Adipose-Derived exosome from Diet-Induced-Obese mouse attenuates LPS-Induced acute lung injury by inhibiting inflammation and Apoptosis: In vivo and in silico insight.

BACKGROUND: Acute lung injury (ALI) is a severe clinical condition in the intensive care units, and obesity is a high risk of ALI. Paradoxically, obese ALI patients had better prognosis than non-obese patients, and the mechanism remains largely unknown. METHODS: Mouse models of ALI and diet-induced-obesity (DIO) were used to investigate the effect of exosomes derived from adipose tissue. The adipose-derived exosomes (ADEs) were isolated by ultracentrifugation, and the role of exosomal miRNAs in the ALI was studied. RESULTS: Compared with ADEs of control mice (C-Exo), ADEs of DIO mice (D-Exo) increased survival rate and mitigated pulmonary lesions of ALI mice. GO and KEGG analyses showed that the target genes of 40 differentially expressed miRNAs between D-Exo and C-Exo were mainly involved with inflammation, apoptosis and cell cycle. Furthermore, the D-Exo treatment significantly decreased Ly6G+ cell infiltration, down-regulated levels of pro-inflammatory cytokines (IL-6, IL-12, TNF-α, MCP-1) and chemokines (IL-8 and MIP-2), reduced pulmonary apoptosis and arrest at G0G1 phase (P < 0.01). And the protective effects of D-Exo were better than those of C-Exo (P < 0.05). Compared with the C-Exo mice, the levels of miR-16-5p and miR-335-3p in the D-Exo mice were significantly up-regulated (P < 0.05), and the expressions of IKBKB and TNFSF10, respective target of miR-16-5p and miR-335-3p by bioinformatic analysis, were significantly down-regulated in the D-Exo mice (P < 0.05). CONCLUSIONS: Exosomes derived from adipose tissue of DIO mice are potent to attenuate LPS-induced ALI, which could be contributed by exosome-carried miRNAs. Our data shed light on the interaction between obesity and ALI.

Metformin suppresses gastric cancer progression by disrupting the STAT1-PRMT1 axis.

Gastric cancer (GC) is a common form of cancer and the leading cause of cancer-related deaths worldwide. Chemotherapy is the primary treatment for patients with unresectable or partially resectable GC. However, its adverse effects and chemoresistance greatly restrict its applicability and efficacy. Although HER2-targeted therapy and immunotherapy have been successfully used for GC treatment, their beneficial population is limited. To expand the range of cancer treatments, drug repurposing has emerged as a promising strategy. In this study, we evaluated the potential of Metformin, an oral anti-hyperglycemic agent, to suppress GC progression both in vivo and in vitro. Functional investigations showed that Metformin significantly inhibits GC proliferation and migration. Furthermore, we discovered that Metformin bound and disrupted STAT1 phosphorylation, inhibiting PRMT1 expression and consequently GC progression. In conclusion, our study not only provides further evidence for the anti-GC role of Metformin but also identifies the direct target mediating the tumor-inhibitory effects of Metformin in GC.

Overexpression of LINC00853 enhances tumorigenesis and metastasis of gastric cancer.

Gastric cancer (GC) is a rising global health issue, with increasing incidence and mortality rates. The pathogenesis of GC is highly complex and involves a combination of genetic and environmental factors. Therefore, identifying new genes and pathways that contribute to the development and progression of GC is essential for improving diagnosis and treatment outcomes. Long noncoding RNAs (lncRNAs) have recently emerged as a promising area of research in understanding the molecular mechanisms underlying various cancers, including GC. These RNA molecules are longer than 200 nucleotides and do not code proteins. Although initially considered "junk DNA", lncRNAs have been demonstrated to play significant roles in various biological processes, including cell proliferation, differentiation, and apoptosis, as well as in the pathogenesis of various cancers. In this study, we screened clinical specimens for a novel lncRNA, LINC00853, which showed high expression in GC tissues and promoted the proliferation, migration, and invasion of GC cells. Furthermore, in vivo experiments confirmed its ability to facilitate the growth and metastasis of GC. These results suggest that LINC00853 plays a crucial role in the development and progression of GC.

Reprogramming tumor-associated macrophages by a dually targeted milk exosome system as a potent monotherapy for cancer.

Tumor-associated macrophages (TAMs) play a key role in inducing an immunosuppressive tumor microenvironment (TME) and cancer immune escape. We previously revealed that PDL1 (a key immune checkpoint) was upregulated in TAMs and induced M2 polarization, highlighting PDL1 in TAMs as a promising cancer therapeutic target. In this study, we developed an engineered milk exosome (mExo) system decorated with M2pep (an M2 macrophage binding peptide) and 7D12 (an anti-EGFR nanobody) (7D12-mExo-M2pep-siPDL1) to specifically deliver siPDL1 into M2 TAMs. A series of in vitro and in vivo assays showed that the dually targeted engineered mExos efficiently delivered siPDL1 into M2 TAMs and repolarized them into M1 macrophages, restoring CD8+ T cell immune activity and remodeling TME. Importantly, systemically administered 7D12-mExo-M2pep-siPDL1 showed efficient single-agent antitumor activity, resulting in nearly 90% tumor growth inhibition in a mouse model of orthotopic epidermal growth factor receptor (EGFR) cancer. Collectively, our study indicates that PDL1 is a promising target for TAM-based cancer immunotherapy, and our engineered mExo-based nanomedicine represents a novel tool for specifically targeting M2 TAMs, distinguishing this novel therapeutic method from other TAM-targeting therapies and highlighting its promising clinical potential.

LINC01852 inhibits the tumorigenesis and chemoresistance in colorectal cancer by suppressing SRSF5-mediated alternative splicing of PKM.

BACKGROUND: Colorectal cancer (CRC) is a major cause of cancer-related deaths worldwide, and chemoresistance is a major obstacle in its treatment. Despite advances in therapy, the molecular mechanism underlying chemoresistance in CRC is not fully understood. Recent studies have implicated the key roles of long noncoding RNAs (lncRNAs) in the regulation of CRC chemoresistance. METHODS: In this study, we investigated the role of the lncRNA LINC01852 in CRC chemoresistance. LINC01852 expression was evaluated in multiple CRC cohorts using quantitative reverse transcription PCR. We conducted in vitro and in vivo functional experiments using cell culture and mouse models. RNA pull-down, RNA immunoprecipitation, chromatin immunoprecipitation, and dual luciferase assays were used to investigate the molecular mechanism of LINC01852 in CRC. RESULTS: Our findings revealed that a lncRNA with tumor-inhibiting properties, LINC01852, was downregulated in CRC and inhibited cell proliferation and chemoresistance both in vitro and in vivo. Further mechanistic investigations revealed that LINC01852 increases TRIM72-mediated ubiquitination and degradation of SRSF5, inhibiting SRSF5-mediated alternative splicing of PKM and thereby decreasing the production of PKM2. Overexpression of LINC01852 induces a metabolic switch from aerobic glycolysis to oxidative phosphorylation, which attenuates the chemoresistance of CRC cells by inhibiting PKM2-mediated glycolysis. CONCLUSIONS: Our results demonstrate that LINC01852 plays an important role in repressing CRC malignancy and chemoresistance by regulating SRSF5-mediated alternative splicing of PKM, and that targeting the LINC01852/TRIM72/SRSF5/PKM2 signaling axis may represent a potential therapeutic strategy for CRC.

SIRT5-mediated ME2 desuccinylation promotes cancer growth by enhancing mitochondrial respiration.

Mitochondrial malic enzyme 2 (ME2), which catalyzes the conversion of malate to pyruvate, is frequently upregulated during tumorigenesis and is a potential target for cancer therapy. However, the regulatory mechanism underlying ME2 activity is largely unknown. In this study, we demonstrate that ME2 is highly expressed in human colorectal cancer (CRC) tissues, and that ME2 knockdown inhibits the proliferation of CRC cells. Furthermore, we reveal that ME2 is succinylated and identify Sirtuins 5 (SIRT5) as an ME2 desuccinylase. Glutamine deprivation directly enhances the interaction of SIRT5 with ME2 and thus promotes SIRT5-mediated desuccinylation of ME2 at lysine 346, activating ME2 enzymatic activity. Activated ME2 significantly enhances mitochondrial respiration, thereby counteracting the effects of glutamine deprivation and supporting cell proliferation and tumorigenesis. Additionally, the levels of succinylated ME2 at K346 and SIRT5 in CRC tissues, which are negatively correlated, are associated with patient prognosis. These observations suggest that SIRT5-catalyzed ME2 desuccinylation is a key signaling event through which cancer cells maintain mitochondrial respiration and promote CRC progression under glutamine deficiency conditions, offering the possibility of targeting SIRT5-mediated ME2 desuccinylation for CRC treatment.

An off-the-shelf small extracellular vesicle nanomedicine for tumor targeting therapy.

Small extracellular vesicles (sEVs) have shown excellent prospects as drug delivery systems for cancer therapy. However, the inherent non-targeting and short blood circulation characteristics severely restrict their practical applications as a delivery system. In addition, post-encapsulating drugs into sEVs also remains challenging. Here, we constructed an engineered cell line that secreted multifunctional sEVs (termed NBsEV204) with 7D12 (an anti-EGFR nanobody) and hCD47 decorations on their surface, as well as high levels of miR-204-5p encapsulation. NBsEV204 exhibited extended blood circulation and improved macrophage-mediated phagocytosis of tumor cells by blocking CD47 signaling. Importantly, NBsEV204 specifically targeted EGFR+ tumor cells and showed robust tumor-suppressive effects both in vitro and in vivo. Overall, this study provides a convenient and feasible method to produce off-the-shelf anticancer sEV nanomedicine, which exhibits tremendous potential for clinical translation.

KDM4C-mediated senescence defense is a targetable vulnerability in gastric cancer harboring TP53 mutations.

BACKGROUND: Gastric cancer patients harboring a TP53 mutation exhibit a more aggressive and chemoresistant phenotype. Unfortunately, efforts to identify the vulnerabilities to overcome these aggressive malignancies have made minimal progress in recent years. Therefore, there is an urgent need to explore the novel therapeutic strategies for this subclass. Histone methylation modulators are critical epigenetic targets for cancer therapies that help maintain the malignancies of cancers harboring TP53 mutations and senescence evasion. Triggering senescence is now considered to benefit multiple cancer therapies. Furthermore, senescence-based "one-two punch" therapy was validated in clinical trials. Therefore, we hypothesized that screening epigenetic modulators might help identify a novel vulnerability to trigger senescence in gastric cancer harboring TP53 mutations. RESULTS: We developed a novel efficient approach to identify senescence inducers by sequentially treating cells with drug candidates and senolytic agents. Based on this, we demonstrated that QC6352 (a selective KDM4C inhibitor) efficiently triggered cellular senescence in gastric cancer harboring TP53 mutations. More importantly, the "one-two punch' therapy consisting of QC6352 and SSK1 eliminates tumor cells harboring TP53 mutations. This finding highlights a potential therapeutic strategy for the aggressive subgroup of gastric cancer. Besides, the functions of QC6352 were totally unknown. We demonstrated that QC6352 might possess far more powerful anti-tumor capacities compared to the traditional genotoxic drugs, 5-Fu and Oxaliplatin. CONCLUSIONS: This initial investigation to identify a senescence inducer revealed that QC6352 triggers senescence in gastric cancer cells harboring TP53 mutations by regulating the SP1/CDK2 axis through suppressing KDM4C. QC6352 and senolytic agent-SSK1 represent a novel 'one-two punch' therapeutic strategy for the more malignant gastric cancer subtypes.

ELOA promotes tumor growth and metastasis by activating RBP1 in gastric cancer.

BACKGROUND: Elongin A (ELOA), our previous work revealed, serves as a novel tumor suppressor in colorectal cancer. However, the function and mechanism of ELOA in other cancer types, including gastric cancer (GC), remain to be elucidated. METHODS: The expression of ELOA was measured by quantitative reverse transcription-polymerase chain reaction and western blot. The effects of ELOA on GC growth and metastasis were assessed through a series of in-vitro and in-vivo assays. Furthermore, the potential mechanism of ELOA was revealed by RNA sequencing, dual luciferase reporter assay, chromatin immunoprecipitation, and rescue experiments in GC. RESULTS: We uncovered increased expression of ELOA in GC tissues compared with paired normal tissues via bioinformatic analyses and our sample detection. Enhanced ELOA expression in GC tissues was obviously correlated with poor tumor differentiation, lymph node metastasis, advanced tumor stage, and a poor prognosis. A series of functional experiments showed that ELOA promoted the proliferation and metastasis of GC. Mechanistically, we revealed that the decreased levels of miR-490-3p caused the upregulation of ELOA in GC. Both RNA-seq and ChIP assays revealed that ELOA transcriptionally activated retinol-binding protein 1 (RBP1) by binding to its promotor. Furthermore, specific knockdown of RBP1 reduced the tumor-promoting ability of ELOA in GC cells. CONCLUSIONS: In summary, our findings demonstrate that ELOA exerts oncogenic properties by activating RBP1 expression, providing the basis for a promising therapeutic target in GC.

Obesity Paradox in Lung Diseases: What Explains It?

BACKGROUND: Obesity is a globally increasing health problem that impacts multiple organ systems and a potentially modifiable risk factor for many diseases. Obesity has a significant impact on lung function and is strongly linked to the pathophysiology that contributes to lung diseases. On the other hand, reports have emerged that obesity is associated with a better prognosis than for normal weight individuals in some lung diseases, including pneumonia, acute lung injury/acute respiratory distress syndrome, chronic obstructive pulmonary disease, and lung cancer. The lesser mortality and better prognosis in patients with obesity is known as obesity paradox. While obesity paradox is both recognized and disputed in epidemiological studies, recent research has suggested possible mechanisms. SUMMARY: In this review, we attempted to explain and summarize these factors and mechanisms, including immune response, pulmonary fibrosis, lung function, microbiota, fat and muscle reserves, which are significantly altered by obesity and may contribute to the obesity paradox in lung diseases. We also discuss contrary literature that attributes the "obesity paradox" to confounding. KEY MESSAGES: The review will illustrate the possible role of obesity in the prognosis or course of lung diseases, leading to a better understanding of the obesity paradox and provide hints for further basic and clinical research in lung diseases.

Acetylation of aldehyde dehydrogenase ALDH1L2 regulates cellular redox balance and the chemosensitivity of colorectal cancer to 5-fluorouracil.

Folate-mediated one-carbon metabolism (FOCM) is crucial in sustaining rapid proliferation and survival of cancer cells. The folate cycle depends on a series of key cellular enzymes, including aldehyde dehydrogenase 1 family member L2 (ALDH1L2) that is usually overexpressed in cancer cells, but the regulatory mechanism of ALDH1L2 remains undefined. In this study, we observed the significant overexpression of ALDH1L2 in colorectal cancer (CRC) tissues, which is associated with poor prognosis. Mechanistically, we identified that the acetylation of ALDH1L2 at the K70 site is an important regulatory mechanism inhibiting the enzymatic activity of ALDH1L2 and disturbing cellular redox balance. Moreover, we revealed that sirtuins 3 (SIRT3) directly binds and deacetylates ALDH1L2 to increase its activity. Interestingly, the chemotherapeutic agent 5-fluorouracil (5-Fu) inhibits the expression of SIRT3 and increases the acetylation levels of ALDH1L2 in colorectal cancer cells. 5-Fu-induced ALDH1L2 acetylation sufficiently inhibits its enzymatic activity and the production of NADPH and GSH, thereby leading to oxidative stress-induced apoptosis and suppressing tumor growth in mice. Furthermore, the K70Q mutant of ALDH1L2 sensitizes cancer cells to 5-Fu both in vitro and in vivo through perturbing cellular redox and serine metabolism. Our findings reveal an unknown 5-Fu-SIRT3-ALDH1L2 axis regulating redox homeostasis, and suggest that targeting ALDH1L2 is a promising therapeutic strategy to sensitize tumor cells to chemotherapeutic agents.

SNHG15 promotes chemoresistance and glycolysis in colorectal cancer.

Long noncoding RNAs (lncRNAs) play an important role in tumor progression. Small nucleolar RNA host gene 15 (SNHG15) is a lncRNA that has been confirmed to play an oncogenic role in multiple cancer types. However, its role in glycolysis and chemoresistance in colorectal cancer (CRC) is unclear. The expression of SNHG15 in CRC was analyzed using data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases by bioinformatics methods. Cell Counting Kit-8 (CCK-8) and colony formation assays were used to evaluate cell viability. Cell sensitivity to 5-fluorouracil (5-FU) was detected by CCK-8. Glucose absorption and lactate production were used to evaluate the impact of SNHG15 on glycolysis. RNA-seq, real-time fluorescence quantitative reverse transcription PCR (RT-qPCR) and Western blotting (WB) were used to reveal the potential molecular mechanism of SNHG15 in CRC. SNHG15 was upregulated in CRC tissues compared with paired noncancerous tissues. Ectopic SNHG15 expression increased proliferation, 5-FU chemoresistance, and glycolysis in CRC cells. In contrast, SNHG15 knockdown inhibited CRC proliferation, 5-FU chemoresistance and glycolysis. Multiple pathways, including apoptosis and glycolysis, were potentially regulated by SNHG15 based on RNA-seq and pathway enrichment analyses. RT-qPCR and WB experiments confirmed that SNHG15 promoted the expression of TYMS, BCL2, GLUT1 and PKM2 in CRC cells. In conclusion, SNHG15 promotes 5-FU chemoresistance and glycolysis in CRC by potentially regulating the expression of TYMS, BCL2, GLUT1 and PKM2 and appears to be a new target for cancer therapy.

Up-regulation of STRA6 predicts poor prognosis and contributes to oxaliplatin resistance in colorectal cancer.

Signaling receptor and transporter of retinol STRA6 (STRA6) plays a primary role in transporting retinol. Several studies have reported that STRA6 is involved in several pathways related to tumorigenesis and progression. However, the exact functions and mechanisms of STRA6 in colorectal cancer (CRC) remain unclear. In our work, STRA6 was highly up-regulated in CRC and promoted the proliferation of CRC cells. Additionally, we discovered that STRA6 suppresses apoptosis partly by controlling BCL2 expression, which in turn causes CRC to become resistant to LOHP treatment. Our study demonstrates that STRA6 is a potential prognostic factor and oncogene in CRC by promoting CRC growth and chemoresistance.

Gamma-Aminobutyric Acid Type A Receptor Subunit Pi is a potential chemoresistance regulator in colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is one of the cancers with high morbidity and mortality worldwide. Chemotherapy is commonly used for metastatic or more advanced CRC. The mechanism of CRC chemoresistance is still under active investigation. Therefore, we identify and validate differentially expressed genes (DEGs) between oxaliplatin/5-FU resistant and sensitive CRC cells. METHODS AND RESULTS: Three datasets of colorectal cancer patients (GSE28691, GSE81006, and GSE77932) from the Gene Expression Omnibus (GEO) database were analyzed and volcano plots for DEGs were generated using the GEO2R tool. The intersection of three GEO datasets showed that GABRP was significantly upregulated in chemo-resistant CRC cells or patients with an adjusted p-value less than 0.01. The potential protein-protein interaction (PPI) network with GABRP was analyzed by the Search Tool for the Retrieval of Interaction Gene/Proteins (STRING) website. The PPI network predicted ANKRD66, CLINT1, HAP1, PLCL1, GABARPAP, GABARAPL1, NSF, GABARAPL2, TRAK2, and CLIC3 had a high likelihood to interact with GABRP. Especially, GABARAP, GABARAPL1, ANKRD66, CLINT1, and CLIC3 were enriched as the most possibly associated proteins with GABRP among the networks. GABRP was significantly more expressed in both oxaliplatin/5-FU resistant CRC cells than in those counterpart sensitive CRC cells using quantitative PCR (qPCR) analysis. Consistently, TCGA, Oncomine, and Human Protein Atlas (HPA) databases confirmed that higher expression of GABRP was robustly found in CRC patients than those in other various cancer types or normal colon tissues. CONCLUSION: We identify GABRP as a promising drug target to mediate oxaliplatin or 5-FU resistance in CRC. It provided the theoretical basis and potential clinical value for CRC patients.

Long noncoding RNA DLGAP1-AS2 promotes tumorigenesis and metastasis by regulating the Trim21/ELOA/LHPP axis in colorectal cancer.

BACKGROUND: Long noncoding RNAs (lncRNAs) have driven research focused on their effects as oncogenes or tumor suppressors involved in carcinogenesis. However, the functions and mechanisms of most lncRNAs in colorectal cancer (CRC) remain unclear. METHODS: The expression of DLGAP1-AS2 was assessed by quantitative RT-PCR in multiple CRC cohorts. The impacts of DLGAP1-AS2 on CRC growth and metastasis were evaluated by a series of in vitro and in vivo assays. Furthermore, the underlying mechanism of DLGAP1-AS2 in CRC was revealed by RNA pull down, RNA immunoprecipitation, RNA sequencing, luciferase assays, chromatin immunoprecipitation, and rescue experiments. RESULTS: We discovered that DLGAP1-AS2 promoted CRC tumorigenesis and metastasis by physically interacting with Elongin A (ELOA) and inhibiting its protein stability by promoting tripartite motif containing 21 (Trim21)-mediated ubiquitination modification and degradation of ELOA. In particular, we revealed that DLGAP1-AS2 decreases phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) expression by inhibiting ELOA-mediated transcriptional activating of LHPP and thus blocking LHPP-dependent suppression of the AKT signaling pathway. In addition, we also demonstrated that DLGAP1-AS2 was bound and stabilized by cleavage and polyadenylation specificity factor (CPSF2) and cleavage stimulation factor (CSTF3). CONCLUSIONS: The discovery of DLGAP1-AS2, a promising prognostic biomarker, reveals a new dimension into the molecular pathogenesis of CRC and provides a prospective treatment target for this disease.

Hyaluronic Acid-Coated Bovine Milk Exosomes for Achieving Tumor-Specific Intracellular Delivery of miRNA-204.

Cell type-specific drug delivery is a straightforward strategy to achieve targeted cancer therapy and reduce side effects. Hyaluronic acid (HA), an U.S. Food and Drug Administration (FDA)-approved biocompatible carbohydrate polymer, has been extensively employed as a targeting ligand for a drug delivery system due to its natural ability to bind to tumor cells overexpressing cluster of differentiation 44 (CD44) receptors. Here, we report the preparation and antitumor efficacy of HA-coated bovine milk exosomes (HA-mExo) for tumor-specific delivery of microRNA-204-5p mimics (miR-204). The exosome-based delivery formulation was prepared with miR-204 encapsulated inside the lumen and HA displayed outside the membrane. The resultant formulation of HA-mExo-miR204 was able to specifically target CD44-positive cancer cells, with a concomitant increase in the intracellular uptake of miR-204. Compared to the uncoated mExo-miR204 formulation, HA-mExo-miR204 showed significantly increased antitumor efficacy both in vitro and in vivo. Importantly, HA-mExo-miR204 showed excellent biocompatibility and did not cause significant systemic toxicity. Given that both HA and bovine milk exosomes are low-cost and highly accessible biogenic materials with broad biomedical applications, HA-decorated bovine milk exosomes can be proven to be a practical drug delivery system of RNA drugs for targeted cancer therapy.

A novel high-risk subpopulation identified by CTSL and ZBTB7B in gastric cancer.

BACKGROUND: Gastric cancer (GC) is characterised by a heterogeneous tumour microenvironment (TME) that is closely associated with the response to treatment, especially immunotherapies. However, most previous GC molecular subtyping systems need complex gene signatures and examination methods, restricting their clinical applications. Thus, we developed a new TME-based molecular subtype using only two genes. METHODS: Nine independent GC cohorts at the tissue- or single-cell level with more than 2000 patients were used in this study, including data we examined by single-cell sequencing, quantitative RT-PCR and immunochemistry/immunofluorescence staining. Nine different methods, five existing molecular subtypes and a series of signatures were used to evaluate the TME and molecular characteristics of GC. RESULTS: We established a CTSL/ZBTB7B subtyping system and uncovered the novel CTSLHighZBTB7BLow high-risk subgroup, but characterised by relative higher immune cell infiltration and lower tumour purity. This subgroup demonstrate higher levels of immune checkpoints and more enrichment of cancer-related pathways compared with other cases. CONCLUSIONS: We identified a high-risk subpopulation with unique TME features based on expressions of CTSL and ZBTB7B, suggesting a counterbalancing phenotype between immunostimulatory and immunosuppressive mechanisms. This subtyping system could be used to select treatment and management strategies for GC.

Colorectal Cancer-Derived Small Extracellular Vesicles Promote Tumor Immune Evasion by Upregulating PD-L1 Expression in Tumor-Associated Macrophages.

Tumor-associated macrophages (TAMs) are one of the most abundant cell types in colorectal cancer (CRC) tumor microenvironment (TME). Recent studies observed complicated "cross-talks" between cancer cells and macrophages in TME. However, the underlying mechanisms are still poorly elucidated. Here, PD-L1 levels are very low in CRC cells but highly abundant in TAMs, and a specific PD-L1+CD206+ macrophage subpopulation are identified, which is induced by tumor cells and associated with a poor prognosis. Mechanistic investigations reveal that CRC cells can secrete small extracellular vesicles (sEVs) taken up by macrophages that induce M2 like polarization and PD-L1 expression, resulting in increased PD-L1+CD206+ macrophage abundance and decreased T cell activity in CRC TME. sEV-derived miR-21-5p and miR-200a are identified as key signaling molecules mediating the regulatory effects of CRC on macrophages. Further studies reveal that CRC-derived miR-21-5p and miR-200a synergistically induces macrophage M2 like polarization and PD-L1 expression by regulating the PTEN/AKT and SCOS1/STAT1 pathways, resulting in decreased CD8+ T cell activity and increased tumor growth. This study suggests that inhibiting the secretion of specific sEV-miRNAs from CRC and targeting PD-L1 in TAMs may serve as novel methods for CRC treatment as well as a sensitization method for anti-PD-L1 therapy in CRC.

SNHG17 promotes colorectal tumorigenesis and metastasis via regulating Trim23-PES1 axis and miR-339-5p-FOSL2-SNHG17 positive feedback loop.

BACKGROUND: Small nucleolar RNA host gene (SNHG) long noncoding RNAs (lncRNAs) are frequently dysregulated in human cancers and involved in tumorigenesis and progression. SNHG17 has been reported as a candidate oncogene in several cancer types, however, its regulatory role in colorectal cancer (CRC) is unclear. METHODS: SNHG17 expression in multiple CRC cohorts was assessed by RT-qPCR or bioinformatic analyses. Cell viability was evaluated using Cell Counting Kit-8 (CCK-8) and colony formation assays. Cell mobility and invasiveness were assessed by Transwell assays. Tumor xenograft and metastasis models were applied to confirm the effects of SNHG17 on CRC tumorigenesis and metastasis in vivo. Immunohistochemistry staining was used to measure protein expression in cancer tissues. RNA pull-down, RNA immunoprecipitation, chromatin immunoprecipitation, and dual luciferase assays were used to investigate the molecular mechanism of SNHG17 in CRC. RESULTS: Using multiple cohorts, we confirmed that SNHG17 is aberrantly upregulated in CRC and correlated with poor survival. In vitro and in vivo functional assays indicated that SNHG17 facilitates CRC proliferation and metastasis. SNHG17 impedes PES1 degradation by inhibiting Trim23-mediated ubiquitination of PES1. SNHG17 upregulates FOSL2 by sponging miR-339-5p, and FOSL2 transcription activates SNHG17 expression, uncovering a SNHG17-miR-339-5p-FOSL2-SNHG17 positive feedback loop. CONCLUSIONS: We identified SNHG17 as an oncogenic lncRNA in CRC and identified abnormal upregulation of SNHG17 as a prognostic risk factor for CRC. Our mechanistic investigations demonstrated, for the first time, that SNHG17 promotes tumor growth and metastasis through two different regulatory mechanisms, SNHG17-Trim23-PES1 axis and SNHG17-miR-339-5p-FOSL2-SNHG17 positive feedback loop, which may be exploited for CRC therapy.

Identification of New Tumor-Related Gene Mutations in Chinese Gastrointestinal Stromal Tumors.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. As the main GIST drivers, gain-of-function mutations in KIT or PDGFRA are closely associated with not only tumor development and progression but also therapeutic response. In addition to the status of KIT and PDGFRA, little is known about other potential GIST-related genes. In this study, we identified the mutation profiles in 49 KIT-mutated GIST tumors using the whole exome sequencing (WES) method. Furthermore, some representative mutations were further validated in an independent GIST cohort using the SNaPshot SNP assay. We identified extensive and diverse mutations of KIT in GIST, including many undescribed variants. In addition, we revealed some new tumor-related gene mutations with unknown pathogenicity. By enrichment analyses of gene function and protein-protein interaction network construction, we showed that these genes were enriched in several important cancer- or metabolism-related signaling pathways, including PI3K-AKT,RTK-RAS, Notch, Wnt, Hippo, mTOR, AMPK, and insulin signaling. In particular, DNA repair-related genes, including MLH1, MSH6, BRCA1, BRCA2, and POLE, are frequently mutated in GISTs, suggesting that immune checkpoint blockade may have promising clinical applications for these GIST subpopulations. In conclusion, in addition to extensive and diverse mutations of KIT, some genes related to DNA-repair and cell metabolism may play important roles in the development, progression and therapeutic response of GIST.