The N-cadherin cytoplasmic domain confers anchorage-independent growth and the loss of contact inhibition

Abstract

Tumor growth is characterized by anchorage independence and the loss of contact inhibition. Previously, we showed that either a red fluorescent protein (DsRed)-tagged N-cadherin or E-cadherin cytoplasmic domain (DNCT or DECT) could function as a dominant negative inhibitor by blocking the cell surface localization of endogenous E-cadherin and inducing cell dissociation. Here, we show that expression of DNCT abrogated contact inhibition of proliferation and conferred anchorage-independent growth. DNCT expression induced the relocation of the tumor suppressor Merlin from the cell surface to intracellular compartments. Although DNCT expression induced redistribution of TAZ from the cytoplasm to the nucleus, YAP/TAZ signaling was not activated. An E-cadherin-α-catenin chimera that functions as a β-catenin-independent cell adhesion molecule restored contact inhibition and anchorage-dependency of growth. Addition of the SV40 large T antigen nuclear localization signal reversed the effects of DNCT expression, indicating that DNCT functioned outside of the nucleus.