Objective: Loss of expression of apoptotic regulatory proteins in many neoplasias might result in defective or delayed apoptosis, thus facilitating tumor growth or survival. We analyzed here, the basal expression of precursors of apoptotic Caspases in normal cervical epithelium, HPV+ cervical tumor samples and HPV+ tumor-derived cell lines.
Methods: Expression of initiator and effector Caspases was analyzed by immunochemistry in normal cervical epithelium and three types of cervical tumors (squamous cell carcinoma, adenocarcinoma and adenosquamous cell carcinoma) whereas expression of Caspases in HeLa, SiHa and CaSki cells was by immunofluorescence, Western blot and RT-PCR. Besides, the effect of the HPV-16 E6/E7 oncogenes on Caspases expression in cervical cells was evaluated by transfecting C33-A (HPV-) cells.
Results: Expression of Caspases 3 and 9 was undetectable in adenocarcinoma and adenosquamous cell carcinoma, respectively. Whereas in squamous cell carcinoma, the expression of Caspases was similar those observed in normal samples. Expression of Caspases 3 and 6 was low in HeLa and CaSki cells, while Caspase 8 was low in SiHa and it was not detected in C33-A cells. All Caspases were detected in the cytoplasm and nucleus of the cells. We did not observe an effect of the E6/E7 oncogenes on the expression of Caspases in C33-A cell.
Conclusion: Our results showed a differential expression of several Caspases in carcinoma samples and cell lines, suggesting multiple alterations of the Caspase pathways in cervical cancer.