Biology subjects

Azeem, S. M.

Publications and source records attributed to Azeem, S. M..

3 recordsLinked to original sources

bioRxiv2025

EGR1 Mediates Riluzole-Induced Apoptosis in Osteosarcoma via the Yap/p73-Bax Signaling Axis

Osteosarcoma (OS), although rare, is the most common primary bone cancer, primarily affecting individuals aged 10-30 years. Despite therapeutic advances, survival rates have remained stagnant for decades. Recent studies show that Riluzole, a glutamate receptor antagonist, induces apoptosis in OS cells both in vitro and in vivo. Our previous work demonstrated that Riluzole increases reactive oxygen species (ROS), activating c-Abl kinase, which phosphorylates Yes-associated protein (Yap) at tyrosine 357. This modification promotes nuclear translocation of Yap and interaction with p73, enhancing Bax expression and inducing apoptosis. Early Growth Response 1 (EGR1), a zinc finger transcription factor often linked to apoptosis in other cancers, is significantly downregulated in OS. Here, we investigated the role of EGR1 in Riluzole-mediated apoptosis across OS cell lines and patient-derived xenografts (PDX). In this study, we show that Riluzole upregulates EGR1 expression in all OS cell lines. Chromatin immunoprecipitation followed by qPCR confirmed that EGR1 directly binds to the Bax promoter along with Yap/p73, enhancing Bax expression. Immunohistochemistry of in vivo xenograft tumors from Riluzole-treated mice revealed increased EGR1 and cleaved caspase-3 levels, indicating elevated apoptosis, while reduced NUMA expression suggested diminished tumor proliferation. Together, these findings reveal a novel mechanism where Riluzole promotes apoptosis through upregulation of EGR1, which then cooperates with YAP/p73 to activate Bax expression. These insights establish Riluzole as a promising therapeutic intervention for OS treatment through modulation of the EGR1/Yap/p73/Bax signaling axis.

cancer biology↗

bioRxiv2025

Riluzole as a Dual-Targeted Radiosensitizer for Osteosarcoma: Targeting Tumor Cells and Angiogenic Vasculature to Enhance Single High Dose Radiotherapy Efficacy

Osteosarcoma is a highly aggressive bone malignancy primarily affecting children and young adults. It presents significant treatment challenges due to its inherent resistance to conventional fractionated radiotherapy (CFRT). Single high dose radiation therapy (SDRT) has promise for the treatment of radioresistant sarcomas, especially those characterized with extensive vascularity. However, its clinical application is severely constrained by toxicity to adjacent critical tissues. Radiosensitizers can enhance tumor cell susceptibility to radiation-induced DNA damage, improving therapeutic efficacy and potentially reducing collateral toxicity. Monotherapies targeting tumor vasculature alone in solid tumors have shown limited success as radiosensitizers in clinical settings. This highlights the importance of compounds that can simultaneously target both tumor cells and its associated microvasculature to maximize the therapeutic outcome to SDRT. Riluzole, the FDA-approved drug for Amyotrophic Lateral Sclerosis, is currently under investigation as a therapeutic agent for osteosarcoma. Riluzole acts to inhibit glutamate release, reduce glutathione levels in cancer cells, and mitigate tumor angiogenesis, positioning it as a potent radiosensitizing agent for the treatment of osteosarcoma. We hypothesize that Riluzole enhances osteosarcoma radiosensitivity to SDRT by simultaneously targeting intrinsic tumor radioresistance and pro-angiogenic signaling. Our findings demonstrate that Riluzole radiosensitizes osteosarcoma cells in vitro by reducing clonogenic survival and enhancing apoptosis. Mechanistically, Riluzole potentiates irradiation-induced reactive oxygen species (ROS) production, induces G2/M phase cell cycle arrest, inhibits DNA repair, and thereby amplifies radiation-induced DNA damage. Additionally, Riluzole suppresses radiation-induced Vascular Endothelial growth factor A (VEGFA) expression indicating its ability to overcome endothelial cell mediated radioresistance. Collectively, these results establish Riluzole as a promising radiosensitizer for osteosarcoma, with the potential to improve SDRT efficacy by overcoming both tumor-intrinsic and microvasculature-mediated radioresistance. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=102 SRC="FIGDIR/small/681036v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1839ca2org.highwire.dtl.DTLVardef@1a05dcaorg.highwire.dtl.DTLVardef@16da8cborg.highwire.dtl.DTLVardef@64ce1d_HPS_FORMAT_FIGEXP M_FIG C_FIG This schematic illustrates the proposed mechanism by which Riluzole enhances SDRT efficacy in osteosarcoma by targeting both tumor cells and VEGFA-mediated pro-survival signaling in endothelial cells. Riluzole increases radiation-induced ROS levels, induces G2/M cell cycle arrest, and inhibits DNA repair in osteosarcoma cells, thereby overcoming intrinsic tumor radioresistance. It also suppresses tumor cell VEGFA expression, which may contribute to reduced pro-survival signaling in the angiogenic endothelial cells within the tumor microenvironment. Together, these effects sensitize osteosarcoma tumors to SDRT, improving therapeutic outcomes (Illustration created using BioRender (BioRender.com, 2025)).

cancer biology↗

bioRxiv2022

Room-temperature crystallography reveals altered binding of small-molecule fragments to PTP1B

Much of our current understanding of how small-molecule ligands interact with proteins stems from X-ray crystal structures determined at cryogenic (cryo) temperature. For proteins alone, room-temperature (RT) crystallography can reveal previously hidden, biologically relevant alternate conformations. However, less is understood about how RT crystallography may impact the conformational landscapes of protein-ligand complexes. Previously we showed that small-molecule fragments cluster in putative allosteric sites using a cryo crystallographic screen of the therapeutic target PTP1B (Keedy*, Hill*, 2018). Here we have performed two RT crystallographic screens of PTP1B using many of the same fragments, representing the largest RT crystallographic screens of a diverse library of ligands to date, and enabling a direct interrogation of the effect of data collection temperature on protein-ligand interactions. We show that at RT, fewer ligands bind, and often more weakly -- but with a variety of temperature-dependent differences, including unique binding poses, changes in solvation, new binding sites, and distinct protein allosteric conformational responses. Overall, this work suggests that the vast body of existing cryogenic-temperature protein-ligand structures may provide an incomplete picture, and highlights the potential of RT crystallography to help complete this picture by revealing distinct conformational modes of protein-ligand systems. Our results may inspire future use of RT crystallography to interrogate the roles of protein-ligand conformational ensembles in biological function.

biophysics↗