Reduced p27Kip1 expression in hepatocellular carcinomas

Oncogenic and tumor suppressor pathways in subchronic aflatoxicosis in rats: Association with serum and urinary aflatoxin exposure biomarkers

In this study, the changes in oncogenic and tumor suppressor signaling pathways in liver and their association with serum and urinary biomarkers of aflatoxin exposure were evaluated in Wistar rats fed diets containing aflatoxin B1 (AFB1) for 90 days. Rats were divided into four groups (n = 15 per group) and assigned to dietary treatments containing 0 (control), 50 (AFB50), 100 (AFB100) and 200 μg AFB1 kg-1 diet (AFB200). Multiple preneoplastic foci of hepatocytes marked with glutathione-S-transferase-placental form (GST-P) were identified in AFB100 and AFB200 groups. Hepatocellular damage induced by AFB1 resulted in overexpression of cyclin D1 and β-catenin. The liver expression of retinoblastoma (Rb) and p27Kip1 decreased in AFB100 and AFB200 groups, confirming the favorable conditions for neoplastic progression to hepatocellular carcinoma. All samples from rats fed AFB1-contaminated diets had quantifiable AFB1-lysine in serum or urinary AFM1 and AFB1-N7-guanine, with mean levels of 20.42-50.34 ng mL-1, 5.31-37.68 and 39.15-126.37 ng mg-1 creatinine, respectively. Positive correlations were found between AFB1-lysine, AFM1 or AFB1-N7-guanine and GST-P+, β-catenin+ and cyclin D1+ hepatocytes, while Rb + cells negatively correlated with those AFB1 exposure biomarkers. The pathways evaluated are critical molecular mechanisms of AFB1-induced hepatocarcinogenesis in rats.

Growth Arrest-Specific Transcript 5 (GAS5) Exerts Important Roles on the Treatment of BM45 Cells of Liver Cirrhosis

Bone marrow (BM)-derived CD45 (BM45) cells were demonstrated to exhibit an improved antifibrotic effect on the treatment of CCL4-induced liver fibrosis by significantly increasing the level of matrix metalloproteinase 9 (MMP-9). In this study, we aimed to validate the therapeutic effect of BM45 on the treatment of liver cirrhosis and to further investigate the molecular mechanism underlying the effect of growth arrest-specific transcript 5 (GAS5) on BM45. Accordingly, GAS5 significantly suppressed miR-222 and miR-21 expression but enhanced p27 and MMP-9 expression in HepG2 and LX2 cells. Additionally, GAS5 obstructed transforming growth factor (TGF)-β-induced dysregulation of miR-222, p27, and α-smooth muscle actin (α-SMA) in mice. GAS5 showed a considerable potential to enhance the capability of BM45 in restoring the normal expression of CCL4, miR-222, miR-21, MMP-9, p27, and α-SMA that was dysregulated by alanine aminotransferase (ALT), albumin, and fibrosis. In summary, our study validated the regulatory relationship between miR-21 and MMP-9, as well as between miR-222 and p27. The overexpression of GAS5 upregulated the expression of MMP-9 and p27 via respectively reducing the miR-222 and miR-21 expression, resulting in higher BM45-induced activation of hepatic stellate cells (HSCs). Accordingly, same results were obtained in an animal model, indicating that GAS5 may exert a positive effect on the treatment of BM45 of liver cirrhosis.

The clinicopathological and prognostic significance of P27kip in hepatocellular carcinoma patients: A systemic review and meta-analysis

OBJECTIVES

P27^kip is a cyclin-dependent kinase inhibitor that has gained importance as a biomarker in human malignant tumors. However, the potential role of P27^kip in hepatocellular carcinoma remains unclear. The aim of this meta-analysis was to explore whether P27^kip acts as prognostic and clinicopathological roles in hepatocellular carcinoma patients.

METHODS/MATERIALS

An electronic search based on three databases, PubMed, Embase, and Web of Science, was performed to select a sufficient number of studies. Pooled hazard ratio (HR) and odds ratio (OR) were used as estimates to investigate the association among P27^kip expression, prognosis and clinicopathological features.

RESULTS

In total, we identified 18 studies with 1774 hepatocellular carcinoma patients. The result derived from four studies revealed a significant positive association between lower P27^kip levels and shorter overall survival (HR = 0.550, 95% CI: 0.464-0.652, P < 0001) and disease-free survival (HR = 0.420, 95% CI: 0.308-0.571, P < 0.0001). Analyses of the clinicopathological features and P27^kip expression also showed that a positive rate of P27^kip was significantly lower in a larger sized tumor (OR = 0.538, 95% CI: 0.315-0.919, P = 0.023). The results also revealed that lower P27^kip levels were correlated with poorer differentiation (0.416, 95% CI: 0.178-0.971, P = 0.043). Additionally, the pooled OR of 0.389 also presented a significant correlation between P27^kip underexpression and the metastasis of HCCs (95% CI: 0.155-0.975, P = 0.044).

CONCLUSIONS

This analysis suggests a strong association among P27^kip underexpression, poorer prognosis and aggressive progression of hepatocellular carcinoma in patients. P27^kip may be a tumor suppressor for predicting the progression and survival outcome in patients with hepatocellular carcinomas.

The Complex Relationship between Liver Cancer and the Cell Cycle: A Story of Multiple Regulations

The liver acts as a hub for metabolic reactions to keep a homeostatic balance during development and growth. The process of liver cancer development, although poorly understood, is related to different etiologic factors like toxins, alcohol, or viral infection. At the molecular level, liver cancer is characterized by a disruption of cell cycle regulation through many molecular mechanisms. In this review, we focus on the mechanisms underlying the lack of regulation of the cell cycle during liver cancer, focusing mainly on hepatocellular carcinoma (HCC). We also provide a brief summary of novel therapies connected to cell cycle regulation.

p27 Is a critical prognostic biomarker in non-alcoholic steatohepatitis-related hepatocellular carcinoma

Non-alcoholic steatohepatitis (NASH) is a recently identified chronic liver disease, which progresses to liver cirrhosis and hepatocellular carcinoma (HCC). As the number of patients studied to date has been limited, clinically useful prognostic biomarkers of NASH-related HCC have not been available. In this study, we investigated the status of a cell-cycle regulator, p27, in NASH-related HCC. p27 has been regarded as a prognostic factor in various types of cancer patients. A total of 22 cases with NASH-related HCC were analyzed for p27 protein expression, and phosphorylation at threonine 157 (T157) and serine 10 (S10) by immunohistochemical analysis. The correlation of p27 with tumor characteristics, disease-free survival (DFS), and overall survival was analyzed. p27 expression was decreased in 13 HCCs (59%), and was significantly correlated with enlarged tumor size (p = 0.01) and increased cell proliferation (p < 0.01). Phospho-p27 at T157 and S10 was detected in four (18%) and seven (32%) cases, respectively, and patients positive for phospho-p27 (S10) showed reduced DFS (hazard ratio 7.623, p = 0.016) by univariate analysis. Further studies with more patients are required to verify the usefulness of p27 as a biomarker for predicting tumor recurrence in NASH patients.

Genetic variants of p21 and p27 and hepatocellular cancer risk in a Chinese Han population: a case-control study

The p21 (Cip1/CDKN1A) and p27 (Kip1/CDKN1B) are members of the Cip/Kip family of cyclin-dependent kinase inhibitors, which can arrest cell proliferation and serve as tumour suppressors. We hypothesized that genetic variants in p21 and p27 may modify individual susceptibility to hepatocellular carcinoma (HCC). To test this hypothesis, we evaluated the associations of the polymorphisms of Ser31Arg and C+20T in p21 and C-79T and Gly109Val in p27, as well as their combinations, with HCC risk in a case-control study of 476 HCC cases and 526 cancer-free controls in a Chinese population. The matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry method was performed to detect these polymorphisms. We found that the variant genotypes of p21 Ser31Arg and p27 C-79T were individually associated with a significantly increased risk of HCC, but no associations were observed for other variant genotypes. Moreover, the combined variant genotypes of the four loci were associated with a significantly increased HCC risk (adjusted OR = 2.24, 95% CI = 1.72, 2.91 among subjects carrying 3 or more variant alleles), especially among HbsAg-positive individuals (adjusted OR = 3.09, 95% CI = 1.86, 5.14). Furthermore, the combined variant genotypes of the four loci (carrying three or more variant alleles) increased a 1.93-fold (95% CI = 1.20, 3.09) and 1.76-fold (95% CI = 1.17, 2.64) risk of HCC among smokers and nonsmokers. The variant genotypes of the two genes in this study have negative correlation with the clinicopathologicals observed. These results suggest that p21 polymorphisms individually or in combination with p27 polymorphisms increases risk of HCC, particularly among HbsAg-positive individuals.

Promoter hypermethylation of p73 and p53 genes in cervical cancer patients among north Indian population

Hypermethylation of CpG islands leads to transcriptional silencing and it is the predominant mechanism of tumor suppressor gene inactivation in many tumors. Methylation-specific polymerase chain reaction was performed to analyse the methylation status of the promoter region of the tumor suppressor genes. Hypermethylation of the 5' CpG island of the p21 ( CIP1 ), p27 ( KIP1 ), p57 ( KIP2 ), p53, p73 and RB 1 gene promoter were found in 8.8, 8.8, 11.2, 12, 25.6 and 4.8 % of 125 cervical cancer samples from north Indian population, respectively. Methylation of p73 was significantly (P < 0.001) associated with the cervical cancer cases in comparison to controls. Significant correlation was also observed between the methylation of p73 gene and increase in the risk of cervical cancer among passive smokers. Promoter hypermethylation of p53 gene was also observed to be significant among oral contraceptive users and cervical cancer patients having age at first sexual intercourse <20 years whereas hypermethylation of other genes was not found to be significant in the present study. This is the first report showing significant hypermethylation of p73 and p53 genes among cervical cancer patients in north Indian population. This is also the first report on significant p53 hypermethylation in cervical cancer in any population. Our findings did not show any correlation between promoter methylation of p73 and the other genes under study with clinicopathological parameters, including human papillomavirus infection and stage of the disease. The frequency of aberrant methylation of p73 and p53 gene promoter was unchanged according to the age of patients.

Identification of genes, including the gene encoding p27Kip1, regulated by serine 276 phosphorylation of the p65 subunit of NF-kappaB

Phosphorylation of the p65 subunit of NF-kappaB is required for its transcriptional activity. Recent reports show that phosphorylation of p65 at serine 276 regulates only a subset of genes, such as those encoding IL-6, IL-8, Gro-beta, and ICAM-1. In order to identify additional genes regulated by serine 276 phosphorylation, HepG2 hepatoma cells were infected with adenoviruses encoding either wild-type p65 or the S276A mutant of p65, followed by DNA microarray analysis. The results show that mutation of serine 276 affected the expression of several genes that encode proteins involved in cell cycle regulation, signal transduction, transcription, and metabolism. Notably, expression of S276A increased the mRNA and protein level of p27, a cell cycle inhibitory protein, which led to an increased association of p27 with cdk2, and inhibition of cdk2 activity. Furthermore, while wild-type NF-kappaB is known to increase cell proliferation in a number of different cancer cell lines, our data shows that S276A inhibited cell proliferation. Evidence is mounting that NF-kappaB plays a pivotal role in oncogenesis. Therapeutic agents that regulate the phosphorylation of serine 276 and p27 gene expression, therefore, may be useful as anti-cancer agents in the future.

p27(Kip1)is overexpressed in very early stages of hepatocarcinogenesis

Hepatocellular carcinoma (HCC) associated with chronic liver disease evolves from precancerous lesions and early HCC to more malignant forms. Despite the demonstrated importance of cell-cycle regulators in tumor biology, there have been few studies of their role in multistep hepatocarcinogenesis. Expression of p27(Kip1) and a degradation pathway associated protein, S-phase kinase-interacting protein 2 (Skp2), was therefore evaluated in surgically resected specimens of eight adenomatous hyperplasias, 16 early HCC and 126 classical HCC. Immunohistochemistry revealed no p27(Kip1) expression in the majority of hepatocytes from normal and cirrhotic liver, whereas positive staining for p27(Kip1) protein was found in 75.0% and 93.8% of adenomatous hyperplasias and early HCC, respectively. The average p27(Kip1) labeling indices (LI) for adenomatous hyperplasias, early HCC, well differentiated HCC, moderately differentiated HCC and poorly differentiated HCC were 36.99, 43.59, 47.73, 49.24, and 30.21, respectively. Real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) analyses confirmed the increases. Skp2 LI were also significantly elevated in accordance with stepwise progression of hepatocarcinogenesis. Increased expression of Skp2 mRNA was observed most frequently in less differentiated tumors and Kaplan-Meier survival analysis showed a significantly association with a poor prognosis (P = 0.0496). In conclusion, a high level of p27(Kip1) expression is evident from early stages of hepatocarcinogenesis, indicating that this parameter could be a useful diagnostic marker for precancerous lesions and early HCC. In addition, Skp2 expression correlates with tumor dedifferentiation and may contribute to biological aggression in HCC.

MiR-221 controls CDKN1C/p57 and CDKN1B/p27 expression in human hepatocellular carcinoma

The identification of target mRNAs is a key step for assessing the role of aberrantly expressed microRNAs in human cancer. MiR-221 is upregulated in human hepatocellular carcinoma (HCC) as well as in other malignancies. One proven target of miR-221 is CDKN1B/p27, whose downregulation affects HCC prognosis. Here, we proved that the cyclin-dependent kinase inhibitor (CDKI) CDKN1C/p57 is also a direct target of miR-221. Indeed, downregulation of both CDKN1B/p27 and CDKN1C/p57 occurs in response to miR-221 transfection into HCC-derived cells and a significant upregulation of both CDKN1B/p27 and CDKN1C/p57 occurs in response to antimiR-221 transfection. A direct interaction of miR-221 with a target site on the 3' UTR of CDKN1C/p57 mRNA was also demonstrated. By controlling these two CDKIs, upregulation of miR-221 can promote growth of HCC cells by increasing the number of cells in S-phase. To assess the relevance of these studies in primary tumors, matched HCC and cirrhosis samples were assayed for miR-221, for CDKN1B/p27 and CDKN1C/p57 expression. MiR-221 was upregulated in 71% of HCCs, whereas CDKN1B/p27 and CDKN1C/p57 proteins were downregulated in 77% of cases. A significant inverse correlation between miR-221 and both CDKN1B/p27 and CDKN1C/p57 was found in HCCs. In conclusion, we suggest that miR-221 has an oncogenic function in hepatocarcinogenesis by targeting CDKN1B/p27 and CDKN1C/p57, hence promoting proliferation by controlling cell-cycle inhibitors. These findings establish a basis toward the development of therapeutic strategies aimed at blocking miR-221 in HCC.

Expression and hypermethylation of p27kip1 in hepatocarcinogenesis

AIM: To study the expressions of p27^kip1 protein and p27mRNA, the hypermethylation of p27^kip1 and the relation between them in various stages of hepatocarcinogenesis.

METHODS: p27 protein and p27mRNA were detected by immunohistochemical staining and in situ hybridization respectively in 68 cases of normal liver, liver cirrhosis, pericancerous cirrhosis and hepatocellular carcinoma (HCC). The hypermethylation of p27^kip1 was detected by methylation-specific PCR (MSP) in 44 cases of normal liver, liver cirrhosis, and HCC.

RESULTS: The positive rate of p27 protein was 66.7% (4/6) in normal liver, 60.0% (6/10) in liver cirrhosis, 50.0% (12/24) in pericancerous cirrhosis and 21.4% (6/28) in HCC. There were no statistical differences in normal liver, liver cirrhosis and pericancerous cirrhosis, but the positive rate of p27 protein significantly decreased in HCC compared to that in the other groups (P = 0.006, χ² = 7.664). The positive rate of p27^kip1 mRNA was 83.3% (5/6) in normal liver, 70.0% (7/10) in liver cirrhosis, 75.0% (18/24) in pericancerous cirrhosis and 25.0% (7/28) in HCC. There were no statistical differences in normal liver, liver cirrhosis and pericancerous cirrhosis, but the positive rate of p27^kip1 mRNA also significantly decreased in HCC compared to that in the other groups (P = 0.000, χ² = 16.600). In addition, there was a significant correlation between the expression of p27 protein and p27mRNA in the integrated group of normal liver and liver cirrhosis. However, no significant correlation was found between pericancerous cirrhosis and HCC. Using MSP, we found that 1 HCC in 44 cases (including 6 cases of normal liver, 10 cases of liver cirrhosis and 28 cases of HCC) was methylated, whose p27 protein and p27mRNA were negative.

CONCLUSION: The reduction or loss of p27 protein and p27mRNA are potentially involved in hepatocarcinogenesis. The hypermethylation of p27 might lead to the loss of p27mRNA transcription.

Guanine nucleotide depletion triggers cell cycle arrest and apoptosis in human neuroblastoma cell lines

Mycophenolic acid (MPA) specifically inhibits inosine-5'-monophosphate dehydrogenase, the first committed step toward GMP biosynthesis. In its morpholinoethyl ester pro-drug form it is one of the most promising immunosuppressive drugs recently developed. The aim of the present study was to investigate the in vitro effects of MPA, at concentrations readily attainable during immunosuppressive therapy, on 3 human neuroblastoma cell lines (LAN5, SHEP and IMR32). Mycophenolic acid (0.1-10 microM) caused a decrease of intracellular levels of guanine nucleotides, a G(1) arrest and a time- and dose-dependent death by apoptosis. These effects, associated with an up-regulation of p53, p21 and bax, a shuttling of p53 protein into the nucleus and a down-regulation of bcl-2, survivin and p27 protein, were reversed by the simultaneous addition of guanine or guanosine and were more evident using nondialysed serum containing hypoxanthine. These results suggest that in neuroblastoma cell lines clinically attainable concentrations of mycophenolic acid deplete guanine nucleotide pools triggering G(1) arrest and apoptosis through p53-mediated pathways, indicating a potential role of its morpholinoethyl ester pro-drug in the management of patients with neuroectodermal tumors.

Mechanisms of c-myc-mediated transcriptional repression of growth arrest genes

Constitutive expression of the proto-oncogene c-myc results in oncogenic activation and contributes to progression of a wide range of human and animal tumors. Myc executes its multiple activities mostly through transcriptional regulation of the target genes. The special interest of this review is the mechanism of transcriptional repression of cell cycle inhibitors by Myc. Myc suppresses expression of cell cycle/growth arrest genes gas1, p15, p21, p27, and gadd34, -45, and -153. It appears that Myc represses growth arrest gene transcription by at least two distinct mechanisms. One mechanism is limited to the binding of Myc-Max heterodimers to the Inr element in their promoters and inhibition of Miz-1 or other transcriptional activators via the C-terminal domain of c-Myc. This mechanism requires DNA binding of the Myc-Max complex to Inr sequences. The other mechanism is dependent on c-Myc binding to the Sp1 transcription factor via the c-Myc central region and inhibition of Sp1 transcriptional activity. At this time it is not entirely clear which Sp1-containing promoters will be repressed by c-Myc and what other modes of c-Myc transcriptional repression may exist. The ability of c-Myc to repress transcription of growth arrest genes may contribute to its potential to promote proliferation and oncogenesis.

P21 functions to maintain quiescence of p27-deficient hepatocytes

Hepatocytes rarely proliferate in the healthy adult liver. We explored the roles of the cyclin kinase inhibitors p21 and p27 in maintaining hepatocyte quiescence. p27 is expressed throughout the wild-type liver, but the related protein p21 was not detected. However, p21 was detected in livers of p27-deficient mice. Increased p21 protein levels did not result from an increase in p21 mRNA expression, indicating that p21 expression is regulated post-transcriptionally. p21 protein levels increased in cultured primary hepatocytes treated with the proteasome inhibitor MG132 and cycloheximide, indicating that p21 expression is regulated at the level of protein stability in liver cells. Although increased expression of cyclin-dependent kinase (Cdk) 4, Cdk2, and proliferating cell nuclear antigen was detected in p27-deficient livers, increased hepatocyte proliferation was detected only in livers of mice deficient for both p21 and p27. In p27-deficient livers, p21 was found in complexes with Cdk2 and CdK4 and can compensate for the absence of p27. Our data indicate that cyclin kinase inhibitor activity is important for maintaining hepatocyte quiescence in the adult liver. Significant increases in p21 were detected in multiple tissues of mature p27-deficient mice compared with wild-type mice, suggesting that the ability of p21 to functionally substitute for p27 is not liver-specific.

Cell cycle deregulation in liver lesions of rats with and without genetic predisposition to hepatocarcinogenesis

Preneoplastic and neoplastic hepatocytes undergo c-Myc up-regulation and overgrowth in rats genetically susceptible to hepatocarcinogenesis, but not in resistant rats. Because c-Myc regulates the pRb-E2F pathway, we evaluated cell cycle gene expression in neoplastic nodules and hepatocellular carcinomas (HCCs), induced by initiation/selection (IS) protocols 40 and 70 weeks after diethylnitrosamine treatment, in susceptible Fisher 344 (F344) rats, and resistant Wistar and Brown Norway (BN) rats. No interstrain differences in gene expression occurred in normal liver. Overexpression of c-myc, Cyclins D1, E, and A, and E2F1 genes, at messenger RNA (mRNA) and protein levels, rise in Cyclin D1-CDK4, Cyclin E-CDK2, and E2F1-DP1 complexes, and pRb hyperphosphorylation occurred in nodules and HCCs of F344 rats. Expression of Cdk4, Cdk2, p16(INK4A), and p27(KIP1) did not change. In nodules and/or HCCs of Wistar and BN rats, low or no increases in c-myc, Cyclins D1, E, and A, and E2F1 expression, and Cyclin-CDKs complex formation were associated with p16(INK4A) overexpression and pRb hypophosphorylation. In conclusion, these results suggest deregulation of G1 and S phases in liver lesions of susceptible rats and block of G1-S transition in lesions of resistant strains, which explains their low progression capacity.

Molecular aspects of hepatic carcinogenesis

Exogenous agents correlated with hepatocellular carcinoma (HCC) have been identified and well characterized. These agents, including the different viruses that cause chronic hepatitis and cirrhosis, can lead to regenerative nodules and dysplastic nodules/adenomatous hyperplasia. These conditions associated with several molecular alterations of hepatocyte ultimately culminate in hepatocellular carcinoma. Recently, there has been a great progress in the identification of somatic and germinative mutations that may be correlated with the development of HCC, justifying a review on the subject. Hence, the factors involved in the process of hepatic carcinogenesis, such as infection by the hepatitis B and C viruses, with a special focus in the molecular alterations described in recent years are discussed herein, pointing out areas potentially relevant for clinical development.

FUP1, a gene associated with hepatocellular carcinoma, stimulates NIH3T3 cell proliferation and tumor formation in nude mice

Human primary hepatocellular carcinoma (HCC)is one of the highly prevalent malignant diseases worldwide, the identification of HCC-associated genes has been a major approach in elucidating the molecular mechanism of tumorigenesis of HCC. In our previous studies, a function-unknown gene, which displayed marked expression difference between the HCC sample and normal liver control has been detected by cDNA microarray. This gene was named after fup1 (function-unknown protein 1), and was cloned according to the data of GenBank. The cDNA of fup1 has an open-reading frame 1233 base pairs in size. Here, the function analysis of FUP1 related to HCC is being reported. The NIH3T3 cells transiently transfected with FLAG-conjugated FUP1 revealed strong nuclear staining in immunofluorescent assay. Furthermore, cell proliferation enhancing activity of fup1 was shown by MTT assay in stable transfectant NIH3T3 cell line with pcDNA3-derived plasmid having fup1 under the regulation of pCMV, while cell proliferation repressing activity of antisense fup1 was observed in BEL7404 stable transfectant cells. Tumorigenicity of the above stable transfectant cells was analyzed in nude mice compared with appropriate controls. The result was in good agreement with MTT assay. Elevated tumorigenicity of fup1 transfected NIH3T3 cell and repressed tumorigenicity of antisense fup1 transfected BEL7404 cell were clearly demonstrated. The results above suggested that fup1 might be a critical gene related to carcinogenesis of HCC. Detailed molecular function of fup1 remains to be elucidated.

Reduced p21(WAF1/CIP1) protein expression is predominantly related to altered p53 in hepatocellular carcinomas

To investigate the relationship between the expression of p21(WAF1/CIP1) protein and p53 status and the possible role of the two proteins in hepatocellular carcinomas (HCCs), we examined the expression of p21(WAF1/CIP1) and p53 immunohistochemically in 81 tumours from 65 patients with hepatocellular carcinoma. p21(WAF1/CIP1) protein was absent from 59 of 81 tumours (72.8%), and altered p53 expression was found in 43 (53.1%). p21(WAF1/CIP1) expression was significantly associated with p53 status (P = 0.0008); 38 of 59 tumours lacking p21(WAF1/CIP1) protein were accompanied by altered p53 expression. Further analyses showed that p21(WAF1/CIP1) expression was inversely correlated with p53 expression in hepatitis C virus (HCV)-related HCCs, but not in HBV-related hepatocellular carcinomas and hepatocellular carcinomas without viral infection. All 11 tumours with intrahepatic metastasis showed altered p21(WAF1/CIP1) or p53 expression. In contrast, no intrahepatic metastasis was found in any of the 17 tumours without abnormal expression of either of the two proteins. These results suggest that: (1) different modes of p21(WAF1/CIP1) regulation are involved in HCCs differing in their hepatitis viral infection status, and p21(WAF1/CIP1) expression appears to be predominantly related to altered p53 in HCV-related HCCs; (2) disruption of the p53-p21(WAF1/CIP1) cell-cycle-regulating pathway may contribute to malignant progression of HCC.

Loss of p16(INK4) protein, alone and together with loss of retinoblastoma protein, correlate with hepatocellular carcinoma progression

To investigate the role of p16(INK4) protein absence in hepatocellular carcinoma progression, we examined p16(INK4) expression immunohistochemically in 81 primary and 23 metastatic lesions of hepatocellular carcinoma, in which retinoblastoma protein status had been determined. p16(INK4) protein was absent from 44% of the total of 104 tumors. The rate of p16(INK4) absence was twice as high in metastatic lesions (74%) compared with primary lesions (36%) (P=0.001). Loss of p16(INK4) and/or retinoblastoma protein was significantly associated with decreased tumor differentiation, vascular invasion and metastasis. In conclusion, p16(INK4) protein absence, alone and together with loss of retinoblastoma protein, contributes to hepatocellular carcinoma progression.

Mutational analysis of the p27(kip1) gene in hepatocellular carcinoma

p27(Kip1) is an inhibitor of cyclin-dependent kinase. It has been reported that reduced p27(Kip1) expression is present in human hepatocellular carcinoma. To determine the role of p27(Kip1) in hepatocarcinogenesis, 46 cases with hepatocellular carcinomas were studied. p27(Kip1) mutation was first screened by single strand conformation polymorphism, and direct DNA sequencing was then performed on those cases with mobility shifts. Two polymorphism sites were found. One is a previously described polymorphism at codon 109 (GTC-->GGC) which was found in two cases. The second polymorphism was identified at codon 55 (GCG-->GCA) in six of the 46 cases. However, the polymorphism at codon 55 was also present in seven of 93 healthy controls (7.5%), indicating that it is not associated with a predisposition for development of hepatocellular carcinoma (Fisher's exact test, 0.05). These results show that p27(Kip1) mutation is not a frequent event in human hepatocellular carcinoma, and suggest that it may be inactivated predominantly by transcriptional and/or posttranscriptional regulation rather than genomic aberrations.

p27(Kip1) expression in normal epithelia, precancerous lesions, and carcinomas of the gallbladder: association with cancer progression and prognosis

p27(Kip1) is a cyclin-dependent kinase inhibitor that negatively regulates cell proliferation. This study was designed to evaluate the roles of p27(Kip1) in gallbladder carcinogenesis and the prognostic value of p27(Kip1) in patients with gallbladder carcinoma. p27(Kip1) expression was examined immunohistochemically in surgically resected specimens of 8 normal epithelia, 8 adenomyomatosis lesions, 6 precancerous adenomas, and 37 carcinomas of the gallbladder. Decreased p27(Kip1) expression (<50% nuclear staining) was observed in 16 of the 37 (43%) gallbladder carcinomas, but not in any specimen of normal epithelium, adenomyomatosis, or adenoma. The fact that all of the adenomas showed normal p27(Kip1) expression suggests that decreased p27(Kip1) expression is probably not an early event in gallbladder carcinogenesis. Decreased p27(Kip1) expression was significantly associated with less marked tumor cell differentiation (P =.017), lymphatic invasion (P =.046), lymph node metastasis (P =.007), and advanced TNM stage (stage IV vs. stage I, P =.026; stage IV vs. stage II, P =.005). This suggests that down-regulation of p27(Kip1) expression is a late event in gallbladder carcinogenesis, possibly promoting tumor progression and metastasis. Kaplan-Meier curves showed that decreased p27(Kip1) expression was significantly associated with shorter overall survival (P =.001) in patients with gallbladder carcinomas who had undergone radical surgery. Cox's proportional hazards model revealed decreased p27(Kip1) expression to be an independent predictor for death (P =.034; risk ratio, 3.9; 95% confidence interval, 1.1-13.7). In conclusion, decreased p27(Kip1) expression significantly correlates with tumor progression and predicts poor prognosis in gallbladder carcinomas.

Over-expression and lack of retinoblastoma protein are associated with tumor progression and metastasis in hepatocellular carcinoma

To determine the role of retinoblastoma (Rb) gene alteration in hepatocarcinogenesis, we examined Rb protein expression immuno-histochemically in a series of surgically resected specimens including non-cancerous liver tissues with cirrhosis or chronic hepatitis, large regenerative nodules, pre-cancerous adenomatous hyperplasias as well as primary and metastatic lesions of hepatocellular carcinoma (HCC). All of the non-cancerous liver tissues, large regenerative nodules and adenomatous hyperplasias showed normal Rb protein expression. Altered Rb protein expression was observed in 31 (lack of Rb protein in 16 and over-expression in 15) of the 81 primary HCCs (38%) and was significantly associated with tumor differentiation grade: altered Rb protein expression occurred in 1 of 23 (4%), 16 of 43 (37%) and 14 of 15 (93%) well-, moderately and poorly differentiated tumors (moderately vs. well-differentiated p < 0.01; poorly vs. moderately differentiated p < 0.001). Incidences of both Rb protein absence and over-expression were higher for moderately differentiated than for well-differentiated tumors and even higher for poorly differentiated tumors. Rb protein absence and over-expression were observed in 9 (39%) and 10 (44%) of the 23 metastatic lesions of HCC, respectively, and the incidence of altered Rb protein expression (absence or over-expression) was significantly higher than in primary lesions (83% vs. 38%, p < 0.001). Our observations suggest that elevated and absent Rb protein are closely associated with tumor progression and developing metastatic disease rather than tumor initiation in cases of HCC. Int. J. Cancer (Pred. Oncol.) 84:604-608, 1999.

Decreased p27(Kip1) expression and cyclin D1 overexpression, alone and in combination, influence recurrence and survival of patients with resectable extrahepatic bile duct carcinoma

This study was undertaken to identify potential abnormalities of p27(Kip1) and cyclin D1 expression in extrahepatic bile duct carcinomas and to assess the prognostic significance of p27(Kip1) and cyclin D1 levels for patients with this disease. Decreased p27(Kip1) expression (<50% nuclei staining) and cyclin D1 overexpression (>5% nuclei staining) was observed immunohistochemically in 19 (56%) and 23 (68%) of the 34 tumors examined, respectively. Both decreased p27(Kip1) and cyclin D1 overexpression were associated with relapse (P =.0005 for p27(Kip1) and P =.0004 for cyclin D1). Kaplan-Meier curves showed that both decreased p27(Kip1) and cyclin D1 overexpression correlate significantly with shortened survival rates (for p27(Kip1), P =.0419 and P =.002 for overall and disease-free survival; for cyclin D1, P =.0392 and P =.0021 for overall and disease-free survival). Cox regression model analyses identified decreased p27(Kip1) and cyclin D1 overexpression as independent markers predicting death from relapse (P =.0371, risk ratio: 3.891 for p27(Kip1); P =.0429, risk ratio: 8.31 for cyclin D1). Decreased p27(Kip1) was associated with cyclin D1 overexpression (P =.0202), and coincident abnormalities of the 2 proteins occurred in 16 of the 34 (47%) tumors, indicating that extrahepatic bile duct carcinoma progression may require synchronous dysfunction of p27(Kip1) and cyclin D1 in about half of patients. Patients with tumors showing coincident abnormalities of p27(Kip1) and cyclin D1 showed even more frequent recurrence than patients with an alteration in only 1 of the 2 proteins. In conclusion, decreased p27(Kip1) expression and cyclin D1 overexpression, alone and in combination, predict poor prognosis in patients with resectable extrahepatic bile duct carcinoma.