Glucocorticoid receptor alpha and beta variant expression is associated with ASF/SF2 splicing factor upregulation in HT-29 colon cancer and MCF-7 breast carcinoma cells.
OBJECTIVE
Transcriptional activity of NF-kappaB is inhibited by the liganded glucocorticoid receptor (GR), which exists mainly in two splice variants as functional GRalpha and nonfunctional GRbeta. We investigated the effect of 5-aza-2'-deoxycytidine (5-dAzaC), trichostatin A (TSA), and sodium butyrate (NaBu) on GRalpha,GRbeta and ASF/SF2 splicing factor expression in HT-29 colon and MCF-7 breast carcinoma cells.


METHODS
HT-29 and MCF-7 cells were cultured in the absence or in the presence of 5-dAzaC, TSA, and NaBu, followed by RNA and protein isolation. The transcript and protein levels of GRalpha, GRbeta ASF/SF2 were determined by reverse transcription, real-time quantitative PCR and Western blot analysis.


RESULTS
We found that 5-dAzaC, TSA, and NaBu lead to an increase in GRalpha and ASF/SF2 transcript levels and a decrease in GRbeta transcript levels in HT-29 and MCF-7 cells. The 5-dAzaC, TSA, and NaBu resulted in increased GRalpha and ASF/SF2 protein levels and GRbeta protein downregulation in HT-29 cells. The most increased GRalpha protein expression in MCF-7 cells was observed with NaBu. However, all of these compounds inhibited GRbeta protein expression in MCF-7 cells. The MCF-7 cells treated with NaBu demonstrated a remarkable increase in ASF/SF2 protein expression.


CONCLUSIONS
Because NF-kappaB is considered to be a factor in the augmentation of malignant properties of cells, treatment of tumors with 5-dAzaC, TSA, and NaBu may provide a novel approach to the enhancement of therapeutic effects of glucocorticoids in epithelial carcinomas.
Department of Biochemistry and Molecular Biology, Poznan University of Medical Sciences, Poznan, Poland.
Hanna
H
Piotrowska
Pawel P
PP
Jagodzinski
D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001943:Breast Neoplasms / Q000378:metabolism; D002087:Butyrates / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000378:metabolism; D000077209:Decitabine; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019073:HT29 Cells; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D009687:Nuclear Proteins / Q000187:drug effects / Q000378:metabolism*; D016601:RNA-Binding Proteins; D011965:Receptors, Glucocorticoid / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics; D000068103:Serine-Arginine Splicing Factors
D002087:Butyrates; D004791:Enzyme Inhibitors; D006877:Hydroxamic Acids; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D011965:Receptors, Glucocorticoid; C411470:glucocorticoid receptor alpha; C121943:glucocorticoid receptor beta; D000068103:Serine-Arginine Splicing Factors; C012589:trichostatin A; D000077209:Decitabine; D001374:Azacitidine