Project description:Long wavelength Ultraviolet (UVA-1) radiation causes oxidative stress that leads to the formation of noxious substances within the skin. As a defensive mechanism skin cells produce detoxifying enzymes and antioxidants when they detect modified molecules. We have recently shown that UVA-1 irradiation oxidizes the abundant membrane phospholipid 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (PAPC), which then induced the synthesis of the stress response protein heme oxygenase 1 (HO-1) in dermal fibroblasts. Here we examined the effects of UVA-1 and (UV-) oxidized phospholipids on the global gene expression in human dermal fibroblasts. We identified a cluster of genes that were co-induced by UVA-1-oxidized PAPC and UVA-1 radiation. The cluster included HO-1, glutamate-cysteine ligase modifier subunit (GCLM), aldo-keto reductases-1-C1 and -C2 (AKR1C1, AKR1C2), and interleukin 8 (IL8). These genes are members of the cellular stress response system termed âantioxidant responseâ or âPhase II detoxificationâ. Accordingly, the regulatory regions of all these genes contain binding sites for NF-E2-related factor 2 (Nrf2), a major regulator of the antioxidant response. Both UVA-1 irradiation and treatment with oxidized lipids led to increased nuclear accumulation of Nrf2. Silencing expression of Nrf2 using siRNA or using cells and tissue from Nrf2-deficient mice, we show that the induction of the co-regulated genes was suppressed. Expression of other canonical UVA-1-induced genes, including cyclooxygenase 2 (Cox2) and interleukin 6 (IL6) was unaltered in the absence of Nrf2. Together, our data show that UVA-1-mediated lipid oxidation induces induction of antioxidant response genes, which is dependent on the redox-regulated transcription factor Nrf2. To activate Nrf2 is a major strategy for novel antioxidant drugs, the skin photo-adaptation (SPA) inducers. Our finding that specific uv-oxidized lipids act similar sheds a new (ultraviolet) light on the usually detrimental âimageâ of UV generated lipid mediators. Experiment Overall Design: we profiled global mRNA expression levels in human dermal fibroblasts that had been treated with either UVA-1 or oxidized lipids. To investigate the effect of oxidized phospholipids on gene regulation, we used two preparations, which differed in their degree of oxidation; the minimally oxidized UV-PAPC resulting from UVA-1 irradiation of PAPC, and air-oxidized PAPC (OxPAPC), which represents the full spectrum of oxidation products (Gruber 07) (Reis et al., 2005). We irradiated dermal fibroblasts with UVA-1 (40J/cmÂ²) or treated them with UV-PAPC, OxPAPC or native PAPC (100Âµg/ml each). We analyzed global gene expression four hours after stimulation with gene arrays (Affymetrix U133A Plus 2.0 Gene Chips).

Project description:DNA methylation causes silencing of tumor suppressor and differentiation-associated genes being linked to chemoresistance and stemness. Previous studies demonstrated that hypomethylating agents (HMA) re-sensitize ovarian cancer (OC) cells to chemotherapy, however, translation to the clinic has been slow. NTX 301 (PinotBio) is a novel, highly potent and orally bioavailable HMA, in early clinical development. We assessed the anti-tumor effects of NTX301 in OC models and studied the underlying molecular mechanisms by using cell proliferation, stemness and ferroptosis assays, RNA sequencing and validation. OC cells (SKOV3, IC50=5.089nM; OVCAR5 IC50=3.664nM) were highly sensitive to NTX301 (p<0.05) compared to immortalized fallopian tube epithelial cells (FT-190) (IC50=103.3nM). Treatment with NTX301 induced significant downregulation of the DNA methyltransferases (DNMTs) 1-3 expression in SKOV3 and OVCAR5 cells compared with decitabine (p<0.05). Treatment with low dose NTX301 (100nM) induced significant transcriptomic reprogramming with 15,000 differentially expressed genes (DEGs) compared to DMSO (p<0.05). Among the NTX301 down-regulated DEGs, Gene Ontology (GO) enrichment analysis identified pathways related to regulation of alcohol, cholesterol, and fatty acid biosynthetic process and molecular functions related to aldehyde dehydrogenase (ALDH) and oxidoreductase activity, known features of cancer stem cells (CSCs). Indeed, treatment with low dose NTX301 (100nM) reduced the ALDH(+) cell population and expression of stemness associated transcription factors (Oct4 and Sox2). Additionally, stearoyl-Coenzyme A desaturase 1 (SCD), a key enzyme that regulates unsaturated fatty acid homeostasis in the lipogenesis process was found among the top DEGs downregulated in response to NTX301 (fold change=9.36, FDR<0.05). As blockade of SCD had been shown to induce ferroptosis, oxidized lipids levels were measured by C11-BODIPY staining. NTX301 treatment increased the levels of oxidized lipids compared to DMSO and this was blunted by deferoxamine, indicating that NTX301 promoted cell death via ferroptosis. NTX301 induced ferroptosis was successfully rescued by addition of oleic acid (200mM) into the culture medium, supporting that it was mediated through SCD depletion. In vivo, monotherapy with NTX301 (1mg/kg), significantly inhibited subcutaneous OC and PDX xenograft tumor growth (p<0.05). Decreased SCD levels and increased oxidized lipids were recorded in NTX301-treated xenografts. In conclusions, NTX301 is a potent HMA active in OC models. Our findings point to a new mechanism by which epigenetic blockade disrupts lipid homeostasis and promotes cancer cell death.

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GNPS - Targeting FSP1 triggers ferroptosis in lung cancer

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