Head and neck squamous cell carcinoma (HNSCC) affects squamous cells in the head and neck region and is currently ranked as the sixth most common cancer worldwide. NF-E2-related factor 2 (NRF2) plays a crucial role in cellular protection and defence mechanisms and NRF2 over-expression has been linked to various cancers; however, its role in the response of HNSCC cells remains elusive. We investigated the effects of ML385, a selective NRF2 inhibitor, on HNSCC to understand the underlying molecular mechanisms, and to assess the potential of ML385 as a therapeutic agent. We treated HNSCC cell lines with ML385 and observed a significant reduction in the expression of NRF2 and its downstream target, heme oxygenase-1 (HO-1), using Western blotting. We evaluated its effects on various cellular processes, including cell proliferation, cloning, migration, and wound healing, in HNSCC cell lines. ML385 treatment substantially reduced NRF2 expression, promoting a decrease in the investigated cellular activities. Additionally, we examined changes in the expression of cell-cycle-related proteins and found that ML385 induced cell cycle arrest at the G1/S phase in HNSCC cell lines. Our findings suggest that ML385 can regulate cell cycle progression, inhibit HNSCC growth, and have potential as a therapeutic agent for HNSCC.

Akt is an important kinase in metabolism. Akt also phosphorylates and activates endothelial and neuronal nitric oxide (NO) synthases (eNOS and nNOS, respectively) expressed in M0 (unpolarized) macrophages. We showed that e/nNOS NO production downstream of bitter taste receptors enhances macrophage phagocytosis. In airway epithelial cells, we also showed that the activation of Akt by a small molecule (SC79) enhances NO production and increases levels of nuclear Nrf2, which reduces IL-8 transcription during concomitant stimulation with Toll-like receptor (TLR) 5 agonist flagellin. We hypothesized that SC79's production of NO in macrophages might likewise enhance phagocytosis and reduce the transcription of some pro-inflammatory cytokines. Using live cell imaging of fluorescent biosensors and indicator dyes, we found that SC79 induces Akt activation, NO production, and downstream cGMP production in primary human M0 macrophages. This was accompanied by a reduction in IL-6, IL-8, and IL-12 production during concomitant stimulation with bacterial lipopolysaccharide, an agonist of pattern recognition receptors including TLR4. Pharmacological inhibitors suggested that this effect was dependent on Akt and Nrf2. Together, these data suggest that several macrophage immune pathways are regulated by SC79 via Akt. A small-molecule Akt activator may be useful in some infection settings, warranting future in vivo studies.

The extracellular accumulation of glutamate is a pathologic hallmark of numerous neurodegenerative diseases including ischemic stroke and Alzheimer's disease. At high extracellular concentrations, glutamate causes neuronal damage by promoting oxidative stress, which can lead to cellular death. This has led to significant interest in developing pharmacologic approaches to mitigate the oxidative toxicity caused by high levels of glutamate. Here, we show that the small molecule proteostasis regulator AA147 protects against glutamate-induced cell death in a neuronal-derived cell culture model. While originally developed as an activator of the activating transcription factor 6 (ATF6) arm of the unfolded protein response, this AA147-dependent protection against glutamate toxicity is primarily mediated through activation of the NRF2-regulated oxidative stress response. We demonstrate that AA147 activates NRF2 selectively in neuronal-derived cells through a mechanism involving metabolic activation to a reactive electrophile and covalent modification of KEAP1─a mechanism analogous to that involved in the AA147-dependent activation of ATF6. These results define the potential for AA147 to protect against glutamate-induced oxidative toxicity and highlight the potential for metabolically activated proteostasis regulators like AA147 to activate both protective ATF6 and NRF2 stress-responsive signaling pathways to mitigate oxidative damage associated with diverse neurologic diseases.

Gene expression is controlled by the collective binding of transcription factors to cis-regulatory regions. Deciphering gene-centered regulatory networks is vital to understanding and controlling gene misexpression in human disease; however, systematic approaches to uncovering regulatory networks have been lacking. Here we present high-throughput interrogation of gene-centered activation networks (HIGAN), a pipeline that employs a suite of multifaceted genomic approaches to connect upstream signaling inputs, trans-acting TFs, and cis-regulatory elements. We apply HIGAN to understand the aberrant activation of the cytidine deaminase APOBEC3B, an intrinsic source of cancer hypermutation. We reveal that nuclear factor κB (NF-κB) and AP-1 pathways are the most salient trans-acting inputs, with minor roles for other inflammatory pathways. We identify a cis-regulatory architecture dominated by a major intronic enhancer that requires coordinated NF-κB and AP-1 activity with secondary inputs from distal regulatory regions. Our data demonstrate how integration of cis and trans genomic screening platforms provides a paradigm for building gene-centered regulatory networks.
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