Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.2 (focal adhesion kinase)
 44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Germ cells were isolated from rabbit fetal gonads between 18 and 22 days post coitum and examined morphologically, ultrastructurally and for immunocytochemical and cytochemical characteristics. Observations were compared with the information available from the corresponding cells of other mammalian species. The general morphology and ultrastructure of healthy isolated rabbit fetal germ cells were found to be very similar to those of the rabbit and mouse diploid germ cells in situ. Moreover, rabbit fetal germ cells shared common immunocytochemical characteristics with mouse undifferentiated embryonic stem cells or embryonic carcinoma cells, such as the presence of TEC-1 (SSEA-1) antigens, a peripheral network of F-actin, the absence of cytokeratins 8/18 and lamins A/C and an alkaline phosphatase activity. No difference between the sexes was observed. Morphological and physiological similarities with the migrating and cultured primordial germ cells of the mouse also suggest that diploid rabbit germ cells would be good candidates for deriving pluripotential embryonic germ cells (EG cells) if favourable culture conditions could be found. In conclusion, the rabbit may be a suitable model for investigations on EG cells in domestic mammals with delayed meiosis.
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PMID:Ultrastructural and immunocytochemical analysis of diploid germ cells isolated from fetal rabbit gonads. 922 45

The inappropriate activation of protein-tyrosine kinases (PTKs) has been associated with initiation and progression of several types of human cancers. We therefore postulated that immortalization by DNA tumor viruses results in the induction of PTKs fundamental to these processes. An RT-PCR-based screen was thus used to identify PTKs that were abundantly expressed in HPV-18-immortalized epithelial cells and HPV-containing carcinoma cell lines. One of the genes isolated in this screen was the focal adhesion kinase (FAK; pp125FAK), a cytoplasmic protein kinase that is activated in v-src transformed cells or by stimulation with mitogenic polypeptides. FAK also becomes catalytically active upon integrin engagement with extracellular matrix proteins, such as fibronectin. We found that FAK expression and activity were significantly elevated in HPV-18 E6/E7-immortalized human genital epithelial cells relative to their primary cell counterparts. Protein expression and tyrosine phosphorylation of the putative FAK substrate, paxillin, were also notably increased upon HPV-18 immortalization of genital epithelial cells and in HPV-containing cervical carcinoma cell lines. Most significantly, these cells expressed markedly higher levels of both intracellular and extracellular fibronectin, thus providing a mechanism for activation of FAK and increased tyrosine phosphorylation of paxillin. These findings suggest a role for the integrin/FAK-mediated signaling pathway in cervical carcinogenesis and represent one of the first demonstrations of a tyrosine kinase whose activity is elevated following viral immortalization.
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PMID:Activation of the focal adhesion kinase signal transduction pathway in cervical carcinoma cell lines and human genital epithelial cells immortalized with human papillomavirus type 18. 923 61

Bombesin-like peptides, including the mammalian homologue gastrin-releasing peptides, are highly expressed and secreted by neuroendocrine cells in prostate carcinoma (PCa) tissues and are likely to be related to the progression of this disease. In the present study, we show that bombesin enhances the migration of androgen-independent PCa cells (PC-3) in vitro, while not affecting their adhesion to extracellular matrix proteins. The bombesin-increased motility of PC-3 cells occurs through its receptor, and, as shown with inhibitors, it likely requires activation of both protein tyrosine kinases (PTKs) and protein kinases C (PKCs). Because the focal adhesion kinase pp125FAK plays a key role in adhesion/motility and is highly expressed in advanced PCa, we examined whether in PC-3 cells bombesin signal transduction triggers the tyrosine phosphorylation of this PTK and of associated integrins and signaling proteins likely to be present in focal adhesion plaques. pp125FAK tyrosine phosphorylation was stimulated by bombesin and mimicked by PKC activation with the tumor-promotor phorbol 12-myristate-13-acetate (PMA). Moreover, this effect of bombesin on pp125FAK tyrosine phosphorylation requires the presence of both active PKC and cytoskeleton integrity since this signal was abolished by down-regulating PKCs induced by prolonged PMA treatment or by PKC inhibition with GF 109203X, as well as by disruption of the cytoskeleton with cytochalasin D. We also show that bombesin increases the tyrosine phosphorylation of a 95-kDa protein (pp95) which was co-immunoprecipitated with the alpha v and beta (3 and 5) subunits, forming integrin receptors with alpha v in PC-3 cells. The protein pp95 is distinct from the endogenously tyrosine-phosphorylated beta3 subunit. In addition, upon bombesin treatment, the beta1, beta3 and beta5 integrin subunits co-immunoprecipitated with pp125FAK and major phosphotyrosine (pY)-containing proteins of 125 and 68-70 kDa, likely corresponding to pp125FAK and paxillin. Together our data suggest that, in addition to PKC activation, tyrosine phosphorylation of pp125FAK and integrin-associated proteins may play an important role in bombesin signaling, triggering the processes of PCa cell motility and invasion.
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PMID:Bombesin stimulates the motility of human prostate-carcinoma cells through tyrosine phosphorylation of focal adhesion kinase and of integrin-associated proteins. 924 95

Ionizing radiation is a well-known risk factor of cancer development, but the mechanism of radiation induced carcinogenesis is not clear. Chromosomal rearrangements induced by radiation most likely are one of the principal genetic alterations resulting in malignant transformation. The chimeric BCR-ABL associated with chronic myelogenous leukemia (CML) and H4-RET oncogenes associated with thyroid papillary carcinoma are the result of a translocation and inversion, respectively. In vitro studies showed these genes were induced by high-doses of X-irradiation in cell lines. Studies also show that therapeutic external X-ray doses as high as 60 Gy for treatment of various childhood cancers including Hodgkin's disease significantly increase the risk of thyroid cancer. Therefore, we examined the induction and persistence of these chimeric genes in human thyroid tissues transplanted in scid mice after 50 Gy exposure as a function of time for 2 months to elucidate the early events of thyroid carcinogenesis. The H4-RET genes were detected on day 2 and throughout the 2 month period. On the other hand, BCR-ABL genes were detected on day 2 and were undetectable subsequently. These results suggest that ionizing radiation causes various oncogene activations, but cells with only specific gene alteration uniquely associated with thyroid carcinogenesis are selectively retained demonstrating one of the early events in the beginnings of radiation carcinogenesis in human thyroid tissues.
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PMID:Continued expression of a tissue specific activated oncogene in the early steps of radiation-induced human thyroid carcinogenesis. 933 21

The insulin-like growth factor I receptor (IGF-IR) has been shown to mediate mitogenesis and suppression of apoptosis. Certain mutations in the COOH terminus of the receptor abrogate the antiapoptotic activity but not the mitogenic activity. However, truncation of the receptor by deletion of the COOH-terminal 108 amino acids enhances suppression of apoptosis by the IGF-IR, which suggests that the COOH terminus has a negative regulatory role. To investigate this further, a series of mammalian expression vectors were generated that encoded either the COOH terminus of the receptor or the COOH terminus plus the kinase domain. In some cases, the first 16 amino acids of SRC were included at the NH2 terminus to provide a site for myristylation. In transient transfection assays, the membrane-targeted COOH-terminal construct, MyCF, was found to induce apoptosis in MCF-7 breast carcinoma cells and C6 glioblastoma cells, whereas the COOH-terminal construct without the myristylation signal, CF, was poorly cytotoxic. MyKCF, which encodes the kinase domain as well as the COOH terminus, had intermediate cytotoxicity. The cytotoxicity of MyCF was diminished by point mutations that were previously shown to abrogate suppression of apoptosis in the context of the full-length receptor. MCF-7 cells stably expressing the CF or the MyCF proteins exhibited decreased clonogenicity in soft agar and increased sensitivity to UV irradiation. These results indicate that expression of the IGF-IR COOH terminus promotes apoptosis of tumor cells, possibly by interfering with signals necessary for cell survival.
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PMID:Expression of the insulin-like growth factor I receptor C terminus as a myristylated protein leads to induction of apoptosis in tumor cells. 945 7

The gene for transforming growth factor-beta 1 (TGF-beta 1) was transfected into the murine EMT-6/Parent mammary carcinoma tumor line to form the EMT6/PRK5 beta 1E tumor line. In monolayer culture the EMT-6/PRK5 beta 1E tumor line secretes about 15-times as much TGF-beta 1 into the medium as the EMT-6/Parent line. There was no difference in the response of these two cell lines to 4-hydroperoxycyclophosphamide, cisplatin, melphalan or thiotepa in monolayer culture. When the EMT-6/PRK5 beta 1E cells were grown as a solid tumor in Balb/C mice, plasma levels of TGF-beta 1 were about 5-fold higher than in animals bearing the EMT-6/Parent tumor. The EMT-6/PRK5 beta 1E tumor was markedly resistant to a dosage range of cyclophosphamide, cisplatin, melphalan and thiotepa compared with the EMT-6/Parent tumor. The bone marrow CFU-GM from the animals bearing the EMT-6/PRK5 beta 1E tumor were spared from the cytotoxicity of the drugs compared with the bone marrow CFU-GM from animals bearing the EMT-6/Parent tumor. Administration of decorin, a naturally occurring inhibitor of TGF-beta 1, to animals bearing the EMT-6/PRK5 beta 1E tumor prior to treatment of the animals with the antitumor alkylating agents restored drug sensitivity to the tumor and to the bone marrow CFU-GM. Administration of decorin prior to the antitumor alkylating agents produced very little or no increase in the response of the EMT6/Parent tumor or the bone marrow CFU-GM from those animals. The EMT6/PRK5 beta 1E tumor model allows the effect of secretion of TGF-beta 1 on therapeutic resistance to be assessed directly compared with the EMT-6/Parent tumor. In vivo resistance occurred in the presence of high levels of TGF-beta 1 and was reversed by the TGF-beta 1 inhibitor decorin.
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PMID:Transforming growth factor-beta 1 overexpression produces drug resistance in vivo: reversal by decorin. 950 96

In the design of sequential high-dose chemotherapy regimens, the selection of antitumor alkylating agents to be included in each intensification and the interval between the intensifications are critical to the design of the therapy. The tumor cell survival assay and tumor growth delay assay using the murine EMT-6 mammary carcinoma were used as a solid tumor model in which to address these issues. Tumor-bearing mice were treated with high-dose melphalan or cyclophosphamide followed 7 or 12 days later by melphalan, cyclophosphamide, thiotepa, or carboplatin. After treatment with melphalan both 7 and 12 days later, the tumor was resistant to each of the four drugs studied. After treatment with cyclophosphamide both 7 and 12 days later, the tumor was resistant to melphalan and thiotepa but was not resistant to cyclophosphamide or carboplatin. To extend the interval between high-dose treatments to 14 and 21 days, after the first intensification the tumor was transferred to second hosts that were either drug-treated or not drug treated. When high-dose melphalan-treated tumors were treated with a second high dose of melphalan, the tumors were very resistant with the 14-day interval and less resistant with the 21-day interval. This small effect was evident in the bone marrow colony-forming unit, granulocyte-macrophage (CFU-GM), except in the hosts pretreated with melphalan. When high-dose cyclophosphamide-treated tumors were treated with a second high dose of cyclophosphamide, drug resistance was observed both with the 14-day and 21-day interval if the host was non-pretreated or was pretreated with melphalan, but not if the host was pretreated with cyclophosphamide. The same was true in the bone marrow CFU-GM. Tumor growth delay studies supported these findings in that treatment with high-dose cyclophosphamide, melphalan, thiotepa, and carboplatin resulted in less than additive tumor growth delay, whereas treatment with high-dose cyclophosphamide prior to treatment with high-dose melphalan, cyclophosphamide, thiotepa, or carboplatin resulted in additivity to greater-than-additive tumor growth delay. High-dose combination regimens required dose reduction of the drugs, which resulted in decreased tumor growth delays.
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PMID:Acute in vivo resistance in high-dose therapy. 951 40

Changes in integrin expression during malignant transformation have been observed in many tumors. Colon-carcinoma cells show reduced expression or even loss of the alpha5beta1 integrin compared to normal or adenoma cells. To determine the significance of absent alpha5beta1 integrin signaling, we transfected the cDNA coding for the alpha5 integrin sub-unit into the human colon-carcinoma cell line HT29, which constitutively lacks this subunit but does express the beta1 subunit. We show here that the newly expressed fibronectin receptor alpha5beta1 generates multiple signals, causing marked changes in cytoskeletal arrangements within a few minutes of adhesion to fibronectin. Cells expressing the alpha5beta1 integrin exhibit the formation of actin stress fibers and focal adhesions, as well as the induction of tyrosine phosphorylation of several proteins, within 10 min. We identified the focal adhesion kinase pp125FAK and the cytoskeletal protein paxillin as major phosphorylation substrates in these cells. These proteins remained hypophosphorylated when alpha5-negative control cells were plated on fibronectin. The tyrosine kinase pp60c-src, regarded as central in the regulation of cellular proliferation and constitutively over-expressed in HT29 and in colon-carcinoma cells, showed reduced intrinsic kinase activity in unstimulated HT29alpha5 cells. In contrast, fibronectin-induced signaling through alpha5beta1 increased pp60c-src activity. Moreover, immunoprecipitation of pp60c-src from extracts of HT29alpha5 cells cultivated on fibronectin for 20 min revealed complex formation of pp60c-src and tyrosine-phosphorylated pp125FAK. Our data suggest that de novo expression of the alpha5beta1 integrin in HT29 colon-cancer cells restores signaling via pp125FAK and pp60c-src. Thus, loss of this receptor during malignant transformation may contribute to tumor-cell autonomy, while reduced activity of pp60c-src in HT29alpha5-cells may participate directly in growth control.
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PMID:De novo expression of the alpha5beta1-fibronectin receptor in HT29 colon-cancer cells reduces activity of C-SRC. Increase of C-SRC activity by attachment on fibronectin. 953 67

Interleukin-2 (IL-2) is recognized as a T cell growth factor. We have previously reported that human carcinoma cell lines are inhibited in growth by exogenous IL-2, which binds to the IL-2 receptor beta (IL-2Rbeta) chain ubiquitously expressed on the surface of tumor cells. A possibility was considered that IL-2Rbeta on carcinomas responsible for negative signaling was different from that expressed on hematopoietic cells. To investigate this possibility, mRNA for the IL-2Rbeta chain was amplified and compared in carcinoma and lymphoid cells. Using RT-PCR with pairs of sense-antisense oligonucleotide primers specific for the various regions of extracellular, transmembrane and intracellular domains of the IL-2Rbeta chain, we amplified mRNA obtained from three human carcinoma cell lines and human lymphoid cells as controls. The identity of the amplicons was confirmed by Southern analysis with the 32P-labeled cDNA probe coding for the entire span of the IL-2Rbeta chain. In addition, genomic DNA obtained from the tumor cell lines was sequenced to examine the possibility that a mutation is present in the gene coding for the intracellular IL-2Rbeta chain domain. No mutations or deletions were detected. The message for all three domains of the beta chain was identical in tumor cells and in normal lymphoid cells used as controls. Also, by Western blot and northern analyses no differences between IL-2Rbeta chain in tumors vs that expressed in lymphoid cells were demonstrable. The IL-2Rgamma chain, which participates in IL-2/IL-2R signaling pathway, was expressed in tumor cells. Expression of JAK1 transcripts in these cells was comparable to that in lymphocytes. However, RT-PCR analysis identified differences in expression of JAK3 splice variants (B and M) in tumor cells. These differences may be responsible for altered downstream signaling by IL-2. Overall, our data indicate that the same IL-2/IL-2R pathway is operative in human carcinomas and in normal epithelial or lymphoid cells.
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PMID:Molecular analysis of the IL-2 receptor beta chain gene expressed in human tumor cells. 954 32

Several lines of evidence have demonstrated that IFNs could be relevant in the treatment of certain neoplastic diseases such as carcinomas. In particular, IFN-alpha, in addition to the anti-proliferative and cytostatic effects, was demonstrated to be capable of inducing cell death by apoptosis both in vivo and in vitro. Numerous protocols have also been proposed which consider the association of IFN-alpha with other drugs. Among these are retinoids, a class of compounds capable of inducing inhibition of cell growth and differentiation. We address the question here by analyzing the role of cell adhesion in susceptibility to IFN-alpha, RA and their combination of a human cell line derived from a squamous carcinoma of the cervix, the Bcl-2-negative SiHa cell line. In this context, cytoskeleton components and several surface molecules playing a role in cell substrate and cell-to-cell relationships have been evaluated. We found that RA treatment is capable of improving stress fiber formation, decreasing cell detachment and increasing cell-adhesion capability. However, no variations in the ability to adhere to specific extracellular-matrix molecules were found in RA-treated cells. No quantitative changes were detected in integrins involved as receptors for extracellular matrix molecules (VLAI-VLA5) or in other cell-adhesion-associated molecules (e.g., CD44). By contrast, 2 important molecules involved in cell-adhesion processes appeared to be up-regulated by RA exposure: focal adhesion kinase and E-cadherin, involved in adhesion plaque formation and cell-to-cell contacts, respectively. Keeping in mind the importance of adhesion properties in the cell-growth pathway, our findings could be of interest in the study of carcinoma-cell proliferation and metastatic potential.
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PMID:Antiproliferative activity of interferon alpha and retinoic acid in SiHa carcinoma cells: the role of cell adhesion. 959 Jan 30


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