Activation of PI3K-Akt signaling pathway promotes prostate cancer cell invasion.
Activated phosphoinositide 3-kinase (PI3K) and its downstream target Akt/PKB are important signaling molecules and key survival factors involved in the control of cell proliferation, apoptosis and oncogenesis. We investigated the role of the PI3K-Akt signaling pathway in the invasion of prostate cancer cell lines and activation of this pathway in primary human prostate tumors. Treatment of human prostate cancer cells viz. LNCaP, PC-3 and DU145 with PI3K pharmacological inhibitor, LY294002, potentially suppressed the invasive properties in each of these cell lines. Restoration of the PTEN gene to highly invasive prostate cancer PC-3 cells or expression of a dominant negative version of the PI3K target, Akt also significantly inhibited invasion and downregulated protein expression of urokinase-type plasminogen activator (uPA) and matrix metalloproteinase (MMP)-9, markers for cell invasion, indicating a central role of the PI3K-Akt pathway in this process. Immunoblot analysis of PI3K and total/activated levels of Akt showed increased protein levels of catalytic (p110alpha/beta) and regulatory (p85) subunits of PI3K and constitutive Akt activation in high-grade tumors compared to low-grade tumor and benign tissue. Immunohistochemical analyses further confirmed a progressive increase in p-Akt (p-Ser473) levels but not of total-Akt (Akt1/2) in cancer tissues compared to benign specimens. A successive increase in p-Akt expression was further noted in specimens serially obtained from individuals with time-course disease progression. Taken together, these results suggest that aberrant activation of PI3K-Akt pathway may contribute to increased cell invasiveness and facilitate prostate cancer progression.
Shukla
Sanjeev
S
Department of Urology, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland 44106, OH, USA.
Maclennan
Gregory T
GT
Hartman
Douglas J
DJ
Fu
Pingfu
P
Resnick
Martin I
MI
Gupta
Sanjay
S
D015153:Blotting, Western; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008297:Male; D009025:Morpholines / Q000494:pharmacology; D009361:Neoplasm Invasiveness; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014162:Transfection
D002867:Chromones; D004791:Enzyme Inhibitors; D049452:Green Fluorescent Proteins; D009025:Morpholines; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494929:PTEN protein, human