Biology subjects

Miousse, I. R.

Publications and source records attributed to Miousse, I. R..

4 recordsLinked to original sources

bioRxiv2025

Pancreatic tumor microenvironment reprogramming via alloantigen-expressing virotherapy elicits tumor rejection and improves immunotherapy response

Pancreatic ductal adenocarcinoma (PDAC), the most common malignant type of pancreatic cancer, is characterized by a dense desmoplastic stroma, low neoantigen burden, and a highly immunosuppressive tumor microenvironment (TME), which severely limit cytotoxic T-cell infiltration and the efficacy of immune therapies. Here, we present a novel strategy harnessing acute transplant rejection mechanisms by employing a recombinant oncolytic rVMG vector engineered to express the murine H-2Kk MHC class I alloantigen (rVMG-H-2Kk), thereby inducing tumor-specific antigenic mismatch responses. In vitro, rVMG-H-2Kk exhibited strong replication and cytolytic activity while inducing cell surface expression of both H-2Kk and endogenous H-2Kb, in addition to upregulation of antigen presentation genes ({beta}2-microglobulin, Tap1, and Tapbp). In two independent immunocompetent PDAC models, intratumoral and systemic delivery of rVMG-H-2Kk delayed tumor progression and prolonged survival. Multiplex immunohistochemistry and immunophenotyping revealed substantial TME remodeling, marked by increased effector T-cell infiltration, regulatory T-cell depletion, and reduced fibrosis. Spatial transcriptomics further showed compartment-specific immune activation and epithelial metabolic reprogramming, corroborating with enhanced tumor immunogenicity. Despite these effects, rVMG-H-2Kk also induced compensatory immunosuppressive pathways, including upregulation of antiviral response genes and immune checkpoint receptors such as PDL-2. Importantly, combination therapy with rVMG-H-2Kk and murine checkpoint blockade (anti-PD-1 and anti-CTLA-4) drastically improved survival than checkpoint blockade alone. Strikingly, surviving mice resisted tumor rechallenge, indicating the establishment of durable antitumor memory. Collectively, these findings establish rVMG-H-2Kk as a novel immunotherapeutic platform capable of converting immune-cold tumors into immune-hot, sensitizing tumors to immune checkpoint inhibitors, and establishing durable antitumor immunity in PDAC. One Sentence SummaryOncolytic virus-based delivery of an alloantigen improves antitumor immunity and synergizes with immune checkpoint inhibitors in pancreatic cancer. Significance statementDelivery of murine alloantigens via an engineered oncolytic vesiculovirus, combined with immune checkpoint blockade, overcomes immunosuppressive barriers and establishes durable antitumor immunity in PDAC.

cancer biology↗

bioRxiv2023

Increased response to immune checkpoint inhibitors with dietary methionine restriction

Dietary methionine restriction, defined as reduction of methionine intake by around 80%, reproducibly decreases tumor growth and synergizes with cancer therapies. Here, we combined dietary methionine restriction with immune checkpoint inhibitors in a model of colon adenocarcinoma. In vitro, we observed that methionine restriction increased the expression of MHC-I and PD-L1 in both mouse and human colorectal cancer cells. We also saw an increase in the gene expression of STING, a known inducer of type I interferon signaling. Inhibition of the cGAS-STING pathway, pharmacologically or with siRNA, blunted the increase in MHC-I and PD-L1 surface and gene expression following methionine restriction. PD-L1 expression was also This indicated that the cGAS-STING pathway in particular, and interferon in general, is playing a role in the immune response to methionine restriction. We then combined dietary methionine restriction with immune checkpoint inhibitors targeted against CTLA-4 and PD-1 in a MC38 colorectal cancer tumor model in C57BL/6 mice. The combination treatment was five times more effective at reducing tumor size than immune checkpoint inhibition alone in males. We noted sex differences in the response to dietary methionine restriction for the MC38 tumor model in C57BL/6 mice. Finally, we observed an increase in PD-L1 protein expression in MC38 tumors from animals who were fed a methionine-restricted diet. Furthermore, the distribution of CD8 staining changed from mostly peripheric in the controls, to intratumoral in the methionine-restricted tumors. MHC-I, which has a high basal expression in MC38 cells, was highly expressed in all tumors. These results indicate that methionine restriction improves the response to immune checkpoint inhibitors in mice, and that this improvement is associated with the cGAS-STING pathway and interferon signaling.

cancer biology↗

bioRxiv2023

Characterization of methionine dependence in melanoma cells

Dietary methionine restriction is associated with a reduction in tumor growth in preclinical studies and an increase in lifespan in animal models. The mechanism by which methionine restriction inhibits tumor growth while sparing normal cells is incompletely understood. We do know that normal cells can utilize methionine or homocysteine interchangeably (methionine independence) while most cancer cells are strictly dependent on methionine availability. Here, we compared a typical methionine dependent and a rare methionine independent melanoma cell line. We show that replacing methionine, a methyl donor, with its precursor homocysteine generally induced hypomethylation in gene promoters. This decrease was similar in methionine dependent and methionine independent cells. There was only a low level of pathway enrichment, suggesting that the hypomethylation is generalized rather than gene specific. Whole proteome and transcriptome were also analyzed. This analysis revealed that contrarily to the effect on methylation, the replacement of methionine with homocysteine had a much greater effect on the transcriptome and proteome of methionine dependent cells than methionine independent cells. Interestingly, methionine adenosyltransferase 2A (MAT2A), responsible for the synthesis of s-adenosylmethionine from methionine, was equally strongly upregulated in both cell lines. This suggests that the absence of methionine is equally detected but triggers different outcomes in methionine dependent versus independent cells. Our analysis reveals the importance of cell cycle control, DNA damage repair, translation, nutrient sensing, oxidative stress and immune functions in the cellular response to methionine stress in melanoma.

molecular biology↗

bioRxiv2020

Methionine stress induces ferroptosis in methionine dependent cancer cells

Dietary methionine restriction is associated with a reduction in tumor growth in preclinical studies and an increase in lifespan in animal models. The mechanism by which methionine restriction inhibits tumor growth while sparing normal cells is incompletely understood, except for the observation that normal cells can utilize methionine or homocysteine interchangeably (methionine independence) while most cancer cells are strictly dependent on methionine availability. Here, we compared a typical methionine dependent and a rare methionine independent melanoma cell line. We found that replacing methionine with homocysteine generally induced hypomethylation in gene promoters. We isolated nuclear proteins and submitted it for tandem mass tag (TMT) proteomics. This analysis revealed that several proteins involved in the mitochondrial integrated stress response (ISR) were upregulated in response to the replacement of methionine to homocysteine in both cell lines, but to a much greater degree in the methionine dependent cell line. Consistent with the ISR signature, a proteomic analysis of a subcellular fraction enriched for mitochondrial content revealed a strong enrichment for proteins involved in oxidative phosphorylation. Analysis of cellular bioenergetics confirmed that homocysteine induces a decrease in ATP production from oxidative phosphorylation and glycolysis, but to a similar extent in methionine dependent and methionine independent cells. The mitochondrial integrated stress response shared a signature with ferroptosis. Methionine dependent cells displayed a strong ferroptotic signature, which was decreased by half in methionine independent cells. Consistent with ferroptosis, lipid peroxidation was significantly increased in methionine independent cells grown in homocysteine, and viability could be rescued partially but significantly with the inhibitor ferrostatin. Therefore, we propose that methionine stress induces ferroptotic cell death in methionine dependent cancer cells.

cancer biology↗