[Over expression of hyperplasia suppressor gene inhibits the malignant phenotype of breast cancer cell].
OBJECTIVE
To investigate the effect of over expression of human hyperplasia suppressor gene (HSG) on proliferation, invasion, apoptosis and cell cycle of human breast cancer cells and to determine the relationship between HSG and Ras-dependent signaling pathway.


METHODS
Full length HSG coding sequences were cloned into plasmid pcDNA3.0. The recombinant plasmids were transfected into MDA-MB-231, a highly malignant breast cancer cell line. Vacant pcDNA3.0 was used as the control. MTT, Matrigel transwell assay and flow cytometric analysis were used to test for proliferation, invasion, cell cycle distribution and apoptosis of tumor cells after transient transfection of HSG.GST-pulldown and Western blotting assays were performed to investigate the activity of Ras protein.


RESULTS
HSG transfection inhibited proliferation of MDA-MB-231 cells, and significantly decreased the number of invading cells in Matrigel transwell assay compared with the vector/231 group (78.5 +/- 5.8 vs. 131.1 +/- 14.5) cells. FACS analyses demonstrated that compared with the vector/231 group, up-regulation of HSG promoted breast cancer cell apoptosis [(35.8 +/- 4.8)% vs. (25.6 +/- 3.5%)] and induced G(0)/G(1) phase arrest [(56.3 +/- 2.3)% vs. (50.4 +/- 1.9%)] after transfection for 18 hours. Furthermore, GST-pulldown assay showed that over-expression of HSG remarkably decreased the activity of Ras (about 65% lower than control).


CONCLUSIONS
HSG exibits multiple anticancer functions in breast cancer cells including inhibition of proliferation and in vitro invasion, G(0)/G(1) arrest and promotion of apoptosis. Besides, inhibition of Ras-dependent signaling pathway may be involved in these processes.
Zhang
Yang
Y
Department of Pathology, Peking University Health Science Center, Beijing 100191, China.
DU
Qiang
Q
Qiu
Xiao-yan
XY
Tian
Xin-xia
XX
Fang
Wei-gang
WG
D000818:Animals; D017209:Apoptosis; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D020558:GTP Phosphohydrolases; D015972:Gene Expression Regulation, Neoplastic; D005822:Genetic Vectors; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D041681:NIH 3T3 Cells; D009361:Neoplasm Invasiveness; D010957:Plasmids; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D015854:Up-Regulation; D018631:ras Proteins / Q000378:metabolism
D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011994:Recombinant Proteins; D020558:GTP Phosphohydrolases; C470018:MFN2 protein, human; D018631:ras Proteins