Description

Nori Feline IGFBP-3 ELISA Kit Summary

Alternative names for IGFBP-3: Insulin-like growth factor binding protein 3, IGFBP3, IBP3

Alternative names for feline: cat

A0A337S9R3

Standard Curve

Kit Components
1. Pre-coated 96-well Microplate
2. Biotinylated Detection Antibody
3. Streptavidin-HRP Conjugate
4. Lyophilized Standards
5. TMB One-Step Substrate
6. Stop Solution
7. 20 x PBS
8. Assay Buffer

Other Materials Required but not Provided:
1. Microplate Reader capable of measuring absorption at 450 nm
2. Log-log graph paper or computer and software for ELISA data analysis
3. Precision pipettes (1-1000 µl)
4. Multi-channel pipettes (300 µl)
5. Distilled or deionized water

Protocol Outline
1. Prepare all reagents, samples and standards as instructed in the datasheet.
2. Add 100 µl of Standard or samples to each well and incubate 1 h at RT.
3. Add 100 µl of Working Detection Antibody to each well and incubate 1 h at RT.
4. Add 100 µl of Working Streptavidin-HRP to each well and incubate 20 min at RT.
5. Add 100 µl of Substrate to each well and incubate 5-30 min at RT.
6. Add 50 µl of Stop Solution to each well and read at 450 nm immediately.

Background: 

Insulin-like growth factor-binding protein 3 (IGFBP-3) is a protein that is encoded by the IGFBP3 gene[1] and binds the insulin-like growth factors IGF-1 and IGF-2 with high affinity.  IGFBP-3 is the main IGF transport protein in the bloodstream, where it carries the growth factors predominantly in stable complexes that contain IGF-1 or IGF-2, and a third protein called the acid-labile subunit (ALS). IGFBP-3 may functions as a low-penetrance tumor suppressor gene.^[2] For IGFs to reach the tissues from the bloodstream, the circulating complexes are believed to partly dissociate, possibly enhanced by limited proteolysis of IGFBP-3. Within tissues, IGFBP-3 can bind IGF-1 and IGF-2 released by many cell types, and block their access to the IGF-1 receptor (IGF1R), which is activated by both IGFs. IGFBP-3 also interacts with cell-surface proteins, affecting cell signaling from outside the cell or after internalization, and also enters the cell nucleus where it binds to nuclear hormone receptors and other ligands. IGFBP-3 mRNA is expressed in all tissue examined.^[3]  Many factors increase IGFBP-3 production by cells, including TGFβ, TNF-α and IGF-1, and stimuli such as chemotherapy that activate the tumor suppressor p53.^[4] Estrogen inhibits IGFBP-3 production, and its tissue levels are lower in estrogen receptor (ER)-positive breast cancers than in ER-negative cancers. High levels of IGFBP-3 within tumors are associated with increased cancer severity for some cancers, but decreased severity or better outcome for others. Dysregulation of IGFBP-3 has been implicated in many cancers.^[5] Downregulation of its tissue expression by promoter hypermethylation in some cancers, such as hepatoma^[6] and non-small cell lung cancer^[7] may be associated with poor patient outcome. IGFBP3 has the dual inhibitory and stimulatory roles in cancers. Since IGFBP-3 is abundant in the bloodstream of healthy adults (typically 2–4 mg/L), and is largely stabilized by its complex formation with IGFs and ALS, it is unlikely that tumor-derived IGFBP-3 has a large influence on circulating levels.

References

1. Cubbage ML, et al. (1990) J Biol Chem 265 (21), 12642-12649 (1990)
2. Jogie-Brahim S, Feldman D, Oh Y (2009). Endocr. Rev. 30 (5): 417–37.
3. Albiston AL, Herington AC (1992). Endocrinology. 130 (1): 497–502.
4. Buckbinder L, et al. (1995). Nature. 377 (6550): 646–9.
5. Baxter RC (2014). Nat. Rev. Cancer. 14 (5): 329–41.
6. Hanafusa T, et al. (2002). Cancer Lett. 176 (2): 149–58.
7. Chang YS, et al. (2002). Clin. Cancer Res. 8 (12): 3669–75.

Product Citation