Expression Of Musashi-1 Research Articles

Musashi1 regulates survival of hepatoma cell lines by activation of Wnt signalling pathway

Musashi1 (MSI1) belongs to the RNA-binding protein (RBP) family, with functions as translational activator or suppressor of specifically bound mRNA. However, its function in hepatocellular carcinoma (HCC) has been deeply unexplored. Here, we investigated the role of MSI1 for proliferation and tumourigenesis in HCC. The expression of MSI1 in HCC tissues was examined by immunohistochemistry and western blotting. The effects of MSI1 overexpression and silencing on cell proliferation, cell viability, tumoursphere and tumour formation of HCC were explored. In this study, we initially reported that MSI1 was upregulated in HCC. Overexpression of MSI1 in HepG2 cell lines resulted in significantly promoted cell growth, tumour formation and cell cycle progression. Consistently, knockdown of MSI1 in Huh7 cell lines remarkably inhibited cell growth and tumour formation, and caused cell cycle arrest at the G1/S transition. Dual-luciferase assays indicated that MSI1 activated Wnt signal pathway, and APC and DKK1 were direct targets of MSI1. Taken together, these findings indicate that an oncogenic role of MSI1 in HCC may be through modulation of cell growth and cell cycle by activating Wnt pathway via direct downregulation of APC and DKK1.

Musashi-1 expression and clinicopathological significance in young gastric cancer patients: A matched case-control study

Musashi-1 (Msi-1) is proposed to be a marker of progenitor cells in the human gastric mucosa. We examined Msi-1 expression and localization in surgical specimens of gastric cancer in young patients using immunohistochemistry and tested associations of Msi-1 expression with clinicopathological features. Patients (n=611) with gastric cancer who underwent radical gastrectomy were included in the present study. To minimize confounding effects, we matched 26 gastric cancer patients 30 years of age or younger (age ≤30) with 26 patients 60 years of age or older (age ≥60). The groups were matched by gender, tumor histological type and tumor stage. Gastric cancer in the younger patients was significantly associated with female gender and with diffuse histological type, compared with 585 gastric cancer patients older than 31 years. Msi-1 expression was more frequently upregulated in gastric cancer in young patients than in patients older than 60 years. Msi-1 expression was significantly associated with diffuse histological type, depth of tumor invasion, lymph node metastasis and tumor stage in the 26 young patients with gastric cancer. Univariate Kaplan-Meier survival analysis identified Msi-1 expression as a significantly negative factor in the survival of young gastric cancer patients. However, Msi-1 expression was not significantly associated with survival in the 26 matched older patients. According to mucin phenotype, the gastric foveolar type predominated in Msi-1-positive gastric cancers. Our principal findings included a significantly higher level of Msi-1 expression in younger gastric cancer patients compared to older ones, and a probable association of tumor Msi-1 expression in young gastric cancer patients with more aggressive tumor type.

Amyloid β-Peptide 1–42 Modulates the Proliferation of Mouse Neural Stem Cells: Upregulation of Fucosyltransferase IX and Notch Signaling

Amyloid β-peptides (Aβs) aggregate to form amyloid plaques, also known as senile plaques, which are a major pathological hallmark of Alzheimer's disease (AD). Aβs are reported to possess proliferation effects on neural stem cells (NSCs); however, this effect remains controversial. Thus, clarification of their physiological function is an important topic. We have systematically evaluated the effects of several putative bioactive Aβs (Aβ1-40, Aβ1-42, and Aβ25-35) on NSC proliferation. Treatment of NSCs with Aβ1-42 significantly increased the number of those cells (149 ± 10 %). This was not observed with Aβ1-40 which did not have any effects on the proliferative property of NSC. Aβ25-35, on the other hand, exhibited inhibitory effects on cellular proliferation. Since cell surface glycoconjugates, such as glycolipids, glycoproteins, and proteoglycans, are known to be important for maintaining cell fate determination, including cellular proliferation, in NSCs and they undergo dramatic changes during differentiation, we examined the effect of Aβs on a number of key glycoconjugate metabolizing enzymes. Significantly, we found for the first time that Aβ1-42 altered the expression of several key glycosyltransferases and glycosidases, including fucosyltransferase IX (FUT9), sialyltransferase III (ST-III), glucosylceramide ceramidase (GLCC), and mitochondrial sialidase (Neu4). FUT9 is a key enzyme for the synthesis of the Lewis X carbohydrate epitope, which is known to be expressed in stem cells. Aβ1-42 also stimulated the Notch1 intracellular domain (NICD) by upregulation of the expression of Musashi-1 and the paired box protein, Pax6. Thus, Aβ1-42 upregulates NSC proliferation by modulating the expression of several glycogenes involved in Notch signaling.

11 - Effects of Musashi-1 Expression in Response to Ionizing Radiation and its Association with Radioresistance

11 - Effects of Musashi-1 Expression in Response to Ionizing Radiation and its Association with Radioresistance

Brief report: Musashi1-eGFP mice, a new tool for differential isolation of the intestinal stem cell populations

The intestinal epithelium self-renews rapidly and continuously throughout life, due to the presence of crypt stem cells. Two pools of these cells have been identified in the small intestine, which differ in position ("+4" or the bottom of the crypts), expression of specific markers (Bmi1/mTert or Lgr5/Ascl2), and cell cycle characteristics. Interestingly, the RNA-binding protein Musashi1 is expressed in both populations and therefore a potential marker for both stem cell types. In order to locate, isolate, and study Musashi1-expressing cells within the intestinal epithelium, we generated transgenic mice expressing GFP fluorescent protein under the control of a 7-kb Msi1 promoter. The expression pattern of GFP in the intestinal crypts of both small and large intestines completely overlapped that of Musashi1, validating our model. By using fluorescence-activated cell sorting, cellular, and molecular analyses, we showed that GFP-positive Msi1-expressing cells are divided into two major pools corresponding to the Lgr5- and mTert-expressing stem cells. Interestingly, monitoring the cell cycle activity of the two sorted populations reveals that they are both actively cycling, although differences in cell cycle length were confirmed. Altogether, our new reporter mouse model based upon Musashi1 expression is a useful tool to isolate and study stem cells of the intestinal epithelium. Moreover, these mice uniquely enable the concomitant study of two pools of intestinal stem cells within the same animal model.

Expression of LGR-5, MSI-1 and DCAMKL-1, putative stem cell markers, in the early phases of 1,2-dimethylhydrazine-induced rat colon carcinogenesis: correlation with nuclear β-catenin

BackgroundColon cancer stem cells may drive carcinogenesis and account for chemotherapeutic failure. Although many markers for these cells have been proposed, there is no complete agreement regarding them, nor has their presence in the early phases of carcinogenesis been characterized in depth.MethodsThe expression of the putative markers LGR-5 (leucine-rich-repeat-containing G-protein-coupled receptor 5), MSI-1 (Musashi-1) and DCAMKL-1 (doublecortin and calcium/calmodulin-dependent protein kinase-like-1) was studied in normal colon mucosa (NM), in the precancerous lesions Mucin Depleted Foci (MDF) and in macroscopic tumours (adenomas) of 1,2-dimethylhydrazine-treated rats. Co-localization between these markers and nuclear β-catenin (NBC), an attributed feature of cancer stem cells, was also determined. Moreover, since PGE2 could increase NBC, we tested whether short-term treatment with celecoxib, a COX-2 inhibitor (2 weeks, 250 ppm in the diet) could reduce the expression of these markers.ResultsLGR-5 expression in NM was low (Labelling Index (LI): 0.22±0.03 (means±SE)) with positive cells located mainly at the base of the crypts. Compared to NM, LGR-5 was overexpressed in MDF and tumours (LI: 4.7±2.0 and 2.9±1.0 in MDF and tumours, respectively, P<0.01 compared to NM). DCAMKL-1 positive cells, distributed along the length of normal crypts, were reduced in MDF and tumours. Nuclear expression of MSI-1, located mainly at the base of normal crypts, was not observed in MDF or tumours. In both MDF and tumours, few cells co-expressed LGR-5 and NBC (LI: 1.0±0.3 and 0.4±0.2 in MDF and tumours, respectively). Notwithstanding the lower expression of DCAMKL-1 in tumours, the percentage of cells co-expressing DCAMKL-1 and NBC was higher than in NM (LI: 0.5±0.1 and 0.04±0.02 in tumours and NM, respectively). MSI-1 and NBC co-localization was not observed. Celecoxib did not reduce cells co-expressing LGR-5 and NBC.ConclusionsBased on its prevalent localization at the base of normal crypts, as expected for stem cells, and on the overexpression in precancerous lesions and tumours, we support LGR-5, but not MSI-1 or DCAMKL-1, as putative neoplastic stem cell marker. In both MDF and tumours, we identified LGR-5-positive cells co-expressing NBC which could be a subpopulation with the highest stem cell features.

The stem cell self-renewal gene, Musashi 1, is highly expressed in tumor and non-tumor samples of human bladder

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. 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. Relative expression of MSI1 was determined by the real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) in 70 surgical samples of bladder. 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). All together, our data demonstrated that Musashi 1 is highly and un-differentially expressed in both examined tumoral and apparently normal bladder tissues.

Expression and significance of Musashi-1 in gastric cancer and precancerous lesions

To investigate expression of stem cell marker Musashi-1 (Msi-1) in relationship to tumorigenesis and progression of intestinal-type gastric cancer (GC). Endoscopic biopsy specimens and surgical specimens were obtained, including 54 cases of intestinal-type GC, 41 high-grade intraepithelial neoplasia, 57 low-grade intraepithelial neoplasia, 31 intestinal metaplasia, and 36 normal gastric mucosa. Specimens were fixed in 10% paraformaldehyde, conventionally dehydrated, embedded in paraffin, and sliced in 4-μm-thick serial sections. Two-step immunohistochemical staining was used to detect Msi-1 and proliferating cell nuclear antigen (PCNA) expression. Correlation analysis was conducted between Msi-1 and PCNA expression. The relationship between Msi-1 expression and clinicopathological parameters of GC was analyzed statistically. There were significant differences in Msi-1 and PCNA expression in different pathological tissues (χ² = 15.37, P < 0.01; χ² = 115.36, P < 0.01). Msi-1 and PCNA-positive cells were restricted to the isthmus of normal gastric glands. Expression levels of Msi-1 and PCNA in intestinal metaplasia were significantly higher than in normal mucosa (U = 392.0, P < 0.05; U = 40.50, P < 0.01), whereas there was no significant difference compared to low or high-grade intraepithelial neoplasia. Msi-1 and PCNA expression in intestinal-type GC was higher than in high-grade intraepithelial neoplasia (U = 798.0, P < 0.05; U = 688.0, P < 0.01). There was a significantly positive correlation between Msi-1 and PCNA expression (r(s) = 0.20, P < 0.01). Msi-1 expression in GC tissues was correlated with their lymph node metastasis and tumor node metastasis stage (χ² = 12.62, P < 0.01; χ² = 11.24, P < 0.05), but not with depth of invasion and the presence of distant metastasis. Msi-1-positive cells may play a key role in the early events of gastric carcinogenesis and may be involved in invasion and metastasis of GC.

C-Kit and Musashi-1 expression in colorectal carcinoma and its association with etiological factors

c-Kit and Musashi-1 expression in colorectal carcinoma and its association with etiological factors

Epigenetic Regulation of Cancer Stem Cell Genes in Triple-Negative Breast Cancer

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.

C-Kit and Musashi-1 expression in colorectal carcinoma and its association with etiological factors

Introduction: The proto-oncogene c-Kit encodes a tyrosine kinase receptor which is essential during embryonic and postnatal life but its expression in precancerous lesions has not been studied. Musashi-1 was initially identified as a neuronal stem cell marker and recently as an intestinal stem cell marker and is aberrantly expressed in several cancers including colorectal cancer, but its role in neoplastic tissues has not been elucidated. The present study aims to study the expression of c-Kit and Musashi-1 in precancerous lesions and colorectal carcinoma in correlation with etiological factors. Methods: Immunohistochemical analysis, western blot and RT-PCR were done to observe the expression of c-Kit and Musashi-1 in normal, ulcerative colitis, adenoma and adenocarcinoma of colorectal tissues. Results: c-Kit expression was observed to decrease from normal to adenocarcinoma. In contrast, Musashi-1 showed increased expression from adenoma to carcinoma stages. Furthermore, c-Kit showed statistically significant association with alcoholic and non-alcoholic patients (p Conclusions: Overall, these studies indicate that the decreased or loss of c-Kit and increase in the Musashi-1 expression in carcinoma can be attributed to the disease progression and malignant transformation of colorectal epithelium. A statistically significant negative correlation was found between c-Kit and Musashi-1 in colorectal carcinoma.

Aberrant expression of CD133 and musashi‐1 in preneoplastic and neoplastic human oral squamous epithelium and their correlation with clinicopathological factors

The present study focuses on the expression pattern of the stem cell markers CD133 and Musashi-1 in precancerous and cancerous tissues of oral epithelium. The study also aims to investigate the correlation of CD133 and Musashi-1 expression with clinicopathological factors. Immunohistochemical analysis was done to investigate the expression pattern of CD133 and Musashi-1, whereas, the coexpression of CD133 and Musashi-1 was studied using immunofluorescence analysis. A gradual increase in the expression of CD133 and Musashi-1 was observed from normal to dysplasia to carcinoma. In addition, the expression of CD133 and Musashi-1 shows significant difference between the stages and histological types of oral carcinoma. Interestingly, coexpression of CD133 and Musashi-1 was observed in oral carcinoma and CAL27 cells. A gradual increase in the expression of CD133 and Musashi-1 from normal to dysplasia to carcinoma suggests the possible involvement of these 2 proteins in oral carcinogenesis. The overexpression of CD133 and Musashi-1 in advanced stages and also in poorly differentiated tumors reveals their relationship with invasion and differentiation status of oral carcinoma cells. Moreover, the significant positive correlation between CD133 and Musashi-1 expression suggests that they might have a functional relationship in oral carcinoma cells, which needs further investigation.

&lt;i&gt;In Vitro&lt;/i&gt; Isolation of Intestinal Side Population Cells from Newborn Mice

To isolate side population cells from newborn mice small intestinal mucosa, and to investigate the feasibility of constructing the murine intestinal stem cell population by fluorescence activated cell sorting. Small intestine mucosa organoids of mice were isolated and dissociated into single cells. The side population cells were stained with Hoechst 33342 and propidium iodide, then sorted using fluorescence activated cell sorting. Total RNA and protein were purified from sorted fractions to detect Musashi-1 expressions by RT-PCR and Western-blotting. Single cell suspension from mouse small intestine mucosa contained a viable population of cells, which showed the side population phenotype and were sensitive to verapamil. These cells were enriched for Musashi-1 mRNA and MSI-1 protein expression. Results demonstrated that the side population fraction separated from mice intestinal mucosa is enriched for intestinal stem cells, the murine intestinal stem cell population can be successfully constructed with fluorescence activated cell sorting.

Musashi1 expression cells derived from mouse embryonic stem cells can be enriched in side population isolated by fluorescence activated cell sorter

BackgroundPurifying stem cells is an inevitable process for further investigation and cell-therapy. Sorting side population (SP) cells is generally regarded as an effective method to enrich for progenitor cells. This study was to explore whether sorting SP could enrich for the Musashi1 (Msi1) positive cells from Msi1 high expression cells (Msi1high cells) derived from mouse embryonic stem cells (ESCs) in vitro.ResultsIn this study, Msi1high cell population derived from ESCs were stained by Hoechst 33342, and then the SP and non-SP (NSP) fractions were analyzed and sorted by fluorescence activated cell sorter. Subsequently, the expressions of Msi1 and other markers for neural and intestinal stem cells in SP and NSP were respectively detected. SP and NSP cells were hypodermically engrafted into the backs of NOD/SCID mice to form grafts. The developments of neural and intestinal epithelial cells in these grafts were investigated. SP fraction was identified and isolated from Msi1high cell population. The expression of Msi1 in SP fraction was significantly higher than that in NSP fraction and unsorted Msi1high cells (P< 0.05). Furthermore, the markers for neural cells and intestinal epithelial cells were more highly expressed in the grafts from SP fraction than those from NSP fraction (P< 0.05).ConclusionsSP fraction, isolated from Msi1high cells, contains almost all the Msi1-positive cells and has the potential to differentiate into neural and intestinal epithelial cells in vivo. Sorting SP fraction could be a convenient and practical method to enrich for Msi1-positive cells from the differentiated cell population derived from ESCs.

Expression of a putative stem cell marker Musashi-1 in endometrium.

Firstly to examine the expression characteristics of Musashi (Msi)-1 in fetal endometrium, reproductive normal endometrium, endometrial hyperplasia and endometrioid adenocarcinoma, next, to focus on exploring the possibility that Msi-1 serves as a marker of the endometrial stem cells in-situ. Immunohistochemical staining was performed to detect the expression of Msi-1 in 20 cases of fetal endometrium, 20 cases of normal endometrium, 20 cases of endometrial hyperplasia and 50 cases of endometrioid adenocarcinoma respectively. In fetal endometrium, Msi-1 positive cells were observed from the 12th week in epithelium, but the number of Msi-1 positive cells decreased with an increase in gestational age. In reproductive normal endometrium, Msi-1 expression presented as dispersed single cell and cell groups in the stroma adjacent to the myometrium. In endometrial hyperplasia and endometrioid adenocarcinoma, Msi-1 expression significantly increased and was more widely distributed. Msi-1 positive cells mainly lie in the stroma of normal endometrium, and the distribution pattern is consistent with that of the speculated endometrial stem cells. The high expression of Msi-1 in fetal endometrium and endometrioid adenocarcinoma suggests that Msi-1 positive cells have several characteristics of stem cells, such as high proliferative potentiality and multipotency. Considering these factors, this makes Msi-1 potentially a promising stem cell marker.

YB-1 Bridges Neural Stem Cells and Brain Tumor–Initiating Cells via Its Roles in Differentiation and Cell Growth

The Y-box binding protein 1 (YB-1) is upregulated in many human malignancies including glioblastoma (GBM). It is also essential for normal brain development, suggesting that YB-1 is part of a neural stem cell (NSC) network. Here, we show that YB-1 was highly expressed in the subventricular zone (SVZ) of mouse fetal brain tissues but not in terminally differentiated primary astrocytes. Conversely, YB-1 knockout mice had reduced Sox-2, nestin, and musashi-1 expression in the SVZ. Although primary murine neurospheres were rich in YB-1, its expression was lost during glial differentiation. Glial tumors often express NSC markers and tend to loose the cellular control that governs differentiation; therefore, we addressed whether YB-1 served a similar role in cancer cells. YB-1, Sox-2, musashi-1, Bmi-1, and nestin are coordinately expressed in SF188 cells and 9/9 GBM patient-derived primary brain tumor-initiating cells (BTIC). Silencing YB-1 with siRNA attenuated the expression of these NSC markers, reduced neurosphere growth, and triggered differentiation via coordinate loss of GSK3-β. Furthermore, differentiation of BTIC with 1% serum or bone morphogenetic protein-4 suppressed YB-1 protein expression. Likewise, YB-1 expression was lost during differentiation of normal human NSCs. Consistent with these observations, YB-1 expression increased with tumor grade (n = 49 cases). YB-1 was also coexpressed with Bmi-1 (Spearmans 0.80, P > 0.001) and Sox-2 (Spearmans 0.66, P > 0.001) based on the analysis of 282 cases of high-grade gliomas. These proteins were highly expressed in 10/15 (67%) of GBM patients that subsequently relapsed. In conclusion, YB-1 correlatively expresses with NSC markers where it functions to promote cell growth and inhibit differentiation.

Sequential expression of putative stem cell markers in gastric carcinogenesis

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.

Expression of Nestin and Musashi-1 in human glioma and clinical significance

Objective To investigate the expression of Nestin and Musashi-1 in human glioma tissues and its clinicopathogical significance.Methods The expression of Nestin and Musashi-1 was examined in 50 human glioma samples by using immunohistochemistry staining.Results The expression rate of Nestin and Musashi-1 in glioma tissues was 76% and 68% respectively. There was a positive correlation between the expression of Nestin and Musashi-1 in glioma tissues. Immunohistochemical results showed that the positive rate of Nestin and Musashi-1 in low and high grade malignant gliomas was 60.9% (14/23), 88.9% (24/27); 52.2% (12/23), 81.5% (22/27) respectively (P<0.05).Conclusion The expression of Nestin and Musashi-1 may play a pivotal role in the initiation and development of glioma and may be correlated with cthe prognosis of glioma. Key words: Glioma; Nestin; Musashi-1

The response of intestinal stem cells and epithelium after alemtuzumab administration

Intestinal stem cells may have important roles in the maintenance of epithelial integrity during tissue repair. Alemtuzumab is a humanized anti-CD52 lymphocytic antibody that is increasingly being used to induce immunosuppression; intestinal barrier function is impaired during treatment with alemtuzumab. We investigated the response of intestinal stem cells to epithelial damage resulting from alemtuzumab treatment. Intestinal epithelial cell loss and abnormal Paneth cell morphology were found following a single dose of alemtuzumab. The animals receiving alemtuzumab exhibited increased apoptosis in the villi 3 days after alemtuzumab treatment and in the crypt on day 9, but apoptosis was scarce on day 35. We assessed expression of Musashi-1- and Lgr5-positive stem cells following alemtuzumab treatment. Increased numbers of cells staining positive for both Musashi-1 and Lgr5 were found in the stem cell zone after alemtuzumab treatment for 3 and 9 days. These data indicated that the epithelial cells were injured following alemtuzumab treatment, with the associated expansion of intestinal stem cells. After alemtuzumab treatment for 35 days, the numbers of intestinal epithelial cells and intestinal stem cells returned to normal. This study suggests that alemtuzumab treatment induced the increase in stem cells, resulting in the availability of more enterocytes for repair.

The adult stem cell marker Musashi‐1 modulates endometrial carcinoma cell cycle progression and apoptosis via Notch‐1 and p21WAF1/CIP1

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.