Membrane ERalpha-dependent activation of PKCalpha in endometrial cancer cells by estradiol.
The purpose of this study was to investigate the role of the oestrogen receptor subtypes ERalpha and ERbeta in mediating the non-genomic effects of 17-beta-estradiol (E(2)) in two human endometrial cancer cell lines (RL95-2 and HEC-1A) expressing different levels of these receptor subtypes. Western blotting analysis using phosphorylation site-specific antibodies showed that physiological concentrations of E(2) rapidly (<20 min) activated PKCalpha, but not PKCdelta in the RL95-2 cell line. E(2) had no effect on PKCalpha or PKCdelta activity in the HEC-1A cell line and suppressed basal levels of PKA activity in both cell lines. PKCalpha activation coincided with its membrane translocation. ERalpha was detected in the RL95-2 cell line by Western blotting and RT-PCR but not in the HEC-1A cells, which did express ERbeta. A selective ERalpha agonist PPT had the same effect as E(2) on PKCalpha activation in the RL95-2 cells, but the selective ERbeta agonist DPN had no such effect. A 46kDa variant of ERalpha increased in abundance in the cell membrane within 20 min of E(2) treatment suggesting that ERalpha mediated the E(2) non-genomic effects on PKCalpha through the formation of a membrane associated signalling complex.
Yang
Jian Zhi
JZ
Shanghai First Maternity and Infant Health Hospital, Tongji University, 536 Chang-Le Road, Shanghai, PR China.
O'Flatharta
Cathal
C
Harvey
Brian J
BJ
Thomas
Warren
W
D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D016889:Endometrial Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D006801:Humans; D007202:Indicators and Reagents / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051571:Protein Kinase C-alpha / Q000032:analysis / Q000378:metabolism*; D013778:Tetrazolium Salts / Q000378:metabolism; D013997:Time Factors
D047628:Estrogen Receptor alpha; D007202:Indicators and Reagents; D013778:Tetrazolium Salts; D004958:Estradiol; C496628:PRKCA protein, human; D051571:Protein Kinase C-alpha