Abstract
BackgroundIn most women with ovarian cancer, the diagnosis occurs after dissemination of tumor cells beyond ovaries. Several molecular perturbations occur ahead of tumor initiation including loss of lamin A/C. Our hypothesis was that the loss of nuclear structural proteins A type lamins (lamin A/C) transcribed from LMNA gene and substrate for active caspase-6 maybe one of the molecular perturbations. Our objective is to investigate the association between the loss of lamin A/C and the overexpression of caspase-6 in ovarian cancer cells.MethodWestern blotting and immunofluorescence were used to analyze the expression of lamin A/C and active caspase-6 in normal human ovarian surface epithelial (HOSE) cells, immortalized human ovarian surface epithelial cells and a set of seven ovarian cancer cell lines (including OVCAR3, OVCAR5, and A2780). The activity of caspase-6 was measured by densitometry, fluorescence and flow cytometry. Immunohistochemistry was used to evaluate the expression of caspase-6 in set of ovarian cancer tissues previously reported to have lost lamin A/C.ResultsThe results showed that HOSE cells expressed lamin A/C and no or low level of active caspase-6 while cancer cells highly expressed caspase-6 and no or low level of lamin A/C. The inhibition of caspase-6 activity in OVCAR3 cells increased lamin A but has no effect on lamin C; active caspase-6 was localized in the cytoplasm associated with the loss of lamin A.ConclusionOverexpression and cytoplasmic localization of caspase-6 in ovarian cancer cells may be involved in lamin A degradation and deficiency observed in some ovarian cancer cells.
Highlights
In most women with ovarian cancer, the diagnosis occurs after dissemination of tumor cells beyond ovaries
We showed by immunoblotting, immunofluorescence, flow cytometry and immunohistochemistry that active caspase-6 was highly present in most ovarian cancer cell and tissues unlike normal ovarian epithelial cells or tissues
The nuclear localization of caspase-6 was commonly associated with the cleavage of nuclear lamin A and cell death while cytoplasmic localization of active caspase-6 was not associated with instantaneous apoptosis [14, 15]
Summary
In most women with ovarian cancer, the diagnosis occurs after dissemination of tumor cells beyond ovaries. Several molecular perturbations occur ahead of tumor initiation including loss of lamin A/C. Our hypothesis was that the loss of nuclear structural proteins A type lamins (lamin A/C) transcribed from LMNA gene and substrate for active caspase-6 maybe one of the molecular perturbations. Our objective is to investigate the association between the loss of lamin A/C and the overexpression of caspase-6 in ovarian cancer cells. To the best of our acknowledges, the link between cytoplasmic localization of activated caspase-6 and the loss of the nuclear structural protein lamin A in ovarian cancer was not yet reported. Our investigation demonstrated an inverse association between active caspase-6 and lamin A in ovarian cancer cell lines and tissues. We hypothesized that active caspase-6 may be involved in lamin A/C degradation leading to the loss of nuclear structural proteins A type lamins (lamin A/C) prior to nuclear anomalies leading to carcinogenesis
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call