Ai Jun Zhou

RBM24 suppresses cancer progression by upregulating MIR-25 to target MALAT1 in nasopharyngeal carcinoma

Abnormal interaction between non-coding RNAs has been demonstrated to be a common molecular event in various human cancers, but its significance and underlying mechanisms have not been well documented. RNA-binding proteins (RBPs) are key regulators of RNA transcription and post-transcriptional processing. In this study, we found that RNA-binding protein 24 (RBM24) was frequently downregulated in nasopharyngeal carcinoma (NPC). The restoration of RBM24 expression suppressed NPC cellular proliferation, migration and invasion and impeded metastatic colonization in mouse models. Microarray analyses revealed that miR-25 expression was upregulated by RBM24 expression in NPC cells. Similarly, ectopic miR-25 expression suppressed NPC cellular growth and motility by targeting the pro-oncogenic lncRNA MALAT1, and the knockdown of MALAT1 expression exhibited similar effects as RBM24 restoration in NPC cells. Overall, these findings suggest a novel role of RBM24 as a tumor suppressor. Mechanistically, RBM24 acts at least in part through upregulating the expression of miR-25, which in turn targets MALAT1 for degradation.

Ephrin receptor A2 is an epithelial cell receptor for Epstein-Barr virus entry.

Epstein–Barr virus (EBV) is causally associated with nasopharyngeal carcinoma, 10% of gastric carcinoma and various B cell lymphomas1. EBV infects both B cells and epithelial cells2. Recently, we reported that epidermal growth factor and Neuropilin 1 markedly enhanced EBV entry into nasopharyngeal epithelial cells3. However, knowledge of how EBV infects epithelial cells remains incomplete. To understand the mechanisms through which EBV infects epithelial cells, we integrated microarray and RNA interference screen analyses and found that Ephrin receptor A2 (EphA2) is important for EBV entry into the epithelial cells. EphA2 short interfering RNA knockdown or CRISPR–Cas9 knockout markedly reduced EBV epithelial cell infection, which was mostly restored by EphA2 complementary DNA rescue. EphA2 overexpression increased epithelial cell EBV infection. Soluble EphA2 protein, antibodies against EphA2, soluble EphA2 ligand EphrinA1, or the EphA2 inhibitor 2,5-dimethylpyrrolyl benzoic acid derivative efficiently blocked EBV epithelial cell infection. Mechanistically, EphA2 interacted with EBV entry proteins gH/gL and gB to facilitate EBV internalization and fusion. The EphA2 Ephrin-binding domain and fibronectin type III repeats domain were essential for EphA2-mediated EBV infection, while the intracellular domain was dispensable. This is distinct from Kaposi’s sarcoma-associated herpesvirus infection through EphA24. Taken together, our results identify EphA2 as a critical player for EBV epithelial cell entry.The receptor tyrosine kinase EphA2 is found to be an important determinant of EBV entry and fusion in epithelial cells. EphA2 depletion or absence, or the use of anti-EphA2 antibodies, inhibits oropharyngeal epithelial cell infection.

ISG15 predicts poor prognosis and promotes cancer stem cell phenotype in nasopharyngeal carcinoma.

Interferon-stimulated gene 15 (ISG15), the first identified ubiquitin-like protein, is known for its anti-viral capacity. However, its role in tumorigenesis remains controversial. Here, using RNA-seq profiling analysis, we identified ISG15 as a differentially expressed gene in nasopharyngeal carcinoma (NPC) and validated its overexpression in NPC samples and cells. High ISG15 levels in NPC tissues were correlated with more frequent local recurrence and shorter overall survival and disease-free survival. ISG15 overexpression promoted a cancer stem cell phenotype in NPC cells, including increased colony and tumorsphere formation abilities, pluripotency-associated genes expression, and in vivo tumorigenicity. By contrast, knockdown of ISG15 attenuated stemness characteristics in NPC cells. Furthermore, overexpression of ISG15 increased NPC cell resistance to radiation and cisplatin (DDP) treatment. Our study demonstrates a protumor role of ISG15, and suggests that ISG15 is a prognostic predictor and a potential therapeutic target for NPC.

Genomic comparison of esophageal squamous cell carcinoma and its precursor lesions by multi-region whole-exome sequencing

Esophageal squamous dysplasia is believed to be the precursor lesion of esophageal squamous cell carcinoma (ESCC); however, the genetic evolution from dysplasia to ESCC remains poorly understood. Here, we applied multi-region whole-exome sequencing to samples from two cohorts, 45 ESCC patients with matched dysplasia and carcinoma samples, and 13 tumor-free patients with only dysplasia samples. Our analysis reveals that dysplasia is heavily mutated and harbors most of the driver events reported in ESCC. Moreover, dysplasia is polyclonal, and remarkable heterogeneity is often observed between tumors and their neighboring dysplasia samples. Notably, copy number alterations are prevalent in dysplasia and persist during the ESCC progression, which is distinct from the development of esophageal adenocarcinoma. The sharp contrast in the prevalence of the ‘two-hit’ event on TP53 between the two cohorts suggests that the complete inactivation of TP53 is essential in promoting the development of ESCC.The pathogenesis of oesophageal squamous cell carcinoma is a multi-step process but the genetic determinants behind this progression are unknown. Here the authors use multi-region exome sequencing to comprehensively investigate the genetic evolution of precursor dysplastic lesions and untransformed oesophagus.

Far upstream element-binding protein 1 is a prognostic biomarker and promotes nasopharyngeal carcinoma progression

Nasopharyngeal carcinoma (NPC) is a malignant epithelial tumor with tremendous invasion and metastasis capacities, and it has a high incidence in southeast Asia and southern China. Previous studies identified that far upstream element-binding protein 1 (FBP1), a transcriptional regulator of c-Myc that is one of the most frequently aberrantly expressed oncogenes in various human cancers, including NPC, is an important biomarker for many cancers. Our study aimed to investigate the expression and function of FBP1 in human NPC. Quantitative real-time RT-PCR (qRT-PCR), western blot and immunohistochemical staining (IHC) were performed in NPC cells and biopsies. Furthermore, the effect of FBP1 knockdown on cell proliferation, colony formation, side population tests and tumorigenesis in nude mice were measured by MTT, clonogenicity analysis, flow cytometry and a xenograft model, respectively. The results showed that the mRNA and protein levels of FBP1, which are positively correlated with c-Myc expression, were substantially higher in NPC than that in nasopharyngeal epithelial cells. IHC revealed that the patients with high FBP1 expression had a significantly poorer prognosis compared with the patients with low expression (P=0.020). In univariate analysis, high FBP1 and c-Myc expression predicted poorer overall survival (OS) and poorer progression-free survival. Multivariate analysis indicated that high FBP1 and c-Myc expression were independent prognostic markers. Knockdown of FBP1 reduced cell proliferation, clonogenicity and the ratio of side populations, as well as tumorigenesis in nude mice. These data indicate that FBP1 expression, which is closely correlated with c-Myc expression, is an independent prognostic factor and promotes NPC progression. Our results suggest that FBP1 can not only serve as a useful prognostic biomarker for NPC but also as a potential therapeutic target for NPC patients.

TACC3 promotes colorectal cancer tumourigenesis and correlates with poor prognosis

Colorectal carcinoma (CRC) is a malignant epithelial tumour with tremendous invasion and metastatic capacity. Transforming acidic coiled-coil protein-3 (TACC3), a frequently aberrantly expressed oncogene, is an important biomarker in various human cancers. Our study aimed to investigate the expression and function of TACC3 in human CRC. We found that TACC3 was over-expressed at both the mRNA and protein levels in CRC cells and in biopsies of CRC tissues compared with normal controls as determined by qRT-PCR, western blot and immunohistochemical (IHC) staining assays. IHC staining of samples from 161 patients with CRC also revealed that TACC3 expression was significantly correlated with clinical stage (P = 0.045), T classification (P = 0.029) and M classification (P = 0.020). Multivariate analysis indicated that high TACC3 expression was an independent prognostic marker for CRC. Patients who had high TACC3 expression had significantly poorer overall survival (OS, P = 0.023) and disease-free survival (DFS, P = 0.019) compared to patients who had low TACC3 expression. Furthermore, TACC3 knockdown attenuated CRC cell proliferation, colony formation capability, migration and invasion capability, and tumourigenesis in nude mice; these properties were measured using a real-time cell analyser (RTCA), clonogenicity analysis, and transwell and xenograft assays, respectively. These data indicate that TACC3 promotes CRC progression and could be an independent prognostic factor and a potential therapeutic target for CRC.

Overexpression of Nogo receptor 3 (NgR3) correlates with poor prognosis and contributes to the migration of epithelial cells of nasopharyngeal carcinoma patients

Lymph node metastasis (N classification) is one of the most important prognostic factors of nasopharyngeal carcinoma (NPC), and nerve involvement is associated with the transition of the N category in NPC patients. Although the nervous system has been reported to participate in many types of cancer progression, its functions in NPC progression remains unknown. Through analysis of gene profiling data, we demonstrate an enrichment of genes associated with neuronal development and differentiation in NPC tissues and cell lines. Among these genes, Nogo receptor 3 (NgR3), which was originally identified in the nervous system and plays a role in nerve development and regeneration, was inappropriately overexpressed in NPC cells and tissues. Immunohistochemical analysis demonstrated that the overexpression of NgR3 was correlated with poor prognosis in NPC patients. Overexpression of NgR3 promoted, and knocking down NgR3 inhibited, NPC cell migration and invasion in vitro and metastasis in vivo. The ability of NgR3 to promote cell migration was triggered by the downregulation of E-cadherin and enhanced cytoskeletal rearrangement and cell polarity, which were correlated with the activation of focal adhesion kinase (FAK). Collectively, NgR3 is a novel indicator of poor outcomes in NPC patients and plays an important role in driving the progression of NPC. These results suggest a potential link between the nervous system and NPC progression.Key messagesGenes involved in the neuronal biological process are enriched in nasopharyngeal carcinoma.Overexpression of NgR3 correlates with poor prognosis of nasopharyngeal carcinoma.NgR3 promotes NPC cell migration by downregulating E-cadherin.NgR3 promotes NPC cell polarity and enhances the formation of NPC cell pseudopodia by activating FAK/Src pathway.

The RARS-MAD1L1 Fusion Gene Induces Cancer Stem Cell-like Properties and Therapeutic Resistance in Nasopharyngeal Carcinoma

Purpose: Nasopharyngeal carcinoma (NPC) is the most common head and neck cancer in Southeast Asia. Because local recurrence and distant metastasis are still the main causes of NPC treatment failure, it is urgent to identify new tumor markers and therapeutic targets for advanced NPC. Experimental Design: RNA sequencing (RNA-seq) was applied to look for interchromosome translocation in NPC. PCR, FISH, and immunoprecipitation were used to examine the fusion gene expression at RNA, DNA, and protein levels in NPC biopsies. MTT assay, colony formation assay, sphere formation assay, co-immunoprecipitation, chromatin immunoprecipitation assay, and in vivo chemoresistance assay were applied to explore the function of RARS-MAD1L1 in NPC. Results: We demonstrated that RARS-MAD1L1 was present in 10.03% (35/349) primary NPC biopsies and 10.7% (9/84) in head and neck cancer (HNC) samples. RARS-MAD1L1 overexpression increased cell proliferation, colony formation, and tumorigenicity in vitro, and the silencing of endogenous RARS-MAD1L1 reduced cancer cell growth and colony formation in vitro. In addition, RARS-MAD1L1 increased the side population (SP) ratio and induced chemo- and radioresistance. Furthermore RARS-MAD1L1 interacted with AIMP2, which resulted in activation of FUBP1/c-Myc pathway. The silencing of FUBP1 or the administration of a c-Myc inhibitor abrogated the cancer stem cell (CSC)-like characteristics induced by RARS-MAD1L1. The expression of c-Myc and ABCG2 was higher in RARS-MAD1L1–positive HNC samples than in negative samples. Conclusions: Our findings indicate that RARS-MAD1L1 might contribute to tumorigenesis, CSC-like properties, and therapeutic resistance, at least in part, through the FUBP1/c-Myc axis, implying that RARS-MAD1L1 might serve as an attractive target for therapeutic intervention for NPC. Clin Cancer Res; 24(3); 659–73. ©2017 AACR.

Author Correction: Ephrin receptor A2 is an epithelial cell receptor for Epstein–Barr virus entry

In the version of this Letter originally published, the authors reported on the use of 2,5-dimethylpyrrolyl benzoic acid to block Ephrin receptors. In 2011, it was reported that newly synthesized 2,5-dimethylpyrrolyl benzoic acid lacked the previously reported EphA2 antagonizing activity1. However, the purchased compound did in fact have the activity initially reported, suggesting that an uncharacterized alteration occurred during storage. The authors therefore wish to clarify that the compound used in their study should be more accurately referred to as a 2,5-dimethylpyrrolyl benzoic acid derivative. All references to 2,5-dimethylpyrrolyl benzoic acid in the Letter have now been changed to reflect this.Although 2,5-dimethylpyrrolyl benzoic acid derivatives have been reported to have off-target effects2, as do most small-molecule inhibitors, the multiple complementary methods and techniques used demonstrate that EphA2 is a key Epstein–Barr virus epithelial cell receptor. The conclusions of the study are therefore unchanged.