Background: Prostate cancer is the second leading malignancy worldwide and the second prominent cause of cancer-related deaths among men. Therefore, there is a serious necessity for finding advanced alternative therapeutic measures against this lethal malignancy. In this article, we report the cytotoxicity and the mechanism of cell death of the methanolic extract prepared from Echinophora platyloba DC plant against human prostate adenocarcinoma PC 3 cell line and Human Umbilical Vein Endothelial Cells HUVEC cell line.
Methods: Cytotoxicity and viability of the methanolic extract were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and dye exclusion assay. Cell death enzyme-linked immunosorbent assay (ELISA) was employed to quantify the nucleosome production resulting from nuclear DNA fragmentation during apoptosis and determine whether the mechanism involves induction of apoptosis or necrosis. The cell death was identified as apoptosis using terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay and DNA fragmentation gel electrophoresis.
Results: E. platyloba could decrease cell viability in malignant cells in a dose- and time-dependent manner. The IC50 values against PC 3 were determined as 236.136 ± 12.4, 143.400 ± 7.2, and 69.383 ± 1.29 μg/ml after 24, 36, and 48 h, respectively, but there was no significant activity in HUVEC normal cell (IC50 > 800 μg/ml). Morphological characterizations and DNA laddering assay showed that the methanolic extract treated cells displayed marked apoptotic characteristics such as nuclear fragmentation, appearance of apoptotic bodies, and DNA laddering fragment. Increase in an early apoptotic population was observed in a dose-dependent manner. PC 3 cell death elicited by the extract was found to be apoptotic in nature based a clear indication of TUNEL assay and gel electrophoresis DNA fragmentation, which is a hallmark of apoptosis.
Conclusions: In summary, the E. platyloba extract attenuated the human prostate adenocarcinoma cell proliferation in vitro possibly by inducing apoptosis. E. platyloba is likely to be valuable for the treatment of human prostate adenocarcinoma.