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  • American Association for Cancer Research (AACR)  (4)
  • 2000-2004  (4)
  • 1
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2004
    In:  Clinical Cancer Research Vol. 10, No. 12 ( 2004-06-15), p. 4029-4037
    In: Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 10, No. 12 ( 2004-06-15), p. 4029-4037
    Abstract: Squamous carcinomas of the head and neck (HNSCC) represent the sixth most common cancer among men worldwide and a major cause of morbidity and mortality due to its relatively poor prognosis. As part of ongoing studies addressing the molecular events underlying tumor progression in HNSCC, we have explored the nature of the proliferative pathways in which dysregulation may promote aberrant cell growth in this tumor type. The serine/threonine protein kinase Akt is a downstream target of phosphatidylinositol 3-kinase and a key regulator of normal and cancerous growth and cell fate decisions. Therefore, in this study, we have examined the status of activation of Akt in different stages of squamous cell carcinoma development in mice and in clinical samples from HNSCC patients. By immunohistochemical analysis, using a recently developed phosphorylation state-specific antibody, we demonstrated that Akt activation correlates closely with the progression of mouse skin squamous cell carcinoma. We also observed that activation of Akt is a frequent event in human HNSCC because active Akt can be detected in these tumors with a pattern of expression and localization correlating with the progression of the lesions. In line with these observations, Akt was constitutively activated in a large fraction of HNSCC-derived cell lines. We also provide evidence that the Akt signaling pathway may represent a biologically relevant target for a novel antineoplastic agent, UCN-01, which recently has been shown to be active in cellular and xenograft models for HNSCC at concentrations safely achievable in clinically relevant situations.
    Type of Medium: Online Resource
    ISSN: 1078-0432 , 1557-3265
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2004
    detail.hit.zdb_id: 1225457-5
    detail.hit.zdb_id: 2036787-9
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2004
    In:  Cancer Research Vol. 64, No. 15 ( 2004-08-01), p. 5212-5224
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 64, No. 15 ( 2004-08-01), p. 5212-5224
    Abstract: The semaphorins are a large family of secreted and cell surface proteins that provide attractive and repulsive cues for axon guidance during neuronal development. Semaphorins share a conserved NH2-terminal Sema domain with their receptors, the plexins, which mediate neuronal cell adhesion, axon guidance, and maintenance of established neuronal pathways in the adult. Both semaphorins and plexins share structural homology with the extracellular domain of c-Met, a member of the scatter factor family of receptors. However, the highly conserved cytoplasmic region of plexins has no homology with the c-Met tyrosine kinase or with any other known protein. Using a recently developed antibody and RNA analysis, we found that high levels of plexin-B1 are expressed in endothelial cells. Whereas c-Met, with which plexin-B1 can interact, is known to be a potent promoter of angiogenesis, the effects of semaphorin-mediated plexin activation in endothelial cells are still poorly understood. Here, we examined the role of plexin-B1 activation in angiogenesis using a purified, secreted form of its ligand, Semaphorin 4D (Sema4D). Sema4D potently induced chemotaxis and tubulogenesis in endothelial cells and enhanced blood vessel formation in an in vivo mouse model. Interestingly, responses to Sema4D did not require c-Met activation. Instead, the use of chimeric plexin-B1 receptors, Rho inhibitors, and lentiviral gene delivery of interfering molecules revealed that these proangiogenic effects are dependent on a COOH-terminal PDZ-binding motif of plexin-B1, which binds two guanine nucleotide exchange factors for the small GTPase Rho, PDZ-RhoGEF and LARG, and are mediated by the activation of Rho-initiated pathways.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2004
    detail.hit.zdb_id: 2036785-5
    detail.hit.zdb_id: 1432-1
    detail.hit.zdb_id: 410466-3
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2004
    In:  Cancer Research Vol. 64, No. 24 ( 2004-12-15), p. 8804-8807
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 64, No. 24 ( 2004-12-15), p. 8804-8807
    Abstract: Ras genes are the most frequently mutated oncogenes in human cancer. However, the contribution of ras to tumor initiation still is unclear because ras expression in primary cells can cause cell cycle arrest and even cell death by apoptosis. Furthermore, when expressed in the epidermis of mice, mutant ras promotes the formation of benign papillomas, only few of which will progress into carcinomas. However, in these cases, ras-transgene expression often is restricted to suprabasal or follicular epithelial cells that may lack self-renewal capacity. Thus, it still is conceivable that expression of active ras in other epithelial compartments may exert a distinct ability to promote malignant progression. To address this possibility, transgenic mice carrying the tetracycline-inducible system (tet-on receptor) targeted to the basal layer of stratified epithelium, which includes the epithelial stem cells, were engineered and crossed with mice expressing the K-rasG12D oncogene under the control of tet-regulated responsive elements. On doxycycline administration, proliferative lesions ranging from hyperplasias, papillomas, and dysplasias to metastatic carcinomas developed in squamous epithelia of the skin, oral mucosa, salivary glands, tongue, esophagus, forestomach, and uterine cervix within just 10 to 20 days. The most noticeable lesions were invasive squamous carcinomas of the skin and oral mucosa. These findings suggest that the expression of oncogenes in an epithelial compartment that includes the stem cells may be sufficient to promote squamous carcinogenesis. They also provide a molecularly defined conditional animal model system in which the mechanisms responsible for cancer initiation, maintenance, and metastatic spread can be readily investigated.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2004
    detail.hit.zdb_id: 2036785-5
    detail.hit.zdb_id: 1432-1
    detail.hit.zdb_id: 410466-3
    Location Call Number Limitation Availability
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  • 4
    In: Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 10, No. 15 ( 2004-08-01), p. 4944-4958
    Abstract: A number of genetic and epigenetic changes underlying the development of nasopharyngeal carcinomas have recently been identified. However, there is still limited information on the nature of the genes and gene products whose aberrant expression and activity promote the malignant conversion of nasopharyngeal epithelium. Here, we have performed a genome-wide transcriptome analysis by probing cDNA microarrays with fluorescent-labeled amplified RNA derived from laser capture microdissected cells procured from normal nasopharyngeal epithelium and areas of metaplasia-dysplasia and carcinoma from EBV-associated nasopharyngeal carcinomas. This approach enabled the identification of genes differentially expressed in each cell population, as well as numerous genes whose expression can help explain the aggressive clinical nature of this tumor type. For example, genes indicating cell cycle aberrations (cyclin D2, cyclin B1, activator of S-phase kinase, and the cell cycle checkpoint kinase, CHK1) and invasive-metastatic potential (matrix metalloproteinase 11, v-Ral, and integrin β4) were highly expressed in tumor cells. In contrast, genes underexpressed in tumors included genes involved in apoptosis (B-cell CLL/lymphoma 6, secretory leukocyte protease inhibitor, and calpastatin), cell structure (keratin 7 and carcinoembryonic antigen-related cell adhesion molecule 6), and putative tumor suppressor genes (H-Ras-like suppressor 3, retinoic acid receptor responder 1, and growth arrested specific 8) among others. Gene expression patterns also suggested alterations in the Wnt/β-catenin and transforming growth factor β pathways in nasopharyngeal carcinoma. Thus, expression profiles indicate that aberrant expression of growth, survival, and invasion-promoting genes may contribute to the molecular pathogenesis of nasopharyngeal carcinoma. Ultimately, this approach may facilitate the identification of clinical useful markers of disease progression and novel potential therapeutic targets for nasopharyngeal carcinoma.
    Type of Medium: Online Resource
    ISSN: 1078-0432 , 1557-3265
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2004
    detail.hit.zdb_id: 1225457-5
    detail.hit.zdb_id: 2036787-9
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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