Abstract / Summary
Introduction: Despite widespread use, chemotherapy often leads to adverse effects and resistance. Hydroxyurea (HU) is commonly used in combination with other chemotherapeutic agents. Efforts have been made to enhance its efficacy and reduce associated toxicity. Combination therapy appears to be the most effective approach for targeting cancer cells through multiple mechanisms. Newcastle disease virus (NDV) has recently been investigated as a potential cancer therapy. This is the first study to evaluate the combined cytotoxicity of NDV and HU in HepG2 cells.
Materials and methods: The effects of the nonvirulent oncolytic LaSota strain of NDV and HU (alone and in combination) on human liver cancer cells were assessed using MTT, annexin/PI, AO/EtBr staining, scratch and transwell assays, colony formation, quantitative real-time PCR, and Western blot for gene and protein expression. The combination results were analyzed using the Chou-Talalay method.
Results: The combination of HU and NDV at IC30 doses resulted in approximately 65%-70% cell death, which is significantly greater than that observed with either monotherapy (p = 0.0006). The annexin V/PI assay showed that the combination induced 36.8% apoptosis, whereas monotherapy with HU or NDV induced only about 17% (p < 0.05). Cell migration was significantly impeded in all treated groups, with the combination resulting in a 65% decrease in migration relative to the control (p = 0.009). With HU + NDV, colony formation was reduced by about 60%, and with HU alone, it was reduced by about 43% (p = 0.0005). The mRNA expression of VEGF-A was markedly diminished in all treated groups; but, on the contrary, the cleaved caspase 9 was boosted at the protein level. These data collectively confirm a synergistic inhibitory effect on the proliferation, migration, and survival of HepG2 cells.
Conclusion: The combination of the common chemotherapeutic agent HU with the nonpathogenic LaSota strain of NDV as virotherapy showed a synergistic effect on HepG2 cells in vitro. The results suggest a possible therapeutic benefit by suppressing cancer cell proliferation, inhibiting growth, and inducing cell death. However, these results are restricted to in vitro tests and may not fully represent the complexity of liver cancer in humans; additional in vivo research is required to assess the approach's safety and clinical applicability. Additionally, this combination might serve as a foundation for further research on multidrug resistance.