Understanding Mechanisms of Metastasis of Aggressive Breast Cancers via Microfluidic Means

Abstract

The spread of cancer from its site of origin to other organs is called metastasis, and it is this stage of the disease that is responsible for over 90% of cancer deaths. Tumors are comprised of a heterogeneous population and not every cell in a primary tumor has the intrinsic capability to metastasize. Understanding what gives certain metastatically enabled cells this potential will ultimately provide insight into how to target and prevent metastases. In order to form a metastasis, a cancer cell must: move, invade through often stiff supporting tissue, enter the vasculature via small intercellular spaces, survive the hydrodynamic forces of circulation, squeeze through vessel endothelium once again, and finally proliferate. Imbued with the knowledge of this metastatic journey of a cancer cell, it is understandable how very physical and mechanical in nature the process is. Therefore, to study the steps of metastasis effectively requires the ability to precisely control physical attributes of a cell’s surroundings. The engineering field of microfluidics affords this opportunity and in this work I advanced our present knowledge of the metastatic process by using microfluidic techniques in four fundament studies of critical steps required for metastases. In one study, cancer cells are challenged with a geometrically confining migration space which mimics the constraints of a lymphatic capillary and the early necessary intravasation metastatic step. After migration, motile and non-motile cells are recaptured and analyzed for genetic differences which allow for intravasation. In another study, the effects of secreted factors from normal immune cells in the tumor microenvironment are tested for their stimulation of cancer cell migration – the first required step of metastasis – in the most aggressive form of breast cancer that is considered metastatic at its inception. A third study leveraged the adhesive properties of cancer cells as a novel paradigm for circulating tumor cell capture and analysis independent of dynamic cell surface markers. Lastly, specifically designed microfluidic assays were used to determine a multiparametric cellular phenotype of the most aggressive subpopulation of cancer cells’ biomechanical properties, which may confer the capability to effectively traverse the inefficient steps of metastasis.