Hyperfractionation compared with standard fractionation in intensity-modulated radiotherapy for patients with locally advanced recurrent nasopharyngeal carcinoma: a multicentre, randomised, open-label, phase 3 trial.

BACKGROUND: Reirradiation in standard fractionation for locally advanced recurrent nasopharyngeal carcinoma after a previous course of high-dose radiotherapy is often associated with substantial late toxicity, negating its overall benefit. We therefore aimed to investigate the efficacy and safety of hyperfractionation compared with standard fractionation in intensity-modulated radiotherapy. METHODS: This multicentre, randomised, open-label, phase 3 trial was done in three centres in Guangzhou, China. Eligible patients were aged 18-65 years with histopathologically confirmed undifferentiated or differentiated, non-keratinising, advanced locally recurrent nasopharyngeal carcinoma. Participants were randomly assigned (1:1) to either receive hyperfractionation (65 Gy in 54 fractions, given twice daily with an interfractional time interval of at least 6 h) or standard fractionation (60 Gy in 27 fractions, given once a day). Intensity-modulated radiotherapy was used in both groups. A computer program generated the assignment sequence and randomisation was stratified by treatment centre, recurrent tumour stage (T2-T3 vs T4), and recurrent nodal stage (N0 vs N1-N2), determined at the time of randomisation. The two primary endpoints were the incidence of severe late complications defined as the incidence of grade 3 or worse late radiation-induced complications occurring 3 months after the completion of radiotherapy until the latest follow-up in the safety population, and overall survival defined as the time interval from randomisation to death due to any cause in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT02456506. FINDINGS: Between July 10, 2015, and Dec 23, 2019, 178 patients were screened for eligibility, 144 of whom were enrolled and randomly assigned to hyperfractionation or standard fractionation (n=72 in each group). 35 (24%) participants were women and 109 (76%) were men. After a median follow-up of 45·0 months (IQR 37·3-53·3), there was a significantly lower incidence of grade 3 or worse late radiation-induced toxicity in the hyperfractionation group (23 [34%] of 68 patients) versus the standard fractionation group (39 [57%] of 68 patients; between-group difference -23% [95% CI -39 to -7]; p=0·023). Patients in the hyperfractionation group had better 3-year overall survival than those in the standard fractionation group (74·6% [95% CI 64·4 to 84·8] vs 55·0% [43·4 to 66·6]; hazard ratio for death 0·54 [95% CI 0·33 to 0·88]; p=0·014). There were fewer grade 5 late complications in the hyperfractionation group (five [7%] nasal haemorrhage) than in the standard fractionation group (16 [24%], including two [3%] nasopharyngeal necrosis, 11 [16%] nasal haemorrhage, and three [4%] temporal lobe necrosis). INTERPRETATION: Hyperfractionated intensity-modulated radiotherapy could significantly decrease the rate of severe late complications and improve overall survival among patients with locally advanced recurrent nasopharyngeal carcinoma. Our findings suggest that hyperfractionated intensity-modulated radiotherapy could be used as the standard of care for these patients. FUNDING: Key-Area Research and Development of Guangdong Province, the National Natural Science Foundation of China, the Special Support Program for High-level Talents in Sun Yat-sen University Cancer Center, the Guangzhou Science and Technology Plan Project, and the National Ten Thousand Talents Program Science and Technology Innovation Leading Talents, Sun Yat-Sen University Clinical Research 5010 Program.

BCL6-SPECC1L: A Novel Fusion Gene in Nasopharyngeal Carcinoma.

Background: Nasopharyngeal carcinomas (NPCs) are malignant tumors originating from the lining epithelium of the nasopharynx. Fusion genes have been confirmed to play important roles in the occurrence and development of various malignant tumors, but the role of fusion genes in NPC is poorly understood. We aimed to explore new fusion genes that promote the occurrence and development of NPC. Methods: RNA-seq was used to search for interchromosomal translocations in 18 NPC tissues. Polymerase chain reaction (PCR) and Sanger sequencing were applied to verify the presence of BCL6-SPECC1L (BS); quantitative PCR (qPCR) and Western blotting were used to measure the expression level of BCL-6 in NPC cells; MTT and in vivo tumorigenesis assays were applied to evaluate the cell proliferation ability; immunofluorescence assays were used to determine the cellular localization of BCL6 and BS; and a luciferase reporter assay was performed to evaluate the ability of BCL6 and BS to inhibit transcription. Results: BS was present in 5.34% (11/206) of primary NPC biopsies and 2.13% (1/47) of head and neck cancer biopsies. The expression of BCL6 was downregulated in NPC, and silencing of endogenous BCL6 promoted NPC cell proliferation in vitro. Overexpression of BCL6 but not BS inhibited the growth of NPC cells in vivo and in vitro. Mechanistically, BCL6 localized in the nucleus can inhibit the G1/S transition to suppress the growth of NPC cells. However, after the fusion of BCL6 and SPECC1L, the product cannot localize to the nucleus, and the transcriptional inhibitory function of BCL6 is abolished, eventually abolishing its tumor suppressor effect and leading to the development of NPC. Conclusion: BS is a novel fusion gene in NPC that may play an important role in the occurrence and development of this cancer. The clinical significance of the BS fusion gene needs further elucidation.

Establishment of a patient-derived organoid model and living biobank for nasopharyngeal carcinoma.

Background: Recurrent nasopharyngeal carcinoma (NPC) remains a major challenge for clinicians and scientists. Tumor organoid is a revelational disease model that highly resembled the heterogeneity and histopathological characteristics of original tumors. This study aimed to optimize the modeling process of patient-derived NPC organoids (NPCOs), and establish a living-biobank of NPCs to study the mechanism and explore the more effective treatment of the disease. Methods: Sixty-two fresh NPC tissue samples and 15 normal mucosa samples were collected for 3-dimensional (3D) organoid culture. The organoids were confirmed using hematoxylin and eosin assays. The expression levels of CD133, CD44, BMI-1, and Epstein-Barr virus (EBV)-encoded small RNAs (EBERs) were detected by immunohistochemistry (IHC) and in situ hybridization (ISH). Recurrent NPCOs were frozen in liquid nitrogen for 6 months and then resuscitated and passaged. Results: We identified a novel two-step enzymatic strategy for the treatment of NPC and nasal mucosa specimens and an optimal medium for culturing NPCOs and nasal mucosa organoids (NMOs). Organoid cultures were generated from 34 primary NPC samples, 28 recurrent NPC samples, and 15 normal mucosa samples. The success rates for primary NPCO, recurrent NPCO, and NMO formation were 47.06%, 81.25%, and 86.5%, respectively. All the NPCOs were EBER positive and CK7 negative. Recurrent NPCOs had higher expressions of stem cell markers, including BMI-1, CD44, and CD133. Additionally, recurrent NPCOs could be cultured to passage 4 and frozen and revived repeatedly, while primary NPCOs were challenging to culture. Conclusions: In summary, we successfully established a living biobank using the NPCO model, which has enormous potential in basic and clinical research on NPC.

The prognostic value of weight loss during radiotherapy among patients with nasopharyngeal carcinoma: a large-scale cohort study.

BACKGROUND: We aim to investigate the prognostic value of weight loss during radiotherapy (RT) among patients with nasopharyngeal carcinoma (NPC). METHODS: A total of 1149 NPC patients who received radical RT were retrospectively analyzed. Patients' weight were measured at initiation of RT (WPre-RT) and every week during RT (WRT1,2,3,4,5,6,7). Percentage of weight loss (PWL) at 1st, 2nd, 3rd, 4th, 5th, 6th, and 7th week of RT (RT-PWL1,2,3,4,5,6,7) were calculated using the following equation: (WPre-RT -WRT1,2,3,4,5,6,7)/WPre-RT × 100%. The optimal threshold of RT-PWL7 was determined by recursive partitioning analyses (RPAs). Our endpoints included disease-free survival (DFS), overall survival (OS), distant metastasis-free survival (DMFS), and locoregional relapse-free survival (LRRFS). RESULTS: The median RT-PWLs were 0, 0, 1.5, 2.9, 4.1, 5.5, 6.6% at 1st, 2nd, 3rd, 4th, 5th, 6th, and 7th week of RT, respectively. RT-PWL7 optimal threshold with respect to DFS was 5.3% based on RPAs. Therefore, a consistent threshold of 5% (<5% vs > ≥5%) was selected to classify NPC patients into low RT-PWL7 and high RT-PWL7 groups for survival analysis. Compared to high RT-PWL7 (≥5%), patients with low RT-PWL7 (< 5%) had significantly better ten-year DFS (61.2% vs 78.8%; P < 0.001), OS (70.1% vs 86.6%; P < 0.001), and DMFS (80.2% vs 88.5%; P = 0.007). However, no difference was observed between LRRFS groups (91.7% vs 94.3%; P = 0.173). In multivariate analysis, high RT-PWL7 was an independent risk factor for DFS (HR, 1.56; 95%CI, 1.19-2.03; P = 0.001), OS (HR, 1.54; 95%CI, 1.11-2.15; P = 0.011), and DMFS (HR, 1.47; 95%CI, 1.03-2.10; P = 0.033) in patients with NPC. In addition, treatment strategy, plasma Epstein-Barr virus DNA, and N stage were associated with weight loss. CONCLUSIONS: High RT-PWL7 was significantly associated with decreased DFS, OS, and DMFS for NPC patients. Clinicians should continuously inform patients on the health impact of minimizing RT-PWL7 under 5% during radiotherapy.

The genomic architecture of EBV and infected gastric tissue from precursor lesions to carcinoma.

BACKGROUND: Epstein-Barr virus (EBV)-associated gastric carcinomas (EBVaGCs) present unique molecular signatures, but the tumorigenesis of EBVaGCs and the role EBV plays during this process remain poorly understood. METHODS: We applied whole-exome sequencing, EBV genome sequencing, and whole-genome bisulfite sequencing to multiple samples (n = 123) derived from the same patients (n = 25), which covered saliva samples and different histological stages from morphologically normal epithelial tissues to dysplasia and EBVaGCs. We compared the genomic landscape between EBVaGCs and their precursor lesions and traced the clonal evolution for each patient. We also analyzed genome sequences of EBV from samples of different histological types. Finally, the key molecular events promoting the tumor evolution were demonstrated by MTT, IC50, and colony formation assay in vitro experiments and in vivo xenograft experiments. RESULTS: Our analysis revealed increasing mutational burden and EBV load from normal tissues and low-grade dysplasia (LD) to high-grade dysplasia (HD) and EBVaGCs, and oncogenic amplifications occurred late in EBVaGCs. Interestingly, within each patient, EBVaGCs and HDs were monoclonal and harbored single-strain-originated EBV, but saliva or normal tissues/LDs had different EBV strains from that in EBVaGCs. Compared with precursor lesions, tumor cells showed incremental methylation in promotor regions, whereas EBV presented consistent hypermethylation. Dominant alterations targeting the PI3K-Akt and Wnt pathways were found in EBV-infected cells. The combinational inhibition of these two pathways in EBV-positive tumor cells confirmed their synergistic function. CONCLUSIONS: We portrayed the (epi) genomic evolution process of EBVaGCs, revealed the extensive genomic diversity of EBV between tumors and normal tissue sites, and demonstrated the synergistic activation of the PI3K and Wnt pathways in EBVaGCs, offering a new potential treatment strategy for this disease.

Identification of an N6-methyladenosine-mediated positive feedback loop that promotes Epstein-Barr virus infection.

N6-methyladenosine (m6A) is among the most abundant mRNA modifications, particularly in eukaryotes, and is found in mammals, plants, and even some viruses. Although essential for the regulation of many biological processes, the exact role of m6A modification in virus-host interaction remains largely unknown. Here, using m6A -immunoprecipitation and sequencing, we find that Epstein-Barr virus (EBV) infection decreases the m6A modification of transcriptional factor KLF4 mRNA and subsequently increases its protein level. Mechanistically, EBV immediate-early protein BZLF1 interacts with the promoter of m6A methyltransferase METTL3, inhibiting its expression. Subsequently, the decrease of METTL3 reduces the level of KLF4 mRNA m6A modification, preventing its decay by the m6A reader protein YTHDF2. As a result, KLF4 protein level is upregulated and, in turn, promotes EBV infection of nasopharyngeal epithelial cells. Thus, our results suggest the existence of a positive feedback loop formed between EBV and host molecules via cellular mRNA m6A levels, and this feedback loop acts to facilitate viral infection. This mechanism contains multiple potential targets for controlling viral infectious diseases.

N(6)-methyladenosine-binding protein YTHDF1 suppresses EBV replication and promotes EBV RNA decay.

N6 -methyladenosine (m6 A) modification of mRNA mediates diverse cellular and viral functions. Infection with Epstein-Barr virus (EBV) is causally associated with nasopharyngeal carcinoma (NPC), 10% of gastric carcinoma, and various B-cell lymphomas, in which the viral latent and lytic phases both play vital roles. Here, we show that EBV transcripts exhibit differential m6 A modification in human NPC biopsies, patient-derived xenograft tissues, and cells at different EBV infection stages. m6 A-modified EBV transcripts are recognized and destabilized by the YTHDF1 protein, which leads to the m6 A-dependent suppression of EBV infection and replication. Mechanistically, YTHDF1 hastens viral RNA decapping and mediates RNA decay by recruiting RNA degradation complexes, including ZAP, DDX17, and DCP2, thereby post-transcriptionally downregulating the expression of EBV genes. Taken together, our results reveal the critical roles of m6 A modifications and their reader YTHDF1 in EBV replication. These findings contribute novel targets for the treatment of EBV-associated cancers.

Single-cell transcriptomic analysis defines the interplay between tumor cells, viral infection, and the microenvironment in nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV)-associated malignancy with a complex tumor ecosystem. How the interplay between tumor cells, EBV, and the microenvironment contributes to NPC progression and immune evasion remains unclear. Here we performed single-cell RNA sequencing on ~104,000 cells from 19 EBV+ NPCs and 7 nonmalignant nasopharyngeal biopsies, simultaneously profiling the transcriptomes of malignant cells, EBV, stromal and immune cells. Overall, we identified global upregulation of interferon responses in the multicellular ecosystem of NPC. Notably, an epithelial-immune dual feature of malignant cells was discovered and associated with poor prognosis. Functional experiments revealed that tumor cells with this dual feature exhibited a higher capacity for tumorigenesis. Further characterization of the cellular components of the tumor microenvironment (TME) and their interactions with tumor cells revealed that the dual feature of tumor cells was positively correlated with the expression of co-inhibitory receptors on CD8+ tumor-infiltrating T cells. In addition, tumor cells with the dual feature were found to repress IFN-γ production by T cells, demonstrating their capacity for immune suppression. Our results provide new insights into the multicellular ecosystem of NPC and offer important clinical implications.

Upregulation of METTL3 Expression Predicts Poor Prognosis in Patients with Esophageal Squamous Cell Carcinoma.

BACKGROUND: The N6-methyladenosine (m6A) RNA modification of mRNA mediates various cellular functions and cancer progression. However, the roles of m6A RNA modification in the regulation of esophageal squamous cell carcinoma (ESCC), the dominant subtype of esophageal cancer in Asia, were unclear. MATERIALS AND METHODS: Here, we analyzed the mRNA expression level of methyltransferase like 3 (METTL3) in the public available datasets of ESCC tissues and matched adjacent normal tissues. We also performed immunohistochemistry (IHC) assays to detect the protein expression of METTL3 in human ESCC tissue specimen. In our study, we also analyzed the association between METTL3 expression and prognosis using Cox proportional hazard regression in 207 ESCC patients. RESULTS: The results of public available datasets and IHC assays showed that METTL3 was upregulated in tumor compared with adjacent nonmalignant esophageal mucosal tissues. The IHC results indicated that higher expression level of METTL3 was associated with worse survival. We also found that METTL3 expression level was an independent predictor for disease-free survival and overall survival of ESCC patients. CONCLUSION: Our results revealed that the METTL3 expression level could be used as an independent prognostic biomarker for ESCC prognosis.

Correction to: Elevated expression of CST1 promotes breast cancer progression and predicts a poor prognosis.

In Figure 7f the panel for c-myc of MDA-MB-468 was erroneously duplicated. The corrected version of the figure is shown in this paper. This correction does not influence the conclusion of the study and we sincerely apologize for this oversight.

Anillin is required for tumor growth and regulated by miR-15a/miR-16-1 in HBV-related hepatocellular carcinoma.

Anillin (ANLN) is an actin-binding protein essential for assembly of cleavage furrow during cytokinesis. Although reportedly overexpressed in various human cancers, its role in hepatocellular carcinoma (HCC) is unclear. To address this issue, we confirmed that in 436 liver samples obtained from surgically removed HCC tissues, higher ANLN expression was detected in tumor tissues than in adjacent non-tumor tissues of HCC as measured by immunohistochemistry, quantitative real-time PCR and western blotting. Correlation and Kaplan-Meier analysis revealed that patients with higher ANLN expression were associated with worse clinical outcomes and a shorter survival time, respectively. Moreover, ANLN inhibition resulted in growth restraint, reduced colony formation, and a lower sphere number in suspension culture. Mechanistically, ANLN deficiency induced an increasing number of multinucleated cells along with the activation of apoptosis signaling and DNA damage checkpoints. Furthermore, HBV infection increased ANLN expression by inhibiting the expression of microRNA (miR)-15a and miR-16-1, both of which were identified as ANLN upstream repressors by targeting its 3' untranslated region. Thus, we conclude that ANLN promotes tumor growth by ways of decreased apoptosis and DNA damage. Expression level of ANLN significantly influences the survival probability of HCC patients and may represent a promising prognostic biomarker.

CRLF1 promotes malignant phenotypes of papillary thyroid carcinoma by activating the MAPK/ERK and PI3K/AKT pathways.

Papillary thyroid carcinoma (PTC) is the one of the most common types of endocrine cancer and has a heterogeneous prognosis. Tumors from patients with poor prognosis may differentially express specific genes. Therefore, an analysis of The Cancer Genome Atlas (TCGA) database was performed and revealed that cytokine receptor-like factor 1 (CRLF1) may be a potential novel target for PTC treatment. The objective of the current study was to explore the expression of CRLF1 in PTC and to investigate the main functions and mechanisms of CRLF1 in PTC. PTC tissues exhibited higher CRLF1 expression at both the mRNA and protein levels than it did with normal thyroid tissues. High CRLF1 levels were associated with aggressive clinicopathological features and poor disease-free survival rates. By using loss-of-function and gain-of-function assays, we found that CRLF1 not only increased cell migration and invasion in vitro but also promoted tumor growth both in vitro and in vivo. In addition, CRLF1 induced epithelial-mesenchymal transitions. Overexpression of CRLF1 activated the ERK1/2 and AKT pathways. The oncogenic effects induced by CRLF1 were suppressed by treating the cells with the MEK inhibitor U0126 or the AKT inhibitor MK-2206. These results suggest that CRLF1 enhances cell proliferation and metastasis in PTC and thus may therefore be a potential therapeutic target for PTC.

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 MESSAGES: Genes 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.

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.

Novel chimeric transcript RRM2-c2orf48 promotes metastasis in nasopharyngeal carcinoma.

Recently, chimeric transcripts have been found to be associated with the pathogenesis and poor prognosis of malignant tumors. Through our preliminary experiment, a novel chimeric transcript called chimeric transcript RRM2-c2orf48 was detected in C666-1, a classical cell line of human nasopharyngeal carcinoma (NPC). Therefore, the objective of this study was to demonstrate the existence and expression of novel chimeric transcript RRM2-c2orf48 and to explore the main functions and mechanisms of RRM2-c2orf48 in NPC. In this study, the expression of RRM2-c2orf48 was evaluated in NPC cells and specimens. Effects of RRM2-c2orf48 on migration and invasive capacities were detected in vivo and vitro. Moreover, ways in which RRM2-c2orf48 increases the invasive capacities of NPC were explored. As a result, the presence of novel chimeric transcript RRM2-c2orf48 was confirmed in C666-1 by RT-PCR and sequencing, and it was a read-through between RRM2 and c2orf48 through the transcription of interchromosome. Higher expressions of novel RRM2-c2orf48 were detected in NPC cell lines and NPC tissue specimens relative to the controls and its expression was be statistically relevant to TNM staging. High level of RRM2-c2orf48 could increase the migration and invasive capacities of NPC cells, potentially as a result of NPC cell epithelial-mesenchymal transition. RRM2-c2orf48 could also enhance resistance of chemotherapy. In vivo, RRM2-c2orf48 could enhance lung and lymph node metastasis in nude mice. These results demonstrate that high levels of RRM2-c2orf48 expression may be a useful predictor of NPC patients of metastatic potency, presenting potential implications for NPC diagnosis and therapy.

Elevated expression of CST1 promotes breast cancer progression and predicts a poor prognosis.

Cystatin SN (CST1) belongs to the type 2 cystatin (CST) superfamily, which restricts the proteolytic activities of cysteine proteases. CST1 has been recently considered to be involved in the development of several human cancers. However, the prognostic significance and function of CST1 in breast cancer remains unknown. In the current study, we found that CST1 was generally upregulated in breast cancer at both mRNA and protein level. Furthermore, overall survival (OS) and disease-free survival (DFS) in the low CST1 expression subgroup were significantly superior to the high CST1 expression subgroup (OS, p < 0.001; DFS, p < 0.001), which indicated that CST1 expression level was closely correlated to the survival risk of these patients. Univariate and multivariate analyses demonstrated that CST1 expression was an independent prognostic factor, the same as ER status and nodal status. Next, CST1 overexpression promoted breast cancer cell proliferation, clonogenicity, migration, and invasion abilities. By contrast, knockdown of CST1 attenuated these malignant characteristics in breast cancer cells. Collectively, our study indicates that CST1 cannot only serve as a significant prognostic indicator but also as a potential therapeutic target for breast cancer. KEY MESSAGES: High CST1 expression is negatively correlated with survival of breast cancer patients. CST1 promotes cell proliferation, clone formation, and metastasis in breast cancer cells. CST1 is a novel potential prognostic biomarker and therapeutic target for breast cancer.

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.