Biology subjects

Gadde, S.

Publications and source records attributed to Gadde, S..

6 recordsLinked to original sources

bioRxiv2026

Therapeutic targeting of MYC- and MYCN-driven medulloblastoma with a novel MYC degrader molecule

BackgroundMedulloblastoma (MB) is the most common malignant brain tumour in children, and aggressive subgroups are frequently driven by the oncoproteins MYC or MYCN. Direct therapeutic targeting of MYC/MYCN has been challenging because of their intrinsically disordered protein structures. The aim of this study was to determine whether novel SE486-11 analogues (UNSW-SCs) can therapeutically target MYC/MYCN-driven MB. MethodsThe anticancer activity of UNSW-SCs was assessed in MB cell lines with differential MYC/MYCN expression. Target engagement was evaluated using surface plasmon resonance and drug affinity responsive target stability assays. Blood-brain barrier penetration, MYC/MYCN protein degradation, cell cycle effects, apoptosis, DNA damage, and synergy with histone deacetylase (HDAC) inhibitors were examined. Therapeutic efficacy was evaluated in murine models of MYC- and MYCN-driven human MB. ResultsUNSW-SCs showed potent anticancer activity, with preferential selectivity toward MB cells expressing high MYC/MYCN levels and IC50 values ranging from 0.22 to 1.18 M. The lead molecule, UNSW-SC-22, directly bound MYC, crossed the blood-brain barrier, and achieved a brain-to-plasma ratio of 1.44 at peak concentrations. UNSW-SC-22 induced MYC/MYCN-dependent cytotoxicity associated with enhanced proteasomal degradation, cell cycle arrest, apoptosis, and DNA damage. Combined treatment with HDAC inhibitors further reduced MYC/MYCN protein levels, increased DNA damage, and enhanced apoptosis. In vivo, UNSW-SC-22, either alone or with entinostat, significantly suppressed intracranial tumour growth and prolonged survival. ConclusionsUNSW-SC-22 is a brain-penetrant MYC/MYCN-targeting molecule with potent preclinical activity in MYC/MYCN-driven MB, supporting its development as a monotherapy or combination strategy with HDAC inhibition. Key PointsO_LIUNSW-SC-22 directly targets MYC/MYCN in medulloblastoma. C_LIO_LIUNSW-SC-22 crosses the blood-brain barrier and prolongs survival. C_LIO_LIHDAC inhibition enhances UNSW-SC-22 activity in MYC-driven cells. C_LI Importance of the StudyMYC- and MYCN-driven medulloblastomas remain among the most aggressive paediatric brain tumours, yet direct pharmacological targeting of MYC/MYCN has historically been difficult. This study identifies UNSW-SC-22 as a novel brain-penetrant small molecule that directly engages MYC/MYCN and promotes proteasomal degradation, leading to tumour cell death. Compared with prior MYC-directed approaches, UNSW-SC-22 combines direct target engagement, blood-brain barrier penetration, and in vivo efficacy in orthotopic MYC- and MYCN-driven medulloblastoma models. The study further demonstrates that combining UNSW-SC-22 with histone deacetylase inhibition enhances MYC/MYCN suppression, DNA damage, apoptosis, and survival benefit. These findings provide a translational framework for developing MYC/MYCN degradation as a therapeutic strategy for high-risk medulloblastoma and support future pharmacological optimisation, biomarker-guided patient selection, and combination therapy development.

cancer biology↗

bioRxiv2024

Development of 3-in-1 nanotherapeutic strategies for ovarian cancer

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/604002v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@1c2d3e3org.highwire.dtl.DTLVardef@1e4e73eorg.highwire.dtl.DTLVardef@109aceeorg.highwire.dtl.DTLVardef@387843_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOTOCC_FLOATNO C_FIG Among gynecological cancers, ovarian cancer causes the most fatality. Platin-based chemotherapy is the primary therapeutic option, but it is limited by a variety of drug resistance mechanisms. Ovarian cancer is a complex and challenging disease to treat, and combination approaches have shown stronger efficacy than a single drug alone. However, they still need to overcome challenges, such as the non-selective distribution of drugs, and side effects caused by each drug in the combination. To overcome these issues, here we explored a 3-in-1 combination nanotherapeutic approach containing cisplatin, olaparib, and metformin for ovarian cancer. To encapsulate hydrophilic cisplatin and metformin inside the nanoparticle (NP) core, we developed cisplatin polymer prodrugs and metformin derivatives. Our results showed successful development of 3-in-1 NPs containing cisplatin, olaparib, and metformin, and they are stable in the physiological conditions. In vitro evaluation showed each agent in the 3-in-1 NPs is active and exerts therapeutic effects, contributing to ovarian cancer cell killing at lower concentrations. These results provide insight into developing novel nanotherapeutic strategies for improving ovarian cancer treatment.

bioengineering↗

bioRxiv2024

Nanoparticles co-delivering siRNA and mRNA for simultaneous restoration and silencing of gene/protein expression in vitro and invivo

RNA-based agents such as siRNA, miRNA, and mRNA can selectively manipulate gene expression/proteins and have the potential to revolutionize the current therapeutic strategies for various diseases, including cancer. To address the poor stability and inherent limitations of RNA agents, nanoparticle (NP) platforms have been developed to deliver functional mRNA or siRNA inside the cells. Recent studies have focused on either siRNA to knock down proteins causing drug resistance or mRNA technology to introduce tumor suppressors. However, complex diseases like cancer need multi-targeted approaches to selectively target multiple gene expressions/proteins. In this proof-of-concept study, we developed co-delivery nanoparticles containing Luc-mRNA and siRNA-GFP as model RNA agents ((M+S)-NPs) and assessed their effects in vitro and in vivo. Our studies show that NPs can effectively deliver both functional mRNA and siRNA together, simultaneously impacting the expression of two genes/proteins in vitro. Additionally, after in vivo administration, co-delivery NPs successfully knocked down GFP while introducing luciferase in a TNBC mouse model, indicating our NPs have the potential to develop RNA-based anticancer therapeutics. These studies pave the way to develop RNA-based, multitargeted, multi-delivery approaches for complex diseases like cancer. TOC O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/600196v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@1668ae2org.highwire.dtl.DTLVardef@1283491org.highwire.dtl.DTLVardef@9336daorg.highwire.dtl.DTLVardef@f654c5_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

Interaction of SCoV-2 NSP7 or NSP8 alone may cause constriction of the RNA entry channel in NSP12: Implications for novel RdRp inhibitor drug discovery

RNA-dependent RNA polymerase (RdRP) is a critical component of the RNA virus life cycle, including SCoV-2. Among the Coronavirus-encoded proteins, non-structural protein 12 (NSP12) exhibits polymerase activity in collaboration with one unit of NSP7 and two units of NSP8, constituting the RdRp holoenzyme. While there is abundant information on SCoV-2 RdRp-mediated RNA replication, the influence of interplay among NSP12, NSP7, and NSP8 on template RNA binding and primer extension activity remains relatively unexplored and poorly understood. Here, we recreated a functional RdRp holoenzyme in vitro using recombinant SCoV-2 NSP12, NSP7, and NSP8, and established its functional activity. Subsequently, molecular interactions among the NSPs in the presence of a variety of templates and their effects on polymerase activity were studied, wherein we found that NSP12 alone exhibited notable polymerase activity that increased significantly in the presence of NSP7 and NSP8. However, this activity was completely shut down, and the template RNA-primer complex was detached from NSP12 when one of the two cofactors was present. Through computational analysis, we found that the template RNA entry channel was more constricted in the presence of one of the two cofactors, which was relatively more constricted in the presence of NSP8 compared to that in the presence of NSP7. In conclusion, we report that NSP7 and NSP8 together synergise to enhance the activity of NSP12, but antagonise when present alone. Our findings have implications for novel drug development, and compounds that obstruct the binding of NSP7 or NSP8 to NSP12 can have lethal effects on viral RNA replication.

molecular biology↗

bioRxiv2020

Foam cell induction activates AMPK but uncouples its regulation of autophagy and lysosomal homeostasis

The dysregulation of macrophage lipid metabolism drives atherosclerosis. AMP-activated protein kinase (AMPK) is a master regulator of cellular energetics and plays essential roles regulating macrophage lipid dynamics. Here, we investigated the consequences of atherogenic lipoprotein-induced foam cell formation on downstream immunometabolic signaling in primary mouse macrophages. A variety of atherogenic low-density lipoproteins (acetylated, oxidized and aggregated forms) activated AMPK signaling in a manner that was in part, due to CD36 and calcium-related signaling. In quiescent macrophages, basal AMPK signaling was crucial for maintaining markers of lysosomal homeostasis, as well as levels of key components in the lysosomal expression and regulation network. Moreover, AMPK activation resulted in targeted up-regulation of members of this network via transcription factor EB. However, in lipid-induced macrophage foam cells, neither basal AMPK signaling nor its activation affected lysosomal-associated programs. These results suggest that while the sum of AMPK signaling in cultured macrophages may be anti-atherogenic, atherosclerotic input dampens the regulatory capacity of AMPK signaling.

cell biology↗

bioRxiv2019

Characterization of LXR-activating nanoparticle formulations in primary mouse macrophages

Activation of the transcription factor liver X receptor (LXR), has shown to be efficient at curbing aberrant lipid metabolism and inflammation. While small molecule delivery via nanomedicine has promising applications for a number of chronic diseases, there remain questions as to how nanoparticle formulation might be tailored to suit different tissue microenvironments and aid in drug delivery. In the current study, we compared the drug delivery capability of three nanoparticle (NP) formulations encapsulating the LXR activator, GW-3956. We observed little difference in the base characteristics of standard PLGA-PEG NP when compared to two redox-active polymeric NP formulations (DD and DB). Moreover, we also observed similar uptake of these NP into primary mouse macrophages. After an initial acute uptake period and using the transcript and protein expression of the cholesterol efflux protein ATP binding cassette A1 (ABCA1) as a readout, we determined that while the induction of transcript expression was similar between NPs, treatment with the redox-sensitive DB formulation resulted in a higher level of ABCA1 protein 24 h after the removal of the drug-containing NPs. Our results suggest that NP formulations responsive to cellular cues may be an effective tool for targeted and disease-specific drug release.

biochemistry↗