Sandra Rebouissou1,2,3,4, Andrea Franconi1,2,3,4, Julien Calderaro1,2,3,4,5, Eric Letouzé1,2,3,4, Sandrine Imbeaud1,2,3,4, Camilla Pilati1,2,3,4, Jean-Charles Nault1,2,3,4,6, Gabrielle Couchy1,2,3,4, Alexis Laurent7,8, Charles Balabaud9,10, Paulette Bioulac-Sage9,10,11, Jessica Zucman-Rossi1,2,3,4,12. 1. Inserm, UMR-1162, Functional Genomics of Solid Tumors, Equipe labellisée Ligue Contre le Cancer, Paris, France. 2. University of Paris Descartes, Sorbonne Paris Cité, Labex Immuno-oncology, Paris, France. 3. University of Paris Diderot, Sorbonne Paris Cité, University Institute of Hematology, Paris, France. 4. University of Paris 13, Sorbonne Paris Cité, Saint-Denis, France. 5. Public Hospitals of Paris, Department of Pathology, CHU Henri Mondor, Créteil, France. 6. Public Hospitals of Paris, University hospital of Paris-Seine Saint-Denis, Site Jean Verdier, Cancerology unit, Department of Hepatology, Bondy, France. 7. Public Hospitals of Paris, Department of Digestive and Hepatobiliary Surgery, CHU Henri Mondor, Créteil, France. 8. INSERM U955 Henri Mondor Hospital University of Paris-Est Créteil, France. 9. Inserm, UMR-1053, Bordeaux, France. 10. University of Bordeaux, Bordeaux, France. 11. Hospital of Bordeaux, Pellegrin Hospital, Department of Pathology, Bordeaux, France. 12. Public Hospitals of Paris, European Hospital Georges Pompidou, Paris, France.
Abstract
CTNNB1 mutations activating ß-catenin are frequent somatic events in hepatocellular carcinoma (HCC) and adenoma (HCA), particularly associated with a risk of malignant transformation. We aimed to understand the relationship between CTNNB1 mutation types, tumor phenotype, and level of ß-catenin activation in malignant transformation. To this purpose, CTNNB1 mutation spectrum was analyzed in 220 HCAs, 373 HCCs, and 17 borderline HCA/HCC lesions. ß-catenin activation level was assessed in tumors by quantitative reverse-transcriptase polymerase chain reaction and immunohistochemistry (IHC), in cellulo by TOP-Flash assay. Overall, ß-catenin activity was higher in malignant mutated tumors, compared to adenomas, and this was related to a different spectrum of CTNNB1 mutations in HCCs and HCAs. In benign tumors, we defined three levels of ß-catenin activation related to specific mutations: (1) S45, K335, and N387 mutations led to weak activation; (2) T41 mutations were related to moderate activity; and (3) highly active mutations included exon 3 deletions and amino acid substitutions within the ß-TRCP binding site (D32-S37). Accordingly, in vitro, K335I and N387K mutants showed a lower activity than S33C. Tumors with highly active mutations demonstrated strong/homogeneous glutamine synthase (GS) staining and were associated with malignancy. In contrast, weak mutants demonstrated heterogeneous pattern of GS staining and were more frequent in HCAs except for the S45 mutants identified similarly in 20% of mutated HCAs and HCCs; however, in most of the HCCs, the weak S45 mutant alleles were duplicated, resulting in a final high ß-catenin activity. CONCLUSION: High ß-catenin activity driven by specific CTNNB1 mutations and S45 allele duplication is associated with malignant transformation. Consequently, HCAs with S45 and all high/moderate mutants should be identified with precise IHC criteria or mutation screening. (Hepatology 2016;64:2047-2061).
CTNNB1 mutations activating ß-catenin are frequent somatic events in hepatocellular carcinoma (HCC) and adenoma (HCA), particularly associated with a risk of malignant transformation. We aimed to understand the relationship between CTNNB1 mutation types, tumor phenotype, and level of ß-catenin activation in malignant transformation. To this purpose, CTNNB1 mutation spectrum was analyzed in 220 HCAs, 373 HCCs, and 17 borderline HCA/HCC lesions. ß-catenin activation level was assessed in tumors by quantitative reverse-transcriptase polymerase chain reaction and immunohistochemistry (IHC), in cellulo by TOP-Flash assay. Overall, ß-catenin activity was higher in malignant mutated tumors, compared to adenomas, and this was related to a different spectrum of CTNNB1 mutations in HCCs and HCAs. In benign tumors, we defined three levels of ß-catenin activation related to specific mutations: (1) S45, K335, and N387 mutations led to weak activation; (2) T41 mutations were related to moderate activity; and (3) highly active mutations included exon 3 deletions and amino acid substitutions within the ß-TRCP binding site (D32-S37). Accordingly, in vitro, K335I and N387K mutants showed a lower activity than S33C. Tumors with highly active mutations demonstrated strong/homogeneous glutamine synthase (GS) staining and were associated with malignancy. In contrast, weak mutants demonstrated heterogeneous pattern of GS staining and were more frequent in HCAs except for the S45 mutants identified similarly in 20% of mutated HCAs and HCCs; however, in most of the HCCs, the weak S45 mutant alleles were duplicated, resulting in a final high ß-catenin activity. CONCLUSION: High ß-catenin activity driven by specific CTNNB1 mutations and S45 allele duplication is associated with malignant transformation. Consequently, HCAs with S45 and all high/moderate mutants should be identified with precise IHC criteria or mutation screening. (Hepatology 2016;64:2047-2061).
Authors: Juan Putra; Linda D Ferrell; Annette S H Gouw; Valerie Paradis; Arvind Rishi; Christine Sempoux; Charles Balabaud; Swan N Thung; Paulette Bioulac-Sage Journal: Mod Pathol Date: 2019-09-30 Impact factor: 7.842