PH responsive hydrogel nanocomposites for targeted Shikonin delivery enhance anti PDL1 immunotherapy in osteosarcoma

To enhance the therapeutic effect of atezolizumab on osteosarcoma (OS) by constructing a pH-responsive hydrogel nanocomplex (Gel@PLGA@FA) as a delivery platform for Shikonin.

First, Shikonin was initially employed to analyze the GSE14359 dataset, leading to the identification of 28 differentially expressed genes (DEGs). Based on this, a risk score model was constructed and molecular dynamics simulations were performed to assess the binding ability between Shikonin and cyclin-dependent kinase 1 (CDK1). In addition, the in vitro antiproliferative effect of Shikonin on MG63 and Saos-2 OS cell lines and its selective toxicity on normal cells were assessed. In order to overcome the disadvantages of poor water solubility and normal cytotoxicity towards Shikonin, a complex loaded with Shikonin by pH-responsive intelligent hydrogel nanomaterials was synthesized and its anti-programmed death ligand-1 (PD-L1) therapeutic effect on OS cells was evaluated.

Molecular dynamics simulation showed that Shikonin showed strong binding ability to CDK1, showing stable conformation, enhanced structural stability and other characteristics. In vitro experiments showed that Shikonin had a significant anti-proliferative effect on OS cells, while it had selective toxicity on normal liver, kidney and osteoblasts. The pH-responsive hydrogel nanomaterial (Gel@PLGA@FA) loaded with Shikonin showed good drug release characteristics at different pH conditions, especially in the tumor microenvironment to achieve controllable drug release. Combined use of Gel@PLGA@Shikonin@FA and atezolizumab effectively down-regulated CDK1 and PD-L1 expression, inhibited cell proliferation and promoted apoptosis, significantly enhancing the anti-PD-L1 therapeutic effect on OS cells. JC-1 staining experiments further confirmed that this combination therapy could perturb mitochondrial membrane potential and lead to stronger apoptosis.

This study reveals the unique mechanism of action of Shikonin as a potential anticancer drug and demonstrates the potential of pH-responsive hydrogel nanomaterials as efficient and safe delivery systems for targeted cancer therapeutics. The strategy of Gel@PLGA@Shikonin@FA combined with atezolizumab provides a new idea and experimental basis for OS treatment.