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pubmed:abstractText |
(-)-Rhazinilam was spontaneously generated from a natural product during isolation. In cultured cells, it causes microtubule bundle formation, like those caused by paclitaxel. With tubulin, (-)-rhazinilam causes formation of an aberrant spiral polymer. Using glutamate and GTP, we developed an assay for spiral formation and applied it to 17 new (+/-)-rhazinilam analogs with either a modified side chain or a different size D ring. There was reasonable correlation between spiral formation and inhibition of human MCF-7 breast carcinoma cell growth. Only one side chain analog was as active as (+/-)-rhazinilam. During these studies, we observed that omitting GTP from the reaction mixture caused a major change in the morphology of the (-)-rhazinilam-induced polymer, with half the observed polymer being microtubule-like and half being spirals. This mixed polymer slowly disassembled at 0 degrees C, but there was no apparent difference in the lability of the microtubules versus the spirals.
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pubmed:affiliation |
Toxicology and Pharmacology Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702, USA.
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