Lycopene inhibits growth of human colon cancer cells via suppression of the Akt signaling pathway.
The aberrant regulation of the phosphoinositide 3-kinase/Akt survival signaling pathway in cancer has prompted significant interest in suppression of this pathway to treat cancer. Previous studies identified an important role for phosphoinositide 3-kinase/Akt in colon cancer progression. Lycopene, a major component in tomato, exhibited potential anti-carcinogenic activity. Consumption of tomato has been associated with reduced risk of several types of human cancer. However, the inhibitory mechanisms of lycopene on the proliferation of human colon cancer have not been studied well yet. Thus we investigated the inhibitory effects of lycopene on the Akt signaling pathway in human colon cancer HT-29 cells. Lycopene inhibited cell proliferation in human colon cancer HT-29 cells with a IC(50) value of 10 microM. Lycopene treatment suppressed Akt activation and non-phosphorylated beta-catenin protein level in human colon cancer cells. Immunocytochemical results indicated that lycopene increased the phosphorylated form of beta-catenin proteins. These effects were also associated with reduced promoter activity and protein expression of cyclin D1. Furthermore, lycopene significantly increased nuclear cyclin-dependent kinase inhibitor p27(kip)abundance and inhibited phosphorylation of the retinoblastoma tumor suppressor protein in human colon cancer cells. In conclusion, lycopene inhibited cell proliferation of human colon cancer cells via suppression of the Akt signaling pathway and downstream targeted molecules.
Biomedical Science Laboratory, Department of Nutrition, China Medical University, Taichung, Taiwan. vincenttang@mail.cmu.edu.tw
Feng-Yao
FY
Tang
Chung-Jin
CJ
Shih
Li-Hao
LH
Cheng
Hsin-Jung
HJ
Ho
Hung-Jiun
HJ
Chen
D002338:Carotenoids / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000737:chemistry / Q000473:pathology*; D019938:Cyclin D1 / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D000077276:Lycopene; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects*; D051176:beta Catenin / Q000032:analysis
D002338:Carotenoids; D019938:Cyclin D1; D000077276:Lycopene; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D051176:beta Catenin