The effect of adenovirus expressing wild-type p53 on 5-fluorouracil chemosensitivity is related to p53 status in pancreatic cancer cell lines

AIM:There are conflicting data about p53 function on cellular sensitivity to the cytotoxic action of 5-fluorouracil (5-FU). Therefore the objective of this study was to determine the combined effects of adenovirus-mediated wild-type (wt) p53 gene transfer and 5-FU chemotherapy on pancreatic cancer cells with different p53 gene status. METHODS:Human pancreatic cancer cell lines Capan-1^(p53mut), Capan-2^(p53wt),FAMPAC^(p53mut),PANC1^(p53mut),and rat pancreatic cancer cell lines AS^(p53wt) and DSL6A^(p53null) were used for in vitro studies.Following infection with different ratios of Ad- p53-particles (MOI) in combination with 5-FU,proliferation of tumor cells and apoptosis were quantified by cell proliferation assay (WST-1) and FACS (PI-staining).In addition,DSL6A syngeneic pancreatic tumor cells were inoculated subcutaneously in to Lewis rats for in vivo studies. Tumor size,apoptosis (TUNEL) and survival were determined. RESULTS:Ad-p53 gene transfer combined with 5-FU significantly inhibited tumor cell proliferation and substantially enhanced apoptosis in all four cell lines with an alteration in the p53 gene compared to those two cell lines containing wt-p53.In vivo experiments showed the most effective tumor regression in animals treated with Ad-p53 plus 5-FU.Both in vitro and in vivo analyses revealed that a sublethal dose of Ad-p53 augmented the apoptotic response induced by 5-FU. CONCLUSION:Our results suggest that Ad-p53 may synergistically enhance 5-FU-chemosensitivity most strikingly in pancreatic cancer cells lacking p53 function.These findings illustrate that the anticancer efficacy of this combination treatment is dependent on the p53 gene status of the target tumor cells.

抑癌基因DPC4/SMAD4的缺失表达与胰腺肿瘤的关系

目的 综述DPC4/SMAD 4的缺乏表达与胰腺癌发生的关系。方法 复习相关文献 ,并综述成文。结果与结论 DPC4/SMAD4是一种新的肿瘤抑制基因 ,定位于第 1 8号染色体长臂 1 8q2 1 .1的位置。它编码的蛋白SMAD 4参与了转移生长因子 β(TGF β)超家族细胞内信号传导。SMAD 4是信号传递蛋白SMADS的功能活动中心。DPC4/SMAD 4基因的缺失表达与胰腺癌发病密切有关。

胰腺癌中nm23基因的表达

目的 探讨nm23基因及蛋白在胰腺癌中的表达水平及其与转移的关系。方法 用Northern blot分析、原位杂交及免疫组织化学法分别对16例正常胰腺及29例胰腺癌中的nm23基因及蛋白的表达进行检测。结果 nm23在胰腺癌组织中的表达高于正常胰腺组织,无转移的胰腺癌组织nm23表达高于有转移的胰腺癌组织。结论 nm23与胰腺癌的转移和恶化密切相关。

5-杂氮脱氧胞嘧啶核苷联合吉西他滨对胰腺癌细胞株原钙黏蛋白8基因表达的影响

目的研究5-杂氮脱氧胞嘧啶核苷（5-Aza—CdR）对胰腺癌细胞株Capan-2原钙黏蛋白8（protocadherin8，PCDH8）基因DNA启动子甲基化的转录调控，以及联合吉西他滨对癌细胞生长抑制与凋亡的影响。方法采用MTT法、流式细胞术检测5-Aza—CdR及联合吉西他滨对Capan-2细胞的抑制率与凋亡率。应用甲基化特异性PCR（MSP）、RT—PCR和Westernblot的方法检测不同浓度5-Aza—CdR处理细胞前后PCDH8基因的甲基化状态、mRNA表达水平和蛋白表达水平。结果5-Aza-CdR能使胰腺癌细胞Capan-2增长速度减慢，呈浓度依赖性，联合吉西他滨显著抑制细胞生长；5-Aza—CdR联合吉西他滨与单药组、对照组相比，可显著诱导细胞凋亡。不同浓度的5-Aza—CdR可逆转PCDH8基因在胰腺癌细胞Capan-2的甲基化，恢复mRNA表达水平和蛋白表达水平，并呈一定的浓度正相关。结论5-Aza—CdR可有效逆转PCDH8基因在胰腺癌细胞株Capan-2的高甲基化状态，解除DNA高甲基化导致的基因沉默，重新诱导基因mRNA转录和蛋白表达，同时可抑制胰腺癌细胞生长，与吉西他滨有协同抗肿瘤作用。