Unbiased Screening of Activated Receptor Tyrosine Kinases (RTKs) in Tumor Extracts Using a Mouse Phospho-RTK Array Kit.

Kaposi's sarcoma (KS) herpesvirus (KSHV) is a virus that causes KS, an angiogenic AIDS-associated spindle-cell neoplasm, by activating host oncogenic signaling cascades through autocrine and paracrine mechanisms. Many host signaling cascades co-opted by KSHV including PI3K/AKT/mTORC, NFkB and Notch are critical for cell-specific mechanisms of transformation and their identification is paving the way to therapeutic target discovery. Analysis of the molecular KS signature common to human KS tumors and our mouse KS-like tumors showed consistent expression of KS markers VEGF and PDGF receptors with upregulation of other angiogenesis ligands and their receptors in vivo. This points to the autocrine and paracrine activation of various receptor tyrosine kinase (RTK) signaling axes. Hereby we describe a protocol to screen for activated receptor tyrosine kinase of KSHV-induced KS-like mouse tumors using a Mouse Phospho-RTK Array Kit and its validation by RTK western blots. We showed that this method can be successfully used to rank the tyrosine kinase receptors most activated in tumors in an unbiased manner. This allowed us to identify PDGFRA as an oncogenic driver and therapeutic target in AIDS-KS.