Role of PI3K and AKT specific isoforms in ovarian cancer cell migration, invasion and proliferation through the p70S6K1 pathway.
Ovarian cancer is the leading cause of death from gynecological malignancy for women. The amplification of the PI3K catalytic subunit (p110alpha) and the lost function of PTEN are frequently detected in ovarian cancer cells. PI3K plays an important role in tumorigenesis. To specifically inhibit PI3K activity in ovarian cancer cells, we constructed small interfering RNA (siRNA) against p110alpha. The expression of p110alpha siRNA significantly decreased cell migration, invasion, and proliferation compared to the siSCR control cells. The expression of p110alpha siRNA induced CDK inhibitor p27(KIP1) levels, and decreased levels of cyclin D1, CDK4, and phosphorylated retinoblastoma protein. PI3K transmits the mytogenic signal through AKT. AKT has three isoforms in the cells: AKT1, AKT2 and AKT3. We found that inhibition of AKT1 is sufficient to affect cell migration, invasion, and proliferation. Expression of AKT1 siRNA had a similar effect as p110alpha siRNA in the cells. We showed the roles of specific PI3K and AKT isoforms in the cells, which are important to understanding the mechanism of PI3K/AKT signaling in ovarian cancer cells. Both p110alpha and AKT1 siRNA-expressing cells decreased the activation of p70S6K1. Inhibition of p70S6K1 activity by its siRNA also decreased cell migration, invasion, and proliferation associated with the induction of p27(KIP1) levels, and with the inhibition of cell cycle-associated proteins including cyclin D1, CDK2, and phosphorylated retinoblastoma protein. This study demonstrates the important role of the PI3K/AKT/mTOR/p70S6K1 pathway in cell proliferation, migration, and invasion in ovarian cancer cells by using siRNA-mediated gene silencing as a reverse genetic method.
Meng
Qiao
Q
Mary Babb Randolph Cancer Center, Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, WV 26506, USA.
Xia
Chang
C
Fang
Jing
J
Rojanasakul
Yon
Y
Jiang
Bing-Hua
BH
D020134:Catalytic Domain / Q000235:genetics / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D049109:Cell Proliferation; D050760:Cyclin-Dependent Kinase Inhibitor p27; D005260:Female; D006801:Humans; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D009361:Neoplasm Invasiveness; D010051:Ovarian Neoplasms / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D034622:RNA Interference / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
C436291:CDKN1B protein, human; D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; D034741:RNA, Small Interfering; D050760:Cyclin-Dependent Kinase Inhibitor p27; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; C448901:ribosomal protein S6 kinase, 70kD, polypeptide 1