17/06/2019
Hepatocellular Carcinomas With Mutational
Activation of Beta Catenin Require Choline and can
be Detected by Positron Emission Tomography
Angélique Gougelet, Chiara Sartor, Nadia Senni, Julien Calderaro, Laetitia Fartoux, Marie Lequoy, Dominique Wendum, Jean-Noël Talbot, Aurélie Prignon, Julia Chalaye, Sandrine Imbeaud, Jessica Zucman-Rossi, Thierry Tordjmann, Cécile Godard, Pascale Bossard, Olivier Rosmorduc, Giuliana Amaddeo, Sabine Colnot.
Abstract
Background & Aims
In one third of hepatocellular carcinomas (HCCs), cancer cells have mutations that activate beta catenin pathway. These cells have alterations in glutamine, bile, and lipid metabolism. We investigated whether positron emission tomography (PET) imaging allows identification of altered metabolic pathways that might be targeted therapeutically.
Methods
We studied mice with activation of beta catenin in liver (Apcko-liv mice) and male C57Bl/6 mice given injections of diethylnitrosamine, which each develop HCCs. Mice were fed a conventional or a methionine- and choline-deficient (MCD) diet or a choline-deficient (CD) diet. Choline uptake and metabolism in HCCs were analyzed by micro-PET imaging of mice; livers were collected and analyzed by histologic, metabolomic, mRNA quantification, and RNA-seq analyses. Fifty-two patients with HCC underwent PET imaging with 18F-fluorodeoxyglucose (FDG) followed by 18F-fluorocholine (FHC) tracer metabolites. Human HCC specimens were analyzed by immunohistochemistry, quantitative PCR, and DNA sequencing. We used hepatocytes and mouse tumor explants for studies of incorporation of radiolabeled choline into phospholipids and its contribution to DNA methylation. We analyzed HCC progression in mice fed a CD diet.
Results
Livers and tumors from Apcko-liv mice had increased uptake of dietary choline, which contributes to phospholipid formation and DNA methylation in hepatocytes. In patients and in mice, HCCs with activated beta catenin were positive in FCH-PET but not FDG-PET, and they overexpressed the choline transporter organic cation transporter 3. The HCC cells from Apcko-liv mice incorporated radiolabeled methyl groups of choline into phospholipids and DNA. In Apcko-liv mice, the MCD diet reduced proliferation and DNA hypermethylation of hepatocytes and HCC cells, and the CD diet reduced long-term progression of tumors.
Conclusions
In mice and humans, HCCs with mutations that activate beta catenin are characterized by increased uptake of a fluorocholine tracer (FCH), but not FDG, revealed by PET. The increased uptake of choline by HCCs promotes phospholipid formation, DNA hypermethylation, and hepatocyte proliferation. In mice, the CD diet reverses these effects and promotes regression of HCCs that overexpress beta catenin.
Key Words
liver cancerOCT3CTNNB1Wnt pathway