[Effect of 14-3-3sigma on transcriptional activity of p73 gene].
OBJECTIVE
p53 gene is the main regulator of 14-3-3sigma. Activated p53 could induce the expression of 14-3-3sigma, while 14-3-3sigma stabilizes the expression of p53 and enhances its transcriptional activity. p63 and p73, the members of p53 family, also have some functions similar to p53. This study was to investigate the effect of 14-3-3sigma on the transcriptional activity of p73.


METHODS
Luciferase reporter assay, reverse transcription-polymerase chain reaction (RT-PCR), and Western blot were used to evaluate the effect of 14-3-3sigma on the transcriptional activity of p73 in p53-deficient human lung carcinoma cell line H1299. Colony formation test was used to evaluate the effect of 14-3-3sigma on the transcriptional activity of p73 in p53-mutant human breast cancer cell line MDA-MB-436.


RESULTS
The luciferase activities induced by bax and p21WAF1 promotors were significantly higher in p73-transfected H1299 cells than in control H1299 cells (P<0.01), and were further increased by the transfection of p73 (25 ng) and 14-3-3sigma (100, 200, and 400 ng) in a dose-dependent manner (P<0.01). The expression of bax and p21WAF1 were higher in p73-transfected H1299 cells than in control H1299 cells, and were significantly higher in p73-and 14-3-3sigma-transfected H1299 cells than in p73-transfected H1299 cells (P<0.01). The number of colonies was fewer in p73-transfected MDA-MB-436 cells than in control MDA-MB-436 cells, and the colonies were significantly smaller in p73-and 14-3-3sigma-transfected H1299 cells than in p73-transfected H1299 cells (P<0.01).


CONCLUSIONS
14-3-3sigma can enhance the transcriptional activity of p73 in a dose-dependent manner.
Sang
Mei-Xiang
MX
Department of The First General Surgery, The Fourth Affiliated Hospital, Hebei Medical University, Shijiazhuang, Hebei, 050011, PR China.
Geng
Cui-Zhi
CZ
Shan
Bao-En
BE
D048948:14-3-3 Proteins; D014408:Biomarkers, Tumor / Q000008:administration & dosage / Q000494:pharmacology*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003114:Colony-Forming Units Assay; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005092:Exonucleases / Q000008:administration & dosage / Q000494:pharmacology*; D005095:Exoribonucleases; D005260:Female; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology; D009363:Neoplasm Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis* / Q000235:genetics
D048948:14-3-3 Proteins; D014408:Biomarkers, Tumor; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D051028:bcl-2-Associated X Protein; D008156:Luciferases; D005092:Exonucleases; D005095:Exoribonucleases; C413442:SFN protein, human