2-Methoxyestradiol attenuates phosphatidylinositol 3-kinase/Akt pathway-mediated metastasis of gastric cancer.
The major obstacle for the treatment of gastric cancer is recurrence and metastasis; yet, its molecular mechanism is largely unknown. 2-methoxyestradiol (2-ME), a metabolite of the estradiol-17beta, has recently been demonstrated to have multifactorial effects against tumor proliferation and angiogenesis; how these effects are interrelated and act cooperatively is the key question to be elucidated. Akt activation was shown to promote cancer cell invasiveness, and inhibition of Akt phosphorylation by 2-ME was also noted. We herein investigated the significance of PI3K/Akt activation in gastric cancer metastasis and the anti-metastatic effect of 2-ME through attenuation of Akt activity. Immunohistochemistry of PI3K, phosphorylated Akt (p-Akt) and phosphorylated Erk (p-Erk) was performed in tumors from 56 gastric cancer patients, and a significant correlation between PI3K/p-Akt and tumor stage/prognosis was demonstrated (p < 0.05). An in vitro study of 7 gastric cancer cell lines showed a remarkable correlation between PI3K and p-Akt. PI3K/p-Akt overexpression was associated with invasiveness/migration; in contrast, phosphorylation of Erk was not shown to be correlated with invasiveness. In addition, metastatic gastric cancer clones expressed a higher level of PI3K/p-Akt. The anti-metastatic effect of a low dose of 2-ME and inactivation of Akt was demonstrated. 2-ME also exhibited an ability to inhibit gastric cancer cell proliferation and induce G2/M cell cycle arrest at a higher concentration than that required for inhibition of migration. We conclude that the activation of PI3K/Akt pathway is involved in the late-stage progression and metastasis of gastric cancer, and attenuation of p-Akt by 2-ME suppresses metastasis.
Lin
Heng-Liang
HL
Department of Medical Research and Education, Taipei Veterans General Hospital, National Yang-Ming University, Taipei, Taiwan.
Yang
Muh-Hwa
MH
Wu
Chew-Wun
CW
Chen
Po-Min
PM
Yang
Yi-Ping
YP
Chu
Yue-Ru
YR
Kao
Chung-Lan
CL
Ku
Hung-Hai
HH
Lo
Jen-Fan
JF
Liou
Jing-Ping
JP
Chi
Chin-Wen
CW
Chiou
Shih-Hwa
SH
D000077584:2-Methoxyestradiol; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003124:Colorimetry; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D005260:Female; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011379:Prognosis; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000187:drug effects
D000970:Antineoplastic Agents; D049452:Green Fluorescent Proteins; D004958:Estradiol; D000077584:2-Methoxyestradiol; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt