Gene Summary

Gene:SCRIB; scribble planar cell polarity protein
Aliases: CRIB1, SCRB1, SCRIB1, Vartul
Summary:This gene encodes a protein that was identified as being similar to the Drosophila scribble protein. The mammalian protein is involved in tumor suppression pathways. As a scaffold protein involved in cell polarization processes, this protein binds to many other proteins. The encoded protein binds to papillomavirus E6 protein via its PDZ domain and the C-terminus of E6. Two alternatively spliced transcript variants that encode different protein isoforms have been found for this gene. [provided by RefSeq, Nov 2011]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:protein scribble homolog
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
Show (28)

Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 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.

  • Drosophila
  • RAS Genes
  • Cell Proliferation
  • Cancer Gene Expression Regulation
  • MAP Kinase Signaling System
  • Membrane Proteins
  • Papillomavirus Infections
  • Amino Acid Sequence
  • Messenger RNA
  • Liver Cancer
  • Cell Line
  • Virus Attachment
  • Tumor Suppressor Gene
  • HEK293 Cells
  • Carcinogenesis
  • Knockout Mice
  • Neoplasm Metastasis
  • Mutation
  • Apoptosis
  • Zinc Finger E-box-Binding Homeobox 1
  • Breast Cancer
  • Epithelial-Mesenchymal Transition
  • Disease Models, Animal
  • Transcription Factors
  • Cell Movement
  • Young Adult
  • Cervical Cancer
  • Epithelial Cells
  • Disease Progression
  • Biological Models
  • Drosophila melanogaster
  • Cell Polarity
  • Protein-Serine-Threonine Kinases
  • Intracellular Signaling Peptides and Proteins
  • Chromosome 8
  • Neoplasm Invasiveness
  • MicroRNAs
  • Zonula Occludens-1 Protein
  • Neoplastic Cell Transformation
  • Drosophila Proteins
Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

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: SCRIB (cancer-related)

Tabariès S, McNulty A, Ouellet V, et al.
Afadin cooperates with Claudin-2 to promote breast cancer metastasis.
Genes Dev. 2019; 33(3-4):180-193 [PubMed] Free Access to Full Article Related Publications
Claudin-2 promotes breast cancer liver metastasis by enabling seeding and early cancer cell survival. We now demonstrate that the PDZ-binding motif of Claudin-2 is necessary for anchorage-independent growth of cancer cells and is required for liver metastasis. Several PDZ domain-containing proteins were identified that interact with the PDZ-binding motif of Claudin-2 in liver metastatic breast cancer cells, including Afadin, Arhgap21, Pdlim2, Pdlim7, Rims2, Scrib, and ZO-1. We specifically examined the role of Afadin as a potential Claudin-2-interacting partner that promotes breast cancer liver metastasis. Afadin associates with Claudin-2, an interaction that requires the PDZ-binding motif of Claudin-2. Loss of Afadin also impairs the ability of breast cancer cells to form colonies in soft agar and metastasize to the lungs or liver. Immunohistochemical analysis of Claudin-2 and/or Afadin expression in 206 metastatic breast cancer tumors revealed that high levels of both Claudin-2 and Afadin in primary tumors were associated with poor disease-specific survival, relapse-free survival, lung-specific relapse, and liver-specific relapse. Our findings indicate that signaling downstream from a Claudin-2/Afadin complex enables the efficient formation of breast cancer metastases. Moreover, combining Claudin-2 and Afadin as prognostic markers better predicts the potential of breast cancer to metastasize to soft tissues.

Wang X, Dong B, Zhang K, et al.
E-cadherin bridges cell polarity and spindle orientation to ensure prostate epithelial integrity and prevent carcinogenesis in vivo.
PLoS Genet. 2018; 14(8):e1007609 [PubMed] Free Access to Full Article Related Publications
Cell polarity and correct mitotic spindle positioning are essential for the maintenance of a proper prostate epithelial architecture, and disruption of the two biological features occurs at early stages in prostate tumorigenesis. However, whether and how these two epithelial attributes are connected in vivo is largely unknown. We herein report that conditional genetic deletion of E-cadherin, a key component of adherens junctions, in a mouse model results in loss of prostate luminal cell polarity and randomization of spindle orientations. Critically, E-cadherin ablation causes prostatic hyperplasia which progresses to invasive adenocarcinoma. Mechanistically, E-cadherin and the spindle positioning determinant LGN interacts with the PDZ domain of cell polarity protein SCRIB and form a ternary protein complex to bridge cell polarity and cell division orientation. These findings provide a novel mechanism by which E-cadherin acts an anchor to maintain prostate epithelial integrity and to prevent carcinogenesis in vivo.

Saito Y, Desai RR, Muthuswamy SK
Reinterpreting polarity and cancer: The changing landscape from tumor suppression to tumor promotion.
Biochim Biophys Acta Rev Cancer. 2018; 1869(2):103-116 [PubMed] Related Publications
Cell polarity is a fundamental property used to generate asymmetry and structure in all cells. Cancer is associated with loss of cell and tissue structure. While observations made in model system such as Drosophila, identify polarity regulators as tumor suppressors that cause inappropriate cell division, studies in mammalian epithelia do not always support such a causative contribution. Our analysis of published cancer dataset shows that many polarity genes, including PARD6B, SCRIB, PRKCI, DLG1, DLG2, DLG5 and LLGL2, are frequently amplified in multiple cancers raising the possibility that mammalian epithelia may have evolved to use polarity proteins in multiple ways where they may have tumor promoting functions. In this review, we reinterpret the published results and propose a modified perspective for the role of polarity regulators in cancer biology. In addition to the traditional form of cell polarity, which is involved establishment of maintenance of normal cell structure and asymmetry, we propose that some mammalian polarity proteins also regulate subcellular polarity (intracellular asymmetry), which can improve cellular fitness to carry out functions such as proliferation, apoptosis, stress adaptation, stemness and organelle biology. Here, we define subcellular polarity and discuss evidence that supports a role for subcellular polarity in biology.

Wan S, Meyer AS, Weiler SME, et al.
Cytoplasmic localization of the cell polarity factor scribble supports liver tumor formation and tumor cell invasiveness.
Hepatology. 2018; 67(5):1842-1856 [PubMed] Related Publications
The loss of epithelial cell polarity plays an important role in the development and progression of liver cancer. However, the specific molecular mechanisms supporting tumor initiation and progression are poorly understood. In this study, transcriptome data and immunofluorescence stains of tissue samples derived from hepatocellular carcinoma (HCC) patients revealed that overexpression associated with cytoplasmic localization of the basolateral cell polarity complex protein scribble (Scrib) correlated with poor prognosis of HCC patients. In comparison with HCC cells stably expressing wild-type Scrib (Scrib
CONCLUSION: Perturbation of hepatocellular polarity due to overexpression and cytoplasmic enrichment of Scrib supports tumor initiation and HCC cell dissemination through specific molecular mechanisms. Biomarker signatures identified in this study can be used for the identification of HCC patients with higher risk for the development of metastasis. (Hepatology 2018;67:1842-1856).

Banerjee A, Roy JK
Study of bantam miRNA expression in brain tumour resulted due to loss of polarity modules in Drosophila melanogaster.
J Genet. 2017; 96(2):365-369 [PubMed] Related Publications
Disturbance of delicate concordance between stem cell proliferation, specification and differentiation during brain development leads to several neural disorders including tumours. Accumulating evidences have demonstrated involvement of short noncoding microRNAs (miRNAs) in governing several biological as well as pathological processes, including tumourigenesis across various species. Drosophila bantam miRNA, known to regulate critical physiological functions is reported to have elevated expression in ovarian tumour. Here, we provide an update on the expression of bantam miRNA in Drosophila brain tumour background resulting due to loss of well characterized polarity proteins, Brat, Lgl and Scrib. Since, both miRNA TaqMan assay and bantam sensor assay showed elevated expression of bantam in brain tumour background, it clearly reflects presence of an antagonistic relationship between polarity proteins and bantam miRNA indicating of its involvement in tumour progression.

Kapil S, Sharma BK, Patil M, et al.
The cell polarity protein Scrib functions as a tumor suppressor in liver cancer.
Oncotarget. 2017; 8(16):26515-26531 [PubMed] Free Access to Full Article Related Publications
Scrib is a membrane protein that is involved in the maintenance of apical-basal cell polarity of the epithelial tissues. However, Scrib has also been shown to be mislocalized to the cytoplasm in breast and prostate cancer. Here, for the first time, we report that Scrib not only translocates to the cytoplasm but also to the nucleus in hepatocellular carcinoma (HCC) cells, and in mouse and human liver tumor samples. We demonstrate that Scrib overexpression suppresses the growth of HCC cells in vitro, and Scrib deficiency enhances liver tumor growth in vivo. At the molecular level, we have identified the existence of a positive feed-back loop between Yap1 and c-Myc in HCC cells, which Scrib disrupts by simultaneously regulating the MAPK/ERK and Hippo signaling pathways. Overall, Scrib inhibits liver cancer cell proliferation by suppressing the expression of three oncogenes, Yap1, c-Myc and cyclin D1, thereby functioning as a tumor suppressor in liver cancer.

Yoshimatsu Y, Nakahara T, Tanaka K, et al.
Roles of the PDZ-binding motif of HPV 16 E6 protein in oncogenic transformation of human cervical keratinocytes.
Cancer Sci. 2017; 108(7):1303-1309 [PubMed] Free Access to Full Article Related Publications
The high-risk human papillomavirus E6 proteins have been shown to interact with and lead to degradation of PDZ-domain-containing proteins through its carboxy-terminal motif. This PDZ-binding motif plays important roles in transformation of cultured cells and carcinogenesis of E6-transgenic mice. However, its biological effects on the natural host cells have not been elucidated. We have examined its roles in an in vitro carcinogenesis model for cervical cancer, in which E6 and E7 together with activated HRAS (HRAS

Liu J, Li J, Li P, et al.
Loss of DLG5 promotes breast cancer malignancy by inhibiting the Hippo signaling pathway.
Sci Rep. 2017; 7:42125 [PubMed] Free Access to Full Article Related Publications
Discs Large Homolog 5 (DLG5) plays an important role in the maintenance of epithelial cell polarity. Recent research showed that DLG5 is decreased in Yes-associated protein (YAP)-overexpressing cells. However, the exact relationship between DLG5 and YAP is not clear. In this study, we showed that loss of DLG5 promoted breast cancer cell proliferation by inhibiting the Hippo signaling pathway and increasing nuclear YAP expression. Furthermore, depletion of DLG5 induced epithelial-mesenchymal transition (EMT) and disrupted epithelial cell polarity, which was associated with altered expression of Scribble, ZO1, E-cadherin and N-cadherin and their mislocalization. Interestingly, we first reported that loss of DLG5 inhibited the interaction of Mst1 and Lats1 with Scribble, which was crucial for YAP activation and the transcription of TEA domain (TEAD) family members. In summary, loss of DLG5 expression promoted breast cancer malignancy by inactivating the Hippo signaling pathway and increasing nuclear YAP.

Chung J, Aburaya S, Aoki W, Ueda M
Molecular changes in appearance of a cancer cell among normal HEK293T cells.
J Biosci Bioeng. 2017; 123(3):281-286 [PubMed] Related Publications
In very early stages of cancer development, one or a few cells expressing cancer-associated genes appear among a much larger number of surrounding normal cells. To analyze the molecular changes induced by this co-existence, we artificially prepared transformed cells with complete loss of tumor suppressor gene, SCRIB, among normal human embryonic kidney (HEK293T) cells. A cell strain with SCRIB-knockout was successfully constructed by using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9 nuclease system and co-cultured with normal cells. By measuring the time-course changes in cell numbers when SCIRB-knockout cells (cancer model) or cells with normal level of SCRIB expression were respectively co-cultured with wild-type normal HEK293T cells, it was shown that the SCRIB-knockout strain was beneficial for proliferation when mixed together with normal cells. Moreover, as a result of proteome analysis on wild-type cells separated from co-culture with SCRIB-knockout cells, a total of 843 proteins were identified, among which 139 proteins were specific. Among the specifically identified proteins, 22 proteins were annotated to be involved in cytoskeletons including microtubule motor activity-associated proteins. It was implied that molecular changes in cytoskeletons occurred in normal cells when co-cultured with SCRIB knockout cells, but the SCRIB knockout might affect proliferation of the transformed cells with SCRIB knockout by defensive or offensive mechanism of surrounding normal cells.

Metodieva G, Adoki S, Lausen B, Metodiev MV
Decreased Usage of Specific Scrib Exons Defines a More Malignant Phenotype of Breast Cancer With Worsened Survival.
EBioMedicine. 2016; 8:150-158 [PubMed] Free Access to Full Article Related Publications
SCRIB is a polarity regulator known to be abnormally expressed in cancer at the protein level. Here we report that, in breast cancer, an additional and hidden dimension of deregulations exists: an unexpected SCRIB exon usage pattern appears to mark a more malignant tumor phenotype and significantly correlates with survival. Conserved exons encoding the leucine-rich repeats tend to be overexpressed while others are underused. Mechanistic studies revealed that the underused exons encode part of the protein necessary for interaction with Vimentin and Numa1, a protein which is required for proper positioning of the mitotic spindle. Thus, the inclusion/exclusion of specific SCRIB exons is a mechanistic hallmark of breast cancer, which could potentially be exploited to develop more efficient diagnostics and therapies.

Zhou Y, Chang R, Ji W, et al.
Loss of Scribble Promotes Snail Translation through Translocation of HuR and Enhances Cancer Drug Resistance.
J Biol Chem. 2016; 291(1):291-302 [PubMed] Free Access to Full Article Related Publications
Drug resistance of cancer cells to various therapeutic agents and molecular targets is a major problem facing current cancer research. The tumor suppressor gene Scribble encodes a polarity protein that is conserved between Drosophila and mammals; loss of the locus disrupts cell polarity, inhibits apoptosis, and mediates cancer process. However, the role of Scribble in drug resistance remains unknown. We show here that knockdown of Scribble enhances drug resistance by permitting accumulation of Snail, which functions as a transcription factor during the epithelial-mesenchymal transition. Then, loss of Scribble activates the mRNA-binding protein human antigen R (HuR) by facilitating translocation of HuR from the nucleus to the cytoplasm. Furthermore, we demonstrate HuR can recognize AU-rich elements of the Snail-encoding mRNA, thereby regulating Snail translation. Moreover, loss of Scribble-induced HuR translocation mediates the accumulation of Snail via activation of the p38 MAPK pathway. Thus, this work clarifies the role of polarity protein Scribble, which is directly implicated in the regulation of developmental transcription factor Snail, and suggesting a mechanism for Scribble mediating cancer drug resistance.

Pearson HB, McGlinn E, Phesse TJ, et al.
The polarity protein Scrib mediates epidermal development and exerts a tumor suppressive function during skin carcinogenesis.
Mol Cancer. 2015; 14:169 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The establishment and maintenance of polarity is vital for embryonic development and loss of polarity is a frequent characteristic of epithelial cancers, however the underlying molecular mechanisms remain unclear. Here, we identify a novel role for the polarity protein Scrib as a mediator of epidermal permeability barrier acquisition, skeletal morphogenesis, and as a potent tumor suppressor in cutaneous carcinogenesis.
METHODS: To explore the role of Scrib during epidermal development, we compared the permeability of toluidine blue dye in wild-type, Scrib heterozygous and Scrib KO embryonic epidermis at E16.5, E17.5 and E18.5. Mouse embryos were stained with alcian blue and alizarin red for skeletal analysis. To establish whether Scrib plays a tumor suppressive role during skin tumorigenesis and/or progression, we evaluated an autochthonous mouse model of skin carcinogenesis in the context of Scrib loss. We utilised Cre-LoxP technology to conditionally deplete Scrib in adult epidermis, since Scrib KO embryos are neonatal lethal.
RESULTS: We establish that Scrib perturbs keratinocyte maturation during embryonic development, causing impaired epidermal barrier formation, and that Scrib is required for skeletal morphogenesis in mice. Analysis of conditional transgenic mice deficient for Scrib specifically within the epidermis revealed no skin pathologies, indicating that Scrib is dispensable for normal adult epidermal homeostasis. Nevertheless, bi-allelic loss of Scrib significantly enhanced tumor multiplicity and progression in an autochthonous model of epidermal carcinogenesis in vivo, demonstrating Scrib is an epidermal tumor suppressor. Mechanistically, we show that apoptosis is the critical effector of Scrib tumor suppressor activity during skin carcinogenesis and provide new insight into the function of polarity proteins during DNA damage repair.
CONCLUSIONS: For the first time, we provide genetic evidence of a unique link between skin carcinogenesis and loss of the epithelial polarity regulator Scrib, emphasizing that Scrib exerts a wide-spread tumor suppressive function in epithelia.

Hawkins ED, Oliaro J, Ramsbottom KM, et al.
Scribble acts as an oncogene in Eμ-myc-driven lymphoma.
Oncogene. 2016; 35(9):1193-7 [PubMed] Related Publications
Scribble complex proteins maintain apicobasal polarity, regulate cell fate determination and function as tumour suppressors in epithelial tissue. Despite evidence that the function of Scribble is maintained in the lymphocyte lineage, we still understand little about its role as a tumour suppressor in haematological malignancies. Using the Eμ-myc model of Burkitt's lymphoma we investigated the role of Scribble in lymphomagenesis. We found that contrary to its well-documented tumour suppressor role in epithelial tissue, loss of Scribble expression delayed the expansion of peripheral B cells and delayed the onset of Eμ-myc-driven lymphoma. This was despite upregulated ERK phosphorylation levels in Scribble-deficient tumours, which are associated with loss of Scribble expression and the development of more aggressive Burkitt's lymphoma. Interestingly, the developmental stage of lymphoma was unaffected by Scribble expression challenging any role for Scribble in fate determination in the haematopoetic lineage. These data provide evidence for oncogenic properties of Scribble in Myc-driven B-cell lymphomagenesis, reinforcing recent findings that overexpression of a mutant form of Scribble can act as an oncogene in epithelial cells. Our results support the growing appreciation that the tumour regulatory functions of Scribble, and other polarity protein family members, are context dependent.

Seiki T, Nagasaka K, Kranjec C, et al.
HPV-16 impairs the subcellular distribution and levels of expression of protein phosphatase 1γ in cervical malignancy.
BMC Cancer. 2015; 15:230 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The high risk Human Papillomavirus (HPV) E6 oncoproteins play an essential role in the development of cervical malignancy. Important cellular targets of E6 include p53 and the PDZ domain containing substrates such as hScrib and Dlg. We recently showed that hScrib activity was mediated in part through recruitment of protein phosphatase 1γ (PP1γ).
METHODS: Expression patterns of hScrib and PP1γ were assessed by immunohistochemistry of HPV-16 positive cervical intraepithelial neoplasm (CIN), classified as CIN1 (n = 4), CIN2 (n = 8), CIN3 (n = 8), cervical carcinoma tissues (n = 11), and HPV-negative cervical tissues (n = 8), as well as by subfractionation assay of the HPV-16 positive cervical cancer cell lines, CaSki and SiHa. To explore the effects of the HPV-16 oncoproteins, we have performed siRNA knockdown of E6/E7 expression, and monitored the effects on the expression patterns of hScrib and PP1γ.
RESULTS: We show that PP1γ levels in HPV-16 positive tumour cells are reduced in an E6/E7 dependent manner. Residual PP1γ in these cells is found mostly in the cytoplasm as opposed to the nucleus where it is predominantly found in normal cells. We have found a striking concordance with redistribution in the pattern of expression (9/11; 81.8%) and loss of PP1γ expression in HPV-16 positive cervical tumours (2/11; 18.2%). Furthermore, this loss of PP1γ expression and redistribution in the pattern of expression occurs progressively as the lesions develop (8/8; 100%).
CONCLUSION: Together, these results suggest that PP1γ may be a novel target of the HPV-16 oncoproteins and indicate that it might be a potential novel biomarker for HPV-16 induced malignancy.

Andersen DS, Colombani J, Palmerini V, et al.
The Drosophila TNF receptor Grindelwald couples loss of cell polarity and neoplastic growth.
Nature. 2015; 522(7557):482-6 [PubMed] Related Publications
Disruption of epithelial polarity is a key event in the acquisition of neoplastic growth. JNK signalling is known to play an important part in driving the malignant progression of many epithelial tumours, although the link between loss of polarity and JNK signalling remains elusive. In a Drosophila genome-wide genetic screen designed to identify molecules implicated in neoplastic growth, we identified grindelwald (grnd), a gene encoding a transmembrane protein with homology to members of the tumour necrosis factor receptor (TNFR) superfamily. Here we show that Grnd mediates the pro-apoptotic functions of Eiger (Egr), the unique Drosophila TNF, and that overexpression of an active form of Grnd lacking the extracellular domain is sufficient to activate JNK signalling in vivo. Grnd also promotes the invasiveness of Ras(V12)/scrib(-/-) tumours through Egr-dependent Matrix metalloprotease-1 (Mmp1) expression. Grnd localizes to the subapical membrane domain with the cell polarity determinant Crumbs (Crb) and couples Crb-induced loss of polarity with JNK activation and neoplastic growth through physical interaction with Veli (also known as Lin-7). Therefore, Grnd represents the first example of a TNFR that integrates signals from both Egr and apical polarity determinants to induce JNK-dependent cell death or tumour growth.

Wang M, Meng JY, He SF
Xihuang Pill () induces mesenchymal-epithelial transition and inhibits loss of apical-basal polarity in colorectal cancer cell through regulating ZEB1-SCRIB loop.
Chin J Integr Med. 2014; 20(10):751-7 [PubMed] Related Publications
OBJECTIVE: To investigate the antiproliferative and anti-metastasis effect of Xihuang Pill (, XP) on human colorectal cancer cell and to explore the molecular mechanism by which it produces the effects.
METHODS: Highly metastatic human colorectal cancer cell line LoVo was treated with low-, medium-, and highdose XP-containing serum (XP-L, XP-M, XP-H) groups for 48 h, cells intervened with no drug rat serum and PD98059 [extracellular signal-regulated kinase (ERK) inhibitor] as negative and positive controls (NC and PC) groups. Cell proliferation assay was made using cell counting kit-8 (CCK8). The 8 μm pore-size transwell chamber and 4', 6-diamidino-2-phenylindole (DAPI) staining were applied to examine the ability of invasion and migration of the cells. The protein expression of ERK1/2, zinc fifi nger E-box-binding homeobox 1 (ZEB1), Scrib and lethal giant larvae homolog 2 (Lgl2) was detected by Western blotting while the relative mRNA quantity of E-cadherin, N-cadherin, Occludin and junctional adhesion molecule-1 (JAM1) was measured by realtime fluorescent quantitative polymerase chain reaction (RT-qPCR).
RESULTS: XP induced a dose-dependent suppression on the proliferation of LoVo cells (P <0.05 or P<0.01), with the inhibition rates varied from 27.30% to 31.08%. Transwell assay showed that when preprocessed with PD98059 and XP-containing serum, the number of cells that passed the filter decreased significantly compared with that of NC group (P <0.05 or P<0.01). Moreover, XP inhibited the protein expression of ERK1/2 and ZEB1 (P <0.05); and up-regulated the protein expression of Scrib and Lgl2 (P <0.05). The mRNA levels of E-cadherin, Occludin and JAM1 of the XP intervened groups and PC group markedly ascended (P <0.05) while that of N-cadherin showed a descending tendency (P>0.05).
CONCLUSION: XP intervention suppressed the ability of proliferation, invasion and migration of the LoVo cells. Regulating ZEB1-SCRIB Loop so as to recover epithelial phenotype and apical junctional complex might be one of the mechanisms by which XP produces the anti-metastasis effect.

Feigin ME, Akshinthala SD, Araki K, et al.
Mislocalization of the cell polarity protein scribble promotes mammary tumorigenesis and is associated with basal breast cancer.
Cancer Res. 2014; 74(11):3180-94 [PubMed] Free Access to Full Article Related Publications
Scribble (SCRIB) localizes to cell-cell junctions and regulates establishment of epithelial cell polarity. Loss of expression of SCRIB functions as a tumor suppressor in Drosophila and mammals; conversely, overexpression of SCRIB promotes epithelial differentiation in mammals. Here, we report that SCRIB is frequently amplified, mRNA overexpressed, and protein is mislocalized from cell-cell junctions in human breast cancers. High levels of SCRIB mRNA are associated with poor clinical prognosis, identifying an unexpected role for SCRIB in breast cancer. We find that transgenic mice expressing a SCRIB mutant [Pro 305 to Leu (P305L)] that fails to localize to cell-cell junctions, under the control of the mouse mammary tumor virus long terminal repeat promoter, develop multifocal hyperplasia that progresses to highly pleomorphic and poorly differentiated tumors with basal characteristics. SCRIB interacts with phosphatase and tensin homolog (PTEN) and the expression of P305L, but not wild-type SCRIB, promotes an increase in PTEN levels in the cytosol. Overexpression of P305L, but not wild-type SCRIB, activates the Akt/mTOR/S6K signaling pathway. Human breast tumors overexpressing SCRIB have high levels of S6K but do not harbor mutations in PTEN or PIK3CA, identifying SCRIB amplification as a mechanism of activating PI3K signaling in tumors without mutations in PIK3CA or PTEN. Thus, we demonstrate that high levels of mislocalized SCRIB functions as a neomorph to promote mammary tumorigenesis by affecting subcellular localization of PTEN and activating an Akt/mTOR/S6kinase signaling pathway.

Savi F, Forno I, Faversani A, et al.
miR-296/Scribble axis is deregulated in human breast cancer and miR-296 restoration reduces tumour growth in vivo.
Clin Sci (Lond). 2014; 127(4):233-42 [PubMed] Related Publications
miR-296-5p is a central regulator of signalling pathways affecting development, stem cell differentiation and cancer. We hypothesized that miR-296-5p is involved in breast cancer onset and progression possibly through regulation of its target SCRIB (Scribble), a polarity protein recently implicated in the acquisition of cancer stem cell traits and in cell motility. We found that miR-296-5p levels were consistently reduced in human breast cancer tissues compared with non-neoplastic mammary parenchyma, and low expression of this miRNA predicted shorter disease-free survival independently of classic clinicopathological parameters. Further, reduced miR-296-5p levels were significantly correlated with an earlier spread of cancer in the overall series and with distant metastases in the subset. In contrast with its regulator, SCRIB was overexpressed and mislocalized in primary breast cancers or locoregional or distant metastatic lesions compared with normal parenchyma. Notably, SCRIB mislocalization was associated with overall survival, metastatic spread and organ tropism in patients with breast cancer. Finally, direct injection of a precursor miR-296-5p into tumours of a breast cancer xenograft model significantly decreased tumour growth. Our results show that the miR-296-5p/SCRIB axis plays a role in breast carcinogenesis and an miR-296-5p-based therapeutic approach hampers breast cancer tumour growth in vivo. Modulation of miR-296-5p may represent a new therapeutic option for patients with breast cancer.

Khursheed M, Bashyam MD
Apico-basal polarity complex and cancer.
J Biosci. 2014; 39(1):145-55 [PubMed] Related Publications
Apico-basal polarity is a cardinal molecular feature of adult eukaryotic epithelial cells and appears to be involved in several key cellular processes including polarized cell migration and maintenance of tissue architecture. Epithelial cell polarity is maintained by three well-conserved polarity complexes, namely, PAR, Crumbs and SCRIB. The location and interaction between the components of these complexes defines distinct structural domains of epithelial cells. Establishment and maintenance of apico-basal polarity is regulated through various conserved cell signalling pathways including TGF beta, Integrin and WNT signalling. Loss of cell polarity is a hallmark for carcinoma, and its underlying molecular mechanism is beginning to emerge from studies on model organisms and cancer cell lines. Moreover, deregulated expression of apico-basal polarity complex components has been reported in human tumours. In this review, we provide an overview of the apico-basal polarity complexes and their regulation, their role in cell migration, and finally their involvement in carcinogenesis.

Elsum IA, Yates LL, Pearson HB, et al.
Scrib heterozygosity predisposes to lung cancer and cooperates with KRas hyperactivation to accelerate lung cancer progression in vivo.
Oncogene. 2014; 33(48):5523-33 [PubMed] Related Publications
Lung cancer is the leading cause of cancer deaths worldwide with non small-cell lung cancer (NSCLC) accounting for 80% of all lung cancers. Although activating mutations in genes of the RAS-MAPK pathway occur in up to 30% of all NSCLC, the cooperating genetic lesions that are required for lung cancer initiation and progression remain poorly understood. Here we identify a role for the cell polarity regulator Scribble (Scrib) in NSCLC. A survey of genomic databases reveals deregulation of SCRIB in human lung cancer and we show that Scrib(+/-) mutant mice develop lung cancer by 540 days with a penetrance of 43%. To model NSCLC development in vivo, we used the extensively characterized LSL-KRas(G12D) murine model of NSCLC. We show that loss of Scrib and activated oncogenic KRas cooperate in vivo, resulting in more aggressive lung tumors, likely due to a synergistic elevation in RAS-MAPK signaling. Finally, we provide data consistent with immune infiltration having an important role in the acceleration of tumorigenesis in KRas(G12D) lung tumors following Scrib loss.

Tenedini E, Bernardis I, Artusi V, et al.
Targeted cancer exome sequencing reveals recurrent mutations in myeloproliferative neoplasms.
Leukemia. 2014; 28(5):1052-9 [PubMed] Free Access to Full Article Related Publications
With the intent of dissecting the molecular complexity of Philadelphia-negative myeloproliferative neoplasms (MPN), we designed a target enrichment panel to explore, using next-generation sequencing (NGS), the mutational status of an extensive list of 2000 cancer-associated genes and microRNAs. The genomic DNA of granulocytes and in vitro-expanded CD3+T-lymphocytes, as a germline control, was target-enriched and sequenced in a learning cohort of 20 MPN patients using Roche 454 technology. We identified 141 genuine somatic mutations, most of which were not previously described. To test the frequency of the identified variants, a larger validation cohort of 189 MPN patients was additionally screened for these mutations using Ion Torrent AmpliSeq NGS. Excluding the genes already described in MPN, for 8 genes (SCRIB, MIR662, BARD1, TCF12, FAT4, DAP3, POLG and NRAS), we demonstrated a mutation frequency between 3 and 8%. We also found that mutations at codon 12 of NRAS (NRASG12V and NRASG12D) were significantly associated, for primary myelofibrosis (PMF), with highest dynamic international prognostic scoring system (DIPSS)-plus score categories. This association was then confirmed in 66 additional PMF patients composing a final dataset of 168 PMF showing a NRAS mutation frequency of 4.7%, which was associated with a worse outcome, as defined by the DIPSS plus score.

Turkel N, Sahota VK, Bolden JE, et al.
The BTB-zinc finger transcription factor abrupt acts as an epithelial oncogene in Drosophila melanogaster through maintaining a progenitor-like cell state.
PLoS Genet. 2013; 9(7):e1003627 [PubMed] Free Access to Full Article Related Publications
The capacity of tumour cells to maintain continual overgrowth potential has been linked to the commandeering of normal self-renewal pathways. Using an epithelial cancer model in Drosophila melanogaster, we carried out an overexpression screen for oncogenes capable of cooperating with the loss of the epithelial apico-basal cell polarity regulator, scribbled (scrib), and identified the cell fate regulator, Abrupt, a BTB-zinc finger protein. Abrupt overexpression alone is insufficient to transform cells, but in cooperation with scrib loss of function, Abrupt promotes the formation of massive tumours in the eye/antennal disc. The steroid hormone receptor coactivator, Taiman (a homologue of SRC3/AIB1), is known to associate with Abrupt, and Taiman overexpression also drives tumour formation in cooperation with the loss of Scrib. Expression arrays and ChIP-Seq indicates that Abrupt overexpression represses a large number of genes, including steroid hormone-response genes and multiple cell fate regulators, thereby maintaining cells within an epithelial progenitor-like state. The progenitor-like state is characterised by the failure to express the conserved Eyes absent/Dachshund regulatory complex in the eye disc, and in the antennal disc by the failure to express cell fate regulators that define the temporal elaboration of the appendage along the proximo-distal axis downstream of Distalless. Loss of scrib promotes cooperation with Abrupt through impaired Hippo signalling, which is required and sufficient for cooperative overgrowth with Abrupt, and JNK (Jun kinase) signalling, which is required for tumour cell migration/invasion but not overgrowth. These results thus identify a novel cooperating oncogene, identify mammalian family members of which are also known oncogenes, and demonstrate that epithelial tumours in Drosophila can be characterised by the maintenance of a progenitor-like state.

Metodieva G, Nogueira-de-Souza NC, Greenwood C, et al.
CD74-dependent deregulation of the tumor suppressor scribble in human epithelial and breast cancer cells.
Neoplasia. 2013; 15(6):660-8 [PubMed] Free Access to Full Article Related Publications
The γ subunit of the major histocompatibility complex (MHC) class II complex, CD74, is overexpressed in a significant proportion of metastatic breast tumors, but the mechanistic foundation and biologic significance of this phenomenon are not fully understood. Here, we show that when CD74 is overexpressed in human cancer and noncancerous epithelial cells, it interacts and interferes with the function of Scribble, a product of a well-known tumor suppressor gene. Furthermore, using epithelial cell lines expressing CD74 under the control of tetracycline-inducible promoter and quantitative high-resolution mass spectrometry, we demonstrate that, as a result of CD74 overexpression, the phosphorylation pattern of the C-terminal part of Scribble undergoes specific changes. This is accompanied with a translocation of the protein from the sites of cell-to-cell contacts at the plasma membrane to the cytoplasm, which is likely to effectively enhance the motility and invasiveness of the cancer cells.

Nagasaka K, Seiki T, Yamashita A, et al.
A novel interaction between hScrib and PP1γ downregulates ERK signaling and suppresses oncogene-induced cell transformation.
PLoS One. 2013; 8(1):e53752 [PubMed] Free Access to Full Article Related Publications
Previous studies have shown that the cell polarity regulator hScrib interacts with, and consequently controls, the ERK signaling pathway. This interaction occurs through two well-conserved Kinase Interacting Motifs, which allow hScrib to bind ERK1 directly, resulting in a reduction in the levels of phospho-ERK. This suggests that hScrib might recruit a phosphatase to regulate this signaling pathway. Using a proteomic approach we now show that Protein Phosphatase 1γ (PP1γ) is a major interacting partner of hScrib. This interaction is direct and occurs through a conserved PP1γ interaction motif on the hScrib protein, and this interaction appears to be required for hScrib's ability to downregulate ERK phosphorylation. In addition, hScrib also controls the pattern of PP1γ localization, where loss of hScrib enhances the nuclear translocation of PP1γ. Furthermore, we also show that the ability of hScrib to interact with PP1γ is important for the ability of hScrib to suppress oncogene-induced transformation of primary rodent cells. Taken together, these results demonstrate that hScrib acts as a scaffold to integrate the control of the PP1γ and ERK signaling pathways and explains how disruption of hScrib localisation can contribute towards the development of human malignancy.

Anastas JN, Biechele TL, Robitaille M, et al.
A protein complex of SCRIB, NOS1AP and VANGL1 regulates cell polarity and migration, and is associated with breast cancer progression.
Oncogene. 2012; 31(32):3696-708 [PubMed] Free Access to Full Article Related Publications
By analyzing public data sets of gene expression in human breast cancers we observed that increased levels of transcripts encoding the planar cell polarity (PCP) proteins SCRIB and VANGL1 correlate with increased risk of patient relapse. Experimentally, we found that reducing expression of SCRIB by short-hairpin RNAs (shRNAs) reduces the growth of human breast cancer cells in xenograft assays. To investigate SCRIB-associated proteins that might participate in the responses of breast cancer cells to altered levels of SCRIB, we used mass spectrometry and confocal microscopy. These studies reveal that SCRIB is present in at least two unique protein complexes: (1) a complex of SCRIB, ARHGEF, GIT and PAK (p21-activated kinase), and (2) a complex of SCRIB, NOS1AP and VANGL. Focusing on NOS1AP, we observed that NOS1AP colocalizes with both SCRIB and VANGL1 along cellular protrusions in metastatic breast cancer cells, but does not colocalize with either SCRIB or VANGL1 at cell junctions in normal breast cells. We investigated the effects of shRNA-mediated knockdown of NOS1AP and SCRIB in vitro, and found that reducing NOS1AP and SCRIB slows breast cancer cell migration and prevents the establishment of leading-trailing polarity. We also find that reduction of NOS1AP enhances anchorage-independent growth. Collectively these data point to the relevance of NOS1AP and SCRIB protein complexes in breast cancer.

Enomoto M, Igaki T
Deciphering tumor-suppressor signaling in flies: genetic link between Scribble/Dlg/Lgl and the Hippo pathways.
J Genet Genomics. 2011; 38(10):461-70 [PubMed] Related Publications
Loss of apico-basal polarity is one of the crucial factors that drives epithelial tumor progression. scribble/discs large/lethal giant larvae (scrib/dlg/lgl), a group of apico-basal polarity genes, were initially identified as members of "neoplastic" tumor-suppressors in flies. The components of the Hippo signaling pathway, which is crucial for organ size control and cancer development, were also identified through Drosophila genetic screens as members of "hyperplastic" tumor-suppressors. Accumulating evidence in recent studies implies that these two tumor-suppressor signaling pathways are not mutually exclusive but rather cooperatively act to give rise to highly malignant tumors. The interaction of these tumor-suppressor pathways could include deregulations of actin cytoskeleton, cell-cell contact, and apical-domain size of the epithelial cell.

Pearson HB, Perez-Mancera PA, Dow LE, et al.
SCRIB expression is deregulated in human prostate cancer, and its deficiency in mice promotes prostate neoplasia.
J Clin Invest. 2011; 121(11):4257-67 [PubMed] Free Access to Full Article Related Publications
Loss of cellular polarity is a hallmark of epithelial cancers, raising the possibility that regulators of polarity have a role in suppressing tumorigenesis. The Scribble complex is one of at least three interacting protein complexes that have a critical role in establishing and maintaining epithelial polarity. In human colorectal, breast, and endometrial cancers, expression of the Scribble complex member SCRIB is often mislocalized and deregulated. Here, we report that Scrib is indispensable for prostate homeostasis in mice. Scrib heterozygosity initiated prostate hyperplasia, while targeted biallelic Scrib loss predisposed mice to prostate intraepithelial neoplasia. Mechanistically, Scrib was shown to negatively regulate the MAPK cascade to suppress tumorigenesis. Further analysis revealed that prostate-specific loss of Scrib in mice combined with expression of an oncogenic Kras mutation promoted the progression of prostate cancer that recapitulated the human disease. The clinical significance of the work in mice was highlighted by our observation that SCRIB deregulation strongly correlated with poor survival in human prostate cancer. These data suggest that the polarity network could provide a new avenue for therapeutic intervention.

Tervonen TA, Partanen JI, Saarikoski ST, et al.
Faulty epithelial polarity genes and cancer.
Adv Cancer Res. 2011; 111:97-161 [PubMed] Related Publications
Epithelial architecture is formed in tissues and organs when groups of epithelial cells are organized into polarized structures. The epithelial function and integrity as well as signaling across the epithelial layer is orchestrated by apical junctional complexes (AJCs), which are landmarks for PAR/CRUMBS and lateral SCRIB polarity modules and by dynamic interactions of the cells with underlying basement membrane (BM). These highly organized epithelial architectures are demolished in cancer. In all advanced epithelial cancers, malignant cells have lost polarity and connections to the basement membrane and they have become proliferative, motile, and invasive. Clearly, loss of epithelial integrity associates with tumor progression but does it contribute to tumor development? Evidence from studies in Drosophila and recently also in vertebrate models have suggested that even the oncogene-driven enforced cell proliferation can be conditional, dependant on the influence of cell-cell or cell-microenvironment contacts. Therefore, loss of epithelial integrity may not only be an obligate consequence of unscheduled proliferation of malignant cells but instead, malignant epithelial cells may need to acquire capacity to break free from the constraints of integrity to freely and autonomously proliferate. We discuss how epithelial polarity complexes form and regulate epithelial integrity, highlighting the roles of enzymes Rho GTPases, aPKCs, PI3K, and type II transmembrane serine proteases (TTSPs). We also discuss relevance of these pathways to cancer in light of genetic alterations found in human cancers and review molecular pathways and potential pharmacological strategies to revert or selectively eradicate disorganized tumor epithelium.

Vaira V, Faversani A, Dohi T, et al.
miR-296 regulation of a cell polarity-cell plasticity module controls tumor progression.
Oncogene. 2012; 31(1):27-38 [PubMed] Free Access to Full Article Related Publications
The expression of small, non-coding RNA or microRNAs (miR), is frequently deregulated in human cancer, but how these pathways affect disease progression is still largely elusive. Here, we report on a miR, miR-296, which is progressively lost during tumor progression and correlates with metastatic disease in colorectal, breast, lung, gastric, parathyroid, liver and bile ducts cancers. Functionally, miR-296 controls a global cell motility gene signature in epithelial cells by transcriptionally repressing the cell polarity-cell plasticity module, Scribble (Scrib). In turn, loss of miR-296 causes aberrantly increased and mislocalized Scrib in human tumors, resulting in exaggerated random cell migration and tumor cell invasiveness. Re-expression of miR-296 in MDA-MB231 cells inhibits tumor growth in vivo. Finally, miR-296 or Scrib levels predict tumor relapse in hepatocellular carcinoma patients. These data identify miR-296 as a global repressor of tumorigenicity and uncover a previously unexplored exploitation of Scrib in tumor progression in humans.

Vaira V, Faversani A, Dohi T, et al.
Aberrant overexpression of the cell polarity module scribble in human cancer.
Am J Pathol. 2011; 178(6):2478-83 [PubMed] Free Access to Full Article Related Publications
Human Scribble (Scrib) is an evolutionary-conserved cell polarity protein, but its potential role in human cancer is controversial. Herein, we show that Scrib is nearly universally overexpressed in cultured tumor cell lines and genetically disparate cancer patient series compared with matched normal tissues in vivo. Instead of a membrane association seen in normal epithelia, tumor-associated Scrib is mislocalized and found predominantly in the cytosol. Small-interfering RNA silencing of Scrib in model lung adenocarcinoma A549 cells inhibited cell migration in wound-healing assays, suppressed tumor cell invasion across Matrigel-coated inserts, and down-regulated the expression of cell motility markers and mediators of epithelial-mesenchymal transition. These data uncover a previously unrecognized exploitation of Scrib for aberrant tumor cell motility and invasion, thus potentially contributing to disease progression in humans.

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