Abstract
Background: Nasopharyngeal carcinoma (NPC) is mainly treated with chemo-radiotherapy but treatment failure was associated with drug resistance. Photodynamic therapy (PDT) is an anti-tumor treatment that combines photosensitiser (PS), visible light and molecular oxygen to induce reactive oxygen species for tumor eradication. However, limited supply of oxygen and PS in cell during light activation restricted PDT effect. Fractionated light irradiation might overcome this restriction, yet there is lacking information on the effect of fractionated light irradiation on Foslip® PDT. Therefore, in this study, effect of fractionated light irradiation on Foslip® was evaluated using C666-1 cells.
Methods: The uptake and cytotoxicity of PS was analysed using flow cytometry and MTT assay. 3 x 104 cells were seeded 24 hours and incubated with 4 hours PS, followed with a single light irradiation or with a fractionated light irradiation at 1, 2 and 4 hours intervals at total energy of 4J/cm2. Cells were incubated with 1/10 concentration of PSs suspended in RPMI-1640 in darkness for fractionated light intervals to mimic the PS concentration in the tissue microenvironment.
Results: Results revealed that the uptake of Foslip® was optimum at 4 hours in C666- 1 cells. Foslip® PDT was effective to C666-1 cells, with drug and light dose dependent manners. IC30 and IC70 were achieved at 0.05mg/mL and 0.5mg/mL Foslip® with 4J/ cm2 respectively. Fractionated light irradiation with a 2 hours interval significantly enhanced the IC from IC30 to IC50. However, no difference were observed between 2 hours and 4 hours interval, indicated that 2 hours might be enough for oxygen and PS replenished in cells.
Conclusion: Fractionated light irradiation with 2 hours interval significantly enhanced PDT effect on C666-1 cells. Further investigation is needed on the mechanisms of fractionated light irradiation activated PDT in NPC cells. Acknowledgments: We thank Biolitec provided Foslip® for this study.
Methods: The uptake and cytotoxicity of PS was analysed using flow cytometry and MTT assay. 3 x 104 cells were seeded 24 hours and incubated with 4 hours PS, followed with a single light irradiation or with a fractionated light irradiation at 1, 2 and 4 hours intervals at total energy of 4J/cm2. Cells were incubated with 1/10 concentration of PSs suspended in RPMI-1640 in darkness for fractionated light intervals to mimic the PS concentration in the tissue microenvironment.
Results: Results revealed that the uptake of Foslip® was optimum at 4 hours in C666- 1 cells. Foslip® PDT was effective to C666-1 cells, with drug and light dose dependent manners. IC30 and IC70 were achieved at 0.05mg/mL and 0.5mg/mL Foslip® with 4J/ cm2 respectively. Fractionated light irradiation with a 2 hours interval significantly enhanced the IC from IC30 to IC50. However, no difference were observed between 2 hours and 4 hours interval, indicated that 2 hours might be enough for oxygen and PS replenished in cells.
Conclusion: Fractionated light irradiation with 2 hours interval significantly enhanced PDT effect on C666-1 cells. Further investigation is needed on the mechanisms of fractionated light irradiation activated PDT in NPC cells. Acknowledgments: We thank Biolitec provided Foslip® for this study.
| Original language | English |
|---|---|
| Pages (from-to) | S339 |
| Number of pages | 1 |
| Journal | Annals of Oncology |
| Volume | 32 |
| Issue number | Supplement 4 |
| Early online date | 26 Jul 2021 |
| DOIs | |
| Publication status | Published - Jul 2021 |
| Externally published | Yes |
| Event | Virtual Congress 2021 the Japanese Society of Medical Oncology Annual Meeting - Online Duration: 18 Feb 2021 → 21 Feb 2021 http://www.congre.co.jp/jsmo2021/en/greeting/index.html (Link to conference website) |