Establishing LOX as a Critical Component of Adipocyte-Induced Mesenchymal-to-Epithelial transition in Human Triple Negative Breast Cancer Cells

Grant Kelly
PhD Student 
Department of Biochemistry

Date: November 18, 2024
Time: 1:00 p.m. to 2:00 p.m. 
Room: CSF 1302

Abstract:

Metastasis is the leading cause of death among breast cancer patients. Metastasis begins as cancer cells break away from the primary tumour to invade and colonize distant tissue. To aid metastasis, tumour cells may undergo an epithelial-to-mesenchymal transition (EMT), a type of morphology change which results in more motile and invasive cancer cells. These cells then undergo the reverse process, a mesenchymal-to-epithelial transition (MET), to form new tumours in distant tissues. Recent work published by our group showed the ability for adipocytes, which are abundant at the most common sites of metastasis, such as bone marrow and the brain, to induce MET in triple negative breast cancer cells (TNBCs), but only when co-cultured in three-dimensions (3D). Furthermore, we found adipocytes grown in a 3D environment secreted an extracellular protein called LOX, while adipocytes grown in traditional cell culture did not. LOX alone was found to induce a partial MET in TNBCs without the presence of adipocytes. However, it remains unclear whether adipocyte-secreted LOX is necessary to produce MET in TNBCs co-cultured with adipocytes in 3D. To that end, we have found that Lox is a critical mediator of adipocyte-dependent MET in TNBCs. Inhibition of Lox activity, using siRNA or chemical inhibition, in 3D co-culture should cause breast cancer cells to, at least partially, lose epithelial features and display more mesenchymal features. Breast cancer cells in a Lox-deficient environment should form smaller colonies and have a higher proportion of stellate cells, in comparison to untreated control. There are two proteins of interest which control the activity of LOX via proteolytic cleavage, BMP-1 and ADAMTS-2. Western blot analysis will determine how these proteases and Lox are affected by the presence of extracellular matrix — a distinguishing component of 3D co-culture. In total, these data will demonstrate the critical role of Lox in adipocyte-dependent MET and provide some insight into its regulation. In the future, these experiments will be translated into an in vivo model, hopefully, providing evidence that Lox has a larger role in breast cancer metastasis.