BACKGROUND AND OBJECTIVEAs a barrier to metastases, cells normally undergo apoptosis after they lose contact with their extra cellular matrix (ECM). This process has been termed "anoikis". Tumour cells that acquire malignant potential have developed mechanisms to resist anoikis and thereby survive after detachment from their primary site while traveling through the lymphatic and circulatory systems. This "anoikis resistance" is considered the first step to tumor metastases. The aim of this study was to screen metastasis-associated genes from anoikis resistant and adherent growth A549 lung cancer cell by Human Genome Array.

METHODSEstablish anoikis resistant A549 lung cancer cell lines by using poly-hydroxyethyl methacrylate resin processed petri dishes, which causes cell free from adherent. The different expressed gene between anoikis resistant A549 cell and adherent growth A549 cell was tested using human V2.0 whole-genome oligonucleotide microarray, a product of Capitalbio Corporation, Beijing. Screen metastasis-associated genes.

RESULTS745 different expressed genes were screened, including 63 highly metastasis-associated genes.

CONCLUSIONThe successfully established anoikis resistant A549 cell lines and screened different expressed genes provide us basis for further research on metastasis of lung cancer.

Anoikis ; genetics ; physiology ; Cell Line, Tumor ; Flow Cytometry ; Gene Expression Profiling ; Genome, Human ; genetics ; Humans ; Lung Neoplasms ; genetics ; Oligonucleotide Array Sequence Analysis

OBJECTIVETo investigate the effect and mechanisms of tumor suppressor gene PTEN on the induction of anoikis of hepatocellular carcinoma SMMC-7721 cells.

METHODSSMMC-7721 cells were transfected with GFP plasmids containing wild-type PTEN or phosphatase inactivating mutant PTEN (C124A-PTEN) in vitro; The PTEN expression and the phosphorylation levels of focal adhesion kinase (FAK) and protein kinase B (PKB/Akt) were detected by Western blotting; Flow cytometry assay and laser scanning confocal microscopy were used to analyze apoptosis in adherent and non-adherent cells.

RESULTSCompared with the control, PTEN expression in the cells transfected with wild-type PTEN increased to 248%, while the phosphorylation level of FAK and Akt decreased 65.2% and 89.1%, respectively; and the anoikis percentage increased from 9.5% to 31.3%. In the cells transfected with C124A-PTEN, neither the phosphorylation of FAK and Akt nor the anoikis percentage had obviously changed, although the PTEN expression enhanced dramatically in comparison with the control.

CONCLUSIONThrough its phosphatase activity, tumor suppressor gene PTEN can suppress the phosphorylation of FAK and Akt, and induce anoikis in hepatocellular carcinoma cells.

Anoikis ; physiology ; Carcinoma, Hepatocellular ; pathology ; Focal Adhesion Protein-Tyrosine Kinases ; metabolism ; Humans ; Liver Neoplasms ; pathology ; PTEN Phosphohydrolase ; biosynthesis ; genetics ; Phosphoric Monoester Hydrolases ; metabolism ; Phosphorylation ; Tumor Cells, Cultured

Cyclooxygenase-2 (COX-2) has been reported to be associated with tumor development and progression as well as to protect cells from apoptosis induced by various cellular stresses. Through a tetracycline-regulated COX-2 overexpression system, we found that COX-2 inhibits detachment-induced apoptosis (anoikis) in a human bladder cancer cell line, EJ. We also found that the inhibition of anoikis by COX-2 results from activation of the PI-3K/Akt pathway as evidenced by suppression of the COX-2 effect on anoikis by a PI-3K inhibitor, LY294002. Furthermore, COX-2 enhanced Mcl-1 expression in the anoikis process, implying that Mcl-1 also may be involved in mediating the survival function of COX-2. Together, these results suggest that COX-2 inhibits anoikis by activation of the PI-3K/Akt pathway and probably by enhancement of Mcl-1 expression in human bladder cancer cells. This anti- anoikis effect of COX-2 may be a part of mechanisms to promote tumor development and progression.
1-Phosphatidylinositol 3-Kinase/*metabolism ; Anoikis/*physiology ; Bladder Neoplasms/*metabolism/pathology ; Enzyme Activation ; Humans ; Neoplasm Proteins/*metabolism ; Prostaglandin-Endoperoxide Synthase/*metabolism ; Protein-Serine-Threonine Kinases/*metabolism ; Proto-Oncogene Proteins/*metabolism ; Proto-Oncogene Proteins c-bcl-2/*metabolism ; Research Support, Non-U.S. Gov't ; Signal Transduction ; Transfection ; Tumor Cells, Cultured