A high-throughput screen to identify novel synthetic lethal compounds for the treatment of E-cadherin-deficient cells

Henry Beetham,Parry Guilford,Kate E Jarman,Andrew Single,Bryony J Telford,Augustine Chen,Kurt Lackovic,Andreas Luxenburger

doi:10.1038/s41598-019-48929-0

Abstract

The cell-cell adhesion protein E-cadherin (CDH1) is a tumor suppressor that is required to maintain cell adhesion, cell polarity and cell survival signalling. Somatic mutations in CDH1 are common in diffuse gastric cancer (DGC) and lobular breast cancer (LBC). In addition, germline mutations in CDH1 predispose to the autosomal dominant cancer syndrome Hereditary Diffuse Gastric Cancer (HDGC). One approach to target cells with mutations in specific tumor suppressor genes is synthetic lethality. To identify novel synthetic lethal compounds for the treatment of cancers associated with E-cadherin loss, we have undertaken a high-throughput screening campaign of ~114,000 lead-like compounds on an isogenic pair of human mammary epithelial cell lines – with and without CDH1 expression. This unbiased approach identified 12 novel compounds that preferentially harmed E-cadherin-deficient cells. Validation of these compounds using both real-time and end-point viability assays identified two novel compounds with significant synthetic lethal activity, thereby demonstrating that E-cadherin loss creates druggable vulnerabilities within tumor cells. In summary, we have identified novel synthetic lethal compounds that may provide a new strategy for the prevention and treatment of both sporadic and hereditary LBC and DGC.

Highlights

E-cadherin is a calcium-dependent transmembrane glycoprotein, expressed predominantly at the adherens junction on the basolateral surface of epithelial cells
Despite controlling for the usual causes of positional effects in HTS35, we found that temperature fluctuations of the plates during end-point cell titre blue (CTB) fluorescence readings were producing a classic edge effect (Fig. 1A)
We hypothesized that CDH1 loss creates vulnerabilities in a tumor cell that can be targeted with drugs using a synthetic lethal approach

Summary

Introduction

E-cadherin is a calcium-dependent transmembrane glycoprotein, expressed predominantly at the adherens junction on the basolateral surface of epithelial cells It has long been regarded as a tumor suppressor due to its frequent downregulation in sporadic tumors during invasion and metastasis[1] and the high frequency of inactivating CDH1 mutations that are observed in diffuse gastric cancer (DGC) and lobular breast cancer (LBC). Females with germline CDH1 mutations have an additional ~40% lifetime risk of developing LBC8,10,11 Breast cancer is both the most common cancer in women and the leading cause of cancer death[12]. The breast cancer risk in HDGC families is usually managed by routine screening; prophylactic mastectomy is currently not recommended[9], but remains an option for some women. LCIS is a LBC precursor that is often CDH1 negative and increases the risk of developing LBC by 8–10 fold[28,29]

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Conclusion