CRTAC1 antibodies are monoclonal or polyclonal reagents designed for applications such as Western blot (WB), immunofluorescence (IF/ICC), and ELISA. Key commercial clones include:
Molecular Weight: 71–105 kDa (varies by isoform and glycosylation) .
Epitopes: Target regions include Ser28-Cys661 (R&D Systems) and FG-GAP domains .
Lung Adenocarcinoma (LUAD): CRTAC1 expression is significantly reduced in LUAD tissues compared to normal tissues (p < 0.05). Low CRTAC1 correlates with poor prognosis, while high expression enhances cisplatin chemosensitivity by promoting Ca²⁺-dependent Akt1 degradation and apoptosis .
Urothelial Carcinoma (UC): Reduced CRTAC1 is associated with aggressive tumor characteristics (high stage, vascular invasion) and worse metastasis-free survival (p < 0.001). Exogenous CRTAC1 expression suppresses cell proliferation and invasion by downregulating MMP2 .
Bladder Cancer: CRTAC1 inhibits glycolysis and angiogenesis via the TFAP2A-TPRG1-AS1 axis, making it a prognostic marker .
CRTAC1 is a biomarker for OA severity and progression. Plasma CRTAC1 levels predict joint replacement risk (HR = 16 for knee replacement within 5 years) . Its expression in chondrocytes is induced by IL-1β, implicating it in cartilage degeneration .
Cell Signaling: CRTAC1 overexpression increases intracellular Ca²⁺, activating NFAT/STUB1 pathways to degrade oncogenic Akt1 .
Immune Microenvironment: High CRTAC1 expression correlates with increased tumor-infiltrating immune cells (e.g., CD8⁺ T cells) and improved immunotherapy response .
CRTAC1 (cartilage acidic protein 1) is a protein encoded by the CRTAC1 gene with a calculated molecular weight of 71 kDa (661 amino acids) and observed molecular weight of 68-72 kDa in Western blot analyses . Recent research has identified CRTAC1 as a pyroptosis-related gene that functions as a protective factor in several cancer types including gastric adenocarcinoma and bladder cancer .
In bladder cancer, CRTAC1 has been shown to inhibit cell viability, proliferation, migration, invasion, and the epithelial-mesenchymal transition (EMT) process . CRTAC1 also plays a significant role in non-small cell lung cancer (NSCLC) where it enhances chemosensitivity to cisplatin treatment by promoting calcium-dependent Akt1 degradation and subsequent apoptosis .
CRTAC1 antibodies, such as the 13001-1-AP from Proteintech, are validated for multiple research applications:
| Application | Recommended Dilution | Validated Reactivity |
|---|---|---|
| Western Blot (WB) | 1:500-1:1000 | Human, mouse, rat |
| Immunohistochemistry (IHC) | 1:50-1:500 | Human, mouse, rat |
| Immunofluorescence (IF) | Varies by protocol | Human |
| ELISA | Application-dependent | Human, mouse, rat |
Positive WB detection has been confirmed in human brain tissue, while positive IHC detection has been observed in mouse lung tissue, mouse brain tissue, and rat lung tissue . For optimal results, it is recommended to titrate the antibody concentration for each specific testing system and sample type .
CRTAC1 expression shows significant alterations in several pathological conditions:
In cancer:
CRTAC1 mRNA expression is significantly downregulated in lung adenocarcinoma (LUAD) tissues compared to normal lung tissue (p < 0.05)
Lower CRTAC1 expression is associated with poor prognosis in LUAD patients
Similarly, CRTAC1 is downregulated in bladder cancer tissues and cell lines
Both mRNA and protein levels of CRTAC1 are reduced in tumor tissue compared to adjacent normal tissue in LUAD
In degenerative conditions:
CRTAC1+ cell populations show altered expression patterns in degenerative spinal ligaments
A higher number of CRTAC1+ cells express CD44 in degenerative ligaments compared to normal tissues
These expression patterns suggest that CRTAC1 may function as a tumor suppressor in certain cancers, with its downregulation contributing to pathogenesis and poor outcomes.
Based on established methodologies in NSCLC research , a comprehensive experimental design should include:
In vitro studies:
Generate stable cell lines:
Overexpress CRTAC1 in cancer cell lines with high chemotherapeutic IC50 values
Create vector control cell lines for comparison
Validate CRTAC1 expression by Western blotting
Perform knockdown experiments:
Use siRNAs targeting CRTAC1 in cell lines with naturally lower IC50 values
Verify knockdown efficiency by Western blotting
Include appropriate scramble controls
Assess chemosensitivity:
Conduct ATP assays to determine IC50 values for chemotherapeutic agents
Perform dose-response curves across multiple cell lines
Measure apoptosis using Annexin V/7-AAD flow cytometry
Quantify cell death markers (cleaved caspase-3, PARP) by Western blotting
In vivo studies:
Establish xenograft models:
Inject CRTAC1-overexpressing cells and vector control cells into immunodeficient mice
Allow tumors to form (approximately 7 days)
Randomize mice into treatment and control groups
Administer treatment:
Treat with chemotherapeutic agent (e.g., cisplatin 3 mg/kg every 3 days)
Treat control groups with vehicle solution (e.g., PBS)
Monitor outcomes:
Analyze molecular mechanisms:
To investigate CRTAC1's interactions with signaling pathways, researchers should implement the following methodological approaches:
Protein-protein interaction studies:
Transcriptional regulation analysis:
Chromatin immunoprecipitation (ChIP) to identify DNA binding interactions
Luciferase reporter assays to assess effects on transcriptional activity
qRT-PCR to measure changes in target gene expression
Pathway activity assessment:
Mechanistic validation:
For example, researchers studying CRTAC1 in NSCLC demonstrated that it promotes NFAT transcriptional activation by increasing intracellular Ca²⁺, inducing STUB1 expression, which in turn accelerates Akt1 protein degradation and enhances cisplatin-induced apoptosis . In bladder cancer, researchers showed that CRTAC1 inactivates the TGF-β pathway by downregulating YY1 expression .
Single-cell approaches offer powerful tools for investigating CRTAC1+ cell populations in complex tissues:
Single-cell RNA sequencing (scRNA-seq):
Spatial transcriptomics:
Maintain tissue context while obtaining single-cell resolution data
Map spatial distribution of CRTAC1+ cells within tissue microenvironments
Correlate CRTAC1 expression with anatomical features or pathological changes
Identify spatial relationships with other cell types
CyTOF (mass cytometry):
Simultaneously analyze >40 protein markers at single-cell resolution
Create high-dimensional phenotypic profiles of CRTAC1+ cells
Identify rare CRTAC1+ subpopulations in heterogeneous samples
Correlate CRTAC1 with activation/functional markers
Single-cell functional assays:
Isolate CRTAC1+ cells by FACS for downstream functional analyses
Perform single-cell cloning to assess functional heterogeneity
Conduct single-cell secretome analysis to identify paracrine factors
Integrated analysis approaches:
Combine multiple single-cell modalities for comprehensive characterization
Integrate with bulk -omics data for validation
Apply computational methods to infer cell-cell communication networks
Use trajectory inference to understand developmental relationships
These approaches would be particularly valuable for understanding the role of CRTAC1+ cells in conditions like spinal ligament degeneration, where single-cell analysis has already revealed intriguing patterns of co-expression with markers like CD44 .
When confronted with seemingly contradictory CRTAC1 expression data across different cancer types, researchers should consider several analytical frameworks:
Tissue-specific baseline expression:
Cancer subtype heterogeneity:
Different molecular subtypes within a cancer type may show distinct CRTAC1 expression patterns
Stratify samples by established molecular classifications
Consider histological subtypes as potential sources of variation
Methodological considerations:
Compare detection methods (RNA-seq, qPCR, Western blot, IHC) used across studies
Account for antibody differences (epitope recognition, sensitivity)
Consider sample preparation variations (fixation methods, processing protocols)
Biological context:
Disease stage and progression:
Temporal dynamics may differ across cancer types
Early vs. late-stage expression patterns may reveal context-dependent roles
Primary vs. metastatic lesions may show different expression profiles
For example, while CRTAC1 is consistently downregulated in both lung adenocarcinoma and bladder cancer , the downstream mechanisms and pathways affected may differ (Ca²⁺-NFAT-STUB1-Akt1 in NSCLC vs. YY1-TGF-β in bladder cancer ), explaining potential functional differences despite similar expression trends.
When analyzing CRTAC1 as a biomarker for cancer prognosis, researchers should employ these statistical approaches:
Survival analysis:
Kaplan-Meier curves stratified by CRTAC1 expression levels
Log-rank tests to assess statistical significance of survival differences
Cox proportional hazards regression for multivariable analysis
Calculation of hazard ratios with confidence intervals
Expression threshold determination:
ROC curve analysis to identify optimal cutoff values
X-tile analysis for unbiased cut-point selection
Consideration of quartiles or median split for categorical classification
Sensitivity analyses using multiple thresholds to ensure robustness
Multivariate modeling:
Include established clinicopathological parameters (stage, grade, age, etc.)
Test for independence of CRTAC1's prognostic value
Develop nomograms or other visual prediction tools
Calculate concordance indices (C-index) to assess predictive accuracy
Subgroup analyses:
Validation approaches:
Internal validation using bootstrapping or cross-validation
External validation in independent cohorts
Comparison with established prognostic biomarkers
Meta-analysis across multiple datasets when available
Integration with other biomarkers:
Development of combined prognostic indices
Assessment of complementarity with other markers
Network-based approaches incorporating pathway information
Machine learning methods for complex pattern recognition
For example, in lung adenocarcinoma research, reduced CRTAC1 expression has been associated with poor prognosis , suggesting its utility as a positive prognostic factor. Statistical robustness of such findings should be ensured through multivariable analysis controlling for established prognostic factors.
Integration of proteomics with transcriptomics provides a comprehensive understanding of CRTAC1 regulation:
Correlation analysis:
Compare CRTAC1 mRNA and protein expression levels across samples
Calculate Pearson or Spearman correlation coefficients
Identify discordant cases suggesting post-transcriptional regulation
Analyze temporal dynamics if time-series data are available
Post-translational modification (PTM) characterization:
Use mass spectrometry to identify PTMs on CRTAC1 protein
Map modifications to functional domains
Correlate PTM patterns with activity or stability
Develop targeted assays for key regulatory modifications
Protein-protein interaction network analysis:
Perform immunoprecipitation-mass spectrometry (IP-MS) to identify CRTAC1 interactors
Construct interaction networks integrating proteomic and transcriptomic data
Identify hub proteins that may regulate CRTAC1
Validate key interactions through orthogonal methods
Proteogenomic integration methods:
Apply computational frameworks specifically designed for multi-omics integration
Use dimensionality reduction techniques to identify patterns across data types
Employ network-based approaches to identify regulatory modules
Implement machine learning algorithms to predict functional relationships
Pathway enrichment analysis:
Protein degradation assessment:
This integrative approach is particularly relevant for CRTAC1, as research has demonstrated important post-transcriptional regulatory mechanisms, such as the protein degradation pathway involving STUB1-mediated Akt1 degradation in NSCLC .
Successful Western blotting of CRTAC1 requires attention to several critical factors:
Sample preparation:
Antibody selection and optimization:
Detection parameters:
Common issues and solutions:
For weak signal: Increase protein loading, reduce antibody dilution, extend exposure time
For high background: Increase blocking time, use more stringent washing, reduce secondary antibody concentration
For multiple bands: Validate with positive controls, consider negative controls (knockdown samples)
For inconsistent results: Standardize protein extraction and quantification methods
Protocol optimization:
Follow manufacturer's specific WB protocol for CRTAC1 antibody
Consider gradient gels for optimal resolution around the target molecular weight
Adjust transfer conditions based on protein size (wet transfer often preferred for >50 kDa proteins)
Optimize blocking conditions (typically 5% non-fat milk or BSA in TBST)
Researchers studying CRTAC1 in clinical samples should be particularly attentive to sample preservation methods, as protein degradation can significantly impact detection of this biomarker.
Optimizing immunohistochemistry (IHC) protocols for CRTAC1 detection requires attention to these key considerations:
Tissue fixation and processing:
Standardize fixation time (typically 24-48 hours in 10% neutral buffered formalin)
Use consistent processing protocols to ensure reproducibility
Consider tissue-specific requirements (lung and brain tissues show reliable CRTAC1 detection)
Optimize section thickness (typically 4-5 μm for FFPE tissues)
Antigen retrieval optimization:
Antibody dilution and incubation:
Detection system selection:
Choose between chromogenic (DAB, AEC) and fluorescent detection based on research needs
For multiplex IHC, ensure compatibility with other antibodies
Select detection systems with appropriate sensitivity for expression level
Consider tyramide signal amplification for weak signals
Controls and validation:
Quantification approaches:
Define clear scoring methods (H-score, percentage positive cells, intensity scale)
Consider digital image analysis for objective quantification
Use multiple independent observers for manual scoring
Document representative images of scoring categories
Following these optimization steps will enable reliable detection of CRTAC1 in tissue specimens, facilitating its use as a diagnostic or prognostic biomarker in cancer research.
Comprehensive validation of CRTAC1 knockdown or overexpression models requires multi-level verification:
Genetic/transcript level validation:
Quantify CRTAC1 mRNA levels using qRT-PCR with validated primers
Design primers spanning exon-exon junctions to avoid genomic DNA amplification
Use multiple reference genes for normalization
For knockdown models, measure efficiency relative to control (scramble siRNA)
Protein level confirmation:
Functional validation:
Specificity controls:
Include rescue experiments (re-express CRTAC1 in knockdown models)
Use multiple siRNA/shRNA sequences targeting different regions
For CRISPR-based knockout, sequence verify the edited region
Test for potential off-target effects on related genes
Stability assessment:
Verify persistence of knockdown/overexpression over experimental timeframe
For stable cell lines, test expression after multiple passages
For inducible systems, characterize kinetics of induction/reversal
Consider clonal variation in stable cell lines
Documentation standards:
Maintain detailed records of construct sequences, cell line origins, and passage numbers
Record complete transfection/transduction protocols
Archive original validation data (unprocessed blot images, qPCR raw data)
Validate phenotypes in multiple cell lines when possible
For example, in NSCLC research, CRTAC1 overexpression was validated by Western blotting and functionally confirmed by demonstrating increased chemosensitivity to cisplatin in multiple cell lines (H1299, HCC827, and H226) . Similarly, knockdown efficiency was verified before conducting functional assays in A549 and H1975 cell lines .
CRTAC1 shows significant potential as a predictive biomarker for chemotherapy response, particularly for platinum-based treatments:
Clinical implementation strategies:
Develop standardized assays for CRTAC1 detection in tumor samples
Establish validated cutoff values for "high" versus "low" expression
Create predictive algorithms incorporating CRTAC1 with other biomarkers
Design prospective clinical trials to validate predictive accuracy
Mechanistic basis for predictive value:
CRTAC1 overexpression increases sensitivity to cisplatin in NSCLC through:
These mechanisms provide a biological rationale for CRTAC1's predictive potential
Multi-drug response prediction:
Higher CRTAC1 expression correlates with increased drug sensitivity beyond platinum agents
Investigate predictive value for other chemotherapeutics with distinct mechanisms
Develop drug-specific prediction models incorporating CRTAC1
Consider combination therapy prediction models
Integration with companion diagnostics:
Explore CRTAC1 testing as a companion diagnostic for specific therapies
Develop point-of-care testing methods for rapid assessment
Integrate with existing biomarker panels for enhanced prediction
Correlate with imaging-based response assessment methods
Resistance mechanism identification:
Study CRTAC1 expression changes in acquired resistance settings
Identify bypass mechanisms in CRTAC1-high non-responders
Develop strategies to overcome resistance in CRTAC1-low patients
Investigate combination approaches targeting CRTAC1-related pathways
Personalized dosing strategies:
Use CRTAC1 levels to guide chemotherapy dosing decisions
Investigate relationship between CRTAC1 expression and optimal drug scheduling
Develop adaptive therapy approaches based on CRTAC1 dynamics
Correlate with pharmacokinetic parameters for optimized exposure
The established relationship between CRTAC1 expression and cisplatin sensitivity in NSCLC provides a strong foundation for developing CRTAC1 as a clinically useful predictive biomarker.
Several emerging technologies offer promising approaches for enhanced CRTAC1 detection and functional characterization:
Digital spatial profiling:
Combines high-plex protein or RNA detection with spatial resolution
Maps CRTAC1 expression within tissue context alongside numerous other markers
Correlates CRTAC1 with microenvironmental features and cell types
Enables region-of-interest selection for focused analysis
Single-molecule imaging techniques:
Super-resolution microscopy (STORM, PALM, STED) for nanoscale localization
Single-molecule FISH for detecting low-abundance CRTAC1 transcripts
Live-cell single-particle tracking to monitor CRTAC1 dynamics
Visualizes CRTAC1 interactions with signaling partners at molecular scale
CRISPR-based functional genomics:
CRISPR activation (CRISPRa) to upregulate endogenous CRTAC1
CRISPR interference (CRISPRi) for precise transcriptional repression
CRISPR screening to identify synthetic lethal interactions with CRTAC1
Base editors or prime editors for introducing specific CRTAC1 variants
Proximity labeling proteomics:
BioID or APEX2 fusion proteins to identify proximal proteins in living cells
Maps the CRTAC1 protein interaction network with spatial resolution
Identifies context-specific interactors in different cellular compartments
Reveals previously unknown functional associations
Organoid and patient-derived xenograft models:
Tests CRTAC1 function in physiologically relevant 3D systems
Preserves tissue architecture and cellular heterogeneity
Enables long-term studies of CRTAC1 in complex environments
Facilitates personalized medicine approaches for CRTAC1-based therapies
Liquid biopsy approaches:
Detects CRTAC1 expression in circulating tumor cells
Monitors tumor-derived exosomes for CRTAC1 protein or mRNA
Enables longitudinal non-invasive monitoring of CRTAC1 status
Correlates with treatment response or disease progression
Application of these technologies would significantly advance our understanding of CRTAC1's role in cancer biology and other pathological conditions, potentially accelerating its clinical translation as both a biomarker and therapeutic target.
Development of CRTAC1-targeting therapeutic strategies for cancer treatment could proceed along several promising avenues:
Expression restoration approaches:
Since CRTAC1 is downregulated in multiple cancers , restoring expression may have therapeutic benefits
Delivery methods could include:
Non-viral gene therapy using lipid nanoparticles
Viral vectors (AAV, lentivirus) for CRTAC1 gene delivery
mRNA therapeutics for transient expression
Small molecules that upregulate endogenous CRTAC1 expression
Pathway modulation strategies:
Target the signaling pathways regulated by CRTAC1:
Combinatorial approaches with chemotherapy:
Given CRTAC1's role in chemosensitivity , develop rational combinations:
CRTAC1 inducers plus cisplatin for enhanced efficacy
Sequential therapy designs (pathway priming followed by cytotoxic agents)
Dosage optimization based on CRTAC1 expression levels
Biomarker-guided patient selection for combination approaches
Immunotherapy integration:
Drug delivery innovations:
Develop targeted delivery systems for CRTAC1-based therapies:
Antibody-drug conjugates targeting cancer-specific markers
Tumor-homing peptides for selective delivery
Stimuli-responsive nanocarriers for tumor-specific release
Local delivery systems for accessible tumors
Companion diagnostics development:
Create paired diagnostic/therapeutic strategies:
CRTAC1 expression assays to guide therapy selection
Pharmacodynamic biomarkers to monitor target engagement
Resistance mechanism profiling for adaptive treatment
Early response indicators for timely intervention adjustment
While these therapeutic strategies are largely conceptual at present, they are grounded in the emerging understanding of CRTAC1's biology in cancer. Particularly promising is the prospect of enhancing chemosensitivity in NSCLC through CRTAC1-targeted approaches, building on established mechanistic insights linking CRTAC1 to cisplatin response .