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Indole-3-carbinol induces a G1 cell cycle arrest and inhibits prostate-specific antigen production in human LNCaP prostate carcinoma cells

  1. Joann Zhang Ph.D.1,
  2. Jocelyn C. Hsu B.A.1,2,
  3. Matthew A. Kinseth B.A.1,2,
  4. Leonard F. Bjeldanes Ph.D.3,
  5. Gary L. Firestone Ph.D.1,2,†,*

Article first published online: 29 OCT 2003

DOI: 10.1002/cncr.11844

Issue

Cancer

Cancer

Volume 98, Issue 11, pages 2511–2520, 1 December 2003

Additional Information

How to Cite

Zhang, J., Hsu B.A., J. C., Kinseth B.A., M. A., Bjeldanes, L. F. and Firestone, G. L. (2003), Indole-3-carbinol induces a G1 cell cycle arrest and inhibits prostate-specific antigen production in human LNCaP prostate carcinoma cells. Cancer, 98: 2511–2520. doi: 10.1002/cncr.11844

Author Information

  1. 1

    Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California

  2. 2

    Cancer Research Laboratory, University of California at Berkeley, Berkeley, California

  3. 3

    Department of Nutritional Sciences and Toxicology, University of California at Berkeley, Berkeley, California

  1. †

    Fax: (510) 643-6791

*Department of Molecular and Cell Biology, 591 LSA, University of California at Berkeley, Berkeley, CA 94720-3200

Publication History

  1. Issue published online: 17 NOV 2003
  2. Article first published online: 29 OCT 2003
  3. Manuscript Accepted: 8 SEP 2003
  4. Manuscript Revised: 13 AUG 2003
  5. Manuscript Received: 16 JUN 2003

Funded by

  • NIH Public Health Service
  • National Cancer Institute. Grant Number: CA69056
  • California Department of Health Services. Grant Number: 99-00497V-10010

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Keywords:

  • indole-3-carbinol;
  • prostate carcinoma cells;
  • cell cycle control;
  • growth inhibition;
  • cyclin-dependent kinase;
  • gene expression;
  • protein kinase activity;
  • prostate-specific antigen

Abstract

BACKGROUND

Indole-3-carbinol (I3C), a naturally occurring component of Brassica vegetables, such as cabbage, broccoli, and Brussels sprouts, is a promising anticancer agent for certain reproductive tumor cells. The objective of the current study was to characterize the cell cycle effects of I3C in human prostate carcinoma cells.

METHODS

The incorporation of [3H]thymidine and flow cytometry of propidium iodide–stained nuclei were used to monitor I3C-regulated changes in prostate carcinoma cell proliferation and cell cycle progression. Western blotting was used to document expression changes in cell cycle components and prostate-specific antigen (PSA) levels. The enzymatic activities of cyclin-dependent kinases (CDK) were tested by in vitro protein kinase assays using the retinoblastoma protein as a substrate.

RESULTS

I3C suppressed the growth of LNCaP prostate carcinoma cells in a dose-dependent manner by inducing a G1 block in cell cycle progression. I3C selectively inhibited the expression of CDK6 protein and transcripts and strongly stimulated the production of the p16 CDK inhibitor. In vitro protein kinase assays revealed the striking inhibition by I3C of immunoprecipitated CDK2 enzymatic activity and the relatively minor down-regulation of CDK4 enzymatic activity. In LNCaP prostate carcinoma cells, I3C treatment inhibited production of PSA, whereas combinations of I3C and the androgen antagonist flutamide more effectively inhibited DNA synthesis and PSA levels compared with either agent alone.

CONCLUSIONS

The results of the current study demonstrated that I3C has a potent antiproliferative effect in LNCaP and other human prostate carcinoma cells. These findings implicate this dietary indole as a potential chemotherapeutic agent for controlling the growth of human prostate carcinoma cells. Cancer 2003. © 2003 American Cancer Society.

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