Photodynamic therapy-mediated modulation of inflammatory cytokine production by Epstein-Barr virus-infected nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a malignant disease associated with Epstein-Barr virus (EBV) infection. This study aims to examine the effects of EBV infection on the production of proinflammatory cytokines in NPC cells after the Zn-BC-AM photodynamic therapy (PDT) treatment. Cells were treated with the photosensitiser Zn-BC-AM for 24 h before light irradiation. Quantitative ELISA was used to evaluate the production of cytokines. Under the same experimental condition, HK-1-EBV cells produced a higher basal level of IL-1α (1561 pg/ml), IL-1Β (16.6 pg/ml) and IL-8 (422.9 pg/ml) than the HK-1 cells. At the light dose of 0.25-0.5 J/cm 2, Zn-BC-AM PDT-treated HK-1-EBV cells were found to produce a higher level of IL-1α and IL-1Β than the HK-1 cells. The production of IL-1Β appeared to be mediated via the IL-1Β-converting enzyme (ICE)-independent pathway. In contrast, the production of angiogenic IL-8 was downregulated in both HK-1 and HK-1-EBV cells after Zn-BC-AM PDT. Our results suggest that Zn-BC-AM PDT might indirectly reduce tumour growth through the modulation of cytokine production.