[In vitro study of the effects of estrogen receptor beta expression on the biological behavior of a human breast cancer cell line].
OBJECTIVE
To study effects of estrogen receptor beta (ER beta) on the biological behavior of a human breast cancer cell line MDA-MB-435.


METHODS
Human ER beta cDNA was introduced into MDA-MB-435 cells by stable transfection. Effects of ER beta expression on cell proliferation and invasion were investigated by MTT, flow cytometry and transwell techniques. Cyclin A, cyclin E, cyclin D1, p21, MMPs, Ets-1, VEGF and b-FGF were detected by RT-PCR and/or Western blot or gelatin zymography.


RESULTS
ER beta was shown to be able to significantly increase the proliferation and invasion of MDA-MB-435 cells in an estradiol-independent manner. The S phase distribution of the cells with ER beta overexpression was 46.8%, significantly higher than that of wild type (29.9%) and mock transfected cells (27.6%) (P = 0.01). In ER beta transfected cells, the expression of p21 decreased by 33.3% at mRNA level (P = 0.03) and by 47.4% at protein level (P = 0.02), respectively. The expression of MMP-9 increased by 91.3% at mRNA level (P < 0.01) and its activity was up-regulated by 67.3% (P = 0.02). Furthermore, the mRNA and protein levels of Ets-1 increased 62.2% (P = 0.01) and 51.0% (P = 0.01), respectively. No significant difference was observed in the mRNA levels of cyclin A, cyclin E, cyclin D1, MMP-1, MMP-2, MMP-7, VEGF and b-FGF among these cells.


CONCLUSIONS
ER beta can enhance proliferation and invasion of breast cancer cells. Down-regulation of p21 and up-regulation of MMP-9 and Ets-1 may be involved in its mechanisms.
Hou
Yi-feng
YF
Department of Breast Surgery, Cancer Hospital, Fudan University, Shanghai 200032, China.
Yuan
Sheng-tao
ST
Li
He-cheng
HC
Wu
Jiong
J
Lu
Jin-song
JS
Lu
Li-juan
LJ
Liu
Gang
G
Shen
Zhen-zhou
ZZ
Ding
Jian
J
Shao
Zhi-min
ZM
D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D047629:Estrogen Receptor beta / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis / Q000235:genetics; D009361:Neoplasm Invasiveness; D050784:Proto-Oncogene Protein c-ets-1 / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018076:DNA, Complementary; D047629:Estrogen Receptor beta; D050784:Proto-Oncogene Protein c-ets-1; D012333:RNA, Messenger; D020780:Matrix Metalloproteinase 9