Significant Differences in Biological Parameters between Prodrugs Cleavable by Carboxypeptidase G2 That Generate 3,5-Difluoro-phenol and -aniline Nitrogen Mustards in Gene-Directed Enzyme Prodrug Therapy Systems

Abstract

Nine new nitrogen mustard compounds derived from 2,6-difluoro-4-hydroxy- (3a-e) and 2,6-difluoro-4-amino- (4a-d) aniline were synthesized as potential prodrugs. They were designed to be activated to their corresponding 3,5-difluorophenol and -aniline (4)-nitrogen mustards by the enzyme carboxypeptidase G2 (CPG2) in gene-directed enzyme prodrug therapy (GDEPT) models. The compounds were tested for cytotoxicity in the MDA MB-361 breast adenocarcinoma. The cell line was engineered to express stably either CPG2 tethered to the cell surface stCPG2-(Q)3 or beta-galactosidase (beta-Gal) as control. The cytotoxicity differentials were calculated between CPG 2-expressing and -nonexpressing cells and yielded different results for the two series of prodrugs despite their structural similarities. While the phenol compounds are ineffective as prodrugs, their aniline counterparts exhibit outstanding activity in the tumor cell lines expressing CPG2. [3,5-Difluoro-4-[bis(2-chloroethyl)amino]phenyl]carbamoyl-l-glutamic acid gave a differential of >227 in MDA MB361 cells as compared with 19 exhibited by 4-[(2-chloroethyl)(2-mesyloxyethyl)amino]benzoyl-l-glutamic acid, 1a, which has been in clinical trials.

Suicide genes for cancer therapy

“…CPG2, which has no human analogue, converts the nitrogen mustard prodrugs CMDA and ZD2767P, as well as several other recently described prodrugs into DNA alkylating agents, without the requirement of endogenous enzymes or cofactors (Blakey et al, 1996;Davies et al, 2005;Friedlos et al, 2002;Niculescu-Duvaz et al, 2004;Springer et al, 1990). CPG2 recombinantly expressed in eukaryotic cells is normally secreted due to an N-terminal signal peptide.…”

The Biocatalysis in Cancer Therapy

“…PMEG is subsequently phosphorylated by CKs to PMEGpp (115, Figure 11C), resulting in anticancer activity through inhibition of nuclear DNA polymerases. 137 Other prodrugs activated by biocatalytic cascade reaction also include tocladesine (116) and AFP464 (119), which are activated by phosphodiesterase/ 5′-nucleotidase/CE and esterase/P450, respectively (Figure 11D and E). 138,139 In addition, some prodrugs designed using the ProTide technology are also activated by a biocatalytic cascade.…”

Compostos organofosforados pentavalentes: histórico, métodos sintéticos de preparação e aplicações como inseticidas e agentes antitumorais

“…O anel de seis membros 1,3,2-oxazafosforinas é a estrutura comum presente nestes compostos 113,114 .…”