Abstract 2605: Cytokeratin 5 promotes endocytosis to remodel cell adhesions in breast cancer

Breast cancer (BC) is clinically classified according to expression of estrogen receptor, progesterone receptor (ER+ BC), HER2 (HER2+), or absence of these markers (triple negative BC). While TNBC has the inferior prognosis in the short term, ER+ breast cancer has an extended risk of recurrence that lasts up to 20 years and accounts for the most deaths overall. Cytokeratin 5 (CK5) is an intermediate filament protein that is expressed in the majority of TNBC cases and 10-50% of ER+ BC. In CK5+/ER+ BC, there is widespread heterogeneity in the amount of CK5+ tumor cells (~1-50%). The mere presence of CK5+ cells is an indicator of poor prognosis across both subtypes of BC; the reasons for this are poorly understood. We have shown that CK5+ cells within ER+ and TNBC cell lines, and heterogeneous PDX tumor models lose membrane localization of adherens junction proteins β-catenin and E-cadherin. Loss of membrane β-catenin and E-cadherin is associated with poor prognosis in breast cancer and is a precursor to cell invasion. CK5+ cells have been reported to have increased invasive potential by us and others. Thus, identifying the mechanism of CK5-dependent loss of adherens proteins at the membrane could lead to development of therapies targeting this process. β-catenin and E-cadherin localization have been reported to be regulated through endocytosis which is mediated through the small GTPase family of Rab proteins. We performed a screen to identify potential CK5 interacting proteins in breast cancer cells and identified several Rab proteins. Thus, we hypothesize that CK5 acts as a scaffold for Rabs to promote endocytosis of β-catenin and E-cadherin to increase invasive potential.To investigate this, we treated CK5 overexpressing ER+ and TNBC cells with the endocytosis inhibitor Dyngo4a and found membrane β-catenin and E-cadherin localization were restored, suggesting that CK5 may be mediating endocytosis of β-catenin and E-cadherin. Rab5 is responsible for trafficking vesicles from the plasma membrane to the early endosomes. CK5 was confirmed to interact with Rab5 by co-IP in TNBC and CK5 overexpressing ER+ cell lines. In ongoing studies, we are testing whether Rab5 knockdown prevents loss of membrane β-catenin and E-cadherin and decreases cell invasiveness. These experiments will collectively determine whether CK5 regulated endocytosis is a targetable feature in breast cancer cells.

Citation Format: Olivia Frances McGinn, Ashley V. Ward, Jessica Finlay-Schultz, Kiran Vinod Paul, Peter Kabos, Carol Sartorius. Cytokeratin 5 promotes endocytosis to remodel cell adhesions in breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2605.

Multiparameter optimisation of a magneto-optical trap using deep learning

Machine learning based on artificial neural networks has emerged as an efficient means to develop empirical models of complex systems. Cold atomic ensembles have become commonplace in laboratories around the world, however, many-body interactions give rise to complex dynamics that preclude precise analytic optimisation of the cooling and trapping process. Here, we implement a deep artificial neural network to optimise the magneto-optic cooling and trapping of neutral atomic ensembles. The solution identified by machine learning is radically different to the smoothly varying adiabatic solutions currently used. Despite this, the solutions outperform best known solutions producing higher optical densities.