Down-regulation of epidermal growth factor receptor induced by estrogens and phytoestrogens promotes the differentiation of U2OS human osteosarcoma cells.
In previous studies on HeLa cells we demonstrated estrogen-responsiveness of the epidermal growth factor receptor (EGFR) gene, as 17beta-estradiol (E(2)) and selective estrogen receptor modulators (SERMs) genistein (G), daidzein (D), and 4-hydroxytamoxifen (4OH-T) modulated its transcription in a ligand- and estrogen receptor (ER) isoform-specific way. This study describes further investigations into the role of ERs in mediating the effects induced by E(2) and SERMs on EGFR expression, and the relationship between the actions of ERs and EGFR in U2OS osteosarcoma cells stably expressing ERalpha or ERbeta. Cell number and DNA content determination revealed that E(2), G, and D inhibited proliferation and cell cycle progression and promoted apoptosis in both cell lines. In parallel, changes in cell morphology typical of osteoblast maturation were observed via optical microscopy. Consistently, quantitative PCR and Western blot analysis showed an up-regulation of markers of osteoblast differentiation and bone repair, and a decrease in EGFR expression. The transfection of specific antisense (AS) oligonucleotides strengthened our hypothesis that EGFR reduction caused changes in the proliferation/differentiation pattern comparable to those induced by ER ligands. The link between the ER and EGFR pathways was confirmed by treatment with 4OH-T, which decreased the EGFR level and produced differentiation effects via ERalpha, but induced both EGFR expression and proliferation effects via ERbeta. In conclusion, we show that also in U2OS cells, E(2) and SERMs are able to modulate the expression of the EGFR gene and can affect events strictly controlled by its signaling pathway, such as the maturation of osteoblasts.
Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy. luisa.salvatori@ifo.it
Luisa
L
Salvatori
Francesca
F
Caporuscio
Giuseppe
G
Coroniti
Giuseppe
G
Starace
Luigi
L
Frati
Matteo Antonio
MA
Russo
Elisa
E
Petrangeli
D017209:Apoptosis / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects* / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D015536:Down-Regulation; D066246:ErbB Receptors / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000187:drug effects / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000187:drug effects / Q000378:metabolism; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D048789:Phytoestrogens / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology*; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000494:pharmacology; D013997:Time Factors
D015415:Biomarkers; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D007529:Isoflavones; D048789:Phytoestrogens; D012333:RNA, Messenger; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen; C016601:afimoxifene; D004958:Estradiol; C004742:daidzein; D019833:Genistein; C512478:EGFR protein, human; D066246:ErbB Receptors