p53 mutation and overexpression in hepatocellular carcinoma and dysplastic nodules in the liver

Hepatic Precancerous Lesions and Early Hepatocellular Carcinoma

This review discusses the diagnostic challenges of diagnosing and treating precursor lesions of hepatocellular carcinoma (HCC) in both cirrhotic and non-cirrhotic livers. The distinction of high-grade dysplastic nodule (the primary precursor lesion in cirrhotic liver) from early HCC is emphasized based on morphologic, immunohistochemical, and genomic features. The risk factors associated with HCC in hepatocellular adenomas (precursor lesion in non-cirrhotic liver) are delineated, and the risk in different subtypes is discussed with emphasis on terminology, diagnosis, and genomic features.

Immunohistochemical Determination of p53 Protein Overexpression for Predicting p53 Gene Mutations in Hepatocellular Carcinoma: A Meta-Analysis

BACKGROUND

Whether increased expression of the tumor suppressor protein p53 indicates a p53 gene mutation in hepatocellular carcinoma (HCC) remains unclear. We conducted a meta-analysis to determine whether p53 protein overexpression detected by immunohistochemistry (IHC) offers a diagnostic prediction for p53 gene mutations in HCC patients.

METHODS

Systematic literature searches were conducted with an end date of December 2015. A meta-analysis was performed to estimate the diagnostic accuracy of IHC-determined p53 protein overexpression in the prediction of p53 gene mutations in HCC. Sensitivity, subgroup, and publication bias analyses were also conducted.

RESULTS

Thirty-six studies were included in the meta-analysis. The results showed that the overall sensitivity and specificity for IHC-determined p53 overexpression in the diagnostic prediction of p53 mutations in HCC were 0.83 (95% CI: 0.80-0.86) and 0.74 (95% CI: 0.71-0.76), respectively. The summary positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were 2.65 (95% CI: 2.21-3.18) and 0.36 (95% CI: 0.26-0.50), respectively. The diagnostic odds ratio (DOR) of IHC-determined p53 overexpression in predicting p53 mutations ranged from 0.56 to 105.00 (pooled, 9.77; 95% CI: 6.35-15.02), with significant heterogeneity between the included studies (I2 = 40.7%, P = 0.0067). Moreover, subgroup and sensitivity analyses did not alter the results of the meta-analysis. However, potential publication bias was present in the current meta-analysis.

CONCLUSION

The upregulation of the tumor suppressor protein p53 was indeed linked to p53 gene mutations. IHC determination of p53 overexpression can predict p53 gene mutations in HCC patients.

p21/Wafl/Cipl cellular expression in chronic long-lasting hepatitis C: correlation with HCV proteins (C, NS3, NS5A), other cell-cycle related proteins and selected clinical data

Studies indicate that proteins of hepatitis C virus (HCV) disturb expression of cell-cycle-related proteins. A disturbed cell-cycle control is a hepatocellular carcinoma (HCC) risk factor in patients with HCV-related liver damage. The present study aimed to analyse the cellular expression of p21/Wafl/Cipl (p21) in long-lasting chronic hepatitis C (CH-C), its correlation with the key oncogenic HCV proteins (C, NS3, NS5A), other cell-cycle-related proteins (PCNA, Ki-67, cyclin D1, p53) and selected clinical data. Archival liver biopsies, obtained from patients with CH-C, normal livers, and hepatocellular carcinoma (HCC) specimens were analysed by immunocytochemistry and ImmunoMax technique. In CH-C overexpression of p21 protein was demonstrated. Positive correlations of p21 protein expression in CH-C involved age of the patients, grading, and liver steatosis. Moreover, expression of p21 correlated significantly with expression of p53 protein, of D1 cyclin and Ki-67. Although Ki-67 antigen was related to p21 expression, only Ki-67 expression proved to be directly related to liver staging. Expression of the NS3 protein, which prevailed in CH-C patients, manifested correlation with p21 expression, and that of cyclin D1. In presence of preserved potential for regeneration, overexpression of p21 indicates inhibition of cell cycle in hepatocytes, which probably plays a protective role for the chronically damaged cells. Out of the three HCV proteins only NS3 seems to affect control of p21 protein expression in in vivo infection. Nevertheless, the studies indicate that neither expression of p21 protein nor that of viral NS3 protein can serve as a marker of progression of CH-C to HCC in vivo.

p53 immunocytochemistry and TP53 gene mutations in patients with chronic hepatitis C virus (HCV) infection

Chronic infection with hepatitis C virus (HCV) is regarded as a risk factor for hepatocellular carcinoma (HCC), mostly in patients with liver cirrhosis. Present study aimed at evaluation of cellular expression of p53 protein, genetic TP53 changes in liver samples and anti-p53 in serum of patients with chronic hepatitis C virus infection. The expression of p53 protein were analysed by immunocytochemistry in liver biopsies from adult patients with chronic, long-lasting hepatitis C. In order to detect TP53 mutations, PCR/SSCP and sequencing were performed. Antibodies against p53 in serum were determined using enzyme immunoassay (ELISA).In two out of 14 examined patients TP53 point mutations were detected in the liver samples. In the first patient, a substitution of C to T was demonstrated in position 1 of the codon 250, resulting in substitution of proline by serine. The other patient carried a substitution of C to G in position 13274 of the intron 6. The patient carrying mutation in the codon 250 demonstrated morphological traits of liver cirrhosis and had high number of p53-immunoreactive cell nuclei in tissue. None of the patients manifested elevated titres of serum anti-p53. In the liver, significant positive correlations were disclosed between expression of p53 on one hand and grading and staging on the other. A negative correlation was disclosed between cellular expression of p53 and duration time of infection. In conclusions, genetic changes in TP53 can be detected also in non-neoplastic lesions linked to chronic HCV infection.

Hepatitis B virus-associated multistep hepatocarcinogenesis: a stepwise increase in allelic alterations

Hepatocarcinogenesis is a multistep process, but systematic analysis using a genetic or molecular approach to accurately delineate the different stages of hepatocellular carcinoma (HCC) development is scarce. In this study, we used genome-wide allelotyping to systematically evaluate the allelic alterations in the multisteps of hepatitis B virus-associated hepatocarcinogenesis. The overall fractional allelic loss (FAL) indices of cirrhosis, dysplastic nodules (DN), and HCC were significantly different, with a clear stepwise increase (P < 0.001). Loss of heterozygosity (LOH) was uncommon in cirrhotic livers (n = 24; mean FAL index +/- SD, 0.09 +/- 0.09; median, 0.07). In contrast, LOH was common in our 74 HCC nodules, which were predominantly hepatitis B virus-associated (mean FAL index +/- SD, 0.40 +/- 0.23; median, 0.38). The 18 DNs had FAL index (mean +/- SD, 0.27 +/- 0.19; median, 0.20) in between that of cirrhosis and HCC. Importantly, high-grade DNs had FAL index significantly higher than that of low-grade DNs (P = 0.031) and close to that of HCC, indicating that high-grade DNs were genetically closer to HCC. However, there was no significant difference in FAL indices between primary HCCs and their corresponding intrahepatic metastases, but this absence of major allelic losses in this transformation to a metastatic phenotype does not exclude small-scale chromosomal losses or gene deletions. To conclude, hepatitis B virus-associated hepatocarcinogenesis is a multistep process accompanied by stepwise increase in allelic losses from cirrhosis and low- and high-grade DN to HCC. Such allelic losses contribute to promote tumor development and progression.

Hepatic expression of the proliferative marker Ki-67 and p53 protein in HBV or HCV cirrhosis in relation to dysplastic liver cell changes and hepatocellular carcinoma

To evaluate hepatic expression of the nuclear proliferative marker Ki-67 and the p53 oncoprotein in hepatitis B virus (HBV)/HCV cirrhosis in relation to dysplastic liver cell changes and hepatocellular carcinoma (HCC). We studied needle liver biopsies from 107 patients with cirrhosis and no HCC (52 HBV, 55 HCV) who had been assessed for protocol studies, and 57 cirrhotic patients with HCC (40 HBV, 17 HCV). We evaluated small and large cell dysplastic changes along with the expression of Ki-67 and p53 by immunohistochemistry. The labelling index (LI) was defined as the proportion (%) of positive-stained nuclei of the 500 measured. Large and small cell dysplastic changes were observed in 12 and 9% of specimens respectively. Only small cell changes were associated with Ki-67 expression. Ki-67 LI was 5.50 +/- 5.7 in cirrhosis (13.90 +/- 3.84 in those with small cell dysplastic changes vs 4.64 +/- 4.98 in those without, P < 0.01), 10.2 +/- 5.95 in cirrhosis with HCC (P < 0.05) and 18.56 +/- 10 in HCC (P < 0.01). Neither the presence of small cell dysplastic changes nor the expression of Ki-67 was related to severity or aetiology of cirrhosis. Expression of p53 was observed in 30% of the non-tumorous and in 53% of the neoplastic tissue obtained from patients with HCC, with no differences between HCV and HBV. Ki-67 and p53 expression was associated with the tumour grade (P < 0.001). Our observations clearly demonstrate the association between the proliferation activity and the morphological changes in the cirrhotic liver from the non-dysplastic to dysplastic lesion to HCC. They also support the hypothesis that p53 alterations are a rather late event in carcinogenesis and related to HCC grade. And finally, they suggest that the final steps of hepatocarcinogenesis are common and independent of the aetiology of the chronic viral infection.

Overexpressed Id-1 is associated with a high risk of hepatocellular carcinoma development in patients with cirrhosis without transcriptional repression of p16

BACKGROUND

Inhibitor of differentiation/DNA binding protein 1 (Id-1) plays a pivotal role in the regulation of cell proliferation and carcinogenesis via inhibiting basic helix-loop-helix (HLH) transcription factors. Recently, Id-1 was found to repress p16 in tumorous tissue specimens including hepatocellular carcinoma (HCC), but its relevance in precancerous liver tissues is unknown.

METHODS

Id-1 expression in the liver tissue specimens of 112 patients with cirrhosis without HCC was studied by immunohistochemical analysis. Correlations were investigated between Id-1 expression and clinicopathologic features, the status of p16, and the risk of HCC occurrence.

RESULTS

A high expression of Id-1 was observed in 42 patients (38%). The level of Id-1 expression was not associated with clinical standard parameters or the status of p16 in cirrhotic tissue specimens. The cumulative incidence of HCC development was significantly higher in a group of patients with high Id-1 expression (P = 0.0008). Multivariate analysis revealed that increased Id-1 expression is an independent significant factor for the risk of HCC development in patients with cirrhosis (relative risk = 2.75, P = 0.003).

CONCLUSIONS

The results of the current study suggested that increased expression of Id-1 may play an important role in the early step of hepatocarcinogenesis, and might serve as a useful marker for determining patients with cirrhosis with a high risk of HCC occurrence.

Alterations of p53, Bcl-2, and hMSH2 protein expression in the cirrhotic, macroregenerative, dysplastic nodules and hepatocellular carcinomas in Upper Egypt

BACKGROUND

Hepatocarcinogenesis involves alterations in p53, Bcl-2 and human Mut S homologue-2 (hMSH2) genes. In Upper Egypt, the clinicopathologic and genetic changes during hepatocarcinogensis (cirrhotic nodules (CN); macroregenerative nodules (MRN) and dysplastic nodules (DN) are unknown.

METHODS

To examine these issues, 48 hepatic resection specimens entailing 25 CN, 16 MRN, 23 DN and 48 hepatocellular carcinoma (HCC) were immunohistochemically evaluated for p53, Bcl-2 and hMSH2 protein expression.

RESULTS

HCC was common in males than in females (2.6:1, P<0.05) and with hepatitis C virus than hepatitis B virus infection (77.1% vs. 18.7%, P=0.001). p53 expression was found in DN (3/23) and HCC (12/48). Its average weighted scores were high in DN/HCC as compared with CN (1.60+/-0.40 and 7.20+/-1.20, P=0.0001). Bcl-2 expression was seen in CN, MRN, DN and HCC (7/48). Its average weighted scores were high in DN (7.60+/-1.60), HCC (6.86+/-0.85) as compared with CN (6.14+/-0.42) and MRN (6.50+/-0.50, P=0.22). hMSH2 average weighted scores were reduced in HCC (7.94+/-1.06) as compared with CN (8.47+/-0.52), MRN (8.00+/-1.00) and DN (8.20+/-0.80, P>0.05).

CONCLUSION

In Upper Egypt: (1) HCC had similar clinicopathologic features to those in the high-risk regions, and (2) alterations of the p53, Bcl-2 and hMSH2 proteins occur during hepatocarcinogensis.

p16 Hypermethylation in the early stage of hepatitis B virus-associated hepatocarcinogenesis

Abnormality of the p16 expression is involved in the pathogenesis of hepatocellular carcinoma (HCC), and hypermethylation of p16 gene is known as a major p16 inactivation mechanism. Cirrhotic nodule (CN) is now regarded as a preneoplastic lesion that is frequently associated with microscopic foci of HCC through dysplastic nodules (DNs). This observation clearly supports a multistep hepatocarcinogenesis from CNs through DNs. We thus examined the methylation status of p16 gene in HCCs surrounded by DNs and CNs to define the significance of p16 hypermethylation in the early stage of hepatocarcinogenesis. We tested 24 hepatitis B virus (HBV)-associated CNs, 37 DNs, and 18 HCCs within DNs that were microdissected from paraffin-embedded tissue sections. Frequency of p16 hypermethylation was significantly high in HCCs within DNs (15/18. 83.3%) and it increased from CNs (15/24. 62.5%) through DNs (26/37, 70.3%). Interestingly, 11 out of 12 (91.7%) HCC associated with methylation-positive DNs revealed hypermethylation of p16, and 18 out of 23 (78.2%) DNs associated with methylation-positive CNs showed p16 hypermethylation. These data suggest that p16 hypermethylation in the early stages, CNs and DNs may predispose to HCC. In addition, p16 methylation status of five cell lines with or without HBV infection was examined to test whether the high frequency of hypermethylation is related to HBV infection. HBV-infected cell lines were exclusively methylation-positive. These data suggest that high frequency of hypermethylation may be associated with hepatitis B virus infection.

Expression of p53 and C-myc genes and its clinical relevance in the hepatocellular carcinomatous and pericarcinomatous tissues

AIM: To investigate the possible roles of p53 and C-myc genes in the primary hepatocellular carcinogenesis and the relationship between the liver hyperplastic nodule (LHN) and hepatocellular carcinoma (HCC).

METHODS: The expression of p53 and C-myc genes was detected immunohist-ochemically in 73 and 60 cases of HCC and pericarcinomatous tissues, respectively.

RESULTS: The positive expression of p53 in HCC was significantly higher than that in pericarcinomatous tissues (P < 0.05). In pericarcinomatous tissues, the p53 expression was observed only in LHN, but not in liver cirrhosis (LC) and normal liver tissues. The positive expression rate of C-myc in HCC or LHN was significantly higher than that in LC or normal liver tissues (P < 0.05 and P < 0.01), however, no significant difference was found between HCC and LHN (P > 0.05). The positive expression rate of p53 and C-myc in HCC was correlated with the histological differentiation, that in the poorly differentiated was significantly higher than that in well differentiated samples (P < 0.05).

CONCLUSION: The overexpression of p53 and C-myc genes might play a role in the carcinogenesis of HCC; And LHN seems a preneoplastic lesion related to hepatocarcinogenesis; No evidence supports that LC contribute directly to the hepatocarcinogenesis.

Molecular changes in hepatocellular dysplastic nodules on microdissected liver biopsies

The genetic profile of dysplastic hepatocellular nodules arising in cirrhosis is poorly understood. We assessed loss of heterozygosity (LOH) and microsatellite instability (MI) in 10 dysplastic nodules (4 low-grade and 6 high-grade) with surrounding cirrhosis and in 10 hepatocellular carcinomas (HCC). Six microsatellite loci were selected and investigated on microdissected needle biopsies. Twenty-four (24.4%) informative loci showed allelic loss, while MI was seen in 3 loci only (3%). The most involved sites were located on chromosomes 4q (54.5%) and 8p (50%). LOH was documented in 16.6%, cirrhotic, 50% low-grade dysplastic nodules (LGDN), 83% high-grade dysplastic nodules (HGDN), and 70% malignant nodules. LOH at multiple loci was increasingly seen from cirrhotic to HGDN, but not from the latter to HCC. The fractional allelic loss (FAL) was significantly increased in dysplastic and neoplastic nodules as compared with cirrhosis (P <.01). The progressive accumulation of genetic changes in cirrhotic, dysplastic, and malignant hepatocellular nodules is in keeping with a multistep process of carcinogenesis; within this spectrum, HGDN can be considered advanced precursors of HCC.

Overexpression of p53 protein is not directly related to hepatitis B x protein expression and is associated with neoplastic progression in hepatocellular carcinomas rather than hepatic preneoplasia

p53 mutations and binding of p53 to hepatitis B virus (HBV) x protein (HBx) have been suggested as alternative mechanisms of development of hepatocellular carcinomas (HCCs) in man, both processes resulting in intracellular accumulation of the protein which is detectable by immunohistochemical approaches. We have examined p53 expression in 149 explanted human livers, including 39 cases infected with HBV and 35 bearing HCC. p53 was demonstrated immunohistochemically in 51% of HCC samples (18/35), localized mainly in fast growing poorly differentiated areas. Accumulation of mutant p53 was verified by immunoprecipitation in most of the positive HCC samples (14/15), implying occurrence of p53 mutations. No cells positive for p53 were found in 354 preneoplastic hepatocellular lesions examined. This indicates that p53 mutation is associated with progression, rather than early development, of HCC in the low-aflatoxin B(1)-exposed region. The intracellular distribution patterns of p53 and HBx were different, with the former within nuclei and the latter confined to cytoplasmic compartment. HBx did not coimmunoprecipitate with p53. These data indicate that p53-HBx binding is infrequent, if it really occurs, in HBV-infected human liver, and that it cannot be a common mechanism of HBV-associated hepatocarcinogenesis. In addition, p53 accumulation was also observed in some parenchymal and ductular (oval) cells in cirrhotic livers and, more frequently, in fulminant hepatitis, being independent of HBx expression, and seemingly associated with the damage and/or regeneration of liver parenchyma, perhaps merely reflecting a cellular stress response.

Analysis of the p53 tumor suppressor gene in rheumatoid arthritis synovial fibroblasts

OBJECTIVE

To determine whether mutations in the tumor suppressor gene p53 may contribute to the transformed-appearing phenotype of rheumatoid arthritis (RA) synovial fibroblasts.

METHODS

We performed p53 gene mutation analysis using different molecular approaches. Synovial fibroblasts of 10 patients with RA were cultured and RNA and DNA were harvested after 3-5 passages in cell culture. Sequence analysis of all exons of the p53 gene was performed using 3 different techniques: 1) single-strand conformational polymorphism, 2) nonisotopic RNase cleavage assay, and 3) base excision sequence scanning T-scan, followed by sequence analysis of specific gene segments.

RESULTS

Although p53 antigen could be detected by immunocytochemistry in numerous cultured fibroblasts, gel electrophoresis analysis of products obtained using all 3 methods and subsequent sequence analysis showed no specific mutation pattern in the genome of the synovial fibroblasts from patients in Germany, including the known "hot spots" within the p53 genome. However, p53 mutations were identified in different clones of 3 additional RA synovial fibroblast populations from the United States. Sequence analysis of the p53 promoter did not reveal mutational base changes.

CONCLUSION

The findings of the study support the hypothesis that the majority of the mutations of the p53 gene observed in RA synovium are not derived from the genome of RA synovial fibroblasts, and that the variability of the mutation pattern reflects, in part, the heterogeneity of the disease.