Platycodin d induces reactive oxygen species-mediated apoptosis signal-regulating kinase 1 activation and endoplasmic reticulum stress response in human breast cancer cells

Abstract Platycodin D (PD), a natural compound found in Platycodon grandiflorum, induces apoptotic cell death in various carcinoma cells. One mechanism of PD-mediated cell death is by activation of mitogen-activated protein kinases, as suggested in a recent report. In this study, we further examined upstream signal pathways and the relationship between these signals and reactive oxygen species (ROS). Using immunoblotting assays, we found that PD activated apoptosis signal-regulating kinase 1 (ASK1) through phosphorylation of ASK1 at threonine and dephosphorylation of ASK1 at serine. We also showed that PD caused activation of the endoplasmic reticulum (ER) stress response. This was supported by observations showing that treatment with PD induces phosphorylation of PKR-like ER kinase (PERK) and eukaryotic initiation factor 2 α (eIF 2α), up-regulating expression of glucose-regulated protein 78/immunoglobulin heavy chain binding protein (GRP78/Bip) and CCAAT/enhancer-binding protein homologous protein/growth arrest and DNA damage-inducible gene 153 (CHOP/GADD153) and activation of caspase-4. Furthermore, PD-induced ASK1 and ER stress responses were inhibited by the antioxidant N-acetyl-l-cysteine. These results suggest that ROS play a critical role for activation of ASK1 and ER stress in PD-treated cancer cells.     

Dancing on damaged chromatin: functions of ATM and the RAD50/MRE11/NBS1 complex in cellular responses to DNA damage

In order to preserve and protect genetic information, eukaryotic cells have developed a signaling or communications network to help the cell respond to DNA damage, and ATM and NBS1 are key players in this network. ATM is a protein kinase which is activated immediately after a DNA double strand break (DSB) is formed, and the resulting signal cascade generated in response to cellular DSBs is regulated by post-translational protein modifications such as phosphorylation and acetylation. In addition, to ensure the efficient functioning of DNA repair and cell cycle checkpoints, the highly ordered structure of eukaryotic chromatin must be appropriately altered to permit access of repair-related factors to DNA. These alterations are termed chromatin remodeling, and are executed by a specific remodeling complex in conjunction with histone modifications. Current advances in the molecular analysis of DNA damage responses have shown that the auto-phosphorylation of ATM and the interaction between ATM and NBS1 are key steps for ATM activation, and that the association of ATM and NBS1 is involved in chromatin remodeling. Identification of novel factors which function in ubiquitination (RNF8, Ubc13, Rap80, etc.) has also enabled us to understand more details of the early stages in DNA repair pathways which respond to DSBs. In this review, the focus is on the role of ATM and the RAD50/MRE11/NBS1 complex in DSB response pathways, and their role in DSB repair and in the regulation of chromatin remodeling.     

Ampelopsin Induces DR5-Mediated Apoptotic Cell Death in EBV-Infected Cells through the p38 Pathway

Abstract

Ampelopsin (AMP) is a well-known flavonoid that exerts a number of biological and pharmacological effects including anticancer effects against several cancer cell lines. In this study, we investigated the anticancer activity of AMP against Epstein-Barr virus (EBV)-positive cells and its mechanism of action. Our results showed that AMP dose-dependently inhibited cell viability and induced apoptotic cell death in EBV-positive cells without cytotoxicity in EBV-negative cells. In particular, AMP induced caspase-8 dependent apoptosis via upregulation of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and death receptor (DR5). Knockdown of DR5 by RNA interference blocked AMP-induced apoptosis. Furthermore, AMP dose-dependently activated p38 mitogen-activated protein kinases (MAPKs) in EBV-positive cells. Additionally, SB203580 (a p38-MAPK inhibitor) effectively inhibited apoptotic cell death. These results demonstrate that treatment with AMP induces the apoptosis of EBV-positive cells through upregulation of TRAIL/DR5 and activation of p38 signaling. Therefore, these results provide experimental information for developing AMP as a new therapeutic drug against EBV-positive cancer.     

YAP基因在甲状腺乳头状癌中的表达及意义

目的:探讨YAP基因在甲状腺乳头状癌中的表达及其生物学意义。方法:应用QRT-PCR、免疫组织化学SP法、Western-blotting,分别检测人甲状腺乳头状癌组织标本中YAP基因和蛋白的表达情况。结果:QRT-PCR检测显示甲状腺乳头状癌组织中YAP mRNA的表达明显低于对照组;免疫组织化学结果显示YAP在甲状腺乳头状癌中低表达;Western-blotting提示YAP在甲状腺乳头状癌组织中的表达较对照组明显降低。YAP mRNA及蛋白的表达在甲状腺乳头状癌和对照组之间有统计学差异(P<0.05)。结论:在甲状腺乳头状癌组织中,YAP在mRNA和蛋白水平均低表达,提示YAP基因在甲状腺乳头状癌的发生发展中起抑癌作用。     

Sarsaparilla (Smilax Glabra Rhizome) Extract Activates Redox-Dependent ATM/ATR Pathway to Inhibit Cancer Cell Growth by S Phase Arrest,Apoptosis, and Autophagy

Sarsaparilla (Smilax Glabra Rhizome) exerts growth inhibitory effect on multiple cancer cells in vitro and in vivo, and redox-dependent persistent activation of ERK1/2 has been reported to underlie this effect. Here, we report an activation of ATM/ATR-dependent signaling pathway also as a mechanism for the cancer cell growth inhibition induced by the supernatant fraction of the water-soluble extract from sarsaparilla (SW). SW treatment (3.5 μg/μL) promoted the phosphorylations of ATM, ATR, and CHK1 in AGS and HT-29 cells. The ATM kinase inhibitor, KU55933, could reverse SW-induced ERK phosphorylation but not the reduced glutathione/oxidized glutathione (GSH/GSSG) imbalance in AGS cells. However, both the redox inhibitor glutathione (GSH) and ERK inhibitor U0126 antagonized SW-induced phosphorylations of ATM, ATR, and CHK1 in AGS cells. We further found KU55933 significantly antagonized SW-induced S phase arrest, apoptosis, autophagy and the resultant cell growth inhibition. Our results provide another molecular basis for the anticancer action of sarsaparilla.     

The Effect of Green Tea Extract and EGCG on the Signaling Network in Squamous Cell Carcinoma

Green tea and its major active component, epigallocatechin-3-gallate (EGCG), have been reported to have anticancer activity on various cancers. However, the exact molecular mechanism of its anticancer activity is still not well understood. We investigated the anticancer activity of green tea extract (GTE) and EGCG on 3 human squamous carcinoma cell lines (CAL-27, SCC-25, and KB) in vitro. We also examined the effects of GTE and EGCG on cell signaling networks using our newly developed Pathway Array technology, which is an innovative proteomic assay to globally screen changes in protein expression and phosphorylation. Our results demonstrated that GTE and EGCG inhibited all 3 squamous carcinoma cells’ growth via S and G₂/M phase arrest, but different sensitivities to GTE and EGCG in different cell lines were observed: CAL-27 cells were more sensitive to the both agents than SCC-25 and KB cells, and GTE at an EGCG equivalent concentration displayed a stronger inhibition than EGCG alone. The Pathway Array assessment of 107 proteins indicated that different signaling pathways were activated in different cell lines, suggesting heterogeneity at the signaling network level. After treatment with GTE or EGCG, a total of 21 proteins and phosphorylations altered significantly in all 3 cell lines based on analysis of variance (ANOVA) (P < 0.05). The major signaling pathways affected by GTE and EGCG were EGFR and Notch pathways, which, in turn, affected cell cycle-related networks. These results suggested that GTE and EGCG target multiple pathways or global networks in cancer cells, which resulted in collective inhibition of cancer cell growth. The finding pointed out the future direction to study the underlying mechanism of the chemotherapeutic and chemopreventive activities of EGCG and GTE.     

Macranthoside B Induces Apoptosis and Autophagy Via Reactive Oxygen Species Accumulation in Human Ovarian Cancer A2780 Cells

Macranthoside B (MB), a saponin compound in Lonicera macranthoides, can block cell proliferation and induce cell death in several types of cancer cells; however, the precise mechanisms by which MB exerts its anticancer effects remain poorly understood. MB blocked A2780 human ovarian carcinoma cell proliferation both dose- and time-dependently. MB induced apoptosis, with increased poly (ADP-ribose) polymerase (PARP) and caspase-3/9 cleavage. MB also caused autophagy in A2780 cells, with light chain 3 (LC3)-II elevation. Inhibiting MB-induced autophagy with the autophagy inhibitor 3-methyladenine (3-MA) significantly decreased apoptosis, with a reduction of growth inhibition; inhibiting MB-induced apoptosis with the pan-caspase inhibitor Z-VAD-FMK did not decrease autophagy but elevated LC3-II levels, indicating that MB-induced autophagy is cytotoxic and may be upstream of apoptosis. Furthermore, MB increased intracellular reactive oxygen species (ROS) levels, with activated 5′ adenosine monophosphate-activated protein kinase (AMPK), decreased mammalian target of rapamycin (mTOR) and P70S6 kinase phosphorylation, and increased PARP and caspase-3/9 cleavage, and LC3-II elevation; treatment with the ROS scavenger N-acetyl cysteine and the AMPK inhibitor Compound C diminished this effect. Therefore, the ROS/AMPK/mTOR pathway mediates the effect of MB on induction of apoptosis via autophagy in human ovarian carcinoma cells.     

Protective effects of Korean red ginseng against radiation-induced apoptosis in human HaCaT keratinocytes

Radiation-induced oral mucositis is a dose-limiting toxic side effect for patients with head and neck cancer. Numerous attempts at improving radiation-induced oral mucositis have not produced a qualified treatment. Ginseng polysaccharide has multiple immunoprotective effects. Our aim was to investigate the effectiveness of Korean red ginseng (KRG) on radiation-induced damage in the human keratinocyte cell line HaCaT and in an in vivo zebrafish model. Radiation inhibited HaCaT cell proliferation and migration in a cell viability assay and wound healing assay, respectively. KRG protected against these effects. KRG attenuated the radiation-induced embryotoxicity in the zebrafish model. Irradiation of HaCaT cells caused apoptosis and changes in mitochondrial membrane potential (MMP). KRG inhibited the radiation-induced apoptosis and intracellular generation of reactive oxygen species (ROS), and stabilized the radiation-induced loss of MMP. Western blots revealed KRG-mediated reduced expression of ataxia telangiectasia mutated protein (ATM), p53, c-Jun N-terminal kinase (JNK), p38 and cleaved caspase-3, compared with their significant increase after radiation treatment. The collective results suggest that KRG protects HaCaT cells by blocking ROS generation, inhibiting changes in MMP, and inhibiting the caspase, ATM, p38 and JNK pathways.     

Selenomethionine stimulates MAPK (ERK) phosphorylation, protein oxidation, and DNA synthesis in gastric cancer cells

Selenium is an essential trace element and is required for the synthesis of cellular enzymes that protect against oxidative stress. Epidemiological findings indicate that low selenium intake is associated with increased cancer risk, and, although the majority of studies show that exposure of transformed cells to selenium results in apoptotic cell death, there are reports indicating that cells exposure to low selenium concentrations promotes cellular proliferation. Gastric adenocarcinoma SNU-1 cells responded to selenomethionine with a biphasic proliferative curve: enhanced incorporation of 3H-thymidine into DNA within a very narrow range of selenomethionine concentrations followed by decreased 3H-thymidine uptake at higher levels. Concentrations of selenomethionine that stimulate cellular proliferation also induce cellular oxidation and phosphorylation of MAPK (ERK), a component of cell signaling cascades. MAPK (ERK) phosphorylation is synonymous with MAPK activation and enhanced cell growth. Our findings support previous observations of enhanced proliferation in response to low levels of selenium and suggest that, at certain concentrations, selenomethionine induces mild oxidative stress that, in turn, stimulates DNA synthesis.     

90例甲状腺乳头状癌的针吸细胞学诊断

目的　总结甲状腺乳头状癌的针吸细胞学特征 ,为诊断与鉴别诊断提供重要依据。方法　回顾性分析 90例甲状腺乳头状癌针吸细胞学特征。结果　甲状腺乳头状癌的针吸细胞学特征有 :乳头状结构 91.11% (82 90 ) ;核内包涵体 85 .5 6 % (77 90 ) ;毛玻璃样核 6 7.78% (6 1 90 ) ;核沟 6 1.11% (5 5 90 ) ;多核巨细胞 5 6 .6 7% (5 1 90 ) ;砂粒体14 .4 4 % (13 90 )。结论　乳头状结构、核内包涵体为诊断甲状腺乳头状癌的重要指征 ;毛玻璃样核、核沟、多核巨细胞、砂粒体等在甲状腺乳头状癌的诊断中亦具重要价值。     

Diallyl trisulfide-induced prostate cancer cell death is associated with Akt/PKB dephosphorylation mediated by P-p66shc

Purpose

P66Shc, an isoform of adaptor proteins, is known to mediate various signals including those leading to apoptosis or cell proliferation. Previously, we have shown that diallyl trisulfide (DATS)-induced prostate cancer cell death was mediated by increased ROS formation. In this study, we investigated the role of p66Shc protein and its serine 36 phosphorylation in DATS induced decrease in prostate cancer cell viability (PC-3).

Methods

PC-3 prostate cancer cells were used in this study. Stable cell lines expressing p66ShcS36A or an empty vector have been obtained. Cell viability, concentration of ROS, changes in P-p66Shc and P-Akt and DNA damage were determined.

Results

We observed that DATS treatment increased p66Shc phosphorylation at serine 36. Importantly, the phosphorylation was abolished by JNK inhibitor SP600125. Cells expressing plasmid-encoded variant of p66ShcS36A showed much higher resistance to DATS-induced cells death. In addition to that, we observed that DATS-induced ROS formation was completely abolished in cells expressing the p66ShcS36A variant. Interestingly, SP600125 proved to prevent DATS-induced Akt inactivation. In order to confirm that the observed effect is related to phosphorylation of p66Shc, we performed experiments on a stable cell line expressing p66ShcS36A. In such cells, DATS-induced Akt dephosphorylation was significantly reduced. On the other hand, hydrogen peroxide induced Akt activation in PC-3 cells, which was abrogated in cells expressing p66ShcS36A.

Conclusions

Our results uncover a novel signaling pathway with p66Shc being indispensable for DATS-induced inactivation of Akt due to hypophosphorylation.     

Luteolin Impacts on the DNA Damage Pathway in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) exhibited high chemoresistance to current treatments. Here we aimed at identifying and repositioning approved drugs that could be selectively toxic toward OSCC cells. Through a cell-based drug screening of 1,280 chemical molecules, we selected compounds lethal to oral cancer SCC-25 cells, while sparing normal keratinocyte HaCaT cells. Within the chemical library, the natural flavonoid luteolin was identified as a potent cytotoxic agent against oral cancer cells in vitro, along with metixene hydrochloride and nitazoxanide. Of note, they exhibit low toxicity and high efficiency compared to the standard-of-care, such as cisplatin and the epidermal growth factor receptor inhibitor tyrphostin. From a molecular standpoint, luteolin causes phosphorylation of ataxia telangiectasia mutated (ATM) and H2AX in a DNA repair pathway and can be efficiently combined with a checkpoint kinase (CHK) pharmacological inhibitor. Thus, luteolin emerges as a potent cytotoxic and/or adjuvant therapy in oral cancer, as it is a natural compound presenting better effects in vitro compared to conventional chemotherapeutic agents. Future in vivo exploration is next required to provide the proof-of-concept that luteolin could be an efficient anticancer molecule.     

Punicic Acid Triggers Ferroptotic Cell Death in Carcinoma Cells

Plant-derived conjugated linolenic acids (CLnA) have been widely studied for their preventive and therapeutic properties against diverse diseases such as cancer. In particular, punicic acid (PunA), a conjugated linolenic acid isomer (C18:3 c9t11c13) present at up to 83% in pomegranate seed oil, has been shown to exert anti-cancer effects, although the mechanism behind its cytotoxicity remains unclear. Ferroptosis, a cell death triggered by an overwhelming accumulation of lipid peroxides, has recently arisen as a potential mechanism underlying CLnA cytotoxicity. In the present study, we show that PunA is highly cytotoxic to HCT-116 colorectal and FaDu hypopharyngeal carcinoma cells grown either in monolayers or as three-dimensional spheroids. Moreover, our data indicate that PunA triggers ferroptosis in carcinoma cells. It induces significant lipid peroxidation and its effects are prevented by the addition of ferroptosis inhibitors. A combination with docosahexaenoic acid (DHA), a known polyunsaturated fatty acid with anticancer properties, synergistically increases PunA cytotoxicity. Our findings highlight the potential of using PunA as a ferroptosis-sensitizing phytochemical for the prevention and treatment of cancer.     

The effect of green tea extract and EGCG on the signaling network in squamous cell carcinoma

Green tea and its major active component, epigallocatechin-3-gallate (EGCG), have been reported to have anticancer activity on various cancers. However, the exact molecular mechanism of its anticancer activity is still not well understood. We investigated the anticancer activity of green tea extract (GTE) and EGCG on 3 human squamous carcinoma cell lines (CAL-27, SCC-25, and KB) in vitro. We also examined the effects of GTE and EGCG on cell signaling networks using our newly developed Pathway Array technology, which is an innovative proteomic assay to globally screen changes in protein expression and phosphorylation. Our results demonstrated that GTE and EGCG inhibited all 3 squamous carcinoma cells' growth via S and G(2)/M phase arrest, but different sensitivities to GTE and EGCG in different cell lines were observed: CAL-27 cells were more sensitive to the both agents than SCC-25 and KB cells, and GTE at an EGCG equivalent concentration displayed a stronger inhibition than EGCG alone. The Pathway Array assessment of 107 proteins indicated that different signaling pathways were activated in different cell lines, suggesting heterogeneity at the signaling network level. After treatment with GTE or EGCG, a total of 21 proteins and phosphorylations altered significantly in all 3 cell lines based on analysis of variance (ANOVA) (P < 0.05). The major signaling pathways affected by GTE and EGCG were EGFR and Notch pathways, which, in turn, affected cell cycle-related networks. These results suggested that GTE and EGCG target multiple pathways or global networks in cancer cells, which resulted in collective inhibition of cancer cell growth. The finding pointed out the future direction to study the underlying mechanism of the chemotherapeutic and chemopreventive activities of EGCG and GTE.     

Sensitization by wortmannin of heat- or X-ray induced cell death in cultured Chinese hamster V79 cells

Here we found that wortmannin sensitized Chinese hamster V79 cells to hyperthermic treatment at 44.0 degrees C as determined either by colony formation assay or by dye exclusion assay. Wortmannin enhanced heat-induced cell death accompanying cleavage of poly (ADP-ribose) polymerases (PARP). Additionally, the induction of heat shock protein HSP70 was suppressed and delayed in wortmannin-treated cells. Heat sensitizing effect of wortmannin was obvious at more than 5 or 10 microM of final concentrations, while radiosensitization was apparent at 5 microM. Requirement for high concentration of wortmannin, i.e., order of microM, suggests a possible role of certain protein kinases, such as DNA-PK and/or ATM among PI3-kinase family. The sensitization was minimal when wortmannin was added at the end of heat treatment. This was similar to the case of X-ray. Since heat-induced cell death and PARP cleavage preceded HSP70 induction phenomenon, the sensitization to the hyperthermic treatment was considered mainly caused by enhanced apoptotic cell death rather than secondary to suppression or delay by wortmannin of HSP70 induction. Further, in the present system radiosensitization by wortmannin was also at least partly mediated through enhancement of apoptotic cell death.     

Capsaicin Induces Apoptosis of Cisplatin-Resistant Stomach Cancer Cells by Causing Degradation of Cisplatin-Inducible Aurora-A Protein

Various chemotherapeutic agents such as cisplatin have been used to treat gastric cancer. However, a substantial number of patients acquire resistance to this treatment, and this is followed by rapid relapse of the disease. We investigated the anticancer effect of capsaicin, the active ingredient in red pepper, in the cisplatin-resistant Korean human gastric cancer cell line SNU-668. We found that treatment of SNU-668 cells with capsaicin in combination with cisplatin induced higher apoptotic cell death than that of treatment with either capsaicin orcisplatin alone. Furthermore, we discovered that Aurora-A protein increased in response to cisplatin and was degraded upon combined treatment with capsaicin with cisplatin, suggesting that the Aurora-A-mediated signaling pathway is responsible for the resistance to cisplatin in cisplatin-resistant gastric cancer cell lines. Combined treatment with capsaicin and cisplatin induced G1/S arrest, whereas cisplatin alone caused accumulation in G2/M. Combined treatment with capsaicin and cisplatin inhibited IκB phosphorylation in a dose-dependent manner, suggesting that Aurora-A directly or indirectly regulates NF-κB translocation. We propose that combined administration of cisplatin and capsaicin may provide a strategy for overcoming cisplatin resistance.     

1 - 硝基芘对GC - 2细胞的损伤效应及AhR信号通路的活化

目的 研究1 - 硝基芘（1 - nitropyrene, 1 - NP）对小鼠精母细胞株GC - 2的损伤效应及芳香烃受体（aryl hydrocarbon receptor, AhR）信号通路的影响。方法 建立不同剂量1 - NP染毒的GC - 2细胞模型，采用CCK - 8法检测细胞活性，流式细胞术检测细胞周期，Western blot分析各组细胞DNA双链断裂损伤标志物γ - H2AX、DNA损伤反应通路蛋白以及AhR通路蛋白的表达。实时荧光定量PCR检测细胞色素450 (CYP)1a1和1b1 mRNA表达水平。结果 1 - NP处理可导致GC - 2细胞活性降低及G2/M期细胞比例升高，同时诱导γ - H2AX蛋白表达升高，DNA损伤反应及细胞周期G2/M期检测点蛋白ATM、Chk1、Cdc25c、Cdc2的磷酸化表达水平升高，Cyclin B1表达降低。1 - NP染毒也提高了GC - 2细胞中AhR核蛋白及下游靶基因CYP1A1的蛋白表达，提高了Cyp1a1和Cyp1b1的转录表达水平。结论 1 - NP暴露造成小鼠生精细胞的DNA损伤、细胞周期阻滞和细胞活性抑制，其效应可能与AhR信号通路的活化及对化学物的代谢活化有关。     

Mechanisms of benzene-induced hematotoxicity and leukemogenicity: cDNA microarray analyses using mouse bone marrow tissue

Although the mechanisms underlying benzene-induced toxicity and leukemogenicity are not yet fully understood, they are likely to be complicated by various pathways, including those of metabolism, growth factor regulation, oxidative stress, DNA damage, cell cycle regulation, and programmed cell death. With this as a background, we performed cDNA microarray analyses on mouse bone marrow tissue during and after a 2-week benzene exposure by inhalation. Our goal was to clarify the mechanisms underlying the hematotoxicity and leukemogenicity induced by benzene at the level of altered multigene expression. Because a few researchers have postulated that the cell cycle regulation mediated by p53 is a critical event for benzene-induced hematotoxicity, the present study was carried out using p53-knockout (KO) mice and C57BL/6 mice. On the basis of the results of large-scale gene expression studies, we conclude the following: (a) Benzene induces DNA damage in cells at any phase of the cell cycle through myeloperoxidase and in the redox cycle, resulting in p53 expression through Raf-1 and cyclin D-interacting myb-like protein 1. (b) For G1/S cell cycle arrest, the p53-mediated pathway through p21 is involved, as well as the pRb gene-mediated pathway. (c) Alteration of cyclin G1 and Wee-1 kinase genes may be related to the G2/M arrest induced by benzene exposure. (d) DNA repair genes such as Rad50 and Rad51 are markedly downregulated in p53-KO mice. (e) p53-mediated caspase 11 activation, aside from p53-mediated Bax gene induction, may be an important pathway for cellular apoptosis after benzene exposure. Our results strongly suggest that the dysfunction of the p53 gene, possibly caused by strong and repeated genetic and epigenetic effects of benzene on candidate leukemia cells, may induce fatal problems such as those of cell cycle checkpoint, apoptosis, and the DNA repair system, finally resulting in hemopoietic malignancies. Our cDNA microarray data provide valuable information for future investigations of the mechanisms underlying the toxicity and leukemogenicity of benzene.     

Response of cell cycle/stress-related protein expression and DNA damage upon treatment of CaCo2 cells with anthocyanins

Anthocyanins are a class of flavonoids, widely spread throughout the plant kingdom, exhibiting important antioxidant and anti-inflammatory actions as well as chemotherapeutic effects; nonetheless, little is known about the molecular mechanisms by which these activities are exerted. The present study is aimed at investigating molecular mechanisms involved in the chemotherapeutic effects induced by both cyanidin-3-O-beta glucopyranoside (CY3G) and its aglycon form, cyanidin chloride (CY), in human colon cancer cells (CaCo2). The effect on cell growth, reactive oxygen species (ROS) formation and cell cycle/stress proteins modification, including ataxia teleangectasia mutated protein (ATM), p53, p21, 8-oxoguanine DNA glycosylase (OGG1), 70 kDa heat shock protein (HSP70) and topoisomerase IIbeta, as well as on DNA fragmentation, was determined. CY and CY3G treatment affect cell growth and cell proliferation, this latter in a moderately dose-dependent way. Interestingly, ROS level is decreased by any concentration of CY and, only at the lowest concentration, by CY3G. Moreover, the two molecules exert their activities increasing ATM, topoisomerase II, HSP70 and p53 expression. The analysis of DNA fragmentation by Comet assay evidences: (1) a dose-dependent increase in DNA damage only after treatment with CY3G; (2) a more evident trend in the DNA fragmentation when the treatment is performed on agarose embedded cells (cellular atypical Comet); (3) a highly dose-dependent DNA fragmentation induced by CY when the treatment is carried out on agarose embedded naked DNA (acellular atypical Comet). The present findings substantiate a possible chemotherapeutic role of anthocyanins and suggest that CY and CY3G act on CaCo2 by different mechanisms, respectively, ROS-dependent and ROS-independent.     

Capsaicin induces apoptosis of cisplatin-resistant stomach cancer cells by causing degradation of cisplatin-inducible Aurora-A protein

Various chemotherapeutic agents such as cisplatin have been used to treat gastric cancer. However, a substantial number of patients acquire resistance to this treatment, and this is followed by rapid relapse of the disease. We investigated the anticancer effect of capsaicin, the active ingredient in red pepper, in the cisplatin-resistant Korean human gastric cancer cell line SNU-668. We found that treatment of SNU-668 cells with capsaicin in combination with cisplatin induced higher apoptotic cell death than that of treatment with either capsaicin or cisplatin alone. Furthermore, we discovered that Aurora-A protein increased in response to cisplatin and was degraded upon combined treatment with capsaicin with cisplatin, suggesting that the Aurora-A-mediated signaling pathway is responsible for the resistance to cisplatin in cisplatin-resistant gastric cancer cell lines. Combined treatment with capsaicin and cisplatin induced G1/S arrest, whereas cisplatin alone caused accumulation in G2/M. Combined treatment with capsaicin and cisplatin inhibited IκB phosphorylation in a dose-dependent manner, suggesting that Aurora-A directly or indirectly regulates NF-κB translocation. We propose that combined administration of cisplatin and capsaicin may provide a strategy for overcoming cisplatin resistance.