Targeting the PLEC/TPM4 cytoskeletal axis: DT-13 inhibits colorectal cancer metastasis through direct binding to PLEC and inactivation of Akt/ERK signaling

DT-13 potently inhibits CRC metastasis with a favorable biosafety profile. • Plectin (PLEC) is identified as the direct intracellular binding target of DT-13. • DT-13 occupies the PLEC CH domain to physically disrupt the PLEC-TPM4 interactome. • Target engagement down-regulate TPM4 and suppresses Akt/ERK-driven EMT programs. Background Metastasis is the leading cause of colorectal cancer (CRC) mortality. Standard 5-fluorouracil (5-FU) has limited anti-metastatic efficacy and dose-dependent toxicities, underscoring the need for therapeutic alternatives with improved safety profiles. Methods This study investigated the anti‑metastatic mechanism of Liriope muscari baily saponins C (DT‑13) in CRC. Cell viability, migration, and invasion were assessed in HCT116 cells. An orthotopic CRC model was established in BALB/c nude mice to compare the therapeutic efficacy and hematological safety of DT-13 against 5-FU. Direct targets of DT-13 were identified using chemical proteomics (small‑molecule pull‑down, cellular thermal shift assay, drug affinity responsive target stability assay) and molecular dynamics simulations. Results DT-13 inhibited HCT116 proliferation (IC 50 ∼19 μM) and reduced migration and invasion by 78% and 90% in vitro. In vivo , DT-13 achieved a comparable reduction in tumor volume to 5-FU (21% of control volume), while exhibiting a favorable safety profile. Chemical proteomics identified plectin (PLEC) as a primary direct target of DT-13. Molecular docking revealed a binding affinity of –7.654 kcal/mol. Mechanistically, DT-13 occupied the calponin homology domain of PLEC, disrupting its interaction with tropomyosin-4 (TPM4). This led to TPM4 downregulation and subsequently inhibition of Akt and ERK signaling pathways, thereby suppressing the epithelial-mesenchymal transition process. Conclusion DT‑13 exerts anti-metastatic effects in CRC by disrupting the PLEC/TPM4 cytoskeletal scaffold. DT-13 achieved potent anti-metastatic efficacy with a significantly improved systemic safety profile compared to 5-FU. These findings highlight the clinical potential of DT-13 as a safer therapeutic alternative for patients with metastatic CRC. Download: Download high-res image (126KB) Download: Download full-size image