桂皮醛对裸鼠人胃癌细胞移植瘤生长及凋亡的影响

目的研究桂皮醛对肿瘤细胞的细胞毒作用和对裸鼠人胃癌SGC-7901细胞移植瘤生长及凋亡的影响。方法采用MTT法观察桂皮醛对人癌细胞体外增殖的抑制作用;建立胃癌裸鼠移植瘤模型,以不同浓度桂皮醛ip,与卡铂治疗对比,观察移植瘤的瘤重及瘤重抑制率。应用流式细胞术(FCM)检测各组裸鼠移植瘤细胞周期时相和凋亡率。通过透射电镜观察肿瘤组织细胞凋亡情况。结果桂皮醛对体外培养的7种人肿瘤细胞具有直接细胞毒作用,其半数抑制浓度(IC50)的范围为12.3~37.1μg·ml-1;桂皮醛25、50、100mg·kg-1和卡铂5mg·kg-1ip21d均能明显抑制裸鼠移植瘤的生长,抑瘤率分别为15.15%、41.67%、60.61%和65.15%。桂皮醛治疗组裸鼠移植瘤细胞S期比率升高,50、100mg·kg-1剂量组诱导移植瘤细胞凋亡率明显高于对照组。透射电镜发现桂皮醛导致移植瘤大量细胞发生凋亡,可见典型的细胞凋亡形态学变化。结论桂皮醛体内抗肿瘤作用明显,其机制与抑制肿瘤细胞增殖,诱导细胞凋亡有关。     

SM－1通过激活前胱天蛋白酶－3诱导人胃腺癌BGC－823细胞凋亡发挥抗肿瘤作用

目的：探讨前胱天蛋白酶（ procaspase）－3激活剂SM－1体内外对人胃癌BGC－823细胞的抗肿瘤作用及初步机制。方法体外MTT法测定SM－1对BGC－823细胞增殖的抑制作用,流式细胞仪分析不同浓度SM－1对BGC－823细胞凋亡率的影响,分别用Western印迹和RT－PCR测定SM－1对胱天蛋白酶（ caspase）－3蛋白和procaspase－3 mRNA表达的影响,采用裸鼠皮下移植瘤模型评价SM－1体内抗肿瘤作用。结果 SM－1体外呈剂量依赖性地抑制BGC－823细胞增殖并诱导其凋亡;SM－1暴露48 h 后, caspase－3蛋白和 procaspase－3 mRNA 表达水平增加;在300 mg／kg剂量下,SM－1对BGC－823皮下移植瘤生长具有明显的抑制作用,其抑制率达到56．3％（ P＜0．05）。结论 SM－1体内外对BGC－823细胞及皮下移植瘤具有较好的抑制作用,其机制主要通过激活procaspase－3诱导肿瘤细胞凋亡发挥抗肿瘤作用。     

氧化砷抑制结肠癌裸鼠皮下移植瘤生长及作用机制的研究

 目的研究氧化砷(As2O3)对人结肠癌SW480细胞裸鼠皮下移植瘤生长的抑制作用及其作用机制.方法建立BALB/C-nu/nu裸鼠SW480结肠癌皮下移植瘤模型,以不同浓度As2O3行腹腔内注射治疗,与5-氟脲嘧啶(5-FU)治疗进行对比,观察移植瘤的瘤重及瘤重抑制率,TUNEL法检测移植瘤SW480细胞凋亡率,免疫组织化学法检测bcl-2,Fas基因表达水平的变化.结果5-FU、低剂量As2O3及高剂量As2O3均能明显抑制裸鼠皮下肿瘤的生长,抑瘤率分别为41.51%、53.21%和58.02%,As2O3对移植瘤的生长抑制作用明显强于5-FU,两者比较有显著性差异(P＜0.01).两种浓度As2O3组SW480细胞凋亡率明显高于5-FU.移植瘤组织中bcl-2蛋白阳性细胞数明显减少,Fas蛋白阳性细胞数明显增加.结论As2O3对结肠癌移植瘤的生长具有明显的抑制作用,可诱导移植瘤SW480细胞凋亡,其作用的分子机制可能是下调bcl-2基因表达,上调Fas基因表达.     

D-Ala对转染DAAO基因的K562e细胞移植瘤的杀伤效应

以高致瘤性K562e细胞和表达DAAO基因的KDfGC细胞建立裸鼠移植瘤模型，D－丙氨酸（D－Ala)腹腔注射，持续3周，观察D－Ala对移植瘤的治疗作用以及肿瘤，裸鼠重要脏器的病理变化，结果显示，经D－Ala治疗，转基因肿瘤抑制率为53．8％，未转基因肿瘤抑制率为0．3％，治疗组KDfGC细胞瘤体出现围绕血管分布的坏死，心，肝，肾治疗组与对照组均无明显病理改变，说明在体内DAAO的K562e能被D－Ala有效杀伤，并对重要脏器无明显损伤。     

hNIS基因转染介导Hela细胞移植瘤放射性核素显像和治疗的实验研究

目的 利用131I对转染hNIS基因的宫颈癌Hela-NIS（＋）细胞移植瘤进行显像及治疗实验研究,评价hNIS基因转染介导131I治疗宫颈癌的可行性.方法 （1）利用Hela-NIS（＋）细胞和未转染hNIS的Hela细胞分别建立荷宫颈癌裸鼠模型,进行131I及99TcmO4-显像,观察移植瘤的显影情况,并计算移植瘤部位与对侧相同部位的T/B比值.（2）通过腹腔注射法观察比较74,111和148 MBq131I对荷Hela-NIS（＋）宫颈癌裸鼠移植瘤的抑制作用,另设不行任何治疗的对照组.用SPSS 13.0软件,样本均数间差异行t检验.结果 （1）成功构建荷Hela-NIS（＋）裸鼠移植瘤与荷Hela裸鼠移植瘤模型.131I显像示荷Hela-NIS（＋）裸鼠移植瘤部位明显放射性浓聚,注射后8 h T/B比值最高达17.34,而未转染hNIS基因的荷Hela裸鼠移植瘤部位始终未见明显的放射性浓聚.99TcmO4-显像示荷Hela-NIS（＋）裸鼠移植瘤部位在注射后25 h内持续放射性浓聚.（2）经不同剂量的131I治疗后2～3周起,各治疗组荷Hela-NIS（＋）裸鼠移植瘤生长开始受到抑制,移植瘤体积有不同程度缩小.111MBq组和148 MBq组的移植瘤抑制率差异无统计学意义（t=0.13～2.17,P＞0.05）,但二者均明显高于74 MBq组的移植瘤抑制率（t=2.74～5.75,P＜0.05）.对照组荷Hela-NIS（＋）裸鼠移植瘤持续生长.结论 荷Hela-NIS（＋）宫颈癌裸鼠移植瘤可明显聚集131I及99TcmO4-,且在较长时间内持续清晰显影;131I体内治疗效果显著.     

131I-抗ProGRP（31-98）单克隆抗体E-B5放射免疫显像及放射免疫治疗实验研究

目的了解131I标记的胃泌素释放肽前体（ProGRP）单克隆抗体E-B5在荷小细胞肺癌裸鼠的体内分布及放射免疫显像情况,观察131I—E—B5对荷小细胞肺癌裸鼠移植瘤的生长抑制作用。方法（1）分别建立荷小细胞肺癌、荷肺腺癌及荷大肠癌裸鼠模型。（2）自荷小细胞肺癌裸鼠尾静脉注射131I—E-B5后1,12,24,48,72和96h处死裸鼠并取各主要脏器组织,计算各时间点的每克组织百分注射剂量率（％ID／g）和肿瘤／非肿瘤放射性（T／NT）比值。（3）分别对荷小细胞肺癌、荷肺腺癌和荷大肠癌裸鼠模型进行131I—E—B5放射免疫显像,观察移植瘤的显影情况,并计算移植瘤体／对侧相同部位的放射性（T／B）比值。（4）以未经任何治疗处理组为对照,采用瘤内注射法观察比较3．7,7．4,14．8和22．2MBq131I-E—B5和Na131I对荷小细胞肺癌裸鼠移植瘤的抑制作用。采用SPSS13．0软件处理数据,行两样本均数t检验。结果（1）体内分布研究示：注射后72h,荷小细胞肺癌裸鼠移植瘤体的放射性摄取达到最高值,为（14．1±2．9）％ID／g,高于其他脏器及组织（t=4．11～8．58,P均〈0．05）,瘤体与各脏器组织的T／NT比值随时间延长而逐渐升高,72h时瘤体与肌肉组织的T／NT比值高达4．67±0．66。（2）放射免疫显像发现：注射131I—E—B5后24h荷小细胞肺癌裸鼠移植瘤部位放射性明显聚集,随时间延长放射性浓聚程度逐渐增强,72至96h时最为清晰。荷肺腺癌裸鼠移植瘤局部无明显的放射性浓聚。荷大肠癌裸鼠移植瘤模型显像结果与荷小细胞肺癌裸鼠模型显像结果类似,但其T／B比值低于荷小细胞肺癌裸鼠模型（t=4．29,P〈0．01）。注射后72h,荷小细胞肺癌、荷大肠癌及荷肺腺癌裸鼠的T／B比值分别为5．27±0．97,2．28±0．72和1．26±0．65。（3）131I—E-B5对荷小细胞肺癌移植瘤的生长抑制作用明显大于Na131I（t=2．88～17．77,P均〈0．05）。结论131I—E—B5对小细胞肺癌有较好的靶向作用,可以抑制小细胞肺癌移植的生长并破坏肿瘤组织,有望成为一种较为理想的小细胞肺癌放射免疫显像及放射免疫治疗药物,值得进一步深入研究。     

复方硫酸铝注射液体外及小鼠瘤体注射抗肿瘤作用的研究

目的考察复方硫酸铝注射液体外对膀胱肿瘤BIU87细胞生长的抑制作用及体内对小鼠移植肿瘤生长的抑制作用。方法用MTT法进行体外细胞毒性试验,采用瘤内一次注射给药法考察体内抑制肿瘤生长的作用。结果复方硫酸铝注射液对膀胱肿瘤BIU87细胞的半数抑制浓度为199.3μg·ml-1;瘤内注射对肿瘤生长有显著的抑制作用,有效成份是硫酸铝,复方注射液对肿瘤的抑制作用随硫酸铝浓度的增加而增大,浓度为0.117、0.175、0.234、0.292mol·L-1时,平均抑制率分别为23.0%、32.7%、45.4%和53.3%,表现出剂量正相关。处方中其它成分不影响小鼠移植肿瘤的生长。结论复方硫酸铝注射液体外对膀胱肿瘤细胞具有杀伤作用,小鼠移植肿瘤内一次注射能显著抑制肿瘤生长。     

非甾体类抗炎药塞来昔布抑制肺癌细胞血管生成的实验研究

 目的研究非甾体类抗炎药塞来昔布对肺癌细胞血管生成的抑制作用.方法选用肺癌A549细胞系体外培养,在不同塞来昔布浓度作用下,应用MTT法检测肺癌细胞的增殖抑制,RT-PCR法观察肺癌细胞血管内皮生长因子mRNA(VEGF mRNA)的表达水平;裸鼠移植瘤实验检测塞来昔布在体内对肺癌细胞的抑制作用,并用免疫组化法检测移植瘤微血管密度.结果塞来昔布对肺癌细胞增殖有抑制作用,且呈剂量依赖关系,IC50为50 μmol/L;RT-PCR法中,对照组肺癌细胞VEGFmRNA的表达水平高于药物组(P＜0.05),药物组中肺癌细胞VEGFmRNA表达水平与塞来昔布浓度相关;裸鼠移植瘤实验中,对照组瘤重平均(2.1567±0.9750)g,药物组平均(0.9783±0.5423)g,两组有显著性差异(P＜0.05),抑瘤率为54.64%;移植瘤微血管密度药物组低于对照组(P＜0.05).结论塞来昔布在体内及体外均刘肺癌细胞表现出抑制作用,其作用与抑制肺癌细胞血管生成相关.     

肝癌裸鼠移植瘤端粒酶活性表达的近日节律

目的：探讨肝癌裸鼠移植瘤细胞DNA合成与端粒酶表达的近日节律。方法：在时辰同步化裸鼠中构建肝癌细胞SMMC-7721裸鼠移植瘤，继续在程控光照条件下饲养，于光照后3、9、15、21h取样，用流式细胞仪测定各时期细胞DNA含量，细胞周期分布及端粒酶活性水平。结果：肝癌裸鼠移植瘤细胞DNA合成随近日节律变化，且伴随端粒酶活性的同步节律变化，呈近日节律特征。结论：肝癌裸鼠移植瘤的生长与端粒酶活性表达在静止相达高峰，为制定肿瘤时辰化疗方案提供了有价值的参考。     

Ad—HGF转染对HepG2细胞的生长抑制作用

目的：探讨Ad—HGF转染对HepG2生长抑制作用的影响。方法：用Ad—HGF转染HepG2细胞，检测HGF蛋白表达及对细胞凋亡的影响；并用裸鼠致瘤试验体内观察Ad—HGF对HepG2细胞致癌的影响。结果：转染后24hHGF即有表达，48h达高峰。并观察到Ad—HGF可促进HepG2凋亡，体内Ad—HGF可抑制HepG2细胞生长成瘤。结论：Ad—HGF在体外可抑制HepG2细胞增殖、促进其凋亡，体内抑制其致癌作用。     

In vitro and in vivo investigation of matrix metalloproteinase expression in metastatic tumor models

INTRODUCTION: Overexpression of matrix metalloproteinases (MMPs), particularly MMP-2 and MMP-9, has been correlated with poor prognosis in several cancer types including lung, colon and breast. Noninvasive detection of MMP expression might allow physicians to better determine when more aggressive cancer therapy is appropriate. The peptide CTT (CTTHWGFTLC) was identified as a selective inhibitor of MMP-2/9 that inhibits the growth of MDA-MB-435 human breast cancer xenografts. METHODS: CTT was conjugated with the bifunctional chelator DOTA (1,4,7,10-tetraazacyclotetradecane-N,N',N',N'-tetraacetic acid) for radiolabeling with (64)Cu (t(1/2)=12.7 h, 17.4% beta(+), 39% beta(-)), a radionuclide suitable for positron emission tomography (PET). In vitro affinity was determined in a fluorogenic substrate assay. Tumor gelatinase targeting was evaluated in both biodistribution and microPET imaging studies. RESULTS: Cu(II)-DOTA-CTT inhibited hMMP-2 (EC(50)=8.7 microM) and mMMP-9 (EC(50)=18.2 microM) with similar affinity to CTT (hMMP-2 EC(50)=13.2 microM; mMMP-9 EC(50)=11.0 microM). In biodistribution and microPET imaging studies, (64)Cu-DOTA-CTT was taken up by MMP-2/9-positive B16F10 murine melanoma tumors. Subsequently, imaging studies using (64)Cu-DOTA-CTT were performed on MDA-MB-435 tumor-bearing mice. With zymography, tumor MMP-2/9 expression in this model was shown to be inconsistent, resulting in microPET detection of the MDA-MB-435 tumor in only 1 of 24 imaged mice. Following limited imaging success, (64)Cu-DOTA-CTT was shown to have poor in vivo stability. CONCLUSIONS: Despite some evidence for selective uptake of (64)Cu-DOTA-CTT by gelatinase-expressing tumors, the low affinity for MMP-2 and MMP-9 and in vivo instability make this an inadequate radioligand for in vivo tumor evaluation.     

冬凌草甲素抑制BGC823细胞的生长及MMP-2 MMP-9的表达

目的探讨冬凌草甲素（oridonin,Ori）在体内、外对胃癌BGC823细胞生长的影响,及对BGC823移植瘤MMP-2、MMP-9表达的影响。方法MTT法检测Ori对BGC823细胞生长的抑制作用,流式细胞术检测其对BGC823细胞周期的影响,体内抑瘤实验观察其对BGC823移植瘤生长的影响,免疫组织化学染色法观察Ori对移植瘤组织中MMP-2、MMP-9表达的影响。结果Ori在体外显著抑制细胞的增殖,引起细胞G2/M期阻滞;体内实验表明,Ori显著抑制肿瘤组织的生长,抑制率达70.7%;免疫组化染色结果显示,Ori显著抑制移植瘤MMP-2及MMP-9的表达。结论Ori在体内、外显著抑制胃癌BGC823细胞的生长,减少移植瘤MMP-2、MMP-9的表达,提示Ori可能具有抑制肿瘤侵袭转移及血管生成的作用。     

111In-labeled galectin-3-targeting peptide as a SPECT agent for imaging breast tumors.

Galectin-3 is a member of the galectin family of beta-galactoside-binding animal lectins. Galectin-3 is overexpressed in a wide range of neoplasms and is associated with tumor growth and metastases. Given this fact, radiolabeled galectin-3-targeting molecules may be useful for the noninvasive imaging of tumors expressing galectin-3, as well as for targeted radionuclide therapy. In this study, the tumor cell-targeting and SPECT properties of a galectin-3-avid peptide identified from bacteriophage display were evaluated in human breast carcinoma cells and in human breast tumor-bearing mice. METHODS: The galectin-3-avid peptide G3-C12 (ANTPCGPYTHDCPVKR) was synthesized with a Gly-Ser-Gly (GSG) linker at the amino terminus. After conjugation with 1,4,7,10-tetra-azacyclododecane-N,N',N'N'-tetraacetic acid (DOTA), the peptide was labeled with (111)In. The radiochemical purity and stability of the compound was assessed by high-performance liquid chromatography. MDA-MB-435 human breast carcinoma cells expressing galectin-3 were used to characterize the in vitro binding properties of the radiolabeled compound. SCID mice bearing MDA-MB-435 xenografts were used as an in vivo model for biodistribution and imaging studies with the (111)In-labeled peptide. RESULTS: (111)In-DOTA(GSG)-G3-C12 bound specifically to galectin-3-expressing MDA-MB-435 cells. The radiolabeled peptide was stable in serum and was found intact in excreted urine for at least 1 h. Competitive binding experiments indicated that the radiolabeled peptide exhibited an inhibitory concentration of 50% of 200.00+/-6.70 nM for cultured breast carcinoma cells. In vivo biodistribution studies revealed that tumor uptake was 1.2+/-0.24, 0.75+/-0.05, and 0.6+/-0.04 (mean +/- SD) percentage injected dose per gram at 30 min, 1.0 h, and 2.0 h after injection of the radiotracer, respectively. SPECT/CT studies with (111)In-DOTA(GSG)-G3-C12 showed excellent tumor uptake and contrast in the tumor-bearing mice. Specificity of peptide binding was demonstrated by successful blocking (52%) of in vivo tumor uptake of (111)In-DOTA(GSG)-G3-C12 in the presence of its nonradiolabeled counterpart at 2 h after injection. CONCLUSION: This study demonstrated the successful use of a new radiolabeled peptide for the noninvasive imaging of galectin-3-positive breast tumors. This peptide may be a promising candidate for future clinical applications.     

111In-labeled EGF is selectively radiotoxic to human breast cancer cells overexpressing EGFR.

Our objective was to determine whether the internalization and nuclear translocation of human epidermal growth factor (hEGF) after binding to its cell surface receptor (EGFR) could be exploited to deliver the Auger electron emitter 111In into EGFR-positive breast cancer cells for targeted radiotherapy. METHODS: hEGF was derivatized with diethylenetriamine pentaacetic acid (DTPA) and radiolabeled with 111In-acetate. The internalization of 111In-DTPA-hEGF by MDA-MB-468 breast cancer cells (1.3x10(6) EGFRs/cell) was determined by displacement of surface-bound radioactivity by an acid wash. The radioactivity in the cell nucleus and chromatin, isolated by differential centrifugation, was measured. The effect on the growth rate of MDA-MB-468 or MCF-7 (1.5x10(4) EGFRs/cell) cells was determined after treatment in vitro with 111In-DTPA-hEGF, unlabeled DTPA-hEGF, or 111In-DTPA. The surviving fraction of MDA-MB-468 or MCF-7 cells treated in vitro with 111In-DTPA-hEGF was determined in a clonogenic assay. The radiotoxicity in vivo against normal hepatocytes or renal tubular cells was evaluated by measuring alanine aminotransferase (ALT) or creatinine levels in mice administered high amounts of 111In-DTPA-hEGF (equivalent to human doses up to 14,208 MBq) and by light and electron microscopy of the tissues. RESULTS: Approximately 70% of 111In-DTPA-hEGF was internalized by MDA-MB-468 cells within 15 min at 37 degrees C and up to 15% was translocated to the nucleus within 24 h. Chromatin contained 10% of internalized radioactivity. The growth rate of MDA-MB-468 cells was decreased 3-fold by treatment with 111In-DTPA-hEGF (45-60 mBq/cell). Treatment with unlabeled DTPA-hEGF caused a 1.5-fold decrease in growth rate, whereas treatment with 111In-DTPA had no effect. Targeting of MDA-MB-468 cells with up to 130 mBq/cell of 111In-DTPA-hEGF resulted in a 2-logarithm decrease in their surviving fraction. No decrease in the growth rate or surviving fraction of MCF-7 cells was evident. There was no evidence of hepatotoxicity or renal toxicity in mice administered high amounts of 111In-DTPA-hEGF. Radiation dosimetry estimates suggest that the radiation dose to an MDA-MB-468 cell targeted with 111In-DTPA-hEGF could be as high as 25 Gy with up to 19 Gy delivered to the cell nucleus. CONCLUSION: 111In-DTPA-hEGF is a promising novel radiopharmaceutical for targeted Auger electron radiotherapy of advanced, hormone-resistant breast cancer.     

人类成纤维细胞生长因子受体1的Ⅲb亚型在胰腺癌细胞中的作用

目的 探讨人类成纤维细胞生长因子受体1的Ⅲb亚型(FGFR1-Ⅲb)在胰腺癌细胞中的作用. 方法 以脂质体法将人类全长FGFR1-Ⅲb表达质粒pSVK4/FGFR1-Ⅲb稳定转染入PANC-1胰腺癌细胞,通过MTT试验、软琼脂试验、细胞迁移试验、单个细胞运动试验和裸鼠移植瘤试验检测FGFR1-Ⅲb在转染的胰腺癌细胞中的功能. 结果 转染FGFR1-Ⅲb受体的胰腺癌细胞,在细胞生长、细胞迁移、细胞运动、移植瘤形成及生长方面均受抑,且移植瘤Ki-67表达减低、肿瘤组织中坏死灶减少. 结论 人类FGFR1-Ⅲb受体为胰腺癌细胞的功能性受体,对胰腺癌细胞具有抑制作用.     

A comparison of EGF and MAb 528 labeled with 111In for imaging human breast cancer.

Our objective was to compare 111In-labeled human epidermal growth factor (hEGF), a 53-amino acid peptide with anti-epidermal growth factor receptor (EGFR) monoclonal antibody (MAb) 528 (IgG2a) for imaging EGFR-positive breast cancer. METHODS: hEGF and MAb 528 were derivatized with diethylenetriamine pentaacetic acid (DTPA) and labeled with 111In acetate. Receptor binding assays were conducted in vitro against MDA-MB-468 human breast cancer cells. Biodistribution and tumor imaging studies were conducted after intravenous injection of the radiopharmaceuticals in athymic mice bearing subcutaneous MCF-7, MDA-MB-231, or MDA-MB-468 human breast cancer xenografts or in severe combined immunodeficiency mice implanted with a breast cancer metastasis (JW-97 cells). MCF-7, MDA-MB-231, JW-97, and MDA-MB-468 cells expressed 1.5 x 10(4), 1.3 x 10(5), 2.7 x 10(5), and 1.3 x 106 EGFR/cell, respectively in vitro. RESULTS: 111In-DTPA-hEGF and 111In-DTPA-MAb 528 bound with high affinity to MDA-MB-468 cells (Ka of 7.5 x 10(8) and 1.2 x 10(8) L/mol, respectively). 111In-DTPA-hEGF was eliminated rapidly from the blood with < 0.2% injected dose/g (%ID/g) circulating at 72 h after injection, whereas 111In-DTPA-MAb 528 was cleared more slowly (3%ID/g in the blood at 72 h). Maximum localization of 111In-DTPA-hEGF in MDA-MB-468 tumors (2.2 %ID/g) was 10-fold lower than with 111In-DTPA-MAb 528 (21.6 %ID/g). There was high uptake in the liver and kidneys for both radiopharmaceuticals. Tumor-to-blood ratios were greater for 111In-labeled hEGF than for MAb 528 (12:1 versus 6:1), but all other tumor-to-normal tissue ratios were higher for MAb 528. MDA-MB-468 and JW-97 tumors were imaged successfully with both radiopharmaceuticals, but tumors were more easily visualized using 111In-labeled MAb 528. There was no direct quantitative relationship between EGFR expression on breast cancer cell lines in vitro, and tumor uptake of the radiopharmaceuticals in vivo, but control studies showed that tumor uptake was receptor mediated. CONCLUSION: Our results suggest that the tumor uptake in vivo of receptor-binding radiopharmaceuticals is controlled to a greater extent by their elimination rate from the blood than by the level of receptor expression on the cancer cells. Radiolabeled anti-EGFR MAbs would be more effective for tumor imaging in cancer patients than peptide-based radiopharmaceuticals such as hEGF, because they exhibit higher tumor uptake at only moderately lower tumor-to-blood ratios.     

131I-recombinant human EGF has antitumor effects against MCF-7 human breast cancer xenografts with low levels of EGFR

This study investigated the inhibitory action of (131)I-recombinant human EGF ((131)I-rhEGF) on MCF-7 human breast cancer tumor development in nude mice. The activity and tumor uptake of (131)I-rhEGF was measured by tissue distribution assay, and its effect on tumor growth was measured by monitoring tumor size after treatment with (131)I-rhEGF. Changes in tumor cell ultrastructure were observed by transmission electron microscopy (TEM), and pathological changes in tumor tissue were observed by light microscopy. The tissue distribution assay revealed that (131)I-rhEGF was markedly absorbed by the tumor and reached its maximal uptake rate (16.73%ID. g(-1)) at 120 hours at which point the drug concentration in the tumor was 11.1-fold, 8.1-fold, and 6.6-fold higher than that in blood, liver, and kidneys, respectively. Tumor size measurements showed that tumor development was significantly inhibited by intravenously and intratumorally injected (131)I-rhEGF. Tumor inhibition rates (82.0% and 80.7%, respectively) were significantly higher than those of tumors treated with (131)I (7.49%) and (131)I-HSA (6.91%; P < 0.05). TEM and light microscopy revealed that intravenous and intratumoral injection of (131)I-rhEGF could significantly damage and ultimately kill tumor cells. Our results suggest that (131)I-rhEGF suppresses development of xenografted breast cancer cells in nude mice, providing a novel candidate for receptor-mediated targeted radiotherapy.     

11C]Choline as a potential PET marker for imaging of breast cancer athymic mice

[11C]Choline has been evaluated as a potential positron emission tomography (PET) marker for imaging of breast cancer. The biodistribution of [11C]choline was determined at 45 min post iv injection in MCF-7's transfected with IL-1alpha implanted athymic mice and MDA-MB-435 implanted athymic mice. The results showed the uptake of [11C]choline in these tumors was high, 2.0% dose/g in MCF-7's transfected with IL-1alpha implanted mice and 1.8% dose/g in MDA-MB-435 implanted mice; the ratios of tumor/muscle (T/M) and tumor/blood (T/B) were 1.7 (T/M, MCF-7's), 2.1 (T/M, MDA-MB-435) and 6.9 (T/B, MCF-7's), 12.5 (T/B, MDA-MB-435), respectively; the tumor/muscle ratios are moderate, and the tumor/blood ratios are high. The micro-PET imaging of [11C]choline in both breast cancer athymic mice was acquired for 15 min from a MCF-7's transfected with IL-1alpha and/or MDA-MB-435 implanted mouse at 45 min post iv injection of 1 mCi of the tracer using a dedicated high resolution (<3 mm full-width at half-maximum) small FOV (field-of-view) PET imaging system, Indy-PET II scanner, developed in our laboratory, which showed the uptake of [11C]choline in MCF-7's transfected with IL-1alpha tumor or MDA-MB-435 tumor implanted in a nude athymic mouse. These results suggest that [11C]choline may be a potential PET breast cancer imaging agent.     

Comparative antiproliferative effects of (111)In-DTPA-hEGF,chemotherapeutic agents and gamma-radiation on EGFR-positive breast cancer cells

The antiproliferative effects of (111)In-DTPA-hEGF on breast cancer cells expressing high levels of EGFR were compared with those of chemotherapeutic agents or gamma-radiation. MDA-MB-468 cells were cultured with (111)In-DTPA-hEGF (30 MBq/microg, 1.8 x 10(5) MBq/micromol), DTPA-hEGF, methotrexate, doxorubicin, paclitaxel or 5-fluorouracil. Cell growth was measured colorimetrically. The IC(50) for 111In-DTPA-hEGF was < 70 pM (11 kBq/mL) versus 500 pM for DTPA-hEGF. The IC(50) for paclitaxel, methotrexate, doxorubicin and 5-fluorouracil was 6 nM, 15 nM, 20 nM and 4 microM respectively. (111)In-DTPA-hEGF (70 pM, 11 kBq/mL) delivered approx. 6 Gy to breast cancer cells producing growth inhibition equivalent to 4 Gy of gamma-radiation. We conclude that (111)In-DTPA-hEGF exhibited potent antiproliferative effects towards breast cancer cells at concentrations much lower than chemotherapeutic agents and equivalent to those produced by several Gy of high dose rate gamma-radiation.