CBLL1 Antibody

What is CBLL1 and why is it important in research?

CBLL1 (also known as Hakai or RNF188) is an evolutionarily conserved E3 ubiquitin ligase containing a RING-finger domain. It's significant in research because it plays multiple roles in development and tumorigenesis. CBLL1 is frequently upregulated in non-small cell lung cancer (NSCLC) tissues compared to adjacent normal tissues, and its expression is associated with tumor size in NSCLC tissues . Studies have shown that CBLL1 promotes cell proliferation by facilitating G1/S cell cycle transition, and its knockdown inhibits cell invasion via increased E-cadherin protein expression and decreased expression of matrix metalloproteinases MMP2 and MMP9 in NSCLC cell lines . Due to its roles in cancer progression, CBLL1 serves as an important research target for understanding tumorigenesis and developing potential therapeutic strategies.

What are the key specifications of common CBLL1 antibodies?

CBLL1 antibodies are typically available as polyclonal or monoclonal formats targeting specific epitopes of the protein. Key specifications of common CBLL1 antibodies include:

For Western blot applications, CBLL1 antibodies typically show bands at 55-60 kDa, which corresponds to the calculated molecular weight of 55 kDa (491 amino acids) . Some antibodies may also detect additional bands at different molecular weights, such as 36 kDa, as observed in some experimental conditions .

What are the recommended dilutions for different applications?

Optimal dilutions vary depending on the specific application and the antibody being used. Based on available data, the following dilutions are recommended:

It's important to note that these are general guidelines, and researchers should titrate the antibody in their specific testing systems to obtain optimal results. Factors such as sample type, fixation method, and detection system can influence the optimal dilution . For some antibodies like EPR25389-121, specific dilutions have been validated for certain applications, such as 1/1000 for Western blot and 1/500 for flow cytometry .

How should I design controls for CBLL1 antibody validation?

Proper controls are crucial for validating CBLL1 antibody specificity and performance. For rigorous antibody validation, implement the following control strategies:

For Western blot applications, include a positive control using cell lines known to express CBLL1, such as HEK-293, HeLa, or MCF-7 cells . Include a negative control by using cells where CBLL1 has been knocked down via siRNA, as demonstrated in the validation data where HeLa cells transfected with CBLL1-targeting siRNA showed reduced band intensity compared to cells transfected with scrambled siRNA control . This knockdown approach provides strong evidence for antibody specificity.

For immunohistochemistry, incorporate both positive tissue controls (human colon cancer tissue or lung cancer tissue have been validated) and negative controls using the secondary antibody alone without primary antibody incubation . For immunofluorescence, include cells with known CBLL1 expression (HepG2 cells have been validated) and compare with negative controls where the primary antibody is omitted .

Cross-validation using different detection methods (e.g., WB, IHC, and IF) on the same samples can further strengthen confidence in antibody specificity. This multi-technique approach ensures that observed patterns are consistent across different detection platforms.

What are the recommended tissue preparation methods for CBLL1 IHC?

For optimal CBLL1 immunohistochemical staining, proper tissue preparation is essential. Based on published protocols, follow these methodological steps:

Prepare tissue specimens in 4 μm sections for optimal antibody penetration and staining. For antigen retrieval, use pressure cooking in citric acid buffer (pH 6.0) for approximately 1 minute and 40 seconds . This step is critical as it unmasks epitopes that may be cross-linked during fixation. Alternatively, antigen retrieval may be performed with TE buffer at pH 9.0, which has also been validated for CBLL1 antibodies .

Use a validated anti-CBLL1 antibody dilution (typically 1:50-1:500 range), and incubate overnight at 4°C for optimal binding . Include appropriate negative controls using unconjugated rabbit IgG and phosphate-buffered saline (PBS) . For automated staining systems, protocols using instruments such as the Leica Biosystems BOND® RX have been validated, with counterstaining using Hematoxylin to visualize tissue architecture .

For semi-quantitative scoring, evaluate both staining intensity and percentage of stained cells in representative areas. A standardized scoring system can be implemented: negative (0), light yellow (1), yellow (2), and deep brown (3) for intensity; and <5% (0), 5-25% (1), 25-50% (2), 51-75% (3), >75% (4) for percentage of stained cells . Multiply these scores to obtain a coloring coefficient, with ≤4 considered "low expression" and >4 considered "high expression" .

How can I optimize CBLL1 antibody for multiple detection methods?

Optimizing CBLL1 antibody for multiple detection methods requires systematic adjustment of protocols for each application. For Western blot optimization, test dilutions in the range of 1:1000-1:6000 and adjust blocking conditions accordingly—5% non-fat dry milk in TBST has been successful for detecting CBLL1 in cell lysates . For challenging samples, consider longer exposure times, as demonstrated in published protocols where 48-second exposures revealed clear bands at the expected molecular weight .

For immunofluorescence applications, dilutions in the range of 1:200-1:800 have proven effective . When working with fixed cells, 4% paraformaldehyde fixation followed by 90% methanol permeabilization has been validated for optimal intracellular staining . For flow cytometry, a 1:500 dilution (0.1 μg) has been successfully used with proper controls, including rabbit monoclonal IgG isotype controls and unstained cells .

When transitioning between detection methods, maintain consistent antibody lots when possible to minimize variability. For multiplex applications, ensure the antibody is compatible with your conjugation chemistry if using direct labeling approaches. Many CBLL1 antibodies are available in conjugation-ready formats designed for use with fluorochromes, metal isotopes, oligonucleotides, and enzymes, making them suitable for antibody labeling, functional assays, flow-based assays, and multiplex imaging applications .

Why might Western blot show multiple bands with CBLL1 antibody?

These multiple bands could represent alternative splice variants of CBLL1, post-translational modifications such as phosphorylation or ubiquitination (particularly relevant given CBLL1's role as an E3 ubiquitin ligase), or protein degradation products. To determine whether additional bands are specific, perform validation experiments using siRNA knockdown of CBLL1. In published validation studies, both the primary 55-60 kDa band and additional bands showed reduced intensity in CBLL1 siRNA-transfected cells compared to control siRNA-transfected cells, suggesting these bands are indeed CBLL1-specific .

Technical factors that might contribute to non-specific bands include inadequate blocking, excessive antibody concentration, or sample overloading. To minimize these issues, optimize blocking conditions (5% non-fat dry milk in TBST has been successful), titrate antibody concentration within the recommended 1:1000-1:6000 range, and load appropriate amounts of protein (20 μg has been used successfully in published protocols) .

How can I address weak or no signal in CBLL1 immunohistochemistry?

Weak or absent signals in CBLL1 immunohistochemistry can stem from several methodological issues. If you encounter this problem, implement the following troubleshooting strategies:

First, review your antigen retrieval method. CBLL1 antibodies require efficient epitope unmasking, with published protocols recommending pressure cooking in citric acid buffer (pH 6.0) for 1 minute 40 seconds . Alternatively, try TE buffer at pH 9.0, which has also been validated . Insufficient antigen retrieval is a common cause of weak signals.

Next, optimize antibody concentration. The recommended dilution range for IHC is 1:50-1:500 , but you may need to use a higher concentration (1:50) for weakly expressing tissues. Extend the primary antibody incubation time to overnight at 4°C to maximize binding .

Verify antibody performance using positive control tissues known to express CBLL1, such as human colon cancer tissue or lung cancer tissue . If controls work while your samples don't, consider tissue-specific factors like fixation time or sample age that might affect antigen preservation.

For quantification purposes, be aware that CBLL1 immunostaining is observed in both the nuclei and cytoplasm of cancer cells, while in normal lung tissues, CBLL1 expression is typically low in the nuclei of alveoli, bronchi tissues, and lung parenchyma . This subcellular localization pattern can help distinguish specific from non-specific staining.

What factors affect reproducibility in CBLL1 antibody-based experiments?

Multiple factors can impact reproducibility in CBLL1 antibody-based experiments, requiring careful attention to experimental parameters. Antibody source and lot-to-lot variation significantly influence results—published studies have used specific validated antibodies such as Sigma's HPA021773 for CBLL1 detection . When possible, maintain consistent antibody lots throughout a study and validate new lots against previous results.

Sample preparation variables are critical. For cell lines, CBLL1 expression levels vary significantly—A549, H1299, and SK cells show higher CBLL1 expression than immortalized HBE cells . Cellular confluence and passage number can affect expression levels. For tissue samples, fixation methods and duration significantly impact epitope preservation and accessibility.

Technical variables include antibody dilution consistency, incubation time and temperature control, and detection system sensitivity. For Western blots, loading equal amounts of protein (typically 20 μg) and using validated housekeeping controls like GAPDH are essential . For IHC, consistent staining conditions and scoring methods are crucial—published protocols use a semi-quantitative scoring system evaluating both staining intensity and percentage of stained cells .

Experimental controls must be rigorously implemented. For knockdown studies, validate siRNA efficiency at both mRNA and protein levels. Three pairs of CBLL1 siRNA sequences were initially tested in published studies, with the most effective sequence (5′-CAC CAG ACA AGC ACC AUA UTT-3′ and 5′-AUA UGG UGC UUG UCU GGU GTT-3′) selected for experiments .

How does CBLL1 expression vary across different cancer types?

CBLL1 expression exhibits distinctive patterns across various cancer types, with notable differences in expression levels and clinical significance. In non-small cell lung cancer (NSCLC), CBLL1 is frequently upregulated compared to adjacent non-tumor tissues. Immunohistochemical analysis of 79 NSCLC tissues and 24 adjacent normal lung tissues revealed high expression of CBLL1 in 64 (81.01%) of the NSCLC cases . This high expression positively correlated with tumor size, suggesting a role in NSCLC progression .

In colon and gastric cancers, CBLL1 is similarly upregulated and has been reported to induce anchorage-dependent cell growth . CBLL1 expression is inversely correlated with E-cadherin in several colon adenocarcinoma tissues, suggesting a role in the epithelial-mesenchymal transition in these cancers .

Interestingly, CBLL1 appears to play contrasting roles in different cancer types. While it promotes proliferation in lung and colon cancers, in estrogen receptor alpha-dependent breast cancer (MCF-7 cells), CBLL1 overexpression inhibits estrogen-dependent cell proliferation and migration, potentially playing a negative role in the progression of estrogen-dependent breast cancer . This context-dependent function highlights the complexity of CBLL1's role in cancer biology.

The subcellular localization of CBLL1 also varies by tissue type. In normal lung tissues, CBLL1 expression is typically low and primarily nuclear in alveoli, bronchi tissues, and lung parenchyma . In contrast, in NSCLC tissues, CBLL1 immunostaining is observed in both the nuclei and cytoplasm of cancer cells . This differential localization may have functional implications for CBLL1's role in cellular processes.

What is the relationship between CBLL1 and E-cadherin in cancer progression?

The relationship between CBLL1 and E-cadherin represents a critical mechanism in cancer progression, particularly in relation to invasion and metastasis. CBLL1, as an E3 ubiquitin ligase, directly regulates E-cadherin levels post-translationally. Research has demonstrated that knockdown of CBLL1 inhibits cell invasion via increased E-cadherin protein expression in NSCLC cell lines . Importantly, while protein levels of E-cadherin increase after CBLL1 depletion, E-cadherin mRNA remains unaffected, confirming that CBLL1 regulates E-cadherin at the post-transcriptional level, likely through its ubiquitin ligase activity .

In colorectal cancer, the relationship is particularly well-characterized. The autocrine Slit-Robo pathway promotes CBLL1-mediated downregulation of E-cadherin to promote carcinogenesis . An inverse correlation between CBLL1 and E-cadherin expression has been observed in several colon adenocarcinoma tissues , supporting the functional relationship between these proteins in clinical samples.

The CBLL1/E-cadherin axis affects multiple downstream pathways involved in cancer progression. CBLL1 knockdown not only increases E-cadherin but also decreases the expression of matrix metalloproteinases MMP2 and MMP9 in NSCLC cell lines . These MMPs are crucial for degrading extracellular matrix components and facilitating tumor cell invasion.

Interestingly, research suggests that CBLL1 may also influence cell phenotypes through E-cadherin-independent mechanisms. Studies have shown that knockdown of E-cadherin in CBLL1-overexpressing epithelial cells does not promote cusp formation, suggesting additional pathways through which CBLL1 affects cellular behavior . This complex interplay highlights the multifaceted role of CBLL1 in cancer progression beyond simply regulating E-cadherin.

How can CBLL1 antibodies be applied in combination with other markers?

CBLL1 antibodies can be effectively combined with other markers to provide deeper insights into cancer biology and cellular processes. For investigating epithelial-mesenchymal transition (EMT) mechanisms, combine CBLL1 antibodies with E-cadherin, N-cadherin, and vimentin antibodies. Published research has already established connections between CBLL1 and E-cadherin, showing that knockdown of CBLL1 increases E-cadherin protein expression without affecting E-cadherin mRNA levels in NSCLC cell lines . This multiplex approach allows visualization of CBLL1's role in regulating EMT dynamics.

For cell cycle regulation studies, combine CBLL1 antibodies with cyclins and cyclin-dependent kinases. Research has demonstrated that CBLL1 promotes G1/S cell cycle transition in NSCLC cells . Specific antibodies against cyclin D1, cyclin E, and CDK4 have been used alongside CBLL1 in published studies , enabling comprehensive assessment of how CBLL1 affects the cell cycle machinery.

When studying invasion mechanisms, pair CBLL1 with matrix metalloproteinases (MMPs). CBLL1 knockdown decreases expression of MMP2 and MMP9 in NSCLC cell lines . Co-staining with these markers in tissue samples can reveal spatial relationships and potential regulatory connections.

For multiplex immunofluorescence approaches, consider that CBLL1 antibodies are available in conjugation-ready formats designed for use with fluorochromes, metal isotopes, oligonucleotides, and enzymes . This flexibility makes them suitable for sophisticated applications like mass cytometry and multiplex imaging. When designing these experiments, ensure spectral compatibility between fluorophores and include appropriate controls for each marker.

What are the latest techniques for studying CBLL1 function using antibody-based approaches?

Cutting-edge techniques for studying CBLL1 function with antibody-based approaches have expanded research capabilities in this field. Proximity ligation assays (PLA) represent an advanced application for detecting protein-protein interactions involving CBLL1. Given CBLL1's role as an E3 ubiquitin ligase that interacts with E-cadherin and potentially other proteins, PLA can visualize these interactions in situ with high specificity and sensitivity, revealing spatial and temporal dynamics of CBLL1-protein interactions within cells.

ChIP-seq applications using CBLL1 antibodies can explore potential nuclear functions of CBLL1. Immunofluorescence studies have shown that CBLL1 localizes to both the nucleus and cytoplasm in cancer cells but is primarily nuclear in normal cells like HBE . This differential localization suggests possible nuclear functions that could be investigated through chromatin immunoprecipitation followed by sequencing.

CBLL1 antibodies can be effectively utilized in CRISPR-Cas9 knockout validation. When generating CBLL1 knockout cell lines, antibodies provide crucial validation of successful gene editing. Previously published siRNA knockdown studies have already established protocols for validating CBLL1 depletion using Western blot , which can be adapted for CRISPR-Cas9 applications.

For single-cell analysis approaches, flow cytometry using CBLL1 antibodies has been validated. Protocols exist for 4% paraformaldehyde fixation followed by 90% methanol permeabilization, with CBLL1 antibody dilution at 1/500 . This approach can be extended to more sophisticated single-cell techniques like mass cytometry (CyTOF) for higher-dimensional protein profiling, especially given the availability of conjugation-ready antibody formats .

How can quantitative analysis of CBLL1 expression be standardized across studies?

Standardizing quantitative analysis of CBLL1 expression across studies requires establishing consistent methodologies and reporting practices. For immunohistochemistry quantification, adopt the validated semi-quantitative scoring system that evaluates both staining intensity and percentage of positive cells . This system assigns scores for intensity (0-3) and percentage (0-4), which are multiplied to obtain a coloring coefficient categorized as "low expression" (≤4) or "high expression" (>4) . Implementing this standardized approach facilitates comparison across different studies and patient cohorts.

For Western blot quantification, normalize CBLL1 band intensity to established housekeeping proteins such as GAPDH, which has been used successfully in published CBLL1 studies . Present relative expression as fold change compared to control samples, and include representative blot images alongside quantification graphs. Ensure equal protein loading (typically 20 μg per lane) and consistent antibody dilutions (1:1000-1:6000 range) across experiments .

Image analysis standardization is critical for immunofluorescence studies. Use unbiased automated quantification when possible, with clearly defined parameters for intensity thresholds, background correction, and region of interest selection. For subcellular localization analysis, develop separate quantification strategies for nuclear versus cytoplasmic CBLL1, as the protein shows different distribution patterns between normal and cancer cells .

Statistical analysis approaches should be standardized, with clear reporting of tests used. Published CBLL1 studies have employed chi-square tests for analyzing correlations between CBLL1 expression and clinicopathological factors, and independent t-tests, one-way ANOVA, or Kruskal-Wallis tests (selected based on data distribution) for experimental comparisons . Consistently report p-values with a standard significance threshold (p < 0.05).