The in vitro and in vivo effects of 2-(4-morpholinyl)-8-phenyl-chromone (LY294002), a specific inhibitor of phosphatidylinositol 3'-kinase, in human colon cancer cells.
OBJECTIVE
Phosphatidylinositol 3'-kinase (PI3K) and Akt/protein kinase B(PKB) allow for escape from apoptosis in various human cancer cells. We postulated that 2-(4-morpholinyl)-8-phenyl-chromone (LY294002), a PI3K inhibitor, should inactivate Akt/PKB, consequently inhibiting cell proliferation and inducing apoptosis in vitro and in vivo.


METHODS
Human colon cancer cell lines (DLD-1, LoVo, HCT15, and Colo205) and their mouse xenografts (DLD-1 and LoVo) were used in this study. The expression of phosphorylated Akt (Ser(473)) and apoptosis in cancer cells were determined by immunoblotting and immunohistochemistry. To evaluate the activity of caspase-3 in culturing cells, the caspase colorimetric assay was also performed.


RESULTS
LY294002 demonstrated a remarkable growth-inhibitory and apoptosis-inducing effect in these colon cancer cell lines, with decreased expression of phosphorylated Akt (Ser(473)). However, there was a great discrepancy between the sensitivity for LY294002 and the level of expression of phosphorylated Akt. Although the LoVo and Colo205 cells exhibited high sensitivity to LY294002 with increased apoptosis, the DLD-1 and HCT15 cells did not show rapid induction of apoptosis. The caspase-3 activity was significantly high in the LoVo cells but not in the DLD-1 cells. In the experiments using mouse xenografts, we found that LY294002 administration in vivo also resulted in suppression of tumor growth and induction of apoptosis, especially in the LoVo tumors, and therefore showed remarkable effectiveness in the mouse peritonitis carcinomatosa model.


CONCLUSIONS
PI3K-Akt/PKB plays an important role in colon cancer development and progression by helping to promote cell growth and allowing cells to escape apoptosis. These results propose the usefulness of LY294002 as an antitumoral agent for patients with colorectal cancer.
Semba
Shuho
S
First Department of Pathology, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata 990-9585, Japan. senba@med.id.yamagata-u.ac.jp
Itoh
Nanami
N
Ito
Masafumi
M
Harada
Masaru
M
Yamakawa
Mitsunori
M
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000201:enzymology* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D066298:In Vitro Techniques; D051379:Mice; D016513:Mice, SCID; D009025:Morpholines / Q000494:pharmacology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000502:physiology
D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020169:Caspases