As4S4对宫颈癌HeLa细胞增殖抑制和诱导凋亡的初步研究

背景与目的四硫化四砷(As4S4)是雄黄的主要成分.近年,实验显示雄黄治疗急性早幼粒细胞白血病(APL)疗效明显,发现其具有抗肿瘤作用,但对实体瘤宫颈癌未见报道,本实验体外研究中药雄黄主要成分As4S4对子宫颈癌HeLa细胞的作用,旨在观察其对HeLa细胞的增殖抑制和诱导凋亡的作用.方法以不同浓度 (7.5、15、30、60 mmol/L)的As4S4,分12、24、36、48、60 h处理HeLa细胞,用四甲基偶氮唑蓝(MTT)法测定细胞增殖抑制率;流式细胞仪(FCM)检测细胞凋亡率;用DNA梯状电泳(DNA ladder)检测凋亡的发生.结果不同浓度 (7.5、15、30、60 mmol/L)的As4S4处理的HeLa细胞,细胞增殖受到抑制,作用呈明显的时效和量效关系.24h时IC50为30 mmo/L,与对照组相比,差异有非常显著性(P＜0.01).As4S4诱导HeLa细胞的凋亡率分别为(8.1±1.1)%、(29.6±2.5%)、(46±3)%、(62±4)%,与对照组比较(2.8±1.8)%,差异有极显著性(P＜0.01),并呈浓度依赖性;DNA ladder呈梯状条带.结论As4S4 对HeLa细胞体外具有增殖抑制和促进凋亡作用.     

四硫化四砷对人宫颈癌细胞Hela环氧合酶表达和PGE2产生的影响

目的研究中药雄黄主要成分四硫化四砷(As4S4)对子宫颈癌细胞Hela增殖和凋亡作用的影响及其作用机制。方法以不同浓度(7．5、15、30、60 mg/L)的As4S4对Hela细胞分别处理不同的时间(12、24、36、48、60 h),用四甲基偶氮唑蓝(MTT)法测定细胞增殖反应;流式细胞仪检测细胞凋亡率;Western blot检测环氧合酶-2(COX-2)蛋白的表达;用放射免疫法榆测细胞PGE2释放水平。结果As4S4对Hela细胞增殖有明显的抑制作用(P<0．01),并呈明显的时效和量效关系,作用24 h时IC50的As4S4作用浓度为30 mg／L。As4S4可诱导Hela细胞凋亡,与对照组相比,差异有极显著意义(P< 0．01),并呈浓度依赖性。As4S4可明显抑制Hela细胞COX-2的表达(P<0．05),随着As4S4浓度的增加,其COX-2蛋白表达水平逐渐降低。不同浓度As4S4作用24 h,可明显抑制Hela细胞PGE2的分泌水平,与对照组比较差异有极显著意义(P<0．01)。结论As4S4对Hela细胞增殖具有抑制作用,可促进细胞凋亡,其作用机制可能与抑制细胞COX-2表达和PGE2分泌水平有关。     

四硫化四砷对人宫颈癌细胞Hela环氧合酶表达和PGE2产生的影响

目的研究中药雄黄主要成分四硫化四砷（As4S4）对子宫颈癌细胞Hela增殖和凋亡作用的影响及其作用机制。方法以不同浓度（7．5、15、30、60mg／L）的As4S4对Hela细胞分别处理不同的时间（12、24、36、48、60h）,用四甲基偶氮唑蓝（MTY）法测定细胞增殖反应;流式细胞仪检测细胞凋亡率;Western blot检测环氧合酶-2（COX-2）蛋白的表达;用放射免疫法检测细胞PGE2释放水平。结果As4S4对Hela细胞增殖有明显的抑制作用（P〈0．01）,并呈明显的时效和量效关系,作用24h时IC50的As4S4作用浓度为30ms／L。As4S4可诱导Hela细胞凋亡,与对照组相比,差异有极显著意义（P〈0．01）,并呈浓度依赖性。As4S4可明显抑制Hela细胞COX-2的表达（P〈0．05）,随着As4S4浓度的增加,其COX-2蛋白表达水平逐渐降低。不同浓度As4S4作用24h,可明显抑制Hela细胞PGE2的分泌水平,与对照组比较差异有极显著意义（P〈0．01）。结论As4S4对Hela细胞增殖具有抑制作用,可促进细胞凋亡,其作用机制可能与抑制细胞COX-2表达和PGE2分泌水平有关。     

As4S4 Induced Apoptosis in HeLa Cells and Its Molecular Mechanism

Objective To investigate the As4S4 induced growth inhibition and apoptosis in HeLa cells and its possible relationship with cyclooxygenase-2 (COX-2). Methods HeLa cells were treated with various concentrations (7.5, 15, 30, 60 mg/L) of As4S4 at different times (12, 24, 36, 48, 60 h). Cell growth was measured by MTT. Apoptosis was detected by double staining flow cytometry (FCM). Levels of PGE2 were measured by radioimmunoassay. The expression of COX-2 protein was examined by Western blot analysis. Results After treated with different concentrations of As4S4, the growth of HeLa cells was suppressed significantly in a dose-and time-dependent manner. The IC50 of 24 h was 30 mg/L (P＜0.01). As4S4 induced apoptosis with apoptosis rates at 8.13%-62.36% by flow cytometry (FCM) in a dose-dependent manners. The release of PGE2 was reduced in HeLa cells with the values being (70.56±2.03), (48.58±2.28), (29.25±1.57) and (18.02±1.04) respectively, significantly different compared with control group (3.15±0.01) (P＜0.01). As4S4 also inhibited the activity and expression of COX-2 in a dose dependent manner and down-regulated the expression of COX-2 protein greatly. Conclusion As4S4 could inhibit the proliferation and increase apoptosis in human HeLa cells. These effects may depend on the inhibition of the expression of COX-2 and PGE2 by As4S4.     

神经节苷脂GM3对人宫颈癌HeLa细胞凋亡和血管内皮生长因子表达的影响

目的 研究外源性神经节苷脂GM3对人宫颈癌HeLa细胞增殖、凋亡和VEGF表达的影响.方法 不同浓度GM3干预HeLa细胞24 h后,MTT法检测细胞增殖变化,流式细胞学技术检测细胞凋亡率,RT-PCR技术检测细胞VEGF mRNA表达水平,Western blot技术检测细胞VEGF蛋白水平.结果 (1) GM3浓度分别为2、10、50和250 μmol/L时,HeLa细胞生长抑制率分别为9.8％、32.9％、50.7％和78.6％,半数抑制浓度(IC50)为49.8 μmol/L.(2) GM3浓度分别为10、50和250 μmol/L时,HeLa细胞凋亡率分别为(4.9±0.4)％、(15.1±0.3)％、(24.4±0.7)％.(3)当GM3浓度高于10 μmol/L时,HeLa细胞VEGF mRNA表达水平以及VEGF蛋白表达水平均显著下降(P＜0.05).结论 外源性神经节苷脂GM3能呈浓度依赖性抑制人宫颈癌HeLa细胞增殖,促进HeLa细胞凋亡,下调HeLa VEGF mRNA水平和蛋白水平,提示GM3可能通过调节肿瘤细胞凋亡和肿瘤血管生成而发挥双重抗肿瘤作用.     

Toll样受体8在人宫颈癌细胞株HeLa中的表达及其激动剂对HeLa细胞增殖和凋亡的影响

目的 观察Toll样受体8(TLR8)在人官颈癌细胞株HeLa中的表达,探讨TLR8激动剂CL075对HeLa细胞增殖和凋亡的影响。方法 采用实时荧光定量聚合酶链反应(PCR)法,检测13种肿瘤细胞系中TLR8 mRNA和经CL075作用后HeLa细胞中环氧化酶2(COX-2)、Bcl-2和血管内皮生长因子(VEGF) mRNA的表达水平;采用免疫荧光技术对HeLa细胞中TLR8蛋白的表达进行定位观察;采用流式细胞术检测不同浓度CL075作用下HeLa细胞的细胞周期和凋亡的变化;采用四甲基偶氮唑蓝(MTT)法检测HeLa细胞的增殖状态。结果 与其他肿瘤细胞株相比,HeLa细胞中TLR8mRNA的表达水平最高,达703.7±20.6。TLR8蛋白主要定位于HeLa细胞的胞浆中。0.1、0.5和1.0 μg/ml的CL075分别作用于HeLa细胞48 h后,G2/M+S期细胞所占的比例逐渐增高,其中1.0μg/ml CL075作用组G2/M+S期细胞所占的比例最高,达(57.67±1.73)％,明显高于空白对照组[(39.02±2.33)％,P＜0.01]。经不同浓度的CL075处理后,HeLa细胞的凋亡水平与空白对照组相比,无明显改变(P＞0.05);但经顺铂处理后,凋亡细胞明显增多(P＜0.01)。MTT法检测结果显示,与空白对照组比较,CL075作用于HeLa细胞48和72 h后,HeLa细胞的增殖能力明显增强(P＜0.01)。CI075作用于官颈癌HeLa细胞24和48 h后,COX-2、Bcl-2和VEGF mRNA的表达水平明显升高(P＜0.05)。结论宫颈癌HeLa细胞中TLR8的表达水平及其与配体相互作用的信号,可能是肿瘤发生和发展的重要因素之一。TLR8可能是宫颈癌治疗的一个潜在靶点。     

熊果酸抑制胃癌细胞SGC7901增殖和诱导细胞凋亡的机制

背景与目的:研究表明熊果酸(ursolicacid,UA)可抑制多种肿瘤细胞的增殖并诱导凋亡,但目前有关UA作用于胃癌细胞的报道较为少见。环氧合酶-2(cyclooxygenase-2,COX-2)在多种癌前病变及癌组织中高表达。本研究旨在探讨熊果酸抑制人胃癌细胞SGC7901增殖和诱导凋亡的机制。方法:MTT法检测0、10、20、30、40!mol/LUA作用不同时间对SGC7901细胞增殖的影响;荧光染料Hoechst33258染色观察不同浓度UA作用24h细胞凋亡情况;流式细胞仪检测细胞周期变化及凋亡率;Westernblot法检测COX-2蛋白以及凋亡相关蛋白Bcl-2、Bax表达。放射免疫分析法测定COX-2催化产物前列腺素E2(prostaglandinE2,PGE2)。结果:20～40!mol/LUA可抑制SGC7901细胞的增殖,并呈浓度和时间依赖性,作用12、24、36、48h的半数抑制浓度(IC50)分别为(57.50±1.18)!mol/L、(34.28±2.05)!mol/L、(27.54±1.11)!mol/L、(24.83±1.02)!mol/L;20～40!mol/LUA作用24h后,SGC7901细胞被阻滞于G0/G1期,细胞凋亡率分别为(9.10±2.39)%、(26.30±1.25)%、(35.20±2.26)%;同时COX-2蛋白表达及其催化生成产物PGE2浓度下降,凋亡相关蛋白Bcl-2表达减少,Bax无明显变化。结论:熊果酸对SGC7901细胞具有增殖抑制及诱导凋亡作用,其机制可能与阻滞细胞周期、抑制COX-2表达进而减少PGE2生成以及下调凋亡相关蛋白Bcl-2表达有关。     

索拉非尼对宫颈癌细胞的增殖抑制作用及对PCNA、Survivin表达的影响

目的 探讨索拉非尼对宫颈癌细胞株增殖和凋亡的影响。方法体外培养宫颈癌HeLa、SiHa细胞株,实验分为空白对照组、阴性对照组（DMSO）和索拉非尼（0、25、5、10、20 μmol／L）处理组。光学显微镜观察各组细胞形态学改变;Hoechst荧光染色观察凋亡细胞核的形态学变化;采用MTS法检测索拉非尼对HeLa和SiHa细胞的增殖抑制作用;免疫细胞化学法检测索拉非尼（10 μmol／L）处理HeLa、SiHa细胞48 h后Survivin蛋白的表达;Western blotting检测索拉非尼对宫颈癌HeLa、SiHa细胞PCNA、Survivin蛋白表达的影响。结果不同浓度索拉非尼作用48 h后,HeLa、SiHa细胞出现了凋亡形态学改变;Hoechst染色显示,HeLa、SiHa细胞的胞核变小、固缩,荧光明显增强。MTS检测显示,索拉非尼可抑制宫颈癌HeLa、SiHa细胞增殖,并呈浓度依赖性（P＜0.05）。免疫细胞化学法检测显示,阴性对照组Survivin在HeLa和SiHa细胞中的平均光密度值分别为0.19±0.05和0.17±0.07,与索拉非尼处理组的0.13±0.01和0.13±0.03比较,差异均有统计学意义（P＜0.05）。Western blotting检测显示,索拉非尼在蛋白水平上能够降低PCNA、Survivin表达,且这种下调作用具有浓度依赖性。结论索拉非尼能诱导HeLa、SiHa细胞凋亡,抑制其增殖且呈浓度依赖性,其机制可能与下调癌基因 PCNA、Survivin表达有关。     

选择性环氧合酶2抑制剂对人膀胱癌细胞T24增殖和凋亡的作用

背景与目的:环氧合酶2(cyclooxygenase-2,COX-2)与膀胱癌的发生发展密切相关,因此COX-2抑制剂对于膀胱癌可能具有潜在的抗肿瘤效应.本实验旨在探讨选择性COX-2抑制剂对人膀胱癌细胞T24增殖和凋亡的抑制作用.方法:用四甲基偶氮唑蓝还原法(MTT)研究选择性COX-2抑制剂SC-58125、塞来昔布(celecoxib)和非选择性COX抑制剂吲哚美辛(indomethacin)对T24细胞增殖的影响;用流式细胞术、DNA电泳和Hoechst33258荧光染色3种方法检测SC-58125作用下T24细胞的凋亡,同时逆转录聚合酶链反应(RT-PCR)检测细胞凋亡相关基因Bcl-2和Bax基因的变化.结果:在12.5 μmol/L至200 μmol/L的剂量范围内,SC-58125、塞来昔布及吲哚美辛均能不同程度地抑制T24细胞的增殖,以SC-58125的抑制作用最强,IC50在25 μmol/L～50 μmol/L之间;3种凋亡检测方法均观察到SC-58125作用后凋亡细胞的比例增加,其中100 μmol/L的SC-58125作用于T24细胞6 h和12 h后,流式细胞仪测得凋亡细胞的比例分别为(7.95±1.88)%和(12.5±2.42)%,较对照组增加(P＜0.05),但细胞内与凋亡相关的Bcl-2和Bax基因表达没有变化.结论:选择性COX-2抑制剂体外可抑制T24细胞的增殖,并诱导细胞凋亡.     

环氧合酶-2抑制剂尼美舒利对白血病HL-60细胞增殖的抑制作用

 目的　探讨选择性环氧合酶-2（COX-2）抑制剂尼美舒利对人类急性髓系白血病HL-60细胞的增殖抑制作用。方法　以不同浓度的尼美舒利体外处理HL-60细胞,采用CCK-8、流式细胞术、Western blotting、ELISA等方法,检测尼美舒利对HL-60细胞增殖的作用及对细胞凋亡、细胞周期、COX-2、前列腺素E2（PGE2）、Bax、bcl-2、c-myc的影响。结果　尼美舒利对HL-60细胞增殖的抑制呈剂量、时间依赖性,可诱导细胞凋亡,将细胞周期阻滞于G0～G1期。尼美舒利作用HL-60细胞48 h后,细胞COX-2表达下调,100、200、400 μmol／L尼美舒利处理组与对照组HL-60细胞总凋亡率分别为（24.97±6.36）%、（34.22±5.76）%、（44.59±6.69）%及（4.11±1.26）%,差异有统计学意义（P＜0.05）。HL-60细胞合成PGE2减少,同时bcl-2、c-myc蛋白表达明显减少,Bax蛋白表达明显上调。结论　尼美舒利可抑制HL-60细胞增殖,诱导细胞凋亡,其作用与抑制COX-2表达,减少PGE2合成,阻滞细胞周期和调节凋亡相关蛋白bcl-2、c-myc、Bax的表达等有关。     

Cellular pharmacology of 4'-iodo-4'-deoxydoxorubicin

We have studied the growth inhibition, DNA synthesis inhibition and cell incorporation of the new anthracycline 4'-iodo-4'-deoxydoxorubicin (4'-iododoxorubicin) and of its 13-dihydroderivative in a model of doxorubicin-sensitive and -resistant rat C6 glioblastoma cells; results were compared to those obtained with doxorubicin and doxorubicinol in the same model. 4'-Iododoxorubicin was 7.5 times more potent than doxorubicin on the wild cell line and 45 times on the doxorubicin-resistant line, indicating that cross-resistance was only partial between the two drugs. Whereas doxorubicinol presented only a very faint cytotoxic activity, 4'-iododoxorubicinol retained the same activity as the parent drug against sensitive cells and a lower activity against resistant cells. DNA synthesis inhibition occurred for much higher doses than growth inhibition in the sensitive cells, but for similar doses in resistant cells. In both cell lines, 4'-iododoxorubicin and its metabolite were incorporated to a higher extent than doxorubicin and doxorubicinol respectively. Incorporation of metabolites was always lower than that of their parent compound. We have studied the metabolism of doxorubicin and 4'-iododoxorubicin by sensitive and resistant cells; only traces (less than 5%) of metabolites were identified in the cells as well as in the culture medium. A new cell line was selected for resistance in the presence of low amounts of 4'-iododoxorubicin. It presented a 6-fold resistance to 4'-iododoxorubicin and an 85-fold resistance to doxorubicin. Doxorubicin incorporation was markedly reduced in this cell line while 4'-iododoxorubicin was incorporated to the same extent as in the sensitive line. Measurements of drug efflux were performed in the three cell lines. No significant difference was exhibited between the efflux of doxorubicin and that of 4'-iododoxorubicin in each cell line; these effluxes were very rapid in the doxorubicin-selected resistant line, slow in the wild line and intermediate in the 4'-iododoxorubicin-selected line.     

Chemical and biological characterization of 4'-iodo-4'-deoxydoxorubicin

4'-Iodo-4'-deoxydoxorubicin is a doxorubicin (DXR) analogue with greater lipophilicity and reduced basicity of the amino group. In vitro 4'-iodo-4'-deoxydoxorubicin is more cytotoxic than DXR against a panel of human and murine cell lines and is characterized by a higher and faster uptake. In vivo, the spectrum of activity of 4'-iodo-4'-deoxydoxorubicin is comparable to that of DXR, but the new compound has higher activity against murine P388 leukemia resistant to DXR and against pulmonary metastases from Lewis lung carcinoma. Moreover, the new analogue exhibits antitumor activity also after p.o. administration and shows no cardiotoxicity in experimental systems.     

Expression of erB4/HER4 in Gastric Carcinoma

Objective： To explore the expression of HER4 in gastric carcinoma and elucidate the relationship between its overexpression and clinical pathology. Methods： A total of 68 samples of gastric carcinoma were examined for the expression of HER4 by immunohistochemical assay. Results： HER4 was overexpressed in 79.41% of gastric carcinoma. The overexpression of HER4 correlated only with lymph node metastasis and TNM staging. Conclusion： erbB4 is one of the genes to regulate the growth of gastric carcinoma and artificial interference the overexpression of HER4 may be an effective treatment of gastric carcinoma.     

Two polyamine analogs (BE-4-4-4 and BE-4-4-4-4) directly affect growth,survival, and cell cycle progression in two human brain tumor cell lines

1,14-Bis-(ethyl)-amino-5,10-diazatetradecaneN ¹,N ¹¹-bis(ethyl)norspermine (BE-4-4-4) and 1,19-bis-(ethylamino)-5,10,15 triazanonadecane (BE-4-4-4-4) are two relatively new polyamine analogs synthesized for use as antineoplastic agents. In human brain tumor cell lines U-251 MG and SF-767, both agents inhibited cell growth, were cytotoxic, induced a variable G₁/S block, and depleted intracellular polyamines. Since intracellular polyamine depletion did not always correlate with growth inhibition, cell survival, or cell cycle progression, it cannot completely explain the effects of these agents on growth, survival, and cell cycle progression in U-251 MG and SF-767 cells.This work was supported by grants CA 13525 and CA 49409 from the National Cancer Institute, by the Association pour la Recherche sur le Cancer (Villejuif), and by the National Brain Tumor Foundation     

erbB4/HER4基因和肿瘤

erbB４基因，又称HER４基因，是编码第四个表皮生长因子受体（HER４）的癌基因，该基因在正常的人体组织中有不同的表达，在多种肿瘤组织中存在过度表达，提示该基因在肿瘤的发生发展中起作用。１erbB４基因的由来erbB４基因起初是在新生鼠神经系统的发育中发现的，该基因在新生鼠神经系统的发育过程中普遍表达犤１犦。１９９３年，该基因在人体组织中被克隆，并发现它是编码Ⅰ型受体酪氨酸激酶（RTK）家族第四个成员HER４／P１８０erbB４的基因犤２犦。２erbB４基因／HER４蛋白的结构人类erbB４基因定位于２号染色体长臂，即２q３…     

Pharmacokinetics and metabolism of 4'-iodo-4'-deoxy-doxorubicin in humans.

PURPOSE: 4'-iodo-4'-deoxydoxorubicin is a new anthracycline that currently is under clinical evaluation. To improve the management of future trials, we have determined its pharmacokinetics and metabolism during a phase I/II study and have tried to relate the parameters obtained to the hematologic toxicity of the drug in terms of the survival of blood cells. PATIENTS AND METHODS: The pharmacologic study included 19 patients who were entered at dose levels that ranged between 6 and 90 mg/m2; nine patients were treated at 80 mg/m2, which is close to the maximum recommended dose level. Blood sampling was performed from the end of the bolus infusion to 48 hours after treatment. Drug and metabolites were extracted and analyzed by high-performance liquid chromatography (HPLC), and the data were processed by nonlinear fitting to multicompartment models. RESULTS: Plasma concentrations were best fitted to a three-compartment model with half-lives of 5.2 minutes, 0.79 hours, and 10.3 hours. The total body clearance and volume of distribution at steady state were high (350 L/h/m2 and 2,065 L/m2). The drug was metabolized extensively to a 13-dihydroderivative, 4'-iodo-4'-deoxy-doxorubicinol; the mean area under the curve (AUC) ratio metabolite/parent drug was the highest observed ever for an anthracycline (12.1 +/- 7.4); the metabolite was cleared from the plasma with an elimination half-life of 15.3 hours. The AUCs of the parent compound and its metabolite were related linearly to the dose administered, and showed no saturation phenomenon. Urinary excretion was studied in nine patients and showed a cumulative elimination of less than 6% of the dose administered, two thirds of which were eliminated in the first 12 hours after injection. Ninety-three percent to 100% of the elimination of fluorescent compounds occurred in the form of the metabolite. Drug concentration in five tumor samples showed a rapid uptake of the drug from plasma and a preferential uptake of the parent drug compared with the metabolite. Blood cell counts after 4'-iodo-4'-deoxydoxorubicin treatment showed significant correlations among the surviving fractions of both granulocytes and platelets and the AUCs of the parent drug and its metabolite; the most significant correlations were obtained for the granulocytes and the metabolite. Significant correlations between AUCs and blood-cell survivals were maintained, even if only the nine patients treated at the dose of 80 mg/m2 were taken into account for the computation. CONCLUSIONS: Our results especially show that myelosuppression that is induced by 4'-iodo-4'-deoxydoxorubicin can be well predicted by the measure of the AUC of the drug and its metabolite. This could be used for the further development of the drug toward high-dosage schedules.     

MARDHRS4的鉴定及其对DHRS4转录的调节

目的： 筛选新的小鼠DHRS4反义链转录本并对其功能进行研究。方法：采用快速cDNA末端扩增方法,从小鼠正常肝细胞株NCTC1469中克隆DHRS4反义链转录本,据此转录本设计合适siRNA,然后转染NCTC1469细胞,转染成功36 h后应用RT-qPCR检测细胞内DHRS4 mRNA水平的改变。结果：成功克隆出1个新的天然反义RNA,全长835 nt,属于长链非编码RNA (long non-coding RNA,LncRNA),命名为MARDHRS4,应用siRNA干扰MARDHRS4后,DHRS4 mRNA降低约40%。结论：来自DHRS4反义链的LncRNA MARDHRS4具有增强DHRS4转录的作用。     

Carcinogenicity of 4-methoxyphenol and 4-methylcatechol in F344 rats

The carcinogenic potentials of 4-methoxyphenol (4-MP) and 4-methylcatechol (4-MC), phenolic compounds which are structurally similar to the known forestomach carcinogen BHA and the glandular stomach carcinogen catechol respectively, and cause considerably enhanced cell proliferation and cytotoxicities in rat forestomach and/or glandular stomach epithelium, were examined in male and female F344 rats. Groups of 30 male and female animals were administered diets containing 2% 4-MP or 2% 4-MC for 104 weeks. Histopathological findings in the 4-MP case included atypical hyperplasias (male, 67%, female, 37%), papillomas (50%, 23%) and squamous-cell carcinomas (77%, 20%) in the forestomach. 4-MC induced forestomach papillomas (70%, 93%) and squamous-cell carcinomas (53%, 37%), also glandular stomach submucosal hyperplasias (90%, 93%), adenomas (100%, 100%) and adenocarcinomas (57%, 47%), with ulceration or erosion. The degree of differentiation of the squamous-cell carcinomas induced by 4-MP was less than with 4-MC. The present study demonstrated unequivocal forestomach carcinogenicity for 4-MP and forestomach and glandular stomach carcinogenicity for 4-MC, with cytotoxicity and cell proliferation both appearing as important factors for these non-genotoxic carcinogens.