Singlet oxygen (1O2) generated by ultraviolet A irradiation has been reported to induce cytokine-dependent Matrix metalloproteinase-1 (MMP-1) expression in dermal fibroblasts. In the present study, we analyzed the effect of hypericin-based photodynamic therapy (PDT) on MMP-1 expression in two nasopharyngeal cancer (NPC) cell lines and an animal tumor model. MMP-1 protein and mRNA expression were evaluated by Western blot analysis and quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) respectively. Photoactivation of hypericin, a polycyclic phenanthroperylenedione, elicited an increase in MMP-1 protein and mRNA expression in well differentiated HK1 and poorly differentiated CNE-2 NPC cells in vitro. Similarly, there was up-regulation of MMP1 mRNA expression in hypericin-PDT-treated NPC/HK1-tumors. To our knowledge, this is the first time that modulation of MMP-1 expression has been demonstrated as a photodynamic effect of hypericin in NPC cells. This has clinical implications as MMP-1 is known to play an essential role in the biological process of matrix remodeling.

Related Articles