SRSF9 promotes colorectal cancer progression via stabilizing DSN1 mRNA in an m6A-related manner

EEF1D stabilized by SRSF9 promotes colorectal cancer via enhancing the proliferation and metastasis

Colorectal cancer (CRC) is the third most common cancer and causes high mortality worldwide. Although CRC has been studied widely, the molecular mechanism is not completely known. Eukaryotic translation elongation factor 1 delta (EEF1D) participates in the progression of various tumors, however, the effect of EEF1D on CRC remains unclear. Here, we aimed to identify the potential mechanism of EEF1D in CRC. The expression levels of EEF1D were assessed in CRC samples. Functional analysis of EEF1D in CRC was detected in vitro and in vivo. The regulatory mechanism of EEF1D was identified with RNA immunoprecipitation, RNA pull-down assay, and proteomics analysis. Our findings confirmed that EEF1D was upregulated in human CRC tissues. Functionally, EEF1D overexpression accelerated cell proliferation and metastasis, whereas EEF1D knockdown inhibited cell proliferation and metastasis both in vitro and in vivo CRC models. Furthermore, we showed that EEF1D was upregulated by SRSF9 via binding to 3'UTR of EEF1D mRNA. EEF1D knockdown reversed the malignant phenotype induced by SRSF9 overexpression. These findings demonstrated that EEF1D promotes CRC progression, and EEF1D may be a molecular target against CRC.

Interaction of the intestinal cytokines-JAKs-STAT3 and 5 axes with RNA N6-methyladenosine to promote chronic inflammation-induced colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers, with a high mortality rate worldwide. Mounting evidence indicates that mRNA modifications are crucial in RNA metabolism, transcription, processing, splicing, degradation, and translation. Studies show that N6-methyladenosine (m6A) is mammalians' most common epi-transcriptomic modification. It has been demonstrated that m6A is involved in cancer formation, progression, invasion, and metastasis, suggesting it could be a potential biomarker for CRC diagnosis and developing therapeutics. Cytokines, growth factors, and hormones function in JAK/STAT3/5 signaling pathway, and they could regulate the intestinal response to infection, inflammation, and tumorigenesis. Reports show that the JAK/STAT3/5 pathway is involved in CRC development. However, the underlying mechanism is still unclear. Signal Transducer and Activator of Transcription 3/5 (STAT3, STAT5) can act as oncogenes or tumor suppressors in the context of tissue types. Also, epigenetic modifications and mutations could alter the balance between pro-oncogenic and tumor suppressor activities of the STAT3/5 signaling pathway. Thus, exploring the interaction of cytokines-JAKs-STAT3 and/or STAT5 with mRNA m6A is of great interest. This review provides a comprehensive overview of the characteristics and functions of m6A and JAKs-STAT3/5 and their relationship with gastrointestinal (GI) cancers.

SRSF9 promotes cell proliferation and migration of glioblastoma through enhancing CDK1 expression

BACKGROUND

Glioblastoma (GBM) is a highly aggressive and prevalent brain tumor that poses significant challenges in treatment. SRSF9, an RNA-binding protein, is essential for cellular processes and implicated in cancer progression. Yet, its function and mechanism in GBM need clarification.

METHODS

Bioinformatics analysis was performed to explore differential expression of SRSF9 in GBM and its prognostic relevance to glioma patients. SRSF9 and CDK1 expression in GBM cell lines and patients' tissues were quantified by RT-qPCR, Western blot or immunofluorescence assay. The role of SRSF9 in GBM cell proliferation and migration was assessed by MTT, Transwell and colony formation assays. Additionally, transcriptional regulation of CDK1 by SRSF9 was investigated using ChIP-PCR and dual-luciferase assays.

RESULTS

The elevated SRSF9 expression correlates to GBM stages and poor survival of glioma patients. Through gain-of-function and loss-of-function strategies, SRSF9 was demonstrated to promote proliferation and migration of GBM cells. Bioinformatics analysis showed that SRSF9 has an impact on cell growth pathways including cell cycle checkpoints and E2F targets. Mechanistically, SRSF9 appears to bind to the promoter of CDK1 gene and increase its transcription level, thus promoting GBM cell proliferation.

CONCLUSIONS

These findings uncover the cellular function of SRSF9 in GBM and highlight its therapeutic potential for GBM.

ZSWIM4 inhibition improves chemosensitivity in epithelial ovarian cancer cells by suppressing intracellular glycine biosynthesis

BACKGROUND

Zinc finger SWIM-type containing 4 (ZSWIM4) induces drug resistance in breast cancer cells. However, its role in epithelial ovarian cancer (EOC) remains unknown. In this study, we aimed to investigate the clinical significance of ZSWIM4 expression in EOC and develop new clinical therapeutic strategies for EOC.

METHODS

ZSWIM4 expression in control and EOC tumor tissues was examined using immunohistochemistry. Lentiviral transduction, Cell Counting Kit-8 assay, tumorsphere formation assay, flow cytometry, western blotting, and animal xenograft model were used to assess the role of ZSWIM4 in chemotherapy. Cleavage Under Targets and Tagmentation (CUT&Tag) assays, chromatin immunoprecipitation assays, and luciferase reporter assays were used to confirm FOXK1-mediated upregulation of ZSWIM4 expression. The mechanism by which ZSWIM4 inhibition improves chemosensitivity was evaluated using RNA-sequencing. A ZSWIM4-targeting inhibitor was explored by virtual screening and surface plasmon resonance analysis. Patient-derived organoid (PDO) models were constructed from EOC tumor tissues with ZSWIM4 expression.

RESULTS

ZSWIM4 was overexpressed in EOC tumor tissues and impaired patient prognoses. Its expression correlated positively with EOC recurrence. ZSWIM4 expression was upregulated following carboplatin treatment, which, in turn, contributed to chemoresistance. Silencing ZSWIM4 expression sensitized EOC cells to carboplatin treatment in vitro and in vivo. FOXK1 could bind to the GTAAACA sequence of the ZSWIM4 promoter region to upregulate ZSWIM4 transcriptional activity and FOXK1 expression increased following carboplatin treatment, leading to an increase in ZSWIM4 expression. Mechanistically, ZSWIM4 knockdown downregulated the expression of several rate-limiting enzymes involved in glycine synthesis, causing a decrease in intracellular glycine levels, thus enhancing intracellular reactive oxygen species production induced by carboplatin treatment. Compound IPN60090 directly bound to ZSWIM4 protein and exerted a significant chemosensitizing effect in both EOC cells and PDO models.

CONCLUSIONS

ZSWIM4 inhibition enhanced EOC cell chemosensitivity by ameliorating intracellular glycine metabolism reprogramming, thus providing a new potential therapeutic strategy for EOC.

Recent advances of m6A methylation in skeletal system disease

Skeletal system disease (SSD) is defined as a class of chronic disorders of skeletal system with poor prognosis and causes heavy economic burden. m6A, methylation at the N6 position of adenosine in RNA, is a reversible and dynamic modification in posttranscriptional mRNA. Evidences suggest that m6A modifications play a crucial role in regulating biological processes of all kinds of diseases, such as malignancy. Recently studies have revealed that as the most abundant epigentic modification, m6A is involved in the progression of SSD. However, the function of m6A modification in SSD is not fully illustrated. Therefore, make clear the relationship between m6A modification and SSD pathogenesis might provide novel sights for prevention and targeted treatment of SSD. This article will summarize the recent advances of m6A regulation in the biological processes of SSD, including osteoporosis, osteosarcoma, rheumatoid arthritis and osteoarthritis, and discuss the potential clinical value, research challenge and future prospect of m6A modification in SSD.

A multidimensional analysis of ZW10 interacting kinetochore protein in human tumors

ZW10 interacting kinetochore protein (ZWINT), an essential part of the kinetochore complex, plays a crucial role in maintaining genome stability by correcting improper attachments between the kinetochore and microtubules. An initial analysis of The Cancer Genome Atlas and Gene Expression Omnibus databases revealed that ZWINT is significantly expressed across a diverse range of tumor types. We subsequently investigated the influence of ZWINT on clinical outcomes and potential signaling pathways. A multidimensional analysis of ZWINT revealed significant statistical associations between ZWINT expression and clinical outcomes, as well as the E2F1 oncogenic signature. Experimental validation confirmed the increased expression of ZWINT in both pancreatic cancer cell lines and pancreatic adenocarcinoma tissues. Furthermore, our findings indicate that ZWINT promotes the proliferation of PANC-1 cells through cell cycle regulation. This comprehensive analysis of ZWINT suggests a strong correlation between its expression and various types of tumors, especially pancreatic adenocarcinoma (PAAD), indicating its potential oncogenic role. These findings enhance our understanding of the function of ZWINT in carcinogenesis.

Fucoxanthin Inhibits Development of Sigmoid Colorectal Cancer in a PDX Model With Alterations of Growth, Adhesion, and Cell Cycle Signals

BACKGROUND/AIM

Fucoxanthin (Fx), a dietary marine xanthophyll, exerts potent anticancer effects in various colorectal cancer (CRC) animal models. However, therapeutic effects of Fx in human cancer tissues remain unclear. A patient-derived xenograft (PDX) mouse model transplanted with cancer tissues from patients is widely accepted as the best preclinical model for evaluating the anticancer potential of drug candidates.

MATERIALS AND METHODS

Herein, we investigated the anticancer effects of Fx in PDX mice transplanted with cancer tissues derived from a patient with CRC (CRC-PDX) using LC-MS/MS- and western blot-based proteome analysis.

RESULTS

The tumor in the patient with CRC was a primary adenocarcinoma (T3N0M0, stage II) showing mutations of certain genes that were tumor protein p53 (TP53), AT-rich interaction domain 1A (ARID1A), neuroblastoma RAS viral oncogene homolog (NRAS), and PMS1 homolog 2 (PMS2). Administration of Fx significantly suppressed the tumor growth (0.6-fold) and tended to induce differentiation in CRC-PDX mice. Fx up-regulated glycanated-decorin (Gc-DCN) expression, and down-regulated Kinetochore-associated protein DSN1 homolog (DSN1), phospho(p) focal adhesion kinase (pFAK)(Tyr397), pPaxillin(Tyr31), and c-MYC involved in growth, adhesion, and/or cell cycle, in the tumors of CRC-PDX mice than in control mice. Alterations in the five proteins were consistent with those in human CRC HT-29 and HCT116 cells treated with fucoxanthinol (FxOH, a major metabolite of Fx).

CONCLUSION

Fx suppresses development of human-like CRC tissues, especially through growth, adhesion, and cell cycle signals.

Targeting serine- and arginine-rich splicing factors to rectify aberrant alternative splicing

Serine- and arginine-rich splicing factors are pivotal modulators of constitutive splicing and alternative splicing that bind to the cis-acting elements in precursor mRNAs and facilitate the recruitment and assembly of the spliceosome. Meanwhile, SR proteins shuttle between the nucleus and cytoplasm with a broad implication in multiple RNA-metabolizing events. Recent studies have demonstrated the positive correlation of overexpression and/or hyperactivation of SR proteins and development of the tumorous phenotype, indicating the therapeutic potentials of targeting SR proteins. In this review, we highlight key findings concerning the physiological and pathological roles of SR proteins. We have also investigated small molecules and oligonucleotides that effectively modulate the functions of SR proteins, which could benefit future studies of SR proteins.

Towards understandings of serine/arginine-rich splicing factors

Serine/arginine-rich splicing factors (SRSFs) refer to twelve RNA-binding proteins which regulate splice site recognition and spliceosome assembly during precursor messenger RNA splicing. SRSFs also participate in other RNA metabolic events, such as transcription, translation and nonsense-mediated decay, during their shuttling between nucleus and cytoplasm, making them indispensable for genome diversity and cellular activity. Of note, aberrant SRSF expression and/or mutations elicit fallacies in gene splicing, leading to the generation of pathogenic gene and protein isoforms, which highlights the therapeutic potential of targeting SRSF to treat diseases. In this review, we updated current understanding of SRSF structures and functions in RNA metabolism. Next, we analyzed SRSF-induced aberrant gene expression and their pathogenic outcomes in cancers and non-tumor diseases. The development of some well-characterized SRSF inhibitors was discussed in detail. We hope this review will contribute to future studies of SRSF functions and drug development targeting SRSFs.

Comparative analysis of quantitative phosphoproteomics between two tilapias (Oreochromis niloticus and Oreochromis aureus) under low-temperature stress

As an important farmed fish, tilapia has poor tolerance to low-temperatures. At the same time, different tilapia strains have apparent differences in low-temperature tolerance. In this study, using the iTRAQ method, the phosphorylated proteomics of two tilapia strains (Oreochromis niloticus and Oreochromis aureus) with different tolerances to low-temperature stress were quantitatively and comparatively analyzed, to clarify the physiological mechanism of tilapia's response to low-temperature stress. Through the GO and IPR analyses of differentially phosphorylated proteins, a number of similarities in physiological activities and regulatory effects were found between the two tilapias in response to low-temperature stress. Many differentially phosphorylated proteins are mainly involved in lipid metabolism, cell proliferation and apoptosis. However, the difference in endurance of low temperature of these two tilapias might be related to the differences in categories, expression and modification level of genetic products which were involved in the aforementioned physiological processes. And meanwhile, the enrichment results of KEGG showed the changes of multiple immune-related and growth-related phosphorylated proteins in the cytokine-cytokine receptor interaction pathway in O. aureus are more prominent. Furthermore, the significantly enriched pathway of carbohydrate digestion and absorption in O. niloticus may indicate that low-temperature stress exerts a more severe impact on energy metabolism. The relative results would help elucidating the molecular mechanism by which tilapia responds to low-temperature stress, and developing culture of tilapia species.

Insights into established and emerging roles of SR protein family in plants and animals

Splicing of pre-mRNA is an essential part of eukaryotic gene expression. Serine-/arginine-rich (SR) proteins are highly conserved RNA-binding proteins present in all metazoans and plants. SR proteins are involved in constitutive and alternative splicing, thereby regulating the transcriptome and proteome diversity in the organism. In addition to their role in splicing, SR proteins are also involved in mRNA export, nonsense-mediated mRNA decay, mRNA stability, and translation. Due to their pivotal roles in mRNA metabolism, SR proteins play essential roles in normal growth and development. Hence, any misregulation of this set of proteins causes developmental defects in both plants and animals. SR proteins from the animal kingdom are extensively studied for their canonical and noncanonical functions. Compared with the animal kingdom, plant genomes harbor more SR protein-encoding genes and greater diversity of SR proteins, which are probably evolved for plant-specific functions. Evidence from both plants and animals confirms the essential role of SR proteins as regulators of gene expression influencing cellular processes, developmental stages, and disease conditions. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing.

Effect of N6-methyladenosine (m6A) regulator-related immunogenes on the prognosis and immune microenvironment of breast cancer

Background

Breast cancer is one of the most common malignant tumor and the prognosis remains unsatisfying. Various studies demonstrate that m6A modulators are new predictors of prognosis in immune microenvironment. We aimed to identify several m6A regulator-related immunogenes and explore the relationship between m6A regulator-related immunogenes and breast cancer prognosis as well as the tumor immune microenvironment (TIME).

Methods

RNA sequencing data and clinical information on 21 m6A regulators in 1,047 breast cancer samples were downloaded from The Cancer Genome Atlas (TCGA), and immune gene data were downloaded from InnateDB. Kaplan-Meier survival analysis was conducted with log-rank test using the survival package. An m6A-related immunogene-prognostic signature was then constructed, followed by immune infiltration and checkpoint analyses.

Results

A risk prognostic signature of m6A regulator-related immunogenes, including TOX, PSME2, MCTS1, NFKBIE, SH3BP4, RSPH1, JAK1, MLLT4, and PTGES3, was constructed. Furthermore, univariate and multivariate Cox regression analyses suggested that the tumor stage and risk score could be independent prognostic factors for patients with breast cancer. Immune infiltration analysis showed that the infiltration levels of T cells, memory B cells, activated NK cells, and macrophages between the high- and low-risk groups were significantly different. In addition, checkpoint analyses demonstrated that the levels of immune checkpoint genes, such as those of LAG3, PDCD1, CTLA4, and HAVCR2, were downregulated in the high-risk group compared to those in the low-risk group.

Conclusions

Our findings suggest that the m6A regulator-related risk prognostic signature can predict the prognosis of breast cancer and that it is related to the immune microenvironment.

SR Splicing Factors Promote Cancer via Multiple Regulatory Mechanisms

Substantial emerging evidence supports that dysregulated RNA metabolism is associated with tumor initiation and development. Serine/Arginine-Rich proteins (SR) are a number of ultraconserved and structurally related proteins that contain a characteristic RS domain rich in arginine and serine residues. SR proteins perform a critical role in spliceosome assembling and conformational transformation, contributing to precise alternative RNA splicing. Moreover, SR proteins have been reported to participate in multiple other RNA-processing-related mechanisms than RNA splicing, such as genome stability, RNA export, and translation. The dysregulation of SR proteins has been reported to contribute to tumorigenesis through multiple mechanisms. Here we reviewed the different biological roles of SR proteins and strategies for functional rectification of SR proteins that may serve as potential therapeutic approaches for cancer.