PTEN and rapamycin inhibiting the growth of K562 cells through regulating mTOR signaling pathway.
OBJECTIVE
To investigate, in vitro, the regulatory effects of tumor-suppressing gene PTEN on mTOR (mammalian target of rapamycin) signaling pathway, the effects of transfected PTEN and rapamycin on the growth inhibition, and apoptosis induction for human leukemia cell line K562 cells.


METHODS
K562 cells were transfected with recombined adenovirus-PTEN vector containing green fluorescent protein (Ad-PTEN-GFP), followed by the treatment of the cells with or without rapamycin. The proliferation inhibition rate and apoptotic rate of these transfected and/or rapamycin treated K562 cells were measured by MTT assay and flow cytometry (FCM), the expression levels of PTEN-, mTOR-, cyclinD1- and P27kip1- mRNA were measured by real-time fluorescent relative-quantification reverse transcriptional PCR (FQ-PCR), the protein expression levels of PTEN, Akt, p-Akt were detected by western blotting.


RESULTS
The proliferation of K562 cells was inhibited by PTEN gene transfection with/without the treatment of rapamycin. The expression levels of PTEN- and P27kip1- mRNA were up-regulated, and the mTOR- and cyclinD1- mRNA were down-regulated in K562 cells after the cells transfected with wild type PTEN gene and treated with rapamycin.


CONCLUSIONS
PTEN and rapamycin inhibited mTOR expression by acting as an upstream regulator of mTOR. Low dose rapamycin in combination with over-expressed PTEN might have synergistic effects on inhibiting the proliferation and promoting apoptosis of K562 cells.
Cheng
Zhi Y
ZY
Department of Hematology and Heibei Institute of Hematology, The Second Hospital of Hebei Medical University, Shijiazhuang, PR China. dzczy@sohu.com
Guo
Xiao L
XL
Yang
Xiao Y
XY
Niu
Zhi Y
ZY
Li
Shi H
SH
Wang
Su Y
SY
Chen
Hao
H
Pan
Ling
L
D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D048708:Cell Growth Processes / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D019938:Cyclin D1 / Q000096:biosynthesis / Q000235:genetics; D050760:Cyclin-Dependent Kinase Inhibitor p27; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D020014:K562 Cells; D051059:PTEN Phosphohydrolase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D011494:Protein Kinases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction; D020123:Sirolimus / Q000378:metabolism / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases; D014162:Transfection
C436291:CDKN1B protein, human; D047908:Intracellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D019938:Cyclin D1; D050760:Cyclin-Dependent Kinase Inhibitor p27; D011494:Protein Kinases; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D020123:Sirolimus