Figure 1. ER+ breast cancer cells co-cultured with MSCs exhibit increased metastases, growth, and mesenchymal morphologies.

For all panels, cell type of interest is bolded in co-culture comparisons. Lines show pair-wise comparisons with *p <0.05,***p<0.001, or ****p<0.0001.

• a: Scheme of the monoculture versus co-culture system for breast cancer cells and MSCs.

• b: Representative whole mouse bioluminescence images of mice 101 days post intracardiac injection. Logarithmic pseudocolor scale depicts range of bioluminescence values with red being highest and blue lowest.

• c: Fraction of mice with metastatic tumor burden detectable by bioluminescence imaging post intracardiac injection over time. N = 5 mice per condition.

• d: Log₂ bioluminescence fold change of individual mice on day 101 versus day 1 post intracardiac injection overlayed on the mean value ± standard error of the mean (SEM) for each condition. As MCF7 monoculture only had one mouse with metastases, we did not perform any statistical analyses. N = 5 mice per condition.

• e-g: Mean values ± SEM of percent growth of MCF7 (e), T47D (f), and HCC1428 (g) breast cancer cells grown in monoculture, co-culture, or with conditioned media (CM) from MSCs for three days. N = 8 per condition.

• h: Representative holographic tomography images of MCF7 breast cancer cells marked by LifeAct-GFP and a mCherry nucleus in monoculture versus co-culture with MSCs. Scale bar = 20 μm.

• i: Density plots show morphometric quantification of area and perimeter of cancer cells in monoculture versus co-culture with MSCs. Regions of yellow and blue show higher and lower densities, respectively. N > 200 cells.