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: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inhibition of cell proliferation is an important biologic function of interferons (IFNs), which has been exploited in therapeutic treatment of certain hematologic malignancies. However, the molecular mechanism was not clear. We have recently shown that IFNs (alpha/beta and gamma) inhibit protein kinase C (PKC)-dependent (such as PDGF and phorbol ester) but not PKC-independent (such as epidermal growth factor) activation of Raf-1 and mitogen-activated protein kinases (MAPK/ERKs) in fibroblasts (Xu et al, Mol Cell Biol 14:8018, 1994), suggesting a novel mechanism by which IFNs execute their antiproliferative function. Monocytes/macrophages are primary targets in vivo for IFN-gamma, the major activity of macrophage-activating factor. In the present study, mechanism of IFN-gamma-induced antiproliferative action in macrophages in response to colony-stimulating factor-1 (CSF-1) has been investigated. Our results show that antiproliferative effect of IFN-gamma overrode mitogenic effect of CSF-1 and phorbol ester, as measured by early gene expression, DNA synthesis and cell proliferation. Although activation, phosphorylation, and turnover of the CSF-1 receptor and CSF-1-induced increase in diacylglycerol production remained normal, IFN-gamma blocked CSF-1-stimulated activation of mitogen-activated protein kinases, Raf-1 kinase, increase in GTP-bound Ras and tyrosine phosphorylation, and activation of protein kinase C delta (PKC-delta). PKC-delta was required for CSF-1-induced mitogenic signaling and a primary target for IFN-gamma-induced inhibition. Interestingly, although phorbol myristate acetate stimulated Ras activation, PKC-delta did not appear to be an upstream activator of Ras. These studies clearly indicated that IFN-gamma specifically inhibits PKC-delta activation, resulting in blockage of the early events of mitogenesis in macrophages in response to CSF-1.
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PMID:Blockage of the early events of mitogenic signaling by interferon-gamma in macrophages in response to colony-stimulating factor-1. 870 28

The protein p27KIP1 belongs to a recently identified family of proteins termed cyclin-dependent kinase inhibitors (CDKIs). These proteins play an important role in regulating cell-cycle progression and loss of their function has been implicated in tumorigenesis. Transforming growth factor beta (TGF-beta) may induce cell growth arrest through p27 activation. TGF-beta often loses its ability to arrest growth of transformed cells; this could potentially occur through a defect in p27. To determine the role of p27 in tumorigenesis, we examined its mutational status in 74 non-Hodgkin's lymphomas (NHLs) (52 of B-cell phenotype, 22 of T-cell phenotype), 5 lymphoma cell lines, and 42 adult T-cell leukemias/lymphomas (ATLs) using polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) and Southern blot analyses. A nonsense mutation (stop codon) that could result in expression of a truncated nonfunctional p27 protein was detected at codon 76 in one case of acute lymphomatous ATL, but not in matched normal tissues. Previously undescribed polymorphisms were also identified at codon 109 in the lymphomas and at codon 55 in the ATLs. Two homozygous deletions of the p27 gene were detected in one case of B-immunoblastic NHL and in one case of acute ATL by Southern blot hybridization. These results indicate that p27 gene alterations are rare events in NHLs and ATLs, but may play an important role in the pathogenesis of some hematologic malignancies.
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PMID:Alterations of the p27KIP1 gene in non-Hodgkin's lymphomas and adult T-cell leukemia/lymphoma. 765 21

Inactivation of the cyclin-dependent kinase inhibitors p16INK4A and p15INK4B are frequent alterations in neoplasia, often resulting from homozygous deletion or promoter region hypermethylation. We have analyzed both modes of inactivation of p15INK4B and p16INK4A in the major types of adult and pediatric hematological malignancies. Hypermethylation of p15INK4B, without alteration of p16INK4A, was an almost universal finding in adult acute myelogenous leukemia, and occurred very frequently in adult acute lymphocytic leukemia and pediatric acute myelogenous leukemia and acute lymphocytic leukemia. In contrast, neither p15INK4B nor p16INK4A were inactivated in any stage of chronic myelogenous leukemia. Hypermethylation of p16INK4A, often without alterations of p15INK4B, was found in non-Hodgkin's lymphoma and was much more frequent in cases with high-grade than low-grade histology. Enriched normal bone marrow stem cells had no detectable promoter region methylation of these genes, as analyzed by a newly developed PCR method. Remarkably distinct patterns of inactivation of p15INK4B and p16INK4A characterize different types of hematological malignancy, and alterations in these tumor suppressor genes are one of the most common alterations in hematological malignancies.
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PMID:Distinct patterns of inactivation of p15INK4B and p16INK4A characterize the major types of hematological malignancies. 904 Nov 82

Lymphatic mapping with selective sentinel lymphadenectomy allows accurate pathologic examination of the nodes most likely to contain macro- or micrometastastic disease for staging and proper adjuvant chemotherapy. The hypothesis of SLN biopsies was histopathologically validated by Turner et al that if the node is tumor free by H&E and immunohistochemistry, the probability of non-SLN involvement is less than 0.1%. Giuliano et al and Veronesi et al reported that detection of metastases in SLNs by frozen section technique is 89% and 64%, respectively. At MCC, frozen section evaluation of SLN is not performed because of its potential loss of micrometastasis in the cryostat, freezing artifacts, sampling error, and perhaps radioactive contamination. Intraoperative detection of macro- or micrometastasis is critical because it enables conversion of patients with positive SLN to CLND in one surgical setting more cost-effectively. IIC of the lymph nodes has been used routinely in the diagnosis of hematologic malignancies and also in breast cancer as a useful method in many series. In the author's experience, IIC by Diff-Quik stain converted 100% of grossly positive and suspicious SLNs and 22% of grossly negative SLNs. The significance of detecting micrometastases in axillary lymph nodes using immunohistochemical techniques has been reported in many series. At the MCC, routine use of CKI on paraffin sections of grossly negative SLNs enabled the upstaging of 10.6% of patients from N0 to N1. Recent addition of intraoperative rapid CKI as an adjunct to complement Diff-Quik stain has proven to be more sensitive in detecting micrometastases than using Diff-Quik stain alone. IIC technique using either Diff-Quik stain or CKI requires intensive training and experience to avoid potential pitfalls and errors in interpretation. Evaluation of SLN should use methods that enhance the ability to detect micrometastasis, however, in a cost-effective manner. The cost-effectiveness of IIC by Diff-Quik stain is incomparable with frozen section evaluation. The added cost of routine immunohistochemical stain and perhaps multiple levels of H&E stain should be offset by the decreased costs of IIC and clinically by treating most patients in the outpatient settings. In summary, IIC by Diff-Quik stain is simple, rapid, and has excellent diagnostic accuracy in grossly positive and suspicious SLNs allowing cost-effective, immediate CLND. IIC by CKI is an extremely useful ancillary technique that complements Diff-Quik stain in detecting micrometastases particularly in low grade ductal or lobular carcinoma and low tumor cell volume. Appropriate combined use of both stains may lead to intraoperative nodal staging and cost-effective CLND. SLN mapping technology at MCC using IIC in conjunction with serial sections, entire tissue submission, routine use of CKI, and multiple levels of the SLN have led us to uncover micrometastasis in high-risk, traditionally node-negative patients. These results have encouraged investigators to pursue even more sensitive techniques to detect micrometastases, including molecular biology techniques such as RT-PCR. Experienced cytopathologists and active cytopathology services are required to avoid potential pitfalls in performing and interpreting IIC. More long-term follow-up and prospective trials are needed to determine the prognostic significance of upstaging by ancillary techniques, which may lead to a revision of the current TNM staging system.
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PMID:Pathologic examination of sentinel lymph nodes in breast cancer. 1044 90

Peripheral blood progenitor cells (PBPC) mobilized by granulocyte colony-stimulating factor (G-CSF) promptly engraft allogeneic recipients after myeloablative chemotherapy for hematologic malignancies. Surprisingly, no exacerbation of acute graft-vs-host disease has been observed despite a 10-fold higher T-cell content in PBPC compared with bone marrow allografts. Because G-CSF can suppress T-cell proliferation in response to mitogens and enhance their activation-induced apoptosis, we examined the molecular mechanisms underlying G-CSF-induced immune dysfunction. Normal allogeneic lymphocytes were challenged with phytohemagglutinin in the presence of serum collected after G-CSF administration (postG) to healthy PBPC donors, and the expression of key components of the cell cycle and apoptotic machineries was investigated by flow cytometry and Western blotting. Lymphocyte stimulation was associated with collapse of mitochondrial transmembrane potential, hypergeneration of reactive oxygen intermediates, and activation of caspase-3 and DNA fragmentation. Lymphocytes were arrested in a G(1)-like phase of the cell cycle, as measured by G(1)-phase cyclin expression and bromodeoxyuridine (BrdUrd) incorporation. Cell tracking experiments confirmed the occurrence of a lower number of population doublings in postG compared with preG cultures. Unexpectedly, the phosphorylation state of the protein encoded by the retinoblastoma susceptibility gene (pRB) was unaltered in postG cultures, and the inhibition of cell cycle progression occurred without the recruitment of the cyclin-dependent kinase inhibitors p15(INK4B), p16(INK4A), and p27(Kip1). We eventually evaluated the ability of antioxidant/cytoprotectant agents to prevent the G-CSF-induced mitochondrial dysfunction and inhibition of cell cycle progression. Of interest, both N-acetylcysteine and amifostine reduced apoptotic cell death by 45% on average, inhibited the activation/processing of caspase-3, and increased BrdUrd incorporation in postG cultures. Based on these experimental findings, a model is proposed in which T-cell activation in the presence of serum immunoregulatory factor(s) induced by G-CSF is associated with a molecular phenotype mimicking the G(1)-S transition and consisting of pRB phosphorylation, lack of CDKI recruitment, and reduced cyclin-E expression. The putative relationship between lymphocyte mitogenic unresponsiveness and apoptosis induction would occur at the level of key molecules shared by the cell cycle and apoptotic machineries. Whether the G-CSF-mediated modulation of lymphocyte functions in vitro is beneficial in transplantation medicine remains to be determined.
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PMID:T-cell apoptosis induced by granulocyte colony-stimulating factor is associated with retinoblastoma protein phosphorylation and reduced expression of cyclin-dependent kinase inhibitors. 1130 Nov 80

Members of the nuclear receptor superfamily, including retinoic acid receptors (RARs), retinoid X receptors (RXRs), and vitamin D receptors (VDRs), are transcription factors that control many important cellular functions, and their ligands are widely used in several clinical indications. The latest family member is the peroxisome proliferator-activated receptor-gamma (PPARgamma), which is highly expressed in normal monocytes, different leukemias, and epithelial malignancies. PPARgamma ligands have been developed and signal differentiation, growth arrest, and apoptosis. PPARgamma forms heterodimers with RXR, and ligation of both receptors is required for maximal signaling. PPARgamma signaling, its expression in hematologic malignancies, and role in differentiation are discussed. Interactions of PPARgamma with X-RARalpha, protein kinase R (PKR), PTEN, and mitogen-activated protein kinase (MAPK) have been described. PPARgamma ligands have been developed for the management of diabetes, but new and more potent ligands, including triterpenoids, are being investigated as therapeutic agents for epithelial and hematologic malignancies.
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PMID:Role of peroxisome proliferator-activated receptor-gamma in hematologic malignancies. 1204 3

Interactions between the proteasome inhibitor bortezomib and histone deacetylase inhibitors (HDIs) have been examined in Bcr/Abl+ human leukemia cells (K562 and LAMA 84). Coexposure of cells (24-48 hours) to minimally toxic concentrations of bortezomib + either suberoylanilide hydroxamic acid (SAHA) or sodium butyrate (SB) resulted in a striking increase in mitochondrial injury, caspase activation, and apoptosis, reflected by caspases-3 and -8 cleavage and poly(adenosine diphosphate-ribose) polymerase (PARP) degradation. These events were accompanied by down-regulation of the Raf-1/mitogen-induced extracellular kinase (MEK)/extracellular signal-related kinase (ERK) pathway as well as diminished expression of Bcr/Abl and cyclin D1, cleavage of p21CIP1 and phosphorylation of the retinoblastoma protein (pRb), and induction of the stress-related kinases Jun kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). Transient transfection of cells with a constitutively active MEK construct significantly protected them from bortezomib/SAHA-mediated lethality. Coadministration of bortezomib and SAHA resulted in increased reactive oxygen species (ROS) generation and diminished nuclear factor kappa B (NF-kappa B) activation; moreover, the free radical scavenger L-N-acetylcyteine (LNAC) blocked bortezomib/SAHA-related ROS generation, induction of JNK and p21CIP1, and apoptosis. Lastly, this regimen potently induced apoptosis in STI571 (imatinib mesylate)-resistant K562 cells and CD34+ mononuclear cells obtained from a patient with STI571-resistant disease, as well as in Bcr/Abl- leukemia cells (eg, HL-60, U937, Jurkat). Together, these findings raise the possibility that combined proteasome/histone deacetylase inhibition may represent a novel strategy in leukemia, including apoptosis-resistant Bcr/Abl+ hematologic malignancies.
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PMID:The proteasome inhibitor bortezomib interacts synergistically with histone deacetylase inhibitors to induce apoptosis in Bcr/Abl+ cells sensitive and resistant to STI571. 1289 73

Interactions between the cyclin-dependent kinase (CDK) inhibitor flavopiridol and the proteasome inhibitor bortezomib were examined in Bcr/Abl(+) human leukemia cells. Coexposure of K562 or LAMA84 cells to subtoxic concentration of flavopiridol (150-200 nM) and bortezomib (5-8 nM) resulted in a synergistic increase in mitochondrial dysfunction and apoptosis. These events were associated with a marked diminution in nuclear factor kappaB (NF-kappaB)/DNA binding activity; enhanced phosphorylation of SEK1/MKK4 (stress-activated protein kinase/extracellular signal-related kinase 1/mitogen-activated protein kinase kinase 4), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK); down-regulation of Bcr/Abl; and a marked reduction in signal transducer and activator of transcription 3 (STAT3) and STAT5 activity. In imatinib mesylate-resistant K562 cells displaying increased Bcr/Abl expression, bortezomib/flavopiridol treatment markedly increased apoptosis in association with down-regulation of Bcr/Abl and BclxL, and diminished phosphorylation of Lyn, Hck, CrkL, and Akt. Parallel studies were performed in imatinib mesylate-resistant LAMA84 cells exhibiting reduced expression of Bcr/Abl but a marked increase in expression/activation of Lyn and Hck. Flavopiridol/bortezomib effectively induced apoptosis in these cells in association with Lyn and Hck inactivation. The capacity of flavopiridol to promote bortezomib-mediated Bcr/Abl down-regulation and apoptosis was mimicked by the positive transcription elongation factor-b (P-TEFb) inhibitor DRB (5,6-dichloro 1-beta-d-ribofuranosylbenzinida-sole). Finally, the bortezomib/flavopiridol regimen also potently induced apoptosis in Bcr/Abl(-) human leukemia cells. Collectively, these findings suggest that a strategy combining flavopiridol and bortezomib warrants further examination in chronic myelogenous leukemia and related hematologic malignancies.
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PMID:Bortezomib and flavopiridol interact synergistically to induce apoptosis in chronic myeloid leukemia cells resistant to imatinib mesylate through both Bcr/Abl-dependent and -independent mechanisms. 1503 84

Transforming growth factor beta (TGFbeta) is one of few known negative regulators of hematopoiesis, yet the mechanisms by which it affects cell cycle arrest and stem cell quiescence are poorly understood. Induction of the cyclin-dependent kinase inhibitors, p15INK4b (p15) and p21WAF1 (p21) is important for TGFbeta-mediated cytostasis in epithelial cells but not in hematopoietic cells. Using primary human hematopoietic cells and microarray analysis, we identified p57KIP2 (p57) as the only cyclin-dependent kinase inhibitor induced by TGFbeta. Up-regulation of p57 mRNA and protein occurs before TGFbeta-induced G1 cell cycle arrest, requires transcription, and is mediated via a highly conserved region of the proximal p57 promoter. The up-regulation of p57 is essential for TGFbeta-induced cell cycle arrest in these cells, because two different small interfering RNAs that prevent p57 up-regulation block the cytostatic effects of TGFbeta on human hematopoietic cells. Reduction of basal p57 expression by this approach also allows hematopoietic cells to proliferate more readily in the absence of TGFbeta. p57 is a putative tumor suppressor gene whose expression is frequently silenced by promoter hypermethylation in hematologic malignancies. Our studies identify a molecular pathway by which TGFbeta mediates its cytostatic effects on human hematopoietic cells and suggests an explanation for the frequent silencing of p57 expression.
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PMID:Transforming growth factor beta-induced cell cycle arrest of human hematopoietic cells requires p57KIP2 up-regulation. 1547 87

Earlier we reported that a novel mitotic protein kinase, PDZ-binding kinase (PBK), is expressed in primary hematopoietic neoplasms. Recent reports have suggested a role for PBK in mitotic progression. In the present study, we demonstrate that PBK is down regulated during doxorubicin induced growth arrest of HL60 promyelocytic leukemia cells at least partly due to cell cycle-specific transcriptional regulation. Furthermore, we show that transcriptional control is mostly due to binding of transcription factors E2F and CREB/ATF to two distinct binding sites within the PBK promoter. This was demonstrated by: (i) electrophoretic mobility shift assays showing transcription factor binding within the PBK promoter at the putative E2F (-146bp) and CREB/ATF (-312bp) binding sites; (ii) Western immunoblot analysis of knockdown extracts from siRNA inhibition of transcription factor expression showing that PBK protein expression is dependent upon the presence of these transcription factors; (iii) codistribution of CREB factor and PBK in cell lines of disparate tissue origin; and (iv) luciferase reporter assays showing that PBK promoter activity is dependent on factor binding at intact E2F and CREB/ATF sites. These findings may provide insight into the mechanisms that upregulate PBK expression in proliferative hematologic malignancies and down regulate its expression following growth arrest of leukemic cells.
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PMID:Expression of PDZ-binding kinase (PBK) is regulated by cell cycle-specific transcription factors E2F and CREB/ATF. 1617 62


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