塞来昔布联合三苯氧胺对甲基亚硝基脲诱导大鼠乳腺肿瘤的影响

  目的   塞来昔布联合三苯氧胺对甲基亚硝基脲（MNU）诱发大鼠乳腺肿瘤的影响。  方法   雌性3周龄SPF级Sprague Dawley（SD）大鼠140只随机分成对照组、塞来昔布组、三苯氧胺组及联合组,腹腔注射MNU后分别给予不同的方案进行干预,观察各组大鼠乳腺肿瘤的发生率、肿瘤的体积及COX-2和C-erbB-2的表达。  结果  塞来昔布组、三苯氧胺组与对照组比较,肿瘤发生率低,肿瘤体积小;联合组肿瘤发生率最低,肿瘤体积最小。塞来昔布组、联合组大鼠乳腺肿瘤COX-2、C-erbB-2的阳性表达率低于对照组和三苯氧胺组（P < 0.05）。  结论   塞来昔布和三苯氧胺对MNU诱发大鼠乳腺肿瘤的发生均有预防抑制作用,两药联合效果更好。      

三苯氧胺联合塞来昔布预防大鼠乳腺癌发生的实验研究

背景与目的:三苯氧胺能有效预防乳腺癌的发生,但并非全部有效。多种肿瘤细胞表达环氧化酶-2(cyclooxygenase-2,COX-2),其表达与肿瘤的发生发展有关。本研究观察三苯氧胺联合COX-2选择性抑制剂塞来昔布对化学致癌剂7,12-二甲基苯蒽(7,12-dimethybenzanthracene,DMBA)诱发的大鼠乳腺癌形成的影响。方法:DMBA油剂灌胃制备大鼠乳腺癌模型,每组30只大鼠,分为单纯诱癌组、三苯氧胺组、塞来昔布组和联合药物组4组,观察各组肿瘤发生率、潜伏期、肿瘤数目及体积的差异。结果:(1)乳腺肿瘤发生率三苯氧胺组(48.15%,13/27)、塞来昔布组(50.00%,14/28)低于单纯诱癌组(85.71%,24/28),高于联合药物组(21.43%,6/28);(2)乳腺肿瘤发生时间三苯氧胺组[(97.54±1.85)天]、塞来昔布组[(96.79±2.89)天]晚于单纯诱癌组[(89.50±5.99)天],早于联合药物组[(103.67±3.39)天];(3)乳腺肿瘤数目三苯氧胺组[(1.77±0.73)个]、塞来昔布组[(1.71±0.61)个]小于单纯诱癌组[(3.50±1.62)个],大于联合药物组[(1.17±0.42)个];(4)乳腺肿瘤体积三苯氧胺组[(1.78±0.71)cm3]、塞来昔布组[(2.05±1.04)cm3]小于单纯诱癌组[(6.42±3.96)cm3],大于联合药物组[(0.71±0.96)cm3],且均有统计学意义(均为P<0.05)。结论:塞来昔布和三苯氧胺能抑制DMBA诱发的大鼠乳腺癌的发生、发展,两者联合使用效果更好。     

大豆苷元对乳腺癌生长和血管生成的影响

目的： 利用7,12-二甲基苯蒽(DMBA)诱导的大鼠乳腺癌模型,探讨大豆苷元对乳腺癌肿瘤血管生成的抑制作用及机制。方法：建立DMBA诱导的乳腺癌大鼠模型,随机分为对照组、10、25、50和75 mg/kg大豆苷元灌胃组,观察各组肿瘤生长情况,测定肿瘤微血管密度(MVD),并计算各组肿瘤的增殖指数和凋亡指数;酶联免疫吸附试验(ELISA)法检测心脏离心血标本中血管内皮生长因子(VEGF)、碱性成纤维细胞生长因子(bFGF)和内皮抑素的水平。结果：与对照组比较,50和75 mg/kg大豆苷元组大鼠瘤体质量显著减轻(P<0.05),75 mg/kg大豆苷元组的凋亡指数增加,其抑制肿瘤血管生成的效果显著(P均<0.05)。与对照组比较,25、50和75 mg/kg大豆苷元组的VEGF水平降低,且呈剂量依赖性(P<0.05),同时50和75 mg/kg大豆苷元组的内皮抑素水平增加,差异均有统计学意义(P均<0.05)。结论：较高剂量(≥50 mg/kg)的大豆苷元能使大鼠乳腺肿瘤的微血管密度下降,可有效抑制乳腺肿瘤生长。     

去氢表雄酮抗始发突变作用的研究

目的 探讨在肿瘤始发阶段去氢表雄酮（DHEA）的肿瘤化学预防作用及其机理。方法 通过二甲基蒽[7,12-Dimethylbenz(α)-anthracene,DMBA]诱发的SD大鼠乳腺肿瘤模型和紫外线照射所致DNA损伤和Ames抗突变实验,观察DHEA的抗始发突变活性和对化学致癌的抑制作用。结果 DHEA预防给药能够明显抑制DMBA诱发的大鼠乳腺癌,对照组在给予DMBA后8周即可观察到乳腺发生肿瘤,至实验结束时,肿瘤诱发率为73．0％;DHEA连续给药12周,在25mg/kg剂量组发瘤时间推迟3．5周,肿瘤诱发率降至22．0％,瘤体积较对照组显著减小,抑制率达92．0％,且乳腺肿瘤的潜伏期明显延长,至DMBA给药后11．5周才开始出现瘤块。10^-9mol/L DHEA预处理细胞可对抗紫外线引起的DNA务,抑制率为90．0％。DHEA对DMBA和苯并芘代谢活化后引起的沙门氏菌TA98和TA100的回复突变具有明显抑制作用,DHEA 5μg/平板剂量下的抑制率分别为53．2％和73．0％。此外,DHEA在体外可显著抑制细胞内6－磷酸葡萄糖脱氢酶活性（P＜0．05）,凝胶条带灰度扫描结果表明,10^-7mol/L DHEA抑制率达38．6％。结论 体内外实验结果表明,DHEA对肿瘤的始发突变和化学致癌具有明显的抑制作用,显示了良好的肿瘤化学预防活性。     

塞来昔布联合氟尿嘧啶对MFC细胞615小鼠原位移植瘤COX-2、Fas表达的影响及意义

[目的]通过测定在塞来昔布及氟尿嘧啶干预下的小鼠前胃癌细胞(MFC)615小鼠原位移植瘤中环氧合酶(COX-2)、Fas的表达,对COX-2抑制剂联合氟尿嘧啶对胃癌的影响及意义进行探讨.[方法]制备MFC细胞615小鼠原位移植胃癌模型.造模成功后分为塞来昔布组、联合用药组及对照组,其中塞来昔布25mg/kg灌胃,氟尿嘧啶50mg/kg腹腔注射.观察各组小鼠一般情况.干预3周后处死小鼠,计算抑瘤率.SP免疫组织化学法检测各组肿瘤COX-2、Fas表达.[结果]造模成功率100.00％(30/30).联合用药组、塞来昔布组的小鼠一般情况优于对照组.实验结束后3组比较,塞来昔布组、联合用药组比对照组肿瘤体积和瘤重的抑制率均明显升高(P＜0.05).与塞来昔布组相比,联合用药组肿瘤体积更小、瘤重减轻(P＜0.05).COX-2蛋白在塞来昔布组、联合用药组表达阳性率明显低于对照组,而Fas蛋白的表达则明显高于对照组(P＜0.05).[结论]塞来昔布及氟尿嘧啶对胃癌有抑制作用,其机制与调节COX-2、Fas蛋白表达有关.     

已烯雌酚对Wistar大鼠乳腺癌发生的干预作用

背景与目的:作为一类人工合成雌激素药物,二乙基已烯雌酚(diethyl-stilbestrol,DES)被广泛应用于治疗雌激素不足所致的更年期综合征及骨质疏松症等,但其对乳腺上皮细胞作用的研究有待进一步探讨.本研究通过建立与人相似的Wistar大鼠乳腺癌发生的模型,并用DES进行干预,观察DES在Wistar大鼠乳腺癌发生过程中的作用.方法:利用不同剂量的DES干预二甲基苯蒽[7,12-dimethylben(a)anthracene,DMBA]诱导Wistar大鼠乳腺癌模型,研究其对乳腺上皮细胞的作用.实验分为6个组:对照组、DES1组、DMBA组、DES1 DMBA组、DES2 DMBA组和DES3 DMBA组,其中DES1、DES2和DES3中DES剂量分别为:0.1 mg·kg-1·d-1、0.2 mg·kg-1·-1和0.4 mg·kg-1·d-1喂养大鼠,观察44周处死大鼠,取乳腺组织作常规病理分析以及核仁组成区相关嗜银蛋白(silver-bindingnucleolar organizer regions,AgNOR)计数、PCNA染色强度指数(proliferating cell nuclear antigen staining intensity index,PCNA SⅡ)、Bcl-2和C-erbB-2蛋白表达测定.结果:DMBA组和DES1 DMBA组分别有13只和2只Wistar大鼠发生癌变;单纯DES1组大鼠乳腺上皮细胞AgNOR计数及PCNASⅡ水平上升,Bcl-2及C-erbB-2的表达提高,但未导致癌变;与其他组相比,DES2 DMBA组大鼠乳腺上皮细胞的AgNOR计数和PCNA SⅡ水平下降,Bcl-2及C-erbB-2的表达降低(P＜0.05);DES3 DMBA组上述指标与DES1 DMBA组差异无统计学意义(P＞0.05).结论:单纯小剂量DES可导致大鼠乳腺上皮细胞增生,但不导致乳腺组织癌变;在DMBA诱发大鼠乳腺上皮细胞癌变过程中,小剂量DES可以促使乳腺导管上皮细胞增生、乃至癌变;而中等剂量DES可以明显抑制大鼠乳腺上皮细胞增生,加大DES剂量,抑制作用不增强.     

苦参碱对BBN诱发大鼠膀胱癌发生发展作用及其机制探讨

目的研究苦参碱对N-丁基-N-（4-羟丁基）亚硝基胺（BBN）致大鼠膀胱癌发生发展的影响及其分子机制。方法雄性Sprague-Dawley大鼠,随机分为空白对照组、BBN组（模型组）、阳性药物对照组〔塞来昔布500mg/（kg·d）〕、苦参碱50、100和200mg/（kg·d）剂量组6组。采用BBN诱发大鼠膀胱癌,苦参碱灌胃给药35周,病理学观察膀胱组织形态,免疫组织化学法和蛋白质印迹法分别检测膀胱组织中表皮生长因子受体（epidermal growth factor receptor,EGFR）蛋白表达和细胞周期调控通路p16^INK4a/Cyclin D1/CDK4各蛋白的表达。结果 BBN组、塞来昔布组、苦参碱组膀胱癌的发生率没有显著性变化,差异无统计学意义,P=0.068。在确诊的膀胱癌组织中,与BBN组相比,苦参碱组浸润性膀胱癌的发生率明显降低,χ^2=6.065,P=0.014。免疫组织化学法检测结果显示,BBN组EGFR蛋白表达评分为3.845±0.972,与50mg/kg苦参碱的2.691±1.045（P=0.036）、100 mg/kg苦参碱的2.230±0.748（P=0.029）和200mg/kg苦参碱的2.739±0.814（P=0.041）比较,差异有统计学意义。蛋白质印迹法检测结果显示,大鼠膀胱组织p16INK4a蛋白平均表达量苦参碱200mg/kg组（0.448 6±0.195）较BBN组（0.303 8±0.183）上调,P=0.045;Cyclin D1蛋白的平均表达量苦参碱50mg/kg组（0.448 0±0.236）和200mg/kg组（0.389 2±0.242）较BBN组（0.630 2±0.221）下降,P值分别为0.018和0.010;CDK4蛋白的平均表达量苦参碱200mg/kg组（0.648 4±0.366）较BBN组（0.913 3±0.312）下降,P=0.041。结论苦参碱对BBN诱导的大鼠膀胱癌的发生无抑制作用,但可抑制其向浸润进展,其作用机制可能与抑制大鼠膀胱组织EGFR蛋白的表达及对p16^INK4a/Cyclin D1/CDK4细胞周期调控通路的调控有关。     

平消胶囊对实验性乳腺癌的作用

目的观察平消胶囊对实验性乳腺癌的作用。方法将36只SD雌性大鼠随机分为6组:正常组、模型组、他莫昔芬组(0.36 mg/kg)以及平消胶囊低(250 mg/kg)、中(500 mg/kg)、高(750 mg/kg)剂量组。采用腹腔注射二甲基苯蒽(DMBA,80 mg/kg)的方法建立大鼠乳腺癌模型,建模3 d后给予药物干预,正常组大鼠给予正常饮食,25周后观察乳腺肿瘤发生情况及进行组织病理学分析;并用酶联免疫吸附试验(ELISA)检测大鼠血清中雌二醇(E_2)、谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)、丙二醛(MDA)、肿瘤坏死因子α(TNF-α)水平变化;观察大鼠脏器指数的变化。多组间比较采用单因素方差分析,重复测量数据采用重复测量的方差分析,两两比较采用LSD法。结果 (1)大鼠体质量经重复测量方差分析显示,时间因素、分组因素以及时间与分组的交互作用均对大鼠体质量有影响(F=70.385,P0.001;F=19.389,P0.001;F=3.184,P=0.020)。(2)模型组大鼠双侧乳腺均发生肿瘤,给予他莫昔芬及平消胶囊干预后,大鼠只发生单侧乳腺肿瘤;模型组乳腺肿瘤体积为(21.5±9.6) cm~3,他莫昔芬组及平消胶囊低、中、高剂量组乳腺肿瘤体积分别为(13.6±9.6)、(20.1±5.3)、(15.5±6.2)、(5.2±2.3) cm~3,其中高剂量组乳腺肿瘤体积与模型组比较,差异有统计学意义(P0.050)。(3)各组大鼠双侧第二乳头直径的差异有统计学意义(右侧:F=11.378,P0.001;左侧:F=9.600,P0.001),组间两两比较显示:模型组分别与他莫昔芬组以及平消胶囊中、高剂量组比较,差异均有统计学意义(P均0.050);他莫昔芬组与平消胶囊低剂量组比较,差异也有统计学意义(P0.050)。(4)各组大鼠血清中E_2、GSH-Px、SOD、MDA、TNF-α水平差异均有统计学意义(F=64.845、60.303、32.583、80.558、46.740,P均0.001)。其中,模型组与正常组比较,E_2、MDA、TNF-α水平明显升高(P均0.050),GSH-Px、SOD水平明显降低(P均0.050);模型组分别与他莫昔芬组、平消胶囊中剂量及高剂量组比较,E_2、GSH-Px、SOD、MDA、TNF-α水平的差异均有统计学意义(P均0.050),他莫昔芬组分别与平消胶囊中、高剂量组比较,E_2、GSH-Px、SOD、MDA水平的差异均有统计学意义(P均0.050)。(5)各组间子宫、胸腺、脾脏、肝脏及肾脏脏器指数的差异均有统计学意义(F=3.502、1.696、13.672、2.995、4.465,P均0.050),其中,模型组分别与正常组、他莫昔芬组以及平消胶囊中、高剂量组比较,子宫、胸腺、脾脏脏器指数的差异均有统计学意义(P均0.050),他莫昔芬组分别与平消胶囊低、中、高剂量组比较,差异均无统计学意义(P均0.050)。HE染色结果显示,平消胶囊中、高剂量组大鼠的乳腺瘤样变化程度减轻,腺泡数量减小,导管增生和扩张也有明显改善,病变明显减轻。结论平消胶囊对DMBA诱导的大鼠乳腺癌病变具有显著的防治作用,其作用机制可能与其调节血清中E_2、GSH-Px、SOD、MDA、TNF-α水平,调节机体氧化应激状态,进而提高机体免疫调节水平有关。     

二甲基苯蒽诱发大鼠乳腺癌的组织形态学和微血管密度观察

目的：研究诱发性大鼠乳腺癌发生过程中组织形态学变化和肿瘤微血管密度（MVD）。方法：Wistar雌性大鼠85只,SD雌性大鼠22只,配制浓度为10 mg/ml的二甲基苯蒽（DMBA）麻油溶液灌胃大鼠。17只大鼠8周前死亡,剩余90只大鼠从第8周开始至24周,每2周取大鼠10只活杀,观察乳腺外形,取乳腺肿块HE染色和Ⅷ因子相关抗原免疫组化染色。结果：存活8周以上的90只大鼠中,73只成功诱发乳腺肿瘤,其中乳腺良性增生11只,乳腺癌62只。乳腺癌62只大鼠中,浸润性导管癌35只,浸润性小叶癌15只,乳头状腺癌5只,其他类型肿瘤7只。乳腺癌分化程度分级为：高分化5只,中分化36只,低分化21只。乳腺癌MVD平均值为（6.53±2.71）个/高倍视野,乳腺良性增生MVD为（1.67±0.95）个/高倍视野,乳腺癌MVD显著高于乳腺增生性疾病（P〈0.01）。低分化乳腺癌MVD显著高于中、高分化乳腺癌（P〈0.001）。结论：DMBA灌胃Wistar雌性大鼠乳腺癌诱发成功率高,肿瘤分化程度与微血管密度密切相关。     

二甲基苯蒽诱发大鼠乳腺癌的组织形态学和微血管密度观察

目的:研究诱发性大鼠乳腺癌发生过程中组织形态学变化和肿瘤微血管密度(MVD).方法:Wistar雌性大鼠85只,SD雌性大鼠22只,配制浓度为10 mg/ml的二甲基苯蒽(DMBA)麻油溶液灌胃大鼠.17只大鼠8周前死亡,剩余90只大鼠从第8周开始至24周,每2周取大鼠10只活杀,观察乳腺外形,取乳腺肿块HE染色和Ⅷ因子相关抗原免疫组化染色.结果:存活8周以上的90只大鼠中,73只成功诱发乳腺肿瘤,其中乳腺良性增生11只,乳腺癌62只.乳腺癌62只大鼠中,浸润性导管癌35只,浸润性小叶癌15只,乳头状腺癌5只,其他类型肿瘤7只.乳腺癌分化程度分级为:高分化5只,中分化36只,低分化21只.乳腺癌MVD平均值为(6.53±2.71)个/高倍视野,乳腺良性增生MVD为(1.67±0.95)个/高倍视野,乳腺癌MVD显著高于乳腺增生性疾病(P<0.01).低分化乳腺癌MVD显著高于中、高分化乳腺癌(P<0.001).结论:DMBA灌胃Wistar雌性大鼠乳腺癌诱发成功率高,肿瘤分化程度与微血管密度密切相关.     

Dose-response effects of the COX-2 inhibitor, celecoxib, on the chemoprevention of mammary carcinogenesis

Recent chemopreventive studies in our laboratories showed that the COX-2 inhibitor, celecoxib, inhibited the induction of mammary cancer by 7,12-dimethylbenz(a)anthracene (DMBA). In this study, we examined the relative chemopreventive effect of varying doses of celecoxib on the development and growth of DMBA-induced rat mammary tumors. At 10 days prior to receiving a single intragastric dose of 15 mg DMBA/rat, female Sprague-Dawley rats were fed a control chow diet or diets containing 250, 500, 1000 or 1500 ppm celecoxib until termination of the experiment. Administration of increasing doses of celecoxib inhibited mammary tumor incidence and multiplicity as well as tumor volume in a dose-dependent manner. At 122 days post DMBA-intubation, mammary tumor incidence was 100% in the control rats compared to 80%, 50%, 45% and 25% in rats receiving 250, 500, 1000 or 1500 ppm celecoxib, respectively (p<0.001). Similarly, tumor multiplicity and tumor volume were significantly reduced by increasing the dose of celecoxib from 250 to 1500 ppm in the diet. The control rats had an average of 3.46 tumors/rat compared to 1.80, 1.00, 0.75 and 0.50 tumors/rat in animals receiving 250, 500, 1000 or 1500 ppm celecoxib, respectively (p<0.001). Average tumor volumes in rats fed 250, 500, 1000 or 1500 ppm celecoxib were 0.42, 0.34, 0.31 and 0.16 cm3 compared to 1.29 cm3 in the control rats (p<0.001). There was a concomitant increase in the steady-state serum concentration of celecoxib with the dose. These results indicate that, in this rat model, the chemopreventive effect of celecoxib against breast cancer is dose-dependent and that celecoxib is effective even at lower dose levels.     

Celecoxib inhibits growth of tumors in a syngeneic rat liver metastases model for colorectal cancer

INTRODUCTION: Nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to reduce the risk of colorectal cancer in cyclooxygenase-2 (COX-2) overexpressing colorectal cancers. The present study was designed to evaluate the inhibitory effects of the COX-2 inhibitor celecoxib on the growth of colorectal cancer liver metastases in a syngeneic rat model, CC531. MATERIALS AND METHODS: The effects of celecoxib on cell viability in vitro were evaluated by treatment of CC531 tumor cell cultures with celecoxib. In vivo, Wag/Rij rats were inoculated with CC531 tumor cells at two sites in the liver and treated with celecoxib starting one week before, or directly after tumor inoculation. Control rats were inoculated without treatment. Three weeks after tumor inoculation rats were sacrificed. Tumor size, immune cell infiltration, caspase-3 activity, PGE(2) and celecoxib levels were determined. RESULTS: CC531 tumors did not show COX-2 expression. Tumor growth was significantly inhibited by celecoxib treatment in a dose dependent manner. Immune cell infiltration was decreased after celecoxib treatment, indicating that the immune system was not involved in preventing tumor growth. Tumor caspase-3 levels were only significantly increased if treatment was started before tumor inoculation. Celecoxib serum concentration starting at 0.84 mug/ml significantly inhibited the outgrowth of CC531 liver tumors. In contrast, in vitro concentrations of celecoxib of at least 12 mug/ml were needed to affect tumor cell viability. CONCLUSION: These results suggest that the inhibitory effects of celecoxib on tumor growth are not by direct cytotoxicity, but by creating an unfavorable environment for tumor growth.     

Chemopreventive effects of celecoxib are limited to hormonally responsive mammary carcinomas in the neu-induced retroviral rat model

Introduction

While current breast cancer chemoprevention strategies using selective estrogen response modulators and aromatase inhibitors are quite successful, their effects are limited to hormonally responsive breast cancer. Hormonally nonresponsive breast cancer (including estrogen receptor-negative cancer) is associated with poor prognosis for patients, and few chemoprevention agents exist for this type of cancer. The cyclooxygenase-2 inhibitor celecoxib (Celebrex^®) is a nonsteroidal anti-inflammatory drug and as such is a potential candidate for the prevention of hormonally nonresponsive breast cancer.

Methods

The chemopreventive effects of celecoxib were evaluated in the neu-induced retroviral rat mammary carcinogenesis model, to assess the efficacy of celecoxib on hormonally responsive and hormonally nonresponsive mammary carcinomas.

Results

Dietary celecoxib at 1,200 mg/kg diet was highly efficacious in the prevention of hormonally responsive mammary carcinomas in intact rats, decreasing tumor multiplicity by 56% (P < 0.0001) and by 74% (P = 0.0002) in two independent experiments. No significant effect was found, however, on hormonally nonresponsive mammary carcinomas of ovariectomized rats. Treatment with a combination diet, consisting of tamoxifen at 2 mg/kg diet and celecoxib at 1,200 mg/kg diet, reduced tumor multiplicity by 72% (P = 0.0002) in intact rats. This reduction was not statistically different from that observed with celecoxib alone. Furthermore, long-term treatment with celecoxib was not associated with reductions in tumor volume in either intact rats or ovariectomized rats. In contrast, tamoxifen treatment and the combination regimen caused significant reductions in tumor volumes in intact rats (P = 0.01 and P = 0.004, respectively). Consistent with these data, decreases in proliferation and increases in apoptosis were detected in tamoxifen-treated and combination diet-treated tumors. No such modulations were observed in celecoxib-treated tumors.

Conclusion

The chemopreventive effects of celecoxib appear to be limited to modulations in multiplicity of hormonally responsive mammary carcinomas. The fact that no synergistic or additive effects were observed in combination diet-treated rats raises the question of whether celecoxib is suitable for the prevention of hormonally nonresponsive breast cancer or for use in combination therapy with selective estrogen response modulators or aromatase inhibitors.     

Influence of lithium on mammary tumor growth in vivo

The possibility that lithium ions stimulate growth of mammary tumors in vivo has been suggested by their mitogenic action in vitro on normal and neoplastic mammary epithelium [8] and their clinical use as stimulators of neutrophil production in tumor-bearing patients treated with cytotoxic drugs [14,15]. Three experiments were performed to assess this possibility. Buffalo/N female rats received a single injection of N-nitrosomethylurea (NMU) at a dose known to produce mammary carcinomas in about 50% of animals under standard conditions. Under lithium treatment, the incidence of tumors did not increase significantly. Sprague-Dawley female rats treated with a single dose of 7,12-dimethylbenz[alpha] anthracene (DMBA), but showing no mammary tumors after 4 months, received lithium in their drinking water for 3 additional months. The number of late-appearing tumors was not increased by lithium treatment. Buffalo/N females with NMU-induced tumors were castrated, and the subsequent changes in tumor volume were compared in lithium-treated and control animals. The regression-regrowth curves were not altered by lithium treatment. These results are in contrast to the growth stimulatory capacity of lithium on mammary epithelium observed in vitro [8] and indicate it is very unlikely that lithium ions have an undesirable growth stimulatory action on primary mammary carcinomas in vivo.     

Effects of prolactin or growth hormone on growth of carcinogen-induced mammary tumors of adreno-ovariectomized rats

The effects of exogenous administration of bovine prolactin and bovine growth hormone (GH) on 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumor were investigated in female Sprague-Dawley rats. Rats were bilaterally adrenoovariectomized 15 days after the appearance of the first palpable mammary tumors and were treated with either prolactin or GH beginning the next morning. Marked stimulation of incidence and growth of mammary tumor and of normal mammary gland growth followed subcutaneous injections of 1.25 or 2.5 mg prolactin twice daily for 20 days. GH had no effects on mammary tumor, whereas it accelerated the growth of normal mammary gland and increased the body weight. The administration of 2.5 mg prolactin twice daily for 10 days, beginning 20 days after adreno-ovariectomy, raised the number and size of regressed mammary tumors to the pre-operative levels, while the half dose of prolactin had no effects. These results indicate that prolactin is the principal hormone responsible for the growth of DMBA-induced mammary tumor of the rat, whereas GH has only a minimal role in the growth of the tumor.     

Celecoxib prevents neuroblastoma tumor development and potentiates the effect of chemotherapeutic drugs in vitro and in vivo.

PURPOSE: Neuroblastoma is the most common and deadly solid tumor of childhood. Cyclooxygenase-2 is expressed in clinical neuroblastoma tumors and cell lines and inhibitors of this enzyme induce apoptosis in human neuroblastoma cells in vitro and in neuroblastoma xenografts in vivo. We hypothesized that the cyclooxygenase-2-specific inhibitor celecoxib could enhance the cytotoxic effect of chemotherapeutic drugs currently used in neuroblastoma treatment. Furthermore, we investigated if prophylactic treatment with celecoxib could prevent neuroblastoma tumor development in vivo. EXPERIMENTAL DESIGN: Neuroblastoma cell cytotoxicity of chemotherapeutic drugs in combination with celecoxib was examined. In vivo, athymic rats carrying established SH-SY5Y xenografts were treated with celecoxib in combination with irinotecan, doxorubicin or etoposide, or with either drug alone. For prevention studies, rats received celecoxib in the diet, 250 to 2,500 ppm, from the time of tumor cell injection. RESULTS: Celecoxib induced a synergistic or an additive cytotoxic effect in combination with doxorubicin, etoposide, irinotecan or vincristine in vitro. In vivo, treatment with celecoxib in combination with irinotecan or doxorubicin induced a significant growth inhibition of established neuroblastoma tumors. Rats receiving celecoxib in the diet showed a distinct dose-dependent delay in tumor development compared with untreated rats. Plasma levels of celecoxib were comparable with levels obtainable in humans. CONCLUSIONS: Celecoxib potentiates the antitumor effect of chemotherapeutic drugs currently used in neuroblastoma treatment, which argues for clinical trials combining these drugs. Celecoxib could also be a potential drug for treatment of minimal residual disease.     

Combination of radiation and celebrex (celecoxib) reduce mammary and lung tumor growth

The selective cyclooxygenase (COX)-2 inhibitor, celecoxib, alone and in combination with radiation was investigated in vitro and in vivo. Murine mammary tumor line (MCa-35) and human lung carcinoma line (A549) have high and low basal levels of COX-2 protein, respectively. Treatment of both tumor cells with celecoxib alone resulted in a dose- and time-dependent reduction of cell number (clonogenic cell death) and tumor cell growth rate in vitro; however, inhibition of tumor cell growth by celecoxib was not correlated with the reduction of COX-2 protein in tumor cells. Although both tumor cell types had similar DNA damage after celecoxib treatment, significant induction of tumor cell apoptosis was only observed in MCa-35. Celecoxib-mediated radiation sensitization also occurred in MCa-35 cells determined by clonogenic assay, in part due to a G2/M arrest at 8 to 24 hours after treatment. The tumor growth inhibitory effects of celecoxib were also studied in vivo. It was found that celecoxib inhibited both tumor growth after intragastric administration of celecoxib (5 daily doses of 50 mg/kg). Combined with a single 30-Gy dose of radiation, celecoxib resulted in additive effects on A549 tumors. Celecoxib-treated A549 tumors had marginal reduction of total and perfused blood vessels compared with untreated controls. Reduction of tumor angiogenic cytokine and growth factor mRNA was associated with decreased perfused vessels. Finally, reduction of vascular endothelial growth factor protein after celecoxib was also observed in both tumor lines by Western blot. Our results indicate that the selective inhibition of COX-2 combined with radiation has potential application in radiotherapy, and celecoxib-mediated antitumor effects may act through different mechanisms including direct inhibition of tumor cell proliferation, alteration of tumor cell cycle, and antiangiogenesis.     

Metabolism of retinol and retinoic acid in N-methyl-N-nitrosourea-induced mammary carcinomas in rats

This study was conducted to examine the in vivo uptake and metabolism of natural retinoids by N-methyl-N-nitrosourea-induced mammary carcinomas. In this study, endogenous retinol and retinyl esters were present in normal mammary epithelial cells, but were undetectable in N-methyl-N-nitrosourea-induced mammary carcinomas in rats as determined by high-pressure liquid chromatography. No differences were found in plasma levels of retinol, in liver retinyl esters, or total content of vitamin A between tumor-bearing and control animals. Administered labeled retinol was taken up and esterified by normal mammary epithelial cells. Tumor-bearing rats were given injections i.p. of either [3H]retinol or [3H]retinoic acid. Radioactivity increased progressively with time in liver and other tissues except in breast tumor, where the uptake fluctuated over the 8 days after the injection of [3H]retinol; in mammary tumors practically no metabolism of [3H]retinol occurred, while in other tissues extensive esterification was detectable. In contrast, in animals given injections of [3H]retinoic acid, the uptake and metabolism of the label in the breast tumors paralleled with those found in other tissues. Neither the activity of acyl coenzyme A:retinol acyl transferase nor the activity of retinyl ester hydrolase was altered in the mammary tumor compared to the normal mammary gland. On the other hand, a significant decrease in the retinal oxidase activity was found in tumor tissue compared to normal mammary tissue. Since no esterification of [3H]retinol occurred in vivo despite the presence of acyl coenzyme A:retinol acyl transferase activity, it is possible that a specific defect in the cellular uptake of retinol may exist in N-methyl-N-nitrosourea-induced mammary carcinomas.     

Suppression of tumor formation by a cyclooxygenase-2 inhibitor and a peroxisome proliferator-activated receptor gamma agonist in an in vivo mouse model of spontaneous breast cancer

PURPOSE: Activation of COX-2 and inhibition of PPARgamma have been observed in human and animal models of breast cancer. Both inhibition of COX-2 and activation of PPARgamma can inhibit proliferation of breast cancer cells in vitro. Here, we examine the effects of the COX-2 inhibitor celecoxib and the PPARgamma agonist N-(9-fluorenyl-methyloxycarbonyl)-l-leucine (F-L-Leu) on mouse breast tumor cells in vitro and in vivo. EXPERIMENTAL DESIGN: We created and characterized a mouse mammary adenocarcinoma cell (MMAC-1) line from C3 (1)-SV40 tumor antigen mice to study COX-2 and PPARgamma expression and response to celecoxib and F-L-Leu in vitro. To study the in vivo effects, C3 (1)-SV40 tumor antigen mice were given either control diet or diets containing three different concentrations of celecoxib and F-L-Leu as well as a combination of both agents. Mice were then followed for tumor formation up to 1 year. RESULTS: MMAC-1 cells express both COX-2 and PPARgamma mRNA and exhibited cooperative growth inhibition with a combination of celecoxib and F-L-Leu. In mice, the median age of death due to mammary tumors was significantly delayed in celecoxib-treated animals at all three concentrations but was not significantly affected by F-L-Leu treatment alone. A combination of celecoxib and F-L-Leu was significantly more effective than celecoxib alone. CONCLUSIONS: Our findings suggest that a combination of a COX-2 inhibitor and PPARgamma agonist can delay breast cancer in a mouse model and suggest that these agents should be studied in the context of human populations with high breast cancer risk.     

COX-2选择性抑制剂塞来昔布对裸鼠荷人子宫内膜腺癌的抑制作用

 目的 探讨环氧化酶-2（cyclooxygenase-2,COX-2）选择性抑制剂塞来昔布对人子宫内膜腺癌的治疗作用及其机制。 方法 建立人子宫内膜腺癌HEC-1B细胞裸鼠荷瘤模型,待成瘤后随机分为对照组与实验组,对照组予生理盐水口服2周,实验组分别予塞来昔布4mg/d和2mg/d口服2周。从治疗开始每3天计算瘤体积一次,描绘肿瘤生长曲线,治疗结束后处死裸鼠剥除瘤组织,计算抑瘤率,采用RT-PCR法测定移植瘤组织COX-2 mRNA的表达、免疫组化法测定COX-2蛋白的表达和微血管密度（MVD）。 结果 塞来昔布对裸鼠皮下移植瘤的生长具有明显的抑制作用,且随着药物浓度的增加,抑瘤作用逐渐增强（抑瘤率分别为 32.4％和48.6％）,RT-PCR结果显示移植瘤组织COX-2 mRNA的表达逐渐减弱,免疫组化结果显示移植瘤组织 COX 2蛋白的表达及微血管密度（MVD）逐渐减少,实验组与对照组之间及各实验组之间的差异均有统计学意义（P <0.05）,COX-2蛋白的表达与MVD数量呈正相关（r系数为0.921,P<0.01）。 结论 COX-2选择性抑制剂塞来昔布能够抑制裸鼠荷人子 宫内膜腺癌的生长,其机制可能与降低COX 2的表达、减少微血管的生成有关。