Background: Although Delta-like ligand 3 (DLL3)-targeted therapies have shown promise for lung cancer, limited information is available regarding recombinant immunotoxins using Granzyme B as the cytotoxic moiety.
Objectives: This study evaluated the effects of the recombinant immunotoxin named, Rovaliptuzumab-Granzyme B, on apoptosis in the lung cancer cell line A549.
Methods: The A549 lung cancer cell line was treated with three different concentrations (150, 350 and 700 nanomolar (nM)) of Rovaliptuzumab-Granzyme B. Lactate dehydrogenase (LDH) activity assay was performed to measure cell membrane integrity and cytotoxicity. In addition, the activation of caspases 3/7 was studied as markers of apoptosis. Quantitative real-time PCR was evaluated to quantify the expression levels of BAX and BCL-2 genes.
Results: Our data show that Rovaliptuzumab-Granzyme B, at all studied concentrations (150, 350, and 700 nM), significantly causes cytotoxicity in A549 cells, as characterized by increased LDH release (48, 120, 206.8%, respectively), increased caspase activity (0.77, 1.33 and 2.34 nmol/min/mL, respectively), and enhances in the BAX/BCL-2 gene expression ratio compared to negative control (.97, 2.68 and 4.03, respectively) (P<0.05). In addition, the BCL-2 gene expression showed 0.74, 0.67 and 0.58-fold decrease at a concentration of 150, 350, and 700 nM, respectively, while 1.48, 1.8, 2.34-fold increase in BAX gene expression was seen at a concentration of 150, 350, and 700 nM, respectively, compared to negative control (P<0.05).
Conclusion: Overall, these findings suggest that the recombinant Rovalpituzumab/Granzyme B immunotoxin exerts pro-apoptotic activity in A549 lung cancer cells.