Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously shown that the leukotriene B4 receptor antagonist, LY293111 inhibits proliferation and induces apoptosis in human pancreatic cancer cells both in vitro and in vivo. In the current study, we investigated the molecular mechanisms of LY293111-induced apoptosis and cell cycle arrest. Two human pancreatic cancer cell lines were used in this study, MiaPaCa-2 and AsPC-1. Cell cycle analysis by flow cytometry showed a dramatic increase in the percentage of apoptotic cells as well as S-phase arrest after treatment with 250 nmol/l LY293111 for up to 48 h. Western blotting indicated that LY293111 treatment induced cytochrome c release from the mitochondria into the cytosol, accompanied by caspase-9, caspase-7 and caspase-3 activation, and cleavage of poly ADP-ribose polymerase. Caspase-8 was not activated by LY293111. A decrease was found in the expression of the antiapoptotic proteins, Bcl-2 and Mcl-1, and an increase in the proapoptotic protein, Bax. LY293111 reduced the expression of CDK2, cyclin A and cyclin E, consistent with the S-phase arrest observed in these cells. The expression of cyclin-dependent kinase inhibitors, p21 and p27 was not affected by LY293111 treatment. In conclusion, LY293111 induces apoptosis in human pancreatic cancer cells through the mitochondria-mediated pathway. LY293111 also induces S-phase arrest with downregulation of CDK2, cyclin A and cyclin E. Blockade of leukotriene B4 metabolic pathway may provide a novel treatment for human pancreatic cancer.
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PMID:Leukotriene B4 receptor antagonist LY293111 induces S-phase cell cycle arrest and apoptosis in human pancreatic cancer cells. 1741 22

Dietary grape seed proanthocyanidins (GSPs) prevent photocarcinogenesis in mice. Here, we report that in vitro treatment of human epidermoid carcinoma A431 cells with GSPs inhibited cellular proliferation (13-89%) and induced cell death (1-48%) in a dose (5-100 mug/ml)- and time (24, 48 and 72 h)-dependent manner. GSP-induced inhibition of cell proliferation was associated with an increase in G1-phase arrest at 24 h, which was mediated through the inhibition of cyclin-dependent kinases (Cdk) Cdk2, Cdk4, Cdk6 and cyclins D1, D2 and E and simultaneous increase in protein expression of cyclin-dependent kinase inhibitors (Cdki), Cip1/p21 and Kip1/p27, and enhanced binding of Cdki-Cdk. The treatment of A431 cells with GSPs (20-80 mug/ml) resulted in a dose-dependent increase in apoptotic cell death (26-58%), which was associated with an increased protein expression of proapoptotic Bax, decreased expression of antiapoptotic Bcl-2 and Bcl-xl, loss of mitochondrial membrane potential, and cleavage of caspase-9, caspase-3 and PARP. Pretreatment with the pan-caspase inhibitor (z-VAD-fmk) blocked the GSP-induced apoptosis in A431 cells suggesting that GSP-induced apoptosis is associated primarily with the caspase-3-dependent pathway. Together, our study suggests that GSPs possess chemotherapeutic potential against human epidermoid carcinoma cells in vitro, further in vivo mechanistic studies are required to verify the chemotherapeutic effect of GSPs in skin cancers.
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PMID:Grape seed proanthocyanidins promote apoptosis in human epidermoid carcinoma A431 cells through alterations in Cdki-Cdk-cyclin cascade, and caspase-3 activation via loss of mitochondrial membrane potential. 1743 83

The IFN-induced double-stranded RNA-dependent protein kinase (PKR) is one of the four mammalian serine-threonine kinases (the three others being HRI, GCN2 and PERK) that phosphorylate the eIF2 alpha translation initiation factor, in response to stress signals, mainly as a result of viral infections. eIF2 alpha phosphorylation results in arrest of translation of both cellular and viral mRNAs, an efficient way to inhibit virus replication. The particularity of PKR is to activate by binding to dsRNA through two N terminal dsRNA binding motifs (dsRBM). PKR activation during a viral infection represents a threat for several viruses, which have therefore evolved to express PKR inhibitors, such as the Vaccinia E3L and K3L proteins. The function of PKR can also be regulated by cellular proteins, either positively (RAX/PACT; Mda7) or negatively (p58IPK, TRBP, nucleophosmin, Hsp90/70). PKR can provoke apoptosis, in part through its ability to control protein translation, but the situation appears to be more complex, as NF-kappaB, ATF-3 and p53 have also been implicated. PKR-induced apoptosis involves mainly the FADD/caspase 8 pathway, while the mitochondrial APAF/caspase 9 pathway is also engaged. As a consequence of the effects of PKR on translation, transcription and apoptosis, PKR can function to control cell growth and cell differentiation, and its activity can be controlled by the action of several oncogenes.
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PMID:The dsRNA protein kinase PKR: virus and cell control. 1745 62

The p57(Kip2) gene belongs to the Cip/Kip family of cyclin-dependent kinase (CDK) inhibitors and has been suggested to be a tumor suppressor gene, being inactivated in various types of human cancers. However, little is known concerning p57(Kip2) possible interplay with the apoptotic cell death machinery and its possible implication for cancer. Here, we report that selective p57(Kip2) expression sensitizes cancer cells to apoptotic agents such as cisplatin, etoposide and staurosporine (STS) via a mechanism, which does not require p57(Kip2)-mediated inhibition of CDK. Translocation of p57(Kip2) to mitochondria occurs within 20 min after STS application. In fact, p57(Kip2) primarily promotes the intrinsic apoptotic pathways, favoring Bax activation and loss of mitochondrial transmembrane potential, consequent release of cytochrome-c into cytosol, caspase-9 and caspase-3 activation. In accordance, Bcl2 overexpression or voltage-dependent anion channel (VDAC) inhibition is able to inhibit p57(Kip2) cell death promoting effect. Thus, in addition to its established function in control of proliferation, these results reveal a mechanism whereby p57(Kip2) influences the mitochondrial apoptotic cell death pathway in cancer cells.
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PMID:The cell cycle inhibitor p57(Kip2) promotes cell death via the mitochondrial apoptotic pathway. 1746 23

Multimodal therapies play important roles in the treatment of osteosarcoma (OS) and Ewing's family of tumors (EFTs), two most frequent malignant bone tumors. Although the clinical outcome of primary OS and EFTs is greatly improved, the relapsed cases often are associated with multidrug resistance of the tumors and the prognosis of these patients is still poor. Flavopiridol, a pan cyclin-dependent kinase (CDK) inhibitor is a novel antitumor agent that can induce cell cycle arrest and apoptosis in many cancer cells. However, there have been no studies about the effects of flavopiridol on drug-resistant OS and EFTs. Here, we demonstrated that flavopiridol induced the cleavage of poly-ADP-ribose polymerase (PARP) in a time and dose dependent manner in adriamycin-resistant OS and EFTs cells expressing P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP(1)) as effectively as in their parental cells. Our data also showed that flavopiridol caused the release of mitochondrial cytochrome c and the activation of caspase-9, caspase-8 and caspase-3, with an increase ratio of the proapoptotic protein level (Bax) to the antiapoptotic protein level (Bcl-2 and Bcl-X(L)), while apoptosis was inhibited by pan caspase inhibitor (Z-VAD-FMK) and caspase-3 inhibitor (Z-DEVD-FMK), not by caspase-8 inhibitor (Z-IETD-FMK). The treatment with flavopiridol further inhibited the tumor growth in mouse models of the drug-resistant OS and EFTs. These results suggest that flavopiridol might be promising in clinical therapy for the relapsed OS and EFTs.
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PMID:Cyclin-dependent kinase inhibitor, flavopiridol, induces apoptosis and inhibits tumor growth in drug-resistant osteosarcoma and Ewing's family tumor cells. 1752 Jun 76

In the rodent cerebellum, PACAP is expressed by Purkinje neurons and PAC1 receptors are present on granule cells during both the development period and in adulthood. Treatment of granule neurons with PACAP inhibits proliferation, slows migration, promotes survival and induces differentiation. PACAP also protects cerebellar granule cells against the deleterious effects of neurotoxic agents. Most of the neurotrophic effects of PACAP are mediated through the cAMP/PKA signaling pathway and often involve the ERK MAPkinase. Caspase-3 is one of the key enzymes implicated in the neuroprotective action of PACAP but PACAP also inhibits caspase-9 activity and increases Bcl-2 expression. PACAP and functional PAC1 receptors are expressed in the monkey and human cerebellar cortex with a pattern of expression very similar to that described in rodents, suggesting that PACAP could also exert neurodevelopmental and neuroprotective functions in the cerebellum of primates including human.
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PMID:Neurotrophic effects of PACAP in the cerebellar cortex. 1754 70

In humans, the molecular mechanisms underlying ovarian follicle endowment and activation, which are closely related to the control of female reproduction, occurrence of menopause, and related diseases such as premature ovarian failure, are poorly understood. In the current study, we provide several lines of genetic evidence that the cyclin-dependent kinase (Cdk) inhibitor 1B (commonly known as p27(kip1) or p27) controls ovarian development in mice by suppressing follicle endowment and activation, and by promoting follicle death. In p27-deficient (p27(-/-)) mice, postnatal follicle assembly was accelerated, and the number of endowed follicles was doubled as compared with p27(+/+) mice. Moreover, in p27(-/-) ovaries the primordial follicle pool was prematurely activated once it was endowed, and at the same time the massive follicular death that occurs before sexual maturity was rescued by loss of p27. In early adulthood, however, the overactivated follicular pool in p27(-/-) ovaries was largely depleted, causing premature ovarian failure. Furthermore, we have extensively studied the molecular mechanisms underlying the above-mentioned phenotypes seen in p27(-/-) ovaries and have found that p27 controls follicular development by several distinct mechanisms at different stages of development of the ovary. For example, p27 controls oocyte growth by suppressing the functions of Cdk2/Cdc2-cyclin A/E1 in oocytes that are arrested at the diplotene stage of meiosis I. This function of p27 is distinct from its well-known role as a suppressor of cell cycle progression. In addition, we have found that p27 activates the caspase-9-caspase-3-caspase-7-poly (ADP-ribose) polymeraseapoptotic cascade by inhibiting Cdk2/Cdc2-cyclin A/B1 kinase activities in follicles, thereby inducing follicle atresia. Our results suggest that the p27 gene is important in determining mammalian ovarian development. This study therefore provides insight into ovary-borne genetic aberrations that cause defects in folliculogenesis and infertility in humans.
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PMID:p27kip1 (cyclin-dependent kinase inhibitor 1B) controls ovarian development by suppressing follicle endowment and activation and promoting follicle atresia in mice. 1756 40

The MYC oncogene is frequently deregulated in human tumors, indicative of a poor prognosis because of enhanced resistance to treatment. In such cases, the cellular sensitivity to chemotherapy could be restored by reactivation of Myc-driven apoptosis. We have analyzed apoptosis induced by the cytotoxic agents camptothecin (CPT) and paclitaxel (PTX) using Rat1 fibroblasts with different c-myc status and human Tet21N neuroblastoma cells with conditional MYCN expression. In these cell lines, the drug sensitivity was enhanced by Myc in line with previous reports showing that Myc sensitizes to apoptosis induction by many different apoptosis inducers. CPT-induced apoptosis involved cleavage and activation of proapoptotic Bid and Bax, induction of mitochondrial membrane depolarization, activation of caspase-9 and caspase-3, protein kinase c delta (PKCdelta) signaling and upregulation of p53. We also observed reduced transcriptional activity by Myc and other transcription factors in response to CPT. In contrast, the manner by which Myc potentiates the apoptosis induced by PTX differs from that of CPT and remains to be explored. In summary, our findings revealed that activation of PKCdelta in response to CPT treatment requires Myc and is important in CPT-mediated apoptosis signaling.
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PMID:Camptothecin-induced apoptosis is enhanced by Myc and involves PKCdelta signaling. 1756 38

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

Glioblastoma is the deadliest and most prevalent brain tumor, which is not yet amenable to any treatments. Therefore, new and innovative therapeutic strategies need to be developed for treating this deadly disease. We found that all-trans retinoic acid (ATRA) or 13-cis retinoic acid (13-CRA) induced astrocytic differentiation with down regulation of telomerase activity in rat glioblastoma C6 cells and enhanced sensitivity of the cells to interferon-gamma (IFN-gamma) or taxol (TXL) for apoptosis. Sensitivity of differentiated cells to IFN-gamma or TXL was greatly increased for apoptosis with increases in calcineurin expression, Bax:Bcl-2 ratio, mitochondrial release of cytochrome c, and expression and activity of calpain and caspases. Treatment with IFN-gamma activated caspase-8 indicating induction of apoptosis via the receptor-mediated pathway. Notably, IFN-gamma activated the signal transducer and activator of transcription-1 (STAT-1) for signaling via binding to gamma activator sequence (GAS), whereas TXL activated Raf-1 kinase for inactivation of Bcl-2 by its phosphorylation. We confirmed involvement of different proteolytic mechanisms in cell death by pretreating the cells with caspase-8 inhibitor II, calpeptin (calpain inhibitor), and caspase-9 inhibitor I, and caspase-3 inhibitor IV. Results demonstrated that retinoids induced astrocytic differentiation with down regulation of telomerase activity and worked synergistically to enhance sensitivity of cells to the cytotoxic agent IFN-gamma and the cytostatic agent TXL for apoptosis. This combination therapy for differentiation and apoptosis could be highly effective for controlling the malignant growth of glioblastoma.
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PMID:Differentiation decreased telomerase activity in rat glioblastoma C6 cells and increased sensitivity to IFN-gamma and taxol for apoptosis. 1769 33


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