Crude extract of Nigella sativa inhibits proliferation and induces apoptosis in human cervical carcinoma HeLa cells

Cervical cancer is a major cause of morbidity in women worldwide and chemotherapy for this cancer seems unsatisfactory, which demands exploring new therapeutic options. The seeds and oil from Nigella sativa have been reputed to have many curative properties in traditional medicine. Utilizing different techniques (4',6-diamidino-2-phenylindole (DAPI) staining, deoxyribonucleic acid (DNA) laddering, Comet assay and reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analyses), this study was carried out to evaluate the impact of N. sativa on the growth of human cervical carcinoma HeLa cells. The ethanol extract from N. sativa (EENS) significantly inhibited proliferation and colony formation and induced apoptosis in HeLa cells. The apoptotic induction was associated with the release of mitochondrial cytochrome c, increase of Bax/Bcl-2 ratio, activation of caspases-3, -9 and -8 and cleavage of poly (ADP-ribose) polymerase (PARP). EENS decreased expression of oncoproteins such as c-Myc, human telomerase reverse transcriptase (hTERT), cyclin D1 and cyclin-dependent kinase-4 (CDK-4), but increased expression of tumor-suppressor proteins including p53 and p21. These findings demonstrate that EENS inhibits proliferation and induces apoptosis in HeLa cells and suggest this extract may be a promising agent for the prevention/treatment of human cervical cancer.