Murine Leukemia Virus Integration Site Research Articles

Bmi-1 regulates stem cell-like properties of gastric cancer cells via modulating miRNAs.

BackgroundB cell-specific Moloney murine leukemia virus integration site 1 (Bmi-1) plays an important role in regulating stemness in some kinds of cancer. However, the mechanisms remain unclear. This study was to investigate whether and how Bmi-1 regulates stemness of gastric cancer.MethodsWe firstly explored the role of Bmi-1 in regulating stem cell-like features in gastric cancer. Secondly, we screened out its downstream miRNAs and clarified whether these miRNAs are involved in the regulation of stemness. Finally, we investigated the mechanisms how Bmi-1 regulates miRNAs.ResultsBmi-1 positively regulates stem cell-like properties of gastric cancer and upregulates miR-21 and miR-34a. There was a positive correlation between Bmi-1 and miR-21 expression in gastric cancer tissues. MiR-21 mediated the function of Bmi-1 in regulating stem cell-like properties, while miR-34a negatively regulates stem cell-like characteristics via downregulating Bmi-1. Bmi-1 binds to PTEN promoter and directly inhibits PTEN and thereafter activates AKT. Bmi-1 also regulates p53 and PTEN via miR-21. Bmi-1 activated NF-kB via AKT and enhanced the binding of NF-kB to the promoter of miR-21 and miR-34a and increased their expression.ConclusionsBmi-1 positively regulates stem cell-like properties via upregulating miR-21, and miR-34a negatively regulates stem cell-like characteristics by negative feedback regulation of Bmi-1 in gastric cancer. Bmi-1 upregulates miR-21 and miR-34a by activating AKT-NF-kB pathway.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-016-0323-9) contains supplementary material, which is available to authorized users.

Acute myeloid leukemia stem cell markers in prognosis and targeted therapy: potential impact of BMI-1, TIM-3 and CLL-1.

Acute myeloid leukemia (AML) patients show high relapse rates and some develop conventional chemotherapy resistance. Leukemia Stem Cells (LSCs) are the main player for AML relapses and drug resistance. LSCs might rely on the B-cell-specific Moloney murine leukemia virus integration site-1 (BMI-1) in promoting cellular proliferation and survival. Growth of LSCs in microenvironments that are deprived of nutrients leads to up-regulation of the signaling pathways during the progression of the disease, which may illustrate the sensitivity of LSCs to inhibitors of those signaling pathways as compared to normal cells. We analyzed the expression of LSC markers (CD34, CLL-1, TIM-3 and BMI-1) using quantitative RT-PCR in bone marrow samples of 40 AML patients of different FAB types (M1, M2, M3, M4, M5, and M7). We also studied the expression of these markers in 2 AML cell lines (Kasumi-1 and KG-1a) using flow cytometry and quantitative RT-PCR. The overexpression of TIM-3, CLL-1, and BMI-1 was markedly correlated with poor prognosis in these patients. Our in vitro findings demonstrate that targeting BMI-1, which markedly increased in the leukemic cells, was associated with marked decrease in leukemic burden. This study also presents results for blocking LSCs' surface markers CD44, CLL-1, and TIM-3. These markers may play an important role in elimination of AML. Our study indicates a correlation between the expression of markers TIM-3, CLL-1, and especially of BMI-1 and the aggressiveness of AML and thus the potential impact of prognosis and therapies that target LSCs on improving the cure rates.

B-cell-specific Moloney murine leukemia virus integration site 1: potential stratification factor and therapeutic target for epithelial ovarian cancer.

Epithelial ovarian cancer, a vexing challenge for clinical management, still lacks biomarkers for early diagnosis, precise stratification, and prognostic evaluation of patients. B-cell-specific Moloney murine leukemia virus integration site 1 (BMI1), a member of the polycomb group of proteins, engages in diverse cellular processes, including proliferation, differentiation, senescence, and stem cell renewal. In addition, BMI1, as a cancer stem-cell marker, participates in tumorigenesis through various pathways. Rewardingly, recent studies have also revealed a relationship between BMI1 expression and the clinical grade/stage, therapy response, and survival outcome in a majority of human malignancies, including epithelial ovarian cancer. Therefore, BMI1 might serve as a potential stratification factor and treatment target for epithelial ovarian cancer, pending evidence from further investigations.

BMI1 is downregulated by the natural compound curcumin, but not by bisdemethoxycurcumin and dimethoxycurcumin.

The B‐cell‐specific Moloney murine leukemia virus integration site 1 (BMI1) locus encodes a 37‐kD protein that is a key regulatory component of the polycomb regulatory complex 1 (PRC1). When overexpressed in various cancer types, the BMI1 protein induces cell growth and promotes tumor growth in vitro and in vivo. Curcumin, a major phytochemical in turmeric (Curcuma longa), inhibits the proliferation and survival of many types of cancer cells, both in vitro and in vivo, and has been reported to reduce BMI1 expression in breast cancer cells. In this study, effects of curcumin and two analogs (bisdemethoxycurcumin and dimethoxycurcumin) on BMI1 expression were evaluated in DLD‐1 colorectal cancer cells. Bisdemethoxycurcumin (BDMC) is naturally occurring in turmeric, whereas dimethoxycurcumin (DMC) is a synthetic analog of curcumin. All three compounds reduced cell survival, but only the natural compound downregulated BMI1 protein expression; curcumin significantly reduced BMI1 levels more than bisdemethoxycurcumin and dimethoxycurcumin. In addition, curcumin and BDMC inhibit survival of the DLD‐1 colorectal cancer cells by inducing apoptosis, whereas DMC inhibits survival by a mechanism other than apoptosis.

Auraptene Attenuates Malignant Properties of Esophageal Stem-Like Cancer Cells.

The high incidence of esophageal squamous cell carcinoma has been reported in selected ethnic populations including North of Iran. Low survival rate of esophageal carcinoma is partially due to the presence of stem-like cancer cells with chemotherapy resistance. In the current study, we aimed to determine the effects of auraptene, an interesting dietary coumarin with various biological activities, on malignant properties of stem-like esophageal squamous cell carcinoma, in terms of sensitivity to anticancer drugs and expression of specific markers. To do so, the half maximal inhibitory concentration values of auraptene, cisplatin, paclitaxel, and 5-fluorouracil were determined on esophageal carcinoma cells (KYSE30 cell line). After administrating combinatorial treatments, including nontoxic concentrations of auraptene + cisplatin, paclitaxel, or 5-fluorouracil, sensitivity of cells to chemical drugs and also induced apoptosis were assessed. In addition, quantitative real-time polymerase chain reaction was used to study changes in the expression of tumor suppressor proteins 53 and 21 ( P53 and P21), cluster of differentiation 44 ( CD44), and B cell-specific Moloney murine leukemia virus integration site 1 ( BMI-1) upon treatments. Results of thiazolyl blue assay revealed that auraptene significantly ( P < .05) increased toxicity of cisplatin, paclitaxel, and 5-fluorouracil in KYSE30 cells, specifically 72 hours after treatment. Conducting an apoptosis assay using flow cytometry also confirmed the synergic effects of auraptene. Results of quantitative real-time polymerase chain reaction revealed significant ( P < .05) upregulation of P53 and P21 upon combinatorial treatments and also downregulation of CD44 and BMI-1 after auraptene administration. Current study provided evidence, for the first time, that auraptene attenuates the properties of esophageal stem-like cancer cells through enhancing sensitivity to chemical agents and reducing the expression of CD44 and BMI-1 markers.

Radiosensitization of esophageal carcinoma cells by the silencing of BMI-1.

Radiotherapy (RT) has been widely used to treat cancer patients, particularly esophageal cancer patients. B-cell-specific Moloney murine leukemia virus integration site-1 (BMI-1) plays an important role in promoting the growth of cancer cells after exposure to irradiation. The present study aimed to characterize the effects of BMI-1 on the proliferation and invasion of cancer cells, as well as the mechanism involved in the regulation of the growth of esophageal cancer ECA109 and TE13 cells. The expression levels of the BMI-1 gene and protein in esophageal cancer ECA109 and TE13 cells were determined by quantitative PCR and western blotting after transfection. Co-immunoprecipitation (Co-IP) assay was employed to detect the interaction of BMI-1 with r-H2AX and H2AK119ub. We used flow cytometry to analyze the cell cycle distribution and apoptosis of transfected cells after irradiation or not, and examined cellular growth and invasion invitro by MTS and Transwell assays. The results revealed that shRNA targeting the BMI-1 gene and protein downregulated BMI-1 expression after transfection for 24h. The proliferation and invasion of tumor cells in the BMI-1‑shRNA group were suppressed after RT. In addition, the interaction of BMI-1, H2AK119ub and r-H2AX was increased after exposure to IR, followed by an increased apoptosis rate and decreased percentage of cells arrested at the G2/Mphase after irradiation and silencing of BMI-1 by shRNA. Knockdown of BMI-1 expression decreased the phosphorylation of H2AX, upregulated p16, and induced the radiosensitivity of esophageal cancer ECA109 and TE13 cells invitro and significantly inhibited the growth and invasion of tumor cells. The mechanisms were found to be abrogation of cell cycle arrest at the G2/Mstage and promotion of apoptosis.

Prognostic Value and Clinicopathological Differences of Bmi1 in Gastric Cancer: A Meta-analysis.

B cell-specific Moloney murine leukemia virus integration site 1 (Bmi1) was identified as a biomarker of cancer stem cells, and over-expression of Bmi1 might enhance tumor aggressive clinical behavior in gastric cancer (GC). Our aim of this meta-analysis is to investigate the prognostic role and clinicopathological differences of Bmi1 in GC patients. A total of 6 studies up to September 2014 were included in our study. Our results showed that there were no relationships between Bmi1 expression and the gender (pooled OR=0.87, 95%CI=0.66-1.14, P=0.319, fixed effect), age (pooled OR=1.22, 95%CI=0.95-1.59, P=0.126, fixed effect) and differentiation (pooled OR=1.15, 95%CI=0.71-1.86, P=0.582, random effect) in GC patients. But high Bmi1 expression was significantly correlated with the clinical stage (pooled OR=3.04, 95%CI=1.31-7.07, P=0.010, random effect), tumor size (pooled OR=2.01, 95%CI=1.14-3.55, P=0.016, random effect), T classification (pooled OR=2.79, 95%CI=1.94-4.03, P<0.001, fixed effect), lymph node metastasis (pooled OR=2.24, 95%CI=1.47-3.39, P<0.001, random effect) and distant metastasis (pooled OR=5.05, 95%CI=1.29-19.70, P=0.020, random effect), and led to a poor overall survival (OS) in GC patients (RR=3.38, 95%CI=2.43-4.69, P<0.001, fixed effect). These findings suggested that Bmi1 might serve as a novel and effective prognostic biomarker in GC, and could be a promising emerging molecular target in GC therapy.

Changes and significance of B cell specific monoclonal murine leukemia virus integration site-1 and helper T cell-related cytokine in children with immune thrombocytopenia

Objective To analyze the functional changes and the clinical significance of B cell specific monoclonal murine leukemia virus integration site-1(Bmi-1 ) and Th1/Th2 cells in children with newly diagnosed immune thrombocytopenia(ITP) by testing the mRNA expressions of Bmi-1, helper T cell-related cytokine interferon(IFN)-γ and interleukin(IL)-4 in children with newly diagnosed ITP. Methods Thirty-six cases of patients with newly diagnosed ITP in the experimental group came from the inpatient and outpatient children admitted to the Department of Pediatrics of the First Affiliated Hospital of Xinxiang Medical University from April to December 2013.In the control group, 26 cases of children requiring selective operation were admitted to the Department of Pediatric Surgery during the same period.The mRNA expressions of Bmi-1, IFN-γ and IL-4 in the peripheral blood lymphocytes were detected by means of the reverse transcription-polymerase chain reaction(RT-PCR) method, and were analyzed and compared by t test and linear correlation analysis. Results (1) The mRNA expressions of Bmi-1, IFN-γ and IL-4 in peripheral blood lymphocytes in the experimental group were 2.63±0.54, 3.84±0.43 and 1.44±0.39, respectively; while the mRNA expressions of Bmi-1, IFN-γ and IL-4 in the peripheral blood lymphocytes in the control group were 3.91±0.92, 2.88±0.57 and 1.87±0.34, respectively.The levels of IFN-γ of the experimental group were significantly higher than those of the control group (P 0.05). Conclusions Bmi-1 may be involved in the pathogenesis of ITP by regulating Th cell, and Th cell dysfunction may occur in the children with ITP, and the disproportion between Th1 and Th2 may be due to the advantages of Th1. Key words: B cell specific moloney murine leukemia virus integration site-1; Helper T cells; Immune thrombocytopenia; Child

Foxl1-expressing mesenchymal cells constitute the intestinal stem cell niche.

Background & AimsIntestinal epithelial stem cells that express leucine-rich repeat-containing G-protein coupled receptor 5 (Lgr5) and/or B cell specific Moloney murine leukemia virus integration site 1 (Bmi1) continuously replicate and generate differentiated cells throughout life. Previously, Paneth cells were suggested to constitute an epithelium-intrinsic niche that regulates the behavior of these stem cells. However, ablating Paneth cells has no effect on the maintenance of functional stem cells. Here, we show definitively that a small subset of mesenchymal subepithelial cells expressing the winged-helix transcription factor forkhead box l1 (Foxl1) are a critical component of the intestinal stem cell niche.MethodsWe genetically ablated Foxl1+ mesenchymal cells in adult mice using 2 separate models by expressing either the human or simian diphtheria toxin receptor under Foxl1 promoter control.ConclusionsKilling Foxl1+ cells by diphtheria toxin administration led to an abrupt cessation of proliferation of both epithelial stem- and transit-amplifying progenitor cell populations that was associated with a loss of active Wnt signaling to the intestinal epithelium. Therefore, Foxl1-expressing mesenchymal cells constitute the fundamental niche for intestinal stem cells.

Preclinical activity of the novel B-cell-specific Moloney murine leukemia virus integration site 1 inhibitor PTC-209 in acute myeloid leukemia: Implications for leukemia therapy.

Curing patients with acute myeloid leukemia (AML) remains a therapeutic challenge. The polycomb complex protein B-cell-specific Moloney murine leukemia virus integration site 1 (BMI-1) is required for the self-renewal and maintenance of leukemia stem cells. We investigated the prognostic significance of BMI-1 in AML and the effects of a novel small molecule selective inhibitor of BMI-1, PTC-209. BMI-1 protein expression was determined in 511 newly diagnosed AML patients together with 207 other proteins using reverse-phase protein array technology. Patients with unfavorable cytogenetics according to Southwest Oncology Group criteria had higher levels of BMI-1 compared to those with favorable (P = 0.0006) or intermediate cytogenetics (P = 0.0061), and patients with higher levels of BMI-1 had worse overall survival (55.3 weeks vs. 42.8 weeks, P = 0.046). Treatment with PTC-209 reduced protein level of BMI-1 and its downstream target mono-ubiquitinated histone H2A and triggered several molecular events consistent with the induction of apoptosis, this is, loss of mitochondrial membrane potential, caspase-3 cleavage, BAX activation, and phosphatidylserine externalization. PTC-209 induced apoptosis in patient-derived CD34(+)CD38(low/-) AML cells and, less prominently, in CD34(-) differentiated AML cells. BMI-1 reduction by PTC-209 directly correlated with apoptosis induction in CD34(+) primary AML cells (r = 0.71, P = 0.022). However, basal BMI-1 expression was not a determinant of AML sensitivity. BMI-1 inhibition, which targets a primitive AML cell population, might offer a novel therapeutic strategy for AML.

Targeting self-renewal pathways in cancer stem cells: clinical implications for cancer therapy.

Extensive cancer research in the past few decades has identified the existence of a rare subpopulation of stem cells in the grove of cancer cells. These cells are known as the cancer stem cells marked by the presence of surface biomarkers, multi-drug resistance pumps and deregulated self-renewal pathways (SRPs). They have a crucial role in provoking cancer cells leading to tumorigenesis and its progressive metastasis. Cancer stem cells (CSCs) are much alike to normal stem cells in their self-renewal mechanisms. However, deregulations in the SRPs are seen in CSCs, making them resistant to conventional chemotherapeutic agents resulting in the tumor recurrence. Current treatment strategies in cancer fail to detect and differentiate the CSCs from their non-tumorigenic progenies owing to absence of specific biomarkers. Now, it has become imperative to understand complex functional biology of CSCs, especially the signaling pathways to design improved treatment strategies to target them. It is hopeful that the SRPs in CSCs offer a promising target to alter their survival strategies and impede their tumorigenic potential. However, there are many perils associated with the direct targeting method by conventional therapeutic agents such as off targets, poor bioavailability and poor cellular distribution. Recent evidences have shown an increased use of small molecule antagonists directly to target these SRPs may lead to severe side-effects. An alternative to solve these issues could be an appropriate nanoformulation. Nanoformulations of these molecules could provide an added advantage for the selective targeting of the pathways especially Hedgehog, Wnt, Notch and B-cell-specific moloney murine leukemia virus integration site 1 in the CSCs while sparing the normal stem cells. Hence, to achieve this goal a complete understanding of the molecular pathways corroborate with the use of holistic nanosystem (nanomaterial inhibition molecule) could possibly be an encouraging direction for future cancer therapy.

Expression of B cell-specific Moloney murine leukemia virus integration site 1 in vulvar squamous cell carcinoma and its effect on the biological behavior of A-431 cells.

The aim of the present study was to investigate the expression of B cell-specific Moloney murine leukemia virus integration site 1 (BMI-1) in vulvar squamous cell carcinoma (VSCC) and vulvar intraepithelial neoplasia (VIN). Furthermore, the present study investigated the effects of BMI-1 expression on the biological behavior of A-431 human epidermoid carcinoma cells. BMI-1 expression in human VSCC and VIN tissues was detected using immunohistochemistry. Subsequently, BMI-1 expression was silenced in A-431 cells using small interfering RNA (siRNA), and BMI-1 expression was detected using reverse transcription-quantitative polymerase chain reaction and western blotting. The effects of BMI-1 silencing on cell proliferation, apoptosis and invasive ability were determined using an MTT assay, Annexin V-fluorescein isothiocyanate/propidium iodide double-labeling experiment and Transwell assay, respectively. The expression rate of BMI-1 in normal vulvar, VIN and VSCC tissues was 0.0, 25.0 and 68.0% respectively, demonstrating an increasing trend in the severity of the disease. BMI-1 overexpression was found not to correlate with age, pathological stage, lymph node metastasis or degree of differentiation (P>0.05). BMI-1 siRNA transfection effectively inhibited BMI-1 messenger RNA and protein expression in A-431 cells. The mean rate of apoptosis promotion and proliferation inhibition in the most effectively silenced group were 20.19 and 46.82%, respectively, which was significantly higher than that of the cells in the blank and control siRNA groups (P<0.05). The number of invading cells was decreased in the most effectively silenced group compared with that of the blank and control siRNA groups. Abnormal expression of BMI-1 was also detected in VIN and VSCC tissues, and targeting of BMI-1 with siRNA was able to successfully silence BMI-1 expression in A-431 cells. Silencing of BMI-1 promoted apoptosis and inhibited the invasive abilities of A-431 cells in vitro.

Overexpression and lack of copy number variation in the BMI-1 gene in human glioma.

Malignant gliomas are neoplasms of the brain that are associated with a poor prognosis. The B-cell-specific Moloney murine leukemia virus integration site 1 (BMI-1) gene is one of the major cancer stem cell factors responsible for treatment failure in glioma. In the present study, the DNA-RNA-protein alterations in the BMI-1 gene were assessed in 50 glioma samples. Copy number variations in the BMI-1 gene were analyzed using SYBR® Green quantitative polymerase chain reaction. Gene expression analysis was performed using a Taqman assay and protein quantitation was performed using western blotting. A comparative Ct analysis showed the absence of copy number variations in all glioma samples. BMI-1 mRNA expression was found to be overexpressed in 36 out of 50 samples (72.0%), and 37 out of 50 samples showed overexpression (74.0%) of BMI-1 protein; this was statistically significant when compared with non-glioma tissues. It was observed that the protein and RNA expression in glioma were concordant. In this study on the BMI-1 gene, transcription and translation in glioma were observed and BMI-1 overexpression was found to be a common phenomenon.

IDH1R¹³²H decreases the proliferation of U87 glioma cells through upregulation of microRNA-128a.

Mutations in isocitrate dehydrogenase 1 (IDH1) are found in >70% of secondary glioblastomas and lower-grade gliomas (grades II–III). Among the numerous phenotypic differences between IDH1 mutant and wild-type glioma patients, the most salient is an improved survival rate for patients with a mutation. MicroRNAs (miRNAs) are a class of small, non-coding, single-stranded RNAs that can negatively regulate gene expression at the post-transcriptional level, predominantly by binding to the 3′-untranslated region of their target mRNAs. The dysregulated expression of several miRNAs has been reported to modulate glioma progression; however, it is unclear whether mutations in IDH1 regulate glioma cell proliferation through miRNA dysregulation. In the present study, stable overexpression of IDH1WT or IDH1R132H was established in the U87 glioma cell line. It was found that IDH1R132H decreased cell proliferation of U87 glioma cells by inducing the expression of the miRNA miR-128a. This process was dependent on the transcription factor hypoxia inducible factor-1α (HIF-1α), which binds to a hypoxia response element in the promoter of miR-128a. Furthermore, miR-128a negatively regulated the expression of B-cell-specific Moloney murine leukemia virus integration site 1 protein (Bmi-1), which is involved in suppressing cell proliferation. These findings suggest that the IDH1R132H-HIF-1α-miR-128a-Bmi-1 pathway is involved in glioma cell proliferation.

The Stem Cell Marker Bmi-1 Is Sensitive in Identifying Early Lesions of Carcinoma ex Pleomorphic Adenoma.

In the present study, we evaluated and described the sensitivity of the stem cell marker B cell-specific moloney murine leukemia virus integration site 1 (Bmi-1) in identifying early lesions of carcinoma ex pleomorphic adenoma (CXPA). While invasive CXPAs are tumors with a prominent and easily recognizable malignant component, the identification of early carcinomatous changes in PA remains a diagnostic challenge due to the lack of objective morphological criteria. The immunohistochemical expression of Bmi-1 was assessed in both adenomatous and carcinomatous components of 9 CXPA cases at an early phase of histological progression (6 intracapsular and 3 minimally invasive) grouped according to the cellular differentiation as luminal (7 cases) or myoepithelial (2 cases). A selective nuclear expression of Bmi-1 was found exclusively in the malignant component of 8 cases (6 luminal type and 2 myoepithelial type), including intraductal carcinoma areas, except for 1 case in which scarce cells of the remnant PA were positive. Thus, Bmi-1 is expressed from the earliest morphologically detectable stages of PA malignant transformation. When faced with atypical features in PA, evaluation of Bmi-1 expression can provide more objective criteria for identification and diagnosis of early lesions of CXPA. This is applied to carcinomas with luminal or myoepithelial differentiation.

Downregulated miR-495 [Corrected] Inhibits the G1-S Phase Transition by Targeting Bmi-1 in Breast Cancer.

Bmi-1 (B cell-specific Moloney murine leukemia virus integration site 1) is upregulated in breast cancer and was involved in many malignant progressions of breast cells, including cell proliferation, stem cell pluripotency, and cancer initiation. However, the epigenetic regulatory mechanism of Bmi-1 in breast cancer remains unclear. After analysis of the ArrayExpress dataset GSE45666, we comparatively detected the expression levels of miR-495 in 9 examined breast cancer cell lines, normal breast epithelial cells and 8 pairs of fresh clinical tumor samples. Furthermore, to evaluate the effect of miR-495 on the progression of breast cancer, MCF-7 and MDA-MB-231 were transduced to stably overexpress miR-495. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay, colony formation assays, 5-Bromo-2-deoxyUridine labeling and immunofluorescence, anchorage-independent growth ability assay, flow cytometry analysis, and luciferase assays were used to test the effect of miR-495 in MCF-7 and MDA-MB-231 cells in vitro. Xenografted tumor model was also used to evaluate the effect of miR-495 in breast cancer. Herein, we found that miR-495, a predicted regulator of Bmi-1, was frequently downregulated in malignant cells and tissues of breast. Upregulation of miR-495 significantly suppressed breast cancer cell proliferation and tumorigenicity via G1-S arrest. Further analysis revealed that miR-495 targeted Bmi-1 through its 3' untranslated region. Moreover, Bmi-1 could neutralize the suppressive effect of miR-495 on cell proliferation and tumorigenicity of breast cancer in vivo. These data suggested that miR-495 could inhibit the G1-S phase transition that leads to proliferation and tumorigenicity inhibition by targeting and suppressing Bmi-1 in breast cancer.

Interaction of tetraspan(in) TM4SF5 with CD44 promotes self‐renewal and circulating capacities of hepatocarcinoma cells

Tumor metastasis involves circulating and tumor-initiating capacities of metastatic cancer cells. Epithelial-mesenchymal transition (EMT) is related to self-renewal capacity and circulating tumor cell (CTC) characteristics for tumor metastasis. Although tumor metastasis is a life-threatening, complicated process that occurs through circulation of tumor cells, mechanistic aspects of self-renewal and circulating capacities have been largely unknown. Hepatic transmembrane 4 L six family member 5 (TM4SF5) promotes EMT for malignant growth and migration, so it was rationalized that TM4SF5, as a hepatocellular carcinoma (HCC) biomarker, might be important for metastatic potential. Here, self-renewal capacity by TM4SF5 was mechanistically explored using hepatocarcinoma cells with or without TM4SF5 expression, and we explored whether they became CTCs using mouse liver-orthotopic model systems. We found that TM4SF5-dependent sphere growth correlated with CD24(-) , aldehyde dehydrogenase (ALDH) activity, as well as a physical association between CD44 and TM4SF5. Interaction between TM4SF5 and CD44 was through their extracellular domains with N-glycosylation modifications. TM4SF5/CD44 interaction activated proto-oncogene tyrosine-protein kinase Src (c-Src)/signal transducer and activator of transcription 3 (STAT3)/Twist-related protein 1 (Twist1)/B-cell-specific Moloney murine leukemia virus integration site 1 (Bmi1) signaling for spheroid formation, whereas disturbing the interaction, expression, or activity of any component in this signaling pathway inhibited spheroid formation. In serial xenografts using 200∼5,000 cells per injection, TM4SF5-positive tumors exhibited subpopulations with locally increased CD44 expressions, supporting for tumor cell differentiation. TM4SF5-positive, but not TM4SF5- or CD44-knocked-down, cells were identified circulating in blood 4-6 weeks after orthotopic liver injection using in vivo laser scanning endomicroscopy. Anti-TM4SF5 reagent blocked their metastasis to distal intestinal organs. TM4SF5 promotes self-renewal and CTC properties supported by TM4SF5(+) /CD44(+(TM4SF5-bound)) /ALDH(+) /CD24(-) markers during HCC metastasis.

Inverse association between Bmi-1 and RKIP affecting clinical outcome of gastric cancer and revealing the potential molecular mechanisms underlying tumor metastasis and chemotherapy resistance.

B-cell-specific Moloney murine leukemia virus integration site 1 (Bmi-1) and Raf kinase inhibitory protein (RKIP) are involved in cancer metastasis and chemotherapeutic resistance, respectively. In this study, we evaluated the association between Bmi-1 and RKIP and outcome of gastric cancer through clinical data analysis and in vitro experiments. Bmi-1 expression and RKIP expression were observed in 107 cases of gastric cancer through use of tissue microarray technology to identify their correlations with clinicopathological parameters, patient survival, and susceptibility to chemotherapy. The correlation was confirmed in gastric cancer cell lines, analyzed further by gene overexpression and silencing analysis, a cell invasion assay, and a chemosensitivity test. Positive expression of Bmi-1 was highly correlated with T classification and clinical stage. Diminished or lost expression of RKIP was significantly associated with T classification, lymph node metastasis, distant metastasis, and clinical stage. Bmi-1 is negatively and RKIP is positively related to patient survival. Positive expression of Bmi-1 and negative expression of RKIP are associated with poor patient survival and modest efficacy of postoperative chemotherapy. A meaningfully inverse association between Bmi-1 and RKIP was found in tissue microarray studies, and was verified further in gastric cancer cell lines. Moreover, gene overexpression and silencing analysis indicated that RKIP might be regulated by Bmi-1. Furthermore, the impacts of Bmi-1 on cell invasion and chemotherapy resistance were rescued by knockdown of RKIP. Our study implies that detection of Bmi-1 and RKIP is valuable in predicting patient survival and therapeutic response in gastric cancer, and the inverse association between Bmi-1 and RKIP reveals the potential molecular mechanisms underlying tumor metastasis and chemotherapy resistance.

Establishment of detection method for serum circulating Bmi-1 mRNA and its application in diagnosis of colorectal cancer

Objective To establish a direct reverse transcription real-time fluorescence quantitative polymerase chain reaction （RT-qPCR-D） method for detecting serum circulating B cell-specific moloney murine leukemia virus integration site-1 (Bmi-1) mRNA, and analyze the levels of serum circulating Bmi-1 mRNA in colorectal cancer patients by using of this method for exploring its diagnosis value in colorectal cancer. Methods Methodology establishment. RNA was extracted from colorectal cancer HT29 cell line, and detection standard curves of Bmi-1, ubiquitin C（UBC）, glyceraldehyde-3-phosphate dehydrogenase（GAPDH）mRNAs were established, then the amplification efficiencies were calculated. Bmi-1 mRNA level was directly detected in serum and preparation buffer mixture, then the specificity of assay was evaluated by melting curve, and detection limit was observed through diluted serum samples. The serum circulating Bmi-1 mRNA levels were detected by ELISA in 158 cases with colorectal cancer, of which there were 26 cases of tumor node metastasis （TNM）Ⅰ stage, 53 cases of TNM Ⅱ, 47 cases of TNM Ⅲ, 32 cases of TNM Ⅳ and 53 cases of controls with normal colonoscopy collected from January 2008 to January 2009 in Qilu Hospital of Shandong University. Comparisons of groups were determined by applying Mann-Whitney U test or Kruskal-Wallis test, and receiver operating characteristic（ROC） curves were established to illustrate the diagnostic performance. Results The log values of Bmi-1, UBC and GAPDH showed good linear correlations with quantification cycle (Cq) values（R2=0.990, 0.990, 0.991, all P 0.05）. ROC curve analysis showed area under the ROC curve（AUC） for serum circulating Bmi-1 mRNA was 0.921（95%CI=0.876-0.953）, which was significantly superior to the AUC of CEA（0.745，95%CI=0.680-0.802，Z=4.697，P 0.05）. Conclusions The study establishes a higher sensitive, specific for detecting serum circulating Bmi-1 mRNA. Based on this method, serum circulating Bmi-1 mRNA is found to be increased in colorectal cancer, and is superior to traditional tumor marker CEA in diagnosis of colorectal cancer, which may become a potential detection index for early detection of colorectal cancer.（Chin J Lab Med,2014,37:678-682） Key words: Colorectal neoplasms; Reverse transcriptase polymerase chain reaction; Sensitivity and specificity

A retrospective review of the prognostic value of ALDH-1, Bmi-1 and Nanog stem cell markers in esophageal squamous cell carcinoma.

Stem cell markers are upregulated in various cancers and have potential as prognostic indicators. The objective of this study was to determine the expression of three stem cell markers, aldehyde dehydrogenase 1 (ALDH-1), B cell-specific Moloney murine leukemia virus integration site 1 (Bmi-1), and Nanog, in esophageal squamous cell carcinoma (ESCC) tissues. Immunohistochemistry was used to measure the expression of ALDH-1, Bmi-1, and Nanog in ESCC tissues from 41 patients who received pre-operative chemoradiation. We evaluated the relationship between expression of these markers, and clinicopathological features, tumor regression grade (TRG), and 5-year overall survival (OS). There were no significant associations of ALDH-1 or Bmi-1 expression with age, gender, clinical stage, and treatments (p>0.05). However, patients with Nanog-positive tumors were significantly older than those whose tumors were Nanog-negative (p = 0.033). TRG after treatment was significantly associated with expression of ALDH-1 (p = 0.001), Bmi-1 (p = 0.004), and Nanog (p<0.001). Although OS was significantly better in patients with low TRGs (p = 0.001), there were no significant correlations between ALDH-1, Bmi-1, or Nanog with OS. Expression of ALDH-1, Bmi-1, and Nanog correlated with TRG, but not OS. Further large studies are necessary to fully elucidate the prognostic value of these stem cell markers for ESCC patients.