CD55 is a HIF-2α marker with anti-adhesive and pro-invading properties in neuroblastoma

CD55 in cancer: Complementing functions in a non-canonical manner

CD55, or decay accelerating factor, is a membrane lipid microdomain-associated, GPI-anchored protein implicated in the shielding of cells from complement-mediated attack via accelerating decay of C3 and C5. Loss of CD55 is associated with a number of pathologies due to hyperactivation of the complement system. CD55 is also implicated in cancer progression thought to be driven via its role in cell shielding mechanisms. We now appreciate that CD55 can signal intracellularly to promote malignant transformation, cancer progression, cell survival, angiogenesis, and inhibition of apoptosis. Outside-in signaling via CD55 is mediated by signaling pathways including JNK, JAK/STAT, MAPK/NF-κB, and LCK. Moreover, CD55 is enriched in the cancer stem cell (CSC) niche of multiple tumors including breast, ovarian, cervical, and can be induced by chemotherapeutics and hypoxic environments. CSCs are implicated in tumor recurrence and chemoresistance. Here, we review the unexpected roles of CD55 in cancer including the roles of canonical and noncanonical pathways that CD55 orchestrates. We will highlight opportunities for therapeutic targeting CD55 and gaps in the field that require more in-depth mechanistic insights.

Polyadenylate-binding protein cytoplasmic 1 mediates alternative splicing events of immune-related genes in gastric cancer cells

Polyadenylate-binding protein cytoplasmic 1 (PABPC1) is dysregulated in malignancies, which is considered as a potential therapeutic target for many cancer types. By alternative splicing (AS) for gastric cancer (GC), we described PABPC1-modulated AS events in this study. PABPC1 expression was analyzed in 408 GC tissues from The Cancer Genome Altas (TCGA) database. Human gastric adenocarcinoma (AGS) cells were transfected with PABPC1-specific small interfering RNA (siPABPC1) with siCtrl as a negative control. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was done for the determination of transcripts. To detect the differentially expressed genes (DEGs) and 10 different types of AS events, RNA sequencing (RNA-seq) was performed. DEGs were analyzed for functional categories including gene ontology, and the Kyoto encyclopedia of genes and genomes pathway were analyzed for DEGs. GC displayed an elevated expression of PABPC1. PABPC1 was efficiently knocked down in AGS cells. Here, we excavated 1234 PABPC1-regulated DEGs, among which 502 were down-regulated and 732 were up-regulated compared to the siCtrl group. A total of 94 DEGs were involved in inflammation and immune response. Results from qRT-PCR validated the up-regulation of 10 immune and inflammation-related DEGs in the siPABPC1 group. PABPC1 deficiency causes 1304 AS events differentially occurred in AGS cells. The most common type of AS events regulated by PABPC2 is alternative 5' splice sites. qRT-PCR confirmed the transcription level of five immune-related genes, in which AS events were detected in the siPABPC1 group. PABPC1 knockdown mediates AS events and thus the transcript level of immune and inflammation-related genes in AGS cells. PABPC1-regulated oncogenic AS events display potential as targets for therapeutic development.

FGFR1 is a potential therapeutic target in neuroblastoma

BACKGROUND

FGFR1 regulates cell-cell adhesion and extracellular matrix architecture and acts as oncogene in several cancers. Potential cancer driver mutations of FGFR1 occur in neuroblastoma (NB), a neural crest-derived pediatric tumor arising in sympathetic nervous system, but so far they have not been studied experimentally. We investigated the driver-oncogene role of FGFR1 and the implication of N546K mutation in therapy-resistance in NB cells.

METHODS

Public datasets were used to predict the correlation of FGFR1 expression with NB clinical outcomes. Whole genome sequencing data of 19 paired diagnostic and relapse NB samples were used to find somatic mutations. In NB cell lines, silencing by short hairpin RNA and transient overexpression of FGFR1 were performed to evaluate the effect of the identified mutation by cell growth, invasion and cologenicity assays. HEK293, SHSY5Y and SKNBE2 were selected to investigate subcellular wild-type and mutated protein localization. FGFR1 inhibitor (AZD4547), alone or in combination with PI3K inhibitor (GDC0941), was used to rescue malignant phenotypes induced by overexpression of FGFR1 wild-type and mutated protein.

RESULTS

High FGFR1 expression correlated with low relapse-free survival in two independent NB gene expression datasets. In addition, we found the somatic mutation N546K, the most recurrent point mutation of FGFR1 in all cancers and already reported in NB, in one out of 19 matched primary and recurrent tumors. Loss of FGFR1 function attenuated invasion and cologenicity in NB cells, whereas FGFR1 overexpression enhanced oncogenicity. The overexpression of FGFR1^N546K protein showed a higher nuclear localization compared to wild-type protein and increased cellular invasion and cologenicity. Moreover, N546K mutation caused the failure in response to treatment with FGFR1 inhibitor by activation of ERK, STAT3 and AKT pathways. The combination of FGFR1 and PI3K pathway inhibitors was effective in reducing the invasive and colonigenic ability of cells overexpressing FGFR1 mutated protein.

CONCLUSIONS

FGFR1 is an actionable driver oncogene in NB and a promising therapy may consist in targeting FGFR1 mutations in patients with therapy-resistant NB.

Investigation of Potential Genetic Biomarkers and Molecular Mechanism of Ulcerative Colitis Utilizing Bioinformatics Analysis

Objectives

To reveal the molecular mechanisms of ulcerative colitis (UC) and provide potential biomarkers for UC gene therapy.

Methods

We downloaded the GSE87473 microarray dataset from the Gene Expression Omnibus (GEO) and identified the differentially expressed genes (DEGs) between UC samples and normal samples. Then, a module partition analysis was performed based on a weighted gene coexpression network analysis (WGCNA), followed by pathway and functional enrichment analyses. Furthermore, we investigated the hub genes. At last, data validation was performed to ensure the reliability of the hub genes.

Results

Between the UC group and normal group, 988 DEGs were investigated. The DEGs were clustered into 5 modules using WGCNA. These DEGs were mainly enriched in functions such as the immune response, the inflammatory response, and chemotaxis, and they were mainly enriched in KEGG pathways such as the cytokine-cytokine receptor interaction, chemokine signaling pathway, and complement and coagulation cascades. The hub genes, including dual oxidase maturation factor 2 (DUOXA2), serum amyloid A (SAA) 1 and SAA2, TNFAIP3-interacting protein 3 (TNIP3), C-X-C motif chemokine (CXCL1), solute carrier family 6 member 14 (SLC6A14), and complement decay-accelerating factor (CD antigen CD55), were revealed as potential tissue biomarkers for UC diagnosis or treatment.

Conclusions

This study provides supportive evidence that DUOXA2, A-SAA, TNIP3, CXCL1, SLC6A14, and CD55 might be used as potential biomarkers for tissue biopsy of UC, especially SLC6A14 and DUOXA2, which may be new targets for UC gene therapy. Moreover, the DUOX2/DUOXA2 and CXCL1/CXCR2 pathways might play an important role in the progression of UC through the chemokine signaling pathway and inflammatory response.

Human papillomavirus E6 protein enriches the CD55(+) population in cervical cancer cells, promoting radioresistance and cancer aggressiveness

Accumulating evidence indicates that the human papillomavirus (HPV) E6 protein plays a crucial role in the development of cervical cancer. Subpopulations of cells that reside within tumours are responsible for tumour resistance to cancer therapy and recurrence. However, the identity of such cells residing in cervical cancer and their relationship with the HPV-E6 protein have not been identified. Here, we isolated sphere-forming cells, which showed self-renewal ability, from primary cervical tumours. Gene expression profiling revealed that cluster of differentiation (CD) 55 was upregulated in primary cervical cancer sphere cells. Flow-cytometric analysis detected abundant CD55(+) populations among a panel of HPV-positive cervical cancer cell lines, whereas few CD55(+) cells were found in HPV-negative cervical cancer and normal cervical epithelial cell lines. The CD55(+) subpopulation isolated from the C33A cell line showed significant sphere-forming ability and enhanced tumourigenicity, cell migration, and radioresistance. In contrast, the suppression of CD55 in HPV-positive CaSki cells inhibited tumourigenicity both in vitro and in vivo, and sensitized cells to radiation treatment. In addition, ectopic expression of the HPV-E6 protein in HPV-negative cervical cancer cells dramatically enriched the CD55(+) subpopulation. CRISPR/Cas9 knockout of CD55 in an HPV-E6-overexpressing stable clone abolished the tumourigenic effects of the HPV-E6 protein. Taken together, our data suggest that HPV-E6 protein expression enriches the CD55(+) population, which contributes to tumourigenicity and radioresistance in cervical cancer cells. Targeting CD55 via CRISPR/Cas9 may represent a novel avenue for developing new strategies and effective therapies for the treatment of cervical cancer. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Proteomic Alterations in Response to Hypoxia Inducible Factor 2α in Normoxic Neuroblastoma Cells

Hypoxia inducible factor (HIF)-2α protein expression in solid tumors promotes stem-like phenotype in cancer stem cells and increases tumorigenic potential in nonstem cancer cells. Recently, we have shown that HIF-1/2α gene expression is correlated to neuroblastoma (NB) poor survival and to undifferentiated tumor state; HIF-2α protein was demonstrated to enhance aggressive features of the disease. In this study, we used proteomic experiments on NB cells to investigate HIF-2α downstream-regulated proteins or pathways with the aim of providing novel therapeutic targets or bad prognosis markers. We verified that pathways mostly altered by HIF-2α perturbation are involved in tumor progression. In particular, HIF-2α induces alteration of central metabolism and splicing control pathways. Simultaneously, WNT, RAS/MAPK, and PI3K/AKT activity or expression are affected and may impact the sensitivity and the intensity of HIF-2α-regulated pathways. Furthermore, genes coding the identified HIF-2α-related markers built a signature able to stratify NB patients with unfavorable outcome. Taken together, our findings underline the relevance of dissecting the downstream effects of a poor survival marker in developing targeted therapy and improving patient stratification. Future prospective studies are needed to translate the use of these data into the clinical practice.