大鼠肺癌癌变过程中Rb肿瘤抑制途径失控的意义

目的 :探讨大鼠肺癌癌变过程中Rb肿瘤抑制途径的主要成员p16、CyclinD1和CDK4基因的动态表达和肺癌发生发展及侵袭转移的关系。方法 :用 3 甲基胆蒽 (3 methylcholanthrene,MCA)及二乙基亚硝胺 (diethylnitrosa mine,DEN)碘油溶液在 80只大鼠诱发大鼠肺癌 ,12只作为对照组。应用免疫组织化学及原位杂交技术检测大鼠肺癌癌变各阶段组织的p16、CyclinD1和CDK4基因的改变。结果 :随大鼠肺癌的发生发展 ,p16基因呈不同程度的缺失或低表达 ,其中p16蛋白在 6 0 .75 % (6 5 10 7)的大鼠肺癌中缺失表达 ;p16蛋白表达的阳性率在对照组及癌前病变与肺癌相比差异有极显著性 (P <0 .0 1) ;浸润癌与原位癌相比 ,p16蛋白阳性率的差异有显著性 (P <0 .0 5 )。CyclinD1、CDK4的表达在对照组较弱或阴性 ,而在实验组有不同程度的过表达 ,阳性率范围分别为 10 .0 0 %～ 79.0 7%、15 .0 0 %～ 72 .0 9% ;在不典型增生与原位癌、原位癌与浸润癌之间 ,cyclinD1和CDK4表达的升高有显著性 (P <0 .0 5 )。大鼠肺癌癌变中p16与cyclinD1呈负相关 (P <0 .0 1) ,Pearson列联系数为 0 .5 30 7;CDK4与CyclinD1呈正相关(P <0 .0 1) ,Pearson列联系数为 0 .5 782 ;p16与CDK4无明显相关性 (P >0 .0 5 )。p16、CyclinD1、CDK4与大鼠肺癌发?

Deregulation Significance of Rb Tumor Suppression Pathway during Carcinogenesis of Lung Cancer in Wistar Rats

Objective: To investigate the effect of p16INK4a cyclin D1/cyclin dependent kinase4(CDK4) retinoblastoma(Rb) pathway during lung carcinogenesis and its metastasis in rats. Methods: 3 methylcholanthrene(MCA) and diethyinitrosamine(DEN) to induce lung squamous cell carcinoma by intra left lobar bronchial instillation in Wistar rats was used. 80 induced lung cancer rats and 12 control rats instilled with iodized oil were killed in turn from 15 to 270 days. Expression of p16,Cyclin D1 and CDK4 was evaluated by immunohistochemistry(IHC). In situ hybridization was used to confirm expression of specific mRNAs. Results: During carcinogenesis,loss of protein expression of p16INK4a was observed in 60.75 per cent(65/107) of induced lung cancer but cyclin D1 and CDK4 overexpression in 61.68 per cent(66/107) and 58.88 per cent(63/107) respectively. The expression of p16INK4a in induced lung cancer was significantly reduced compared to those of normal bronchial epithelium and premalignant lesions (P<0.01). There were significant differences in p16 and CDK4 expression in carcinoma in situ(CIS) versus infiltration carcinoma (P<0.05). Significant differences were found in cyclin D1 and CDK4 expression between dysplasia and CIS(P<0.05). Cyclin D1 expression was significantly higher in infiltration carcinoma than that in CIS and early stage infiltration carcinoma(P<0.01,P<0.05 respectively). There was a negative correlation between p16 and Cyclin D1 (P<0.01),and pearson coefficient was 0.530 7. The expression of CDK4 was positively correlated with Cyclin D1(P<0.01),and pearson coefficient was 0.578 2. p16,Cyclin D1 and CDK4 were all related to lung cancer metastasis in rats(P<0.05). Conclusion:Deregulation the p16INK4a cyclin D1/CDK4 Rb pathway may be involved in tumorigenesis of induced lung cancer in Wistar rats from early stage, both the low expression of p16 and the overexpression of Cyclin D1 may cooperate in the maliglant progression of induced lung cancer.