Division of Radiation Effects, Korea Institute of Radiological and Medical Sciences, Seoul 136-706, Korea.
Int J Radiat Oncol Biol Phys. 2011 May 1;80(1):221-30. doi: 10.1016/j.ijrobp.2010.11.069. Epub 2011 Feb 15.
Previous data suggest that the PKCδ catalytic V5 (PKCδ-V5) heptapeptide (HEPT) (FEQFLDI) binds HSP27 and blocks HSP27-mediated radio- or chemoresistance. Here we investigated further the in vivo function of the PKCδ-V5 HEPT.
Labeling of HEPT with Cy5.5 or fluorescein isothiocyanate was performed to evaluate in vitro or in vivo distribution of HEPT. A clonogenic survival assay, flow cytometry, and Western blotting of cleaved caspase-3 were performed to determine in vitro sensitization effects of HEPT plus ionizing radiation (IR) versus IR alone or those of HEPT plus cisplatin(Cis) versus Cis alone. A nude mouse xenografting system was also applied to detect in vivo sensitizing effects of HEPT.
HEPT efficiently bound to HSP27 and showed sensitization after combined treatment with IR versus treatment with Cis alone in NCI-H1299 lung carcinoma cells, with higher HSP27 expression, which was similar to that of combined treatment with IR or with Cis alone in NCI-H460 lung carcinoma cells with lower HSP27 expression. In vivo image analysis using Cy5.5-labeled HEPT showed that HEPT was retained in HSP27-overexpressing cancer cells after xenografting to nude mice. Combined treatment of HEPT with IR versus that with Cis alone in xenografted mice showed that HEPT increased radio- or chemosensitization in NCI-H1299 cells compared to that in mice xenografted with NCI-H460 cells.
The novel PKCδ-V5 HEPT may help overcome HSP27-mediated radio- or chemoresistance.
先前的数据表明，蛋白激酶 C δ 催化 V5（PKCδ-V5）七肽（HEPT）（FEQFLDI）与热休克蛋白 27（HSP27）结合并阻断 HSP27 介导的放射或化学耐药性。在这里，我们进一步研究了 PKCδ-V5 HEPT 的体内功能。
用 Cy5.5 或异硫氰酸荧光素标记 HEPT 以评估 HEPT 的体外或体内分布。通过克隆形成存活测定、流式细胞术和裂解的 caspase-3 的 Western blot 分析来确定 HEPT 加电离辐射（IR）与单独 IR 或 HEPT 加顺铂（Cis）与单独 Cis 相比的体外增敏作用。还应用裸鼠异种移植系统来检测 HEPT 的体内增敏作用。
HEPT 有效地与 HSP27 结合，并在 NCI-H1299 肺癌细胞中与单独 Cis 处理相比，在 HSP27 表达较高的情况下，与 IR 联合治疗或单独 Cis 治疗相比表现出增敏作用，NCI-H460 肺癌细胞中 HSP27 表达较低。使用 Cy5.5 标记的 HEPT 的体内图像分析表明，HEPT 在裸鼠异种移植后保留在 HSP27 过表达的癌细胞中。与单独 Cis 处理相比，在裸鼠异种移植中 HEPT 与 IR 的联合处理表明，与 NCI-H460 细胞异种移植的小鼠相比，HEPT 增加了 NCI-H1299 细胞的放射或化学增敏作用。
新型 PKCδ-V5 HEPT 可能有助于克服 HSP27 介导的放射或化学耐药性。
