ALDOB (Aldolase B) is an enzyme encoded by the ALDOB gene that plays a critical role in carbohydrate metabolism. It catalyzes the cleavage of fructose-1,6-bisphosphate and fructose-1-phosphate in the glycolytic pathway (GO: 0006096). In February 2018, ALDOB was identified as the most significantly up-regulated transcript among those related to glycolysis in rectal cancer transcriptome analysis. The enzyme is primarily expressed in the liver, kidney proximal tubule cells, and small intestine, where it serves as a key metabolic regulator for fructose processing. Unlike other aldolase isoforms, ALDOB has a distinctly higher catalytic efficiency for fructose-1-phosphate, making it crucial for dietary fructose metabolism in these tissues .
Hereditary fructose intolerance (HFI) is an autosomal recessive disorder caused by mutations in the gene coding for aldolase B. Individuals with HFI develop severe, potentially life-threatening manifestations when exposed to even minute amounts of fructose. The mutations reduce or eliminate ALDOB enzymatic activity, resulting in accumulation of fructose-1-phosphate in hepatocytes and proximal kidney tubule cells following fructose consumption. This accumulation causes rapid ATP depletion, leading to acute hypoglycemia, renal tubular acidosis, and hyperuricemia .
The most common pathogenic variants include c.448G>C (p.Ala150Pro) with an ExAC frequency of 0.2% and c.548T>C (p.Leu183Pro). HFI prevalence in central Europe is estimated at 1:26,100, making heterozygous carriers relatively common. No clear genotype-phenotype correlations have been identified; clinical severity appears dependent on individual nutritional habits .
For comprehensive analysis of ALDOB expression, researchers should implement multiple complementary techniques:
For mRNA quantification:
RNA sequencing (RNA-seq) through databases like TCGA, GEO, and ArrayExpress
Quantitative real-time PCR (qRT-PCR) for validation studies
For protein detection:
Immunohistochemistry (IHC) - Particularly useful for visualizing spatial distribution in tissues
Western blotting for semi-quantitative protein analysis
Proteomic analysis via the Clinical Proteomic Tumor Analysis Consortium (CPTAC)
For structural analysis:
The Human Protein Atlas (HPA) database provides valuable immunohistochemistry images that visualize ALDOB protein expression patterns in normal and pathological tissues. For maximum reliability, researchers should cross-validate findings using both mRNA and protein detection methods to account for potential post-transcriptional regulation .
ALDOB expression shows significant associations with multiple clinical parameters across cancer types:
In rectal cancer patients:
High ALDOB expression correlates with:
In kidney clear cell renal cell carcinoma (KIRC):
ALDOB expression shows significant relationships with:
These correlations, validated through logistic regression analyses, suggest ALDOB may be involved in mechanisms driving disease progression and treatment resistance .
Multiple lines of evidence establish ALDOB as a valuable prognostic biomarker:
In kidney clear cell renal cell carcinoma (KIRC):
ROC analysis demonstrates ALDOB's superior prognostic performance:
Validation methodology:
Multiple independent cohorts (1,070 KIRC tissues and 409 normal tissues) from GEO, TCGA, and ArrayExpress databases
Kaplan-Meier survival analysis with Log-Rank testing
Univariate and multivariate Cox regression analysis identifying ALDOB as an independent prognostic predictor
Construction of nomograms for 1-year, 3-year, and 5-year OS, DSS, and PFS prediction
This extensive validation across multiple datasets consistently identifies ALDOB as a robust prognostic marker, particularly in KIRC, suggesting its potential clinical utility in patient risk stratification .
Researchers can follow this methodological framework to develop ALDOB-integrated prognostic models:
Data collection and preprocessing:
Extract ALDOB expression data and clinicopathological variables from appropriate databases
Apply normalization techniques to ensure comparability across samples
Handle missing data through appropriate imputation methods
Prognostic model development:
Perform univariate Cox regression to identify significant prognostic variables
Use multivariate Cox regression to determine independent predictors
Apply LASSO regression for feature selection among ALDOB and related genes
Nomogram construction:
Integrate T stage, N stage, M stage, AJCC stage, pathological grade, and ALDOB expression
Develop separate nomograms for different survival endpoints (OS, DSS, PFS)
Model validation:
Calculate concordance index (C-index) using 1,000 bootstrap resamples
Generate calibration curves to assess predictive accuracy
Perform internal and external validation using independent cohorts
Statistical analysis tools:
This systematic approach ensures rigorous development and validation of clinically applicable prognostic models incorporating ALDOB expression.
Recent research has uncovered significant relationships between ALDOB expression and the tumor immune microenvironment:
Experimental findings:
In vivo and in vitro experiments demonstrate that ALDOB may regulate tumor growth by modulating CD8+ T cell infiltration
These findings are consistent with computational immune infiltration analyses showing correlations between ALDOB expression and immune cell populations
Analytical approaches for researchers:
Research implications:
ALDOB may have potential reference value for immunotherapy response prediction
Understanding ALDOB's influence on the tumor immune microenvironment could inform therapeutic strategies targeting metabolic pathways in cancer
This emerging area represents a frontier in ALDOB research, linking metabolic functions with immunological processes in the cancer microenvironment.
Researchers investigating epigenetic regulation of ALDOB should focus on these methodological approaches:
m6A methylation analysis:
Examine correlations between ALDOB and 23 types of m6A regulators, including:
Analytical methodologies:
Extract RNA methylation data from appropriate databases
Calculate Pearson correlation coefficients between ALDOB and m6A regulator expression
Apply LASSO regression to identify significant associations
Validate findings using experimental approaches such as:
Methylated RNA immunoprecipitation sequencing (MeRIP-seq)
RNA methylation assays
Gene knockdown/overexpression studies
The contradictory findings regarding ALDOB's roles in different cancers present both challenges and opportunities for researchers. A methodological framework to address these contradictions includes:
Systematic approach for reconciling contradictory findings:
Conduct meta-analysis across cancer types:
Pool data from multiple studies using random-effects models
Perform subgroup analyses by cancer type, stage, and molecular subtype
Identify factors that modify ALDOB's prognostic significance
Investigate tissue-specific contexts:
Compare ALDOB's molecular interactions across tissue types
Analyze protein-protein interaction networks using STRING database
Perform differential pathway enrichment analysis between cancer types
Examine functional mechanisms:
Design experiments to test ALDOB's function in multiple cell line models
Use CRISPR-Cas9 to modulate ALDOB expression in different cancer contexts
Measure metabolic parameters and oncogenic properties
Consider genetic and epigenetic modifiers:
Analyze how genomic alterations affect ALDOB function
Investigate epigenetic regulation patterns across cancer types
Examine interactions with tissue-specific transcription factors
This methodological framework can help researchers systematically investigate and explain why ALDOB might act as a tumor suppressor in some contexts while promoting progression in others .
Researchers should consider this methodological framework when designing experiments to investigate ALDOB's functional impact:
In vitro experimental design:
Cell line selection:
Use multiple cell lines representing the cancer type of interest
Include cell lines with varying baseline ALDOB expression
Consider primary patient-derived cells when available
ALDOB modulation approaches:
Generate stable ALDOB knockdown using shRNA or CRISPR-Cas9
Create ALDOB overexpression models using lentiviral vectors
Consider inducible expression systems for temporal control
Functional assays:
Proliferation: MTT/XTT assays, colony formation, cell counting
Migration/invasion: Transwell assays, wound healing
Metabolism: Seahorse analysis, lactate production, glucose consumption
Apoptosis: Annexin V/PI staining, caspase activity
In vivo experimental design:
Animal models:
Xenograft models using ALDOB-modulated cell lines
Orthotopic implantation for tissue-specific effects
Consider genetically engineered mouse models when appropriate
Analytical endpoints:
Tumor growth kinetics and final tumor volume/weight
Metastatic burden assessment
Survival analysis
Immunohistochemical analysis of harvested tumors
Mechanistic investigations:
Analyze tumor microenvironment changes (CD8+ T cell infiltration)
Examine signaling pathway alterations
Perform metabolomic profiling of tumors
These systematic approaches enable rigorous assessment of ALDOB's functional impact on cancer progression, providing mechanistic insights beyond correlative observations .
Researchers should employ these statistical methodologies when analyzing ALDOB expression in relation to clinical outcomes:
Basic statistical approaches:
Mann-Whitney U test or Student's t-test for comparing expression between two groups
Kruskal-Wallis H test with Dunn's test for multiple group comparisons
Pearson or Spearman correlation for continuous variable associations
Survival analysis methods:
Kaplan-Meier curves with Log-Rank test for survival differences
Cox proportional hazards model for univariate and multivariate analysis
Harrell's concordance index (C-index) for predictive accuracy assessment
Advanced statistical considerations:
Optimal cutpoint determination:
X-tile software or maxstat R package to identify optimal expression thresholds
Validation of cutpoints in independent cohorts
Model development and validation:
Training/validation set approach (typical split: 70%/30%)
Cross-validation techniques (e.g., 10-fold cross-validation)
Bootstrap resampling (1,000 iterations recommended)
Handling confounding factors:
Propensity score matching for balanced comparisons
Stratified analysis by relevant clinical variables
Interaction term analysis in regression models
Statistical software recommendations:
R software (version 4.2.0) with specialized packages:
Statistical significance should typically be set at P < 0.05, with appropriate multiple testing corrections when necessary.
Researchers can optimize mass spectrometry protocols for ALDOB analysis following these methodological guidelines:
Sample preparation optimization:
Tissue processing:
Flash-freeze samples immediately after collection
Consider laser capture microdissection for cellular specificity
Optimize protein extraction buffers (RIPA vs. urea-based) for ALDOB recovery
Protein digestion protocols:
Compare trypsin, Lys-C, and combination digestion approaches
Optimize enzyme-to-protein ratios (typically 1:20 to 1:100)
Consider extended digestion times (12-16 hours) at controlled temperatures
Enrichment strategies:
Evaluate immunoprecipitation with ALDOB-specific antibodies
Test fractionation methods (SCX, high-pH RP) to reduce sample complexity
Consider phosphopeptide enrichment to study ALDOB post-translational modifications
MS acquisition parameters:
MS instrument selection:
High-resolution instruments (Orbitrap, Q-TOF) for discovery phase
Triple quadrupole instruments for targeted quantification
Acquisition methods:
Data-dependent acquisition (DDA) for discovery
Parallel reaction monitoring (PRM) or multiple reaction monitoring (MRM) for targeted quantification
Data-independent acquisition (DIA) for comprehensive peptide coverage
ALDOB-specific considerations:
Target multiple unique peptides across different regions of ALDOB
Include both common and variant-specific peptides when analyzing genetic variants
Monitor post-translational modifications (phosphorylation, acetylation)
Quantification strategies:
Relative quantification:
Label-free quantification using MS1 intensity or spectral counting
Isobaric labeling (TMT, iTRAQ) for multiplexed comparison
Absolute quantification:
Stable isotope-labeled standard (SIS) peptides for ALDOB
AQUA peptide approach for precise quantification
QconCAT strategy for multi-peptide quantification
These optimized mass spectrometry approaches enable reliable detection and quantification of ALDOB protein in clinical samples, facilitating translational research applications .
When facing discrepancies between ALDOB mRNA and protein expression, researchers should implement these methodological approaches:
Analytical framework for resolving mRNA-protein discrepancies:
Validation of measurement techniques:
Confirm antibody specificity through multiple approaches:
Western blot with recombinant protein controls
Knockdown/overexpression validation
Multiple antibodies targeting different epitopes
Validate RNA measurement methods:
qRT-PCR with multiple primer sets
RNA-seq with appropriate quality controls
In situ hybridization for spatial validation
Investigation of post-transcriptional mechanisms:
microRNA regulation:
Identify miRNAs targeting ALDOB through bioinformatic prediction
Perform correlation analysis between miRNA and ALDOB expression
Conduct luciferase reporter assays to validate direct targeting
RNA stability analysis:
Actinomycin D chase experiments to measure ALDOB mRNA half-life
RNA-binding protein immunoprecipitation to identify regulators
Analysis of alternative splicing patterns
Protein-level regulation assessment:
Proteasomal degradation:
Proteasome inhibitor studies (MG132, bortezomib)
Ubiquitination analysis via immunoprecipitation
Half-life determination via cycloheximide chase
Post-translational modifications:
Phosphorylation, acetylation, or glycosylation analysis
Mass spectrometry to identify modification sites
Functional impact assessment of modifications
Integrative data analysis:
Stratify samples by mRNA-protein correlation status
Identify clinical or molecular features associated with discrepancies
Develop multivariate models incorporating both mRNA and protein data
This systematic approach helps researchers uncover biological mechanisms underlying ALDOB regulation and ensures accurate interpretation of seemingly contradictory expression data .
Implementation of ALDOB testing in clinical pathology requires standardized protocols and careful workflow integration:
Clinical implementation framework:
Specimen requirements and processing:
Tissue: FFPE or fresh frozen tumor sections (recommended minimum: 1 cm²)
Blood: Plasma or serum (potential circulating tumor DNA analysis)
Processing timeline: Within 30 minutes of collection for fresh samples
Fixation protocol: 10% neutral buffered formalin, 6-24 hours for optimal IHC results
Testing methodologies with clinical validity:
Immunohistochemistry:
Antibody selection: Validated antibodies with demonstrated specificity
Scoring system: H-score (0-300) with median cutoff (e.g., 195) for high vs. low expression
Quality controls: Positive (liver tissue) and negative controls on each slide
RT-qPCR:
Validated primer sets targeting conserved ALDOB regions
Reference gene normalization (GAPDH, ACTB, B2M)
Established Ct thresholds for expression categorization
Reporting standards:
Standardized terminology for expression levels
Inclusion of relevant prognostic and predictive information
Integration with existing molecular pathology reporting
Quality assurance measures:
Inter-laboratory proficiency testing
Regular concordance testing between methods
Slide exchange programs for IHC standardization
Implementation timeline:
Validation phase: 3-6 months
Limited clinical implementation: 6-12 months
Full integration into routine practice: 12-18 months
This structured approach ensures reliable, clinically meaningful ALDOB testing that can inform treatment decisions and prognostication .
To rigorously evaluate ALDOB as a predictive biomarker, researchers should implement this methodological framework:
Optimal study design elements:
Prospective-retrospective design (initial validation):
Utilize archived specimens from completed randomized trials
Ensure treatment arms with and without the therapy of interest
Implement blinded ALDOB assessment
Predefine statistical analysis plan and cutpoints
Prospective observational study (clinical validation):
Multi-institutional cohort with standardized treatment protocols
Baseline ALDOB assessment before treatment initiation
Predefined response criteria (RECIST 1.1, pathological response)
Minimum follow-up period appropriate for the cancer type
Prospective interventional trial (clinical utility):
Biomarker-stratified design or biomarker-strategy design
Power calculations based on preliminary data
Incorporation of ALDOB status in treatment decision algorithm
Collection of quality of life and economic outcomes
Statistical considerations:
Sample size calculation accounting for expected biomarker prevalence
Interaction testing between ALDOB status and treatment effect
Multivariable analysis adjusting for known prognostic factors
Predefined subgroup analyses based on molecular or clinical features
Biospecimen considerations:
Collection at multiple timepoints (baseline, during treatment, progression)
Multiple testing methodologies (IHC, RNA-seq) for cross-validation
Central laboratory assessment with rigorous quality control
Exploration of dynamic changes in ALDOB expression during treatment
This comprehensive approach provides the methodological rigor needed to establish ALDOB as a clinically useful predictive biomarker .
Researchers exploring ALDOB-targeted therapeutics should consider these methodological approaches:
Therapeutic targeting strategies:
Direct enzymatic inhibition:
Structure-based drug design utilizing AlphaFold-predicted ALDOB structure
High-throughput screening of small molecule libraries
Allosteric modulators targeting regulatory sites
Validation in enzymatic assays with purified ALDOB protein
Gene expression modulation:
RNA interference approaches (siRNA, shRNA)
CRISPR-Cas9 gene editing (knockout, knockdown)
Antisense oligonucleotides targeting ALDOB mRNA
Epigenetic modulators affecting ALDOB promoter methylation
Protein-protein interaction disruption:
Identification of critical ALDOB interaction partners via proteomic approaches
Peptide mimetics targeting interaction interfaces
Small molecule disruptors of protein complexes
Validation using co-immunoprecipitation and FRET assays
Metabolic pathway intervention:
Targeting upstream or downstream metabolites in ALDOB pathway
Synthetic lethality approaches in ALDOB-high tumors
Combination with other metabolic inhibitors
Metabolic flux analysis to confirm mechanism of action
Experimental validation hierarchy:
In vitro screening in multiple cell line models
Ex vivo testing in patient-derived organoids
In vivo efficacy in xenograft and syngeneic models
Toxicity assessment in appropriate animal models
Combination studies with standard-of-care treatments
These approaches provide a structured framework for developing ALDOB-targeted therapeutic strategies with potential for clinical translation .
To investigate ALDOB's role in metabolic reprogramming, researchers should implement these methodological approaches:
Experimental framework for metabolic studies:
Metabolic profiling techniques:
Targeted LC-MS/MS for glycolytic intermediates and related metabolites
13C-glucose and 13C-fructose tracing to track carbon flux
Seahorse analysis for glycolytic rate and mitochondrial respiration
NMR-based metabolomics for comprehensive metabolite detection
Enzyme activity assessments:
Spectrophotometric assays for ALDOB enzymatic activity
Metabolic flux analysis using isotope-labeled substrates
In situ enzyme activity measurements in tissue sections
Correlation of activity with protein/mRNA expression levels
Metabolic pathway analysis:
Gene set enrichment analysis focusing on metabolic pathways
Protein-protein interaction mapping with other metabolic enzymes
Regulatory network analysis of metabolism-related transcription factors
Integration with publicly available metabolic datasets
Functional metabolic studies:
Glucose/fructose dependency assays under ALDOB modulation
Mitochondrial function assessment after ALDOB knockdown/overexpression
Lipid metabolism analysis in ALDOB-altered cells
Nutrient deprivation studies to assess metabolic flexibility
Analytical considerations:
Temporal dynamics of metabolic changes after ALDOB modulation
Microenvironmental factors (oxygen, pH, nutrient availability)
Comparison between 2D cultures and 3D models
Integration of metabolomic, transcriptomic, and proteomic data
This comprehensive approach enables detailed characterization of ALDOB's role in cancer metabolic reprogramming, potentially revealing vulnerabilities that could be therapeutically exploited .
Researchers investigating ALDOB's protein interactions should employ this comprehensive methodological approach:
Interactome analysis workflow:
Affinity purification-mass spectrometry (AP-MS):
Endogenous ALDOB immunoprecipitation with validated antibodies
Tagged-ALDOB (FLAG, HA, GFP) expression and pull-down
Quantitative comparison between cancer and normal cells
SILAC or TMT labeling for differential interaction analysis
Proximity-based labeling methods:
BioID: ALDOB-BirA* fusion for biotinylation of proximal proteins
APEX2-ALDOB fusion for peroxidase-mediated labeling
Split-BioID for detecting conditional interactions
Controlled expression using inducible systems
Protein-fragment complementation assays:
Mammalian two-hybrid screening
Bimolecular fluorescence complementation (BiFC)
NanoBiT complementation for dynamic interaction monitoring
FRET/BRET approaches for real-time interaction studies
Crosslinking mass spectrometry (XL-MS):
Chemical crosslinking of intact cells or purified complexes
MS/MS analysis to identify crosslinked peptides
Structural modeling of interaction interfaces
Comparison between different cellular contexts
Computational analysis pipeline:
Filtering against CRAPome database to remove common contaminants
Network visualization using Cytoscape or STRING
Gene Ontology enrichment analysis of interaction partners
Structural modeling of protein complexes using AlphaFold-Multimer
Validation strategies:
Co-immunoprecipitation of key interactions
Proximity ligation assay in tissue sections
Mutagenesis of putative interaction domains
Functional studies of disrupted interactions
This systematic approach provides a comprehensive view of ALDOB's protein interaction network in cancer cells, potentially revealing novel regulatory mechanisms and therapeutic targets .
To systematically address contradictory findings about ALDOB's role across cancer types, researchers should implement this experimental framework:
Comprehensive experimental design strategy:
Standardized multi-cancer cell line panel assessment:
Select representative cell lines from ≥5 cancer types with contradictory ALDOB findings
Implement identical ALDOB modulation approaches across all lines
Measure consistent endpoints using standardized protocols
Create an "ALDOB effect score" normalizing impact across cancer types
Context-dependent mechanism investigation:
Perform comparative phosphoproteomic analysis across cancer types
Analyze differential gene expression after ALDOB modulation
Map metabolic dependencies using CRISPR screening
Identify cancer-specific interaction partners
Genetic background analysis:
Sequence cancer cells for mutations in ALDOB-related pathways
Engineer isogenic cell lines differing only in key genetic alterations
Assess how genetic context modifies ALDOB function
Perform synthetic lethality screens in different genetic backgrounds
Microenvironmental influence evaluation:
Test ALDOB function under varying oxygen tensions
Assess impact of pH, nutrient availability, and ECM components
Co-culture with cancer-specific stromal and immune cells
Develop appropriate 3D models mimicking tissue-specific TME
Analytical integration framework:
Develop computational models to predict ALDOB behavior based on cellular context
Perform meta-analysis across all experimental conditions
Identify decision trees for ALDOB function based on context
Generate testable hypotheses explaining contradictory findings
This systematic approach allows researchers to methodically dissect the factors determining ALDOB's differential roles across cancer contexts, providing a cohesive understanding of its complex biology .
Aldolase B catalyzes the reversible cleavage of fructose 1,6-bisphosphate (FBP) into glyceraldehyde 3-phosphate and dihydroxyacetone phosphate (DHAP). It also catalyzes the reversible cleavage of fructose 1-phosphate (F1P) into glyceraldehyde and dihydroxyacetone phosphate . This dual functionality is essential for the metabolism of fructose and the regulation of glycolytic and gluconeogenic pathways.
Aldolase B is predominantly expressed in the liver, kidney, and intestine. In contrast, Aldolase A is primarily found in muscle and erythrocytes, while Aldolase C is expressed in the brain . The expression pattern of these isozymes is tightly regulated and reflects their specialized roles in different tissues.
Human recombinant Aldolase B is produced using recombinant DNA technology, which involves inserting the human ALDOB gene into a suitable expression system, such as bacteria or yeast. This allows for the large-scale production of the enzyme for research and therapeutic purposes. Recombinant Aldolase B retains the same structural and functional properties as the native enzyme, making it a valuable tool for studying fructose metabolism and related disorders.