Abstract 909: Activation of NF-κB and its downstream targets play a key role in the dramatic induction of hepatocarcinogenesis in metallothionein null mice

Abstract

Abstract Hepatocellular Carcinoma (HCC) is one of the most prevalent cancers in the world and the third leading cause of cancer-related death. Although hepatitis C and fatty liver disease appear to be the main risk factors in most western countries other factors including alcohol, tobacco, diabetes, and other metabolic disorders can also increase the likelihood of HCC development. HCC is believed to develop through a tumor promoting mechanism involving inflammation and oxidative stress. We have previously shown that metallothionein (MT), a ubiquitously expressed free radical scavenger, is dramatically downregulated in human and rodent HCCs. To test the hypothesis that MT protects the liver from carcinogenesis by relieving oxidative stress, MT knockout (MTKO) mice were injected with Diethylnitrosamine (DEN), a potent liver carcinogen. When compared to wild-type DEN treated mice, the MTKO groups exhibited significantly higher (5-fold) incidence and an accelerated rate of hepatocarcinogenesis. Gene expression analysis at the preneoplastic stage revealed a dramatic increase in the levels of Serpine-1 in the MTKO mice, which was validated by real-time PCR. Serpine-1, a tissue glycoprotein and an active suppressor of fibrinolysis through the inhibition of tissue plasminogen activator and urokinase plasminogen activator, is also believed to increase cell migration and angiogenesis. Real-time PCR analysis of the pro-inflammatory cytokines known to induce Serpine-1 revealed substantial upregulation of TNF-α, IL-6, and IL-1β in the MTKO/DEN mice compared to the WT/DEN and untreated controls. Electrophoretic mobility shift assay confirmed differential activation of NF-κB, a downstream effector of pro-inflammatory cytokines and inducer of Serpine-1 expression, in the MTKO/DEN mice at the preneoplastic stage. These data demonstrate that Serpine-1 and NF- κB act in concert at the early stages of hepatocarcinogenesis when free radical scavenging is compromised. These data show the protective role of MT against HCC induction in a mouse model and provide the rationale for an alternate therapeutic strategy in HCC therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 909. doi:10.1158/1538-7445.AM2011-909