RT Journal Article
SR Electronic
T1 Cytokeratin 18 Expression Inhibits Cytokine-Induced Death of Cervical Cancer Cells
JF International Journal of Gynecologic Cancer
JO Int J Gynecol Cancer
FD BMJ Publishing Group Ltd
SP 1474
OP 1481
DO 10.1111/IGC.0b013e3181fc3a03
VO 20
IS 9
A1 Brian T. Sullivan
A1 Jessica A. Cherry
A1 Hideo Sakamoto
A1 Luiz E. Henkes
A1 David H. Townson
A1 Bo R. Rueda
YR 2010
UL http://ijgc.bmj.com/content/20/9/1474.abstract
AB Objectives: In cervical cancer, increased cytokeratin 18 (CK18) filament expression is associated with disease progression. However, it may also provide resistance to cytokine-induced apoptosis. The present study tested whether CK18 expression influences susceptibility to cytokine-induced apoptosis.Methods: The cervical cancer cell lines C-4II (high CK18 expression), ME-180 (low CK18 expression), and 2 subtypes of HeLa cells containing or lacking CK18 expression (CK18+ and CK18− cells, respectively) were exposed to vehicle (control), Fas ligand (FasL) (50 ng/mL), or tumor necrosis factor α (TNF-α; 10 ng/mL) without/with cycloheximide (CHX; 2.5 μg/mL) to test the hypothesis that diminished CK18 expression increases susceptibility to cytokine-induced apoptosis.Results: Flow cytometric analysis of cell death via TUNEL staining revealed that cytokine-induced apoptosis was 2-fold greater in ME-180 cells than C-4II cells in response to FasL+CHX or TNF-α+CHX (P < 0.05). Similarly, there was a higher incidence of FasL-induced apoptosis in CK18− HeLa cells (23% and 91% apoptotic for FasL and FasL+CHX, respectively) than CK18+ HeLa cells (1% and 11%, respectively; P < 0.05). Surprisingly, TNF-α had no effect on either CK18+ or CK18− HeLa cells (P > 0.05). Caspase 3 activity was greater in CK18− HeLa cells than in CK18+ HeLa cells at 8 and 18 hours after FasL treatment (P < 0.05), an effect abrogated by the caspase 8 inhibitor IETD-fmk (P < 0.05).Conclusions: Cervical cancer cells with diminished CK18 expression are more susceptible to cytokine-induced apoptosis, particularly in response to FasL treatment. These observations suggest that relative CK18 expression is an important factor when considering therapeutic strategies to enhance immune cell-mediated death of cervical cancer cells.