Biology subjects

Smith, L. E.

Publications and source records attributed to Smith, L. E..

4 recordsLinked to original sources

bioRxiv2025

Curcumin Analogues Trigger HMOX1-Mediated Ferroptosis to Halt Endometrial Cancer Growth

BackgroundAdvanced endometrial cancer remains challenging to treat due to limited therapeutic options and drug resistance. Ferroptosis, an iron-dependent form of cell death, offers a potential strategy for overcoming resistance. Curcumin analogues with improved bioavailability, such as HO-3867 and AKT-100, exhibit potent anti-cancer activity, but their mechanisms remain under-explored. MethodsKLE, Hec50co and Ishikawa endometrial cancer cells were treated with HO-3867 or AKT-100. RNA sequencing, qPCR, and immunoblotting assessed ferroptosis-related gene expression, focusing on HMOX1. Intracellular iron and ROS were measured via FerroOrange and DCFH-DA staining. Cytotoxicity and colony formation were evaluated using CyQUANT assays, with pharmacological inhibitors (ZnPP, Liproxstatin-1, Z-VAD-FMK) and HMOX1 siRNA to dissect the roles of ferroptosis and apoptosis. ResultsBoth analogues upregulated multiple ferroptosis genes, prominently HMOX1. AKT-100 increased intracellular iron and ROS levels. Inhibition of HMOX1, ferroptosis, or apoptosis partially rescued cell viability, while HMOX1 knockdown enhanced clonogenic growth, confirming its key role in AKT-100-mediated cytotoxicity. ConclusionsHO-3867 and AKT-100 induce HMOX1-mediated ferroptosis and apoptosis, effectively suppressing endometrial cancer cell growth. These findings support the therapeutic potential of curcumin analogues and provide a foundation for in vivo studies targeting HMOX1 in endometrial cancer. O_FIG O_LINKSMALLFIG WIDTH=187 HEIGHT=200 SRC="FIGDIR/small/689080v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@610bcorg.highwire.dtl.DTLVardef@34d8eaorg.highwire.dtl.DTLVardef@18d2a5aorg.highwire.dtl.DTLVardef@d7b4f3_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2025

The novel curcumin analogue AKT-100 targets mutant p53 in gynecologic cancer cells

Loss of normal p53 tumor-suppressive activity is common in advanced cancers, where TP53 mutations produce either p53-null states or highly expressed missense proteins with gain of oncogenic function. Mutant p53 proteins not only lose wild type p53 pro-apoptotic and DNA repair functions but also acquire new activities, including constitutive STAT3 activation. We hypothesize that directly targeting missense mutant p53 instead of downstream pathways is advantageous. Curcumin analogues have been reported to bind mutant p53, motivating the development of AKT-100, a novel analogue designed to restore wild type p53 functionality. AKT-100 binds mutant p53 and STAT3, as shown by fluorescence quenching, and inhibits STAT3 Tyr705 phosphorylation in KLE and COV362 cells. This agent exhibits potent cytotoxicity in gynecological cancer cells with IC50 values ranging from 4 nm to 2.51 {micro}M, and demonstrates synergy with the PARP inhibitor olaparib and with chemotherapy by suppressing alternative DNA repair mechanisms associated with therapeutic resistance. RNA sequencing and immunoblotting confirms AKT-100 reactivates wild type p53 transcriptional profiles regulating cell cycle arrest (CDKN1A/p21, GADD45A), apoptosis (PMAIP1/Noxa, DR5), and inhibits DNA replication and repair. These findings support AKT-100 as a promising therapeutic agent with the dual capabilities of directly targeting oncogenic mutant p53 and constitutively active STAT3. HighlightsO_LIAKT-100 is a novel curcumin analogue that functions as a WT p53 reactivator. C_LIO_LIAKT-100 inhibits STAT3 phosphorylation at Tyrosine 705 in endometrial and ovarian cancer cells. C_LIO_LICell proliferation is inhibited in multiple ovarian and serous endometrial cancer cell lines with AKT-100 as a single agent. C_LIO_LIAKT-100 is synergistic with PARP inhibitor olaparib and chemotherapy drugs carboplatin and paclitaxel. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/680794v3_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@1fdb8a8org.highwire.dtl.DTLVardef@6648acorg.highwire.dtl.DTLVardef@12d301aorg.highwire.dtl.DTLVardef@1b1370f_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2022

Endothelial-derived sphingolipids are required for vascular development and systemic lipid homeostasis

Serine palmitoyl transferase (SPT), the rate-limiting enzyme in the de novo synthesis of sphingolipids (SL), is needed for embryonic development, physiological homeostasis, and response to stress. The functions of de novo SL synthesis in vascular endothelial cells (EC), which line the entire circulatory system, are not well understood. Here we show that the EC de novo synthesis not only impacts vascular development but also maintains normal SL metabolic homeostasis in the circulatory system and peripheral organs. Mice with an endothelial-specific gene knockout of SPTLC1 (Sptlc1 ECKO), an essential subunit of the SPT complex, exhibited EC-intrinsic effects including reduced EC proliferation and tip/stalk cell differentiation, resulting in delayed retinal vascular development. In addition, Sptlc1 ECKO mice had reduced pathological retinal neovascularization in the oxygen-induced retinopathy model, suggesting that EC SL produced from the de novo pathway are needed for efficient VEGF signaling within the vascular system. Post-natal deletion of the EC Sptlc1also showed cell-extrinsic effects, including rapid reduction of several SL metabolites in plasma, red blood cells and peripheral organs (lung and liver) but not in the retina, part of the central nervous system (CNS). In the liver, EC de novo SL synthesis was required for acetaminophen-induced ceramide elevation and hepatotoxicity. These results suggest that EC-derived SL metabolites are in constant flux between the vasculature, circulatory elements, and parenchymal cells of non-CNS organs. Taken together, our data point to the central role of the endothelial SL biosynthesis in maintaining vascular development and neovascular proliferation, non-CNS tissue metabolic homeostasis and hepatocyte response to stress.

developmental biology↗

bioRxiv2019

HIV-1 genome trafficking initiates APOBEC3G packaging in the cytosol

HIV-1 RNA genomes interact with diverse RNA binding proteins (RBPs) in the cytoplasm including antiviral factor APOBEC3G (A3G) that, in the absence of viral Vif proteins, is packaged into virions. Where and when HIV-1-A3G interactions are initiated for packaging inside the cell is unknown, and the relative contributions of genome vs. Gag capsid proteins to this process remains controversial. Here we visualized A3G responses to HIV-1 infection over an entire replication cycle using long-term (up to 72 h) live single cell imaging. We show that Vif-deficient HIV-1 dramatically shifts A3G and a second RNA surveillance factor, MOV10, from the cytoplasm to virus particle assembly sites with little to no net discernible effects on general markers of cytoplasmic processing bodies (DCP1A), stress granules (TIA-1), or a marker of the nonsense-mediated decay machinery (UPF1). Using a new live cell RNA-protein interaction assay based on RNA tethering (the in-cell RNA-protein interaction protocol, or IC-IP), we provide evidence that A3G- and MOV10- genome interactions are selective, strong, occur in presence or absence of Gag, and are initiated in the cytosol soon if not immediately after genome nuclear export. Finally, although Gag is sufficient to package A3G into virions even in the absence of genomes, single virion imaging indicates that selective A3G-genome interactions promote much more consistent per virion delivery of A3G to assembly sites. Collectively, these studies suggest a paradigm for early, strong, and persistent cytosolic detection of select HIV-1 RNA signatures by A3G, MOV10 and other host RBPs that are enriched in virions. IMPORTANCEHost-pathogen interactions determine the success of viral replication. While extensive work has identified many interactions between HIV-1 and cellular factors, our understanding of where these interactions in cells occur during the course of infection is incomplete. Here, we show that multiple RNA-binding proteins (including the antiviral restriction factor, APOBEC3G, and MOV10 helicase) bind HIV-1 RNA genomes in the cytoplasm and co-traffic with them into progeny virions. Furthermore, we show that these interactions with HIV-1 RNA occur in the absence of Gag and are sufficiently strong to recruit these to otherwise non-native subcellular locales. Together, these data begin to illuminate the intracellular trafficking pathways shared by host RNA binding proteins and the viral RNAs they preferentially bind.

cell biology↗