Gene Summary

Gene:NUMB; NUMB, endocytic adaptor protein
Aliases: S171, C14orf41, c14_5527
Summary:The protein encoded by this gene plays a role in the determination of cell fates during development. The encoded protein, whose degradation is induced in a proteasome-dependent manner by MDM2, is a membrane-bound protein that has been shown to associate with EPS15, LNX1, and NOTCH1. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Feb 2016]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:protein numb homolog
Source:NCBIAccessed: 11 March, 2017


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 11 March 2017 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 11 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: NUMB (cancer-related)

Cheng G, He J, Zhang L, et al.
HIC1 modulates uveal melanoma progression by activating lncRNA-numb.
Tumour Biol. 2016; 37(9):12779-12789 [PubMed] Related Publications
Uveal melanoma (UM) is the most common primary intraocular cancer in adults. Although the diagnosis modality of primary UM was improved significantly, there are currently no effective therapies for metastatic UM. Hypermethylated in cancer 1 (HIC1) is frequently deleted or epigenetically silenced in various human cancers. However, the role and mechanism of HIC1 in UM is still unclear. In this study, we found that HIC1 acted as a tumor suppressor and that its expression was downregulated in UM. Functional studies demonstrated that ectopic expression of HIC1 in UM cells inhibited cell proliferation and invasion. Moreover, through long non-coding RNA (lncRNA) microarray and real-time PCR, we found that expression of lncRNA-numb was activated by HIC1 in UM. The results provide evidence that lncRNA-numb is a newly proposed tumor suppressor that is involved in HIC1-induced phenotypes. Taken together, our studies of UM reveal a critical role of HIC1 in the regulation of tumorigenesis, at least partly through its downstream target, lncRNA-numb, and provide a potential therapeutic target for UM.

Bi YL, Min M, Shen W, Liu Y
Numb/Notch signaling pathway modulation enhances human pancreatic cancer cell radiosensitivity.
Tumour Biol. 2016; 37(11):15145-15155 [PubMed] Related Publications
The present study aims to evaluate whether repression of the Numb/Notch signaling pathway affects the radiosensitivity of human pancreatic cancer cell lines. Different doses of X-rays (0, 2, 3, 4, and 5 Gy) were applied to the PANC-1, SW1990, and MIA PaCa-2 human pancreatic cancer cell lines, and the Numb/Notch pathway inhibitor DAPT was added at different doses (0, 1, 3, and 5 μmol/l). MTT assay, colony formation assay, flow cytometry, scratch assay, and Transwell experiments were performed, and qRT-PCR and Western blot were conducted for the detection of Numb expression. Tumorigenicity assay in nude mice was carried out to verify the influence of blocker of the Numb/Notch signaling pathway on the radiosensitivity of xenograft tumors. The MTT assay, colony formation assay and flow cytometry experiments revealed that proliferation decreased as radiation dose increased. The viability of PANC-1 cells at 5 Gy, SW 1990 cells at 4 Gy and 5 Gy, and MIA PaCa-2 cells at 2-5 Gy was significantly lower than that of non-irradiated cells (all P < 0.05). The migration and invasion assays indicated that the PANC-1 cell line was least radiosensitive, while the MIA PaCa-2 cell line was the most radiosensitive. Numb expression significantly increased with increasing radiation dose, whereas the expression of Hes1, Notch1, and Hes5 significantly decreased compared to non-irradiated cells (P < 0.05). Compared to untreated control cells, DAPT dose dependently increased Numb expression and inhibited Notch1, Hes1, and Hes5 expressions at 2 Gy (P < 0.05). Subcutaneous tumorigenicity assay in nude mice demonstrated that DAPT increased the radiosensitivity of PANC-1, SW 1990, and MIA PaCa-2 cells. These findings suggest that Numb/Notch signaling in pancreatic cancer cells is associated with X-ray radiation and that inhibition of the Numb/Notch signaling pathway can enhance radiosensitivity, suggesting that inhibition of the Numb/Notch signaling pathway may serve as a potential target for clinical improvement of the radiosensitivity of pancreatic cancer.

Song SG, Yu HY, Ma YW, et al.
Inhibition on Numb/Notch signal pathway enhances radiosensitivity of lung cancer cell line H358.
Tumour Biol. 2016; 37(10):13705-13719 [PubMed] Related Publications
The objective of the study is to investigate the effects of the Numb/Notch signal pathway on the radiosensitivity of lung cancer cell line H358. MTT assay and colony forming assay were used to detect the effects of different doses of X-rays and MW167 on the in vitro proliferation of the lung cancer cell line H358. Flow cytometry was applied to evaluate the effects of X rays on the apoptosis of H358. Scratch assay and Transwell invasion assay were used to examine the effects of X-rays on the migration and invasion abilities of H358. The mRNA and protein expressions in the signal pathway were detected by real-time PCR and western blot. Assays in vitro confirmed the effects of the Numb/Notch pathway inhibitor on the radiosensitivity to lung cancer. MW167 enhanced the inhibiting effects of X-ray on the proliferation of H358 cell line. After the addition of MW167, the apoptosis rates significantly increased, but the invasion and migration abilities decreased significantly. Meanwhile, MW167 could dose-dependently promote the increase of expression of Numb, which is the upstream gene of the Numb/Notch signaling pathway, but inhibit the expression of and HES1. In vivo experiments revealed that cell proliferation was suppressed in the radiation, pathway inhibitor, and pathway inhibitor + radiation groups, and the pathway inhibitor + radiation group exhibited more active anti-tumor ability when compared with the blank group (all P < 0.05); Numb expression was up-regulated, but Notch1 and HES1 expressions were down-regulated in those three groups, and also, the pathway inhibitor + radiation group exhibited more significant alternation when compared with the blank group (all P < 0.05); cell apoptosis was promoted in those three groups, and the pathway inhibitor + radiation group showed more active apoptosis when compared with the blank group (all P < 0.05). Repression of the Numb/Notch pathway enhances the effects of radiotherapy on the radiosensitivity of the lung cancer cell line H358, and thus the Numb/Notch pathway may be a new target of radiotherapy for lung cancer.

Shan GP, Zhang P, Li P, et al.
Numb Gene Enhances Radiation Sensitivity of Nonsmall Cell Lung Cancer Stem Cells.
Cancer Biother Radiopharm. 2016; 31(5):180-8 [PubMed] Related Publications
OBJECTIVE: To study the effects of Numb gene expression on radiation sensitivity of nonsmall cell lung cancer (NSCLC) stem cells.
MATERIALS AND METHODS: The side population (SP) cells A549-SP were transfected with pcDNA3.1 (pcDNA3.1 group), pcDNA-Numb (pcDNA-Numb group) and shRNA-Numb (shRNA-Numb group). Real-time quantitative polymerase chain reaction and Western blot were performed to determine Numb expression; MTT method was used to measure the proliferation activity change of the NSCLC stem cells both before and after irradiation with different doses of 60Coγ ray; Hoechst staining and Annexin V-FITC/PI were used to detect the apoptosis of the NSCLC stem cells; and colony-forming assay was used to determine the effect of Numb expression on radiation sensitivity of the NSCLC stem cells.
RESULTS: Increased mRNA and protein expressions of the A549-SP cells were found in the pcDNA-Numb group, and decreased mRNA and protein expressions were found in the shRNA-Numb group. The optical density value of the cells decreased in the pcDNA-Numb group but increased in the shRNA-Numb group. The cells with over-expressed Numb showed obvious nuclear condensation and fragmentation; the apoptosis rate increased significantly. The cells with knockdown Numb showed less nuclear damage; the apoptosis rate significantly decreased. After irradiation, the cells in the pcDNA-Numb group showed decreased survival rate, clonality, and the values of D0, Dq, N, and SF2; whereas the cells in the shRNA-Numb group showed the opposite trend.
CONCLUSIONS: Radiation sensitivity of NSCLC stem cells was enhanced with the increase of Numb expression. Determination of Numb expression helped to evaluate the response of lung cancer to radiotherapy, which was important for guiding tumor treatment clinically.

García-Alegría E, Lafita-Navarro MC, Aguado R, et al.
NUMB inactivation confers resistance to imatinib in chronic myeloid leukemia cells.
Cancer Lett. 2016; 375(1):92-9 [PubMed] Related Publications
Chronic myeloid leukemia (CML) progresses from a chronic to a blastic phase, where the leukemic cells are proliferative and undifferentiated. The CML is nowadays successfully treated with BCR-ABL kinase inhibitors as imatinib and its derivatives. NUMB is an evolutionary well-conserved protein initially described as a functional antagonist of NOTCH function. NUMB is an endocytic protein associated with receptor internalization, involved in multiple cellular functions. It has been reported that MSI2 protein, a NUMB inhibitor, is upregulated in CML blast crisis, whereas NUMB itself is downregulated. This suggest that NUMB plays a role in the malignant progression of CML. Here we have generated K562 cells (derived from CML in blast crisis) constitutively expressing a dominant negative form of NUMB (dnNUMB). We show that dnNUMB expression confers a high proliferative phenotype to the cells. Importantly, dnNUMB triggers a partial resistance to imatinib in these cells, antagonizing the apoptosis mediated by the drug. Interestingly, imatinib resistance is not linked to p53 status or NOTCH signaling, as K562 lack p53 and imatinib resistance is reproduced in the presence of NOTCH inhibitors. Taken together, our data support the hypothesis that NUMB activation could be a new therapeutic target in CML.

Hollander D, Donyo M, Atias N, et al.
A network-based analysis of colon cancer splicing changes reveals a tumorigenesis-favoring regulatory pathway emanating from ELK1.
Genome Res. 2016; 26(4):541-53 [PubMed] Free Access to Full Article Related Publications
Splicing aberrations are prominent drivers of cancer, yet the regulatory pathways controlling them are mostly unknown. Here we develop a method that integrates physical interaction, gene expression, and alternative splicing data to construct the largest map of transcriptomic and proteomic interactions leading to cancerous splicing aberrations defined to date, and identify driver pathways therein. We apply our method to colon adenocarcinoma and non-small-cell lung carcinoma. By focusing on colon cancer, we reveal a novel tumor-favoring regulatory pathway involving the induction of the transcription factor MYC by the transcription factor ELK1, as well as the subsequent induction of the alternative splicing factor PTBP1 by both. We show that PTBP1 promotes specific RAC1,NUMB, and PKM splicing isoforms that are major triggers of colon tumorigenesis. By testing the pathway's activity in patient tumor samples, we find ELK1,MYC, and PTBP1 to be overexpressed in conjunction with oncogenic KRAS mutations, and show that these mutations increase ELK1 levels via the RAS-MAPK pathway. We thus illuminate, for the first time, a full regulatory pathway connecting prevalent cancerous mutations to functional tumor-inducing splicing aberrations. Our results demonstrate our method is applicable to different cancers to reveal regulatory pathways promoting splicing aberrations.

Gui SL, Teng LC, Wang SQ, et al.
Overexpression of CXCL3 can enhance the oncogenic potential of prostate cancer.
Int Urol Nephrol. 2016; 48(5):701-9 [PubMed] Related Publications
PURPOSE: CXCL3 and its receptor CXCR2 were considered to play particularly important roles in the progression of malignancies. However, the investigations about CXCL3/CXCR2 axis in prostate cancer have been poorly involved. Herein we firstly reported our studies on the expression and biological roles of CXCL3 and CXCR2 in prostate cancer.
METHODS: Expression levels of CXCL3 and CXCR2 in prostate cancer cell lines (PC-3, DU145 and LNCaP), immortalized prostate stromal cell line (WPMY-1) and immortalized prostate epithelial cell line (RWPE-1) were investigated by RT-PCR, ELISA and western blot, whereas expression levels of CXCL3 in a prostate tissue microarray were detected by immunohistochemistry. Cell counting kit-8 and transwell assays were, respectively, utilized to determine the effects of exogenous CXCL3 on the cell proliferation and migration. We further examined whether CXCL3 could regulate the expression of genes correlated with prostate tumorigenesis by RT- PCR.
RESULTS: Elevated expression of CXCR2 was detected in DU145, LNCaP and RWPE-1. Moreover, high-level CXCL3 can be secreted by PC-3 and RWPE-1, and CXCL3 protein expression level in tissue microarray is concordant with prostate cancer metastasis. Exogenous CXCL3 does not contribute to proliferation, but has a significant effect on migration of prostate cancer cells and RWPE-1. Finally, our data showed that exogenous CXCL3 can regulate the expression of genes including ERK, TP73, NUMB, BAX and NDRG3.
CONCLUSION: Our findings suggest that CXCL3 and its receptor CXCR2 are overexpressed in prostate cancer cells, prostate epithelial cells and prostate cancer tissues, which may play multiple roles in prostate cancer progression and metastasis.

Zhang L, Liu X, Zhang X, Chen R
Identification of important long non-coding RNAs and highly recurrent aberrant alternative splicing events in hepatocellular carcinoma through integrative analysis of multiple RNA-Seq datasets.
Mol Genet Genomics. 2016; 291(3):1035-51 [PubMed] Related Publications
Hepatocellular carcinoma (HCC) is an aggressive and deadly cancer. The molecular pathogenesis of the disease remains poorly understood. To better understand HCC biology and explore potential biomarkers and therapeutic targets, we investigated the whole transcriptome of HCC. Considering the genetic heterogeneity of HCC, four datasets from four studies consisting of 15 pairs of HCC and adjacent normal samples were analyzed. We observed that the number of lncRNAs expressed in each HCC sample was consistently greater than the adjacent normal sample. Moreover, 15 lncRNAs were identified expressed in five to seven HCC tissues but were not detected in any adjacent normal tissue. Differential expression analysis detected 35 up- and 80 down-regulated lncRNAs in HCC samples compared with adjacent normal samples. In addition, five differentially expressed lncRNAs were predicted to play a role in oxidation and reduction process. With regard to splicing alterations, we identified nine highly recurrent differential splicing events belonging to eight genes USO1, RPS24, CCDC50, THNSL2, NUMB, FN1 (two events), SLC39A14 and NR1I3. Of them, splicing alterations of SLC39A14 and NR1I3 were reported for the association with HCC for the first time. The splicing dysregulation in HCC may be influenced by three splicing factors ESRP2, CELF2 and SRSF5 which were significantly down-regulated in HCC samples. This study revealed uncharacterized aspects of HCC transcriptome and identified important lncRNAs and splicing isoforms with the potential to serve as biomarkers and therapeutic targets for the disease.

Narayanappa R, Rout P, Aithal MG, Chand AK
Aberrant expression of Notch1, HES1, and DTX1 genes in glioblastoma formalin-fixed paraffin-embedded tissues.
Tumour Biol. 2016; 37(5):6935-42 [PubMed] Related Publications
Glioblastoma is the most common malignant brain tumor accounting for more than 54 % of all gliomas. Despite aggressive treatments, median survival remains less than 1 year. This might be due to the unavailability of effective molecular diagnostic markers and targeted therapy. Thus, it is essential to discover molecular mechanisms underlying disease by identifying dysregulated pathways involved in tumorigenesis. Notch signaling is one such pathway which plays an important role in determining cell fates. Since it is found to play a critical role in many cancers, we investigated the role of Notch genes in glioblastoma with an aim to identify biomarkers that can improve diagnosis. Using real-time PCR, we assessed the expression of Notch genes including receptors (Notch1, Notch2, Notch3, and Notch4), ligands (JAG1, JAG2, and DLL3), downstream targets (HES1 and HEY2), regulator Deltex1 (DTX1), inhibitor NUMB along with transcriptional co-activator MAML1, and a component of gamma-secretase complex APH1A in 15 formalin-fixed paraffin-embedded (FFPE) patient samples. Relative quantification was done by the 2(-ΔΔCt) method; the data are presented as fold change in gene expression normalized to an internal control gene and relative to the calibrator. The data revealed aberrant expression of Notch genes in glioblastoma compared to normal brain. More than 85 % of samples showed high Notch1 (P = 0.0397) gene expression and low HES1 (P = 0.011) and DTX1 (P = 0.0001) gene expression. Our results clearly show aberrant expression of Notch genes in glioblastoma which can be used as putative biomarkers together with histopathological observation to improve diagnosis, therapeutic strategies, and patient prognosis.

Sajadimajd S, Yazdanparast R, Akram S
Involvement of Numb-mediated HIF-1α inhibition in anti-proliferative effect of PNA-antimiR-182 in trastuzumab-sensitive and -resistant SKBR3 cells.
Tumour Biol. 2016; 37(4):5413-26 [PubMed] Related Publications
Trastuzumab is a humanized monoclonal antibody against the human epidermal growth factor receptor 2 (HER2) that is overexpressed in about 25 % of breast cancer patients. However, primary and/or acquired resistance to trastuzumab develops in most affected persons. In this study, we explored the functional role of miR-182 inhibition with aiming the sensitization of SKBR3 cells to trastuzumab. Cell viability, apoptosis, colony formation, and migration capacities of SKBR3(S) (sensitive) and SKBR3(R) (resistant) cells were assessed to determine the anti-proliferative effects of PNA-antimiR-182. In addition, the expression levels of miR-182, mRNA of FOXO1, and Bim as well as the protein levels of HER2 and Notch1 signaling factors were evaluated by stem-loop RT-qPCR, RT-qPCR, and Western blot, respectively. The results indicated that miR-182 might play a causal role in the mechanism of trastuzumab. In line with that, PNA-antimiR-182 inhibited synergistically the viability of both the sensitive and resistant cell groups. Furthermore, the inhibitory effect of PNA-anitmiR-182 on migration in SKBR3 cells was more than the induction of apoptosis. In addition, PNA-antimiR-182 reduced the levels of NICD, Hes1, HIF-1α, and p-Akt in both cell groups, while it augmented the intracellular content of FOXO1 and Numb suppressor proteins. In other words, PNA-antimiR-182-mediated upregulation of Numb was associated with downregulation of HIF-1α and Hes1. Consequently, downregulation of miR-182 might find therapeutical value for overcoming trastuzumab resistance. Graphical Abstract The crosstalk between HER2 and Notch1 signaling pathway is mediated by miR-182.

Zhao E, Maj T, Kryczek I, et al.
Cancer mediates effector T cell dysfunction by targeting microRNAs and EZH2 via glycolysis restriction.
Nat Immunol. 2016; 17(1):95-103 [PubMed] Free Access to Full Article Related Publications
Aerobic glycolysis regulates T cell function. However, whether and how primary cancer alters T cell glycolytic metabolism and affects tumor immunity in cancer patients remains a question. Here we found that ovarian cancers imposed glucose restriction on T cells and dampened their function via maintaining high expression of microRNAs miR-101 and miR-26a, which constrained expression of the methyltransferase EZH2. EZH2 activated the Notch pathway by suppressing Notch repressors Numb and Fbxw7 via trimethylation of histone H3 at Lys27 and, consequently, stimulated T cell polyfunctional cytokine expression and promoted their survival via Bcl-2 signaling. Moreover, small hairpin RNA-mediated knockdown of human EZH2 in T cells elicited poor antitumor immunity. EZH2(+)CD8(+) T cells were associated with improved survival in patients. Together, these data unveil a metabolic target and mechanism of cancer immune evasion.

Hu T, Yang H, Han ZG
PDZRN4 acts as a suppressor of cell proliferation in human liver cancer cell lines.
Cell Biochem Funct. 2015; 33(7):443-9 [PubMed] Related Publications
Recently, some reports show that Ligand of Numb Protein-X 1 (LNX1) could be a suppressor gene in gliomas, while our current research has firstly shown that PDZ domain containing ring finger 4 (PDZRN4), another member of LNX family, could also be a potential suppressor in hepatocellular carcinoma (HCC). PDZRN4, also named LNX4 (Ligand of Numb Protein-X 4), is a member of the LNX family. We recently found that PDZRN4, but not LNX1, was down-regulated in HCC samples, and the role of PDZRN4 in the progression of HCC had not been studied before. To address this question, firstly, we evaluated the expression of PDZRN4 in HCC samples and adjacent non-cancerous tissues. Semi-quantitative polymerase chain reaction showed that PDZRN4 was down-regulated in 24/36 (66.7%) HCC samples separately. In addition, our research shows that PDZRN4 is silenced in all of the 12 HCC cell lines tested. Subsequently, cell-based functional assay exhibited that ectopic expression of PDZRN4 inhibits the proliferation, plate colony formation and anchorage-independent colony formation of HCC cells. Collectively, our results showed that PDZRN4 might be a potential tumour suppressor gene and had anti-proliferative effect on HCC cell proliferation, which would be of great significance to the researches on HCC.

Zheng KL, He TL, Ji WP, et al.
Alternative splicing of NUMB, APP and VEGFA as the features of pancreatic ductal carcinoma.
Int J Clin Exp Pathol. 2015; 8(6):6181-91 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is the most common form of malignancy in pancreatic carcinoma. Here we report our discovery on the correlations between transcriptional alternative splicing (AS) of NUMB, APP, VEGFA and PDAC in patients.
METHODS: The expression of NUMB, APP, VEGFA from patient samples was determined by qRT-PCR. AS of these genes was examined through laser induced fluorescence capillary electrophoresis. Correlation between the AS of the genes and results from clinical laboratory examinations were analyzed. Expression of NOTHC1 and NOTCH4 as downstream target genes was examined by qRT-PCR and Western blot.
RESULTS: Quantitative results indicated that expression of NUMB was significantly lower in tumor tissues (TT) than in para-tumor tissues (TP) (P<0.05), while APP (P<0.01) and VEGFA (P<0.05) were significantly higher. AS transcript percentage of NUMB PRR(S) was lower in TT than TP (P<0.05). AS transcript percentage of VEGFA (105+185) was significantly lower in TT than TP (P<0.05) compared to higher expression of VEGFA (206+338) (P<0.05). Regression analysis indicated that AS transcript of NUMB PRR(L) correlated with tumor size (P<0.01), while AS transcripts of APP and VEGFA correlated with results of laboratory examinations. To reveal the correlation between AS and its downstream targets, NOTCH1 and NOTCH4 were selected as NUMB gene targets and detected to be significantly higher in TT than TP (P<0.05).
CONCLUSION: Alternative splicing of APP, VEGFA and NUMB may play an important role in pathogenesis of pancreatic ductal adenocarcinoma. Among the 3 genes, PRR(L) form of NUMB gene is highly expressed in TT and positively correlated with tumor size, while PRR(S) is lacking in TT and negatively correlated with NOTCH expression suggesting that PRR(S) might be protective in tumorogenesis and shows NOTCH pathway down regulation ability.

Xie C, Lu Z, Liu G, et al.
Numb downregulation suppresses cell growth and is associated with a poor prognosis of human hepatocellular carcinoma.
Int J Mol Med. 2015; 36(3):653-60 [PubMed] Free Access to Full Article Related Publications
Numb, an endocytic adaptor, is a known cell fate determinant that participates in asymmetric cell division. The present study aimed to explore the potential roles of Numb in hepatocarcinogenesis. Numb expression was investigated in hepatocellular carcinomas (HCC) with reverse transcription‑quantitative polymerase chain reaction and immunohistochemical examination; its association with the prognosis of HCC patients was analyzed. In addition, the effects of Numb deletion on proliferation of HCC cells and its relevant molecules were evaluated in Huh7 and HepG2 cells. Numb overexpression was observed in 62% of adjacent non‑tumor tissues and 46% of tumor tissues. Overexpression of Numb in HCC was associated with histological grade, portal vein invasion and the number of tumors (P=0.001, 0.022 and 0.034 respectively). Multivariate analysis revealed that Numb expression was an independent prognostic indicator of HCC patients. Methylation of the Numb promoter contributed to hepatocarcinogenesis. In vitro assays demonstrated that Numb silencing resulted in inhibition of cell proliferation, induction of apoptosis, downregulation of cyclin‑dependent protein kinase 4 (CDK4) and S‑phase kinase‑associated protein 2 (SKP2), and upregulation of Bcl‑2 homologous antagonist/killer (BAK) and cyclin‑dependent kinase inhibitor 1 (p21). The present study suggests that downregulation of Numb inhibits colony formation and cell proliferation, induces apoptosis of HCC cells and independently predicts the poor prognosis of HCC patients. Thus, Numb has a potential role in the development and progression of HCC.

Zhao YJ, Han HZ, Liang Y, et al.
Alternative splicing of VEGFA, APP and NUMB genes in colorectal cancer.
World J Gastroenterol. 2015; 21(21):6550-60 [PubMed] Free Access to Full Article Related Publications
AIM: To investigate alternative splicing in vascular endothelial growth factor A (VEGFA), amyloid beta precursor protein (APP), and Numb homolog (NUMB) in colorectal cancer (CRC).
METHODS: Real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and PCR-restriction fragment length polymorphism analyses were performed to detect the expression of VEGFA, APP, and NUMB mRNA in 20 CRC tissues and matched adjacent normal tissues, as well as their alternative splicing variants.
RESULTS: qRT-PCR analysis revealed that the expression of APP, NUMB, and VEGFA165b mRNA were significantly downregulated, while VEGFA mRNA was upregulated, in CRC tissues (all P < 0.05). PCR-restriction fragment length polymorphism analysis revealed that the expression of VEGFA165a/b in CRC tissues was significantly higher than in adjacent normal tissues (P < 0.05). Compared with adjacent normal tissues, the expression of NUMB-PRR(S) in CRC tissues was significantly decreased (P < 0.05), and the expression of NUMB-PRR(L) was increased (P < 0.05).
CONCLUSION: Alternative splicing of VEGFA, APP, and NUMB may regulate the development of CRC, and represent new targets for its diagnosis, prognosis, and treatment.

Tessier SJ, Loiselle JJ, McBain A, et al.
Insight into the role of alternative splicing within the RBM10v1 exon 10 tandem donor site.
BMC Res Notes. 2015; 8:46 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: RBM10 is an RNA binding protein involved in the regulation of transcription, alternative splicing and message stabilization. Mutations in RBM10, which maps to the X chromosome, are associated with TARP syndrome, lung and pancreatic cancers. Two predominant isoforms of RBM10 exist, RBM10v1 and RBM10v2. Both variants have alternate isoforms that differ by one valine residue, at amino acid 354 (RBM10v1) or 277 (RBM10v2). It was recently observed that a novel point mutation at amino acid 354 of RBM10v1, replacing valine with glutamic acid, correlated with preferential expression of an exon 11 inclusion variant of the proliferation regulatory protein NUMB, which is upregulated in lung cancer.
FINDINGS: We demonstrate, using the GLC20 male-derived small cell lung cancer cell line - confirmed to have only one X chromosome - that the two (+/-) valine isoforms of RBM10v1 and RBM10v2 result from alternative splicing. Protein modeling of the RNA Recognition Motif (RRM) within which the alteration occurs, shows that the presence of valine inhibits the formation of one of the two α-helices associated with RRM tertiary structure, whereas the absence of valine supports the α-helical configuration. We then show 2-fold elevated expression of the transcripts encoding the minus valine RBM10v1 isoform in GLC20 cells, compared to those encoding the plus valine isoform. This expression correlates with preferential expression of the lung cancer-associated NUMB exon 11 inclusion variant.
CONCLUSIONS: Our observations suggest that the ability of RBM10v1 to regulate alternative splicing depends, at least in part, on a structural alteration within the second RRM domain, which influences whether RBM10v1 functions to support or repress splicing. A model is presented.

Wang S, Zhao Y, Li D, et al.
Identification of biomarkers for the prognosis of pancreatic ductal adenocarcinoma with miRNA microarray data.
Int J Biol Markers. 2015; 30(2):e226-33 [PubMed] Related Publications
BACKGROUND: The aim of this study was to explore the mechanism of chemotherapy resistance and to screen biomarkers of pancreatic ductal adenocarcinoma (PDAC).
METHODS: MicroRNA (miRNA) expression profile data for GSE38781 were downloaded from the Gene Expression Omnibus database. Differentially expressed miRNAs between short-overall survival (OS) and long-OS patients were screened with the limma package in R. The function and protein-protein interaction (PPI) network of the miRNA target genes were further investigated. Finally, multivariate statistical analysis was performed to verify the significant miRNAs obtained in our work.
RESULTS: In total, 66 miRNAs were identified to be differentially expressed. Gene ontology (GO) and pathway enrichment analysis showed that 163 miRNA target genes were mainly enriched in heart function, cancer development and angiogenesis. Ten nodes, including TGFBR1, TGFBR2, ACVR1 and SHC1, were found to be hub nodes in the PPI network. Multivariate statistical analysis showed 8 of the most significant miRNAs could completely distinguish the 2 groups of samples. Seven target genes (i.e., RET, ETS1, RHOA, NUMB, TIAM, ITGA5 and YY1) of the 8 significant miRNAs were found to be associated with control of cell fate decisions, T-cell lymphoma invasion and angiogenesis enhancement.
CONCLUSIONS: The heart function-related pathway, cell cycle, immune system and angiogenesis may be dysregulated in patients with poorer prognosis. The significant nodes (e.g., TGFBR1, TGFBR2, ACVR1 and SHC1) in the PPI network may be potential biomarkers for predicting outcomes for patients with pancreatic cancer. The significant miRNAs and gene targets may be potential biomarkers or therapeutic targets for PDAC.

Sima J, Zhang B, Yu Y, et al.
Overexpression of Numb suppresses growth, migration, and invasion of human clear cell renal cell carcinoma cells.
Tumour Biol. 2015; 36(4):2885-92 [PubMed] Related Publications
The objective of the study was to investigate the impact of Numb on cell growth, cell migration, and invasion in human clear cell renal cell carcinoma (ccRCC). Endogenous expression of Numb was evaluated in the ccRCC cell lines (786-O, Caki-1, and Caki-2) and control reference human renal proximal tubular epithelial cells. Numb expression was decreased in the ccRCC cells compared with the control cells (P < 0.01). Then, 786-O and Caki-1 cells described as suitable transfection hosts were used in transfection to carry out biological function studies. The three experimental groups were as follows: Numb-ORF (transfected with Numb-ORF plasmid), blank-vector (transfected with pCMV6-entry), and cell-alone group (no DNA). Numb expression in the Numb-ORF groups was significantly higher than that in the controls (P < 0.01). Cell growth was remarkably reduced (P < 0.01), and the number of migrating or invading cells was reduced (P < 0.01) in the Numb-ORF groups compared with controls. Furthermore, the ratio of G0/G1 phase in the Numb-ORF group of 786-O cells was increased, and the S phase fraction and proliferation index was decreased (P < 0.01). Cyclin D1 and MMP-9 expression was reduced in the Numb-ORF groups compared with controls. Here, we have provided data for attenuated Numb expression in the ccRCC cells. Overexpression of Numb could induce G0/G1 phase arrest and inhibit cell proliferation, migration, and invasion. The suppressive effects might be due to downregulation of cyclin D1 or MMP-9 expression. Taken together, our data suggest that Numb may possibly function as a tumor suppressor involved in the carcinogenesis of ccRCC.

Machida K, Feldman DE, Tsukamoto H
TLR4-dependent tumor-initiating stem cell-like cells (TICs) in alcohol-associated hepatocellular carcinogenesis.
Adv Exp Med Biol. 2015; 815:131-44 [PubMed] Related Publications
Alcohol abuse predisposes individuals to the development of hepatocellular carcinoma (HCC) and synergistically heightens the HCC risk in patients infected with hepatitis C virus (HCV). The mechanisms of this synergism have been elusive until our recent demonstration of the obligatory role of ectopically expressed TLR4 in liver tumorigenesis in alcohol-fed HCV Ns5a or Core transgenic mice. CD133+/CD49f+ tumor-initiating stem cell-like cells (TICs) isolated from these models are tumorigenic in a manner dependent on TLR4 and NANOG. TICs' tumor-initiating activity and chemoresistance are causally associated with inhibition of TGF-β tumor suppressor pathway due to NANOG-mediated expression of IGF2BP3 and YAP1. TLR4/NANOG activation causes p53 degradation via phosphorylation of the protective protein NUMB and its dissociation from p53 by the oncoprotein TBC1D15. Nutrient deprivation reduces overexpressed TBC1D15 in TICs via autophagy-mediated degradation, suggesting a possible role of this oncoprotein in linking metabolic reprogramming and self-renewal.

Kaeda J, Ringel F, Oberender C, et al.
Up-regulated MSI2 is associated with more aggressive chronic myeloid leukemia.
Leuk Lymphoma. 2015; 56(7):2105-13 [PubMed] Related Publications
A better understanding of events triggering chronic myeloid leukemia progression is critical for optimized clinical management of chronic myeloid leukemia (CML). We sought to validate that increased expression of Musashi 2 (MSI2), a post-transcription regulator, is associated with progression and prognosis. Screening of 152 patients with CML showed that MSI2 was significantly decreased among patients with CML in chronic phase (CP) at diagnosis (p < 0.0001), but found no significant difference between the normal control group and treated patients with CML in CP. Moreover MSI2 was significantly increased (p < 0.0001) in patients with advance disease (AD) CML. Furthermore, our human hematopoietic cell line data imply that MSI2 and BCR-ABL1 mRNA expression are correlated. However, these data cast a doubt on earlier reports that MSI2 effects HES1 expression via NUMB-NOTCH signaling.

Hong J, Liu Z, Zhu H, et al.
The tumor suppressive role of NUMB isoform 1 in esophageal squamous cell carcinoma.
Oncotarget. 2014; 5(14):5602-14 [PubMed] Free Access to Full Article Related Publications
Esophageal quamous cell carcinoma (ESCC) is the predominant histological type of esophageal carcinoma in Asian populations. To date, few biomarkers have been identified for ESCC. In present study, we found a tumor suppressor, NUMB isoform 1 (NUMB-1), as a promising prognostic biomarker for patients with ESCC. NUMB-1 mRNA was downregulated in 66.7% of primary ESCC tissues when compared with matched adjacent non-tumor tissues. The low expression of NUMB-1 was significantly associated with high tumor recurrence (p=0.029) and poor post-operative overall survival (p=0.016). To further explore the underlying mechanisms by which NUMB-1 regulates ESCC, we demonstrated that ectopic expression of NUMB-1 inhibited cell proliferation through inducing G2/M phase arrest, which was accompanied by an increase in p21 and cyclin B1-cdc2 levels. However, it had no impact on apoptosis of ESCC cells. In addition, overexpression of NUMB-1 prevented epithelial-mesenchymal transition, inhibited invasion of ESCC cells and NOTCH pathway, suppressed Aurora-A activity by preventing phosphorylation of Aurora-A at T288 which resulted in cell cycle arrest. Taken together, our findings suggested NUMB-1 functions as a tumor-suppressor and serves as a prognositc biomarker for ESCC patients; thus, NUMB-1 may be a potential novel therapeutic target for treatment of ESCC.

Rafnar T, Sulem P, Thorleifsson G, et al.
Genome-wide association study yields variants at 20p12.2 that associate with urinary bladder cancer.
Hum Mol Genet. 2014; 23(20):5545-57 [PubMed] Related Publications
Genome-wide association studies (GWAS) of urinary bladder cancer (UBC) have yielded common variants at 12 loci that associate with risk of the disease. We report here the results of a GWAS of UBC including 1670 UBC cases and 90 180 controls, followed by replication analysis in additional 5266 UBC cases and 10 456 controls. We tested a dataset containing 34.2 million variants, generated by imputation based on whole-genome sequencing of 2230 Icelanders. Several correlated variants at 20p12, represented by rs62185668, show genome-wide significant association with UBC after combining discovery and replication results (OR = 1.19, P = 1.5 × 10(-11) for rs62185668-A, minor allele frequency = 23.6%). The variants are located in a non-coding region approximately 300 kb upstream from the JAG1 gene, an important component of the Notch signaling pathways that may be oncogenic or tumor suppressive in several forms of cancer. Our results add to the growing number of UBC risk variants discovered through GWAS.

Puca F, Colamaio M, Federico A, et al.
HMGA1 silencing restores normal stem cell characteristics in colon cancer stem cells by increasing p53 levels.
Oncotarget. 2014; 5(10):3234-45 [PubMed] Free Access to Full Article Related Publications
High-mobility group A1 (HMGA1) proteins are architectural chromatinic proteins, abundantly expressed during embryogenesis and in most cancer tissues, but expressed at low levels or absent in normal adult tissues. Several studies have demonstrated that HMGA1 proteins play a causal role in neoplastic cell transformation. The aim of this study was to investigate the role of these proteins in the control of cancer stem cells (CSCs), which have emerged as a preferred target in cancer therapy, because of their role in cancer recurrence. We observed that HMGA1 is overexpressed in colon tumour stem cell (CTSC) lines compared to normal and colon cancer tissues. We demonstrated that HMGA1 silencing in CTSCs increases stem cell quiescence and reduces self-renewal and sphere-forming efficiency (SFE). The latter, together with the upregulation and asymmetric distribution of NUMB, is indicative of the recovery of an asymmetric division pattern, typical of normal stem cells. We further found that HMGA1 transcriptionally regulates p53, which is known to control the balance between symmetric and asymmetric divisions in CSCs. Therefore, our data indicate a critical role for HMGA1 in regulating both self-renewal and the symmetric/asymmetric division ratio in CSCs, suggesting that blocking HMGA1 function may be an effective anti-cancer therapy.

Wu J, Shen SL, Chen B, et al.
Numb promotes cell proliferation and correlates with poor prognosis in hepatocellular carcinoma.
PLoS One. 2014; 9(4):e95849 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Numb is an evolutionary conserved protein that plays critical roles in cell fate determination, cell adhesion, cell migration and a number of signaling pathways, but evidence for a substantial involvement of Numb in HCC has remained unclear. The present study was aimed to investigate the clinical and prognostic significance of Numb and its role in hepatocellular carcinoma (HCC).
METHODOLOGY: The expression of Numb was detected in 107 cases of clinical paraffin-embedded hepatocellular carcinoma tissues,5 matched paris of fresh tissues and six hepatocellular cell lines by immunohistochemistry with clinicopathological analyses,RT-PCR or Western blot. Moreover, loss of function and gain of function assays were performed to evaluate the effect of Numb on cell proliferation in vitro.
CONCLUSIONS: We found that Numb was obviously up-regulated in HCC tissues and cell lines (p<0.05). The Numb up-regulation correlated significantly with poor prognosis, and Numb status was identified as an independent prognostic factor. Over-expression of Numb increased proliferation in SMMC-7721 and BEL-7402 cells, while knock-down of Numb showed the opposite effect. Our study indicates that Numb up-regulation significantly correlates with cell proliferation and poor prognosis in hepatocellular carcinoma patients. It may be a useful biomarker for therapeutic strategy in hepatocellular carcinoma treatment.

Zong FY, Fu X, Wei WJ, et al.
The RNA-binding protein QKI suppresses cancer-associated aberrant splicing.
PLoS Genet. 2014; 10(4):e1004289 [PubMed] Free Access to Full Article Related Publications
Lung cancer is the leading cause of cancer-related death worldwide. Aberrant splicing has been implicated in lung tumorigenesis. However, the functional links between splicing regulation and lung cancer are not well understood. Here we identify the RNA-binding protein QKI as a key regulator of alternative splicing in lung cancer. We show that QKI is frequently down-regulated in lung cancer, and its down-regulation is significantly associated with a poorer prognosis. QKI-5 inhibits the proliferation and transformation of lung cancer cells both in vitro and in vivo. Our results demonstrate that QKI-5 regulates the alternative splicing of NUMB via binding to two RNA elements in its pre-mRNA, which in turn suppresses cell proliferation and prevents the activation of the Notch signaling pathway. We further show that QKI-5 inhibits splicing by selectively competing with a core splicing factor SF1 for binding to the branchpoint sequence. Taken together, our data reveal QKI as a critical regulator of splicing in lung cancer and suggest a novel tumor suppression mechanism involving QKI-mediated regulation of the Notch signaling pathway.

Kim SY, Hong C, Wie J, et al.
Reciprocal positive regulation between TRPV6 and NUMB in PTEN-deficient prostate cancer cells.
Biochem Biophys Res Commun. 2014; 447(1):192-6 [PubMed] Related Publications
Calcium acts as a second messenger and plays a crucial role in signaling pathways involved in cell proliferation. Recently, calcium channels related to calcium influx into the cytosol of epithelial cells have attracted attention as a cancer therapy target. Of these calcium channels, TRPV6 is overexpressed in prostate cancer and is considered an important molecule in the process of metastasis. However, its exact role and mechanism is unclear. NUMB, well-known tumor suppressor gene, is a novel interacting partner of TRPV6. We show that NUMB and TRPV6 have a reciprocal positive regulatory relationship in PC-3 cells. We repeated this experiment in two other prostate cancer cell lines, DU145 and LNCaP. Interestingly, there were no significant changes in TRPV6 expression following NUMB knockdown in DU145. We revealed that the presence or absence of PTEN was the cause of NUMB-TRPV6 function. Loss of PTEN caused a positive correlation of TRPV6-NUMB expression. Collectively, we determined that PTEN is a novel interacting partner of TRPV6 and NUMB. These results demonstrated a novel relationship of NUMB-TRPV6 in prostate cancer cells, and show that PTEN is a novel regulator of this complex.

Zhang S, Liu Y, Liu Z, et al.
Transcriptome profiling of a multiple recurrent muscle-invasive urothelial carcinoma of the bladder by deep sequencing.
PLoS One. 2014; 9(3):e91466 [PubMed] Free Access to Full Article Related Publications
Urothelial carcinoma of the bladder (UCB) is one of the commonly diagnosed cancers in the world. The UCB has the highest rate of recurrence of any malignancy. A genome-wide screening of transcriptome dysregulation between cancer and normal tissue would provide insight into the molecular basis of UCB recurrence and is a key step to discovering biomarkers for diagnosis and therapeutic targets. Compared with microarray technology, which is commonly used to identify expression level changes, the recently developed RNA-seq technique has the ability to detect other abnormal regulations in the cancer transcriptome, such as alternative splicing. In this study, we performed high-throughput transcriptome sequencing at ∼50× coverage on a recurrent muscle-invasive cisplatin-resistance UCB tissue and the adjacent non-tumor tissue. The results revealed cancer-specific differentially expressed genes between the tumor and non-tumor tissue enriched in the cell adhesion molecules, focal adhesion and ECM-receptor interaction pathway. Five dysregulated genes, including CDH1, VEGFA, PTPRF, CLDN7, and MMP2 were confirmed by Real time qPCR in the sequencing samples and the additional eleven samples. Our data revealed that more than three hundred genes showed differential splicing patterns between tumor tissue and non-tumor tissue. Among these genes, we filtered 24 cancer-associated alternative splicing genes with differential exon usage. The findings from RNA-Seq were validated by Real time qPCR for CD44, PDGFA, NUMB, and LPHN2. This study provides a comprehensive survey of the UCB transcriptome, which provides better insight into the complexity of regulatory changes during recurrence and metastasis.

Hwang WL, Jiang JK, Yang SH, et al.
MicroRNA-146a directs the symmetric division of Snail-dominant colorectal cancer stem cells.
Nat Cell Biol. 2014; 16(3):268-80 [PubMed] Related Publications
Asymmetrical cell division (ACD) maintains the proper number of stem cells to ensure self-renewal. In cancer cells, the deregulation of ACD disrupts the homeostasis of the stem cell pool and promotes tumour growth. However, this mechanism is unclear. Here, we show a reduction of ACD in spheroid-derived colorectal cancer stem cells (CRCSCs) compared with differentiated cancer cells. The epithelial-mesenchymal transition (EMT) inducer Snail is responsible for the ACD-to-symmetrical cell division (SCD) switch in CRCSCs. Mechanistically, Snail induces the expression of microRNA-146a (miR-146a) through the β-catenin-TCF4 complex. miR-146a targets Numb to stabilize β-catenin, which forms a feedback circuit to maintain Wnt activity and directs SCD. Interference with the Snail-miR-146a–β-catenin loop by inhibiting the MEK or Wnt activity reduces the symmetrical division of CRCSCs and attenuates tumorigenicity. In colorectal cancer patients, the Snail(High)Numb(Low) profile is correlated with cetuximab resistance and a poorer prognosis. This study elucidates a unique mechanism of EMT-induced CRCSC expansion.

Forloni M, Dogra SK, Dong Y, et al.
miR-146a promotes the initiation and progression of melanoma by activating Notch signaling.
Elife. 2014; 3:e01460 [PubMed] Free Access to Full Article Related Publications
Oncogenic mutations in BRAF and NRAS occur in 70% of melanomas. In this study, we identify a microRNA, miR-146a, that is highly upregulated by oncogenic BRAF and NRAS. Expression of miR-146a increases the ability of human melanoma cells to proliferate in culture and form tumors in mice, whereas knockdown of miR-146a has the opposite effects. We show these oncogenic activities are due to miR-146a targeting the NUMB mRNA, a repressor of Notch signaling. Previous studies have shown that pre-miR-146a contains a single nucleotide polymorphism (C>G rs2910164). We find that the ability of pre-miR-146a/G to activate Notch signaling and promote oncogenesis is substantially higher than that of pre-miR-146a/C. Analysis of melanoma cell lines and matched patient samples indicates that during melanoma progression pre-miR-146a/G is enriched relative to pre-miR-146a/C, resulting from a C-to-G somatic mutation in pre-miR-146a/C. Collectively, our results reveal a central role for miR-146a in the initiation and progression of melanoma. DOI:

Pastò A, Serafin V, Pilotto G, et al.
NOTCH3 signaling regulates MUSASHI-1 expression in metastatic colorectal cancer cells.
Cancer Res. 2014; 74(7):2106-18 [PubMed] Related Publications
MUSASHI-1 (MSI-1) is a well-established stem cell marker in both normal and malignant colon cells and it acts by positively regulating the NOTCH pathway through inactivation of NUMB, a NOTCH signaling repressor. To date, the mechanisms of regulation of MSI-1 levels remain largely unknown. Here, we investigated the regulation of MSI-1 by NOTCH signaling in colorectal cancer cell lines and in primary cultures of colorectal cancer metastases. Stimulation by the NOTCH ligand DLL4 was associated with an increase of MSI-1 mRNA and protein levels, and this phenomenon was prevented by the addition of an antibody neutralizing NOTCH2/3 but not NOTCH1. Moreover, forced expression of activated NOTCH3 increased MSI-1 levels, whereas silencing of NOTCH3 by short hairpin RNA reduced MSI-1 levels in both colorectal cancer cells and CRC tumor xenografts. Consistent with these findings, enforced NOTCH3 expression or stimulation by DLL4 increased levels of activated NOTCH1 in colorectal cell lines. Finally, treatment of colorectal cancer cells with anti-NOTCH2/3 antibody increased NUMB protein while significantly reducing formation of tumor cell spheroids. This novel feed-forward circuit involving DLL4, NOTCH3, MSI-1, NUMB, and NOTCH1 may be relevant for regulation of NOTCH signaling in physiologic processes as well as in tumor development. With regard to therapeutic implications, NOTCH3-specific drugs could represent a valuable strategy to limit NOTCH signaling in the context of colorectal cancers overexpressing this receptor.

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