Adenovirus-mediated transfer of the PTEN gene inhibits human colorectal cancer growth in vitro and in vivo.
The tumor-suppressor gene PTEN encodes a multifunctional phosphatase that is mutated in a variety of human cancers. PTEN inhibits the phosphatidylinositol 3-kinase pathway and downstream functions, including activation of Akt/protein kinase B (PKB), cell survival, and cell proliferation in tumor cells carrying mutant- or deletion-type PTEN. In such tumor cells, enforced expression of PTEN decreases cell proliferation through cell-cycle arrest at G1 phase accompanied, in some cases, by induction of apoptosis. More recently, the tumor-suppressive effect of PTEN has been reported in ovarian and thyroid tumors that are wild type for PTEN. In the present study, we examined the tumor-suppressive effect of PTEN in human colorectal cancer cells that are wild type for PTEN. Adenoviral-mediated transfer of PTEN (Ad-PTEN) suppressed cell growth and induced apoptosis significantly in colorectal cancer cells (DLD-1, HT29, and SW480) carrying wtPTEN than in normal colon fibroblast cells (CCD-18Co) carrying wtPTEN. This suppression was induced through downregulation of the Akt/PKB pathway, dephosphorylation of focal adhesion kinase (FAK) and mitogen-activated protein kinase (MAPK) and cell-cycle arrest at the G2/M phase, but not the G1 phase. Furthermore, treatment of human colorectal tumor xenografts (HT-29, and SW480) with Ad-PTEN resulted in significant (P=0.01) suppression of tumor growth. These results indicate that Ad-PTEN exerts its tumor-suppressive effect on colorectal cancer cells through inhibition of cell-cycle progression and induction of cell death. Thus Ad-PTEN may be a potential therapeutic for treatment of colorectal cancers.
Saito
Y
Y
Department of Thoracic and Cardiovascular Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Swanson
X
X
Mhashilkar
A M
AM
Oida
Y
Y
Schrock
R
R
Branch
C D
CD
Chada
S
S
Zumstein
L
L
Ramesh
R
R
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D015153:Blotting, Western / Q000379:methods; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D004268:DNA-Binding Proteins / Q000235:genetics; D004789:Enzyme Activation; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage* / Q000235:genetics; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D051059:PTEN Phosphohydrolase; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000235:genetics; D051057:Proto-Oncogene Proteins c-akt; D014157:Transcription Factors / Q000235:genetics; D014183:Transplantation, Heterologous; D025521:Tumor Suppressor Proteins / Q000235:genetics*
D004268:DNA-Binding Proteins; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; C448021:glycogen synthase kinase 3 alpha; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D020169:Caspases