产品中心

首页>产品中心>科学研究检测
SDS
Monkey Insulin Like Growth Factor Binding Protein 3 ELISA kit
Catalog #: E09I0074
Sample Type: Biological samples
BackgroundDatasheetStandard CurveProtocol DownloadsFAQs

 

Other Names

BP53; IBP3; Growth Hormone-Dependent Binding Protein; Acid Stable Subunit Of The 140 K IGF Complex

Research Area

Cell Biology, Cancer, Cardiovascular, Metabolism, Signal Transduction

Background

Insulin-like growth factor-binding protein 3, also known as IGFBP-3, is a protein that in humans is encoded by the IGFBP3 gene. IGFBP-3 is one of six IGF binding proteins (IGFBP-1 to IGFBP-6) that have highly conserved structures and bind the insulin-like growth factors IGF-1 and IGF-2 with high affinity. IGFBP-7, sometimes inappropriately included in this family, shares neither the conserved structural features nor the high IGF affinity. IGFBP-3 was first isolated, characterized, and quantitated in human plasma, in 1986.[3][4] It has well-documented functions in the circulation, in the extracellular environment, and inside cells. It is the main IGF transport protein in the bloodstream, where it carries the growth factors predominantly in stable complexes that contain the binding protein, either IGF-1 or IGF-2, and a third protein called the acid-labile subunit or ALS. 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. The IGF-1/IGFBP-3 ratio has sometimes been used as an index of IGF bioavailability in the human circulation, but this ignores IGF-1 binding to other IGFBPs (so the ratio is affected by the concentrations of all six IGFBPs), and the fact that IGF-2, which is three times more abundant than IGF-1 in the bloodstream of adults, occupies the majority of binding sites on circulating 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. High levels of IGFBP-3 within tumors are associated with increased cancer severity (or worse outcome) for some cancers, but decreased severity or better outcome for others. No cases of IGFBP3 gene deletion in humans have been reported, but mice lacking the gene show near-normal growth. Based on cell growth experiments, animal cancer models, and epidemiological studies, it appears that IGFBP-3 functions as a low-penetrance tumor suppressor gene. Dysregulation of IGFBP-3 has been implicated in many cancers.IGFBP-3 is sometimes referred to as a tumor suppressor, and downregulation of its tissue expression by promoter hypermethylation in some cancers, such as hepatoma. and non-small cell lung cancer may be associated with poor patient outcome. However, consistent with the dual inhibitory and stimulatory roles of IGFBP-3 seen in cell culture, there are other cancer types, such as breast cancer,pancreatic cancer,and clear cell renal cell cancer in which high tissue IGFBP-3 expression has been linked to poor prognostic features or patient outcome. The mechanisms regulating these contrasting effects of IGFBP-3 in vivo are not well understood. 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. There have been many studies linking circulating IGFBP-3 levels to the presence, or risk, of various cancers, or to patient outcomes.but unequivocal conclusions have often been lacking. For example, high plasma IGFBP-3 levels were associated with a reduced prospective risk of colorectal cancer in women.but in a study including men and women, colon cancer risk was positively associated with plasma IGFBP-3, while there was no significant association for rectal cancer.A large systematic review concluded that circulating IGFBP-3 levels showed a modest association with increased risk for a number of cancers, but the results vary among sites. IGFBP-3 protein levels decrease during the progression of prostate cancer from benign to metastatic disease although production of the protein does not cease completely. IGFBP-3 is still made (at a lower level) by prostate cancer cells and secreted into the surrounding environment. However, instead of the full length, functional protein, IGFBP-3 is found to be cleaved.This decreases the affinity of IGF binding to IGFBP-3, making the growth factors more likely to bind the IGF1R and promote cell survival.