Determination of organic fluorinated compounds content in complex samples through combustion ion chromatography methods: a way to define a "Total Per- and Polyfluoroalkyl Substances (PFAS)" parameter?

Emerging contaminants are a growing concern for scientists and public authorities. The group of per-polyfluoroalkyl substances (PFAS), known as 'forever chemicals', in complex environmental liquid and solid matrices was analysed in this study. The development of global analytical methods based on combustion ion chromatography (CIC) is expected to provide accurate picture of the overall PFAS contamination level via the determination of extractable organic fluorine (EOF) and adsorbable organic fluorine (AOF). The obtained results may be put into perspective with other methods such as targeted analyses (LC-MS/MS). The impact of pH, the presence of dissolved organic carbon and suspended particles on AOF measurements were explored. The effectiveness of the washing step to remove adsorbed inorganic fluorine (IF) has been proven for samples containing up to 8 mgF.L-1. CIC-based methods showed good repeatability and reproducibility for the complex matrices studied. Environmental applications of these methods have been tested. AOF and EOF analyses could explain between 1 % and 23 % and 0.1 % to 2 % of total organic fluorine (TOF), respectively. The sum of PFAS compounds expressed as fluorine could explain from 0.2 % to 11 % and from 0.003 % to 5 % for AOF and EOF, respectively. These results also suggest that some fluorinated compounds are not adsorbed or extractable and/or lost by volatilisation during the application of AOF and EOF analytical procedure. These findings highlight that AOF and EOF are not entirely efficient as proxy to assess "total PFAS" for assessing environmental contamination by PFAS. However, these methods could still be applied to gain a better understanding of the sources and fate of PFAS in the environment.

P18.06.B ETS-Transcription Factor inhibitors are effective inTERT promoter mutated meningioma cells in vitro

Background

TERT promoter mutations in meningiomas were recently found to be strongly prognostic and associated with malignant progression and risk of recurrence. As result, the mutation in the TERT promoter generates a binding site for E twenty-six (ETS) transcription factors. Consequently, ETS-transcription factor inhibition might represent a novel strategy to impede meningioma growth. In a prior study we could demonstrate effectiveness of the ETS-transcription factor inhibitor YK-4-279 in TERT promoter mutant meningiomas. Recently, TK216 the clinical derivative of YK-4-279 was developed. Therefore, we aimed to clarify whether TK216 might have an increased effect as compared to YK-4-279 in TERT promoter mutated meningioma cells in vitro.

Methods

A meningioma-derived cell line (BTL695) generated from a TERT promoter mutated (C228T) anaplastic meningioma served as cell model for the experiments. BTL695 was characterized by high telomerase activity and TERT mRNA expression as analysed by the TRAP assay and RT-PCR, respectively. Genomic aberrations were verified using Ion Torrent Oncomine Comprehensive Assay v3-based next-generation sequencing (NGS). The sensitivity of BTL695 to YK-4-279 and TK216 was determined using an MTT-based viability assay (EZ4U). To elucidate the effectiveness of TK216 on cell cycle and apoptosis, cells were stained with PI and annexin V, respectively, and measured by flow cytometry. The effect of TK216 on the protein expression of the cleaved poly(ADP-ribose) polymerase-1 (PARP-1), indicative for apoptosis, was investigated by western blot. Additionally, a TK216-resistant cell model (BTL695res) was generated and analysed by NGS.

Results

BTL695 was significantly more sensitive to TK216 as compared to YK-4-279 (p<0.0001) characterized by the distinctly lower IC50 value of TK216 exposed cells (0.7 µM TK216; 1.6 µM YK-4-279). Flow cytometry analysis revealed a TK216 induced G2M cell cycle arrest and increased apoptosis rate, which was additionally verified by the expression of cleaved PARP-1 expression using western blot. Genomic aberrations were found in 18 genes including NF2, CDKN2A/B, ARID1A and PTEN. Interestingly, although the majority of genomic alterations was persistent in the TK216 resistant cell model, a p53 mutation was newly acquired as compared to the parental cell line.

Conclusion

In summary, our results indicate that ETS transcription factor inhibition by TK216 exerts antitumour activity in our TERT promoter mutant meningioma cell model. Additionally, the sensitivity against TK216 is superior to YK-4-279 and therefore TK216 may represent a promising new therapeutic option for patients with aggressive, TERT promoter mutated meningioma.

P10.08.A Lipogenesis inhibition by fatostatin shows effectiveness in glioblastoma models highly expressing fatty acid synthase (FASN)

Background

Glioblastoma (GBM) is the most common and most aggressive primary brain tumour in adults. Despite intensive treatment, the medium overall survival of GBM patients remains below 20 months after diagnosis. Therefore, new tumour specific targets allowing successful therapeutic treatment are needed to distinctly enhance GBM patient overall survival. Reprogramming of lipid metabolism leading to highly upregulated anabolic pathways, like phosphatidylinositol-3-kinase (PI3K)/AKT pathway and subsequently lipogenesis, is a hallmark of cancer cells including glioblastomas to meet increased energy demands for proliferation and cell growth. Accordingly, lipogenesis inhibition might be a promising strategy to impede GBM cell growth. Therefore, it was aim of our study to analyse the effect of the lipogenesis inhibitor fatostatin on downstream targets e.g. fatty acid synthase (FASN) and its impact on cell growth in GBM cells in vitro.

Material and Methods

In a cohort of 52 GBM-derived cell lines, FASN mRNA was investigated by qRT-PCR. The impact of fatostatin on cell viability (IC50) was analysed in selected cell lines using cell viability assays (Cell Titer Glo®). To elucidate whether fatostatin exposure affects cell migration, wound healing assays were performed. The effect of fatostatin on cell cycle and apoptosis was analysed by flow cytometry. Additionally, expression of FASN and level of phosphorylated AKT, the active form of AKT serine/threonine kinase, were examined before and after fatostatin treatment with qRT-PCR (mRNA) and Western blot (protein), respectively.

Results

FASN mRNA was found to be expressed at varying levels in our GBM-derived cell line cohort (n=52). Compared to normal astrocytes, FASN mRNA expression was significantly upregulated in GBM cells (p=0.0127). Furthermore, high FASN mRNA expression was significantly associated with higher sensitivity against fatostatin (p=0.0352). Regarding corresponding recurrences, the response to the inhibitor was shown to be persistent. Accordingly, the effectiveness of fatostatin treatment resulted in substantial downregulation of AKT phosphorylation and consequently in the induction of apoptosis and G2/M arrest of the cell cycle. In addition, a significant inhibition of the migration potential by fatostatin treatment was observed.

Conclusion

In summary, FASN expression represents a promising biomarker and therapy target within the lipid metabolism indicated by a significant sensitivity to fatostatin in FASN overexpressing GBM cell lines. Consequently, lipogenesis inhibition by fatostatin might be a promising novel therapeutic option in glioblastoma.