The Grb2 splice variant, Grb3-3, is a negative regulator of RAS activation

The emerging role of receptor tyrosine kinase phase separation in cancer

Receptor tyrosine kinase (RTK)-mediated signal transduction is fundamental to cell function and drives important cellular outcomes which, when dysregulated, can lead to malignant tumour growth and metastasis. The initiation of signals from plasma membrane-bound RTKs is subjected to multiple regulatory mechanisms that control downstream effector protein recruitment and function. The high propensity of RTKs to condense via liquid-liquid phase separation (LLPS) into membraneless organelles with downstream effector proteins provides a further fundamental mechanism for signal regulation. Herein we highlight how this phenomenon contributes to cancer signalling and consider the potential impact of LLPS on outcomes for cancer patients.

The Configuration of GRB2 in Protein Interaction and Signal Transduction

Growth-factor-receptor-binding protein 2 (GRB2) is a non-enzymatic adaptor protein that plays a pivotal role in precisely regulated signaling cascades from cell surface receptors to cellular responses, including signaling transduction and gene expression. GRB2 binds to numerous target molecules, thereby modulating a complex cell signaling network with diverse functions. The structural characteristics of GRB2 are essential for its functionality, as its multiple domains and interaction mechanisms underpin its role in cellular biology. The typical signaling pathway involving GRB2 is initiated by the ligand stimulation to its receptor tyrosine kinases (RTKs). The activation of RTKs leads to the recruitment of GRB2 through its SH2 domain to the phosphorylated tyrosine residues on the receptor. GRB2, in turn, binds to the Son of Sevenless (SOS) protein through its SH3 domain. This binding facilitates the activation of Ras, a small GTPase, which triggers a cascade of downstream signaling events, ultimately leading to cell proliferation, survival, and differentiation. Further research and exploration into the structure and function of GRB2 hold great potential for providing novel insights and strategies to enhance medical approaches for related diseases. In this review, we provide an outline of the proteins that engage with domains of GRB2, along with the function of different GRB2 domains in governing cellular signaling pathways. This furnishes essential points of current studies for the forthcoming advancement of therapeutic medications aimed at GRB2.

Discovery of Potent SOS1 PROTACs with Effective Antitumor Activities against NCI-H358 Tumor Cells In Vitro/In Vivo

Directly targeted KRAS inhibitors are now facing resistance problems, which might be partially solved by the combination of SOS1 inhibitors with KRAS inhibitors. However, this combination may still have some resistance mitigation potential. Comparatively, SOS1 PROTAC may have promising applications in addressing the drug resistance problem by degrading the SOS1 protein. Herein, we report the discovery of novel SOS1 PROTACs and their antitumor activity both in vitro and in vivo. In vitro studies demonstrated that degrader 4 had strong inhibitory effects on the proliferation of NCI-H358 cells with IC50 of 5 nM, together with significant degradation of SOS1 protein with DC50 of 13 nM. In the NCI-H358 xenograft model, degrader 4 exhibited significant antitumor activities with TGITV values of 58.8% at 30 mg/kg bid. The PK and safety profiles also supported degrader 4 for further studies as an effective tool compound.