Chrysin and chrysin-loaded nanocarriers induced immunogenic cell death on B16 melanoma cells

Induction of immunogenic cell death (ICD) is a promising strategy for cancer immunotherapy. Chrysin, which has potential anticancer effects, faces limitations in clinical applications due to its poor water solubility. This study aimed to formulate chrysin with PEG-poly(α-benzylcarboxylate-ε-caprolactone) (PBCL) nanoparticles (NPs) and assess their anticancer and ICD-inducing potency in melanoma cells, comparing with free chrysin. The co-solvent evaporation method was employed to develop chrysin-loaded NPs. UV spectroscopy, dynamic light scattering, and the dialysis bag method were used to evaluate the encapsulation efficiency (EE), particle size, polydispersity index (PDI), and drug release profile, respectively. The anticancer effects of the drugs were assessed using the MTT and trypan blue exclusion assays. Flow cytometry was employed to evaluate apoptosis and calreticulin (CRT) expression. ELISA and western blotting were used to detect heat shock protein 90 (HSP90), Annexin A1, GRP78 (Glucose-related protein78), and activated protein kinase R-like endoplasmic reticulum kinase (p-PERK). Chrysin-loaded PEG-PBCL NPs (chrysin-PEG-PBCL) showed an EE of 97 ± 1%. Chrysin-PEG-PBCL was 38.18 ± 3.96 nm in size, with a PDI being 0.62 ± 0.23. Chrysin-PEG-PBCL showed an initial burst release, followed by sustained release over 24 h. Chrysin-PEG-PBCL exhibited a significantly stronger anticancer effect in B16 cells. Chrysin-PEG-PBCL was found to be more potent in inducing apoptosis. Both free chrysin and chrysin NPs induced ICD as indicated by an increase in the levels of ICD biomarkers. Interestingly, chrysin NPs were found to be more potent inducers of ICD than the free drug. These findings demonstrate that chrysin and chrysin-PEG-PBCL NPs can induce ICD in B16 cells. PEG-PBCL NPs significantly enhanced the potency of chrysin in inducing ICD compared to its free form.