Saturday, September 22, 2012

New drug candidate shows promise against cancer - MIT Media Relations

Drugs containing platinum are among the most powerful and widely used cancer drugs. However, such drugs have toxic side effects, and cancer cells can eventually become resistant to them. Stephen J Lippard, Chemistry Professor, MIT who has spent much of his career studying platinum drugs, has now identified a compound that kills cancer cells better than cisplatin, the most commonly used platinum anticancer drug. The new compound may be able to evade cancer-cell resistance to conventional platinum compounds.
“I’ve long believed that there’s something special about platinum and its ability to treat cancer. Using new variants, we might have a chance of applying platinum to a broader range of cancer types, more successfully,” said Lippard. Lippard is senior author of a paper describing the new drug candidate, known as phenanthriplatin - which is cis-[Pt(NH3)2(phenanthridine)Cl]NO3.

As per the authors, phenanthriplatin exhibits significantly greater activity than the Food and Drug Administration-approved drugs cisplatin and oxaliplatin. Studies of phenanthriplatin in the National Cancer Institute 60-cell tumor panel screen revealed a spectrum of activity distinct from that of these clinically validated anticancer agents. The cellular uptake of phenanthriplatin is substantially greater than that of cisplatin and pyriplatin because of the hydrophobicity of the phenanthridine ligand. Phenanthriplatin binds more effectively to 5′-deoxyguanosine monophosphate than to N-acetyl methionine, whereas pyriplatin reacts equally well with both reagents. This chemistry supports DNA as a viable cellular target for phenanthriplatin and suggests that it may avoid cytoplasmic platinum scavengers with sulfur-donor ligands that convey drug resistance. With the use of globally platinated Gaussialuciferase vectors, we determined that phenanthriplatin inhibits transcription in live mammalian cells as effectively as cisplatin, despite its inability to form DNA cross-links. 

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