STC1 Antibody

What is Stanniocalcin 1 (STC1) and why is it important in research?

STC1 is a secreted 35 kDa disulfide-linked homodimeric glycoprotein that functions in diverse biological processes including calcium phosphate homeostasis, cell proliferation, apoptosis, inflammation, oxidative stress responses, and cancer development . It is expressed in a wide variety of tissues and may have autocrine or paracrine functions . The protein has gained significant research interest due to its altered expression in multiple cancer types including breast, ovarian, colorectal, glioma, and bladder cancers . The calculated molecular weight of STC1 is 28 kDa, though it is typically observed at approximately 31 kDa in experimental systems due to post-translational modifications .

What is the genetic location and structure of human STC1?

Human STC1 is encoded by the STC1 gene located on chromosome 8p21-p11.2 as determined by fluorescence in situ hybridization . The gene produces a 247 amino acid protein with a molecular weight of approximately 28 kDa (calculated), although the observed molecular weight in experimental systems is typically around 31 kDa due to glycosylation and other post-translational modifications . The mature STC1 protein forms homodimers through disulfide linkages, which is essential for its biological activity .

Which applications are most suitable for STC1 antibody detection?

STC1 antibodies have been validated across multiple applications with varying effectiveness:

Researchers should optimize the dilution for their specific experimental system, as sample-dependent variations can significantly affect antibody performance .

How should researchers validate STC1 antibody specificity for their experimental system?

Validating antibody specificity is crucial for reliable experimental outcomes. A comprehensive validation approach for STC1 antibodies should include:

• Positive and negative controls:

  • Use tissues known to express STC1 (e.g., mouse small intestine for WB, human cervical cancer for IHC)

  • Include tissues from STC1 knockout models when available

• Multiple detection methods:

  • Compare results across different techniques (WB, IHC, IF)

  • Confirm band size in Western blots (expected at ~31-36 kDa)

• Peptide competition assays:

  • Pre-incubate antibody with blocking peptide to confirm binding specificity

• siRNA/CRISPR validation:

  • Use STC1 knockdown/knockout cells to confirm signal reduction

  • Several publications have utilized KD/KO approaches for validation

• Multiple antibody validation:

  • Compare results using antibodies that target different epitopes of STC1

Recent studies have demonstrated successful validation of STC1 antibodies in various cancer models, including bladder cancer and glioma, using these approaches .

What are the optimal sample preparation protocols for STC1 detection in different applications?

Optimal sample preparation varies by application and tissue type:

For Western Blotting:

• Use RIPA buffer with protease inhibitors for cell/tissue lysis

• Typical protein loading: 20-50 μg per lane

• Reducing conditions are recommended as STC1 forms disulfide-linked dimers

• Observed molecular weight is approximately 31-36 kDa

For Immunohistochemistry:

• Formalin-fixed, paraffin-embedded (FFPE) tissues show good results

• Antigen retrieval is critical:

  • Primary recommendation: TE buffer pH 9.0

  • Alternative: Citrate buffer pH 6.0

• Blocking with 5% normal serum is recommended to reduce background

For Cell-Based Assays:

• 4% paraformaldehyde fixation for 15 minutes at room temperature

• 0.1% Triton X-100 permeabilization for intracellular detection

Proper storage of antibodies (at -20°C, aliquoted to avoid freeze-thaw cycles) is essential for maintaining reactivity and specificity .

How does STC1 expression correlate with tumor progression and patient outcomes?

Multiple studies have demonstrated significant correlations between STC1 expression and cancer progression:

These findings highlight that STC1's prognostic value may be cancer-type specific, requiring careful interpretation within the specific disease context.

What is the relationship between STC1 and immune markers in the tumor microenvironment?

Recent research has uncovered significant correlations between STC1 and various immune markers:

• Immune Checkpoint Molecules:

  • Positive correlations between STC1 and PDL1, PD-L2, OX40L, TIM3, OX40, FOXP3, CTLA4, B7H3 in BLCA

  • Tumors with higher STC1 expression tended to express higher PDL1 levels (p=0.055)

• Immune Cell Markers:

  • STC1 expression showed significant positive correlations with markers of:

    • General T cells (CD3D, CD3E, CD2, CD7)

    • CD8+ T cells (CD8A, CD8B, CD45R)

    • CD4+ T cells (CD4, IL7RA, BTLA, PDCD1)

    • Th1 cells (STAT1, STAT4, CXCR3, CCR5)

    • Th2 cells (CXCR6, CCR3)

    • Th17 cells (STAT3, IL17RA)

    • Regulatory T cells (FOXP3, TGFB, ITGA4, CCR8)

    • B cells (CD20, CD79A, CD79B)

    • Macrophages (various M1 and M2 markers)

    • Neutrophils and dendritic cells

• Functional Analysis:

  • Gene Ontology (GO) analysis of STC1 co-expressed immune genes revealed enrichment in immune-related pathways

  • Majority of immune-related genes (318 of 377) were positively correlated with STC1 expression

These findings suggest STC1 may play a critical role in modulating the immune microenvironment in cancers, potentially affecting immunotherapy responses and highlighting STC1 as a potential therapeutic target.

What are the most effective strategies for quantifying STC1 expression levels in research studies?

Quantification strategies should be selected based on research goals and available resources:

• Protein Level Quantification:

  • Western Blot with densitometry analysis:

    • Recommended for relative quantification

    • Should include housekeeping protein controls (β-actin, GAPDH)

    • Signal must be in linear range for accurate quantification

    • Use at least three biological replicates for statistical validity

  • Immunohistochemistry (IHC) scoring:

    • Immunoreactive score (IRS) method combines staining intensity and percentage of positive cells

    • H-score system (0-300 scale) offers more granular assessment

    • Digital image analysis software can reduce observer bias

    • Example from BLCA study: patients grouped by median IRS score of STC1 showed significant survival differences

  • ELISA for secreted STC1:

    • Most precise quantitative method for serum/medium samples

    • Standard curves must be generated for each experiment

    • Commercial kits available with validated protocols

• mRNA Level Quantification:

  • RT-qPCR:

    • Requires careful primer design specific to STC1

    • Multiple reference genes should be validated for normalization

    • Example from glioma study: RT-qPCR confirmed higher STC1 expression in tumor vs. non-tumor tissues

  • RNA-Seq analysis:

    • Public databases (TCGA, GEO) provide extensive STC1 expression data

    • Should be normalized according to standard bioinformatic protocols

    • Can reveal correlations with other genes and pathways

Each method has specific strengths and limitations, and researchers should consider using multiple approaches for robust quantification.

How can researchers troubleshoot common issues with STC1 immunodetection?

Common challenges and solutions for STC1 detection include:

Additionally, for reproducible results, antibodies should be stored according to manufacturer recommendations, typically at -20°C in aliquots to prevent freeze-thaw cycles. The storage buffer (PBS with 0.02% sodium azide and 50% glycerol pH 7.3) helps maintain antibody stability .

What role does STC1 play in modulating the tumor microenvironment?

Recent studies have uncovered multiple mechanisms through which STC1 influences the tumor microenvironment:

• Immune Regulation:

  • STC1 expression positively correlates with various immune checkpoint molecules including PDL1, PD-L2, and CTLA4

  • Higher STC1 expression correlates with increased infiltration of CD3+ T cells in bladder cancer

  • Gene ontology analysis of STC1 co-expressed genes reveals enrichment in immune function pathways

• Extracellular Matrix Modulation:

  • STC1 is involved in reorganization of the extracellular matrix

  • Significantly correlated with invasion-related proteins in glioma

  • May facilitate tumor cell migration and invasion through matrix remodeling

• Mesenchymal Stromal Cell Interactions:

  • Mesenchymal stromal cells protect cancer cells from ROS-induced apoptosis by secreting STC1

  • STC1 enhances the Warburg effect (aerobic glycolysis) in cancer cells

  • May create a metabolically favorable microenvironment for tumor growth

• Liver Cancer Studies:

  • Stanniocalcin-1 has demonstrated ability to reduce tumor size in hepatocellular carcinoma

  • STC1-overexpressing hepatocellular carcinoma cells affect macrophage migration

These findings suggest STC1 as a potential target for therapeutic interventions aimed at modifying the tumor microenvironment, particularly in combination with immunotherapies targeting checkpoint molecules.

How can STC1 research be integrated with other biomarker studies for improved clinical applications?

Integration of STC1 with other biomarkers offers promising avenues for enhanced clinical applications:

• Multi-marker Panels:

  • Combining STC1 with other prognostic markers can improve predictive accuracy

  • In bladder cancer, integrating STC1 with PDL1 expression may better predict immunotherapy response

  • For glioma, combining STC1 with IDH mutation status could enhance prognostic stratification

• Molecular Subtyping:

  • STC1 expression is enriched in specific molecular subtypes:

    • IDH wild-type gliomas

    • Mesenchymal subtype gliomas

  • Can be used to refine molecular classification systems

• Complementary Biomarker Approaches:

  • Combine protein-level STC1 detection (IHC/WB) with genetic/epigenetic markers

  • In endometrial cancer, STC1 expression correlates with DNA mismatch repair deficiency

  • Integration with genomic data may reveal new mechanistic insights

• Liquid Biopsy Development:

  • As a secreted protein, STC1 has potential as a serum biomarker

  • Developing sensitive ELISA or other detection methods for circulating STC1

  • Could enable non-invasive monitoring of disease progression

• Therapeutic Response Prediction:

  • Given correlations with immune markers, STC1 expression may predict response to immunotherapies

  • Longitudinal studies evaluating STC1 expression before and after treatment could identify patterns associated with therapeutic success or failure

Methodologically, such integrated approaches require careful statistical analysis to account for multiple variables and potential confounding factors, with validation across independent cohorts being essential for clinical translation.