Background/Aim: We aimed to investigate the synergistic effects of apigenin and curcumin on the cross-talk between apoptosis and autophagic cell death, as well as on paraptosis in HeLa cells. Materials and Methods: Cell viability was measured using the MTT assay. Synergistic effects were measured using the Bliss independence model. qRT-PCR was used to study the expression of genes related to apoptosis, autophagic cell death, and cross-talk. GRP78/BiP immunostaining was used to identify endoplasmic reticulum (ER) stress. Results: Treatment with a combination of apigenin and curcumin increased the expression levels of genes related to cell death in HeLa cells 1.29- to 27.6-fold. The combination of curcumin and apigenin showed a synergistic anti-tumor effect via cross-talk between processes leading to apoptosis and autophagic cell death, as well as ER stress-associated paraptosis. GRP78 expression was down-regulated, and massive cytoplasmic vacuolization was observed in HeLa cells. Conclusion: The combination of curcumin and apigenin is an effective potential therapeutic for cervical cancers.

We investigated the cytotoxic and apoptotic effects of a methanol extract of Centaurea nerimaniae, a plant endemic in Turkey, on HeLa and MDA-MB-231 cells. Eight concentrations of C. nerimaniae extract were applied to cells, and cytotoxic effects were measured using the xCELLigence system. The TUNEL assay was used to assess apoptotic cell death and immunohistochemistry was used to determine active caspase-3 using the effective cytotoxic doses of the extract. Doses of 1.42 mg/ml C. nerimaniae inhibited the growth of HeLa cells and 3.67 mg/ml C. nerimaniae inhibited the growth of MDA-MB-231 cells in a dose- and time-dependent manner. The apoptotic indexes for HeLa and MDA-MB-231 cells were increased significantly compared to control groups. Immunohistochemistry showed that the number of caspase-3 immunostained cells increased in the extract treatment groups for both HeLa and MDA-MB-231 cells. In the MDA-MB-231 cell line, caspase-3 immunostaining was observed in nuclei and/or cytoplasm in the extract treated group. Caspase-3 activation was greater in HeLa cells than in MDA-MB-231 cells. We found that the extract of C. nerimaniae had a strong antiproliferative effect and induced apoptosis via caspase-3; MDA-MB-231 cancer cells were more resistant than HeLa cells.