Biology subjects

Markovic, M.

Publications and source records attributed to Markovic, M..

5 recordsLinked to original sources

bioRxiv2025

Mevalonate pathway activation in Ewing sarcoma reveals a 3D-specific synergy between statins and BCL-xL inhibition

Bone sarcomas are rare and aggressive pediatric cancers with limited progress in targeted therapy development, in part due to the poor physiological relevance of conventional two-dimensional (2D) culture systems used for preclinical testing. To address this gap, we developed a standardized three-dimensional (3D) culture and drug-testing platform for Ewing sarcoma (ES) and osteosarcoma (OS) that more accurately recapitulates in vivo tumor biology. Across 3D spheroids, bioprinted constructs, and patient-derived xenograft (PDX) cultures, we observed a consistent activation and dependency on the mevalonate pathway in ES. Leveraging this platform, we identified a selective therapeutic synergy between statins, which inhibit mevalonate pathway flux, and BCL-xL inhibitors, a vulnerability that was not detectable in 2D cultures. These findings highlight the mevalonate pathway as a targetable metabolic dependency in ES and demonstrate how physiologically grounded 3D models can uncover clinically actionable treatment strategies that remain hidden in traditional 2D systems. Our findings show that 3D tumor models can expose actionable metabolic vulnerabilities obscured by traditional approaches, supporting their use in rational combination therapy discovery for aggressive pediatric sarcomas.

cancer biology↗

bioRxiv2021

Spatial epitope barcoding reveals subclonaltumor patch behaviors

Intratumoral variability is a seminal feature of human tumors contributing to tumor progression and response to treatment. Current technologies are unsuitable to accurately track phenotypes and subclonal evolution within tumors, especially in response to genetic manipulations. Here, we developed epitope combinatorial tags (EpicTags), which we coupled to multiplexed ion beam imaging (EpicMIBI) for in situ tracking of barcodes within tissue microenvironments. Using this platform, we dissected the spatial component of cell lineages and phenotypes in a xenograft model of small-cell lung cancer. We observed emergent properties from mixed clones leading to the preferential expansion of subclonal patches for both neuroendocrine and non-neuroendocrine cancer cell states in this model. In tumors harboring a fraction of PTEN-deficient cancer cells, we uncovered a non-autonomous increase of subclonal patch size in PTEN wildtype cancer cells. EpicMIBI can facilitate in situ interrogation of cell-intrinsic and cell-extrinsic processes involved in intratumoral heterogeneity.

cancer biology↗

bioRxiv2019

Immunomodulatory effects of extract of Ganoderma lucidum basidiocarps cultivated on alternative substrate

The aim of the study was to investigate if there are any differences in effects of extracts of commercially (GC) and alternatively (wheat straw) (GA) cultivated Ganoderma lucidum basidiocarps on properties of peritoneal macrophages (PM) and monocyte-derived dendritic cells (MoDCs). GA extract stronger stimulated the metabolic and phagocytic activity of PMs, their adhesion capability and ability to produce ROS and NO compared to GC. Both tested extracts significantly increased allostimulatory and Th1 polarization capacity of simultaneous TLR3 and TLR7-activated MoDCs, but GA extract was more effective. The GA extract increased the production of ROS and NO by TLR4 stimulated PMs and up-regulated the production of certain cytokines as well as allostimulatory and Th1 polarization capacity of MoDCs. The GA extract could be a potent immunostimulatory agent for activation of MoDCs with the simultaneous engagement of TLRs that seems to be a promising strategy for preparation of DC-based anti-tumor vaccines.

immunology↗

bioRxiv2018

Adaptive disinhibitory gating by VIP interneurons permits associative learning

Learning drives behavioral adaptations necessary for survival. While plasticity of excitatory projection neurons during associative learning is studied extensively, little is known about the contributions of local interneurons. Using fear conditioning as a model for associative learning, we find that behaviorally relevant, salient stimuli cause learning by tapping into a local microcircuit consisting of precisely connected subtypes of inhibitory interneurons. By employing calcium imaging and optogenetics, we demonstrate that vasoactive intestinal peptide (VIP)-expressing interneurons in the basolateral amygdala are activated by aversive events and provide an instructive disinhibitory signal for associative learning. Notably, VIP interneuron responses are plastic and shift from the instructive to the predictive cue upon memory formation. We describe a novel form of adaptive disinhibitory gating by VIP interneurons that allows to discriminate unexpected, important from irrelevant information, and might be a general dynamic circuit motif to trigger stimulus-specific learning, thereby ensuring appropriate behavioral adaptations to salient events.

neuroscience↗

bioRxiv2017

Central Amygdala Circuits Modulate Food Consumption Through A Positive Valence Mechanism

The complex behaviors underlying the pursuit and consumption of rewards are integral to an organisms survival. The hypothalamus and mesolimbic dopamine system are key mediators of these behaviors, yet regulation of appetitive and consummatory behaviors outside of these regions is not well understood. The central nucleus of the amygdala (CeA) is implicated in feeding and reward behavior, but the specific neural players and circuit mechanisms that positively regulate these behaviors remain unclear. Here, we define the neuronal mechanisms by which the CeA promotes consumption of food. We show, using in vivo activity manipulations and Ca2+ imaging, that CeA GABAergic neurons expressing the serotonin receptor 2a (Htr2a) modulate food consumption in multiple contexts, promote positive reinforcement and are active in vivo during eating. We demonstrate using electrophysiology, anatomical tracing methods and in vivo optogenetics that both intra-CeA and long-range circuit mechanisms underlie these functional effects. Finally, we show that CeAHtr2a neurons are poised to regulate food consumption through inputs from feeding-relevant brain regions. Our study highlights a mechanism by which defined CeA neural circuits positively regulate food consumption.

neuroscience↗