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C/EBPα‐dependent preneoplastic tumor foci are the origin of hepatocellular carcinoma and aggressive pediatric liver cancer
Author(s) -
Cast Ashley,
Valanejad Leila,
Wright Mary,
Nguyen Phuong,
Gupta Anita,
Zhu Liqin,
Shin Soona,
Timchenko Nikolai
Publication year - 2018
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.29677
Subject(s) - hepatoblastoma , cancer stem cell , liver cancer , cancer research , stem cell , hepatocellular carcinoma , biology , cancer cell , cancer , pathology , medicine , microbiology and biotechnology , genetics
Recent publications show that classic hepatoblastoma (HBL) is the result of failure of hepatic stem cells to differentiate into hepatocytes, while hepatocellular carcinoma (HCC) is caused by the dedifferentiation of hepatocytes into cancer stem cells. However, the mechanisms of aggressive HBL and the mechanisms that cause dedifferentiation of hepatocytes into cancer stem cells are unknown. We found that, similar to HCC but opposite to classic HBL, aggressive HBL is the result of dedifferentiation of hepatocytes into cancer stem cells. In both cases of liver cancer, the dephosphorylation of tumor suppressor protein CCAAT/enhancer binding protein α (C/EBPα) at Ser193 (Ser190 in human protein) or mutation of Ser193 to Ala results in a modified protein with oncogenic activities. We have investigated liver cancer in a mouse model C/EBPα‐S193A, in a large cohort of human HBL samples, and in Pten/p53 double knockout mice and found that these cancers are characterized by elevation of C/EBPα that is dephosphorylated at Ser190/193. We found that dephosphorylated C/EBPα creates preneoplastic foci with cancer stem cells that give rise to HCC and aggressive HBL. C/EBPα‐dependent dedifferentiation of hepatocytes into cancer stem cells includes increased proliferation of hepatocytes, followed by generation of multinucleated hepatocytes and subsequent appearance of hepatocytes with delta‐like 1 homolog–positive intranuclear inclusions. We further isolated C/EBPα‐dependent multinucleated hepatocytes and found that they possess characteristics of tumor‐initiating cells, including elevation of stem cell markers. C/EBPα‐dependent cancer stem cells are observed in patients with aggressive HBL and in patients with a predisposition for liver cancer. Conclusion: The earliest steps of adult HCC and aggressive pediatric liver cancer have identical features that include conversion of the tumor suppressor C/EBPα into an oncogenic isoform, which further creates preneoplastic foci where hepatocytes dedifferentiate into cancer cells, giving rise to liver cancer. (H epatology 2018;67:1857‐1871).