Wakame seaweed suppresses the proliferation of 7,12-dimethylbenz(a)-anthracene-induced mammary tumors in rats

Jpn J Cancer Res. 1999 Sep;90(9):922-7. doi: 10.1111/j.1349-7006.1999.tb00836.x.


We examined the anti-tumor proliferation effects of wakame seaweed on 7,12-dimethylbenz(a)-anthracene (DMBA)-induced rat mammary tumor. DMBA was administered to 8-week-old female Sprague-Dawley rats, and rats which developed mammary tumors were assigned randomly to three groups. Commercial rat feed was used in a control group (group I-A), and two feed mixtures were prepared, which contained commercial rat feed blended with wakame at 1.0% (group I-B) and 5.0% (group I-C) by weight. The respective feeds were given to each group for 8 weeks, and changes in mammary tumor size were compared. At the end of the experiment, mammary tumors and thyroid glands were resected to compare their weights. Serum total iodine and thyroxin (T4) levels were measured. Immunohistochemical studies for bromodeoxyuridine (BrdU) labeling, transforming growth factor (TGF)-beta, and apoptosis were carried out in the resected tumor. Significant suppression of tumor growth was observed in groups I-B and I-C compared with I-A. In groups I-B and I-C, the weights of resected mammary tumors were significantly lower and serum total iodine concentration was significantly higher than in I-A. BrdU indices were significantly lower in groups I-B and I-C, compared with I-A. TGF-beta and apoptotic index were inversely related to BrdU. These results suggest that iodine is transported from the serum into mammary tissues and induces apoptosis through the expression of TGF-beta. In conclusion, wakame suppressed the proliferation of DMBA-induced mammary tumors.

MeSH terms

  • 9,10-Dimethyl-1,2-benzanthracene
  • Animals
  • Apoptosis
  • Body Weight / drug effects
  • Bromodeoxyuridine / analysis
  • Cell Division / drug effects
  • Endocrine Glands / drug effects
  • Eosine Yellowish-(YS) / metabolism
  • Female
  • Hematoxylin / metabolism
  • Immunohistochemistry
  • In Situ Nick-End Labeling
  • Iodine / blood
  • Mammary Neoplasms, Experimental / blood
  • Mammary Neoplasms, Experimental / chemically induced
  • Mammary Neoplasms, Experimental / drug therapy*
  • Neoplasm Transplantation
  • Phaeophyta*
  • Plant Extracts / adverse effects
  • Plant Extracts / therapeutic use
  • Rats
  • Rats, Sprague-Dawley
  • Seaweed / chemistry*
  • Thyroid Gland / drug effects
  • Thyroxine / blood
  • Transforming Growth Factor beta / analysis


  • Plant Extracts
  • Transforming Growth Factor beta
  • 9,10-Dimethyl-1,2-benzanthracene
  • Iodine
  • Bromodeoxyuridine
  • Thyroxine
  • Eosine Yellowish-(YS)
  • Hematoxylin