The effect of a novel transition state inhibitor of methylthioadenosine phosphorylase on pemetrexed activity.

Article Details

Citation

Copy to clipboard

Chattopadhyay S, Zhao R, Tsai E, Schramm VL, Goldman ID

The effect of a novel transition state inhibitor of methylthioadenosine phosphorylase on pemetrexed activity.

Mol Cancer Ther. 2006 Oct;5(10):2549-55.

PubMed ID

17041099 [ View in PubMed

]

Abstract

Pemetrexed is a new-generation antifolate inhibitor of thymidylate synthase (TS) and a weaker inhibitor of glycinamide ribonucleotide transformylase (GARFT) required for de novo purine synthesis. Methylthioadenosine phosphorylase (MTAP) salvages purines by releasing adenine from methylthioadenosine and is often deleted in mesothelioma. The current study addresses the effect of MTAP on pemetrexed activity using a highly potent transition state inhibitor of MTAP, MT-DADMe-Immucillin A (ImmA; K(i) = 86 pmol/L) in the MTAP(+) NCI-H28 and MTAP(-) NCI-H2052 mesothelioma cell lines. Based on selective nucleoside protection, TS was found to be the primary pemetrexed target in both cell lines with GARFT inhibition requiring 20- to 30-fold higher pemetrexed concentrations. ImmA had no effect on pemetrexed activity but, when thymidine was added, the pemetrexed IC(50) decreased by a factor of approximately 3 in MTAP(+) H28 cells with no effect in MTAP(-) H2052 cells. Conversely, the transfection of MTAP into H2052 cells increased the pemetrexed IC(50) by nearly 3-fold but only in the presence of thymidine; this was reversed by ImmA. An MTAP-specific short interfering RNA produced a 2-fold decrease in pemetrexed IC(50) in MTAP(+) HeLa cells in the presence of thymidine. These data indicate that suppression of constitutive MTAP has no effect on pemetrexed activity when the primary target is TS. There is a modest salutary effect when the pemetrexed target is GARFT alone.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Adenine	S-methyl-5'-thioadenosine phosphorylase	Protein	Humans	Unknown	Not Available	Details