Tumor microenvironment-activated ferritin nanovector enables enhanced tumor delivery of KRASG12C inhibitors and degraders – Research

FIGURE 1

FIGURE 1

Molecular mechanisms of KRAS, PROTACs and The-05. (A) KRAS as a Molecular Switch and its Role in Cancer. KRAS functions as a guanosine diphosphate (GDP)/triphosphate (GTP) binary switch, which is mainly determined by regulatory guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). KRAS controls important signal transduction from activated membrane receptors to intracellular molecules to nucleus, and particularly the PI3K-PDK1-AKT pathway, the RAF-MEK-ERK pathway, the PLC-PKC pathway and the RALGDS-RAL pathway. These pathways control cellular proliferation, survival, differentiation and angiogenesis. Mutated KRAS (in particular, KRAS mutations G12C, G12D and G12V) is permanently activated, and leads to uncontrolled signal transduction, uncontrolled cellular proliferation, survival, differentiation and angiogenesis, that lead to tumor development and metastasis. (B) Mechanism of action of a PROTAC. PROTACs are heterobifunctional molecules designed to induce the ubiquitination and subsequent degradation of specific proteins of interest (POIs). A PROTAC consists of three key components: a moiety that binds to an E3 ubiquitin ligase, a linker and a moiety that binds to the POI (a) PROTACs hijack the ubiquitin-proteasome system (UPS). The UPS is a highly conserved cellular mechanism for degrading proteins. It involves three main enzymes: Ubiquitin-activating enzyme (E1), Ubiquitin-conjugating enzyme (E2), and Ubiquitin ligase (E3). E1 activates free ubiquitin (Ub), which is then transferred to E2. E3 ligases are responsible for specifically recognizing substrates and facilitating the transfer of Ub from E2 to a lysine residue (Lys) on the substrate. Repeated ubiquitination forms a poly-ubiquitin chain, targeting the substrate for degradation by the 26S proteasome. PROTACs work by bringing the POI into close proximity with the E2-E3 complex (b) This trimeric complex formation facilitates the transfer of ubiquitins to the POI (c) The resulting poly-ubiquitinated POIs (d) are then rapidly degraded by the proteasome (e) A key feature of PROTACs is their catalytic, event-driven mechanism of action: a single PROTAC molecule can induce the degradation of multiple POI molecules, as it is released to bind another POI after inducing degradation. (C) Mechanism of Action of The-05 Nanocarrier. The The-05 polypeptide is engineered with an N-terminal shielding PASE moiety (blue), a matrix metalloprotease (MMP)-cleavable linker (green), and a C-terminal human ferritin heavy chain (HFt, orange). These components fold into a The-05 monomer. In the presence of the drug (either Adagrasib or the LC-2 PROTAC), and using a simple pH-dependent association-dissociation protocol, these monomers self-assemble into a shielded The-05 24-mer. The drug is encapsulated within the internal cavity of this stimuli-sensitive protein, which is then ready for administration. In vivo, within the tumor microenvironment (TME), the abundant MMPs cleave the PASE shield, leading to its release. The de-shielded The-05 is subsequently internalized by tumor cells via the highly expressed Transferrin Receptor 1 (TfR1, CD71). Once inside the tumor cell, the encapsulated drug is rapidly released, where it can then exert its inhibitory effect on KRAS.