Edelfosine-induced metabolic changes in cancer cells that precede the overproduction of reactive oxygen species and apoptosis

Background  

Metabolic flux profiling based on the analysis of distribution of stable isotope tracer in metabolites is an important method widely used in cancer research to understand the regulation of cell metabolism and elaborate new therapeutic strategies. Recently, we developed software Isodyn, which extends the methodology of kinetic modeling to the analysis of isotopic isomer distribution for the evaluation of cellular metabolic flux profile under relevant conditions. This tool can be applied to reveal the metabolic effect of proapoptotic drug edelfosine in leukemia Jurkat cell line, uncovering the mechanisms of induction of apoptosis in cancer cells.     

Buffering capacity of whole corn mash alters concentrations of organic acids required to inhibit growth of Saccharomyces cerevisiae and ethanol production

Growth of Saccharomyces cerevisiae and fermentative ethanol production in the presence of acetic and lactic acids was measured in whole corn mash. In this industrial medium, as compared to glucose minimal medium, the yeast had increased tolerance to organic acid stress. It was concluded that the increased buffering capacity of whole corn mash, resulting in decreased concentration of undissociated acid, was responsible for this phenomenon.     

EPR studies of higher plant mitochondria I. Ubisemiquinone and its relation to alternative respiratory oxidations

An EPR investigation of the region of the higher plant respiratory chain involving ubiquinone and Center S-3 of succinate dehydrogenase is reported. At temperatures close to those of liquid helium, first derivative spectra corresponding to Center S-3 (g_max = 2.017) and a signal split around g = 2.00 (major features of peaks and troughs at g values of 2.045, 2.03, 1.985, 1.97 and 1.96) were observed in mung bean (Phaseolus aureus), Arum maculatum spadix, Sauromatum guttatum spadix and tulip bulb (Tulipa gesnerana) mitochondria. The split signal was small or absent in potato tuber and Symplocarpus foetidus spadix mitochondria.

The redox behavior of these signals in mung bean mitochondria in a variety of respiratory steady-state conditions suggested that the components giving rise to them were an integral part of the respiratory chain and were located on the substrate side of coupling Site II. The split signal could be removed by addition of hydroxamic acids in all tissues tested, although the K_s of this effect was an order of magnitude higher than the K_i of inhibition of the alternative respiratory pathway in mung bean and Sauromatum guttatum spadix mitochondria.

The results are discussed in relation to the current ideas on the ordering of components in the region around the classical Site II of the respiratory chain and in relation to the location of the alternative respiratory oxidase pathway of higher plants.     

Ligand-dependent differences in estrogen receptor beta-interacting proteins identified in lung adenocarcinoma cells corresponds to estrogenic responses

Background

A recent epidemiological study demonstrated a reduced risk of lung cancer mortality in breast cancer patients using antiestrogens. These and other data implicate a role for estrogens in lung cancer, particularly nonsmall cell lung cancer (NSCLC). Approximately 61% of human NSCLC tumors express nuclear estrogen receptor β (ERβ); however, the role of ERβ and estrogens in NSCLC is likely to be multifactorial. Here we tested the hypothesis that proteins interacting with ERβ in human lung adenocarcinoma cells that respond proliferatively to estradiol (E₂) are distinct from those in non-E₂-responsive cells.

Methods

FLAG affinity purification of FLAG-ERβ-interacting proteins was used to isolate ERβ-interacting proteins in whole cell extracts from E₂ proliferative H1793 and non-E₂-proliferative A549 lung adenocarcinoma cell lines. Following trypsin digestion, proteins were identified using liquid chromatography electrospray ionization tandem mass spectrometry (LC-MS/MS). Proteomic data were analyzed using Ingenuity Pathway Analysis. Select results were confirmed by coimmunoprecipitation.

Results

LC-MS/MS identified 27 non-redundant ERβ-interacting proteins. ERβ-interacting proteins included hsp70, hsp60, vimentin, histones and calmodulin. Ingenuity Pathway Analysis of the ERβ-interacting proteins revealed differences in molecular and functional networks between H1793 and A549 lung adenocarcinoma cells. Coimmunoprecipitation experiments in these and other lung adenocarcinoma cells confirmed that ERβ and EGFR interact in a gender-dependent manner and in response to E₂ or EGF. BRCA1 interacted with ERβ in A549 cell lines and in human lung adenocarcinoma tumors, but not normal lung tissue.

Conclusion

Our results identify specific differences in ERβ-interacting proteins in lung adenocarcinoma cells corresponding to ligand-dependent differences in estrogenic responses.