Expression of the retinoblastoma gene product in human hepatocellular carcinoma

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.

Molecular-based prediction of early recurrence in hepatocellular carcinoma

BACKGROUND/AIMS

Hepatocellular carcinoma (HCC) has a very poor prognosis, due to the high incidence of tumor recurrence. As the current morphological indicators are often insufficient for therapeutic decisions, we sought to identify additional biologic indicators for early recurrence.

METHODS

We analyzed gene expression using a PCR-based array of 3,072 genes in 100 HCC patients. Informative genes predicting early intrahepatic recurrence were selected by random permutation testing, and a weighted voting prediction method was constructed. Following estimation of prediction accuracy, a multivariate Cox analysis was performed.

RESULTS

By permutation testing, we selected 92 genes demonstrated distinct expression patterns differing significantly between recurrence cases and recurrence-free cases. Our prediction method, using the 20 top-ranked genes, correctly predicted the early intrahepatic recurrence for 29 of 40 cases within the validation group, and the odds ratio was 6.8 (95%CI 1.7-27.5, P = 0.010). The 2-year recurrence rates in the patients with the good signature and those with the poor signature were 29.4 and 73.9%, respectively. Multivariate Cox analysis revealed that molecular-signature was an independent indicator for recurrence (hazard ratio 3.82, 95%CI 1.44-10.10, P = 0.007).

CONCLUSIONS

Our molecular-based prediction method using 20 genes is clinically useful to predict early recurrence of HCC.

Immunohistochemical investigation of new suppressor oncogene p130 in oral squamous cell carcinoma

New onco-suppressor gene p130 is one of the Rb family forms and is reported to undergo allelic loss in hepatocellular, prostate, and breast carcinomas; however, no report of p130 has been made in oral tumors. The present study dealt with the expression of p130 and Rb proteins by immunohistochemical staining in oral squamous cell carcinomas (n = 110) and oral mucosa. The site of the carcinomas included tongue (n = 48), gingiva (n = 32), oral floor of the mouth (n = 15), oropharynx (n = 6), buccal mucosa (n = 5), and others (n = 4). Histologically there were 65 well-differentiated carcinomas, 33 moderately differentiated carcinomas, and 12 poorly differentiated ones. Positive staining for p130 and Rb was localized to suprabasal cell layers of the normal oral epithelium. In the oral squamous cell carcinoma, positive staining for p130 and Rb was observed in well-differentiated carcinomas (p130, 66.2%; Rb, 78.5%), more than in poorly differentiated ones (p130, 16.7%; Rb, 50.0%). In immunoelectron microscopic features, p130 protein was localized in the nucleus and mitochondria. The expression of p130 was related to the degree of tumor differentiation as that of Rb. It is suggested that p130 gene may be associated with the development of a wide variety of human malignancies rather than the progression.

Retinoblastoma (RB1) gene product expression in breast carcinoma. Correlation with Ki-67 growth fraction and biopathological profile

AIMS

To investigate the expression of retinoblastoma protein (pRb) in invasive breast tumours and compare its expression with the major biopathological prognostic indicators to identify more aggressive subgroups.

MATERIAL

Archival paraffin embedded tissues from 153 consecutive primary breast carcinomas.

METHODS

pRb, Ki-67, and oestrogen receptor/progesterone receptor proteins were identified by immunohistochemistry and score values were recorded by image cytometric analysis; p53 and EGFr expression was also evaluated.

RESULTS

pRb scores correlated strongly with proliferation activity as determined by Ki-67 staining. Positive relations were also observed between pRb scores, tumour size, nuclear and histological grade, and oestrogen receptor/progesterone receptor content, while abnormal p53 accumulation was not associated with pRb expression. Among the high proliferating carcinomas it was possible to identify 13 cases with loss of pRb expression.

CONCLUSIONS

pRb expression paralleled proliferative activity in the majority of breast carcinomas examined, suggesting that in these cases the protein behaves normally in regulating the cell cycle. Conversely in cases with loss of pRb immunostaining, the combined expression of specific highly aggressive factors (EGFr and p53 expression, oestrogen receptor/progesterone receptor negative status, and high K67) seems to characterise a more aggressive phenotype showing growth advantage and cellular "progression" rather than significant nodal involvement.

Induction of apoptosis in a human hepatocellular carcinoma cell line by a neutralizing antibody to transforming growth factor-alpha

A cell line derived from a Japanese man with hepatocellular carcinoma was established in culture and designated OCUH-16. The cell line has the morphological and chromosomal features of hepatocellular carcinoma cells and has a short doubling time (approximately 33 h). OCUH-16 cells were shown to express transforming growth factor-alpha (TGF-alpha) in addition to albumin, DNA polymerase-alpha, c-JUN, and the retinoblastoma gene product. Electron microscopy revealed TGF-alpha immunoreactivity associated with the cell membrane, but TGF-alpha was not detected in medium conditioned by OCUH-16 cells by enzyme-linked immunosorbent assay. Reverse transcription and polymerase chain reaction analysis revealed the presence of TGF-alpha messenger RNA in these cells. Culture of OCUH-16 cells in the presence of a neutralizing antibody to TGF-alpha inhibited cell proliferation and induced many cells to undergo apoptosis (programmed cell death). These observations suggest that endogenous TGF-alpha is necessary for OCUH-16 cell growth.