Glycation of collagen matrices promotes breast tumor cell invasion.

Cancer metastasis is a physical process in which tumor cells break away from the primary tumor, enter, and then exit the blood or lymph vessels, and establish secondary tumors in distant organs. Current clinical studies report a higher risk of cancer metastasis for diabetics than non-diabetics. However, due to complex overlapping risk factors between diabetes and cancer, the mechanism underlying this correlation is largely unknown. Elevated lifetime blood sugar levels in diabetics are known to increase glycation of collagen, causing stiffening of the ECM and connective tissue. In this study, we explored the roles of glycation of 3D collagen matrices in tumor cell invasion and migration. Using time-lapse images, we quantitatively compared the motility behavior of malignant breast tumor cells (MDA-MB-231) and co-culture spheroids (1:1 ratio of MDA-MB-231 cells with normal epithelial MCF-10A cells) embedded in glycated and non-glycated collagen matrices of various concentrations. Experimental results demonstrated that glycation increased tumor invasion within collagen matrices. More specifically, the average speed of MDA-MB-231 cells was higher in glycated collagen gels than in non-glycated collagen gels for all three gel concentrations tested. Cell spreading characterized by its diffusion coefficient or the effective spheroid radii at various time points was significantly greater in glycated collagen than in non-glycated collagen at a concentration of 3.5 mg/mL. This enhancement was moderate and less evident at lower collagen concentrations of 1.0 and 2.0 mg/mL. These results suggest a possible biomechanical link that relates to the high blood sugar level in diabetic patients and the cancer metastatic outcome.