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

B16 melanoma sublines (B16-F10-BL6 and B16-F1) exhibited elevated adenosine 3',5'-cyclic monophosphate (cAMP) levels when cultured in Dulbecco's modified Eagle's medium (DMEM) in comparison to cells in RPMI-1640 medium. In parallel, cells cultured in DMEM had increased tyrosinase activity, melanization and dendrite formation, all markers of melanoma differentiation. Also, the proliferative rates of both cell lines were decreased by 80-85% when cultured in DMEM relative to cells maintained in RPMI-1640 medium. In these studies, elevated levels of the melanin precursors tyrosine (Tyr) and phenylalanine (Phe) found in DMEM were shown not to be solely responsible for the phenotypic changes observed with DMEM. Both BL6 and B16-F1 cell lines formed more experimental pulmonary tumor metastasis in syngeneic C57BL/6 mice when maintained in DMEM vs RPMI-1640 medium. Analysis of metastasis formation in nude mice with normal and depleted natural killer (NK) cell activity revealed that the enhanced lung colonizing capacity of the BL6 cells maintained in DMEM was independent of the function of T-cell or NK-cell-mediated immunity. A close association between metastatic ability of tested lines and the expression of the membrane-associated enzyme gamma-glutamyltranspeptidase (gamma-GTPase, EC 2.3.2.2) was observed. The highly metastatic BL6 cell line had 20-fold higher levels of gamma-GTPase activity than the weakly metastatic B16-F1 cell line. Both cell lines, when grown in DMEM, had elevated gamma-GTPase activity that paralleled augmentation of metastatic ability. The dramatic changes in lung-colonizing capacity of the variant B16 melanoma cells maintained in DMEM in contrast to those grown in RPMI-1640 medium may serve as a useful model in understanding certain steps involved in triggering cell differentiation as well as metastasis development.
Clin Exp Metastasis 1993 May
PMID:Enhancement of pulmonary metastasis formation and gamma-glutamyltranspeptidase activity in B16 melanoma induced by differentiation in vitro. 809 41

Activating mutations of the alpha subunit of the G protein G(s) (G(s)alpha) have been identified in thyroid adenomas and well-differentiated thyroid carcinomas. To examine the role of activating mutations of G(s)alpha in thyroid neoplasia, we transfected rat follicular thyroid (FRTL-5) cells with a transgene in which the cholera toxin A1 subunit (CTA1) is expressed under the control of the rat thyroglobulin gene promoter (TG). This transgene recapitulates effects of the activating mutation of G(s)alpha by its ability to ADP-ribosylate and thereby inhibit GTPase activity of endogenous G(s)alpha molecules. To assess the effect of G(s)alpha activation on cell growth, TGCTA1, or control, pM AM neotransfected FRTL-5 cells (10(4)-10(6)) were injected s.c. into nude mice. TGCTA1-transfected FRTL-5 cells grow in nude mice, whereas control cells do not. Tumor histology revealed increased mitotic activity, infiltration of skeletal muscle, perineural invasion, and plugging of lymphatic spaces. In addition, nude mice injected with TGCTA1 transfected cells or xenografted with the tumors developed metastases to lung. These results indicate that activation of G(s)alpha and constitutive production of cAMP in FRTL-5 cells can result in TSH-independent cellular proliferation and neoplastic transformation.
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PMID:Transformation of rat thyroid follicular cells stably transfected with cholera toxin A1 fragment. 894 Mar 62

Metastasis formation is the leading cause of death in cancer patients. Using an in vitro model system, we have identified Tiam1 (T-lymphoma invasion and metastasis 1) as a gene that can induce invasion by and metastasis of mouse T-lymphoma cells. Subsequent studies showed that Tiam1 is a guanine nucleotide exchange factor for the Rho-like GTPase Rac1, a member of the Ras superfamily of small GTP-binding proteins. Rho-like GTPases play a pivotal role in the orchestration of changes in the actin cytoskeleton in response to receptor stimulation, but have also been shown to be involved in transcriptional activation and cell cycle regulation. Moreover, they can induce oncogenic transformation in fibroblast cells. In this chapter, we first summarize what is known about the signalling pathways that are activated by Tiam1 and Rho-like GTPases, and discuss the putative effectors that may mediate the effects in different cell types. In the latter part, we will more tentatively discuss the role of Tiam1 and Rho-like GTPases in invasion by and metastasis of tumour cells.
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PMID:Rho-like GTPases: their role in cell adhesion and invasion. 1032 Sep 37

Lysophosphatidic acid (LPA) triggers the invasion of a mesothelial cell monolayer by rat ascites hepatoma (MM1) cells. LPA also induces rapid morphological changes of MM1 cells, cell surface blebbing and pseudopodia formation. Pseudopodia formation is tightly correlated with cellular invasiveness. Clostridium Botulinum C3 exoenzyme and genistein abrogated the formation of blebs and pseudopodia together with the inhibition of invasion, indicating that GTPase Rho and certain tyrosine kinases are involved in both processes. MM1 cells expressing constitutively active Rho exhibited the invasion and the formation of blebs and pseudopodia in the absence of LPA. In contrast, MM1 cells expressing constitutively active Rac were not invasive in the absence of LPA, but were invasive in the presence of LPA. Their morphological response to LPA was almost the same as that of parental MM1 cells. Expression of dominant negative Rac suppressed the invasiveness to approximately 3% of that of parental MM1 cells, together with the inhibition of pseudopodia formation. Thus, Rho and Rac are cooperatively involved in both the invasion and the related morphological changes of MM1 cells. Rho activation is sufficient both for the induction of invasion and the morphological changes leading to the invasion, whereas Rac activation is necessary but not sufficient by itself. We propose that Rho activation is not mediated by Rac but the cooperation of both GTPases is essential to trigger the invasive behavior of MM1 cells.
Clin Exp Metastasis 1999 Mar
PMID:Involvement of small GTPases Rho and Rac in the invasion of rat ascites hepatoma cells. 1041 Nov 6

Rac1 is a member of the Ras superfamily of small guanosine triphosphatases (GTPases) that act as molecular switches to control cytoskeletal rearrangements and cell growth. Analogous to Ras, constitutively activating point mutations of Rac1 cause tumorigenic transformation of cell lines. However, there is no information about whether Rac1 is also mutated in vivo. After RT - PCR of Rac1, several clones of seven benign and 10 malignant breast cancer tissues as well as eight breast cancer cell lines were sequenced. Only single-nucleotide polymorphisms of Rac1 could be detected, and none of these corresponded to constitutively activating point mutations that have been used in cell lines for transformation. While sequencing Rac1 in breast tissues, a new Rac1 isoform with an insertion of 19 codons within the reading frame of Rac1 close to switch region II was identified and named Rac1b. The Rac1b protein acts like a fast cycling GTPase in GTP binding and hydrolysis assays. In Northern and Western blot experiments both Rac1 RNA and Rac1 protein had a significantly higher expression in breast cancer tissues compared to normal breast tissue samples. Immunohistochemical staining of Rac1 showed weak Rac1 expression in benign breast disease but high expression level in ductal carcinoma-in-situ, primary breast cancer, and lymph node metastases. In addition, breast tumor cells from patients with recurrent disease had Rac1 expression at the plasma membrane, suggesting activation of Rac1, in patients with aggressive breast cancer. Oncogene (2000).
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PMID:Rac1 in human breast cancer: overexpression, mutation analysis, and characterization of a new isoform, Rac1b. 1087 53

The most important factor in predicting outcome in patients with early breast cancer is the stage of the disease. There is no robust marker capable of identifying invasive carcinomas that despite their small size have a high metastatic potential, and that would benefit from more aggressive treatment. RhoC-GTPase is a member of the Ras-superfamily and is involved in cell polarity and motility. We hypothesized that RhoC expression would be a good marker to identify breast cancer patients with high risk of developing metastases, and that it would be a prognostic marker useful in the clinic. We developed a specific anti-RhoC antibody and studied archival breast tissues that comprise a broad spectrum of breast disease. One hundred eighty-two specimens from 164 patients were used. Immunohistochemistry was performed on formalin-fixed tissues. Staining intensity was graded 0 to 3+ (0 to 1+ was considered negative and 2 to 3+ was considered positive). RhoC was not expressed in any of the normal, fibrocystic changes, atypical hyperplasia, or ductal carcinoma in situ, but was expressed in 36 of 118 invasive carcinomas and strongly correlated with tumor stage (P = 0.01). RhoC had high specificity (88%) in detecting invasive carcinomas with metastatic potential. Of the invasive carcinomas smaller than 1 cm, RhoC was highly specific in detecting tumors that developed metastases. RhoC expression was associated with negative progesterone receptor and HER-2/neu overexpression. We characterized RhoC expression in human breast tissues. RhoC is specifically expressed in invasive breast carcinomas capable of metastasizing, and it may be clinically useful in patients with tumors smaller than 1 cm to guide treatment.
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PMID:Characterization of RhoC expression in benign and malignant breast disease: a potential new marker for small breast carcinomas with metastatic ability. 1183 78

Inflammatory breast cancer (IBC) is the most lethal form of locally advanced breast cancer known. IBC carries a guarded prognosis primarily due to rapid onset of disease, typically within six months, and the propensity of tumor emboli to invade the dermal lymphatics and spread systemically. Although the clinical manifestations of IBC have been well documented, until recently little was known about the genetic mechanisms underlying the disease. In a comprehensive study aimed at identifying the molecular mechanisms responsible for the unique IBC phenotype, our laboratory identified overexpression of RhoC GTPase in over 90% of IBC tumors in contrast to 36% of stage-matched non-IBC tumors. We also demonstrated that overexpression of RhoC GTPase in human mammary epithelial (HME) cells nearly recapitulated the IBC phenotype with regards to invasion, motility and angiogenesis. In the current study we sought to delineate which signaling pathways were responsible for each aspect of the IBC phenotype. Using well-established inhibitors to the mitogen activated protein kinase (MAPK) and phosphatidylinositol-3 kinase (PI3K) pathways. We found that activation of the MAPK pathway was responsible for motility, invasion and production of angiogenic factors. In contrast, growth under anchorage independent conditions was dependent on the PI3K pathway.
Clin Exp Metastasis 2002
PMID:Mitogen activated protein kinase pathway is involved in RhoC GTPase induced motility, invasion and angiogenesis in inflammatory breast cancer. 1209 Apr 70

A balance between proliferation, differentiation, migration and death of cells is critical for the normal development of an organism. Perturbations of this balance can contribute to cancer development. The p21-activated serine/threonine kinases (Paks) play an important role in a variety of cellular functions including cell morphogenesis, motility, survival, angiogenesis, and mitosis. Paks were initially identified as an effector molecules of RHO GTPases; however, recent evidence that they can be activated in both GTPase-dependent and -independent manners expands our understanding of their physiologic functions. Paks play an important role in growth factor signaling, leading to cytoskeletal reorganization that subsequently influences growth factor-mediated cell migration and metastasis functions. Recent findings that Paks play a role in mitosis, nuclear receptor-signaling and deregulation of Pak in cancer cells suggest that these kinases play an important role in both normal development and cancer progression. In this review, we summarize the results of recent advances into the role of Paks in tumorigenesis and metastasis.
Cancer Metastasis Rev 2003 Dec
PMID:P21-activated kinases in human cancer. 1288 13

Here we describe the isolation of C33/CD82/KAI1 in a screen for apoptosis-inducing genes. C33 is a gene that is downregulated in many metastatic tumor cells and the expression of which can attenuate the process of metastases formation in a variety of tumors. In accordance, we observed cell death induction by C33 in many different cell types. C33 seems to promote cell death by the generation of reactive oxygen intermediates (ROIs). These ROIs, however, are not derived from the mitochondrial respiratory chain as in most other scenarios leading to apoptosis. We observed that C33 renders cells sensitive to ROIs by causing the specific release of the intracellular antioxidant glutathione (GSH) from cells. Moreover, C33 activates the GTPase Cdc42, which mediates GSH release and apoptosis induction and allows to detect the formation of ROIs.
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PMID:The metastasis suppressor gene C33/CD82/KAI1 induces apoptosis through reactive oxygen intermediates. 1459 53

Inflammatory breast cancer (IBC) is the most deadly form of breast cancer in humans presumably due to its ability to metastasize from its inception. In our laboratory, overexpression of RhoC GTPase was observed to be specific for IBC tumors, but not for stage-matched, non-IBC tumors. RhoC is known to contribute to an IBC-like phenotype in HPV-E6E7 immortalized breast cells. To further study the effect of RhoC overexpression on IBC metastasis, we generated stable transfectants of spontaneous immortalized mammary epithelial cells (MCF10A) overexpressing wild-type RhoC or a constitutively active RhoC mutant (G14V). Both the RhoC wild type and the G14V transfectants were highly invasive and proliferated more rapidly compared to vector-only control clones. Overexpression of RhoC led to an increase in actin stress fiber and focal adhesion contact formation. Comparative microarray analysis of these clones further revealed that RhoC overexpression upregulated 108 genes whereas seven genes were down-regulated. We have further verified by quantitative RT-PCR that genes involved in cell proliferation, invasion/adhesion, and angiogenesis were modulated by RhoC. This work suggests strong candidates for the downstream oncogenic functions of RhoC.
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PMID:RhoC induces differential expression of genes involved in invasion and metastasis in MCF10A breast cells. 1499 49


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