Fiorentino M, Altimari A, D'Errico A, Cukor B, Barozzi C, Loda M, Grigioni W F
Department of Hematology-Oncology, University of Bologna, Italy.
Clin Cancer Res. 2000 Oct;6(10):3966-72.
The p27 cyclin-dependent kinase inhibitor is a negative regulator of cell-cycle progression. In many human epithelial malignancies, decreased expression of p27 correlates with high grade, early recurrence, and poor prognosis. To evaluate the prognostic significance of p27 in hepatocellular carcinoma (HCC), we studied 54 HCCs along with corresponding nontumoral tissue. Immunohistochemistry (IHC) and Western blot (WB) analysis before and after immunoprecipitation with Cdk2 were performed on paraffin-embedded tissues and protein homogenates, respectively, to compare localization and expression of the p27 protein and to determine the total and active (Cdk2-bound) fractions of p27. Correlations were analyzed between IHC-assessed levels of p27, survival, and major clinical and pathological variables. IHC revealed no p27 expression in the majority of hepatocytes from normal and cirrhotic liver, whereas 14 HCCs (26%) were high p27 expressers (>50% positive cells), 26 (48%) low expressers (<50% positive cells), and 14 (26%) negative. High IHC signals of p27 correlated with Cdk2-bound p27 as assessed by immunoprecipitation-WB; by contrast, WB alone displayed similar levels of p27 protein in all normal and tumoral samples. High IHC p27 expression correlated with prolonged survival (P = 0.027), whereas the presence of cirrhosis was associated with poor outcome (P = 0.029). We conclude that with respect to their nonneoplastic counterparts, a subset of HCCs acquire significant p27 expression and that high expression of p27 is a favorable independent prognostic parameter for HCC.
p27细胞周期蛋白依赖性激酶抑制剂是细胞周期进程的负调节因子。在许多人类上皮性恶性肿瘤中，p27表达降低与高分级、早期复发及预后不良相关。为评估p27在肝细胞癌（HCC）中的预后意义，我们研究了54例HCC以及相应的非肿瘤组织。分别对石蜡包埋组织和蛋白质匀浆进行免疫组化（IHC）以及用Cdk2免疫沉淀前后的蛋白质印迹（WB）分析，以比较p27蛋白的定位和表达，并确定p27的总量及活性（与Cdk2结合的）部分。分析了IHC评估的p27水平、生存率以及主要临床和病理变量之间的相关性。IHC显示，正常和肝硬化肝脏的大多数肝细胞中无p27表达，而14例HCC（26%）为p27高表达者（阳性细胞>50%），26例（48%）为低表达者（阳性细胞<50%），14例（26%）为阴性。通过免疫沉淀-WB评估，p27的高IHC信号与与Cdk2结合的p27相关；相比之下，单独的WB显示所有正常和肿瘤样本中p27蛋白水平相似。高IHC p27表达与生存期延长相关（P = 0.027），而肝硬化的存在与预后不良相关（P = 0.029）。我们得出结论，相对于其非肿瘤对应物，一部分HCC获得了显著的p27表达，并且p27的高表达是HCC一个有利的独立预后参数。
