Mcl-1L cleavage is involved in TRAIL-R1– and TRAIL-R2–mediated apoptosis induced by HGS-ETR1 and HGS-ETR2 human mAbs in myeloma cells

Blood ◽  
2006 ◽  
Vol 108 (4) ◽  
pp. 1346-1352 ◽  
Author(s):  
Emmanuelle Menoret ◽  
Patricia Gomez-Bougie ◽  
Alexandrine Geffroy-Luseau ◽  
Sylvanne Daniels ◽  
Philippe Moreau ◽  
...  
Keyword(s):  
Caspase 3 ◽  
Kinetic Studies ◽  
Myeloma Cell ◽  
Caspase 8 ◽  
Caspase Activation ◽  
Caspase 9 ◽  
Human Mabs ◽  
Myeloma Cells ◽  
Activation Kinetic ◽  
Survival And Growth

Abstract We evaluated the ability of 2 human mAbs directed against TRAILR1 (HGS-ETR1) and TRAILR2 (HGS-ETR2) to kill human myeloma cells. HGS-ETR1 and HGS-ETR2 mAbs killed 15 and 9 human myeloma cell lines (HMCLs; n = 22), respectively. IL-6, the major survival and growth factor for these HMCLs, did not prevent their killing. Killing induced by either HGS-ETR1 or HGS-ETR2 was correlated with the cleavage of Mcl-1L, a major molecule for myeloma survival. Mcl-1L cleavage and anti-TRAILR HMCL killing were dependent on caspase activation. Kinetic studies showed that Mcl-1L cleavage occurred very early (less than 1 hour) and became drastic once caspase 3 was activated. Our data showed that both the extrinsic (caspase 8, Bid) and the intrinsic (caspase 9) pathways are activated by anti–TRAIL mAb. Finally, we showed that the HGS-ETR1 and, to a lesser extent, the HGS-ETR2 mAbs were able to induce the killing of primary myeloma cells. Of note, HGS-ETR1 mAb was able to induce the death of medullary and extramedullary myeloma cells collected from patients at relapse. Taken together, our data clearly encourage clinical trials of anti–TRAILR1 mAb in multiple myeloma, especially for patients whose disease is in relapse, at the time of drug resistance.

Arsenic Trioxide-Mediated Growth Inhibition of Myeloma Cells Is Associated with An Extrinsic Signaling Pathway Involved in Caspase 3 and Caspase 8.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4899-4899
Author(s):  
Jumei Shi ◽  
Yi Wu ◽  
Siqing Wang ◽  
Xiuqin Meng ◽  
Rong Wei ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Growth Inhibition ◽  
Arsenic Trioxide ◽  
Signaling Pathway ◽  
Molecular Mechanism ◽  
Caspase 3 ◽  
Myeloma Cell ◽  
Caspase 8 ◽  
Myeloma Cells

Abstract Abstract 4899 Arsenic trioxide (ATO) is a well-known inhibitor of cell proliferation in certain forms of malignancy and has been successfully used in the treatment of acute promyelocytic leukemia. Preclinical and clinical studies showed that ATO has anti-myeloma effects both as a single agent and in the combination therapy; however, the underlying molecular mechanism remains elusive. This study was performed to evaluate the molecular mechanism underlying its anti-myeloma activities. Cells from OPM2, U266, RPMI8226 myeloma cell lines and patients diagnosed with myeloma (n=6) were cultured with various concentrations of ATO for 4 days. Cell growth and viability were assayed by trypan blue dye exclusion. Cell cycle and apoptosis were analyzed by flow cytometry using CellQuest software and Vybrant Apoptosis Assay Kit. Alterations of the signaling pathways induced by ATO were tested by real-time PCR and western blot. ATO induced potent inhibition of myeloma cell growth compared with untreated control cells. Further investigation showed that ATO down-regulated c-Myc and phosphorylated (p)-Rb, while it up-regulated p53, p21Clip1, and p27Kip1 proteins, resulting in G2/M cell cycle arrest and cell growth inhibition. ATO treatment increased mRNA levels of interferon regulatory factor-1 (IRF-1) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), as well as protein levels of caspase 8 and cleaved caspase 3, indicating involvement of the extrinsic apoptotic pathway. No significant change was detected in the expression levels of Bax, Bcl-xL caspase 9 and Bcl-2, indicating that the intrinsic signaling pathway was not involved. A pan-caspase inhibitor abrogated ATO-induced apoptosis of myeloma cells. Our data suggest that ATO induces apoptosis in MM cells most likely through an extracellular signaling pathway. Disclosures No relevant conflicts of interest to declare.

Arsenic trioxide–induced apoptosis in myeloma cells: p53-dependent G1 or G2/M cell cycle arrest, activation of caspase-8 or caspase-9, and synergy with APO2/TRAIL

Blood ◽  
2003 ◽  
Vol 101 (10) ◽  
pp. 4078-4087 ◽  
Author(s):  
Qun Liu ◽  
Susan Hilsenbeck ◽  
Yair Gazitt
Keyword(s):  
Cell Cycle ◽  
Arsenic Trioxide ◽  
Cell Lines ◽  
Myeloma Cell ◽  
Caspase 8 ◽  
Dependent Manner ◽  
Caspase 9 ◽  
Myeloma Cells ◽  
Induced Apoptosis ◽  
In Cells

Abstract Arsenic trioxide (ATO) has been shown to induce differentiation and apoptosis in acute promyelocytic leukemia (APL) cells concomitant with down-regulation of the PML-RARα fusion protein, a product of the t(15:17) translocation characteristic of APL leukemic cells. However, ATO is also a potent inducer of apoptosis in a number of other cancer cells lacking the t(15:17) translocation. The exact mechanism of ATO-induced apoptosis in these cells is not yet clear. We tested the effect of ATO on 7 myeloma cell lines with varying p53 status and report that in cells with mutated p53, ATO induced rapid and extensive (more than 90%) apoptosis in a time- and dose-dependent manner concomitant with arrest of cells in G2/M phase of the cell cycle. Myeloma cells with wild-type (wt) p53 were relatively resistant to ATO with maximal apoptosis of about 40% concomitant with partial arrest of cells in G1 and up-regulation of p21. The use of caspase blocking peptides, fluorescence-tagged caspase-specific substrate peptides, and Western immunoblotting confirmed the involvement of primarily caspase-8 and -3 in ATO-induced apoptosis in myeloma cells with mutated p53 and primarily caspase-9 and -3 in cells expressing wt p53. We also observed up-regulation by ATO of R1 and R2 APO2/TRAIL (tumor necrosis factor–related apoptosis-inducing ligand) receptors. Most important, however, we observed a synergy between ATO and APO2/TRAIL in the induction of apoptosis in the partially resistant myeloma cell lines and in myeloma cells freshly isolated from myeloma patients. Our results justify the use of the combination of these 2 drugs in clinical setting in myeloma patients.

The extrinsic caspase pathway modulates endotoxin-induced diaphragm contractile dysfunction

2007 ◽  
Vol 102 (4) ◽  
pp. 1649-1657 ◽  
Author(s):  
Gerald S. Supinski ◽  
Xinying Ji ◽  
Wenyi Wang ◽  
Leigh A. Callahan
Keyword(s):  
Caspase 3 ◽  
Death Receptor ◽  
Interferon Γ ◽  
Caspase 8 ◽  
Contractile Dysfunction ◽  
Tnf Receptor ◽  
Caspase Activation ◽  
Caspase 9 ◽  
Diaphragm Dysfunction ◽  
Tnf Α

The mechanisms by which infections induce diaphragm dysfunction remain poorly understood. The purpose of this study was to determine which caspase pathways (i.e., the extrinsic, death receptor-linked caspase-8 pathway, and/or the intrinsic, mitochondrial-related caspase-9 pathway) are responsible for endotoxin-induced diaphragm contractile dysfunction. We determined 1) whether endotoxin administration (12 mg/kg IP) to mice induces caspase-8 or -9 activation in the diaphragm; 2) whether administration of a caspase-8 inhibitor ( N-acetyl-Ile-Glu-Thr-Asp-CHO, 3 mg/kg iv) or a caspase-9 inhibitor ( N-acetyl-Leu-Glu-His-Asp-CHO, 3 mg/kg iv) blocks endotoxin-induced diaphragmatic weakness and caspase-3 activation; 3) whether TNF receptor 1-deficient mice have reduced caspase activation and diaphragm dysfunction following endotoxin; and 4) whether cytokines (TNF-α or cytomix, a mixture of TNF-α, interleukin-1β, interferon-γ, and endotoxin) evoke caspase activation in C2C12 myotubes. Endotoxin markedly reduced diaphragm force generation ( P < 0.001) and induced increases in caspase-3 and caspase-8 activity ( P < 0.03), but failed to increase caspase-9. Inhibitors of caspase-8, but not of caspase-9, prevented endotoxin-induced reductions in diaphragm force and caspase-3 activation ( P < 0.01). Mice deficient in TNF receptor 1 also had reduced caspase-8 activation ( P < 0.001) and less contractile dysfunction ( P < 0.01) after endotoxin. Furthermore, incubation of C2C12 cells with either TNF-α or cytomix elicited significant caspase-8 activation. The caspase-8 pathway is strongly activated in the diaphragm following endotoxin and is responsible for caspase-3 activation and diaphragm weakness.

TRAILR Triggering by Human Antibodies Induces Apoptosis through an Early Cleavage of Mcl-1 and Caspase 3 in Myeloma Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3397-3397
Author(s):  
Catherine Pellat-Deceunynck ◽  
Patricia Gomez-Bougie ◽  
Sylvanne Daniels ◽  
Alexandrine Geffroy-Luseau ◽  
Regis Bataille ◽  
...  
Keyword(s):  
Cell Lines ◽  
Caspase 3 ◽  
Chromosomal Translocation ◽  
Myeloma Cell ◽  
Caspase 8 ◽  
Early Cleavage ◽  
Myeloma Cells ◽  
Growth And Survival ◽  
Human Antibodies

Abstract We investigated TRAILR expression and sensitivity of myeloma cells in vitro. This study was done using a panel of 20 myeloma cell lines that are representative of primary myeloma cells (14q chromosomal translocation, IL-6 dependency, phenotype, oncogenes mutation). TRAILR were stimulated with agonistic human antibodies directed against either TRAIL-R1/DR4 (HGS-ETR1, mapatumumab) or TRAIL-R2/DR5 (HGS-ETR2), provided by Human Genome Sciences, Rockville, MD. This approach allowed us to analyze the contribution of each receptor separately. We show that a wide majority of cell lines, 16 of 20 were killed upon either TRAIL-R1 or R2 stimulation in the presence or absence of IL-6. However, 4 cell lines were resistant to HGS-ETR1 and 6 to HGS-ETR2 and 3 to both. Activation of both caspase 8 and Bid has been extensively described as being associated with TRAIL response. Indeed, we observed an activation of both caspase 8 and Bid. Cleaved molecules were detected 6 to 18h after antibody addition but after detection of cellular apoptosis. However, we show that Mcl-1L, a key molecule for myeloma survival, was downregulated and cleaved as soon as 3h after Ab addition. The cleaved form of Mcl-1 has been shown to behave like a proapoptotic molecule. Since caspase 3 has been reported to cleave Mcl-1, we looked at caspase 3 activation. Indeed, we observed that caspase 3 cleavage occured early and concomitantly to the one of Mcl-1. Our data show that in a wide majority of myeloma cell lines (80%) TRAILR triggering induces massive apoptosis that was not prevented by IL-6, the major myeloma cell growth and survival factor. Moreover, apoptosis induced upon TRAILR triggering was fully correlated to an early cleavage of both caspase 3 and Mcl-1 and to a delayed one of both caspase 8 and Bid.

Baicalein, a component of Scutellaria radix from Huang-Lian-Jie-Du-Tang (HLJDT), leads to suppression of proliferation and induction of apoptosis in human myeloma cells

Blood ◽  
2005 ◽  
Vol 105 (8) ◽  
pp. 3312-3318 ◽  
Author(s):  
Zi Ma ◽  
Ken-ichiro Otsuyama ◽  
Shangqin Liu ◽  
Saeid Abroun ◽  
Hideaki Ishikawa ◽  
...  
Keyword(s):  
Cell Lines ◽  
Caspase 3 ◽  
Herbal Medicines ◽  
Myeloma Cell ◽  
Suppressive Effect ◽  
Caspase 9 ◽  
Myeloma Cells ◽  
Induction Of Apoptosis ◽  
Induced Apoptosis

Abstract In the search for a more effective adjuvant therapy to treat multiple myeloma (MM), we investigated the effects of the traditional Chinese herbal medicines Huang-Lian-Jie-Du-Tang (HLJDT), Gui-Zhi-Fu-Ling-Wan (GZFLW), and Huang-Lian-Tang (HLT) on the proliferation and apoptosis of myeloma cells. HLJDT inhibited the proliferation of myeloma cell lines and the survival of primary myeloma cells, especially MPC-1- immature myeloma cells, and induced apoptosis in myeloma cell lines via a mitochondria-mediated pathway by reducing mitochondrial membrane potential and activating caspase-9 and caspase-3. Further experiments confirmed that Scutellaria radix was responsible for the suppressive effect of HLJDT on myeloma cell proliferation, and the baicalein in Scutellaria radix showed strong growth inhibition and induction of apoptosis in comparison with baicalin or wogonin. Baicalein as well as baicalin suppressed the survival in vitro of MPC-1- immature myeloma cells rather than MPC-1+ myeloma cells from myeloma patients. Baicalein inhibited the phosphorylation of IkB-α, which was followed by decreased expression of the IL-6 and XIAP genes and activation of caspase-9 and caspase-3. Therefore, HLJDT and Scutellaria radix have an antiproliferative effect on myeloma cells, especially MPC-1- immature myeloma cells, and baicalein may be responsible for the suppressive effect of Scutellaria radix by blocking IkB-α degradation. (Blood. 2005;105:3312-3318)

TP53 Positively Regulates Cell Death through TRAILR2 (DR5) but Negatively through TRAILR1 (DR4) In Myeloma Cells

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 136-136
Author(s):  
Sylvanie Surget ◽  
Patricia Gomez-Bougie ◽  
David Chiron ◽  
Robin Humphreys ◽  
Philippe Moreau ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Lines ◽  
Caspase 3 ◽  
Target Genes ◽  
Conflicts Of Interest ◽  
Myeloma Cell ◽  
Caspase 8 ◽  
Myeloma Cells ◽  
Trail Receptors ◽  
Tp53 Status

Abstract Abstract 136 Mapatumumab and lexatumumab are human antibodies that bind and activate death receptors TRAILR1/TNFSF10A/DR4 and TRAILR2/TNFSF10B/DR5, respectively. Treatment of primary myeloma cells and myeloma cell lines with these mAbs induced cell death. Mapatumumab induced cell death more effectively than lexatumumab in a panel of 30 human myeloma cell lines (HMCLs). Interestingly, sensitivity to mapatumumab and lexatumumab was mutually exclusive and related to TP53 status (p=0.006). Indeed, wildtype TP53 HMCLs (n=9) were sensitive to lexatumumab (mean of death 40%) but resistant to mapatumumab (mean of death 7%). In contrast, abnormal (n=21) TP53 HMCLs were resistant to lexatumumab (mean of death 7%) but sensitive to mapatumumab (mean of death 44%). Of note, killing by lexatumumab was correlated to TRAILR2 expression while no correlation was found for TRAILR1 expression and lapatumumab killing. Transcriptomic analysis of 30 HMCLs revealed that HMCLs with abnormal TP53 status underexpressed 4 well-known p53 target genes, MDM2, CDKN1A, Bax and TRAILR2 (p<0.01). To activate p53 pathway in myeloma cells, we used melphalan at low doses. Melphalan treatment of wildtype HMCLs, but not of TP53 abnormal HMCLs, increased TRAILR2 expression and cell death mediated by lexatumumab. In contrast, melphalan did not alter TRAILR1 expression or mapatumumab-induced killing, suggesting that TRAILR2 but not TRAILR1 is a p53 target in myeloma cells. Silencing TP53 significantly increased mapatumumab apoptosis (>50% p<0.01). In good agreement with Bax underexpression in TP53 abnormal HMCLs, extensive silencing of key molecules of both extrinsic (caspase 8, caspase 3) and intrinsic pathways of apoptosis (caspase 9, Bid, Bim, Bax) showed that mapatumumab killing was dependent on the extrinsic pathway of apoptosis only: only silencing of caspase 8 or caspase 3 inhibited mapatumumab killing. Altogether, these data show that killing through TRAIL receptors is differentially regulated by p53 in myeloma cells, positively for TRAILR2 but negatively for TRAILR1. Interestingly, myeloma cells with an abnormal p53 that are more resistant to all drugs are more sensitive than wt ones to killing through TRAILR1 making this pathway very attractive for p53 deficient myeloma cells. Disclosures: No relevant conflicts of interest to declare.

Reactive oxygen species and caspase activation mediate silica-induced apoptosis in alveolar macrophages

2001 ◽  
Vol 280 (1) ◽  
pp. L10-L17 ◽  
Author(s):  
Han-Ming Shen ◽  
Zhuo Zhang ◽  
Qi-Feng Zhang ◽  
Choon-Nam Ong
Keyword(s):  
Reactive Oxygen Species ◽  
Cell Death ◽  
Alveolar Macrophages ◽  
Caspase 3 ◽  
Reactive Oxygen ◽  
Parp Cleavage ◽  
Oxygen Species ◽  
Caspase Activation ◽  
Caspase 9 ◽  
Induced Apoptosis

Alveolar macrophages (AMs) are the principal target cells of silica and occupy a key position in the pathogenesis of silica-related diseases. Silica has been found to induce apoptosis in AMs, whereas its underlying mechanisms involving the initiation and execution of apoptosis are largely unknown. The main objective of the present study was to examine the form of cell death caused by silica and the mechanisms involved. Silica-induced apoptosis in AMs was evaluated by terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling assay and cell cycle/DNA content analysis. The elevated level of reactive oxygen species (ROS), caspase-9 and caspase-3 activation, and poly(ADP-ribose) polymerase (PARP) cleavage in silica-treated AMs were also determined. The results showed that there was a temporal pattern of apoptotic events in silica-treated AMs, starting with ROS formation and followed by caspase-9 and caspase-3 activation, PARP cleavage, and DNA fragmentation. Silica-induced apoptosis was significantly attenuated by a caspase-3 inhibitor, N-acetyl-Asp-Glu-Val-Asp aldehyde, and ebselen, a potent antioxidant. These findings suggest that apoptosis is an important form of cell death caused by silica exposure in which the elevated ROS level that results from silica exposure may act as an initiator, leading to caspase activation and PARP cleavage to execute the apoptotic process.

scholarly journals Inclusion Complex of Zerumbone with Hydroxypropyl-β-Cyclodextrin Induces Apoptosis in Liver Hepatocellular HepG2 Cells via Caspase 8/BID Cleavage Switch and Modulating Bcl2/Bax Ratio

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Nabilah Muhammad Nadzri ◽  
Ahmad Bustamam Abdul ◽  
Mohd Aspollah Sukari ◽  
Siddig Ibrahim Abdelwahab ◽  
Eltayeb E. M. Eid ◽  
...  
Keyword(s):  
Inclusion Complex ◽  
Mitochondrial Membrane ◽  
Morphological Study ◽  
Caspase 3 ◽  
Anticancer Agent ◽  
Caspase 8 ◽  
Caspase 9 ◽  
Solubility In Water ◽  
Anticancer Effects ◽  
First Time

Zerumbone (ZER) isolated fromZingiber zerumbetwas previously encapsulated with hydroxypropyl-β-cyclodextrin (HPβCD) to enhance ZER’s solubility in water, thus making it highly tolerable in the human body. The anticancer effects of this new ZER-HPβCD inclusion complex via apoptosis cell death were assessed in this study for the first time in liver hepatocellular cells, HepG2. Apoptosis was ascertained by morphological study, nuclear stain, and sub-G1 cell population accumulation with G2/M arrest. Further investigations showed the release of cytochrome c and loss of mitochondrial membrane potential, proving mitochondrial dysfunction upon the ZER-HPβCD treatment as well as modulating proapoptotic and anti-apototic Bcl-2 family members. A significant increase in caspase 3/7, caspase 9, and caspase 8 was detected with the depletion of BID cleaved by caspase 8. Collectively, these results prove that a highly soluble inclusion complex of ZER-HPβCD could be a promising anticancer agent for the treatment of hepatocellular carcinoma in humans.

scholarly journals Protective Effects of Shenfuyixin Granule on H2O2-Induced Apoptosis in Neonatal Rat Cardiomyocytes

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xinlu Wang ◽  
Xuanxuan Hao ◽  
Youping Wang ◽  
Bin Li ◽  
Lin Cui ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Caspase 3 ◽  
Neonatal Rat ◽  
Caspase 8 ◽  
Caspase 9 ◽  
Rat Cardiomyocytes ◽  
Expression Levels ◽  
Apoptosis Rate ◽  
Neonatal Rat Cardiomyocytes ◽  
Mitochondrion Membrane Potential

Shenfuyixin granule (SFYXG, i.e., Xinshuaikang granule) is a prescription, commonly used in the clinical experience, which plays a significant role in the treatment of heart failure. The purpose of this present research was to investigate the protective effect of SFYXG, and the mechanism about anti-H2O2-induced oxidative stress and apoptosis in the neonatal rat cardiomyocytes. Myocardial cells, as is well known, were divided into 4 groups: normal, model, SFYXG, and coenzyme Q10 group, respectively. Cells viability was determined by MTT assay. Flow cytometry and AO/EB staining were implemented to test the apoptosis rate and intracellular reactive oxygen species (ROS) level. Mitochondrion membrane potential (MMP) was evaluated by JC-1 fluorescence probe method. The myocardial ultrastructure of mitochondrion was measured by electron microscope. The related mRNA expression levels of Bax, Bcl-2, Caspase-3, caspase-8, and caspase-9 were detected by real-time polymerase chain reaction (PCR). Also, the expression levels of Bax and Bcl-2 protein were detected by Western blot, and the expression levels of caspase-3, caspase-8, and caspase-9 protein were tested by caspase-Glo®3 Assay, caspase-Glo®8 Assay, and caspase-Glo®9 Assay, respectively. GAPDH was used as the internal reference gene/protein. The results revealed that SFYXG (0.5 mg/ml) raised the viability of myocardial cell, weakened the apoptosis rate and ROS level, corrected the mitochondrion membrane potential stability, and improved cell morphology and ultrastructure of myocardial mitochondrion. Furthermore, SFYXG upregulated the antiapoptosis gene of Bcl-2, but downregulated the proapoptosis genes of Bax, caspase-3, and caspase-9. In conclusion, SFYXG could appear to attenuate myocardial injury by its antioxidative and antiapoptosis effect.

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.

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