Metabolomics analysis of endogenous metabolites in breast cancer cells exposed to polybrominated diphenyl ethers

Major components of polybrominated diphenyl ethers (PBDEs) have been included in the Stockholm Convention on Persistent Organic Pollutants since May 2009. The chemicals are found to be accumulated in human milk, adipose and blood. Previous work also suggested that PBDEs may promote breast cancer proliferation. More importantly, it has been widely recognized that the origin of cancer is by means of metabolic selection. Therefore, we hypothesized that PBDEs may enhance breast cancer risk through metabolic reprogramming. To test this hypothesis, we will carry out mass spectrometry- based metabolomics in combination with isotope labeling technique. The endogenous metabolites are the amplified readout of cell pathogenesis, which would indicate altered metabolism in cells exposed to PBDEs. PBDEs exposure will be investigated not only in non-tumorigenic human breast cell lines (MCF-10A and Hs578Bst) for understanding the toxicological effects, but also with estrogen receptor-positive breast cancer cell lines (MCF-7 and T47D) as well as estrogen receptor-negative breast cancer cell lines (MDA- MB-231 and Hs578T) for evaluating the promoting proliferative effects. Liquid chromatography and gas chromatography coupled with mass spectrometry will be employed for non-targeted and targeted metabolomics analysis. The feature selection from total ion chromatograms in mass spectra will be applied for searching potential biomarkers that will be proposed in the metabolic pathways. The metabolomics data analysis package MetaXCMS will then be used to detect the shared metabolites from multiple sample groups representing different models of the same phenotype. Moreover, regarding Warburg effect in cancer metabolism, targeted metabolomics in combination with isotope-labeling technique will be applied for quantitative analysis of the intermediate metabolites in glycolysis and citric acid cycle to reveal metabolic reprogramming induced by PBDEs exposure. The isotope-labeled glucose or glutamine will be used in cell culture for metabolite extraction, and metabolic switches will be unlocked. By taking the toxicological effects of PBDEs in normal breast cells into account, the disturbed metabolic pathways might be linked to breast cancer development for uncovering estrogen-dependent or –independent metabolic mechanisms. In summary, we will apply mass spectrometry-based metabolomics for studying metabolic phenotypes associated with the possible toxicological effects of PBDEs. The hypothesis on PBDEs exposure associated with breast cancer development will be tested.