Antitumour Effects of Human Antithymocyte Alobulin on Peripheral-T Cell Lymphoma Via Complement-Dependent and -Independent Cytotoxicity in Xenograft Mouse Models

Background

Peripheral T-cell lymphomas (PTCL) is a group of non-Hodgkin lymphomas characterised by substantial molecular heterogeneity, rapid progression, poor therapeutic response, and unfavourable outcomes. In recent clinical studies, antithymocyte globulin (ATG)-based allogeneic-haematopoietic stem cell transplantation (allo-HSCT) has markedly improved the prognosis and survival of patients with PTCL. This study aimed to explore whether ATG has toxic effects on PTCL cells and evaluate whether ATG combined with chemotherapy has a synergistic antitumour effect.

Methods

The cytotoxicity and proliferative effects of ATG were tested with the CCK-8 assay and verified using the cell colony formation assay in Hut78, Karpas299, and SU-DHL-1 cell lines. After propidium iodide (PI) staining, the proportion of cells at different cell cycle stages was measured using flow cytometry to determine the impact of ATG on the cell cycle. Transwell assays were performed to examine the effect of ATG on PTCL cell invasion. The apoptotic effects induced by ATG in PTCL cells were evaluated from three aspects, including fluorescein isothiocyante annexin-V/PI detection, mitochondrial membrane potential (∆Ψm) analysis with JC-1, and apoptosis-specific morphological changes. BALB/C-nu/nu mice were used to establish a PTCL cell-induced subcutaneous tumour model to investigate the chemotherapeutic effect of ATG and its synergistic effect with anthracycline.

Results

ATG significantly inhibited PTCL cell growth by suppressing cell proliferation and colony formation. Moreover, ATG treatment decreased cell invasion; however it had no effect on cell cycle arrest in PTCL cells. ATG induced PTCL cell apoptosis, which was partially reversed by pan-caspase inhibitor and caspase 8 inhibitor. Additionally, ATG was able to induce complement-dependent cytotoxicity in PTCL cells. Most importantly, the combination of ATG and doxorubicin exhibited enhanced effectiveness against PTCL cells both in vitro and in vivo, suggesting that ATG can exert a synergistic antitumour effect when administered with doxorubicin.

Conclusion

ATG can exert cytotoxic effects in PTCL cells by activating the caspase-dependent apoptotic pathway and complement-dependent cytotoxicity and can exert a synergistic antitumour effect when combined with traditional anthracyclines in vitro and in vivo. This study provides a scientific basis for the clinical application of ATG for PTCL treatment.

No relevant conflicts of interest to declare.