MIA PaCa-Ⅱ胰腺癌细胞系神经转移动物模型建立的实验研究

目的建立MIA PaCa-Ⅱ人胰腺癌细胞系裸鼠胰腺原位移植瘤模型并观察神经侵袭情况。方法将MIA PaCa-Ⅱ细胞行裸鼠背部皮下接种,建立高转移特性胰腺癌裸鼠皮下移植瘤模型,然后将高转移性移植瘤组织接种于裸鼠胰腺被膜下,分别于4周、6周和8周处死裸鼠行移植瘤组织解剖和病理学检查,测量移植瘤大小和重量,并用HE和银染方法观察神经侵袭情况。结果MIA PaCa-Ⅱ细胞裸鼠皮下接种成瘤率为100.0%（10/10）,皮下移植瘤呈局限性生长,无脏器和神经转移。原位移植4周、6周和8周后,胰腺癌原位移植瘤成瘤率均为100.0%（10/10）,神经转移率分别为50.0%（5/10）、80.0%（8/10）和60.0%（6/10）,并可见多个脏器转移,以肝脏、肝门淋巴结、胃窦转移和腹膜播散多见。结论人胰腺癌细胞系MIA PaCa-Ⅱ裸鼠胰腺原位移植瘤模型为一较理想的＂拟人＂神经浸润转移模型,可用于胰腺癌体内嗜神经性机制的研究。     

人肝癌裸鼠连续传代的病理变化特征

目的：探讨裸鼠人肝癌20年连续传代的病理变化特征。方法：裸鼠人肝癌组织模型（SMMU-LTNM）连续观察20年（1987—2007年），皮下移植瘤传至228代，建立腹腔移植瘤、肝原位移植瘤及NOD-SCID小鼠肝原位移植瘤的病理资料，经光镜、电镜、图像分析、染色体分析、周围血液AFP检测等方法分析病理变化特征。结果：（1）上述4种肿瘤模型的局部侵袭和转移均长期存在：皮下移植瘤的局部侵袭率为59．70％（40／67），肺内转移率为37．10％（23／62）；腹腔移植瘤的肺内转移率为59．02％（36／61）；肝原位移植瘤的肝内转移率为18．18％（4／22），肺内转移率为31．82％（7／22）；NOD—SCID小鼠肝原位移植瘤的肺内转移率为53．85％。（2）皮下移植瘤的组织学变化：第10代前的瘤细胞分化和组织结构与原人肝癌近似，以Ⅱ级分化、粗梁型为主；第11代至225代瘤细胞以分化Ⅲ级、团块型为主，电镜下亦证实瘤细胞分化更差。（3）AFP检测第32代前为92500μg／L，第33代至130代AFP下降为6729μg／L，220代AFP检测为1000—5000μg／L。（4）腹腔移植瘤的瘤细胞群体与肺转移瘤的瘤细胞群体DNA含量分布范围明显增宽，2C-6C不等，峰值明显右移，前者的分布范围比后者更宽；DNA含量分别为2．60±0．20和2．10±0．26。（5）染色体检测，第55—206代（相隔12年）部分瘤细胞染色体变为裸鼠染色体。结论：裸鼠皮下移植瘤可连续传代20年，局部侵袭及转移的恶性生物学行为不变；瘤细胞分化更差，AFP下降，部分瘤细胞染色体变为裸鼠染色体。这些病理变化可能与裸鼠内环境影响和瘤细胞的多潜能分化有关。     

裸鼠动物模型中胰腺癌神经侵袭的研究

  目的   探讨在裸鼠动物模型中胰腺癌神经侵袭发生情况。   方法  人Mia PaCa-2和Capan-2胰腺癌细胞株培养,裸鼠皮下胰腺癌细胞注射成瘤后,将瘤块取出切碎后裸鼠胰腺原位移植建立裸鼠原位胰腺癌动物模型,于术后4、6、8周分批处死裸鼠,采用大体标本观察和病理切片HE染色的方法观察模型中肿瘤大小、转移情况和胰腺癌神经侵袭的情况。   结果  裸鼠胰腺原位植瘤术后成瘤率100%,术后4周Mia PaCa-2组3例（50.00%）发生腹膜后神经侵犯,Capan-2组2例（33.33%）发生腹膜后神经侵犯;原位植瘤术后6周,Mia PaCa-2组5例（83.33%）发生腹膜后神经侵犯,Capan-2组4例（66.67%）发生腹膜后神经侵犯;原位植瘤术后8周,Mia PaCa-2组8例（100.00%）发生腹膜后神经侵犯,Capan-2组7例（100.00%）发生腹膜后神经侵犯。腹膜后神经侵犯组与其他组比较差异均有统计学意义（P<0.01）。   结论  神经侵袭是胰腺癌发展过程中的一个早期、独立的事件,在胰腺癌发生的早期,无其他转移或很少时,已经发生了腹膜后神经侵犯。      

维甲酸对胃癌裸鼠移植瘤中p53、H—ras和C—myc基因表达的影响

目的：探讨全反式维甲酸（ATRA）对胃癌裸鼠移植瘤中p53、H-ras和C－myc表达的影响。方法：采用免疫组化ABC法测定p53、H－ras,C-myc基因蛋白产物在胃癌裸鼠移植瘤中的表达水平。结果：MKN28和SGC7901胃癌裸鼠移植瘤经ATRA治疗后,突变型p53、C－myc基因表达水平降低,H－ras基因表达水平提高,但MKN45胃癌移植瘤细胞中p53、H－ras、C－myc基因表达与ATRA治疗无关。结论：ATRA抑制胃癌细胞增殖及诱导胃癌细胞分化的分子机制之一可能是通过调控P^53、H－ras、C－myc 的表达实现的。     

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。     

尼美舒利对人喉鳞癌Hep-2细胞祼鼠移植瘤CD44和MMP-7表达的影响

目的探讨尼美舒利对喉鳞状细胞癌裸鼠皮下移植模型的抑瘤作用及机制。方法建立人喉鳞癌Hep-2细胞株裸鼠移植瘤模型,应用尼美舒利处理裸鼠,观察肿瘤生长情况并绘制生长曲线,免疫组织化学技术检测移植瘤组织中COX-2、CD44和MMP-7蛋白表达,RT-PCR技术检测移植瘤组织中COX-2、CD44 和MMP-7mRNA表达情况。结果与对照组相比,治疗组肿瘤体积增长较对照组缓慢,体积抑瘤率为63.36%,重量抑瘤率达51.81%,肿瘤体积和重量均明显低于对照组（P均＜0.05）。实验组和对照组治疗前后裸鼠体重增长值差异无统计学意义（P＞0.05）。实验组COX-2、CD44和MMP-7蛋白及mRNA表达明显低于对照组,差异有统计学意义（P均＜0.05）。结论尼美舒利可有效抑制人喉鳞癌细胞系Hep-2裸鼠移植瘤的生长,其机制可能与抑制COX-2、CD44及MMP-7表达有关。     

人骨肉瘤原位移植模型的建立及生物学特征

目的 用人骨肉瘤细胞系HOS-98建立人骨肉瘤裸鼠胫骨原位移植模型,以探讨宿主器官微环境对人骨肉瘤细胞侵袭及转移等生物学行为的影响。方法 将人骨肉瘤细胞系HOS-98接种于裸鼠皮下,形成移植瘤,用传代移植瘤组织作为移植材料,进行胫骨原位移植及皮下移植。分别于移植后4周和8周处死小鼠,进行病理形态学检查,并对两种方法在成瘤率、生长方式及侵袭、转移等生物学行为比较。结果 两种移植方式在成瘤率及形态学上无明显不同,胫骨原位移植的潜伏期较短,并且生长快于皮下移植方式。皮下移植瘤呈局限性膨胀生长,有不完整的纤维包膜,瘤内类骨基质较少见,未见肺转移,观察8周时无明显消瘦;而胫骨原位移植瘤侵袭周围组织,可见发生肺转移,8周明显消瘦。原位移植的裸鼠血清ALP水平高于皮下移植者。原位移植的X线检查有明显的类似于人的骨性反应。结论 用人骨肿瘤细胞系HOS-98皮下接种的移植瘤作为移植材料是建立肿瘤异位移植的可行途径,裸鼠胫骨微环境较皮下组织更适合于人骨肉瘤的侵袭及转移表达,裸鼠胫骨原位移植模型的恶性生物学行为更接近临床骨肉瘤患者的体内侵袭及转移实际,该原位移植模型为今后的实验研究提供了更加接近患者实际的实验模型。     

白桦脂酸对人宫颈癌裸鼠移植瘤的抑制作用及机制

目的 探讨白桦脂酸（BA）对人宫颈癌HeLa细胞株裸鼠皮下移植瘤生长的抑制作用及其机制。方法 将4×10⁶个HeLa细胞接种于裸鼠右肩背部皮下,建立人宫颈癌裸鼠皮下移植瘤模型,24只荷瘤裸鼠随机分为BA高剂量（80mg／kg）、中剂量（40mg／kg）、低剂量（20mg／kg）组及空白对照组（含溶剂）,每组6只,隔日腹腔注射连续给药21d,停药24 h后处死裸鼠,测量裸鼠体重、移植瘤体积、瘤重,计算抑瘤率;光镜下观察移植瘤组织形态学变化;TUNEL法检测肿瘤细胞凋亡指数;免疫组化法检测瘤组织内caspase-3、CytoC蛋白表达。结果 裸鼠处死后,BA处理组的移植瘤体积均明显小于空白对照组（P＜0.01）,其中高、中、低剂量组抑瘤率分别为56.2％、40.4％和24.6％ （P＜0.01）;HE染色法显示BA处理组小鼠的移植瘤组织出现明显凋亡及坏死改变;TUNEL检测对照组和BA低、中、高剂量组的凋亡指数分别为（8.36±2.78）％、（20.98±3.01）％、（28.74±4.77）％和（39.34±6.15）％（P＜0.05）;免疫组化法示BA处理组的肿瘤组织caspase-3、CytoC蛋白表达水平较空白对照组明显升高（P＜0.01）。结论 BA对人宫颈癌HeLa细胞移植瘤的生长具有明显的抑制作用,其机制可能与上调caspase-3、CytoC蛋白的表达及诱导细胞凋亡有关。     

生存素基因RNAi对宫颈癌裸鼠移植瘤生长、凋亡和放射敏感性的影响

背景与目的：生存素基因是近年来肿瘤研究的焦点之一,本研究旨在观察生存素基因RNAi对宫颈癌裸鼠移植瘤生长、凋亡和放射敏感性的影响。方法：随机选择雌性BALB／c—nu／nu裸小鼠24只,细胞接种法建立4组人宫颈癌裸鼠皮下移植瘤模型,每天观察裸鼠一般状况及肿瘤生长情况,通过绘制肿瘤生长曲线并计算肿瘤生长抑制率,观察生存素基因RNAi对人宫颈癌裸鼠皮下移植瘤生长的影响;通过免疫组化SP法检测各组移植瘤组织中生存素蛋白表达情况,Ⅷ因子相关抗原（factor Ⅷ related antigen,FⅧRAg）表达情况并计算微血管密度（MVD）,HE染色及TUNEL染色观察生存素基因RNAi对人宫颈癌裸鼠皮下移植瘤凋亡的影响;当肿瘤体积达0．2cm^3时予X线放射治疗观察生存素基因RNAi对人宫颈癌裸鼠皮下移植瘤放疗敏感性的影响。结果：成功建立4组人宫颈癌裸鼠皮下移植瘤模型,接种HeLa-s2组裸鼠肿瘤体积在每个检测点均明显小于接种HeLa组。观察结束时,接种HeLa—s2组裸鼠瘤重明显小于接种HeLa组,分别为（0．369&#177;0．043）g和（1．150&#177;0．136）g（P〈0．05）;接种HeLa—s2组裸鼠肿瘤生长抑制率为67．9％。免疫组化结果显示：接种HeLa-s2组裸鼠生存素蛋白表达显著下降;接种HeLa—s2组裸鼠FⅧRag表达亦显著下降,MVD值降至23．4&#177;3．1。HE染色、TUNEL染色结果显示：接种HeLa—s2组裸鼠细胞凋亡明显增多,AI值达（22．7&#177;1．4）％。X线放疗后不同检测点接种HeLa—s2组裸鼠肿瘤体积明显小于接种HeLa组,肿瘤生长明显受抑。观察结束后,接种HeLa～s2组裸鼠瘤重明显小于接种HeLa组,分别为（0．41&#177;0．06）g和（1．38&#177;0．29）g（P〈0．05）。接种HeLa—s2组裸鼠肿瘤细胞凋亡明显增多,与接种HeLa组AI比较,接种HeLa—s2组AI明显升高,分别为（30．06&#177;0．98）％和（4．17&#177;0．64）％（P〈0．05）。结论：生存素基因RNAi可通过下调移植瘤组织生存素蛋白表达降低其MVD,从而抑制移植瘤生长并促进其凋亡,并通过增加X线放射治疗诱导的细胞凋亡,增强放射治疗对移植瘤的生长抑制,进而提高移植瘤的放射敏感性。     

流式细胞术检测肿瘤相关蛋白在人卵巢上皮性肿瘤裸鼠冻融卵巢组织移植中的意义

目的 通过对人卵巢上皮性肿瘤裸鼠原位移植瘤的癌旁组织相关蛋白的检测,探讨癌旁正常卵巢组织筛选的标准及冻融卵巢组织移植的可行性.方法 将人卵巢上皮性肿瘤OVCAR3细胞于裸小鼠颈背部近腋窝处皮下种植获取瘤源,行卵巢原位移植后,取癌组织、癌旁近端组织、癌旁中段组织、癌旁远端组织及正常裸鼠卵巢组织,采用流式细胞术检测各组织中的细胞角蛋白-7（CK-7）、CA125、p53、Survivin、基质金属蛋白酶-2（MMP-2）、金属蛋白酶组织抑制物-2（T1MP-2）的表达量;分别取全部指标阴性组、CK-7（-）CA125（-）Survivin（-）组、CK-7（＋）CA125（＋）Survivin（＋）组的组织、癌组织和冻融正常裸鼠卵巢组织进行移植,分析各组移植后的癌变率及CA125水平变化,同时检测原位移植后不同病变程度的裸鼠血清CA125水平.结果 从52份人卵巢上皮性肿瘤裸鼠原位移植瘤模型中获取46份（88.5％）活组织检查正常的癌旁残余卵巢组织;仅卵巢种植裸鼠血清CA125水平高于正常裸鼠（P＜0.01）,低于卵巢外种植裸鼠（P＜0.05）.原位移植瘤组织中CK-7、CA125、p53、Survivin、MMP-2及TIMP-2的表达率分别为93.3 ％（28/30）、93.3 ％（28/30）、86.7％（26/30）、86.7％（26/30）、83.3％（25/30）、83.3％（25/30）,癌旁近端组织的表达率分别为70.0％（21/30）、70.0％（21/30）、63.3％（19/30）、63.3％（19/30）、60.0％（18/30）、56.7％（17/30）,癌旁中段组织的表达率分别为33.3％（10/30）、30.0％（9/30）、30.0％（9/30）、30.0％（9/30）、26.7％（8/30）、23.3％（7/30）,癌旁远端组织的表达率分别为26.7％（8/30）、23.3％（7/30）、26.7％（8/30）、26.7 ％（8/30）、30.0％（9/30）、30.0％（9/30）;20份原位移植正常卵巢组织上述指标均为阴性.癌旁近端组织中CK-7、CA125、p53、Survivin、MMP-2及TIMP-2的表达率低于癌组织（P＜0.05）,高于癌旁中段组织及癌旁远端组织（P＜0.01）;癌旁中段组织及癌旁远端组织表达率差异无统计学意义（P＞0.05）.癌旁组织CK-7、CA125、Survivin的强阳性表达率明显高于p53、MMP-2、TIMP-2（P＜ 0.05）.全部指标表达阴性组或CK-7（-）CA125（-）Survivin（-）组的组织移植后,未发现癌变,其癌变率及CA125水平低于CK-7（＋）CA125（＋）Survivin（＋）组（P＜0.01,P＜0.05）.结论 CK-7、CA125、p53、Survivin、MMP-2及TIMP-2等分子指标的表达向无癌方向呈递减趋势,这些肿瘤相关基因表达全部阴性或主要指标CK-7、CA125、Survivin阴性均可作为筛选癌旁残余正常卵巢组织的标准,流式细胞术可作为筛查残留癌灶及隐匿转移的有效方法;人卵巢上皮性肿瘤裸鼠冻融卵巢组织移植安全、可行.     

神经菌毛素在胰腺癌组织及MIA PaCa-Ⅱ细胞系中的表达

目的探讨神经菌毛素（Neuropilin-1，NRP-1）在胰腺导管癌组织及MIA PaCa-Ⅱ胰腺癌细胞系中的表达及意义。方法运用免疫组化和RT-PCR法分别检测在正常胰腺组织、癌旁组织、胰腺癌组织及MIA PaCa-Ⅱ细胞系中Neuropilin-1蛋白及mRNA表达水平。结果蛋白水平：可见正常胰腺组织无表达，癌旁组织轻度表达，而胰腺癌组织及MIA PaCa-Ⅱ胰腺癌细胞中高水平表达。神经组织也可表达Neuropilin-1 mRNA水平见正常胰腺组织呈微量表达，癌旁组织中度表达，而胰腺癌组织及MIA PaCa-Ⅱ胰腺癌细胞中呈高水平表达。结论Neuropilin-1可能与参与了胰腺癌的发生发展，在胰腺癌神经转移中可能起着重要作用。     

The role of manganese superoxide dismutase in the growth of pancreatic adenocarcinoma

Chronic pancreatitis, K-ras oncogene mutations, and the subsequent generation of reactive oxygen species (ROS) appear to be linked to pancreatic cancer. ROS have also been suggested to be mitogenic and capable of stimulating cell proliferation. Cells contain antioxidant enzymes to regulate steady state levels of ROS produced by products of metabolism. The aims of our study were to determine antioxidant enzyme activity in pancreatic cancer cells and correlate enzyme activity with tumor growth, as well as determine whether tumor cell growth could be altered with antioxidant gene transfection. Western blots, enzyme activity, and enzyme activity gels were performed for manganese superoxide dismutase (MnSOD), copper/zinc, catalase, and glutathione peroxidase in normal human pancreas and in the human pancreatic cancer cell lines BxPC-3, Capan-1, MIA PaCa-2, and AsPC-1. Cell population doubling times were determined and correlated with antioxidant enzyme activity. MnSOD was overexpressed in MIA PaCa-2 using an adenoviral vector, and the effect on cell growth was determined. The cell pancreatic cancer lines BxPC-3, MIA PaCa-2, and AsPC-1 had decreased levels of MnSOD immunoreactive protein as well as activity and decreases in MnSOD levels correlated well with increased rates of tumor cell proliferation as determined by cell doubling time. No correlation could be found between cell growth and levels of copper/zinc superoxide dismutase, catalase, or glutathione peroxidase. Enforced expression of MnSOD by adenovirus transfection in the rapid growing cell line MIA PaCa-2 increased MnSOD immunoreactivity and MnSOD activity and decreased growth rate. Overexpression of MnSOD may be effective in growth suppression of pancreatic cancer.     

Cyclooxygenase-2 expression in human pancreatic adenocarcinomas

Cyclooxygenase-2 (COX-2) expression is up-regulated in several types of human cancers and has also been directly linked to carcinogenesis. To investigate the role of COX-2 in pancreatic cancer, we evaluated COX-2 protein expression in primary human pancreatic adenocarcinomas (n = 23) and matched normal adjacent tissue (n = 11) by immunoblot analysis. COX-2 expression was found to be significantly elevated in the pancreatic tumor specimens compared with normal pancreatic tissue. To examine whether the elevated levels of COX-2 protein observed in pancreatic tumors correlated with the presence of oncogenic K-ras, we determined the K-ras mutation status in a subset of the tumors and corresponding normal tissues. The presence of oncogenic K-ras did not correlate with the level of COX-2 protein expressed in the pancreatic adenocarcinomas analyzed. These observations were also confirmed in a panel of human pancreatic tumor cell lines. Furthermore, in the pancreatic tumor cell line expressing the highest level of COX-2 (BxPC-3), COX-2 expression was demonstrated to be independent of Erk1/2 activation. The lack of correlation between COX-2 and oncogenic K-ras expression suggests that Ras activation may not be sufficient to induce COX-2 expression in pancreatic tumor cells and that the aberrant activation of signaling pathways other than Ras may be required for up-regulating COX-2 expression. We also report that the COX inhibitors sulindac, indomethacin and NS-398 inhibit cell growth in both COX-2-positive (BxPC-3) and COX-2-negative (PaCa-2) pancreatic tumor cell lines. However, suppression of cell growth by indomethacin and NS-398 was significantly greater in the BxPC-3 cell line compared with the PaCa-2 cell line (P = 0.004 and P < 0.001, respectively). In addition, the three COX inhibitors reduce prostaglandin E(2) levels in the BxPC-3 cell line. Taken together, our data suggest that COX-2 may play an important role in pancreatic tumorigenesis and therefore be a promising chemotherapeutic target for the treatment of pancreatic cancer.     

Role of Rac1-dependent NADPH oxidase in the growth of pancreatic cancer

K-ras mutations occur in as high as 95% of patients with pancreatic cancer. K-ras activates Rac1-dependent NADPH oxidase, a key source of superoxide. Superoxide has an important function in pancreatic cancer cell proliferation, and scavenging or decreasing the levels of superoxide inhibits pancreatic cancer cell growth both in vitro and in vivo. DNA microarray analysis and RT-PCR has demonstrated that Rac1 is also upregulated in pancreatic cancer. The aim of this study was to determine whether inhibiting Rac1 would alter pancreatic tumor cell behavior. Human pancreatic cancer cells with mutant K-ras (MIA PaCa-2), wild-type K-ras (BxPC-3) and the immortal H6c7 cell line (pancreatic ductal epithelium) expressing K-ras oncogene (H6c7eR-KrasT) that is tumorigenic, were infected with a dominant/negative Rac1 construct (AdN17Rac1). In cells with mutant K-ras, AdN17Rac1 decreased rac activity, decreased superoxide levels and inhibited in vitro growth. However, in the BxPC-3 cell line, AdN17Rac1 did not change rac activity, superoxide levels or in vitro cell growth. Additionally, AdN17Rac1 decreased superoxide levels and inhibited in vitro growth in the KrasT tumorigenic cell line, but had no effect in the immortalized H6c7 cell line. In human pancreatic tumor xenografts, intratumoral injections of AdN17Rac1 inhibited tumor growth. These results suggest that activation of Rac1-dependent superoxide generation leads to pancreatic cancer cell proliferation. In pancreatic cancer, inhibition of Rac1 may be a potential therapeutic target.     

CNT1 expression influences proliferation and chemosensitivity in drug-resistant pancreatic cancer cells

Overcoming the inherent chemoresistance of pancreatic cancers remains a major goal of therapeutic investigations in this disease. In this study, we discovered a role for the human concentrative nucleoside transporter-1 (hCNT1; SLC28A1), a high-affinity pyrimidine nucleoside transporter, in determining the chemosensitivity of human pancreatic cancer cells to gemcitabine, the drug used presently as a standard of care. Compared with normal pancreas and pancreatic ductal epithelial cells, hCNT1 expression was frequently reduced in pancreatic tumors and tumor cell lines. In addition, hCNT1-mediated (3)H-gemcitabine transport was lower in pancreatic cancer cell lines and correlated with cytotoxic IC(50) estimations of gemcitabine. In contrast to gemcitabine-sensitive pancreatic cancer cell lines, MIA PaCa-2, a gemcitabine-resistant pancreatic cancer cell line, exhibited relatively restrictive, cell cycle-dependent hCNT1 expression and transport. hCNT1 translation was suppressed in the late G1-enriched MIA PaCa-2 cell population possibly in an miRNA-dependent manner, which corresponded with the lowest hCNT1-mediated gemcitabine transport during this phase. Although hCNT1 protein was induced during G1/S transition, increased hCNT1 trafficking resulted in maximal cell surface recruitment and transport-overshoot in the G2/M phase-enriched cell population. hCNT1 protein was directed predominantly to proteasomal or lysosomal degradation in S or G2/M phase MIA PaCa-2 cells, respectively. Pharmacological inhibition of hCNT1 degradation moderately increased cell surface hCNT1 expression and cellular gemcitabine transport in MIA PaCa-2 cells. Constitutive hCNT1 expression reduced clonogenic survival of MIA PaCa-2 cells and steeply augmented gemcitabine transport and chemosensitization. In addition to supporting a putative tumor suppressor role for hCNT1, our findings identify hCNT1 as a potential candidate to render drug-resistant pancreatic cancer cells amenable to chemotherapy.     

K-ras 抗原致敏的DC诱导CTL 对胰腺癌体内杀伤活性的研究*

目的:研究K-ras多肽的致敏树突状细胞（DC）活化的特异性细胞毒性T 淋巴细胞（CTL）对胰腺癌的体内外杀伤作用。方法:联合应用粒细胞- 巨噬细胞集落刺激因子和白细胞介素-4 诱导培养外周血DC。表达K-ras突变体的胰腺癌细胞株全瘤、单纯K-ras突变体多肽和K-ras突变体表位肽阳离子纳米颗粒分别致敏DC。致敏DC刺激T 淋巴细胞得到肿瘤抗原特异的细胞毒性T 淋巴细胞（CTL）。 Patu 8988、SW1990细胞系制备荷瘤裸鼠模型评价CTL 体内抗肿瘤活性。结果:负载全瘤抗原的DC其诱导产生的CTL 对胰腺癌有较好的抑制,负载单纯K-ras（12-Val ）突变体多肽、K-ras（12-Val ）突变体表位肽阳离子纳米颗粒的DC其诱导产生的CTL 对表达K-ras（12-Val ）突变体阳性（Patu 8988）的胰腺癌有较特异的抑制作用,而对K-ras（12-Val ）突变体阴性（SW1990）的胰腺癌的抑制作用与对照组比较无显著性差异。结论:负载肿瘤抗原的DC诱导的CTL 可显著提高对荷瘤裸鼠的生存时间,抑制肿瘤的生长速度,并显示其可增加抗肿瘤特异性。      

In vivo selection and characterization of metastatic variants from human pancreatic adenocarcinoma by using orthotopic implantation in nude mice

We determined whether the implantation of human pancreatic cancer cells into the pancreas of nude mice can be used to select variants with increasing metastatic potential. COLO 357 line fast-growing cells were injected into the spleen or pancreas of nude mice. Hepatic metastases were harvested, and tumor cells were reinjected into the spleen or pancreas. This cycle was repeated several times to yield cell lines L3.6sl (spleen to liver) and L3.6pl (pancreas to liver). The variant cells produced significantly higher incidence and number of lymph node and liver metastases than the parental cells. Their increased metastatic potential was associated with increased expression (mRNA and protein) of the proangiogenic molecules basic fibroblast growth factor, vascular endothelial growth factor, and interleukin-8. The metastatic cells also exhibited increased motility and invasiveness, which were associated with increased expression of collagenase type IV (MMP-9) and decreased expression of E-cadherin. Collectively, the data show that the orthotopic implantation of human pancreatic cancer cells in nude mice is a relevant model with which to study the biology of pancreatic cancer metastasis and to select variant cell lines with enhanced metastatic potential.