Up-regulation of LRP16 mRNA by 17beta-estradiol through activation of estrogen receptor alpha (ERalpha), but not ERbeta, and promotion of human breast cancer MCF-7 cell proliferation: a preliminary report.
LRP16 is a novel gene cloned from lymphocytic cells, and its function is not known. The expression level of LRP16 mRNA was up-regulated by estrogen in breast cancer MCF-7 cells based on the computed aided serial analysis of gene expression (SAGE) analysis. In this study, we investigate the effect of 17beta-estradiol (17beta-E(2)) on the expression of LRP16 mRNA and the effects of overexpression of LRP16 on the proliferation of cultured MCF-7 cells and the possible mechanisms involved. The expression level of LRP16 mRNA induced by 17beta-E(2) was determined by Northern blot analysis. LRP16 promoter-controlled luciferase expression vector (pGL3-S(0)) was co-transfected with various nuclear receptors, including estrogen receptor alpha and beta (ERalpha and ERbeta), glucocorticoid receptor alpha (GRalpha), androgen receptor (AR) and peroxisome-proliferator activated receptor gamma and alpha (PPARgamma and PPARgamma) into COS-7 cells, and the relative luciferase activity was measured using Dual-luciferase report assay systems. The effect of overexpression of LRP16 on MCF-7 proliferation was examined by the Trypan Blue exclusion method, and the cell cycle was analyzed by flow cytometry. The expression levels of cyclin E, p53 and p21(WAF1/CIP1) proteins were determined by Western blot analysis. The results showed (1) 17beta-E(2) induced a five- to eightfold increase in LRP16 mRNA levels in MCF-7 cells; (2) the relative luciferase activities in the COS-7 cells co-transfected by pGL3-S(0) and ERalpha or AR were 7.8-fold and 11-fold respectively of those in the control cells transfected by pGL3-S(0) alone; (3) overexpression of LRP16 stimulated MCF-7 cell proliferation, and the numbers of cells in the S-phase of the cell cycle in cells transfected with LRP16 increased about 10% compared with the control cells; and (4) cyclin E levels were much higher in cells with overexpression of LRP16 than in the control cells, while the expression levels of p53 and p21(WAF1/CIP1) were not different between the two groups of cells. From these results we concluded that estrogen up-regulates the expression level of LRP16 mRNA through activation of ERalpha and that overexpression of LRP16 promotes MCF-7 cell proliferation probably by increasing cyclin E.
Han
W-D
WD
Department of Molecular Biology, Institute of Basic Medicine, Chinese PLA General Hospital, 28 Fu Xing Road, Beijing 100853, People's Republic of China.
Mu
Y-M
YM
Lu
X-C
XC
Xu
Z-M
ZM
Li
X-J
XJ
Yu
L
L
Song
H-J
HJ
Li
M
M
Lu
J-M
JM
Zhao
Y-L
YL
Pan
C-Y
CY
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D019556:COS Cells; D002265:Carboxylic Ester Hydrolases; D002455:Cell Division / Q000187:drug effects; D019927:Cyclin E / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation
C493956:CDKN1A protein, human; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D011944:Receptors, Androgen; D018160:Receptors, Cytoplasmic and Nuclear; D011960:Receptors, Estrogen; D016159:Tumor Suppressor Protein p53; D004958:Estradiol; D002265:Carboxylic Ester Hydrolases; C476832:MACROD1 protein, human