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Growth inhibitory effects of flavonoids in human thyroid cancer cell lines
F Yin1, A E Giuliano, A J Van Herle
1Division of Endocrinology, UCLA School of Medicine, Los Angeles, California 90024, USA.
Abstract:
Previous studies have indicated that flavonoids exhibit antiproliferative properties on some hormone-dependent cancer cell lines, such as breast and prostate cancer. In the present study, the effects of some selected flavonoids, genistein, apigenin, luteolin, chrysin, kaempferol, and biochanin A on human thyroid carcinoma cell lines, UCLA NPA-87-1 (NPA) (papillary carcinoma), UCLA RO-82W-1 (WRO) (follicular carcinoma), and UCLA RO-81A-1 (ARO) (anaplastic carcinoma) have been examined. Among the flavonoids tested, apigenin and luteolin are the most potent inhibitors of these cell lines with IC50 (concentration at which cell proliferation was inhibited by 50%) values ranging from 21.7 microM to 32.1 microM. The cells were viable at these concentrations. Using NPA cells known to be estrogen receptor positive (ER+), it was shown that no significant [3H]-E2 displacement occurred with these flavonoids at the IC50 concentration. In WRO cells that are known to have an antiestrogen binding site (AEBS), biochanin A caused a stronger inhibitory growth effect (IC50 = 64.1 microM) than in NPA and ARO cells. In addition, it was observed that biochanin A has an appreciable binding affinity for the AEBS as indicated by the displacement of [3H]-tamoxifen from the WRO cells. In summary, flavonoids have potent antiproliferative activity in vitro against various human thyroid cancer cell lines. The inhibitory activity of certain flavonoid compounds may be mediated via the AEBS and/or type II EBS. The observation that ARO cells that lack both the AEBS and the ER are effectively inhibited by apigenin and luteolin suggest that other mechanisms of action are operative as well. The present study suggests that flavonoids may represent a new class of therapeutic agents in the management of thyroid cancer.
Insights
Flavonoids show strong potential as thyroid cancer treatments. Apigenin and luteolin effectively inhibited thyroid cancer cell growth, with biochanin A interacting with specific binding sites.
Area of Science:
- Biochemistry
- Pharmacology
- Oncology
Background:
- Flavonoids are known for antiproliferative effects on hormone-dependent cancers.
- Thyroid carcinoma comprises papillary, follicular, and anaplastic subtypes.
Purpose of the Study:
- To evaluate the antiproliferative effects of selected flavonoids on human thyroid carcinoma cell lines.
- To investigate the mechanisms of action, including interactions with estrogen receptors and antiestrogen binding sites.
Main Methods:
- Testing six flavonoids (genistein, apigenin, luteolin, chrysin, kaempferol, biochanin A) on NPA, WRO, and ARO thyroid cancer cell lines.
- Determining IC50 values for growth inhibition.
- Assessing [3H]-E2 displacement in ER+ NPA cells and [3H]-tamoxifen displacement in AEBS-possessing WRO cells.
Main Results:
- Apigenin and luteolin demonstrated potent inhibition of all tested thyroid cancer cell lines (IC50: 21.7–32.1 µM).
- Biochanin A showed significant inhibition in WRO cells (IC50: 64.1 µM) and displaced [3H]-tamoxifen, indicating AEBS interaction.
- Apigenin and luteolin inhibited ARO cells lacking ER and AEBS, suggesting alternative mechanisms.
Conclusions:
- Flavonoids exhibit potent in vitro antiproliferative activity against human thyroid cancer cell lines.
- Inhibitory effects may involve the antiestrogen binding site (AEBS) and/or Type II estrogen binding sites (EBS).
- Flavonoids, particularly apigenin and luteolin, represent a promising new class of therapeutic agents for thyroid cancer management.