XBP1 regulates the protumoral function of tumor-associated macrophages in human colorectal cancer

YTHDF2 favors protumoral macrophage polarization and implies poor survival outcomes in triple negative breast cancer

Patients with triple-negative breast cancer (TNBC) frequently experience resistance to chemotherapy, leading to recurrence. The approach of optimizing anti-tumoral immunological effect is promising in overcoming such resistance, given the heterogeneity and lack of biomarkers in TNBC. In this study, we focused on YTHDF2, an N6-methyladenosine (m6A) RNA-reader protein, in macrophages, one of the most abundant intra-tumoral immune cells. Using single-cell sequencing and ex vivo experiments, we discovered that YTHDF2 significantly promotes pro-tumoral phenotype polarization of macrophages and is closely associated with down-regulated antigen-presentation signaling to other immune cells in TNBC. The in vitro deprivation of YTHDF2 favors anti-tumoral effect. Expressions of multiple transcription factors, especially SPI1, were consistently observed in YTHDF2-high macrophages, providing potential therapeutic targets for new strategies. In conclusion, YTHDF2 in macrophages appears to promote pro-tumoral effects while suppressing immune activity, indicating the treatment targeting YTHDF2 or its transcription factors could be a promising strategy for chemoresistant TNBC.

Detailed role of SR-A1 and SR-E3 in tumor biology, progression, and therapy

The first host defense systems are the innate immune response and the inflammatory response. Among innate immune cells, macrophages, are crucial because they preserve tissue homeostasis and eradicate infections by phagocytosis, or the ingestion of particles. Macrophages exhibit phenotypic variability contingent on their stimulation state and tissue environment and may be detected in several tissues. Meanwhile, critical inflammatory functions are played by macrophage scavenger receptors, in particular, SR-A1 (CD204) and SR-E3 (CD206), in a variety of pathophysiologic events. Such receptors, which are mainly found on the surface of multiple types of macrophages, have different effects on processes, including atherosclerosis, innate and adaptive immunity, liver and lung diseases, and, more recently, cancer. Although macrophage scavenger receptors have been demonstrated to be active across the disease spectrum, conflicting experimental findings and insufficient signaling pathways have hindered our comprehension of the molecular processes underlying its array of roles. Herein, as SR-A1 and SR-E3 functions are often binary, either protecting the host or impairing the pathophysiology of cancers has been reviewed. We will look into their function in malignancies, with an emphasis on their recently discovered function in macrophages and the possible therapeutic benefits of SR-A1 and SR-E3 targeting.

CXCL1/IGHG1 signaling enhances crosstalk between tumor cells and tumor-associated macrophages to promote MC-LR-induced colorectal cancer progression

Microcystin-leucine arginine (MC-LR) is a common cyantotoxin produced by hazardous cyanobacterial blooms, and eutrophication is increasing the contamination level of MC-LR in drinking water supplies and aquatic foods. MC-LR has been linked to colorectal cancer (CRC) progression associated with tumor microenvironment, however, the underlying mechanism is not clearly understood. In present study, by using GEO, KEGG, GESA and ImmPort database, MC-LR related differentially expressed genes (DEGs) and pathway- and gene set-enrichment analysis were performed. Of the three identified DEGs (CXCL1, GUCA2A and GDF15), CXCL1 was shown a positive association with tumor infiltration, and was validated to have a dominantly higher upregulation in MC-LR-treated tumor-associated macrophages (TAMs) rather than in MC-LR-treated CRC cells. Both CRC cell/macrophage co-culture and xenograft mouse models indicated that MC-LR stimulated TAMs to secrete CXCL1 resulting in promoted proliferation, migration, and invasion capability of CRC cells. Furtherly, IP-MS assay found that interaction between TAMs-derived CXCL1 and CRC cell-derived IGHG1 may enhance CRC cell proliferation and migration after MC-LR treatment, and this effect can be attenuated by silencing IGHG1 in CRC cell. In addition, molecular docking analysis, co-immunoprecipitation and immunofluorescence further proved the interactions between CXCL1 and IGHG1. In conclusion, CXCL1 secreted by TAMs can trigger IGHG1 expression in CRC cells, which provides a new clue in elucidating the mechanism of MC-LR-mediated CRC progression.

A comprehensive review of phytochemicals targeting macrophages for the regulation of colorectal cancer progression

BACKGROUND

Phytochemicals are natural compounds derived from plants, and are now at the forefront of anti-cancer research. Macrophage immunotherapy plays a crucial role in the treatment of colorectal cancer (CRC). In the context of colorectal cancer, which remains highly prevalent and difficult to treat, it is of research value to explore the potential mechanisms and efficacy of phytochemicals targeting macrophages for CRC treatment.

PURPOSE

The aim of this study was to gain insight into the role of phytochemical-macrophage interactions in regulating CRC and to provide a theoretical basis for the development of new therapeutic strategies in the future.

STUDY DESIGN

This review discusses the potential immune mechanisms of phytochemicals for the treatment of CRC by summarizing research of phytochemicals targeting macrophages.

METHODS

We reviewed the PubMed, EMBASE, Web of Science and CNKI databases from their initial establishment to July 2023 to classify and summaries phytochemicals according to their mechanism of action in targeting macrophages.

RESULTS

The results of the literature review suggest that phytochemicals interfere with CRC development by affecting macrophages through four main mechanisms. Firstly, they modulate the production of cytotoxic substances, such as NO and ROS, by macrophages to exert anticancer effects. Secondly, phytochemicals polarize macrophages towards the M1 phenotype, inhibit M2 polarisation and enhance the anti-tumour immune responses. Thirdly, they enhance the secretion of macrophage-derived cytokines and alter the tumour microenvironment, thereby inhibiting tumor growth. Finally, they activate the immune response by targeting macrophages, triggering the recruitment of other immune cells, thereby enhancing the immune killing effect and exerting anti-tumor effects. These findings highlight phytochemicals as potential therapeutic strategies to intervene in colorectal cancer development by modulating macrophage activity, providing a strong theoretical basis for future clinical applications.

CONCLUSION

Phytochemicals exhibit potential anti-tumour effects by modulating macrophage activity and intervening in the colorectal cancer microenvironment by multiple mechanisms.

CircPDIA3/miR-449a/XBP1 feedback loop curbs pyroptosis by inhibiting palmitoylation of the GSDME-C domain to induce chemoresistance of colorectal cancer

Although oxaliplatin (OXA) is widely used in the frontline treatment of colorectal cancer (CRC), CRC recurrence is commonly observed due to OXA resistance. OXA resistance is associated with a number of factors, including abnormal regulation of pyroptosis. It is therefore important to elucidate the abnormal regulatory mechanism underlying pyroptosis. Here, we identified that the circular RNA circPDIA3 played an important role in chemoresistance in CRC. CircPDIA3 could induce chemoresistance in CRC by inhibiting pyroptosis both in vitro and in vivo. Mechanistically, RIP, RNA pull-down and co-IP assays revealed that circPDIA3 directly bonded to the GSDME-C domain, subsequently enhanced the autoinhibitory effect of the GSDME-C domain through blocking the GSDME-C domain palmitoylation by ZDHHC3 and ZDHHC17, thereby restraining pyroptosis. Additionally, it was found that the circPDIA3/miR-449a/XBP1 positive feedback loop increased the expression of circPDIA3 to induce chemoresistance. Furthermore, our clinical data and patient-derived tumor xenograft (PDX) models supported the positive association of circPDIA3 with development of chemoresistance in CRC patients. Taken together, our findings demonstrated that circPDIA3 could promote chemoresistance by amplifying the autoinhibitory effect of the GSDME-C domain through inhibition of the GSDME-C domain palmitoylation in CRC. This study provides novel insights into the mechanism of circRNA in regulating pyroptosis and providing a potential therapeutic target for reversing chemoresistance of CRC.

Surgical stress induced tumor immune suppressive environment

Despite significant advances in cancer treatment over the decades, surgical resection remains a prominent management approach for solid neoplasms. Unfortunately, accumulating evidence suggests that surgical stress caused by tumor resection may potentially trigger postoperative metastatic niche formation. Surgical stress not only activates the sympathetic-adrenomedullary axis and hypothalamic-pituitary-adrenocortical axis but also induces hypoxia and hypercoagulable state. These adverse factors can negatively impact the immune system by downregulating immune effector cells and upregulating immune suppressor cells, which contribute to the colonization and progression of postoperative tumor metastatic niche. This review summarizes the effects of surgical stress on four types of immune effector cells (neutrophils, macrophages, natural killer cells and cytotoxic T lymphocytes) and two types of immunosuppressive cells (regulatory T cells and myeloid-derived suppressor cells), and discusses the immune mechanisms of postoperative tumor relapse and progression. Additionally, relevant therapeutic strategies to minimize the pro-tumorigenic effects of surgical stress are elucidated.

Neoadjuvant chemotherapy-induced remodeling of human hormonal receptor-positive breast cancer revealed by single-cell RNA sequencing

Hormone receptor-positive breast cancer (HR+ BC) is known to be relatively insensitive to chemotherapy, and since chemotherapy has remained the major neoadjuvant therapy for HR+ BC, the undetermined mechanism of chemoresistance and how chemotherapy reshapes the immune microenvironment need to be explored by high-throughput technology. By using single-cell RNA sequencing and multiplexed immunofluorescence staining analysis of HR+ BC samples (paired pre- and post-neoadjuvant chemotherapy (NAC)), the levels of previously unrecognized immune cell subsets, including CD8+ T cells with pronounced expression of T-cell development (LMNA) and cytotoxicity (FGFBP2) markers, CD4+ T cells characterized by proliferation marker (ATP1B3) expression and macrophages characterized by CD52 expression, were found to be increased post-NAC, which were predictive of chemosensitivity and their antitumor function was also validated with in vitro experiments. In terms of immune checkpoint expression of CD8+ T cells, we found their changes were inconsistent post-NAC, that LAG3, VSIR were decreased, and PDCD1, HAVCR2, CTLA4, KLRC1 and BTLA were increased. In addition, we have identified novel genomic and transcriptional patterns of chemoresistant cancer cells, both innate and acquired, and have confirmed their prognostic value with TCGA cohorts. By shedding light on the ecosystem of HR+ BC reshaped by chemotherapy, our results uncover valuable candidates for predicting chemosensitivity and overcoming chemoresistance in HR+ BC.

Prenatal inflammation exposure accelerates lung cancer tumorigenesis in offspring mouse: possible links to IRE1α/XBP1-mediated M2-like polarization of TAMs and PD-L1 up-expression

BACKGROUND

Prenatal inflammation exposure (PIE) can increase the disease susceptibility in offspring such as lung cancer. Our purpose was to investigate the mechanisms of PIE on lung cancer.

METHODS

Prenatal BALB/c mice were exposed to lipopolysaccharide (LPS), and then, their offspring were intraperitoneally instilled with urethane to establish the two-stage lung cancer carcinogenesis model. At the 48 weeks of age, the offspring mice were killed and lung tissues were collected for HE, immunohistochemistry, immunofluorescence, and Luminex MAGPIX®-based assays. CD11b + F4/80 + tumor-associated macrophages (TAMs) were sorted out from lung tumor tissues by cell sorting technique. Flow cytometry was employed to evaluate the extent of M2-like polarization of TAMs and PD-L1 expression.

RESULTS

The offspring of PIE mice revealed more lung lesion changes, including atypical hyperplasia and intrapulmonary metastases. The number of lung nodules, lung organ index, and PCNA, MMP-9 and Vimentin positive cells in lung tissue of PIE group were higher than those of Control group. The increases of mRNA encoding M2 macrophage markers and cytokines in offspring of prenatal LPS-treated mice confirmed the induced effect of PIE on macrophage polarization. Additionally, PIE treatment increased the percentage of CD163 + CD206 + cells in the sorted TAMs. Importantly, endoplasmic reticulum (ER) stress-markers like GRP78/BIP and CHOP, p-IRE1α and XBP1s, and PD-L1 were up-regulated in TAMs from PIE group. Besides, we also observed that IRE1α inhibitor (KIRA6) reversed the M2-like TAMs polarization and metastasis induced by PIE.

CONCLUSIONS

IRE1α/XBP1-mediated M2-like TAMs polarization releases the pro-tumorigenic cytokines and PD-L1 expression, which may be the regulatory mechanism of accelerating lung cancer in offspring of mice undergoing PIE.

The predictive efficacy of programmed cell death in immunotherapy of melanoma: A comprehensive analysis of gene expression data for programmed cell death biomarker and therapeutic target discovery

In this study, genes linked to prognosis in skin cutaneous melanoma (SKCM) involved in programmed cell death (PCD) were identified and confirmed and prognostic models based on these genes were constructed. Acquisition and analysis of clinical data and RNA sequencing information from The Cancer Genome Atlas-SKCM (TCGA-SKCM) and Sangerbox databases, gene expression data for 477 tumor samples and 2 normal samples were successfully gathered. The patients were separated into two clusters based on consensus clustering of PCD-related genes, with Cluster A having greater tumor purity, ESTIMATE score, immune score, and matrix score, and Cluster B having a significantly distinct pattern of immune cell infiltration. The use of gene set enrichment analysis and weighted correlation network analysis showed significant associations between certain genes and factors such as tumor mutation burden, age, stage, grade, and tumor subtype. Finally, based on the 12 genes selected by Least Absolute Shrinkage and Selection Operator regression analysis (STAT3, IRF2, SLC7A11, ZEB1, LIPT1, PML, GCH1, GYS1, ABCC1, XBP1, TFAP2C, NOX4), a prognostic model of PGD-related genes was constructed. The effectiveness of the model's prognostic value was confirmed through survival analysis, time-dependent receiver operating characteristic curve, single-factor Cox regression analysis, and nomogram. We also verified the relationship between the GCH1 and MKI67 expression by wet experiment. This model has high prediction accuracy in SKCM patients and can provide a reference for clinical treatment.

Hepatocellular carcinoma cell-derived exosomal miR-21-5p promotes the polarization of tumor-related macrophages (TAMs) through SP1/XBP1 and affects the progression of hepatocellular carcinoma

BACKGROUND

Tumor-associated macrophages (TAMs) have unique functions in the development of hepatocellular carcinoma (HCC). The tumor microenvironment is in a complex state in chronic disease. As a major participant in tumor-associated inflammation, TAMs have a unique effect on promoting tumor cell proliferation, angiogenesis and immunosuppression. The in-depth study of TAMs has important scientific and clinical value and provides new ideas for the treatment of cancer.

METHODS

Bioinformatics analysis, dual-luciferase reporter assays, RT-qPCR and clinical samples were used to analyze the potential mechanism of the miR-21-5p/SP1/XBP1 molecular axis in HCC. In this study, miR-21-5p was highly expressed in HCC exosomes compared with normal hepatocyte exosomes, and HCC exosomes containing miR-21-5p promoted the proliferation and migration of HCC cells and inhibited cell apoptosis. In addition, this treatment promoted the M2 polarization of macrophages, induced the expression of transcription factor-specific protein 1 (SP1), and inhibited the expression of X-box binding protein 1 (XBP1). However, these expression trends were reversed after inhibition of miR-21-5p expression in exosomes of hepatoma cells, and the effects of exosomal miR-21-5p were partially restored after overexpression of SP1. Animal experiments also verified that exosomal miR-21-5p in HCC cells affected the expression level of the SP1/XBP1 protein and promoted M2 polarization of TAMs.

CONCLUSION

Exosomal miR-21-5p in HCC cells can affect the development of HCC cells by regulating SP1/XBP1 and promoting the M2 polarization of TAMs, thereby affecting the adverse prognostic response of HCC patients.

Translatomics to explore dynamic differences in immunocytes in the tumor microenvironment

Protein is an essential component of all living organisms and is primarily responsible for life activities; furthermore, its synthesis depends on a highly complex and accurate translation system. For proteins, the regulation at the translation level exceeds the sum of that during transcription, mRNA degradation, and protein degradation. Therefore, it is necessary to study regulation at the translation level. Imbalance in the translation process may change the cellular landscape, which not only leads to the occurrence, maintenance, progression, invasion, and metastasis of cancer but also affects the function of immune cells and changes the tumor microenvironment. Detailed analysis of transcriptional and protein atlases is needed to better understand how gene translation occurs. However, a more rigorous direct correlation between mRNA and protein levels is needed, which somewhat limits further studies. Translatomics is a technique for capturing and sequencing ribosome-related mRNAs that can effectively identify translation changes caused by ribosome stagnation and local translation abnormalities during cancer occurrence to further understand the changes in the translation landscape of cancer cells themselves and immune cells in the tumor microenvironment, which can provide new strategies and directions for tumor treatment.

Research progress on the relationship between Paneth cells-susceptibility genes, intestinal microecology and inflammatory bowel disease

Inflammatory bowel disease (IBD) is a disorder of the immune system and intestinal microecosystem caused by environmental factors in genetically susceptible people. Paneth cells (PCs) play a central role in IBD pathogenesis, especially in Crohn's disease development, and their morphology, number and function are regulated by susceptibility genes. In the intestine, PCs participate in the formation of the stem cell microenvironment by secreting antibacterial particles and play a role in helping maintain the intestinal microecology and intestinal mucosal homeostasis. Moreover, PC proliferation and maturation depend on symbiotic flora in the intestine. This paper describes the interactions among susceptibility genes, PCs and intestinal microecology and their effects on IBD occurrence and development.

Targeting MS4A4A on tumour-associated macrophages restores CD8+ T-cell-mediated antitumour immunity

OBJECTIVE

Checkpoint immunotherapy unleashes T-cell control of tumours but is suppressed by immunosuppressive myeloid cells. The transmembrane protein MS4A4A is selectively highly expressed in tumour-associated macrophages (TAMs). Here, we aimed to reveal the role of MS4A4A+ TAMs in regulating the immune escape of tumour cells and to develop novel therapeutic strategies targeting TAMs to enhance the efficacy of immune checkpoint inhibitor (ICI) in colorectal cancer.

DESIGN

The inhibitory effect of MS4A4A blockade alone or combined with ICI treatment on tumour growth was assessed using murine subcutaneous tumour or orthotopic transplanted models. The effect of MS4A4A blockade on the tumour immune microenvironment was assessed by flow cytometry and mass cytometry. RNA sequencing and western blot analysis were used to further explore the molecular mechanism by which MS4A4A promoted macrophages M2 polarisation.

RESULTS

MS4A4A is selectively expressed by TAMs in different types of tumours, and was associated with adverse clinical outcome in patients with cancer. In vivo inhibition of MS4A4A and anti-MS4A4A monoclonal antibody treatment both curb tumour growth and improve the effect of ICI therapy. MS4A4A blockade treatment reshaped the tumour immune microenvironment, resulting in reducing the infiltration of M2-TAMs and exhausted T cells, and increasing the infiltration of effector CD8+ T cells. Anti-MS4A4A plus anti-programmed cell death protein 1 (PD-1) therapy remained effective in large, treatment-resistant tumours and could induce complete regression when further combined with radiotherapy. Mechanistically, MS4A4A promoted M2 polarisation of macrophages by activating PI3K/AKT pathway and JAK/STAT6 pathway.

CONCLUSION

Targeting MS4A4A could enhance the ICI efficacy and represent a new anticancer immunotherapy.

KYNU as a Biomarker of Tumor-Associated Macrophages and Correlates with Immunosuppressive Microenvironment and Poor Prognosis in Gastric Cancer

Background

Kynureninase (KYNU) is a potential prognostic marker for various tumor types. However, no reports on the biological effects and prognostic value of KYNU in gastric cancer (GC) exist.

Methods

GC-associated single-cell RNA sequencing and bulk RNA sequencing (bulk-seq) data were obtained from the Gene Expression Omnibus and The Cancer Genome Atlas databases, respectively. The differential expression of KYNU between GC and normal gastric tissues was first analyzed based on the bulk-seq data, followed by an exploration of the relationship between KYNU and various clinicopathological features. The Kaplan-Meier survival and Cox regression analyses were performed to determine the prognostic value of KYNU. The relationship between KYNU expression and immune cell infiltration and immune checkpoints was also explored. The biological function of KYNU was further examined at the single-cell level, and in vitro experiments were performed to examine the effect of KYNU on GC cell proliferation and invasion.

Results

KYNU expression was significantly elevated in GC samples. Clinical features and survival analysis indicated that high KYNU expression was associated with poor clinical phenotypes and prognosis, whereas Cox analysis showed that KYNU was an independent risk factor for patients with GC. Notably, high expression of KYNU induced a poor immune microenvironment and contributed to the upregulation of immune checkpoints. KYNU-overexpressing macrophages drove GC progression through unique ligand-receptor pairs and transcription factors and were associated with adverse clinical phenotypes in GC. KYNU was overexpressed in GC cells in vitro, and KYNU knockout significantly inhibited GC cell proliferation and invasion.

Conclusion

High KYNU expression promotes an adverse immune microenvironment and low survival rates in GC. KYNU and KYNU-related macrophages may serve as novel molecular targets in the treatment of GC.

HER-2 Expression in Colorectal Cancer and Its Correlation with Immune Cell Infiltration

BACKGROUND

This study aimed to investigate the effect of increased HER-2 expression on tumor-infiltrating lymphocytes (TILs) and determine its impact on the prognosis of colorectal cancer (CRC) patients; Methods: HER-2, CD4, CD8, CD19, LY6G, CD56, CD68, CD11b, and EpCam expression in CRC tissues and adjacent paracancerous tissues were assessed using multiplex fluorescence immunohistochemical staining. The correlation between HER-2 expression and the number of TILs in CRC tissues was analyzed. Kaplan-Meier and Cox proportional hazards models were used to analyze survival outcomes; Results: The expression of HER-2 in tumor tissues was higher than that in paracancerous tissues (1.31 ± 0.45 vs. 0.86 ± 0.20, p < 0.05). Additionally, there was an increase in the numbers of CD4+, CD8+, CD19+, and CD68+ cells in CRC tissues (14.11 ± 1.10 vs. 3.40 ± 0.18, p < 0.005; 0.16 ± 0.12 vs. 0.04 ± 0.04, p < 0.005; 0.71 ± 0.46 vs. 0.25 ± 0.13, p < 0.0005; 0.27 ± 0.24 vs. 0.03 ± 0.11, p < 0.05). An increase in HER-2 expression was positively correlated with an increase in CD4, CD8, and CD19 (p < 0.0001). In HER-2-positive CRC tissues, CD68 expression was increased (0.80 ± 0.55 vs. 0.25 ± 0.22, p < 0.05). In HER-2-upregulated CRC tissues, CD4, CD8, CD19, CD68, CD11b, Ly6G, and CD56 expressions were elevated (0.70 ± 0.37 vs. 0.32 ± 0.17, p = 0.03; 0.22 ± 0.13 vs. 0.09 ± 0.06, p = 0.03; 0.31 ± 0.19 vs. 0.12 ± 0.08, p = 0.02; 1.05 ± 0.62 vs. 0.43 ± 0.21, p < 0.01; 1.34 ± 0.81 vs. 0.53 ± 0.23, p < 0.01; 0.50 ± 0.31 vs. 0.19 ± 0.10, p < 0.01; 1.26 ± 0.74 vs. 0.52 ± 0.24, p < 0.01). Furthermore, increased HER-2 expression was an independent risk factor for recurrence-free survival (RFS) in patients (p < 0.01, HR = 3.421); Conclusions: The increased expression of HER-2 and its relationship with immune cells will provide new insights for immunotherapy in CRC patients.

Control of immune cell function by the unfolded protein response

Initiating and maintaining optimal immune responses requires high levels of protein synthesis, folding, modification and trafficking in leukocytes, which are processes orchestrated by the endoplasmic reticulum. Importantly, diverse extracellular and intracellular conditions can compromise the protein-handling capacity of this organelle, inducing a state of 'endoplasmic reticulum stress' that activates the unfolded protein response (UPR). Emerging evidence shows that physiological or pathological activation of the UPR can have effects on immune cell survival, metabolism, function and fate. In this Review, we discuss the canonical role of the adaptive UPR in immune cells and how dysregulation of this pathway in leukocytes contributes to diverse pathologies such as cancer, autoimmunity and metabolic disorders. Furthermore, we provide an overview as to how pharmacological approaches that modulate the UPR could be harnessed to control or activate immune cell function in disease.

Pan-Cancer Identification of Prognostic-Associated Metabolic Pathways

Metabolic dysregulation has been reported involving in the clinical outcomes of multiple cancers. However, systematical identification of the impact of metabolic pathways on cancer prognosis is still lacking. Here, we performed a pan-cancer analysis of popular metabolic checkpoint genes and pathways with cancer prognosis by integrating information of clinical survival with gene expression and pathway activity in multiple cancer patients. By discarding the effects of age and sex, we revealed extensive and significant associations between the survival of cancer patients and the expression of metabolic checkpoint genes, as well as the activities of three primary metabolic pathways: amino acid metabolism, carbohydrate metabolism, lipid metabolism, and eight nonprimary metabolic pathways. Among multiple cancers, we found the survival of kidney renal clear cell carcinoma and low-grade glioma exhibit high metabolic dependence. Our work systematically assesses the impact of metabolic checkpoint genes and pathways on cancer prognosis, providing clues for further study of cancer diagnosis and therapy.

How the Unfolded Protein Response Is a Boon for Tumors and a Bane for the Immune System

The correct folding of proteins is essential for appropriate cell function and is tightly regulated within the endoplasmic reticulum (ER). Environmental challenges and cellular conditions disrupt ER homeostasis and induce ER stress, which adversely affect protein folding and activate the unfolded protein response (UPR). It is now becoming recognized that cancer cells can overcome survival challenges posed within the tumor microenvironment by activating the UPR. Furthermore, the UPR has also been found to impose detrimental effects on immune cells by inducing immunoinhibitory activity in both tumor-infiltrating innate and adaptive immune cells. This suggests that these signaling axes may be important therapeutic targets, resulting in multifaceted approaches to eradicating tumor cells. In this mini-review, we discuss the role of the UPR in driving tumor progression and modulating the immune system's ability to target cancer cells. Additionally, we highlight some of the key unanswered questions that may steer future UPR research.

Targeting XBP1 mRNA splicing sensitizes glioblastoma to chemotherapy

Glioblastoma (GBM) is the most frequent and deadly primary brain tumor in adults. Temozolomide (TMZ) is the standard systemic therapy in GBM but has limited and restricted efficacy. Better treatments are urgently needed. The role of endoplasmic reticulum stress (ER stress) is increasingly described in GBM pathophysiology. A key molecular mediator of ER stress, the spliced form of the transcription factor x-box binding protein 1 (XBP1s) may constitute a novel therapeutic target; here we report XBP1s expression and biological activity in GBM. Tumor samples from patients with GBM (n = 85) and low-grade glioma (n = 20) were analyzed by immunohistochemistry for XBP1s with digital quantification. XBP1s expression was significantly increased in GBM compared to low-grade gliomas. XBP1s mRNA showed upregulation by qPCR analysis in a panel of patient-derived GBM cell lines. Inhibition of XBP1 splicing using the small molecular inhibitor MKC-3946 significantly reduced GBM cell viability and potentiated the effect of TMZ in GBM cells, particularly in those with methylated O⁶-methylguanine-DNA methyl transferase gene promoter. GBM cells resistant to TMZ were also responsive to MKC-3946 and the long-term inhibitory effect of MKC-3946 was confirmed by colony formation assay. In conclusion, this data reveals that XBP1s is overexpressed in GBM and contributes to cancer cell growth. XBP1s warrants further investigation as a clinical biomarker and therapeutic target in GBM.

Integrated multi-omics profiling yields a clinically relevant molecular classification for esophageal squamous cell carcinoma

Integrated molecular analysis of human cancer has yielded molecular classification for precise management of cancer patients. Here, we analyzed the whole genomic, epigenomic, transcriptomic, and proteomic data of 155 esophageal squamous cell carcinomas (ESCCs). Multi-omics analysis led to the classification of ESCCs into four subtypes: cell cycle pathway activation, NRF2 oncogenic activation, immune suppression (IS), and immune modulation (IM). IS and IM cases were highly immune infiltrated but differed in the type and distribution of immune cells. IM cases showed better response to immune checkpoint blockade therapy than other subtypes in a clinical trial. We further developed a classifier with 28 features to identify the IM subtype, which predicted anti-PD-1 therapy response with 85.7% sensitivity and 90% specificity. These results emphasize the clinical value of unbiased molecular classification based on multi-omics data and have the potential to further improve the understanding and treatment of ESCC.

Sensitizing Tumors to Immune Checkpoint Blockage via STING Agonists Delivered by Tumor-Penetrating Neutrophil Cytopharmaceuticals

Immune checkpoint inhibitors (ICIs) have displayed potential efficacy in triple-negative breast cancer (TNBC) treatment, while only a minority of patients benefit from ICI therapy currently. Although activation of the innate immune stimulator of interferon genes (STING) pathway potentiates antitumor immunity and thus sensitizes tumors to ICIs, the efficient tumor penetration of STING agonists remains critically challenging. Herein, we prepare a tumor-penetrating neotype neutrophil cytopharmaceutical (NEs@STING-Mal-NP) with liposomal STING agonists conjugating on the surface of neutrophils, which is different from the typical neutrophil cytopharmaceutical that loads drugs inside the neutrophils. We show NEs@STING-Mal-NP that inherit the merits of neutrophils including proactive tumor vascular extravasation and tissue penetration significantly boost the tumor penetration of STING agonists. Moreover, the backpacked liposomal STING agonists can be released in response to hyaluronidase rich in the tumor environment, leading to enhanced uptake by tumor-infiltrating immune cells and tumor cells. Thus, NEs@STING-Mal-NP effectively activate the STING pathway and reinvigorate the tumor environment through converting macrophages and neutrophils to antitumor phenotypes, promoting the maturation of dendritic cells, and enhancing the infiltration and tumoricidal ability of T cells. Specifically, this cytopharmaceutical displays a significant inhibition on tumor growth and prolongs the survival of TNBC-bearing mice when combined with ICIs. We demonstrate that neutrophils serve as promising vehicles for delivering STING agonists throughout solid tumors and the developed neutrophil cytopharmaceuticals with backpacked STING agonists exhibit huge potential in boosting the immunotherapy of ICIs.

Platelets promote CRC by activating the C5a/C5aR1 axis via PSGL-1/JNK/STAT1 signaling in tumor-associated macrophages

Rationale: Platelets can influence the progression and prognosis of colorectal cancer (CRC) through multiple mechanisms, including crosstalk with tumor-associated macrophages (TAMs). However, the mechanisms underlying the crosstalk between platelets and TAMs remain unclear. The present study aimed to investigate the role of intratumoral platelets in regulating the function of TAMs and to identify the underlying mechanisms. Methods: The interaction of platelets with macrophages was assessed in the presence or absence of the indicated compounds in vivo. An azoxymethane/dextran sodium sulfate (AOM/DSS)-induced CRC mouse model was used to investigate the role of platelets in controlling CRC development. Multiplexed immunofluorescence staining, fluorescence-activated cell sorting (FACS), and RNA sequence analysis were used to examine the changes in TAMs. TAMs and bone marrow-derived macrophages (BMDMs) were treated with the indicated compounds or siRNA against specific targets, and the expression levels of signal transducer and activator of transcription 1 (STAT1), c-Jun N-terminal kinase (JNK), and P-selectin glycoprotein ligand-1 (PSGL-1) were measured by Western blotting. The mRNA expression levels of complement 5 (C5), complement 5a receptor 1 (C5ar1), Arginase 1 (Arg1) and Il10 were measured by real-time RT-PCR, and the complement 5a (C5a) concentration was measured by ELISA. The dual-luciferase reporter assay and ChIP assay were performed to examine the potential regulatory mechanisms of platelet induction of C5 transcription in TAMs. Results: In our study, we found that an increase in platelets exacerbated CRC development, while inhibiting platelet adhesion attenuated tumor growth. Platelets signal TAMs through P-selectin (CD62P) binding to PSGL-1 expressed on TAMs and activating the JNK/STAT1 pathway to induce the transcription of C5 and the release of C5a, shifting TAMs toward a protumor phenotype. Inhibiting the C5a/C5aR1 axis or PSGL-1 significantly reduced CRC growth. Conclusions: An increase in intratumoral platelets promoted CRC growth and metastasis by CD62P binding to PSGL-1 expressed on TAMs, leading to JNK/STAT1 signaling activation, which promoted C5 transcription and activated the C5a/C5aR1 axis in TAMs. Our study examined the mechanism of the crosstalk between platelets and TAMs to exacerbate CRC development and proposed a potential therapeutic strategy for CRC patients.

A novel regulator in cancer initiation and progression: long noncoding RNA SHNG9

Cancer has become the most common life-threatening disease in the world. Cancers presenting with advanced stages and metastasis show poor prognosis, even with the application of radiotherapy, surgery, chemotherapy and immunotherapy. It is of great importance to explore novel, efficient biomarkers and their internal mechanisms. Recently, it has been reported that long noncoding RNAs (lncRNAs) play important roles in tumor initiation and progression, influencing downstream mRNAs by interacting with miRNAs and functioning as sponges in competing endogenous RNA (ceRNA) networks. Small nucleolar RNA host gene 9 (SNHG9) binds with miRNAs, inducing miRNA downregulation. The downregulated miRNAs enhance downstream target gene expression via ceRNA networks. Dysregulation of SNHG9 is widely observed in tumors and is associated with clinical prognosis features, which makes it a valuable target for cancer biomarkers and therapeutics. Dysregulated SNHG9 in tumor cells also functions in tumor proliferation, colony formation, migration, invasion and inhibition of apoptosis and tumor cell metabolism. This systematic review of SNHG9 in tumors provides new perspectives on cancer diagnosis and treatment.

MUC13-miRNA-4647 axis in colorectal cancer: Prospects to identifications of risk factors and clinical outcomes

MUC13, a transmembrane mucin glycoprotein, is overexpressed in colorectal cancer (CRC), however, its regulation and functions are not fully understood. It has been shown that MUC13 protects colonic epithelial cells from apoptosis. Therefore, studying MUC13 and MUC13-regulated pathways may reveal promising therapeutic approaches for CRC treatment. Growing evidence suggests that microRNAs (miRs) are involved in the development and progression of CRC. In the present study, the MUC13-miR-4647 axis was addressed in association with survival of patients. miR-4647 is predicted in silico to bind to the MUC13 gene and was analyzed by RT-qPCR in 187 tumors and their adjacent non-malignant mucosa of patients with CRC. The impact of previously mentioned genes on survival and migration abilities of cancer cells was validated in vitro. Significantly upregulated MUC13 (P=0.02) in was observed tumor tissues compared with non-malignant adjacent mucosa, while miR-4647 (P=0.05) showed an opposite trend. Higher expression levels of MUC13 (log-rank P=0.05) were associated with worse patient's survival. The ectopic overexpression of studied miR resulted in decreased migratory abilities and worse survival of cells. Attenuated MUC13 expression levels confirmed the suppression of colony forming of CRC cells. In summary, the present data suggested the essential role of MUC13-miR-4647 in patients' survival, and this axis may serve as a novel therapeutic target. It is anticipated MUC13 may hold significant potential in the screening, diagnosis and treatment of CRC.

Age-related macrophage alterations are associated with carcinogenesis of colorectal cancer

Older age is a major risk factor for colorectal cancer. Macrophage is one of the most abundant immune cell types infiltrated in colorectal cancer, but the contribution of macrophages in elder tumor microenvironment is far from clear. In this study, we first detected the expression of CD206, CD68 in colorectal cancer tissues by multiplex fluorescence immunohistochemical staining. The infiltration of CD68+/CD206+ cells in tumor tissues from old patients was higher than those from young patients. When mixed with CT26 cells, both young and aged TAMs enhanced tumor growth of CT26 cells, but CT26 mixed with aged TAMs form larger tumors compared with young TAMs. CT26 formed more and larger tumors in the abdominal cavity of aged mice compared with young. Total macrophage infiltration and the CD206+ macrophages infiltration were both higher in aged mice compared with young mice. The expression signatures of tumor-associated macrophages altered with ageing and p-NF-κB translocation to nucleus was more significant in TAMs from aged mice compared with young. Our results showed that infiltration of macrophages in colorectal cancer tissues increased with ageing. Macrophages from aged host were more likely to polarize to pro-tumor phenotype, and more powerful in promoting tumor cell proliferation.

Curcumin Reprograms TAMs from a Protumor Phenotype towards an Antitumor Phenotype via Inhibiting MAO-A/STAT6 Pathway

M1 phenotype macrophages have anticancer characteristics, whereas M2 phenotype macrophages promote tumor growth and metastasis. A higher M1/M2 ratio, therefore, has a beneficial effect on the tumor immune microenvironment, thereby inhibiting tumor growth. The natural alkaloid curcumin is found to have anticancer properties. However, the mechanism remains unclear. In this study, a cell co-culture system and M2 macrophage model were used to evaluate the effects of curcumin on tumor-associated macrophage (TAM) phenotypes. Our results demonstrate that curcumin reprogrammed the M2 macrophages by reducing the level of anti-inflammatory cytokines (TGF-β, Arg-1, and IL-10) and an M2 surface marker (CD206) induced by Cal27 cells or IL-4, as well as upregulating proinflammatory cytokines (TNF-α, iNOS, and IL-6) and an M1 surface marker (CD86). The in vitro assays suggested that curcumin treatment suppressed the migration and invasion of the Cal27 cells induced by the M2-like macrophages. Mechanistically, the repolarization of TAMs may be attributed to the inhibition of monoamine oxidase A (MAO-A)/STAT6 signaling after curcumin treatment. Collectively, our results show that the anticancer effects of curcumin could be explained by reprogramming TAMs from a protumor phenotype towards an antitumor phenotype.

Decoding endoplasmic reticulum stress signals in cancer cells and antitumor immunity

The tumor microenvironment (TME) provokes endoplasmic reticulum (ER) stress in malignant cells and infiltrating immune populations. Sensing and responding to ER stress is coordinated by the unfolded protein response (UPR), an integrated signaling pathway governed by three ER stress sensors: activating transcription factor (ATF6), inositol-requiring enzyme 1α (IRE1α), and protein kinase R (PKR)-like ER kinase (PERK). Persistent UPR activation modulates malignant progression, tumor growth, metastasis, and protective antitumor immunity. Hence, therapies targeting ER stress signaling can be harnessed to elicit direct tumor killing and concomitant anticancer immunity. We highlight recent findings on the role of the ER stress responses in onco-immunology, with an emphasis on genetic vulnerabilities that render tumors highly sensitive to therapeutic UPR modulation.

Flavonoids regulate tumor-associated macrophages - From structure-activity relationship to clinical potential (Review)

In recent years, the strategy for tumor therapy has changed from focusing on the direct killing effect of different types of therapeutic agents on cancer cells to the new mainstream of multi-mode and -pathway combined interventions in the microenvironment of the developing tumor. Flavonoids, with unique tricyclic structures, have diverse and extensive immunomodulatory and anti-cancer activities in the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) are the most abundant immunosuppressive cells in the TME. The regulation of macrophages to fight cancer is a promising immunotherapeutic strategy. This study covers the most comprehensive cognition of flavonoids in regulating TAMs so far. Far more than a simple list of studies, we try to dig out evidence of crosstalk at the molecular level between flavonoids and TAMs from literature, in order to discuss the most relevant chemical structure and its possible relationship with the multimodal pharmacological activity, as well as systematically build a structure-activity relationship between flavonoids and TAMs. Additionally, we point out the advantages of the macro-control of flavonoids in the TME and discuss the potential clinical implications as well as areas for future research of flavonoids in regulating TAMs. These results will provide hopeful directions for the research of antitumor drugs, while providing new ideas for the pharmaceutical industry to develop more effective forms of flavonoids.

The role and therapeutic implication of endoplasmic reticulum stress in inflammatory cancer transformation

Endoplasmic reticulum (ER) stress occurs when proteins are affected by various factors, fail to fold properly into higher structures and accumulate in the lumen of the ER, which activates the unfolded protein response (UPR) to restore normal cellular function or induce apoptosis as a self-protective mechanism. However, a growing number of studies have shown that the three branches of ER stress and the UPR can mediate inflammation and cancer development by interacting with inflammatory transformation-related signaling pathways. Targeting the UPR, especially the use of small molecules that target the active sites of the enzymes IRE1α and PERK and BIP/GRP78 inhibitors are potential strategies for treating tumors and have shown promising results in some tumor models. Therefore, in this review, we summarize the progress of ER stress/UPR research and the signaling pathways associated with inflammatory cancer transformation, provide an in-depth description of the mechanisms of these pathways, and outline strategies in the field of UPR biology in tumor therapy to provide new ideas for the mechanisms of inflammatory cancer transformation and tumor-related treatment.

Immunosuppressive Signaling Pathways as Targeted Cancer Therapies

Immune response has been shown to play an important role in defining patient prognosis and response to cancer treatment. Tumor-induced immunosuppression encouraged the recent development of new chemotherapeutic agents that assists in the augmentation of immune responses. Molecular mechanisms that tumors use to evade immunosurveillance are attributed to their ability to alter antigen processing/presentation pathways and the tumor microenvironment. Cancer cells take advantage of normal molecular and immunoregulatory machinery to survive and thrive. Cancer cells constantly adjust their genetic makeup using several mechanisms such as nucleotide excision repair as well as microsatellite and chromosomal instability, thus giving rise to new variants with reduced immunogenicity and the ability to continue to grow without restrictions. This review will focus on the central molecular signaling pathways involved in immunosuppressive cells and briefly discuss how cancer cells evade immunosurveillance by manipulating antigen processing cells and related proteins. Secondly, the review will discuss how these pathways can be utilized for the implementation of precision medicine and deciphering drug resistance.

Immunosuppressive Signaling Pathways as Targeted Cancer Therapies

Immune response has been shown to play an important role in defining patient prognosis and response to cancer treatment. Tumor-induced immunosuppression encouraged the recent development of new chemotherapeutic agents that assists in the augmentation of immune responses. Molecular mechanisms that tumors use to evade immunosurveillance are attributed to their ability to alter antigen processing/presentation pathways and the tumor microenvironment. Cancer cells take advantage of normal molecular and immunoregulatory machinery to survive and thrive. Cancer cells constantly adjust their genetic makeup using several mechanisms such as nucleotide excision repair as well as microsatellite and chromosomal instability, thus giving rise to new variants with reduced immunogenicity and the ability to continue to grow without restrictions. This review will focus on the central molecular signaling pathways involved in immunosuppressive cells and briefly discuss how cancer cells evade immunosurveillance by manipulating antigen processing cells and related proteins. Secondly, the review will discuss how these pathways can be utilized for the implementation of precision medicine and deciphering drug resistance.