Pittet Olivier, Petermann David, Michod David, Krueger Thorsten, Cheng Cai, Ris Hans-Beat, Widmann Christian
Division of Thoracic Surgery, University of Lausanne, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
J Photochem Photobiol B. 2007 Jul 27;88(1):29-35. doi: 10.1016/j.jphotobiol.2007.04.009. Epub 2007 May 1.
5,10,15,20-Tetrakis(m-hydroxyphenyl)chlorin (mTHPC)-mediated photodynamic therapy (PDT) has shown insufficient tumor selectivity for the treatment of pleural mesothelioma. Tumor selectivity of mTHPC-PDT may be enhanced in the presence of the TAT-RasGAP(317-326) peptide which has the potential to specifically sensitize tumor cells to cytostatic agents.
H-meso-1 and human fibroblast cell cultures, respectively, were exposed to two different mTHPC doses followed by light delivery with and without TAT-RasGAP(317-326) administration. mTHPC was added to the cultures at a concentration of 0.04microg/ml and 0.10microg/ml, respectively, 24h before laser light illumination at 652nm (3J/cm(2), 40mW/cm(2)). TAT-RasGAP(317-326) was added to the cultures immediately after light delivery at a concentration of 20microM. The apoptosis rate was determined by scoring the cells displaying pycnotic nuclei. Cell viability was measured by using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay.
Light delivery associated with 0.04microg/ml mTHPC resulted in a significantly higher apoptosis rate in the presence of TAT-RasGAP(317-326) than without in H-meso-1 cells (p<0.05) but not in fibroblasts. In contrast, 1.0microg/ml mTHPC and light resulted in a significantly higher apoptosis rate in both H-meso-1 cells and fibroblasts as compared to controls (p<0.05) but the addition of TAT-RasGAP(317-326) did not lead to a further significant increase of the apoptosis rate of both H-meso-1 cells and fibroblasts as compared to mTHPC and light delivery alone.
TAT-RasGAP(317-326) selectively enhanced the effect of mTHPC and light delivery on H-meso-1 cells but not on fibroblasts. However, this effect was mTHPC dose-dependent and occurred only at a low sensitizer dose.
5,10,15,20-四（间羟基苯基）二氢卟酚（mTHPC）介导的光动力疗法（PDT）在治疗胸膜间皮瘤时显示出肿瘤选择性不足。在存在TAT-RasGAP(317-326)肽的情况下，mTHPC-PDT的肿瘤选择性可能会增强，该肽有可能使肿瘤细胞对细胞生长抑制剂产生特异性敏感性。
分别将H-meso-1细胞和人成纤维细胞培养物暴露于两种不同剂量的mTHPC，然后在给予和不给予TAT-RasGAP(317-326)的情况下进行光照。在652nm（3J/cm²，40mW/cm²）激光照射前24小时，分别以0.04μg/ml和0.10μg/ml的浓度将mTHPC添加到培养物中。光照后立即以20μM的浓度将TAT-RasGAP(317-326)添加到培养物中。通过对显示固缩核的细胞进行评分来确定凋亡率。使用3-（4,5-二甲基噻唑-2-基）-2,5-二苯基溴化四氮唑（MTT）法测量细胞活力。
在H-meso-1细胞中，与0.04μg/ml mTHPC相关的光照在存在TAT-RasGAP(317-326)时导致的凋亡率显著高于不存在时（p<0.05），但在成纤维细胞中并非如此。相比之下，1.0μg/ml mTHPC和光照导致H-meso-1细胞和成纤维细胞中的凋亡率均显著高于对照组（p<0.05），但与单独的mTHPC和光照相比，添加TAT-RasGAP(317-326)并未导致H-meso-1细胞和成纤维细胞的凋亡率进一步显著增加。
TAT-RasGAP(317-326)选择性增强了mTHPC和光照对H-meso-1细胞的作用，但对成纤维细胞没有作用。然而，这种作用是mTHPC剂量依赖性的，并且仅在低敏化剂剂量下发生。
