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Internalization and intracellular trafficking of G protein-coupled receptors (GPCRs) play pivotal roles in cell responsiveness. Dysregulation in receptor trafficking can lead to aberrant signaling and cell behavior. Here, using an endosomal BRET-based assay in a high-throughput screen with the prototypical GPCR angiotensin II type 1 receptor (AT1R), we sought to identify receptor trafficking inhibitors from a library of ~115,000 small molecules. We identified a novel dual Ras and ARF6 inhibitor, which we named Rasarfin, that blocks agonist-mediated internalization of AT1R and other GPCRs. Rasarfin also potently inhibits agonist-induced ERK1/2 signaling by GPCRs, and MAPK and Akt signaling by EGFR, as well as prevents cancer cell proliferation. In silico modeling and in vitro studies reveal a unique binding modality of Rasarfin within the SOS-binding domain of Ras. Our findings unveil a class of dual small G protein inhibitors for receptor trafficking and signaling, useful for the inhibition of oncogenic cellular responses., While Ras is a promising target for cancer therapy, development of inhibitors targeting Ras signaling has proven challenging. Here, the authors report the discovery of Rasarfin, a small molecule from a phenotypic screen on G protein-coupled receptor (GPCR) endocytosis that acts as a dual Ras and ARF6 inhibitor.

The Transient Receptor Potential A1 (TRPA1) ion channel has evolved in animals to respond to signals from a variety of sensory stimuli. Many structural determinants of its multimodal activation have been identified to date. TRPA1 activities include responses to exogenous chemical irritants, responses to endogenous inflammatory mediators, zinc, voltage, temperature or stretch and subtle yet critical modulation by calcium ions. TRPA1 has emerged as an important target for several types of pain and inflammatory conditions because of its limited expression profile and its demonstrated roles in mediating different types of pain and sensitization of peripheral sensory afferents. Despite observed species differences in channel pharmacology, recent genetic evidence in human brings some hope that preclinical efficacy in disease models will translate to patient condition. During the past decade, various groups have investigated the development of a new class of analgesic drugs or anti-tussive agents aimed at blocking TRPA1 activity in primary sensory afferents. Several companies are advancing toward clinical proof of concept studies. This review aims to summarize key advances in the understanding of TRPA1 with regard to its roles and implications for patient conditions.

During inflammation, several Transient Receptor Potential (TRP) channels are directly or indirectly activated by inflammatory signaling molecules and microenvironmental changes including heat, oxidative conditions or low pH. In either case, specific TRP isoforms participate in chains of pro- or anti-inflammatory signaling cascades often including activation of transcription factors, protein kinases and phospholipases, which result in signal integration or amplification. In a few cases, their potentials as therapeutic targets for inflammatory conditions like pruritis, cystitis, dermatitis, asthma among other conditions are investigated pre-clinically or clinically by pioneering academic groups and industries. Significant efforts are still devoted to the understanding of the detailed physiological roles played by TRP channels during inflammation. This review intends to summarize key biological findings and reports of drug discovery activities when available, in an overview of the current status and recent developments in the field.

TRPV1 was originally characterized as an integrator of various noxious stimuli such as capsaicin, heat, and protons. TRPV1-null mice exhibit a deficiency in sensing noxious heat stimuli, suggesting that TRPV1 is one of the main heat sensors on nociceptive primary afferent neurons and a candidate target for heat hypersensitivity in chronic pain. Several different potent and selective TRPV1 antagonists have been developed by more than 50 companies since the characterization of the receptor in 1997. A consequence of this competitive interest is the crowding of patentable chemical space, because very similar in vitro screening assays are used. To circumvent this issue and to expand our understanding of TRPV1 biology, we sought to take advantage of recent advancements in automated patch-clamp technology to design a novel screening cascade. This SAR-driving assay identified novel modulators that blocked the depolarization-induced activation of outwardly-rectifying TRPV1 currents independent of agonist stimulation, and we correlated the pharmacology to three other innovative assays for higher-throughput screening. Ultimately, we have identified a screening paradigm that would have good predictive value for future TRPV1 drug discovery projects and novel chemical space with a higher probability of gaining intellectual property coverage.