Flavopiridol: pleiotropic biological effects enhance its anti-cancer activity.
Flavopiridol has potent anti-proliferative properties due to its direct action of binding to the ATP-binding pocket of cyclin-dependent kinases (cdks), and due to its indirect action reducing levels of other cyclins and cdk inhibitors, contributing to its pleiotropic effects. Flavopiridol is a potent apoptotic agent due to its ability to cause cell death in cycling as well as non-cycling tumor cells; to down-regulate important cell survival proteins, such as survivin, through inhibition of the phosphorylation of Thr34; to increase sensitivity for S phase cells to drug treatment by modulating E2F-1 transcription factor activity in tumor cells; to induce both caspase-dependent and -independent mitochondrial cell death pathways; and to inhibit the activation of p-Akt which in turn inhibits activation of NF-kappaB. Flavopiridol possesses several important anti-angiogenic activities including induction of apoptosis of endothelial cells; inhibition of the hypoxic induction of vascular endothelial growth factor and/or its production under hypoxic conditions through inhibition of HIF-1alpha transcription; and decreased secretion of matrix metalloproteinases that is linked with significant inhibition of invasive potential in Matrigel assays. Taken together, the anti-proliferative and anti-angiogenic properties of flavopiridol may contribute to its anti-tumor activities observed in several preclinical animal models of human cancers including prostate, lymphoid, head and neck, colon, and glioma. These promising preclinical observations opened the way for phase I and II clinical trials. Given the low toxicity profile of flavopiridol used as a single agent in patients, combination therapy now offers numerous opportunities in the near future to improve the efficacy of flavopiridol in the treatment of refractory cancers.
Newcomb
Elizabeth W
EW
Department of Pathology, New York University Cancer Institute, New York University School of Medicine, New York, NY 10016, USA. newcoe01@med.nyu.edu
D020533:Angiogenesis Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D002986:Clinical Trials as Topic; D005419:Flavonoids / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy*; D010880:Piperidines / Q000494:pharmacology* / Q000627:therapeutic use
D020533:Angiogenesis Inhibitors; D000970:Antineoplastic Agents; D005419:Flavonoids; D010880:Piperidines; C077990:alvocidib