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.

Public Health Relevance

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.

National Institute of Health (NIH)
National Institute on Alcohol Abuse and Alcoholism (NIAAA)
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University of Southern California
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Harrall, Kylie K; Kechris, Katerina J; Tabakoff, Boris et al. (2016) Uncovering the liver's role in immunity through RNA co-expression networks. Mamm Genome 27:469-84
Pham, Hung; Birtolo, Chiara; Chheda, Chintan et al. (2016) Essential Role of Lyn in Fibrosis. Front Physiol 7:387
Birtolo, Chiara; Go, Vay Liang W; Ptasznik, Andrzej et al. (2016) Phosphatidylinositol 3-Kinase: A Link Between Inflammation and Pancreatic Cancer. Pancreas 45:21-31
Page, Agata; Paoli, Pier; Moran Salvador, Eva et al. (2016) Hepatic stellate cell transdifferentiation involves genome-wide remodeling of the DNA methylation landscape. J Hepatol 64:661-73
Puri, Puneet; Xu, Jun; Vihervaara, Terhi et al. (2016) Alcohol produces distinct hepatic lipidome and eicosanoid signature in lean and obese. J Lipid Res 57:1017-28
Wang, Ping; Koyama, Yukinori; Liu, Xiao et al. (2016) Promising Therapy Candidates for Liver Fibrosis. Front Physiol 7:47
Chen, Jian; Yao, Zhi-Xing; Chen, Jiun-Sheng et al. (2016) TGF-β/β2-spectrin/CTCF-regulated tumor suppression in human stem cell disorder Beckwith-Wiedemann syndrome. J Clin Invest 126:527-42
Nuño-Lámbarri, Natalia; Domínguez-Pérez, Mayra; Baulies-Domenech, Anna et al. (2016) Liver Cholesterol Overload Aggravates Obstructive Cholestasis by Inducing Oxidative Stress and Premature Death in Mice. Oxid Med Cell Longev 2016:9895176
Li, Yuchang; Lua, Ingrid; French, Samuel W et al. (2016) Role of TGF-β signaling in differentiation of mesothelial cells to vitamin A-poor hepatic stellate cells in liver fibrosis. Am J Physiol Gastrointest Liver Physiol 310:G262-72
Kweon, Soo-Mi; Chi, Feng; Higashiyama, Reiichi et al. (2016) Wnt Pathway Stabilizes MeCP2 Protein to Repress PPAR-γ in Activation of Hepatic Stellate Cells. PLoS One 11:e0156111

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