Identification of leptin receptors in human breast cancer: functional activity in the T47-D breast cancer cell line.
To evaluate whether leptin plays a putative role in breast tumorigenesis, we studied the expression of its long and short receptor isoforms in various tumoral breast tissues. We applied semiquantitative RT-PCR method to RNA extracted from 20 breast cancer biopsies and two human breast cancer cell lines (T47-D and MCF-7). Our results showed the expression of both leptin receptor transcripts in all tumoral tissues examined. By in situ hybridization experiments, we localized leptin receptors in proliferating epithelial cells. Study of leptin effects on human breast cancer cells growth was performed by [3H]-thymidine incorporation method and colorimetric MTT assay. We demonstrated that leptin (50-100 ng/ml) significantly stimulates proliferation of the human breast cancer cell line T47-D (P<0.05). Western blot analysis indicated that leptin induces a time-dependent activation of mitogen-activated protein kinases (MAPKinase) 1 and 2 in T47-D cell line. Moreover, the specific MAPK-inhibitor PD 98059 blocked cell proliferation induced by leptin. In conclusion, we demonstrate that leptin receptors are expressed in breast cancer and that leptin induces proliferation in the T47-D cell line via activation of the MAPKinases pathway. These data suggest that leptin and its receptors may be implicated in mammary cell proliferation and in breast cancer pathogenesis.
Laud
K
K
Laboratoire de Biologie Cellulaire et Moléculaire, Institut National de la Recherche Agronomique, 78352 Jouy-en-Josas, Cedex, France.
Gourdou
I
I
Pessemesse
L
L
Peyrat
J P
JP
Djiane
J
J
D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism; D018270:Carcinoma, Ductal, Breast / Q000235:genetics* / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics*; D002455:Cell Division; D017931:DNA Primers / Q000737:chemistry; D005260:Female; D006801:Humans; D017403:In Situ Hybridization; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D008875:Middle Aged; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000378:metabolism; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013778:Tetrazolium Salts; D013844:Thiazoles; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D017931:DNA Primers; C515448:LEPR protein, human; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D013778:Tetrazolium Salts; D013844:Thiazoles; C482128:MAP2K2 protein, human; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; C022616:thiazolyl blue; D013936:Thymidine