Biology subjects

Selvanesan, B. C.

Publications and source records attributed to Selvanesan, B. C..

4 recordsLinked to original sources

bioRxiv2025

AI-powered Deep Visual Proteomics reveals critical molecular transitions in pancreatic cancer precursors

Pancreatic ductal adenocarcinoma (PDAC) evolves through non-invasive precursor lesions, yet its earliest molecular events remain unclear. We established the first spatially resolved proteomic atlas of these lesions using Deep Visual Proteomics (DVP). AI-driven computational pathology classified normal ducts, acinar-ductal metaplasia (ADM), and pancreatic intraepithelial neoplasia (PanIN) from cancer-free organ donors (incidental, "iPanINs") and PDAC patients (cancer-associated, "cPanINs"). Laser microdissection of 96 discrete regions containing as few as 100 phenotypically matched cells and ultrasensitive mass spectrometry quantified a total of 8,512 proteins from formalin-fixed tissues. Distinct molecular signatures stratifying cPanINs from iPanINs, and remarkably, many cancer-associated proteins already marked histologically normal epithelium. Four core programs - stress adaptation, immune engagement, metabolic reprogramming, mitochondrial dysfunction - emerged early and intensified during progression. By integrating DVP with AI-guided tissue annotation, we demonstrate that molecular reprogramming precedes histological transformation, creating opportunities for earlier detection and interception of a near-uniformly lethal cancer. SignificanceOur spatially-resolved proteomics atlas uncovers distinct molecular signatures in pancreatic cancer adjacent precursor lesions, clearly diverging from those in incidental, cancer-free pancreatic lesions. Our deep proteomics dataset offers a valuable resource for identifying novel biomarkers and therapeutic targets, informed by the earliest cancer-associated molecular events in archival pancreatic tissues.

cancer biology↗

bioRxiv2024

Metabolic Reprogramming by Mutant GNAS Creates an Actionable Dependency in Intraductal Papillary Mucinous Neoplasms of the Pancreas

ObjectiveOncogenic "hotspot" mutations of KRAS and GNAS are two major driver alterations in Intraductal Papillary Mucinous Neoplasms (IPMNs), which are bona fide precursors to pancreatic ductal adenocarcinoma. We previously reported that pancreas-specific KrasG12D and GnasR201C co-expression in p48Cre; KrasLSL-G12D; Rosa26LSL-rtTA; Tg (TetO-GnasR201C) mice ("Kras;Gnas" mice) caused development of cystic lesions recapitulating IPMNs. Here, we aim to unveil the consequences of mutant GnasR201C expression on phenotype, transcriptomic profile, and genomic dependencies. DesignWe performed multimodal transcriptional profiling (bulk RNA sequencing, single cell RNA sequencing, and spatial transcriptomics) in the "Kras;Gnas" autochthonous model and tumor-derived cell lines (Kras;Gnas cells), where GnasR201C expression is inducible. A genome-wide CRISPR/Cas9 screen was conducted to identify potential vulnerabilities in KrasG12D;GnasR201Cco-expressing cells. ResultsInduction of GnasR201C - and resulting G(s)alpha signaling - leads to the emergence of a gene signature of gastric (pyloric type) metaplasia in pancreatic neoplastic epithelial cells. CRISPR screening identified the synthetic essentiality of glycolysis-related genes Gpi1 and Slc2a1 in KrasG12D;GnasR201C co-expressing cells. Real-time metabolic analyses in Kras;Gnas cells and autochthonous Kras;Gnas model confirmed enhanced glycolysis upon GnasR201C induction. Induction of GnasR201C made KrasG12D expressing cells more dependent on glycolysis for their survival. Protein kinase A-dependent phosphorylation of the glycolytic intermediate enzyme PFKFB3 was a driver of increased glycolysis upon GnasR201C induction. ConclusionMultiple orthogonal approaches demonstrate that KrasG12D and GnasR201C co-expression results in a gene signature of gastric pyloric metaplasia and glycolytic dependency during IPMN pathogenesis. The observed metabolic reprogramming may provide a potential target for therapeutics and interception of IPMNs. SUMMARYO_ST_ABSWhat is already known on this topicC_ST_ABSO_LIActivating "hotspot" mutations of KRAS and GNAS are found in a majority of Intraductal Papillary Mucinous Neoplasms (IPMNs). C_LIO_LIExpression of mutant KRAS and GNAS drives development of IPMN-like cystic lesions in the murine pancreas that eventually progress to pancreatic ductal adenocarcinoma (PDAC). C_LI What this study addsO_LIMutant GNAS and the resulting aberrant G(s)alpha signaling drives a transcriptional signature of gastric (pyloric type) metaplasia in IPMNs with mucin production. C_LIO_LIAberrant G(s)alpha signaling enhances glycolysis via protein kinase A-dependent phosphorylation of the glycolytic enzyme PFKFB3. C_LIO_LIEnhanced glycolysis in KRAS;GNAS-mutated IPMN cells is validated via multiple orthogonal approaches in vitro and in vivo and represents an actionable metabolic vulnerability. C_LI How this study might affect research, practice or policyO_LIThe present study provides mechanistic insight into how aberrant G(s)alpha signaling alters the biology of Kras-mutant pancreatic epithelial neoplasia through metaplastic and metabolic reprogramming. C_LIO_LITargeting glycolysis in IPMNs may represent both a therapeutic avenue as well as an opportunity for intercepting progression to invasive cancer. C_LI

cancer biology↗

bioRxiv2020

Nicotinamide combined with gemcitabine is an immunomodulatory therapy that restrains pancreatic cancer in mice

Treatments for pancreatic ductal adenocarcinoma (PDAC) are poorly effective, at least partly due to the tumors immune-suppressive stromal compartment. New evidence of positive effects on immune responses in the tumor microenvironment, compelled us to test the combination of gemcitabine (GEM), a standard chemotherapeutic for pancreatic cancer, with nicotinamide (NAM), the amide form of niacin (vitamin B3), in various mouse tumor models of pancreatic cancer, i.e. peritoneal or orthotopic of Panc-02 (KrasG12D) and orthotopic KPC (KrasG12D, p53R172H, Pdx1-Cre) grafts. A significant reduction in tumor weight and number of metastases was found, as well as a significant improved survival of the NAM+GEM group compared to all control groups. Immunohistochemistry and flow cytometry of pancreatic tumors showed a significant decrease in tumor-associated macrophages (TAM) and myeloid-derived suppressor cells (MDSC), an increase in the number of CD4 and CD8 T cells and the production of granzyme B in the NAM+GEM group. Moreover, T cell responses to tumor-associated antigen survivin were observed in spleens of the mice that received NAM+GEM but not in those that received single agents or saline. In addition, remodeling of the tumor stroma was observed with decreased collagen I and expression of hyaluronic acid binding protein, reorganization of the immune cells into lymph node like structures, and CD31 positive vessels. Expression profiling for a panel of immuno-oncology genes revealed significant changes in genes involved in migration and activation of T cells, attraction of dendritic cells, and epitope spreading. This study highlights the potential of NAM+GEM as immunotherapy for advanced pancreatic cancer.

immunology↗

bioRxiv2019

A new immunotherapeutic concept for pancreatic cancer using childhood vaccine recall antigens and Listeria

Pancreatic ductal adenocarcinoma is highly metastatic, poorly immunogenic, and immune suppression prevents T cell activation in the tumor microenvironment. We developed a microbial-based immunotherapeutic concept for selective delivery of a highly immunogenic tetanus toxoid protein (TT856-1313), into tumor cells by attenuated Listeria monocytogenes, and reactivation of pre-existing TT-specific memory T cells (generated during childhood) to kill infected tumor cells. Thus, TT here functions as an alternative for neoantigens. Treatment of KPC mice with Listeria-TT resulted in TT accumulation in tumors and inside tumor cells, and attraction of predominantly TT-specific memory CD4 T cells. Moreover, gemcitabine (GEM) combined with Listeria-TT significantly improved the migration of CD4 T cells into tumors and the production of perforin and granzyme B, turning cold tumors into immunological hot tumors. In vivo depletion of T cells in Listeria-TT+GEM-treated mice demonstrated CD4 T cell-mediated eradication of tumors and metastases (Mann-Whitney p<0.05). In addition, peritumoral lymph node like structures (LNS) were observed in close contact with the pancreatic tumors displaying CD4 T cells and CD8 T cells of KPC mice treated with Listeria-TT or Listeria-TT+GEM. The production of perforin and granzyme B was observed in LNS of KPC mice that received Listeria-TT+GEM. This combination not only reduced tumor burden (80%) and metastases (87%) significantly (p<0.05, Mann-Whitney), but also improved the survival time of KPC mice with advanced pancreatic cancer substantially (Mantel-Cox p<0.0001). Our results unveil new mechanisms of Listeria and GEM improving immunotherapy for PDAC.

immunology↗