scholarly journals The apoptosome molecular timer synergises with XIAP to suppress apoptosis execution and contributes to prognosticating survival in colorectal cancer

2020 ◽  
Vol 27 (10) ◽  
pp. 2828-2842
Author(s):  
Gavin Fullstone ◽  
Tabea L. Bauer ◽  
Cristiano Guttà ◽  
Manuela Salvucci ◽  
Jochen H. M. Prehn ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Mitochondrial Outer Membrane ◽  
Apoptosis Resistance ◽  
Caspase 9 ◽  
Biologically Relevant ◽  
Autocatalytic Cleavage ◽  
Execution Phase ◽  
Crucial Component ◽  
Mitochondrial Outer Membrane Permeabilisation ◽  
Cellular Stresses

Abstract The execution phase of apoptosis is a critical process in programmed cell death in response to a multitude of cellular stresses. A crucial component of this pathway is the apoptosome, a platform for the activation of pro-caspase 9 (PC9). Recent findings have shown that autocleavage of PC9 to Caspase 9 (C9) p35/p12 not only permits XIAP-mediated C9 inhibition but also temporally shuts down apoptosome activity, forming a molecular timer. In order to delineate the combined contributions of XIAP and the apoptosome molecular timer to apoptosis execution we utilised a systems modelling approach. We demonstrate that cooperative recruitment of PC9 to the apoptosome, based on existing PC9-apoptosome interaction data, is important for efficient formation of PC9 homodimers, autocatalytic cleavage and dual regulation by XIAP and the molecular timer across biologically relevant PC9 and APAF1 concentrations. Screening physiologically relevant concentration ranges of apoptotic proteins, we discovered that the molecular timer can prevent apoptosis execution in specific scenarios after complete or partial mitochondrial outer membrane permeabilisation (MOMP). Furthermore, its ability to prevent apoptosis is intricately tied to a synergistic combination with XIAP. Finally, we demonstrate that simulations of these processes are prognostic of survival in stage III colorectal cancer and that the molecular timer may promote apoptosis resistance in a subset of patients. Based on our findings, we postulate that the physiological function of the molecular timer is to aid XIAP in the shutdown of caspase-mediated apoptosis execution. This shutdown potentially facilitates switching to pro-inflammatory caspase-independent responses subsequent to Bax/Bak pore formation.

Mechanisms of p53-dependent apoptosis

2001 ◽  
Vol 29 (6) ◽  
pp. 684-688 ◽  
Author(s):  
M. Schuler ◽  
D. R. Green
Keyword(s):  
Cell Death ◽  
Cytochrome C ◽  
Apoptotic Cell ◽  
Mitochondrial Outer Membrane ◽  
Caspase Activation ◽  
Caspase 9 ◽  
High Molecular Weight Complex ◽  
Mitochondrial Outer Membrane Permeabilization ◽  
Cellular Stresses ◽  
Induced Apoptosis

Cellular stresses, such as growth factor deprivation, DNA damage or oncogene expression, lead to stabilization and activation of the p53 tumour suppressor protein. Depending on the cellular context, this results in one of two different outcomes: cell cycle arrest or apoptotic cell death. Cell death induced through the p53 pathway is executed by the caspase proteinases, which, by cleaving their substrates, lead to the characteristic apoptotic phenotype. Caspase activation by p53 occurs through the release of apoptogenic factors from the mitochondria, including cytochrome c and Smac/DIABLO. Released cytochrome c allows the formation of a high-molecular weight complex, the apoptosome, which consists of the adapter protein Apaf-1 and caspase 9, which is activated following recruitment into the apoptosome. Active caspase 9 then cleaves and activates the effector caspases, such as caspases-3 and -7, which execute the death program. Released Smac/DIABLO facilitates caspase activation through repression of the IAP caspase inhibitor proteins. The release of mitochondrial apoptogenic factors is regulated by the pro- and anti-apoptotic Bcl-2 family proteins, which either induce or prevent the permeabilization of the outer mitochondrial membrane. The mechanism by which p53 signals to the Bcl-2 family proteins is unclear. It was shown that some of the pro-apoptotic family members, such as Bax, Noxa or PUMA, are transcriptional targets of p53. In addition, transcription-independent, pro-apoptotic activities of p53 have been described. The elucidation of the p53-dependent pathway, resulting in mitochondrial outer membrane permeabilization through the pro-apoptotic Bcl-2 family proteins, is a key to unveiling the mechanism of stress-induced apoptosis.

scholarly journals Antiproliferative and Apoptotic Effects of Red Beetroot and Betanin on Human Colorectal Cancer Cell Lines

2021 ◽  
Author(s):  
Amir Saber ◽  
Nasim Abedimanesh ◽  
Mohammad-Hossein Somi ◽  
Ahmad Yari Khosroushahi
Keyword(s):  
Colorectal Cancer ◽  
Cell Lines ◽  
Caspase 3 ◽  
Caspase 8 ◽  
Alcoholic Extract ◽  
Caspase 9 ◽  
Dapi Staining ◽  
Normal Cells ◽  
Colorectal Cancer Cell Lines ◽  
Ht 29

Abstract Background: Colorectal cancer (CRC) is the third most common type of cancer worldwide. Fruit and vegetables have some active compounds such as flavonoids and polyphenols that protect against malignancies through their antioxidative, anti-inflammatory, anti-proliferative, neuro, and hepatoprotective properties. Red beetroot (Beta vulgaris) contains red (betacyanins) and yellow (betaxanthins) pigments known as betalains. Betanin makes up 75-95% of the total betacyanins, possessed a wide range of favorable biological effects such as chemopreventive, anticarcinogenic, anti-tumorogenic, antiangiogenic, and proapoptotic effects. Methods: Red beetroot hydro-alcoholic extract and betanin were used to treat Caco-2 and HT-29 colorectal cancer cells, as well as KDR/293 normal epithelial cells. The half-maximal inhibitory concentration (IC50) was determined by prescreening MTT tests in the range of 20 to 140 µg/ml at 24 and 48 h. The cytotoxicity and apoptosis-inducing evaluations were performed via MTT assay, DAPI staining, and FACS-flow cytometry tests using determined times and doses. Moreover, the expression level of six important genes involving in the apoptosis pathway (Bcl-2, BAD, Caspase-3, Caspase-8, Caspase-9, and Fas-R) were determined using the real-time polymerase chain reaction (RT-PCR) method.Results: The IC50 doses for HT-29 and Caco-2 cell lines were determined to be about 92 μg/mL, 107 μg/mL for beetroot hydro-alcoholic extract, and 64 μg/mL, 90 μg/mL for betanin at 48 h, respectively. Our findings showed that beetroot extract and betanin significantly inhibit the growth of HT-29 and Caco-2 cell lines, time and dose-dependently, without considerable adverse effects on KDR/293 normal cells. Moreover, DAPI staining and flow cytometry results revealed significant apoptosis symptoms in treated cancerous cell lines. The expression level of pro-apoptotic genes involved in intrinsic and extrinsic apoptosis pathways (BAD, Caspase-3, Caspase-8, Caspase-9, and Fas-R) in treated HT-29 and Caco-2 cells was higher than untreated and normal cells, whereas the anti-apoptotic gene (Bcl-2) was downregulated. Conclusion: Beetroot hydro-alcoholic extract and betanin significantly inhibited cell proliferation and induced cell apoptosis (intrinsic and extrinsic pathways) via modification of effective genes in both colorectal cancer cell lines with no significant cytotoxic effects on KDR/293 normal cells. The mechanism of the anticancer effects of red beetroot extract and betanin needs to be further studied.

scholarly journals Nei Endonuclease VIII-Like1 (NEIL1) Inhibits Apoptosis of Human Colorectal Cancer Cells

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Wanjuan Xue ◽  
Yongcheng Liu ◽  
Ningning Xin ◽  
Jiyu Miao ◽  
Juan Du ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cancer Cells ◽  
Signaling Pathway ◽  
Human Colon ◽  
Caspase 9 ◽  
Human Colon Cancer ◽  
Expression Levels ◽  
Colorectal Cancer Cells ◽  
Human Colorectal Cancer Cells

The study is aimed at investigating the role of Nei endonuclease VIII-like1 (NEIL1) in the pathogenesis of colorectal cancer (CRC). The human CRC (HCT116 and SW480) cells were subjected to the siRNA silencing and recombinant plasmid overexpression of NEIL1. Transfection of siNEIL1 significantly inhibited the cell growth. It also increased the Bax expression levels, while it decreased the Bcl-2 expression levels in human CRC cells, leading the Bax/Bcl-2 balance toward apoptosis. Moreover, the apoptosis was promoted through the caspase-9 signaling pathway. One the other hand, high expression of NEIL1 promoted the cell viability and reduced the apoptosis, inducing the balance of Bax/Bcl-2 in the human colon cancer cells to be antiapoptotic. In addition, the caspase-9 signaling pathway inhibited apoptosis, contrary to the results obtained by downregulating NEIL1 expression. Furthermore, NEIL1 was negatively regulated by miR-7-5p, indicating that miR-7-5p inhibited the NEIL1 expression after transcription. Overexpression of miR-7-5p reversed the effects of NEIL1 on these CRC cells. In conclusion, NEIL1 promotes the proliferation of CRC cells, which is regulated negatively by miR-7-5p. These findings suggest that NEIL1 is a potential therapeutic target for CRC.

scholarly journals Caspase-9 cleavage, do you need it?

2007 ◽  
Vol 405 (1) ◽  
Author(s):  
Davina Twiddy ◽  
Kelvin Cain
Keyword(s):  
Cell Death ◽  
Apoptotic Cell ◽  
Caspase 9 ◽  
Autocatalytic Cleavage ◽  
Downstream Effector ◽  
Apoptosis Inhibition ◽  
Biochemical Journal ◽  
Effector Caspase ◽  
Effector Caspases

Caspase-9, which is activated by association with the Apaf-1 (apoptotic protease-activating factor-1) apoptosome complex, cleaves and activates the downstream effector caspases-3 and -7, thereby executing the caspase-cascade and cell-death programme. Although caspase-9 does not need to be cleaved to be active, apoptotic cell death is always accompanied by autocatalytic cleavage and by further downstream effector caspase-dependent cleavage of caspase-9. In this issue of the Biochemical Journal, Denault and co-workers evaluate the role of caspase-3-dependent cleavage of caspase-9 and conclude that this mechanism mainly serves to enhance apoptosis by alleviating XIAP (X-linked inhibitor of apoptosis) inhibition of the apical caspase.

scholarly journals Structural Insights into Bak Activation and Oligomerisation

2014 ◽  
Vol 70 (a1) ◽  
pp. C1166-C1166
Author(s):  
Jason Brouwer ◽  
Adeline Robin ◽  
Geoff Thompson ◽  
Ahmad Wardak ◽  
Ruth Kluck ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Cell Death ◽  
Outer Membrane ◽  
Crystal Structures ◽  
Conformational Changes ◽  
Mitochondrial Outer Membrane ◽  
Related Protein ◽  
Mitochondrial Outer Membrane Permeabilisation ◽  
Structural Insights ◽  
Analogous Mechanism

Apoptotic stimuli activate and oligomerise the pro-apoptotic proteins Bak and Bax resulting in mitochondrial outer membrane permeabilisation and subsequent cell death. This activation can occur when certain BH3-only proteins directly interact with Bak and Bax. A recent crystal structure by Czabotar et al. (2013) revealed a novel conformational change for Bax upon activation by BH3-only peptides. Distinguishing characteristics of BH3-only proteins capable of directly activating Bax were also elucidated. Here we describe complementary studies on the related protein Bak. We identify specific BH3-only peptides capable of inducing Bak dimerisation and describe crystal structures that provide key insights into Bak activation and oligomerisation. These structures demonstrate that Bak undergoes similar conformational changes upon activation to those observed with Bax. Altogether our results confirm an analogous mechanism for activation and dimerization of Bak and Bax in response to BH3-only peptides.

Down-regulation of NTSR3 inhibits cell growth and metastasis, as well as the PI3K–AKT and MAPK signaling pathways in colorectal cancer

2020 ◽  
Vol 98 (5) ◽  
pp. 548-555
Author(s):  
Aihua Liu ◽  
Zhongfu Zuo ◽  
Linlin Liu ◽  
Lihua Liu
Keyword(s):  
Colorectal Cancer ◽  
Cell Growth ◽  
Signaling Pathways ◽  
Cell Apoptosis ◽  
Caspase 3 ◽  
Mapk Signaling ◽  
Adhesion Assay ◽  
Caspase 9 ◽  
Down Regulation ◽  
Mapk Signaling Pathways

Colorectal cancer is a common malignancy. NTS receptor 3 (NTSR3) is known to play an important role in several cancers. This study examined the effects of NTSR3 on cell growth and metastasis in colorectal cancer. Western blot analysis, real-time PCR, immunofluorescence staining, MTT, cell cycle assay, cell apoptosis assay, Hoechst staining, caspase-3 and caspase-9 activity assays, cell adhesion assay, wound healing assay, and a Transwell assay were used in this study. We found that NTSR3 was expressed at relatively high levels in the colorectal cancer cell lines SW620 and SW480. NTSR3 knockdown suppressed cell growth and promoted cell apoptosis. Meanwhile, the protein expression levels of cyclinD1, cyclinE1, CDK4, and p-RB were reduced, and the levels of p-P27, P15, P21, cleaved caspase-3, and cleaved caspase-9 protein were increased. Cell invasiveness and cell migration were reduced with knockdown of NTSR3. In addition, our rescue experiments demonstrated that overexpression of the siRNA-resistant alleles of NTSR3 abrogated the NTSR3-siRNA-mediated effects on cell function. Further, down-regulation of NTSR3 inactivated the PI3K–AKT and MAPK signaling pathways. Collectively, these data demonstrate that knockdown of NTSR3 inhibits cell growth and metastasis, as well as the PI3K–AKT and MAPK signaling pathways in colorectal cancer. Thus, our results indicate that NTSR3 is a potential therapeutic target for treating colorectal cancer.

scholarly journals Antiproliferative activity and caspase enhancement properties of Annona muricata leaves extract against colorectal cancer cells

2016 ◽  
Vol 25 (3) ◽  
pp. 136-42
Author(s):  
Lili Indrawati ◽  
Purwantyastuti Ascobat ◽  
Budiman Bela ◽  
Murdani Abdullah ◽  
Ingrid S. Surono ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cell Line ◽  
Cancer Cell ◽  
Water Extract ◽  
Cancer Cell Line ◽  
Colorectal Cancer Cell ◽  
Colorectal Cancer Cell Line ◽  
Annona Muricata ◽  
Caspase 9

Background: The prevalence of colorectal cancer is rising in Asia including Indonesia. Annona muricata tea leaves, that is traditionally used for maintaining health, and lately being used by cancer patients. The objectives of this study is to investigate its effects in human colorectal cancer cell in vitro and ex vivo.Methods: Thirty patients with colorectal cancer (CRC) were enrolled in a randomized double-blind placebo-controlled trial. They were equally divided into two groups: those treated with 300 mg A. muricata leaf extract and placebo daily for 8 weeks. Serum from supplemented CRC patients of both groups was compared for caspase 9 and caspase 8 enhancement activity. Antiproliferative effect of water extract of A. muricata leaves and its fractions were evaluated against colorectal cancer cell line (DLD-1 and COLO 205) compared with 5-fluorouracil and placebo, the dose range was 62.5-2,000 µg/mL. Method used was 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Data were analyzed by Mann-Whitney U test. The p value was set at 0.05.Results: Ethanol-soluble fraction of A. muricata leaves extract water extract (ESFAM) leaves extract had cytotoxicity effects on DLD-1 as well as COLO 205 cell line, as shown by the lower IC50 compared to 5-fluorouracil and placebo, 20.59 μg/mL and 654.9μg/mL, respectively. Serum of subjects supplemented with extract significantly induced caspase 9 (p=0.001) activity of DLD-1 colorectal cancer cell line, but not for caspase 8 activity (p=0.372).Conclusion: The study's results suggest the cytotoxicity potential of  A. muricata  leaves extract  in in vitro and ex vivo studies.

Measurement of quality of care for adjuvant chemotherapy of colorectal cancer

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 6071-6071
Author(s):  
M. Morse ◽  
R. Prosnitz ◽  
C. Mantyh ◽  
D. Fisher ◽  
G. Samsa ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Adjuvant Chemotherapy ◽  
Quality Care ◽  
Future Research ◽  
Inclusion Criteria ◽  
Policy Makers ◽  
Leverage Points ◽  
Stage Iii Colon Cancer ◽  
Crucial Component

6071 Background: Although adjuvant chemotherapy (CT) is a crucial component of the therapy for stage III colon cancer and stage II and III rectal cancer patients, little is known about how best to measure whether quality care is being delivered. We sought to provide policy-makers and stake-holders with an inventory of the available measures and their usefulness. Methods: The MEDLINE and Cochrane databases were searched for all publications which might contain quality measures (QMs) pertaining to the diagnosis and treatment of patients with colorectal cancer (CRC). Our analysis was confined to QMs pertaining to adjuvant CT for CRC, based on US data, and published after 1990. Identified QMs were quantitatively rated based on the concepts of importance/usability, scientific acceptability, and validity or how well they had been tested. Results: 3,429 abstracts were reviewed, of which 843 articles underwent full text evaluation. Ultimately 74 articles met the established inclusion criteria for containing QMs, 32 of which pertained to adjuvant CT. These 32 articles contained 10 QMs, 8 of which had major flaws limiting their applicability. The two most ideal measures are presented in the table . Among the reasons some measures did not rate highly was the failure to utilize standard staging definitions or reliance on administrative inpatient databases, which do not account for chemotherapy administered on an out-patient basis. Conclusions: Very few measures of the quality of adjuvant CT for CRC have been published to date and fewer rate highly with regard to the concepts of importance/usability, scientific acceptability, and validity. Future research should focus on refining existing QMs and on developing new QMs which target important leverage points with respect to the provision of adjuvant therapy for CRC. [Table: see text] [Table: see text]

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