Catechins induced acute promyelocytic leukemia cell apoptosis and triggered PML-RARα oncoprotein degradation
© Zhang et al.; licensee BioMed Central Ltd. 2014
Received: 17 June 2014
Accepted: 23 September 2014
Published: 1 October 2014
It has recently been reported that the extracts of green tea polyphenol have cancer preventive effects. In this study, we investigated the effect of the natural composition from green tea leaves Catechins on acute promyelocytic leukemia (APL).
In vitro, APL cell lines NB4, retinoic acid-resistant NB4-R1 and NB4-R2 were treated with different concentrations of Catechins. Cell viability and cell apoptosis were analyzed using MTT assay and flow cytometric assay, respectively. Expression of proteins related to apoptosis and PML-RARα oncoprotein were assessed by Western blot. In vivo anti-tumor activity of Catechins was examined in nude mice xenografted with NB4 cells and in situ cell apoptosis was detected by terminal deoxytransferase-catalyzed DNA nick-end labeling assay.
Catechins at micromolar concentration levels significantly inhibited APL cell proliferation and induced cell apoptosis, in association with mitochondria damage, ROS production and caspase activation. The anti-apoptotic Bcl-2 family member Bcl-xL was down regulated, with pro-apoptotic member Bax remaining unchanged. Moreover, Catechins induced the degradation of PML-RARα oncoprotein. Catechins-mediated apoptotic effect was also observed in primary APL cells without affecting normal hematopoietic progenitor cells. In the murine xenograft model, Catechins remarkably inhibited tumor growth and induced in situ leukemic cell apoptosis.
Catechins might be a potential candidate for APL treatment by activating intrinsic apoptotic pathway and targeting PML-RARα oncoprotein.
KeywordsCatechins Acute promyelocytic leukemia Apoptosis PML-RARα oncoprotein
Acute promyelocytic leukemia (APL) accounts for approximately 10% of all acute myeloid leukemias and is characterized by a specific chromosomal translocation t(15;17), resulting in the fusion of promyelocytic leukemia (PML) gene to retinoic acid receptor (RARα) gene. The expression of PML-RARα chimeric protein plays a central role in leukemogenesis, including arrest of differentiation and deregulation of apoptosis ,. The currently used agents all-trans retinoic acid (ATRA) and arsenic trioxide (As2O3) directly target PML-RARα oncoprotein and dramatically improve the clinical outcome of APL patients -. This greatly encourages further discovery of potential molecular target-based agents, particularly nature products, on APL treatment.
Epidemiologic studies have already shown that green tea consumption is beneficial to health and can reduce the incidence of cancer . Recently, green tea products have attracted more attention because of their anti-cancer effects revealed in experimental tumor models -. Catechins is the main component extracted from the green tea leaves, including epipallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and epicatechin (EC) etc. . Catechins prove to be inexpensive, safe, and can be administrated orally. Therefore, whether Catechins possesses anti-leukemia capability is of great interest to leukemia treatment.
In this study, we assessed the effect of Catechins on both retinoic acid (RA)-sensitive and -resistant APL cell lines -, as well as on primary APL cells and on a murine xenograft APL model. The Catechins-induced apoptosis of APL cells and expressions of related proteins (Bcl-2, Bcl-xL, Bax and PML-RARα) were also investigated to explore possible molecular mechanism.
Catechins inhibited cell growth and induced cell apoptosis in human APL cell lines
The response curves of NB4-R1, NB4-R2 and NB4 to Catechins were shown in Figure 1B. Catechins inhibited cell growth in a time- and dose-dependent manner. To confirm whether the growth inhibition of Catechins was caused by apoptosis, cell morphology and AnnexinV-FITC/PI double staining were performed. Morphologically, cell apoptosis was observed at 24 hours of treatment with Catechins, showing characteristic changes, such as chromatin condensation, nuclear fragmentation, and formation of apoptotic bodies (Figure 1C). The percentage of Annexin V-positive cells, reflecting those undergoing apoptosis, was gradually increased during treatment (Figure 1D). Cell cycle analysis also revealed a time-dependent elevation of sub-G1 cell content, consistent with Catechins-induced APL cell apoptosis (Figure 1E).
Catechins-induced apoptosis was associated with mitochondria damage, ROS production and caspase activation
NB4 cells were then treated with Catechins, either alone or combined with pan-caspase inhibitor ZVAD-FMK. Catechins-induced cell growth inhibition could be significantly abrogated by ZVAD-FMK treatment, referring Catechins as an apoptotic-dependent cell death inducer (Figure 2B). Marked dissipation of mitochondrial trans-membrane potential (Δψm) (Figure 2C) and subsequent decreased mitochondrial cytochrome c (Figure 2D) were observed in NB4-R1, NB4-R2 and NB4 cells treated with Catechins in a dose-dependent manner.
To investigate whether ROS level was also affected by Catechins, we also used flow cytometric analysis with a cell-permeable dye, H2DCFDA, which is specifically cleaved to emit a fluorescence wave length in the presence of ROS. Treatment with 200 μM Catechins for 2 hours resulted in a significant elevation of intracellular ROS in NB4-R1, NB4-R2 and NB4 cells (Figure 2E).
Catechins acted on intrinsic apoptotic pathway through downregulation of Bcl-xL and induced apoptosis-independent degradation of PML-RARα oncoprotein
Mitochondrial membrane permeability is directly controlled by Bcl-2 family proteins, which are the central regulators of caspase activation. To determine whether Catechins impair the mitochondria through affecting these Bcl-2 family members, the expression of anti-apoptotic factor Bcl-2 and Bcl-xL, as well as pro-apoptotic factor Bax were investigated in NB4 cells at 24 hours of incubation with Catechins. Bcl-xL expression were decreased, while no significant change was detected on Bcl-2 and Bax expression (Figure 3B).
Western blot analysis confirmed that untreated NB4 cells expressed the PML-RARα oncoprotein. Catechins treatment induced the degradation of PML-RARα at 12 and 24 hours (Figure 3C). Independent on its apoptotic action, Catechins-mediated degradation of PML-RARα oncoprotein was not affected by co-treatment with pan-caspase inhibitor ZVAD-FMK (Figure 3D). However, the degradation process could be, at least partially, blocked by proteasome inhibitor bortezomib, indicating that it was dependent on proteasome pathway (Figure 3E).
Catechins induced apoptosis of leukemia cells from t(15;17) APL patients and did not affect the proliferation capacity of normal hematopoietic progenitor cells
Of note, as determined by MTT assay, proliferation of CD34+ cells isolated from human cord blood was not affected even at the concentrations up to 800 μM after 72 hours of treatment, suggesting that primary APL cells responded to Catechins in a similar way as NB4 cells and Catechins exerted no severe cytotoxic effect on normal hematopoietic precursors (Figure 4F).
Catechins inhibited tumor growth and induced in situ leukemia cell apoptosis in a murine xenograft model
Tumor cell apoptosis was evaluated by TUNEL assay. Comparing with the control mice, a significantly increased number of apoptotic cells was observed in the Catechins-treated mice (p < 0.001) (Figure 5B), providing in vivo evidence of Catechins-induced APL cell apoptosis.
Catechins is the full extracts of the natural green tea leaves. EGCG is the main component of Catechins and has been shown with anti-tumor activities in many types of cancers -. Here we reported the first time, that Catechins possessed an anti-proliferative effect on leukemia cells, especially on t(15;17) leukemia cells. This was observed not only in well-established APL cell lines and primary tumor samples of APL patients, but also in a murine xenograft tumor model of t(15;17) leukemia. Equally effective to targeted agents commonly used in APL as As2O3, Catechins, with similar bioactivity but much less expensive than EGCG, could be a potential candidate to treat APL.
Catechins possesses the anti-leukemic activity mainly due to the induction of apoptosis, which has been demonstrated by morphological features and increase of apoptotic cells both in vitro and in vivo. Caspase-3 activation is essential for leukemia cell apoptosis. In our study, Catechins generated a cleavage of caspase-3 and subsequent cleavage of the DNA repair enzyme PARP, the hallmark of apoptosis. Bcl-xL, as an important anti-apoptotic protein of Bcl-2 family , was accordingly reduced by Catechins, further implying that intrinsic apoptotic pathway was involved in Catechins-induced apoptosis. This is in consistent with previous study of EGCG on many solid tumors, such as hepatocellular carcinoma, chondrosarcoma, and endometrial cancer -. Moreover, Catechins also changed the intracellular redox status and regulatedthe mitochondria pathway through elevating ROS, similar to EGCG . The intracellular redox status, depending on ROS generation, is critical in keeping mitochondria stable. Elevation of intracellular ROS production was also shown during EGCG-induced apoptosis in tumor cell lines mentioned above -. Therefore, Catechins induced APL cell apoptosis through intrinsic apoptotic pathway via Bcl-xL downregulation and ROS induction.
Interestingly, PML-RARα oncoprotein can be directly targeted by Catechins. In hepatocellular carcinoma, EGCG lowers the expression of phosphorylated STAT3 protein and inhibits the expression of multiple genes including Bcl-xL . In an apoptosis-independent manner, functional modulation of RARA and PML-RARα by the peptidyl-prolyl-isomerase Pin1, or the the mitogen-activated protein kinase, p38α correlates with stabilization/degradation of PML-RARα via the proteasome pathway ,. Our data also revealed that Catechins acted on PML-RARα, at least partially, in a proteasome-dependent manner. Therefore, PML-RARα oncoprotein may also represent the target of the Catechins treatment in APL, although the precise mechanism of action in Catechins-induced PML-RARα degradation need further investigation.
Our findings not only suggested possible mechanisms of Catechins in the apoptosis-regulatory pathways in APL cells, but also provide a model for studying Catechins in cancer treatment. Since green tea extracts have already entered phase I trials in patients with solid tumors -, similar clinical trials would be necessary to further evaluate the anti-leukemic effect of Catechins on acute leukemias.
In summary, our study demonstrated that Catechins effectively induced apoptosis of APL cells through induction of intrinsic apoptotic pathway and degradation of PML-RARα oncoprotein. Catechins may thus be a potential apoptosis inducer and therapeutic agent for APL treatment.
Materials and methods
Catechins (Pharmanex, USA, each capsule contains EGCG 95 mg, ECG 37 mg, EGC 15 mg), EGCG (Sigma-ALDRICH, E4143, C22H18O11, MW: 458.37), ECG (Shanghai Winherb Medical Technology Co., Ltd, C22H18O10, MW: 442.37) and EGC (Shanghai Winherb Medical Technology Co., Ltd, C15H14O7, MW: 306.27) were prepared at the concentration of 10 mM with RPMI 1640 medium (GIBCO-BRL, Grand Island, NY, USA). Arsenic trioxide (As2O3, Sigma-ALDRICH, A1010, MW: 197.84) was dissolved in RPMI 1640 medium as 5 mM solution. All-trans-retinoic acid (ATRA, Sigma-ALDRICH) was dissolved in ethanol as 100 μM solution. Pan-caspase inhibitor ZVAD-FMK (627610) was from Merck & Co. Inc. Bortezomib was from Millennium Pharmaceuticals (Cambridge, MA, USA). The primary antibodies against β-actin (13E5, #4970), anti-caspase-3 (8G10, #9665), anti-caspase-8 (D35G2, #4790), anti-caspase-9 Antibody (#9502), anti-PARP Antibody (#9542), anti-Bcl-2 (D55G8, #4223), anti-Bax (D2E11, #5023), anti-Bcl-xL (54H6, #2764) were from Cell Signaling (Beverly, MA, USA). Mouse monoclonal anti-PML Protein (ab57276) was from Abcam (Hongkong). The secondary antibody ImmunoPure Goat Anti-Rabbit IgG (#31460) was from Thermo Scientific (USA). Goat anti-mouse IgG (PB001) was from Shanghai Immune Biotech Ltd (ImB, CHINA). Chemiluminescence phototope-horseradish peroxidase kit (WBKLS0100) was from Millipore (Germany).
Cell lines, cell viability and cell morphology
Human APL leukemia cell lines NB4 (retinoic acid-sensitive), NB4-R1 and NB4-R2 cells (retinoic acid-resistant) were kindly provided by Professor Michel Lanotte at Saint Louis Hospital in France. Acute myeloid leukemia cell lines Kasumi-1, K562 and U937 were available from American Type Culture Collection. Cells were cultured in RPMI 1640 medium, supplemented with 10% heat-inactivated fetal bovine serum (GIBCO-BRL), 100 U/mL penicillin and 100 mg/mL streptomycin (GIBCO-BRL), in 5%CO2-95% air humidified atmosphere at 37°C. Fresh leukemia cells from the bone marrow of three APL patients were enriched by Ficoll separation. The diagnosis was established on the basis of morphological examination, presence of t(15;17) by cytogenetic study and PML-RARα fusion gene by molecular analysis. CD34+ cells were purified from human cord blood by density gradient centrifugation. Informed consent was obtained according to institutional guidelines. Cell viability was assessed by triplicate counting of trypan blue dye-excluding cells under light microscopy. Cell morphology was evaluated by Wright's staining of cells prepared by cytospin centrifugation.
MTT reduction assay
A total of 5 × 104 cells per well were seeded in a 96-well plate, and treated with Catechins at concentrations of 25, 50, 100, 200 or 400 μM for different time (24 h, 48 h or 72 h). After treatment, 0.1 mg MTT was added to each well. The samples were incubated for 4 hours and the absorbance (optical density, OD value) was measured at 490 nm by spectrophotometry. Calculation of the cell growth inhibition rate at different concentrations is done by comparing it against the growth rate of untreated control group. Inhibition rate = [1 - OD value of treated cell/OD value of control cell] × 100%.
Flow cytometric assays for Annexin-V/PI, nuclear DNA contentdistribution, mitochondrial trans-membrane potentials, mitochondrial cytochrome c, and reactive oxygen species (ROS) detection
A total of 2 × 105 cells was analyzed using an Annexin V-FITC/PI apoptosis detection kit II (BD Pharmingen™, Franklin Lakes, NJ, USA) according to manufacturer's instructions. To assess the distribution of nuclear DNA content, cells were collected, washed in PBS and fixed overnight in 75% ethanol at −20°C, treated with 1% RNase A for at least 15 min at 37°C, and stained with 50 μg/ml PI. For mitochondrial trans-membrane potential assessment, 1 × 106 cells were washed twice with PBS, incubated with 10 μg/mL of Rh123 for 30 min at 37°C, and stained with 50 μg/mL of PI. Mitochondrial cytochrome c was measured by FlowCellect™ cytochrome c kit (Millipore) according to manufacturer's protocols. To measure ROS levels, 5 × 105 cells were washed with RPMI1640 and incubated with 5 μM DCFH-DA for 30 min at 37°C. The fluorescent intensity was measured by flow cytometry (Becton Dickinson, San Jose, CA, USA). All experiments were performed in triplicate and data were collected, stored, and analyzed by Lysis 11 software (Becton Dickinson).
Western blot analysis
Western blot analysis was performed according to standard protocols. Approximately 5 × 106 cells were harvested and incubated in 100 μL lysis buffer [50 mM Tris (pH 7.4), 150 mM NaCl, 1% Triton X-100, 1% deoxycholate, 0.1% SDS)] to prepare total protein samples. Equal amounts of protein (20 μg) were separated by SDS-PAGE on 10% gels and transferred on to PVDF membrane (Millipore), and blocked with 5% non-fat dried milk in TBST [phosphate-buffered saline-0.05% Tween] at room temperature for 60 min. The membranes were subjected to immunoblot analyses with appropriate primary antibody followed by horseradish peroxidase-linked secondary antibody. The immunocomplexes were visualized using chemiluminescence phototype-horseradish peroxidase kit.
Terminal deoxytransferase-catalyzed DNA nick-end labeling (TUNEL) assay
In situ tumor cell apoptosis was performed on deparaffinized 5 μm thick sections using TdT-FragEL™ DNA Fragmentation Detection Kit (Merck, Germany) according to the manufacturer's recommendation. For quantification, three different fields were counted under light microscopy and at least 500 cells were enumerated in each field. All experiments were performed in triplicate.
APL murine model
Murine xenograft APL model was established by NB4 cells inoculation in nude mice. Briefly, mice were pretreated with 3 Gy of total body irradiation, which is a sublethal dose that was expected to enhance the acceptance of xenografts. Subsequently, NB4 cells (1 × 107) were inoculated subcutaneously into the right flank of nude mice (male, 5–6 weeks of age). Inoculated NB4 cells formed subcutaneous tumors at the injection site from 6–8 days. Ten days after cell inoculation, mice were randomly divided into two groups, and received water (n = 5) or Catechins (10 mM, n = 5) as the sole drinking treated for 21 days. Tumor volumes were calculated by the formula: 0.5 × a × b2 in millimeters, where `a' is the length and `b' is the width. Tissue samples were fixed in formaldehyde and further embedded in paraffin.
All the results were expressed as the mean ± S.D. and determined using t-test to compare variance. Survival functions were estimated using the Kaplan-Meier method and compared by the log-rank test. P value < 0.05 were considered statistically significant. All statistical analyses were evaluated using the SPSS for Windows, Version 18.0.
Acute promyelocytic leukemia
All-trans retinoic acid
- MTT assays:
3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assays
The half maximal inhibitory concentration
Mitochondrial trans-membrane potential
Reactive oxygen species
Terminal deoxytransferase-catalyzed DNA nick-end labeling assay
The work was supported, in part, by the National Natural Science Foundation of China (81325003 and 81201863), the Shanghai Commission of Science and Technology (11JC1407300 and 08411953900), and the Program of Shanghai Subject Chief Scientists (13XD1402700).
- Chen Z, Wang ZY, Chen SJ: Acute promyelocytic leukemia: cellular and molecular basis of differentiation and apoptosis. Pharmacol Ther. 1997, 76 (1–3): 141-149. 10.1016/S0163-7258(97)00090-9.View ArticlePubMedGoogle Scholar
- Dong S, Tong JH, Huang W, Chen SJ, Chen Z, Wang ZY, Geng JP, Qi ZW: Molecular study on the chromosome 15 breakpoints in the translocation t(15; 17) in acute promyelocytic leukemia (APL). Sci China B. 1993, 36 (9): 1101-1109.PubMedGoogle Scholar
- Hu J, Liu YF, Wu CF, Xu F, Shen ZX, Zhu YM, Li JM, Tang W, Zhao WL, Wu W, Sun HP, Chen QS, Chen B, Zhou GB, Zelent A, Waxman S, Wang ZY, Chen SJ, Chen Z: Long-term efficacy and safety of all-trans retinoic acid/arsenic trioxide-based therapy in newly diagnosed acute promyelocytic leukemia. Proc Natl Acad Sci U S A. 2009, 106 (9): 3342-3347. 10.1073/pnas.0813280106.PubMed CentralView ArticlePubMedGoogle Scholar
- Wang ZY, Chen Z: Acute promyelocytic leukemia: from highly fatal to highly curable. Blood. 2008, 111 (5): 2505-2515. 10.1182/blood-2007-07-102798.View ArticlePubMedGoogle Scholar
- Shen ZX, Shi ZZ, Fang J, Gu BW, Li JM, Zhu YM, Shi JY, Zheng PZ, Yan H, Liu YF, Chen Y, Shen Y, Wu W, Tang W, Waxman S, De Thé H, Wang ZY, Chen SJ, Chen Z: All-trans retinoic acid/As2O3 combination yields a high quality remission and survival in newly diagnosed acute promyelocytic leukemia. Proc Natl Acad Sci U S A. 2004, 101 (15): 5328-5335. 10.1073/pnas.0400053101.PubMed CentralView ArticlePubMedGoogle Scholar
- Wang ZY: Ham-Wasserman lecture: treatment of acute leukemia by inducing differentiation and apoptosis. Hematology Am Soc Hematol Educ Program. 2003, 2003 (1): 1-13. 10.1182/asheducation-2003.1.1.View ArticleGoogle Scholar
- Wang ZY: Mechanism of action of all-trans retinoic acid and arsenic trioxide in the treatment of acute promyelocytic leukemia. Gan to kagaku ryoho Cancer & chemotherapy. 2002, 29 (Suppl 1): 214-218.Google Scholar
- Zhao WL, Chen SJ, Shen Y, Xu L, Cai X, Chen GQ, Shen ZX, Chen Z, Wang ZY: Treatment of acute promyelocytic leukemia with arsenic trioxide: clinical and basic studies. Leuk Lymphoma. 2001, 42 (6): 1265-1273. 10.3109/10428190109097751.View ArticlePubMedGoogle Scholar
- Wang ZY: Arsenic compounds as anticancer agents. Cancer Chemother Pharmacol. 2001, 48 (Suppl 1): S72-S76. 10.1007/s002800100309.View ArticlePubMedGoogle Scholar
- Chen GQ, Zhu J, Shi XG, Ni JH, Zhong HJ, Si GY, Jin XL, Tang W, Li XS, Xong SM, Shen ZX, Sun GL, Ma J, Zhang P, Zhang TD, Gazin C, Naoe T, Chen SJ, Wang ZY, Chen Z: In vitro studies on cellular and molecular mechanisms of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia: As2O3 induces NB4 cell apoptosis with downregulation of Bcl-2 expression and modulation of PML-RAR alpha/PML proteins. Blood. 1996, 88 (3): 1052-1061.PubMedGoogle Scholar
- Chen Z, Tong JH, Dong S, Zhu J, Wang ZY, Chen SJ: Retinoic acid regulatory pathways, chromosomal translocations, and acute promyelocytic leukemia. Genes Chromosomes Cancer. 1996, 15 (3): 147-156. 10.1002/(SICI)1098-2264(199603)15:3<147::AID-GCC1>3.0.CO;2-2.View ArticlePubMedGoogle Scholar
- Chen SJ, Wang ZY, Chen Z: Acute promyelocytic leukemia: from clinic to molecular biology. Stem Cells. 1995, 13 (1): 22-31. 10.1002/stem.5530130104.View ArticlePubMedGoogle Scholar
- Chen Z, Chen SJ, Wang ZY: Retinoic acid and acute promyelocytic leukemia: a model of targetting treatment for human cancer. C R Acad Sci III. 1994, 317 (12): 1135-1141.PubMedGoogle Scholar
- Mukhtar H, Ahmad N: Tea polyphenols: prevention of cancer and optimizing health. Am J Clin Nutr. 2000, 71 (6 Suppl): 1698S-1702S. discussion 1703S-1694SPubMedGoogle Scholar
- Mitscher LA, Jung M, Shankel D, Dou JH, Steele L, Pillai SP: Chemoprotection: a review of the potential therapeutic antioxidant properties of green tea (Camellia sinensis) and certain of its constituents. Med Res Rev. 1997, 17 (4): 327-365. 10.1002/(SICI)1098-1128(199707)17:4<327::AID-MED2>3.0.CO;2-Y.View ArticlePubMedGoogle Scholar
- Stuart EC, Scandlyn MJ, Rosengren RJ: Role of epigallocatechin gallate (EGCG) in the treatment of breast and prostate cancer. Life Sci. 2006, 79 (25): 2329-2336. 10.1016/j.lfs.2006.07.036.View ArticlePubMedGoogle Scholar
- Horie N, Hirabayashi N, Takahashi Y, Miyauchi Y, Taguchi H, Takeishi K: Synergistic effect of green tea catechins on cell growth and apoptosis induction in gastric carcinoma cells. Biol Pharm Bull. 2005, 28 (4): 574-579. 10.1248/bpb.28.574.View ArticlePubMedGoogle Scholar
- Porath D, Riegger C, Drewe J, Schwager J: Epigallocatechin-3-gallate impairs chemokine production in human colon epithelial cell lines. J Pharmacol Exp Ther. 2005, 315 (3): 1172-1180. 10.1124/jpet.105.090167.View ArticlePubMedGoogle Scholar
- Ran ZH, Zou J, Xiao SD: Experimental study on anti-neoplastic activity of epigallocatechin-3-gallate to digestive tract carcinomas. Chin Med J. 2005, 118 (16): 1330-1337.PubMedGoogle Scholar
- Ravindranath MH, Saravanan TS, Monteclaro CC, Presser N, Ye X, Selvan SR, Brosman S: Epicatechins purified from green tea (Camellia sinensis) differentially suppress growth of gender-dependent human cancer cell lines. Evidence-based complementary and alternative medicine: eCAM. 2006, 3 (2): 237-247. 10.1093/ecam/nel003.View ArticlePubMedGoogle Scholar
- Sah JF, Balasubramanian S, Eckert RL, Rorke EA: Epigallocatechin-3-gallate inhibits epidermal growth factor receptor signaling pathway. Evidence for direct inhibition of ERK1/2 and AKT kinases. J Biol Chem. 2004, 279 (13): 12755-12762. 10.1074/jbc.M312333200.View ArticlePubMedGoogle Scholar
- Nam S, Smith DM, Dou QP: Ester bond-containing tea polyphenols potently inhibit proteasome activity in vitro and in vivo. J Biol Chem. 2001, 276 (16): 13322-13330. 10.1074/jbc.M004209200.View ArticlePubMedGoogle Scholar
- Suganuma M, Okabe S, Kai Y, Sueoka N, Sueoka E, Fujiki H: Synergistic effects of (−−)-epigallocatechin gallate with (−−)-epicatechin, sulindac, or tamoxifen on cancer-preventive activity in the human lung cancer cell line PC-9. Cancer Res. 1999, 59 (1): 44-47.PubMedGoogle Scholar
- Fang MZ, Wang Y, Ai N, Hou Z, Sun Y, Lu H, Welsh W, Yang CS: Tea polyphenol (−)-epigallocatechin-3-gallate inhibits DNA methyltransferase and reactivates methylation-silenced genes in cancer cell lines. Cancer Res. 2003, 63 (22): 7563-7570.PubMedGoogle Scholar
- Katiyar SK, Afaq F, Azizuddin K, Mukhtar H: Inhibition of UVB-induced oxidative stress-mediated phosphorylation of mitogen-activated protein kinase signaling pathways in cultured human epidermal keratinocytes by green tea polyphenol (−)-epigallocatechin-3-gallate. Toxicol Appl Pharmacol. 2001, 176 (2): 110-117. 10.1006/taap.2001.9276.View ArticlePubMedGoogle Scholar
- Jung YD, Ellis LM: Inhibition of tumour invasion and angiogenesis by epigallocatechin gallate (EGCG), a major component of green tea. Int J Exp Pathol. 2001, 82 (6): 309-316. 10.1046/j.1365-2613.2001.00205.x.PubMed CentralView ArticlePubMedGoogle Scholar
- Qian Y, Zhang L, Chen Q-S, Zhang Y, Xiao D, Wen X-Q, Zhao W-L: Catechins induce apoptosis of multiple myeloma RPMI 8226 cells and its mechanism. Tumor. 2012, 32 (1): 1-6.Google Scholar
- Pillai SP, Mitscher LA, Menon SR, Pillai CA, Shankel DM: Antimutagenic/antioxidant activity of green tea components and related compounds. J Environ Pathol Toxicol Oncol. 1999, 18 (3): 147-158.PubMedGoogle Scholar
- Riazantseva NV, Novitskii VV, Kaigorodova EV, Chasovskikh N, Starikova EG: Mitogenactivated protein kinases JNK and p38 as redox-dependent molecular targets correction of programmed cell death disturbances in oxidative stress condition. Usp Fiziol Nauk. 2009, 40 (2): 3-11.PubMedGoogle Scholar
- Lee YK, Bone ND, Strege AK, Shanafelt TD, Jelinek DF, Kay NE: VEGF receptor phosphorylation status and apoptosis is modulated by a green tea component, epigallocatechin-3-gallate (EGCG), in B-cell chronic lymphocytic leukemia. Blood. 2004, 104 (3): 788-794. 10.1182/blood-2003-08-2763.View ArticlePubMedGoogle Scholar
- Nakagawa H, Hasumi K, Woo JT, Nagai K, Wachi M: Generation of hydrogen peroxide primarily contributes to the induction of Fe(II)-dependent apoptosis in Jurkat cells by (−)-epigallocatechin gallate. Carcinogenesis. 2004, 25 (9): 1567-1574. 10.1093/carcin/bgh168.View ArticlePubMedGoogle Scholar
- Nakazato T, Ito K, Ikeda Y, Kizaki M: Green tea component, catechin, induces apoptosis of human malignant B cells via production of reactive oxygen species. Clin Cancer Res. 2005, 11 (16): 6040-6049. 10.1158/1078-0432.CCR-04-2273.View ArticlePubMedGoogle Scholar
- de Mejia EG, Ramirez-Mares MV, Puangpraphant S: Bioactive components of tea: cancer, inflammation and behavior. Brain Behav Immun. 2009, 23 (6): 721-731. 10.1016/j.bbi.2009.02.013.View ArticlePubMedGoogle Scholar
- Zhu J, Shi XG, Chu HY, Tong JH, Wang ZY, Naoe T, Waxman S, Chen SJ, Chen Z: Effect of retinoic acid isomers on proliferation, differentiation and PML relocalization in the APL cell line NB4. Leukemia. 1995, 9 (2): 302-309.PubMedGoogle Scholar
- Lanotte M, Martin-Thouvenin V, Najman S, Balerini P, Valensi F, Berger R: NB4, a maturation inducible cell line with t(15;17) marker isolated from a human acute promyelocytic leukemia (M3). Blood. 1991, 77 (5): 1080-1086.PubMedGoogle Scholar
- Ruchaud S, Duprez E, Gendron MC, Houge G, Genieser HG, Jastorff B, Doskeland SO, Lanotte M: Two distinctly regulated events, priming and triggering, during retinoid-induced maturation and resistance of NB4 promyelocytic leukemia cell line. Proc Natl Acad Sci U S A. 1994, 91 (18): 8428-8432. 10.1073/pnas.91.18.8428.PubMed CentralView ArticlePubMedGoogle Scholar
- Kroemer G: The proto-oncogene Bcl-2 and its role in regulating apoptosis. Nat Med. 1997, 3 (6): 614-620. 10.1038/nm0697-614.View ArticlePubMedGoogle Scholar
- Li W, Nie S, Yu Q, Xie M: (−)-Epigallocatechin-3-gallate induces apoptosis of human hepatoma cells by mitochondrial pathways related to reactive oxygen species. J AgricFood Chem. 2009, 57 (15): 6685-6691. 10.1021/jf901396f.View ArticleGoogle Scholar
- Manohar M, Fatima I, Saxena R, Chandra V, Sankhwar PL, Dwivedi A: (−)-Epigallocatechin-3-gallate induces apoptosis in human endometrial adenocarcinoma cells via ROS generation and p38 MAP kinase activation. J Nutr Biochem. 2013, 24 (6): 940-947. 10.1016/j.jnutbio.2012.06.013.View ArticlePubMedGoogle Scholar
- Yang WH, Fong YC, Lee CY, Jin TR, Tzen JT, Li TM, Tang CH: Epigallocatechin-3-gallate induces cell apoptosis of human chondrosarcoma cells through apoptosis signal-regulating kinase 1 pathway. J Cell Biochem. 2011, 112 (6): 1601-1611. 10.1002/jcb.23072.View ArticlePubMedGoogle Scholar
- Shirakami Y, Shimizu M, Adachi S, Sakai H, Nakagawa T, Yasuda Y, Tsurumi H, Hara Y, Moriwaki H: (−)-Epigallocatechin gallate suppresses the growth of human hepatocellular carcinoma cells by inhibiting activation of the vascular endothelial growth factor-vascular endothelial growth factor receptor axis. Cancer Sci. 2009, 100 (10): 1957-1962. 10.1111/j.1349-7006.2009.01241.x.View ArticlePubMedGoogle Scholar
- Abou E, Naga RN, Azab SS, El-Demerdash E, Shaarawy S, El-Merzabani M, el Ammar SM: Sensitization of TRAIL-induced apoptosis in human hepatocellular carcinoma HepG2 cells by phytochemicals. Life Sci. 2013, 92 (10): 555-561. 10.1016/j.lfs.2013.01.017. 21View ArticleGoogle Scholar
- Kim CY, Lee C, Park GH, Jang JH: Neuroprotective effect of epigallocatechin-3-gallate against beta-amyloid-induced oxidative and nitrosative celldeath via augmentation of antioxidant defense capacity. Arch Pharm Res. 2009, 32 (6): 869-881. 10.1007/s12272-009-1609-z.View ArticlePubMedGoogle Scholar
- Wang Y, Ren X, Deng C, Yang L, Yan E, Guo T, Li Y, Xu MX: Mechanism of the inhibition of the STAT3 signaling pathway by EGCG. Oncol Rep. 2013, 30 (6): 2691-2696.PubMedGoogle Scholar
- Maurizio G, Andrea B, Valeria G, Alessandro R, Edoardo P, Ivan R, Cecile RE, Giannino DS, Alessandra R, Mineko T, Enrico G: Inhibition of the Peptidyl-prolyl-isomerase Pin1 enhances the responses of acute myeloid leukemia cells to retinoic acid via stabilization of RARA and PML-RARA. Cancer Res. 2009, 69: 1016-1026.Google Scholar
- Gianni M, Peviani M, Bruck N, Rambaldi A, Borleri G, Terao M, Kurosaki M, Paroni G, Rochette-Egly C, Garattini E: p38aMAPK interacts with and inhibits RARa: suppression of the kinase enhances the therapeutic activity of retinoids in acute myeloid leukemia cells. Leukemia. 2012, 26: 1850-1861. 10.1038/leu.2012.50.View ArticlePubMedGoogle Scholar
- Pisters KM, Newman RA, Coldman B, Shin DM, Khuri FR, Hong WK, Glisson BS, Lee JS: Phase I trial of oral green tea extract in adult patients with solid tumors. J Clin Oncol. 2001, 19 (6): 1830-1838.PubMedGoogle Scholar
- Crew KD, Brown P, Greenlee H, Bevers TB, Arun B, Hudis C, McArthur HL, Chang J, Rimawi M, Vornik L, Cornelison TL, Wang A, Hibshoosh H, Ahmed A, Terry MB, Santella RM, Lippman SM, Hershman DL: Phase IB randomized, double-blinded, placebo-controlled, dose escalation study of polyphenon E in women with hormone receptor-negative breast cancer. Cancer Prev Res. 2012, 5 (9): 1144-1154. 10.1158/1940-6207.CAPR-12-0117.View ArticleGoogle Scholar
- Zhao H, Zhu W, Xie P, Li H, Zhang X, Sun X, Yu J, Xing L: A phase I study of concurrent chemotherapy and thoracic radiotherapy with oral epigallocatechin-3-gallate protection in patients with locally advanced stage III non-small-cell lung cancer. Radiother Oncol. 2014, 110 (1): 132-136. 10.1016/j.radonc.2013.10.014.View ArticlePubMedGoogle Scholar
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