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Biology subjects

Chowdary, R.

Publications and source records attributed to Chowdary, R..

3 recordsLinked to original sources

Drug and single-cell gene expression integration identifies sensitive and resistant glioblastoma cell populations

Glioblastoma (GBM) remains the most common and lethal adult malignant primary brain cancer with few treatment options. A significant issue hindering GBM therapeutic development is intratumor heterogeneity. GBM tumors contain neoplastic cells within a spectrum of different transcriptional states. Identifying effective therapeutics requires a platform that predicts the differential sensitivity and resistance of these states to various treatments. Here, we developed a novel framework, ISOSCELES (Inferred cell Sensitivity Operating on the integration of Single-Cell Expression and L1000 Expression Signatures), to quantify the cellular drug sensitivity and resistance landscape. Using single-cell RNA sequencing of newly diagnosed and recurrent GBM tumors, we identified compounds from the LINCS L1000 database with transcriptional response signatures selectively discordant with distinct GBM cell states. We validated the significance of these findings in vitro, ex vivo, and in vivo, and identified a novel combination of an OLIG2 inhibitor and Depatux-M for GBM. Our studies suggest that ISOSCELES identifies cell states sensitive and resistant to targeted therapies in GBM and that it can be applied to identify new synergistic combinations. HighlightsO_LIIntegration of GBM single-cell RNA sequencing data with L1000-derived drug response signatures facilitates clustering of tumor cells and small molecules on cell-drug connectivity. C_LIO_LICell-drug connectivity predicts the identities of drug-sensitive and resistant cell states. C_LIO_LIIn silico perturbation analysis using cell-drug connectivity predicts drug-induced changes in the cell-drug connectivity landscape in vivo. C_LIO_LIIn silico perturbation analysis to predict drug-induced changes in the tumor cell-drug connectivity landscape predicts drug combinations that synergize in vivo to extend survival. C_LI

cancer biology↗

Identification of disease-specific vulnerability states at the single-cell level

Intratumor heterogeneity in glioblastoma (GBM) impedes successful treatment as it is not obvious which tumor cells should be targeted. Here, we posit that single-cell-resolution transcriptomic data can be integrated with loss-of-function screens to identify the most critical cells to target within a tumor. We parsed CRISPR screen data from the Dependency Map (DepMap) Consortium and identified a GBM Dependency Signature (GDS) - 168 genes that are essential for GBM cell viability in vitro. Through similarity scoring of GDS transcriptomic profiles in single-cell RNA-sequencing (scRNA-seq) data and iterative hierarchical clustering, we identify and report 3 single-cell vulnerability states (VS) characterized in 49 GBM tumors using both scRNA-seq and spatial transcriptomic data. These VS reflect single-cell gene dependencies and differ significantly in enrichment profiles and spatial distributions. Additionally, each VS is differently sensitive to cancer drugs, with VS2 solely responsive to temozolomide treatment. Importantly, the proportion of VS in each GBM tumor is variable, suggesting a means of stratifying patients in clinical trials. Collectively, we have developed a novel computational pipeline to identify unique vulnerability states in GBM and other cancers, which can be used to identify existing or novel drugs for incurable diseases.

cancer biology↗

In Vitro Patients Derived Glioma Culture Model: Identification of Aggressive, Drug Resistant Phenotype Among Low-Grade Gliomas

BackgroundClinical management of glioma is crucial irrespective of tumor grade. Despite newer treatment modalities, the prognosis of glioma is abysmal and, survival statistics are not remarkable. In vitro glioma culture is emerging as a standard model to get insight into phenotypic transformation, drug response, and tumor relapse. In this viewpoint, this study established comprehensive patient-specific short-term cultures comprising low-grade, and high-grade glioma, and evaluated their pertinence in the potential disease management. Methods50 patients with MRI diagnosed glioma were recruited for this study. Primary glioma cultures established from fresh surgical tumor tissues, which were then evaluated for their intrinsic growth kinetics, response to temozolomide, and expression profile of Glial-Mesenchymal Transition (GMT) markers along with an oncogenic marker, cMyc. ResultsShort-term glioma culture was successfully established in 40 clinical samples. Glioma culture, irrespective of tumor grade, displayed two distinct patterns of growth kinetics - one with shorter doubling time (high-proliferating) and another group with longer doubling time (low-proliferating). Significant distinctive features were noticed between these two groups in terms of response to temozolomide, the expression pattern of GMT markers and their association with 1p/19q co-deletion and p53 expression. ConclusionOur findings effectively demonstrated the practicality of the development of short-term glioma culture toward a functional approach for personalized medicine. Our study revealed the presence of a highly proliferative, drug-resistant phenotype irrespective of tumor grade. Hence, short-term culture could be an important prognostic tool for predicting patient clinical responses and cue about imminent tumor relapse.

cancer biology↗