?E-catenin is a candidate tumor suppressor for the development of E-cadherin-expressing lobular-type breast cancer.
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ABSTRACT: Although mutational inactivation of E-cadherin (CDH1) is the main driver of invasive lobular breast cancer (ILC), approximately 10-15% of all ILCs retain membrane-localized E-cadherin despite the presence of an apparent non-cohesive and invasive lobular growth pattern. Given that ILC is dependent on constitutive actomyosin contraction for tumor development and progression, we used a combination of cell systems and in vivo experiments to investigate the consequences of ?-catenin (CTNNA1) loss in the regulation of anchorage independence of non-invasive breast carcinoma. We found that inactivating somatic CTNNA1 mutations in human breast cancer correlated with lobular and mixed ducto-lobular phenotypes. Further, inducible loss of ?-catenin in mouse and human E-cadherin-expressing breast cancer cells led to atypical localization of E-cadherin, a rounded cell morphology, and anoikis resistance. Pharmacological inhibition experiments subsequently revealed that, similar to E-cadherin-mutant ILC, anoikis resistance induced by ?-catenin loss was dependent on Rho/Rock-dependent actomyosin contractility. Finally, using a transplantation-based conditional mouse model, we demonstrate that inducible inactivation of ?-catenin instigates acquisition of lobular features and invasive behavior. We therefore suggest that ?-catenin represents a bona fide tumor suppressor for the development of lobular-type breast cancer and as such provides an alternative event to E-cadherin inactivation, adherens junction (AJ) dysfunction, and subsequent constitutive actomyosin contraction. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
SUBMITTER: de Groot JS
PROVIDER: S-EPMC6055824 | biostudies-other | 2018 Aug
REPOSITORIES: biostudies-other
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