MSI1; musashi RNA-binding protein 1 (12q24)

Gene Summary

Gene:MSI1; musashi RNA-binding protein 1
Summary:This gene encodes a protein containing two conserved tandem RNA recognition motifs. Similar proteins in other species function as RNA-binding proteins and play central roles in posttranscriptional gene regulation. Expression of this gene has been correlated with the grade of the malignancy and proliferative activity in gliomas and melanomas. A pseudogene for this gene is located on chromosome 11q13. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:RNA-binding protein Musashi homolog 1
Updated:12 December, 2014


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1989-2014)
Graph generated 12 December 2014 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.

Tag cloud generated 12 December, 2014 using data from PubMed, MeSH and CancerIndex

Notable (6)

Scope includes mutations and abnormal protein expression.

Entity Topic PubMed Papers
Bladder CancerMSI1 and Bladder Cancer View Publications1
Stomach CancerMSI1 and Stomach Cancer View Publications2
Colorectal CancerMSI1 and Colorectal Cancer View Publications5
Brain Tumours, ChildhoodMSI1 and Brain Tumours View Publications7
-MSI1 and Glioblastoma View Publications4
Breast CancerMSI1 and Breast Cancer View Publications3

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

Related Links

Latest Publications: MSI1 (cancer-related)

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

Related: Colorectal (Bowel) Cancer Signal Transduction NOTCH3

He L, Zhou X, Qu C, et al.
Musashi2 predicts poor prognosis and invasion in hepatocellular carcinoma by driving epithelial-mesenchymal transition.
J Cell Mol Med. 2014; 18(1):49-58 [PubMed] Free Access to Full Article Related Publications
The high incidence of recurrence and the poor prognosis of hepatocellular carcinoma (HCC) necessitate the discovery of new predictive markers of HCC invasion and prognosis. In this study, we evaluated the expression pattern of two members of a novel oncogene family, Musashi1 (MSI1) and Musashi2 (MSI2) in 40 normal hepatic tissue specimens, 149 HCC specimens and their adjacent non-tumourous tissues. We observed that MSI1 and MSI2 were significantly up-regulated in HCC tissues. High expression levels of MSI1 and MSI2 were detectable in 37.6% (56/149) and 49.0% (73/149) of the HCC specimens, respectively, but were rarely detected in adjacent non-tumourous tissues and were never detected in normal hepatic tissue specimens. Nevertheless, only high expression of MSI2 correlated with poor prognosis. In addition, MSI2 up-regulation correlated with clinicopathological parameters representative of highly invasive HCC. Further study indicated that MSI2 might enhance invasion of HCC by inducing epithelial-mesenchymal transition (EMT). Knockdown of MSI2 significantly decreased the invasion of HCC cells and changed the expression pattern of EMT markers. Moreover, immunohistochemistry assays of 149 HCC tissue specimens further confirmed this correlation. Taken together, the results of our study demonstrated that MSI2 correlates with EMT and has the potential to be a new predictive biomarker of HCC prognosis and invasion to help guide diagnosis and treatment of post-operative HCC patients.

Related: Liver Cancer

Binder ZA, Siu IM, Eberhart CG, et al.
Podocalyxin-like protein is expressed in glioblastoma multiforme stem-like cells and is associated with poor outcome.
PLoS One. 2013; 8(10):e75945 [PubMed] Free Access to Full Article Related Publications
Glioblastoma multiforme (GBM) is the most common primary malignant adult brain tumor and is associated with poor survival. Recently, stem-like cell populations have been identified in numerous malignancies including GBM. To identify genes whose expression is changed with differentiation, we compared transcript profiles from a GBM oncosphere line before and after differentiation. Bioinformatic analysis of the gene expression profiles identified podocalyxin-like protein (PODXL), a protein highly expressed in human embryonic stem cells, as a potential marker of undifferentiated GBM stem-like cells. The loss of PODXL expression upon differentiation of GBM stem-like cell lines was confirmed by quantitative real-time PCR and flow cytometry. Analytical flow cytometry of numerous GBM oncosphere lines demonstrated PODXL expression in all lines examined. Knockdown studies and flow cytometric cell sorting experiments demonstrated that PODXL is involved in GBM stem-like cell proliferation and oncosphere formation. Compared to PODXL-negative cells, PODXL-positive cells had increased expression of the progenitor/stem cell markers Musashi1, SOX2, and BMI1. Finally, PODXL expression directly correlated with increasing glioma grade and was a marker for poor outcome in patients with GBM. In summary, we have demonstrated that PODXL is expressed in GBM stem-like cells and is involved in cell proliferation and oncosphere formation. Moreover, high PODXL expression correlates with increasing glioma grade and decreased overall survival in patients with GBM.

Related: SOX2 gene

Nikpour P, Mowla SJ, Forouzandeh-Moghaddam M, Ziaee SA
The stem cell self-renewal gene, Musashi 1, is highly expressed in tumor and non-tumor samples of human bladder.
Indian J Cancer. 2013 Jul-Sep; 50(3):214-8 [PubMed] Related Publications
CONTEXT: The stem cell model for cancer assumes that a key event in tumorigenesis is the deregulation of genes involved in the regulation of stem cell self-renewal. The Musashi family is an evolutionarily conserved group of neural RNA-binding proteins. In mammals, the family consists of two individual genes, Musashi 1 (MSI1) and MSI2, encoding the Musashi 1 and Musashi 2 proteins. Musashi 1 is involved in the regulation of self-renewal of stem cells. Recently, its over-expression has also been reported in a variety of human tumors.
AIMS: To investigate a potential expression of the stem cell self-renewal gene, Musashi 1, in human bladder cancer, we examined its gene expression in a series of tumor and non-tumor tissue samples of bladder.
MATERIALS AND METHODS: Relative expression of MSI1 was determined by the real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) in 70 surgical samples of bladder.
RESULTS: Using specific primers for MSI1 and TBP (as an internal control) for qRT-PCR technique, we found a relatively high expression level of MSI1 in all examined tumor and non-tumor bladder tissue specimens. However, our data did not show any correlation between the level of gene expression and tumor/non-tumor states of the samples (P>0.05).
CONCLUSIONS: All together, our data demonstrated that Musashi 1 is highly and un-differentially expressed in both examined tumoral and apparently normal bladder tissues.

Related: Transitional Cell Cancer of the Renal Pelvis and Ureter Bladder Cancer Bladder Cancer - Molecular Biology

Emadi-Baygi M, Nikpour P, Mohammad-Hashem F, et al.
MSI2 expression is decreased in grade II of gastric carcinoma.
Pathol Res Pract. 2013; 209(11):689-91 [PubMed] Related Publications
Gastric cancer is the second most frequent cause of cancer death worldwide. In Iran, gastric cancer is the first cause of national cancer-related mortality in men and the second one in women. In mammals, the Musashi family of RNA binding proteins comprises the Musashi1 and Musashi2 proteins, encoded by the MSI1 and MSI2 genes. Mammalian Musashi contributes to the self-renewal of various types of stem cells. Furthermore, there is mounting evidence that stem cells exist in many tissues. Due to this, Msi appears to be associated with tumorigenesis. In the present study, 30 paired gastric tissue samples were examined for MSI2 gene expression by quantitative real-time RT-PCR. Our results demonstrated that the relative expression of the gene did not significantly alter between tumoral and non-tumoral tissues and different tumor types; but there was a statistical difference between the MSI2 gene expression in different tumor grades, of note between grade I and grade II.

Related: Stomach Cancer Gastric Cancer

Sutherland JM, McLaughlin EA, Hime GR, Siddall NA
The Musashi family of RNA binding proteins: master regulators of multiple stem cell populations.
Adv Exp Med Biol. 2013; 786:233-45 [PubMed] Related Publications
In order to maintain their unlimited capacity to divide, stem cells require controlled temporal and spatial protein expression. The Musashi family of RNA-binding proteins have been shown to exhibit this necessary translational control through both repression and activation in order to regulate multiple stem cell populations. This chapter looks in depth at the initial discovery and characterisation of Musashi in the model organism Drosophila, and its subsequent emergence as a master regulator in a number of stem cell populations. Furthermore the unique roles for mammalian Musashi-1 and Musashi-2 in different stem cell types are correlated with the perceived diagnostic power of Musashi expression in specific stem cell derived oncologies. In particular the potential role for Musashi in the identification and treatment of human cancer is considered, with a focus on the role of Musashi-2 in leukaemia. Finally, the manipulation of Musashi expression is proposed as a potential avenue towards the targeted treatment of specific aggressive stem cell cancers.

Related: Leukemia

Nikpour P, Emadi-Baygi M, Mohhamad-Hashem F, et al.
MSI1 overexpression in diffuse type of gastric cancer.
Pathol Res Pract. 2013; 209(1):10-3 [PubMed] Related Publications
Being the third most frequent cause of cancer mortality in the world, gastric cancer is the major cause of cancer-related mortality in Iran. Musashi1 recognizes a motif in the 3'UTR of target mRNAs - involved in cell cycle regulation, proliferation and apoptosis - and represses the translation of the mRNAs. As tissue stem cells exist in many adult tissues other than the CNS, Musashi is considered to be associated with many malignancies. In the current study, we aimed to assess Musashi1 gene expression in human stomach cancer. In total, 30 paired gastric tumoral and adjacent non-tumoral tissue specimens were examined for gene expression by qReal-Time RT-PCR. Our results demonstrated that the expression of the gene did not significantly change between tumor/non-tumor tissues (p value: 16×10(-2)) and different grades (p value: 36×10(-2)). However, there was a statistical difference between the MSI1 gene expression in different tumor types, i.e., intestinal versus diffuse type (p value: 3×10(-2)). All together, further investigations should be done to elucidate the precise molecular mechanisms by which MSI1 contribute to the pathogenesis of gastric cancer.

Related: Stomach Cancer Gastric Cancer

Song X, Zhou C, Zhou S, et al.
The expression patterns of Msi1 related with the glioma grade and the cytoplasmic Msi1 promotes angiogenesis.
Tissue Cell. 2013; 45(1):1-6 [PubMed] Related Publications
To investigate the expression patterns of Msi1 and its relationship with tumour grading and angiogenesis in human glioma. Msi1 expression and the angiogenesis labelled by CD31 were detected by immunohistochemical staining in glioma from Grade I to Grade IV. MVD-CD31 was counted respectively in nuclear and cytoplasmic positive areas of Msi1. There was weak expression of Msi1 in the adjacent normal brain tissue of glioma, and there were less MVD-CD31 than in glioma. Glioma showed strong expression and different patterns of Msi1. From Grade I to Grade IV glioma, the expression pattern of Msi1 was changed from nuclear into cytoplasmic pattern gradually (P<0.05), and the expression patterns of Msi1 were related with the angiogenesis of glioma (P<0.05). It suggested that cytoplasmic Msi1 promoted angiogenesis and nuclear Msi-1 inhibited angiogenesis in glioma (P<0.05). Msi1 has different expression patterns in glioma from Grade I to Grade IV, and the different expression patterns play diverse roles in angiogenesis of glioma. This might explain that from Grade I to IV, glioma showed worse and worse prognosis.

Related: Angiogenesis and Cancer

Vo DT, Subramaniam D, Remke M, et al.
The RNA-binding protein Musashi1 affects medulloblastoma growth via a network of cancer-related genes and is an indicator of poor prognosis.
Am J Pathol. 2012; 181(5):1762-72 [PubMed] Free Access to Full Article Related Publications
Musashi1 (Msi1) is a highly conserved RNA-binding protein that is required during the development of the nervous system. Msi1 has been characterized as a stem cell marker, controlling the balance between self-renewal and differentiation, and has also been implicated in tumorigenesis, being highly expressed in multiple tumor types. We analyzed Msi1 expression in a large cohort of medulloblastoma samples and found that Msi1 is highly expressed in tumor tissue compared with normal cerebellum. Notably, high Msi1 expression levels proved to be a sign of poor prognosis. Msi1 expression was determined to be particularly high in molecular subgroups 3 and 4 of medulloblastoma. We determined that Msi1 is required for tumorigenesis because inhibition of Msi1 expression by small-interfering RNAs reduced the growth of Daoy medulloblastoma cells in xenografts. To characterize the participation of Msi1 in medulloblastoma, we conducted different high-throughput analyses. Ribonucleoprotein immunoprecipitation followed by microarray analysis (RIP-chip) was used to identify mRNA species preferentially associated with Msi1 protein in Daoy cells. We also used cluster analysis to identify genes with similar or opposite expression patterns to Msi1 in our medulloblastoma cohort. A network study identified RAC1, CTGF, SDCBP, SRC, PRL, and SHC1 as major nodes of an Msi1-associated network. Our results suggest that Msi1 functions as a regulator of multiple processes in medulloblastoma formation and could become an important therapeutic target.

Related: Childhood Medulloblastoma / PNET

Kagara N, Huynh KT, Kuo C, et al.
Epigenetic regulation of cancer stem cell genes in triple-negative breast cancer.
Am J Pathol. 2012; 181(1):257-67 [PubMed] Related Publications
Expression of specific breast cancer stem cells (BCSCs) is seen in aggressive tumors, but their regulation is unclear. Epigenetic changes influence gene expression and are implicated in breast cancer progression. We hypothesized that promoter methylation regulates specific BCSC-related genes [CD44, CD133, CD24, MSH1 (alias, Musashi-1), and ALDH1] and that this epigenetic profile can identify aggressive subtypes, such as triple-negative breast cancer (TNBC). Methylation analysis was performed using MassARRAY EpiTYPER sequencing; CpG-rich sites were identified in the promoter regions of BCSC genes, except ALDH1. These sites were screened by treatment with 5-aza-2'-deoxycytidine in four TN and five non-TNBC cell lines. The specific regulatory CpG site demonstrating the most significant inverse correlation between CpG site methylation and mRNA expression was identified for CD44, CD133, and Musashi-1, but not for CD24. Methylation of CD44, CD133, and Musashi-1 was evaluated in 91 American Joint Committee on Cancer stage I to III primary breast cancer tumors, and these sites were significantly hypomethylated in TNBC versus non-TNBC. The IHC staining of primary tumors with the highest and lowest methylation levels revealed the strongest staining in hypomethylated specimens, suggesting that hypomethylation leads to gene activation. We demonstrate that methylation is a significant mechanism regulating CD44, CD133, and Musashi-1, and that gene hypomethylation correlates with TNBC. Assessment of epigenetic changes in BCSC genes may provide a more accurate classification of TNBC and could be developed as potential therapeutic targets.

Related: Breast Cancer

Asuthkar S, Gondi CS, Nalla AK, et al.
Urokinase-type plasminogen activator receptor (uPAR)-mediated regulation of WNT/β-catenin signaling is enhanced in irradiated medulloblastoma cells.
J Biol Chem. 2012; 287(24):20576-89 [PubMed] Free Access to Full Article Related Publications
Urokinase plasminogen activator receptor (uPAR) is known to promote invasion, migration, and metastasis in cancer cells. In this report, we showed that ionizing radiation (IR)-induced uPAR has a role in WNT-β-catenin signaling and mediates induction of cancer stem cell (CSC)-like properties in medulloblastoma cell lines UW228 and D283. We observed that IR induced the expression of uPAR and CSC markers, such as Musashi-1 and CD44, and activated WNT-7a-β-catenin signaling molecules. Overexpression of uPAR alone or with IR treatment led to increased WNT-7a-β-catenin-TCF/LEF-mediated transactivation, thereby promoting cancer stemness. In contrast, treatment with shRNA specific for uPAR (pU) suppressed WNT-7a-β-catenin-TCF/LEF-mediated transactivation both in vitro and in vivo. Quercetin, a potent WNT/β-catenin inhibitor, suppressed uPAR and uPAR-mediated WNT/β-catenin activation, and furthermore, addition of recombinant human WNT-7a protein induced uPAR, indicating the existence of a mutual regulatory relationship between uPAR and WNT/β-catenin signaling. We showed that uPAR was physically associated with the WNT effector molecule β-catenin on the membrane, cytoplasm, and nucleus of IR-treated cells and CSC. Most interestingly, we demonstrated for the first time that localization of uPAR in the nucleus was associated with transcription factors (TF) and their specific response elements. We observed from uPAR-ChIP, TF protein, and protein/DNA array analyses that uPAR associates with activating enhancer-binding protein 2α (AP2a) and mediates β-catenin gene transcription. Moreover, association of uPAR with the β-catenin·TCF/LEF complex and various other TF involved during embryonic development and cancer indicates that uPAR is a potent activator of stemness, and targeting of uPAR in combination with radiation has significant therapeutic implications.

Related: Childhood Medulloblastoma / PNET CTNNB1 gene

Yamamoto T, Kato Y, Hiroi A, et al.
Post-transcriptional regulation of fukutin in an astrocytoma cell line.
Int J Exp Pathol. 2012; 93(1):46-55 [PubMed] Free Access to Full Article Related Publications
Fukutin is the gene responsible for Fukuyama-type congenital muscular dystrophy (FCMD), an autosomal recessive disease associated with central nervous system (CNS) and eye anomalies. Fukutin is involved in basement membrane formation via the glycosylation of α-dystroglycan (α-DG), and hypoglycosylation of α-DG provokes the muscular, CNS and eye lesions of FCMD. Astrocytes play an important role in the pathogenesis of the CNS lesions, but the post-transcriptional regulation of fukutin mRNA has not been elucidated. In this study, we investigated the characteristics of fukutin mRNA using an astrocytoma cell line that expresses fukutin and glycosylated α-DG. The glycosylation of α-DG was considered to be increased by over-expression of fukutin and decreased by knockdown of fukutin. Knockdown of Musashi-1, one of the RNA-binding proteins involved in the regulation of neuronal differentiation, induced a decrease in fukutin mRNA. Immunoprecipitation and ELISA-based RNA-binding assay demonstrated possible binding between fukutin mRNA and Musashi-1 protein. A relationship between fukutin mRNA and vimentin protein was also proposed. In situ hybridization for fukutin mRNA showed a positive cytoplasmic reaction including cytoplasmic processes. From these results, fukutin mRNA is suggested to be a localized mRNA up-regulated by Musashi-1 and to be a component of a mRNA-protein complex which includes Musashi-1 and (presumably) vimentin proteins.

Vo DT, Abdelmohsen K, Martindale JL, et al.
The oncogenic RNA-binding protein Musashi1 is regulated by HuR via mRNA translation and stability in glioblastoma cells.
Mol Cancer Res. 2012; 10(1):143-55 [PubMed] Free Access to Full Article Related Publications
Musashi1 (Msi1) is an evolutionarily conserved RNA-binding protein (RBP) that has profound implications in cellular processes such as stem cell maintenance, nervous system development, and tumorigenesis. Msi1 is highly expressed in many cancers, including glioblastoma, whereas in normal tissues, its expression is restricted to stem cells. Unfortunately, the factors that modulate Msi1 expression and trigger high levels in tumors are largely unknown. The Msi1 mRNA has a long 3' untranslated region (UTR) containing several AU- and U-rich sequences. This type of sequence motif is often targeted by HuR, another important RBP known to be highly expressed in tumor tissue such as glioblastoma and to regulate a variety of cancer-related genes. In this report, we show an interaction between HuR and the Msi1 3'-UTR, resulting in a positive regulation of Msi1 expression. We show that HuR increased MSI1 mRNA stability and promoted its translation. We also present evidence that expression of HuR and Msi1 correlate positively in clinical glioblastoma samples. Finally, we show that inhibition of cell proliferation, increased apoptosis, and changes in cell-cycle profile as a result of silencing HuR are partially rescued when Msi1 is ectopically expressed. In summary, our results suggest that HuR is an important regulator of Msi1 in glioblastoma and that this regulation has important biological consequences during gliomagenesis.

Glazer RI, Vo DT, Penalva LO
Musashi1: an RBP with versatile functions in normal and cancer stem cells.
Front Biosci (Landmark Ed). 2012; 17:54-64 [PubMed] Related Publications
Musashi1 (Msi1) is a highly conserved RNA binding protein that was initially identified in Drosophila by its ability to regulate sensory organ development and asymmetric cell division. Studies in mammalian cells reveal multiple functions for Musashi1 in normal and abnormal processes by mediating different post-transcriptional processes. According to our recent studies, Musashi1 very likely controls hundreds of targets, forming networks that regulate apoptosis, differentiation, proliferation and cell cycle. Musashi1 is a characteristic stem cell marker that regulates the balance between self-renewal and differentiation. Over-expression of Musashi1 has been associated with numerous tumor types and its function is required for tumor growth in breast, colon, medulloblastoma and glioblastoma. Musashi1 has also been implicated in neurogenesis and neurodegenerative diseases, and is emerging as a potential therapeutic target in both regenerative medicine and cancer.

Related: Breast Cancer Signal Transduction

Vo DT, Qiao M, Smith AD, et al.
The oncogenic RNA-binding protein Musashi1 is regulated by tumor suppressor miRNAs.
RNA Biol. 2011 Sep-Oct; 8(5):817-28 [PubMed] Related Publications
Musashi1 (Msi1) is an evolutionarily conserved RNA-binding protein that has been implicated in processes like stem cell fate, nervous system development, and tumorigenesis via its activities as a specific regulator of translation. While Msi1 is barely detected in normal adult tissue, it has been observed to be highly expressed in numerous tumor types (e.g. breast, colon, medulloblastoma, glioblastoma, and et cetera). Unfortunately, the molecular cues that are responsible for Msi1 upregulation in cancer cells are largely unknown. Tumor suppressor microRNAs (miRNAs) are known for targeting genes with oncogenic properties like Msi1 and for being either downregulated or deleted in tumor tissue. We observed that Msi1 long 3'UTR region is potentially targeted by several tumor suppressor miRNAs (miR-34a, -101, -128, -137, and -138). Western blotting of endogenous Msi1 protein as well as luciferase assays confirmed Msi1 regulation by these tumor suppressor miRNAs. Furthermore, we observed when examining different cellular states that these miRNAs and Msi1 have opposite expression profiles. Cell proliferation inhibition induced by the tumor suppressor miRNAs was partially rescued by Msi1 transgenic expression. We conclude that tumor suppressor miRNAs are direct and influential regulators of Msi1, affecting its expression pattern during tumorigenesis of malignant nervous system tumors.

Related: Cancer Prevention and Risk Reduction Signal Transduction

Wang T, Ong CW, Shi J, et al.
Sequential expression of putative stem cell markers in gastric carcinogenesis.
Br J Cancer. 2011; 105(5):658-65 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Gastric carcinogenesis has been well documented in the step-wise histopathological model, known as Correa pathway. Several biomarkers including CD44, Musashi-1 and CD133 have been reported as putative stem cell (PSC) markers.
METHODS: We investigated expression of PSC markers CD44, Musashi-1 and CD133 in relation to gastric carcinogenesis and prognosis and chemoresponse. Immunohistochemistry staining was performed in gastric cancer (GC) clinical specimens representing different steps of the Correa pathway. Gastric cancer samples taken before and after neoadjuvant chemotherapy with docetaxel, cisplatin and capecitabine (DCX) were also evaluated for PSC marker expression.
RESULTS: We showed that the expression of three PSC markers was significantly elevated in GC relative to normal gastric mucosa (P<0.001 for each marker). Precancerous lesions, including intestinal metaplasia and dysplasia, demonstrated increased expression of CD44 and Musashi-1. CD133 was predominantly expressed along the border between intramucosal carcinoma and connective tissue at later stages. High CD44 and CD133 expression showed prognostic value for worse patient survival (P=0.014 and P=0.019, respectively). A small number of tumours with high expression of CD44 and CD133 showed pathological response to DCX-based neoadjuvant chemotherapy.
CONCLUSION: CD44 and Musashi-1 are frequently expressed in both premalignant gastric lesions and invasive GC, whereas CD133 expression is restricted mainly to neoplastic tissues.

Related: Stomach Cancer Gastric Cancer

Ying M, Wang S, Sang Y, et al.
Regulation of glioblastoma stem cells by retinoic acid: role for Notch pathway inhibition.
Oncogene. 2011; 30(31):3454-67 [PubMed] Free Access to Full Article Related Publications
It is necessary to understand mechanisms by which differentiating agents influence tumor-initiating cancer stem cells. Toward this end, we investigated the cellular and molecular responses of glioblastoma stem-like cells (GBM-SCs) to all-trans retinoic acid (RA). GBM-SCs were grown as non-adherent neurospheres in growth factor supplemented serum-free medium. RA treatment rapidly induced morphology changes, induced growth arrest at G1/G0 to S transition, decreased cyclin D1 expression and increased p27 expression. Immunofluorescence and western blot analysis indicated that RA induced the expression of lineage-specific differentiation markers Tuj1 and GFAP and reduced the expression of neural stem cell markers such as CD133, Msi-1, nestin and Sox-2. RA treatment dramatically decreased neurosphere-forming capacity, inhibited the ability of neurospheres to form colonies in soft agar and inhibited their capacity to propagate subcutaneous and intracranial xenografts. Expression microarray analysis identified ∼350 genes that were altered within 48 h of RA treatment. Affected pathways included retinoid signaling and metabolism, cell-cycle regulation, lineage determination, cell adhesion, cell-matrix interaction and cytoskeleton remodeling. Notch signaling was the most prominent of these RA-responsive pathways. Notch pathway downregulation was confirmed based on the downregulation of HES and HEY family members. Constitutive activation of Notch signaling with the Notch intracellular domain rescued GBM neurospheres from the RA-induced differentiation and stem cell depletion. Our findings identify mechanisms by which RA targets GBM-derived stem-like tumor-initiating cells and novel targets applicable to differentiation therapies for glioblastoma.

Related: SOX2 gene

Götte M, Greve B, Kelsch R, et al.
The adult stem cell marker Musashi-1 modulates endometrial carcinoma cell cycle progression and apoptosis via Notch-1 and p21WAF1/CIP1.
Int J Cancer. 2011; 129(8):2042-9 [PubMed] Related Publications
The RNA-binding protein Musashi-1 has been proposed to maintain stem cell function during development and regenerative processes as a modulator of the Notch-1 signaling pathway. Musashi-1 expression is upregulated in endometrial carcinoma, however, its pathogenetic role in this tumor entity is unknown. Here we investigate the functional impact and mode of action of Musashi-1 on endometrial carcinoma cell behaviour in vitro. Aldehyde dehydrogenase-1 activity and side population (SP) measurement by Hoechst dye exclusion revealed that the Ishikawa endometrial carcinoma cell line contains a pool of putative cancer stem cells. Musashi-1 expression is 20.8-fold upregulated in SP+ compared to SP- and equally distributed between ALDH+ and ALDH- cell pools. siRNA-mediated knockdown of Musashi-1 mRNA expression lead to an altered expression of the signaling receptor Notch-1 and its downstream targets, the transcription factor Hes-1 and the cell cycle regulators p21(WAF1/CIP1) and cyclin B1, as determined by Western blotting and quantitative real-time PCR. Flow cytometric and ELISA analyses revealed that Musashi-1-mediated modulation of these factors exerted an antiproliferative effect on the cell cycle, and increased apoptosis in endometrial carcinoma cells. We conclude that Ishikawa cells contain a subpopulation of cells with stem cell-like properties. Musashi-1 modulates endometrial carcinoma cell cycle progression and apoptosis via the stemness-related factors Notch-1, Hes-1 and p21(WAF1/CIP1) , thus emerging as a novel future target for endometrial carcinoma therapy.

Related: Apoptosis CDKN1A Endometrial (Uterus) Cancer Endometrial Cancer NOTCH1 gene

Schiapparelli P, Enguita-Germán M, Balbuena J, et al.
Analysis of stemness gene expression and CD133 abnormal methylation in neuroblastoma cell lines.
Oncol Rep. 2010; 24(5):1355-62 [PubMed] Related Publications
Neuroblastoma is the most common extracranial solid tumor in children, accounting for up to 10% of all childhood malignancies. Cellular heterogeneity is a hallmark of this embryonal cancer, as distinct neural crest lineages can be found within the same tumor sample. The aim of our study was to investigate the presence of a subpopulation of immature cells with features of cancer-like stem cells in 10 neuroblastoma cell lines. RT-PCR and flow cytometry were performed in order to analyze different kinds of 'stemness genes' such as: NESTIN (NES), CD133, SOX-2, BMI1, c-KIT, MELK1, MUSASHI-1 (MSI1), FAS, CD44 and VIMENTIN (VIM). In addition, glial and neuronal markers such as NCAM1, GFAP and B-TUBULIN III (TUBB3) were analyzed. Epigenetic changes within the CD133 (Prominin-1) gene promoter were also analyzed. Neuroblastoma cell lines showed a particular pattern of expression, suggesting the presence of an immature cancer stem cell-like subpopulation. The CD133 protein, commonly used to enrich putative cancer propagating stem cell-like populations in different kinds of solid tumors, presented a half-methylated DNA state in 7 of the 12 neuroblastoma cell lines analyzed. An increase in RNA and protein levels of CD133 was achieved following demethylation by assays using 5-aza-2'-deoxycytidine (5-Aza-dC). Since cancer stem cells are believed to be responsible for tumor metastasis, escape from anticancer therapies and disease relapse, their therapeutic targeting and analysis is crucial in neuroblastoma. Moreover, the regulation of CD133 by epigenetic changes may provide an innovative mechanism of CD133 expression as its regulation still remains unclear.

Related: Neuroblastoma

Wang XY, Penalva LO, Yuan H, et al.
Musashi1 regulates breast tumor cell proliferation and is a prognostic indicator of poor survival.
Mol Cancer. 2010; 9:221 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Musashi1 (Msi1) is a conserved RNA-binding protein that regulates the Notch and Wnt pathways, and serves as a stem cell marker in the breast and other tissues. It is unknown how Msi1 relates to other breast cancer markers, whether it denotes tumor initiating cells (TICs), and how it affects gene expression and tumor cell survival in breast cancer cells.
RESULTS: Msi1 expression was analyzed in 20 breast cancer cell lines and in 140 primary breast tumors by western blotting and immunohistochemistry, respectively. Lentivirus RNA interference was used to reduce Msi1 expression in breast cancer cell lines MCF-7 and T47D grown as spheroid cultures and to assess stem cell gene expression and the growth of these cell lines as xenografts. In normal human breast tissue, Msi1 was expressed in 10.6% of myoepithelum and 1.2% of ductal epithelium in the terminal ductal lobular unit (TDLU), whereas, less than 0.05% of ductal epithelium and myoepithelium in large ducts outside the TDLU expressed Msi1. Msi1 was expressed in 55% of the breast cancer cell lines and correlated with ErbB2 expression in 50% of the cell lines. Msi1 was expressed in 68% of primary tumors and in 100% of lymph node metastases, and correlated with 5 year survival. Msi1 was enriched in CD133+ MCF-7 and T47D cells and in spheroid cultures of these cells, and Msi1 'knockdown' (KD) with a lentivirus-expressed shRNA decreased the number and size of spheroid colonies. Msi1 KD reduced Notch1, c-Myc, ErbB2 and pERK1/2 expression, and increased p21CIP1 expression, which is consistent with known Msi1 target mRNAs. Msi1 KD also reduced the expression of the somatic and embryonic stem cell markers, CD133, Bmi1, Sox2, Nanog and Oct4. Xenografts of MCF-7 and T47D Msi1 KD cells resulted in a marked reduction of tumor growth, reduced Msi1 and Notch1 expression and increased p21CIP1 expression.
CONCLUSION: Msi1 is a negative prognostic indicator of breast cancer patient survival, and is indicative of tumor cells with stem cell-like characteristics. Msi1 KD reduces tumor cell survival and tumor xenograft growth, suggesting that it may represent a novel target for drug discovery.

Related: Breast Cancer NOTCH1 gene

Nikpour P, Baygi ME, Steinhoff C, et al.
The RNA binding protein Musashi1 regulates apoptosis, gene expression and stress granule formation in urothelial carcinoma cells.
J Cell Mol Med. 2011; 15(5):1210-24 [PubMed] Related Publications
The RNA-binding protein Musashi1 (MSI1) is a marker of progenitor cells in the nervous system functioning as a translational repressor. We detected MSI1 mRNA in several bladder carcinoma cell lines, but not in cultured normal uroepithelial cells, whereas the paralogous MSI2 gene was broadly expressed. Knockdown of MSI1 expression by siRNA induced apoptosis and a severe decline in cell numbers in 5637 bladder carcinoma cells. Microarray analysis of gene expression changes after MSI1 knockdown significantly up-regulated 735 genes, but down-regulated only 31. Up-regulated mRNAs contained a highly significantly greater number and density of Musashi binding sites. Therefore, a much larger set of mRNAs may be regulated by Musashi1, which may affect not only their translation, but also their turnover. The study confirmed p21(CIP1) and Numb proteins as targets of Musashi1, suggesting additionally p27(KIP1) in cell-cycle regulation and Jagged-1 in Notch signalling. A significant number of up-regulated genes encoded components of stress granules (SGs), an organelle involved in translational regulation and mRNA turnover, and impacting on apoptosis. Accordingly, heat shock induced SG formation was augmented by Musashi1 down-regulation. Our data show that ectopic MSI1 expression may contribute to tumorigenesis in selected bladder cancers through multiple mechanisms and reveal a previously unrecognized function of Musashi1 in the regulation of SG formation.

Related: Apoptosis Signal Transduction Bladder Cancer Bladder Cancer - Molecular Biology

Huang J, Gao J, Lv X, et al.
Target gene therapy of glioma: overexpression of BAX gene under the control of both tissue-specific promoter and hypoxia-inducible element.
Acta Biochim Biophys Sin (Shanghai). 2010; 42(4):274-80 [PubMed] Related Publications
Glioma-specific transcription of tumor-killing genes has been exploited as a promising gene therapeutic modality in glioma patients. Musashi1 (Msi1) and GFAP gene promoters are both cancer-specific promoters. Optimized HIF-binding site (optHBS) sequence was newly found as efficient as EPO HREs used as enhancer in cancer gene therapy. We constructed 4optHBS-Msi1/GFAP promoters and tested their ability to mediate BAX expression to induce apoptosis in glioma cell lines. Our results demonstrated that 4optHBS-Msi1/GFAP promoters are apparently strong and glioma-selective promoters with potential application in targeted glioma gene therapy, and 4optHBS-Msi1/GFAPBAXa are valuable tools for glioma gene therapy.

Related: Apoptosis

Silva AK, Yi H, Hayes SH, et al.
Lithium chloride regulates the proliferation of stem-like cells in retinoblastoma cell lines: a potential role for the canonical Wnt signaling pathway.
Mol Vis. 2010; 16:36-45 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Cancer stem cells are found in many tumor types and are believed to lead to regrowth of tumor mass due to their chemoresistance and self-renewal capacity. We previously demonstrated small subpopulations of cells in retinoblastoma tissue and cell lines that display cancer stem cell-like activities, including expression of stem cell markers, Hoechst dye exclusion, slow cycling, and self-renewal ability. Identifying factors regulating stem cell proliferation will be important for selectively targeting stem cells and controlling tumor growth. Wingless and Int1 (Wnt) signaling is an essential cellular communication pathway that regulates proliferation and differentiation of non-neoplastic stem/progenitor cells in the retina and other tissues, but its role in cancer stem cells in the retinal tumor retinoblastoma is unknown. In this study, we investigated whether the Wnt pathway activator lithium chloride (LiCl) regulates proliferation of retinoblastoma cancer stem-like cells.
METHODS: The number of stem-like cells in Weri and Y79 retinoblastoma cell line cultures was measured by 5-bromo-2-deoxyuridine (BrdU) pulse-chase, immunohistochemistry, and quantitative polymerase chain reaction (PCR) for stem cell marker genes. The cell lines were sorted into stem-like and non-stem-like populations by fluorescence-activated cell sorting (FACS), using an antibody against the stem cell marker ATP-binding cassette, subfamily G, member 2 (ABCG2). Activated Wnt signaling was measured in the sorted cells by western blotting and immunolocalization of the central mediator beta-catenin.
RESULTS: LiCl increased the number of stem-like cells, measured by BrdU retention and elevated expression of the stem cell marker genes Nanog, octamer transcription factor 3 and 4 (Oct3/4), Musashi 1 (Msi1), and ABCG2. Sorted ABCG2-positive stem-like cells had higher levels of beta-catenin than ABCG2-negative non-stem cells, suggesting elevated canonical Wnt signaling. Furthermore, stem cell marker gene expression increased after small interfering RNA (siRNA) knock-down of the Wnt inhibitor secreted frizzled-related protein 2 (SFRP2).
CONCLUSIONS: These results indicate that the cancer stem-like cell population in retinoblastoma is regulated by canonical Wnt/beta-catenin signaling, which identifies the Wnt pathway as a potential mechanism for the control of stem cell renewal and tumor formation in retinoblastoma tumors in vivo.

Related: Retinoblastoma Signal Transduction

Fan LF, Dong WG, Jiang CQ, et al.
Expression of putative stem cell genes Musashi-1 and beta1-integrin in human colorectal adenomas and adenocarcinomas.
Int J Colorectal Dis. 2010; 25(1):17-23 [PubMed] Related Publications
BACKGROUND AND AIMS: Recent studies revealed that Musashi-1and beta1-integrin were putative stem cell genes. Overexpressions of Musashi-1 and beta1-integrin have been reported in some tumor tissues and cell lines. This study was to detect expressions of the two genes in colorectal adenomas and carcinomas and to analyze the correlation between Musashi-1 and beta1-integrin.
METHODS: Musashi-1 and beta1-integrin immunoreactivity was studied immunohistochemically in tissue microarray-based samples containing 69 colorectal adenocarcinomas, eight normal mucosa, and eight adenomas, and their messenger RNA (mRNA) expression level was detected by RT-PCR in resected specimens including the three types of tissue.
RESULTS: A percentage of 66.7% (46/69) and 59.2% (41/69) of colorectal adenocarcinomas were immunoreactive with Musashi-1 and beta1-integrin, respectively. The expressions of Musashi-1 and beta1-integrin protein were significantly higher in tissue samples of stage III than those of stage I-II (P = 0.0252; P = 0.0018, respectively). beta1-integrin expression was higher in group of adenocarcinomas than that of adenomas (P = 0.0276). Musashi-1 expression was closely correlated with beta1-integrin (rs = 0.631, P = 0.0001). Significant differences of Musashi-1 and beta1-integrin mRNA expression levels were found between the normal colorectal mucosa, adenoma, and adenocarcinoma tissues (P = 0.01; P = 0.03, respectively).
CONCLUSIONS: Musashi-1 and beta1-integrin may be involved in human colorectal tumor carcinogenesis and progression. Our observations also indicate the need for further investigations to test in vivo whether cells with these markers have stem cell properties.

Related: ITGB1 Colorectal (Bowel) Cancer

de Sousa Abreu R, Sanchez-Diaz PC, Vogel C, et al.
Genomic analyses of musashi1 downstream targets show a strong association with cancer-related processes.
J Biol Chem. 2009; 284(18):12125-35 [PubMed] Free Access to Full Article Related Publications
Musashi1 (Msi1) is a highly conserved RNA-binding protein with pivotal functions in stem cell maintenance, nervous system development, and tumorigenesis. Despite its importance, only three direct mRNA targets have been characterized so far: m-numb, CDKN1A, and c-mos. Msi1 has been shown to affect their translation by binding to short elements located in the 3'-untranslated region. To better understand Msi1 functions, we initially performed an RIP-Chip analysis in HEK293T cells; this method consists of isolation of specific RNA-protein complexes followed by identification of the RNA component via microarrays. A group of 64 mRNAs was found to be enriched in the Msi1-associated population compared with controls. These genes belong to two main functional categories pertinent to tumorigenesis: 1) cell cycle, cell proliferation, cell differentiation, and apoptosis and 2) protein modification (including ubiquitination and ubiquitin cycle). To corroborate our findings, we examined the impact of Msi1 expression on both mRNA (transcriptomic) and protein (proteomic) expression levels. Genes whose mRNA levels were affected by Msi1 expression have a Gene Ontology distribution similar to RIP-Chip results, reinforcing Msi1 participation in cancer-related processes. The proteomics study revealed that Msi1 can have either positive or negative effects on gene expression of its direct targets. In summary, our results indicate that Msi1 affects a network of genes and could function as a master regulator during development and tumor formation.

Related: Apoptosis Cancer Prevention and Risk Reduction

Murayama M, Okamoto R, Tsuchiya K, et al.
Musashi-1 suppresses expression of Paneth cell-specific genes in human intestinal epithelial cells.
J Gastroenterol. 2009; 44(3):173-82 [PubMed] Related Publications
BACKGROUND: Musashi-1 (Msi-1) is a RNA-binding protein, known as a putative marker of intestinal stem cells (ISCs). However, little is known about the function of Msi-1 within human intestinal epithelial cells (IECs). Thus, the present study aimed to clarify the role of Msi-1 in differentiation and proliferation of IECs.
METHODS: A human intestinal epithelial cell line stably expressing Msi-1 was established. Proliferation of the established cell lines was measured by bromodeoxyuridine incorporation, whereas differentiation were assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of lineage-specific genes. Activities of the Notch and Wnt pathways were examined either by reporter assays or expression of downstream target genes. The distribution of Msi-1 and PLA2G2A expression in vivo was determined by immunohistochemistry.
RESULTS: Constitutive expression of Msi-1 in IECs had no significant effect on cell proliferation, but suppressed expression of Paneth cell-specific genes, including PLA2G2A. Msi-1 appeared to suppress expression of the PLA2G2A gene at the mRNA level. Analysis of Notch and Wnt pathway activity, however, revealed no significant change upon Msi-1 expression. The expression of Msi-1 and PLA2G2A in vivo was restricted to IECs residing at the lowest part of the human intestinal crypt, but was clearly separated to within basal columnar cells or mature Paneth cells, respectively.
CONCLUSIONS: Msi-1 suppresses expression of Paneth cell-specific genes in IECs, presumably through a pathway independent from Notch or Wnt. These findings suggest Msi-1 is a negative regulator of Paneth cell differentiation, an may contribute to maintain the undifferentiated phenotype of ISCs.

Chua C, Zaiden N, Chong KH, et al.
Characterization of a side population of astrocytoma cells in response to temozolomide.
J Neurosurg. 2008; 109(5):856-66 [PubMed] Related Publications
OBJECT: Cancer progenitor-like cells isolated by Hoechst 33342 dye efflux (termed the "side population" [SP]) have been studied in a variety of cancers, including malignant brain tumors. In this study, the authors investigate the nature of the SP phenotype in 2 glioma cell lines, U87MG and T98G, and their response to temozolomide. The roles of several adenosine triphosphate-binding cassette (ABC) multidrug transporters expressed by SP cells, in particular ABCG2, are also examined.
METHODS: Using fluorescence-activated cell sorting, the cells were separated into SP and non-SP fractions and analyzed for progenitor cell-like properties with immunofluorescence staining, quantitative real-time polymerase chain reaction, and their ability to reform glioma mass in an immune-compromised mouse. The response of the SP cells to temozolomide was investigated at the cellular and molecular levels. Small interfering RNA knockdown was used to examine the specific role of the ABCG2 transporter, and the cells' tumorigenic potential was measured using the soft agar clonogenic assay.
RESULTS: Side population cells are characterized by the presence of progenitor cell-like properties: increased expression of nestin, musashi-1, and ABCG2 were observed. In addition, only SP cells were able to reconstitute cellular heterogeneity; these cells were also more invasive than the non-SP cells, and possessed tumorigenic capacity. Temozolomide treatment increased the number of SP cells, and this corresponded to more progenitor-like cells, concurrent with elevated expression of several ABC transporters.
CONCLUSIONS: Knockdown of ABCG2 transporters did not abrogate the SP cell response to temozolomide. Upregulation of several other ABC drug transporter genes is proposed to account for this chemoresistance.

Related: Dacarbazine ABCG2 Temozolomide

Sanchez-Diaz PC, Burton TL, Burns SC, et al.
Musashi1 modulates cell proliferation genes in the medulloblastoma cell line Daoy.
BMC Cancer. 2008; 8:280 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Musashi1 (Msi1) is an RNA binding protein with a central role during nervous system development and stem cell maintenance. High levels of Msi1 have been reported in several malignancies including brain tumors thereby associating Msi1 and cancer.
METHODS: We used the human medulloblastoma cell line Daoy as model system in this study to knock down the expression of Msi1 and determine the effects upon soft agar growth and neurophere formation. Quantitative RT-PCR was conducted to evaluate the expression of cell proliferation, differentiation and survival genes in Msi1 depleted Daoy cells.
RESULTS: We observed that MSI1 expression was elevated in Daoy cells cultured as neurospheres compared to those grown as monolayer. These data indicated that Msi1 might be involved in regulating proliferation in cancer cells. Here we show that shRNA mediated Msi1 depletion in Daoy cells notably impaired their ability to form colonies in soft agar and to grow as neurospheres in culture. Moreover, differential expression of a group of Notch, Hedgehog and Wnt pathway related genes including MYCN, FOS, NOTCH2, SMO, CDKN1A, CCND2, CCND1, and DKK1, was also found in the Msi1 knockdown, demonstrating that Msi1 modulated the expression of a subset of cell proliferation, differentiation and survival genes in Daoy.
CONCLUSION: Our data suggested that Msi1 may promote cancer cell proliferation and survival as its loss seems to have a detrimental effect in the maintenance of medulloblastoma cancer cells. In this regard, Msi1 might be a positive regulator of tumor progression and a potential target for therapy.

Related: Apoptosis Childhood Medulloblastoma / PNET

Götte M, Wolf M, Staebler A, et al.
Increased expression of the adult stem cell marker Musashi-1 in endometriosis and endometrial carcinoma.
J Pathol. 2008; 215(3):317-29 [PubMed] Related Publications
Adult stem cells are thought to be responsible for the high regenerative capacity of the human endometrium, and have been implicated in the pathology of endometriosis and endometrial carcinoma. The RNA-binding protein Musashi-1 is associated with maintenance and asymmetric cell division of neural and epithelial progenitor cells. We investigated expression and localization of Musashi-1 in endometrial, endometriotic and endometrial carcinoma tissue specimens of 46 patients. qPCR revealed significantly increased Musashi-1 mRNA expression in the endometrium compared to the myometrium. Musashi-1 protein expression presented as nuclear or cytoplasmic immunohistochemical staining of single cells in endometrial glands, and of single cells and cell groups in the endometrial stroma. Immunofluorescence microscopy revealed colocalization of Musashi-1 with its molecular target Notch-1 and telomerase. In proliferative endometrium, the proportion of Musashi-1-positive cells in the basalis layer was significantly increased 1.5-fold in the stroma, and three-fold in endometrial glands compared to the functionalis. The number of Musashi-1 expressing cell groups was significantly increased (four-fold) in proliferative compared to secretory endometrium. Musashi-1 expressing stromal cell and cell group numbers were significantly increased (five-fold) in both endometriotic and endometrial carcinoma tissue compared to secretory endometrium. A weak to moderate, diffuse cytoplasmic glandular staining was observed in 50% of the endometriosis cases and in 75% of the endometrioid carcinomas compared to complete absence in normal endometrial samples. Our results emphasize the role of Musashi-1-expressing endometrial progenitor cells in proliferating endometrium, endometriosis and endometrioid uterine carcinoma, and support the concept of a stem cell origin of endometriosis and endometrial carcinoma.

Related: Endometrial (Uterus) Cancer Endometrial Cancer NOTCH1 gene

Sureban SM, May R, George RJ, et al.
Knockdown of RNA binding protein musashi-1 leads to tumor regression in vivo.
Gastroenterology. 2008; 134(5):1448-58 [PubMed] Related Publications
BACKGROUND & AIMS: In the gut, tumorigenesis is thought to arise from the stem cell population located near the base of intestinal and colonic crypts. The RNA binding protein musashi-1 (Msi-1) is a putative intestinal and progenitor/stem cell marker. Msi-1 expression is increased during rat brain development and in APC(min/+) mice tumors. This study examined a potential role of Msi-1 in tumorigenesis.
METHODS: Msi-1 small interfering RNA (siRNA) was administered as a liposomal preparation to HCT116 colon adenocarcinoma xenografts in athymic nude mice and tumor volume was measured. Cell proliferation was assessed by hexosaminidase and 3-(4,5-dimethylthiazol 2-yl)-2,5-diphenyltetrazolium bromide MTT assays. siRNA-transfected cells were subjected to 12 Gy gamma-irradiation. Apoptosis was assessed by immunoreactive activated caspase-3 and mitosis was assessed by phosphorylated histone H3 staining. The tumor xenografts were stained similarly for phosphorylated histone H3, activated caspase-3, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling, Notch-1, and p21(WAF1). Furthermore, siRNA-transfected cells were subjected to cell-cycle analysis and Western blot analyses for Notch-1 and p21(WAF1).
RESULTS: Knockdown of Msi-1 resulted in tumor growth arrest in xenografts, reduced cancer cell proliferation, and increased apoptosis alone and in combination with radiation injury. siRNA-mediated reduction of Msi-1 lead to mitotic catastrophe in tumor cells. Moreover, there was inhibition of Notch-1 and up-regulation of p21(WAF1) after knockdown of Msi-1.
CONCLUSIONS: Our results show the involvement of Msi-1 in cancer cell proliferation, inhibition of apoptosis, and mitotic catastrophe, suggesting an important potential mechanism for its role in tumorigenesis.

Related: Apoptosis Colorectal (Bowel) Cancer


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