In vitro evidence of HER2-selective cytotoxicity by scFv(Herceptin)-PE-STXA immunotoxin in gastric cancer cells

The delivery of therapeutic agents in a targeted manner shows great potential for improving the degree of efficacy in cancer therapies by minimizing harm for normal tissues and reducing treatment-related complications. Among patients with gastric cancer, the HER2 receptor is expressed in approximately 10-30 % of cases. The scFv(Herceptin)-PE-STXA was cloned into the pET28a vector, followed by protein expression and purification. HEK-293 cells served as the control (HER2-negative), while NCI-N87 cells were utilized as the gastric cancer cells (HER2-positive). The cells were subjected to exposure different concentrations (35 and 50 μg/mL) of immunotoxin, after which growth was assessed using the MTT test. The capability of scFv(Herceptin)-PE-STXA to induce apoptotic pathway in NCI-N87 and HEK-293 cells was estimated through flow cytometry. Furthermore, the affinity for binding the IT, lactate dehydrogenase release, and the measurement of apoptosis pathway enzymes (caspase-9 and caspase-3 activities) were also conducted. The outcomes demonstrated that cytotoxic effects occurred in NCI-N87 cells with a dose-proportional manner approach, whereas no such impact was seen in HEK-293(P < 0.001). Flow cytometry analysis of NCI-N87 cells treated with scFv(Herceptin)-PE-STXA revealed a significant increase in apoptotic rate at dose of 35 and 50 μg/mL (55.6 % and 74.2 %). Additional analysis showed that exposing HER2-expressing NCI-N87 cells to the scFv(Herceptin)-PE-STXA caused a notable to enhance in apoptotic caspases activity (3 and 9) (P < 0.001). Results of our study indicated that the scFv(Herceptin)-PE-STXA induces apoptosis in the NCI-N87 cell line derived from gastric cancer. This study emphasizes the potential of scFv(Herceptin)-PE-STXA to specifically target HER2-expressing cancer cells.