Development of albumin-binding camptothecin prodrugs using a peptide positional scanning library

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Item Type:	Article
Title:	Development of albumin-binding camptothecin prodrugs using a peptide positional scanning library
Creators Name:	Schmid, B., Warnecke, A., Fichtner, I., Jung, M. and Kratz, F.
Abstract:	Designing truly tumor-specific prodrugs remains a challenge in the field of cancer chemotherapy. As a new strategy, we incubated homogenates of a spectrum of human colon tumor xenografts with a fluorogenic positional scanning tetrapeptide library in order to identify peptide sequences that are preferentially cleaved by colon tumors. Our screening experiments at pH 7.4 revealed that Met, Leu, and Lys were preferred amino acids in the position P(1) and Tyr, Phe, and Met in P(2), whereas in P(3) and P(4), the cleavage profiles were less characteristic. However, similar results were obtained when testing breast tumor material and homogenates from healthy murine organs. On the basis of these results, we developed albumin-binding camptothecin (CPT) prodrugs of the general formula EMC-Arg-P(4)-P(3)-P(2)-P(1)-Ala-CPT (EMC = 6-maleimidocaproic acid) that incorporated two peptide linkers: H-Arg-Ala-Phe-Met-OH and H-Arg-Phe-Tyr-Met-OH (P(4)-P(3)-P(2)-P(1)). The incorporation of two arginine residues rendered the prodrugs water-soluble (>7 mg spacer proved to be beneficial for the release of the active agent. Incubation studies with homogenates of HT-29 colon tumor tissue and murine spleen, liver, and kidneys demonstrated cleavage of the peptide linker with CPT-peptide derivatives and CPT being the major cleavage products. Although the peptide sequence is not selectively cleaved in colon tumors, an in vivo study in a HT-29 xenograft model showed that the prodrug EMC-Arg-Arg-Ala-Phe-Met-Ala-CPT demonstrated enhanced antitumor efficacy when compared to CPT [( T for the prodrug (2 x 12.5 mg mg/kg)].
Keywords:	Albumins, Camptothecin, Health, Molecular Structure, Neoplasms, Peptide Library, Prodrugs, Tumor Cell Line, Xenograft Model Antitumor Assays, Animals, Mice
Source:	Bioconjugate Chemistry
ISSN:	1043-1802
Publisher:	American Chemical Society
Volume:	18
Number:	6
Page Range:	1786-1799
Date:	November 2007
Official Publication:	https://doi.org/10.1021/bc0700842
PubMed:	View item in PubMed

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