Preparation and Evaluation of 99mTc-Epidermal Growth Factor Receptor (EGFR)-Peptide Nucleic Acid for Visualization of EGFR Messenger RNA Expression in Malignant Tumors

Journal of Nuclear Medicine

Xinming Zhao¹  Jingmian Zhang¹  Jingya Han¹  Yunuan Liu¹  Jianfang Wang¹  Na Wang¹  Xiuchun Ren¹  Lizhuo Jia¹  Zhaoqi Zhang¹ 

[1] Department of Nuclear Medicine, the Fourth Hospital of Hebei Medical University, Shijiazhuang, China Department of Nuclear Medicine, the Fourth Hospital of Hebei Medical University, Shijiazhuang, China Department of Nuclear Medicine, the Fourth Hospital of Hebei Medical University, Shijiazhuang, China

关键词: peptide nucleic acid;    ^99mTc;    molecular imaging;    EGFR;    malignant tumors;   

DOI  :  10.2967/jnumed.113.136101

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

Epidermal growth factor receptor (EGFR) is overexpressed in many carcinomas and remains a prime target for diagnostic and therapeutic applications. There is a need to develop noninvasive methods to identify the subset of patients that is most likely to benefit from EGFR-targeted treatment. Noninvasive imaging of EGFR messenger RNA (mRNA) expression may be a useful approach. The aim of this study was to develop a method for preparation of single-photon-emitting probes, 99mTc-labeled EGFR mRNA antisense peptide nucleic acid (PNA) (99mTc-EGFR-PNA), and nontargeting control (99mTc-CTL-PNA) and to evaluate their feasibility for imaging EGFR mRNA overexpression in malignant tumors in vivo. Methods: On the 5′ terminus of synthesized single-stranded 17-mer antisense EGFR mRNA antisense PNA and mismatched PNA, a 4-amino-acid (Gly-(D)-Ala-Gly-Gly) linker forming an N4 structure was used for coupling 99mTc. Probes were labeled with 99mTc by ligand exchange. The radiochemical purity of these 99mTc-labeled probes was determined by reversed-phase high-performance liquid chromatography. Cellular uptake, retention, binding specificity, and stability of the probes were studied either in vitro or in vivo. Biodistribution and radionuclide imaging were performed in BALB/c nude mice bearing SKOV3 (EGFR-positive) or MDA-MB-435S (EGFR-negative) carcinoma xenografts, respectively. Results: The average labeling efficiencies of 99mTc-EGFR-PNA and 99mTc-CTL-PNA were 98.80% ± 1.14% and 98.63% ± 1.36% (mean ± SD, n = 6), respectively, within 6 h at room temperature, and the radiochemical purity of the probes was higher than 95%. 99mTc-EGFR-PNA was highly stable in normal saline and fresh human serum at 37°C in vitro and in urine and plasma samples of nude mice after 2–3 h of injection. Cellular uptake and retention ratios of 99mTc-EGFR-PNA in SKOV3 cells were higher than those of 99mTc-CTL-PNA and the EGFR-negative control. Meanwhile, EGFR mRNA binding 99mTc-EGFR-PNA was blocked with an excess of unlabeled EGFR-PNA in SKOV3 cell lines. The biodistribution study demonstrated accumulation of 99mTc-EGFR-PNA primarily in the SKOV3 xenografts and in EGFR-expressing organs. Radionuclide imaging demonstrated clear localization of 99mTc-EGFR-PNA in the SKOV3 xenografts shortly after injection but not in 99mTc-CTL-PNA and the EGFR-negative control. Conclusion: 99mTc-EGFR-PNA has the potential for imaging EGFR mRNA overexpression in tumors.

【 授权许可】

Unknown