Spatial control of cAMP/PKA by integrin receptors

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DESCRIPTION (provided by applicant): Cell motility is a fundamental and indispensable aspect of both tumor cell invasion and metastasis. As such, uncontrolled tumor cell motility is directly responsible for the vast majority of cancer deaths and, therefore, represents an excellent target for therapeutic intervention. To better understand cell motility, this study will explore signaling from integrins, which are receptors for the extracellular matrix that transduce signals that are critical for cell motility. Recently, integrins were shown to regulate Protein Kinase A (PKA) through the synthesis and degradation of cAMP mediated by different subsets of integrin receptors. Importantly, this regulation of PKA is critical for cell motility due to the involvement of PKA in the differential regulation of Rac and Rho GTPases. However, the mechanisms of integrin regulation of cAMP/PKA and how this regulation promotes cell motility are unclear. The long-term goal of this project is to understand how integrins and their control of cAMP metabolism promote carcinoma cell invasion. The objective of this proposal is to understand how integrins regulate the spatial distribution of cAMP/PKA during the chemotactic migration of breast carcinoma cells. In our first aim, we will define the distribution of activated PKA using in chemoattractant-stimulated cells using fluorescence resonance energy transfer (FRET) technique and assess the contributions of alpha6beta4 and beta1 integrins to this distribution. In our second aim, we will determine how beta1 integrins signal to PKA by identifying the adenyl cyclase isoforms expressed in our cell system and reducing their expression using small interfering RNAs (siRNAs). Using state-of-the-art technologies and our ideal model system, we expect that these approaches will identify cAMP/PKA activity gradients that influence cell polarity during cell migration and begin elucidating how they form. These studies will be significant because they will give us information that will permit us to intelligently target PKA as a target for therapeutic intervention of late-stage cancer. This is an exciting possibility since drugs targeting cAMP are currently being developed for treating inflammation that also have the potential to decrease cancer patient morbidity and mortality.