bims-tucedo 2022-06-19 papers

bims-tucedo

Biomed News

on Tumor cell dormancy

Issue of 2022–06–19
fiveteen papers selected by
Isabel Puig Borreil, Vall d’Hebron Institute of Oncology

Loss of LPR8 Reduces GPX4 Levels, Resulting in Ferroptosis Sensitivity.
Bacterial Darth Vader: May the force be with you.
cGAS-STING drives the IL-6-dependent survival of chromosomally instable cancers.
NELL-1 regulates the matrisome to promote osteosarcoma progression.
Tracking and characterization of partial and full epithelial-mesenchymal transition cells in a mouse model of metastatic breast cancer.
Developmental pathways are epigenetically reprogrammed during lung cancer brain metastasis.
FOXM1 variant contributes to gefitinib resistance via activating wnt/β-catenin signal pathway in non-small cell lung cancer patients.
Estimation of tumor cell total mRNA expression in 15 cancer types predicts disease progression.
Brain cancer stem cells: resilience through adaptive plasticity and hierarchical heterogeneity.
Therapeutic targeting of macrophage plasticity remodels the tumor-immune microenvironment.
Androgen receptor blockade promotes response to BRAF/MEK-targeted therapy.
Iron-Sensitive Prodrugs That Trigger Active Ferroptosis in Drug-Tolerant Pancreatic Cancer Cells.
The reversible fourth-generation EGFR tyrosine kinase inhibitor OBX02-011 overcomes C797S-mediated resistance in lung cancer.
Microenvironmental landscape of human melanoma brain metastases in response to immune checkpoint inhibition.
METTL3 inhibits anti-tumor immunity by targeting m6A-BHLHE41-CXCL1/CXCR2 axis to promote colorectal cancer.

Cancer Discov. 2022 Jun 17. OF1

Loss of LPR8 Reduces GPX4 Levels, Resulting in Ferroptosis Sensitivity.

LPR8 was identified as a factor contributing to ferroptosis resistance in multiple tumor types.

DOI: https://doi.org/10.1158/2159-8290.CD-RW2022-109
Cancer Cell. 2022 Jun 13. pii: S1535-6108(22)00219-7. [Epub ahead of print]40(6): 600-602

Bacterial Darth Vader: May the force be with you.

Kornelia Polyak.

The microbiome has a major impact on tumor progression, yet the mechanisms are poorly defined. Fu et al. report in Cell that intracellular bacteria in a breast cancer model promote metastasis via reorganizing the cytoskeleton to enhance resistance to mechanical stress, thereby facilitating survival in the circulation during dissemination.

DOI: https://doi.org/10.1016/j.ccell.2022.05.008
Nature. 2022 Jun 15.

cGAS-STING drives the IL-6-dependent survival of chromosomally instable cancers.

Christy Hong, Michael Schubert, Andréa E Tijhuis, Marta Requesens, Maurits Roorda, Anouk van den Brink, Lorena Andrade Ruiz, Petra L Bakker, Tineke van der Sluis, Wietske Pieters, Mengting Chen, René Wardenaar, Bert van der Vegt, Diana C J Spierings, Marco de Bruyn, Marcel A T M van Vugt, Floris Foijer.

Chromosomal instability (CIN) drives cancer cell evolution, metastasis and therapy resistance, and is associated with poor prognosis1. CIN leads to micronuclei that release DNA into the cytoplasm after rupture, which triggers activation of inflammatory signalling mediated by cGAS and STING2,3. These two proteins are considered to be tumour suppressors as they promote apoptosis and immunosurveillance. However, cGAS and STING are rarely inactivated in cancer4, and, although they have been implicated in metastasis5, it is not known why loss-of-function mutations do not arise in primary tumours4. Here we show that inactivation of cGAS-STING signalling selectively impairs the survival of triple-negative breast cancer cells that display CIN. CIN triggers IL-6-STAT3-mediated signalling, which depends on the cGAS-STING pathway and the non-canonical NF-κB pathway. Blockade of IL-6 signalling by tocilizumab, a clinically used drug that targets the IL-6 receptor (IL-6R), selectively impairs the growth of cultured triple-negative breast cancer cells that exhibit CIN. Moreover, outgrowth of chromosomally instable tumours is significantly delayed compared with tumours that do not display CIN. Notably, this targetable vulnerability is conserved across cancer types that express high levels of IL-6 and/or IL-6R in vitro and in vivo. Together, our work demonstrates pro-tumorigenic traits of cGAS-STING signalling and explains why the cGAS-STING pathway is rarely inactivated in primary tumours. Repurposing tocilizumab could be a strategy to treat cancers with CIN that overexpress IL-6R.

DOI: https://doi.org/10.1038/s41586-022-04847-2
Cancer Res. 2022 Jun 14. pii: canres.0732.2022-3-1 13:01:34.140. [Epub ahead of print]

NELL-1 regulates the matrisome to promote osteosarcoma progression.

Qizhi Qin, Mario Gomez-Salazar, Robert J Tower, Leslie Chang, Carol D Morris, Edward F McCarthy, Kang Ting, Xinli Zhang, Aaron W James.

Sarcomas produce an abnormal extracellular matrix (ECM), which in turn provides instructive cues for cell growth and invasion. Neural EGF like-like molecule 1 (NELL1) is a secreted glycoprotein characterized by its non-neoplastic osteoinductive effects, yet it is highly expressed in skeletal sarcomas. Here, we show that genetic deletion of NELL1 markedly reduces invasive behavior across human osteosarcoma (OS) cell lines. NELL1 deletion resulted in reduced OS disease progression, inhibiting metastasis and improving survival in a xenograft mouse model. These observations were recapitulated with Nell1 conditional knockout in mouse models of p53/Rb-driven sarcomagenesis, which reduced tumor frequency and extended tumor-free survival. Transcriptomic and phosphoproteomic analyses demonstrated that NELL1 loss skews the expression of matricellular proteins associated with reduced FAK signaling. Culturing NELL1 knockout sarcoma cells on wild-type OS-enriched matricellular proteins reversed the phenotypic and signaling changes induced by NELL1 deficiency. In sarcoma patients, high expression of NELL1 correlated with decreased overall survival. These findings in mouse and human models suggest that NELL1 expression alters the sarcoma ECM, thereby modulating cellular invasive potential and prognosis. Disruption of NELL1 signaling may represent a novel therapeutic approach to short-circuit sarcoma disease progression.

DOI: https://doi.org/10.1158/0008-5472.CAN-22-0732
STAR Protoc. 2022 Jun 17. 3(2): 101438

Tracking and characterization of partial and full epithelial-mesenchymal transition cells in a mouse model of metastatic breast cancer.

Fabiana Lüönd, Natascha Santacroce, Christian Beisel, Laurent Guérard, Thomas R Bürglin, Gerhard Christofori, Nami Sugiyama.

  The various stages of epithelial-mesenchymal transition (EMT) generate phenotypically heterogeneous populations of cells. Here, we detail a dual recombinase lineage tracing system using a transgenic mouse model of metastatic breast cancer to trace and characterize breast cancer cells at different EMT stages. We describe analytical steps to label cancer cells at an early partial or a late full EMT state, followed by tracking their behavior in tumor slice cultures. We then characterize their transcriptome by five-cell RNA sequencing. For complete details on the use and execution of this protocol, please refer to Luond et al. (2021).

Keywords:  Cancer; Cell Biology; Cell Differentiation; Flow Cytometry/Mass Cytometry; Microscopy; Molecular Biology; RNAseq; Single Cell

DOI:  https://doi.org/10.1016/j.xpro.2022.101438
Cancer Res. 2022 Jun 15. pii: canres.4160.2021-12-4 00:44:15.000. [Epub ahead of print]

Developmental pathways are epigenetically reprogrammed during lung cancer brain metastasis.

Jennifer A Karlow, Siddhartha Devarakonda, Xiaoyun Xing, Hyo Sik Jang, Ramaswamy Govindan, Mark A Watson, Ting Wang.

Non-small cell lung cancer (NSCLC) is one of the most commonly diagnosed and deadliest cancers worldwide, with roughly half of all patients initially presenting with both primary and metastatic disease. While the major events in the metastatic cascade have been identified, a mechanistic understanding of how NSCLC routinely and successfully colonizes the brain is largely unknown. Recent studies have begun demonstrating the role of epigenetic misregulation during tumorigenesis and metastasis, including widespread changes in DNA methylation and histone modifications. To better understand the role of altered DNA methylation in NSCLC metastasis to the brain, we measured DNA methylation during disease progression for 12 patients, globally profiling the methylation status of normal lung, primary lung tumor, and brain metastasis samples. The variation in methylation was similar during metastatic spread and primary tumorigenesis but less coordinated across genomic features during metastasis. The greatest recurrent changes during metastatic progression were methylation gains in DNA methylation valleys (DMVs) harboring the constitutive heterochromatin mark H3K9me3 as well as bivalent marks H3K27me3 and H3K4me1. In a lymph node-derived cancer cell line, EZH2 binding within DMVs was lost, accompanied by an increase in DNA methylation, exemplifying epigenetic switching. The vast majority of the differentially methylated region-associated DMVs harbored developmental genes, suggesting that altered epigenetic regulation of developmentally important genes may confer a selective advantage during metastatic progression. The characterization of epigenetic changes during NSCLC brain metastasis identified recurrent methylation patterns that may be prognostic biomarkers and contributors to disease progression.

DOI: https://doi.org/10.1158/0008-5472.CAN-21-4160
Clin Cancer Res. 2022 Jun 13. pii: clincanres.0791.2022-3-11 20:24:57.550. [Epub ahead of print]

FOXM1 variant contributes to gefitinib resistance via activating wnt/β-catenin signal pathway in non-small cell lung cancer patients.

Shaoxing Guan, Xi Chen, Youhao Chen, Wen Xie, Heng Liang, Xia Zhu, Yunpeng Yang, Wenfeng Fang, Yan Huang, Hongyun Zhao, Wei Zhuang, Shu Liu, Min Huang, Xueding Wang, Li Zhang.

PURPOSE: Although gefitinib prolonged the progression-free survival (PFS) of non-small cell lung cancer (NSCLC) patients, unpredictable resistance limited its clinical efficacy. Novel predictive biomarkers with explicit mechanisms are urgently needed.
EXPERIMENTAL DESIGN: A total of 282 NSCLC patients with gefitinib treatment were randomly assigned in a 7:3 ratio to exploratory (n=192) and validation (n=90) cohorts. The candidate polymorphisms were selected with Haploview4.2 in Hapmap and genotyped by a MassARRAY system, and the feature variables were identified through Randomforest Survival analysis. Tans-well and clonogenic assays, base editing and cell-derived tumor xenograft model were performed to uncover the underlying mechanism.
RESULTS: We found that the germline missense polymorphism rs3742076 (A>G, S628P), located in transactivation domain of FOXM1, was associated with PFS in exploratory (median PFS: GG vs. GA&AA, 9.20 vs. 13.37 months, P=0.00039, HR=2.399) and validation (median PFS: GG vs. GA&AA, 8.13 vs. 13.80 months, P=0.048, HR=2.628) cohorts. We elucidated that rs3742076_G conferred resistance to gefitinib by increasing protein stability of FOXM1 and facilitating an aggressive phenotype in vitro and in vivo through activating wnt/β-catenin signaling pathway. Meanwhile, FOXM1 level was highly associated with prognosis in EGFR-mutant NSCLC patients. Mechanistically, FOXM1 rs3742076_G upregulated wnt/β-catenin activity by directly binding to β-catenin in cytoplasm and promoting transcription of β-catenin in nucleus. Remarkably, inhibition of β-catenin markedly reversed rs3742076_G-induced gefitinib resistance and aggressive phenotypes.
CONCLUSION: These findings characterized rs3742076_G as a gain-of-function polymorphism in mediating gefitinib resistance and tumor aggressiveness, and highlighted the variant as a predictive biomarker in guiding gefitinib treatment.

DOI: https://doi.org/10.1158/1078-0432.CCR-22-0791
Nat Biotechnol. 2022 Jun 13.

Estimation of tumor cell total mRNA expression in 15 cancer types predicts disease progression.

Shaolong Cao, Jennifer R Wang, Shuangxi Ji, Peng Yang, Yaoyi Dai, Shuai Guo, Matthew D Montierth, John Paul Shen, Xiao Zhao, Jingxiao Chen, Jaewon James Lee, Paola A Guerrero, Nicholas Spetsieris, Nikolai Engedal, Sinja Taavitsainen, Kaixian Yu, Julie Livingstone, Vinayak Bhandari, Shawna M Hubert, Najat C Daw, P Andrew Futreal, Eleni Efstathiou, Bora Lim, Andrea Viale, Jianjun Zhang, Matti Nykter, Bogdan A Czerniak, Powel H Brown, Charles Swanton, Pavlos Msaouel, Anirban Maitra, Scott Kopetz, Peter Campbell, Terence P Speed, Paul C Boutros, Hongtu Zhu, Alfonso Urbanucci, Jonas Demeulemeester, Peter Van Loo, Wenyi Wang.

Single-cell RNA sequencing studies have suggested that total mRNA content correlates with tumor phenotypes. Technical and analytical challenges, however, have so far impeded at-scale pan-cancer examination of total mRNA content. Here we present a method to quantify tumor-specific total mRNA expression (TmS) from bulk sequencing data, taking into account tumor transcript proportion, purity and ploidy, which are estimated through transcriptomic/genomic deconvolution. We estimate and validate TmS in 6,590 patient tumors across 15 cancer types, identifying significant inter-tumor variability. Across cancers, high TmS is associated with increased risk of disease progression and death. TmS is influenced by cancer-specific patterns of gene alteration and intra-tumor genetic heterogeneity as well as by pan-cancer trends in metabolic dysregulation. Taken together, our results indicate that measuring cell-type-specific total mRNA expression in tumor cells predicts tumor phenotypes and clinical outcomes.

DOI: https://doi.org/10.1038/s41587-022-01342-x
Nat Rev Cancer. 2022 Jun 16.

Brain cancer stem cells: resilience through adaptive plasticity and hierarchical heterogeneity.

Ryan C Gimple, Kailin Yang, Matthew E Halbert, Sameer Agnihotri, Jeremy N Rich.

Malignant brain tumours are complex ecosystems containing neoplastic and stromal components that generate adaptive and evolutionarily driven aberrant tissues in the central nervous system. Brain cancers are cultivated by a dynamic population of stem-like cells that enforce intratumoural heterogeneity and respond to intrinsic microenvironment or therapeutically guided insults through proliferation, plasticity and restructuring of neoplastic and stromal components. Far from a rigid hierarchy, heterogeneous neoplastic populations transition between cellular states with differential self-renewal capacities, endowing them with powerful resilience. Here we review the biological machinery used by brain tumour stem cells to commandeer tissues in the intracranial space, evade immune responses and resist chemoradiotherapy. Through recent advances in single-cell sequencing, improved models to investigate the role of the tumour microenvironment and a deeper understanding of the fundamental role of the immune system in cancer biology, we are now better equipped to explore mechanisms by which these processes can be exploited for therapeutic benefit.

DOI: https://doi.org/10.1038/s41568-022-00486-x
Cancer Res. 2022 Jun 16. pii: canres.CAN-21-3506-A.2021. [Epub ahead of print]

Therapeutic targeting of macrophage plasticity remodels the tumor-immune microenvironment.

Hee-Jin Jang, Hyun-Sung Lee, Wendong Yu, Maheshwari Ramineni, Cynthia Y Truong, Daniela Ramos, Taylor Splawn, Jong Min Choi, Sung Yun Jung, Ju-Seog Lee, Daniel Y Wang, Joel M Sederstrom, Massimo Pietropaolo, Farrah Kheradmand, Christopher I Amos, Thomas M Wheeler, R Taylor Ripley, Bryan M Burt.

Although the majority of patients with advanced lung adenocarcinoma (LUAD) are eligible to receive immune checkpoint blockade, approximately 80% of these tumors are resistant to this therapeutic approach. Insights at the single-cell level into mechanisms that drive LUAD tumorigenesis and the relationship of LUAD histologic heterogeneity to response to immune checkpoint blockade could help identify biomarkers and potential combinational approaches to improve immunotherapy efficacy. Here we used a genetically engineered mouse model that replicates the development of human LUAD through a spectrum of pre-invasive to invasive adenocarcinoma histologic subtypes. A systems onco-immunology approach of integrating the analytical power and unique, complementary capabilities of time-of-flight mass cytometry (CyTOF) and imaging mass cytometry was leveraged to identify cellular and spatial immune contextures in LUAD. Comprehensive investigation of mouse and human LUAD using these single-cell proteomics platforms showed that LUAD progression is associated with spatiotemporal evolution of tumor-associated macrophages in the tumor-immune microenvironment, which governs tumor response to immunotherapy. PD-1 was expressed in a highly plastic tumor-promoting subtype of tumor-associated macrophages that develops during tumor progression from pre-invasive to invasive adenocarcinoma, controls the lymphocyte-depleted niche of invasive tumors, and protects tumor cells in the solid histologic components of the tumor. Longitudinal, multi-dimensional single-cell analyses of LUAD tumorigenesis revealed dynamic alteration of immunoregulatory PD-1-expressing tumor-associated macrophages that can be targeted to overcome resistance to checkpoint immunotherapy.

DOI: https://doi.org/10.1158/0008-5472.CAN-21-3506
Nature. 2022 Jun 15.

Androgen receptor blockade promotes response to BRAF/MEK-targeted therapy.

Christopher P Vellano, Michael G White, Miles C Andrews, Manoj Chelvanambi, Russell G Witt, Joseph R Daniele, Mark Titus, Jennifer L McQuade, Fabio Conforti, Elizabeth M Burton, Matthew J Lastrapes, Gabriel Ologun, Alexandria P Cogdill, Golnaz Morad, Peter Prieto, Alexander J Lazar, Yanshuo Chu, Guangchun Han, M A Wadud Khan, Beth Helmink, Michael A Davies, Rodabe N Amaria, Jeffrey J Kovacs, Scott E Woodman, Sapna Patel, Patrick Hwu, Michael Peoples, Jeffrey E Lee, Zachary A Cooper, Haifeng Zhu, Guang Gao, Hiya Banerjee, Mike Lau, Jeffrey E Gershenwald, Anthony Lucci, Emily Z Keung, Merrick I Ross, Laura Pala, Eleonora Pagan, Rossana Lazcano Segura, Qian Liu, Mikayla S Borthwick, Eric Lau, Melinda S Yates, Shannon N Westin, Khalida Wani, Michael T Tetzlaff, Lauren E Haydu, Mikhila Mahendra, XiaoYan Ma, Christopher Logothetis, Zachary Kulstad, Sarah Johnson, Courtney W Hudgens, Ningping Feng, Lorenzo Federico, Georgina V Long, P Andrew Futreal, Swathi Arur, Hussein A Tawbi, Amy E Moran, Linghua Wang, Timothy P Heffernan, Joseph R Marszalek, Jennifer A Wargo.

Treatment with therapy targeting BRAF and MEK (BRAF/MEK) has revolutionized care in melanoma and other cancers; however, therapeutic resistance is common and innovative treatment strategies are needed1,2. Here we studied a group of patients with melanoma who were treated with neoadjuvant BRAF/MEK-targeted therapy ( NCT02231775 , n = 51) and observed significantly higher rates of major pathological response (MPR; ≤10% viable tumour at resection) and improved recurrence-free survival (RFS) in female versus male patients (MPR, 66% versus 14%, P = 0.001; RFS, 64% versus 32% at 2 years, P = 0.021). The findings were validated in several additional cohorts2-4 of patients with unresectable metastatic melanoma who were treated with BRAF- and/or MEK-targeted therapy (n = 664 patients in total), demonstrating improved progression-free survival and overall survival in female versus male patients in several of these studies. Studies in preclinical models demonstrated significantly impaired anti-tumour activity in male versus female mice after BRAF/MEK-targeted therapy (P = 0.006), with significantly higher expression of the androgen receptor in tumours of male and female BRAF/MEK-treated mice versus the control (P = 0.0006 and P = 0.0025). Pharmacological inhibition of androgen receptor signalling improved responses to BRAF/MEK-targeted therapy in male and female mice (P = 0.018 and P = 0.003), whereas induction of androgen receptor signalling (through testosterone administration) was associated with a significantly impaired response to BRAF/MEK-targeted therapy in male and female patients (P = 0.021 and P < 0.0001). Together, these results have important implications for therapy.

DOI: https://doi.org/10.1038/s41586-022-04833-8
J Am Chem Soc. 2022 Jun 13.

Iron-Sensitive Prodrugs That Trigger Active Ferroptosis in Drug-Tolerant Pancreatic Cancer Cells.

Michał Antoszczak, Sebastian Müller, Tatiana Cañeque, Ludovic Colombeau, Nelson Dusetti, Patricia Santofimia-Castaño, Christine Gaillet, Alain Puisieux, Juan Lucio Iovanna, Raphaël Rodriguez.

Persister cancer cells represent rare populations of cells resistant to therapy. Cancer cells can exploit epithelial-mesenchymal plasticity to adopt a drug-tolerant state that does not depend on genetic alterations. Small molecules that can interfere with cell plasticity or kill cells in a cell state-dependent manner are highly sought after. Salinomycin has been shown to kill cancer cells in the mesenchymal state by sequestering iron in lysosomes, taking advantage of the iron addiction of this cell state. Here, we report the chemo- and stereoselective synthesis of a series of structurally complex small molecule chimeras of salinomycin derivatives and the iron-reactive dihydroartemisinin. We show that these chimeras accumulate in lysosomes and can react with iron to release bioactive species, thereby inducing ferroptosis in drug-tolerant pancreatic cancer cells and biopsy-derived organoids of pancreatic ductal adenocarcinoma. This work paves the way toward the development of new cancer medicines acting through active ferroptosis.

DOI: https://doi.org/10.1021/jacs.2c03973
Cancer Res. 2022 Jun 14. pii: canres.0394.2022-2-3 21:03:12.200. [Epub ahead of print]

The reversible fourth-generation EGFR tyrosine kinase inhibitor OBX02-011 overcomes C797S-mediated resistance in lung cancer.

Yun Jung Choi, Da-Som Kim, Young Hoon Sung, Dong Ha Kim, Kyungtaek Im, Hyeonjeong Lee, Chae Won Lee, Jeongin Cho, Joongkee Min, Dong-Cheol Woo, Sung-Eun Kim, Sunho Lee, Yun Jeong Kong, Hyung Chul Ryu, Jae-Sun Kim, Rajesh Rengasamy, Wonjun Ji, Chang-Min Choi, Jae Cheol Lee, Jin Kyung Rho.

Osimertinib is an irreversible third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that was initially developed to overcome the EGFR T790M mutation and is used as a standard therapy in patients with advanced non-small cell lung cancer (NSCLC) with EGFR-activating mutations. Despite the remarkable initial efficacy, osimertinib, like other EGFR-TKIs, is limited by the emergence of acquired resistance. As the EGFR mutation C797S has been identified as a key driver of acquired resistance to osimertinib, development of a drug that targets this clinically relevant mutation could help improve patient outcomes. Here, we report the discovery and preclinical efficacy of OBX02-011, a reversible fourth-generation EGFR TKI that overcomes the EGFR C797S mutation. Compared to approved EGFR TKIs, OBX02-011 showed potent anticancer effects and inhibited EGFR-related signaling in various models, including those harboring the EGFR C797S mutation. Additionally, in transgenic mouse models (EGFRL858R/T790M/C797S), OBX02-011 treatment effectively inhibited tumor growth and EGFR activity, leading to enhanced survival. Collectively, these results suggest that OBX02-011 may be a promising new EGFR TKI to overcome C797S-mediated resistance in NSCLC.

DOI: https://doi.org/10.1158/0008-5472.CAN-22-0394
Cancer Immunol Res. 2022 Jun 15. pii: canimm.CIR-21-0870-E.2021. [Epub ahead of print]

Microenvironmental landscape of human melanoma brain metastases in response to immune checkpoint inhibition.

Christopher Alvarez-Breckenridge, Samuel C Markson, Jackson H Stocking, Naema Nayyar, Matt Lastrapes, Matthew R Strickland, Albert E Kim, Magali de Sauvage, Ashish Dahal, Juliana M Larson, Joana L Mora, Andrew W Navia, Robert H Klein, Benjamin M Kuter, Corey M Gill, Mia Bertalan, Brian Shaw, Alexander Kaplan, Megha Subramanian, Aarushi Jain, Swaminathan Kumar, Husain Danish, Michael White, Osmaan Shahid, Kristen E Pauken, Brian C Miller, Dennie T Frederick, Christine Hebert, McKenzie Shaw, Maria Martinez-Lage, Matthew Frosch, Nancy Wang, Elizabeth Gerstner, Brian V Nahed, William T Curry, Bob Carter, Daniel P Cahill, Genevieve Marie Boland, Benjamin Izar, Michael A Davies, Arlene H Sharpe, Mario L Suva, Ryan J Sullivan, Priscilla K Brastianos, Scott L Carter.

Melanoma-derived brain metastases (MBM) represent an unmet clinical need because central nervous system (CNS) progression is frequently an end-stage of the disease. Immune checkpoint inhibitors (ICI) provide a clinical opportunity against MBM; however, the MBM tumor microenvironment (TME) has not been fully elucidated in the context of ICI. To dissect unique elements of the MBM TME and correlates of MBM response to ICI, we collected 32 fresh MBM and performed single-cell RNA sequencing of the MBM TME and T-cell receptor clonotyping on T cells from MBM and matched blood and extracranial lesions. We observed myeloid phenotypic heterogeneity in the MBM TME, most notably multiple distinct neutrophil states, including an IL8-expressing population that correlated with malignant cell epithelial-to-mesenchymal transition. Additionally, we observed significant relationships between intracranial T-cell phenotypes and the distribution of T-cell clonotypes intracranially and peripherally. We found that the phenotype, clonotype, and overall number of MBM-infiltrating T cells were associated with response to ICI, suggesting that ICI-responsive MBMs interact with peripheral blood in a manner similar to extracranial lesions. These data identify unique features of the MBM TME that may represent potential targets to improve clinical outcomes for patients with MBM.

DOI: https://doi.org/10.1158/2326-6066.CIR-21-0870
Gastroenterology. 2022 Jun 11. pii: S0016-5085(22)00629-1. [Epub ahead of print]

METTL3 inhibits anti-tumor immunity by targeting m6A-BHLHE41-CXCL1/CXCR2 axis to promote colorectal cancer.

Huarong Chen, Yasi Pan, Qiming Zhou, Cong Liang, Chi-Chun Wong, Yunfei Zhou, Dan Huang, Weixin Liu, Jianning Zhai, Hongyan Gou, Hao Su, Xiaoting Zhang, Hongzhi Xu, Yifei Wang, Wei Kang, William Ka Kei Wu, Jun Yu.

   BACKGROUND & AIMS: N6-Methyladenosine (m6A) is the most prevalent RNA modification and recognized as an important epitranscriptomic mechanism in colorectal cancer (CRC). We aim to exploit whether and how tumor-intrinsic m6A modification drove by methyltransferase like 3 (METTL3) can dictate the immune landscape of CRC.
METHODS: Mettl3 knockout mice, CD34+ humanized mice and different syngeneic mice models were employed. Immune cells composition and cytokines level were analyzed by flow cytometry and Cytokine 23-Plex immunoassay, respectively. M6A-seq and RNA-seq were performed to identify downstream targets and pathways of METTL3. Human CRC specimens (n=176) were used to evaluate correlation between METTL3 expression and myeloid-derived suppressor cells (MDSCs) infiltration.
RESULTS: We demonstrated that silencing of METTL3 in CRC cells reduced MDSCs accumulation to sustain activation and proliferation of CD4+ and CD8+ T cell, and eventually suppressed CRC in ApcMin/+Mettl3+/- mice, CD34+ humanized mice and syngeneic mice models. Mechanistically, METTL3 activated m6A-BHLHE41-CXCL1 axis by analysis of m6A-seq, RNA-seq and cytokines arrays. METTL3 promoted BHLHE41 expression in m6A-dependent manner, which subsequently induced CXCL1 transcription to enhance MDSC migration in vitro. However, the effect was negligible upon BHLHE41 depletion, CXCL1 protein or CXCR2 inhibitor SB265610 administration, inferring that METTL3 promotes MDSC migration via BHLHE41-CXCL1/CXCR2. Consistently, depletion of MDSCs by anti-Gr1 antibody or SB265610 blocked tumor-promoting effect of METTL3 in vivo. Importantly, targeting METTL3 by METTL3-sgRNA or specific inhibitor potentiated the effect of anti-PD1 treatment.
CONCLUSIONS: Our study identifies METTL3 as a potential therapeutic target for CRC immunotherapy whose inhibition reverses immune suppression through m6A-BHLHE41-CXCL1 axis. METTL3 inhibition plus anti-PD-1 treatment show promising antitumor efficacy against CRC.

Keywords:  Colorectal cancer; MDSC; METTL3; N(6)-Methyladenosine; immunotherapy

DOI:  https://doi.org/10.1053/j.gastro.2022.06.024