Annatto constituent cis-bixin has selective antimyeloma effects mediated by oxidative stress and associated with inhibition of thioredoxin and thioredoxin reductase

Jennifer D. Tibodeau, Crescent R. Isham, Keith C. Bible

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

In pursuit of the anticancer effects of seeds of the rain forest plant Bixa orellana (annatto), we found that its constituent cis-bixin induced cytotoxicity in a wide variety of tumor cell lines (IC50 values from 10 to 50μM, 24-h exposures) and, importantly, also selectively killed freshly collected patient multiple myeloma cells and highly drug-resistant multiple myeloma cell lines. Mechanistic studies indicated that cis-bixin-induced cytotoxicity was greatly attenuated by co-treatment with glutathione or N-acetylcysteine (NAC); whereas fluorescence-activated cell sorting (FACS) assays using the cell-permeable dyes 5-(and-6) chloromethyl-2′,7′- dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA), or dihydroethidium demonstrated that cis-bixin rapidly induced cellular reactive oxygen species (ROS) in dose-and time-dependent fashions, collectively implicating ROS as contributory to cis-bixin-induced cytotoxicity. In pursuit of potential contributors to ROS imposition by cis-bixin, we found that cis-bixin inhibited both thioredoxin (Trx) and thioredoxin reductase (TrxR1) activities at concentrations comparable to those required for cytotoxicity, implicating the inhibition of these redox enzymes as potentially contributing to its ability to impose cellular ROS and to kill cancer cells. Collectively, our studies indicate that the annatto constituent cis-bixin has intriguing selective antimyeloma activity that appears to be mediated through effects on redox signaling.

Original languageEnglish (US)
Pages (from-to)987-997
Number of pages11
JournalAntioxidants and Redox Signaling
Volume13
Issue number7
DOIs
StatePublished - Oct 1 2010

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Molecular Biology
  • Clinical Biochemistry
  • Cell Biology

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