Exacerbation of diabetes-induced testicular apoptosis by zinc deficiency is most likely associated with oxidative stress, p38 MAPK activation, and p53 activation in mice

Since diabetes induces testicular oxidative damage and cell death, and zinc (Zn) plays an important role in the spermatogenesis, the objective of the present study was to define the effects of Zn deficiency on diabetes-induced testicular apoptosis and associated mechanisms. Zn deficiency was induced by chronic treatment of normal and diabetic mice with N,N,N',N'-tetrakis (2-pyridylemethyl) ethylenediamine (TPEN) chelation. After diabetes onset, mice were given intraperitoneally TPEN at 5mg/kg daily for four months, which, like diabetes, induced a significant decrease in testicular Zn level. TUNEL staining revealed that testicular apoptosis was significantly increased along with an increased Bax/Bcl-2 ratio, in diabetic mice and TPEN-treated normal mice. Zn deficiency significantly exacerbated diabetes-induced testicular apoptosis, along with significantly increased oxidative and nitrosative damage and down-regulation of antioxidant Nrf2 expression. Increased oxidative stress was associated with an increase in activation of p38 MAPK and p53 protein in diabetic testis, which was worsened in the testes of diabetic mice with Zn deficiency. Diabetes also induced a significant increase in endoplasmic reticulum stress and associated cell death, which was not affected by Zn deficiency. These results suggest that like diabetes, chronic depletion of Zn with TPEN induces testicular oxidative stress and damage, along with the activation of p38 MAPK and p53 signaling and mitochondria-related apoptotic cell death. Therefore, prevention of Zn deficiency for diabetic patients is important in order to avoid the exacerbation of diabetic effects on testicular cells death.     

Repetitive exposures to low-dose X-rays attenuate testicular apoptotic cell death in streptozotocin-induced diabetes rats

To define whether repetitive exposures to low-dose radiation (LDR) can attenuate diabetes-induced testicular cell death, Type 1 diabetic rats were produced by single injection of streptozotocin (STZ). Once hyperglycemia was diagnosed, diabetic rats were treated with and without LDR (25 and 50 mGy X-rays) daily for 4 weeks. Eight and 12 weeks after diabetes onset, testicular apoptotic cell death was examined by flow cytometry with Annexin V/PI staining, Western blotting assay for caspase-3 cleavage, and TUNEL staining for localization of apoptotic cells. Diabetes induced a significant increase in testicular apoptotic cell death, which was able to be attenuated by repetitive exposures to LDR. Diabetes-induced testicular cell death was associated with increased mitochondrial dysfunction, shown by the decreased mitochondrial potential and increased expressions of Bax mRNA and protein. All these changes were significantly attenuated in certain extends by repetitive exposures to LDR. To investigate the mechanisms by which LDR attenuates diabetes-induced testicular apoptotic cell death, serum sex hormone (testosterone, luteinizing hormone and follicle stimulating hormone) levels, and both serum and testicular oxidative damage (lipid peroxides) and antioxidant contents (superoxide dismutase, catalase and glutathione) were measured. Serum sex hormones were significantly decreased in diabetic rats, but not significantly in diabetic rats with multiple exposures to LDR; serum and testicular oxidative damage was significantly increased along with significant decreases in serum and testicular antioxidants in diabetic rats; however, these changes were significantly prevented by repetitive exposures to LDR. Furthermore, diabetic effects on the testicular oxidative damage and cell death were all attenuated by antioxidant N-acetylcysteine. These results suggest that diabetes-induced testicular cell death is probably mediated by increased oxidative stress. LDR protection from diabetes-induced testicular cell death is most likely mediated by its preserving antioxidants.     

Effects of Zn deficiency,antioxidants, and low-dose radiation on diabetic oxidative damage and cell death in the testis

Infertility is one of the common complications in diabetic men and mainly due to the loss of germ cells by apoptotic cell death. Although several mechanisms have been proposed to explain the induction of testicular cell death by diabetes, diabetic induction of testicular oxidative stress and damage may be the predominant mechanism responsible for the testicular cell death in diabetes. To explore whether factors that either increase or decrease the testicular oxidative stress and damage will enhance or prevent diabetes-induced testicular cell death, the effect of zinc (Zn) deficiency on diabetes-induced cell death has been examined since Zn was found to play an important role in the protection of testis from oxidative stress and damage. Zn deficiency, induced by its chelator N,N,N,N-Tetrakis(2-pyridylmethyl)-1,2-ethylenediamine, was found to exacerbate diabetes-induced testicular oxidative damage and cell death. In contrast, treatment of diabetic rats with antioxidant N-acetylcysteine or low-dose radiation that can up-regulate endogenous antioxidants significantly attenuated diabetes-induced testicular cell death. These results suggest that diabetes-induced testicular cell death that may eventually cause men’s infertility is predominantly mediated by the oxidative stress and damage. To prevent or delay diabetes-caused infertility, diabetic patients should avoid Zn deficiency, and might consider antioxidant supplementation.     

白术内酯Ⅰ对人胃癌细胞SGC-7901裸鼠移植瘤生长及凋亡的影响

目的：研究白术内酯Ⅰ（atractylenolide Ⅰ）对人胃癌细胞SGC-7901裸鼠移植瘤生长及凋亡相关蛋白Bax、cleaved caspase-3、p53、Bcl-2表达的影响。方法：建立SGC-7901裸鼠移植瘤模型,观察白术内酯Ⅰ对肿瘤生长的影响;TUNEL法检测移植瘤组织中的细胞凋亡;Western blotting检测瘤组织中Bax、Bcl-2、cleaved caspase-3及p53蛋白表达。结果：白术内酯Ⅰ不同程度抑制裸鼠SGC-7901移植瘤的生长,与对照组比较,给药后肿瘤体积（TV,tumor volume）、相对肿瘤体积（RTV,relative tumor volume）和相对肿瘤增殖率[T/C（%）,T_RTV/C_RTV]明显下降;移植瘤组织中凋亡细胞明显增多;白术内酯Ⅰ上调移植瘤组织中Bax、cleaved caspase-3及p53的蛋白表达,下调Bcl-2 的蛋白表达。结论：白术内酯Ⅰ能明显抑制人胃癌细胞SGC-7901裸鼠移植瘤的生长,分子机制主要包括增加Bax、cleaved caspase-3、p53蛋白表达,减少Bcl-2蛋白表达,最终导致肿瘤细胞凋亡。     

Preventive effect of non-mitogenic acidic fibroblast growth factor on diabetes-induced testicular cell death

Fibroblast growth factor (FGF)-1 was found to protect the heart from oxidative damage, but clinically its long-term use was restricted for its undesirable proliferating activity on cells. Thus a cluster of amino acids responsible for the proliferation were deleted in the native FGF-1 to create a non-mitogenic FGF-1 (nmFGF-1). Whether the nmFGF-1 protects male germ cells from diabetes-induced apoptotic death was examined in diabetic mice induced with multiple low-doses of streptozotocin, followed by nmFGF-1 treatment for 6 months. Diabetic mice showed a decrease in testicular weight and an increase in apoptotic cell death. Treatment with nmFGF-1 alleviated the diabetic effects on testicular weight and apoptotic cell death. Mechanistically, nmFGF-1 may alleviate diabetes-induced germ cell death by decreasing the BAX/Bcl-2 ratio and endoplasmic reticulum stress as well as associated cell death, which is associated with Nrf-2 activation.     

Protection by doxycycline against doxorubicin-induced oxidative stress and apoptosis in mouse testes

Spermatogenic cells constitute one of the body tissues that are susceptible to doxorubicin-induced oxidative stress and apoptosis. To explore whether doxorubicin toxicity to these male germ cells could be prevented by adjuvant medication, this study was designed to examine the possible ameliorating action of doxycycline, an antibiotic with anti-oxidant property, on doxorubicin-induced oxidative and apoptotic effects in mouse testes. Male mice at 5-week of age were treated with vehicles, doxorubicin alone (3 mg/kg, i.p. every other day for 3 doses), doxycycline alone (2.5 mg/kg, i.p. every other day for 3 doses), or doxycycline plus doxorubicin (each dose given 1 day post-doxycycline). After 28 days, mice treated with doxorubicin alone displayed smaller body and testicular weights, reduced sperm counts, impaired spermatogenic capability (scarcer spermatids and spermatocytes), increased oxidative stress (malondialdehyde levels), decreased anti-oxidant activity (superoxide dismutase and glutathione peroxidase), and elevated apoptotic indexes (upregulation of Bax and Bad, downregulation of Bcl-2 and Bcl-xL, release of cytochrome c from mitochondria to cytosol, activation of caspase-3, and increase of cleaved caspase-3 abundance and TUNEL positive cells), while doxycycline pretreatment could effectively prevent nearly all of these abnormalities. These results provide firm evidence that doxycycline pretreatment would offset the oxidative and apoptotic impact imposed by doxorubicin, and imply doxycycline to be a promising adjuvant agent that may attenuate the toxicity of doxorubicin on testicular tissues in clinical practice.     

FGF10 and FGF21 as regulators in adipocyte development and metabolism

The FGF family comprises twenty-two evolutionarily related members with diverse functions in development, metabolism, and neuronal activities. FGF10 and FGF21 play unique roles in adipocyte development and metabolism, respectively. FGF10 mediates biological responses by activating FGF receptor 2b (FGFR2b) with heparin/heparan sulfate in a paracrine manner. In contrast, FGF21 mediates biological responses by activating FGFRs with βKlotho in cultured cells. However, FGF21 acts in an autocrine manner via a β Klotho-independent signaling pathway in mice. Fgf10 knockout mice die shortly after birth. Preadipocyte proliferation and adipogenesis are greatly impaired in Fgf10 knockout mouse embryos. FGF10 stimulates preadipocyte proliferation through the Ras/MAPK pathway followed by the cyclin D2-dependent phosphorylation of p130. FGF10 also stimulates adipogenesis by inducing the expression of pRb through the Ras/MAPK pathway. pRb binds C/EBPα. The pRb-C/EBPα complex induces adipogenesis. Fgf21 is abundantly expressed in the liver. Hepatic Fgf21 expression is markedly induced in mice by fasting. FGF21 exerts pharmacological effects on glucose and lipid metabolism in hepatocytes and adipocytes. However, the phenotypes of Fgf21 knockout mice, which are apparently normal and fertile, indicate FGF21 not to be a physiological regulator for hepatic functions. Hepatic FGF21 inhibits lipolysis in adipocytes, and so is a negative regulator of lipolysis during fasting. FGF21 may be a "thrifty factor". Serum FGF21 levels are increased in patients with metabolic diseases related with obesity, indicating potential roles of FGF21 in adipocyte metabolism.     

维生素D对过氧化氢诱导MIN6细胞凋亡的保护作用

目的探讨维生素D(vitamin D,VitD)对过氧化氢(hydrogen peroxide,H 2O 2)诱导小鼠胰岛β细胞株MIN6细胞凋亡的保护作用及机制。方法VitD预处理后,用H 2O 2处理MIN6细胞,分别运用CCK-8法、Hoechst 33258荧光染色法、流式细胞术检测MIN6细胞增殖、形态及凋亡百分率。Western blot检测增殖与凋亡相关基因Bax、Bcl-2、Caspase-3以及Cleaved caspase-3的表达。结果H 2O 2呈时间和剂量依赖性抑制MIN6细胞增殖,诱导细胞凋亡,降低Bcl-2表达、增加Bax及Cleaved caspase-3表达,Bcl-2/Bax比值降低,Cleaved caspase-3/caspase-3比值增加;当用VitD预处理后,Bcl-2表达增加,Bax、Cleaved caspase-3表达降低,Bcl-2/Bax比值增加,Cleaved caspase-3/caspase-3比值降低,MIN6细胞活力增加。结论VitD预处理后,通过增加抗凋亡Bcl-2表达,降低促凋亡Bax和Cleaved caspase-3表达,减少由H 2O 2诱导的小鼠胰岛β细胞株MIN6细胞凋亡。     

Molecular mechanism on the testicular toxicity of 1,3-dinitrobenzene in Sprague-Dawley rats: preliminary study

The present study was conducted to elucidate the possible molecular mechanism of germinal cell apoptosis induced by Sertoli cell damage after 1,3-dinitrobenzene (1,3-DNB), a testicular toxicant, was administered to laboratory male rats. In this study, male Sprague-Dawley rats were administered with a single oral dose of 1,3-DNB (25 mg/kg body weight). Histopathological examinations and TUNEL methods revealed a marked increase in the number of apoptotic pachytene spermatocytes in seminiferous tubules showing stages VII–VIII and IX–XI of the spermatogenic cycle at 24 h after 1,3-DNB treatment. In immunohistochemical analysis, the cytoplasm and nuclei of pachytene spermatocytes were sometimes stained with antibodies to Bax and cleaved caspase-3 at 24 h after treatment. RT-PCR analysis for apoptosis-related gene expression showed that the expression of Bax,Bcl-2, Bcl-xL, and Bcl-xs genes, which are implicated in mitochondrial pathway, was significantly upregulated in the testes of the treated rats. These results suggest that the mitochondrial pathway is mainly involved in the testicular germinal cell apoptosis in rats induced by 1,3-DNB.     

线粒体融合素2通过Ras-PI3K-Akt信号途径抑制缺血再灌注诱导的乳鼠心肌细胞凋亡

目的：研究线粒体融合素2（Mfn2）基因对缺血再灌注诱导的乳鼠心肌细胞凋亡的影响及其相关的信号通路。方法：乳鼠心肌细胞经缺氧/复氧（H/Re）处理模拟心肌缺血再灌注损伤。用Mfn2基因的重组腺病毒（Adv-Mfn2）感染经缺氧复氧处理的乳鼠心肌细胞。采用TUNEL染色、ELISA、流式细胞术等方法检测Mfn2对缺血再灌注诱导的乳鼠心肌细胞凋亡的影响。Western blot分析线粒体凋亡路径中Bcl-2蛋白、Bax蛋白、Caspase-9以及磷酸化蛋白激酶B（p-Akt）的表达变化。结果：TUNEL染色发现Adv-Mfn2感染乳鼠心肌细胞后,细胞凋亡较H/Re组和Adv-LacZ组显著减少。ELISA和流式细胞仪检测结果表明,Adv-Mfn2组心肌细胞凋亡较H/Re组及Adv-LacZ组明显减少,且这一作用呈时间依赖性。Western blot结果显示,Adv-Mfn2组中Bcl-2蛋白表达较H/Re组和Adv-LacZ感染组上升,Bax蛋白表达下降,各组中Caspase-9的表达变化与Bax相同,Adv-Mfn2组的p-Akt蛋白表达水平则较H/Re组和Adv-LacZ感染组明显上升。结论：Mfn2基因主要通过正向调控RasPI3K-Akt信号通路,促进Akt的磷酸化水平,使Bcl-2蛋白表达量增加,Bax蛋白表达量降低,抑制Caspase-9活化,从而抑制缺血再灌注诱导的乳鼠心肌细胞凋亡。     

Rutin from Lonicera japonica inhibits myocardial ischemia/reperfusion-induced apoptosis in vivo and protects H9c2 cells against hydrogen peroxide-mediated injury via ERK1/2 and PI3K/Akt signals in vitro

We investigated pharmacological effects of rutin isolated form Lonicera japonica on H₂O₂-induced cell death in H9c2 cells in vitro and rat myocardial ischemia-reperfusion injury model in vivo. Western blot analysis showed that H₂O₂ increased expression of cleaved form of caspase-3 and proapoptotic Bax protein, but decreased antiapoptotic Bcl-2 protein in H9c2 cell. However, treatment with rutin decreased expression of both cleaved from of caspase-3 and increased Bcl-2/Bax ratio in H9c2 cells. The protective effect of rutin was inhibited not by JNK inhibitor or p38 MAPK inhibitor but by PI3K inhibitor or ERK inhibitor. Rutin increased phosphorylation of ERK and Akt in H9c2 cells. These anti-apoptotic effects of rutin were confirmed both by annexin-V and TUNEL assay. Furthermore, rutin improved I/R-induced myocardial contractile function and reduced infarct size. Rutin administration also inhibited apoptosis in myocardial tissues in I/R rats by increasing Bcl-2/bax ratio and decreasing active caspase-3 expression. These results suggest that rutin reduced oxidative stress-mediated myocardial damage in vitro model and in vivo model, which might be useful in treatment of myocardial infarction.     

人参皂苷Rg1对小鼠1—甲基—4—苯基—1，2，3，6—四氢吡啶诱导的黑质神经元凋亡的保护作用

目的:探讨人参皂苷Rg1对抗1-甲基-4-苯基-1,2,3,6-四氢吡啶(MPTP)诱导的C57BL小鼠黑质神经元凋亡的可能机制.方法:MPTP(30 mg·kg~(-1)·d~(-1)×5 d)腹腔注射制备C57BL小鼠帕金森病模型,同时预防组分别以不同剂量人参皂苷Rg1(2.5、5.0、10.0 mg·kg~(-1)·d~(-1)×8 d)于MPTP注射前预先腹腔注射小鼠.用Nissl染色和TH组化染色观察黑质损害情况,TUNEL染色检测细胞凋亡,同时运用免疫组织化学方法检测caspase-3的活性片段以及Bcl-2、Bcl-xl、Bax、iNOS和 nNOS的表达情况.结果:人参皂苷Rg1(5.0和10.0 mg/kg)预处理能使黑质致密带Nissl阳性神经元和TH阳性神经元的脱失减少,同时降低了TUNEL阳性率,并伴有Bcl-2和Bcl-xl表达增加,Bax和iNOS表达减少以及抑制caspase-3的激活.结论:人参皂苷Rg1预处理对MPTP诱导的小鼠黑质神经元凋亡有明显的保护作用,其作用可能是通过降低iNOS和Bax蛋白表达,增加Bcl-2和Bcl-xl蛋白表达以及抑制caspase-3的激活来实现的.     

Endoplasmic reticulum stress in murine liver and kidney exposed to microcystin-LR

To investigate the effect of microcystin-LR (MC-LR) on apoptosis based on the endoplasmic reticulum stress (ERS) pathway in mouse liver and kidney, male ICR mice were intraperitoneally injected with 20 μg kg⁻¹ body weight MC-LR for 21 days, and mRNA and protein levels of ERS special molecules in liver and kidney were analyzed using quantitative real-time PCR and western blotting. MC-LR significantly improved mRNA and protein expression of C/EBP homologous protein (CHOP) and cleaved caspase-12 in liver, whereas it inhibited expression of CHOP and caspase-12 in kidney. MC-LR also induced significant down-regulation of B-cell lymphoma/leukemia-2 (Bcl-2) mRNA expression in liver and weak up-regulation in kidney. These results indicated the involvement of the ERS pathway in MC-LR-induced apoptosis of hepatic cells but not in renal cells of mice. The weight changes and histological damage of liver and kidney were in accordance with the appearance of ERS. Our results indicate that ERS plays an important role in hepatic cell apoptosis induced by MC-LR, and is considered as a new pathway of liver toxicity. Its relative special genes might be considered as potentially new biomarkers used for risk assessment of MC-LR in the environment.     

长链非编码 RNA HOTAIR 影响人舌鳞癌细胞 Tb3.1 增殖与凋亡的体内外研究

目的 研究长链非编码 RNA HOTAIR 对人舌鳞癌细胞系 Tb3.1 增殖与凋亡的影响 。 方法 使用 HOTAIR siRNA（siHOTAIR）敲低 HOTAIR 的表达; 实验分为 siHOTAIR 组、无义序列组和空白对照组。 前 2 组分别用 siHOTAIR 和无义序列转染舌鳞癌细胞, 空白对照组细胞不做任何处理。 实时定量 PCR 检测 HOTAIR 的表达水平; 四甲基偶氮唑蓝（MTT）法检测 Tb3.1 细胞增殖; Western blot 检测 B 细胞淋巴瘤 2（Bcl-2）、活化型半胱氨酸天冬氨酸蛋白酶-3（Cleaved Caspase-3）、BAX 的表达; 流式细胞仪检测细胞凋亡; 平板克隆形成实验检测细胞增殖情况;并行细胞衰老检测 。 动物实验建立 Tb3.1 裸鼠皮下荷瘤模型, 通过免疫组织化学染色及 TUNEL 法评价干扰 HOTAIR 后对 Tb3.1 细胞增殖、凋亡的作用。 结果 siHOTAIR 处理后 HOTAIR 的表达水平降低; Western blot 结果示 Cleaved Caspase-3 和 BAX 表达水平升高, Bcl-2 表达水平降低。 MTT 结果显示 siHOTAIR 组细胞增殖受到抑制;流式细胞示 siHOTAIR 组细胞凋亡升高; 细胞衰老实验显示 siHOTAIR 组细胞衰老数目增加; 免疫组化结果显示, siHOTAIR 组较对照组 Ki-67、Bcl-2 表达减少, Caspase-3、BAX 表达增加; TUNEL 结果显示, siHOTAIR 组较空白对照组肿瘤细胞凋亡水平升高。 结论 干扰 HOTAIR 可以促进舌鳞癌细胞的凋亡并抑制其增殖, HOTAIR 可以作为舌鳞癌治疗的研究方向。     

Apoptotic effects of cigarette smoke extracts on mouse embryonic stem cells via oxidative stress

Previous studies have reported that cigarette smoke and cigarette smoke extract (CSE) have negative effects on embryonic development. However, no studies have investigated the mechanism through which CSE affects the cellular signaling pathway leading to apoptosis and oxidative stress in embryonic cells, or how the two pathways are cross‐linked. Thus, we studied the effects of CSE on apoptosis and oxidative stress in mouse embryonic stem cells (mESCs). Specifically, we measured changes in cell viability in response to CSEs (3R4F and two domestic cigarettes CSE 1 and 2) using a water soluble tetrazolium (WST) assay and a neutral red uptake (NRU) assay, which revealed that cell viability decreased in a concentration‐dependent manner. Western blot analysis revealed that the expression of cyclin D1 and cyclin E1 was decreased and that of p21 and p27 was increased by CSE. Additionally, the number of terminal deoxynucleotidyl transferase (TUNEL)‐stained cells was increased by CSE, while the levels of Bax and Caspase‐3 increased and Bcl‐2 decreased. Moreover, a 2′,7′‐dichlorofluorescin diacetate (DCF‐DA) assay and reactive oxygen species (ROS)‐Glo H₂O₂ assay confirmed that ROS were generated in response to CSE and that they were associated with up‐regulated Keaf‐1 and CHOP. Overall, the results revealed that cigarette smoke extract (CSE) inhibited cell proliferation by regulating cell cycle‐related protein expression and increased oxidative stress by regulating the expression of Kelch‐like ECH‐associated protein 1 (Keap‐1) and CCAAT/enhancer‐binding protein homologous protein (CHOP), resulting in apoptosis in mESCs.     

双去甲氧基姜黄素对小鼠乳腺癌的抗肿瘤作用及机制

目的　本研究旨在研究双去甲氧基姜黄素（bisdesmethoxycurcumin,BDMC）对小鼠乳腺癌的影响及机制。方法　采用小鼠乳腺癌4T1细胞,分为Control组及不同剂量（3、9、27 μM）BDMC组,通过CCK8法检测BDMC对小鼠乳腺癌4T1细胞增殖的影响,TUNEL染色检测BDMC对4T1细胞凋亡的影响,Western blot检测BDMC对4T1细胞Bax、Bcl-2及cleaved caspase-3表达的影响;采用4T1乳腺癌荷瘤小鼠模型,分为Control组及不同剂量（10、30 mg/kg）BDMC组,检测BDMC对小鼠肿瘤体积及体质量的影响,Western blot检测BDMC对乳腺癌小鼠肿瘤组织Bax、Bcl-2及cleaved caspase-3表达的影响。采用单因素方差分析。结果　与Control组相比,9、27 μM BDMC均能明显抑制4T1细胞增殖（均P<0.01）,促进其凋亡（均P<0.01）,同时上调细胞Bax/Bcl-2比值及cleaved caspase-3表达（均P<0.01）;10、30 mg/kg BDMC均能明显抑制乳腺癌小鼠肿瘤体积的增长（均P<0.05）,同时明显上调肿瘤组织Bax/Bcl-2比值及cleaved caspase-3表达（均P<0.05）,但对体质量无明显影响。结论　BDMC对乳腺癌小鼠模型具有明显的抗肿瘤作用,其机制与激活线粒体凋亡通路有关。     

Oxidative stress induction by T-2 toxin causes DNA damage and triggers apoptosis via caspase pathway in human cervical cancer cells

T-2 toxin is the most toxic trichothecene and both humans and animals suffer from several pathological conditions after consumption of foodstuffs contaminated with trichothecenes. We investigated the molecular mechanism of T-2 toxin induced cytotoxicity and cell death in HeLa cells. T-2 toxin at LC50 of 10 ng/ml caused time dependent increase in cytotoxicity as assessed by dye uptake, lactatedehydrogenase leakage and MTT assay. The toxin caused generation of reactive oxygen species as early as 30 min followed by significant depletion of glutathione levels and increased lipid peroxidation. The results indicate oxidative stress as underlying mechanism of cytotoxicity. Single stranded DNA damage after T-2 treatment was observed as early as 2 and 4 h by DNA diffusion assay. The cells exhibited apoptotic morphology like condensed chromatin and nuclear fragmentation after 4 h of treatment. Downstream of T-2 induced oxidative stress and DNA damage a time dependent increase in expression level of p53 protein was observed. The increase in Bax/Bcl2 ratio indicated shift in response, in favour of apoptotic process in T-2 toxin treated cells. Western blot analysis showed increase in levels of mitochondrial apoptogenic factors Bax, Bcl-2, cytochrome-c followed by activation of caspases-9, -3 and -7 leading to DNA fragmentation and apoptosis. In addition to caspase-dependent pathway, our results showed involvement of caspase-independent AIF pathway in T-2 induced apoptosis. Broad spectrum caspase inhibitor z-VAD-fmk could partially protect the cells from DNA damage but could not inhibit AIF induced oligonucleosomal DNA fragmentation beyond 4 h. Results of the study clearly show that oxidative stress is the underlying mechanism by which T-2 toxin causes DNA damage and apoptosis.     

Gallic Acid Hindered Lung Cancer Progression by Inducing Cell Cycle Arrest and Apoptosis in A549 Lung Cancer Cells via PI3K/Akt Pathway

This study elucidates the anti-cancer potential of gallic acid (GA) as a promising therapeutic agent that exerts its effect by regulating the PI3K/Akt pathway. To prove our research rationale, we used diverse experimental methods such as cell viability assay, colony formation assay, tumor spheroid formation assay, cell cycle analysis, TUNEL assay, Western blot analysis, xenograft mouse model and histological analysis. Treatment with GA inhibited cell proliferation in dose-dependent manner as measured by cell viability assay at 48 h. GA and cisplatin (CDDP) also inhibited colony formation and tumor spheroid formation. In addition, GA and CDDP induced apoptosis, as determined by the distribution of early and late apoptotic cells and DNA fragmentation. Western blot analysis revealed that inhibition of the PI3K/Akt pathway induced upregulation of p53 (tumor suppressor protein), which in turn regulated cell cycle related proteins such as p21, p27, Cyclin D1 and E1, and intrinsic apoptotic proteins such as Bax, Bcl-2 and cleaved caspase-3. The anti-cancer effect of GA was further confirmed in an in vivo mouse model. Intraperitoneal injection with GA for 4 weeks in an A549-derived tumor xenograft model reduced the size of tumor mass. Injection of them downregulated the expression of proliferating cell nuclear antigen and p-Akt, but upregulated the expression of cleaved caspase-3 in tumor tissues. Taken together, these results indicated that GA hindered lung cancer progression by inducing cell cycle arrest and apoptosis, suggesting that GA would be a potential therapeutic agent against non-small cell lung cancer.