CEP55 Antibody

What is CEP55 and why is it important in cellular research?

CEP55 (Centrosomal Protein of 55 kDa) is a critical protein that localizes to the centrosome during interphase and is recruited to the midbody during cytokinesis. It plays an essential role in mitotic exit and cytokinesis, particularly in the final stages of cell division. CEP55 functions as a microtubule-bundling protein that associates with the centralspindlin complex (MKLP1-MgcRacGAP) to control midbody integrity and cell abscission during cytokinesis . The protein is expressed in various tissues, particularly in proliferative tissues, with high expression noted in testis and embryonic brain . Its importance in research stems from its dual role in normal cellular division and its emerging significance as an oncogene in multiple cancer types .

What are the typical applications for CEP55 antibodies in research?

CEP55 antibodies are utilized in multiple experimental applications:

The antibodies can detect CEP55 in multiple species, particularly human and mouse samples, making them versatile tools for comparative studies . Western Blot is the most widely used application, while immunohistochemistry is particularly valuable for analyzing CEP55 expression in tumor tissues for cancer research .

What are the optimal protocols for CEP55 immunodetection in cancer tissues?

For immunohistochemical detection of CEP55 in cancer tissues, the following protocol optimizations are recommended:

• Antigen retrieval: Use TE buffer at pH 9.0 for optimal results. Alternatively, citrate buffer at pH a6.0 may be used .

• Antibody dilution: Begin with a 1:1000 dilution for paraffin-embedded samples and adjust as needed (1:1000-1:4000 range) .

• Detection systems: For cancer tissues with potentially variable expression levels, a high-sensitivity detection system is preferable.

• Controls: Include both positive controls (testis tissue expresses high levels of CEP55) and negative controls (brain tissue has low expression in most regions) .

• Counterstaining: Use light hematoxylin counterstaining to preserve visibility of CEP55 immunoreactivity, particularly important when analyzing nuclear vs. cytoplasmic localization.

These recommendations are based on studies of CEP55 immunoreactivity in colorectal cancer specimens and other cancer types, though each tissue type may require specific optimization.

How can researchers validate CEP55 antibody specificity for their experiments?

Validating antibody specificity is crucial for reliable research results. For CEP55 antibodies, the following validation approaches are recommended:

• Knockdown/overexpression controls: Generate stable CEP55 knockdown (using RNAi) and overexpression cell lines to confirm antibody specificity. This approach was effectively used in studies of CEP55 in glioma cells, where three different RNAi constructs were tested, and RNAi-2 was selected for the highest knockdown efficiency .

• Multiple antibody comparison: Use antibodies from different sources or those targeting different epitopes of CEP55 to confirm consistent findings.

• Western blot analysis: Confirm that the antibody detects a band of the expected molecular weight (47-55 kDa).

• Phospho-specificity validation: For phospho-specific antibodies, treat samples with phosphatase to confirm that signal is lost after dephosphorylation .

• Subcellular localization pattern: Verify that the antibody shows the expected localization pattern - CEP55 should localize to the centrosome during interphase, the mitotic spindle during prometaphase and metaphase, and the midbody during cytokinesis .

What are the critical considerations when using CEP55 antibodies for cell cycle analysis?

When using CEP55 antibodies to study cell cycle dynamics, researchers should consider:

• Cell synchronization: For optimal detection of cell cycle-specific localization patterns, cells should be synchronized. Nocodazole treatment followed by release is an effective method, as it allows for the observation of CEP55 at different cell cycle stages .

• Co-staining markers: Include co-staining with established cell cycle markers (such as phospho-histone H3 for mitosis) and cytoskeletal markers (α-tubulin for microtubules).

• Dynamic interactions: The association between CEP55 and centralspindlin complex changes throughout the cell cycle, peaking during cytokinesis and G1. Time-course experiments are therefore valuable for capturing these dynamic interactions .

• Fixation methods: For preserving centrosomal and midbody structures, paraformaldehyde fixation (4%) for 15 minutes at room temperature is recommended, followed by permeabilization with 0.2% Triton X-100.

• Resolution requirements: High-resolution microscopy (confocal or super-resolution) is necessary to accurately visualize CEP55 localization during cell division, particularly at the midbody.

How can CEP55 antibodies be used to investigate cancer progression and prognosis?

CEP55 antibodies have become valuable tools in cancer research due to the correlation between CEP55 expression and cancer prognosis. Advanced applications include:

• Tissue microarray analysis: CEP55 antibodies can be used to evaluate expression across multiple tumor samples simultaneously, correlating levels with clinical parameters such as tumor grade, stage, and patient survival. This approach has revealed that CEP55 upregulation correlates with poor prognosis in multiple cancers, including liver, kidney, and lung cancers .

• Prognostic stratification: In colorectal cancer, CEP55 expression has been used to stratify patients, with multivariate analysis showing that patients with N stage (1+2) colorectal cancer and high CEP55 expression had significantly lower five-year survival rates compared to those with low CEP55 expression .

• Correlation with molecular markers: CEP55 antibody staining can be combined with analysis of other markers to develop comprehensive prognostic panels. Studies have shown correlations between CEP55 expression and tumor mutation burden (TMB), microsatellite instability (MSI), and neoantigen counts across multiple cancer types .

• Response to therapy prediction: CEP55 expression levels have been correlated with response to immunotherapy, with higher CEP55 expression associated with better response to anti-PDL1 therapy in some cancer types .

What approaches can be used to study CEP55 phosphorylation and its functional significance?

Studying CEP55 phosphorylation requires specialized approaches:

• Phospho-specific antibodies: Antibodies that specifically recognize phosphorylated residues, such as Phospho-CEP55 (Ser425), enable the detection of activated forms of CEP55 .

• Phosphorylation site mutants: Create point mutations at key phosphorylation sites (such as Ser425) to generate phospho-mimetic (e.g., S425D) or phospho-dead (e.g., S425A) mutants for functional studies.

• Kinase inhibition studies: Use specific kinase inhibitors to block phosphorylation pathways and observe effects on CEP55 function and localization.

• Mass spectrometry analysis: For comprehensive identification of all phosphorylation sites, immunoprecipitate CEP55 using validated antibodies and analyze by LC-MS/MS.

• In vitro kinase assays: To identify kinases responsible for CEP55 phosphorylation, purified CEP55 can be used as a substrate for candidate kinases, with phospho-specific antibodies used to detect successful phosphorylation.

How can researchers utilize CEP55 antibodies to investigate its role in the tumor immune microenvironment?

CEP55 has emerging roles in immune regulation within the tumor microenvironment. Advanced applications include:

What are common challenges in CEP55 immunodetection and how can they be addressed?

Researchers frequently encounter these challenges when working with CEP55 antibodies:

• Background staining: High background can obscure specific signals, particularly in IHC applications. Solutions include:

  • Additional blocking steps (5% BSA or normal serum from the secondary antibody species)

  • Titrating primary antibody concentration (starting with higher dilutions like 1:5000 for WB)

  • Using monoclonal antibodies for higher specificity

• Isoform detection variability: Some antibodies may preferentially detect one isoform over another.

  • Verify which epitope the antibody recognizes

  • Consider using antibodies raised against different regions of CEP55

• Cell cycle-dependent detection: CEP55 localization and potentially epitope accessibility change during the cell cycle.

  • For population studies, consider cell synchronization

  • For imaging studies, use cell cycle markers for accurate interpretation

• Fixation artifacts: Improper fixation can disrupt CEP55 structure or accessibility.

  • For IF/ICC, test both PFA and methanol fixation methods

  • For IHC, optimize antigen retrieval conditions (TE buffer pH 9.0 recommended)

How can researchers resolve discrepancies in CEP55 expression data between different detection methods?

When facing inconsistent results across different methodologies:

• Antibody validation across platforms: Verify that the same antibody performs consistently across different applications (WB, IHC, IF). Some antibodies work well for WB but poorly for IHC or vice versa.

• Epitope accessibility issues: Consider whether the epitope might be masked in certain contexts.

  • For FFPE tissues, extended antigen retrieval may be necessary

  • For protein complexes, native conditions may mask epitopes visible under denaturing conditions

• Isoform-specific expression: Discrepancies may reflect differential expression of CEP55 isoforms.

  • Use antibodies that recognize different regions of CEP55

  • Complement protein detection with mRNA analysis (RT-qPCR or RNA-seq)

• Sample preparation effects: Different lysis buffers or fixation methods can affect epitope preservation.

  • Standardize sample preparation across experiments

  • Include positive controls (testis tissue or cells with known high CEP55 expression)

• Quantification methods: Variations in quantification approaches can lead to apparent discrepancies.

  • Use consistent scoring systems for IHC (H-score, percentage positive, or intensity scales)

  • For WB, normalize to appropriate loading controls

How can CEP55 antibodies contribute to the development of targeted cancer therapies?

CEP55 antibodies are becoming instrumental in developing targeted therapies:

• Target validation: CEP55 antibodies can validate its overexpression across patient cohorts to determine suitable cancer types for targeted therapy. Pan-cancer analyses have identified CEP55 as upregulated in 22 cancer types compared to normal tissues .

• Drug screening: Antibodies can be used to monitor CEP55 levels or localization changes following treatment with candidate compounds. Several small molecule drugs have been predicted to target CEP55, including AZ628, SB52334, SB590885, A-770,041, AZD7762, and others .

• Antibody-drug conjugates (ADCs): For cancers with cell-surface exposed CEP55 epitopes, therapeutic antibodies conjugated to cytotoxic agents could be developed.

• Immunotherapy biomarkers: CEP55 expression levels correlate with response to immunotherapy, with higher CEP55 expression associated with better responses to anti-PDL1 therapy in some cancers. Antibody-based assays can help stratify patients for immunotherapy trials .

• Combination therapy rationales: CEP55 antibody staining has revealed correlations with other cancer pathways, suggesting potential combination therapy approaches. For example, the positive correlation between CEP55 and proliferation markers like KIF11, CDK1, and CCNA2 suggests potential synergies with cell cycle inhibitors .

What are the future methodological advances expected for CEP55 antibody applications?

Several technological advances are likely to enhance CEP55 antibody applications:

• Super-resolution microscopy: As these techniques become more accessible, they will enable more detailed analysis of CEP55 localization during cell division and its interactions with midbody components.

• Single-cell proteomics: Emerging single-cell protein analysis methods will allow correlation of CEP55 levels with other proteins at individual cell resolution, revealing heterogeneity within tumors.

• In vivo imaging: Development of near-infrared labeled antibodies or nanobodies against CEP55 could enable tracking of CEP55-overexpressing tumors in preclinical models.

• Proximity labeling approaches: Antibodies can be used to validate results from BioID or APEX2 proximity labeling studies identifying novel CEP55 interacting partners.

• Spatially-resolved transcriptomics integration: Combining CEP55 antibody staining with spatial transcriptomics will provide insights into how the tumor microenvironment shapes CEP55 expression patterns.

• Liquid biopsy applications: Development of sensitive assays to detect CEP55 in circulating tumor cells using validated antibodies could provide minimally invasive monitoring of CEP55-associated cancer progression.

How can researchers integrate CEP55 antibody data with multi-omics approaches for comprehensive cancer studies?

Integration of CEP55 antibody-generated data with multi-omics approaches can provide powerful insights:

• Proteogenomic integration: Correlate CEP55 protein levels (detected by antibodies) with genomic alterations and transcriptomic changes to understand regulatory mechanisms.

  • Studies have linked CEP55 expression with specific genetic alterations and methylation patterns across cancer types

• Pathway analysis: Combine CEP55 localization data with interactome studies to map functional networks.

  • CEP55 interacts with MKLP1-MgcRacGAP centralspindlin complex and is under its control during cytokinesis

  • It also shows strong correlations with KIF11, CDK1, and CCNA2 in cancer contexts

• Immune contexture mapping: Integrate CEP55 expression patterns with immunophenotyping to understand influences on the tumor microenvironment.

  • CEP55 expression correlates with infiltration of specific immune cell populations, including Th2 cells and certain CD4+ T cell subsets

  • It also affects levels of different immune checkpoints and chemokines in the tumor microenvironment

• Clinical data integration: Link CEP55 expression patterns with treatment responses and clinical outcomes.

  • Higher CEP55 expression has been associated with better response to anti-PDL1 therapy in some cancer types

  • Elevated CEP55 expression correlates with poorer survival in multiple cancer types

• Systems biology modeling: Use CEP55 antibody data as input for computational models predicting cancer behavior and treatment responses.

  • The correlation of CEP55 with tumor mutation burden (TMB) and microsatellite instability (MSI) can inform immunotherapy response predictions