Overexpression of Transmembrane Protein BST2 is Associated with Poor Survival of Patients with Esophageal, Gastric, or Colorectal Cancer

Identification and validation of immune-related and inflammation-related genes in endometriosis

Aim

Endometriosis is characterized by immune evasion and progressive inflammation. This study aimed to identify key genes related to immune and inflammation in endometriosis.

Methods

Differentially expressed genes between patients with and without endometriosis were identified from the GEO database. Furthermore, immune- and inflammation-related genes (IRGs) were identified by intersecting the differentially expressed genes with known immune and inflammatory genes. Functional analyses of the GO and KEGG pathways of these genes were performed. Subsequently, three machine learning models-LASSO regression, SVM-RFE, and Boruta-were conducted to identify the potential key genes in endometriosis. Finally, the expressions of key genes in endometriosis were verified in two validation cohorts using an online database and qRT-PCR, and their immunoregulatory properties were verified.

Results

A total of 13 differentially expressed IRGs were identified. Using machine learning algorithms, five key genes were selected in the endometriosis: BST2, IL4R, INHBA, PTGER2, and MET. Furthermore, the three hub genes exhibited consistent trends across both training and validation datasets. The three keys also correlated with infiltrated immune cells, checkpoint genes, and immune factors in various degrees. Finally, validation analysis using the online database and qRT-PCR confirmed that MET expression aligned with outcomes from both training and validation datasets.

Conclusion

Three immune- and inflammation-related genes were identified as potential biomarkers of endometriosis, providing new insights into the molecular mechanisms underlying immune function in endometriosis. The immune-related function of MET, particularly its correlation with NK cell activity in endometriosis, will be the focus of future studies.

Novel Diagnostic Biomarker BST2 Identified by Integrated Transcriptomics Promotes the Development of Endometriosis via the TNF-α/NF-κB Signaling Pathway

Endometriosis (EMS) is a common gynecological condition with apparent heterogeneity, lack of diagnostic markers, and unclear pathogenesis. A series of bioinformatics methods were employed to explore EMS's pathological mechanisms and potential biomarkers by analyzing the combined datasets of EMS (GSE7305, GSE7307, GSE58198, E-MTAB-694), which included 34 normal, 127 eutopic, and 46 ectopic endometrium samples. Then, wet-laboratory experiments (including Western blot, qRT-PCR, and Immunohistochemistry, Immunofluorescence, CCK-8, EdU, Wound healing, Transwell, and Adhesion assays) were applied to examine the biomarkers' expression and function in primary endometrial stromal cells. Bioinformatic analysis indicated that the core pathogenesis of EMS was dysregulated immune-inflammation and tissue remolding processes. Among the upregulated DEGs, BST2 was screened as a potential diagnostic biomarker in EMS, which associated with the revised American Fertility Society (r-AFS) stage and immune-inflammation processes of EMS. Moreover, BST2's overexpression was affirmed in the RNA and protein levels in EMS tissues. In vitro experiments demonstrated that TNF-α promoted the expression of BST2 in ESCs. And BST2 knockdown inhibited migration, invasion, adhesion, and inflammation except for the proliferation of ESCs, probably via the TNF-α/NF-κB pathway. Through a combination of wet and dry studies, we concluded that the core pathogenesis of endometriosis was dysregulated immune-inflammation and tissue remolding, and BST2 might be a potential diagnostic and therapeutic target in endometriosis.

BST2 induces vascular smooth muscle cell plasticity and phenotype switching during cancer progression

Background

Smooth muscle cell (SMC) plasticity and phenotypic switching play prominent roles in the pathogenesis of multiple diseases, but their role in tumorigenesis is unknown. We investigated whether and how SMC diversity and plasticity plays a role in tumor angiogenesis and the tumor microenvironment.

Methods and Results

We use SMC-specific lineage-tracing mouse models and single cell RNA sequencing to observe the phenotypic diversity of SMCs participating in tumor vascularization. We find that a significant proportion of SMCs adopt a phenotype traditionally associated with macrophage-like cells. These cells are transcriptionally similar to 'resolution phase' M2b macrophages, which have been described to have a role in inflammation resolution. Computationally predicted by the ligand-receptor algorithm CellChat, signaling from BST2 on the surface of tumor cells to PIRA2 on SMCs promote this phenotypic transition; in vitro SMC assays demonstrate upregulation of macrophage transcriptional programs, and increased proliferation, migration, and phagocytic ability when exposed to BST2. Knockdown of BST2 in the tumor significantly decreases the transition towards a macrophage-like phenotype, and cells that do transition have a comparatively higher inflammatory signal typically associated with anti-tumor effect.

Conclusion

As BST2 is known to be a poor prognostic marker in multiple cancers where it is associated with an M2 macrophage-skewed TME, these studies suggest that phenotypically switched SMCs may have a previously unidentified role in this immunosuppressive milieu. Further translational work is needed to understand how this phenotypic switch could influence the response to anti-cancer agents and if targeted inhibition of SMC plasticity would be therapeutically beneficial.

BST2 promotes gastric cancer metastasis under the regulation of HOXD9 and PABPC1

Gastric cancer (GC) constitutes substantial cancer mortality worldwide. Several cancer types aberrantly express bone marrow stromal cell antigen 2 (BST2), yet its functional and underlying mechanisms in GC progression remain unknown. In our study, RNA sequencing data revealed that BST2 was transcriptionally activated by homeobox D9 (HOXD9). BST2 was significantly upregulated in GC tissues and promoted epithelial-mesenchymal transition and metastasis of GC. BST2 knockdown reversed HOXD9's oncogenic effect on GC metastasis. Moreover, BST2 messenger RNA stability could be enhanced by poly(A) binding protein cytoplasmic 1 (PABPC1) through the interaction between BST2 3'-UTR and PABPC1 in GC cells. PABPC1 promoted GC metastasis, which BST2 silencing attenuated in vitro and in vivo. In addition, positive correlations among HOXD9, BST2, and PABPC1 were established in clinical samples. Taken together, increased expression of BST2 induced by HOXD9 synergizing with PABPC1 promoted GC cell migration and invasion capacity.

Inhibitory receptors of plasmacytoid dendritic cells as possible targets for checkpoint blockade in cancer

Plasmacytoid dendritic cells (pDCs) are the major producers of type I interferons (IFNs), which are essential to mount antiviral and antitumoral immune responses. To avoid exaggerated levels of type I IFNs, which pave the way to immune dysregulation and autoimmunity, pDC activation is strictly regulated by a variety of inhibitory receptors (IRs). In tumors, pDCs display an exhausted phenotype and correlate with an unfavorable prognosis, which largely depends on the accumulation of immunosuppressive cytokines and oncometabolites. This review explores the hypothesis that tumor microenvironment may reduce the release of type I IFNs also by a more pDC-specific mechanism, namely the engagement of IRs. Literature shows that many cancer types express de novo, or overexpress, IR ligands (such as BST2, PCNA, CAECAM-1 and modified surface carbohydrates) which often represent a strong predictor of poor outcome and metastasis. In line with this, tumor cells expressing ligands engaging IRs such as BDCA-2, ILT7, TIM3 and CD44 block pDC activation, while this blocking is prevented when IR engagement or signaling is inhibited. Based on this evidence, we propose that the regulation of IFN secretion by IRs may be regarded as an "innate checkpoint", reminiscent of the function of "classical" adaptive immune checkpoints, like PD1 expressed in CD8+ T cells, which restrain autoimmunity and immunopathology but favor chronic infections and tumors. However, we also point out that further work is needed to fully unravel the biology of tumor-associated pDCs, the neat contribution of pDC exhaustion in tumor growth following the engagement of IRs, especially those expressed also by other leukocytes, and their therapeutic potential as targets of combined immune checkpoint blockade in cancer immunotherapy.

Identification of BST2 as a conjunctival epithelial stem/progenitor cell marker

The conjunctival epithelium consists of conjunctival epithelial cells and goblet cells derived from conjunctival epithelial stem/progenitor cells. However, the source of these cells is not well known because no specific markers for conjunctival epithelial stem/progenitor cells have been discovered. Therefore, to identify conjunctival epithelial stem/progenitor cell markers, we performed single-cell RNA sequencing of a conjunctival epithelial cell population derived from human-induced pluripotent stem cells (hiPSCs). The following conjunctival epithelial markers were identified: BST2, SLC2A3, AGR2, TMEM54, OLR1, and TRIM29. Notably, BST2 was strongly positive in the basal conjunctival epithelium, which is thought to be rich in stem/progenitor cells. Moreover, BST2 was able to sort conjunctival epithelial stem/progenitor cells from hiPSC-derived ocular surface epithelial cell populations. BST2-positive cells were highly proliferative and capable of successfully generating conjunctival epithelial sheets containing goblet cells. In conclusion, BST2 has been identified as a specific marker of conjunctival epithelial stem/progenitor cells.

Increased Expression of the RBPMS Splice Variants Inhibits Cell Proliferation in Ovarian Cancer Cells

RNA-Binding Protein with Multiple Splicing (RBPMS) is a member of family proteins that bind to nascent RNA transcripts and regulate their splicing, localization, and stability. Evidence indicates that RBPMS controls the activity of transcription factors associated with cell growth and proliferation, including AP-1 and Smads. Three major RBPMS protein splice variants (RBPMSA, RBPMSB, and RBPMSC) have been described in the literature. We previously reported that reduced RBPMS levels decreased the sensitivity of ovarian cancer cells to cisplatin treatment. However, little is known about the biological role of the RBPMS splice variants in ovarian cancer cells. We performed RT-PCR and Western blots and observed that both RBPMSA and RBPMSC are reduced at the mRNA and protein levels in cisplatin resistant as compared with cisplatin sensitive ovarian cancer cells. The mRNA and protein levels of RBPMSB were not detectable in any of the ovarian cancer cells tested. To better understand the biological role of each RBPMSA and RBPMSC, we transfected these two splice variants in the A2780CP20 and OVCAR3CIS cisplatin resistant ovarian cancer cells and performed cell proliferation, cell migration, and invasion assays. Compared with control clones, a significant reduction in the number of colonies, colony size, cell migration, and invasion was observed with RBPMSA and RBPMSC overexpressed cells. Moreover, A2780CP20-RBPMSA and A2780CP20-RBPMSC clones showed reduced senescence-associated β-galactosidase (β-Gal)-levels when compared with control clones. A2780CP20-RBPMSA clones were more sensitive to cisplatin treatment as compared with A2780CP20-RBPMSC clones. The A2780CP20-RBPMSA and A2780CP20-RBPMSC clones subcutaneously injected into athymic nude mice formed smaller tumors as compared with A2780CP20-EV control group. Additionally, immunohistochemical analysis showed lower proliferation (Ki67) and angiogenesis (CD31) staining in tissue sections of A2780CP20-RBPMSA and A2780CP20-RBPMSC tumors compared with controls. RNAseq studies revealed many common RNA transcripts altered in A2780CP20-RBPMSA and A2780CP20-RBPMSC clones. Unique RNA transcripts deregulated by each RBPMS variant were also observed. Kaplan-Meier (KM) plotter database information identified clinically relevant RBPMSA and RBPMSC downstream effectors. These studies suggest that increased levels of RBPMSA and RBPMSC reduce cell proliferation in ovarian cancer cells. However, only RBPMSA expression levels were associated with the sensitivity of ovarian cancer cells to cisplatin treatment.

Dysregulated Expression of Three Genes in Colorectal Cancer Stratifies Patients into Three Risk Groups

Despite advances in recent years in the study of the molecular profile of sporadic colorectal cancer (sCRC), the specific genetic events that lead to increased aggressiveness or the development of the metastatic process of tumours are not yet clear. In previous studies of the gene expression profile (GEP) using a high-density array (50,000 genes and 6000 miRNAs in a single assay) in sCRC tumours, we identified a 28-gene signature that was found to be associated with an adverse prognostic value for predicting patient survival. Here, we analyse the differential expression of these 28 genes for their possible association with tumour local aggressiveness and metastatic processes in 66 consecutive sCRC patients, followed for >5 years, using the NanoString nCounter platform. The global transcription profile (expression levels of the 28 genes studied simultaneously) allowed us to discriminate between sCRC tumours and nontumoral colonic tissues. Analysis of the biological and functional significance of the dysregulated GEPs observed in our sCRC tumours revealed 31 significantly altered canonical pathways. Among the most commonly altered pathways, we observed the increased expression of genes involved in signalling pathways and cellular processes, such as the PI3K-Akt pathway, the interaction with the extracellular matrix (ECM), and other functions related to cell signalling processes (SRPX2). From a prognostic viewpoint, the altered expression of BST2 and SRPX2 genes were the only independent variables predicting for disease-free survival (DFS). In addition to the pT stage at diagnosis, dysregulated transcripts of ADH1B, BST2, and FER1L4 genes showed a prognostic impact on OS in the multivariate analysis. Based on the altered expression of these three genes, a scoring system was built to stratify patients into low-, intermediate-, and high-risk groups with significantly different 5-year OS rates: 91%, 83%, and 52%, respectively. The prognostic impact was validated in two independent series of sCRC patients from the public GEO database (n = 562 patients). In summary, we show a strong association between the altered expression of three genes and the clinical outcome of sCRC patients, making them potential markers of suitability for adjuvant therapy after complete tumour resection. Additional prospective studies in larger series of patients are required to confirm the clinical utility of the newly identified biomarkers because the number of patients analysed remains small.

Human Papillomavirus 16 E6 and E7 Oncoproteins Alter the Abundance of Proteins Associated with DNA Damage Response, Immune Signaling and Epidermal Differentiation

The high-risk human papillomaviruses are oncogenic viruses associated with almost all cases of cervical carcinomas, and increasing numbers of anal, and oral cancers. Two oncogenic HPV proteins, E6 and E7, are capable of immortalizing keratinocytes and are required for HPV associated cell transformation. Currently, the influence of these oncoproteins on the global regulation of the host proteome is not well defined. Liquid chromatography coupled with quantitative tandem mass spectrometry using isobaric-tagged peptides was used to investigate the effects of the HPV16 oncoproteins E6 and E7 on protein levels in human neonatal keratinocytes (HEKn). Pathway and gene ontology enrichment analyses revealed that the cells expressing the HPV oncoproteins have elevated levels of proteins related to interferon response, inflammation and DNA damage response, while the proteins related to cell organization and epithelial development are downregulated. This study identifies dysregulated pathways and potential biomarkers associated with HPV oncoproteins in primary keratinocytes which may have therapeutic implications. Most notably, DNA damage response pathways, DNA replication, and interferon signaling pathways were affected in cells transduced with HPV16 E6 and E7 lentiviruses. Moreover, proteins associated with cell organization and differentiation were significantly downregulated in keratinocytes expressing HPV16 E6 + E7. High-risk HPV E6 and E7 oncoproteins are necessary for the HPV-associated transformation of keratinocytes. However their influence on the global dysregulation of keratinocyte proteome is not well documented. Here shotgun proteomics using TMT-labeling detected over 2500 significantly dysregulated proteins associated with E6 and E7 expression. Networks of proteins related to interferon response, inflammation and DNA damage repair pathways were altered.

Single-Cell RNA Sequencing Reveals the Role of Epithelial Cell Marker Genes in Predicting the Prognosis of Colorectal Cancer Patients

Single-cell RNA sequencing (scRNA-seq) is increasingly used in studies on gastrointestinal cancers. This study investigated the prognostic value of epithelial cell-associated biomarkers in colorectal cancer (CRC) using scRNA-seq data. We downloaded and analysed scRNA-seq data from four CRC samples from the Gene Expression Omnibus (GEO), and we identified marker genes of malignant epithelial cells (MECs) using CRC transcriptome and clinical data downloaded from The Cancer Genome Atlas (TCGA) and GEO as training and validation cohorts, respectively. In the TCGA training cohort, weighted gene correlation network analysis, univariate Cox proportional hazard model (Cox) analysis, and least absolute shrinkage and selection operator regression analysis were performed on the marker genes of MEC subsets to identify a signature of nine prognostic MEC-related genes (MECRGs) and calculate a risk score based on the signature. CRC patients were divided into high- and low-risk groups according to the median risk score. We found that the MECRG risk score was significantly correlated with the clinical features and overall survival of CRC patients, and that CRC patients in the high-risk group showed a significantly shorter survival time. The univariate and multivariate Cox regression analyses showed that the MECRG risk score can serve as an independent prognostic factor for CRC patients. Gene set enrichment analysis revealed that the MECRG signature genes are involved in fatty acid metabolism, p53 signalling, and other pathways. To increase the clinical application value, we constructed a MECRG nomogram by combining the MECRG risk score with other independent prognostic factors. The validity of the nomogram is based on receiver operating characteristics and calibration curves. The MECRG signature and nomogram models were well validated in the GEO dataset. In conclusion, we established an epithelial cell marker gene-based risk assessment model based on scRNA-seq analysis of CRC samples for predicting the prognosis of CRC patients.

Bone marrow stromal cell antigen 2(BST2) suppresses the migration and invasion of trophoblasts in preeclampsia by downregulating matrix metallopeptidase 2(MMP2)

Preeclampsia is a grievous pregnancy-related complication with an incidence of approximately 5∼7% in pregnant women. Placental abnormalities and decreased placental perfusion associated with impaired trophoblast invasion are early pathological findings of preeclampsia. BST2 is a multifunctional transmembrane protein that plays critical roles in physiological and pathological processes, but its impacts and mechanisms of action in preeclampsia are inadequately understood. The aim of this manuscript was to investigate the functional impacts of BST2 and MMP2 on the biological behavior of trophoblast cells in preeclampsia. The expression of these proteins and their genes was analyzed by qRT-PCR, western blotting and immunohistochemistry. The results showed that the expression of BST2 and MMP2 was significantly downregulated in preeclampsia. The migration and invasion capacities of HTR-8/SVneo and JAR cells with overexpression or knockdown of BST2 were detected by wound healing assay and Transwell assays. It was found that BST2 overexpression could up-regulate MMP2 expression, and enhance the migration and invasion capacity of HTR-8/SVneo and JAR cells. BST2 knockdown could reverse these effects. MMP2 knockdown could downregulate the invasion capacity of HTR-8/SVneo cells, and MMP2 overexpression reversed these effects. Pearson correlation analysis demonstrated that the expression of MMP2 and BST2 were positively correlated. These results indicate that the downregulation of BST2 lowers MMP2 expression and restraint trophoblast functions, which probably explain its role in the pathogenesis of preeclampsia.

Activation of FGD5-AS1 Promotes Progression of Cervical Cancer through Regulating BST2 to Inhibit Macrophage M1 Polarization

Accumulating evidence has elucidated the biological function of lncRNAs in various tumors. FGD5 antisense RNA 1 (FGD5-AS1) is identified as a significant tumor regulator in malignancies. Up to now, the detailed function of FGD5-AS1 in cervical cancer and its underlying molecular mechanisms remain uninvestigated. Bone marrow stromal cell antigen 2 (BST2) can play critical roles in immune response, and the roles of BST2 in cervical cancer was explored currently. The level of FGD5-AS1 and BST2 was detected by qRT-PCR in cervical cancer cells. FGD5-AS1 and BST2 expression was significantly upregulated in cervical cancer cells. Then, the decrease of FGD5-AS1 greatly repressed cervical cancer cell growth in vitro. In addition, FGD5-AS1 silencing repressed BST2 expression and suppressed M2 macrophage polarization. Mechanistically, we confirmed that FGD5-AS1 sponged miR-129-5p to reduce its inhibition on BST2. Furthermore, lack of BST2 depressed cervical cancer cell growth, while inducing apoptosis. Loss of BST2 induced M1 macrophage polarization while blocking M2 macrophage polarization. For another, we demonstrated that FGD5-AS1-triggered M2 macrophage polarization was remarkably reversed by miR-129-5p via suppressing BST2. In conclusion, FGD5-AS1 induced M2 macrophage polarization via sponging miR-129-5p and modulating BST2, thus contributing to cervical cancer development. Our findings revealed FGD5-AS1/miR-129-5p/BST2 as a new potential target for cervical cancer.

Total ginsenosides induce autophagic cell death in cervical cancer cells accompanied by downregulation of bone marrow stromal antigen-2

Ginsenosides are important active components in Panax ginseng. In the present study, total ginsenosides (TGNs) were demonstrated to enhance autophagy by promoting acidic vacuole organelle formation, recruitment of enhanced green fluorescent protein-microtubule-associated protein light chain 3 and expression of autophagy-related factors in cervical cancer cell lines. TGN markedly increased the expression of p62 at the transcriptional level, but decreased p62 protein expression in the presence of actinomycin D. The autophagic regulatory effect was reversible. TGN (≤120 µg/ml) did not affect the proliferation of cervical cancer cells under normal culture conditions, but markedly inhibited the growth of serum-deprived cells. Treatment with an inhibitor of autophagy (3-methyladenine) impaired TGN-induced cell death. This suggested that TGN caused autophagic cell death. In addition, western blot analysis demonstrated that the protein level of bone marrow stromal antigen-2 (BST-2) was downregulated by TGN. Upregulation of BST-2 reduced cell death. The results of the combined actions of various monomeric ginsenosides in TGN provide the molecular basis to develop TGN as a promising candidate for cancer therapy.

Increased BST-2 expression by HBV infection promotes HBV-associated HCC tumorigenesis

BACKGROUND

The majority of hepatocellular carcinoma (HCC) is closely associated with hepatitis B virus (HBV) infection, while the mechanism of HCC induced by HBV is debatable. Bone marrow stromal cell antigen 2 (BST-2), an N-glycoprotein, has been characterized as an oncogenic factor in several types of cancer. However, whether BST-2 plays an important role in HCC tumorigenesis remains unknown.

METHODS

A total of 182 HCC tumorous and adjacent nontumor liver tissues were collected. HepG2, Huh7, L02, HepAD38, and HEK293T cell lines were adopted in this study. Tumor proliferation was detected by CCK8, transwell, wound healing, colony formation assays in vitro, and in vivo tumorigenesis was measured by mouse xenografts. NF-κB activation was determined by luciferase assay and Western blot. Protein expression was detected by Western blot, ELISA, or qPCR. Immunoprecipitation was used to confirm the interaction between BST-2 and Syk.

RESULTS

Here, we observed the higher BST-2 expression in HBV-infected HCC than their paired adjacent tissues and HBV-uninfected HCC tissues, particularly more aberrant non-N-glycosylated BST-2 in HBV-infected HCC tumors. We also observed the increased ER degradation-enhancing α-mannosidase-like protein 3 (EDEM3), which is trimming of N-linked glycans by sequential removal of mannose residues, might result in more non-N-glycosylated form of BST-2. Moreover, we demonstrated that BST-2 and non-N-glycosylated BST-2 N65/92A mutant, not only enhanced the tumor characteristics of hepatoma cell lines in vitro, but also enhanced the growth of mouse xenografts in vivo. Mechanically, N65/92A mutant has stronger ability to promote HCC than BST-2 via NF-κB/ERK1/2 but not NF-κB/anti-apoptotic factors pathway. NF-κB inhibitor attenuated BST-2-mediated tumorigenesis of HCC.

CONCLUSIONS

Our findings illuminate the novel function of BST-2 as an oncogene of HBV-associated HCC, and highlight the novel relationship of N-glycosylation of BST-2 in regulating HCC tumorigenesis in vitro.

Development of a Cationic Amphiphilic Helical Peptidomimetic (B18L) As A Novel Anti-Cancer Drug Lead

BST-2 is a novel driver of cancer progression whose expression confers oncogenic properties to breast cancer cells. As such, targeting BST-2 in tumors may be an effective therapeutic approach against breast cancer. Here, we sought to develop potent cytotoxic anti-cancer agent using the second-generation BST-2-based anti-adhesion peptide, B18, as backbone. To this end, we designed a series of five B18-derived peptidomimetics. Among these, B18L, a cationic amphiphilic α-helical peptidomimetic, was selected as the drug lead because it displayed superior anti-cancer activity against both drug-resistant and drug-sensitive cancer cells, with minimal toxicity on normal cells. Probing mechanism of action using molecular dynamics simulations, biochemical and membrane biophysics studies, we observed that B18L binds BST-2 and possesses membranolytic characteristics. Furthermore, molecular biology studies show that B18L dysregulates cancer signaling pathways resulting in decreased Src and Erk1/2 phosphorylation, increased expression of pro-apoptotic Bcl2 proteins, caspase 3 cleavage products, as well as processing of the caspase substrate, poly (ADP-ribose) polymerase-1 (PARP-1), to the characteristic apoptotic fragment. These data indicate that through the coordinated regulation of membrane, mitochondrial and signaling events, B18L executes cancer cell death and thus has the potential to be developed into a potent and selective anti-cancer compound.

Bone Marrow Stromal Antigen 2 is a Potential Unfavorable Prognostic Factor for High-Grade Glioma

BACKGROUND

Bone marrow stromal antigen 2 (BST2) is considered as a transmembrane glycoprotein and plays essential roles in innate immunity. It has been recently reported that up-regulation of BST2 was associated with the development of breast carcinoma. However, the clinical significance of BST2 in glioma has not been identified. The purpose of the present study is to explore the expression pattern and the role of BST2 in the progression of high-grade glioma.

METHODS

Expression levels of BST2 were tested in glioma tissues by analyzing the GEO database and immunohistochemistry staining. The prognostic role of BST2 in glioma was evaluated through univariate and multivariate analyses. In vitro and in vivo assays were conducted to confirm the role of BST2 on promoting glioma proliferation.

RESULTS

The mRNA level of BST2 was higher in glioma tissues than that in nontumorous brain tissues. High protein level of BST2 was correlated with larger tumor size and advanced WHO grade. Glioma patients with a high BST2 level had worse overall survival. In addition, BST2 was defined as an independent risk factor for glioma prognosis. Cellular and xenograft studies revealed that BST2 can significantly promote glioma proliferation.

CONCLUSION

Our study revealed that a high BST2 expression level was closely related to the unfavorable clinical features and poor prognosis of high-grade glioma patients. BST2 may serve as an invaluable prognostic indicator and novel therapeutic target for glioma treatment considering its membrane localization.

SPC18 Expression Is an Independent Prognostic Indicator of Patients with Esophageal Squamous Cell Carcinoma

OBJECTIVES

Esophageal cancer is the sixth most common malignancy worldwide. Signal peptidase complex 18 (SPC18) protein, which is encoded by the SEC11A gene, is one of the subunits of the signal peptidase complex and plays an important role in the secretion of proteins including transforming growth factor α (TGF-α). In this study, we investigated the significance of SPC18 expression in human esophageal squamous cell carcinoma (ESCC).

METHODS

SPC18 expression was examined by immunohistochemistry. RNA interference was used to inhibit SPC18 expression in ESCC cell lines. To examine cell viability, we performed 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. The effects of SPC18 inhibition on epidermal growth factor receptor (EGFR) signaling were analyzed by Western blot.

RESULTS

In total, 46 (50%) of 92 ESCC cases were positive for SPC18. SPC18 staining was observed more frequently in stage II/III/IV cases than in stage I cases (p = 0.028). We found that SPC18 expression was significantly associated with increased cancer-specific mortality (p = 0.006, log-rank test). SPC18 expression was frequently found in EGFR-positive cases compared with EGFR-negative cases. Cell proliferation and EGFR signaling were inhibited by SPC18 knockdown.

CONCLUSION

Specific inhibitors of SPC18 may be promising anticancer drugs for patients with ESCC.

BST2 Promotes Tumor Growth via Multiple Pathways in Hepatocellular Carcinoma

Bone marrow stromal antigen 2 (BST2) is a transmembrane glycoprotein and plays an essential role in innate immunity. Here we firstly found that BST2 expression was significantly elevated in hepatocellular carcinoma (HCC) tissues. High BST2 was closely related to the larger tumor size and more tumor number. Moreover, HCC patients with higher expression of BST2 had poorer overall survival and BST2 was identified as an independent unfavorable prognosis factor. Finally, we demonstrated that BST2 can promote proliferation capacity of tumor cells. In conclusion, HCC patients with higher BST2 expression were more predisposed to poorer clinical symptoms and unfavorable prognosis.

Alternative splicing of LSD1+8a in neuroendocrine prostate cancer is mediated by SRRM4

Neuroendocrine prostate cancer (NEPC) is the most virulent form of prostate cancer. Importantly, our recent work examining metastatic biopsy samples demonstrates NEPC is increasing in frequency. In contrast to prostate adenocarcinomas that express a luminal gene expression program, NEPC tumors express a neuronal gene expression program. Despite this distinction, the diagnosis of NEPC is often challenging, demonstrating an urgent need to identify new biomarkers and therapeutic targets. Our prior work demonstrated that the histone demethylase LSD1 (KDM1A) is important for survival of prostate adenocarcinomas, but little was known about LSD1's role in NEPC. Recently, a neural-specific transcript variant of LSD1-LSD1+8a-was discovered and demonstrated to activate neuronal gene expression in neural cells. The splicing factor SRRM4 was previously shown to promote LSD1+8a splicing in neuronal cells, and SRRM4 promotes NEPC differentiation and cell survival. Therefore, we sought to determine if LSD1+8a might play a role in NEPC and whether LSD1+8a splicing was linked to SRRM4. To investigate a potential role for LSD1+8a in NEPC, we examined a panel of prostate adenocarcinoma and NEPC patient-derived xenografts and metastatic biopsies. LSD1+8a was expressed exclusively in NEPC samples and correlated significantly with elevated expression of SRRM4. Using SRRM4-overexpressing cell lines, we determined that SRRM4 mediates alternative splicing of LSD1+8a. Finally, using gain of function studies, we confirmed that LSD1+8a and SRRM4 co-regulate target genes distinct from canonical LSD1. Our findings suggest further study of the interplay between SRRM4 and LSD1+8a and mechanisms by which LSD1+8a regulates gene expression in NEPC is warranted.

DNA-methylated gene markers for colorectal cancer in TCGA database

Colorectal cancer (CRC) is characterized by the accumulation of genetic and epigenetic alterations in neoplastic processes. DNA methylation, as an important epigenetic process, contributes to the development of CRC. In the present study, the epigenetic landscape of genes in CRC was characterized by analyzing the dataset from The Cancer Genome Atlas database and 177 DNA-methylated genes were screened based on the criterion of the Pearson correlation (R) between expression and methylation levels being >0.4. Pathway enrichment analysis revealed prominent pathways, including transcription and metabolism, further implying their significant role in tumorigenesis. Among the methylated genes, only zinc finger protein (ZNF)726 with aberrant expression was determined to affect overall survival (OS) as well as disease-free survival of patients with CRC. In addition, ZNF726 was identified as an independent prognostic risk factor for OS in patients with CRC. The methylation-based regulation of ZNF726 expression in CRC cells was further assessed using the Cancer Cell Line Encyclopedia database. Finally, the CpG island methylation of the ZNF726 promoter was evaluated to further elucidate its role in the development of CRC. In conclusion, the epigenetic landscape of genes in terms of promoter methylation in CRC was characterized, revealing that aberrant expression of ZNF726 may be an independent prognostic risk factor for OS in patients with CRC.

Integrated Whole Transcriptome Profiling and Bioinformatics Analysis for Revealing Regulatory Pathways Associated With Quercetin-Induced Apoptosis in HCT-116 Cells

Quercetin (QUE) is a bioactive component that belongs to the natural flavonoids group, and recent researchers found that it could prevent colorectal cancer (CRC). However, the exact mechanism by which QUE exerts its anti-tumor effects in CRC remains unclear. In this study, MTS assay and flow cytometry were used to detect the anti-tumor effects of QUE on HCT-116 cells. The results showed that QUE could inhibit the proliferation and induce apoptosis of HCT-116 cells. Furthermore, whole transcriptome sequencing was employed to establish the microRNA (miRNA), long non-coding RNA (lncRNA), circular RNA (circRNA), and mRNA profiles. A total of 240 differentially expressed lncRNAs (DElncRNAs), 131 circRNAs (DEcircRNAs), 83 miRNAs (DEmiRNAs), and 1415 mRNAs (DEmRNAs) were identified in the QUE-treated HCT-116 cells compared to the untreated HCT-116 cells. Then, quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the expression of selected circRNAs, miRNAs, lncRNAs, and mRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed to further investigate RNAs' biological functions and potential mechanisms. Based on the theory of competing endogenous RNA (ceRNA), the circRNA-miRNA-mRNA and lncRNA-miRNA-mRNA regulatory networks were constructed to illustrate the regulatory relationship between non-coding RNA (ncRNA) and mRNA. Our results provided novel information about the molecular basis of QUE in treating CRC. Our findings indicated that deep RNA sequencing analysis of mRNA and ncRNAs was a promising approach to research anticancer mechanisms.

Activation of the ILT7 receptor and plasmacytoid dendritic cell responses are governed by structurally-distinct BST2 determinants

Type I interferons (IFN-I) are key innate immune effectors predominantly produced by activated plasmacytoid dendritic cells (pDCs). By modulating immune responses at their foundation, IFNs can widely reshape immunity to control infectious diseases and malignancies. Nevertheless, their biological activities can also be detrimental to surrounding healthy cells, as prolonged IFN-I signaling is associated with excessive inflammation and immune dysfunction. The interaction of the human pDC receptor immunoglobulin-like transcript 7 (ILT7) with its IFN-I-regulated ligand, bone marrow stromal cell antigen 2 (BST2) plays a key role in controlling the IFN-I amounts produced by pDCs in response to Toll-like receptor (TLR) activation. However, the structural determinants and molecular features of BST2 that govern ILT7 engagement and activation are largely undefined. Using two functional assays to measure BST2-stimulated ILT7 activation as well as biophysical studies, here we identified two structurally-distinct regions of the BST2 ectodomain that play divergent roles during ILT7 activation. We found that although the coiled-coil region contains a newly defined ILT7-binding surface, the N-terminal region appears to suppress ILT7 activation. We further show that a stable BST2 homodimer binds to ILT7, but post-binding events associated with the unique BST2 coiled-coil plasticity are required to trigger receptor signaling. Hence, BST2 with an unstable or a rigid coiled-coil fails to activate ILT7, whereas substitutions in its N-terminal region enhance activation. Importantly, the biological relevance of these newly defined domains of BST2 is underscored by the identification of substitutions having opposing potentials to activate ILT7 in pathological malignant conditions.

Molecular carcinogenesis of gastric cancer: Lauren classification, mucin phenotype expression, and cancer stem cells

Gastric cancer (GC), one of the most common human cancers, is a heterogeneous disease with different phenotypes, prognoses, and responses to treatment. Understanding the pathogenesis of GC at the molecular level is important for prognosis prediction and determining treatments. Microsatellite instability (MSI), silencing of MLH1, MGMT, and CDKN2A genes by DNA hypermethylation, KRAS mutation, APC mutation, and ERBB2 amplification are frequently found in intestinal type GC. Inactivation of CDH1 and RARB by DNA hypermethylation, and amplification of FGFR and MET, are frequently detected in diffuse type GC. In addition, BST2 and PCDHB9 genes are overexpressed in intestinal type GC. Both genes are associated with GC progression. GC can be divided into gastric/intestinal mucin phenotypes according to mucin expression. MSI, alterations of TP73, CDH1 mutation, and DNA methylation of MLH are detected frequently in the gastric mucin phenotype. TP53 mutation, deletion of APC, and DNA methylation of MGMT are detected frequently in the intestinal mucin phenotype. FKTN is overexpressed in the intestinal mucin phenotype, and IQGAP3 is overexpressed in the gastric mucin phenotype. These genes are involved in GC progression. To characterize cancer stem cells, a useful method is spheroid colony formation. KIFC1 and KIF11 genes show more than twofold higher expression in spheroid-forming cells than that in parental cells. Both KIF genes are overexpressed in GC, and knockdown of these genes inhibits spheroid formation. Alterations of these molecules may be useful to understand gastric carcinogenesis. Specific inhibitors of these molecules may also be promising anticancer drugs.

CD317 Activates EGFR by Regulating Its Association with Lipid Rafts

EGFR regulates various fundamental cellular processes, and its constitutive activation is a common driver for cancer. Anti-EGFR therapies have shown benefit in cancer patients, yet drug resistance almost inevitably develops, emphasizing the need for a better understanding of the mechanisms that govern EGFR activation. Here we report that CD317, a surface molecule with a unique topology, activated EGFR in hepatocellular carcinoma (HCC) cells by regulating its localization on the plasma membrane. CD317 was upregulated in HCC cells, promoting cell-cycle progression and enhancing tumorigenic potential in a manner dependent on EGFR. Mechanistically, CD317 associated with lipid rafts and released EGFR from these ordered membrane domains, facilitating the activation of EGFR and the initiation of downstream signaling pathways, including the Ras-Raf-MEK-ERK and JAK-STAT pathways. Moreover, in HCC mouse models and patient samples, upregulation of CD317 correlated with EGFR activation. These results reveal a previously unrecognized mode of regulation for EGFR and suggest CD317 as an alternative target for treating EGFR-driven malignancies. SIGNIFICANCE: Activation of EGFR by CD317 in hepatocellular carcinoma cells suggests CD317 as an alternative target for treating EGFR-dependent tumors.

Pulsed SILAC-based proteomic analysis unveils hypoxia- and serum starvation-induced de novo protein synthesis with PHD finger protein 14 (PHF14) as a hypoxia sensitive epigenetic regulator in cell cycle progression

Hypoxia is an environmental cue that is associated with multiple tumorigenic processes such as immunosuppression, angiogenesis, cancer invasion, metastasis, drug resistance, and poor clinical outcomes. When facing hypoxic stress, cells initiate several adaptive responses such as cell cycle arrest to reduce excessive oxygen consumption and co-activation of oncogenic factors. In order to identify the critical novel proteins for hypoxia responses, we used pulsed-SILAC method to trace the active cellular translation events in A431 cells. Proteomic discovery data and biochemical assays showed that cancer cells selectively activate key glycolytic enzymes and novel ER-stress markers, while protein synthesis is severely suppressed. Interestingly, deprivation of oxygen affected the expression of various epigenetic regulators such as histone demethylases and NuRD (nucleosome remodeling and deacetylase) complex in A431 cells. In addition, we identified PHF14 (the plant homeodomain finger-14) as a novel hypoxia-sensitive epigenetic regulator that plays a key role in cell cycle progress and protein synthesis. Hypoxia-mediated inhibition of PHF14 was associated with increase of key cell cycle inhibitors, p14^ARF, p15^INK4b, and p16^INK4a, which are responsible for G1-S phase transition and decrease of AKT-mTOR-4E-BP1/pS6K signaling pathway, a master regulator of protein synthesis, in response to environmental cues. Analysis of TCGA colon cancer (n=461) and skin cancer (n=470) datasets revealed a positive correlation between PHF14 expression and protein translation initiation factors, eIF4E, eIF4B, and RPS6. Significance of PHF14 gene was further demonstrated by in vivo mouse xenograft model using PHF14 KD cell lines.

CBX6 is negatively regulated by EZH2 and plays a potential tumor suppressor role in breast cancer

Chromobox 6 (CBX6) is a subunit of Polycomb Repressive Complex 1 (PRC1) that mediates epigenetic gene repression and acts as an oncogene or tumor suppressor in a cancer type-dependent manner. The specific function of CBX6 in breast cancer is currently undefined. In this study, a comprehensive analysis of The Cancer Genome Atlas (TCGA) dataset led to the identification of CBX6 as a consistently downregulated gene in breast cancer. We provided evidence showing enhancer of zeste homolog 2 (EZH2) negatively regulated CBX6 expression in a Polycomb Repressive Complex 2 (PRC2)-dependent manner. Exogenous overexpression of CBX6 inhibited cell proliferation and colony formation, and induced cell cycle arrest along with suppression of migration and invasion of breast cancer cells in vitro. Microarray analyses revealed that CBX6 governs a complex gene expression program. Moreover, CBX6 induced significant downregulation of bone marrow stromal cell antigen-2 (BST2), a potential therapeutic target, via interactions with its promoter region. Our collective findings support a tumor suppressor role of CBX6 in breast cancer.

BST-2 promotes survival in circulation and pulmonary metastatic seeding of breast cancer cells

Bone marrow stromal antigen 2 (BST-2) mediates various facets of cancer progression and metastasis. Here, we show that BST-2 is linked to poor survival in invasive breast cancer patients as its expression positively correlates with disease severity. However, the mechanisms that drive the pro‐metastatic functions of BST-2 are not fully understood. Correlation of BST-2 expression and tumor aggressiveness was analyzed in human tissue samples. Migration, invasion, and competitive experimental metastasis assays were used to measure the cellular responses after silencing BST-2 expression. Using a mouse model of breast cancer, we show that BST-2 promotes metastasis independent of the primary tumor. Additional experiments show that suppression of BST-2 renders non-adherent cancer cells non-viable by sensitizing cells to anoikis. Embedment of cancer cells in basement membrane matrix reveals that silencing BTS-2 expression inhibits invadopodia formation, extracellular matrix degradation, and subsequent cell invasion. Competitive experimental pulmonary metastasis shows that silencing BST-2 reduces the numbers of viable circulating tumor cells (CTCs) and decreases the efficiency of lung colonization. Our data define a previously unknown function for BST-2 in the i) formation of invadopodia, ii) degradation of extracellular matrix, and iii) protection of CTCs from hemodynamic stress. We believe that physical (tractional forces) and biochemical (ECM type/composition) cues may control BST-2’s role in cell survival and invadopodia formation. Collectively, our findings highlight BST-2 as a key factor that allows cancer cells to invade, survive in circulation, and at the metastatic site.

Prognostic Values of EPDR1 Hypermethylation and Its Inhibitory Function on Tumor Invasion in Colorectal Cancer

Aberrant DNA methylation is a potential mechanism underlying the development of colorectal cancer (CRC). Thus, identification of prognostic DNA methylation markers and understanding the related molecular functions may offer a new perspective on CRC pathogenesis. To that end, we explored DNA methylation profile changes in CRC subtypes based on the microsatellite instability (MSI) status through genome-wide DNA methylation profiling analysis. Of 34 altered genes, three hypermethylated (epidermal growth factor, EGF; carbohydrate sulfotransferase 10, CHST10; ependymin related 1, EPDR1) and two hypomethylated (bone marrow stromal antigen 2, BST2; Rac family small GTPase 3, RAC3) candidates were further validated in CRC patients. Based on quantitative methylation-specific polymerase chain reaction (Q-MSP), EGF, CHST10 and EPDR1 showed higher hypermethylated levels in CRC tissues than those in adjacent normal tissues, whereas BST2 showed hypomethylation in CRC tissues relative to adjacent normal tissues. Additionally, among 75 CRC patients, hypermethylation of CHST10 and EPDR1 was significantly correlated with the MSI status and a better prognosis. Moreover, EPDR1 hypermethylation was significantly correlated with node negativity and a lower tumor stage as well as with mutations in B-Raf proto-oncogene serine/threonine kinase (BRAF) and human transforming growth factor beta receptor 2 (TGFβR2). Conversely, a negative correlation between the mRNA expression and methylation levels of EPDR1 in CRC tissues and cell lines was observed, revealing that DNA methylation has a crucial function in modulating EPDR1 expression in CRC cells. EPDR1 knockdown by a transient small interfering RNA significantly suppressed invasion by CRC cells, suggesting that decreased EPDR1 levels may attenuate CRC cell invasion. These results suggest that DNA methylation-mediated EPDR1 epigenetic silencing may play an important role in preventing CRC progression.

BST2 promotes cell proliferation, migration and induces NF-κB activation in gastric cancer

OBJECTIVES

To investigate the functional roles of bone marrow stromal cell antigen 2 (BST2) in gastric cancer (GC) cells and its implications in the development of GC patients.

RESULTS

BST2 was frequently overexpressed in GC tissues compared with the adjacent non-tumorous tissues, and high BST2 expression was correlated with tumor stage and lymphatic metastasis. Furthermore, in vitro experiments demonstrated that knockdown of BST2 by siRNA inhibited cell proliferation, induced apoptosis and repressed cell motility in GC cells. In addition, the pro-tumor function of BST2 in GC was mediated partly through the NF-κB signaling.

CONCLUSION

BST2 possesses the oncogenic potential in GC by regulating the proliferation, apoptosis, and migratory ability of GC cells, thereby BST2 could be a potential therapeutic target for the treatment of GC.

A retinoic acid-dependent stroma-leukemia crosstalk promotes chronic lymphocytic leukemia progression

In chronic lymphocytic leukemia (CLL), the non-hematopoietic stromal microenvironment plays a critical role in promoting tumor cell recruitment, activation, survival, and expansion. However, the nature of the stromal cells and molecular pathways involved remain largely unknown. Here, we demonstrate that leukemic B lymphocytes induce the activation of retinoid acid synthesis and signaling in the microenvironment. Inhibition of RA-signaling in stromal cells causes deregulation of genes associated with adhesion, tissue organization and chemokine secretion including the B-cell chemokine CXCL13. Notably, reducing retinoic acid precursors from the diet or inhibiting RA-signaling through retinoid-antagonist therapy prolong survival by preventing dissemination of leukemia cells into lymphoid tissues. Furthermore, mouse and human leukemia cells could be distinguished from normal B-cells by their increased expression of Rarγ2 and RXRα, respectively. These findings establish a role for retinoids in murine CLL pathogenesis, and provide new therapeutic strategies to target the microenvironment and to control disease progression.

The stromal microenvironment plays a key role in the expansion of chronic lymphocytic leukemia. Here, the authors use the Eµ-TCL1 mouse model to show that leukemic B-cells induce the activation of retinoic acid synthesis in stromal cells of the lymphoid microenvironment, and that impacting on retinoic acid signalling via diet or chemical inhibition prolonged survival by preventing leukemia dissemination and accumulation in lymphoid tissues.

Independent prognostic genes and mechanism investigation for colon cancer

PROPOSE

We aimed to explore the potential molecular mechanism and independent prognostic genes for colon cancer (CC).

METHODS

Microarray datasets GSE17536 and GSE39582 were downloaded from Gene Expression Omnibus. Meanwhile, the whole CC-related dataset were downloaded from The Cancer Genome Atlas (TCGA) database. Differentially expressed mRNA (DEMs) were identified between cancer tissue samples and para-carcinoma tissue samples in TCGA dataset, followed by the KEGG pathway and GO function analyses. Furthermore, the clinical prognostic analysis including overall survival (OS) and disease-free survival (DFS) were performed in all three datasets.

RESULTS

A total of 633 up- and 321 down-regulated mRNAs were revealed in TCGA dataset. The up-regulated mRNAs were mainly assembled in functions including extracellular matrix and pathways including Wnt signaling. The down-regulated mRNAs were mainly assembled in functions like Digestion and pathways like Drug metabolism. Furthermore, up-regulation of UL16-binding protein 2 (ULBP2) was associated with OS in CC patients. A total of 12 DEMs including Surfactant Associated 2 (SFTA2) were potential DFS prognostic genes in CC patients. Meanwhile, the GRP and Transmembrane Protein 37 (TMEM37) were two outstanding independent DFS prognostic genes in CC.

CONCLUSIONS

ULBP2 might be a potential novel OS prognostic biomarker in CC, while GRP and TMEM37 could be served as the independent DFS prognostic genes in CC. Furthermore, functions including extracellular matrix and digestion, as well as pathways including Wnt signaling and drug metabolism might play important roles in the process of CC.

Structural determinant of BST-2-mediated regulation of breast cancer cell motility: a role for cytoplasmic tail tyrosine residues

There is now irrefutable evidence that overexpression of the innate immunity protein―BST-2, in breast cancer cells is implicated in tumor growth and progression. The cellular mechanisms that control BST-2-mediated effect in tumor progression involve enhancement of cancer cell motility―migration/invasion. However, the distinct structural elements of BST-2 that mediate breast cancer cell motility remain unknown. Here, we used various motility assays and different variants of BST-2 to examine the cellular and structural mechanisms controlling BST-2-mediated cell motility. We show that BST-2 silencing in various cancer cell lines inhibits cell motility. Restoration of BST-2 expression using construct expressing wild type BST-2 rescues cell motility. Mutational analysis identifies the cytoplasmic tail of BST-2 as a novel regulator of cancer cell motility, because cell motility was significantly abrogated by substitution of the BST-2 cytoplasmic tail tyrosine residues to alanine residues. Furthermore, in a spheroid invasion model, BST-2-expressing tumor spheroids are highly invasive inside 3D Matrigel matrices. In this model, the spreading distance of BST-2-expressing spheroids was significantly higher than that of BST-2-suppressed spheroids. Collectively, our data reveal that i) BST-2-expressing breast cancer cells in spheroids are more motile than their BST-2-supressed counterparts; ii) BST-2 cytoplasmic tail regulates non-proteolytic (migration) and proteolytic (invasion) mechanisms of breast cancer cell motility; and iii) replacement of the tyrosine residues at positions 6 and 8 in the cytoplasmic tail of BST-2 with alanine residues inhibits cell motility.

Prognostic impact of a novel gene expression profile classifier for the discrimination between metastatic and non-metastatic primary colorectal cancer tumors

Despite significant advances have been achieved in the genetic characterization of sporadic colorectal cancer (sCRC), the precise genetic events leading to the development of distant metastasis remain poorly understood. Thus, accurate prediction of metastatic disease in newly-diagnosed sCRC patients remains a challenge. Here, we evaluated the specific genes and molecular pathways associated with the invasive potential of colorectal tumor cells, through the assessment of the gene expression profile (GEP) of coding and non-coding genes in metastatic (MTX) vs. non-metastatic (non-MTX) primary sCRC tumors followed for >5 years. Overall, MTX tumors showed up-regulation of genes associated with tumor progression and metastatic potential while non-MTX cases displayed GEP associated with higher cell proliferation, activation of DNA repair and anti-tumoral immune/inflammatory responses. Based on only 19 genes a specific GEP that classifies sCRC tumors into two MTX-like and non-MTX-like molecular subgroups was defined which shows an independent prognostic impact on patient overall survival, particularly when it is combined with the lymph node status at diagnosis. In summary, we show an association between the global GEP of primary sCRC cells and their metastatic potential and defined a GEP-based classifier that provides the basis for further prognostic stratification of sCRC patients who are at risk of distant metastases.

Overexpression of KIFC1 and its association with spheroid formation in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common human cancers. We previously reported that KIFC1 is involved in gastric cancer pathogenesis and that KIFC1 plays an important role in gastric cancer spheroid colony formation. However, the significance of KIFC1 in ESCC has not been examined. In the present study, we analyzed the expression and distribution of KIFC1 in 132 ESCC cases by immunohistochemistry. In contrast to weak or no staining of KIFC1 in non-neoplastic mucosa, ESCC tissue showed stronger, more extensive KIFC1 staining. In total, 95 (72%) of 132 ESCC cases were positive for KIFC1. Immunostaining of ALDH1 was also performed, and KIFC1-positive ESCC cases were significantly frequently found in ALDH1-positive ESCC cases compared with ALDH1-negative ESCC cases. Spheroid colony formation is an effective method to characterize CSCs, thus we analyzed sphere number and size at 15days in ESCC cells downregulated for KIFC1 by siRNA transfection. Both the number and size of sphere from TE-1 cells were significantly reduced in KIFC1 siRNA-transfected TE-1 cells than in negative control siRNA-transfected cells. These results suggest that KIFC1 plays an important role in ESCC pathogenesis.

Mechanisms of colitis-accelerated colon carcinogenesis and its prevention with the combination of aspirin and curcumin: Transcriptomic analysis using RNA-seq

Colorectal cancer (CRC) remains the leading cause of cancer-related death in the world. Aspirin (ASA) and curcumin (CUR) are widely investigated chemopreventive candidates for CRC. However, the precise mechanisms of their action and their combinatorial effects have not been evaluated. The purpose of the present study was to determine the effect of ASA, CUR, and their combination in azoxymethane/dextran sulfate sodium (AOM/DSS)-induced colitis-accelerated colorectal cancer (CAC). We also aimed to characterize the differential gene expression profiles in AOM/DSS-induced tumors as well as in tumors modulated by ASA and CUR using RNA-seq. Diets supplemented with 0.02% ASA, 2% CUR or 0.01% ASA+1% CUR were given to mice from 1week prior to the AOM injection until the experiment was terminated 22weeks after AOM initiation. Our results showed that CUR had a superior inhibitory effect in colon tumorigenesis compared to that of ASA. The combination of ASA and CUR at a lower dose exhibited similar efficacy to that of a higher dose of CUR at 2%. RNA isolated from colonic tissue from the control group and from tumor samples from the experimental groups was subjected to RNA-seq. Transcriptomic analysis suggested that the low-dose combination of ASA and CUR modulated larger gene sets than the single treatment. These differentially expressed genes were situated in several canonical pathways important in the inflammatory network and liver metastasis in CAC. We identified a small subset of genes as potential molecular targets involved in the preventive action of the combination of ASA and CUR. Taken together, the current results provide the first evidence in support of the chemopreventive effect of a low-dose combination of ASA and CUR in CAC. Moreover, the transcriptional profile obtained in our study may provide a framework for identifying the mechanisms underlying the carcinogenesis process from normal colonic tissue to tumor development as well as the cancer inhibitory effects and potential molecular targets of ASA and CUR.

BST2 confers cisplatin resistance via NF-κB signaling in nasopharyngeal cancer

Concurrent/adjuvant cisplatin-based chemoradiotherapy is regarded as the standard of treatment for locoregionally advanced nasopharyngeal carcinoma (NPC). However, patients who do not respond to cisplatin suffer, rather than benefit, from chemotherapy treatment. The goal of this study was to identify molecules involved in cisplatin resistance and to clarify their molecular mechanisms, which would help in the discovery of potential therapeutic targets and in developing a personalized and precise treatment approach for NPC patients. We previously generated a cisplatin-sensitive NPC cell line, S16, from CNE2 cells and found that eIF3a, ASNS and MMP19 are upregulated in S16 cells, which contributes to their cisplatin sensitivity. In this study, we found that BST2 is downregulated in cisplatin-sensitive S16 cells compared with CNE2 cells. Knockdown of BST2 in NPC cells sensitized their response to cisplatin and promoted cisplatin-induced apoptosis, whereas exogenous overexpression of BST2 increased their cisplatin resistance and inhibited cisplatin-induced apoptosis. Further investigation demonstrated that BST2-mediated cisplatin resistance depended on the activation of the NF-κB signaling pathway and consequent upregulation of anti-apoptotic genes, such as Bcl-X_L and livin. Moreover, an analysis of clinical data revealed that a high BST2 level might serve as an independent indicator of poor prognosis in patients with locally advanced NPC treated with platinum-based chemoradiotherapy. These findings suggest that BST2 likely mediates platinum resistance in NPC, offering guidance for personalized and precise treatment strategies for patients with NPC.

Overexpression of the transmembrane protein BST-2 induces Akt and Erk phosphorylation in bladder cancer

Bladder cancer, the majority of which is urothelial carcinoma (UC), is a common malignancy worldwide. Genes encoding transmembrane/secretory proteins expressed specifically in certain cancers may be ideal biomarkers for cancer diagnosis and may represent therapeutic targets. In the present study, the expression and function of the bone marrow stromal cell antigen 2 (BST2) gene was analyzed in UC. Reverse transcription-quantitative polymerase chain reaction demonstrated that expression of BST2 in normal tissue samples was the highest in liver tissue. However, expression of BST2 in UC tissue samples was higher than in normal liver. Immunohistochemical analysis revealed weak or no staining of BST-2 in non-neoplastic mucosa, whereas UC tissue exhibited stronger and more extensive staining compared with non-neoplastic mucosa. BST-2 staining was observed mainly on UC cell membranes. In total, 28 (41%) of 69 UC cases were positive for BST-2. UC cases positive for BST-2 were more frequently T2/3/4 cases [so-called muscle-invasive bladder cancer (MIBC)] than Ta/is/1 cases (P=0.0001). However, Kaplan-Meier analysis demonstrated no association between BST-2 expression and survival. BST2 small interfering RNA (siRNA)-transfected T24 cells exhibited significantly reduced cell growth relative to negative control siRNA-transfected T24 cells. The levels of phosphorylated Akt and extracellular signal-regulated kinase were lower in BST2 siRNA-transfected T24 cells than in control cells. These results suggest the involvement of BST-2 in the pathogenesis of UC. Since BST-2 is expressed on the cell membrane, BST-2 may be a good therapeutic target for MIBC.

CD317 Promotes the survival of cancer cells through apoptosis-inducing factor

BACKGROUND

Low nutrient environment is a major obstacle to solid tumor growth. However, many tumors have developed adaptive mechanisms to circumvent the requirement for exogenous growth factors.

METHODS

Here we used siRNA interference or plasmid transfection techniques to knockdown or enhance CD317 expression respectively, in mammalian cancer cells, and subjected these CD317-manipulated cells to serum deprivation to study the role of CD317 on stress-induced apoptosis and the underlying mechanism.

RESULTS

We report that CD317, an innate immune gene overexpressed in human cancers, protected cancer cells against serum deprivation-induced apoptosis. In tumor cells, loss of CD317 markedly enhanced their susceptibility to serum deprivation-induced apoptosis with no effect on autophagy or caspase activation, indicating an autophagy- and caspase-independent mechanism of CD317 function. Importantly, CD317 knockdown in serum-deprived tumor cells impaired mitochondria function and subsequently promoted apoptosis-inducing factor (AIF) release and nuclear translocation but had little effect on mitochondrial and cytoplasmic distributions of cytochrome C, a pro-apoptotic factor released from mitochondria that initiates caspase processing in response to death stimuli. Furthermore, overexpression of CD317 in HEK293T cells inhibits serum deprivation-induced apoptosis as well as the release and nuclear accumulation of AIF.

CONCLUSION

Our data suggest that CD317 functions as an anti-apoptotic factor through the mitochondria-AIF axis in malnourished condition and may serve as a potential drug target for cancer therapy.