In vivo study of photodynamic therapy using a new photosensitizer, 9-hydroxypheophorbide-a and 670 nm diode laser on HT-3 cervical cancer cell

Kim, Jong Soo

Abstract

OBJECTIVE
During the last several years, such as Photofrin(R), Photogem(R), HpD, and 5-aminolevulenic acid (ALA) has been used as photosensitizers for a wide range of malignant tumors as well as non-malignant disease. A new photosensitizer, 9-Hydroxypheophorbide-a (9-HpbD-a) was derived from Spirulina platensis. The aim of this study was to evaluate the anticancer effect and mechanism of photodynamic therapy in vivo using 9-HpbD-a and 670 nm diode laser on a HT-3 cervical cancer cell line.
METHODS
PDT effects were observed in xenograft nude mouse model. HT-3 cell line was xenografted into the subcutaneous space of the mouse back. When the tumors grew up to 400~500 mm3, the animals were randomly separated into 4 groups: Group I (n=5), control group; group II (n=10), 9-HpbD-a alone; group III (n=10), laser irradiation alone; and group IV (n=20), PDT in nude mouse group.
RESULTS
PDT treated group (9-HpbD-a+laser irradiation) showed complete response (15/20, 75%), recurrence (3/20, 15%) or no response (2/20, 10%). PDT group showed significant remission rate, comparing to laser irradiation alone group, 9-HpbD-a alone group and untreated control group (P<0.05). When PDT using 9-HpbD-a, tumor size was decrease and microscopically finding, antitumor effect was showed inflammation and necrosis of tumor cell. Overexpression of p53 and Ki-67 gene had been detected at the HT-3 cervical cancer cell and 10 days after PDT. And no experssion in normal tissue and tumor after PDT. So, immunohistochemical study of p53 and Ki-67 gene correlated with PDT for anticancer effect.
CONCLUSION
These results suggest that 9-HpbD-a is one of the promising photosensitizers for the future and would be needed to use 9-HpbD-a as a photosensitizer in clinical setting. We would further suggest that photodynamic therapy is a more effective method than the conventional treatment for women who want to maintain their anatomical and functional uterine cervix.