The cucurbitacins D, E, and I from Ecballium elaterium (L.) upregulate the LC3 gene and induce cell-cycle arrest in human gastric cancer cell line AGS

Objective(s): Cucurbitacins exhibit a range of anti-cancer functions. We investigated the effects of cucurbitacins D, E, and I purified from Ecballium elaterium (L.) A. Rich fruits on some apoptotic and autophagy genes in human gastric cancer cell line AGS. Materials and Methods: Using quantitative reverse transcription PCR (qRT-PCR), the expression of LC3, VEGF, BAX, caspase-3, and c-MYC genes were quantified in AGS cells 24 hr after treatment with cucurbitacins D, E, and I at concentrations 0.3, 0.1 and 0.5 μg/ml, respectively. Cell cycle and death were analyzed by flowcytometry. Results: Purified cucurbitacins induced sub-G1 cell-cycle arrest and cell death in AGS cells and upregulated LC3 mRNA effectively, but showed a very low effect on BAX, caspase-3, and c-MYC mRNA levels. Also after treatment with cucurbitacin I at concentration 0.5 μg/ml, VEGF mRNA levels were increased about 4.4 times. Pairwise comparison of the effect of cucurbitacins D, E, and I on LC3 mRNA expression showed that the cucurbitacin I effect is 1.3 and 1.1 times that of cucurbitacins E and D, respectively; cucurbitacin D effect is 1.2 times that of cucurbitacin E (P-value <0.05). In silico analysis showed that among autophagy genes, LC3 has an important gastric cancer rank relation. Conclusion: Cucurbitacins D, E, and I purified from E. elaterium fruits upregulate LC3 and induce sub-G1 cell-cycle arrest and cell death in human gastric cancer cell line AGS. Cucurbitacin I effect on LC3 mRNA expression is significantly more than that of cucurbitacins E and D.