[Inhibitory effect of N-terminal 24 amino acids of the p55 gamma, a regulatory subunit of phosphoinositide 3-kinase, on proliferation of colon carcinoma cell line HT29].
OBJECTIVE
p55 gamma is one of the regulatory subunits of phosphoinositide 3-kinase (PI3K), which plays an important role in the regulation of PI3K activity. This study was to explore the inhibitory effect of the N-terminal 24 amino acids of the p55 gamma on proliferation of colon carcinoma cell line HT29.


METHODS
Ad-N24p55-GFP, containing N-terminal 24 amino acids of the p55 gamma, and control vector Ad-GFP were constructed, and used to infect HT29 cells. The cell cycle progression was detected using flow cytometry. DNA synthesis was analyzed using the BrdU/PI method. The nude mice model bearing HT29 xenograft tumors was used to study the effect of Ad-N24p55-GFP against the tumor.


RESULTS
Compared with cells infected with Ad-GFP, cells infected with Ad-N24p55-GFP at the G0/G1 phase were increased from 65.11% to 73.39% P < 0.05, and cells at S and G2/M phases were decreased from 17.37% to 15.08% and from 17.51% to 11.13%, respectively; BrdU-positive cells were decreased from 24.82% to 9.27%. In the nude mice model, the tumor growth was inhibited after the administration of Ad-N24p55-GFP. The tumor weight was (0.32+/-0.08)g vs. (10.67+/-0.3)g and (0.72+/-0.28)g in the Ad-N24P55-GFP group,the blank control group and the Ad-GFP group, respectively.


CONCLUSIONS
In HT29 cells, overexpression of the N-terminal 24 amino acids of the p55 gamma can induce cell cycle arrest, inhibit DNA synthesis and inhibit tumor growth in the nude mice model of HT29 xenograft tumors.
Molecular Medical Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, P. R. China.
Gui-Hua
GH
Wang
Xue-Lai
XL
Luo
Li
L
Sun
Yu
Y
Deng
Xiao-Lan
XL
Li
De-Ding
DD
Tao
Jun-Bo
JB
Hu
Jian-Ping
JP
Gong
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002453:Cell Cycle; D004273:DNA, Neoplasm / Q000096:biosynthesis*; D005260:Female; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D019073:HT29 Cells; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D047368:Tumor Burden / Q000187:drug effects*
D004273:DNA, Neoplasm; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D019869:Phosphatidylinositol 3-Kinases; C523442:PIK3R3 protein, human