ISL1 predicts poor outcomes for patients with gastric cancer and drives tumor progression through binding to the ZEB1 promoter together with SETD7

ACAT2 suppresses the ubiquitination of YAP1 to enhance the proliferation and metastasis ability of gastric cancer via the upregulation of SETD7

The contributions of aberrantly expressed metabolic enzymes to gastric cancer (GC) initiation and progression have been widely appreciated in recent years. Acetyl-CoA acetyltransferase 2 (ACAT2) is one member of the acetyl- CoA thiolase family. Previous studies demonstrated that ACAT2 either promotes or suppresses tumor progression in different conditions. However, the function and mechanisms of ACAT2 in GC remain unknown. We found that the expression of this enzyme was significantly increased in GC tissues compared with normal counterparts, which prompted us to further investigate the roles of this protein in GC biology. In vitro functional studies showed that ACAT2 knockdown markedly halted the proliferation and the motility of GC cells; these functions favoring malignant phenotypes of GC cells were further validated in animal experiments. Mechanistically, ACAT2 depletion significantly reduced the transcription of SETD7, which is a histone methyltransferase and plays critical roles in GC cells. We found that the pro-tumoral functions of ACAT2 were largely dependent on SETD7. Moreover, SETD7 decreased the ubiquitination level of Yes-associated protein 1 (YAP1), thereby protecting YAP1 from proteasome degradation. Increased YAP1 protein expression remarkably activated the YAP1/TAZ-TEAD1 signaling pathway, which further boosted the malignant phenotypes in GC cells. In conclusion, these findings highlight the pro-tumoral functions and molecular underpinnings of ACAT2 in GC cells, and suggest that ACAT2 could be a promising target in GC treatment.

Revolutionizing pediatric neuroblastoma treatment: unraveling new molecular targets for precision interventions

Neuroblastoma (NB) is the most frequent solid tumor in pediatric cases, contributing to around 15% of childhood cancer-related deaths. The wide-ranging genetic, morphological, and clinical diversity within NB complicates the success of current treatment methods. Acquiring an in-depth understanding of genetic alterations implicated in the development of NB is essential for creating safer and more efficient therapies for this severe condition. Several molecular signatures are being studied as potential targets for developing new treatments for NB patients. In this article, we have examined the molecular factors and genetic irregularities, including those within insulin gene enhancer binding protein 1 (ISL1), dihydropyrimidinase-like 3 (DPYSL3), receptor tyrosine kinase-like orphan receptor 1 (ROR1) and murine double minute 2-tumor protein 53 (MDM2-P53) that play an essential role in the development of NB. A thorough summary of the molecular targeted treatments currently being studied in pre-clinical and clinical trials has been described. Recent studies of immunotherapeutic agents used in NB are also studied in this article. Moreover, we explore potential future directions to discover new targets and treatments to enhance existing therapies and ultimately improve treatment outcomes and survival rates for NB patients.

The pleiotropic nature of NONO, a master regulator of essential biological pathways in cancers

NONO is a member of the Drosophila behavior/human splicing (DBHS) family of proteins. NONO is a multifunctional protein that acts as a "molecular scaffold" to carry out versatile biological activities in many aspects of gene regulation, cell proliferation, apoptosis, migration, DNA damage repair, and maintaining cellular circadian rhythm coupled to the cell cycle. Besides these physiological activities, emerging evidence strongly indicates that NONO-altered expression levels promote tumorigenesis. In addition, NONO can undergo various post-transcriptional or post-translational modifications, including alternative splicing, phosphorylation, methylation, and acetylation, whose impact on cancer remains largely to be elucidated. Overall, altered NONO expression and/or activities are a common feature in cancer. This review provides an integrated scenario of the current understanding of the molecular mechanisms and the biological processes affected by NONO in different tumor contexts, suggesting that a better elucidation of the pleiotropic functions of NONO in physiology and tumorigenesis will make it a potential therapeutic target in cancer. In this respect, due to the complex landscape of NONO activities and interactions, we highlight caveats that must be considered during experimental planning and data interpretation of NONO studies.

SETD7 promotes metastasis of triple-negative breast cancer by YY1 lysine methylation

Breast cancer has gradually become the predominant cause for cancer-associated death in women. The metastatic dissemination and underlying mechanisms of triple-negative breast cancer (TNBC) are not sufficiently understood. (Su(var)3-9, enhancer of zeste, Trithorax) domain-containing protein 7 (SETD7) is vital for promoting the metastasis of TNBC, as demonstrated in this study. Clinical outcomes were significantly worse in primary metastatic TNBC with upregulated SETD7. Overexpression of SETD7 in vitro and in vivo promotes migration of TNBC cells. Two highly conserved lysine (K) residues K173 and K411 of Yin Yang 1 (YY1) are methylated by SETD7. Further, we found that SETD7-mediated K173 residue methylation protects YY1 from the ubiquitin-proteasome degradation. Mechanistically, it was found that the SETD7/YY1 axis regulates epithelial-mesenchymal transition (EMT) and tumor cell migration via the ERK/MAPK pathway in TNBC. The findings indicated that TNBC metastasis is driven by a novel pathway, which may be a promising target for advanced TNBC treatment.

Isl1 promotes gene transcription through physical interaction with Set1/Mll complexes

Histone H3 lysine 4 (H3K4) methylation is generally recognized as a prominent marker of gene activation. While Set1/Mll complexes are major methyltransferases that are responsible for H3K4 methylation, the mechanism of how these complexes are recruited into the target gene promotor is still unclear. Here, starting with an affinity purification-mass spectrometry approach, we have found that Isl1, a highly tissue-specific expressed LIM/homeodomain transcription factor, is physically associated with Set1/Mll complexes. We then show that Wdr5 directly binds to Isl1. And this binding is likely mediated by the homeodomain of Isl1. Functionally, using mouse β-cell and human neuroblastoma tumor cell lines, we show that both Wdr5 binding and H3K4 methylation level at promoters of some Isl1 target genes are significantly reduced upon depletion of Isl1, suggesting Isl1 is required for efficient locus-specific H3K4 methylation. Taken together, our results establish a critical role of Set1/Mll complexes in regulating the target gene expression of Isl1.

RBBP4 regulates the expression of the Mre11-Rad50-NBS1 (MRN) complex and promotes DNA double-strand break repair to mediate glioblastoma chemoradiotherapy resistance

For treatment of glioblastoma (GBM), temozolomide (TMZ) and radiotherapy (RT) exert antitumor effects by inducing DNA double-strand breaks (DSBs), mainly via futile DNA mismatch repair (MMR) and inducing apoptosis. Here, we provide evidence that RBBP4 modulates glioblastoma resistance to chemotherapy and radiotherapy by recruiting transcription factors and epigenetic regulators that bind to their promoters to regulate the expression of the Mre11-Rad50-NBS1(MRN) complex and the level of DNA-DSB repair, which are closely associated with recovery from TMZ- and radiotherapy-induced DNA damage in U87MG and LN229 glioblastoma cells, which have negative MGMT expression. Disruption of RBBP4 induced GBM cell DNA damage and apoptosis in response to TMZ and radiotherapy and enhanced radiotherapy and chemotherapy sensitivity by the independent pathway of MGMT. These results displayed a possible chemo-radioresistant mechanism in MGMT negative GBM. In addition, the RBBP4-MRN complex regulation axis may provide an interesting target for developing therapy-sensitizing strategies for GBM.

The role of SET domain containing lysine methyltransferase 7 in tumorigenesis and development

SET domain containing lysine methyltransferase 7 (SETD7) belongs to the protein lysine methyltransferase family and can catalyze the monomethylation of histone H3K4, which plays a vital role in the regulation of cell cycle, cell differentiation, DNA damage response and chromatin remodeling through K/R-S/T-K (K is lysine residue) sites and the recognition of substrates mediated by SET, i-SET, and n-SET domains and electrostatic action. SETD7 also can regulate the transcription of several genes including β-catenin, Cullin l and lin-28 homolog A (LIN28A), etc. In addition, the abnormal expression of SETD7 can promote the proliferation, migration, invasion of tumor cells, predict the poor prognosis of tumor patients, and may be a potential target for tumor therapy. This paper reviews the structure of SETD7, its role in tumor genesis and development, and the current research progress of relevant targeted drugs to explore its regulatory mechanism in tumor genesis and development and the prospect of targeted therapy.

Transcription networks rewire gene repertoire to coordinate cellular reprograming in prostate cancer

Transcription factors (TFs) represent the most commonly deregulated DNA-binding class of proteins associated with multiple human cancers. They can act as transcriptional activators or repressors that rewire the cistrome, resulting in cellular reprogramming during cancer progression. Deregulation of TFs is associated with the onset and maintenance of various cancer types including prostate cancer. An emerging subset of TFs has been implicated in the regulation of multiple cancer hallmarks during tumorigenesis. Here, we discuss the role of key TFs which modulate transcriptional cicuitries involved in the development and progression of prostate cancer. We further highlight the role of TFs associated with key cancer hallmarks, including, chromatin remodeling, genome instability, DNA repair, invasion, and metastasis. We also discuss the pluripotent function of TFs in conferring lineage plasticity, that aids in disease progression to neuroendocrine prostate cancer. At the end, we summarize the current understanding and approaches employed for the therapeutic targeting of TFs and their cofactors in the clinical setups to prevent disease progression.

A hypoxia risk score for prognosis prediction and tumor microenvironment in adrenocortical carcinoma

Background: Adrenocortical carcinoma (ACC) is a rare malignant endocrine tumor derived from the adrenal cortex. Because of its highly aggressive nature, the prognosis of patients with adrenocortical carcinoma is not impressive. Hypoxia exists in the vast majority of solid tumors and contributes to invasion, metastasis, and drug resistance. This study aimed to reveal the role of hypoxia in Adrenocortical carcinoma and develop a hypoxia risk score (HRS) for Adrenocortical carcinoma prognostic prediction. Methods: Hypoxia-related genes were obtained from the Molecular Signatures Database. The training cohorts of patients with adrenocortical carcinoma were downloaded from The Cancer Genome Atlas, while another three validation cohorts with comprehensive survival data were collected from the Gene Expression Omnibus. In addition, we constructed a hypoxia classifier using a random survival forest model. Moreover, we explored the relationship between the hypoxia risk score and immunophenotype in adrenocortical carcinoma to evaluate the efficacy of immune check inhibitors (ICI) therapy and prognosis of patients. Results: HRS and tumor stage were identified as independent prognostic factors. HRS was negatively correlated with immune cycle activity, immune cell infiltration, and the T cell inflammatory score. Therefore, we considered the low hypoxia risk score group as the inflammatory immunophenotype, whereas the high HRS group was a non-inflammatory immunophenotype. In addition, the HRS was negatively related to the expression of common immune checkpoint molecules such as PD-L1, CD200, CTLA-4, and TIGIT, suggesting that patients with a lower hypoxia risk score respond better to immunotherapy. Conclusion: We developed and validated a novel hypoxia risk score to predict the immunophenotype and response of patients with adrenocortical carcinoma to immune check inhibitors therapy. These findings not only provide fresh prognostic indicators for adrenocortical carcinoma but also offer several promising treatment targets for this disease.

Single-cell multiomics analysis reveals regulatory programs in clear cell renal cell carcinoma

The clear cell renal cell carcinoma (ccRCC) microenvironment consists of many different cell types and structural components that play critical roles in cancer progression and drug resistance, but the cellular architecture and underlying gene regulatory features of ccRCC have not been fully characterized. Here, we applied single-cell RNA sequencing (scRNA-seq) and single-cell assay for transposase-accessible chromatin sequencing (scATAC-seq) to generate transcriptional and epigenomic landscapes of ccRCC. We identified tumor cell-specific regulatory programs mediated by four key transcription factors (TFs) (HOXC5, VENTX, ISL1, and OTP), and these TFs have prognostic significance in The Cancer Genome Atlas (TCGA) database. Targeting these TFs via short hairpin RNAs (shRNAs) or small molecule inhibitors decreased tumor cell proliferation. We next performed an integrative analysis of chromatin accessibility and gene expression for CD8⁺ T cells and macrophages to reveal the different regulatory elements in their subgroups. Furthermore, we delineated the intercellular communications mediated by ligand–receptor interactions within the tumor microenvironment. Taken together, our multiomics approach further clarifies the cellular heterogeneity of ccRCC and identifies potential therapeutic targets.

NUCB2: roles in physiology and pathology

Nucleobindin2 (NUCB2) is a member of nucleobindin family which was first found in the nucleus of the hypothalamus, and had a relationship in diet and energy homeostasis. Its location in normal tissues such as stomach and islet further confirms that it plays a vital role in the regulation of physiological functions of the body. Besides, NUCB2 participates in tumorigenesis through activating various signal-pathways, more and more studies indicate that NUCB2 might impact tumor progression by promoting or inhibiting proliferation, apoptosis, autophagy, metastasis, and invasion of tumor cells. In this review, we comprehensively stated NUCB2's expression and functions, and introduced the role of NUCB2 in physiology and pathology and its mechanism. What is more, pointed out the potential direction of future research.

Patient-Derived Xenograft: A More Standard "Avatar" Model in Preclinical Studies of Gastric Cancer

Despite advances in diagnosis and treatment, gastric cancer remains the third most common cause of cancer-related death in humans. The establishment of relevant animal models of gastric cancer is critical for further research. Due to the complexity of the tumor microenvironment and the genetic heterogeneity of gastric cancer, the commonly used preclinical animal models fail to adequately represent clinically relevant models of gastric cancer. However, patient-derived models are able to replicate as much of the original inter-tumoral and intra-tumoral heterogeneity of gastric cancer as possible, reflecting the cellular interactions of the tumor microenvironment. In addition to implanting patient tissues or primary cells into immunodeficient mouse hosts for culture, the advent of alternative hosts such as humanized mouse hosts, zebrafish hosts, and in vitro culture modalities has also facilitated the advancement of gastric cancer research. This review highlights the current status, characteristics, interfering factors, and applications of patient-derived models that have emerged as more valuable preclinical tools for studying the progression and metastasis of gastric cancer.

ZKSCAN5 Activates VEGFC Expression by Recruiting SETD7 to Promote the Lymphangiogenesis, Tumour Growth, and Metastasis of Breast Cancer

The growth of lymphatic vessels (lymphangiogenesis) plays a pivotal role in breast cancer progression and metastasis and the immune response. Vascular endothelial growth factor C (VEGFC) has been demonstrated to accelerate cancer metastasis and modulate the immune system by enhancing lymphangiogenesis. However, it remains largely unclear how transcription factors physically regulate VEGFC expression by interacting with histone-modifying enzymes. Like many histone-modifying enzymes, SETD7 plays a key role in cell proliferation and inhibits tumour cell differentiation. In this study, we identified the role of the transcription factor zinc finger with KRAB and SCAN domains 5 (ZKSCAN5) in interacting with histone methyltransferase SETD7 and mediating VEGFC transcription and tumour lymphangiogenesis. ZKSCAN5 interacts with and recruits SETD7 to the VEGFC promoter. By regulating breast cancer-secreted VEGFC, ZKSCAN5 could induce the tube formation of lymph endothelial cells, which promotes tumour proliferation, migration, and metastasis. Clinically, the expression of ZKSCAN5 was frequently upregulated in patients with breast cancer and positively correlated with the expression of VEGFC and the number of lymphatic microvessels. ZKSCAN5 is a poor prognostic factor for patients with breast cancer. Our results characterise the role of ZKSCAN5 in regulating VEGFC transcription and predict ZKSCAN5 as a breast cancer therapeutic target.

The dual role of glioma exosomal microRNAs: glioma eliminates tumor suppressor miR-1298-5p via exosomes to promote immunosuppressive effects of MDSCs

Clear evidence shows that tumors could secrete microRNAs (miRNAs) via exosomes to modulate the tumor microenvironment (TME). However, the mechanisms sorting specific miRNAs into exosomes are still unclear. In order to study the biological function and characterization of exosomal miRNAs, we performed whole-transcriptome sequencing in 59 patients' whole-course cerebrospinal fluid (CSF) small extracellular vesicles (sEV) and matched glioma tissue samples. The results demonstrate that miRNAs could be divided into exosome-enriched miRNAs (ExomiRNAs) and intracellular-retained miRNAs (CLmiRNAs), and exosome-enriched miRNAs generally play a dual role. Among them, miR-1298-5p was enriched in CSF exosomes and suppressed glioma progression in vitro and vivo experiments. Interestingly, exosomal miR-1298-5p could promote the immunosuppressive effects of myeloid-derived suppressor cells (MDSCs) to facilitate glioma. Therefore, we found miR-1298-5p had different effects on glioma cells and MDSCs. Mechanically, downstream signaling pathway analyses showed that miR-1298-5p plays distinct roles in glioma cells and MDSCs via targeting SETD7 and MSH2, respectively. Moreover, reverse verification was performed on the intracellular-retained miRNA miR-9-5p. Thus, we confirmed that tumor-suppressive miRNAs in glioma cells could be eliminated through exosomes and target tumor-associated immune cells to induce tumor-promoting phenotypes. Glioma could get double benefit from it. These findings uncover the mechanisms that glioma selectively sorts miRNAs into exosomes and modulates tumor immunity.

Identification of a new RNA-binding proteins-based signature for prognostic prediction in gastric cancer

Gastric cancer (GC) is one of the most common cancers with high incidence and mortality worldwide. Recently, RNA-binding proteins (RBPs) have drawn more and more attention for its role in cancer pathophysiology. However, the function and clinical implication of RBPs in GC have not been fully elucidated. RNA sequencing data along with the corresponding clinical information of GC patients were downloaded from The Cancer Genome Atlas (TCGA) database. Differentially expressed RNA-binding proteins (DERBPs) between tumor and normal tissues were identified by "limma" package. Functional enrichment analysis and the protein-protein interaction (PPI) network were harnessed to explore the function and interaction of DERBPs. Next, univariate and multiple Cox regression were applied to screen prognosis-related hub RBPs and to construct a signature for GC. Meanwhile, a nomogram was built on the basis of the independent factors. A total of 296 DERBPs were found, and most of them mainly related to post-transcriptional regulation of RNA and ribonucleoprotein. A PPI network of DERBPs was constructed, consisting of 262 nodes and 2567 edges. A prognostic signature was built depending on 7 prognosis-related hub RBPs that could divide GC patients into high-risk and low-risk groups. Survival analysis showed that high-risk group had a worse prognosis compared with the low-risk group and the time-dependent receiver operating characteristic (ROC) curves suggested that signature existed moderate predictive capacities of survival for GC patients. Similar results were obtained from another independent set GSE62254, confirming the robustness of signature. Besides, the genetic variation and immune heterogeneity differences were identified between the high-risk and low-risk groups by bioinformatics methods. These findings would provide evidence of the effect of RBPs and offer a novel potential biomarker in prognostic prediction and clinical decision for GC.

Large-Scale Gastric Cancer Susceptibility Gene Identification Based on Gradient Boosting Decision Tree

The early clinical symptoms of gastric cancer are not obvious, and metastasis may have occurred at the time of treatment. Poor prognosis is one of the important reasons for the high mortality of gastric cancer. Therefore, the identification of gastric cancer-related genes can be used as relevant markers for diagnosis and treatment to improve diagnosis precision and guide personalized treatment. In order to further reveal the pathogenesis of gastric cancer at the gene level, we proposed a method based on Gradient Boosting Decision Tree (GBDT) to identify the susceptible genes of gastric cancer through gene interaction network. Based on the known genes related to gastric cancer, we collected more genes which can interact with them and constructed a gene interaction network. Random Walk was used to extract network association of each gene and we used GBDT to identify the gastric cancer-related genes. To verify the AUC and AUPR of our algorithm, we implemented 10-fold cross-validation. GBDT achieved AUC as 0.89 and AUPR as 0.81. We selected four other methods to compare with GBDT and found GBDT performed best.

ISL1 promotes enzalutamide resistance in castration-resistant prostate cancer (CRPC) through epithelial to mesenchymal transition (EMT)

Abnormal expression of insulin gene enhancer-binding protein 1 (ISL1) has been demonstrated to be closely associated with cancer development and progression in several cancers. However, little is known about ISL1 expression in metastatic castration-resistant prostate cancer (CRPC). ISL1 has also been recognized as a positive modulator of epithelial-mesenchymal transition (EMT). In this study, we focused on ISL1 which showed maximum upregulation at the mRNA level in the enzalutamide-resistant cell line. Accordingly, we found that ISL1 was overexpressed in enzalutamide-resistant C4-2B cells and its expression was significantly related to EMT. Our findings reveal the important role of ISL1 in androgen receptor (AR)-dependent prostate cancer cell growth; ISL1 knockdown reduced the AR activity and cell growth. ISL1 knockdown using small-interfering RNA inhibited AR, PSA, and EMT-related protein expression in C4-2B ENZR cells. In addition, knock-down ISL1 reduced the levels of AKT and p65 phosphorylation in C4-2B ENZR cells and these suggest that knock-down ISL1 suppresses EMT in part by targeting the AKT/NF-κB pathway. Further, ISL1 downregulation could effectively inhibit tumor growth in a human CRPC xenograft model. Together, the present study shows that downregulation of ISL1 expression is necessary for overcoming enzalutamide resistance and improving the survival of CRPC patients.

ISL1 promoted tumorigenesis and EMT via Aurora kinase A-induced activation of PI3K/AKT signaling pathway in neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid malignancy in children and its mortality rate is relatively high. However, driver genes of NB are not clearly identified. Using bioinformatics analysis, we determined the top 8 differentially expressed genes (DEGs) in NB, including GFAP, PAX6, FOXG1, GAD1, PTPRC, ISL1, GRM5, and GATA3. Insulin gene enhancer binding protein 1 (ISL1) is a LIM homeodomain transcription factor which has been found to be highly expressed in a variety of malignant tumors, but the function of ISL1 in NB has not been fully elucidated. We identified ISL1 as an oncogene in NB. ISL1 is preferentially upregulated in NB tissues compared with normal tissues. High ISL1 expression is significantly associated with poor outcome of NB patients. Knockdown of ISL1 markedly represses proliferation and induces cell apoptosis in vitro, and suppresses tumorigenicity in vivo, while overexpression of ISL1 has the opposite effects. Mechanistically, we demonstrate that ISL1 promotes cell proliferation and EMT transformation through PI3K/AKT signaling pathway by upregulating Aurora kinase A (AURKA), a serine-threonine kinase that is essential for the survival of NB cells. The blockade of AURKA attenuates the function of ISL1 overexpression in the regulation of cell proliferation and migration, Conclusively, this study showed that ISL1 targeted AURKA to facilitate the development of NB, which provided new insights into the tumorigenesis of NB. Thus, ISL1 may be a promising therapeutic target in the future.

Phosphorylation of islet-1 serine 269 by CDK1 increases its transcriptional activity and promotes cell proliferation in gastric cancer

Background

Despite recent advances in diagnostic and therapeutic approaches for gastric cancer (GC), the survival of patients with advanced GC remains very low. Islet-1 (ISL1) is a LIM-homeodomain transcription factor, which is upregulated and promotes cell proliferation in GC. The exact mechanism by which ISL1 influences GC development is unclear.

Methods

Co-immunoprecipitation (co-IP) and glutathione S-transferase (GST)-pulldown assays were employed to evaluate the interaction of ISL1 with CDK1. Western blot and immunohistochemistry analyses were performed to evaluate the ability of CDK1 to phosphorylate ISL1 at Ser 269 in GC cell and tissue specimens. Chromatin immunoprecipitation (ChIP), ChIP re-IP, luciferase reporter, and CCK-8 assays were combined with flow cytometry cell cycle analysis to detect the transactivation potency of ISL1-S269-p and its ability to promote cell proliferation. The self-stability and interaction with CDK1 of ISL1-S269-p were also determined.

Results

ISL1 is phosphorylated by CDK1 at serine 269 (S269) in vivo. Phosphorylation of ISL1 by CDK1 on serine 269 strengthened its binding on the cyclin B1 and cyclin B2 promoters and increased its transcriptional activity in GC. Furthermore, CDK1-dependent phosphorylation of ISL1 correlated positively with ISL1 protein self-stability in NIH3T3 cells.

Conclusions

ISL1-S269-p increased ISL1 transcriptional activity and self-stability while binding to the cyclinB1 and cyclinB2 promoters promotes cell proliferation. ISL1-S269-p is therefore crucial for tumorigenesis and potentially a direct therapeutic target for GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00302-6.

Expression of ISL1 and its partners in prostate cancer progression and neuroendocrine differentiation

INTRODUCTION AND OBJECTIVES

ISL1 serves as a biomarker of metastasis and neuroendocrine neoplasia in multiple tumors. However, the expression and relation of ISL1 to other biomarkers in prostate cancer have not been fully elucidated. Here, we characterize the expression of ISL1 and its partners in PCa and document its association to disease progression and post castration resistance neuroendocrine differentiation.

METHODS

The expression of ISL1 was interrogated in > 6000 primary samples from the Decipher GRID registry and 250 mCRPC samples to assess its prognostic value and relation to neuroendocrine differentiation.

RESULTS

ISL1 was highly correlated to MEIS genes and other genes related to cell motility. ISL1 down-regulation in PCa was associated with cancer progression, aggressive primary tumors, and metastatic outcome. We found that ISL1 is highly correlated to MEIS genes across multiple primary PCa and mCRPC cohorts. The expression of ISL1 and MEIS genes were significantly and inversely related to metastasis-free survival and lethal disease, and were downregulated in CRPC and hormone naïve metastatic tumors but showed upregulation in neuroendocrine tumors. Co-immunoprecipitation showed MEIS2 and ISL1 interacting with each supporting their role in modulating transcriptional regulation and nominating this complex for potential targeted therapy.

CONCLUSIONS

ISL1 complex with MEIS2 serves a critical role in prostate tumor progression and its upregulation in mCRPC/NE provides a rationale for assessing the role of ISL1 and its associated protein in treatment resistance.

Insulin gene enhancer protein 1 mediates glycolysis and tumorigenesis of gastric cancer through regulating glucose transporter 4

Background

Insulin gene enhancer protein 1, (ISL1), a LIM‐homeodomain transcription factor, is involved in multiple tumors and is associated with insulin secretion and metabolic phenotypes. However, the role of ISL1 in stimulating glycolysis to promote tumorigenesis in gastric cancer (GC) is unclear. In this study, we aimed to characterize the expression pattern of ISL1 in GC patients and explore its molecular biological mechanism in glycolysis and tumorigenesis.

Methods

We analyzed the expression and clinical significance of ISL1 in GC using immunohistochemistry and real‐time polymerase chain reaction (PCR). Flow cytometry and IncuCyte assays were used to measure cell proliferation after ISL1 knockdown. RNA‐sequencing was performed to identify differentially expressed genes, followed by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and Gene Set Enrichment Analysis (GSEA) to reveal key signaling pathways likely regulated by ISL1 in GC. Alteration of the glycolytic ability of GC cells with ISL1 knockdown was validated by measuring the extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) and by detecting glucose consumption and lactate production. The expression of glucose transporter 4 (GLUT4) and ISL1 was assessed by Western blotting, immunohistochemistry, and immunofluorescent microscopy. The luciferase reporter activity and chromatin immunoprecipitation assays were performed to determine the transcriptional regulation of ISL1 on GLUT4.

Results

High levels of ISL1 and GLUT4 expression was associated with short survival of GC patients. ISL1 knockdown inhibited cell proliferation both in vitro and in vivo. KEGG analysis and GSEA for RNA‐sequencing data indicated impairment of the glycolysis pathway in GC cells with ISL1 knockdown, which was validated by reduced glucose uptake and lactate production, decreased ECAR, and increased OCR. Mechanistic investigation indicated that ISL1 transcriptionally regulated GLUT4 through binding to its promoter.

Conclusion

ISL1 facilitates glycolysis and tumorigenesis in GC via the transcriptional regulation of GLUT4.

Sex-Specific Genetic Associations for Barrett's Esophagus and Esophageal Adenocarcinoma

BACKGROUND & AIMS

Esophageal adenocarcinoma (EA) and its premalignant lesion, Barrett's esophagus (BE), are characterized by a strong and yet unexplained male predominance (with a male-to-female ratio in EA incidence of up to 6:1). Genome-wide association studies (GWAS) have identified more than 20 susceptibility loci for these conditions. However, potential sex differences in genetic associations with BE/EA remain largely unexplored.

METHODS

Given strong genetic overlap, BE and EA cases were combined into a single case group for analysis. These were compared with population-based controls. We performed sex-specific GWAS of BE/EA in 3 separate studies and then used fixed-effects meta-analysis to provide summary estimates for >9 million variants for male and female individuals. A series of downstream analyses were conducted separately in male and female individuals to identify genes associated with BE/EA and the genetic correlations between BE/EA and other traits.

RESULTS

We included 6758 male BE/EA cases, 7489 male controls, 1670 female BE/EA cases, and 6174 female controls. After Bonferroni correction, our meta-analysis of sex-specific GWAS identified 1 variant at chromosome 6q11.1 (rs112894788, KHDRBS2-MTRNR2L9, PBONF = .039) that was statistically significantly associated with BE/EA risk in male individuals only, and 1 variant at chromosome 8p23.1 (rs13259457, PRSS55-RP1L1, PBONF = 0.057) associated, at borderline significance, with BE/EA risk in female individuals only. We also observed strong genetic correlations of BE/EA with gastroesophageal reflux disease in male individuals and obesity in female individuals.

CONCLUSIONS

The identified novel sex-specific variants associated with BE/EA could improve the understanding of the genetic architecture of the disease and the reasons for the male predominance.

The U2AF2 /circRNA ARF1/miR-342-3p/ISL2 feedback loop regulates angiogenesis in glioma stem cells

BACKGROUND

Glioma is the most common and lethal primary brain tumor in adults, and angiogenesis is one of the key factors contributing to its proliferation, aggressiveness, and malignant transformation. However, the discovery of novel oncogenes and the study of its molecular regulating mechanism based on circular RNAs (circRNAs) may provide a promising treatment target in glioma.

METHODS

Bioinformatics analysis, qPCR, western blotting, and immunohistochemistry were used to detect the expression levels of ISL2, miR-342-3p, circRNA ARF1 (cARF1), U2AF2, and VEGFA. Patient-derived glioma stem cells (GSCs) were established for the molecular experiments. Lentiviral-based infection was used to regulate the expression of these molecules in GSCs. The MTS, EDU, Transwell, and tube formation assays were used to detect the proliferation, invasion, and angiogenesis of human brain microvessel endothelial cells (hBMECs). RNA-binding protein immunoprecipitation, RNA pull-down, dual-luciferase reporter, and chromatin immunoprecipitation assays were used to detect the direct regulation mechanisms among these molecules.

RESULTS

We first identified a novel transcription factor related to neural development. ISL2 was overexpressed in glioma and correlated with poor patient survival. ISL2 transcriptionally regulated VEGFA expression in GSCs and promoted the proliferation, invasion, and angiogenesis of hBMECs via VEGFA-mediated ERK signaling. Regarding its mechanism of action, cARF1 upregulated ISL2 expression in GSCs via miR-342-3p sponging. Furthermore, U2AF2 bound to and promoted the stability and expression of cARF1, while ISL2 induced the expression of U2AF2, which formed a feedback loop in GSCs. We also showed that both U2AF2 and cARF1 had an oncogenic effect, were overexpressed in glioma, and correlated with poor patient survival.

CONCLUSIONS

Our study identified a novel feedback loop among U2AF2, cARF1, miR-342-3p, and ISL2 in GSCs. This feedback loop promoted glioma angiogenesis, and could provide an effective biomarker for glioma diagnosis and prognostic evaluation, as well as possibly being used for targeted therapy.

NONO Inhibits Lymphatic Metastasis of Bladder Cancer via Alternative Splicing of SETMAR

Bladder cancer patients with lymph node (LN) metastasis have an extremely poor prognosis and no effective treatment. The alternative splicing of precursor (pre-)mRNA participates in the progression of various tumors. However, the precise mechanisms of splicing factors and cancer-related variants in LN metastasis of bladder cancer remain largely unknown. The present study identified a splicing factor, non-POU domain-containing octamer-binding protein (NONO), that was significantly downregulated in bladder cancer tissues and correlated with LN metastasis status, tumor stage, and prognosis. Functionally, NONO markedly inhibited bladder cancer cell migration and invasion in vitro and LN metastasis in vivo. Mechanistically, NONO regulated the exon skipping of SETMAR by binding to its motif, mainly through the RRM2 domain. NONO directly interacted with splicing factor proline/glutamine rich (SFPQ) to regulate the splicing of SETMAR, and it induced metastasis suppression of bladder cancer cells. SETMAR-L overexpression significantly reversed the metastasis of NONO-knockdown bladder cancer cells, both in vitro and in vivo. The further analysis revealed that NONO-mediated SETMAR-L can induce H3K27me3 at the promotor of metastatic oncogenes and inhibit their transcription, ultimately resulting in metastasis suppression. Therefore, the present findings uncover the molecular mechanism of lymphatic metastasis in bladder cancer, which may provide novel clinical markers and therapeutic strategies for LN-metastatic bladder cancer.

Role of CITED2 in stem cells and cancer

Cbp/P300 interacting transactivator with Glu/Asp-rich carboxy-terminal domain 2 (CITED2) is a transcription co-factor that interacts with several other transcription factors and co-factors, and serves critical roles in fundamental cell processes, including proliferation, apoptosis, differentiation, migration and autophagy. The interacting transcription factors or co-factors of CITED2 include LIM homeobox 2, transcription factor AP-2, SMAD2/3, peroxisome proliferator-activated receptor γ, oestrogen receptor, MYC, Nucleolin and p300/CBP, which regulate downstream gene expression, and serve important roles in the aforementioned fundamental cell processes. Emerging evidence has demonstrated that CITED2 serves an essential role in embryonic and adult tissue stem cells, including hematopoietic stem cells and tendon-derived stem/progenitor cells. Additionally, CITED2 has been reported to function in different types of cancer. Although the functions of CITED2 in different tissues vary depending on the interaction partner, altered CITED2 expression or altered interactions with transcription factors or co-factors result in alterations of fundamental cell processes, and may affect stem cell maintenance or cancer cell survival. The aim of this review is to summarize the molecular mechanisms of CITED2 function and how it serves a role in stem cells and different types of cancer based on the currently available literature.

The role of histone methylation in the development of digestive cancers: a potential direction for cancer management

Digestive cancers are the leading cause of cancer-related death worldwide and have high risks of morbidity and mortality. Histone methylation, which is mediated mainly by lysine methyltransferases, lysine demethylases, and protein arginine methyltransferases, has emerged as an essential mechanism regulating pathological processes in digestive cancers. Under certain conditions, aberrant expression of these modifiers leads to abnormal histone methylation or demethylation in the corresponding cancer-related genes, which contributes to different processes and phenotypes, such as carcinogenesis, proliferation, metabolic reprogramming, epithelial–mesenchymal transition, invasion, and migration, during digestive cancer development. In this review, we focus on the association between histone methylation regulation and the development of digestive cancers, including gastric cancer, liver cancer, pancreatic cancer, and colorectal cancer, as well as on its clinical application prospects, aiming to provide a new perspective on the management of digestive cancers.

Identification and Validation of an Individualized EMT-Related Prognostic Risk Score Formula in Gastric Adenocarcinoma Patients

Background

The epithelial-mesenchymal transition (EMT) is a pivotal process for fibrotic disease, embryonic development, and wound healing. Moreover, some evidence has proven that the disorder of EMT also plays an important role in carcinogenesis, especially invasion and metastasis of various tumors (Ritchie et al., 2015). Additionally, gastric adenocarcinoma (GAC) is a common gastrointestinal malignancy which is the fourth most commonly diagnosed tumor. Our study is aimed at identifying the prognostic value of EMT-related genes in gastric adenocarcinoma.

Methods

Firstly, high-throughput and clinical data were downloaded from The Cancer Genome Atlas (TCGA) database. 99 differentially expressed EMT-related genes (ERGs) were obtained in these gastric adenocarcinoma data. Secondly, GO and KEGG enrichment analyses show that EMT may promote gastric carcinogenesis. Next, 10 ERGs associated with prognosis of gastric adenocarcinoma patients are screened out by univariate Cox regression, and 6 pivotal prognostic ERGs (MMP8, MMP11, TFDP3, MYB, F2, and CNTN1) are identified through multivariate Cox regression. These 6 genes are confirmed with significant prognostic value in gastric adenocarcinoma through overall survival (OS) analysis. Finally, a risk score formula is constructed and tested in another gastric adenocarcinoma cohort from GEO.

Results

99 differentially expressed EMT-related genes (ERGs) and their enriched pathways are identified. 10 ERGs are strongly related to the prognosis of GAC patients. A risk score formula of 6 prognosis-related ERGs used to predict the prognosis of gastric adenocarcinoma patients is identified and tested (risk score = 0.448115∗expression value of MMP8 + 0.378892∗expression value of MMP11 − 0.3226∗expression value of MYB + 1.322812∗expression value of TFDP3 + 0.325063∗expression value of F2 + 0.334197∗expression value of CNTN1).

Conclusion

This study provides a potential prognostic signature for predicting prognosis of gastric adenocarcinoma patients and molecular insights of EMT in gastric adenocarcinoma, and the formula focusing on the prognosis of gastric adenocarcinoma can be effective.

METTL3/YTHDF2 m6 A axis promotes tumorigenesis by degrading SETD7 and KLF4 mRNAs in bladder cancer

N6‐Methyladenosine (m⁶A) modification, the most prevalent modification of eukaryotic messenger RNA (mRNA), is involved in the progression of various tumours. However, the specific role of m⁶A in bladder cancer (BCa) is still poorly understood. In this study, we demonstrated the tumour‐promoting function and specific regulatory mechanism of m⁶A axis, consisting of the core ‘writer’ protein METTL3 and the major reader protein YTHDF2. Depletion of METTL3 impaired cancer proliferation and cancer metastasis in vitro and in vivo. Through transcriptome sequencing, m⁶A methylated RNA immunoprecipitation (MeRIP) and RIP, we determined that the METTL3/YTHDF2 m⁶A axis directly degraded the mRNAs of the tumour suppressors SETD7 and KLF4, contributing to the progression of BCa. In addition, overexpression of SETD7 and KLF4 revealed a phenotype consistent with that induced by depletion of the m⁶A axis. Thus, our findings on the METTL3/YTHDF2/SETD7/KLF4 m⁶A axis provide the insight into the underlying mechanism of carcinogenesis and highlight potential therapeutic targets for BCa.

LIM homeodomain transcription factor Isl1 affects urethral epithelium differentiation and apoptosis via Shh

Urethral hypoplasia, including failure of urethral tube closure, is one of the common phenotypes observed in hereditary human disorders, the mechanism of which remains unclear. The present study was thus designed to study the expression, functions, and related mechanisms of the LIM homeobox transcription factor Isl1 throughout mouse urethral development. Results showed that Isl1 was highly expressed in urethral epithelial cells and mesenchymal cells of the genital tubercle (GT). Functional studies were carried out by utilizing the tamoxifen-inducible Isl1-knockout mouse model. Histological and morphological results indicated that Isl1 deletion caused urethral hypoplasia and inhibited maturation of the complex urethral epithelium. In addition, we show that Isl1-deleted mice failed to maintain the progenitor cell population required for renewal of urethral epithelium during tubular morphogenesis and exhibited significantly increased cell death within the urethra. Dual-Luciferase reporter assays and yeast one-hybrid assays showed that ISL1 was essential for normal urethral development by directly targeting the Shh gene. Collectively, results presented here demonstrated that Isl1 plays a crucial role in mouse urethral development, thus increasing our potential for understanding the mechanistic basis of hereditary urethral hypoplasia.