A parallel-gradient microfluidic chamber for quantitative analysis of breast cancer cell chemotaxis

Wajeeh Saadi, Shur-Jen Wang, Francis Lin, Noo Li Jeon

Growth factor-induced chemotaxis of cancer cells is believed to play a critical role in metastasis, directing the spread of cancer from the primary tumor to secondary sites in the body. Understanding the mechanistic and quantitative behavior of cancer cell migration in growth factor gradients would greatly help in future treatment of metastatic cancers. Using a novel microfluidic chemotaxis chamber capable of simultaneously generating multiple growth factor gradients, we examined the migration of the human metastatic breast cancer cell line MDA-MB-231 in various conditions. First, we quantified and compared the migration in two gradients of epidermal growth factor (EGF) spanning different concentrations: 0-50 ng/ml and 0.1-6 ng/ml. Cells showed a stronger response in the 0-50 ng/ml gradient. However, the fact that even a shallow gradient of EGF can induce chemotaxis, and that EGF can direct migration over a large dynamic range of gradients, confirms the potency of EGF as a chemoattractant. Second, we investigated the effect of antibody against the EGF receptor (EGFR) on MDA-MB-231 chemotaxis. Quantitative analysis indicated that anti-EGFR antibody impaired both motility and directional orientation (CI = 0.03, speed = 0.71 microm/min), indicating that cell motility was induced by the activation of EGFR. The ability to compare, in terms of quantitative parameters, the effects of different pharmaceutical inhibitors, as well as subtle differences in experimental conditions, will aid in our understanding of mechanisms that drive metastasis. The microfluidic chamber described in this work will provide a platform for cell-based assays that can be used to compare the effectiveness of different pharmaceutical compounds targeting cell migration and metastasis.