β2-adrenoceptor signaling regulates invadopodia formation to enhance tumor cell invasion

Abstract

IntroductionFor efficient metastatic dissemination, tumor cells form invadopodia to degrade and move through three-dimensional extracellular matrix. However, little is known about the conditions that favor invadopodia formation. Here, we investigated the effect of β-adrenoceptor signaling - which allows cells to respond to stress neurotransmitters - on the formation of invadopodia and examined the effect on tumor cell invasion.MethodsTo characterize the molecular and cellular mechanisms of β-adrenergic signaling on the invasive properties of breast cancer cells, we used functional cellular assays to quantify invadopodia formation and to evaluate cell invasion in two-dimensional and three-dimensional environments. The functional significance of β-adrenergic regulation of invadopodia was investigated in an orthotopic mouse model of spontaneous breast cancer metastasis.Resultsβ-adrenoceptor activation increased the frequency of invadopodia-positive tumor cells and the number of invadopodia per cell. The effects were selectively mediated by the β2-adrenoceptor subtype, which signaled through the canonical Src pathway to regulate invadopodia formation. Increased invadopodia occurred at the expense of focal adhesion formation, resulting in a switch to increased tumor cell invasion through three-dimensional extracellular matrix. β2-adrenoceptor signaling increased invasion of tumor cells from explanted primary tumors through surrounding extracellular matrix, suggesting a possible mechanism for the observed increased spontaneous tumor cell dissemination in vivo. Selective antagonism of β2-adrenoceptors blocked invadopodia formation, suggesting a pharmacological strategy to prevent tumor cell dissemination.ConclusionThese findings provide insight into conditions that control tumor cell invasion by identifying signaling through β2-adrenoceptors as a regulator of invadopodia formation. These findings suggest novel pharmacological strategies for intervention, by using β-blockers to target β2-adrenoceptors to limit tumor cell dissemination and metastasis.

Cancer cells become less deformable and more invasive with activation of β-adrenergic signaling

“…To independently validate the effect of βAR in cancer cell deformability, we complemented our pharmacological approach with a genetic strategy to knockout the β 2 AR receptor in breast cancer cells. Our previous results show that β 2 AR is the only active βAR subtype in MDA-MB-231 cells (Creed et al, 2015). To delete β 2 AR, we used CRISPR-Cas9 technology to mutate the ADRB2 gene in MDA-MB-231 cells.…”

“…Activation of β-adrenergic signaling is an emerging factor that promotes metastasis and accelerates cancer progression Sloan et al, 2010;Thaker et al, 2006). Cancer cells express β-adrenoceptors, whose activation results in increased invasion and metastasis in vivo (Creed et al, 2015;Le et al, 2016); this suggests that targeting the β-adrenergic signaling pathway might be a promising strategy to slow disease progression, especially for diseases such as triple-negative breast cancer and pancreatic cancer, which are often aggressive and have few treatment options once chemoresistance develops. Inhibition of β-adrenergic signaling is an especially promising therapeutic strategy: an effective antagonist for β-adrenergic receptors (βARs) are β-blocker drugs, which are already widely used to treat cardiac disease and hypertension (Barrese and Taglialatela, 2013;Wiysonge et al, 1996).…”

“…Inhibition of β-adrenergic signaling is an especially promising therapeutic strategy: an effective antagonist for β-adrenergic receptors (βARs) are β-blocker drugs, which are already widely used to treat cardiac disease and hypertension (Barrese and Taglialatela, 2013;Wiysonge et al, 1996). β-blockers inhibit metastasis in vivo (Campbell et al, 2012;Creed et al, 2015;Le et al, 2016;Sloan et al, 2010;Sood et al, 2006) and analyses of cancer patient cohort data has revealed that coincidental use of β-blockers is linked to reduced metastasis and improved survival (Barron et al, 2011;Le et al, 2016;Melhem-Bertrandt et al, 2011;Powe et al, 2010). Recent mechanistic studies show that β-adrenergic signaling modulates metastasis by driving changes in the tumor microenvironment including vascular remodeling and immune cell recruitment Thaker et al, 2006).…”

“…Recent mechanistic studies show that β-adrenergic signaling modulates metastasis by driving changes in the tumor microenvironment including vascular remodeling and immune cell recruitment Thaker et al, 2006). βAR activation also promotes the formation of invadopodia by tumor cells, which are essential for invasion (Creed et al, 2015). Better knowledge of the physical and mechanical changes that drive cancer cells to become more invasive with β-adrenergic signaling could provide a deeper mechanistic understanding of cancer progression and identify more effective treatment strategies.…”

“…To model invasive breast cancer in vitro, we used MDA-MB-231 breast cancer cells (Creed et al, 2015;Pon et al, 2016). We used both pharmacological and genetic tools to manipulate β-adrenergic signaling in cancer cells.…”