Dietary suppression of MHC class II expression in intestinal epithelial cells enhances intestinal tumorigenesis

Cancer Stem Cell markers: Symphonic masters of chemoresistance and immune evasion

Cancer Stem Cells (CSCs) are highly tumorigenic, chemoresistant, and immune evasive. They emerge as a central driver that gives rise to the bulk of tumoral mass, modifies the tumor microenvironment (TME), and exploits it, leading to poor clinical outcomes for patients with cancer. The existence of CSCs thus accounts for the failure of conventional therapies and immune surveillance. Identifying CSCs in solid tumors remains a significant challenge in modern oncology, with the use of cell surface markers being the primary strategy for studying, isolating, and enriching these cells. In this review, we explore CSC markers, focusing on the underlying signaling pathways that drive CSC self-renewal, which simultaneously makes them intrinsically chemoresistant and immune system evaders. We comprehensively discuss the autonomous and non-autonomous functions of CSCs, with particular emphasis on their interactions with the tumor microenvironment, especially immune cells. This reciprocal network enhances CSCs malignancy while compromising the surrounding niche, ultimately defining therapeutic vulnerabilities associated with each CSC marker. The most common CSCs surface markers addressed in this review-CD44, CD133, ICAM1/CD54, and LGR5-provide insights into the interplay between chemoresistance and immune evasion, two critically important phenomena in disease eradication. This new perspective on the state-of-the-art of CSCs will undoubtedly open new avenues for therapy.

Dietary and metabolic effects on intestinal stem cells in health and disease

Diet and nutritional metabolites exhibit wide-ranging effects on health and disease partly by altering tissue composition and function. With rapidly rising rates of obesity, there is particular interest in how obesogenic diets influence tissue homeostasis and risk of tumorigenesis; epidemiologically, these diets have a positive correlation with various cancers, including colorectal cancer. The gastrointestinal tract is a highly specialized, continuously renewing tissue with a fundamental role in nutrient uptake and is, in turn, influenced by diet composition and host metabolic state. Intestinal stem cells are found at the base of the intestinal crypt and can generate all mature lineages that comprise the intestinal epithelium and are uniquely influenced by host diet, metabolic by-products and energy dynamics. Similarly, tumour growth and metabolism can also be shaped by nutrient availability and host diet. In this Review, we discuss how different diets and metabolic changes influence intestinal stem cells in homeostatic and pathological conditions, as well as tumorigenesis. We also discuss how dietary changes and composition affect the intestinal epithelium and its surrounding microenvironment.

Western diet reduces small intestinal intraepithelial lymphocytes via FXR-Interferon pathway

The prevalence of obesity in the United States has continued to increase over the past several decades. Understanding how diet-induced obesity modulates mucosal immunity is of clinical relevance. We previously showed that consumption of a high fat, high sugar "Western" diet (WD) reduces the density and function of small intestinal Paneth cells, a small intestinal epithelial cell type with innate immune function. We hypothesized that obesity could also result in repressed gut adaptive immunity. Using small intestinal intraepithelial lymphocytes (IEL) as a readout, we found that in non-inflammatory bowel disease (IBD) subjects, high body mass index correlated with reduced IEL density. We recapitulated this in wild type (WT) mice fed with WD. A 4-week WD consumption was able to reduce IEL but not splenic, blood, or bone marrow lymphocytes, and the effect was reversible after another 2 weeks of standard diet (SD) washout. Importantly, WD-associated IEL reduction was not dependent on the presence of gut microbiota, as WD-fed germ-free mice also showed IEL reduction. We further found that WD-mediated Farnesoid X Receptor (FXR) activation in the gut triggered IEL reduction, and this was partially mediated by intestinal phagocytes. Activated FXR signaling stimulated phagocytes to secrete type I IFN, and inhibition of either FXR or type I IFN signaling within the phagocytes prevented WD-mediated IEL loss. Therefore, WD consumption represses both innate and adaptive immunity in the gut. These findings have significant clinical implications in the understanding of how diet modulates mucosal immunity.

Cataloguing the postnatal small intestinal transcriptome during the period of susceptibility to necrotizing enterocolitis

In the first postnatal month, the developing mouse intestine shifts from an immature to a mature intestine that will sustain the organism throughout the lifespan. Here, we surveyed the mouse intestine in C57Bl/6 mice by RNA-Seq to evaluate the changes in gene expression over time from the day of birth through 1 month of age in both the duodenum and ileum. We analyzed gene expression for changes in gene families that correlated with the periods of NEC susceptibility or resistance. We highlight that increased expression of DNA processing genes and vacuolar structure genes, tissue development and morphogenesis genes, and cell migration genes all correlated with NEC susceptibility, while increases in immunity gene sets, intracellular transport genes, ATP production, and intracellular metabolism genes correlated with NEC resistance. Using trends identified in the RNA analyses, we further evaluated expression of cellular markers and epithelial regulators, immune cell markers, and adenosine metabolism components. We confirmed key changes with qRT-PCR and immunofluorescence. In addition, we compared some findings to humans using human intestinal biopsies and organoids. This dataset can serve as a reference for other groups considering the role of single molecules or molecular families in early intestinal and postnatal development.

Revolutionizing immune research with organoid-based co-culture and chip systems

The intertwined interactions various immune cells have with epithelial cells in our body require sophisticated experimental approaches to be studied. Due to the limitations of immortalized cell lines and animal models, there is an increasing demand for human in vitro model systems to investigate the microenvironment of immune cells in normal and in pathological conditions. Organoids, which are self-renewing, 3D cellular structures that are derived from stem cells, have started to provide gap-filling tissue modelling solutions. In this review, we first demonstrate with some of the available examples how organoid-based immune cell co-culture experiments can advance disease modelling of cancer, inflammatory bowel disease, and tissue regeneration. Then, we argue that to achieve both complexity and scale, organ-on-chip models combined with cutting-edge microfluidics-based technologies can provide more precise manipulation and readouts. Finally, we discuss how genome editing techniques and the use of patient-derived organoids and immune cells can improve disease modelling and facilitate precision medicine. To achieve maximum impact and efficiency, these efforts should be supported by novel infrastructures such as organoid biobanks, organoid facilities, as well as drug screening and host-microbe interaction testing platforms. All these together or in combination can allow researchers to shed more detailed, and often patient-specific, light on the crosstalk between immune cells and epithelial cells in health and disease.

Epigenetic control of immunoevasion in cancer stem cells

Cancer stem cells (CSCs) are a poorly differentiated population of malignant cells that (at least in some neoplasms) is responsible for tumor progression, resistance to therapy, and disease relapse. According to a widely accepted model, all stages of cancer progression involve the ability of neoplastic cells to evade recognition or elimination by the host immune system. In line with this notion, CSCs are not only able to cope with environmental and therapy-elicited stress better than their more differentiated counterparts but also appear to better evade tumor-targeting immune responses. We summarize epigenetic modifications of DNA and histones through which CSCs evade immune recognition or elimination, and propose that such alterations constitute promising therapeutic targets to increase the sensitivity of some malignancies to immunotherapy.

Dietary fiber promotes antigen presentation on intestinal epithelial cells and development of small intestinal CD4+CD8αα+ intraepithelial T cells

The impact of dietary fiber on intestinal T cell development is poorly understood. Here we show that a low fiber diet reduces MHC-II antigen presentation by small intestinal epithelial cells (IECs) and consequently impairs development of CD4+CD8αα+ intraepithelial lymphocytes (DP IELs) through changes to the microbiota. Dietary fiber supports colonization by Segmented Filamentous Bacteria (SFB), which induces the secretion of IFNγ by type 1 innate lymphoid cells (ILC1s) that lead to MHC-II upregulation on IECs. IEC MHC-II expression caused either by SFB colonization or exogenous IFNγ administration induced differentiation of DP IELs. Finally, we show that a low fiber diet promotes overgrowth of Bifidobacterium pseudolongum, and that oral administration of B. pseudolongum reduces SFB abundance in the small intestine. Collectively we highlight the importance of dietary fiber in maintaining the balance among microbiota members that allow IEC MHC-II antigen presentation and define a mechanism of microbiota-ILC-IEC interactions participating in the development of intestinal intraepithelial T cells.

Glycosphingolipid synthesis mediates immune evasion in KRAS-driven cancer

Cancer cells frequently alter their lipids to grow and adapt to their environment1-3. Despite the critical functions of lipid metabolism in membrane physiology, signalling and energy production, how specific lipids contribute to tumorigenesis remains incompletely understood. Here, using functional genomics and lipidomic approaches, we identified de novo sphingolipid synthesis as an essential pathway for cancer immune evasion. Synthesis of sphingolipids is surprisingly dispensable for cancer cell proliferation in culture or in immunodeficient mice but required for tumour growth in multiple syngeneic models. Blocking sphingolipid production in cancer cells enhances the anti-proliferative effects of natural killer and CD8+ T cells partly via interferon-γ (IFNγ) signalling. Mechanistically, depletion of glycosphingolipids increases surface levels of IFNγ receptor subunit 1 (IFNGR1), which mediates IFNγ-induced growth arrest and pro-inflammatory signalling. Finally, pharmacological inhibition of glycosphingolipid synthesis synergizes with checkpoint blockade therapy to enhance anti-tumour immune response. Altogether, our work identifies glycosphingolipids as necessary and limiting metabolites for cancer immune evasion.

Multiplex spatial omics reveals changes in immune-epithelial crosstalk during inflammation and dysplasia development in chronic IBD patients

Patients with long-standing inflammatory bowel disease (IBD) face an increased risk of developing colitis-associated cancer (CAC). Although IBD-induced prolonged inflammation seems to be involved in CAC pathogenesis, the specific molecular changes that contribute remain unknown. Here, we applied digital spatial RNA profiling, RNAscope, and imaging mass cytometry to examine paired uninflamed, inflamed, and early dysplastic mucosa of patients with IBD. We observed robust type 3 (IL-17) responses during inflammation, accompanied by elevated JAK-STAT signaling and phosphorylated STAT3 (P-STAT3) levels, with both inflamed and dysplastic mucosa displaying immune cell activation. Higher stromal P-STAT3 was detected in uninflamed and inflamed mucosa of patients who eventually developed dysplasia. CD8a+ T cells did not infiltrate inflamed or dysplastic epithelial regions in these patients, while control patients showed elevated CD8a in inflamed mucosa. Our study reveals distinct inflammatory patterns throughout CAC development, marked by an activated IL-17 pathway, engaged STAT3, and diminished cytotoxic T cell infiltration.

Lymphatic system regulation of anti-cancer immunity and metastasis

Cancer dissemination to lymph nodes (LN) is associated with a worse prognosis, increased incidence of distant metastases and reduced response to therapy. The LN microenvironment puts selective pressure on cancer cells, creating cells that can survive in LN as well as providing survival advantages for distant metastatic spread. Additionally, the presence of cancer cells leads to an immunosuppressive LN microenvironment, favoring the evasion of anti-cancer immune surveillance. However, recent studies have also characterized previously unrecognized roles for tumor-draining lymph nodes (TDLNs) in cancer immunotherapy response, including acting as a reservoir for pre-exhausted CD8+ T cells and stem-like CD8+ T cells. In this review, we will discuss the spread of cancer cells through the lymphatic system, the roles of TDLNs in metastasis and anti-cancer immune responses, and the therapeutic opportunities and challenges in targeting LN metastasis.

Interleukin-17F suppressed colon cancer by enhancing caspase 4 mediated pyroptosis of endothelial cells

The combination of anti-angiogenic treatment and immunotherapy presents a promising strategy against colon cancer. Interleukin-17F (IL-17F) emerges as a critical immune cell cytokine expressed in colonic epithelial cells, demonstrating potential in inhibiting angiogenesis. In order to clarify the roles of IL-17F in the colon cancer microenvironment and elucidate its mechanism, we established a mouse colon carcinoma cell line CT26 overexpressing IL-17F and transplanted it subcutaneously into syngeneic BALB/c mice. We also analyzed induced colon tumor in IL-17F knockout and wild type mice. Our results demonstrated that IL-17F could suppress colon tumor growth in vivo with inhibited angiogenesis and enhanced recruitment of cysteine-cysteine motif chemokine receptor 6 (CCR6) positive immune cells. Additionally, IL-17F suppressed the tube formation, cell growth and migration of endothelial cells EOMA in vitro. Comprehensive bioinformatics analysis of transcriptome profiles between EOMA cells and those treated with three different concentrations of IL-17F identified 109 differentially expressed genes. Notably, a potential new target, Caspase 4, showed increased expressions after IL-17F treatment in endothelial cells. Further molecular validation revealed a novel downstream signaling for IL-17F: IL-17F enhanced Caspase 4/GSDMD signaling of endothelial cells, CT26 cells and CT26 transplanted tumors, while IL-17F knockout colon tumors exhibited decreased Caspase 4/GSDMD signaling. The heightened expression of the GSDMD N-terminus, coupled with increased cellular propidium iodide (PI) uptake and lactate dehydrogenase (LDH) release, revealed that IL-17F promoted pyroptosis of endothelial cells. Altogether, IL-17F could modulate the colon tumor microenvironment with inhibited angiogenesis, underscoring its potential as a therapeutic target for colon cancer.

Chromatin modifier Hmga2 promotes adult hematopoietic stem cell function and blood regeneration in stress conditions

The molecular mechanisms governing the response of hematopoietic stem cells (HSCs) to stress insults remain poorly defined. Here, we investigated effects of conditional knock-out or overexpression of Hmga2 (High mobility group AT-hook 2), a transcriptional activator of stem cell genes in fetal HSCs. While Hmga2 overexpression did not affect adult hematopoiesis under homeostasis, it accelerated HSC expansion in response to injection with 5-fluorouracil (5-FU) or in vitro treatment with TNF-α. In contrast, HSC and megakaryocyte progenitor cell numbers were decreased in Hmga2 KO animals. Transcription of inflammatory genes was repressed in Hmga2-overexpressing mice injected with 5-FU, and Hmga2 bound to distinct regions and chromatin accessibility was decreased in HSCs upon stress. Mechanistically, we found that casein kinase 2 (CK2) phosphorylates the Hmga2 acidic domain, promoting its access and binding to chromatin, transcription of anti-inflammatory target genes, and the expansion of HSCs under stress conditions. Notably, the identified stress-regulated Hmga2 gene signature is activated in hematopoietic stem progenitor cells of human myelodysplastic syndrome patients. In sum, these results reveal a TNF-α/CK2/phospho-Hmga2 axis controlling adult stress hematopoiesis.

Drug-Resistance Biomarkers in Patient-Derived Colorectal Cancer Organoid and Fibroblast Co-Culture System

Colorectal cancer, the third most commonly occurring tumor worldwide, poses challenges owing to its high mortality rate and persistent drug resistance in metastatic cases. We investigated the tumor microenvironment, emphasizing the role of cancer-associated fibroblasts in the progression and chemoresistance of colorectal cancer. We used an indirect co-culture system comprising colorectal cancer organoids and cancer-associated fibroblasts to simulate the tumor microenvironment. Immunofluorescence staining validated the characteristics of both organoids and fibroblasts, showing high expression of epithelial cell markers (EPCAM), colon cancer markers (CK20), proliferation markers (KI67), and fibroblast markers (VIM, SMA). Transcriptome profiling was conducted after treatment with anticancer drugs, such as 5-fluorouracil and oxaliplatin, to identify chemoresistance-related genes. Changes in gene expression in the co-cultured colorectal cancer organoids following anticancer drug treatment, compared to monocultured organoids, particularly in pathways related to interferon-alpha/beta signaling and major histocompatibility complex class II protein complex assembly, were identified. These two gene groups potentially mediate drug resistance associated with JAK/STAT signaling. The interaction between colorectal cancer organoids and fibroblasts crucially modulates the expression of genes related to drug resistance. These findings suggest that the interaction between colorectal cancer organoids and fibroblasts significantly influences gene expression related to drug resistance, highlighting potential biomarkers and therapeutic targets for overcoming chemoresistance. Enhanced understanding of the interactions between cancer cells and their microenvironment can lead to advancements in personalized medical research..

TRPC absence induces pro-inflammatory macrophage polarization to promote obesity and exacerbate colorectal cancer

During the past half-century, although numerous interventions for obesity have arisen, the condition's prevalence has relentlessly escalated annually. Obesity represents a substantial public health challenge, especially due to its robust correlation with co-morbidities, such as colorectal cancer (CRC), which often thrives in an inflammatory tumor milieu. Of note, individuals with obesity commonly present with calcium and vitamin D insufficiencies. Transient receptor potential canonical (TRPC) channels, a subclass within the broader TRP family, function as critical calcium transporters in calcium-mediated signaling pathways. However, the exact role of TRPC channels in both obesity and CRC pathogenesis remains poorly understood. This study set out to elucidate the part played by TRPC channels in obesity and CRC development using a mouse model lacking all seven TRPC proteins (TRPC HeptaKO mice). Relative to wild-type counterparts, TRPC HeptaKO mice manifested severe obesity, evidenced by significantly heightened body weights, augmented weights of epididymal white adipose tissue (eWAT) and inguinal white adipose tissue (iWAT), increased hepatic lipid deposition, and raised serum levels of total cholesterol (T-CHO) and low-density lipoprotein cholesterol (LDL-C). Moreover, TRPC deficiency was accompanied by an decrease in thermogenic molecules like PGC1-α and UCP1, alongside a upsurge in inflammatory factors within adipose tissue. Mechanistically, it was revealed that pro-inflammatory factors originating from inflammatory macrophages in adipose tissue triggered lipid accumulation and exacerbated obesity-related phenotypes. Intriguingly, considering the well-established connection between obesity and disrupted gut microbiota balance, substantial changes in the gut microbiota composition were detected in TRPC HeptaKO mice, contributing to CRC development. This study provides valuable insights into the role and underlying mechanisms of TRPC deficiency in obesity and its related complication, CRC. Our findings offer a theoretical foundation for the prevention of adverse effects associated with TRPC inhibitors, potentially leading to new therapeutic strategies for obesity and CRC prevention.

Early life imprinting of intestinal immune tolerance and tissue homeostasis

Besides its canonical role in protecting the host from pathogens, the immune system plays an arguably equally important role in maintaining tissue homeostasis. Within barrier tissues that interface with the external microenvironment, induction of immune tolerance to innocuous antigens, such as commensal, dietary, and environmental antigens, is key to establishing immune homeostasis. The early postnatal period represents a critical window of opportunity in which parallel development of the tissue, immune cells, and microbiota allows for reciprocal regulation that shapes the long-term immunological tone of the tissue and subsequent risk of immune-mediated diseases. During early infancy, the immune system appears to sacrifice pro-inflammatory functions, prioritizing the establishment of tissue tolerance. In this review, we discuss mechanisms underlying early life windows for intestinal tolerance with a focus on newly identified RORγt+ antigen-presenting cells-Thetis cells-and highlight the role of the intestinal microenvironment in shaping intestinal immune system development and tolerance.

Analysis of intestinal epithelial cell responses to Cryptosporidium highlights the temporal effects of IFN-γ on parasite restriction

The production of IFN-γ is crucial for control of multiple enteric infections, but its impact on intestinal epithelial cells (IEC) is not well understood. Cryptosporidium parasites exclusively infect epithelial cells and the ability of interferons to activate the transcription factor STAT1 in IEC is required for parasite clearance. Here, the use of single cell RNA sequencing to profile IEC during infection revealed an increased proportion of mid-villus enterocytes during infection and induction of IFN-γ-dependent gene signatures that was comparable between uninfected and infected cells. These analyses were complemented by in vivo studies, which demonstrated that IEC expression of the IFN-γ receptor was required for parasite control. Unexpectedly, treatment of Ifng-/- mice with IFN-γ showed the IEC response to this cytokine correlates with a delayed reduction in parasite burden but did not affect parasite development. These data sets provide insight into the impact of IFN-γ on IEC and suggest a model in which IFN-γ signalling to uninfected enterocytes is important for control of Cryptosporidium.

Functional CRISPR screens in T cells reveal new opportunities for cancer immunotherapies

T cells are fundamental components in tumour immunity and cancer immunotherapies, which have made immense strides and revolutionized cancer treatment paradigm. However, recent studies delineate the predicament of T cell dysregulation in tumour microenvironment and the compromised efficacy of cancer immunotherapies. CRISPR screens enable unbiased interrogation of gene function in T cells and have revealed functional determinators, genetic regulatory networks, and intercellular interactions in T cell life cycle, thereby providing opportunities to revamp cancer immunotherapies. In this review, we briefly described the central roles of T cells in successful cancer immunotherapies, comprehensively summarised the studies of CRISPR screens in T cells, elaborated resultant master genes that control T cell activation, proliferation, fate determination, effector function, and exhaustion, and highlighted genes (BATF, PRDM1, and TOX) and signalling cascades (JAK-STAT and NF-κB pathways) that extensively engage in multiple branches of T cell responses. In conclusion, this review bridged the gap between discovering element genes to a specific process of T cell activities and apprehending these genes in the global T cell life cycle, deepened the understanding of T cell biology in tumour immunity, and outlined CRISPR screens resources that might facilitate the development and implementation of cancer immunotherapies in the clinic.

Circadian regulation of cancer stem cells and the tumor microenvironment during metastasis

The circadian clock regulates daily rhythms of numerous physiological activities through tightly coordinated modulation of gene expression and biochemical functions. Circadian disruption is associated with enhanced tumor formation and metastasis via dysregulation of key biological processes and modulation of cancer stem cells (CSCs) and their specialized microenvironment. Here, we review how the circadian clock influences CSCs and their local tumor niches in the context of different stages of tumor metastasis. Identifying circadian therapeutic targets could facilitate the development of new treatments that leverage circadian modulation to ablate tumor-resident CSCs, inhibit tumor metastasis and enhance response to current therapies.

Epithelial regulation of microbiota-immune cell dynamics

The mammalian gastrointestinal tract hosts a diverse community of trillions of microorganisms, collectively termed the microbiota, which play a fundamental role in regulating tissue physiology and immunity. Recent studies have sought to dissect the cellular and molecular mechanisms mediating communication between the microbiota and host immune system. Epithelial cells line the intestine and form an initial barrier separating the microbiota from underlying immune cells, and disruption of epithelial function has been associated with various conditions ranging from infection to inflammatory bowel diseases and cancer. From several studies, it is now clear that epithelial cells integrate signals from commensal microbes. Importantly, these non-hematopoietic cells also direct regulatory mechanisms that instruct the recruitment and function of microbiota-sensitive immune cells. In this review, we discuss the central role that has emerged for epithelial cells in orchestrating intestinal immunity and highlight epithelial pathways through which the microbiota can calibrate tissue-intrinsic immune responses.

Senolytic CAR T cells reverse aging-associated defects in intestinal regeneration and fitness

Intestinal stem cells (ISCs) drive the rapid regeneration of the gut epithelium to maintain organismal homeostasis. Aging, however, significantly reduces intestinal regenerative capacity. While cellular senescence is a key feature of the aging process, little is known about the in vivo effects of senescent cells on intestinal fitness. Here, we identify the accumulation of senescent cells in the aging gut and, by harnessing senolytic CAR T cells to eliminate them, we uncover their detrimental impact on epithelial integrity and overall intestinal homeostasis in natural aging, injury and colitis. Ablation of intestinal senescent cells with senolytic CAR T cells in vivo or in vitro is sufficient to promote the regenerative potential of aged ISCs. This intervention improves epithelial integrity and mucosal immune function. Overall, these results highlight the ability of senolytic CAR T cells to rejuvenate the intestinal niche and demonstrate the potential of targeted cell therapies to promote tissue regeneration in aging organisms.

SOX17 enables immune evasion of early colorectal adenomas and cancers

A hallmark of cancer is the avoidance of immune destruction. This process has been primarily investigated in locally advanced or metastatic cancer1-3; however, much less is known about how pre-malignant or early invasive tumours evade immune detection. Here, to understand this process in early colorectal cancers (CRCs), we investigated how naive colon cancer organoids that were engineered in vitro to harbour Apc-null, KrasG12D and Trp53-null (AKP) mutations adapted to the in vivo native colonic environment. Comprehensive transcriptomic and chromatin analyses revealed that the endoderm-specifying transcription factor SOX17 became strongly upregulated in vivo. Notably, whereas SOX17 loss did not affect AKP organoid propagation in vitro, its loss markedly reduced the ability of AKP tumours to persist in vivo. The small fraction of SOX17-null tumours that grew displayed notable interferon-γ (IFNγ)-producing effector-like CD8+ T cell infiltrates in contrast to the immune-suppressive microenvironment in wild-type counterparts. Mechanistically, in both endogenous Apc-null pre-malignant adenomas and transplanted organoid-derived AKP CRCs, SOX17 suppresses the ability of tumour cells to sense and respond to IFNγ, preventing anti-tumour T cell responses. Finally, SOX17 engages a fetal intestinal programme that drives differentiation away from LGR5+ tumour cells to produce immune-evasive LGR5- tumour cells with lower expression of major histocompatibility complex class I (MHC-I). We propose that SOX17 is a transcription factor that is engaged during the early steps of colon cancer to orchestrate an immune-evasive programme that permits CRC initiation and progression.

Moderate intensity exercise may protect cardiac function by influencing spleen microbiome composition

The beneficial effects of physical exercise on human cardiorespiratory fitness might be through reduced systemic inflammation, but the mechanism remains a controversy. Recent studies have highlighted the importance of spleen microbiomes in immune regulation. Hence, we conducted a study using a high-fat diet and exercise mouse model to investigate the relationships among different exercise intensities, spleen microbiome composition, and cardiac function. The mice spleen contained a diverse array of microbiota. Different intensities of exercise resulted in varying compositions of the spleen microbiome, Treg cell levels, and mouse heart function. Additionally, the abundance of Lactobacillus johnsonii in the mouse spleen exhibited a positive correlation with Treg cell levels, suggesting that Lactobacillus johnsonii may contribute to the production of Treg cells, potentially explaining the protective role of moderate-intensity exercise on cardiac function. In conclusion, our findings provide evidence that moderate-intensity exercise may promote cardiac function protection by influencing the spleen microbiome composition.

Role reversals: non-canonical roles for immune and non-immune cells in the gut

The intestine is home to an intertwined network of epithelial, immune, and neuronal cells as well as the microbiome, with implications for immunity, systemic metabolism, and behavior. While the complexity of this microenvironment has long since been acknowledged, recent technological advances have propelled our understanding to an unprecedented level. Notably, the microbiota and non-immune or structural cells have emerged as important conductors of intestinal immunity, and by contrast, cells of both the innate and adaptive immune systems have demonstrated non-canonical roles in tissue repair and metabolism. This review highlights recent works in the following two streams: non-immune cells of the intestine performing immunological functions; and traditional immune cells exhibiting non-immune functions in the gut.

Crosstalk between colorectal CSCs and immune cells in tumorigenesis, and strategies for targeting colorectal CSCs

Cancer immunotherapy has emerged as a promising strategy in the treatment of colorectal cancer, and relapse after tumor immunotherapy has attracted increasing attention. Cancer stem cells (CSCs), a small subset of tumor cells with self-renewal and differentiation capacities, are resistant to traditional therapies such as radiotherapy and chemotherapy. Recently, CSCs have been proven to be the cells driving tumor relapse after immunotherapy. However, the mutual interactions between CSCs and cancer niche immune cells are largely uncharacterized. In this review, we focus on colorectal CSCs, CSC-immune cell interactions and CSC-based immunotherapy. Colorectal CSCs are characterized by robust expression of surface markers such as CD44, CD133 and Lgr5; hyperactivation of stemness-related signaling pathways, such as the Wnt/β-catenin, Hippo/Yap1, Jak/Stat and Notch pathways; and disordered epigenetic modifications, including DNA methylation, histone modification, chromatin remodeling, and noncoding RNA action. Moreover, colorectal CSCs express abnormal levels of immune-related genes such as MHC and immune checkpoint molecules and mutually interact with cancer niche cells in multiple tumorigenesis-related processes, including tumor initiation, maintenance, metastasis and drug resistance. To date, many therapies targeting CSCs have been evaluated, including monoclonal antibodies, antibody‒drug conjugates, bispecific antibodies, tumor vaccines adoptive cell therapy, and small molecule inhibitors. With the development of CSC-/niche-targeting technology, as well as the integration of multidisciplinary studies, novel therapies that eliminate CSCs and reverse their immunosuppressive microenvironment are expected to be developed for the treatment of solid tumors, including colorectal cancer.

p53 suppresses MHC class II presentation by intestinal epithelium to protect against radiation-induced gastrointestinal syndrome

Radiation-induced gastrointestinal syndrome is a major complication and limiting factor for radiotherapy. Tumor suppressor p53 has a protective role in radiation-induced gastrointestinal toxicity. However, its underlying mechanism remains unclear. Here we report that regulating the IL12-p40/MHC class II signaling pathway is a critical mechanism by which p53 protects against radiation-induced gastrointestinal syndrome. p53 inhibits the expression of inflammatory cytokine IL12-p40, which in turn suppresses the expression of MHC class II on intestinal epithelial cells to suppress T cell activation and inflammation post-irradiation that causes intestinal stem cell damage. Anti-IL12-p40 neutralizing antibody inhibits inflammation and rescues the defects in intestinal epithelial regeneration post-irradiation in p53-deficient mice and prolongs mouse survival. These results uncover that the IL12-p40/MHC class II signaling mediates the essential role of p53 in ensuring intestinal stem cell function and proper immune reaction in response to radiation to protect mucosal epithelium, and suggest a potential therapeutic strategy to protect against radiation-induced gastrointestinal syndrome.

MHC class III lymphocyte antigens 6 as endogenous immunotoxins: Unlocking immunotherapy in proficient mismatch repair colorectal cancer

A majority of cancers, including colorectal cancer (CRC) with intact DNA mismatch repair, exhibit a paralyzed antitumor immune response and resistance to immune checkpoint inhibitors. Members of MHC class III lymphocyte antigen 6G (LY6G) encode glycosylphosphatidylinositol (GPI) proteins anchored to the membrane. Snake venom neurotoxins and LY6G proteins share a three-finger (3F) folding domain. LY6 proteins such as LY6G6D are gaining a reputation as excellent tumor-associated antigens that can potently inhibit anti-tumor immunity in cancers with proficient mismatch repair. Thus, we called MHC class III LY6G endogenous immunotoxins. Since the discovery of LY6G6D as a tumor-associated antigen, T-cell engagers (TcEs) have been developed to simultaneously bind LY6G6D on cancer cells and CD3 on T cells, improving the treatment of metastatic solid tumors that are resistant to ICIs. We present a current understanding of how alterations in MHC class III genes inhibit antitumor immunity, and how these understandings can be turned into effective treatments for patients who are refractory to standard immunotherapy. This article is categorized under: Cancer > Genetics/Genomics/Epigenetics Cancer > Molecular and Cellular Physiology.

Microbial regulation of ferroptosis in cancer

Different gut microbial metabolites have the potential to promote and protect against colorectal cancer (CRC). A study now links trans -3-indoleacrylic acid (IDA), a metabolite derived from Peptostreptococcus anaerobius , with colorectal carcinogenesis through a distinct ferroptosis pathway AHR–ALDH1A3–FSP1–CoQ10.

Segmented filamentous bacteria-induced epithelial MHCII regulates cognate CD4+ IELs and epithelial turnover

Intestinal epithelial cells have the capacity to upregulate MHCII molecules in response to certain epithelial-adhesive microbes, such as segmented filamentous bacteria (SFB). However, the mechanism regulating MHCII expression as well as the impact of epithelial MHCII-mediated antigen presentation on T cell responses targeting those microbes remains elusive. Here, we identify the cellular network that regulates MHCII expression on the intestinal epithelium in response to SFB. Since MHCII on the intestinal epithelium is dispensable for SFB-induced Th17 response, we explored other CD4+ T cell-based responses induced by SFB. We found that SFB drive the conversion of cognate CD4+ T cells to granzyme+ CD8α+ intraepithelial lymphocytes. These cells accumulate in small intestinal intraepithelial space in response to SFB. Yet, their accumulation is abrogated by the ablation of MHCII on the intestinal epithelium. Finally, we show that this mechanism is indispensable for the SFB-driven increase in the turnover of epithelial cells in the ileum. This study identifies a previously uncharacterized immune response to SFB, which is dependent on the epithelial MHCII function.

Aged intestinal stem cells propagate cell-intrinsic sources of inflammaging in mice

Low-grade chronic inflammation is a hallmark of ageing, associated with impaired tissue function and disease development. However, how cell-intrinsic and -extrinsic factors collectively establish this phenotype, termed inflammaging, remains poorly understood. We addressed this question in the mouse intestinal epithelium, using mouse organoid cultures to dissect stem cell-intrinsic and -extrinsic sources of inflammaging. At the single-cell level, we found that inflammaging is established differently along the crypt-villus axis, with aged intestinal stem cells (ISCs) strongly upregulating major histocompatibility complex class II (MHC-II) genes. Importantly, the inflammaging phenotype was stably propagated by aged ISCs in organoid cultures and associated with increased chromatin accessibility at inflammation-associated loci in vivo and ex vivo, indicating cell-intrinsic inflammatory memory. Mechanistically, we show that the expression of inflammatory genes is dependent on STAT1 signaling. Together, our data identify that intestinal inflammaging in mice is promoted by a cell-intrinsic mechanism, stably propagated by ISCs, and associated with a disbalance in immune homeostasis.

Microbial underdogs: exploring the significance of low-abundance commensals in host-microbe interactions

Our understanding of host-microbe interactions has broadened through numerous studies over the past decades. However, most investigations primarily focus on the dominant members within ecosystems while neglecting low-abundance microorganisms. Moreover, laboratory animals usually do not have microorganisms beyond bacteria. The phenotypes observed in laboratory animals, including the immune system, have displayed notable discrepancies when compared to real-world observations due to the diverse microbial community in natural environments. Interestingly, recent studies have unveiled the beneficial roles played by low-abundance microorganisms. Despite their rarity, these keystone taxa play a pivotal role in shaping the microbial composition and fulfilling specific functions in the host. Consequently, understanding low-abundance microorganisms has become imperative to unravel true commensalism. In this review, we provide a comprehensive overview of important findings on how low-abundance commensal microorganisms, including low-abundance bacteria, fungi, archaea, and protozoa, interact with the host and contribute to host phenotypes, with emphasis on the immune system. Indeed, low-abundance microorganisms play vital roles in the development of the host's immune system, influence disease status, and play a key role in shaping microbial communities in specific niches. Understanding the roles of low-abundance microbes is important and will lead to a better understanding of the true host-microbe relationships.

Dietary fat and lipid metabolism in the tumor microenvironment

Metabolic reprogramming has been considered a core hallmark of cancer, in which excessive accumulation of lipids promote cancer initiation, progression and metastasis. Lipid metabolism often includes the digestion and absorption of dietary fat, and the ways in which cancer cells utilize lipids are often influenced by the complex interactions within the tumor microenvironment. Among multiple cancer risk factors, obesity has a positive association with multiple cancer types, while diets like calorie restriction and fasting improve health and delay cancer. Impact of these diets on tumorigenesis or cancer prevention are generally studied on cancer cells, despite heterogeneity of the tumor microenvironment. Cancer cells regularly interact with these heterogeneous microenvironmental components, including immune and stromal cells, to promote cancer progression and metastasis, and there is an intricate metabolic crosstalk between these compartments. Here, we focus on discussing fat metabolism and response to dietary fat in the tumor microenvironment, focusing on both immune and stromal components and shedding light on therapeutic strategies surrounding lipid metabolic and signaling pathways.

Nutrient regulation of development and cell fate decisions

Diet contributes to health at all stages of life, from embryonic development to old age. Nutrients, including vitamins, amino acids, lipids and sugars, have instructive roles in directing cell fate and function, maintaining stem cell populations, tissue homeostasis and alleviating the consequences of aging. This Review highlights recent findings that illuminate how common diets and specific nutrients impact cell fate decisions in healthy and disease contexts. We also draw attention to new models, technologies and resources that help to address outstanding questions in this emerging field and may lead to dietary approaches that promote healthy development and improve disease treatments.

Towards modulating the gut microbiota to enhance the efficacy of immune-checkpoint inhibitors

The gut microbiota modulates immune processes both locally and systemically. This includes whether and how the immune system reacts to emerging tumours, whether antitumour immune responses are reactivated during treatment with immune-checkpoint inhibitors (ICIs), and whether unintended destructive immune pathologies accompany such treatment. Advances over the past decade have established that the gut microbiota is a promising target and that modulation of the microbiota might overcome resistance to ICIs and/or improve the safety of treatment. However, the specific mechanisms through which the microbiota modulates antitumour immunity remain unclear. Understanding the biology underpinning microbial associations with clinical outcomes in patients receiving ICIs, as well as the landscape of a 'healthy' microbiota would provide a critical foundation to facilitate opportunities to effectively manipulate the microbiota and thus improve patient outcomes. In this Review, we explore the role of diet and the gut microbiota in shaping immune responses during treatment with ICIs and highlight the key challenges in attempting to leverage the gut microbiome as a practical tool for the clinical management of patients with cancer.

Key regulators of intestinal stem cells: diet, microbiota, and microbial metabolites

Interactions between diet and the intestinal microbiome play an important role in human health and disease development. It is well known that such interactions, whether direct or indirect, trigger a series of metabolic reactions in the body. Evidence suggests that intestinal stem cells (ISCs), which are phenotypic precursors of various intestinal epithelial cells, play a significant role in the regulation of intestinal barrier function and homeostasis. The advent and evolution of intestinal organoid culture techniques have presented a key opportunity to study the association between the intestinal microenvironment and ISCs. As a result, the effects exerted by dietary factors, intestinal microbiomes, and their metabolites on the metabolic regulation of ISCs and the potential mechanisms underlying such effects are being gradually revealed. This review summarises the effects of different dietary patterns on the behaviour and functioning of ISCs and focuses on the crosstalk between intestinal microbiota, related metabolites, and ISCs, with the aim of fully understanding the relationship between these three factors and providing further insights into the complex mechanisms associated with ISCs in the human body. Gaining an understanding of these mechanisms may lead to the development of novel dietary interventions or drugs conducive to intestinal health.

Aged hematopoietic stem cells entrap regulatory T cells to create a prosurvival microenvironment

Although DNA mutation drives stem cell aging, how mutation-accumulated stem cells obtain clonal advantage during aging remains poorly understood. Here, using a mouse model of irradiation-induced premature aging and middle-aged mice, we show that DNA mutation accumulation in hematopoietic stem cells (HSCs) during aging upregulates their surface expression of major histocompatibility complex class II (MHCII). MHCII upregulation increases the chance for recognition by bone marrow (BM)-resident regulatory T cells (Tregs), resulting in their clonal expansion and accumulation in the HSC niche. On the basis of the establishment of connexin 43 (Cx43)-mediated gap junctions, BM Tregs transfer cyclic adenosine monophosphate (cAMP) to aged HSCs to diminish apoptotic priming and promote their survival via activation of protein kinase A (PKA) signaling. Importantly, targeting the HSC-Treg interaction or depleting Tregs effectively prevents the premature/physiological aging of HSCs. These findings show that aged HSCs use an active self-protective mechanism by entrapping local Tregs to construct a prosurvival niche and obtain a clonal advantage.

Cancer cell plasticity and MHC-II-mediated immune tolerance promote breast cancer metastasis to lymph nodes

Tumor-draining lymph nodes (TDLNs) are important for tumor antigen-specific T cell generation and effective anticancer immune responses. However, TDLNs are often the primary site of metastasis, causing immune suppression and worse outcomes. Through cross-species single-cell RNA-Seq analysis, we identified features defining cancer cell heterogeneity, plasticity, and immune evasion during breast cancer progression and lymph node metastasis (LNM). A subset of cancer cells in the lymph nodes exhibited elevated MHC class II (MHC-II) gene expression in both mice and humans. MHC-II+ cancer cells lacked costimulatory molecule expression, leading to regulatory T cell (Treg) expansion and fewer CD4+ effector T cells in TDLNs. Genetic knockout of MHC-II reduced LNM and Treg expansion, while overexpression of the MHC-II transactivator, Ciita, worsened LNM and caused excessive Treg expansion. These findings demonstrate that cancer cell MHC-II expression promotes metastasis and immune evasion in TDLNs.

The Role of Diet and Gut Microbiota Interactions in Metabolic Homeostasis

Diet is a pivotal determinant in shaping the structure and function of resident microorganisms in the gut through different food components, nutritive proportion, and calories. The effects of diet on host metabolism and physiology can be mediated through the gut microbiota. Gut microbiota-derived metabolites have been shown to regulate glucose and lipid metabolism, energy consumption, and the immune system. On the other hand, emerging evidence indicates that baseline gut microbiota could predict the efficacy of diet intervention, highlighting gut microbiota can be harnessed as a biomarker in personalized nutrition. In this review, the alterations of gut microbiota in different dietary components and dietary patterns, and the potential mechanisms in the diet-microbiota crosstalk are summarized to understand the interactions of diet and gut microbiota on the impact of metabolic homeostasis.

Cytotoxic CD4 T cells in the mucosa and in cancer

CD4 T cells were initially described as helper cells that promote either the cellular immune response (Th1 cells) or the humoral immune response (Th2 cells). Since then, a plethora of functionally distinct helper and regulatory CD4 T cell subsets have been described. CD4 T cells with cytotoxic function were first described in the setting of viral infections and autoimmunity, and more recently in cancer and gut dysbiosis. Regulatory CD4 T cell subsets such as Tregs and T-regulatory type 1 (Tr1) cells have also been shown to have cytotoxic potential. Indeed, Tr1 cells have been shown to be important for maintenance of stem cell niches in the bone marrow and the gut. This review will provide an overview of cytotoxic CD4 T cell development, and discuss the role of inflammatory and Tr1-like cytotoxic CD4 T cells in maintenance of intestinal stem cells and in anti-cancer immune responses.

Role of the Gut Microbiota and Its Metabolites in Tumorigenesis or Development of Colorectal Cancer

Colorectal cancer (CRC) is the most common cancer of the digestive system with high mortality and morbidity rates. Gut microbiota is found in the intestines, especially the colorectum, and has structured crosstalk interactions with the host that affect several physiological processes. The gut microbiota include CRC-promoting bacterial species, such as Fusobacterium nucleatum, Escherichia coli, and Bacteroides fragilis, and CRC-protecting bacterial species, such as Clostridium butyricum, Streptococcus thermophilus, and Lacticaseibacillus paracasei, which along with other microorganisms, such as viruses and fungi, play critical roles in the development of CRC. Different bacterial features are identified in patients with early-onset CRC, combined with different patterns between fecal and intratumoral microbiota. The gut microbiota may be beneficial in the diagnosis and treatment of CRC; some bacteria may serve as biomarkers while others as regulators of chemotherapy and immunotherapy. Furthermore, metabolites produced by the gut microbiota play essential roles in the crosstalk with CRC cells. Harmful metabolites include some primary bile acids and short-chain fatty acids, whereas others, including ursodeoxycholic acid and butyrate, are beneficial and impede tumor development and progression. This review focuses on the gut microbiota and its metabolites, and their potential roles in the development, diagnosis, and treatment of CRC.

Dynamic Intestinal Stem Cell Plasticity and Lineage Remodeling by a Nutritional Environment Relevant to Human Risk for Tumorigenesis

New Western-style diet 1 (NWD1), a purified diet establishing mouse exposure to key nutrients recapitulating levels that increase human risk for intestinal cancer, reproducibly causes mouse sporadic intestinal and colonic tumors reflecting human etiology, incidence, frequency, and lag with developmental age. Complex NWD1 stem cell and lineage reprogramming was deconvolved by bulk and single-cell RNA sequencing, single-cell Assay for Transposase-Accessible Chromatin using sequencing, functional genomics, and imaging. NWD1 extensively, rapidly, and reversibly, reprogrammed Lgr5hi stem cells, epigenetically downregulating Ppargc1a expression, altering mitochondrial structure and function. This suppressed Lgr5hi stem cell functions and developmental maturation of Lgr5hi cell progeny as cells progressed through progenitor cell compartments, recapitulated by Ppargc1a genetic inactivation in Lgr5hi cells in vivo. Mobilized Bmi1+, Ascl2hi cells adapted lineages to the nutritional environment and elevated antigen processing and presentation pathways, especially in mature enterocytes, causing chronic, protumorigenic low-level inflammation. There were multiple parallels between NWD1 remodeling of stem cells and lineages with pathogenic mechanisms in human inflammatory bowel disease, also protumorigenic. Moreover, the shift to alternate stem cells reflects that the balance between Lgr5-positive and -negative stem cells in supporting human colon tumors is determined by environmental influences. Stem cell and lineage plasticity in response to nutrients supports historic concepts of homeostasis as a continual adaptation to environment, with the human mucosa likely in constant flux in response to changing nutrient exposures.

IMPLICATIONS

Although oncogenic mutations provide a competitive advantage to intestinal epithelial cells in clonal expansion, the competition is on a playing field dynamically sculpted by the nutritional environment, influencing which cells dominate in mucosal maintenance and tumorigenesis.

Gut microbiota controlling radiation-induced enteritis and intestinal regeneration

Cancer remains the second leading cause of mortality, with nearly 10 million deaths worldwide in 2020. In many cases, radiotherapy is used for its anticancer effects. However, radiation causes healthy tissue toxicity as a side effect. In intra-abdominal and pelvic malignancies, the healthy bowel is inevitably included in the radiation field, causing radiation-induced enteritis and dramatically affecting the gut microbiome. This condition is associated with significant morbidity and mortality that impairs cancer patients' and survivors' quality of life. This Review provides a critical overview of the main drivers in modulating the gut microenvironment in homeostasis, disease, and injury, focusing on gut microbial metabolites and microorganisms that influence epithelial regeneration upon radiation injury.

Inflammatory auxo-action in the stem cell division theory of cancer

Acute inflammation is a beneficial response to the changes caused by pathogens or injuries that can eliminate the source of damage and restore homeostasis in damaged tissues. However, chronic inflammation causes malignant transformation and carcinogenic effects of cells through continuous exposure to pro-inflammatory cytokines and activation of inflammatory signaling pathways. According to the theory of stem cell division, the essential properties of stem cells, including long life span and self-renewal, make them vulnerable to accumulating genetic changes that can lead to cancer. Inflammation drives quiescent stem cells to enter the cell cycle and perform tissue repair functions. However, as cancer likely originates from DNA mutations that accumulate over time via normal stem cell division, inflammation may promote cancer development, even before the stem cells become cancerous. Numerous studies have reported that the mechanisms of inflammation in cancer formation and metastasis are diverse and complex; however, few studies have reviewed how inflammation affects cancer formation from the stem cell source. Based on the stem cell division theory of cancer, this review summarizes how inflammation affects normal stem cells, cancer stem cells, and cancer cells. We conclude that chronic inflammation leads to persistent stem cells activation, which can accumulate DNA damage and ultimately promote cancer. Additionally, inflammation not only facilitates the progression of stem cells into cancer cells, but also plays a positive role in cancer metastasis.

Cyberlindnera jadinii yeast as a functional protein source for Atlantic salmon (Salmo salar L.): Early response of intestinal mucosal compartments in the distal intestine

The interplay between nutrition and the immune system is well recognized, and several studies show that experimental diets elicit local morphological changes and alteration of gene and protein expression in the intestinal mucosa of Atlantic salmon. In this study the pathophysiological effects of experimental diets on mucosal responses in the distal intestine of Atlantic salmon were investigated. Atlantic salmon were fed diets with inclusion of soybean meal (SBM) and Cyberlindnera jadinii (CJ) yeast for 7 days. A standard fish meal (FM) diet was used as a control. Morphological, immunohistochemical and gene expression analyses were used to evaluate the presence of immune cells, proliferating cells, and stem cell populations in mucosal compartments of the simple folds in the distal intestine. Fish fed SBM developed morphological changes consistent with SBM induced enteritis. Immunohistochemistry showed an increased presence of apoptotic cells, CD3ϵ and CD8α labelled cells in the simple fold epithelium of SBM group compared with the CJ group. For the investigated genes, expression levels in all three groups were mostly higher in the epithelial compartment of the simple fold than in the compartment beneath the folds. Most changes within the epithelial compartment were observed in fish fed SBM, where expression of CD3ζ, CD8α, MHC I and MHC II were lower than the FM control group. The CJ group had an increased expression of the stem cell marker Lgr5 in the epithelial compartment compared with SBM group. The division of the simple fold into an apical and basal compartment showed that the increase in Lgr5 was evident along the whole length of the simple folds and not confined to the base of the folds. Similarly, proliferation (PCNA, MCM2) and apoptosis (Caspase-3) gene expression was present in the entire length of the simple folds, suggesting that intestinal epithelial cell turnover is not confined to the basal or apical part of the fold. This study shows that the epithelial compartment is active in the early immunoregulatory response towards dietary stimuli and that the level of an intestinal stem cell marker in salmon was influenced by a diet containing CJ yeast.

Convergence of YAP/TAZ, TEAD and TP63 activity is associated with bronchial premalignant severity and progression

BACKGROUND

Bronchial premalignant lesions (PMLs) are composed primarily of cells resembling basal epithelial cells of the airways, which through poorly understood mechanisms have the potential to progress to lung squamous cell carcinoma (LUSC). Despite ongoing efforts that have mapped gene expression and cell diversity across bronchial PML pathologies, signaling and transcriptional events driving malignancy are poorly understood. Evidence has suggested key roles for the Hippo pathway effectors YAP and TAZ and associated TEAD and TP63 transcription factor families in bronchial basal cell biology and LUSC. In this study we examine the functional association of YAP/TAZ, TEADs and TP63 in bronchial epithelial cells and PMLs.

METHODS

We performed RNA-seq in primary human bronchial epithelial cells following small interfering RNA (siRNA)-mediated depletion of YAP/TAZ, TEADs or TP63, and combined these data with ChIP-seq analysis of these factors. Directly activated or repressed genes were identified and overlapping genes were profiled across gene expression data obtained from progressive or regressive human PMLs and across lung single cell RNA-seq data sets.

RESULTS

Analysis of genes regulated by YAP/TAZ, TEADs, and TP63 in human bronchial epithelial cells revealed a converged transcriptional network that is strongly associated with the pathological progression of bronchial PMLs. Our observations suggest that YAP/TAZ-TEAD-TP63 associate to cooperatively promote basal epithelial cell proliferation and repress signals associated with interferon responses and immune cell communication. Directly repressed targets we identified include the MHC Class II transactivator CIITA, which is repressed in progressive PMLs and associates with adaptive immune responses in the lung. Our findings provide molecular insight into the control of gene expression events driving PML progression, including those contributing to immune evasion, offering potential new avenues for lung cancer interception.

CONCLUSIONS

Our study identifies important gene regulatory functions for YAP/TAZ-TEAD-TP63 in the early stages of lung cancer development, which notably includes immune-suppressive roles, and suggest that an assessment of the activity of this transcriptional complex may offer a means to identify immune evasive bronchial PMLs and serve as a potential therapeutic target.

Western diet influences on microbiome and carcinogenesis

The intestinal microbiota composition and associated bioactivities are sensitive to various modifier cues such as stress, inflammation, age, life-style and nutrition, which in turn are associated with susceptibility to developing cancer. Among these modifiers, diet has been shown to influence both microbiota composition as well as being an important source of microbial-derived compounds impacting the immunological, neurological and hormonal systems. Thus, it is necessary to take a holistic view when considering effect of diet on health and diseases. In this review, we focus on the interplay between western diet, the microbiota and cancer development by dissecting key components of the diet and leveraging data from human interventions and pre-clinical studies to better understand this relationship. We highlight key progress as well as stressing limitations in this field of research.

Immunometabolism at the crossroads of obesity and cancer-a Keystone Symposia report

Immunometabolism considers the relationship between metabolism and immunity. Typically, researchers focus on either the metabolic pathways within immune cells that affect their function or the impact of immune cells on systemic metabolism. A more holistic approach that considers both these viewpoints is needed. On September 5-8, 2022, experts in the field of immunometabolism met for the Keystone symposium "Immunometabolism at the Crossroads of Obesity and Cancer" to present recent research across the field of immunometabolism, with the setting of obesity and cancer as an ideal example of the complex interplay between metabolism, immunity, and cancer. Speakers highlighted new insights on the metabolic links between tumor cells and immune cells, with a focus on leveraging unique metabolic vulnerabilities of different cell types in the tumor microenvironment as therapeutic targets and demonstrated the effects of diet, the microbiome, and obesity on immune system function and cancer pathogenesis and therapy. Finally, speakers presented new technologies to interrogate the immune system and uncover novel metabolic pathways important for immunity.

Ferroptosis open a new door for colorectal cancer treatment

Colorectal cancer (CRC) is the third highest incidence and the second highest mortality malignant tumor in the world. The etiology and pathogenesis of CRC are complex. Due to the long course of the disease and no obvious early symptoms, most patients are diagnosed as middle and late stages. CRC is prone to metastasis, most commonly liver metastasis, which is one of the leading causes of death in CRC patients. Ferroptosis is a newly discovered cell death form with iron dependence, which is driven by excessive lipid peroxides on the cell membrane. It is different from other form of programmed cell death in morphology and mechanism, such as apoptosis, pyroptosis and necroptosis. Numerous studies have shown that ferroptosis may play an important role in the development of CRC. For advanced or metastatic CRC, ferroptosis promises to open a new door in the setting of poor response to chemotherapy and targeted therapy. This mini review focuses on the pathogenesis of CRC, the mechanism of ferroptosis and the research status of ferroptosis in CRC treatment. The potential association between ferroptosis and CRC and some challenges are discussed.

Metabolic determinants of tumour initiation

Tumours exhibit notable metabolic alterations compared with their corresponding normal tissue counterparts. These metabolic alterations can support anabolic growth, enable survival in hostile environments and regulate gene expression programmes that promote malignant progression. Whether these metabolic changes are selected for during malignant transformation or can themselves be drivers of tumour initiation is unclear. However, intriguingly, many of the major bottlenecks for tumour initiation - control of cell fate, survival and proliferation - are all amenable to metabolic regulation. In this article, we review evidence demonstrating a critical role for metabolic pathways in processes that support the earliest stages of tumour development. We discuss how cell-intrinsic factors, such as the cell of origin or transforming oncogene, and cell-extrinsic factors, such as local nutrient availability, promote or restrain tumour initiation. Deeper insight into how metabolic pathways control tumour initiation will improve our ability to design metabolic interventions to limit tumour incidence.

Epigenetic effects of high-fat diet on intestinal tumorigenesis in C57BL/6J-Apc Min/+ mice

Aim

Obesity and obesogenic diets might partly accelerate cancer development through epigenetic mechanisms. To determine these early effects, we investigated the impact of three days of a high-fat diet on epigenomic and transcriptomic changes in Apc ^Min/+ murine intestinal epithelia.

Method

ChIP-Seq and RNA-Seq were performed on small intestinal epithelia of WT and Apc ^Min/+ male mice fed high-fat diet (HFD) or low-fat diet (LFD) for three days to identify genomic regions associated with differential H3K27ac levels as a marker of variant enhancer loci (VELs) as well as differentially expressed genes (DEGs).

Results

Regarding epigenetic and transcriptomic changes, diet type (LFD vs. HFD) showed a significant impact, and genotype (WT vs.Apc ^Min/+) showed a small impact. Compared to LFD, HFD resulted in 1306 gained VELs, 230 lost VELs, 133 upregulated genes, and 127 downregulated genes in WT mice, with 1056 gained VELs, 371 lost VELs, 222 upregulated genes, and 182 downregulated genes in Apc ^Min/+ mice. Compared to the WT genotype, the Apc ^Min/+ genotype resulted in zero changed VELs for either diet type group, 21 DEGs for LFD, and 48 DEGs for HFD. Most gained VELs, and upregulated genes were associated with lipid metabolic processes. Gained VELs were also associated with Wnt signaling. Downregulated genes were associated with antigen presentation and processing.

Conclusion

Three days of HFD-induced epigenomic and transcriptomic changes involving metabolic and immunologic pathways that may promote tumor growth in the genetically predisposed murine intestine without affecting key cancer signaling pathways.