[The changes of PTEN/Akt1 expression and cell proliferation in pulmonary arterial smooth muscle cells induced by hypoxia in rats].
OBJECTIVE
To observe the changes of PTEN/Akt1 mRNA and protein expression level in pulmonary arterial smooth muscle cells (PASMC) induced by hypoxia in rats, and to investigate the role of PTEN/Akt1 signaling pathway in hypoxic pulmonary hypertension (HPH).


METHODS
Pure PASMCs were grown and cultured from rat pulmonary arterial tissues. Semi-quantitative reverse transcription and polymerase chain reaction (RT-PCR) were used to examine PTEN and Akt1 mRNA expression after PASMCs were exposed to hypoxia for 2 h, 8 h, 12 h and 24 h respectively. PTEN/Akt1 protein expressions were determined by Western blotting. The changes of PASMC proliferation were determined by MTT and (3)H-TdR incorporation. Results were expressed as (-x) +/- s. Statistical comparisons of results were performed by t test of Excel 2003. Differences were considered significant if P < 0.05.


RESULTS
PASMCs were induced to keep proliferating by hypoxia. The value of (3)H-TdR was 0.37 +/- 0.06 under normoxia, but was increased with prolonged exposure to hypoxia, reaching 0.70 +/- 0.10 at 12 h (t = 14.29, P < 0.01), being significantly different compared to the normoxia group. The value of MTT was 8374 +/- 545 under normoxia, but was increased by exposure to hypoxia, reaching 11 208 +/- 679 at 24 h (t = 19.56, P < 0.01), being significantly different compared to the normoxia group. The mRNA and protein of PTEN/Akt1 were detectable in all the groups. The values of mRNA, total protein and phosphorylated protein of Akt1 were 0.76 +/- 0.09, 25 +/- 6, 48 +/- 8 respectively in the normoxia group. After exposure to hypoxia, the values were 1.05 +/- 0.09, 41 +/- 7, 79 +/- 14 respectively at 8 h, being significantly different compared to the normoxia group (t = 168.00, 58.54, 8.31, P < 0.01 and P < 0.05), but the values decreased thereafter and returned to the level comparable to the normoxia group at 24 h. The values of mRNA, phosphorylated protein of PTEN were 0.25 +/- 0.06, and 98 +/- 8 respectively in the normoxia group, but were increased after exposure to hypoxia, reaching 0.38 +/- 0.05, and 232 +/- 12 respectively at 24 h, being significantly different compared to the normoxia group (t = 22.04, 50.46, all P < 0.01).


CONCLUSIONS
The results suggested that PTEN/Akt1 signaling pathway might play an important role in hypoxic pulmonary hypertension.
Yi
Bin
B
Institute of Respiratory Diseases, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
Qian
Gui-Sheng
GS
Bai
Li
L
D000818:Animals; D002454:Cell Differentiation; D015687:Cell Hypoxia; D049109:Cell Proliferation; D002478:Cells, Cultured; D006976:Hypertension, Pulmonary / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D051059:PTEN Phosphohydrolase / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D011651:Pulmonary Artery / Q000166:cytology / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats
D012333:RNA, Messenger; C494920:Akt1 protein, rat; D051057:Proto-Oncogene Proteins c-akt; D051059:PTEN Phosphohydrolase