Chaperone-Mediated Autophagy-Directed Degradation of PI3K in Tumor Cells: Development of Multifunctional Peptide-Drug Conjugates With Enhanced Penetration and Selectivity.

The phosphatidylinositol 3-kinase (PI3K) pathway is frequently hyperactivated in cancers, promoting tumor growth and resistance to conventional therapies. Conventional PI3K inhibitors often suffer from poor tumor selectivity, systemic toxicity, and the development of acquired resistance. To overcome these issues, we have designed multifunctional peptide-drug conjugates (PDCs) utilizing chaperone-mediated autophagy (CMA), a selective lysosomal degradation mechanism, for precise targeting of PI3K. Our approach began with the development of a lead compound, CC-3, derived from Copanlisib and incorporating a CMA-recognition motif (KFERQ-like sequence). We further enhanced this compound by creating TCCC-1, integrating a tumor-homing peptide (Thx) and a cell-penetrating peptide (T2) to improve cellular uptake and specificity. In vitro studies revealed that TCCC-1 effectively induced PI3K degradation, inhibited downstream pAkt signaling, and promoted apoptosis alongside G2/M cell cycle arrest in non-small cell lung cancer (NSCLC) cells, including those resistant to Copanlisib. In vivo experiments using NCI-H460 xenograft models demonstrated that TCCC-1 achieved up to 97.0% tumor suppression at high doses, surpassing the efficacy of Copanlisib, without causing significant systemic toxicity, organ damage, or metabolic disturbances such as hyperglycemia. These results highlight TCCC-1 as a promising therapeutic candidate that leverages CMA for precise PI3K degradation, offering enhanced penetration and selectivity against tumors.