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

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 (IC50 ∼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.