Hu Meiduo, Scollard Deborah, Chan Conrad, Chen Paul, Vallis Katherine, Reilly Raymond M
Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada M5S 3M2.
Nucl Med Biol. 2007 Nov;34(8):887-96. doi: 10.1016/j.nucmedbio.2007.06.010. Epub 2007 Sep 4.
Our objective was to evaluate the effect of epidermal growth factor receptor(s) (EGFR) density on the importation and nuclear localization of 111In-labeled diethylenetriaminepentaacetic acid human epidermal growth factor ([111In]DTPA-hEGF) in breast cancer (BC) cells in vitro and in tumor xenografts and normal tissues in vivo in athymic mice, as well as on its cytotoxicity and tumor and normal-tissue distribution.
The internalization and nuclear importation of [111In]DTPA-hEGF were measured in MCF-7, MDA-MB-231, BT-474 and MDA-MB-468 BC cells (10(4), 2 x 10(5), 6 x 10(5) and 10(6) EGFR/cell, respectively). The molecular size (Mr) distribution and immunoreactivity of nuclear radioactivity were characterized. Tumor and normal-tissue uptake of [111In]DTPA-hEGF in athymic mice implanted subcutaneously with BC xenografts were compared. Nuclear radioactivity in the tumor, lungs, liver, kidneys, spleen and colon was measured.
There was a direct association between EGFR density and the nuclear localization of [111In]DTPA-hEGF in BC cells; nuclear importation approached saturation at 6 x 10(5) EGFR/cell. Almost all nuclear radioactivities exhibited an Mr of >100 kDa; immunoreactivity with anti-hEGF, anti-EGFR and anti-importin beta 1 antibodies was detected. The efflux of nuclear radioactivity was slowest for MDA-MB-468 cells. Cytotoxicity was correlated with EGFR expression. Uptake was greater in MDA-MB-468 than in MCF-7 xenografts and improved with preinjection of a 100-fold excess of unlabeled DTPA-hEGF. Nuclear importation was higher in liver, kidney and spleen cells than in tumor cells.
[111In]DTPA-hEGF is translocated to the nucleus of BC cells complexed with EGFR and importin beta1. Nuclear importation and cytotoxicity are effected by EGFR density. The absence of hepatic and renal toxicities in [111In]DTPA-hEGF cannot be explained by a low efficiency of nuclear importation.
我们的目的是评估表皮生长因子受体（EGFR）密度对体外乳腺癌（BC）细胞、无胸腺小鼠体内肿瘤异种移植瘤及正常组织中111In标记的二乙三胺五乙酸人表皮生长因子（[111In]DTPA-hEGF）的摄取及核定位的影响，以及对其细胞毒性和肿瘤及正常组织分布的影响。
在MCF-7、MDA-MB-231、BT-474和MDA-MB-468 BC细胞（分别为10⁴、2×10⁵、6×10⁵和10⁶个EGFR/细胞）中测量[111In]DTPA-hEGF的内化及核摄取。对核放射性的分子大小（Mr）分布及免疫反应性进行了表征。比较了皮下接种BC异种移植瘤的无胸腺小鼠中[111In]DTPA-hEGF在肿瘤及正常组织中的摄取情况。测量了肿瘤、肺、肝、肾、脾和结肠中的核放射性。
BC细胞中EGFR密度与[111In]DTPA-hEGF的核定位之间存在直接关联；在6×10⁵个EGFR/细胞时核摄取接近饱和。几乎所有核放射性物质的Mr均>100 kDa；检测到与抗hEGF、抗EGFR和抗输入蛋白β1抗体的免疫反应性。MDA-MB-468细胞的核放射性流出最慢。细胞毒性与EGFR表达相关。MDA-MB-468异种移植瘤中的摄取高于MCF-7异种移植瘤，且预先注射100倍过量的未标记DTPA-hEGF后摄取增加。肝、肾和脾细胞中的核摄取高于肿瘤细胞。
[111In]DTPA-hEGF与EGFR和输入蛋白β1复合后转运至BC细胞核。核摄取及细胞毒性受EGFR密度影响。[111In]DTPA-hEGF不存在肝毒性和肾毒性不能用核摄取效率低来解释。
