AIM:To investigate p27 expression in hepatocellularcarcinoma (HCC),adjacent nontumoral and normal livertissues,and to verify whether the subcellular localizationof p27 was altered in HCC.METHODS:The level of p27 in tumoral,nontumoral,andnormal liver tissues were assessed by immunohistochemical(IHC) analysis.Parallel immunostaining was done forproliferating cell nuclear antigen (PCNA) to evaluate cellproliferation.RESULTS:The labeling index (LI) of p27 in tumoral lesionswas significantly lower than that in adjacent nontumorallesions (t=2.444,P=0.017) and normal controls (t=2.268,P=0.029).The LI of p27 significantly decreased in patientswith massive type (t=2.227,P=0.037) and infiltration(t=2.197,P=0.036).The prognosis of patients with higherp27 LI was longer than that of patients with lower p27 LI(P=0.0247,log-rank test).The LI of PCNA was significantlyhigher in HCC than that in adjacent nontumoral lesions(t=2.092,P=0.041) and normal controls (t=3.533,P=0.002).There was no significant correlation between p27expression and cell proliferation in tumor samples.Thelevel of p27 in the cytoplasmic fraction was higher in tumoraland nontumoral liver tissues,and was associated withclinical stage (t=2.520,P=0.029) and the degree of invasion(t=2.640,P=0.019).Survival analysis showed that p27 wasan independent prognosis marker for HCC patients.CONCLUSION:These results suggest that p27 underexp-ressing in patients with HCC is closely associated withinfiltration,metastasis,and prognosis.Alterations in thesubcellular localization of p27 protein may occur earlyduring hepatocarcinogenesis. AIM: To investigate p27 expression in hepatocellular carcinoma (HCC), adjacent nontumoral and normal livertissues, and to verify whether the subcellular localization of p27 was altered in HCC. METHODS: The level of p27 in tumoral, nontumoral, and normal liver tissues were assessed by immunohistochemical IHC) analysis.Parallel immunostaining was done for proliferating cell nuclear antigen (PCNA) to evaluate cellproliferation.RESULTS: The labeling index (LI) of p27 in tumoral lesions was significantly lower than that in adjacent nontumorallesions (t = 2.444, P = 0.017) and normal The LI of p27 significantly decreased in patients with massive type (t = 2.227, P = 0.037) and infiltration (t = 2.197, P = 0.036) .The prognosis of patients with higher p27 LI was longer than that of patients with lower p27 LI (P = 0.0247, log-rank test). The LI of PCNA was significantlyhigher in HCC than that of adjacent nontumoral lesions (t = 2.092, , P = 0.002). There was no significant c orrelation between p27expression and cell proliferation in tumor samples. The level of p27in the cytoplasmic fraction was higher in tumoraland nontumoral liver tissues, and was associated withclinical stage (t = 2.520, P = 0.029) and the degree of invasion (t = 2.640, P = 0.019). Survival analysis showed that p27 wasan independent prognosis marker for HCC patients. CONCLUSION: These results suggest that p27 underexp-ressing in patients with HCC is closely associated within filtration, metastasis, and prognosis. Alterations in the subcellular localization of p27 protein may occur earlyduring hepatocarcinogenesis.