Combination doxorubicin and interferon-α therapy stimulates immunogenicity of murine pancreatic cancer Panc02 cells via up-regulation of NKG2D ligands and MHC class I.

BACKGROUND

Pancreatic adenocarcinoma is a malignant gastrointestinal cancer with significant morbidity and mortality. Despite severe side effects of chemotherapy, the use of immunotherapy combined with chemotherapy has emerged as a common clinical treatment. In this study, we investigated the efficacy of the combined doxorubicin and interferon-α (IFN-α) therapy on murine pancreatic cancer Panc02 cells in vitro and in vivo and underlying mechanisms.

MATERIALS AND METHODS

A Panc02-bearing mouse model was established to determine whether doxorubicin and interferon-α (IFN-α) could effectively inhibit tumor growth in vivo. Cytotoxicity of natural killer (NK) cells and cytotoxic T lymphocytes (CTLs) was evaluated using a standard LDH release assay. To evaluate the relevance of NK cells and CD8 T cells to the combination therapy-mediated anti-tumor effects, they were depleted in tumor-bearing mice by injecting anti-asialo-GM-1 antibodies or anti-CD8 antibodies, respectively. Finally, the influence of doxorubicin+interferon-α (IFN-α) on the ligands of NK and T cells was assessed by flow cytometry.

RESULTS

The combination therapy group demonstrated a significant inhibition of growth of Panc02 in vivo, resulting from activated cytotoxicity of NK cells and CTLs. Depleting CD8 T cells or NK cells reduced the anticancer effects mediated by immunochemotherapy. Furthermore, the doxorubicin+IFN-a treatment increased the expression of major histocompatibility complex class I (MHC I) and NKG2D ligands on Panc02 cells, suggesting that the combined therapy may be a potential strategy for enhancing immunogenicity of tumors. All these data indicate that the combination therapy using doxorubicin and interferon-α (IFN-α) may be a potential strategy for treating pancreatic adenocarcinoma.