The comparative effects of 5′-methylthioadenosine and some of its analogs on cells containing, and deficient in, 5′-methylthioadenosine phosphorylase

Michael W. White, Michael K. Riscoe, Adolph J. Ferro

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


The antiproliferative effects of 5′-methylthioadenosine and the 5′-methylthioadenosine analogs, 5′-isobutylthioadenosine, 5′-deoxyadenosine and 5′-methylthiotubercidin were examined using two mouse cell lines, one 5′-methylthioadenosine phosphorylase-deficient the other containing 5′-methylthioadenosine phosphorylase. All of the compounds were found to be growth inhibitory to both cell lines, demonstrating that these compounds need not be degraded to exert their inhibitory effects. A correlation was observed between the potency of the growth inhibitory effect and the ability of the cells to degrade these compounds. 5′-Methylthioadenosine, 5′-deoxyadenosine and 5′-isobutylthioadenosine, all of which are substrates for the 5′-methylthioadenosine phosphorylase in vitro, were more growth inhibitory to the 5′-methylthioadenosine phosphorylase-deficient cells than to the 5′-methylthioadenosine phosphorylase-containing cells, whereas, the 7-deaza analog, 5′-methylthiotubercidin, a nondegradable inhibitor of the 5′-methylthioadenosine phosphorylase, was a more potent inhibitor of the 5′-methylthioadenosine phosphorylase-containing cell line. Due to the inhibition by 5′-methylthiotubercidin on 5′-methylthioadenosine phosphorylase in vitro the disposition of cellularly-synthesized 5′-methylthioadenosine was explored using both cell types. 5′-Methylthiotubercidin inhibited the accumulation of exogenous 5′-methylthioadenosine from 5′-methylthioadenosine phosphorylase-deficient cells with no effect on intracellular 5′-methylthioadenosine. In contrast, 5′-methylthiotubercidin caused a large accumulation of extracellular 5′-methylthioadenosine with a concomitant smaller increase intracellularly in 5′-methylthioadenosine phosphorylase-containing cells. That cellularly-synthesized 5′-methylthioadenosine as well as the cellular excretion of this nucleoside are altered in response to treatment with 5′-methylthiotubercidin suggests two possible sites at which 5′-methylthiotubercidin may exert its effect.

Original languageEnglish (US)
Pages (from-to)405-413
Number of pages9
JournalBBA - Molecular Cell Research
Issue number3
StatePublished - Jun 2 1983


  • (Mouse cell)
  • Methylthioadenosine
  • Methylthioadenosine phosphorylase

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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