Microarray analysis reveals potential mechanisms of BRMS1-mediated metastasis suppression

Long Non-Coding RNAs in Neuroblastoma: Pathogenesis, Biomarkers and Therapeutic Targets

Neuroblastoma is the most common malignant extracranial solid tumor of childhood. Recent studies involving the application of advanced high-throughput "omics" techniques have revealed numerous genomic alterations, including aberrant coding-gene transcript levels and dysfunctional pathways, that drive the onset, growth, progression, and treatment resistance of neuroblastoma. Research conducted in the past decade has shown that long non-coding RNAs, once thought to be transcriptomic noise, play key roles in cancer development. With the recent and continuing increase in the amount of evidence for the underlying roles of long non-coding RNAs in neuroblastoma, the potential clinical implications of these RNAs cannot be ignored. In this review, we discuss their biological mechanisms of action in the context of the central driving mechanisms of neuroblastoma, focusing on potential contributions to the diagnosis, prognosis, and treatment of this disease. We also aim to provide a clear, integrated picture of future research opportunities.

Salmonella enhances osteogenic differentiation in adipose-derived mesenchymal stem cells

The potential of mesenchymal stem cells (MSCs) for tissue repair and regeneration has garnered great attention. While MSCs are likely to interact with microbes at sites of tissue damage and inflammation, like in the gastrointestinal system, the consequences of pathogenic association on MSC activities have yet to be elucidated. This study investigated the effects of pathogenic interaction on MSC trilineage differentiation paths and mechanisms using model intracellular pathogen Salmonella enterica ssp enterica serotype Typhimurium. The examination of key markers of differentiation, apoptosis, and immunomodulation demonstrated that Salmonella altered osteogenic and chondrogenic differentiation pathways in human and goat adipose-derived MSCs. Anti-apoptotic and pro-proliferative responses were also significantly upregulated (p < 0.05) in MSCs during Salmonella challenge. These results together indicate that Salmonella, and potentially other pathogenic bacteria, can induce pathways that influence both apoptotic response and functional differentiation trajectories in MSCs, highlighting that microbes have a potentially significant role as influencers of MSC physiology and immune activity.

Perturbation of BRMS1 interactome reveals pathways that impact metastasis

Breast Cancer Metastasis Suppressor 1 (BRMS1) expression is associated with longer patient survival in multiple cancer types. Understanding BRMS1 functionality will provide insights into both mechanism of action and will enhance potential therapeutic development. In this study, we confirmed that the C-terminus of BRMS1 is critical for metastasis suppression and hypothesized that critical protein interactions in this region would explain its function. Phosphorylation status at S237 regulates BRMS1 protein interactions related to a variety of biological processes, phenotypes [cell cycle (e.g., CDKN2A), DNA repair (e.g., BRCA1)], and metastasis [(e.g., TCF2 and POLE2)]. Presence of S237 also directly decreased MDA-MB-231 breast carcinoma migration in vitro and metastases in vivo. The results add significantly to our understanding of how BRMS1 interactions with Sin3/HDAC complexes regulate metastasis and expand insights into BRMS1's molecular role, as they demonstrate BRMS1 C-terminus involvement in distinct protein-protein interactions.

BRMS1: a multifunctional signaling molecule in metastasis

Despite high mortality rates, molecular understanding of metastasis remains limited. It can be regulated by both pro- and anti-metastasis genes. The metastasis suppressor, breast cancer metastasis suppressor 1 (BRMS1), has been positively correlated with patient outcomes, but molecular functions are still being characterized. BRMS1 has been implicated in focal adhesion kinase (FAK), epidermal growth factor receptor (EGFR), and NF-κB signaling pathways. We review evidence that BRMS1 regulates these vast signaling pathways through chromatin remodeling as a member of mSin3 histone deacetylase complexes.

Prognostic value of HLA-I homozygosity in patients with non-small cell lung cancer treated with single agent immunotherapy

BACKGROUND

We aimed to assess the impact of genomic human leukocyte antigen (HLA)-I/II homozygosity on the survival benefit of patients with unresectable locally advanced, metastatic non-small lung cancer treated by single-agent programmed cell death protein-1/programmed death ligand 1 (PD1/PDL1) inhibitors.

METHODS

We collected blood from 170 patients with advanced lung cancer treated with immunotherapy at two major oncology centers in Western Australia. Genomic DNA was extracted from white blood cells and used for HLA-I/II high-resolution typing. HLA-I/II homozygosity was tested for association with survival outcomes. Univariable and multivariable Cox regression models were constructed to determine whether HLA homozygosity was an independent prognostic factor affecting Overall Survival (OS) and Progression Free Survival (PFS). We also investigated the association between individual HLA-A and -B supertypes with OS.

RESULTS

Homozygosity at HLA-I loci, but not HLA-II, was significantly associated with shorter OS (HR=2.17, 95% CI 1.13 to 4.17, p=0.02) in both univariable and multivariable analysis. The effect of HLA-I homozygosity in OS was particularly relevant for patients with tumors expressing PDL1 ≥50% (HR=3.93, 95% CI 1.30 to 11.85, p<0.001). The adverse effect of HLA-I homozygosity on PFS was only apparent after controlling for interactions between PDL1 status and HLA-I genotype (HR=2.21, 95% CI 1.04 to 4.70, p=0.038). The presence of HLA-A02 supertype was the only HLA-I supertype to be associated with improved OS (HR=0.56, 95% CI 0.34 to 0.93, p=0.023).

CONCLUSION

Our results suggest that homozygosity at ≥1 HLA-I loci is associated with short OS and PFS in patients with advanced non-small cell lung cancer with PDL1 ≥50% treated with single-agent immunotherapy. Carriers of HLA-A02 supertype reported better survival outcomes in this cohort of patients.

Impacts of Early Life Stress on the Methylome and Transcriptome of Atlantic Salmon

Exposure to environmental stressors during early-life stages can change the rate and timing of various developmental processes. Epigenetic marks affecting transcriptional regulation can be altered by such environmental stimuli. To assess how stress might affect the methylome and transcriptome in salmon, fish were treated using cold-shock and air-exposure from the eye-stage until start-feeding. The fish were either stressed prior to hatching (E), post-hatching (PH), pre- and post-hatching (EPH) or not stressed (CO). Assessing transcriptional abundances just prior to start feeding, E and PH individuals were found to have modified the expression of thousands of genes, many with important functions in developmental processes. The EPH individuals however, showed expression similar to those of CO, suggesting an adaptive response to extended periods of stress. The methylome of stressed individuals differed from that of the CO, suggesting the importance of environment in shaping methylation signatures. Through integration of methylation with transcription, we identified bases with potential regulatory functions, some 10s of kb away from the targeted genes. We then followed fish growth for an additional year. Individuals in EPH showed superior growth compared to other treatment groups, highlighting how stress can potentially have long-lasting effects on an organism's ability to adapt to environmental perturbations.

Increased HAGLR expression promotes non-small cell lung cancer proliferation and invasion via enhanced de novo lipogenesis

Lung cancers are broadly classified into small cell lung cancer and non-small cell lung cancer, with non-small cell lung cancer one of the leading causes of cancer-associated deaths worldwide. Presently, the mechanisms underlying lung tumorigenesis remain incompletely understood. Accumulating evidence indicates that abnormal expression of long non-coding RNAs is associated with tumorigenesis in multiple cancers, including lung cancer. HAGLR messenger RNA of non-small cell lung cancer tissues was significantly higher. Moreover, high levels of HAGLR expression were associated with non-small cell lung cancer tumor lymph node metastasis status, stage, and poor overall survival. Inhibition of HAGLR in non-small cell lung cancer cells suppressed cell proliferation and invasion. RNA interference-mediated downregulation of HAGLR also decreased levels of fatty acid synthase, with fatty acid synthase levels positively correlated with HAGLR expression in non-small cell lung cancer specimens. In addition, the cellular free fatty acid content of cancer cells was decreased following HAGLR knockdown. HAGLR depletion significantly inhibited the growth of non-small cell lung cancer cells in vivo. Furthermore, the expression levels of p21 and matrix metallopeptidase-9 (MMP-9) were dysregulated when HAGLR expression was suppressed. Our results suggest that HAGLR is an important regulator of non-small cell lung cancer cell proliferation and invasion, perhaps by regulating fatty acid synthase. Therefore, targeting HAGLR may be a possible therapeutic strategy for non-small cell lung cancer.

Gene promoter methylation and protein expression of BRMS1 in uterine cervix in relation to high-risk human papilloma virus infection and cancer

Cervical cancer is strongly related to certain high-risk types of human papilloma virus infection. Breast cancer metastasis suppressor 1 (BRMS1) is a tumor suppressor gene, its expression being regulated by DNA promoter methylation in several types of cancers. This study aims to evaluate the methylation status of BRMS1 promoter in relation to high-risk types of human papilloma virus infection and the development of pre-cancerous lesions and describe the pattern of BRMS1 protein expression in normal, high-risk types of human papilloma virus-infected pre-cancerous and malignant cervical epithelium. We compared the methylation status of BRMS1 in cervical smears of 64 women with no infection by high-risk types of human papilloma virus to 70 women with proven high-risk types of human papilloma virus infection, using real-time methylation-specific polymerase chain reaction. The expression of BRMS1 protein was described by immunohistochemistry in biopsies from cervical cancer, pre-cancerous lesions, and normal cervices. Methylation of BRMS1 promoter was detected in 37.5% of women with no high-risk types of human papilloma virus infection and was less frequent in smears with high-risk types of human papilloma virus (11.4%) and in women with pathological histology (cervical intraepithelial neoplasia) (11.9%). Methylation was detected also in HeLa cervical cancer cells. Immunohistochemistry revealed nuclear BRMS1 protein staining in normal high-risk types of human papilloma virus-free cervix, in cervical intraepithelial neoplasias, and in malignant tissues, where staining was occasionally also cytoplasmic. In cancer, expression was stronger in the more differentiated cancer blasts. In conclusion, BRMS1 promoter methylation and aberrant protein expression seem to be related to high-risk types of human papilloma virus-induced carcinogenesis in uterine cervix and is worthy of further investigation.

Cyclin-dependent kinase-mediated phosphorylation of breast cancer metastasis suppressor 1 (BRMS1) affects cell migration

Expression of Breast Cancer Metastasis Suppressor 1 (BRMS1) reduces the incidence of metastasis in many human cancers, without affecting tumorigenesis. BRMS1 carries out this function through several mechanisms, including regulation of gene expression by binding to the mSin3/histone deacetylase (HDAC) transcriptional repressor complex. In the present study, we show that BRMS1 is a novel substrate of Cyclin-Dependent Kinase 2 (CDK2) that is phosphorylated on serine 237 (S237). Although CDKs are known to regulate cell cycle progression, the mutation of BRMS1 on serine 237 did not affect cell cycle progression and proliferation of MDA-MB-231 breast cancer cells; however, their migration was affected. Phosphorylation of BRMS1 does not affect its association with the mSin3/HDAC transcriptional repressor complex or its transcriptional repressor activity. The serine 237 phosphorylation site is immediately proximal to a C-terminal nuclear localization sequence that plays an important role in BRMS1-mediated metastasis suppression but phosphorylation does not control BRMS1 subcellular localization. Our studies demonstrate that CDK-mediated phosphorylation of BRMS1 regulates the migration of tumor cells.

Salmonella Degrades the Host Glycocalyx Leading to Altered Infection and Glycan Remodeling

Complex glycans cover the gut epithelial surface to protect the cell from the environment. Invasive pathogens must breach the glycan layer before initiating infection. While glycan degradation is crucial for infection, this process is inadequately understood. Salmonella contains 47 glycosyl hydrolases (GHs) that may degrade the glycan. We hypothesized that keystone genes from the entire GH complement of Salmonella are required to degrade glycans to change infection. This study determined that GHs recognize the terminal monosaccharides (N-acetylneuraminic acid (Neu5Ac), galactose, mannose, and fucose) and significantly (p < 0.05) alter infection. During infection, Salmonella used its two GHs sialidase nanH and amylase malS for internalization by targeting different glycan structures. The host glycans were altered during Salmonella association via the induction of N-glycan biosynthesis pathways leading to modification of host glycans by increasing fucosylation and mannose content, while decreasing sialylation. Gene expression analysis indicated that the host cell responded by regulating more than 50 genes resulting in remodeled glycans in response to Salmonella treatment. This study established the glycan structures on colonic epithelial cells, determined that Salmonella required two keystone GHs for internalization, and left remodeled host glycans as a result of infection. These data indicate that microbial GHs are undiscovered virulence factors.

Synthetic tetracycline-controllable shRNA targeting long non-coding RNA HOXD-AS1 inhibits the progression of bladder cancer

BACKGROUND

Long non-coding RNAs (lncRNAs) have been proved to act as key molecules in cancer development and progression. Dysregulation of lncRNAs is discovered in various tumor tissues and cancer cells where they can serve as oncogenes or tumor suppressors. Long non-coding RNA HOXD-AS (HOXD cluster antisense RNA 1) has recently been identified to be involved in the development of several cancers including neuroblastoma, adenocarcinomas and breast cancer. However, the role of HOXD-AS1 in bladder cancer remains unknown.

METHODS

The synthetic tetracycline-controllable shRNA was used to modulate the level of HOXD-AS1 by adding different concentrations of doxycycline (dox). RT-qPCR was used to detect the expression level of HOXD-AS1. Cell proliferation was determined by CCK-8 assay and EdU incorporation experiment when HOXD-AS1 was knocked down. We used wound-healing assay for detecting the effect of HOXD-AS1 on cell migration. Eventually, cell apoptosis was determined by caspase 3 ELISA assay and flow cytometry assay.

RESULTS

In this study, we found that the expression level of HOXD-AS1 was significantly increased in bladder cancer tissues and cells. Furthermore, high expression of HOXD-AS1 was significantly related to tumor size, histological grade and TNM stage. In vitro assays confirmed that knockdown of HOXD-AS1 suppressed cell proliferation/migration and increased the rate of apoptotic cell in bladder cancer cells. At last, we used the important element of synthetic biology, tetracycline(tet)-controllable switch, to construct tet-controllable shRNA vectors which can modulate the expression of HOXD-AS1 in a dosage-dependent manner.

CONCLUSIONS

Our research suggested that high expression of HOXD-AS1 may be involved in the bladder cancer carcinogenesis through inhibiting the phenotypes and activating endogenous cancer-related molecular pathways. Therefore, HOXD-AS1 may act as an oncogene and provide a potential attractive therapeutic target for bladder cancer. In addition, the synthetic tetracycline-controllable shRNA may provide a novel method for cancer research in vitro assays.

Breast Cancer Metastasis Suppressor 1 (BRMS1): Robust Biological and Pathological Data, But Still Enigmatic Mechanism of Action

Metastasis requires coordinated expression of multiple genetic cassettes, often via epigenetic regulation of gene transcription. BRMS1 blocks metastasis, but not orthotopic tumor growth in multiple tumor types, presumably via SIN3 chromatin remodeling complexes. Although there is an abundance of strong data supporting BRMS1 as a metastasis suppressor, the mechanistic data directly connecting molecular pathways with inhibition of particular steps in metastasis are not well defined. In this review, the data for BRMS1-mediated metastasis suppression in multiple tumor types are discussed along with the steps in metastasis that are inhibited.

In vitro biophysical, microspectroscopic and cytotoxic evaluation of metastatic and non-metastatic cancer cells in responses to anti-cancer drug

The Breast Cancer Metastasis Suppressor 1 (BRMS1) is a nucleo-cytoplasmic protein that suppresses cancer metastasis without affecting the growth of the primary tumor. Previous work has shown that it decreases the expression of protein mediators involved in chemoresistance. This study measured the biomechanical and biochemical changes in BRMS1 expression and the responses of BRMS1 to drug treatments on cancer cells in vitro. The results show that BRMS1 expression affects biomechanical properties by decreasing the Young's modulus and adhesion force of breast cancer cells after doxorubicin (DOX) exposure. Raman spectral bands corresponding to DNA/RNA, lipids and proteins were similar for all cells after DOX treatment. The expression of cytokines were similar for cancer cells after DOX exposure, although BRMS1 expression had different effects on the secretion of cytokines for breast cancer cells. The absence of significant changes on apoptosis, reactive oxygen species (ROS) expression and cell viability after BRMS1 expression shows that BRMS1 has little effect on cellular chemoresistance. Analyzing cancer protein expression is critical in evaluating therapeutics. Our study may provide evidence of the benefit of metastatic suppressor expression before chemotherapy.

Simultaneous topographic and recognition imaging of epidermal growth factor receptor (EGFR) on single human breast cancer cells

Epidermal growth factor receptor (EGFR) plays an important role in signaling pathway of the development of breast cancer cells. Since EGFR overexpresses in most breast cancer cells, it is regarded as a biomarker molecule of breast cancer cells. Here we demonstrated a new AFM technique-topography and recognition (TREC) imaging-to simultaneously obtain highly sensitive and specific molecular recognition images and high-resolution topographic images of EGFR on single breast cancer cells.

HOXD-AS1 is a novel lncRNA encoded in HOXD cluster and a marker of neuroblastoma progression revealed via integrative analysis of noncoding transcriptome

Background

Long noncoding RNAs (lncRNAs) constitute a major, but poorly characterized part of human transcriptome. Recent evidence indicates that many lncRNAs are involved in cancer and can be used as predictive and prognostic biomarkers. Significant fraction of lncRNAs is represented on widely used microarray platforms, however they have usually been ignored in cancer studies.

Results

We developed a computational pipeline to annotate lncRNAs on popular Affymetrix U133 microarrays, creating a resource allowing measurement of expression of 1581 lncRNAs. This resource can be utilized to interrogate existing microarray datasets for various lncRNA studies. We found that these lncRNAs fall into three distinct classes according to their statistical distribution by length. Remarkably, these three classes of lncRNAs were co-localized with protein coding genes exhibiting distinct gene ontology groups. This annotation was applied to microarray analysis which identified a 159 lncRNA signature that discriminates between localized and metastatic stages of neuroblastoma. Analysis of an independent patient cohort revealed that this signature differentiates also relapsing from non-relapsing primary tumors. This is the first example of the signature developed via the analysis of expression of lncRNAs solely. One of these lncRNAs, termed HOXD-AS1, is encoded in HOXD cluster. HOXD-AS1 is evolutionary conserved among hominids and has all bona fide features of a gene. Studying retinoid acid (RA) response of SH-SY5Y cell line, a model of human metastatic neuroblastoma, we found that HOXD-AS1 is a subject to morphogenic regulation, is activated by PI3K/Akt pathway and itself is involved in control of RA-induced cell differentiation. Knock-down experiments revealed that HOXD-AS1 controls expression levels of clinically significant protein-coding genes involved in angiogenesis and inflammation, the hallmarks of metastatic cancer.

Conclusions

Our findings greatly extend the number of noncoding RNAs functionally implicated in tumor development and patient treatment and highlight their role as potential prognostic biomarkers of neuroblastomas.

Computational identification of surrogate genes for prostate cancer phases using machine learning and molecular network analysis

BACKGROUND

Prostate cancer is one of the most common malignant diseases and is characterized by heterogeneity in the clinical course. To date, there are no efficient morphologic features or genomic biomarkers that can characterize the phenotypes of the cancer, especially with regard to metastasis--the most adverse outcome. Searching for effective surrogate genes out of large quantities of gene expression data is a key to cancer phenotyping and/or understanding molecular mechanisms underlying prostate cancer development.

RESULTS

Using the maximum relevance minimum redundancy (mRMR) method on microarray data from normal tissues, primary tumors and metastatic tumors, we identifed four genes that can optimally classify samples of different prostate cancer phases. Moreover, we constructed a molecular interaction network with existing bioinformatic resources and co-identifed eight genes on the shortest-paths among the mRMR-identified genes, which are potential co-acting factors of prostate cancer. Functional analyses show that molecular functions involved in cell communication, hormone-receptor mediated signaling, and transcription regulation play important roles in the development of prostate cancer.

CONCLUSION

We conclude that the surrogate genes we have selected compose an effective classifier of prostate cancer phases, which corresponds to a minimum characterization of cancer phenotypes on the molecular level. Along with their molecular interaction partners, it is fairly to assume that these genes may have important roles in prostate cancer development; particularly, the un-reported genes may bring new insights for the understanding of the molecular mechanisms. Thus our results may serve as a candidate gene set for further functional studies.

Metastasis suppression by BRMS1 associated with SIN3 chromatin remodeling complexes

Epigenetic regulation of gene transcription by histone modification and chromatin remodeling has been linked to many biological and pathological events including cancer metastasis. Breast cancer metastasis suppressor 1 (BRMS1) interacts with SIN3 chromatin remodeling complexes, and, upon forced expression in metastatic cells, a nearly complete suppression of metastasis is noted without preventing primary tumor growth. The data for BRMS1-mediated metastasis suppression and SIN3 interaction are clear; however, connecting the inhibition directly to the association of BRMS1 with SIN3 complexes is currently not well defined. Considering the recent advancements in developing epigenetic drugs for cancer therapy, an improved understanding of how the interactions between BRMS1 and SIN3 regulate the process of metastasis should lead to novel therapies specifically targeting the most deadly aspect of tumor progression. In this article, the data for BRMS1-mediated metastasis suppression are reviewed with a focus on how the SIN3 chromatin remodeling complexes may be functionally involved.

The C-terminal putative nuclear localization sequence of breast cancer metastasis suppressor 1, BRMS1, is necessary for metastasis suppression

Breast cancer metastasis suppressor 1 (BRMS1) is a predominantly nuclear protein that suppresses metastasis in multiple human and murine carcinoma cell lines. BRMS1 interacts with several nuclear proteins including SIN3:HDAC chromatin remodeling complexes that are involved in repressing transcription. However, recent reports suggest BRMS1 may function in the cytoplasm. BRMS1 has two predicted nuclear localization sequences (NLS) that are located near the C-terminus (amino acids 198–205 and 238–244, NLS1 and NLS2 respectively). We hypothesized that nuclear localization sequences of BRMS1 were essential for BRMS1 mediated metastasis suppression. Replacement of NLS2 with NLS1 (BRMS1^NLS1,1), truncation at 238 (BRMS1^ΔNLS2), or switching the location of NLS1 and NLS2 (BRMS1^NLS2,1) did not affect nuclear localization; but, replacement of NLS1 with NLS2 (BRMS1^NLS2,2) or truncation at 197 (BRMS1^ΔNLS which removes both NLS) promoted cytoplasmic localization. MDA-MB-231 human metastatic breast cancer cells transduced with BRMS1^NLS1,1, BRMS1^NLS2,2 or BRMS1^NLS2,1 were evaluated for metastasis suppression in an experimental xenograft mouse model. Interestingly, while NLS2 was not necessary for nuclear localization, it was found to be important for metastasis suppression since BRMS1^NLS2,2 suppressed metastasis by 85%. In contrast, BRMS1^NLS2,1 and BRMS1^NLS1,1 did not significantly suppress metastasis. Both BRMS1 and BRMS1^NLS2,2 co-immunoprecipitated with SIN3A in the nucleus and cytoplasm; however, BRMS1^NLS1,1 and BRMS1^NLS2,1 were associated with SIN3A in the nucleus only. Moreover, BRMS1 and BRMS1^NLS2,2, but not BRMS1^NLS1,1 and BRMS1^NLS2,1, down-regulated the pro-metastatic microRNA, miR-10b. Together, these data demonstrate an important role for NLS2 in the cytoplasm that is critical for metastasis suppression and is distinct from nuclear localization.

ST6Gal-I protein expression is upregulated in human epithelial tumors and correlates with stem cell markers in normal tissues and colon cancer cell lines

The ST6Gal-I sialyltransferase adds an α2-6-linked sialic acid to the N-glycans of certain receptors. ST6Gal-I mRNA has been reported to be upregulated in human cancer, but a prior lack of antibodies has limited immunochemical analysis of the ST6Gal-I protein. Here, we show upregulated ST6Gal-I protein in several epithelial cancers, including many colon carcinomas. In normal colon, ST6Gal-I localized selectively to the base of crypts, where stem/progenitor cells are found, and the tissue staining patterns were similar to the established stem cell marker ALDH1. Similarly, ST6Gal-I expression was restricted to basal epidermal layers in skin, another stem/progenitor cell compartment. ST6Gal-I was highly expressed in induced pluripotent stem (iPS) cells, with no detectable expression in the fibroblasts from which iPS cells were derived. On the basis of these observations, we investigated further an association of ST6Gal-I with cancer stem cells (CSC). Selection of irinotecan resistance in colon carcinoma cells led to a greater proportion of CSCs compared with parental cells, as measured by the CSC markers CD133 and ALDH1 activity (Aldefluor). These chemoresistant cells exhibited a corresponding upregulation of ST6Gal-I expression. Conversely, short hairpin RNA (shRNA)-mediated attenuation of ST6Gal-I in colon carcinoma cells with elevated endogenous expression decreased the number of CD133/ALDH1-positive cells present in the cell population. Collectively, our results suggest that ST6Gal-I promotes tumorigenesis and may serve as a regulator of the stem cell phenotype in both normal and cancer cell populations.

Role of breast cancer metastasis suppressor 1 in digestive system neoplasms

Breast cancer metastasis suppressor 1 (BRMS1) is a tumor metastasis suppressor discovered in breast carcinoma cells in 2000. It can reduce the metastasis potential of tumor cells without affecting the growth of orthotopic tumor. BRMS1 is lowly expressed or not at all in metastases of melanoma, bladder carcinoma, pheochromocytoma, ovarian cancer, non-small cell lung cancer, endometrial cancer, nasal and paranasal sinus carcinoma. Malignant tumors have become one of the most serious diseases endangering human health, and digestive system neoplasms are the most common malignant tumors in China. Elucidation of the role of BRMS1 will certainly provide a potential theoretical basis for the molecular diagnosis, targeted therapy, and prognosis evaluation of tumor metastases. In this review, we will summarize recent progress in understanding the role of BRMS1 in digestive system neoplasms.

Breast cancer metastasis suppressor 1 regulates hepatocellular carcinoma cell apoptosis via suppressing osteopontin expression

Breast cancer metastasis suppressor 1 (BRMS1) was originally identified as an active metastasis suppressor in human breast cancer. Loss of BRMS1 expression correlates with tumor progression, and BRMS1 suppresses several steps required for tumor metastasis. However, the role of BRMS1 in hepatocellular carcinoma (HCC) remains elusive. In this study, we found that the expression level of BRMS1 was significantly down-regulated in HCC tissues. Expression of BRMS1 in SK-Hep1 cells did not affect cell growth under normal culture conditions, but sensitized cells to apoptosis induced by serum deprivation or anoikis. Consistently, knockdown of endogenous BRMS1 expression in Hep3B cells suppressed cell apoptosis. We identified that BRMS1 suppresses osteopontin (OPN) expression in HCC cells and that there is a negative correlation between BRMS1 and OPN mRNA expression in HCC tissues. Moreover, knockdown of endogenous OPN expression reversed the anti-apoptosis effect achieved by knockdown of BRMS1. Taken together, our results show that BRMS1 sensitizes HCC cells to apoptosis through suppressing OPN expression, suggesting a potential role of BRMS1 in regulating HCC apoptosis and metastasis.

Recent advances in breast cancer metastasis suppressor 1

Metastasis is a complex process divided into a number of steps including detachment of tumor cells from the primary tumor, invasion, migration, intravasation, survival in the vasculature, extravasation, and colonization of the secondary site. Proteins that block metastasis without inhibiting primary tumor formation are known as metastasis suppressors; examples are NM23, Maspin, KAI1, KISS1, and MKK4. Breast cancer metastasis suppressor 1 (BRMS1) was identified as a suppressor of breast cancer metastasis in the late 1990s. In vitro and in vivo studies have confirmed that BRMS1 is a potent metastasis suppressor not limited to breast cancer. However, conflicting clinical observations regarding its role as a metastasis suppressor and its validity as a diagnostic biomarker warrant more in-depth clinical study. In this review, the authors provide an overview of its biology, function, action mechanism and pathological significance.

Unraveling the enigmatic complexities of BRMS1-mediated metastasis suppression

Expression of BRMS1 causes dramatic suppression of metastasis in multiple in vivo model systems. As we gain further insight into the biochemical mechanisms of BRMS1, we appreciate the importance of both molecular and cellular context for functional metastasis suppression. BRMS1 associates with large chromatin remodeling complexes including SIN3:HDAC which are powerful epigenetic regulators of gene expression. Additionally, BRMS1 inhibits the activity of NFκB, a well-known transcription factor that plays significant roles in tumor progression. Moreover, BRMS1 coordinately regulates the expression of metastasis-associated microRNA known as metastamir. How these biochemical mechanisms and biological pathways are linked, either directly or indirectly, and the influence of molecular and cellular context, are critical considerations for the discovery of novel therapeutic targets for the most deadly aspect of tumor progression-metastasis.

Metastasis suppressor genes at the interface between the environment and tumor cell growth

The molecular mechanisms and genetic programs required for cancer metastasis are sometimes overlapping, but components are clearly distinct from those promoting growth of a primary tumor. Every sequential, rate-limiting step in the sequence of events leading to metastasis requires coordinated expression of multiple genes, necessary signaling events, and favorable environmental conditions or the ability to escape negative selection pressures. Metastasis suppressors are molecules that inhibit the process of metastasis without preventing growth of the primary tumor. The cellular processes regulated by metastasis suppressors are diverse and function at every step in the metastatic cascade. As we gain knowledge into the molecular mechanisms of metastasis suppressors and cofactors with which they interact, we learn more about the process, including appreciation that some are potential targets for therapy of metastasis, the most lethal aspect of cancer. Until now, metastasis suppressors have been described largely by their function. With greater appreciation of their biochemical mechanisms of action, the importance of context is increasingly recognized especially since tumor cells exist in myriad microenvironments. In this chapter, we assemble the evidence that selected molecules are indeed suppressors of metastasis, collate the data defining the biochemical mechanisms of action, and glean insights regarding how metastasis suppressors regulate tumor cell communication to-from microenvironments.

Sorting nexin 6 interacts with breast cancer metastasis suppressor-1 and promotes transcriptional repression

Sorting nexin 6 (SNX6), a predominantly cytoplasmic protein involved in intracellular trafficking of membrane receptors, was identified as a TGF-β family interactor. However, apart from being a component of the Retromer, little is known about SNX6 cellular functions. Pim-1-dependent SNX6 nuclear translocation has been reported suggesting a putative nuclear role for SNX6. Here, we describe a previously non-reported association of SNX6 with breast cancer metastasis suppressor 1 (BRMS1) protein detected by a yeast two-hybrid screening. The interaction can be reconstituted in vitro and further FRET analysis confirmed the novel interaction. Additionally, we identified their coiled-coil domains as the minimal binding motives required for interaction. Since BRMS1 has been shown to repress transcription, we sought the ability of SNX6 to interfere with this nuclear activity. Using a standard gene reporter assay, we observed that SNX6 increases BRMS1-dependent transcriptional repression. Moreover, over-expression of SNX6 was capable of diminishing trans-activation in a dose-dependent manner.

Protein Signatures in Human MDA-MB-231 Breast Cancer Cells Indicating a More Invasive Phenotype Following Knockdown of Human Endometase/Matrilysin-2 by siRNA

Human matrix metalloproteinase-26 (MMP-26/endometase/matrilysin-2) is a putative biomarker for carcinomas of breast, prostate, and other cancers of epithelial origin. MMP-26 expression was silenced using small interfering RNA (siRNA) in the human breast cancer cell line MDA-MB-231. Immunological and proteomics approaches, including two-dimensional gel electrophoresis and matrix assisted laser desorption/ionization time-of-flight mass spectrometry, were employed to identify differential protein expression in MMP-26 knockdown cells. A comparison of the protein expression profiles of control and MMP-26 knockdown cells revealed nine differentially regulated proteins. Five of the proteins (heat shock protein 90, glucose-regulated protein 78 (GRP78), annexin V, tropomyosin, and peroxiredoxin II) were up-regulated, while alpha-tubulin, cystatin SA-III, breast cancer metastasis suppressor 1 (BRMS1) and beta-actin were down-regulated. This decrease of BRMS1 expression is concomitant with an increase of invasion through matrix-coated membranes. These results suggest an important role for MMP-26 in the regulation of proteins involved in invasive and metastatic breast cancers.

Metastasis suppressors and the tumor microenvironment

The most lethal and debilitating attribute of cancer cells is their ability to metastasize. Throughout the process of metastasis, tumor cells interact with other tumor cells, host cells and a variety of molecules. Tumor cells are also faced with a number of insults, such as hemodynamic sheer pressure and immune selection. This brief review explores how metastasis suppressor proteins regulate interactions between tumor cells and the microenvironments in which tumor cells find themselves.

Integrated gene networks in breast cancer development

Breast cancer is a complex and heterogenous disease. Classical molecular medical approaches cannot fully understand and comprehend its pathogenesis. In this review, the development of new biological markers for the early detection and creation of guided and specific therapy of breast cancer are discussed in light of the rapid advances in the "omics". Results of cancer research in combination with large-scale methods that examine the expression status of genes and proteins have identified a large number of new biomarkers as well as confirmed the human growth hormone as an important player in the pathogenesis of this disease through its autocrine regulation where it influences the activation of Pax5 and HOXA1 gene networks.

BRMS1 expression alters the ultrastructural, biomechanical and biochemical properties of MDA-MB-435 human breast carcinoma cells: an AFM and Raman microspectroscopy study

Restoring BReast cancer Metastasis Suppressor 1 (BRMS1) expression suppresses metastasis in MDA-MB-435 human breast carcinoma cells at ectopic sites without affecting tumor formation at orthotopic site in the body. BRMS1 expression induces many phenotypic alterations in 435 cells such as cell adhesion, cytoskeleton rearrangement, and the down regulation of epidermal growth factor receptor (EGFR) expression. In order to better understand the role of cellular biomechanics in breast cancer metastasis, the qualitative and quantitative detection of cellular biomechanics and biochemical composition is urgently needed. In the present work, using atomic force microscopy (AFM) and fluorescent microscopy we revealed that BRMS1 expression in 435 cells induced reorganization of F-actin and caused alteration in cytoarchitectures (cell topography and ultrastructure). Results from AFM observed increase in biomechanical properties which include cell adhesion, cellular spring constant, and Young's modulus in 435/BRMS1 cells. Raman microspectroscopy showed weaker vibrational spectroscopic bands in 435/BRMS1 cells, implying decrease in concentration of cellular biochemical components in these cells. This was despite the similar spectral patterns observed between 435 and 435/BRMS1 cells. This work demonstrated the feasibility of applying AFM and Raman techniques for in situ measurements of the cellular biomechanics and biochemical components of breast carcinoma cells. It provides vital clues in understanding of the role of cellular biomechanics in cancer metastasis, and further the development of new techniques for early diagnosis of breast cancer.

Linking metastasis suppression with metastamiR regulation

Cancer metastasis requires the coordinate expression of multiple genes during every step of the metastatic cascade. Molecules that regulate these genetic programs have the potential to impact metastasis at multiple levels. Breast cancer metastasis suppressor 1 (BRMS1) suppresses metastasis by inhibiting multiple steps in the cascade through regulation of many protein-encoding, metastasis-associated genes as well as metastasis-regulatory microRNA, termed metastamiR. In this Feature , we will highlight connections between BRMS1 biology and regulation of metastamiR.

Tissue-specific remodeling of the mitochondrial proteome in type 1 diabetic akita mice

OBJECTIVE

To elucidate the molecular basis for mitochondrial dysfunction, which has been implicated in the pathogenesis of diabetes complications.

RESEARCH DESIGN AND METHODS

Mitochondrial matrix and membrane fractions were generated from liver, brain, heart, and kidney of wild-type and type 1 diabetic Akita mice. Comparative proteomics was performed using label-free proteome expression analysis. Mitochondrial state 3 respirations and ATP synthesis were measured, and mitochondrial morphology was evaluated by electron microscopy. Expression of genes that regulate mitochondrial biogenesis, substrate utilization, and oxidative phosphorylation (OXPHOS) were determined.

RESULTS

In diabetic mice, fatty acid oxidation (FAO) proteins were less abundant in liver mitochondria, whereas FAO protein content was induced in mitochondria from all other tissues. Kidney mitochondria showed coordinate induction of tricarboxylic acid (TCA) cycle enzymes, whereas TCA cycle proteins were repressed in cardiac mitochondria. Levels of OXPHOS subunits were coordinately increased in liver mitochondria, whereas mitochondria of other tissues were unaffected. Mitochondrial respiration, ATP synthesis, and morphology were unaffected in liver and kidney mitochondria. In contrast, state 3 respirations, ATP synthesis, and mitochondrial cristae density were decreased in cardiac mitochondria and were accompanied by coordinate repression of OXPHOS and peroxisome proliferator-activated receptor (PPAR)-gamma coactivator (PGC)-1alpha transcripts.

CONCLUSIONS

Type 1 diabetes causes tissue-specific remodeling of the mitochondrial proteome. Preservation of mitochondrial function in kidney, brain, and liver, versus mitochondrial dysfunction in the heart, supports a central role for mitochondrial dysfunction in diabetic cardiomyopathy.

A shift from nuclear to cytoplasmic breast cancer metastasis suppressor 1 expression is associated with highly proliferative estrogen receptor-negative breast cancers

BACKGROUND/AIMS

To determine breast cancer metastasis suppressor 1 (BRMS1) expression in breast cancers and the efficacy of BRMS1 as a prognostic indicator, BRMS1 expression was assessed in two sets of breast cancer tissues.

METHODS

Epithelial cells from 36 frozen samples of breast cancers and corresponding normal breast were collected by laser capture microdissection and assessed for BRMS1 by quantitative RT-PCR and immunohistochemistry. BRMS1 was also evaluated by immunohistochemistry in a tissue microarray of 209 breast cancers and correlated with indicators of prognosis [estrogen receptor (ER), progesterone receptor (PR), ErbB2, p53, p27(Kip1), Bcl2 and Ki-67].

RESULTS

BRMS1 mRNA and protein were higher in 94 and 81%, respectively, of breast cancers than in corresponding normal epithelium. BRMS1 localization was predominantly nuclear, but 60-70% of cancers also exhibited cytoplasmic immunostaining. Breast cancers with lower nuclear than cytoplasmic BRMS1 (nuclear score - cytoplasmic score < or =0; 11% of cancers) had lower ER, lower PR and higher Ki-67 expression. There was also a trend toward poorer overall survival in this group of cancers, but this was only of borderline significance (p = 0.073). In Cox proportional hazards models, loss of nuclear BRMS1 was not a significant predictor of overall survival.

CONCLUSIONS

Loss of nuclear BRMS1 was associated with ER-negative cancers and a high rate of proliferation, but was not an independent indicator of prognosis.

Expression of the Breast Cancer Metastasis Suppressor 1 (BRMS1) maintains in vitro chemosensitivity of breast cancer cells

The Breast Cancer Metastasis Suppressor 1 (BRMS1) belongs to an expanding category of proteins called metastasis suppressors that demonstrate in vivo metastasis suppression while still allowing growth of the orthotopic tumor. Since BRMS1 decreases either the expression or function of multiple mediators implicated in resistance to chemotherapy (NF-kappaB, AKT, EGFR), we asked whether breast carcinoma cells expressing BRMS1 could be sensitized upon exposure to commonly used therapeutic agents that inhibit some of these same cellular mediators as BRMS1. In this report, we demonstrate that chemosensitivity of breast cancer cells is preserved in the presence of BRMS1. Further, BRMS1 does not change expression of AKT isoforms or PTEN, implicated in chemoresistance to common drug agents. Overall, our data with two different metastatic breast cancer cell lines indicates that BRMS1 expression status may not interfere with the response to commonly used chemotherapeutic agents in the management of solid tumors such as breast cancer. Since tumor protein expression analysis increasingly guides therapy decisions, our data may be of clinical benefit in disease management including profiling for BRMS1 expression before start of therapy.

Breast cancer metastasis suppressor 1 up-regulates miR-146, which suppresses breast cancer metastasis

Breast cancer metastasis suppressor 1 (BRMS1) is a predominantly nuclear protein that differentially regulates expression of multiple genes, leading to suppression of metastasis without blocking orthotopic tumor growth in multiple human and murine cancer cells of diverse origins. We hypothesized that miR-146 may be involved in the ability of BRMS1 to supress metastasis because miR-146 expression is altered by BRMS1 and because BRMS1 and miR-146 are both associated with decreased signaling through the nuclear factor-kappaB pathway. BRMS1 significantly up-regulates miR-146a by 6- to 60-fold in metastatic MDA-MB-231 and MDA-MB-435 cells, respectively, and miR-146b by 40-fold in MDA-MB-435 as measured by real-time quantitative reverse transcription-PCR. Transduction of miR-146a or miR-146b into MDA-MB-231 down-regulated expression of epidermal growth factor receptor, inhibited invasion and migration in vitro, and suppressed experimental lung metastasis by 69% and 84%, respectively (mean +/- SE: empty vector = 39 +/- 6, miR-146a = 12 +/- 1, miR-146b = 6 +/- 1). These results further support the recent notion that modulating the levels of miR-146a or miR-146b could have a therapeutic potential to suppress breast cancer metastasis.

The HLA genomic loci map: expression, interaction, diversity and disease

The human leukocyte antigen (HLA) super-locus is a genomic region in the chromosomal position 6p21 that encodes the six classical transplantation HLA genes and at least 132 protein coding genes that have important roles in the regulation of the immune system as well as some other fundamental molecular and cellular processes. This small segment of the human genome has been associated with more than 100 different diseases, including common diseases, such as diabetes, rheumatoid arthritis, psoriasis, asthma and various other autoimmune disorders. The first complete and continuous HLA 3.6 Mb genomic sequence was reported in 1999 with the annotation of 224 gene loci, including coding and non-coding genes that were reviewed extensively in 2004. In this review, we present (1) an updated list of all the HLA gene symbols, gene names, expression status, Online Mendelian Inheritance in Man (OMIM) numbers, including new genes, and latest changes to gene names and symbols, (2) a regional analysis of the extended class I, class I, class III, class II and extended class II subregions, (3) a summary of the interspersed repeats (retrotransposons and transposons), (4) examples of the sequence diversity between different HLA haplotypes, (5) intra- and extra-HLA gene interactions and (6) some of the HLA gene expression profiles and HLA genes associated with autoimmune and infectious diseases. Overall, the degrees and types of HLA super-locus coordinated gene expression profiles and gene variations have yet to be fully elucidated, integrated and defined for the processes involved with normal cellular and tissue physiology, inflammatory and immune responses, and autoimmune and infectious diseases.

Over-expression of the BRMS1 family member SUDS3 does not suppress metastasis of human cancer cells

BRMS1 and SUDS3 are related members of SIN3-HDAC chromatin remodeling complexes. We hypothesized that they might have overlapping functions and that SUDS3 over-expression could compensate for BRMS1 deficiency. SUDS3 expression was ubiquitous in seven breast cell lines, regardless of metastatic potential. SUDS3 over-expression in BRMS1-non-expressing metastatic cells did not suppress metastasis, motility, osteopontin secretion, or EGF receptor expression, phenotypes associated with BRMS1-mediated metastasis suppression. This study demonstrates functional differences for BRMS1 family members and highlights how the composition of SIN3-HDAC (BRMS1/SUDS3) complexes uniquely affects protein expression and biological behaviors.

Multiple forms of BRMS1 are differentially expressed in the MCF10 isogenic breast cancer progression model

Clinical studies evaluating the mRNA expression level of the BRMS1 metastasis suppressor in the progression of breast cancer have not been consistent. The purpose of this study was to characterize endogenous BRMS1 mRNA and protein in a model of the progression of breast cancer. BRMS1 protein expression was evaluated in the genetically related MCF10 cell lines representing 'normal' breast epithelial cells (MCF10A), pre-malignant breast disease (MCF10AT), comedo ductal carcinoma in situ (MCF10DCIS.com), and metastatic carcinoma (MCF10CAa.1 and MCF10CAd.1alpha) with two antibodies that recognize distinct epitopes in the BRMS1 protein. Nuclear expression of the characteristic *35 kDa BRMS1 protein was detected in all cell lines. Because BRMS1 was expressed in the metastatic MCF10 variants, the BRMS1 exons were sequenced to scan for possible genetic mutations. BRMS1 was wild-type with the exception of a synonymous T/C transition in exon 7. However, alternatively spliced variants were detected by RT-PCR. Two variants, BRMS1.v2 and BRMS1.v4 were only detected in the MCF10A and AT cell lines, while BRMS1 and BRMS1.v3 were detected in all lines. These results demonstrate that expression of the characteristic *35 kDa BRMS1 protein is not sufficient to prevent metastasis. The differential expression of alternative splice variants suggests caution should be taken when evaluating BRMS1 mRNA in clinical samples.

Epigenetic silencing contributes to the loss of BRMS1 expression in breast cancer

Breast Cancer Metastasis Suppressor 1 (BRMS1) suppresses metastasis of human breast cancer, ovarian cancer and melanoma in athymic mice. Studies have also shown that BRMS1 is significantly downregulated in some breast tumors, especially in metastatic disease. However, the mechanisms which regulate BRMS1 expression are currently unknown. Upon examination of the BRMS1 promoter region by methylation specific PCR (MSP) analysis, we discovered a CpG island (-3477 to -2214), which was found to be hypermethylated across breast cancer cell lines. A panel of 20 patient samples analyzed showed that 45% of the primary tumors and 60% of the matched lymph node metastases, displayed hypermethylation of BRMS1 promoter. Furthermore, we found a direct correlation between the methylation status of the BRMS1 promoter in the DNA isolated from tissues, with the loss of BRMS1 expression assessed by immunohistochemistry. There are several studies investigating the mechanism by which BRMS1 suppresses metastasis; however thus far there is no study that reports the cause(s) of loss of BRMS1 expression in aggressive breast cancer. Here we report for the first time that BRMS1 is a novel target of epigenetic silencing; and aberrant methylation in the BRMS1 promoter may serve as a cause of loss of its expression.

Alterations of BRMS1-ARID4A interaction modify gene expression but still suppress metastasis in human breast cancer cells

The BRMS1 metastasis suppressor interacts with the protein AT-rich interactive domain 4A (ARID4A, RBBP1) as part of SIN3.histone deacetylase chromatin remodeling complexes. These transcriptional co-repressors regulate diverse cell phenotypes depending upon complex composition. To define BRMS1 complexes and their roles in metastasis suppression, we generated BRMS1 mutants (BRMS1(mut)) and mapped ARID4A interactions. BRMS1(L174D) disrupted direct interaction with ARID4A in yeast two-hybrid genetic screens but retained an indirect association with ARID4A in MDA-MB-231 and -435 human breast cancer cell lines by co-immunoprecipitation. Deletion of the first coiled-coil domain (BRMS1(DeltaCC1)) did not disrupt direct interaction in yeast two-hybrid screens but did prevent association by co-immunoprecipitation. These results suggest altered complex composition with BRMS1(mut). Although basal transcription repression was impaired and the pro-metastatic protein osteopontin was differentially down-regulated by BRMS1(L174D) and BRMS1(DeltaCC1), both down-regulated the epidermal growth factor receptor and suppressed metastasis in MDA-MB-231 and -435 breast cancer xenograft models. We conclude that BRMS1(mut), which modifies the composition of a SIN3.histone deacetylase chromatin remodeling complex, leads to altered gene expression profiles. Because metastasis requires the coordinate expression of multiple genes, down-regulation of at least one important gene, such as the epidermal growth factor receptor, had the ability to suppress metastasis. Understanding which interactions are necessary for particular biochemical/cellular functions may prove important for future strategies targeting metastasis.

Metastasis suppressors and the tumor microenvironment

The most dangerous attribute of cancer cells is their ability to metastasize. Throughout the process of metastasis, tumor cells interact with other tumor cells, host cells and extracellular molecules. This brief review explores how a new class of molecules – metastasis suppressors – regulate tumor cell–microenvironmental interactions. Data are presented which demonstrate that metastasis suppressors act at multiple steps of the metastatic cascade. A brief discussion for how metastasis suppressor regulation of cellular interactions might be exploited is presented.