Y-box binding protein 1 expression in gastric cancer subtypes and association with cancer neovasculature

YBX1 Regulates Satellite II RNA Loading into Small Extracellular Vesicles and Promotes the Senescent Phenotype

Senescent cells secrete inflammatory proteins and small extracellular vesicles (sEVs), collectively termed senescence-associated secretory phenotype (SASP), and promote age-related diseases. Epigenetic alteration in senescent cells induces the expression of satellite II (SATII) RNA, non-coding RNA transcribed from pericentromeric repetitive sequences in the genome, leading to the expression of inflammatory SASP genes. SATII RNA is contained in sEVs and functions as an SASP factor in recipient cells. However, the molecular mechanism of SATII RNA loading into sEVs is unclear. In this study, we identified Y-box binding protein 1 (YBX1) as a carrier of SATII RNA via mass spectrometry analysis after RNA pull-down. sEVs containing SATII RNA induced cellular senescence and promoted the expression of inflammatory SASP genes in recipient cells. YBX1 knockdown significantly reduced SATII RNA levels in sEVs and inhibited the propagation of SASP in recipient cells. The analysis of the clinical dataset revealed that YBX1 expression is higher in cancer stroma than in normal stroma of breast and ovarian cancer tissues. Furthermore, high YBX1 expression was correlated with poor prognosis in breast and ovarian cancers. This study demonstrated that SATII RNA loading into sEVs is regulated via YBX1 and that YBX1 is a promising target in novel cancer therapy.

YBX1 is required for maintaining myeloid leukemia cell survival by regulating BCL2 stability in an m6A-dependent manner

RNA-binding proteins (RBPs) are critical regulators of transcription and translation that are often dysregulated in cancer. Although RBPs are increasingly recognized as being important for normal hematopoiesis and for hematologic malignancies as oncogenes or tumor suppressors, RBPs that are essential for the maintenance and survival of leukemia remain elusive. Here we show that YBX1 is specifically required for maintaining myeloid leukemia cell survival in an N6-methyladenosine (m6A)-dependent manner. We found that expression of YBX1 is significantly upregulated in myeloid leukemia cells, and deletion of YBX1 dramatically induces apoptosis and promotes differentiation coupled with reduced proliferation and impaired leukemic capacity of primary human and mouse acute myeloid leukemia cells in vitro and in vivo. Loss of YBX1 has no obvious effect on normal hematopoiesis. Mechanistically, YBX1 interacts with insulin-like growth factor 2 messenger RNA (mRNA)-binding proteins (IGF2BPs) and stabilizes m6A-tagged RNA. Moreover, YBX1 deficiency dysregulates the expression of apoptosis-related genes and promotes mRNA decay of MYC and BCL2 in an m6A-dependent manner, which contributes to the defective survival that results from deletion of YBX1. Thus, our findings have uncovered a selective and critical role of YBX1 in maintaining myeloid leukemia survival, which might provide a rationale for the therapeutic targeting of YBX1 in myeloid leukemia.

A comprehensive review of the functions of YB-1 in cancer stemness, metastasis and drug resistance

The Y Box binding protein 1 (YB-1) is a member of the highly conserved Cold Shock Domain protein family with multifunctional properties both in the cytoplasm and inside the nucleus. YB-1 is also involved in various cellular functions, including regulation of transcription, mRNA stability, and splicing. Recent studies have associated YB-1 with the regulation of the malignant phenotypes in several tumor types. In this review article, we provide an in-depth and expansive review of the literature pertaining to the multiple physiological functions of YB-1. We will also review the role of YB-1 in cancer development, progression, metastasis, and drug resistance in various malignancies, with more weight on literature published in the last decade. The methodology included querying databases PubMed, Embase, and Google Scholar for Y box binding protein 1, YB-1, YBX1, and Y-box-1.

FOLFOX Therapy Induces Feedback Upregulation of CD44v6 through YB-1 to Maintain Stemness in Colon Initiating Cells

Cancer initiating cells (CICs) drive tumor formation and drug-resistance, but how they develop drug-resistance characteristics is not well understood. In this study, we demonstrate that chemotherapeutic agent FOLFOX, commonly used for drug-resistant/metastatic colorectal cancer (CRC) treatment, induces overexpression of CD44v6, MDR1, and oncogenic transcription/translation factor Y-box-binding protein-1 (YB-1). Our study revealed that CD44v6, a receptor for hyaluronan, increased the YB-1 expression through PGE2/EP1-mTOR pathway. Deleting CD44v6, and YB-1 by the CRISPR/Cas9 system attenuates the in vitro and in vivo tumor growth of CICs from FOLFOX resistant cells. The results of DNA:CD44v6 immunoprecipitated complexes by ChIP (chromatin-immunoprecipitation) assay showed that CD44v6 maintained the stemness traits by promoting several antiapoptotic and stemness genes, including cyclin-D1,BCL2,FZD1,GINS-1, and MMP9. Further, computer-based analysis of the clones obtained from the DNA:CD44v6 complex revealed the presence of various consensus binding sites for core stemness-associated transcription factors “CTOS” (c-Myc, TWIST1, OCT4, and SOX2). Simultaneous expressions of CD44v6 and CTOS in CD44v6 knockout CICs reverted differentiated CD44v6-knockout CICs into CICs. Finally, this study for the first time describes a positive feedback loop that couples YB-1 induction and CD44 alternative splicing to sustain the MDR1 and CD44v6 expressions, and CD44v6 is required for the reversion of differentiated tumor cells into CICs.

YB-1 transferred by gastric cancer exosomes promotes angiogenesis via enhancing the expression of angiogenic factors in vascular endothelial cells

Background

Angiogenesis is important for the progression of gastric cancer (GC). Y-box binding protein 1 (YB-1) predicts advanced disease and indicates neovasculature formation in GC tissues, while the related mechanisms remain elusive. Exosomes mediate intercellular communications via transferring various molecules including proteins, lipids, mRNAs, and microRNAs, while the cargos of GC exosomes and the related mechanisms in GC angiogenesis were rarely reported except for several microRNAs.

Methods

In this study, human umbilical vein endothelial cells (HUVECs) were, respectively, treated by the exosomes isolated from the YB-1 transfected and the control SGC-7901 cells (SGC-7901-OE-Exo and SGC-7901-NC-Exo), and their apoptosis, proliferation, migration, invasion, and angiogenesis were, sequentially, compared. The levels of angiogenic factors including VEGF, Ang-1, MMP-9 and IL-8 in the exosome-treated HUVECs and the GC-derived exosomes were, separately, detected using PCR and Western blotting as well as RNA sequencing assays.

Results

We observed the consistent level of YB-1 in the exosomes and their originated GC cells, and the internalization of exosomes into HUVECs. Comparing with SGC-7901-NC-Exo, SGC-7901-OE-Exo significantly inhibited the apoptosis but promoted the proliferation, migration, invasion, and angiogenesis of HUVECs, within which the increased mRNA and protein levels of VEGF, Ang-1, MMP-9 and IL-8 were demonstrated. Meanwhile, mRNA levels of VEGF, Ang-1, MMP-9 and IL-8 showed no significant difference between SGC-7901-NC-Exo and SGC-7901-OE-Exo, although statistically higher mRNA of YB-1 was detected in the SGC-7901-OE-Exo.

Conclusions

Our findings illustrate YB-1 as the key component of exosome to promote GC angiogenesis by upregulating specific angiogenic factors in the exosome-treated endothelial cells but not in the exosomes themselves.

A Novel Ten-Gene Signature Predicting Prognosis in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) has a dismal long-term outcome. We aimed to construct a multi-gene model for prognosis prediction to inform HCC management. The cancer-specific differentially expressed genes (DEGs) were identified using RNA-seq data of paired tumor and normal tissue. A prognostic signature was built by LASSO regression analysis. Gene set enrichment analysis (GSEA) was performed to further understand the underlying molecular mechanisms. A 10-gene signature was constructed to stratify the TCGA and ICGC cohorts into high- and low-risk groups where prognosis was significantly worse in the high-risk group across cohorts (P < 0.001 for all). The 10-gene signature outperformed all previously reported models for both C-index and the AUCs for 1-, 3-, 5-year survival prediction (C-index, 0.84 vs 0.67 to 0.73; AUCs for 1-, 3- and 5-year OS, 0.84 vs 0.68 to 0.79, 0.81 to 0.68 to 0.80, and 0.85 vs 0.67 to 0.78, respectively). Multivariate Cox regression analysis revealed risk group and tumor stage to be independent predictors of survival in HCC. A nomogram incorporating tumor stage and signature-based risk group showed better performance for 1- and 3-year survival than for 5-year survival. GSEA revealed enrichment of pathways related to cell cycle regulation among high-risk samples and metabolic processes in the low-risk group. Our 10-gene model is robust for prognosis prediction and may help inform clinical management of HCC.

Depletion of WNT10A Prevents Tumor Growth by Suppressing Microvessels and Collagen Expression

Background: We recently reported that WNT10A plays a pivotal role in wound healing by regulating collagen expression/synthesis, as the depletion of WNT10A dramatically delays skin ulcer formation. WNT signaling also has a close correlation with the cancer microenvironment and proliferation, since tumors are actually considered to be 'unhealing' or 'overhealing' wounds. To ascertain the in vivo regulatory functions of WNT10A in tumor growth, we examined the net effects of WNT10A depletion using Wnt10a-deficient mice (Wnt10a ^-/-). Methods and Results: We subjected C57BL/6J wild-type (WT) or Wnt10a ^-/- mice to murine melanoma B16-F10 cell transplantation. Wnt10a ^-/- mice showed a significantly smaller volume of transplanted melanoma as well as fewer microvessels and less collagen expression and more necrosis than WT mice. Conclusions: Taken together, our observations suggest that critical in vivo roles of Wnt10a-depleted anti-stromagenesis prevent tumor growth, in contrast with true wound healing/scarring.

Aloe-emodin inhibits HER-2 expression through the downregulation of Y-box binding protein-1 in HER-2-overexpressing human breast cancer cells

Human epidermal growth factor receptor-2 (HER-2)-positive breast cancer tends to be aggressive, highly metastatic, and drug resistant and spreads rapidly. Studies have indicated that emodin inhibits HER-2 expression. This study compared the HER-2-inhibitory effects of two compounds extracted from rhubarb roots: aloe-emodin (AE) and rhein. Our results indicated that AE exerted the most potent inhibitory effect on HER-2 expression. Treatment of HER-2-overexpressing breast cancer cells with AE reduced tumor initiation, cell migration, and cell invasion. AE was able to suppress YB-1 expression, further suppressing downstream HER-2 expression. AE suppressed YB-1 expression through the inhibition of Twist in HER-2-overexpressing breast cancer cells. Our data also found that AE inhibited cancer metastasis and cancer stem cells through the inhibition of EMT. Interestingly, AE suppressed YB-1 expression through the downregulation of the intracellular integrin-linked kinase (ILK)/protein kinase B (Akt)/mTOR signaling pathway in HER-2-overexpressing breast cancer cells. In vivo study showed the positive result of antitumor activity of AE in nude mice injected with human HER-2-overexpressing breast cancer cells. These findings suggest the possible application of AE in the treatment of HER-2-positive breast cancer.

YBX1 promotes tumor growth by elevating glycolysis in human bladder cancer

Aerobic glycolysis, also known as Warburg effect, is a key hallmark of cancers. The Y-box-binding protein 1 (YBX1) is a well-known oncoprotein implicated in multiple malignant phenotypes of cancers. Meanwhile, little is known about the oncogenic functions and mechanisms of YBX1 in bladder cancer. Based on gene set enrichment analysis (GSEA) of TCGA RNAseq data, we find that YBX1 was profoundly involved in the glycolysis part of glucose metabolism. Loss- and gain-of-function studies show that YBX1 can enhance glycolysis as revealed by expression of glycolytic enzymes, glucose uptake, lactate secretion and extracellular acidification rate (ECAR). Inhibition of glycolysis completely compromises the tumor-promoting effect of YBX1 on tumor growth. Mechanistically, YBX1 regulates the expression of c-Myc and HIF1α, which further upregulate glycolytic enzymes to facilitate glycolysis. Moreover, in vivo study further confirms that genetic silencing of YBX1 markedly attenuates tumor growth and this tumor-suppressive effect is largely dependent on reduced glycolysis. Taken together, these results, as a proof of principle, provide a novel insight into the oncogenic role of YBX1 in glycolysis and suggest the potential therapeutic strategy by targeting YBX1 in bladder cancer.

Potential Biomarkers in Diagnosis of Human Gastric Cancer

The high incidence of gastric cancer (GC) and its consequent mortality rate severely threaten human's health. It is not frequently diagnosed until a relatively advanced stage. Surgery is the only potentially curative treatment. Thus, early screening and diagnosis are critical for patients with GC. The tumor marker assays used currently for detecting GC are simple and rapid, but the usage is limited by its low sensitivity and specificity. Here, we provide a brief description of some new potential markers and new biotechnological methods for the diagnosis of GC, hoping to find out more effective approaches for early detection of GC.

Unraveling Molecular Differences of Gastric Cancer by Label-Free Quantitative Proteomics Analysis

Gastric cancer (GC) has significant morbidity and mortality worldwide and especially in China. Its molecular pathogenesis has not been thoroughly elaborated. The acknowledged biomarkers for diagnosis, prognosis, recurrence monitoring and treatment are lacking. Proteins from matched pairs of human GC and adjacent tissues were analyzed by a coupled label-free Mass Spectrometry (MS) approach, followed by functional annotation with software analysis. Nano-LC-MS/MS, quantitative real-time polymerase chain reaction (qRT-PCR), western blot and immunohistochemistry were used to validate dysregulated proteins. One hundred forty-six dysregulated proteins with more than twofold expressions were quantified, 22 of which were first reported to be relevant with GC. Most of them were involved in cancers and gastrointestinal disease. The expression of a panel of four upregulated nucleic acid binding proteins, heterogeneous nuclear ribonucleoprotein hnRNPA2B1, hnRNPD, hnRNPL and Y-box binding protein 1 (YBX-1) were validated by Nano-LC-MS/MS, qRT-PCR, western blot and immunohistochemistry assays in ten GC patients’ tissues. They were located in the keynotes of a predicted interaction network and might play important roles in abnormal cell growth. The label-free quantitative proteomic approach provides a deeper understanding and novel insight into GC-related molecular changes and possible mechanisms. It also provides some potential biomarkers for clinical diagnosis.

The Role of the Y Box Binding Protein 1 C-Terminal Domain in Vascular Endothelial Cell Proliferation, Apoptosis, and Angiogenesis

Different domains of the multifunctional transcription factor Y-box binding protein 1 (YB1) regulate proliferation, differentiation, and apoptosis by transactivating or repressing the promoters of various genes. Here we report that the C-terminal domain of YB1 (YB1 CTD) is involved in endothelial cell proliferation, apoptosis, and tube formation. The oligo pull-down assays demonstrated that YB1 directly binds double-stranded GC box sequences in endothelial cells through the 125-220 amino acids. Adenovirus expression vectors harboring green fluorescent protein (GFP) or GFP-tagged YB1 CTD were constructed and used to infect EA.hy926 endothelial cells. Overexpression of the YB1 CTD significantly increased p21 expression, decreased cyclin B1 expression, and inhibited the proliferation of EA.hy926 cells. YB1 CTD overexpression also increased Bax and active caspase 3 expression, decreased Bcl-2 expression, and induced apoptosis in EA.hy926 cells. Furthermore, overexpression of the YB1 CTD significantly suppressed migration and tube formation in EA.hy926 cells. Finally, YB1 CTD decreased ERK1/2 phosphorylation in EA.hy926 cells. These findings demonstrated vital roles for YB1 in endothelial cell proliferation, apoptosis, and tube formation through transcriptional regulation of GC box-related genes.

Mitochondrial Transcription Factor A and Mitochondrial Genome as Molecular Targets for Cisplatin-Based Cancer Chemotherapy

Mitochondria are important cellular organelles that function as control centers of the energy supply for highly proliferative cancer cells and regulate apoptosis after cancer chemotherapy. Cisplatin is one of the most important chemotherapeutic agents and a key drug in therapeutic regimens for a broad range of solid tumors. Cisplatin may directly interact with mitochondria, which can induce apoptosis. The direct interactions between cisplatin and mitochondria may account for our understanding of the clinical activity of cisplatin and development of resistance. However, the basis for the roles of mitochondria under treatment with chemotherapy is poorly understood. In this review, we present novel aspects regarding the unique characteristics of the mitochondrial genome in relation to the use of platinum-based chemotherapy and describe our recent work demonstrating the importance of the mitochondrial transcription factor A (mtTFA) expression in cancer cells.

Role of post-translational modification of the Y box binding protein 1 in human cancers

Y box binding protein-1 (YBX1) belongs to a DNA- and RNA-binding family of transcription factors, containing the highly conserved cold shock domain (CSD). YBX1 is involved in a number of cellular functions including transcription, translation, DNA damage repair etc., and it is upregulated during times of environmental stress. YBX1 is localized in both the cytoplasm and the nucleus. There, its nuclear translocation is observed in a number of cancers and is associated with poor prognosis and disease progression. Additionally, YBX1 expression is upregulated in a variety of cancers, pointing towards its role as a potential oncogene. Under certain circumstances, YBX1 also promotes the expression of multidrug resistance 1 (MDR1) gene, which is involved in the development of drug resistance. Thus, it is critical to understand the mechanism of YBX1 regulation and its downstream effects on promoting cancer development. A number of recent studies have highlighted the mechanisms of YBX1 regulation. Mass spectrometric analyses have reported several post-translational modifications that possibly play an important role in modulating YBX1 function. Phosphorylation is the most widely occurring post-translational modification in YBX1. In vivo analyses of sites like S102 and more recently, S165 illustrate the relationship of post-translational regulation of YBX1 in promoting cell proliferation and tumor growth. This review provides a comprehensive and up-to-date account of post-translational modifications identified in YBX1. This knowledge is a key in allowing us to better understand the mechanism of YBX1 regulation, which will aid in development of novel therapeutic strategies to target YBX1 in many types of cancer in the future.