Chronic alcohol intake synergistically increases the incidence of hepatocellular carcinoma (HCC) in hepatitis C patients, however, the underlying mechanisms remain poorly understood. A critical event in HCC is the deregulated expansion of tumor initiating cells (TICs), which are stem-like cells that promote treatment resistant HCC. The p53 tumor suppressor acts as a barrier against stem cell proliferation, and inactivation of p53 or its stabilizing partner NUMB leads to expansion of TICs. However, little is known about the control of the NUMB-p53 interaction and the mechanistic basis for p53 inactivation in TICs from HCC induced by alcohol and HCV. Ectopic induction of TLR4 in hepatocytes in HCV NsSa transgenic (Tg) mice generates TICs and liver tumors when the mice are chronically given alcohol. We demonstrated that stemness and tumor-initiating properties of TICs are dependent on TLR4-NANOG pathway and diminished levels of p53. The NUMB-p53 complex disintegrates upon NANOG-mediated activation of aPKCzeta, a NUMB kinase, leading to MDM2 ubiquitin ligase-dependent proteolysis of p53. Using affinity purification and tandem mass spectrometry, we have identified TBC1D15 as a NUMB-associated oncoprotein that can also disengage p53 from its protective association with NUMB, causing p53 degradation and deregulated TIC propagation. The expression of TBC1D15 is induced by the TLR4-NAN0G pathway and elevated in HCC in alcoholic HCV patients. We hypothesize TLR4-NAN0G-medlated NUMB phosphorylation and TBC1D15 upregulation coordinately trigger p53 degradation to promote self-renewal of TICs in liver oncogenesis caused by HCV and alcohol. To test this hypothesis, we will investigate whether: 1) NANOG-mediated induction of upstream AurA kinase and inhibition of the aPKC inhibitor LGL are responsible for activation of aPKCzeta and p53 degradation in TICs;2) the newly disclosed aPKCzeta-NUMB and TBC1D15 pathways are mutually required for p53 degradation;3) these pathways are evident and required for self-renewal of TICs isolated from HCC of alcoholic HCV patients;and 4) hepatocyte-specific expression of a non-phosphorylatable mutant of NUMB or hepatocyte-specific ablation of TbcldlS suppresses tumorigenesis in alcohol-fed HCV NsSaTg mice.
Increased liver cancer incidence by a combination of alcoholism and hepatitis C virus (HCV) is a major medical problem worldwide. Our proposed research will lead to a better understanding of the mechanism undedying this interaction and will help develop new treatments for liver cancer in alcoholic HCV patients.
|Lazaro, Raul; Wu, Raymond; Lee, Sunyoung et al. (2015) Osteopontin deficiency does not prevent but promotes alcoholic neutrophilic hepatitis in mice. Hepatology 61:129-40|
|Peng, Yue; French, Barbara A; Tillman, Brittany et al. (2014) The inflammasome in alcoholic hepatitis: Its relationship with Mallory-Denk body formation. Exp Mol Pathol 97:305-13|
|Ooi, Ee Lyn; Chan, Stephanie T; Cho, Noell E et al. (2014) Novel antiviral host factor, TNK1, regulates IFN signaling through serine phosphorylation of STAT1. Proc Natl Acad Sci U S A 111:1909-14|
|Win, S; Than, T A; Fernandez-Checa, J C et al. (2014) JNK interaction with Sab mediates ER stress induced inhibition of mitochondrial respiration and cell death. Cell Death Dis 5:e989|
|Kong, Ming; Zhu, Longdong; Bai, Li et al. (2014) Vitamin D deficiency promotes nonalcoholic steatohepatitis through impaired enterohepatic circulation in animal model. Am J Physiol Gastrointest Liver Physiol 307:G883-93|
|Ji, Cheng (2014) New Insights into the Pathogenesis of Alcohol-Induced ER Stress and Liver Diseases. Int J Hepatol 2014:513787|
|Lua, Ingrid; James, David; Wang, Jiaohong et al. (2014) Mesodermal mesenchymal cells give rise to myofibroblasts, but not epithelial cells, in mouse liver injury. Hepatology 60:311-22|
|Schnabl, Bernd; Brenner, David A (2014) Interactions between the intestinal microbiome and liver diseases. Gastroenterology 146:1513-24|
|McArdle, Patrick F; Kittner, Steven J; Ay, Hakan et al. (2014) Agreement between TOAST and CCS ischemic stroke classification: the NINDS SiGN study. Neurology 83:1653-60|
|Shen, Hong; French, Barbara A; Liu, Hui et al. (2014) Increased activity of the complement system in the liver of patients with alcoholic hepatitis. Exp Mol Pathol 97:338-44|
Showing the most recent 10 out of 273 publications