Enhanced Caspase-Mediated Abrogation of Autophagy by Temozolomide-Loaded and Panitumumab-Conjugated Poly(lactic--glycolic acid) Nanoparticles in Epidermal Growth Factor Receptor Overexpressing Glioblastoma Cells.

The mechanism of cell death has attracted a great deal of research interest in the design of antitumor therapy in recent days. Several attempts have been carried out in this direction and in our study also, we studied this phenomenon with the design of panitumumab (PmAb)-conjugated and temozolomide (TMZ)-loaded poly(lactic--glycolic acid) nanoparticles (PLGA-NPs), termed PmAb-TMZ-PLGA-NPs. First, PmAb was functionalized on the surface of TMZ-PLGA-NPs using ethyl(dimethylaminopropyl)carbodiimide (EDC)--hydroxysuccinimide (NHS) chemistry. Targeted PLGA-NPs significantly enhanced the cellular uptake of nanoparticles in the U-87 MG cell line as a result of the high epidermal growth factor receptor (EGFR) expression, compared to the LN229 cell line. Our study demonstrated that following the treatment of PmAb-TMZ-PLGA-NPs, a more pronounced anticancer effect was noticed in comparison with free TMZ and TMZ-PLGA-NPs. Further, a more pronounced cytotoxic effect of PmAb-TMZ-PLGA-NPs was observed in the high EGFR-overexpressed glioblastoma multiforme (GBM) model (U-87 MG) cell line compared to the low EGFR GBM model (LN229). Our study demonstrated that the treatment of PmAb-TMZ-PLGA-NPs in GBM tried to adopt the autophagic pathway of the cell survival mechanism with the elevated level of autophagic marker (Beclin-1 and LC3B) at 24 h time point, thereby suppressing the expression of caspase-9 and PARP. However, at the 48 h time point, the elevated expression of caspase-9 and PARP with the downregulation of Beclin-1 and LC3B, following the treatment of PmAb-TMZ-PLGA-NPs in the GBM model, suggested that apoptotic cell death was superior over autophagic cell survival. It was also noteworthy the activation of caspase-9 was correlated with the continuous overproduction of reactive oxygen species up to a 48 h time point after the treatment of PmAb-TMZ-PLGA-NPs. This result sheds light on the biological effect of targeted chemotherapy and illustrates that PmAb-TMZ-PLGA-NPs could be applied for EGFR-overexpressed different cancer models.