Fig. 2. Characterization of tumor cell invasiveness in β₂AR-deficient MDA-MB-231^HM breast cancer cells.

(a) Quantification of MMP2 mRNA transcript levels using qRT-PCR in scramble control, shADRB2a and shADRB2b tumor cells treated with vehicle, isoproterenol (non-selective βAR agonist, ISO, 1 µM) and/or ICI-118,551 (β₂AR-selective antagonist, 1 µM) (n = 3 – 5). (b) Fold change in proportion of tumor cells that exhibit mesenchymal-like morphology (defined by cell roundness < 0.5) in response to ISO (1 µM, normalized to vehicle) (n = 5 – 6). (c) Representative images of mesenchymal-like cells (roundness < 0.5) highlighted in orange, in cultures of scramble control, shADRB2a, shADRB2b cells after treatment with vehicle or 1 µM ISO. Inset: a magnified view of a mesenchymal-like tumor cell. Scale bar: 100 µm). (d) Quantification of invasion through transwells by scramble control, shADRB2a and shADRB2b tumor cells in response to ISO (1 µM) treatment (n = 4). Data represent mean ± standard error. *p < 0.05, **p < 0.01 and ***p < 0.001 by (b) one-way ANOVA with repeated measures or (a and d) two-way ANOVA with post hoc Tukey’s planned comparison tests. # p < 0.05, ### p < 0.001 for ISO vs. ISO + ICI-118551 within each cell line.