Enhanced cellular uptake by non-endocytic pathway for tumor therapy

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Drug Delivery

Background:

• Endosomal and lysosomal pathways pose a significant barrier to effective intracellular drug delivery, often leading to therapeutic inactivation.
• Overcoming endo/lysosomal trapping is crucial for improving the efficacy of anticancer drugs and other therapeutic agents.
• N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers offer a versatile platform for drug conjugation and delivery.

Purpose of the Study:

• To develop a novel HPMA copolymer conjugate system for efficient intracellular delivery of anticancer drugs, bypassing endosomal entrapment.
• To evaluate the efficacy of a CLIP6 peptide-modified HPMA copolymer conjugate loaded with doxorubicin (DOX) for cancer therapy.
• To assess the in vitro and in vivo therapeutic potential and toxicity of the developed drug delivery system.

Main Methods:

• Covalent grafting of CLIP6 peptide and doxorubicin (DOX) onto an N-(2-hydroxypropyl)methacrylamide (HPMA) backbone to create P-DOX-CLIP6 conjugates.
• Assessment of cellular uptake and intracellular trafficking of the conjugates using cell culture models.
• Evaluation of antiproliferative and anti-tumor effects on 3D tumor spheroids and in a HeLa tumor-bearing mouse model.
• Analysis of systemic toxicity associated with the P-DOX-CLIP6 treatment.

Main Results:

• CLIP6 peptide modification significantly enhanced the cellular uptake of DOX-loaded HPMA copolymers.
• The P-DOX-CLIP6 conjugate effectively reduced lysosomal accumulation of the drug, promoting cytoplasmic delivery.
• Enhanced proliferation inhibition and superior growth inhibition were observed in 3D tumor spheroids compared to unmodified conjugates.
• P-CLIP6-DOX demonstrated high therapeutic efficacy in vivo in HeLa tumor-bearing nude mice with no significant systemic toxicity.

Conclusions:

• HPMA copolymer-based drug delivery systems functionalized with CLIP6 peptide represent a promising strategy to overcome endo/lysosomal trapping.
• This approach enables efficient cytoplasmic delivery of therapeutic agents, enhancing anticancer efficacy.
• The developed P-CLIP6-DOX conjugate offers a safe and effective therapeutic option for cancer treatment, warranting further investigation.