Yoshiaki Miyauchi

Reduced expression of cell cycle regulator p18INK4C in human hepatocellular carcinoma

Cyclins, cyclin‐dependent kinases (Cdks), and Cdk inhibitors (CdkIs) are frequently altered in human cancer. p18INK4C, a member of the INK4 family of CdkIs, is a potential tumor‐suppressor gene product. However, the expression of p18INK4C in hepatocellular carcinoma (HCC) remains unknown. The aim of this study was to examine the expression of p18INK4C in various liver diseases including HCC and to assess its clinical significance in HCC. To that end, we examined the expression of p18INK4C by immunohistochemistry in various liver diseases, including 51 HCCs, and also studied the relationship between p18INK4C expression, the phosphorylation of retinoblastoma protein (pRb), and the activity level of Cdk4 and Cdk6. Immunohistochemical analysis revealed the frequent loss of p18INK4C expression in HCC, especially in poorly differentiated HCC. The loss of p18INK4C expression was shown to be associated with a poor prognosis compared with that associated with p18INK4C‐ positivity. Further, the kinase activity of Cdk4 was found to be higher in p18INK4C‐negative HCCs than in p18INK4C‐ positive HCCs. However, the level of Cdk6 activity was similar in the 2 groups of HCCs. In p18INK4C‐ positive HCCs, p18INK4C dominantly interacted with Cdk4 rather than with Cdk6. pRb phosphorylated at serine(Ser) 780 was detected more frequently in p18INK4C ‐ negative than in p18INK4C ‐ positive HCCs. In conclusion, the loss of p18INK4C expression may play a role in the differentiation and development of HCC through the up‐regulation of Cdk4 activity. (HEPATOLOGY 2004;40:677–686.)

CD28-negative CD8-positive cytotoxic T lymphocytes mediate hepatocellular damage in hepatitis C virus infection.

The pathogenic mechanism for hepatocellular damage in hepatitis C virus (HCV) infection has not been clearly understood. Analysis of costimulatory molecules on lymphocytes may give us insight into the pathogenic mechanism of hepatocellular damage in HCV infection. Peripheral blood mononuclear cells (PBMCs) and liver infiltrating mononuclear cells (LIMCs) isolated from the HCV-infected patients were analyzed with antibodies directed against a variety of costimulatory molecules by flow cytometry. Blocking experiment against HLA-A24-restricted HCV-specific CTLs and immunohistochemical analysis were also performed. PBMCs expressing CD8, CD28, CD80, or CD154 were significantly reduced in HCV-infected patients compared with the healthy controls. CD28(+)CD8(+) PBMCs in the patients inversely correlated with ALT levels. Conversely, levels of CD28(−)CD8(+) LIMCs correlated with ALT levels. HCV-specific CTL activity was blocked by the treatment with anti-CD8 antibody, but not with anti-CD4 or anti-CD28 antibody. Immunohistochemical analysis revealed the accumulation of CD28(+) cells around the portal area in the liver of a patient with chronic active hepatitis C. These results suggest that CD28(+)CD8(+) T cells leave the circulation, move to the livers, and are activated in the portal area in proportion to the extent of liver diseases. CD28(−)CD8(+) T cells may finally function as effector T cells causing the hepatocellular damage in HCV infection.

Coexistence of splenic non-Hodgkin's lymphoma with hepatocellular carcinoma in a patient with chronic hepatitis C.

Chronic hepatitis C virus (HCV) infection is believed to play important roles in hepatocarcinogenesis (1), although there is no apparent evidence that HCV has direct oncogenic effects on hepatocytes. On the other hand, HCV involves many kinds of extrahepatic manifestations, including mixed cryoglobulinemia, Sjögren syndrome, interstitial pneumoniae, and chronic thyroiditis (2). Recently, strong association of HCV with non-Hodgkin’s lymphoma (NHL) has been reported (3–9). Therefore, it has been suggested that chronic HCV infection may also contribute to the development of NHL. We report the case of a HCVinfected patient with coexistent splenic NHL with hepatocellular carcinoma (HCC). Fine needle splenic biopsy under the guidance of ultrasound imaging was a useful procedure for the diagnosis of the splenic lesion in the present case.

Antibodies of p53 as early markers of hepatoceller carcinoma.

今回われわれは各種肝疾患135例について血清中の抗p53抗体 (p53抗体と略す) を測定した. 用いた標的p53抗原は, p53AKBR, p53のアミノ酸37～52を含むリコンビナントペプタイドである. p53抗体は肝細胞癌 (HCC) 患者102例中37.3%に陽性であった. 対照例では, 肝硬変症 (LC) 18例中1例 (5.6%), 自己免疫性肝炎 (AIH) 15例中1例 (6.7%) に弱陽性で, 健常人35例は全例陰性であった. p53抗体の腫瘍径別陽性率は, 単発性HCCで, 径3cm未満が径3cm以上に比し有意に高かった (p<0.05). 起因ウイルス別陽性率は, HCV感染例がHBV感染例に比し高かった. p53抗体は, α-fetoprotein (AFP) との相関は無く, AFP陰性HCCにおいても39.3%に陽性であった. p53抗体はHCCの診断, 特に早期のHCCにおいて有効であった.