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)

The radiosensitivity of proliferating crypt epithelial cells makes the gut a major limiting factor in the use of radiotherapy for treatment of abdominal cancers. As post-mitotic epithelial cells migrate from mouse small intestinal crypts to the base of adjacent villi, they rapidly lose their ability to undergo apoptosis in response to ionizing irradiation (IR). To determine whether this radioresistance reflects withdrawal from the cell cycle, we used a lineage-specific promoter to direct expression of wild type Simian virus 40 T antigen (SV40 TAg(Wt)) to villus, but not crypt, enterocytes in FVB/N transgenic mice. SV40 TAg(Wt) induced, pRB-dependent, re-entry into the cell cycle is not associated with the acquisition of IR-stimulated apoptosis 4 h or 24 h after 6 Gy or 12 Gy of gamma-irradiation. Co-expression of SV40 TAg(Wt) and K-ras(val12) produces dysplasia in cycling villus enterocytes but no shift towards apoptotic responsiveness to IR. These findings suggest that the radioresistance of villus enterocytes is not simply due to their cell cycle arrest and may be a reflection of their microenvironment. Remarkably, reentry of villus enterocytes to the cell cycle increases the radiosensitivity of the crypt epithelium without changing Bcl-2, Bcl-xL, Bak, or Bax expression. This effect is only manifest after IR and, based upon results obtained with mutant SV40 TAgs, depends upon reaching a critical level of proliferation in villus enterocytes. Like the normal crypt response to IR, the villus-derived enhancement of IR-stimulated crypt apoptosis is associated with an induction of p53 and Raf-1, and is dependent upon p53. Unlike the normal crypt response to IR, the p53 induction involves cells distributed throughout the crypt and the apoptotic response is not confined to the lower half of the crypt. These results indicate that signals initiated by cycling enterocytes can be transmitted to the crypt epithelium to induce p53 and influence their IR-induced apoptosis. Understanding the underlying signaling pathways may provide clues about how to modify a normal crypt's radiosensitivity for therapeutic benefit.
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PMID:gamma-Ray-induced apoptosis in transgenic mice with proliferative abnormalities in their intestinal epithelium: re-entry of villus enterocytes into the cell cycle does not affect their radioresistance but enhances the radiosensitivity of the crypt by inducing p53. 924 49

It has been shown that expression of the RIalpha subunit of cyclic AMP (cAMP)-dependent protein kinase is enhanced in human cancer cell lines, primary tumors, and cells after transformation. Using an antisense strategy, we have shown that RIalpha has a role in neoplastic cell growth in vitro and in vivo. In the present study, we have investigated the sequence- and target-specific effects of exogenous RIalpha antisense oligodeoxynucleotides (ODNs) and endogenous antisense gene on tumor growth, apoptosis, and cAMP signaling in androgen-insensitive prostate cancer cells, both in vitro and in nude mice. Here, we show that an RIalpha antisense, RNA/DNA mixed backbone ODN exerts a reduction in RIalpha expression at both the mRNA and protein levels, up-regulation of both the RIIbeta subunit of cAMP-dependent protein kinase or protein kinase A and c-AMP-phosphodiesterase IV expression, and inhibition of cell growth. Growth inhibition was accompanied by changes in cell morphology and the appearance of apoptotic nuclei. In addition, Bcl-2 hyperphosphorylation; increase in the proapoptotic proteins Bax, Bak, and Bad; and Bad hypophosphorylation occurred in the antisense-treated cells. These effects of exogenously supplied antisense ODN mirrored those induced by endogenous antisense gene overexpression. The RIalpha antisense ODNs, which differed in sequence or chemical modification, promoted a sequence- and target-specific reduction in RIalpha protein levels and inhibited tumor growth in nude mice. These results demonstrate that in a sequence-specific manner, RIalpha antisense, via efficient depletion of the growth stimulatory molecule RIalpha, induces growth inhibition, apoptosis, and phenotypic (cell morphology) changes, providing an innovative approach to combat hormone-insensitive prostate cancer cell growth.
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PMID:Protein kinase A RIalpha antisense inhibition of PC3M prostate cancer cell growth: Bcl-2 hyperphosphorylation, Bax up-regulation, and Bad-hypophosphorylation. 1183 45

Bak is a pro-apoptotic member of the Bcl-2 family that is activated by apoptotic stimulation: its activation is characterized by conformational changes such as exposure of the N terminus and oligomerization. In death receptor-mediated apoptosis, the activation of Bak depends on activation of caspase-8. However, we found that exposure of the N terminus of Bak (but not oligomerization) can occur in the absence of active caspase-8. Although exposure of the N terminus of Bak without oligomerization is not sufficient to release cytochrome c from the mitochondria and commit cells to apoptosis, this change sensitizes the mitochondria to apoptotic signals (including Bid) and thus sensitizes cells to apoptotic death. Fas-induced, caspase-8-independent exposure of the N terminus of Bak is blocked by staurosporine, a pan protein kinase inhibitor. These results suggest that Fas stimulation not only activates caspase-8, but also a distinct signaling pathway involving protein kinase(s) to induce exposure of the N terminus of Bak.
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PMID:A caspase-8-independent signaling pathway activated by Fas ligation leads to exposure of the Bak N terminus. 1515 9

We examined the influence of ROS on the phosphorylation and complex formation of Bcl-2 family proteins in Mn-superoxide dismutase (SOD) antisense-transfected squamous cell carcinoma cells, OSC-4 cells. The increase of intracellular ROS level induced by cis-diamminedichloroplatinum (CDDP) and gamma-ray treatment was greater in antisense-transfected cells than in control vector-transfected cells, and apoptosis was more extensively induced in the former. Antisense-transfected cells expressed high levels of Bax and Bak, but low levels of Bcl-2 and Bcl-XL when treated with CDDP, peplomycin, 5-fluorouracil or gamma-rays. After treatment with these agents, the phosphorylation of protein kinase A, Bcl-2 (Thr56) and Bad (Ser155) was increased, especially in antioxidant (N-acetylcysteine and pyrrolidine dithiocarbamate)-pretreated control cells, but the phosphorylation levels were very low in the antisense-transfected cells. Bcl-2 ubiquitination was increased, but ubiquitination of Bad and Bax was decreased in the antisense-transfected cells, although their ubiquitination was increased by the antioxidants. These results reveal that ROS induce apoptosis by regulating the phosphorylation and ubiquitination of Bcl-2 family proteins, resulting in increased proapoptotic protein levels and decreased antiapoptotic protein expression.
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PMID:Reactive oxygen species (ROS) control the expression of Bcl-2 family proteins by regulating their phosphorylation and ubiquitination. 1529 26

Interactions between the histone deacetylase (HDAC) inhibitors suberanoylanilide hydroxamic acid (SAHA) and sodium butyrate (SB) and the heat shock protein (Hsp) 90 antagonist 17-allylamino 17-demethoxygeldanamycin (17-AAG) have been examined in Bcr-Abl(+) human leukemia cells (K562 and LAMA84), including those sensitive and resistant to STI571 (imatinib mesylate). Cotreatment with 17-AAG and SAHA or SB synergistically induced mitochondrial dysfunction (cytochrome c and apoptosis-inducing factor release), caspase-3 and -8 activation, apoptosis, and growth inhibition. Similar effects were observed in LAMA84 cells and K562 cells resistant to STI571, as well as in CD34(+) cells isolated from the bone marrows of three patients with chronic myelogenous leukemia. These events were associated with increased binding of Bcr-Abl, Raf-1, and Akt to Hsp70, and inactivation of extracellular signal-regulated kinase 1/2 and Akt. In addition, 17-AAG/SAHA abrogated the DNA binding and the transcriptional activities of signal transducer and activator of transcription (STAT) 5 in K562 cells, including those ectopically expressing a constitutively active STAT5A construct. Cotreatment with 17-AAG and SAHA also induced down-regulation of Mcl-1, Bcl-xL, and B-Raf; up-regulation of Bak; cleavage of 14-3-3 proteins; and a profound conformational change in Bax accompanied by translocation to the membrane fraction. Moreover, ectopic expression of Bcl-2 attenuated cell death induced by this regimen, implicating mitochondrial injury in the lethality observed. Together, these findings raise the possibility that combining HDAC inhibitors with the Hsp90 antagonist 17-AAG may represent a novel strategy against Bcr-Abl(+) leukemias, including those resistant to STI571.
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PMID:Cotreatment with suberanoylanilide hydroxamic acid and 17-allylamino 17-demethoxygeldanamycin synergistically induces apoptosis in Bcr-Abl+ Cells sensitive and resistant to STI571 (imatinib mesylate) in association with down-regulation of Bcr-Abl, abrogation of signal transducer and activator of transcription 5 activity, and Bax conformational change. 1562 78

Prostate cancer is the most common invasive malignancy and the second leading cause of cancer-related deaths among U.S. males, with a similar trend in many Western countries. One approach to control this malignancy is its prevention through the use of agents present in diet consumed by humans. Pomegranate from the tree Punica granatum possesses strong antioxidant and antiinflammatory properties. We recently showed that pomegranate fruit extract (PFE) possesses remarkable antitumor-promoting effects in mouse skin. In this study, employing human prostate cancer cells, we evaluated the antiproliferative and proapoptotic properties of PFE. PFE (10-100 microg/ml; 48 h) treatment of highly aggressive human prostate cancer PC3 cells resulted in a dose-dependent inhibition of cell growth/cell viability and induction of apoptosis. Immunoblot analysis revealed that PFE treatment of PC3 cells resulted in (i) induction of Bax and Bak (proapoptotic); (ii) down-regulation of Bcl-X(L) and Bcl-2 (antiapoptotic); (iii) induction of WAF1/p21 and KIP1/p27; (iv) a decrease in cyclins D1, D2, and E; and (v) a decrease in cyclin-dependent kinase (cdk) 2, cdk4, and cdk6 expression. These data establish the involvement of the cyclin kinase inhibitor-cyclin-cdk network during the antiproliferative effects of PFE. Oral administration of PFE (0.1% and 0.2%, wt/vol) to athymic nude mice implanted with androgen-sensitive CWR22Rnu1 cells resulted in a significant inhibition in tumor growth concomitant with a significant decrease in serum prostate-specific antigen levels. We suggest that pomegranate juice may have cancer-chemopreventive as well as cancer-chemotherapeutic effects against prostate cancer in humans.
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PMID:Pomegranate fruit juice for chemoprevention and chemotherapy of prostate cancer. 1619 56

Intracellular signaling molecules and apoptotic factors seem to play an important role in determining the radiation response of tumor cells. However, the basis for the link between signaling pathway and apoptotic cell death machinery after ionizing irradiation remains still largely unclear. In this study, we showed that c-Abl-PKCdelta-Rac1-p38 MAPK signaling is required for the conformational changes of Bak and Bax during ionizing radiation-induced apoptotic cell death in human non-small cell lung cancer cells. Ionizing radiation induced conformational changes and subsequent oligomerizations of Bak and Bax, dissipation of mitochondrial membrane potential, and cytochrome c release from mitochondria. Small interference (siRNA) targeting of Bak and Bax effectively protected cells from radiation-induced mitochondrial membrane potential loss and apoptotic cell death. p38 MAPK was found to be selectively activated in response to radiation treatment. Inhibition of p38 MAPK completely suppressed radiation-induced Bak and Bax activations, dissipation of mitochondrial membrane potential, and cell death. Moreover, expression of a dominant negative form of protein kinase Cdelta (PKCdelta) or siRNA targeting of PKCdelta attenuated p38 MAPK activation and conformational changes of Bak and Bax. In addition, ectopic expression of RacN17, a dominant negative form of Rac1, markedly inhibited p38 MAPK activation but did not affect PKCdelta activation. Upon stimulation of cells with radiation, PKCdelta was phosphorylated dramatically on tyrosine. c-Abl-PKCdelta complex formation was also increased in response to radiation. Moreover, siRNA targeting of c-Abl attenuated radiation-induced PKCdelta and p38 MAPK activations, and Bak and Bax modulations. These data support a notion that activation of the c-Abl-PKCdelta-Rac1-p38 MAPK pathway in response to ionizing radiation signals conformational changes of Bak and Bax, resulting in mitochondrial activation-mediated apoptotic cell death in human non-small cell lung cancer cells.
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PMID:Activation of Bak and Bax through c-abl-protein kinase Cdelta-p38 MAPK signaling in response to ionizing radiation in human non-small cell lung cancer cells. 1641 Feb 45

Rosmarinic acid (RosA), frequently found as a secondary metabolite in herbs and medicinal plants, has exhibited antioxidative and anti-inflammatory activities. RosA was shown to inhibit the proliferation and induce apoptosis of Jurkat T cells but the mechanism of action of RosA in apoptosis remains elusive. RosA inhibited the proliferation of Jurkat cells in a dose-dependent manner by suppressing the expression of cyclin D3 and p21(Cip1/Waf1) and up-regulating p27(Kip1). RosA induced apoptosis of Jurkat cells in a dose-dependent manner and failed to protect them from hydrogen peroxide (H2O2)-mediated apoptosis. Induction of apoptosis by RosA correlated with suppression of Bcl-2 but not of Bak or PUMA. Overexpression of Bcl-2 protected Jurkat cells from both H2O2- and RosA-induced apoptosis by altering the ratio of anti- to pro-apoptotic members of the Bcl-2 family. In conclusion, RosA inhibited Jurkat cell proliferation by altering the expression of cyclins and cyclin-dependent kinase inhibitors and induced apoptosis most likely acting through the mitochondrial pathway and possessed no anti-oxidant properties.
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PMID:Rosmarinic acid failed to suppress hydrogen peroxide-mediated apoptosis but induced apoptosis of Jurkat cells which was suppressed by Bcl-2. 1653 55

The Bcl-2 antagonist ABT-737 targets Bcl-2/Bcl-xL but not Mcl-1, which may confer resistance to this novel agent. Here, we show that Mcl-1 down-regulation by the cyclin-dependent kinase (CDK) inhibitor roscovitine or Mcl-1-shRNA dramatically increases ABT-737 lethality in human leukemia cells. ABT-737 induces Bax conformational change but fails to activate Bak or trigger Bax translocation. Coadministration of roscovitine and ABT-737 untethers Bak from Mcl-1 and Bcl-xL, respectively, triggering Bak activation and Bax translocation. Studies employing Bax and/or Bak knockout mouse embryonic fibroblasts (MEFs) confirm that Bax is required for ABT-737+/-roscovitine lethality, whereas Bak is primarily involved in potentiation of ABT-737-induced apoptosis by Mcl-1 down-regulation. Ectopic Mcl-1 expression attenuates Bak activation and apoptosis by ABT-737+roscovitine, whereas cells overexpressing Bcl-2 or Bcl-xL remain fully sensitive. Finally, Mcl-1 knockout MEFs are extremely sensitive to Bak conformational change and apoptosis induced by ABT-737, effects that are not potentiated by roscovitine. Collectively, these findings suggest down-regulation of Mcl-1 by either CDK inhibitors or genetic approaches dramatically potentiate ABT-737 lethality through cooperative interactions at two distinct levels: unleashing of Bak from both Bcl-xL and Mcl-1 and simultaneous induction of Bak activation and Bax translocation. These findings provide a mechanistic basis for simultaneously targeting Mcl-1 and Bcl-2/Bcl-xL in leukemia.
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PMID:Mcl-1 down-regulation potentiates ABT-737 lethality by cooperatively inducing Bak activation and Bax translocation. 1723 90

Epidemiological data suggest that epigallocatechin-3-gallate (EGCG) possesses chemopreventive properties against cancer. In this study, we examined the molecular mechanisms of EGCG in human pancreatic cancer cells. EGCG caused growth arrest at G1 stage of cell cycle through regulation of cyclin D1, cdk4, cdk6, p21/WAF1/CIP1 and p27/KIP1, and induced apoptosis through generation of reactive oxygen species and activation of caspase-3 and caspase-9. EGCG inhibited expressions of Bcl-2 and Bcl-XL and induced expressions of Bax, Bak, Bcl-XS and PUMA. Mouse embryonic fibroblasts (MEFs) derived from Bax and Bak double knockout mice exhibited greater protection against EGCG-induced apoptosis than wild-type or single knockout MEFs. EGCG caused Bax activation in p53 -/- MEFs, suggesting that EGCG can induce apoptosis in the absence of p53. Furthermore, the activities of Ras, Raf-1 and ERK1/2 were inhibited, whereas the activities of MEKK1, JNK1/2 and p38 MAP kinases were induced by EGCG. Inhibition of cRaf-1 or ERK enhanced EGCG-induced apoptosis, whereas inhibition of JNK or p38 MAP kinase inhibited EGCG-induced apoptosis. EGCG inhibited the activation of p90 ribosomal protein S6 kinase, and induced the activation of cJUN. Our results suggest that EGCG induces growth arrest and apoptosis through multiple mechanisms, and can be used for pancreatic cancer prevention.
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PMID:Epigallocatechin-3-gallate inhibits cell cycle and induces apoptosis in pancreatic cancer. 1756 28


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