Recombinant Callicebus moloch Suppressor of tumorigenicity 7 protein (ST7)

What is Recombinant Callicebus moloch Suppressor of Tumorigenicity 7 Protein (ST7)?

Recombinant Full Length Callicebus moloch Suppressor of tumorigenicity 7 protein (ST7) is a protein derived from the Dusky titi monkey (Plecturocebus moloch, formerly classified as Callicebus moloch). The recombinant form typically refers to the full-length protein (spanning amino acids 1-585) with an N-terminal His tag, expressed in E. coli expression systems . ST7 is considered part of a gene family implicated in tumor suppression pathways, making it valuable for cancer research applications.

How should recombinant ST7 protein be properly stored and reconstituted for experimental use?

For optimal experimental outcomes, ST7 protein requires specific handling procedures:

Storage recommendations:

• Store lyophilized powder at -20°C to -80°C upon receipt

• Aliquot reconstituted protein to avoid repeated freeze-thaw cycles

• Working aliquots may be stored at 4°C for up to one week

Reconstitution protocol:

• Briefly centrifuge the vial before opening to collect contents at the bottom

• Reconstitute in deionized sterile water to a concentration of 0.1-1.0 mg/mL

• Add glycerol to a final concentration of 5-50% (recommended 50%) for long-term storage

• Store reconstituted aliquots at -20°C/-80°C

Avoiding repeated freeze-thaw cycles is crucial for maintaining protein activity and stability.

What is the taxonomic classification of Callicebus moloch and its significance in comparative studies?

Callicebus moloch, now reclassified as Plecturocebus moloch (Red-bellied Titi Monkey), belongs to the following taxonomic hierarchy:

Common names include Red-bellied Titi Monkey, Dusky Titi, and Titi Monkey . This species serves as an important non-human primate model for comparative genomic studies of tumor suppressor genes across evolutionarily related species.

What is the relationship between ST7 protein and long non-coding RNA ST7-AS1 in cancer research?

While ST7 protein functions as a potential tumor suppressor, research has identified a related long non-coding RNA called ST7-AS1 that appears to have significant roles in cancer biology:

• ST7-AS1 expression is frequently downregulated in breast cancer tissues compared to normal tissue

• Low ST7-AS1 expression correlates with advanced clinical pathologic characteristics including high grade, histological type, age, menopause status, and HER2 status

• ST7-AS1 expression levels show correlation with survival time and prognosis in breast cancer patients

• Copy Number Variations (CNVs) in ST7-AS1 can cause gene disorder in downstream cancers, linked to proliferation, apoptosis, and cell migration

The functional relationship between ST7 protein and ST7-AS1 suggests complex regulatory mechanisms that may be exploited for cancer diagnostics and therapeutics.

How can researchers utilize recombinant ST7 protein in functional studies of tumor suppression pathways?

When designing experimental approaches to investigate ST7's role in tumor suppression:

• Protein interaction studies:

  • Use purified recombinant ST7 with His-tag for pull-down assays to identify binding partners

  • Perform co-immunoprecipitation experiments with epitope-tagged ST7 in cellular lysates

  • Employ yeast two-hybrid screening to identify novel protein-protein interactions

• Functional rescue experiments:

  • In cell lines with ST7 knockdown/knockout, introduce recombinant ST7 to assess rescue of phenotype

  • Compare wild-type versus mutant forms of recombinant ST7 protein to map functional domains

• Structural biology approaches:

  • Generate crystal structures using purified recombinant ST7 protein to elucidate molecular mechanisms

  • Use the full-length protein (amino acids 1-585) for comprehensive structural analysis

These methodological approaches can help elucidate ST7's role in complex cellular pathways involved in tumor suppression.

What are the correlations between ST7 expression and clinical pathological features in cancer patients?

Research on ST7 and its related gene products has revealed significant correlations with clinical features in cancer:

These findings suggest that reduced expression of ST7-related genes may be associated with more advanced primary tumor characteristics but not necessarily with nodal or metastatic spread . Such correlations highlight the potential value of ST7 as a prognostic biomarker in certain cancers.

How does ST7 expression influence the tumor immune microenvironment?

Analysis of ST7-related gene expression has revealed important correlations with immune cell infiltration in the tumor microenvironment:

• ST7-AS1 expression shows correlation with specific immune cell populations:

  • T helper cells

  • Dendritic cells (DCs)

• Research methodologies to investigate these associations include:

  • Single-sample Gene Set Enrichment Analysis (ssGSEA) to quantify relative enrichment scores

  • Analysis of correlations between gene expression and infiltration levels using Spearman correlation

  • Comparison of immune cell populations between high and low expression groups using Wilcoxon rank sum tests

Understanding these relationships may provide insights into how ST7 influences tumor immune surveillance and potential immunotherapeutic approaches.

What experimental techniques are most effective for studying ST7's role in cell cycle regulation and DNA repair?

Based on gene ontology (GO) analysis and gene set enrichment analysis (GSEA), ST7-related genes have been implicated in cell cycle and DNA repair processes . Researchers investigating these functions should consider:

• Cell cycle analysis techniques:

  • Flow cytometry with propidium iodide staining to assess cell cycle distribution

  • BrdU incorporation assays to measure S-phase entry

  • Time-lapse microscopy with ST7-expressing versus ST7-knockout cells

• DNA repair capacity assessment:

  • Comet assay to measure DNA damage repair kinetics

  • γ-H2AX foci formation to quantify double-strand break repair

  • Reporter assays for specific DNA repair pathways (HR, NHEJ)

• Pathway analysis:

  • Combine recombinant ST7 protein studies with RNA-seq and proteomics

  • Use GO analysis and GSEA to identify significantly enriched biological processes

  • Apply hallmark pathway analysis to identify molecular mechanisms

These methodological approaches provide a comprehensive framework for investigating ST7's functional roles in cellular processes critical to cancer development and progression.

How can researchers develop and validate prognostic models incorporating ST7 expression in cancer?

To develop robust prognostic models using ST7 expression:

• Statistical approach:

  • Utilize Kaplan-Meier survival curve analysis with hazard ratios and 95% CI

  • Apply univariate and multivariate analysis with Cox logistic regression models

  • Establish nomograms for predicting 1-, 3-, or 5-year survival rates

• Validation methodology:

  • Evaluate discrimination ability through receiver operating characteristic (ROC) analysis

  • Assess correlation between clinical characteristics and gene expression using appropriate statistical tests (Chi-squared test, Fisher exact test, Kruskal–Wallis test, etc.)

  • Employ R statistical software (Version 3.5.1 or later) for comprehensive analysis

• Implementation strategy:

  • Combine ST7 expression data with established clinical prognostic factors

  • Validate findings across multiple patient cohorts

  • Consider integration with other molecular biomarkers for improved prognostic power

This systematic approach ensures that ST7-based prognostic models have robust statistical foundation and clinical utility.

What are the key considerations when designing experiments with recombinant ST7 protein?

When planning experiments using recombinant Callicebus moloch ST7 protein:

• Protein preparation:

  • The N-terminal His-tagged form (available commercially) offers advantages for purification and detection

  • Purity greater than 90% as determined by SDS-PAGE is generally suitable for most applications

  • Consider the buffer composition (Tris/PBS-based buffer, 6% Trehalose, pH 8.0) when designing experiments

• Experimental controls:

  • Include appropriate negative controls (e.g., irrelevant His-tagged protein of similar size)

  • Consider species-specific differences when extrapolating findings to human systems

  • Validate antibody specificity for detection of recombinant versus endogenous ST7

• Functional assays:

  • Select cell lines with defined ST7 expression levels

  • Consider transfection efficiency and expression levels in overexpression studies

  • Design time-course experiments to capture dynamic processes

These considerations help ensure experimental rigor and reproducibility when working with recombinant ST7 protein.

How should researchers interpret contradictory findings regarding ST7's role in different cancer types?

When faced with conflicting results across cancer types or experimental systems:

• Contextual analysis:

  • Consider tissue-specific effects of ST7 (expression patterns may vary across tissues)

  • Evaluate the role of ST7 in relation to specific oncogenic drivers in each cancer type

  • Assess potential differences in ST7 splice variants or post-translational modifications

• Methodological variations:

  • Examine differences in experimental approaches (in vitro vs. in vivo models)

  • Consider variations in ST7 detection methods (antibodies, mRNA quantification)

  • Evaluate statistical power and sample sizes across studies

• Integrative approach:

  • Combine findings from multiple methodologies (genomic, transcriptomic, proteomic)

  • Consider evolutionary conservation of ST7 function across species

  • Apply bioinformatic approaches to resolve apparent contradictions

This systematic framework helps researchers navigate discrepancies in the literature and develop coherent models of ST7 function.

What are the most promising future research directions for ST7 in cancer biology?

Based on current knowledge, several key areas warrant further investigation:

• Mechanistic studies:

  • Elucidate the precise molecular mechanisms by which ST7 and ST7-AS1 influence cell cycle and DNA repair

  • Investigate the relationship between ST7 protein function and lncRNA ST7-AS1 regulatory networks

  • Map the signaling pathways downstream of ST7 in normal and malignant cells

• Clinical applications:

  • Develop ST7-based prognostic models with improved accuracy for patient stratification

  • Explore therapeutic strategies targeting ST7 pathways in cancers with aberrant expression

  • Investigate ST7 as a biomarker for response to specific cancer treatments

• Comparative biology:

  • Compare ST7 function across primate species to understand evolutionary conservation

  • Examine species-specific differences in ST7 regulation and activity

  • Utilize the Callicebus moloch model for insights applicable to human cancer biology

These research directions hold potential for translating basic knowledge about ST7 into clinically relevant applications for cancer diagnosis and treatment.