Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.62 (caspase-9)
 7,507 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have examined the effects of the CDK1 inhibitor CGP74514A on cell cycle- and apoptosis-related events in human leukemia cells. An 18-hr exposure to 5 microM CGP74514A induced mitochondrial damage (i.e., loss of Delta psi(m)) and apoptosis in multiple human leukemia cell lines (e.g., U937, HL-60, KG-1, CCRF-CEM, Raji, and THP; range 30-95%). In U937 cells, CGP74514A- induced apoptosis (5 microM) became apparent within 4 hr and approached 100% by 24 hr. The pan- caspase inhibitor Boc-fmk and the caspase-8 inhibitor lETD-fmk opposed CGP74514A-induced caspase-9 activation and PARP degradation, but not cytochrome c or Smac/DIABLO release. CGP74514A-mediated apoptosis was substantially blocked by ectopic expression of full-length Bel- 2, a loop-deleted mutant Bcl-2, and Bcl-x(L). CGP74514A treatment (5 microM; 18 hr) resulted in increased p21(CIP1) expression, p27(KIP1) degradation, diminished E2F1 expression, and dephosphorylation of p34(CDC2). It also induced early (i.e., within 2 hr) inhibition of CDK1 activity and dephosphorylation of pRb, followed by pRb degradation, but did not block pRb phosphorylation at CDK2- and CDK4- specific sites. These findings indicate that the selective CDK1 inhibitor, CGP74514A, induces complex changes in cell cycle-related proteins in human leukemia cells accompanied by extensive mitochondrial damage, caspase activation, and apoptosis.
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PMID:Induction of apoptosis in human leukemia cells by the CDK1 inhibitor CGP74514A. 1242 20

Previously, we showed that sulforaphane (SFN), a naturally occurring cancer chemopreventive agent, effectively inhibits proliferation of PC-3 human prostate cancer cells by causing caspase-9- and caspase-8-mediated apoptosis. Here, we demonstrate that SFN treatment causes an irreversible arrest in the G(2)/M phase of the cell cycle. Cell cycle arrest induced by SFN was associated with a significant decrease in protein levels of cyclin B1, cell division cycle (Cdc) 25B, and Cdc25C, leading to accumulation of Tyr-15-phosphorylated (inactive) cyclin-dependent kinase 1. The SFN-induced decline in Cdc25C protein level was blocked in the presence of proteasome inhibitor lactacystin, but lactacystin did not confer protection against cell cycle arrest. Interestingly, SFN treatment also resulted in a rapid and sustained phosphorylation of Cdc25C at Ser-216, leading to its translocation from the nucleus to the cytoplasm because of increased binding with 14-3-3beta. Increased Ser-216 phosphorylation of Cdc25C upon treatment with SFN was the result of activation of checkpoint kinase 2 (Chk2), which was associated with Ser-1981 phosphorylation of ataxia telangiectasia-mutated, generation of reactive oxygen species, and Ser-139 phosphorylation of histone H2A.X, a sensitive marker for the presence of DNA double-strand breaks. Transient transfection of PC-3 cells with Chk2-specific small interfering RNA duplexes significantly attenuated SFN-induced G(2)/M arrest. HCT116 human colon cancer-derived Chk2(-/-) cells were significantly more resistant to G(2)/M arrest by SFN compared with the wild type HCT116 cells. These findings indicate that Chk2-mediated phosphorylation of Cdc25C plays a major role in irreversible G(2)/M arrest by SFN. Activation of Chk2 in response to DNA damage is well documented, but the present study is the first published report to link Chk2 activation to cell cycle arrest by an isothiocyanate.
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PMID:Sulforaphane-induced G2/M phase cell cycle arrest involves checkpoint kinase 2-mediated phosphorylation of cell division cycle 25C. 1507 69

Phenethyl isothiocyanate (PEITC), a constituent of many cruciferous vegetables, offers significant protection against cancer in animals induced by a variety of carcinogens. The present study demonstrates that PEITC suppresses proliferation of PC-3 cells in a dose-dependent manner by causing G(2)-M-phase cell cycle arrest and apoptosis. Interestingly, phenyl isothiocyanate (PITC), which is a structural analogue of PEITC but lacks the -CH(2) spacers that link the aromatic ring to the -N=C=S group, neither inhibited PC-3 cell viability nor caused cell cycle arrest or apoptosis. These results indicated that even a subtle change in isothiocyanate (ITC) structure could have a significant impact on its biological activity. The PEITC-induced cell cycle arrest was associated with a >80% reduction in the protein levels of cyclin-dependent kinase 1 (Cdk1) and cell division cycle 25C (Cdc25C; 24 h after treatment with 10 micro M PEITC), which led to an accumulation of Tyr(15) phosphorylated (inactive) Cdk1. On the other hand, PITC treatment neither reduced protein levels of Cdk1 or Cdc25C nor affected Cdk1 phosphorylation. The PEITC-induced decline in Cdk1 and Cdc25C protein levels and cell cycle arrest were significantly blocked on pretreatment of PC-3 cells with proteasome inhibitor lactacystin. A 24 h exposure of PC-3 cells to 10 micro M PEITC, but not PITC, resulted in about 56% and 44% decrease in the levels of antiapoptotic proteins Bcl-2 and Bcl-X(L), respectively. However, ectopic expression of Bcl-2 failed to alter sensitivity of PC-3 cells to growth inhibition or apoptosis induction by PEITC. Treatment of cells with PEITC, but not PITC, also resulted in cleavage of procaspase-3, procaspase-9, and procaspase-8. Moreover, the PEITC-induced apoptosis was significantly attenuated in the presence of general caspase inhibitor and specific inhibitors of caspase-8 and caspase-9. In conclusion, our data indicate that PEITC-induced cell cycle arrest in PC-3 cells is likely due to proteasome-mediated degradation of Cdc25C and Cdk1, and ectopic expression of Bcl-2 fails to confer resistance to PEITC-induced apoptosis. Furthermore, the results of the present study point toward involvement of both caspase-8- and caspase-9-mediated pathways in apoptosis induction by PEITC.
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PMID:Proteasome-mediated degradation of cell division cycle 25C and cyclin-dependent kinase 1 in phenethyl isothiocyanate-induced G2-M-phase cell cycle arrest in PC-3 human prostate cancer cells. 1514 Oct 14

4-oxo-N-(4-hydroxyphenyl)retinamide (4-oxo-4-HPR) is a recently identified metabolite of fenretinide (4-HPR). We explored the effectiveness of 4-oxo-4-HPR in inducing cell growth inhibition in ovarian, breast, and neuroblastoma tumor cell lines; moreover, we investigated the molecular events mediating this effect in two ovarian carcinoma cell lines, one sensitive (A2780) and one resistant (A2780/HPR) to 4-HPR. 4-oxo-4-HPR was two to four times more effective than 4-HPR in most cell lines, was effective in both 4-HPR-sensitive and 4-HPR-resistant cells, and, in combination with 4-HPR, caused a synergistic effect. The tumor growth-inhibitory effects of 4-oxo-4-HPR seem to be independent of nuclear retinoid receptors (RAR), as indicated by the failure of RAR antagonists to inhibit its effects and by its poor ability to bind and transactivate RARs. Unlike 4-HPR, which only slightly affected the G(1) phase of the cell cycle, 4-oxo-4-HPR caused a marked accumulation of cells in G(2)-M. This effect was associated with a reduction in the expression of regulatory proteins of G(2)-M (cyclin-dependent kinase 1 and cdc25c) and S (cyclin A) phases, and with an increase in the expression of apoptosis-related proteins, such as p53 and p21. Apoptosis was induced by 4-oxo-4-HPR in both 4-HPR-sensitive and 4-HPR-resistant cells and involved activation of caspase-3 and caspase-9 but not caspase-8. We also showed that 4-oxo-4-HPR, similarly to 4-HPR, increased reactive oxygen species generation and ceramide levels by de novo synthesis. In conclusion, 4-oxo-4-HPR is an effective 4-HPR metabolite that might act as therapeutic agent per se and, when combined with 4-HPR, might improve 4-HPR activity or overcome 4-HPR resistance.
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PMID:4-oxo-fenretinide, a recently identified fenretinide metabolite, induces marked G2-M cell cycle arrest and apoptosis in fenretinide-sensitive and fenretinide-resistant cell lines. 1654 Jun 76

Epidemiologic studies have revealed an inverse correlation between dietary intake of cruciferous vegetables and the risk of breast cancer. We now show that cruciferous vegetable constituent benzyl isothiocyanate (BITC) effectively suppresses growth of cultured human breast cancer cells (MDA-MB-231 and MCF-7) by causing G(2)-M phase cell cycle arrest and apoptosis induction. On the other hand, a normal mammary epithelial cell line (MCF-10A) is significantly more resistant to growth arrest and apoptosis by BITC compared with breast cancer cells. The BITC-mediated cell cycle arrest was associated with a decrease in levels of proteins involved in regulation of G(2)-M transition, including cyclin B1, cyclin-dependent kinase 1, and cell division cycle 25C. The BITC-induced apoptosis correlated with induction of proapoptotic proteins Bax (MCF-7) and Bak (MDA-MB-231 and MCF-7) and down-regulation of antiapoptotic proteins Bcl-2 and Bcl-xL (MDA-MB-231). The SV40-immortalized mouse embryonic fibroblasts derived from Bax and Bak double knockout mice were significantly more resistant to BITC-induced DNA fragmentation compared with wild-type mouse embryonic fibroblasts. The BITC treatment caused rapid disruption of the mitochondrial membrane potential, leading to cytosolic release of apoptogenic molecules, which was accompanied by formation of autophagosome-like structures as revealed by transmission electron microscopy. The BITC-mediated apoptosis was associated with generation of reactive oxygen species and cleavage of caspase-9, caspase-8, and caspase-3. Apoptosis induction by BITC was significantly attenuated in the presence of a combined superoxide dismutase and catalase mimetic EUK134 as well as caspase inhibitors. In conclusion, the present study reveals a complex signaling leading to growth arrest and apoptosis induction by BITC.
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PMID:Benzyl isothiocyanate-induced apoptosis in human breast cancer cells is initiated by reactive oxygen species and regulated by Bax and Bak. 1712 41

We recently reported that gallic acid is a major active agent responsible for grape seed extract activity in DU145 human prostate carcinoma cells. The present study was conducted to examine its efficacy and associated mechanism. Gallic acid treatment of DU145 cells resulted in a strong cell growth inhibition, cell cycle arrest, and apoptotic death in a dose- and time-dependent manner, together with a decrease in cyclin-dependent kinases and cyclins but strong induction in Cip1/p21. Additional mechanistic studies showed that gallic acid induces an early Tyr(15) phosphorylation of cell division cycle 2 (cdc2). Further upstream, gallic acid also induced phosphorylation of both cdc25A and cdc25C via ataxia telangiectasia mutated (ATM)-checkpoint kinase 2 (Chk2) activation as a DNA damage response evidenced by increased phospho-histone 2AX (H2A.X) that is phosphorylated by ATM in response to DNA damage. Time kinetics of ATM phosphorylation, together with those of H2A.X and Chk2, was in accordance with an inactivating phosphorylation of cdc25A and cdc25C phosphatases and cdc2 kinase, suggesting that gallic acid increases cdc25A/C-cdc2 phosphorylation and thereby inactivation via ATM-Chk2 pathway following DNA damage that induces cell cycle arrest. Caffeine, an ATM/ataxia telangiectasia-rad3-related inhibitor, reversed gallic acid-caused ATM and H2A.X phosphorylation and cell cycle arrest, supporting the role of ATM pathway in gallic acid-induced cell cycle arrest. Additionally, gallic acid caused caspase-9, caspase-3, and poly(ADP)ribose polymerase cleavage, but pan-caspase inhibitor did not reverse apoptosis, suggesting an additional caspase-independent apoptotic mechanism. Together, this is the first report identifying gallic acid efficacy and associated mechanisms in an advanced and androgen-independent human prostate carcinoma DU145 cells, suggesting future in vivo efficacy studies with this agent in preclinical prostate cancer models.
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PMID:Gallic acid causes inactivating phosphorylation of cdc25A/cdc25C-cdc2 via ATM-Chk2 activation, leading to cell cycle arrest, and induces apoptosis in human prostate carcinoma DU145 cells. 1717 33

Non-small cell lung cancer (NSCLC) with activating mutations in the epidermal growth factor receptor (EGFR) responds to EGFR tyrosine kinase inhibitors such as erlotinib. However, secondary somatic EGFR mutations (e.g., T790M) confer resistance to erlotinib. BMS-690514, a novel panHER/vascular endothelial growth factor receptor (VEGFR) inhibitor described here, exerted antiproliferative and proapoptotic effects on NSCLC cell lines, with prominent efficacy on H1975 cells expressing the T790M mutation. In this model, BMS-690514 induced a G(1) cell cycle arrest, as well as ultrastructural hallmarks of apoptosis, mitochondrial release of cytochrome c, and activation of caspases involved in the intrinsic (e.g., caspase-2, caspase-3, caspase-7, and caspase-9), but not in the extrinsic (e.g., caspase-8), pathway. Caspase inhibition conferred partial protection against BMS-690514 cytotoxicity, pointing to the involvement of both caspase-dependent and caspase-independent effector mechanisms. Transcriptome analyses revealed the up-regulation of proapoptotic (e.g., Bim, Puma) and cell cycle inhibitory (e.g., p27(Kip1), p57(Kip2)) factors, as well as the down-regulation of antiapoptotic (e.g., Mcl1), heat shock (e.g., HSP40, HSP70, HSP90), and cell cycle promoting [e.g., cyclins B1, D1, and D3; cyclin-dependent kinase 1 (CDK1); MCM family proteins; proliferating cell nuclear antigen (PCNA)] proteins. BMS-690514-induced death of H1975 cells was modified in a unique fashion by a panel of small interfering RNAs targeting apoptosis modulators. Down-regulation of components of the nuclear factor-kappaB survival pathway (e.g., p65, Nemo/IKK gamma, TAB2) sensitized cells to BMS-690514, whereas knockdown of proapoptotic factors (e.g., Puma, Bax, Bak, caspase-2, etc.) and DNA damage-related proteins (e.g., ERCC1, hTERT) exerted cytoprotective effects. BMS-690514 is a new pan-HER/VEGFR inhibitor that may become an alternative to erlotinib for the treatment of NSCLC.
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PMID:A novel epidermal growth factor receptor inhibitor promotes apoptosis in non-small cell lung cancer cells resistant to erlotinib. 1761 83

Glioblastoma is the most malignant and prevalent brain tumor in humans. It is composed of heterogenic abnormal astroglial cells that avoid differentiation, maintain proliferation, and hardly commit apoptosis. N-(4-Hydroxyphenyl)retinamide (4-HPR) induced astrocytic differentiation and increased sensitivity to interferon-gamma (IFN-gamma) for apoptosis in human glioblastoma A172, LN18, and SNB19 cells. Combination of 4-HPR and IFN-gamma significantly inhibited human telomerase reverse transcriptase (hTERT), cyclin dependent kinase 2 (CDK2), and survivin to up-regulate caspase-8, caspase-9, and caspase-3 for increasing apoptosis in all glioblastoma cell lines. Hence, combination of 4-HPR and IFN-gamma should be considered for controlling growth of different human glioblastoma cells.
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PMID:N-(4-Hydroxyphenyl)retinamide induced differentiation with repression of telomerase and cell cycle to increase interferon-gamma sensitivity for apoptosis in human glioblastoma cells. 1816 43

The seed of Strychnos nux-vomica (Loganiaceae) has been used in traditional Oriental medicine as a folk remedy for the treatment of cancer. However, the mechanism responsible for the anticancer effects of Strychni Semen is not clearly understood. The study tested whether and how the water extract of Strychni Semen (ESS) treatment would affect the growth of AGS human gastric carcinoma cells. ESS was found to inhibit the growth of AGS cells in a concentration-dependent manner. Cell cycle analysis showed G2/M phase arrest and apoptosis in AGS cells following ESS treatment. ESS-mediated G2/M arrest was found to be associated with up-regulation of cyclin A, Cdc2, tumor suppressor p53 and cyclin dependent kinase (Cdk) inhibitor p21(WAF1/CIP1), whereas the expressions of other G2/M regulatory proteins, including cyclin B1 and Cdk2, were down-regulated compared with the control. The induction of apoptotic cell death by ESS was associated with down-regulation of anti-apoptotic Bcl-2 and up-regulation of pro-apoptotic Bax expression. Further results indicate that caspase-3, caspase-8 and caspase-9 are all activated by ESS, together with cleavage of downstream caspase-3 target proteins. Taken together, the results of this study suggest the involvement of multiple signaling pathways targeted by ESS in mediating G2/M cell cycle arrest and apoptosis in AGS cells, and warrant further investigation.
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PMID:Induction of G2/M arrest and apoptosis by water extract of Strychni Semen in human gastric carcinoma AGS cells. 1844 45

The antiproliferative and apoptotic effects of cucurbitacin E, a natural product isolated from Cucurbitaceae, were determined in human leukemia HL-60 cells. Cucurbitacin E at low concentrations (3-50 nmol/l) inhibited the growth of HL-60 cells, which was associated with G2/M cell-cycle arrest, decrease in the levels of cyclin-dependent kinase1, and increase in the levels of p21. Cucurbitacin E at high concentrations (1-10 mol/l) induced apoptosis of HL-60 cells and activation of caspase-3, caspase-8, and caspase-9. Jurkat leukemia cells with or without caspase-8 expression were nearly equally sensitive to cucurbitacin E-induced apoptosis. Cucurbitacin E did not increase the levels of reactive oxygen species and antioxidants, N-acetylcysteine and catalase, did not block cucurbitacin E-induced apoptosis. Cucurbitacin E decreased the levels of the antiapoptotic proteins XIAP, survivin, and Mcl-1, but increased the level of the proapoptotic protein, Bax. The levels of phosphorylated eukaryotic translation initiation factor 2 subunit (eIF2) were induced in cells undergoing both apoptosis and cell-cycle arrest. As phosphorylated eIF2 is an inhibitor of protein translation initiation, our data suggest that cucurbitacin E induces cell growth arrest and apoptosis through the induction of eIF2 phosphorylation, which leads to the inhibition of cyclin-dependent kinase 1, Mcl-1, survivin, and/or XIAP protein synthesis and that cucurbitacin E induces apoptosis mainly through a mitochondrial-mediated pathway.
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PMID:The induction of G2/M cell-cycle arrest and apoptosis by cucurbitacin E is associated with increased phosphorylation of eIF2alpha in leukemia cells. 2011 Aug 7


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