Comprehensive 2D and 3D phenotypic characterization of human invasive lobular carcinoma cell lines

Abstract

Invasive lobular carcinoma (ILC) is the second most common subtype of breast cancer following invasive ductal carcinoma (IDC) and characterized by the loss of E-cadherin-mediated adherens junctions. Despite displaying unique histological and clinical features, ILC still remains a chronically understudied disease with limited knowledge on the available laboratory research models. To this end, herein we report a comprehensive 2D and 3D phenotypic characterization of four Estrogen Receptor-positive human ILC cell lines - MDA-MB-134, SUM44, MDA-MB-330 and BCK4. Compared to the IDC cell lines MCF7, T47D and MDA-MB-231, ultra-low attachment culture conditions revealed a remarkable anchorage-independence ability that was unique to the ILC cells, a feature not evident in soft agar gels. 3D Collagen I and Matrigel culture indicated a generally loose morphology for the ILC cell lines, which exhibited differing preferences for adhesion to ECM proteins in 2D. Furthermore, ILC cells had limited migration and invasion ability in wound-scratch and transwell assays with the exception of haptotaxis to Collagen I. Transcriptional comparison of the cell lines confirmed the decreased cell proliferation and E-cadherin-mediated intercellular junctions in ILC, while uncovering the induction of novel pathways related to cyclic nucleotide phosphodiesterase activity, ion channels, drug metabolism and alternative cell adhesion molecules such as N-cadherin, some of which were also differentially regulated in ILC versus IDC tumors. Altogether, these studies will serve as an invaluable resource for the breast cancer research community and facilitate further functional discoveries towards understanding ILC, identifying novel drug targets and ultimately improving the outcome of patients with ILC.