bims-stacyt 2025-03-02 papers

Cell Death Dis. 2025 Feb 27. 16(1): 142

Hypoxia-induced ATF3 escalates breast cancer invasion by increasing collagen deposition via P4HA1.

Shruti Ganesh Dhamdhere, Anamika Bansal, Pranjal Singh, Parik Kakani, Shruti Agrawal, Atul Samaiya, Sanjeev Shukla.

Activating transcription factors (ATFs), members of the adaptive-response gene family, participate in cellular processes to aid adaptations in response to extra and/or intracellular changes. In this study, we observed that one of the ATFs, Activating transcription factor 3 (ATF3), is upregulated under hypoxia via alterations in the epigenetic landscape of its promoter, followed by transcriptional upregulation. Under hypoxic conditions, Hypoxia-inducible factor 1-alpha (HIF1ɑ) alleviates methylation at the ATF3 promoter by recruiting TET1 and induces ATF3 transcription. In addition, our RNA-seq analysis showed that ATF3 globally affects transcription under hypoxia and controls the processes of EMT and cancer invasion by stimulating the transcription of Prolyl 4-Hydroxylase Subunit Alpha 1 (P4HA1), an enzyme which enhances invasion-conducive extracellular matrix (ECM) under hypoxic conditions. Prolyl hydroxylases play a critical role in the hydroxylation and deposition of collagen in the extracellular matrix (ECM) during the evolution of cancer, which is necessary for metastasis. Importantly, P4HA1 undergoes alternative splicing under hypoxia, where the inclusion of exon 9a is increased. Interestingly, involvement of ATF3 in P4HA1 splicing was also evident, as binding of ATF3 at intron 9a led to demethylation of this DNA region via recruitment of TET1. Furthermore, we also show that the demethylated DNA region of intron 9a then becomes accessible to CCCTC-binding factor (CTCF). Thus, a cascade of demethylation via ATF3 recruited TET1, followed by increased RNA Pol II pause at intron 9a via CTCF, leads to inclusion of exon 9a. The P4HA1 9a isoform leads to enhanced invasion under hypoxic conditions by increasing deposition of collagen in the ECM. These results reveal a novel hypoxia-induced HIF1ɑ-ATF3-P4HA1 axis which can potentially be exploited as a therapeutic target to impede EMT and ultimately breast cancer invasion. Hypoxia induced ATF3 regulates P4HA1 expression and alternative splicing to promote breast cancer invasion.

DOI: https://doi.org/10.1038/s41419-025-07461-y

J Immunother Cancer. 2025 Feb 25. pii: e010153. [Epub ahead of print]13(2):

Effector T cells under hypoxia have an altered transcriptome similar to tumor-stressed T cells found in non-responsive melanoma patients.

Mate Z Nagy, Lourdes B Plaza-Rojas, Justin C Boucher, Elena Kostenko, Anna L Austin, Ahmad A Tarhini, Zhihua Chen, Dongliang Du, Awino Maureiq E Ojwang', Joshua Davis, Alyssa Obermayer, Katarzyna A Rejniak, Timothy I Shaw, Jose A Guevara-Patino.

BACKGROUND: In the tumor microenvironment (TME), hypoxia stands as a significant factor that modulates immune responses, especially those driven by T cells. As T cell-based therapies often fail to work in solid tumors, this study aims to investigate the effects of hypoxia on T cell topo-distribution in the TME, gene expression association with T cell states, and clinical responses in melanoma.
METHODS: To generate detailed information on tumor oxygenation and T cell accessibility, we used mathematical modeling of human melanoma tissue microarrays that incorporate oxygen supply from vessels, intratumoral diffusion, and cellular uptake. We created tumor maps and derived plots showing the fraction of CD4 and CD8 T cells against the distance to the nearest vessel and oxygen pressure. To assess their function and transcriptional changes caused by hypoxia, effector T cells were generated and cultured under hypoxia (0.5% oxygen) or normoxia (21% oxygen). The T cell hypoxia-transcriptional signature was compared against datasets from msigDB, iATLAS (clinical trials of melanoma patients treated with immune checkpoint inhibitors (ICIs)), ORIEN AVATAR (real-world melanoma patients treated with ICIs), and a single-cell atlas of tumor-infiltrating lymphocytes.
RESULTS: We made three specific observations: (1) in melanoma T cells preferentially accumulated in oxygenated areas close to blood vessels (50-100 µm from the vasculature in the regions of high oxygen availability) but not in hypoxic areas far from blood vessels. (2) Our analysis confirmed that under hypoxia, T cell functions were significantly reduced compared with normoxic conditions and accompanied by a unique gene signature. Furthermore, this hypoxic gene signature was prevalent in resting and non-activated T cells. Notably and clinically relevant, the hypoxic T cell gene set was found to correlate with reduced overall survival and reduced progression-free survival in melanoma patients, which was more pronounced in non-responder patients undergoing ICI therapy. (3) Finally, compared with a single-cell atlas of tumor-infiltrating T cells, our hypoxia signature aligned with a population of cells at a state termed stress response state (TSTR).
CONCLUSIONS: Our study highlights the critical role of hypoxia in shaping T cell distribution and its correlation with clinical outcomes in melanoma. We revealed a preferential accumulation of T cells in oxygenated areas. Moreover, hypoxic T cells develop a distinct hypoxic gene signature prevalent in resting, non-activated T cells and TSTR that was also associated with poorer outcomes, particularly pronounced among non-responders to ICIs.

Keywords: Gene expression profiling - GEP; Immune Checkpoint Inhibitor; Melanoma; Tumor infiltrating lymphocyte - TIL; Tumor microenvironment - TME

DOI: https://doi.org/10.1136/jitc-2024-010153

Theranostics. 2025 ;15(6): 2338-2359

Histone lactylation-driven B7-H3 expression promotes tumor immune evasion.

Zhibo Ma, Jincui Yang, Wenlong Jia, Le Li, Yixin Li, Junjie Hu, Wei Luo, Ronghui Li, Dawei Ye, Peixiang Lan.

Rationale: Tumor cells possess sophisticated strategies to circumvent immune detection, including the modulation of endogenous immune checkpoints, particularly those within the B7 family. Elucidating the mechanisms that govern the induction of B7 family molecules is crucial for the advancement of immunotherapy. Lysine lactylation (Kla), a newly identified epigenetic modification, is suggested may play a role in reshaping the tumor microenvironment and facilitating immune evasion. Methods: We analyzed the glycolysis pathway's enrichment in patients with immune-evading tumors and assessed the impact of lactate treatment on the antitumor immunity of CD8+ T cells in the tumor microenvironment. We interrupted glycolysis using lactate dehydrogenase A (LDHA) knockdown and sodium oxamate, and evaluated its effects on CD8+ T cell cytotoxicity. Additionally, we investigated the correlation between B7-H3 expression and the glycolysis pathway, and explored the molecular mechanisms underlying lactate-induced B7-H3 expression. Results: Our findings revealed that the glycolysis pathway was highly enriched in immune-evading tumors. Lactate treatment inhibited the antitumor immunity of CD8+ T cells, whereas interruption of glycolysis via LDHA knockdown or treatment with sodium oxamate augmented the cytotoxicity of CD8+ T cells, effectively counteracting tumor immune evasion. B7-H3 expression was found to be closely linked with the glycolysis pathway. Mechanistically, lactate-upregulated H3K18la directly bound to the B7-H3 promoter in conjunction with the transcription factor Creb1 and its co-activator Ep300, leading to increased B7-H3 expression and contributing to tumor progression by compromising the proportion and cytotoxicity of tumor-infiltrating CD8+ T cells. In mouse tumor bearing models, inhibiting glycolysis and B7-H3 expression suppressed tumor cell growth, activated tumor-infiltrating CD8+ T cells, and demonstrated potent anti-tumor efficacy. Furthermore, this approach enhanced the efficacy of anti-PD-1 treatment. Conclusions: This study uncovers a novel mechanism by which lactate modulates the immune microenvironment through the glycolysis pathway and B7-H3 expression, providing new avenues for lactate metabolism-targeted tumor immunotherapy.

Keywords: B7-H3; Glycolysis; H3K18la; Histone lactylation; Immune evasion

DOI: https://doi.org/10.7150/thno.105947