Recombinant Human Oncostatin-M protein (OSM), partial (Active)

What is Recombinant Human Oncostatin-M (OSM) protein?

Recombinant Human Oncostatin-M is a cytokine originally isolated from medium conditioned by PMA-treated U-937 human histiocytic leukemia cells. It was discovered based on its ability to inhibit growth of A375 melanoma cells . As a member of the IL-6 family of cytokines, OSM demonstrates pleiotropic effects across multiple biological systems, particularly in inflammatory responses and cancer progression. The partial active form refers to a recombinant version that contains the essential functional domains necessary for biological activity.

What is the molecular structure of human OSM?

The human OSM cDNA encodes a 252 amino acid pre-pro-OSM polypeptide with a 25 residue hydrophobic signal peptide and a hydrophilic C-terminal domain. These components are proteolytically processed to generate the 196 residue mature form of OSM . The structural characteristics of OSM are summarized in the following table:

How does processing affect OSM activity?

Both mature and pro-OSM forms are equally active in radio-receptor assays, but the mature OSM exhibits 5- to 60-fold higher activity in growth inhibition assays. This significant difference suggests that proteolytic processing of the pro-OSM peptide plays a crucial role in regulating the in vivo activities of OSM . Researchers should be aware of this activity differential when designing experiments with partial active recombinant forms.

What are the primary research applications for recombinant human OSM?

Recombinant human OSM serves as a valuable tool for investigating numerous biological processes, including:

• Cytokine signaling pathway analysis, particularly Jak-STAT and NF-κB pathways

• Cell proliferation studies in models such as TF-1 erythroleukemic cells

• Cancer biology research, especially regarding tumor cell migration and invasion

• Immune cell interactions within the tumor microenvironment

• Cellular differentiation and phenotypic transition investigations

What is the recommended concentration range for OSM in cell-based assays?

Based on established bioassays, researchers should consider the following concentration guidelines:

It is advisable to perform preliminary dose-response experiments to determine the optimal concentration for your specific experimental system and endpoints.

What methodologies are most effective for measuring OSM activity?

Several validated methodologies can be employed to measure OSM activity:

• Proliferation assays using TF-1 human erythroleukemic cells (ED50: 0.05-0.3 ng/mL)

• Wound scratch assays to evaluate migration in responsive cell types

• Invasion assays through extracellular matrix components

• Quantitative RT-PCR to measure OSM-induced gene expression changes

• Western blotting or phospho-flow cytometry to detect activation of downstream signaling molecules, particularly STAT3

• Receptor binding assays to evaluate interaction with OSMR and gp130

Which signaling pathways are activated by OSM and how can they be experimentally monitored?

OSM activates multiple signaling cascades, with the Jak-STAT and NF-κB pathways being particularly prominent in OSM-related biological responses . These pathways can be monitored through:

• Phosphorylation-specific antibodies detecting activated STAT3, STAT1, and STAT5

• Nuclear translocation assays for NF-κB components

• Reporter gene assays with pathway-specific response elements

• Pharmacological pathway inhibition studies (e.g., using STAT3 inhibitors)

• Transcriptional profiling of pathway-specific gene targets

The critical role of STAT3 in mediating OSM effects has been demonstrated through inhibitor studies, where STAT3 inhibitors effectively suppressed OSM-mediated biological effects in experimental models .

How does OSM interact with its receptors and what are the implications for experimental design?

OSM exhibits a unique receptor binding profile, utilizing either type I (gp130/LIFR) or type II (gp130/OSMR) receptor complexes. Cell-cell interaction analysis has demonstrated that the OSM-OSMR pathway is particularly important for OSM to stimulate malignant cells . When designing experiments:

• Consider characterizing receptor expression in your experimental system

• Account for potential differences in signaling outcomes between type I and type II receptor engagement

• Utilize receptor-blocking antibodies to distinguish between different receptor-mediated effects

• Be aware that receptor expression levels may influence cellular responsiveness to OSM

What are the key downstream mediators of OSM signaling and how can they be measured?

Several key downstream mediators participate in OSM signal transduction:

These mediators can be assessed through traditional biochemical techniques or more advanced approaches such as multiplexed phosphoprotein arrays and single-cell phospho-flow cytometry.

How does OSM influence tumor progression and metastasis?

OSM exhibits complex and sometimes contradictory effects on tumor progression. Research has demonstrated that:

• Higher OSM levels are found in most tumor tissues compared with corresponding normal tissues

• Enhanced OSM expression correlates strongly with poor prognosis in several cancer types

• OSM treatment can facilitate migration and invasion of glioblastoma cells

• OSM promotes proneural-mesenchymal transition in glioblastoma, potentially contributing to a more aggressive phenotype

These findings suggest that OSM may contribute to tumor progression through multiple mechanisms, including direct effects on cancer cell behavior and modulation of the tumor microenvironment.

What is the relationship between OSM and the tumor microenvironment?

OSM plays a significant role in tumor-stromal interactions:

• OSM expression is associated with stromal and immune cell infiltration in the tumor microenvironment

• Single-cell RNA sequencing data analysis of glioblastoma multiforme (GBM) revealed that OSM is primarily secreted by microglia

• OSM-related immune checkpoint and chemokine co-expression patterns have been observed

• OSM can communicate extensively with various components of the tumor microenvironment

These interactions suggest that OSM serves as an important mediator of cellular crosstalk within the tumor ecosystem, potentially influencing immune surveillance and treatment response.

How can the apparently contradictory effects of OSM in different tumor contexts be experimentally resolved?

The dual nature of OSM in tumor development (both promotion and inhibition effects) presents a research challenge that can be addressed through:

• Comprehensive pan-cancer analysis using databases like TCGA and GTEx

• Context-specific experimental designs that account for tumor type, stage, and microenvironmental factors

• Single-cell approaches to delineate cell type-specific responses to OSM

• Systematic investigation of dose-dependent and temporal effects

• Comparative studies across multiple model systems (2D culture, 3D organoids, in vivo models)

Such methodological approaches can help resolve the apparent contradictions and provide a more nuanced understanding of OSM's context-dependent activities.

What cutting-edge methodologies are emerging for studying OSM-induced cellular responses?

Several advanced techniques are enhancing our understanding of OSM biology:

• Single-cell RNA sequencing, which has already been applied to identify microglia as the primary source of OSM in GBM

• CRISPR-Cas9 gene editing to interrogate OSM signaling components

• Proximity labeling techniques to identify novel OSM-interacting proteins

• Live-cell imaging with fluorescent biosensors to monitor signaling dynamics

• Spatial transcriptomics to map OSM expression and response patterns within tissues

• Mass cytometry (CyTOF) for high-dimensional analysis of OSM-induced phosphorylation events

These technologies offer unprecedented resolution for dissecting the complex cellular responses to OSM stimulation.

How can researchers effectively inhibit OSM signaling in experimental models?

Several approaches have proven effective for inhibiting OSM signaling:

STAT3 inhibitors have been experimentally validated to suppress OSM-mediated biological effects, confirming the central role of this signaling molecule in OSM-induced responses .

What are the methodological considerations for studying OSM in complex three-dimensional models?

When investigating OSM in 3D models such as organoids or spheroids, researchers should consider:

• Diffusion kinetics of OSM through 3D structures

• Zone-specific cellular responses within the model

• Appropriate techniques for analyzing spatial heterogeneity (e.g., tissue clearing, 3D imaging)

• Modified protocols for protein/RNA extraction from 3D cultures

• Integration of stromal and immune components to recapitulate microenvironmental interactions

• Long-term exposure paradigms to capture sustained signaling effects

• Compatibility with live imaging approaches to monitor dynamic responses

Such considerations are essential for translating 2D findings into more physiologically relevant contexts.

What are the most pressing unresolved questions in OSM biology?

Several critical knowledge gaps remain in our understanding of OSM:

• The mechanisms determining whether OSM promotes or inhibits tumor growth in different contexts

• The comprehensive pan-cancer assessment of OSM's functions and correlations

• The precise molecular pathways governing OSM-induced phenotypic transitions

• The potential for targeting OSM-related pathways in cancer therapy

• The interplay between OSM and other cytokines in the tumor microenvironment

• The role of OSM in treatment resistance mechanisms

Addressing these questions will require interdisciplinary approaches and integration of multiple experimental systems.

How might systems biology approaches enhance our understanding of OSM signaling networks?

Systems biology offers powerful tools for elucidating OSM's complex effects:

• Network analysis to identify key nodes in OSM-regulated gene networks

• Mathematical modeling of signaling dynamics and feedback mechanisms

• Multi-omics integration (transcriptomics, proteomics, metabolomics) to capture system-wide responses

• Machine learning approaches to predict context-dependent outcomes of OSM stimulation

• Comparative pathway analysis across different cell types and disease states

• In silico prediction of potential therapeutic targets within OSM networks

Such approaches can help reconcile apparently contradictory observations and provide a more comprehensive understanding of OSM biology.

What translational opportunities exist for OSM-targeted interventions?

The emerging understanding of OSM biology suggests several potential translational applications:

• Targeting the OSM-OSMR signaling axis in cancers where OSM correlates with poor prognosis

• Developing biomarkers based on OSM expression or pathway activation for patient stratification

• Combination therapies targeting OSM signaling alongside standard treatments

• Repurposing existing STAT3 inhibitors for OSM-driven pathologies

• Exploiting OSM's differential effects in various contexts for tissue-specific interventions

Realizing these opportunities will require continued basic research alongside focused translational efforts to move promising approaches into clinical testing.