PO-333 Somatic engineering of mammary gland epithelial cells using CRISPR/Cas9 for rapid testing of breast cancer susceptibility genes in mouse models

Abstract

IntroductionBreast cancer is one of the most commonly diagnosed malignancies in women. In Western countries it is the second leading cause of cancer death among women. Five to ten percent of all breast cancers have a hereditary component, and approximately twenty five percent of all hereditary breast and ovarian cases are attributable to mutations in the breast cancer 1 or breast cancer 2 (BRCA1 or BRCA2) genes. In vivo studies represent a highly comprehensive and relevant setting for studying the complexity of this human disease. Genetically engineered germline mouse models of breast cancer paved the way for improved basic and translational research, but their generation is slow and expensive.Material and methodsTo overcome these limitations, our lab previously developed CRISPR/Cas9-mediated somatic genome editing approaches to test the role of candidate factors in the adult mammary tissue. In particular, a conditional Cas9-expressing mouse model was used for intraductal injection of sgRNAs encoding lentiviruses (LV-sgRNA), which allowed for somatic gene disruption of tumour suppressor genes in mammary epithelial cells and for evaluating the effect on tumour formation and disease progression (Annunziato et al. 2016).Results and discussionsWe will extend this approach to analyse candidate susceptibility genes in triple negative breast cancer. Using a K14Cre;p53F/F;Cas9 mouse model, this LV-sgRNA intraductal platform provides the opportunity to test in vivo several new (candidate) susceptibility genes and study the effects of tumour suppressor domain deletions.ConclusionThrough these studies, we hope to shed light on several genetic alterations and how they affect tumour suppression and drug response.