Claudin-4 overexpression in epithelial ovarian cancer is associated with hypomethylation and is a potential target for modulation of tight junction barrier function using a C-terminal fragment of Clostridium perfringens enterotoxin.
BACKGROUND
Claudin-4, a tight junction (TJ) protein and receptor for the C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE), is overexpressed in epithelial ovarian cancer (EOC). Previous research suggests DNA methylation is a mechanism for claudin-4 overexpression in cancer and that C-CPE acts as an absorption-enhancing agent in claudin-4-expressing cells. We sought to correlate claudin-4 overexpression in EOC with clinical outcomes and TJ barrier function, investigate DNA methylation as a mechanism for overexpression, and evaluate the effect of C-CPE on the TJ.


METHODS
Claudin-4 expression in EOC was quantified and correlated with clinical outcomes. Claudin-4 methylation status was determined, and claudin-4-negative cell lines were treated with a demethylating agent. Electric cell-substrate impedance sensing was used to calculate junctional (paracellular) resistance (Rb) in EOC cells after claudin-4 silencing and after C-CPE treatment.


RESULTS
Claudin-4 overexpression in EOC does not correlate with survival or other clinical endpoints and is associated with hypomethylation. Claudin-4 overexpression correlates with Rb and C-CPE treatment of EOC cells significantly decreased Rb in a dose- and claudin-4-dependent noncytotoxic manner.


CONCLUSIONS
C-CPE treatment of EOC cells leads to altered TJ function. Further research is needed to determine the potential clinical applications of C-CPE in EOC drug delivery strategies.
Litkouhi
Babak
B
Department of Obstetrics, Gynecology and Reproductive Biology, Division of Gynecologic Oncology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. blitkouhi@partners.org
Kwong
Joseph
J
Lo
Chun-Min
CM
Smedley
James G
JG
McClane
Bruce A
BA
Aponte
Margarita
M
Gao
Zhijian
Z
Sarno
Jennifer L
JL
Hinners
Jennifer
J
Welch
William R
WR
Berkowitz
Ross S
RS
Mok
Samuel C
SC
Garner
Elizabeth I O
EI
D045744:Cell Line, Tumor; D062506:Claudin-4; D003016:Clostridium perfringens / Q000502:physiology*; D019175:DNA Methylation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems / Q000379:methods; D004768:Enterotoxins / Q000008:administration & dosage* / Q000633:toxicity; D005260:Female; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D009375:Neoplasms, Glandular and Epithelial / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000008:administration & dosage* / Q000633:toxicity; D019108:Tight Junctions / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology*
C568157:CLDN4 protein, human; D062506:Claudin-4; D004768:Enterotoxins; D008565:Membrane Proteins; D010446:Peptide Fragments; C035598:enterotoxin, Clostridium