丝裂霉素对体外胃癌细胞DNA损伤和增殖的影响

目的探讨丝裂霉素对体外胃癌细胞DNA损伤和增殖的影响。方法选用不同浓度丝裂霉素处理体外培养的胃癌细胞SGC-7901,利用免疫荧光和Western blot技术,分别检测γH2AX的焦点形成和蛋白水平变化;使用MTT法检测SGC-7901细胞的增殖情况。结果丝裂霉素的作用浓度和作用时间存在交互效应,除400 μg/ml外,平均γH2AX焦点数和焦点细胞率呈逐渐增加趋势（P<0.05）;400 μg/ml时,6 h组平均γH2AX焦点数和焦点细胞率低于4 h组,差异有统计学意义（P<0.05）。随丝裂霉素作用时间延长,γH2AX蛋白水平呈先升后降趋势,差异有统计学意义（P<0.05）。MTT结果显示,丝裂霉素对SGC-7901细胞的增殖有明显抑制作用（P<0.05）。结论γH2AX可敏感反应丝裂霉素对胃癌细胞DNA的损伤,丝裂霉素对体外胃癌细胞增殖抑制明显。     

p53和γ-H2AX作为乙醛引起DNA损伤早期生物标记物的实验研究

目的： 评价乙醛染毒p53野生型人类淋巴母细胞(TK6)后,细胞中DNA损伤标记物p53、γ-H2AX的表达变化,并与彗星试验中的DNA链断裂指标进行敏感性比较,探讨p53和γ-H2AX 作为乙醛引起DNA损伤的早期生物标记物的可能。方法：乙醛在0.5~20 mmol/L的浓度范围分别染毒TK6细胞20 min、2和12 h后,采用高通量的流式细胞术检测肿瘤抑制蛋白total-p53、磷酸化p53(p-p53)以及磷酸化组蛋白(γ-H2AX)的细胞表达率和表达强度(平均荧光强度);同时采用碱性彗星试验检测乙醛引起的DNA链断裂指标(细胞拖尾率、尾长、尾部DNA百分含量以及尾矩)的变化。结果：乙醛染毒TK6细胞12 h后,γ-H2AX的表达强度在15及20 mmol/L浓度下显著升高(P<0.05),p-p53的细胞表达率在0.5~7.5 mmol/L浓度范围内呈现剂量依赖的升高趋势,total-p53的细胞表达率趋势与p-p53相似,但与阴性对照组相比,差异无统计学意义。彗星试验中,细胞拖尾率、尾长、尾部DNA百分含量以及尾矩在5.0~12.5 mmol/L浓度范围内均增加,并呈现剂量依赖性。染毒2 h后,与阴性对照组相比,total-p53和p-p53的细胞表达率在15和20 mmol/L浓度下显著升高(P均<0.05),细胞拖尾率、尾部DNA百分含量以及尾矩在20 mmol/L浓度升高(P均<0.05)。染毒20 min后,3种生物标志物均未见清晰的变化趋势,4种DNA链断裂指标均未见显著变化(P均＞0.05)。结论：乙醛染毒TK6细胞12 h可诱导p-p53细胞表达率升高、γ-H2AX细胞表达强度升高、 total-p53细胞表达率轻微升高,以及细胞拖尾率、尾长、尾部DNA百分含量、尾矩的升高。p-p53比γ-H2AX和DNA链断裂指标在检测乙醛诱导的DNA损伤方面更加敏感。     

p53在调控DNA损伤所致MDA-MB-231细胞死亡中的作用及其机制

目的：研究p53在调控DNA损伤所致乳腺癌MDA-MB-231细胞死亡中发挥的作用及其相关机制。方法：采用5 J/m²短波紫外线UVC体外照射MDA-MB-231细胞建立DNA损伤模型,通过Western blot检测磷酸化H2AX以鉴定DNA损伤程度,并采用Westernblot检测细胞死亡相关蛋白p21、PARP、磷酸化p53和p53,以及核因子NF-90表达的变化。结果：与对照组比较,5 J/m² UVC处理细胞0.5 h后即检测到明显的H2AX磷酸化（P < 0.05）,表明成功建立了DNA损伤模型;同时,p21发生降解并持续保持低表达状态,p53开始发生磷酸化（p-p53增加,P < 0.05）,处理8 h后观察到PARP的剪切增加（P < 0.05）,而p53和NF-90蛋白表达未发现明显改变。结论：MDA-MB-231细胞通过p21-PARP途径发生死亡,而磷酸化p53的增加则可以促进细胞存活,从而抑制DNA损伤引起的细胞死亡。     

顺铂对bcr/abl转化BaF3-P210细胞DNA损伤与修复能力的影响

目的:研究顺铂(cisplatin,Cis)对白血病BaF3-MIGR1细胞和bcr/abl转化BaF3-P210细胞中DNA损伤修复能力的影响.方法:锥虫蓝染色法检测2种细胞经0.5、1、5、10、20和40 μg/mL Cis处理0、2、4、6、8、12、24和48 h时的存活率,免疫荧光法检测上述6种浓度Cis处理细胞8 h后诱导的γH2AX焦点数,Western印迹法检测DNA修复0、4、12和24 h后的γH2AX蛋白表达情况.结果:随着Cis处理时间和剂量增加,2种细胞的存活率降低,BaF3-P210转化细胞的存活率比BaF3-MIGR1细胞高(P<0.05);随着Cis剂量上升,2种细胞的γH2AX焦点数上升, BaF3-P210转化细胞的焦点数比BaF3-MIGR1细胞少(P<0.05);随着DNA修复时间延长,2种细胞的γH2AX蛋白表达均下调,BaF3-P210转化细胞的γH2AX蛋白表达量比BaF3-MIGR1细胞低.结论:Cis对BaF3-MIGR1细胞和BaF3-P210转化细胞的损伤呈时间、剂量效应,2种细胞的γH2AX焦点数与损伤之间存在剂量效应,bcr/abl可增强BaF3-P210转化细胞的DNA修复能力.     

lncRNA NEAT1 通过抑制DNA损伤促进肺腺癌PC-9 细胞的增殖

[摘要] 目的：研究长链非编码RNA核富集转录体1（lncRNA NEAT1）对肺腺癌PC-9 细胞增殖能力的影响,并初步探讨其作用机制。方法：qPCR 检测人肺腺癌PC-9 细胞与人胚肺二倍体2BS 细胞中lncRNA NEAT1 的表达水平;设计并合成lncRNA NEAT1 的小干扰RNA（siRNA）序列,采用脂质体法转染PC-9 细胞,通过qPCR 检测转染前后PC-9 细胞NEAT1 的表达水平。MTT法、流式细胞术分别检测lncRNA NEAT1 敲低对PC-9 细胞增殖及细胞周期的影响;WB检测转染前后DNA损伤相关蛋白,即共济失调毛细血管扩张突变蛋白（ATM）和双链DNA损伤标志物γ-H2AX的表达水平。结果：与2BS细胞相比,PC-9 细胞中lncRNA NEAT1 呈高表达（P<0.05）。成功建立NEAT1 敲低的PC-9 细胞,转染siRNA 12 h 后siNEAT1-1 及siNEAT1-2 干扰组细胞增殖能力较空白对照组及空转染组明显下降（P<0.05）;干扰组细胞周期被阻滞在G1 期［（88.97±2.64）%,（88.15±1.48）% vs（84.5±1.72）%,P<0.05］和G2/M期［（8.35±2.02）%（, 8.11±1.36）% vs（4.28±1.28）%,P<0.05］;干扰组细胞中DNA损伤相关蛋白ATM和γ-H2AX表达水平显著升高（均P<0.05）。结论：lncRNA NETA1 在肺腺癌PC-9 细胞呈高表达,其可通过抑制DNA损伤导致细胞周期G1/M期转变促进肺腺癌细胞PC-9 的增殖能力。     

X射线诱导γH2AX焦点形成的定量分析及其致DNA双链断裂的动态变化

目的 比较DNA依赖蛋白激酶催化亚基(DNA-PKcs^+/+)和DNA-PKcs^-/-小鼠胚胎成纤维细胞(MEF) X射线诱导γH2AX焦点形成的定量分析,并对鼻咽癌SUNE-1细胞进行X射线致DNA DSB动态变化。方法 采用蛋白印迹检测DNA-PKcs蛋白表达情况,细胞免疫荧光检测X射线5 Gy诱导的γH2AX焦点形成,通过ImageJ软件分析γH2AX焦点形成数量的差异。结果 DNA-PKcs在DNA-PKcs^-/-和DNA-PKcs^+/+ MEF细胞中分别表达缺失和正常。应用γH2AX焦点/细胞和γH2AX焦点/mm²分析方法动态分析X射线诱导的DNA-PKcs^+/+、DNA-PKcs^-/-MEF细胞和SUNE-1细胞DSB形成的总体趋势一致;照后 0.5~1.0 h大量γH2AX焦点形成,DNA-PKcs^+/+ MEF细胞于照后6.0 h完成修复,DNA-PKcs^-/-MEF和SUNE-1细胞X射线后于照后24.0 h完成修复。γH2AX焦点/细胞的峰值出现在照后1.0 h,γH2AX焦点/mm²的峰值则出现在照后0.5 h。对于DNA-PKcs^+/+和DNA-PKcs^-/-MEF细胞,γH2AX焦点/细胞在照后0.5、1.0、3.0、6.0、12.0 h的不同,而γH2AX焦点/mm²在照后3.0、6.0、12.0 h不同。结论 利用细胞免疫荧光动态检测照后致γH2AX焦点/细胞或γH2AX焦点/mm²的分析方法为动态定量研究DSB损伤及修复提供了新的思路。     

紫外线A辐射对人角质形成细胞的损伤作用

目的：研究紫外线A（UVA）辐射对人角质形成细胞（HaCaT）活力和凋亡的影响及损伤机制。方法：采用不同剂量（1、5、10、20、30、40 J/cm²）UVA照射HaCaT细胞建立急性UVA损伤细胞模型;采用四甲基噻唑蓝（MTT）法及流式细胞术分别检测UVA照射后对细胞活力和凋亡的影响;免疫荧光和Western blot分别检测细胞内γH2AX焦点形成及其蛋白表达水平;原子力显微镜直接观测DNA损伤断裂情况。结果：与对照组相比,5~30 J/cm²范围内,细胞活力随UVA照射剂量的增加而降低（P<0.05）,且呈现剂量-效应关系（r=0.982,P=0.009）;UVA照射后20 h细胞凋亡率在10~40 J/cm²明显增加且有一定的量-效关系（r=0.936,P=0.008）。在30和40 J/cm² UVA照射后,免疫荧光也可观察到明显的焦点形成;不同剂量照射后均可检测到磷酸化γH2AX蛋白的表达,在5和10 J/cm² UVA照射时磷酸化γH2AX蛋白表达增强最为明显;原子力显微镜观察到在30和40 J/cm² UVA照射后细胞DNA与对照组相比有明显的断裂,并出现许多断片。结论：UVA可诱导DNA链断裂,引起细胞损伤,从而促进HaCaT细胞凋亡并抑制其存活。     

幽门螺杆菌及其毒力因子空泡细胞毒素A对人胃腺癌细胞DNA同源重组修复和细胞周期的影响

目的 研究幽门螺杆菌(Hp)标准株Hp P12和其毒力因子空泡细胞毒素A(VacA)对人胃腺癌细胞DNA损伤、同源重组修复和细胞周期的影响。方法 取对数生长期的人胃腺癌AGS细胞,应用Hp标准株(Hp P12)和其VacA基因敲除株(Hp P12ΔVacA)以感染复数(multiplicity of infection, MOI)100分别感染AGS细胞,使用Western Blot方法检测DNA损伤标记蛋白γH2AX、HR修复关键蛋白(Rad51、CtIP、pCtIP)、细胞周期检测点激酶2(pCHK2)的表达水平,进一步用流式细胞术检测细胞周期,验证Hp P12及其毒力因子VacA对HR修复和细胞周期的影响。结果 DNA损伤标记蛋白γH2AX的表达,在Hp P12感染组较未感染组上调(6 h:t=4.870,P=0.001;12 h:t=4.118,P=0.003),在Hp P12ΔVacA感染组较Hp P12感染组下调(6 h:t=4.669,P=0.002;12 h:t=3.117,P=0.013)。Rad51、CtIP、pCtIP和pCHK2的表达在Hp P12感染12 h组...     

利用多聚腺苷酸信号缺陷逆转录病毒转化人胃上皮细胞GES-1

目的 通过人工改变多聚腺苷酸化信号的重组逆转录病毒感染人胃上皮细胞GES-1,检测病毒转录能否产生病毒-宿主融合转录产物及其是否具有转化胃上皮细胞GES-1的能力。方法使用人工定点突变多聚腺苷酸化信号的小鼠逆转录病毒载体,应用PA317病毒包装细胞获得多聚腺苷酸信号缺陷的重组逆转录病毒;用该病毒感染人胃上皮细胞GES-1,并用G418筛选抗性细胞。通过Northern blot方法检查通读RNA的表达;通过细胞形态、软琼脂集落形成实验检测细胞的转化。结果多聚腺苷酸化信号缺陷病毒可以在PA317病毒包装细胞形成病毒颗粒;用该病毒感染人胃上皮细胞GES-1,可捕获下游宿主细胞序列;多聚腺苷酸化信号缺陷病毒感染的GES-1混合细胞中的部分细胞集聚能力增强,个别克隆细胞形态发生改变,在软琼脂中集落形成率高于pLRD感染GES-1细胞和正常GES-1细胞。结论多聚腺苷酸信号缺陷病毒感染GES-1细胞后可通过表达病毒-宿主通读RNA,激活下游宿主序列使细胞发生转化,为进一步应用多聚腺苷酸信号缺陷逆转录病毒发现胃癌相关基因奠定了基础。     

DNA修复基因OGG1研究进展

细胞正常有氧代谢和外源性物理、化学及生物因素均可使机体产生活性氧自由基,大量研究证实:自由基可攻击DNA形成多种类型的氧化损伤.在众多的DNA氧化损伤中,8-羟基鸟嘌呤(8-oxoguanine,8-oxoG)形成频率最高、致突变性最强,可导致G:C→T:A颠换,该突变与肿瘤的发生发展、机体细胞的老化及某些退行性疾病均有密切关系.体内特异识别8-oxoG并将其切除修复的酶被称为8-羟基鸟嘌呤DNA糖苷酶(8-oxoguanine DNA glycosylase),简称OGG1,在人叫做hOGG1.本文将对OGG1的结构与功能、表达与调节、氧化损伤与肿瘤的关系及其研究进展作一概述.     

PARP and CHK inhibitors interact to cause DNA damage and cell death in mammary carcinoma cells

The present studies examined viability and DNA damage levels in mammary carcinoma cells following PARP1 and CHK1 inhibitor drug combination exposure. PARP1 inhibitors [AZD2281 ; ABT888 ; NU1025 ; {"type":"entrez-nucleotide","attrs":{"text":"AG014699","term_id":"3649917","term_text":"AG014699"}}AG014699] interacted with CHK1 inhibitors [UCN-01 ; AZD7762 ; LY2603618] to kill mammary carcinoma cells. PARP1 and CHK1 inhibitors interacted to increase both single strand and double strand DNA breaks that correlated with increased γH2AX phosphorylation. Treatment of cells with CHK1 inhibitors increased the phosphorylation of CHK1 and ERK1/2. Knock down of ATM suppressed the drug-induced increases in CHK1 and ERK1/2 phosphorylation and enhanced tumor cell killing by PARP1 and CHK1 inhibitors. Expression of dominant negative MEK1 enhanced drug-induced DNA damage whereas expression of activated MEK1 suppressed both the DNA damage response and tumor cell killing. Collectively our data demonstrate that PARP1 and CHK1 inhibitors interact to kill mammary carcinoma cells and that increased DNA damage is a surrogate marker for the response of cells to this drug combination.     

香烟烟雾提取物对人呼吸道上皮细胞DNA损伤和凋亡的影响

背景与目的:香烟烟雾可以致多种细胞发生DNA损伤已有报道证实。本研究旨在进一步阐明香烟烟雾提取物(cigarettesmokeextract,CSE)作用于正常人类支气管上皮细胞系(normalhumanbronchialepithelialcells,NHBE)和肺腺癌细胞系SPC-A1后引起的DNA损伤和凋亡情况。方法:不同浓度的CSE作用于NHBE和SPC-A1细胞,用四甲基偶氮唑盐比色法(MTT)检测两种细胞活性。荧光标记的磷酸化H2AX组蛋白(γ-H2AX)抗体特异性标记细胞核内DNA双链断裂(DNAdouble-strandbreaks,DSBs)处的γ-H2AX,然后用流式细胞仪定量检测并分析DNA损伤。用免疫印迹检测γ-H2AX表达。同时,亚G1峰法(SubG1peak)和AnnexinⅤ-FITC/碘化丙啶双染色流式细胞术检测CSE诱导的细胞凋亡。用激光共聚焦显微镜观察细胞损伤和凋亡形态学变化。结果:MTT结果显示,随CSE浓度和作用时间增加,细胞活性均逐渐降低。CSE可引起细胞DNA双链断裂,γ-H2AX最大值在作用后4h左右,然后逐渐降低。DNA损伤后平均12h可以出现凋亡。另外,激光共聚焦显微镜观察到两种细胞内的γ-H2AX量在细胞受到CSE刺激后快速大量的积聚,呈现典型细胞损伤的形态学变化,较为明显的凋亡形态学特征4h后方可出现。结论:CSE能直接引起NHBE和SPC-A1细胞的DNA损伤和凋亡,且存在着浓度和时间依赖关系。     

Oxidative DNA damage in gastric cancer: CagA status and OGG1 gene polymorphism

Oxidative DNA damage is thought to play an important part in the pathogenesis of H. pylori-induced mucosal damage. 8-OHdG is a sensitive marker of DNA oxidation and is repaired by a polymorphic glycosylase (OGG1) more effectively than by OGG1-Cys(326). The aims of this study were to ascertain the respective roles of H. pylori, cagA status and OGG1 polymorphism in determining 8-OHdG levels in benign and premalignant stomach diseases and in gastric cancer (GC). The study involved 50 GC patients (for whom both neoplastic tissue and surrounding mucosa were available), 35 with intestinal metaplasia and atrophy (IMA) and 43 controls. H. pylori and cagA status were determined by histology and polymerase chain reaction for urease and cagA. 8-OHdG was assayed using HPLC with an electrochemical detector (HPLC-ED). The OGG1 1245C-->G transversion was identified using RFLP analyses. 8-OHdG levels were significantly higher in GC, with no differences in relation to H. pylori or cagA status. OGG1 polymorphism was documented in 34% of GC (15 Ser/Cys, 2 Cys/Cys). OGG1 1245C-->G polymorphism was detected in 54% of IMA patients, but only 16% of controls (p = 0.0004) and coincided with significantly higher 8-OHdG levels. In the multivariate analysis, 8-OHdG levels were predicted by histotype and OGG1 status. OGG1 1245C-->G polymorphism was common in both GC and IMA, but very rare in controls, and correlated more closely with 8-OHdG levels than do H. pylori infection or cagA status.     

Silencing of Tousled-like kinase 1 sensitizes cholangiocarcinoma cells to cisplatin-induced apoptosis

Cholangiocarcinoma is a particularly devastating carcinoma with limited treatment options. Tousled-like kinase 1 (TLK1) is a serine/threonine protein kinase that regulates DNA replication and DNA repair pathways. Here, we show that TLK1 is abundantly expressed in cholangiocarcinoma as well as in cell lines derived from cholangiocarcinoma. Although siRNA knockdown of TLK1 did not affect the viability of cholangiocarcinoma cells, it sensitized cholangiocarcinoma cells to cisplatin-induced apoptosis. Immunofluorescence analysis of γH2AX foci showed that silencing of TLK1 enhanced DNA damage induced by cisplatin treatment. Our results suggest that TLK1 plays a pivotal role for the repair of cisplatin-induced DNA damage.     

幽门螺杆菌感染与胃腺上皮细胞增生关系的研究

 目的:研究幽门螺杆菌(HP)与胃腺上皮细胞增生的关系, 方法:经PCR检测和组织病理学观察138例胃粘膜活检标本, 采用SP免疫组化染色观察PCNA表达和Feulgen二染色测定细胞核DNA含量。 结果:细胞核DNA含量在慢性浅表性胃炎(CSG)和慢性萎缩性胃炎(CAG)中, 有HP感染与无HP感染比较, 二倍体和近二倍体细胞减少, 增殖倍体增加。 PCNA表达在CSG和CAG中, 有HP感染与无HP感染比较阳性细胞数和均值增加。 结论:HP感染与胃腺上皮细胞的增生程度有密切关系。     

Histone H2AX is a critical factor for cellular protection against DNA alkylating agents

Histone H2A variant H2AX is a dose-dependent suppressor of oncogenic chromosome translocations. H2AX participates in DNA double-strand break repair, but its role in other DNA repair pathways is not known. In this study, role of H2AX in cellular response to alkylation DNA damage was investigated. Cellular sensitivity to two monofunctional alkylating agents (methyl methane sulfonate and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)) was dependent on H2AX dosage, and H2AX null cells were more sensitive than heterozygous cells. In contrast to wild-type cells, H2AX-deficient cells displayed extensive apoptotic death due to a lack of cell-cycle arrest at G(2)/M phase. Lack of G(2)/M checkpoint in H2AX null cells correlated well with increased mitotic irregularities involving anaphase bridges and gross chromosomal instability. Observation of elevated poly(ADP) ribose polymerase 1 (PARP-1) cleavage suggests that MNNG-induced apoptosis occurs by PARP-1-dependent manner in H2AX-deficient cells. Consistent with this, increased activities of PARP and poly(ADP) ribose (PAR) polymer synthesis were detected in both H2AX heterozygous and null cells. Further, we demonstrate that the increased PAR synthesis and apoptotic death induced by MNNG in H2AX-deficient cells are due to impaired activation of mitogen-activated protein kinase pathway. Collectively, our novel study demonstrates that H2AX, similar to PARP-1, confers cellular protection against alkylation-induced DNA damage. Therefore, targeting either PARP-1 or histone H2AX may provide an effective way of maximizing the chemotherapeutic value of alkylating agents for cancer treatment.     

Chk1 and DNA-PK mediate TPEN-induced DNA damage in a ROS dependent manner in human colon cancer cells

Recently, we showed that the metal chelator TPEN targets colon cancer cells through redox cycling of copper. Here, we studied the DNA damage potential of TPEN and deciphered the role of Chk1, ATM and DNA-PK in TPEN-induced toxicity in 3 human colon cancer cell lines, HCT116, SW480 and HT29. We also investigated the role of reactive oxygen species (ROS) in TPEN-induced DNA damage. TPEN reduced cell viability in a dose- and time-dependent manner. Cytotoxicity was associated with significant DNA damage and higher expression of γ-H2AX protein and activation of ATM/ATR signaling pathway. Cell death by TPEN was dependent on ROS generation as evidenced by the reversal of cell viability, and DNA damage and the abrogation of γ-H2AX levels in the presence of antioxidants. Treatment with antioxidants, however, failed to reverse cytotoxicity at high TPEN concentrations (10µM). TPEN-induced cell death was also dependent on the redox cycling of copper since the copper chelator neocuproine inhibited DNA damage and reduced pChk1, γ-H2AX, and ATM protein expression. Cell death by low TPEN concentrations, involved ATM/ATR signaling in all 3 cell lines, since pre-incubation with specific inhibitors of ATM and DNA-PK led to the recovery of cells from TPEN-induced DNA damage. In addition, siRNA silencing of Chk1, DNA-PK and ATM abrogated the expression of γ-H2AX and reversed cell death, suggesting that Chk1 and DNA-PK mediate TPEN-induced cytotoxicity in colon cancer cells. This study shows for the first time the involvement of Chk1, DNA-PK and ATM in TPEN-induced DNA damage and confirms our previous findings that ROS generation and the redox cycling of copper in response to TPEN are the main mechanisms by which this compound induces cell death in human colon cancer cells. Inhibition of ATM or DNA-PK did not reverse cytotoxicity at high TPEN concentrations that cause excessive levels of ROS and irreversible cellular damage.     

Testosterone augments polyphenol-induced DNA damage response in prostate cancer cell line, LNCaP

Recently, we reported that combined ingestion of soy isoflavones and curcumin significantly decreased the serum level of prostate-specific antigen based on a randomized placebo-controlled double-blind clinical study. We investigated whether these polyphenols inhibited the proliferation of prostate cancer cells by activating a DNA damage response. The effects of isoflavones and curcumin on the expression and phosphorylation of ataxia-telangiectasia-mutated kinase (ATM), histone H2AX variant (H2AX) and checkpoint kinase2 (Chk2) were examined in LNCaP cells. The induction of apoptosis in LNCaP cells was evaluated by poly(ADP-ribose) polymerase (PARP) cleavage. Furthermore, the effects of a testosterone supplement on modulation of the DNA damage response were examined. Combined treatment of isoflavones and curcumin additively suppressed cellular proliferation and induced phosphorylation of ATM, histone H2AX, Chk2 and p53. Testosterone augmented the activation of the DNA damage response and PARP cleavage induced by curcumin. Our results indicate that activation of the DNA damage response by polyphenols might suppress the malignant transformation of prostate cancer. In addition, testosterone, when combined with curcumin, may have suppressive effects on the progression of prostate cancer.     

Insulin-like growth factor-1 attenuates cisplatin-induced gammaH2AX formation and DNA double-strand breaks repair pathway in non-small cell lung cancer

Because insulin-like growth factor-1 (IGF-1) counteracts the anti-neoplastic effect of cisplatin that induces DNA damage and cell death through the formation of platinum-DNA adducts, we investigated the effects of IGF-1 on the DNA double-strand breaks (DSBs) repair system induced by cisplatin. NCI-H1299 and H460 non-small cell lung cancer (NSCLC) cells treated with IGF-1 recovered from cisplatin-derived inhibited proliferation and apoptosis. Decreased tail length in comet assay and suppressed phosphorylation of histone H2AX at Ser139 with IGF-1 cotreatment indicates that IGF-1 attenuates cisplatin-induced DNA damage. Cotreatment with IGF-1 attenuates phosphorylation of ataxia-telangiectasia mutated (ATM) at Ser1981, and ATM-Rad3-related (ATR) at Ser428 and subsequent phosphorylation of Chk2, Chk1, and p53 also dwindled by IGF-1. On the other hand, suppression of the IGF system with AG1024 or siRNA of insulin receptor substrate-1 (IRS-1), a major adaptor molecule of the IGF system, augmented cisplatin-induced gammaH2AX, Ser1981-pATM, and Ser428-pATR generation. ATM, which plays an important role in the phosphorylation of histone H2AX and Chk2 at Thr68, strongly binds with IRS-1 under the influence of cisplatin, and the interaction was partially inhibited by IGF-1. Immunocytochemistry revealed that cisplatin induces nuclear translocation of IRS-1 with Ser1981-pATM, which is suppressed by cotreatment with IGF-1. In conclusion, cisplatin-induced gammaH2AX formation, DNA DSBs repair, and damage checkpoint pathway is inhibited by IGF-1. Cisplatin derives interaction between ATM and IRS-1, which is suppressed by IGF-1. Modulation of biologic activity of the IGF-1 system could be a promising modality that raises the response rate of conventional chemotherapy.