p53 expression in hepatocellular carcinoma in a population in Singapore with endemic hepatitis B virus infection

Hepatic progenitor cells in liver cancers from Asian children

BACKGROUND/AIMS

Hepatoblastoma (HB) and hepatocellular carcinoma (HCC) are the two most common primary malignant liver tumours in children. Hepatic progenitor cells have been described and can be stained with K19, EpCAM and CD117. We investigated the morphology and staining patterns of primary liver tumours in Asian children.

METHODS

Four pathologists studied slides from 39 paediatric patients from Vietnam and Korea aged 8 months to 16 years. We performed immunohistochemical stains for K19, EpCAM and CD117, and polymerase chain reaction for tissue hepatitis B virus (HBV) DNA and hepatitis C virus (HCV) RNA.

RESULTS

There was agreement on the diagnosis of 24 cases of HCC and 10 cases of HB (one recurrent case). The diagnosis was split for six cases (HCC/HB). All 20 cases of HCC tested were HBV DNA+ and HCV RNA-. All nine cases of HB tested were HBV DNA-, while one was HCV RNA+. Of four HCC/HB cases tested, three were HBV DNA+ and all were HCV RNA-. By immunohistochemistry, 8/24 (33%) cases of HCC were K19+ and 18/24 (75%) were EpCAM+, 5/10 (50%) cases of HB were K19+ and 7/10 (70%) were EpCAM+ and 3/6 (50%) cases of HCC/HB were K19+ and 5/6 (83%) were EpCAM+. CD117 was negative in all 38 cases tested. Paediatric HCC has a morphology different from adult HCC, sometimes resembling HB, and a larger proportion of paediatric tumours have progenitor cell features.

CONCLUSIONS

HB and HCC in children may represent malignant transformation at an early stage in the cellular lineage and often arise from hepatic progenitor cells.

Predictive value of p53 and pRb expression in superficial bladder cancer patients treated with BCG and interferon-alpha

BACKGROUND

Nuclear p53 and retinoblastoma protein (pRb) were reported to be poor prognostic indicators for transitional cell carcinoma of the bladder. The authors sought to determine the prognostic value of nuclear p53 and pRb in superficial bladder transitional cell carcinoma patients who were treated with intravesical bacille Calmette-Guerin (BCG) or BCG with interferon-alpha (IFN-alpha).

METHODS

A prospective histological review was performed for 80 superficial bladder transitional cell carcinoma patients who underwent postresection intravesical regimes of BCG (81 mg, n = 33 or 27 mg, n = 20) or BCG (27 mg) with IFN-alpha (n = 27), and followed for a mean of 4.5 years. Hematoxylin and eosin (H & E) and immunoperoxidase staining were performed on tissue sections. Nuclear p53 and pRb immunoreactivity were assessed semiquantitatively, by using a combination of staining extent and intensity, to categorize overexpression or underexpression. Data were analyzed by using chi-square analysis, multiple logistic regression, and Kaplan-Meier curves.

RESULTS

pRb expression was not associated with patient outcome after BCG-alone therapy, but pRb underexpression was significantly associated with BCG nonresponse and tumor recurrence (P = .047) after BCG and IFN-alpha (BCG + IFN-alpha) therapy. Low-grade tumors were associated with pRb overexpression, with or without nuclear p53 underexpression (P = .019; P = .043, respectively). p53 expression alone or in combination with pRb expression had no significant relation with tumor response to BCG alone or BCG + IFN-alpha with respect to recurrence, progression, or cancer-specific death.

CONCLUSIONS

Nuclear pRb underexpression may be predictive of nonresponse and cancer recurrence after intravesical BCG + IFN-alpha therapy. Nuclear p53 expression or its combination with pRb expression is not associated with post-BCG clinical outcome, so p53 expression or p53 with pRb expression should not be used to influence decisions concerning BCG-alone or BCG + IFN-alpha therapy.

Detecção imunoistoquímica das oncoproteínas p21ras, c-myc E p53 no carcinoma hepatocelular e no tecido hepático não-neoplásico

RACIONAL: A hepatocarcinogênese é um processo no qual as alterações genéticas e epigenéticas são bem conhecidas em modelos animais, mas carece de estudos no homem. OBJETIVOS: Analisar a freqüência das oncoproteínas p21ras, c-myc e p53 no carcinoma hepatocelular e no fígado não-neoplásico. Verificar ainda a associação destas oncoproteínas com os padrões e graus histológicos, assim como com as infecções pelos vírus das hepatites B e C. MÉTODOS: Foi analisada por método imunoistoquímico a detecção das oncoproteínas p21ras, c-myc e p53 em 47 casos de carcinoma hepatocelular e no tecido não-neoplásico circunjacente ao tumor (40 casos). RESULTADOS: As oncoproteínas p21ras, c-myc e p53 foram detectadas, respectivamente, em 44,7%, 53,2% e 36,2% dos casos de carcinoma hepatocelular. A imunorreatividade do p21ras e c-myc mostrou uma associação significativa. Contudo, não houve associação significativa entre a detecção do p21ras, c-myc e p53 com os diferentes graus e padrões histológicos, nem tampouco com as infecções pelos vírus das hepatites B e C. A mesma associação significativa entre o p21ras e c-myc foi encontrada no tecido não-neoplásico dos casos de cirrose em relação aos que não apresentaram cirrose, enquanto que o p53 foi negativo em todos os casos. CONCLUSÕES: A imunorreatividade das oncoproteínas p21ras, c-myc e p53 corrobora evidências prévias de sua detecção no carcinoma hepatocelular, o que sugere poder haver participação destas proteínas na hepatocarcinogênese humana. A significativa associação entre as proteínas p21ras, c-myc e p53 no carcinoma hepatocelular e na cirrose pode apontar uma interação entre as mesmas, sobretudo na hepatocarcinogênese pela via da cirrose.

Is p53 gene mutation an indicatior of the biological behaviors of recurrence of hepatocellular carcinoma?

AIM: To evaluate mutant p53 gene in primary hepatocellular carcinoma and to investigate the correlation between it and the recurrence of hepatocellular carcinoma.

METHODS: Mutations of p53 gene were examined using anti-human p53 monoclonal antibody and immunohistochemical staining in 79 resected hepatocellular carcinomas. The correlations among variables of p53 positivity and invasiveness, disease free interval and survival were studied. In addition, in those who developed recurrence, the correlation among p53 positivity, clinical features and post-recurrence survival were also studied.

RESULTS: Of these 79 cases, 64 (81%) had p53 mutation. Those patients with mutant p53 positivity had significantly more tumor recurrence (76.6% vs 40.0%, P = 0.0107). However, the COX proportional hazards model showed that p53 overexpression had only weak correlations with recurrence free interval and survival time (P = 0.088 and 0.081), which was probably related to the short duration of follow-up. The invasiveness variables may be predictors of HCC recurrence. On univariate analysis, more patients with mutant p53 positivity had vascular permeation [78.1 vs 40.0%, P = 0.0088, O.R. (odds ratio) = 5.3], grade II-IV differentiation (98.4 vs 80.0%, P = 0.0203, O.R. = 15.7), no complete capsule (82.8 vs 53.3%, P = 0.0346, O.R. = 4.2) and daughter nodules (60.9 vs. 33.3%, P = 0.0527, O.R. = 3.1) than patients with negative p53 staining. On multivariate analysis, only vascular permeation and grade of differentiation remained significant (P = 0.042 and 0.012). There was no statistically significant correlation between the status of p53 in the primary lesion and the clinical features of recurrent hepatocellular carcinomas examined, including extrahepatic metastasis (P = 0.1103) and the number of recurrent tumors (P = 1.000) except for disease over more than one segment in the extent of recurrent tumors (P = 0.0043). The post-recurrence median survival was lower in patients in whom p53 mutation had been detected in the primary lesion with a weak significance (3.42 mo vs 11.0 mo, P = 0.051).

CONCLUSION: Our findings suggest that p53 mutation correlates significantly with invasiveness including vascular permeation, grade of cellular differentiation, incomplete capsule and multinodular lesions. Hepatocellular carcinomas with p53 mutations had more tumor recurrence and p53 mutation may also influence disease recurrence interval and survival time. Hepatocellular carcinomas with p53 mutations recur more extensively with a shorter survival. Therefore, p53 mutation in the primary lesion is useful as an indicator of the biological behavior of recurrent hepatocellular carcinomas.

p53 protein expression in patients with hepatocellular carcinoma from the high incidence area of Guangxi, Southern China

Mutation of the p53 gene has been reported in hepatocellular carcinoma (HCC) occurring worldwide. The most frequent p53 mutation has been found in HCCs in regions with high hepatitis B virus (HBV) infection and intake of aflatoxin B1 (AFB1). The aim of our study was to examine p53 protein expression in HCCs from a high incidence area of Guangxi, Southern China, where HBV infection and dietary intake of AFB1 are high. Immunohistochemical staining of p53 protein was carried out using a polyclonal rabbit antibody (CM-1). Serial sections were also stained for hepatitis B surface antigen and core antigen. p53 Protein expression was detected in 13 (43.3%) of the 30 HCCs. Expression of p53 was found in 25.0% (1/4) of the < or = 5.0 cm diameter HCCs, in 36.8% (7/19) of the 5.1-10.0 cm diameter HCCs and in 71.4% (5/7) of the >10.0 cm diameter HCCs. Expression of p53 was observed more in moderately and poorly differentiated than in the well differentiated HCCs and more frequently seen in HCCs from younger patients. These data indicate that there is a close association between p53 protein expression and tumor size, histological grade and age of patients. Twenty-seven out of 30 cases (90.0%) were positive for HBV. No significant association between p53 expression and sex. HBV infection, cirrhosis or alpha-fetoprotein has been found.

Mutations of the p53 tumor suppressor gene and ras oncogenes in aflatoxin hepatocarcinogenesis

Aflatoxin B1 (AFB1) is classified as a group I carcinogen in humans by IARC. However, the exact mechanisms of AFB1 hepatocarcinogenesis have not been fully elucidated. Recent studies have suggested that oncogenes are critical molecular targets for AFB1, and AFB1 causes characteristic genetic changes in the p53 tumor suppressor gene and ras protooncogenes. Up to date, more than 1500 human hepatocellular carcinoma (HCC) samples have been examined for p53 mutations with respect to different AFB1 exposure levels. The most significant finding is that more than 50% of HCC patients from high aflatoxin exposure areas such as southern Africa and Qidong, China harboured a codon 249 G to T transversion in the p53 tumor suppressor gene, which is found to be consistent with the mutagenic specificity of AFB1 observed in vitro. In contrast, this mutational pattern is not found in HCC samples from moderate or low aflatoxin exposure countries or regions. Therefore, this hot-spot mutation is believed to be a molecular fingerprint linking the initial event of AFB1-DNA adduct formation with the ultimate development and progress of human HCC. However, some important points still remain to be explicated. First, in many of these studies, the systematic evaluation of AFB1 exposure is rather limited and the classification of AFB1 exposure level is speculative and confusing, without the definite evidence for the actual aflatoxin exposure level. Second, the role of hepadnaviral infection has to be considered in the induction of this unique mutational spectrum. On the other hand, ras oncogene mutations are frequently found in AFB1-induced HCC samples in experimental animals, while the frequency of ras mutation in human HCC in contrast is much lower than that of p53. Recent studies have provided additional evidence that reactive oxygen species (ROS) and oxidative DNA damage may be involved in AFB1-induced p53 and ras mutations. In future, follow-up cohorts exposed to different levels of AFB1 combined with the determination of putative gene markers are much needed.