The combination of tephrosin with 2-deoxy-D-glucose enhances the cytotoxicity via accelerating ATP depletion and blunting autophagy in human cancer cells

Abstract

Abbreviations: AMPK, AMP-activated protein kinase; 2-DG, 2-Deoxy-D-glucose; EF-2, elongation factor-2; eEF-2K, elongation factor-2 kinase; 4EBP1, eukaryotic translation initiation factor 4E binding protein 1; FITC, fluorescein isothiocynate; GFP, green fluorescent protein; LC3, microtubule-associated protein light chain 3B; PARP, poly ADP-ribose polymerase; mTOR, mammalian target of rapamycin; PI, propidium iodide; siRNA, small interfering RNA; TSN, tephrosin 2-Deoxy-D-glucose (2-DG), a synthetic glucose analog that acts as a glycolytic inhibitor, is currently under clinical evaluation for targeting tumor cells. Tephrosin (TSN), a plant rotenoid, is known as an anticancer agent. In this study, we describe that the addition of TSN to 2-DG enhanced the cytotoxic activity of 2-DG against various types of cancer cells by accelerating ATP depletion and blunting autophagy. TSN increased the sensitivity of cancer cells to the cytotoxic effect of 2-DG. The combination of TSN and 2-DG induced acceleration of intracellular ATP depletion and the drastic activation of AMP-activated protein kinase (AMPK), which resulted in the inactivation of the mammalian target of rapamycin (mTOR) pathway. Of particular interest, TSN suppressed 2-DG-induced autophagy, a cell survival process in response to nutrient deprivation. We also showed that TSN inhibited 2-DG-induced activation of elongation factor-2 kinase (eEF-2K), which has been known to regulate 2-DG-induced autophagy. Inhibition of eEF-2K by RNA interference blunted 2-DG-induced autophagy and increased the sensitivity of cancer cells to the cytotoxic effect of 2-DG. The addition of TSN to 2-DG, however, did not enhance the cytotoxic activity of 2-DG by knockdown of eEF-2K, suggesting that inhibition of eEF-2K by tephrsoin could be a critical role in the potentiating effect of TSN on the cytotoxicity of 2-DG. Furthermore, we showed that the blunted autophagy and enhanced cytotoxicity of 2-DG was accompanied by the augmentation of apoptosis. These results show that TSN may be valuable for augmenting the therapeutic efficacy of 2-DG.

2-Deoxyglucose Reverses the Promoting Effect of Insulin on Colorectal Cancer Cells In Vitro

“…Based on many recent researches, the toxicity following 2DG treatment could be explained by more than one mechanism depending on the metabolic profile of a specific cancer cell type. Mimicking glucose deprivation, 2DG is capable of inducing autophagy [ 41 – 43 ]. The conversion from LC3-I to LC3-II is a representative process for autophagy flux [ 19 ].…”

Bioelectricity, Its Fundamentals, Characterization Methodology, and Applications in Nano‐Bioprobing and Cancer Diagnosis

“…The balance between capture efficiency and cellular viability of rare CTC is critical. In previous studies, cytotoxicity was investigated on several mechanisms of cell‐nano interactions, including endocytosis of nanomaterials, damage of cell membrane and pseudopod, and nutrientdepletion . Morphology of the bioprobe was also found an important factor on cell capture and biocompatibility.…”

Chromosomal instability causes sensitivity to protein folding stress and ATP depletion

“…S4 " type="url"/> ). We expect that knockdowns of ADSS and PRPS2 decrease the rate of Adenosine Mono-Phosphate (AMP) synthesis and AMP is used to maintain phosphorylated AMPK to activate autophagy ( Choi and Lee, 2011 ). However, increased Lysotracker staining in these candidates suggest that in absence of autophagy, lysosomes work hard to compensate.…”