The role of Hepatitis C Virus in hepatocarcinogenesis

Transcription

1 The role of Hepatitis C Virus in hepatocarcinogenesis Laura Beretta Fred Hutchinson Cancer Research Center l8 Incidence and mortality of the five most common cancers worldwide, 2000 Incidence Lung Breast Colon Stomach Liver Mortality Lung Stomach Liver 1

2 Slide 2 l8 600,000 new cases per year lberetta, 3/31/2008

3 Variations in the mortality rates of HCC (the rates are reported per 100,000 persons) El-Serag and Rudolph, Gastroenterology 2007 Risk Factors for HCC Worldwide, by area, 2000 l1 20% 15% 20% 50-60% 60-70% 70% 70% 10-20% Hepatitis B Virus Hepatitis C Virus Persistent HBV or HCV infection account for over 80% of HCC cases 2

4 Slide 4 l1 the causative agents of HCC are quite well established. lberetta, 3/28/2008

5 Trends in US Cancer Mortality Rates Liver cancer has the fastest growing death rate in the US El-Serag and Rudolph, Gastroenterology 2007 Trends in the age distribution of HCC in the US El-Serag and Rudolph, Gastroenterology

6 Hepatitis C Virus-associated Hepatocellular Carcinoma Effective population of HCV Adjusted incidence rate per 100,000 Japan USA Estimated Incidence of Acute HCV Infection United States, New Infections/100, Anti-HCV test (1 st generation) licensed Decline in transfusion recipients Decline in injection drug users Year Source: Hepatology 2000;31:777-82; Hepatology 1997;26:62S-65S; CDC, unpublished data 4

7 Hepatitis C estimated prevalence WHO Region Total Population (Millions) Hepatitis C prevalence Rate % Infected Population (Millions) Africa Americas Eastern Mediterranean Europe South-East Asia Western Pacific Total

8 l3 The connection between virus and cancer l5 Natural History of HCV Infection 3%-8% / year HCV chronic infection Noncirrhotic HCV individuals: <0.1%/year Cirrhotic patients: 3%-8%/year 6

9 Slide 11 l3 it remains a challenge to provide a clear and consistent pictire of the connection between virus and cancer whether the virus plays a direct or indirect role lberetta, 3/30/2008 Slide 12 l5 regional difference lberetta, 3/31/2008

10 Association with co-factors Environmental or genetic background underlying the incidence of HCC development reported in Japanese and Western HCV cohorts Excessive alcohol consumption HBV co-infection Overweight, Diabetes, Insulin resistance Hepatic steatosis which involves an accumulation of intracytoplasmic lipid droplets l4 Indirect involvement of the virus in HCC Chronic hepatic inflammation and cirrhosis are thought to play an important role in tumor initiation : necrosis and regeneration enhance mutagenesis in host cells, the accumulation of which culminates in HCC. 7

11 Slide 14 l4 extremely rare occurence of HCC in patients with autoimmune hepatitis in whom severe inflammation in the liver persists indefinitely absence of a complete set of genetic and epigenetic aberrations required for carcinogenesis. HCV induces genome instability lberetta, 3/31/2008

12 l6 Hepatitis C Virus Enveloped, single-stranded, positive-sense RNA virus l2 Mice with transgenic expression of viral proteins (summary of 18 models) Core protein: Development of steatosis and HCC later in life Inhibition of microsomal triglyceride transfer protein activity which is essential for hepatic lipoprotein assembly and secretion Increase the concentration of monosaturated fatty acids Activation of RXR-alpha and PPAR-alpha Induction of Insulin resistance Synergy of HCV core and alcohol in inducing oxidative stress Structural proteins Core-E1-E2: Similar results E1-E2, E2, NS3-NS4A or NS5A: No major histological changes to the liver Moriya et al J Gen Virol 1997; Moriya et al Nat Med 1998; Moriya et al Cancer Res 2001; Perlemuter et al FASEB J 2002; Lerat et al Gastroenterology 2002; Tsutsumi et al Hepatology 2002; Shintani et al Gastroenterology

13 Slide 15 l2 l6 its genome consists of one large open reading frame that is initially translated into one single polyprotein and subsequently cleaved into the functional protein. lberetta, 3/28/ transgenic mouse line lberetta, 3/31/2008

14 l7 Relevance - Recent reports on HCV patients Chronic hepatitis C can result in fatty changes in the liver and hepatic steatosis is associated with increased frequency of HCC. Correlation between HCV infection and insulin resistance Involvement of the liver microsomal triglyceride transfer protein in HCV induced liver steatosis Increased core genetic variability in tumors compared to adjacent cirrhotic liver, supporting the importance of core genetic variability in hepatocellular carcinogenesis. HCV core variants isolated from liver tumor but not from adjacent non-tumor tissue interact with Smad3 and inhibit the TGF-beta pathway. Mirandola et al Gastroenterology 2006, Sobesky et al Hepatology 2007, Pavio et al Oncogene 2005 These studies strongly support a direct role for core protein in liver pathogenesis. Core may predispose subjects to HCC development through its contribution to the onset of steatosis and insulin resistance. 9

15 Slide 17 l7 l9 even if we consider the variability of morphopgical observations and the diversoity of biochemical data lberetta, 3/31/2008 these data are particularly relevant considering recent reports on HCV patients lberetta, 3/31/2008

16 Recent development of cell culture models of HCV infection and replication Protein changes upon HCV replication Petra Mannova Romain Parent Sufen Shang Neha Lohia 10

17 HCV Infection of Huh7.5 cells P1 P3 P5 P12 P19 P27 Transcriptomic Proteomic Fold Change : P1 P3 P5 P12 P19 P27 P1 P3 P5 P12 P19 P27 Activation of RXRA and PPARA 11

18 Activation of the PI3K/Akt/mTOR pathway Activation of PI3K Activation of mtor Mannova et al J Virol 2005 Mannova et al MCP 2006 N-Ras/PI3K/Akt/mTOR pathway and HCV replication Increased N-Ras levels in sub-cellular sites of HCV replication and stimulation of the PI3K-Akt-mTOR pathway by HCV contribute to the maintenance of steady-state levels of HCV replication. 12

19 PI3K/Akt Oncogenic pathway frequently activated in HCV-associated HCC Normal liver PTEN Tumor mtor S6 kinase Sahin et al Clin Cancer Res 2004 The PI3K/Akt/mTOR pathway and liver progenitor cells Liver progenitor cells may be important in carcinogenesis resulting from chronic liver diseases. These cells may function as tumor progenitors. Romain Parent 13

20 The human bipotent liver progenitor HepaRG cell line Established from the peritumoral region of an HCV-induced Edmondson grade I HCC Share several markers with the regenerative neoductules of the same area studied by IHC Share some features with liver progenitor cells HES CK19 HES CK18 M2-PK OV1 Parent et al Gastroenterology 2004 Progressively acquire a polarized hepatocytic phenotype Day 2 Day 15 B H B Day 4 Day 42 H B H 14

21 Cell cycle A Cell death Translational control plays a prominent role in the hepatocytic differentiation of HepaRG liver progenitor cells Innate Immunity B C D Lipid metabolism + Drug metabolism E F G Cell morphology Cell environment and Cell movement Parent and Beretta Genome Biology 2008 H I J Over-expression of an activated mtor mutant (ΔTOR) lacking the R (repressor) domain 15

22 Impaired hepatocytic differentiation in ΔTOR-expressing HepaRG cells Parent et al Cancer Res 2007 Reversion by rapamycin of the altered phenotype Parent et al Cancer Res

23 Loss of responsiveness to TGF-β in ΔTOR-expressing HepaRG cells Cell cycle Activated mtor specifically targets: A Cell death Innate Immunity Cell death-related network: TNF superfamily members, interferons and caspases B C D Lipid metabolism + Drug metabolism Lipid homeostasis-related network PPARA, PPARD, RXRA and RXRB E F G Cell morphology Cell environment and Cell movement H I J Parent et al Cancer Res 2007 Parent and Beretta Genome Biology

24 Nude mice transplanted with Δ TOR cells expressing Firefly Luciferase week 2 Liver specific PTEN knock-out results in HCC in mice Derek Masse Garrett Booth Horie et al J Clin Invest

25 Collection of liver tissue at 3-months intervals Wild type 6 months PTEN mutant 6 months 9 months A B C D E F Hepatomegaly and liver steatosis A Liver weight (g) Control Experimental p < p < p < B Liver weight (g) months 6 months 9 months 0 596C 597C 655C 660C 680C 595E 620E 622E 627E 636E 1054E 594C 683C 584C 962C 581E 643E 652E 650E 585E 590E 964E 982E 984E 1017E 1018E 1019E 1020E 1023E 342C 461C 486C 855C 864C 902C 341E 375E 458E 467E 480E 482E 688E 827E 828E 833E 858E 903E 907E 912E Controls PTEN -/- Controls PTEN -/- Controls PTEN -/- 3 months 6 months 9 months A Oil Red 0 Staining (pixels) months 6 months 9 months B Oil Red 0 Staining (pixels) E 620E 622E 627E 636E 1054E 581E 585E 590E 643E 650E 652E 964E 982E 984E 1017E 1018E 1019E 1020E 1023E 341E 375E 458E 467E 480E 482E 688E 827E 828E 833E 858E 903E 907E 912E 3 months 6 months 9 months 19

26 US/Histology Show Early HCC at 9 months All mice develop tumors by 12 months l10 Natural History of HCV Infection 3%-8% / year Cellular metabolic disturbances 20

27 Slide 40 l10 an increasing body of evidence suggest a direct involvement in cellular metabolic disturbance lberetta, 4/1/2008