Investigation of the Biological Impact of Charge Distribution on a NTR1-Targeted Peptide
作者:Yinnong Jia、Wenting Zhang、Wei Fan、Susan Brusnahan、Jered Garrison
DOI:10.1021/acs.bioconjchem.6b00418
日期:2016.11.16
The neurotensin receptor 1 (NTR1) has been shown to be a promising target, due to its increased level of expression relative to normal tissue, for pancreatic and colon cancers. This has prompted the development of a variety of NTR1-targeted radiopharmaceuticals, based on the neurotensin (NT) peptide, for diagnostic and radiotherapeutic applications. A major obstacle for the clinical translation of NTR1-targeted radiotherapeutics would likely be nephrotoxicity due to the high levels of kidney retention. It is well-known that for many peptide-based agents, renal uptake is influenced by the overall molecular charge. Herein, we investigated the effect of charge distribution on receptor binding and kidney retention. Using the [(N-α-Me)Arg8,Dmt11,Tle12]NT(6–13) targeting vector, three peptides (177Lu–K2, 177Lu–K4, and 177Lu–K6), with the Lys moved closer (K6) or further away (K2) from the pharmacophore, were synthesized. In vitro competitive binding, internalization and efflux, and confocal microscopy studies were conducted using the NTR1-positive HT-29, human colon cancer cell line. The 177/natLu–K6 demonstrated the highest binding affinity (21.8 ± 1.2 nM) and the highest level of internalization (4.06% ± 0.20% of the total added amount). In vivo biodistribution, autoradiography, and metabolic studies of 177Lu-radiolabeled K2, K4, and K6 were examined using CF-1 mice. 177Lu–K4 and 177Lu–K6 gave the highest levels of in vivo uptake in NTR1-positive tissues, whereas 177Lu–K2 yielded nearly 2-fold higher renal uptake relative to the other radioconjugates. In conclusion, the position of the Lys (positively charged amino acid) influences the receptor binding, internalization, in vivo NTR1-targeting efficacy, and kidney retention profile of the radioconjugates. In addition, we have found that hydrophobicity likely play a role in the unique biodistribution profiles of these agents.
神经降压素受体1 (NTR1)因其相对于正常组织在胰腺癌和结肠癌中的表达水平增高,被认为是一个有前景的治疗靶点。这促使基于神经降压素(NT)肽的NTR1靶向放射性药物的研发,用于诊断和放射治疗应用。NTR1靶向放射治疗的临床转化主要障碍可能是由于高水平的肾脏滞留导致的肾毒性。众所周知,对于许多肽类制剂,肾脏摄取受分子整体电荷的影响。在此,我们研究了电荷分布对受体结合和肾脏滞留的影响。使用[(N-α-Me)Arg8,Dmt11,Tle12]NT(6–13) 靶向载体,合成了三种肽(177Lu–K2, 177Lu–K4, 和 177Lu–K6),其中赖氨酸(Lys)分别靠近(K6)或远离(K2)药效团。采用NTR1阳性的人结肠癌HT-29细胞系进行了体外竞争性结合、内化和流出以及共聚焦显微镜研究。177/natLu–K6显示出最高的结合亲和力(21.8 ± 1.2 nM)和最高水平的内化(4.06% ± 0.20%的总加入量)。通过CF-1小鼠检查177Lu放射性标记的K2、K4和K6的体内生物分布、放射自显影和代谢研究。177Lu–K4和177Lu–K6在NTR1阳性组织中显示出最高的体内摄取水平,而177Lu–K2的肾摄取相对其他放射性偶联物高出近2倍。总之,Lys(带正电荷的氨基酸)的位置影响放射性偶联物的受体结合、内化、体内NTR1靶向效能和肾脏滞留特征。此外,我们发现疏水性可能在这些制剂的独特生物分布特征中起作用。