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Varadan, V.

Publications and source records attributed to Varadan, V..

3 recordsLinked to original sources

SYS-Mut: Decoding the Functional Significance of Rare Somatic Mutations in Cancer

Current tailored-therapy efforts in cancer are largely focused on a small number of highly recurrently-mutated driver genes but therapeutic targeting of these oncogenes remains challenging. On the other hand, the vast number of genes mutated infrequently across cancers have received less attention, in part, due to a lack of understanding of their biologic significance. Here we present SYS-Mut, a systems biology platform that can robustly infer the biologic consequences of somatic mutations by integrating routine multi-omic profiles in primary tumors. We established the accuracy of SYS-Mut by recapitulating the functional impact of known driver genes in PanCancer datasets. Subsequent application of SYS-Mut on low-frequency gene mutations in Head and Neck Cancers (HNSC), followed by molecular and pharmacogenetic validation, revealed the lipidogenic network as a novel therapeutic vulnerability in aggressive HNSC. SYS-Mut is thus a robust scalable framework that enables discovery of new targetable avenues in cancer.

cancer biology↗

The EphB2-MYC Axis is a Major Determinant of Barrett's Pathobiology and a Therapeutic Vulnerability in Esophageal Cancer

Esophageal adenocarcinoma (EAC), a highly aggressive cancer with limited therapeutic options, often arises in the backdrop of a molecularly-complex esophageal metaplasia disorder, Barretts Esophagus (BE). Using transcriptomics and systems biology analyses of treatment-naive malignant/pre-malignant biopsy tissues, we found Eph receptor B2 (EphB2) tyrosine kinase signaling to be frequently hyperactivated during early stages of EAC development, and across the BE-EAC continuum. Functional studies revealed EphB2 to be an upstream post-translational regulator of c-MYC activity and as a key molecular dependency in BE/EAC. Single-cell transcriptomics in a porcine esophageal 3D spheroid model showed enhanced EphB2 and MYC activity to be significantly associated with BE-like cell fate. shRNA-based knockdown of EphB2 or small molecule inhibitors of MEK, that modulate MYC protein stability, proved effective in suppressing EAC tumor growth in vivo. These findings point to EphB2-MYC axis as an early promoter of EAC and a novel therapeutic vulnerability in this increasingly-prevalent esophageal malignancy. STATEMENT OF SIGNIFICANCEWe identify EphB2 signaling as a potential master regulator and early promoter of esophageal adenocarcinoma, and the proto-oncogene MYC as a key downstream effector of EphB2 function. Targeting the EphB2-MYC axis could be a promising therapeutic strategy for these often refractory and lethal EAC tumors.

cancer biology↗

Cell Surface Multimeric Assemblies Regulate Canonical and Noncanonical EphA2 Receptor Tyrosine Kinase Signaling

The EphA2 receptor tyrosine kinase mediates ligand-induced canonical signaling associated with tumor suppression and ligand-independent noncanonical signaling implicated in tumor progression. Using time-resolved fluorescence spectroscopy in live cells, we find that unliganded EphA2 receptors pre-assemble into multimers, which is mediated by two symmetric and one asymmetric interfaces in the ectodomain. Upon ligand binding, EphA2 receptors are further assemble into large clusters that also requires the three interfaces. Functionally, disrupting either the symmetric or asymmetric contacts individually blocks the autorecycling of the EphA2 apo receptor. However, only symmetric contact disruption promotes noncanonical signaling and inhibits ligand-induced catalytic activation and endocytosis, which are associated with increased cell migration in vitro and reduced survival in a syngeneic murine glioblastoma model. Our results reveal the pivotal role of EphA2 assembly in dictating canonical vs. noncanonical signaling, and identify the precise molecular interfaces that mediate the formation of the EphA2 signaling clusters.

biophysics↗