Breast carcinoma metastasis suppressor gene 1 (BRMS1): update on its role as the suppressor of cancer metastases

Exploring the prognostic value of BRMS1 + microglia based on single-cell anoikis regulator patterns in the immunologic microenvironment of GBM

BACKGROUND

Anoikis is a specialized form of programmed cell death induced by the loss of cell adhesion to the extracellular matrix (ECM). Acquisition of anoikis resistance is a significant marker for cancer cell invasion, metastasis, therapy resistance, and recurrence. Although current research has identified multiple factors that regulate anoikis resistance, the pathological mechanisms of anoikis-mediated tumor microenvironment (TME) in glioblastoma (GBM) remain largely unexplored.

METHODS

Utilizing single-cell RNA sequencing (scRNA-seq) data and employing non-negative matrix factorization (NMF), we identified and characterized TME cell clusters with distinct anoikis-associated gene signatures. Prognostic and therapeutic response analyses were conducted using TCGA and CGGA datasets to assess the clinical significance of different TME cell clusters. The spatial relationship between BRMS1 + microglia and tumor cells was inferred from spatial transcriptome RNA sequencing (stRNA-seq) data. To simulate the tumor immune microenvironment, co-culture experiments were performed with microglia (HMC3) and GBM cells (U118/U251), and microglia were transfected with a BRMS1 overexpression lentivirus. Western blot or ELISA were used to detect BRMS1, M2 macrophage-specific markers, PI3K/AKT signaling proteins, and apoptosis-related proteins. The proliferation and apoptosis capabilities of tumor cells were evaluated using CCK-8, colony formation, and apoptosis assays, while the invasive and migratory abilities of tumor cells were assessed using Transwell assays.

RESULTS

NMF-based analysis successfully identified CD8 + T cell and microglia cell clusters with distinct gene signature characteristics. Trajectory analysis, cell communication, and gene regulatory network analyses collectively indicated that anoikis-mediated TME cell clusters can influence tumor cell development through various mechanisms. Notably, BRMS1 + AP-Mic exhibited an M2 macrophage phenotype and had significant cell communication with malignant cells. Moreover, high expression of BRMS1 + AP-Mic in TCGA and CGGA datasets was associated with poorer survival outcomes, indicating its detrimental impact on immunotherapy. Upregulation of BRMS1 in microglia may lead to M2 macrophage polarization, activate the PI3K/AKT signaling pathway through SPP1/CD44-mediated cell interactions, inhibit tumor cell apoptosis, and promote tumor proliferation and invasion.

CONCLUSION

This pioneering study used NMF-based analysis to reveal the important predictive value of anoikis-regulated TME in GBM for prognosis and immunotherapeutic response. BRMS1 + microglial cells provide a new perspective for a deeper understanding of the immunosuppressive microenvironment of GBM and could serve as a potential therapeutic target in the future.

Distinct expression and function of breast cancer metastasis suppressor 1 in mutant P53 glioblastoma

PURPOSE

Glioblastoma (GBM) is the most malignant subtype of astrocytic tumors with the worst prognosis in all its progressive forms. Breast cancer metastasis suppressor 1 (BRMS1) is a metastasis suppressor gene that controls malignancy in multiple tumors. As yet, however, its clinical and functional significance in mutant P53 GBM remains inconclusive. Here, we attempted to study the importance of BRMS1 in mutant P53 GBM.

METHODS

BRMS1 expression was evaluated in 74 human astrocytoma tissues by qRT-PCR, Western blotting and immunohistochemistry. BRMS1 expression in the astrocytoma tissues was correlated with clinicopathological parameters, the P53 mutation status and BRMS1 downstream targets, and compared with TCGA and NCI-60 datasets. siRNA-mediated knockdown of BRMS1 was performed in selected GBM cell lines to evaluate the functional role of BRMS1.

RESULTS

Our study revealed an enhanced expression of BRMS1 in GBM which was associated with a poor patient survival, and this observation was corroborated by the TCGA dataset. We also found a positive correlation between BRMS1 expression and a mutant P53 status in GBM which was associated with a poor prognosis. In vitro BRMS1 silencing reduced the growth of mutant P53 GBM cells and repressed their colonization and migration/invasion by modulating EGFR-AKT/NF-κB signaling. Transcriptional profiling revealed a positive and negative correlation of uPA and ING4 expression with BRMS1 expression, respectively.

CONCLUSION

Our data indicate upregulation of BRMS1 in high grade astrocytomas which correlates positively with mutant P53 and a poor patient survival. Silencing of BRMS1 in mutant P53 GBM cell lines resulted in a reduced cellular growth and migration/invasion by suppressing the EGFR-AKT/NF-kB signaling pathway. BRMS1 may serve as a predictive biomarker and therapeutic target in mutant P53 GBM.

Metastasis Inhibition by Cell Type Specific Expression of BRMS1 Gene under The Regulation of miR200 Family Response Elements

Objective

Specific expression of therapeutic genes in cancer therapy has been per used for many years. One of the innovative strategies that have recently been introduced is employing miRNA response elements (MREs) of microRNAs (whose expression are reduced or inhibited in cancerous cells) into the 3´UTR of the therapeutic genes for their specific expression. Accordingly, MREs of anti-metastatic miRNA family have been used in 3´UTR of the metastasis suppressor gene in the corresponding cells to evaluate the level of metastatic behavior.

Material and Methods

In this experimental study, 3´UTR of the ZEB1 gene with 592 bp length, encompassing multiple MREs of miR-141, miR-429, miR-200b and miR-200c, was employed to replace BRMS1 3´UTR. The obtained vector was then assessed in the context of MCF-10A, MDA-MB231 and MCF-7 cells.

Results

It was shown that the employed MREs are able to up-regulate BRMS expression in the metastatic MDA- MB231 cells (almost 3.5-fold increase), while it was significantly reduced within tumorigenic/non-metastatic MCF-7 cells. Specific expression of BRMS1 in metastatic cells led to a significant reduction in their migratory and invasive characteristics (about 65% and 55%, respectively). Two-tailed student’s t test was utilized for statistical analysis.

Conclusion

It was demonstrated that a chimeric vector containing BRMS1 which is regulated by miR-200 family response element may represent a promising therapeutic tool. This is due to the capability of the chimeric vector for cell type-specific expression of anti-metastatic genes with lowest side-effects. It consequently prohibits the invasive characteristics of metastatic cells.

Oncogenic TRIM37 Links Chemoresistance and Metastatic Fate in Triple-Negative Breast Cancer

The majority of clinical deaths in patients with triple-negative breast cancer (TNBC) are due to chemoresistance and aggressive metastases, with high prevalence in younger women of African ethnicity. Although tumorigenic drivers are numerous and varied, the drivers of metastatic transition remain largely unknown. Here, we uncovered a molecular dependence of TNBC tumors on the TRIM37 network, which enables tumor cells to resist chemotherapeutic as well as metastatic stress. TRIM37-directed histone H2A monoubiquitination enforces changes in DNA repair that rendered TP53-mutant TNBC cells resistant to chemotherapy. Chemotherapeutic drugs triggered a positive feedback loop via ATM/E2F1/STAT signaling, amplifying the TRIM37 network in chemoresistant cancer cells. High expression of TRIM37 induced transcriptomic changes characteristic of a metastatic phenotype, and inhibition of TRIM37 substantially reduced the in vivo propensity of TNBC cells. Selective delivery of TRIM37-specific antisense oligonucleotides using antifolate receptor 1-conjugated nanoparticles in combination with chemotherapy suppressed lung metastasis in spontaneous metastatic murine models. Collectively, these findings establish TRIM37 as a clinically relevant target with opportunities for therapeutic intervention. SIGNIFICANCE: TRIM37 drives aggressive TNBC biology by promoting resistance to chemotherapy and inducing a prometastatic transcriptional program; inhibition of TRIM37 increases chemotherapy efficacy and reduces metastasis risk in patients with TNBC.

Anti-tumor peptide SA12 inhibits metastasis of MDA-MB-231 and MCF-7 breast cancer cells via increasing expression of the tumor metastasis suppressor genes, CDH1, nm23-H1 and BRMS1

In recent years, there has been progress in the treatment of breast cancer; however, the prognosis is still poor due to recurrence and metastasis following conventional treatment. The anti-tumor peptide SA12 has been demonstrated to inhibit proliferation and arrest the cell cycle in MDA-MB-231 and MCF-7 breast cancer cells. In the present study, whether SA12 was able to inhibit the metastasis of breast cancer cells was investigated. Wound healing and Transwell assays were used to investigate the inhibition of SA12 on cell migration while, reverse transcription-quantitative PCR and western blot assays were used to identify the mechanism of action behind the effects of SA12 on cell migration. Results from the wound healing and Transwell assays revealed that SA12 significantly inhibited the migration of MDA-MB-231 and MCF-7 breast cancer cells following treatment with 100 µM SA12. Compared with that in the controls, the mRNA expression levels of cadherin 1 (CDH1), non-metastasis 23-H1 (nm23-H1) and breast cancer metastasis suppressor 1 (BRMS1) were increased in MDA-MB-231 and MCF-7 cells following treatment with 100 µM SA12. Furthermore, the protein expression levels of E-cadherin, NM23A and BRMS1 were also increased in MDA-MB-231 cells and MCF-7 cells following treatment with 100 µM SA12. In conclusion, SA12 inhibited the migration of MDA-MB-231 and MCF-7 breast cancer cells and enhanced the expression of the tumor metastasis suppressor genes, CDH1, nm23-H1 and BRMS1, which may be responsible for the SA12-induced inhibition of breast cancer cell metastasis.

Epigenetics mechanisms mediate the miR-125a/BRMS1 axis to regulate invasion and metastasis in gastric cancer

Purpose

Altered expression of breast cancer metastasis suppressor 1 (BRMS1), is a tumor suppressor, which is found in many types of cancers, including gastric cancer (GC), but the mechanism by which BRMS1 inhibits invasion and metastasis in GC is unknown. The aim of the study was to investigate the molecular mechanisms of miR-125a/BRMS1 in GC.

Materials and methods

The expression of BRMS1 and miR-125a were detected by quantitative real-time PCR (qRT-PCR) and analyzed by bioinformatics. BSP and MSP were used to detecte the methylation status of miR-125a and BRMS1 which was treated by 5-Aza or not. Western Blot and qRT-PCR were used to analyze the expression of BRMS1 and EZH2. Transwell was performed to explore the invasion and metastasis ability of GC cells. The nude mice were used for the tumor formation assay.

Results

BRMS1 may be regulated by copy number variation (CNV), methylation and miR-125a-5p. As one of the essential components of PRC2, EZH2 is an important regulatory factor resulting in the low expression of miR-125a. An epigenetic mechanism mediates the miR-125a/BRMS1 axis to inhibit the invasion and metastasis of GC cells. In vivo experiments, it is also showed that BRMS1 is involved in invasion and metastasis but not the proliferation in GC.

Conclusion

These studies shed light on the mechanism of BRMS1 inhibition of GC invasion and metastasis and the development of new drugs targeting the miR-125a/BRMS1 axis, which will be a promising therapeutic strategy for GC and other human cancers.

BRMS1 downregulation is a poor prognostic biomarker in anaplastic thyroid carcinoma patients

Background

Anaplastic thyroid carcinoma (ATC) is the most aggressive cancer in humans with no optimal treatment strategy available. The molecular mechanisms of ATC remain unclear. The aim of this study was to investigate the prognostic value and role of BRMS1 in the progression of ATC.

Methods

BRMS1 expression was examined in thyroid cell lines using Western blot analysis. Immunohistochemistry was also performed to assess BRMS1 expression in ATC and papillary thyroid cancer (PTC) tissue. Cell proliferation assays, colony formation analysis, cell migration assays, cell apoptosis analysis, and animal studies were used to examine the effects of BRMS1 expression on ATC progression.

Results

The expression of BRMS1 was significantly lower in ATC than in PTC and was associated with poor prognosis in ATC patients. Downregulation of BRMS1 expression promoted the proliferation and migration of 8505C cells and decreased their expression of CX43. Over-expressed BRMS1 promoted the apoptosis and impaired the proliferation and migration of CAL-62 cells via upregulated CX43. In vivo, BRMS1 significantly promoted apoptosis and impaired cell proliferation.

Conclusion

Taken together, these findings demonstrate that decreased expression of BRMS1 is a poor prognostic biomarker in ATC patients. BRMS1 significantly promoted apoptosis and impaired cell proliferation via CX43 and P53. Loss of BRMS1 expression is therefore, one of the key pathomechanisms in ATC.

Additive effect of metastamiR-193b and breast cancer metastasis suppressor 1 as an anti-metastatic strategy

BACKGROUND

It has been reported that enhancing the cellular levels of miR-193b as well as breast cancer-metastasis-suppressor-1 (BRMS1) protein is associated with diminished metastatic characteristics in breast cancer. In view of these facts, as a new therapeutic intervention, we employed a restoration-based strategy using both miR-193b-3p mimic and optimized BRMS1 in the context of a chimeric construct.

METHODS

miR-193b-3p and BRMS1 genes were cloned and the resulting plasmids were transfected into the MDA-MB231, MCF-7 and MCF-10A cell lines. microRNA expression levels were assessed by rea time PCR using LNA-primer and protein expression was confirmed by western blot method. Then, apoptosis, MTT, colony formation and invasion assays were carried out.

RESULTS

The expression levels of miR-146a, miR-146b and miR-373 were up-regulated, while the miR-520c, miR-335 and miR-10b were down-regulated following the exogenous BRMS1 expression. The exogenous over-expression of BRMS1 was associated with higher amounts of endogenous miR-193b-3p expression and enabled more efficient targeting of the 3'UTR of uPA. Although, miR-193b-3p and BRMS1 are individually capable of suppressing breast cancer cell growth, migration and invasion abilities, their cistronic expression was capable of enhancing the ability to repress the breast cancer cells invasion.

CONCLUSIONS

Our results collectively indicated the existence of an additive anti-metastatic effect between miR-193b-3p and BRMS1. Moreover, it has been hypothesized that the exogenous expression of a protein can effect endogenous expression of non-relevant microRNA. Our findings provide new grounds for miR-restoration therapy applications as an amenable anti-metastatic strategy.

Cell motility in cancer invasion and metastasis: insights from simple model organisms

Metastasis remains the greatest challenge in the clinical management of cancer. Cell motility is a fundamental and ancient cellular behaviour that contributes to metastasis and is conserved in simple organisms. In this Review, we evaluate insights relevant to human cancer that are derived from the study of cell motility in non-mammalian model organisms. Dictyostelium discoideum, Caenorhabditis elegans, Drosophila melanogaster and Danio rerio permit direct observation of cells moving in complex native environments and lend themselves to large-scale genetic and pharmacological screening. We highlight insights derived from each of these organisms, including the detailed signalling network that governs chemotaxis towards chemokines; a novel mechanism of basement membrane invasion; the positive role of E-cadherin in collective direction-sensing; the identification and optimization of kinase inhibitors for metastatic thyroid cancer on the basis of work in flies; and the value of zebrafish for live imaging, especially of vascular remodelling and interactions between tumour cells and host tissues. While the motility of tumour cells and certain host cells promotes metastatic spread, the motility of tumour-reactive T cells likely increases their antitumour effects. Therefore, it is important to elucidate the mechanisms underlying all types of cell motility, with the ultimate goal of identifying combination therapies that will increase the motility of beneficial cells and block the spread of harmful cells.

Fascin expression is inversely correlated with breast cancer metastasis suppressor 1 and predicts a worse survival outcome in node-negative breast cancer patients

Background: Fascin is an actin-bundling protein that promotes cancer cell migration and invasion. By contrast, breast cancer metastasis suppressor 1 (BRMS1) inhibits cancer metastasis by targeting multiple steps of the metastatic cascade. We evaluated whether expression patterns of fascin and BRMS1 correlate with clinicopathological features and patient outcome. Methods: Immunohistochemistry for fascin and BRMS1 was performed using a tissue microarray constructed from 183 human breast cancer tissues. Fascin expression determined by the proportion of stained tumor cells (0: 0-5%, 1: 6-25%, 2: 26-50%, 3: 51-75%, or 4: >75%) and staining intensity (0: negative, 1: weak, 2: moderate, or 3: strong) were multiplied and defined as negative (0-3) or positive (4-12). BRMS1 expression was scored separately based on nuclear and cytoplasmic staining intensity (0: negative, 1: weak, 2: moderate, 3: strong). We obtained the BRMS1 H score by summing the nuclear and cytoplasmic scores and defined it as negative (0-2) or positive (3-6). Results: Expression of BRMS1 showed a significant inverse correlation with that of fascin. Fascin+ tumors were significantly associated with no lymph node metastasis, higher histological and higher nuclear grade, ER/PR/HER2 negativity, and triple-negative subtype (all ps < 0.05). These clinicopathological differences showed the same trend in a comparison of fascin-/BRMS1+ and fascin+/BRMS1- tumors. Negative or weak BRMS1 cytoplasmic expression was significantly associated with shorter disease-free survival (DFS; p = 0.043). Fascin positivity was significantly associated with shorter DFS (p = 0.005) and overall survival (p = 0.020) when analyses were confined to node-negative patients. Conclusions: This study confirms an inverse correlation between expression of fascin and expression of BRMS1 using a quite large cohort of human breast cancer tissues. Fascin alone or combined with BRMS1 was a worse prognostic marker, particularly in node-negative breast cancer patients.

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.

Characterization of DAPK1 as a novel transcriptional target of BRMS1

Breast cancer metastasis suppressor 1 (BRMS1) can specifically regulate tumor metastasis in many cancers. Our previous studies have demonstrated that BRMS1 can promote cell apoptosis through regulating osteopontin (OPN) expression in hepatocellular carcinoma (HCC) cells. However, the transcriptional targets of BRMS1 have not been thoroughly studied. In this study, death-associated protein kinase 1 (DAPK1), a tumor suppressor gene with multiple roles in regulating cell death, was identified as a potential transcriptional target of BRMS1 in the whole genome expression microarray. Quantitative real-time PCR and western blot analysis of HCC cells overexpressing BRMS1 further confirmed the transcriptional regulation relationship between BRMS1 and DAPK1. Moreover, DAPK1 expression was frequently decreased or even lost in HCC tissue samples by comparison with neighboring pathologically normal liver tissue, which was consistent with the decreased BRMS1 expression pattern. To unravel the molecular mechanism of BRMS1 in regulating DAPK1, a series of deletion mutants of DAPK1 promoter was subjected to luciferase assay. The luciferase units of -200 to -80 bp region, with two tandem putative NF-κB binding sites, were specifically enhanced by BRMS1 expression. Site-directed mutants of NF-κB binding sites blocked the transcriptional activation effect. In addition, the binding capability of BRMS1 and the putative NF-κB binding sites were demonstrated in the chromatin immunoprecipitation (ChIP) assay. In conclusion, our study characterized DAPK1 as a novel transcriptional target of BRMS1. Transcriptional activation of DAPK1 might be another important mechanism accounting for the metastasis suppressive activity of BRMS1.

Mechanisms governing metastatic dormancy in breast cancer

Breast cancer is a systemic disease characterized by early dissemination of tumor cells to distant organs. In this foreign environment, tumor cells may stay in a dormant state as single cells or as micrometastases for many years before growing out into a macrometastatic lesion. As metastasis is the primary cause for breast cancer-related death, it is important to understand the mechanisms underlying the maintenance of dormancy and dormancy escape to find druggable targets to eradicate metastatic tumor cells. Metastatic dormancy is regulated by complex interactions between tumor cells and the local microenvironment. In addition, cancer-directed immunity and systemic instigation play a crucial role.

miR-346 promotes migration and invasion of nasopharyngeal carcinoma cells via targeting BRMS1

The aim of this study is to determine the expression and roles of miR-346 in nasopharyngeal carcinoma (NPC). We showed that miR-346 was upregulated in NPC tissues compared with adjacent non-tumorous nasopharyngeal tissues. Inhibition of miR-346 significantly attenuated the migration and invasion of NPC cells. Luciferase reporter assay showed that miR-346 targeted the 3'-untranslated region (3'-UTR) of breast cancer metastasis suppressor 1 (BRMS1). Overexpression of miR-346 suppressed the endogenous expression of BRMS1 in NPC cells. There was a significant negative correlation between miR-346 and BRMS1 protein expression in NPC tissues (r = -0.372, P = 0.008). Rescue experiments demonstrated that overexpression of BRMS1 lacking the 3'-UTR impaired the invasiveness of NPC cells transfected with miR-346 mimic. Taken together, miR-346 shows the ability to promote the migration and invasion of nasopharyngeal cancer cells via targeting BRMS1 and represents a potential therapeutic target for NPC.

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.