Induction of apoptosis in endometrial cancer cells by psammaplysene A involves FOXO1.
OBJECTIVE
Endometrial cancer is the most common type of gynecologic cancer in the United States. In this study, we propose that a marine sponge compound, psammaplysene A (PsA) induces apoptosis in endometrial cancer cells through forced nuclear expression of FOXO1.


METHODS
Ishikawa and ECC1 cells were treated with varying doses of PsA. FOXO1 protein localization was observed using immunofluorescent staining of cells. The effects of PsA on cell viability and proliferation were assessed using a cell viability assay and a BrdU incorporation assay respectively. Cell cycle analysis was performed using flow cytometry. To assess the role of FOXO1 in PsA-induced apoptosis, FOXO1 was silenced in ECC1 cells using siRNA technique, and overexpressed in Ishikawa cells using an adenovirus containing FOXO1 cDNAs. Western blots were used to measure levels of FOXO1 and cleaved PARP proteins.


RESULTS
Treatment of both ECC1 and Ishikawa cells with PsA caused an increase in nuclear FOXO1 protein, a dramatic decrease in cell viability of approximately 5-fold (p<0.05) and minimal effect on proliferation. Furthermore, treatment of cells with PsA doubled the percentage of cells in the G2/M phase (p<0.05). PsA induced apoptosis in endometrial cancer cells. When FOXO1 was silenced in ECC1 cells and treated with PsA, the incidence of apoptosis decreased. In addition, overexpression of FOXO1 with PsA treatment increased apoptosis.


CONCLUSIONS
Increasing nuclear FOXO1 function is important for the induction of apoptosis of endometrial cancer cells by PsA.
Berry
Emily
E
Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Northwestern University, Chicago, IL 60611, USA.
Hardt
Jennifer L
JL
Clardy
Jon
J
Lurain
John R
JR
Kim
J Julie
JJ
D017209:Apoptosis / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D016889:Endometrial Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D005260:Female; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D016195:G2 Phase / Q000187:drug effects; D006801:Humans; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000494:pharmacology
C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D034741:RNA, Small Interfering; C501142:psammaplysene A; D014443:Tyrosine