| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2008488 | Peptides | 2007 | 8 Pages |
The effects of vasoactive intestinal peptide–camptothecin (VIP–CPT) conjugates were investigated on breast cancer cells and cells transfected with VIP receptors (R). (Ala2,8,9,19,24.25.27, Nle17, Lys28)VIP, (A-NL-K)VIP, was synthesized and Lys28 was coupled to a linker, N-methyl-amino-ethyl-glycine, L2, which formed a carbamate bond with CPT. The resulting (A-NL-K)VIP-L2-CPT was cytotoxic for MCF7 breast cancer cells, which have VPAC1-R, with IC50 values of 380 and 90 nM using the MTT and clonogenic assays, respectively. (A-NL-K)VIP, (A-NL-K)VIP-L2 and (A-NL-K)VIP-L2-CPT inhibited specific binding of 125I-VIP to 3T3 cells transfected with VPAC1-R with IC50 values of 1.9, 56 and 126 nM, respectively. In contrast, (A-NL-K)VIP, (A-NL-K)VIP-L2 and (A-NL-K)VIP-L2-CPT inhibited specific binding of 125I-Ro25-1553 to 3T3 cells transfected with VPAC2-R with IC50 values of 3.9, 3162 and 2690 nM, respectively. (A-NL-K)VIP, (A-NL-K)VIP-L2 and (A-NL-K)VIP-L2-CPT caused increased cAMP after addition to MCF7 cells. 125I-(A-NL-K)VIP-L2-CPT was internalized by MCF7 cells at 37 °C but not 4 °C. These results indicate that (A-NL-K)VIP-L2-CPT is a VPAC1-R agonist which is cytotoxic for breast cancer cells.
