Gene Summary

Gene:SKI; SKI proto-oncogene
Aliases: SGS, SKV
Summary:This gene encodes the nuclear protooncogene protein homolog of avian sarcoma viral (v-ski) oncogene. It functions as a repressor of TGF-beta signaling, and may play a role in neural tube development and muscle differentiation. [provided by RefSeq, Oct 2009]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:ski oncogene
Source:NCBIAccessed: 17 August, 2015


What does this gene/protein do?
Show (56)

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 17 August 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Pyrimidines
  • Neoplastic Cell Transformation
  • Messenger RNA
  • Apoptosis
  • beta Catenin
  • SKI
  • Nuclear Proteins
  • Transcription Factors
  • DNA-Binding Proteins
  • Melanoma
  • Nitriles
  • MicroRNAs
  • Cell Proliferation
  • siRNA
  • Aniline Compounds
  • Breast Cancer
  • Down-Regulation
  • Fusion Proteins, bcr-abl
  • Intracellular Signaling Peptides and Proteins
  • Proto-Oncogene Proteins
  • Cell Differentiation
  • Chromosome Aberrations
  • Chromosome 1
  • Transfection
  • Leukemia, Promyelocytic, Acute
  • Western Blotting
  • Transcription
  • Quinolines
  • Drug Resistance
  • Immunohistochemistry
  • Signal Transduction
  • Cancer Gene Expression Regulation
  • Base Sequence
  • Gene Expression Profiling
  • Antineoplastic Agents
  • Enzyme Inhibitors
  • Disease Progression
  • Trans-Activators
  • Protein Kinase Inhibitors
  • Mutation
Tag cloud generated 17 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (2)

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: SKI (cancer-related)

Somasekharan SP, El-Naggar A, Leprivier G, et al.
YB-1 regulates stress granule formation and tumor progression by translationally activating G3BP1.
J Cell Biol. 2015; 208(7):913-29 [PubMed] Article available free on PMC after 30/09/2015 Related Publications
Under cell stress, global protein synthesis is inhibited to preserve energy. One mechanism is to sequester and silence mRNAs in ribonucleoprotein complexes known as stress granules (SGs), which contain translationally silent mRNAs, preinitiation factors, and RNA-binding proteins. Y-box binding protein 1 (YB-1) localizes to SGs, but its role in SG biology is unknown. We now report that YB-1 directly binds to and translationally activates the 5' untranslated region (UTR) of G3BP1 mRNAs, thereby controlling the availability of the G3BP1 SG nucleator for SG assembly. YB-1 inactivation in human sarcoma cells dramatically reduces G3BP1 and SG formation in vitro. YB-1 and G3BP1 expression are highly correlated in human sarcomas, and elevated G3BP1 expression correlates with poor survival. Finally, G3BP1 down-regulation in sarcoma xenografts prevents in vivo SG formation and tumor invasion, and completely blocks lung metastasis in mouse models. Together, these findings demonstrate a critical role for YB-1 in SG formation through translational activation of G3BP1, and highlight novel functions for SGs in tumor progression.

Renouf B, Piganeau M, Ghezraoui H, et al.
Creating cancer translocations in human cells using Cas9 DSBs and nCas9 paired nicks.
Methods Enzymol. 2014; 546:251-71 [PubMed] Article available free on PMC after 30/09/2015 Related Publications
Recurrent chromosomal translocations are found in numerous tumor types, often leading to the formation and expression of fusion genes with oncogenic potential. Creating chromosomal translocations at the relevant endogenous loci, rather than ectopically expressing the fusion genes, opens new possibilities for better characterizing molecular mechanisms driving tumor formation. In this chapter, we describe methods to create cancer translocations in human cells. DSBs or paired nicks generated by either wild-type Cas9 or the Cas9 nickase, respectively, are used to induce translocations at the relevant loci. Using different PCR-based methods, we also explain how to quantify translocation frequency and to analyze breakpoint junctions in the cells of interest. In addition, PCR detection of translocations is used as a very sensitive method to detect off-target effects, which has general utility.

Xu LD, Muller S, Thoppe SR, et al.
Expression of the p53 target Wig-1 is associated with HPV status and patient survival in cervical carcinoma.
PLoS One. 2014; 9(11):e111125 [PubMed] Article available free on PMC after 30/09/2015 Related Publications
The p53 target gene WIG-1 (ZMAT3) is located in chromosomal region 3q26, that is frequently amplified in human tumors, including cervical cancer. We have examined the status of WIG-1 and the encoded Wig-1 protein in cervical carcinoma cell lines and tumor tissue samples. Our analysis of eight cervical cancer lines (Ca Ski, ME-180, MS751, SiHa, SW756, C-4I, C-33A, and HT-3) by spectral karyotype, comparative genomic hybridization and Southern blotting revealed WIG-1 is not the primary target for chromosome 3 gains. However, WIG-1/Wig-1 were readily expressed and WIG-1 mRNA expression was higher in the two HPV-negative cervical cell lines (C33-A, HT-3) than in HPV-positive lines. We then assessed Wig-1 expression by immunohistochemistry in 38 cervical tumor samples. We found higher nuclear Wig-1 expression levels in HPV-negative compared to HPV positive cases (p = 0.002) and in adenocarcinomas as compared to squamous cell lesions (p<0.0001). Cases with moderate nuclear Wig-1 staining and positive cytoplasmic Wig-1 staining showed longer survival than patients with strong nuclear and negative cytoplasmic staining (p = 0.042). Nuclear Wig-1 expression levels were positively associated with age at diagnosis (p = 0.023) and histologic grade (p = 0.034). These results are consistent with a growth-promoting and/or anti-cell death function of nuclear Wig-1 and suggest that Wig-1 expression can serve as a prognostic marker in cervical carcinoma.

Verbeke SL, de Jong D, Bertoni F, et al.
Array CGH analysis identifies two distinct subgroups of primary angiosarcoma of bone.
Genes Chromosomes Cancer. 2015; 54(2):72-81 [PubMed] Related Publications
Molecular genetic studies on vascular tumors are rare. Recently, possible involvement of MYC and KDR has been documented in a subset of angiosarcomas of soft tissue. We performed a cytogenetic analysis of primary angiosarcomas of bone (n = 13) and soft tissue (n = 5) using high density array-comparative genomic hybridization (array-CGH). Regions of interest were validated by fluorescence in situ hybridization (FISH). Antibodies for candidate genes (SKI, MYC, KDR, and MAPK9) were selected and immunohistochemistry was performed. Six angiosarcomas of bone and four angiosarcomas of soft tissue showed chromosomal losses, gains, and high level amplifications. Cluster analysis identified two groups: a group with a complex genetic profile and a group with only few genetic aberrations. Five regions of interest were selected, which were located at chromosome bands 1p36.23, 2q32-34, 5q35, 8q24, and 17q21.32-24.2. Interphase FISH confirmed the high-level amplifications. Immunohistochemical analysis showed high expression of MYC (16/60), MAPK9 (63/69), and SKI (52/62). There were no differences between the two groups with regards to location, immunohistochemical expression nor survival. In summary, we identified two subgroups of angiosarcoma: those with few or no gross aberrations and those which show numerous genetic aberrations consisting of chromosomal losses, gains and high level amplifications or complex aberrations. The most common finding was amplification of 2q and 17q in both angiosarcoma of bone and soft tissue, suggesting overlap in tumorigenesis irrespective of their location. We show MYC amplification in primary angiosarcoma indicating this is not entirely specific for radiation-induced angiosarcoma.

Gao W, Wang M, Wang L, et al.
Selective antitumor activity of ibrutinib in EGFR-mutant non-small cell lung cancer cells.
J Natl Cancer Inst. 2014; 106(9) [PubMed] Article available free on PMC after 01/09/2015 Related Publications
Ibrutinib, which irreversibly inhibits Bruton tyrosine kinase, was evaluated for antitumor activity in a panel of non-small cell lung cancer (NSCLC) cell lines and found to selectively inhibit growth of NSCLC cells carrying mutations in the epidermal growth factor receptor (EGFR) gene, including T790M mutant and erlotinib-resistant H1975 cells. Ibrutinib induced dose-dependent inhibition of phosphor-EGFR at both Y1068 and Y1173 sites, suggesting ibrutinib functions as an EGFR inhibitor. Survival was analyzed by Kaplan-Meier estimation and log-rank test. All statistical tests were two-sided. In vivo study showed that ibrutinib statistically significantly suppressed H1975 tumor growth and prolonged survival of the tumor bearing mice (n = 5 per group). The mean survival times for solvent- and erlotinib-treated mice were both 17.8 days (95% confidence interval [CI] = 14.3 to 21.3 days), while the mean survival time for ibrutinib-treated mice was 29.8 days (95% CI = 26.0 to 33.6 days, P = .008). Our results indicate that ibrutinib could be a candidate drug for treatment of EGFR-mutant NSCLC, including erlotinib-resistant tumors.

Li W, Cooper J, Zhou L, et al.
Merlin/NF2 loss-driven tumorigenesis linked to CRL4(DCAF1)-mediated inhibition of the hippo pathway kinases Lats1 and 2 in the nucleus.
Cancer Cell. 2014; 26(1):48-60 [PubMed] Article available free on PMC after 01/09/2015 Related Publications
It is currently unclear whether Merlin/NF2 suppresses tumorigenesis by activating upstream components of the Hippo pathway at the plasma membrane or by inhibiting the E3 ubiquitin ligase CRL4(DCAF1) in the nucleus. We found that derepressed CRL4(DCAF1) promotes YAP- and TEAD-dependent transcription by ubiquitylating and, thereby, inhibiting Lats1 and 2 in the nucleus. Genetic epistasis experiments and analysis of tumor-derived missense mutations indicate that this signaling connection sustains the oncogenicity of Merlin-deficient tumor cells. Analysis of clinical samples confirms that this pathway operates in NF2-mutant tumors. We conclude that derepressed CRL4(DCAF1) promotes activation of YAP by inhibiting Lats1 and 2 in the nucleus.

Melnick M, Deluca KA, Jaskoll T
CMV-induced pathology: pathway and gene-gene interaction analysis.
Exp Mol Pathol. 2014; 97(1):154-65 [PubMed] Related Publications
Mucoepidermoid carcinoma (MEC) is the most prevalent malignant tumor in major and minor salivary glands (SGs). We have recently identified human cytomegalovirus (hCMV) as a principle component in the multifactorial causation of SG-MEC. This finding is corroborated by the ability of the purified mouse CMV (mCMV) to induce malignant transformation of SG cells in a three-dimensional in vitro mouse model, using a similar oncogenic signaling pathway. Our prior studies indicate that the core tumor microenvironment (TME) is a key regulator of pathologic progression, particularly the cancer-associated fibroblast (CAF) component. Studies of early CAFs immunodetect aberrant expression of ECM components, as well as multiple growth factors, cytokines and transcription factors. Here we present the mechanistic insight derived from a mathematical structure ("wiring diagram") used to model complex relationships between a highly relevant (p=9.43×10(-12)) global "cancer network" of 32 genes and their known links. Detailed characterization of the functional architecture of the examined "cancer network" exposes the critical crosstalk and compensatory pathways that limit the efficacy of targeted anti-kinase therapies.

Rajgor D, Mellad JA, Soong D, et al.
Mammalian microtubule P-body dynamics are mediated by nesprin-1.
J Cell Biol. 2014; 205(4):457-75 [PubMed] Article available free on PMC after 01/09/2015 Related Publications
Nesprins are a multi-isomeric family of spectrin-repeat (SR) proteins, predominantly known as nuclear envelope scaffolds. However, isoforms that function beyond the nuclear envelope remain poorly examined. Here, we characterize p50(Nesp1), a 50-kD isoform that localizes to processing bodies (PBs), where it acts as a microtubule-associated protein capable of linking mRNP complexes to microtubules. Overexpression of dominant-negative p50(Nesp1) caused Rck/p54, but not GW182, displacement from microtubules, resulting in reduced PB movement and cross talk with stress granules (SGs). These cells disassembled canonical SGs induced by sodium arsenite, but not those induced by hydrogen peroxide, leading to cell death and revealing PB-microtubule attachment is required for hydrogen peroxide-induced SG anti-apoptotic functions. Furthermore, p50(Nesp1) was required for miRNA-mediated silencing and interacted with core miRISC silencers Ago2 and Rck/p54 in an RNA-dependent manner and with GW182 in a microtubule-dependent manner. These data identify p50(Nesp1) as a multi-functional PB component and microtubule scaffold necessary for RNA granule dynamics and provides evidence for PB and SG micro-heterogeneity.

Wang L, Zhang M, Wu Y, et al.
SKIP expression is correlated with clinical prognosis in patients with bladder cancer.
Int J Clin Exp Pathol. 2014; 7(4):1695-701 [PubMed] Article available free on PMC after 01/09/2015 Related Publications
The Ski-interacting protein (SKIP) is a transcriptional cofactor distinct from other cofactors and is involved in regulation of many cancer-related proteins. However, its distribution and clinical significances in bladder cancer remains poorly understood. In this study, Quantitative real-time PCR and immunohistochemistry were performed to detect the expression of SKIP in clinical bladder cancer samples. In addition, the correlation of SKIP expression and clinicopathological features and clinical outcomes were analyzed. The expression levels of SKIP in clinical bladder cancer were much higher than that in paired adjacent noncancerous tissues. High expression of SKIP was closely related with histological grades and the poor prognosis of bladder cancer. Based on our data, we speculated that SKIP may be a potential prognostic marker in bladder cancer.

Isfort S, Keller-v Amsberg G, Schafhausen P, et al.
Bosutinib: a novel second-generation tyrosine kinase inhibitor.
Recent Results Cancer Res. 2014; 201:81-97 [PubMed] Related Publications
Bosutinib (SKI-606) is a 4-anilino-3-quinoline carbonitrile, which acts as a dual inhibitor of Src and ABL kinases. In addition, the BCR-ABL fusion gene product, a constitutively activated tyrosine kinase which is crucial for the development of chronic myeloid leukemia (CML), is highly sensitive to bosutinib. Interestingly, distinctly lower concentrations of bosutinib are required to ablate BCR-ABL phosphorylation when compared to the first-generation tyrosine kinase inhibitor imatinib (IM). Bosutinib is a potent inhibitor of CML cell proliferation in vitro and has demonstrated promising activity in CML patients resistant or intolerant to IM as well as in newly diagnosed patients with chronic phase CML (CML-CP). Remarkably, bosutinib has been found to be capable of overcoming the majority of IM-resistant BCR-ABL mutations. Bosutinib has the potency to induce deep and fast responses in second- and third-/fourth-line treatment, and as a consequence, the drug has recently been licensed for patients previously treated with one or more tyrosine kinase inhibitor(s) and for whom imatinib, nilotinib, and dasatinib are not considered appropriate treatment options. Due to its potency and differing toxicity profile, it promises to be a good therapeutic option for a defined cohort of patients. The most common side effects are gastrointestinal with most of the patients suffering from nausea, vomiting, or diarrhea. For the most part, these gastrointestinal symptoms occur early after treatment initiation, are manageable, and often self-limiting. Continuous monitoring of liver enzymes upon treatment initiation is necessary during bosutinib treatment. In addition to CML treatment, bosutinib has shown some efficacy in selected patients suffering from advanced-stage solid tumors. In conclusion, bosutinib is a promising novel small molecule inhibitor approved now for targeted therapy of CML and in clinical development for other malignancies.

Tulley S, Chen WT
Transcriptional regulation of seprase in invasive melanoma cells by transforming growth factor-β signaling.
J Biol Chem. 2014; 289(22):15280-96 [PubMed] Article available free on PMC after 01/09/2015 Related Publications
The tumor invasive phenotype driven by seprase expression/activity has been widely examined in an array of malignant tumor cell types; however, very little is known about the transcriptional regulation of this critical protease. Seprase (also named fibroblast activation protein-α, antiplasmin-cleaving enzyme, and dipeptidyl prolyl peptidase 5) is expressed at high levels by stromal fibroblast, endothelial, and tumor cells in a variety of invasive tumors but is undetectable in the majority of normal adult tissues. To examine the transcriptional regulation of the gene, we cloned the human seprase promoter and demonstrated that endogenous seprase expression and exogenous seprase promoter activity are high in invasive melanoma cells but not in non-invasive melanoma cells/primary melanocytes. In addition, we identified a crucial TGF-β-responsive cis-regulatory element in the proximal seprase promoter region that enabled robust transcriptional activation of the gene. Treatment of metastatic but not normal/non-invasive cells with TGF-β1 caused a rapid and profound up-regulation of endogenous seprase mRNA, which coincided with an abolishment of the negative regulator c-Ski, and an increase in binding of Smad3/4 to the seprase promoter in vivo. Blocking TGF-β signaling in invasive melanoma cells through overexpression of c-Ski, chemically using SB-431542, or with a neutralizing antibody against TGF-β significantly reduced seprase mRNA levels. Strikingly, RNAi of seprase in invasive cells greatly diminished their invasive potential in vitro as did blocking TGF-β signaling using SB-431542. Altogether, we found that seprase is transcriptionally up-regulated in invasive melanoma cells via the canonical TGF-β signaling pathway, supporting the roles of both TGF-β and seprase in tumor invasion and metastasis.

Cooper J, Giancotti FG
Molecular insights into NF2/Merlin tumor suppressor function.
FEBS Lett. 2014; 588(16):2743-52 [PubMed] Article available free on PMC after 19/08/2015 Related Publications
The FERM domain protein Merlin, encoded by the NF2 tumor suppressor gene, regulates cell proliferation in response to adhesive signaling. The growth inhibitory function of Merlin is induced by intercellular adhesion and inactivated by joint integrin/receptor tyrosine kinase signaling. Merlin contributes to the formation of cell junctions in polarized tissues, activates anti-mitogenic signaling at tight-junctions, and inhibits oncogenic gene expression. Thus, inactivation of Merlin causes uncontrolled mitogenic signaling and tumorigenesis. Merlin's predominant tumor suppressive functions are attributable to its control of oncogenic gene expression through regulation of Hippo signaling. Notably, Merlin translocates to the nucleus where it directly inhibits the CRL4(DCAF1) E3 ubiquitin ligase, thereby suppressing inhibition of the Lats kinases. A dichotomy in NF2 function has emerged whereby Merlin acts at the cell cortex to organize cell junctions and propagate anti-mitogenic signaling, whereas it inhibits oncogenic gene expression through the inhibition of CRL4(DCAF1) and activation of Hippo signaling. The biochemical events underlying Merlin's normal function and tumor suppressive activity will be discussed in this Review, with emphasis on recent discoveries that have greatly influenced our understanding of Merlin biology.

Jiang H, Jin C, Liu J, et al.
Next generation sequencing analysis of miRNAs: MiR-127-3p inhibits glioblastoma proliferation and activates TGF-β signaling by targeting SKI.
OMICS. 2014; 18(3):196-206 [PubMed] Article available free on PMC after 19/08/2015 Related Publications
Glioblastoma (GBM) proliferation is a multistep process during which the expression levels of many genes that control cell proliferation, cell death, and genetic stability are altered. MicroRNAs (miRNAs) are emerging as important modulators of cellular signaling, including cell proliferation in cancer. In this study, using next generation sequencing analysis of miRNAs, we found that miR-127-3p was downregulated in GBM tissues compared with normal brain tissues; we validated this result by RT-PCR. We further showed that DNA demethylation and histone deacetylase inhibition resulted in downregulation of miR-127-3p. We demonstrated that miR-127-3p overexpression inhibited GBM cell growth by inducing G1-phase arrest both in vitro and in vivo. We showed that miR-127-3p targeted SKI (v-ski sarcoma viral oncogene homolog [avian]), RGMA (RGM domain family, member A), ZWINT (ZW10 interactor, kinetochore protein), SERPINB9 (serpin peptidase inhibitor, clade B [ovalbumin], member 9), and SFRP1 (secreted frizzled-related protein 1). Finally, we found that miR-127-3p suppressed GBM cell growth by inhibiting tumor-promoting SKI and activating the tumor suppression effect of transforming growth factor-β (TGF-β) signaling. This study showed, for the first time, that miR-127-3p and its targeted gene SKI, play important roles in GBM and may serve as potential targets for GBM therapy.

Stansfield L, Hughes TE, Walsh-Chocolaad TL
Bosutinib: a second-generation tyrosine kinase inhibitor for chronic myelogenous leukemia.
Ann Pharmacother. 2013; 47(12):1703-11 [PubMed] Related Publications
OBJECTIVE: To review clinical trials and main characteristics of bosutinib, a second-generation tyrosine kinase inhibitor (TKI) for treatment of chronic myelogenous leukemia (CML).
DATA SOURCES: Pertinent data were identified through a search of PubMed (January 1990-April 2013) using the primary search terms SKI-606, bosutinib, and CML. Additionally, preliminary reports published in abstract form by the American Society of Clinical Oncology and American Society of Hematology (January 1990-April 2013) were screened for inclusion.
STUDY SELECTION AND DATA EXTRACTION: Clinical Phase 1, 2, and 3 studies reported in English evaluating the safety and efficacy of bosutinib in patients with CML were reviewed.
DATA SYNTHESIS: Bosutinib is a TKI of the breakpoint cluster region/Abelson murine leukemia (BCR-ABL) gene approved by the Food and Drug Administration on September 4, 2012, for second-line treatment of chronic phase, accelerated phase, and blast phase CML. In the second-line setting, bosutinib is effective in some patients with CML resistant or intolerant to imatinib, dasatinib, and/or nilotinib, but it is not effective in patients whose disease expresses the T315I point mutation in BCR-ABL. Bosutinib also has been compared with imatinib, the standard first-line treatment, in 502 patients with newly diagnosed chronic phase CML in a Phase 3 trial. Complete cytogenetic response at 12 months, the primary efficacy end point, is similar between bosutinib and imatinib (p = 0.601); therefore, bosutinib is not indicated in the first-line setting. Common adverse events associated with bosutinib include diarrhea, nausea, and vomiting. Grade 3 and 4 adverse events reported in at least 5% of bosutinib-treated patients include elevated serum lipase and liver aminotransferases, anemia, thrombocytopenia, neutropenia, and diarrhea.
CONCLUSIONS: Currently available clinical trials suggest that bosutinib is generally a safe and effective treatment option for patients with CML who have failed first-line TKIs and who do not express the T315I mutation; however, tolerability may be problematic for some patients.

Martin JL, de Silva HC, Lin MZ, et al.
Inhibition of insulin-like growth factor-binding protein-3 signaling through sphingosine kinase-1 sensitizes triple-negative breast cancer cells to EGF receptor blockade.
Mol Cancer Ther. 2014; 13(2):316-28 [PubMed] Related Publications
The type I EGF receptor (EGFR or ErbB1) and insulin-like growth factor-binding protein-3 (IGFBP-3) are highly expressed in triple-negative breast cancer (TNBC), a particularly aggressive disease that cannot be treated with conventional therapies targeting the estrogen or progesterone receptors (ER and PR), or HER2. We have shown previously in normal breast epithelial cells that IGFBP-3 potentiates growth-stimulatory signaling transduced by EGFR, and this is mediated by the sphingosine kinase-1 (SphK1)/sphingosine 1-phosphate (S1P) system. In this study, we investigated whether cotargeting the EGFR and SphK1/S1P pathways in TNBC cells results in greater growth inhibition compared with blocking either alone, and might therefore have novel therapeutic potential in TNBC. In four TNBC cell lines, exogenous IGFBP-3 enhanced ligand-stimulated EGFR activation, associated with increased SphK1 localization to the plasma membrane. The effect of exogenous IGFBP-3 on EGFR activation was blocked by pharmacologic inhibition or siRNA-mediated silencing of SphK1, and silencing of endogenous IGFBP-3 also suppressed EGF-stimulated EGFR activation. Real-time analysis of cell proliferation revealed a combined effect of EGFR inhibition by gefitinib and SphK1 inhibition using SKi-II. Growth of MDA-MB-468 xenograft tumors in mice was significantly inhibited by SKi-II and gefitinib when used in combination, but not as single agents. We conclude that IGFBP-3 promotes growth of TNBC cells by increasing EGFR signaling, that this is mediated by SphK1, and that combined inhibition of EGFR and SphK1 has potential as an anticancer therapy in TNBC in which EGFR and IGFBP-3 expression is high.

Stankic M, Pavlovic S, Chin Y, et al.
TGF-β-Id1 signaling opposes Twist1 and promotes metastatic colonization via a mesenchymal-to-epithelial transition.
Cell Rep. 2013; 5(5):1228-42 [PubMed] Article available free on PMC after 19/08/2015 Related Publications
ID genes are required for breast cancer colonization of the lungs, but the mechanism remains poorly understood. Here, we show that Id1 expression induces a stem-like phenotype in breast cancer cells while retaining epithelial properties, contrary to the notion that cancer stem-like properties are inextricably linked to the mesenchymal state. During metastatic colonization, Id1 induces a mesenchymal-to-epithelial transition (MET), specifically in cells whose mesenchymal state is dependent on the Id1 target protein Twist1, but not at the primary site, where this state is controlled by the zinc finger protein Snail1. Knockdown of Id expression in metastasizing cells prevents MET and dramatically reduces lung colonization. Furthermore, Id1 is induced by transforming growth factor (TGF)-β only in cells that have first undergone epithelial-to-mesenchymal transition (EMT), demonstrating that EMT is a prerequisite for subsequent Id1-induced MET during lung colonization. Collectively, these studies underscore the importance of Id-mediated phenotypic switching during distinct stages of breast cancer metastasis.

Kowli S, Velidandla R, Creek KE, Pirisi L
TGF-β regulation of gene expression at early and late stages of HPV16-mediated transformation of human keratinocytes.
Virology. 2013; 447(1-2):63-73 [PubMed] Article available free on PMC after 19/08/2015 Related Publications
In our in vitro model for HPV16-mediated transformation, HPV16-immortalized human keratinocytes (HKc/HPV16) give rise to differentiation resistant, premalignant cells (HKc/DR). HKc/DR, but not HKc/HPV16, are resistant to growth inhibition by transforming growth factor beta (TGF-β), due to a partial loss of TGF-β receptor type I. We show that TGF-β activates a Smad-responsive reporter construct in HKc/DR to about 50% of the maximum levels of activation observed in HKc/HPV16. To investigate the functional significance of residual TGF-β signaling in HKc/DR, we compared gene expression profiles elicited by TGF-β treatment of HKc/HPV16 and HKc/DR on Agilent 44k human whole genome microarrays. TGF-β altered the expression of cell cycle and MAP kinase pathway genes in HKc/HPV16, but not in HKc/DR. However, epithelial-mesenchymal transition (EMT) responses to TGF-β were comparable in HKc/HPV16 and HKc/DR, indicating that the signaling pathways through which TGF-β elicits growth inhibition diverge from those that induce EMT in HPV16-transformed cells.

Yuan L, Xiao Y, Zhou Q, et al.
Proteomic analysis reveals that MAEL, a component of nuage, interacts with stress granule proteins in cancer cells.
Oncol Rep. 2014; 31(1):342-50 [PubMed] Related Publications
The Maelstrom (MAEL) gene is a cancer-testis (or cancer-germline) gene, which is predominantly expressed in germline cells under normal conditions, but is aberrantly expressed in a range of human cancer cells. In germline cells, MAEL is found predominantly in the nuage, where it plays an essential role in piRNA biogenesis and piRNA-mediated silencing of transposons. However, the role of MAEL in cancer has not been elucidated. We performed immunoprecipitation and Nano-LC-MS/MS analysis to investigate the interactome of MAEL, and identified 14 components of stress granules (SGs) as potential binding partners of MAEL in MDA-MB-231 human breast cancer and SW480 colorectal cancer cells. The interactions between MAEL and 8 of these SG components (PABPC1, YBX1, KHSRP, SYNCRIP, DDX39, ELAV1, EIF4A1 and EIF3F) were confirmed by anti-tag immunoprecipitation. Immunofluorescence analysis showed that MAEL co-localizes with the SG marker PABPC1 in SGs during oxidative stress. Nuages and SGs are the cytoplasmic RNA granules of germline cells and stressed somatic cells, respectively, and both serve as a platform for small RNA-mediated gene silencing. It is, therefore, suggested that MAEL may be involved in miRNA-mediated gene silencing in SGs, as it does in the nuage. This finding should be valuable toward understanding the function of MAEL in carcinogenesis.

Liu X, Ni Q, Xu J, et al.
Expression and prognostic role of SKIP in human breast carcinoma.
J Mol Histol. 2014; 45(2):169-80 [PubMed] Related Publications
Ski-interacting protein (SKIP) is a nuclear hormone receptor-interacting cofactor, interactions with the proto-oncogene Ski, appears to modulate a number of signalling pathways involved in control of cell proliferation and differentiation, and may play a critical role in oncogenesis. In the present study, to investigate the potential roles of SKIP in breast cancer, expression patterns, interaction and the correlation with clinical/prognostic factors of SKIP and Ki-67 were examined among patients with breast cancer. Immunohistochemistry and Western blot analysis were performed for SKIP in 85 breast carcinoma samples. The data were correlated with clinicopathological features. The univariate and multivariate survival analyses were also performed to determine their prognostic significance. We found that SKIP was over expressed in breast carcinoma as compared with the adjacent normal tissues. High expression of SKIP was positively associated with histological grade (P = 0.01) and Ki-67 (P = 0.004). Univariate analysis showed that SKIP expression was associated with a poor prognosis (P = 0.006). While in vitro, following release of breast cancer cell lines from serum starvation, the expression of SKIP was up-regulated, whereas p27 was down-regulated. In addition, we employed small interfering RNA (siRNA) technique to knock down SKIP expression and observed it effects on MDA-MB-231 cells growth. SKIP depletion by siRNA inhibited cell proliferation, blocked S phase and decreased cyclin A and cyclin B levels. On the basis of these results, we suggested that SKIP overexpression was involved in the pathogenesis of breast cancer, which might serve as a future target for breast cancer.

Dozsa A, Dezso B, Toth BI, et al.
PPARγ-mediated and arachidonic acid-dependent signaling is involved in differentiation and lipid production of human sebocytes.
J Invest Dermatol. 2014; 134(4):910-20 [PubMed] Related Publications
The transcriptional basis of sebocyte differentiation and lipid production is mostly unclear. Peroxisome proliferator-activated receptor gamma (PPARγ), a lipid-activated transcription factor, has been implicated in differentiation and lipid metabolism of various cell types. Here, we show that PPARγ is differentially expressed in normal and pathological human sebocytes and appears to have roles in their differentiation and lipid production. We used laser-microdissected normal and pathological human sebaceous glands (SGs) and SZ95 cells (immortalized sebocyte cell line) analyzed by real-time quantitative PCR and immunohistochemistry. Lipids were analyzed by quantitative fluorimetry- and mass spectrometry-based approaches. We have observed that PPARγ and its target genes, ADRP (adipose differentiation-related protein) and PGAR (PPARγ angiopoietin-related protein), are expressed in sebocytes and show association with their level of differentiation. Also, PPARγ is present in normal and hyperplastic SG, whereas its expression levels are decreased in SG adenoma and SG carcinoma cells, reflecting a maturation-linked expression pattern. Furthermore, in SZ95 sebocytes, naturally occurring lipids, including arachidonic acid and arachidonic acid keto-metabolites (e.g., 5-KETE (5-oxo-6E,8Z,11Z,14Z-eicosatetraenoic acid), 12-KETE (12-oxo-5Z,8Z,10E,14Z-eicosatetraenoic acid)), appear to regulate PPARγ signaling pathways, which in turn modulate phospholipid biosynthesis and induce neutral lipid synthesis. Collectively, our findings highlight the importance of endogenous ligand-activated PPARγ signaling in human sebocyte biology and suggest that PPARγ might be a promising candidate for the clinical management of SG disorders.

Trimarchi T, Ntziachristos P, Aifantis I
A new player SETs in myeloid malignancy.
Nat Genet. 2013; 45(8):846-7 [PubMed] Article available free on PMC after 19/08/2015 Related Publications
Recent studies have identified recurrent mutations in SETBP1, the gene that encodes SET-binding protein 1, in several types of myeloid malignancies, including chronic myeloid and acute myeloid leukemias. The identified mutations frequently target the SKI-homologous domain, although the exact pathogenic mechanisms remain unknown.

Weiß N, Stegemann A, Elsayed MA, et al.
Inhibition of the prohormone convertase subtilisin-kexin isoenzyme-1 induces apoptosis in human melanoma cells.
J Invest Dermatol. 2014; 134(1):168-75 [PubMed] Related Publications
Prohormone convertases (PCs) are endoproteases that process many substrates in addition to hormone precursors. Although overexpression of PCs is linked to carcinogenesis in some solid tumors, the role of subtilisin-kexin isoenzyme-1 (SKI-1) in this context is unknown. We show that SKI-1 is constitutively expressed in human pigment cells with higher SKI activity in seven out of eight melanoma cell lines compared with normal melanocytes. SKI-1 immunoreactivity is also detectable in tumor cells of melanoma metastases. Moreover, tissue samples of the latter display higher SKI-1 mRNA levels and activity than normal skin. From various stimuli tested, 12-O-tetradecanoylphorbol-13-acetate and tunicamycin affected SKI-1 expression. Importantly, SKI-1 inhibition by the cell-permeable enzyme inhibitor decanoyl-RRLL-chloromethylketone (dec-RRLL-CMK) not only suppressed proliferation and metabolic activity of melanoma cells in vitro but also reduced tumor growth of melanoma cells injected intracutaneously into immunodeficient mice. Mechanistic studies revealed that dec-RRLL-CMK induces classical apoptosis of melanoma cells in vitro and affects expression of several SKI-1 target genes including activating transcription factor 6 (ATF6). However, ATF6 gene silencing does not result in apoptosis of melanoma cells, suggesting that dec-RRLL-CMK induces cell death in an ATF6-independent manner. Our findings encourage further studies on SKI-1 as a potential target for melanoma therapy.

Takahashi M, Higuchi M, Makokha GN, et al.
HTLV-1 Tax oncoprotein stimulates ROS production and apoptosis in T cells by interacting with USP10.
Blood. 2013; 122(5):715-25 [PubMed] Related Publications
Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia (ATL), and the viral oncoprotein Tax plays key roles in the immortalization of human T cells, lifelong persistent infection, and leukemogenesis. We herein identify the ubiquitin-specific protease 10 (USP10) as a Tax-interactor in HTLV-1-infected T cells. USP10 is an antistress factor against various environmental stresses, including viral infections and oxidative stress. On exposure to arsenic, an oxidative stress inducer, USP10 is recruited into stress granules (SGs), and USP10-containing SGs reduce reactive oxygen species (ROS) production and inhibit ROS-dependent apoptosis. We found that interaction of Tax with USP10 inhibits arsenic-induced SG formation, stimulates ROS production, and augments ROS-dependent apoptosis in HTLV-1-infected T cells. These findings suggest that USP10 is a host factor that inhibits stress-induced ROS production and apoptosis in HTLV-1-infected T cells; however, its activities are attenuated by Tax. A clinical study showed that combination therapy containing arsenic is effective against some forms of ATL. Therefore, these findings may be relevant to chemotherapy against ATL.

Vojvodic M, Hansford LM, Morozova O, et al.
A phosphoproteomics approach to identify candidate kinase inhibitor pathway targets in lymphoma-like primary cell lines.
Curr Drug Discov Technol. 2013; 10(4):283-304 [PubMed] Related Publications
Mass spectrometry-based technologies are increasingly utilized in drug discovery. Phosphoproteomics in particular has allowed for the efficient surveying of phosphotyrosine signaling pathways involved in various diseases states, most prominently in cancer. We describe a phosphotyrosine-based proteomics screening approach to identify signaling pathways and tyrosine kinase inhibitor targets in highly tumorigenic human lymphoma-like primary cells. We identified several receptor tyrosine kinase pathways and validated SRC family kinases (SFKs) as potential drug targets for targeted selection of small molecule inhibitors. BMS-354825 (dasatinib) and SKI-606 (bosutinib), second and third generation clinical SFK/ABL inhibitors, were found to be potent cytotoxic agents against tumorigenic cells with low toxicity to normal pediatric stem cells. Both SFK inhibitors reduced ERK1/2 and AKT phosphorylation and induced apoptosis. This study supports the adaptation of high-end mass spectrometry techniques for the efficient identification of candidate tyrosine kinases as novel therapeutic targets in primary cancer cell lines.

Chiu TH, Lan KY, Yang MD, et al.
Diallyl sulfide promotes cell-cycle arrest through the p53 expression and triggers induction of apoptosis via caspase- and mitochondria-dependent signaling pathways in human cervical cancer Ca Ski cells.
Nutr Cancer. 2013; 65(3):505-14 [PubMed] Related Publications
Diallyl sulfide (DAS) is a component of garlic (Alliaceae family). Although diallyl polysulfide has been shown to exhibit anticancer activities, no report explored DAS-affected cell death in human cervical cancer cells in vitro. This study investigated DAS affected on cell-cycle regulation and apoptosis in human cervical cancer Ca Ski cells. DAS at 25-100 μM decreased the viability of Ca Ski cells by increasing G0/G1 phase arrest followed by induction of apoptosis in concentration- and time-dependent effects. Flow cytomteric assay indicated that DAS (75 μM) promoted the production of Ca(2+) accumulation and decreased the level of mitochondrial membrane potential in Ca Ski cells. Western blotting showed that 75 μM of DAS-induced G0/G1 phase arrest was mediated through the increased expression of p21, p27, and p53 with a simultaneous decrease in CDK2, CDK6, and CHK2 expression. The characteristics of apoptosis, such as morphological changes and DNA condensation, altered the ratio of Bax/Bcl-2 and sub-G1 phase occurred in Ca Ski cells after exposure to DAS. Furthermore, DAS induced mitochondrial dysfunction, leading to the release of cytochrome c for causing apoptosis in Ca Ski cells. These findings suggest that DAS might be a potential chemotherapeutic agent for the treatment of cervical cancer.

Arany S, Benoit DS, Dewhurst S, Ovitt CE
Nanoparticle-mediated gene silencing confers radioprotection to salivary glands in vivo.
Mol Ther. 2013; 21(6):1182-94 [PubMed] Article available free on PMC after 19/08/2015 Related Publications
Radiation treatment of head and neck cancers causes irreversible damage of the salivary glands (SG). Here, we introduce a preclinical mouse model for small-interfering RNA (siRNA)-based gene silencing to provide protection of SG from radiation-induced apoptosis. Novel, pH-responsive nanoparticles complexed with siRNAs were introduced into mouse submandibular glands (SMG) by retroductal injection to modulate gene expression in vivo. To validate this approach, we first targeted Nkcc1, an ion transporter that is essential for saliva secretion. Nkcc1 siRNA delivery resulted in efficient knockdown, as quantified at the mRNA and the protein levels, and the functional result of Nkcc1 knockdown phenocopied the severe decrease in saliva secretion, characteristic of the systemic Nkcc1 gene knockout. To establish a strategy to prevent apoptotic cell loss due to radiation damage, siRNAs targeting the proapoptotic Pkcδ gene were administered into SMG before ionizing radiation. Knockdown of Pkcδ not only reduced the number of apoptotic cells during the acute phase of radiation damage, but also markedly improved saliva secretion at 3 months in irradiated animals, indicating that this treatment confers protection from hyposalivation. These results demonstrate that nanoparticle delivery of siRNAs targeting a proapoptotic gene is a localized, nonviral, and effective means of conferring radioprotection to the SGs.

Briones-Orta MA, Levy L, Madsen CD, et al.
Arkadia regulates tumor metastasis by modulation of the TGF-β pathway.
Cancer Res. 2013; 73(6):1800-10 [PubMed] Article available free on PMC after 19/08/2015 Related Publications
TGF-β can act as a tumor suppressor at early stages of cancer progression and as a tumor promoter at later stages. The E3 ubiquitin ligase Arkadia (RNF111) is a critical component of the TGF-β signaling pathway, being required for a subset of responses, those mediated by Smad3-Smad4 complexes. It acts by mediating ligand-induced degradation of Ski and SnoN (SKIL), which are 2 potent transcriptional repressors. Here, we investigate the role of Arkadia in cancer using model systems to address both potential tumor-suppressive and tumor-promoting roles. Stable reexpression of Arkadia in lung carcinoma NCI-H460 cells, which we show contain a hemizygous nonsense mutation in the Arkadia/RNF111 gene, efficiently restored TGF-β-induced Smad3-dependent transcription, and substantially decreased the ability of these cells to grow in soft agar in vitro. However, it had no effect on tumor growth in vivo in mouse models. Moreover, loss of Arkadia in cancer cell lines and human tumors is rare, arguing against a prominent tumor-suppressive role. In contrast, we have uncovered a potent tumor-promoting function for Arkadia. Using 3 different cancer cell lines whose tumorigenic properties are driven by TGF-β signaling, we show that loss of Arkadia function, either by overexpression of dominant negative Arkadia or by siRNA-induced knockdown, substantially inhibited lung colonization in tail vein injection experiments in immunodeficient mice. Our findings indicate that Arkadia is not critical for regulating tumor growth per se, but is required for the early stages of cancer cell colonization at the sites of metastasis.

Wang W, Liu C, Wang Y, Cao L
Effects of the downregulation of SnoN expression on HepG2 cell proliferation and apoptosis.
Mol Med Rep. 2013; 7(4):1324-8 [PubMed] Related Publications
Ski‑novel protein (SnoN) is a proto‑oncogene that belongs to the Ski protein family and is involved in regulating processes such as cell proliferation and apoptosis. To investigate the role of SnoN in the proliferation and apoptosis of HepG2 cells, we downregulated its expression by the use of small interfering RNA (siRNA). Three fragments predicted to have RNAi capacity were designed and synthesized as the target siRNAs (siRNA‑A, ‑B and ‑C). Following transfection, inhibition efficiency was detected by reverse transcription PCR (RT‑PCR) and western blot analysis. The siRNA with the optimal inhibition efficiency was used for the cell proliferation and apoptosis analysis. Cell proliferation was analyzed by the Cell Counting Kit‑8 (CCK‑8) and cell apoptosis was investigated by flow cytometry. In our study, all three siRNAs efficiently inhibited SnoN expression, and siRNA‑C demonstrated the optimal inhibition efficiency. We found that following downregulation of SnoN expression, HepG2 cell proliferation was significantly inhibited (P<0.05), while HepG2 cell apoptosis was significantly increased (P<0.05). SnoN‑specific siRNA is capable of effectively inhibiting the expression of SnoN in human HepG2 cells, and the downregulation of SnoN expression induces growth inhibition and apoptosis.

Shinozuka E, Miyashita M, Mizuguchi Y, et al.
SnoN/SKIL modulates proliferation through control of hsa-miR-720 transcription in esophageal cancer cells.
Biochem Biophys Res Commun. 2013; 430(1):101-6 [PubMed] Related Publications
It is now evident that changes in microRNA are involved in cancer progression, but the mechanisms of transcriptional regulation of miRNAs remain unknown. Ski-related novel gene (SnoN/SKIL), a transcription co-factor, acts as a potential key regulator within a complex network of p53 transcriptional repressors. SnoN has pro- and anti-oncogenic functions in the regulation of cell proliferation, senescence, apoptosis, and differentiation. We characterized the roles of SnoN in miRNA transcriptional regulation and its effects on cell proliferation using esophageal squamous cell carcinoma (ESCC) cells. Silencing of SnoN altered a set of miRNA expression profiles in TE-1cells, and the expression levels of miR-720, miR-1274A, and miR-1274B were modulated by SnoN. The expression of these miRNAs resulted in changes to the target protein p63 and a disintegrin and metalloproteinase domain 9 (ADAM9). Furthermore, silencing of SnoN significantly upregulated cell proliferation in TE-1 cells, indicating a potential anti-oncogenic function. These results support our observation that cancer tissues have lower expression levels of SnoN, miR-720, and miR-1274A compared to adjacent normal tissues from ESCC patients. These data demonstrate a novel mechanism of miRNA regulation, leading to changes in cell proliferation.

Phuah NH, In LL, Azmi MN, et al.
Alterations of microRNA expression patterns in human cervical carcinoma cells (Ca Ski) toward 1'S-1'-acetoxychavicol acetate and cisplatin.
Reprod Sci. 2013; 20(5):567-78 [PubMed] Article available free on PMC after 19/08/2015 Related Publications
The aims of this study were to investigate the combined effects of a natural compound 1'S-1'-acetoxychavicol acetate (ACA) with cisplatin (CDDP) on HPV-positive human cervical carcinoma cell lines (Ca Ski-low cisplatin sensitivity and HeLa-high cisplatin sensitivity), and to identify microRNAs (miRNAs) modulated in response toward ACA and/or CDDP. It was revealed that both ACA and CDDP induced dose- and time-dependent cytotoxicity when used as a stand-alone agent, while synergistic effects were observed when used in combination with a combination index (CI) value of 0.74 ± 0.01 and 0.85 ± 0.01 in Ca Ski and HeLa cells, respectively. A total of 25 miRNAs were found to be significantly differentially expressed in response to ACA and/or CDDP. These include hsa-miR-138, hsa-miR-210, and hsa-miR-744 with predicted gene targets involved in signaling pathways regulating apoptosis and cell cycle progression. In conclusion, ACA acts as a chemosensitizer which synergistically potentiates the cytotoxic effect of CDDP in cervical cancer cells. The altered miRNA expression upon administration of ACA and/or CDDP suggests that miRNAs play an important role in anticancer drug responses, which can be manipulated for therapeutic purposes.

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