IGF1 Antibody

What is IGF1 and why is it an important research target?

IGF1 (insulin-like growth factor 1), also known as somatomedin C, belongs to the INS family and functions as a 70-amino acid hormone with structural and functional similarities to insulin, though with significantly higher growth-promoting activity. IGF1 is primarily synthesized in the liver under growth hormone regulation, but is also produced in peripheral tissues including muscle, cartilage, bone, kidney, nerves, and skin .

IGF1 serves as a critical mediator of prenatal and postnatal growth, acting through endocrine, paracrine, and autocrine mechanisms. Its importance in research stems from its involvement in various pathological conditions including type I diabetes and multiple cancer types . Defects in IGF1 are associated with IGF1 deficiency, an autosomal recessive disorder characterized by growth retardation .

The mature 7.6 kDa IGF1 protein shares high sequence homology across species (94% with mouse and 96% with rat IGF1), enabling cross-species research applications, while maintaining 64% sequence identity with human IGF2 .

What types of IGF1 antibodies are available for research applications?

Multiple types of IGF1 antibodies are available for research, each with specific characteristics:

Researchers should select antibodies based on their specific experimental needs, including target species, application type, and whether specificity for IGF1 over IGF2 is required.

What are the recommended applications and dilutions for IGF1 antibodies?

Optimal dilutions and conditions vary by antibody and application:

It is essential to titrate each antibody in your specific experimental system for optimal results. Results may be sample-dependent, necessitating validation in each model system .

How should IGF1 antibodies be stored and handled for optimal performance?

Proper storage and handling significantly impact antibody performance:

Some IGF1 antibody formulations (e.g., 20μl sizes) may contain 0.1% BSA, which should be considered when designing experiments sensitive to BSA presence .

How can researchers validate the specificity of an IGF1 antibody?

Antibody specificity validation is critical for reliable experimental interpretation:

Western Blot Analysis:

• Test against recombinant IGF1 proteins and related proteins like IGF2

• The Anti-IGF1 antibody (ANT-046) recognized both rat and human IGF1 but did not recognize IGF2, confirming specificity

• Pre-incubation with specific blocking peptides should eliminate signal if the antibody is specific

Immunohistochemistry/Immunofluorescence:

• Test on tissues with known IGF1 expression (positive controls)

• Include blocking peptide controls

• Example: Anti-IGF1 antibody (ANT-046) showed specific neuronal staining in mouse hippocampus that was abolished by blocking peptide pre-incubation

Quantitative Methods:

• Surface plasmon resonance analysis can determine binding kinetics and affinities to target and non-target proteins

• Affinity determination using biotinylated antigen captured by streptavidin on sensor chips can quantify binding characteristics

What tissues and cell lines serve as appropriate controls for IGF1 antibody validation?

Selecting appropriate positive and negative controls enhances validation quality:

Positive Controls:

• Human liver tissue (validated for IHC)

• Mouse kidney and liver tissues (validated for IHC)

• Mouse hippocampal CA1 region (shows neuronal IGF1 expression)

• Mouse parietal cortex (shows neuronal IGF1 expression)

• MDA-MB-123 human breast cancer cell line (validated for ICC)

Negative Controls:

• PC-3 human prostate cancer cell line (negative for IGF-I/IGF-1 by ICC)

• Samples treated with antibody pre-incubated with specific blocking peptide

• Recombinant human IGF2 (for antibodies specific to IGF1)

What considerations are important when designing experiments using IGF1 antibodies for cancer research?

Cancer research using IGF1 antibodies requires specific methodological considerations:

Antibody Selection:

• For therapeutic investigations, consider dual-specific antibodies targeting both IGF1 and IGF2, like m708.5

• Validate antibody specificity in relevant cancer cell lines (e.g., MDA-MB-123 breast cancer cells show positive IGF1 staining while PC-3 prostate cancer cells are negative)

Experimental Design:

• Include appropriate cancer and normal tissue controls

• Consider the effects of tumor microenvironment on IGF1 expression

• Account for both locally produced and circulating IGF1

Technical Considerations:

• For therapeutic antibodies, characterize binding parameters using surface plasmon resonance

• Assess cross-reactivity with mouse IGF1/IGF2 for preclinical studies in mouse models

• Purify antibodies using appropriate methods (e.g., MabSelect affinity chromatography)

What methods exist for quantifying IGF1 beyond traditional antibody-based assays?

Alternative methods for IGF1 quantification offer advantages in certain research contexts:

LC-MS/MS Methods:

• Antibody-free LC-MS/MS methods provide simple and fast quantification of intact IGF-1 and IGF-2 in human plasma

• Require minimal sample volume (50 μL of plasma)

• Utilize 15N-labeled IGF-1 as internal standard

• Avoid potential antibody cross-reactivity issues

• Enable simultaneous quantification of both IGF1 and IGF2

Other Advanced Methods:

• Surface plasmon resonance for kinetic analysis of interactions

• ELISA with careful optimization of capture and detection antibodies

• Biacore analysis for quantitative binding studies

How can researchers optimize antigen retrieval for IGF1 immunohistochemistry?

Successful IGF1 immunohistochemistry depends on effective antigen retrieval:

Recommended Buffers:

• Primary recommendation: TE buffer at pH 9.0

• Alternative method: Citrate buffer at pH 6.0

Procedure Optimization:

• Heat-induced epitope retrieval is typically more effective than enzymatic methods

• Temperature, time, and pressure should be optimized for specific tissue types

• Formalin fixation time affects the required intensity of antigen retrieval

Validation Approaches:

• Compare staining intensity with different retrieval methods

• Include positive control tissues (human liver, mouse kidney/liver)

• Verify specificity with blocking peptide controls

How do researchers address cross-reactivity issues when IGF1 antibodies are used in multi-species studies?

Cross-species applications require careful consideration:

Sequence Homology Analysis:

• Human IGF1 shares high amino acid sequence identity with mouse (94%) and rat (96%) IGF1

• This conservation enables some antibodies to work across species

Validated Cross-Reactivity:

Epitope Selection:

• Antibodies targeting conserved regions show better cross-species reactivity

• Example: ANT-046 targets peptide (C)NKPTGYGSSIRR (amino acids 74-85 of rat IGF1)

Application-Specific Validation:

• Even with predicted cross-reactivity, validate each antibody in each species and application

• Include species-specific positive controls and recombinant standards