I10 - Adhesion Strength of Tumor Cells Predicts Metastatic Disease in vivo

Introduction: : It is difficult to determine metastatic potential within breast cancer due to a lack of a universal molecular prognostic marker. Prior evidence supports a biophysical marker, i.e., the weakly adherent fraction of a cell population–when selected by a parallel-plate flow chamber (PPFC), as a more accurate means of stratifying tumor metastatic potential. We demonstrate that cells with weak adhesion strength in vivo have increased metastatic potential compared to strongly adherent cells. Additionally, utilizing a patented divergent parallel plate flow chamber (dPPFC) we have assayed the adhesion strength of invasive (invasive lobular carcinoma/ILC; invasive ductal carcinoma/IDC) and noninvasive (ductal carcinoma in situ/DCIS) breast cancer from human patients, finding that cells from IDC/ILC have a lower adhesion strength than cells from DCIS.

Materials and

Methods: : GFP+Luc+MDAMB231 cells were seeded onto glass slides within the PPFC and exposed to shear stress to collect weakly adherent cells. Cells that remained on the slide were trypsinized and collected as strongly adherent cells. The strongly adherent, weakly adherent, or unsorted populations were injected into the mammary fat pad of NOD/SCIDy mice. Human samples were collected from patients that underwent lumpectomies or mastectomies. Samples were digested into a single cell suspension and using the dPPFC, slides were exposed to a gradient of shear stresses. Τ75, or the shear stress at which 25% of seeded cells are sheared off, was found.

Results, Conclusions, and Discussions:: We sorted GFP+Luc+ MDAMB231 population into strongly and weakly adherent cells and, along with unselected control, injected cells into mammary fat pads of mice (Fig 1A). The number of lung metastases was significantly higher for mice receiving weakly adherent cells (Fig. 1B-C). dPPFC analyses provide label-free measurements of adhesion strength and cell abundance, and when applied to metastatic disease can retrospectively predict metastatic potential (Fig. 1D). dPPFC results show IDC/ILC have a weaker adhesion strength than cells from DCIS (Fig. 1E) in a human patient trial using our patented dPPFC device. Results suggest that weakly adherent cells migrate out of the primary tumor microenvironment, and shear stress measurements can retrospectively predict metastatic capacity in vivo. Patient tumors of invasive cancer are composed of a larger population of weakly adherent cells than patient tumors of DCIS.

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