BRMS1 Antibody

What is BRMS1 and why is it significant in cancer research?

BRMS1 is a 246-amino acid protein that functions as a metastasis suppressor in various cancer types, including breast, ovarian, lung, and bladder cancers, as well as murine mammary tumors. Its primary significance lies in its ability to suppress metastasis without inhibiting primary tumor growth (tumorigenicity) . This unique characteristic makes it particularly valuable for understanding the metastatic process, as BRMS1 modifies several metastasis-associated phenotypes that potentially alter cancer progression . BRMS1 mRNA expression has been detected in multiple tissues including ovary, prostate, testis, and colon, though the protein is primarily localized in term placenta .

The protein's significance extends to its participation in transcriptional regulation through interaction with the mSin3/histone deacetylase complex, potentially influencing metastasis-related gene expression . Additionally, BRMS1 regulates gap junction formation by enhancing connexin Cx43 expression while reducing Cx32 levels, facilitating intercellular communication similar to that found in normal breast tissue .

What types of BRMS1 antibodies are available for research applications?

Several types of BRMS1 antibodies have been developed for research purposes:

• Monoclonal antibodies: Mouse monoclonal IgG1 kappa light chain antibodies (such as clone 4H7) that specifically detect human BRMS1 protein .

• Full-length antigen-derived antibodies: These include monoclonal antibodies like clone 3a1.21, developed using full-length BRMS1 as an antigen at the University of Alabama, Birmingham Cancer Center Antibody Core Facility .

• Application-specific antibodies: BRMS1 antibodies are available in formats optimized for western blotting (WB), immunoprecipitation (IP), and enzyme-linked immunosorbent assay (ELISA) .

Most commercially available options are non-conjugated anti-BRMS1 monoclonal isotype antibodies, though their specificity has been confirmed through various validation methods including immunoblots, immunoprecipitation, and mass spectrometry techniques .

What detection methods are compatible with BRMS1 antibodies?

BRMS1 antibodies can be employed in multiple detection techniques:

The choice of method depends on the specific research question. For examining BRMS1 expression patterns in tissue samples, immunohistochemistry is preferred . For quantitative protein analysis or verification of molecular weight, western blotting provides more definitive results .

What is the recommended protocol for immunohistochemical detection of BRMS1?

The validated immunohistochemistry protocol for BRMS1 detection includes:

• Tissue preparation: Create 4-μm-thick unstained sections placed onto electrostatically charged glass slides and bake overnight .

• Antibody optimization: Determine optimal primary antibody concentration through serial dilutions on positive control tissue (placenta). A 1/50 dilution has been successfully employed in previous studies .

• Antigen detection: Use a peroxidase-conjugated secondary antibody followed by 3,3′-diaminobenzidine chromogen for visualization .

• Scoring system: Evaluate BRMS1 staining on a 0 to 3+ intensity scale:

  • 0: Negative nuclear staining

  • 1+: Weak nuclear staining

  • 2+: Moderately intense staining

  • 3+: Strong staining

• Evaluation criteria: Consider a case positive if at least one of two tissue cores contains sufficient tumor for evaluation and at least 10% of invasive tumor cells show staining .

Normal breast epithelial and myoepithelial cells typically show strong nuclear immunoreactivity (2-3+), providing internal positive controls .

What is the protein separation and detection protocol for BRMS1 western blotting?

The recommended western blotting protocol for BRMS1 detection includes:

• Protein extraction: Prepare tissue or cell lysates and centrifuge at 13,000g at 4°C for 10 minutes to remove insoluble material .

• Protein quantification: Determine concentration using Bradford colorimetric assay .

• SDS-PAGE: Load 25-80 μg protein per lane mixed with 5× loading buffer (50% glycerol and 1.5% bromophenol blue) and separate on 12% SDS-polyacrylamide gel .

• Transfer: Perform wet transfer to polyvinylidene difluoride membrane (0.36A, 75 minutes) .

• Blocking: Wet membrane in methanol, rinse in TTBS solution (0.05% Tween 20, 20 mmol/L Tris, and 140 mmol/L NaCl, pH 7.6), and block in TTBS containing 5% dry nonfat milk for 1 hour .

• Antibody incubation: Detect BRMS1 using 1:2500 dilution of mouse monoclonal antibody (e.g., clone 3a1.21) for 2 hours at room temperature under constant agitation .

• Visualization: Use appropriate secondary antibody and detection system according to laboratory standard procedures.

How does BRMS1 inhibit the metastatic cascade at the molecular level?

BRMS1 employs multiple mechanisms to suppress metastasis:

• Transcriptional regulation: BRMS1 interacts with the mSin3/histone deacetylase complex to influence gene expression related to metastasis .

• Gap junction modulation: It enhances the expression of connexin Cx43 while reducing connexin Cx32 levels, leading to the formation of gap junctions that facilitate intercellular communication similar to normal breast tissue .

• NFκB inhibition: BRMS1 may inhibit the activity of nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB), affecting downstream signaling pathways involved in metastasis .

• Anoikis sensitization: BRMS1 expression increases susceptibility to anoikis (programmed cell death due to detachment from the extracellular matrix), thereby reducing survival of circulating tumor cells .

• Protein stabilization: BRMS1 is stabilized by heat shock protein 90 (Hsp90), suggesting regulatory mechanisms involving molecular chaperones .

These molecular functions collectively contribute to BRMS1's ability to suppress metastasis by interfering with multiple steps in the metastatic cascade.

What experimental models demonstrate BRMS1's metastasis suppression function?

Several experimental models have been employed to investigate BRMS1's metastasis suppression capabilities:

• Intracardiac injection model: Human breast carcinoma cell lines MDA-MB-231 and MDA-MB-435 expressing enhanced green fluorescent protein (GFP), with and without BRMS1 expression, injected into the left cardiac ventricle of mice. This approach achieves wide cellular distribution by minimizing first-pass clearance in the lungs and allows assessment of multi-organ metastasis .

• Fluorescence tracking: GFP-labeled cells enable ex vivo detection of single cells in most tissues, overcoming the limitations of traditional histological approaches in tracking tumor cells across multiple tissues .

• Organ-specific metastasis assessment: BRMS1-expressing cells form significantly fewer metastases in multiple organs, including brain, kidneys, pancreas, and adrenal glands, demonstrating the protein's global metastasis suppression capability .

• Anoikis susceptibility assays: In vitro experiments confirm increased susceptibility to cell death during detachment, correlating with the reduced metastatic potential observed in vivo .

These models consistently demonstrate that BRMS1 expression significantly reduces metastatic burden across multiple organ sites, supporting its role as a genuine metastasis suppressor.

How does BRMS1 expression differ between normal and cancerous tissues?

BRMS1 expression exhibits distinct patterns between normal and cancerous tissues:

In normal tissues:

• Normal breast epithelial and myoepithelial cells show strong nuclear immunoreactivity (2-3+) for BRMS1 .

• Tumor-infiltrating lymphocytes consistently display strong nuclear BRMS1 expression .

• Neurons in normal brain tissue exhibit stronger BRMS1 staining compared to glial cells .

In cancerous tissues:

• Breast cancer: 75% of infiltrating breast cancer cases show moderate to strong BRMS1 immunoreactivity, while 25% exhibit focally weak to negative staining .

• BRMS1 can display either a diffuse or granular pattern of nuclear staining within infiltrating breast cancer cells, in both ductal and lobular cell types .

• Gliomas: BRMS1 protein expression is significantly decreased compared to non-cancerous brain tissue, though this finding may be partly attributable to the reduced presence of neurons in glioma tissue .

• Glioma grades 2/3 show stronger BRMS1 staining than glioblastoma multiforme (GBM), potentially correlating with their less aggressive behavior .

Interestingly, while protein expression is often reduced in cancerous tissues, BRMS1 mRNA levels may be elevated in certain cancers compared to normal tissues, suggesting post-transcriptional regulation mechanisms .

What is the relationship between BRMS1 expression and clinical/pathological factors?

Research has identified several associations between BRMS1 expression and clinical/pathological factors:

• Age correlation: Patients younger than 50 years at diagnosis may be more likely to exhibit negative BRMS1 expression .

• Tumor grade relationship: Lower-grade gliomas (grade 2/3) display stronger BRMS1 expression than higher-grade glioblastomas, suggesting potential correlation with tumor aggressiveness .

• Expression patterns in recurrence: Local tumor recurrences and multifocal relapses may exhibit different BRMS1 expression patterns compared to primary tumors .

• Spatial heterogeneity: BRMS1 mRNA expression can vary within different regions of the same tumor, with the leading edge (containing fewer tumor cells) showing significantly lower expression than other areas .

• Potential prognostic value: Given its role in metastasis suppression, BRMS1 expression status may hold prognostic significance, though more comprehensive studies are needed to establish definitive correlations with patient outcomes .

These associations highlight the complex relationship between BRMS1 expression and tumor biology, suggesting its potential utility as a biomarker for tumor behavior and patient stratification.

How can BRMS1 antibodies be used to investigate specific steps in the metastatic cascade?

BRMS1 antibodies enable detailed investigation of the metastatic cascade through several advanced applications:

• In vivo metastatic cell tracking: By combining BRMS1 antibodies with fluorescence labeling techniques, researchers can track the fate of BRMS1-expressing versus non-expressing cells after intravascular injection, revealing when and where BRMS1 exerts its suppressive effects .

• Cellular survival assessment: BRMS1 antibodies can help determine whether fewer BRMS1-expressing cells reach target organs compared to parental cells, suggesting increased cell death during transit—a critical step in metastasis suppression .

• Organ-specific metastasis analysis: Immunohistochemical detection of BRMS1 in metastatic deposits across multiple organs allows assessment of whether BRMS1 globally inhibits metastasis or selectively affects certain target organs .

• Protein complex analysis: Immunoprecipitation with BRMS1 antibodies followed by proteomic analysis can identify novel BRMS1-interacting proteins involved in metastasis regulation, expanding our understanding of the molecular mechanisms underlying metastasis suppression .

• Tumor microenvironment interactions: Dual immunostaining with BRMS1 antibodies and markers for stromal or immune cells can reveal how BRMS1 expression affects tumor-microenvironment interactions that influence metastatic potential .

These applications collectively provide a comprehensive toolkit for dissecting the multifaceted role of BRMS1 in metastasis regulation.

What methodological considerations exist for studying BRMS1 in different cancer models?

Researchers studying BRMS1 across different cancer models should consider several methodological aspects:

• Antibody validation: Verify antibody specificity for each model system, as recommended by using techniques such as immunoblots, immunoprecipitation, and mass spectrometry to confirm that detected sequences are BRMS1-specific .

• Expression level discrepancies: Be aware of potential disconnects between mRNA and protein expression levels. In some cancer types, BRMS1 mRNA levels may be elevated while protein levels are decreased, suggesting post-transcriptional regulation .

• Cell-type heterogeneity: Consider that BRMS1 expression varies among different cell types within the same tissue. For instance, in brain tissue, neurons typically show stronger BRMS1 expression than glial cells, potentially confounding analysis of whole-tissue homogenates .

• Control selection: Carefully select appropriate positive controls (placenta has been established as a reliable positive control for BRMS1 immunostaining) .

• Multi-method approach: Combine protein detection methods (immunohistochemistry, western blotting) with mRNA analysis (RT-PCR, RNA sequencing) to obtain a complete picture of BRMS1 expression patterns .

• Functional validation: Complement expression studies with functional assays to establish the biological relevance of BRMS1 in each cancer model, as expression alone may not directly correlate with metastasis suppression activity .

These considerations help ensure robust and reliable results when investigating BRMS1 across diverse experimental systems.

What is known about BRMS1 expression and function in brain tumors?

Recent research has begun elucidating BRMS1's role in brain tumors, particularly gliomas:

• Expression patterns: BRMS1 protein expression is significantly decreased in gliomas compared to non-cancerous brain tissue in tissue microarray analyses .

• Grade-dependent expression: Gliomas grade 2/3 show stronger BRMS1 immunostaining than glioblastoma multiforme (GBM), potentially correlating with their less aggressive behavior .

• Cell-type variations: BRMS1-positive glioma grade 2/3 cells are more frequently observed than BRMS1-positive tumor cells in GBM or normal astrocytes in cerebellum/cerebrum .

• mRNA vs. protein discrepancy: Interestingly, at the mRNA level, gliomas grade 2/3 exhibit significant BRMS1 overexpression compared to normal brain, pilocytic astrocytoma, and GBM, suggesting complex post-transcriptional regulation .

• Functional effects: In cell culture experiments, BRMS1 suppresses glioma invasion, migration, and adhesion, suggesting that its decreased expression may contribute to the aggressive behavior of high-grade gliomas .

• Pathway interactions: BRMS1 interacts with signaling pathways involved in glioma pathogenesis, including focal adhesion kinase, epidermal growth factor receptor, and NFκB, affecting key cellular functions such as migration, invasion, cell adhesion, and apoptosis .

These findings suggest that despite the low incidence of extra-cerebral glioma metastasis, BRMS1 may still play a significant role in regulating glioma behavior, particularly invasion and migration within the brain.

How does BRMS1 function compare across different cancer types?

BRMS1 exhibits both common and distinct functions across various cancer types:

Common functions:

• Metastasis suppression: BRMS1 consistently demonstrates metastasis-suppressive effects across breast, ovarian, and melanoma xenograft models .

• Apoptosis regulation: Across multiple cancer types, BRMS1 lowers the threshold for tumor cells to undergo apoptosis when exposed to stress .

• Cell migration and invasion inhibition: BRMS1 suppresses cell migration and invasion in breast cancer, melanoma, and glioma models .

Cancer-specific variations:

• Breast cancer: BRMS1 particularly affects gap junction formation through connexin regulation, enhancing intercellular communication similar to normal breast tissue .

• Gliomas: Despite the rarity of extra-cranial metastasis in gliomas, BRMS1 still regulates invasion and migration within the brain parenchyma .

• Expression patterns: While BRMS1 protein expression is generally decreased in cancerous tissues compared to corresponding normal tissues, the magnitude of this reduction varies by cancer type. Additionally, in some cancers like breast cancer and hypopharyngeal cancer, BRMS1 mRNA levels may be elevated in tumor cells compared to normal cells .

These comparative insights suggest that while BRMS1's core function as a regulator of cell motility and survival is conserved across cancer types, its specific mechanisms and expression patterns may be contextualized by tissue-specific factors, warranting tailored investigative approaches for each cancer type.