor (HGF)-MET receptor signaling, resulting in cell migration towards the blood or lymphatic microcirculation. Hypoxia-induced vascular endothelial growth factor (VEGF) activity also plays a critical role in the dynamic tumor-stromal interactions required for the subsequent stages of metastasis. VEGF promotes angiogenesis and lymphangiogenesis in the primary tumor, providing the necessary routes for dissemination. VEGF-induced changes in vascular integrity and permeability promote both intravasation and extravasation, while VEGF-induced angiogenesis in the secondary tissue is essential for cell proliferation and establishment of metastatic lesions. Through regulation of these critical molecular targets, hypoxia promotes each step of the metastatic cascade and selects tumor cell populations that are able to escape the unfavorable microenvironment of the primary tumor.
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PMID:Hypoxia-driven selection of the metastatic phenotype. 1745 7

Disruption of pathways leading to programmed cell death plays a major role in most malignancies, including multiple myeloma (MM). ABT-737 is a BH3 mimetic small-molecule inhibitor that binds with high affinity to Bcl-2 and Bcl-xL, preventing the sequestration of proapoptotic molecules and shifting the cell survival/apoptosis balance toward apoptosis induction. In this study, we show that ABT-737 is cytotoxic to MM cell lines, including those resistant to conventional therapies, and primary tumor cells. Flow cytometric analysis of intracellular levels of Bcl-2 family proteins demonstrates a clear inversion of the Bax/Bcl-2 ratio leading to induction of apoptosis. Activation of the mitochondrial apoptosis pathway was indicated by mitochondrial membrane depolarization and caspase cleavage. Additionally, several signaling pathways known to be important for MM cell survival are disrupted following treatment with ABT-737. The impact of ABT-737 on survival could not be overcome by the addition of interleukin-6, vascular endothelial growth factor or insulin-like growth factor, suggesting that ABT-737 may be effective in preventing the growth and survival signals provided by the microenvironment. These data indicate that therapies targeting apoptotic pathways may be effective in MM treatment and warrant clinical evaluation of ABT-737 and similar drugs alone or in combination with other agents in the setting of MM.
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PMID:ABT-737, an inhibitor of Bcl-2 family proteins, is a potent inducer of apoptosis in multiple myeloma cells. 1746 Jul

The effects of antiangiogenic therapy on tumors relapsing after irradiation are not known. To this end, we irradiated human tumors growing s.c. in nude mice with a single dose of 20 or 30 Gy. Compared with primary (treatment-naive) xenografts, the growth rate of recurrent tumors was 1.6-fold slower, which is consistent with the known "tumor bed effect." For similar size tumors, recurrences had fewer functional vessels, a reduced vessel coverage by perivascular cells, and were more necrotic. Placenta growth factor concentration was significantly lower in relapses, whereas vascular endothelial growth factor (VEGF) levels were similar between primary and recurrent tumors. On the other hand, fibrillar collagen deposition was significantly increased in recurrent tumors. This radiation-induced fibrosis was partially responsible for the slower growth of recurrences; the i.t. injection of collagenase increased the growth rate of tumor relapses without affecting primary tumor growth. The mouse-specific VEGF receptor 2-blocking antibody DC101 induced a 2.2-fold longer growth delay in recurrent tumors compared with treatment-naive tumors. DC101 significantly decreased the interstitial fluid pressure and did not change the functional vessel density and perivascular cell coverage in both tumor variants. Interestingly, DC101 induced a rapid (2 days after treatment initiation) and significant decrease in tumor cell proliferation in recurrent but not in primary tumors. Thus, our results show that the stromal compartment and the response to antiangionenic therapy of primary and in-field recurrent tumors are significantly different. Our findings suggest that antiangiogenic agents could be effective in the treatment of patients with relapses after radiotherapy.
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PMID:Human tumor xenografts recurring after radiotherapy are more sensitive to anti-vascular endothelial growth factor receptor-2 treatment than treatment-naive tumors. 1754 83

The tumor microenvironment is known to have a profound effect on tumor progression in a highly context-specific manner. We have investigated whether peritoneal inflammation plays a causative role in ovarian tumor metastasis, a poorly understood process. Implantation of human ovarian tumor cells into the ovaries of severe combined immunodeficient mice resulted in peritoneal inflammation that corresponds temporally with tumor cell dissemination from the ovaries. Enhancement of the inflammatory response with thioglycolate accelerated the development of ascites and metastases. Suppression of inflammation with acetyl salicylic acid delayed ascites development and reduced tumor implant formation. A similar prometastatic effect for inflammation was observed when tumor cells were injected directly into the peritoneum of severe combined immunodeficient mice, and in a syngeneic immunocompetent mouse model. Inflammation-modulating treatments did not affect primary tumor development or in vitro tumor cell growth. Depletion of peritoneal macrophages, but not neutrophils or natural killer cells, reduced tumor progression, as assessed by ascites formation and peritoneal metastasis. We conclude that inflammation facilitates ovarian tumor metastasis by a mechanism largely mediated by macrophages, and which may involve stromal vascular endothelial growth factor production. The confirmation of these findings in immunocompetent mice suggests relevance to human disease. Identifying the mechanisms by which macrophages contribute to tumor metastasis may facilitate the development of new therapies specifically targeting immune cell products in the tumor microenvironment.
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PMID:Macrophages mediate inflammation-enhanced metastasis of ovarian tumors in mice. 1757 37

Brain metastasis is a critical complication of small-cell lung cancer (SCLC), resulting in rare long-time survival. We report a case of a 72-year-old man who displayed a very unique clinical appearance, with a large metastatic brain tumor that grew much faster than primary SCLC. The brain tumor expressed high levels of vascular endothelial growth factor (VEGF) that was negative in primary lung tumor. The patient, who underwent brain surgery and chemotherapy against SCLC, has survived for > 2 years with a good performance status since initial brain symptoms occurred. Weak expression of VEGF in primary tumor might be associated with good prognosis. However, VEGF upregulation could occur after metastasis, resulting in aggressive tumor growth.
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PMID:Metastatic brain mass caused by slow-growing small-cell lung cancer: differential vascular endothelial growth factor expression in primary and metastatic tumor. 1768 Oct 98


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