Coupling Reaction of Oligo p-Phenylene Ethynylene and Peptide Antagonist RM26 Labeling with ¹³¹I

Investigations reveale that oligo p-phenylene ethynylene (OPE) molecule can insert into cell membrane, which leads to its cellular internization capacility. Antagonists have high cancer cell affinity, high uptake in cancer cells and fast clearance in normal tissue, these capabilities have attracted much research interest in radiopharmaceutical development. Combining the strong cell-penetrating ability and high affinity of Gastrin-releasing peptide which is overexpressed in the PC-3 cells, the thesis designed and synthesized unsymmetric OPE(NH₂) molecule. Then the OPE(NH₂) molecule was followed by the coupling reaction with RM26 peptide to obtain the OPE-RM26, and (Tyr)₃-RM26 was also got for controling study. After that, the (Tyr)₃-RM26 and OPE-RM26 were radiolabeled with I-131 to give high radiolabeling yields that could up to 95%. The radiolabeling compound was stable after 24 h storage at room temperature. These labeled compounds are ready for animal in-vivo experiment. It is expected that OPE-RM26-¹³¹I has multi-properties with targeting membrane crossing fire of radioactive elements. The molecule may fast travel to the target tissue and bind to GRP receptor and internalized into cancer cells. The casade process will give rise to its cancer cell toxicity due to longer retention and more killing effect of ray’s irradiation to cancer cells. In this way, OPE-RM26-¹³¹I can achieve better anti-cancer ability.