Kamuhabwa Appolinary A R, Huygens Ann, De Witte Peter A M
Laboratorium voor Farmaceutische Biologie en Fytofarmacologie, Faculteit Farmaceutische Wetenschappen, Katholieke Universiteit Leuven, Belgium.
Int J Oncol. 2003 Nov;23(5):1445-50.
The objective of the present study was to evaluate the sensitivity of the bladder transitional cell carcinoma (TCC) to hypericin PDT in a 3-D system using multicellular tumor spheroids. The photodynamic response in RT-112 human bladder TCC spheroids was also compared to 2-D cultured monolayer cells. Following a 2-4 h incubation with 8-30 microM hypericin, spheroids or monolayer cells were irradiated at the light dose of 12 J/cm2, delivered at a fluence rate of 10-100 mW/cm2. The PDT effects were evaluated using a clonogenic assay. The results show that compared with the cells in a monolayer, cells in spheroids were dramatically less sensitive to hypericin PDT (<2000-fold). Studies of fluorescence microphotographs of centrally cut frozen sections of hypericin-exposed spheroids showed a gradient in hypericin concentration from the peripheral to the central region of the spheroid. Although it can be suggested that heterogeneity of drug uptake might be responsible for the observed resistance of spheroid to hypericin PDT, hypericin sensitized spheroids that were dissociated prior to light irradiation were as sensitive as the monolayer cells to hypericin PDT, suggesting that other factors such as oxygen depletion might be responsible for the resistance of spheroids to hypericin PDT.
本研究的目的是在三维系统中使用多细胞肿瘤球体评估膀胱移行细胞癌（TCC）对金丝桃素光动力疗法（PDT）的敏感性。还将RT-112人膀胱TCC球体中的光动力反应与二维培养的单层细胞进行了比较。在用8-30 microM金丝桃素孵育2-4小时后，以10-100 mW/cm2的通量率给予12 J/cm2的光剂量照射球体或单层细胞。使用克隆形成试验评估PDT效果。结果表明，与单层细胞相比，球体中的细胞对金丝桃素PDT的敏感性显著降低（<2000倍）。对暴露于金丝桃素的球体中心切割冰冻切片的荧光显微照片研究表明，从球体的周边到中心区域，金丝桃素浓度存在梯度。尽管可以认为药物摄取的异质性可能是观察到的球体对金丝桃素PDT耐药的原因，但在光照前解离的金丝桃素致敏球体对金丝桃素PDT的敏感性与单层细胞一样，这表明其他因素如氧耗竭可能是球体对金丝桃素PDT耐药的原因。
