Understanding the Role of Runx2 in a Breast Cancer Progression Cell Model

Runx2 is a transcription factor required for bone formation and osteoblastic differentiation during normal development and is implicated in metastatic disease during breast cancer progression. Runx2 is highly expressed in many metastatic breast cancers and breast cancer cell lines Knockdown of Runx2 in various breast cancer cell lines restores epithelial characteristics and reduces proliferation, migration, and invasion. However, the role of Runx2 in breast cancer progression from early to late stages is not well understood. The MCF10A derived breast cancer progression model provides the opportunity to study the role of Runx2 in a series of cell lines that progress from nearly normal, with low Runx2 levels, to highly metastatic and aggressive, with much higher Runx2 levels. To address if removal of Runx2 affects gene expression and what pathways it may influence, specifically focused on breast cancer progression, we knocked down Runx2 using an shRNA lentivirus. Depletion of Runx2 inhibits the expression of mesenchymal markers including N-cadherin, Fibronectin, and Vimentin. Despite this finding, functional characteristics including proliferation, migration, and invasion were minimally affected. Possible reasons for the difference in results compared to other cell systems are discussed. As an alternative approach, we have generated stable, inducible cell lines using CRISPRi dCas9-KRAB to target Runx2 and in the future will investigate the effects of Runx2 knockdown in these cells.