Tamoxifen down-regulates CD36 messenger RNA levels in normal and neoplastic human breast tissues.

TitleTamoxifen down-regulates CD36 messenger RNA levels in normal and neoplastic human breast tissues.
Publication TypeJournal Article
Year of Publication1997
AuthorsSilva, ID, Salicioni, AM, Russo, IH, Higgy, NA, Gebrim, LH, Russo, J
JournalCancer research
Volume57
Issue3
Pagination378-81
Date Published1997 Feb 1
KeywordsAntigens, CD36, Antineoplastic Agents, Hormonal, Base Sequence, Breast, Breast Neoplasms, Down-Regulation, Female, Gene Expression Regulation, Humans, Molecular Sequence Data, RNA, Messenger, Tamoxifen, Transcriptional Activation
AbstractTamoxifen (TAM) exerts a long-term suppressive effect on human breast cancer cell proliferation. To determine whether the effects of TAM are mediated by specific gene activation or repression, normal and tumoral human breast tissues obtained before and during TAM treatment were analyzed by differential display technique. Total RNA for differential display analysis was obtained from breast tissues from two women with the diagnosis of estrogen receptor-positive stage II (T2N1M0) infiltrating ductal carcinoma, made by incisional biopsy, followed by modified radical mastectomy performed after a 30-day treatment with TAM (20 mg/day). One 202-bp cDNA band, AP5-1, was present in normal and tumoral biopsy samples, but was absent in breast tissue obtained during TAM treatment, and was confirmed by Northern hybridization, which showed a 2.7-kb band in both patients. The differentially expressed cDNA fragment showed 99% homology to Homo sapiens CD36 gene, a glycoprotein that acts as a receptor for the extracellular matrix proteins thrombospondin-1, collagen types I and IV, and oxidized low-density lipoprotein. These results indicate that the down-regulation of CD36 induced by TAM might represent alternative or additional mechanisms of action of this drug affecting the functions of thrombospondin-1, which is involved in hematogenous tumor spread, invasion and angiogenesis, and oxidized low-density lipoprotein, playing a role in inhibition of arteriosclerosis. The multiple functions affected by the down-regulation of CD36 by TAM warrant the need for additional studies.
Alternate JournalCancer Res.