Small Molecule Ligands for Active Targeting of TrkC-Expressing Tumor Cells
摘要:
A small molecule motif was used in "active targeting" to deliver cytotoxic substances into tumor cells that express the TrkC receptor. Underlying this study was the hypothesis that internalization of targeted conjugates into cells would be facile if mediated by receptor binding and receptor ligand internalization. Initial experiments using 6-mercaptopurine gave encouraging data but demonstrated the importance of maintaining solubility and high cytotoxicity. Conjugates of the targeting agent with a cytotoxic rosamine (similar to a rhodamine) were more successful. Targeting of TrkC was observed, validated in a series of competition experiments featuring other TrkC ligands, and accumulation into lysosomes was observed, as expected for receptor-mediated internalization.
A small molecule motif (IY-IY), which binds the tropomyosin receptor kinase C (TrkC), was used to deliver the promiscuous kinaseinhibitor (KI) dasatinib into breast cancer. Conjugates with noncleavable (1) and cleavable (2) linkers were compared in cellular assays and shown to have more impact on the cell viabilities of TrkC+ breast cancer cells over TrkC- epithelial cells. The IY-IY fragment was
Double-Targeting Using a TrkC Ligand Conjugated to Dipyrrometheneboron Difluoride (BODIPY) Based Photodynamic Therapy (PDT) Agent
作者:Anyanee Kamkaew、Kevin Burgess
DOI:10.1021/jm4012142
日期:2013.10.10
A molecule 1 (IY-IY-PDT) was designed to contain a fragment (if-if) that targets the TrkC receptor and a photosensitizer that acts as an agent for photodynamic therapy (PDT). Molecule 1 had submicromolar photocytotoxicities to cells that were engineered to stably express TrkC (NIH3T3-TrkC) or that naturally express high levels of TrkC (SYSY neuroblastoma lines). Control experiments showed that 1 is not cytotoxic in the dark and has significantly less photocytotoxicity toward cells that do not express TrkC (NIH3T3-WT). Other controls featuring a similar agent 2 (YI-YI-PDT), which is identical and isomeric with 1 except that the targeting region is scrambled (a YI-YI motif, see text), showed that 1 is considerably more photocytotoxic than 2 on TrkC(+) cells. Imaging live TrkC(+) cells after treatment with a fluorescent agent 1 (IY-IY-PDT) proved that 1 permeates into TrkC(+) cells and is localized in the lysosomes. This observation indirectly indicates that agent 1 enters the cells via the TrkC receptor. Consistent with this, the dose-dependent PDT effects of 1 can be competitively reduced by the natural TrkC ligand, neurotrophin NT3.