INHBA overexpression promotes cell proliferation and may be epigenetically regulated in esophageal adenocarcinoma.
BACKGROUND
The expression, mechanisms of regulation, and functional impact of activin (INHBA) in esophageal adenocarcinoma (EAC) have not been fully defined.


METHODS
INHBA expression was examined in 46 esophageal samples (nine Barrett's metaplasia (BM); seven BM/low-grade dysplasia; eight low-grade dysplasia; seven high-grade dysplasia; 15 EAC) using oligonucleotide microarrays and real-time reverse transcription-polymerase chain reaction (RT-PCR) and in 90 tissue samples (79 EAC; 8 dysplastic; 3 BM) using immunohistochemistry (IHC). The proliferation of EAC cell lines FLO and OE-33 was examined after treatment with exogenous activin. The proliferation of OE-33 was also examined after treatment with the activin inhibitor follistatin and INHBA-targeting siRNA. OE-33 and FLO cells were treated with 5-aza-2'deoxycytidine (5-AZA) and trichostatin A to investigate the role of epigenetic regulation in INHBA expression.


RESULTS
Primary EACs expressed 5.7-times more INHBA mRNA than BM samples on oligonucleotide microarray. Transcript overexpression in EAC relative to BM was confirmed on real-time RT-PCR. IHC suggested higher INHBA protein expression in EAC (69.6%) than in the dysplastic (37.5%) and BM samples (33.3%). FLO and OE-33 treated with activin demonstrated increased proliferation, and OE-33 cells treated with follistatin and INHBA-targeting siRNA demonstrated reduced proliferation, relative to untreated controls. Treatment of FLO cells with trichostatin A and 5-AZA up-regulated INHBA mRNA and protein production by real time RT-PCR and IHC.


CONCLUSIONS
INHBA is overexpressed in EAC relative to dysplastic and BM tissue. INHBA overexpression may promote cell proliferation and may be affected by promoter demethylation and histone acetylation in EAC cell lines.
Seder
Christopher W
CW
Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.
Hartojo
Wibisono
W
Lin
Lin
L
Silvers
Amy L
AL
Wang
Zhuwen
Z
Thomas
Dafydd G
DG
Giordano
Thomas J
TJ
Chen
Guoan
G
Chang
Andrew C
AC
Orringer
Mark B
MB
Beer
David G
DG
D028341:Activins / Q000494:pharmacology; D000230:Adenocarcinoma / Q000473:pathology*; D000818:Animals; D002417:Cattle; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D044127:Epigenesis, Genetic; D004938:Esophageal Neoplasms / Q000473:pathology*; D038681:Follistatin / Q000494:pharmacology; D051548:Histone Acetyltransferases / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D028322:Inhibin-beta Subunits / Q000032:analysis / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D034741:RNA, Small Interfering / Q000235:genetics
D038681:Follistatin; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C103008:inhibin beta A subunit; D028341:Activins; D028322:Inhibin-beta Subunits; D051548:Histone Acetyltransferases; C110880:histone acetyltransferase type B complex