荧光素酶标的人肝癌细胞裸鼠异种移植瘤模型的生物发光成像和PET-CT成像比较

目的利用荧光素酶基因标记的人肝癌细胞株BEL-7402建立裸鼠肝原位移植模型,及小鼠肝原位移植模型的生物发光和小动物PET-CT成像的比较。方法构建表达荧光素酶基因的真核表达载体并将其转入人肝癌细胞BEL-7402,经梯度浓度G418筛选获得稳定表达荧光素酶基因的细胞克隆并扩大培养。BALB/cA-nu裸鼠肝门静脉接种5×105个发光细胞使其成瘤,活体荧光成像和小动物PET-CT成像系统观察肿瘤的生长情况。结果获得了稳定表达Luc的人肝癌细胞株,将其接种到裸鼠体内,活体荧光成像系统观察发现能够成瘤,小动物PET-CT影像观察发现小鼠肝脏边缘对18 F-FDG有高摄取区域。结论利用荧光素酶基因标记的人肝癌细胞BEL-7402成功建立了原位肝癌裸鼠模型,小动物活体成像结合小动物PET-CT技术为原位肿瘤模型的建立提供了一种新的可靠的技术,为进一步研究肝癌生长转移机制和药物开发提供了新的有用工具。     

活体荧光成像对裸鼠肝癌细胞系MHCC97-H原位移植模型的动态量化分析

目的:利用生物自发光的裸鼠肝癌原位移植模型,以活体荧光成像技术对肝癌的生长和转移情况进行动态、量化分析.方法:将稳定转染了荧光素酶(luciferase)基因的人肝癌细胞株MHCC97-H-LUC细胞,移植至裸鼠肝脏包膜下,每周利用活体荧光成像系统对裸鼠体内移植瘤的生长部位和范围进行成像,测量肿瘤细胞生物发光量,动态观察肝癌细胞在裸鼠体内的肿瘤数量、生长速度和转移情况.结果:建立可稳定表达荧光素酶的人肝癌细胞株MHCC97-H-LUC并用于进行生物自发光的裸鼠原位移植模型;利用活体荧光成像系统对裸鼠体内的移植瘤成像,见发光部位由肝脏向腹腔扩散,发光量随时间呈指数级增长;病理学观察证实肿瘤细胞长.结论:利用活体荧光成像技术的动态量化分析可灵敏、准确地监测裸鼠肝癌原位移植模型中肿瘤细胞的生长及转移情况,为肿瘤发生、生长、转移机制及对抗肿瘤生长和转移的体内研究提供了科学的量化手段.     

GFP标记的肺癌细胞生长和转移的在体荧光成像

目的:利用稳定表达GFP的人高转移肺巨细胞癌细胞株95D,在体观察肿瘤的生长和淋巴结转移情况.方法:利用逆转录病毒感染人高转移肺巨细胞癌细胞株95D,经过G418筛选获得稳定表达GFP的细胞株.接种裸鼠皮下,成瘤后使用Nikon公司SMZ1000 P-FLA型荧光体视显微镜观察皮下原发肿瘤病灶及转移淋巴结.结果:使用逆转录病毒感染,可以获得稳定表达高强度GFP的肺癌细胞株,且生物学行为无明显改变.接种至裸鼠皮下后,2周左右成瘤,皮下肿瘤原发病灶在荧光体视镜下可清晰观察到肿瘤侵犯范围及周边血管生长情况.切开皮肤,可以观察到表达的GFP的转移淋巴结.结论:GFP标记人高转移肺巨细胞癌细胞株95D,建立裸鼠移植瘤模型,能更方便的观察肿瘤的生长、侵润和转移,为研究肿瘤的生长转移机制打下基础.     

携带荧光素酶基因肝癌细胞株的构建及在肝癌原位移植瘤模型中应用

[目的]构建稳定表达荧光素酶基因的人肝癌细胞株,建立可实时观察的肝癌原位移植瘤模型。[方法]构建含有萤光素酶基因的慢病毒载体,利用慢病毒三质粒系统磷酸钙共转染HEK 293T细胞,收集纯化病毒感染肝癌细胞SMMC7721,嘌呤霉素(puromycin)结合有限稀释法筛选稳定转导细胞株,将细胞原位注射裸鼠肝组织,建立原位肝癌动物模型。[结果]包装纯化的慢病毒悬液的滴度为8.4×106TU/m L,感染肝癌细胞后成功筛选到稳定表达的肝癌细胞株。利用该细胞株成功建立原位注射肝癌裸鼠模型,经活体荧光成像系统观察到肝癌细胞在活体动物体内的分布情况。[结论]荧光素酶肝癌细胞株的成功构建及利用该细胞株建立的原位移植瘤肝癌动物模型为肝癌的治疗研究奠定了基础。     

RNAi沉默SDF-1基因对人胃癌裸鼠原位移植瘤生物学行为的影响及机制

目的:探讨RNAi技术沉默基质细胞衍生因子-1(stromal cell-derived factor-1,SDF-1)对人胃癌裸鼠原位移植瘤生物学行为的影响及可能机制。方法:利用RNAi-SDF-1细胞及对照组细胞建立人胃癌裸鼠皮下移植瘤,Western Blot检测裸鼠皮下移植瘤SDF-1蛋白表达情况。利用裸鼠皮下移植瘤建立其原位移植瘤模型,8周后处死裸鼠解剖尸体,检测原位移植瘤生长、凋亡及远处脏器转移情况。Western Blot检测SDF-1沉默对通路蛋白Akt、p-Akt、NF-κB、p-NF-κB以及侵袭转移相关基因E-cadherin、MMP-7表达的影响。结果:成功建立RNAi-SDF-1裸鼠原位移植瘤模型。与空白及阴性对照组比较,RNAi-SDF-1组裸鼠原位移植瘤生长缓慢,体积与质量均明显降低,差异有统计学意义(P0.01)。流式细胞术结果显示,RNAi-SDF-1组肿瘤细胞凋亡率明显高于空白及阴性对照组(P0.01)。尸体解剖结果显示,RNAi-SDF-1组肿瘤腹腔淋巴结及肝脏转移率明显低于空白及阴性对照组(P0.05)。Western Blot结果显示,与空白及阴性对照组比较,RNAi-SDF-1组肿瘤组织中Akt、p-Akt、NF-κB、p-NF-κB、MMP-7表达水平明显降低,E-cadherin表达水平明显升高(P0.01)。结论:RNAi-SDF-1能够有效抑制人胃癌SGC7901细胞裸鼠原位移植瘤的生长,诱导肿瘤细胞凋亡,抑制其腹腔淋巴结、肝脏转移,其机制可能与抑制PI3K-Akt、NF-κB信号通路及MMP-7的表达并上调E-cadherin的表达相关。     

用于活体成像的小鼠肺癌移植瘤模型的建立

本研究旨在建立可用于活体成像的小鼠肺癌移植瘤模型。利用脂质体将荧光素酶表达载体pGL4.17(luc2/neo)转染至人非小细胞肺癌细胞株A549,经G418筛选获得稳定表达荧光素酶的细胞克隆。根据体外生物发光情况及细胞的生长特性,从中挑选合适克隆,进行裸鼠皮下接种,SCID鼠尾静脉接种,建立肺癌移植瘤模型。利用活体成像系统监测肿瘤的生长转移情况,并用切片HE染色进一步验证小鼠模型移植瘤的原位成瘤和转移能力。实验结果表明:本研究成功地构建了可用于活体成像的小鼠肺癌移植瘤模型,模型稳定可靠、直观、灵敏,为肿瘤生长转移机制的研究及抗肿瘤药物的研发提供了重要工具。     

人胰腺癌裸鼠异种移植瘤模型的生物发光成像和超声成像比较

目的利用荧光素酶基因标记的人胰腺癌细胞株Capan-2建立胰腺癌裸鼠移植模型,评价生物发光和小动物超声成像在移植瘤模型建立中的作用。方法将表达荧光素酶基因的真核表达载体转入人胰腺癌细胞Capan-2,将1×106人胰腺癌细胞悬液分别接种于裸鼠胰腺和右后肢皮下,使其成瘤。生物发光成像和小动物超声成像系统观察肿瘤的生长情况。结果肿瘤细胞原位移植成功率为75%,皮下移植成功率为100%。生物发光成像系统在肿瘤细胞原位接种第7天,可以观察到肿瘤发光;小动物超声成像系统在肿瘤细胞皮下接种第7天,可以测量肿瘤的大小,但在肿瘤细胞原位接种的第7天不能测量肿瘤的大小。另外肿瘤细胞在裸鼠皮下生长的速度比原位生长速度快3倍左右。结论生物发光成像系统更适用于肿瘤早期监测,为深入研究胰腺癌的发生发展、侵袭转移机制提供理想工具。     

基于临床肿瘤标本的胃癌转移模型建立

目的建立基于临床肿瘤标本的胃癌转移模型,为胃癌的转移研究提供个体化动物模型。方法将胃癌新鲜的手术标本移植到裸鼠皮下,建立胃癌患者异种移植(patient-derived xenograft,PDX)模型。进一步通过手术将皮下瘤组织原位移植到裸鼠胃部肌层,连续观察裸鼠的体征状态,通过近红外荧光活体成像技术检测肿瘤转移的发生。解剖荷瘤小鼠,将肺部转移灶进一步移植裸鼠皮下获得实体瘤。HE染色观察原发瘤与转移瘤的结构特征,(short tandem repeat) STR分析原发瘤和转移瘤的遗传特性。PCR-Array分析转移瘤和原发瘤中转移相关基因的表达。结果成功建立胃癌PDX模型,移植瘤组织结构与患者保持基本一致;通过胃部原位移植发现编号C19751的小鼠发生肺和肝的转移。其中肺转移灶皮下移植后获得了实体瘤,STR分析显示原发瘤保持了与肺转移瘤一致的遗传特征。PCR-Array结果显示,与原发瘤相比,转移瘤中CXCL12,IGF1和MMP2基因表达均显著上调。结论利用临床肿瘤标本成功建立胃癌转移模型,为胃癌转移研究提供了良好的个体化模型。     

基于双荧光系统的HepG2肝细胞癌原位移植裸鼠模型建立及活体荧光成像动态定量分析

目的:建立一种可以实时、定量、动态监测的肝细胞癌原位移植模型,并利用活体荧光成像系统对裸鼠体内原位肝细胞癌生长进行分析。方法:利用慢病毒包装系统包装pCDH-GFP-Luc质粒,将绿色荧光蛋白(GFP)和萤光素酶(Luc)基因通过病毒感染的方式整合到HepG2肝癌细胞染色体中,利用流式细胞术分选GFP+细胞,扩增培养后,将该细胞注射到裸鼠皮下进行成瘤,成瘤后分离肿瘤组织接种裸鼠肝脏,将造模成功的裸鼠分为对照组和治疗组,分别灌胃给与0.5%羧甲基纤维素钠(CMC-Na)和50 mg/kg索拉非尼,2/d,连续28 d,每7 d利用活体荧光成像系统观察肝癌细胞在对照组和治疗组裸鼠肝脏内的生长情况。实验结束后,分离裸鼠肝脏肿瘤,拍照称重。结果:建立了稳定表达双荧光的人肝癌细胞系HepG2-GFP-Luc,体外发光强度与表达萤光素酶的细胞数量呈正相关(R2=0.9945);建立了肝细胞癌原位移植活体荧光成像模型,对照组和治疗组肝脏内肿瘤细胞荧光强度随时间的延长逐渐增加,治疗组荧光强度明显低于对照组。定量分析结果显示,在第24、31和38 d,治疗组荧光总光子数值显著低于对照组;治疗组平均瘤重显著低于对照组。结论:建立了一种肝细胞癌原位移植荧光成像模型,可通过活体成像系统对肿瘤大小进行动态定量分析,为抗肝癌药物的药效学评价提供了实时定量分析动物模型。     

荧光素酶标记人胃癌细胞裸鼠原位移植模型的建立

目的建立荧光素酶标记人胃癌原位异种移植模型。方法将萤火虫荧光素酶作为标记基因导入人胃癌MGC803细胞,建立稳定表达荧光素酶的细胞,将其接种裸鼠胃壁浆膜下,建立胃癌裸鼠原位肿瘤模型。用活体荧光成像系统检测肿瘤的发生发展,并进行小动物超声影像和病理学分析。结果裸鼠原位成瘤率为100%,活体荧光成像观察发现在接种第7天,就可以观察到肿瘤发光。21 d后肿瘤进入对数生长期,28 d后肿瘤出现明显坏死,平均荧光光子数呈现下降趋势。超声成像发现小鼠胃部有直径为8.39 mm,面积为28.92 mm2瘤块。结论荧光素酶标记可以实时监测原位异种移植人胃癌生长状况。     

Establishment of a Patient-Derived Orthotopic Xenograft (PDOX) Model of HER-2-Positive Cervical Cancer Expressing the Clinical Metastatic Pattern

Squamous cell carcinoma of the cervix, highly prevalent in the developing world, is often metastatic and treatment resistant with no standard treatment protocol. Our laboratory pioneered the patient-derived orthotopic xenograft (PDOX) nude mouse model with the technique of surgical orthotopic implantation (SOI). Unlike subcutaneous transplant patient-derived xenograft (PDX) models, PDOX models metastasize. Most importantly, the metastasis pattern correlates to the patient. In the present report, we describe the development of a PDOX model of HER-2-positive cervical cancer. Metastasis after SOI in nude mice included peritoneal dissemination, liver metastasis, lung metastasis as well as lymph node metastasis reflecting the metastatic pattern in the donor patient. Metastasis was detected in 4 of 6 nude mice with primary tumors. Primary tumors and metastases in the nude mice had histological structures similar to the original tumor and were stained by an anti-HER-2 antibody in the same pattern as the patient’s cancer. The metastatic pattern, histology and HER-2 tumor expression of the patient were thus preserved in the PDOX model. In contrast, subcutaneous transplantation of the patient’s cervical tumors resulted in primary growth but not metastasis.     

Feasibility and limits of an orthotopic human colon cancer model in nude mice

We sought to develop an accurate colorectal cancer model in nude mice with stable local growth, tumor cell dissemination, and reproducible metastatic capacity. To this end, we orthotopically transplanted histologically intact human colorectal cancer tissue from 10 human patients into nude mice. After successful local tumor growth, tumor tissues were retransplanted as many as 9 times in serial passage. All specimens were transplanted using microsurgical techniques. Histologic, immunohistochemical, and polymerase chain reaction techniques were used to determine tumor growth rates and kinetics, development of regional lymph node and distant hepatic metastases, and the induction of minimal residual disease (MRD). Stable local tumor growth rates with variable growth kinetics were detected in 73.4% of all mice. The lymph node and hepatic metastasis rates were low, at 18.4% and 4.9%, respectively. MRD, as reflected by CK20 positivity of the bone marrow in animals with lymph node and hepatic metastases, was present in 22.2%. The orthotopic colorectal cancer model described here is feasible for the induction of reproducible local tumor growth but is limited by variable growth kinetics and the low rate of lymph node and hepatic metastases. Cytokeratin-positive cells indicative of MRD could be detected in the bone marrow of approximately 25% of the nude mice with metastases. The observed induction of MRD after orthotopic implantation of intact human colon cancer in animals with lymph node and hepatic metastases might be improved if established colon cancer cell lines were used.     

Fluorescent-Antibody Targeting of Insulin-Like Growth Factor-1 Receptor Visualizes Metastatic Human Colon Cancer in Orthotopic Mouse Models

Fluorescent-antibody targeting of metastatic cancer has been demonstrated by our laboratory to enable tumor visualization and effective fluorescence-guided surgery. The goal of the present study was to determine whether insulin-like growth factor-1 receptor (IGF-1R) antibodies, conjugated with bright fluorophores, could enable visualization of metastatic colon cancer in orthotopic nude mouse models. IGF-1R antibody (clone 24–31) was conjugated with 550 nm, 650 nm or PEGylated 650 nm fluorophores. Subcutaneous, orthotopic, and liver metastasis models of colon cancer in nude mice were targeted with the fluorescent IGF-1R antibodies. Western blotting confirmed the expression of IGF-1R in HT-29 and HCT 116 human colon cancer cell lines, both expressing green fluorescent protein (GFP). Labeling with fluorophore-conjugated IGF-1R antibody demonstrated fluorescent foci on the membrane of colon cancer cells. Subcutaneously- and orthotopically-transplanted HT-29-GFP and HCT 116-GFP tumors brightly fluoresced at the longer wavelengths after intravenous administration of fluorescent IGF-1R antibodies. Orthotopically-transplanted HCT 116-GFP tumors were brightly labeled by fluorescent IGF-1R antibodies such that they could be imaged non-invasively at the longer wavelengths. In an experimental liver metastasis model, IGF-1R antibodies conjugated with PEGylated 650 nm fluorophores selectively highlighted the liver metastases, which could then be non-invasively imaged. The IGF-1R fluorescent-antibody labeled liver metastases were very bright compared to the normal liver and the fluorescent-antibody label co-located with green fluorescent protein (GFP) expression of the colon cancer cells. The present study thus demonstrates that fluorophore-conjugated IGF-1R antibodies selectively visualize metastatic colon cancer and have clinical potential for improved diagnosis and fluorescence-guided surgery.     

肺癌转移瘤动物模型的建立

目的通过尾静脉注射,建立一种符合临床特征的肺腺癌转移瘤动物模型,为下一步的肺腺癌转移机制的研究提供可靠的实验造模方法。方法取对数生长期的A549细胞,11只SPF级、4~6周龄BALB/c裸鼠,分别以1×106个细胞/只注射入裸鼠尾静脉。接种后每天观察小鼠状态。分别于接种肿瘤细胞后第4、5、6、7周随机处死2只,余3只小鼠处于濒死状态时处死。解剖小鼠,观察肺部有无转移、转移结节的数目及全身其他器官的转移情况,并做病理取材,HE染色观察。结果注射过程中小鼠均存活。未处死的3只分别于第11、13、14周出现恶液质。第4周肺部未见转移结节;第5周出现镜下肺部转移结节;第6周肉眼可见肺部转移结节;第7周转移结节数增多;第11周出现纵隔淋巴结转移。第11、13、14周出现肺部结构大量破坏,弥漫性的肿瘤细胞浸润,出现淋巴结浸润,病理证实为腺癌。结论通过尾静脉注射A549细胞可以成功建立人肺腺癌转移瘤模型。     

Expression of nm23-H1 gene product in thyroid,ovary, and breast cancers

The nm23 gene product is one of several possible mediators of cancer invasion and metastasis. As the amounts of nm23-H1 mRNA and gene product are reduced in metastatic lymph nodes from patients with papillary carcinoma of the thyroid, we examined the expression of nm23 gene product in 115 thyroid cancers, 78 ovarian cancers, 63 breast cancers, and metastatic lymph node tissues by immunohistochemistry. It was found that nm23-H1, but not nm23-H2 gene product, was expressed in primary sites of thyroid, ovarian, and breast cancers, except for medullary and anaplastic carcinomas of the thyroid, but expressed only weakly or poorly in metastatic lymph nodes. Although nm23-H1 gene product expression was lower in anaplastic and medullary carcinomas of the thyroid, there was no significant difference in nm23-H1 gene product expression among histological types of ovarian and breast cancers. Our data indicate that the nm23-H1 gene product may play a role in metastasis in these hormone-producing organs and that other factors may be involved in metastasis of anaplastic and medullary carcinomas of the thyroid.     

中国人原发性胆囊肿瘤nm23H1基因遗传不稳定性的研究

采用石蜡包埋组织抽提DNA,PCR-单链构象多态性(PCR-SSCP),常规银染,Envision免疫组织化学和Leica-Qwin计算机图像分析等方法,研究人类17号染色体D17S396位点微卫星不稳定性(microsatelliteinstablility,MSI)和杂合性缺失(lossofheterozygosity,LOH),对胆囊肿瘤nm23H1蛋白表达的影响,阐明nm23H1基因遗传不稳定性与胆囊肿瘤进展的关系,为揭示nm23H1基因与肿瘤发生和转移机理提供实验依据。在本实验中,原发性胆囊癌D17S396位点遗传不稳定发生率为42.55%,明显高于良性胆囊肿瘤的13.04%,而在胆囊炎组织中,未见该位点遗传不稳定的发生;其中,LOH的发生率随组织恶性程度的增高而增加(P<0.05)。在胆囊癌中,LOH和MSI发生率与肿瘤组织分化程度具有显著差异(P<0.05);LOH的发生率,在肝脏浸润和淋巴转移组高于无肝脏浸润和无淋巴转移组,在NevinⅣ Ⅴ期高于Ⅰ Ⅱ Ⅲ期(P<0.01);而MSI发生率则相反。nm23H1蛋白阳性率在胆囊癌、胆囊良性肿瘤和炎症组织中差异显著(P<0.05);在胆囊癌中,淋巴转移组低于无淋巴转移组(P<0.01);NevinⅣ Ⅴ期低于Ⅰ Ⅱ Ⅲ期(P<0.05)。此外,计算机图像定量分析显示,在各临床病理参数影响下,nm23H1蛋白的表达强度没有差异。在胆囊癌中,LOH阳性组中nm23H1蛋白阳性率显著低于LOH阴性组,两者差异显著(P<0.05)。实验结果提示,nm23H1基因的遗传不稳定性可能是胆囊肿瘤发生、发展的一个重要机制。nm23H1基因的MSI和LOH,通过相互独立的途径调控胆囊癌的发生和转移,MSI是胆囊癌早期分子指标,LOH可作为胆囊组织恶变的判断指标,可抑制胆囊癌局部nm23H1蛋白的表达,并赋予胆囊癌高淋巴结转移、低预后的特性。提高胆囊癌局部nm23H1蛋白的表达,可减缓肿瘤的浸润转移并提高预后率。     

Development of an experimental model for spontaneous lymph node metastasis of human esophageal carcinoma in nude mice--histopathological analysis]

Three human squamous cell carcinoma cell lines (HPL-EsC-1-K, -S, and -M) originated from a male patient with esophageal carcinoma were established and were studied on their tumorigenic and metastatic properties in nude mice. All cell lines grew in the hind foot pads following subcutaneous inoculation and produced popliteal lymph node metastasis dose (2-8 x 10(6)/mouse)-dependently. Based on the histopathological findings on serial sections of the lymph nodes, the stages of lymph node invasion by cancer cells were classified into 4 stages (St. 0-III). The time course of lymph node metastasis of EsC-K cells were examined. Advanced stage of metastasis increased according to the time elapsed after tumor cell inoculation. Incidence of metastasis of EsC-K cells were not affected by host factors such as sex differences, anti-asialo GM1 antibody treatment on the hosts. Today, there are few experimental models for studies on spontaneous lymph node metastasis of human carcinomas. This experimental model provides a useful research tool for studies on the biology and therapy for lymph node metastasis of esophageal cancer.     

Silencing of Discoidin Domain Receptor-1 (DDR1) Concurrently Inhibits Multiple Steps of Metastasis Cascade in Gastric Cancer

Accumulating evidence suggests that a unique set of receptor tyrosine kinases, known as discoidin domain receptors (DDRs), plays a role in cancer progression by interacting with the surrounding collagen matrix. In this study, we investigated the expression and role of DDR1 in human gastric cancer metastasis. Proliferation, migration, invasion, and tube formation assays were conducted in DDR1-expressing MKN74 gastric cancer cells and corresponding DDR1-silenced cells. The effects of DDR1 on tumor growth and metastasis were examined in orthotopically implanted and experimental liver metastasis models in nude mice. The expression of DDR1 in surgical specimens was analyzed by immunohistochemistry. DDR1 was expressed in human gastric cancer cell lines, and its expression in human gastric tumors was associated with poor prognosis. Among seven gastric cancer cell lines, MKN74 expressed the highest levels of DDR1. DDR1-silenced MKN74 cells showed unaltered proliferation activity. In contrast, migration, invasion, and tube formation were significantly reduced. When examined in an orthotopic nude mouse model, DDR1-silenced implanted tumors significantly reduced angiogenesis and lymphangiogenesis, thereby leading to reductions in lymph node metastasis and liver metastasis. In a model of experimental liver metastasis, DDR1-silenced cells almost completely inhibited liver colonization and metastasis. DDR1 deficiency led to reduced expression of the genes encoding vascular endothelial growth factor (VEGF)-A, VEGF-C, and platelet-derived growth factor-B. These results suggest that DDR1 is involved in gastric cancer tumor progression and that silencing of DDR1 inhibits multiple steps of the gastric cancer metastasis process.     

Specific route mapping visualized with GFP of single‐file streaming contralateral and systemic metastasis of Lewis lung carcinoma cells beginning within hours of orthotopic implantion

In this study, we visualized the origin of Lewis lung carcinoma metastasis after transducing tumor cells with green fluorescent protein (GFP) and transplanting them orthotopically in the middle lobe of the right lung of nude mice. Metastasis was visualized in live tissue at single cell resolution by GFP‐expression as early as 18 h post‐tumor transplant. At this time, single‐file streaming lung carcinoma cells already had invaded inferiorly via a tubular lymphatic structure crossing the lower lobes of the lung to the ipsilateral diaphragmatic surface. By post‐implantation day 2, the ipsilateral lower lobes of the lung were involved with metastatic cells. By post‐implantation day 3, the ipsilateral lower lobes of the lung and the ipsilateral diaphragmatic surface were highly involved with streaming metastatic cells trafficking in single file. By day 4 post‐implantation, cancer cells invaded across the diaphragm to the contralateral diaphragmatic surface. Metastatic cells then invaded superiorly through a lymphatic vessel to involve the contralateral mediastinal lymph nodes. In this model of lung cancer, the origin of metastasis was an inferior invasion from the implanted tumor via a lymphatic duct to the ipsilateral diaphragmatic surface. The cancer cells from this site invaded on the surface of the diaphragm to the contralateral diaphragmatic surface and proceeded superiorly through a lymphatic duct to contralateral lymph nodes. Other organs such as the kidneys and the adrenal glands later became involved with metastasis with the contralateral mediastinal lymph nodes as the source. The use of GFP and the highly metastatic orthotopic lung cancer model allowed the visualization of the origin of metastasis at the single‐cell level and demonstrated the critical role of lymphatic ducts and the diaphragmatic surface as the path to the contralateral side. J. Cell. Biochem. 114: 1738–1743, 2013. © 2013 Wiley Periodicals, Inc.     

Tumor-targeting amino acid auxotrophic <Emphasis Type="Italic">Salmonella typhimurium</Emphasis>

We have developed an effective bacterial cancer therapy strategy by targeting viable tumor tissue using Salmonella typhimurium auxotrophs that we have generated which grow in viable as well as necrotic areas of tumors. However, the auxotrophy severely restricts growth of these bacteria in normal tissue. The S. typhimurium A1-R mutant, which is auxotrophic for leu-arg and has high anti-tumor virulence, was developed in our laboratory. In vitro, A1-R infects tumor cells and causes nuclear destruction. A1-R was initially used to treat metastatic human prostate and breast tumors that had been orthotopically implanted in nude mice. Forty percent of treated mice were cured completely and survived as long as non-tumor-bearing mice. A1-R administered i.v. to nude mice with primary osteosarcoma and lung metastasis was highly effective, especially against metastasis. A1-R was also targeted to both axillary lymph and popliteal lymph node metastasis of human pancreatic cancer and fibrosarcoma, respectively, as well as lung metastasis of the fibrosarcoma in nude mice. The bacteria were delivered via a lymphatic channel to target the lymph node metastases and systemically via the tail vein to target the lung metastasis. The metastases were cured without the need of chemotherapy or any other treatment. A1-R was administered intratumorally to nude mice with an orthotopically transplanted human pancreatic tumor. The primary pancreatic cancer regressed without additional chemotherapy or any other treatment. A1-R was also effective against pancreatic cancer liver metastasis when administered intrasplenically to nude mice. The approach described here, where bacterial monotherapy effectively treats primary and metastatic tumors, is a significant improvement over previous bacterial tumor-therapy strategies that require combination with toxic chemotherapy. Three promoter clones engineered in S. enterica typhimurium were identified to have enhanced expression in bacteria growing in tumors relative to those growing in the spleen. The expression of therapeutics in Salmonella under the regulation of one or more promoters that are activated preferentially in tumors has the potential to improve the efficacy of Salmonella tumor therapy. Exploitation of the tumor-killing capability of Salmonella has great promise for a new paradigm of cancer therapy.