Proliferation of liver cells chronic liver disease: a study of liver in biopsies using immunohistochemical localization of prolifrating cell nuclear antigen

A significant proportion of chronic liver disease [CLD], consisting of chronic hepatitis and liver cirrhosis, results from chronic subclinical infection by hepatitis B and C viruses, HBV and HCV[1]. This chronic hepatitis [CH] is a forerunner of liver cirrhosis [LC] and may further progress to hepatocellular carcinoma[2-3]. The association of cirrhosis with hepatocellular carcinoma [HCC] is also well documented[4]. The exact mechanism of viral hepatocarcinogenesis is yet to be clearly defined[5]. Possibly the persistent liver cell necrosis and the resultant irregular regeneration[6]. The proliferative rate of regenerating hepatocytes may be an important pathogenetic and prognostic factor in chronic liver disease[7]. A number of markers have been used in the assessment of the proliferative status of cells, like bromodeoxyuridine[8], Ki-67[9] and DNA polymerase alpha[10]. Techniques utilizing these markers are complex, however, and require fresh or snap frozen tissue, except for Ki-67, which can be used on paraffin sections. Proliferating cell nuclear antigen [PCNA], an accessory protein of DNA polymerase delta, is one of the best markers for evaluating cell proliferation in studies on retrospective material, since the antigen can be localized in routine formalin-fixed paraffin-embedded tissue[7, 11-14]. Limited reports are available on the proliferation kinetics of normal human livers, though in recent years several studies reported on hepatocytic proliferation rates in acute and chronic liver diseases. Normal hepatocytes are generally quiescent and divide very slowly[15-17] High proliferative rates have been reported in hepatocellular carcinoma, cirrhosis and acute hepatic failure[11, 18-22]. Nakamura et al., [7] have shown that there is no significant difference in PCNA-labeling indices between chronic viral hepatitis types B and C. With increasing knowledge of the biology of hepatitis C virus infection, information on hepatocytic proliferation kinetics is emerging now. In a recent study on the prevalence of HBV- and HCV-associated chronic liver diseases in liver biopsy material over the last decade, we observed a steady rise of HCV-associated diseases and a decline in HBV-associated ones[23]. Chronicity of HCV infection leads to CH and LC much more frequently than chronic infection by other hepatitis viruses[24], and the former infection shows a higher degree of association with hepatocellular carcinoma in several parts of the world[25]. Therefore, we considered it worthwhile to examine for hepatocytic proliferation using PCNA-labeling in our material of chronic liver diseases and to note any differences between hepatitis B- and C-associated diseases

Cytokines' profile in fulminant hepatic failure: effect of hepatocyte transplantation

We used a previously described animal model of fulminant hepatic failure [FHF] to study the effect of hepatocyte transplantation [HcTx] on the cytokine profile. Three groups of Sprague Dawley rats were used. Group I [n=30] received intrasplenic HcTx. Group II [n=12] received intrasplenic injection of saline. Two days later, both groups underwent surgically induced FHF. Group III [n=30] underwent sham operation. Six animals of each group were euthanized preoperatively and on postoperative days 1, 7, 14 and 28 to study plasma cytokines; hepatocyte growth factor [HGF] and transforming growth factor beta one [TGF-beta 1]. Preoperatively, and after hepatocyte transplantation, Group I had a higher level of hepatocyte growth factor [HGF] than Groups II and III. On postoperative day 1, Group I had low levels of HGF and TGF-beta 1 and Group lI had the highest levels among the three groups. No animals in Group II survived beyond day 3 postoperatively. On day 14, HGF showed a rise in Group I as compared with Group III. HcTx has modified the level of cytokines in favor of liver regeneration in FHF rats

Up-regulation of the tumor suppressor gene P53 and WAF1 gene by IP6 in HPG2 human hepatocellular carcinoma cell line

Inositol hexaphosphate [InsP6 or IP6] is a naturally occurring polyphosphorylated carbohydrate that is present in substantial amounts in almost all plant and mammalian cells. It was recently recognized to possess multiple biological functions. IP6 exerts its effects on the body by controlling cell division. It reduces the rate of cellular proliferation, both in vivo and in vitro, and has exhibited an ability to reduce DNA synthesis and also causes differentiation of various cell lines, including HT-29 human colon carcinoma cell. We hypothesize that the tumor suppressor genes such as p53 and WAF1 may be involved in mediating the antineoplastic action of IP6. p53 acts as a molecular policeman preventing propagation of genetically damaged cells; it causes the cells to arrest in the G1 phase of cell cycle, and regulates the level of p21 wafl which acts as a growth inhibitor. We therefore investigated the effects of IP6 on the expression of p53 and WAF1/p21 in HP-G2 human hepatocellular carcinoma by immunocytochemistry. Our immunocytochemical studies with anti p53 antibodies [wild type-PAb246 and Pab 1620] and anti p21 wafl [EA10] antibodies demonstrated an increased level of p53 and p21 wafl after 3 and 6 days of treatment with 3.3 and 5 mM and 8 mM IP6. This increase was dose-dependent and a definite time-dependent increase was not observed. These data demonstrate that IP6 up-regulates the expression of the tumor suppressor gene p53 and p21waf1 gene and their modulation may be one of the mechanisms of the antineoplastic action of IP6 since loss of p53 function enhances cancer cells resistance to chemotherapeutic agents, the stimulating function of IP6 on p53 makes it an attractive adjuvant chemotherapeutic agent as well