PI3K/Akt and GSK-3β prevents in a differential fashion the malignant phenotype of colorectal cancer cells.
OBJECTIVE
During colorectal cancer progression, the loss of differentiation and cell-cell adhesion as well as a higher migratory potential are well-defined features; however, the signaling mechanism governing these events is not fully elucidated. The aim of this study was to investigate the role that PI3K and downstream effectors play in controlling colon cancer malignant phenotypes.


METHODS
HCT-116 cells, a human model of colon cancer, which are highly metastatic and undifferentiated, were treated with LY294002, a specific inhibitor of PI3K. Cell differentiation and apical junctional complex (AJC) formation were monitored using alkaline phosphatase and electron microscopy analysis. Immunofluorescence and Western blotting were used to accompany the subcellular localization of AJC proteins. PI3K downstream molecules were analyzed by western blotting, and proliferation, wound healing, and colony formation techniques to determine malignant phenotype alterations.


RESULTS
PI3K inhibition increased alkaline phosphatase activity, led to an enterocyte-like growth and formed a functional AJC. LY294002 treatment was able to recruit E-cadherin, β-catenin, claudin-3, and ZO-1 to the cell-cell contact region, and this effect was essential for AJC assembly and association of these proteins to the cytoskeleton. Furthermore, we provided evidence that PI3K inhibition leads to a decrease in p-Akt and p-GSK-3β and increased p-β-catenin levels, which in turn controlled cell proliferation, motility, and colony formation.


CONCLUSIONS
Our results demonstrate that PI3K/Akt and GSK-3β prevents in a differential fashion the malignant phenotype of HCT-116 colorectal cancer cells, which could constitute a potential therapeutic target for treatment of this cancer type.
de Araújo
Wallace Martins
WM
Divisão de Biologia Celular, Instituto Nacional de Câncer, Rio de Janeiro, Rua André Cavalcanti 37, 5° andar, 20230-051 Rio de Janeiro, RJ, Brazil.
Vidal
Flavia Castello Branco
FC
de Souza
Waldemir Fernandes
WF
de Freitas
Julio César Madureira
JC
de Souza
Wanderley
W
Morgado-Diaz
Jose Andres
JA
D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors; D015820:Cadherins / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002867:Chromones / Q000627:therapeutic use*; D003114:Colony-Forming Units Assay; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D009025:Morpholines / Q000627:therapeutic use*; D010641:Phenotype; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D014945:Wound Healing / Q000187:drug effects; D051176:beta Catenin / Q000378:metabolism
D015820:Cadherins; D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D051176:beta Catenin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D000469:Alkaline Phosphatase