Related Experiment Video

Updated: Sep 30, 2026

Exploring the Pharmacological Action and Molecular Mechanism of Salidroside in Inhibiting MCF-7 Cell Proliferation and Migration
11:13

Exploring the Pharmacological Action and Molecular Mechanism of Salidroside in Inhibiting MCF-7 Cell Proliferation and Migration

Published on: June 9, 2023

Inhibition of carcinogen-activating enzymes by 16alpha-fluoro-5-androsten-17-one

Henry P Ciolino1, Christopher J MacDonald, Grace Chao Yeh

  • 1Cellular Defense and Carcinogenesis Section, Basic Research Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, NIH, Frederick, Maryland 21702-1201, USA. hciolino@ncifcrf.gov

Cancer Research
|July 5, 2002
PubMed

Insights

Fluasterone, a dehydroepiandrosterone analogue, inhibits carcinogen-activating enzymes like cytochrome P450 (CYP) 1A1 and 1B1. It reduces CYP1A1 and CYP1B1 mRNA levels via transcriptional and post-transcriptional mechanisms.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Pharmacology

Background:

  • Carcinogen-activating enzymes, such as cytochrome P450 (CYP) 1A1 and 1B1, play a crucial role in metabolizing environmental toxins.
  • Dysregulation of these enzymes can lead to increased cancer risk.
  • Dehydroepiandrosterone (DHEA) and its analogues have shown chemopreventive potential.

Purpose of the Study:

  • To investigate the effect of fluasterone, a synthetic DHEA analogue, on the activity and expression of carcinogen-activating enzymes (CYP1A1 and CYP1B1) in MCF-7 cells.
  • To elucidate the mechanisms by which fluasterone modulates these enzymes, focusing on transcriptional and post-transcriptional regulation.

Main Methods:

  • MCF-7 cells were treated with carcinogens dimethylbenzanthracene (DMBA) or dioxin (TCDD) with or without fluasterone.
  • Ethoxyresorufin-O-deethylase activity assays were used to measure CYP1A1 and CYP1B1 activity.
  • Quantitative real-time PCR was employed to assess CYP1A1 and CYP1B1 mRNA levels.
  • Reporter gene assays were conducted to evaluate transcriptional regulation.
  • Actinomycin D chase experiments were performed to study mRNA degradation.

Main Results:

  • Fluasterone cotreatment inhibited the DMBA- or TCDD-induced increase in CYP1A1 and CYP1B1 activity.
  • Fluasterone significantly decreased CYP1A1 and CYP1B1 mRNA levels in a dose-dependent manner.
  • Fluasterone inhibited CYP1A1 promoter activity, indicating transcriptional inhibition.
  • Actinomycin D chase experiments revealed that fluasterone increased CYP1A1 mRNA degradation but not CYP1B1 mRNA degradation.

Conclusions:

  • Fluasterone effectively inhibits the carcinogen-induced upregulation of CYP1A1 and CYP1B1.
  • The inhibition of CYP1A1 expression by fluasterone involves both transcriptional suppression and accelerated mRNA degradation.
  • CYP1B1 expression is regulated at the transcriptional level by fluasterone, but not via post-transcriptional mechanisms involving mRNA stability.

More Related Videos

Structure-Guided Design and Development of Novel Cyclophilin A Inhibitors and Ganoderiol-F Derivatives: An In-Silico Approach10:01

Structure-Guided Design and Development of Novel Cyclophilin A Inhibitors and Ganoderiol-F Derivatives: An In-Silico Approach

Published on: June 23, 2026

Related Concept Videos

Mutagenicity and Carcinogenicity01:25

Mutagenicity and Carcinogenicity

Mutagenicity and carcinogenicity refer to the ability of drugs to cause genetic defects and induce cancer, respectively. The International Agency for Research on Cancer (IARC) classifies agents into four groups based on their carcinogenic potential. Group 1 agents are known human carcinogens; group 2A agents are probably carcinogenic to humans; group 3 agents lack data to support their role in carcinogenesis; and group 4 includes agents for which data support that they are not likely to be...
Cancer Prevention02:59

Cancer Prevention

Several factors can increase the risk of cancer in an individual. About 50% of cancer cases can be prevented by adopting a healthy lifestyle, regular exercise, eating healthy, and following a modest cancer prevention diet. Epidemiological studies have consistently shown that populations with vegetable and fruit-rich diets have reduced the incidence of cancer. On the other hand, populations who have a diet rich in animal fat, red meat, junk food, or high calories are predisposed to cancer.
Some...
Bioactivation and Tissue Toxicity01:25

Bioactivation and Tissue Toxicity

Bioactivation is a metabolic process that transforms less reactive substances into highly reactive metabolites, initiating tissue toxicity. This transformation can lead to various toxic effects, including carcinogenesis and teratogenesis. Reactive metabolites are classified into two main types: electrophiles and free radicals.Electrophiles are electron-deficient species and are produced primarily by the enzyme cytochrome P-450 during the metabolism of compounds containing carbon, nitrogen, or...