STE14 Antibody

What is ST14/Matriptase and what experimental applications are ST14 antibodies suitable for?

ST14/Matriptase is a serine protease that cleaves and activates hepatocyte growth factor/scattering factor and urokinase plasminogen activator . It functions primarily in epithelial tissues including skin and thymus, with important roles in maintaining epithelial integrity and mediating epithelial-mesenchymal transition (EMT) .

ST14 antibodies are validated for multiple research applications including:

• Immunohistochemistry on paraffin-embedded tissues (10 μg/ml)

• Immunofluorescence (1:100-1:500 dilution)

• Western blot analysis (1:500-1:1000 dilution)

• ELISA (1:10000 dilution)

These applications enable researchers to investigate ST14 expression and localization in various experimental models, with validated results in human tissues including prostate, small intestine, and cell lines such as A549 .

How should researchers optimize ST14 antibody protocols for immunohistochemistry studies?

For optimal immunohistochemistry (IHC) results with ST14 antibodies, researchers should follow these methodological guidelines:

• Use formalin-fixed, paraffin-embedded tissue sections

• Perform heat-induced antigen retrieval to expose epitopes masked during fixation

• Apply primary ST14 antibody at the recommended concentration (10 μg/ml)

• Include positive control tissues such as human small intestine or prostate

Validation experiments show distinct staining patterns in human small intestine and prostate tissues, with epithelial-specific localization . For reproducible results, optimize antibody concentration and incubation time based on your specific tissue type, as epitope accessibility may vary between tissues.

What controls should be included when validating ST14 antibody specificity?

When validating ST14 antibody specificity, include these critical controls:

• Peptide competition assay: Pre-incubate antibody with synthesized peptide corresponding to the target epitope before application to demonstrate specificity. Search results show that Western blot and immunofluorescence experiments included lanes/images treated with synthesized peptide as specificity controls .

• Positive control tissues/cells: Include samples known to express ST14, such as A549 cells for Western blot and immunofluorescence or prostate/small intestine tissues for IHC .

• Negative control: Omit primary antibody while maintaining all other steps of the protocol to assess background staining.

• Cross-validation: Compare results across multiple detection methods (e.g., IF, WB, IHC) to confirm consistent expression patterns.

These validation steps ensure reliable detection of ST14 in research applications, preventing misinterpretation of results due to antibody cross-reactivity.

How does ST14 expression correlate with breast cancer progression and patient survival?

Analysis of breast cancer patient data reveals significant correlations between ST14 expression and clinical outcomes:

This data demonstrates that ST14/Prss14 is a strong prognostic marker for breast cancer, particularly in ER negative and triple negative subtypes, where high expression indicates significantly poorer survival outcomes . Researchers should consider ST14 expression when stratifying patients in clinical studies, especially for ER negative populations.

What is the relationship between ST14 and epithelial-mesenchymal transition (EMT) in cancer progression?

ST14/Prss14 plays a critical role in epithelial-mesenchymal transition, a process fundamental to cancer metastasis:

• Studies demonstrate that ST14/Prss14 is "necessary and sufficient for epithelial mesenchymal transition"

• In clustering analyses of 1085 EMT signature genes, ST14/Prss14 is positioned with post-EMT markers (CDH2, VIM, and FN1) rather than pre-EMT markers (CDH1)

• ST14/Prss14 facilitates transendothelial migration of epithelial cancer cells, a key step in the metastatic cascade

• ST14/Prss14 enhances metastasis in experimental breast cancer models

These findings suggest that when using ST14 antibodies to investigate cancer progression, researchers should concurrently examine established EMT markers to correlate ST14 expression with the EMT phenotype. This approach provides mechanistic insights into how ST14 promotes cancer metastasis through EMT regulation.

How does the ratio of ST14 to its inhibitors SPINT1 and SPINT2 affect experimental interpretations?

The balance between ST14/Prss14 and its inhibitors SPINT1 and SPINT2 adds complexity to experimental analyses:

While these ratios correlate with cancer subtypes, their direct impact on survival outcomes appears context-dependent . Therefore, researchers should measure both ST14 and its inhibitors in experimental models to accurately interpret functional outcomes. Multi-transgenic mouse models manipulating both ST14/Prss14 and SPINT2 expression have demonstrated that ST14/Prss14 can initiate tumorigenesis through inflammation mechanisms , suggesting that the protease-inhibitor balance affects multiple cancer-related processes.

How does miR-27b regulate ST14 expression and what methods best detect this interaction?

miR-27b negatively regulates ST14 expression through post-transcriptional mechanisms:

• miR-27b binds to a specific regulatory element in the 3′-UTR region of ST14

• Luciferase reporter assays demonstrate that antisense miR-27b enhances ST14 expression in cancer cells

• miR-27b and ST14 show inverse expression patterns during breast cancer progression

To investigate this regulatory relationship, researchers should employ:

• Luciferase reporter assays with wild-type and mutant 3′-UTR constructs

• Quantitative RT-PCR to measure miR-27b and ST14 mRNA levels

• Western blotting with ST14 antibodies to assess protein expression after miR-27b modulation

• Functional assays (invasion, proliferation) following miR-27b or ST14 manipulation

This experimental approach provides mechanistic insights into how miR-27b controls ST14 expression and function in cancer contexts, potentially revealing therapeutic opportunities targeting this regulatory axis.

What mechanisms explain ST14's differential effects on cell cycle regulation?

ST14 influences cell cycle progression through specific molecular pathways:

• ST14 inhibits cells from entering S phase by up-regulating p27, a cyclin-dependent kinase inhibitor

• This up-regulation leads to down-regulation of cyclin E-CDK2 complexes

• Cells expressing ST14 exhibit a defect in S phase entry with reduced cyclin E and CDK2 levels

• These effects on cell cycle regulation operate independently of miR-27b regulation

To investigate these mechanisms, researchers should employ:

• Flow cytometry for cell cycle analysis

• Western blotting with ST14, p27, cyclin E, and CDK2 antibodies

• EdU incorporation assays to measure S phase entry

• Immunoprecipitation to assess cyclin-CDK complex formation

This methodological approach reveals ST14's role beyond proteolytic function, demonstrating its involvement in fundamental cell cycle control, which contributes to its context-dependent effects on tumor progression.

How should researchers reconcile contradictory ST14 expression patterns between cell lines and patient tissues?

The search results highlight a paradoxical finding: ST14/Prss14 expression is higher in ER negative breast cancers in patient tissues, but higher in ER positive breast cancer cell lines . To address this contradiction, researchers should:

• Use multiple model systems: Complement cell line studies with patient-derived xenografts, organoids, and tissue samples

• Consider microenvironmental factors: The contradiction may stem from microenvironmental differences between in vitro and in vivo settings

• Examine regulatory mechanisms: Investigate whether different regulatory mechanisms (transcriptional, post-transcriptional) operate in different contexts

• Assess ST14 activity: Measure not just ST14 expression but also its proteolytic activity, which may differ between models

What are the key considerations when designing experiments to investigate ST14's role in tumor-associated inflammation?

ST14/Prss14 has been implicated in tumor-associated inflammation , requiring specific experimental approaches:

• Co-culture systems: Design experiments incorporating both epithelial cancer cells and inflammatory cells to recapitulate the tumor microenvironment

• Cytokine profiling: Measure pro-inflammatory cytokine production in response to ST14 modulation using techniques such as multiplex ELISA or cytokine arrays

• In vivo inflammation models: Utilize genetically modified mouse models with altered ST14/SPINT2 expression to assess inflammatory responses

• Mechanistic studies: Investigate proteolytic substrates of ST14 involved in inflammation cascades

• Therapeutic targeting: Test inhibitors of ST14 or downstream inflammatory mediators in preclinical models

This systematic approach helps delineate the mechanisms by which ST14 promotes tumor-associated inflammation, potentially revealing new therapeutic opportunities for cancers with high ST14 expression.

How can researchers effectively study the context-dependent functions of ST14 in different cellular environments?

To address ST14's context-dependent functions, researchers should implement a comprehensive experimental strategy:

• Tissue-specific expression analysis: Use ST14 antibodies to compare expression patterns across multiple tissue types and cancer subtypes

• Co-expression network analysis: Identify genes consistently co-expressed with ST14 across different contexts, such as transcription factors ELF5, GRHL1, and VGLL1

• Conditional expression systems: Employ inducible expression systems to study ST14 function in defined cellular contexts

• Substrate profiling: Identify context-specific ST14 substrates using proteomics approaches

• Single-cell analysis: Apply single-cell RNA-seq and proteomics to resolve heterogeneity in ST14 expression and function within tissues

This multi-faceted approach addresses the observation that "ST14/Prss14 functions are highly context-dependent, influenced by specific cellular environment, tissue type, and regulatory networks" , enabling more precise targeting of ST14 in therapeutic applications.

What experimental designs best capture the relationship between ST14 and HER2 in breast cancer?

The interaction between ST14/Prss14 and HER2 in breast cancer requires specialized experimental approaches:

• Stratified analysis: When designing studies, stratify samples by both HER2 and ST14 expression levels, as survival patterns differ significantly between subgroups:

  • HER2 low/ST14 high: poorest survival (HR: 4.064, P < 0.01)

  • HER2 high/ST14 high vs. HER2 high/ST14 low: HR: 0.473

• Mechanistic studies: Investigate potential signaling crosstalk between HER2 and ST14 pathways using:

  • Co-immunoprecipitation to detect physical interactions

  • Phospho-specific antibodies to assess downstream signaling

  • Dual inhibition experiments targeting both pathways

• Therapeutic implications: Test whether ST14 expression levels predict response to HER2-targeted therapies

• Larger datasets: Expand analyses to larger patient cohorts, as the search results note that "statistical significance was weak or not significant, most likely due to the limiting numbers of data points"

This approach addresses the search results' observation that ST14 is "an emerging therapeutic target for breast cancer where HER2 is not applicable" , helping researchers develop more personalized treatment strategies based on both ST14 and HER2 status.

How can ST14 antibodies be optimized for studying ST14's role in transendothelial migration of cancer cells?

Investigating ST14's role in transendothelial migration requires specialized experimental approaches:

• Live-cell imaging: Optimize fluorescently labeled ST14 antibodies for real-time visualization of ST14 localization during transendothelial migration using confocal microscopy

• Transwell migration assays: Develop protocols using function-blocking ST14 antibodies to assess the requirement of ST14 activity during cancer cell migration through endothelial monolayers

• In vivo models: Employ fluorescently labeled ST14 antibodies for intravital microscopy to track cancer cell behavior at vascular interfaces

• Proximity labeling: Combine ST14 antibodies with proximity labeling techniques to identify interaction partners specifically during the transendothelial migration process

These methodological approaches will help elucidate the mechanisms by which ST14 "plays an important role in transendothelial migration of epithelial cancer cells" , potentially revealing new therapeutic targets to prevent metastasis.

What novel therapeutic approaches targeting ST14 are most promising for ER negative breast cancers?

Based on the strong correlation between high ST14 expression and poor survival in ER negative breast cancers , several therapeutic strategies warrant investigation:

• Small molecule inhibitors: Design specific serine protease inhibitors targeting ST14's catalytic domain

• Monoclonal antibodies: Develop function-blocking antibodies against ST14's extracellular domain to inhibit its proteolytic activity

• RNA interference: Employ siRNA or antisense oligonucleotides to downregulate ST14 expression

• miR-27b mimetics: Develop miR-27b-based therapeutics to downregulate ST14 post-transcriptionally

• Inhibitor regulation: Target mechanisms that downregulate natural ST14 inhibitors (SPINT1/SPINT2) in cancer cells

These approaches address the search results' observation that "ST14 is an emerging therapeutic target for breast cancer where HER2 is not applicable" , potentially offering new treatment options for difficult-to-treat ER negative and triple negative breast cancers.

How should researchers investigate the apparent dual role of ST14 as both tumor promoter and suppressor in different cancer contexts?

The search results highlight that ST14 may have both pro- and anti-carcinogenic activities depending on cancer type . To resolve this paradox, researchers should:

• Comprehensive cancer panel analysis: Apply ST14 antibodies across tissue microarrays from multiple cancer types to establish expression patterns

• Stage-specific analysis: Examine ST14 expression at different stages of cancer progression within each cancer type:

  • In ovarian cancer, ST14 expression appears lower in advanced stages

  • In breast cancer, ST14 expression correlates with progression in ER negative subtypes

• Functional studies: Conduct gain- and loss-of-function experiments in multiple cancer cell types to determine context-specific effects

• Substrate identification: Identify cancer type-specific substrates that might explain differential effects

• Signaling pathway analysis: Map ST14-dependent signaling networks in different cancer contexts

This systematic approach addresses the search results' observation that "it is confusing to determine whether ST14/Prss14 has pro- or anti-carcinogenic activity" and that "sample sizes, tissue types, and context with microenvironments influence the outcome" , enabling more precise targeting of ST14 in specific cancer contexts.