Research projects

In 2006, research focused largely on mechanistic studies as follows:

PDT-induced tissue hypoxia as a result of vascular damage and photochemical oxygen consumption limits the efficacy of this modality. This may largely be due to hypoxia-mediated angiogenesis via hypoxia-inducible factor-1 (HIF-1), a major transcription factor involved in angiogenesis, hematopoiesis and anaerobic energy metabolism.

High expression of HIF-1 induced in vitro by cobalt chloride (CoCl2)-mediated chemical hypoxia mimic was seen in the Het-1A cell line. The CoCl2-treated cells were more resistant to PDT than those without CoCl2 treatment. The photosensitivity of the cells to PDT decreased with increasing HIF-1 expression by enhancing CoCl2 concentrations. Moreover, transfection of the cells with anti-HIF-1 short interfering RNA (siRNA) knocked down the HIF-1 expression and restored the photosensitivity of the cells to PDT.

The finding suggests that PDT in combination with anti-HIF-1 treatment may enhance the PDT efficacy.