Biology subjects

Dongre, A.

Publications and source records attributed to Dongre, A..

7 recordsLinked to original sources

bioRxiv2026

MHC-I downregulation is associated with immune-evasion in breast cancers with heterogeneous activation of epithelial-mesenchymal plasticity

Cancer cell-intrinsic epithelial-mesenchymal plasticity (EMP) drives carcinoma progression through increased intratumoral heterogeneity and an immunosuppressive tumor microenvironment (TME). Specifically, EMP activation in murine mammary carcinomas results in exclusion of CD8+ T-cells and recruitment of immunosuppressive M2-like macrophages, resulting in resistance to anti-CTLA-4 immune checkpoint blockade (ICB) therapy. Notably, mixed E-qM tumors in which only 10% of cancer cells have activated EMP are resistant anti-CTLA-4 immune checkpoint blockade (ICB) therapy. This suggests that minority fractions of qM cancer cells could, in theory, exert immunosuppressive effects on surrounding E cancer and immune cells to shield the entire heterogeneous tumor against immune attack. However, this has not yet been demonstrated. Here, we use spatial transcriptomic profiling to demonstrate that mixed E-qM tumors assemble immunosuppressive cellular niches. Furthermore, E cancer cells within mixed E-qM tumors experience long-term MHC-I downregulation leading to resistance to elimination by CD8+ T-cells. This is associated with the exclusion of T-cells from the tumor core and a dysfunctional phenotype in the remaining CD8+ T-cells. qM cancer cells recruit immunosuppressive M2-like macrophages to mixed tumors, which further downregulates E cancer cell-intrinsic MHC-I levels. Finally, we demonstrate that human triple-negative breast cancers with increased EMP activation exclude T-cells from the tumor core. Together, these findings reveal that qM cancer cells modulate the immune infiltrate of mixed tumors, promoting MHC-I downregulation and evasion of immunological control by CD8+ T-cells.

cancer biology↗

bioRxiv2026

Feline mammary carcinomas display evidence of stemness, epithelial-mesenchymal plasticity, and metastasis-associated M2-like macrophage infiltration

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer-a consequence of high proliferation rates, stemness, epithelial-mesenchymal plasticity, and immune evasion. Feline mammary carcinomas (FMCs) are spontaneous mammary gland cancers associated with high rates of metastasis and death. The aggressive biological behavior of FMCs, as well as their lack of expression of hormone receptors, make FMCs an excellent naturally-occurring model of human triple-negative breast cancer (TNBC). Therefore, we investigated whether FMCs of increasing histologic grade (I-III) harbor characteristics comparable to human TNBC. We performed immunohistochemistry using markers of proliferation (Ki67), stemness (Sox2), and epithelial-mesenchymal plasticity (E-cadherin, vimentin). We found that FMCs expressed high levels of Sox2 and vimentin together with a grade-associated increase in Ki67 expression. Apart from these cancer cell-intrinsic properties, knowledge on the tumor microenvironment of FMCs is limited. To this end, we assessed the presence of T-cells (CD3), total macrophages (Iba1), and immunosuppressive M2-like macrophages (CD204) in FMCs. High-grade FMCs showed increased M2-like macrophage infiltration. Moreover, samples with evidence of vascular invasion and lymph node metastasis displayed increased total and M2-like macrophage infiltration. These findings suggest that the presence of intratumoral macrophages is associated with the biological aggressiveness and metastatic potential of FMCs. Taken together, our results support FMCs as a translational model of human TNBC.

cancer biology↗

bioRxiv2025

Insights into the mechanism of succinimide formation in an archaeal glutaminase.

Succinimide (SNN), an intermediate formed during asparaginyl deamidation or aspartyl dehydration in proteins, is generally hydrolysis-prone, leading to isomerization to L/D /{beta}-aspartyl residue, with the latter being considered deleterious to protein structure and function. An unusually stable SNN-mediated conformational rigidity through restriction of the backbone dihedral angle, {psi}, enhances the thermostability of glutamine amidotransferase (GATase) from Methanocaldococcus jannaschii (Mj). Although several structural features involved in maintaining a stable SNN and imparting SNN-mediated thermostability have been identified in MjGATase, the residues in the protein that catalyse the rapid and complete conversion of Asn109 to SNN remain unknown. Here, we investigated several site-directed mutants of MjGATase for their ability to retain Asn109 side chain in the unmodified form. Mass spectrometric analysis of 10 single mutants enabled the identification of residues that impacted the proportion of SNN and Asn population in the protein sample. This led to the generation of two double mutants that retained intact Asn109 side chain as observed in the mass spectra and crystal structures. These mutants with intact Asn residue at position 109, displayed lower thermal stability than the protein with the SNN modification. Further understanding of the deprotonation mechanism was addressed using QM/MM MD metadynamics simulations. HighlightsO_LIStable succinimide (SNN) arising from deamidation of Asn109 residue imparts hyperthermostability to MjGATase. C_LIO_LIExamination of the structure of MjGATase suggests neighbouring residues playing possible roles in deamidation and cyclization. C_LIO_LIExamination by LC-MS of single site-directed mutants of residues contacting SNN revealed varied levels of intact Asn109 enabling generation of double mutants with complete absence of deamidation. C_LIO_LIPresence of intact Asn109 confirmed by X-ray crystallography highlights the role of Y158, D110, and K151 in mediating SNN formation. C_LIO_LIQM/MM MD metadynamics simulations support experimental findings. C_LI

biochemistry↗

bioRxiv2025

Epithelial-Mesenchymal Plasticity is Associated with Immunosuppressive Features in Canine Mammary Carcinomas

Epithelial-mesenchymal plasticity (EMP) is a cellular process activated in carcinoma cells to drive invasiveness, metastasis, and chemoresistance. Recently, we have demonstrated that activation of the EMP program also results in the assembly of an immunosuppressive tumor microenvironment and resistance to immunotherapy in an immunocompetent orthotopic murine model. However, it has yet to be shown whether these findings can be translated to canine carcinomas. Here, we show that in spontaneous canine mammary carcinomas (CMCs), which share similar histopathologic, molecular, and clinical features with human breast cancers, EMP activation is linked to the recruitment of immunosuppressive cells including regulatory T-cells and M2-like macrophages. Additionally, through transcriptomic profiling of CMCs, we identify that the glycoprotein CD109 is associated with EMP-mediated immunosuppression across canine, murine, and human breast cancer models. CD109 has been previously associated with tumorigenicity, but not immunosuppression in cancers of any species. Finally, we identified upregulation of several immunosuppressive paracrine factors across multiple canine carcinomas, including oral squamous cell carcinoma, urothelial carcinoma, and pulmonary carcinoma samples. These findings demonstrate for the first time that the EMP program is associated with immunosuppression in canine carcinomas, with direct translational implications for human breast cancers.

cancer biology↗

bioRxiv2025

Post-Translational Modifications Remodel Proteome-Wide Ligandability

Post-translational modifications (PTMs) vastly expand the diversity of human proteome, dynamically reshaping protein activity, interactions, and localization in response to environmental, pharmacologic, and disease-associated cues. While it is well established that PTMs modulate protein function, structure, and biomolecular interactions, their proteome-wide impact on small-molecule recognition--and thus druggability--remains largely unexplored. Here, we introduce a chemical proteomic strategy to delineate how PTM states remodel protein ligandability in human cells. By deploying broad profiling photoaffinity probes, we identified over 400 functionally diverse proteins whose ability to engage small molecules is impacted by phosphorylation or N-linked glycosylation status. Integration of binding site mapping with structural analyses revealed a diverse array of PTM-dependent pockets. Among these targets, we discovered that the phosphorylation status of common oncogenic KRAS mutants impact the action of small molecules, including clinically approved inhibitors. These findings illuminate an underappreciated, PTM-governed layer of proteome plasticity and uncover opportunities for the development of chemical probes to selectively target proteins in defined modification states.

biochemistry↗

bioRxiv2025

CD4+ T-cells sensitize quasi-mesenchymal breast tumors lacking CD73 to anti-CTLA4 immune checkpoint blockade therapy

Although immune checkpoint blockade therapy has generated dramatic responses in certain cancer types, breast tumors are largely unresponsive. Epithelial-mesenchymal plasticity leads to the assembly of an immunosuppressive tumor microenvironment and drives resistance of breast tumors to immunotherapies. Importantly, targeting CD73 completely sensitizes quasi-mesenchymal breast tumors to anti-CTLA4 immune checkpoint blockade therapy. However, the mechanism(s) of sensitization remained unknown. We demonstrate that targeting CD73 in quasi-mesenchymal breast tumors sensitizes them to anti-CTLA4 immune checkpoint blockade therapy in a CD4+ T-cell dependent manner. Moreover, epithelial-mesenchymal plasticity results in elevated expression of cancer cell-intrinsic CD73 in human triple negative breast cancers. Given the ability of quasi-mesenchymal cancer cells to metastasize and resist multiple therapies, these findings can instruct the formation of novel translational strategies for the treatment of human breast cancers. These findings also bring to the forefront the attractive possibility of utilizing the phenotypic plasticity of cancer cells along with CD73 and CD4+ T-cells as a predictive criterion for immunotherapy responsiveness. TeaserTargeting CD73 sensitizes breast cancer cells with mesenchymal traits to anti-CTLA4 therapy in a CD4+ T-cell dependent manner.

cancer biology↗

bioRxiv2018

Degradation of the extracellular matrix is part of the pathology of ulcerative colitis

The scientific value of re-analyzing existing datasets is often proportional to the complexity of the data. Proteomics data are inherently complex and can be analyzed at many levels, including proteins, peptides, and post-translational modifications to verify and/or develop new hypotheses. In this paper, we present our re-analysis of a previously published study comparing colon biopsy samples from ulcerative colitis (UC) patients to non-affected controls. In addition to confirming and reinforcing the original finding of upregulation of neutrophil extracellular traps (NETs), we report novel findings, including that Extracellular Matrix (ECM) degradation and neutrophil maturation are involved in the pathology of UC. The pharmaceutically most relevant differential protein expressions were confirmed using immunohistochemistry as an orthogonal method. As part of this study, we also compared proteomics data to previously published mRNA expression data. These comparisons indicated compensatory regulation at transcription levels of the ECM proteins we identified and open possible new venues for drug discovery.

molecular biology↗