The ARL4C antibody is a diagnostic and research tool designed to detect the expression of ADP-ribosylation factor-like 4C (ARL4C), a small GTP-binding protein implicated in cancer progression and immune regulation. Its development has enabled researchers to map ARL4C expression in tumor tissues and correlate it with clinical outcomes, as demonstrated in studies across multiple cancer types .
3.1. Prognostic Biomarker Studies
ARL4C antibodies have been pivotal in identifying high expression levels of ARL4C in aggressive cancers. Key findings include:
| Cancer Type | ARL4C Expression | Prognostic Correlation | Source |
|---|---|---|---|
| Bladder (BLCA) | High | Poor OS and PFS | |
| Lung (LUAD) | High | Poor RFS, PFS | |
| Colorectal (COAD) | High | Poor OS |
3.2. Immune Microenvironment Analysis
Using ARL4C antibodies, researchers linked its expression to tumor-associated macrophages (TAMs) and immune activation. Data from revealed:
TAM infiltration: High ARL4C expression correlates with increased CD68+ macrophages in tumor stroma.
Immune activation: ARL4C+ tumors show elevated granzyme B+ cytotoxic T cells, suggesting adaptive immune responses .
4.1. Drug Sensitivity
ARL4C antibodies facilitated studies linking its expression to tumor sensitivity to:
Staurosporine: 2.4-fold increased sensitivity in ARL4C-high tumors (P < 0.001) .
Midostaurin: 1.8-fold sensitivity enhancement in colorectal cancers .
4.2. Targeted Therapies
While no ARL4C-specific therapies are FDA-approved, preclinical models using anti-ARL4C antisense oligonucleotides (ASO-1316) showed tumor growth inhibition in KRAS/EGFR-mutant lung adenocarcinoma .
5.1. Lung Adenocarcinoma
A retrospective cohort of 161 patients (2011–2018) using ARL4C antibodies demonstrated:
High expression (>20% tumor area): 66.7% in atypical adenomatous hyperplasia (AAH), progressing to invasive adenocarcinoma .
Survival correlation: Multivariate analysis identified ARL4C as an independent risk factor for relapse-free survival (HR = 2.30, P = 0.0341) .
5.2. Pancreatic Cancer
In xenograft models, ARL4C antibodies confirmed protein localization in invasive tumor regions, supporting its role in metastasis .
Antibody specificity: Cross-reactivity with other ARF/ARL family proteins requires validation.
Clinical translation: Prospective trials are needed to validate ARL4C as a predictive marker for immunotherapy or targeted drugs.
The ARL4C antibody (10202-1-AP) has been validated for multiple applications:
| Application | Validated In | Recommended Dilution |
|---|---|---|
| Western Blot (WB) | HUVEC cells, human brain tissue | 1:500-1:1000 |
| Immunoprecipitation (IP) | HUVEC cells | 0.5-4.0 μg for 1.0-3.0 mg of total protein lysate |
| Immunohistochemistry (IHC) | Human colon cancer tissue, human pancreas tissue | 1:50-1:500 |
| Immunofluorescence (IF)/ICC | HUVEC cells | 1:50-1:500 |
| ELISA | Human samples | Application-dependent |
The antibody has demonstrated reactivity with human samples, with cited reactivity in both human and mouse tissues .
For optimal results in immunohistochemistry using ARL4C antibody (10202-1-AP), antigen retrieval with TE buffer at pH 9.0 is suggested. Alternatively, antigen retrieval may be performed with citrate buffer at pH 6.0. For paraffin-embedded tissue sections, the recommended antibody dilution is 1:50-1:500. The calculation of IHC density should involve determining the ratio between the intensity of BCA and the size of the area . Specific protocols are available from the manufacturer for optimal staining conditions. It is important to note that studies involving human tissues should be conducted in accordance with institutional ethics committee approval and with proper informed consent .
Optimization of ARL4C antibody dilutions requires systematic titration in each testing system to obtain optimal results. Start with the recommended dilution ranges:
For Western Blot: Begin with 1:500 dilution and adjust based on signal-to-noise ratio
For IHC: Start at 1:100 and adjust based on staining intensity and background
For IF/ICC: Initial testing at 1:100 is recommended, with adjustments for optimal visualization
The optimal dilution is sample-dependent, and researchers should check validation data galleries provided by manufacturers. When working with new sample types or tissues, a dilution series experiment is recommended to determine optimal conditions. For quantitative applications, standard curves with positive controls at known dilutions should be established .
For successful Western blot detection of ARL4C:
Sample preparation: Use appropriate lysis buffers that preserve protein integrity (HUVEC cells and human brain tissue are validated positive controls)
Protein loading: Load 20-40 μg of total protein per lane
Resolution: Use 12-15% SDS-PAGE gels to properly resolve the 21-25 kDa ARL4C protein
Transfer: Optimize transfer conditions for proteins in this molecular weight range
Blocking: Use 5% non-fat milk or BSA in TBST for 1-2 hours at room temperature
Primary antibody: Incubate with ARL4C antibody (1:500-1:1000 dilution) overnight at 4°C
Detection: Use HRP-conjugated secondary antibodies and ECL detection systems
When interpreting results, note that the calculated molecular weight of ARL4C is 21 kDa, but the observed molecular weight ranges from 21-25 kDa, possibly due to post-translational modifications .
When designing experiments with ARL4C antibody in cancer research, include the following controls:
Positive tissue controls: HUVEC cells for WB/IP/IF; human colon cancer and pancreas tissues for IHC
Negative controls: Tissues or cells known to have low or no ARL4C expression
Knockdown/knockout controls: ARL4C KD/KO samples to validate antibody specificity
Isotype controls: Rabbit IgG at equivalent concentrations to assess non-specific binding
Loading controls: For WB, include appropriate housekeeping proteins
Technical replicates: Minimum of three to account for technical variability
Biological replicates: Samples from different patients/sources to account for biological variation
Published literature indicates successful application of ARL4C knockdown approaches in several studies, which can serve as methodological references .
ARL4C expression demonstrates significant prognostic value across multiple cancer types. High ARL4C expression is associated with poor prognosis in several cancers:
Bladder urothelial carcinoma (BLCA)
Colon adenocarcinoma (COAD)
Kidney renal papillary cell carcinoma (KIRP)
Brain lower grade glioma (LGG)
Uterine corpus endometrial carcinoma (UCEC)
To comprehensively study ARL4C alterations in cancer tissues, researchers can employ multiple complementary approaches:
Expression analysis:
RNA-seq or microarray analysis (using log2 TPM+1 transformation)
qRT-PCR for mRNA quantification
Western blot and IHC for protein expression
Genetic alterations:
Whole exome/genome sequencing to identify mutations (particularly relevant in sarcoma, brain lower grade glioma, and esophageal adenocarcinoma)
Copy number variation analysis
Epigenetic regulation:
Methylation analysis of the ARL4C promoter, especially in BRCA, COAD, KIRP, and LIHC (positive correlation)
Chromatin immunoprecipitation to study transcription factor binding
Functional studies:
Knockdown/knockout experiments using siRNA, shRNA, or CRISPR-Cas9
Pathway analysis focusing on Wnt/β-Catenin signaling
Single-cell analysis:
To validate the functional role of ARL4C in tumor progression, researchers should implement a multi-faceted experimental approach:
In vitro functional assays:
Proliferation assays after ARL4C knockdown/overexpression
Migration and invasion assays (particularly relevant as ARL4C has been shown to influence EMT phenomena)
Colony formation and spheroid assays to assess stem cell-like properties
Cell cycle and apoptosis analysis
Molecular mechanism investigation:
Co-immunoprecipitation to identify binding partners
Pathway analysis focusing on Wnt/β-Catenin signaling, which has been implicated in ARL4C-mediated effects in kidney cancer
Downstream target gene expression analysis
In vivo validation:
Xenograft models with ARL4C-modulated cancer cells
Patient-derived xenografts (PDXs) with varying ARL4C expression levels
Analysis of tumor growth, metastasis, and survival outcomes
Clinical correlation:
Correlation of experimental findings with patient data from TCGA or local cohorts
Integration of ARL4C expression with clinical parameters and outcomes
Relevant experimental precedents can be found in studies investigating ARL4C in kidney cancer cell lines, where knockdown of ARL4C inhibited proliferation, migration, and invasion through Wnt/β-Catenin pathway regulation .
ARL4C expression shows significant correlations with immune cell infiltration in the tumor microenvironment (TME), providing important insights for cancer immunology research:
ARL4C is expressed in various immune cells, including:
CD4+ T lymphocytes
CD8+ T lymphocytes
Natural killer (NK) cells
Monocytes
Macrophages
Analysis methods for studying this relationship include:
ESTIMATE algorithm to calculate stromal and immune cell scores
TIMER2.0 database and CIBERSORT algorithm for immune cell infiltration correlation analysis
Single-sample Gene Set Enrichment Analysis (ssGSEA) for classifying high and low ARL4C expression groups and assessing immune cell infiltration
High ARL4C expression correlates with cancer immune activation, highlighting its potential role in regulating the immune microenvironment of tumors
Immunofluorescence (IF) can be used to validate co-localization of ARL4C with immune cell markers in tissue samples, with the IF density determined by the ratio between the fluorescence intensity of positive cells and that of DAPI .
To investigate ARL4C's role in tumor immune escape mechanisms, researchers can employ the following approaches:
Analysis of immune checkpoint correlation:
Evaluate correlation between ARL4C expression and known immune checkpoint molecules (PD-1, PD-L1, CTLA-4, etc.)
Use flow cytometry or multiplex IHC to quantify checkpoint expression in ARL4C-high vs. ARL4C-low tumors
Immune dysfunction and exclusion analysis:
Utilize the TIDE (Tumor Immune Dysfunction and Exclusion) database to analyze ARL4C-associated immune escape in tumors
Assess T cell exclusion and dysfunction signatures in relation to ARL4C expression
Tumor mutation burden (TMB) and microsatellite instability (MSI) analysis:
Calculate TMB scores from somatic mutation data
Use Spearman's correlation coefficient to examine associations between ARL4C expression and either TMB or MSI
Functional validation:
Co-culture experiments with tumor cells and immune cells under ARL4C manipulation
In vivo models with immune-competent mice to assess ARL4C's effect on anti-tumor immunity
Analysis of cytokine/chemokine profiles in ARL4C-high versus ARL4C-low tumors
Single-cell RNA sequencing:
Integration of ARL4C expression data with immunotherapy response prediction involves several sophisticated analytical approaches:
Predictive analysis frameworks:
TISMO database for ARL4C-related immunotherapy prediction in mouse samples
TIDE algorithm to predict clinical response to immune checkpoint blockade
Gene expression correlation analysis:
Correlation of ARL4C expression with established immunotherapy response biomarkers
GSEA enrichment analysis using Hallmark gene sets from MSigDB to compute normalized enrichment scores (NES) and false discovery rates (FDR) for differentially expressed genes
Drug sensitivity correlation:
Analysis of ARL4C expression in relation to sensitivity to specific immunotherapy drugs
Studies have shown positive correlation between ARL4C expression and heightened sensitivity to Staurosporine, Midostaurin, and Nelarabine
Clinical data integration:
Stratification of patient cohorts by ARL4C expression levels
Analysis of differential treatment outcomes in immunotherapy clinical trials
Multi-omics integration:
Combine ARL4C expression data with other molecular features (mutation, methylation, etc.)
Develop predictive models incorporating multiple biomarkers for enhanced accuracy
These approaches collectively provide a framework for exploring ARL4C as a potential predictive biomarker for immunotherapy response, particularly in cancers where ARL4C demonstrates significant prognostic value .
Troubleshooting inconsistent ARL4C staining patterns in immunohistochemistry requires systematic analysis of several factors:
Fixation issues:
Ensure consistent fixation time (recommended: 24-48 hours in 10% neutral buffered formalin)
Avoid over-fixation which can mask epitopes
Consider testing different fixatives if working with specialized tissues
Antigen retrieval optimization:
Primary recommendation: TE buffer at pH 9.0
Alternative: Citrate buffer at pH 6.0
Test different retrieval times (15, 20, and 30 minutes)
Compare heat-induced versus enzymatic retrieval methods
Antibody-related factors:
Titrate antibody concentration (1:50, 1:100, 1:200, 1:500)
Extend primary antibody incubation time (overnight at 4°C may yield more consistent results)
Test different detection systems (ABC, polymer-based)
Consider lot-to-lot variability; validate each new lot against known positive controls
Tissue-specific considerations:
Different cancer types may require adjusted protocols
Note that ARL4C staining has been validated in human colon cancer and pancreas tissues
Consider tissue-specific background reduction strategies
Quantification approach:
When studying ARL4C in both normal and cancer tissues comparatively, employ these best practices:
Sample selection and preparation:
Use matched pairs of tumor and adjacent normal tissue from the same patient whenever possible
Ensure consistent processing of both normal and tumor samples
Consider tissue microarrays (TMAs) for high-throughput analysis
Multi-modal analysis:
Combine IHC/IF with mRNA expression analysis
Validate protein expression changes with transcript levels
Use laser capture microdissection to isolate specific cell populations
Controls and standardization:
Include known positive controls (e.g., HUVEC cells, human brain tissue)
Use the same antibody lot, dilutions, and protocols for all comparative analyses
Implement blinded scoring by multiple observers
Quantitative assessment:
Use digital pathology tools for objective quantification
Analyze subcellular localization patterns in addition to expression levels
Correct for cell density differences between normal and tumor tissues
Data integration:
Correlate tissue findings with public datasets (TCGA, GTEx)
Compare with cancer cell line data from CCLE database
Control for potential confounding factors (age, gender, treatment history)
Research has shown significantly higher ARL4C expression in 23 out of 33 cancer types compared to normal tissues, with particularly elevated levels in thymic epithelial tumors (THYM), cholangiocarcinoma (CHOL), and ovarian cancer (OV) .
Single-cell techniques offer powerful approaches to study ARL4C expression heterogeneity in tumors:
Single-cell RNA sequencing (scRNA-seq):
Dissociate fresh tumor samples into single-cell suspensions
Sort cells using FACS to enrich for specific populations if needed
Process through 10x Genomics or similar platforms
Apply computational analysis to:
Identify cell clusters with differential ARL4C expression
Correlate with cell type-specific markers
Analyze expression in pre- and post-treatment samples using Mann-Whitney U test
Spatial transcriptomics:
Apply techniques like Visium (10x Genomics) or GeoMx DSP (NanoString)
Map ARL4C expression patterns within the spatial context of the tumor
Correlate with histological features and tumor regions
Single-cell protein analysis:
Use CyTOF (mass cytometry) to simultaneously measure ARL4C with other markers
Apply multiplex immunofluorescence to visualize ARL4C in different cell populations
Calculate IF density as the ratio between fluorescence intensity of positive cells and DAPI
Integrated analysis:
Combine scRNA-seq with surface protein measurements (CITE-seq)
Correlate ARL4C expression with functional states of cells
Track clonal evolution and ARL4C expression changes during tumor progression
Data analysis considerations:
Apply appropriate normalization methods for single-cell data
Use dimensional reduction techniques (tSNE, UMAP) for visualization
Implement trajectory analysis to identify developmental relationships between cell populations
These approaches can reveal heterogeneous expression patterns of ARL4C in both tumor and immune cells, providing insights into its role in different cellular compartments within the tumor microenvironment .
Incorporating ARL4C expression analysis into precision oncology approaches can enhance patient stratification and treatment selection:
Biomarker development:
Establish standardized IHC protocols for clinical implementation
Develop RNA-based tests for ARL4C expression quantification
Validate cutoff values for "high" versus "low" expression across different cancer types
Patient stratification:
Use ARL4C expression levels to identify high-risk patients in cancer types where it has prognostic value (BLCA, COAD, KIRP, LGG, UCEC)
Incorporate ARL4C with other established biomarkers in multi-parameter prognostic models
Adjust risk assessment based on cancer-specific ARL4C roles
Treatment selection:
Correlate ARL4C expression with drug sensitivity profiles
Patients with high ARL4C expression may show increased sensitivity to Staurosporine, Midostaurin, and Nelarabine
Develop companion diagnostics for ARL4C-targeted therapies
Monitoring response:
Track ARL4C expression changes during treatment
Evaluate ARL4C expression in circulating tumor cells or cell-free DNA
Correlate expression changes with treatment outcomes
Implementation considerations:
Establish quality control parameters for clinical testing
Integrate with existing molecular pathology workflows
Develop standardized reporting formats for clinicians
Given ARL4C's correlation with immunotherapy response and drug sensitivity, its assessment could become a valuable component of comprehensive molecular tumor profiling .
The relationship between ARL4C genetic alterations and cancer development reveals important mechanistic insights:
Mutation patterns:
High frequency of ARL4C alterations in sarcoma, brain lower grade glioma, and esophageal adenocarcinoma
Mutations play a critical role in the progression of tumorigenesis across these cancer types
Epigenetic regulation:
Positive correlation between ARL4C expression and promoter methylation in breast cancer (BRCA), colon adenocarcinoma (COAD), kidney renal papillary cell carcinoma (KIRP), and liver hepatocellular carcinoma (LIHC)
Negative correlation in testicular germ cell tumors (TGCT), uterine corpus endometrial carcinoma (UCEC), lung squamous cell carcinoma (LUSC), and kidney renal clear cell carcinoma (KIRC)
Pathway interactions:
ARL4C functions through the Wnt/β-Catenin pathway in kidney cancer
Knockdown of ARL4C inhibits various EMT phenomena including proliferation, migration, and invasion in kidney cancer cell lines
Dual roles in cancer:
Pro-tumorigenic effects in multiple cancer types
Potential tumor suppressor role in ovarian cancer, where high expression may impede cell migration
Research methods:
Access mutational data through the UCSC Xena database
Analyze promoter methylation patterns in relation to expression
Perform pathway analysis to understand the functional consequences of genetic alterations
This complex relationship highlights the context-dependent nature of ARL4C function across different cancer types and suggests the need for cancer-specific approaches to targeting ARL4C .