Chitosan gold nanogel containing Rova-Typhoid immunotoxins against the DLL3 receptor has a promising effect on small-cell lung cancer.

SCLC (small-cell lung cancer) is hardly treated with chemotherapy alone, even though it was initially sensitive to the drug. A novel therapeutic combination for treating diseases that have resisted typical first-line treatments is available with immunotoxin-based anticancer medicines. The use of delta-like ligand 3 (DLL3) in target treatment has potential because of the high expression of DLL3 in patients with SCLC. Nanoparticles are gaining popularity in developing new therapeutics, with gold nanoparticles (AuNPs) being investigated as potential cancer treatments. Emerging evidence indicates that AuNPs stabilized with chitosan (CS) have interesting biological functions. Therefore, in this study, we aimed to synthesize chitosan nanogel to deliver Rova-Typhoid immunotoxins to target cancer cells. In this research, we synthesized CS-AuNPs and CS-Rova-Typh-AuNPs and analyzed their cytotoxicity in small-cell lung (A549) cancer cells and HUVEC cell lines. Then, we evaluated the inhibitory concentration (IC50), cell cycle, and mRNA expression. Free AuNPs did not show cytotoxic effects on our cell lines; however, the inhibitory concentration of Rova-Typh immunotoxin is reduced when loaded into CS-AuNPs. Besides, immunotoxin-loaded nanogel induces late apoptosis in A549 cells and effectively induces sub-G1 cell arrest. Moreover, immunotoxin-loaded nanogel causes downregulation in DLL3, HES1, and NOTCH1 genes, which are involved in the Notch signaling pathway. Our results indicate that CS-AuNPs were an effective Rova-Typh delivery means, and Rova-Typhoid immunotoxin induces apoptosis in cancer cells through inhibiting DLL3, which is a Notch signaling ligand.