Biology subjects

Sharan, S.

Publications and source records attributed to Sharan, S..

6 recordsLinked to original sources

bioRxiv2026

Metabolic maintenance of breast cancer cells and metastases throughE-cadherin/YAP-dependent pyruvate carboxylase expression

Epithelial-mesenchymal transition (EMT) and glycolytic metabolism are well-characterized drivers of cancer progression and metastasis. However, most primary breast tumors and metastases express E-cadherin and the epithelial phenotype is associated with mitochondrial oxidative metabolism, yet the causality and relevance of these relationships and their underlying mechanisms remain poorly understood. Using a 3D culture model with mechano-stimulation, we found that E-cadherin promotes mitochondrial oxidative phosphorylation (OXPHOS) while reducing oxidative stress. Through pharmacological and genetic manipulations of inflammatory breast cancer (IBC) and/or triple negative breast cancer (TNBC) cell lines, we identified pyruvate carboxylase (PC) as an E-cadherin effector. Critically, restoring PC in E-cadherin-silenced cells rescued mitochondrial oxygen consumption and protection from oxidative stress. Co-expression of E-cadherin and PC was confirmed in breast cancer tissues and experimental lung metastases. Mechanistically, E-cadherin induced PC expression and OXPHOS via AKT-mediated activation of YAP/ /TEAD transcription factors, which are better known as supporting EMT. Clinically relevant AKT and TEAD inhibitors reduced both PC expression and oxidative respiration. Importantly, PC inhibition as monotherapy attenuated established experimental lung metastases and primary tumor burden in mice. Taken together, these findings reveal that E-cadherin-mediated cell-cell adhesions directly support mitochondrial metabolism through AKT-YAP/TEAD-PC signaling, identifying a therapeutic vulnerability in metastatic epithelial TNBC.

cancer biology↗

bioRxiv2025

Assessment of Imaging Mass Cytometry (IMC) as a Tool to Characterize Circulating Tumor Cells (CTCs) in Preclinical Mouse Models

Circulating tumor cells (CTCs), particularly multicellular clusters, are associated with poor prognosis and may provide insight into mechanisms of metastasis and therapy resistance. Unbiased approaches for functionally characterizing CTCs in liquid biopsies are therefore urgently needed. Here, we evaluate multiplex imaging mass cytometry (IMC) for CTC analysis in mice bearing human xenograft tumors. In a single-step workflow, IMC uses metal-conjugated antibodies to simultaneously detect numerous proteins and post-translational modifications in minimally processed, small-volume blood samples collected from the tail vein or heart. Using breast cancer cell lines and a patient-derived xenograft (PDX), we assessed a panel of antibodies, including human-specific markers such as Lamin B1 (LMNB1), to enable cross-species interpretation. Combined with manual review, HALO AI-based cell segmentation was used to identify CTCs and quantify marker expression. This approach enables studies of how genetic and pharmacologic interventions alter the properties of single CTCs and CTC clusters in tumor-bearing mice.

cancer biology↗

bioRxiv2025

A simple liquid 3D cell culture paradigm models oxidative mitochondrial metabolism of epithelial breast cancer cells with relevance for lung metastases.

Three-dimensional (3D) cell culture systems have emerged as powerful tools for modeling tumor biology in ex vivo settings. However, the diverse array of available 3D culture methods presents challenges in selecting the most appropriate model for specific research questions. This study provides a comparative analysis of breast cancer cells (SUM149, IBC-3, and MDA-MB-468) in the mammosphere culture (SphC) model or an "emboli" culture (EmC) model, which enrich for cancer stem cells and epithelial features, respectively. The EmC model, designed originally for inflammatory breast cancer, is characterized by media viscosity and mechanical rocking of the culture vessel. Notably, cells in EmC showed a distinct and durable reduction in cell proliferation ex vivo while demonstrating increased capacity to establish experimental lung metastases in vivo. Ultrastructural quantitative analysis of electron microscopy images suggested that cells in EmC acquire nuclear and mitochondrial features that resemble those of tumor tissue. Proteomics, single-cell transcriptomics, and metabolic flux analyses showed that cells in EmC and SphC favor mitochondrial oxidative metabolism (OXPHOS) and glycolysis, respectively. EmC rendered cells hypersensitive to OXPHOS inhibition, but more resistant to oxidative stress. Several genes associated with lung metastasis, including ID1, were specifically enriched in EmC. Given the emerging role of OXPHOS in cancer cell survival during dissemination and as established metastases, we propose that the EmC paradigm is a suitable ex vivo model to study signaling pathways relevant for tumor tissue and to assess drug sensitivities and resistance mechanisms of metastatic breast cancer cells ex vivo. SIGNIFICANCEThis study provides an in-depth characterization of a resource-efficient yet powerful 3D culture paradigm to improve the physiological relevance of ex vivo approaches. Applicable to epithelial cancers, this model offers a platform to accelerate the discovery of physiologically relevant signaling pathways and specific cancer cell vulnerabilities.

cancer biology↗

bioRxiv2023

Aging-related changes in expression and function of glutamate transporters in rat spinal cord astrocytes

Astrocytes are abundant and heterogeneous cell types in the CNS [1]. They promote neuronal health and survival and protect neurons from glutamate-induced excitotoxicity. In the spinal cord, astrocytes are present in both the dorsal horn (DH) and ventral horns (VH). However, only motor neurons in the VH are highly vulnerable to glutamate excitotoxicity. We hypothesize that the preferential vulnerability of motor neurons may underlie their spatial confinement to the VH, where astrocytes are differentially equipped with glutamate-handling machinery. With aging, glutamate excitotoxicity increases, suggesting compromised astrocytic glutamate handling. We tested our hypotheses by comparing astrocytic morphology, expression of glutamate transporters, and glutamate uptake function in the DH and VH using immunohistochemical staining, western blotting, and whole-cell patch-clamp electrophysiology. We found a global reduction in the numerical density and astroglial coverage in the spinal cord, with a prominent decline in the VH with aging. Astrocytic glutamate transporters, Excitatory amino acid transporter 1 (EAAT1) and Excitatory amino acid transporter 2 (EAAT2), show an overall reduction in expression with aging, with a more progressive decrease in the VH than DH. We performed whole-cell patch-clamp studies on DH and VH astrocytes to assess the functional outcome of the altered expression of EAATs with aging. Both VH and DH astrocytes showed a dramatic decline in glutamate uptake currents with aging, suggesting compromised glutamate handling in aging astrocytes. Our study suggests that astrocytes in the DH and VH undergo differential changes with aging, exhibiting compromised glutamate handling properties, which may be one of the key contributors to the late onset of neurodegenerative disorders.

neuroscience↗

bioRxiv2022

Stabilization of E-cadherin adhesions by COX-2/GSK3β signaling is a targetable pathway in metastatic breast cancer

Metastatic progression and treatment-resistance of breast cancer has been associated with epithelial-mesenchymal-transition including downregulation of E-cadherin (CDH1) expression, which can be initiated by inflammatory mediators such as COX-2. Recently, E-cadherin-mediated, cluster-based metastasis and treatment resistance has become more appreciated, though the mechanisms that maintain E-cadherin expression in this context are unknown. Through studies of inflammatory breast cancer and an in vitro tumor cell emboli culture paradigm, we identified a role for COX-2, a target gene of C/EBP{delta}, or its metabolite PGE2 in promoting protein stability of E-cadherin, {beta}-catenin and p120 catenin through inhibition of GSK3{beta}, without affecting CDH1 mRNA. The COX-2 inhibitor celecoxib downregulated E-cadherin complex proteins and caused cell death. Co-expression of E-cadherin and COX-2 was seen in breast cancer patients with poor outcome and, along with inhibitory GSK3{beta} phosphorylation, in patient-derived xenografts of triple negative breast cancer. Celecoxib alone decreased E-cadherin protein expression within xenograft tumors, reduced circulating tumor cells and clusters, and in combination with paclitaxel attenuated or regressed lung metastases. This study uncovered a mechanism by which metastatic breast cancer cells can maintain E-cadherin-mediated cell-cell adhesions and cell survival, suggesting that patients with COX-2+/E-cadherin+ breast cancer may benefit from targeting of the PGE2 signaling pathway.

cancer biology↗

bioRxiv2017

Improved Aedes aegypti mosquito reference genome assembly enables biological discovery and vector control

Female Aedes aegypti mosquitoes infect hundreds of millions of people each year with dangerous viral pathogens including dengue, yellow fever, Zika, and chikungunya. Progress in understanding the biology of this insect, and developing tools to fight it, has been slowed by the lack of a high-quality genome assembly. Here we combine diverse genome technologies to produce AaegL5, a dramatically improved and annotated assembly, and demonstrate how it accelerates mosquito science and control. We anchored the physical and cytogenetic maps, resolved the size and composition of the elusive sex-determining \"M locus\", significantly increased the known members of the glutathione-S-transferase genes important for insecticide resistance, and doubled the number of chemosensory ionotropic receptors that guide mosquitoes to human hosts and egg-laying sites. Using high-resolution QTL and population genomic analyses, we mapped new candidates for dengue vector competence and insecticide resistance. We predict that AaegL5 will catalyse new biological insights and intervention strategies to fight this deadly arboviral vector.

genomics↗