IGFBP2 and IGFBP3 Protein Expressions in Human Breast Cancer: Association with Hormonal Factors and Obesity

Abstract

Purpose: The insulin-like growth factor (IGF) signaling system is involved in breast cancer initiation and progression. The prognostic relevance of tumor expression patterns of IGFI-related proteins remains poorly understood. This study associates the expression of selected IGF proteins with breast tumor and patient characteristics.Experimental Design: IGFI, IGFI receptor, IGF-binding protein (IGFBP)2, and IGFBP3 expression was measured in 855 primary breast carcinomas by immunohistochemistry using tissue microarrays. We investigated the association of tumor and nodal stage, grade, hormone receptor status, HER2 gene amplification, menopausal status, body mass index, and survival with IGF protein expression.Results: In contrast to IGFI, the expression of IGFI receptor, IGFBP2, and IGFBP3 was associated with estrogen receptor status. In addition, IGFBP3 was positively correlated with body mass index and premenopausal status. Importantly, IGFBP2 was an independent and positive predictor of overall survival (hazard ratio, 0.48; 95% confidence interval, 0.24-0.95; P = 0.04). There was a weak suggestion for IGFBP2 and overweight to modify each other's effect on survival.Conclusions: According to these results, which need confirmation in larger patient series, the prognostic relevance of IGFBP2 and IGFBP3 protein expressions in breast cancer may depend on the hormonal context and body weight. Clin Cancer Res; 16(3); 1025-32. ©2010 AACR.Understanding the biology of breast cancer progression is an important aspect of identifying therapeutic targets. Both obesity at diagnosis and subsequent weight gain are predictive of worse breast cancer survival (1). The obesity-breast cancer association may in part be related to hyperinsulinemia, the concomitant decrease in insulin-like growth factor (IGF)-binding proteins (IGFBP)1 and IGFBP2, and the resulting increase in bioactive IGFI (2). IGFI and IGF2 play a role in mammary gland development (3-5). They have mitogenic, antiapoptotic, and proangiogenic effects and stimulate the motility of breast cancer cells in vitro (3). The two growth factors act through IGFI receptor (IGFIR) homodimerization (3). Their bioavailability in circulation and tissues is regulated by at least six IGF-binding proteins. IGFBP3 and IGFBP2 are the most abundant IGFBPs in the blood. In addition to regulating IGF activity, IGFBPs exert additional IGF-independent effects (6).Transgenic mice deficient in IGFI exhibit a decreased susceptibility to mammary carcinogens (7). Tumor incidence is increased in mice expressing IGFI or IGF2 in the mammary gland (3). According to several meta-analyses and systematic reviews, circulating concentrations of IGFI and less consistently of IGFBP3 were positively associated with premenopausal breast cancer (8). Much less is known about the prognostic relevance of autocrine and paracrine IGF signaling in tumor tissue. Several breast cancer studies reported on the correlation between estrogen receptor (ER) status and the expression patterns of IGF-related proteins (9-12...

Targeted mass spectrometry analysis of the proteins IGF1, IGF2, IBP2, IBP3 and A2GL by blood protein precipitation

“…These proteins were selected based on the interest for the indirect detection of the administration of growth hormone in anti-doping analysis [17][18][19] and in relation to growth disorders, or as potential biomarkers of interest for cancer disease [20][21][22][23][24]. The fact that these proteins had a medium and low abundance and the necessity for short and high-throughput analysis made necessary to apply a first sample preparation step to reduce sample complexity and increase the sensitivity of the assay.…”

“…We employed the optimised precipitation protocol to develop a method for targeting the low mass proteins IGF1 (7.6 kDa), IGF2 (7.5 kDa), IBP2 (31.5 kDa), IBP3 (28.7 kDa) and A2GL (34.3 kDa), all of them putative or confirmed protein biomarkers of medium and low abundance, selected based on their relevance within the anti-doping [17][18][19] and clinical analysis [20][21][22][23][24]. Plasma samples were precipitated at 60% ACN and 30-fold diluted plasma (i.e., at a plasma protein concentration of~2 g/L) and quantified by SRM LC-MS/MS experiments, which is the method of choice for targeted and quantitative protein analysis [43], based on proteotypic tryptic peptides derived from plasma protein digests (Table 1).…”

“…The proteins of medium and low abundance insulin-like growth factor 1 (IGF1), insulin-like growth factor 2 (IGF2), insulin-like growth factor binding protein 2 (IBP2), insulin-like growth factor binding protein 3 (IBP3) and leucine-rich alpha-2-glycoprotein (A2GL) have been proposed as indirect biomarkers for the detection of GH administration [17][18][19], of interest in anti-doping analysis and for prognostic monitoring of GH-related disease treatments, and as putative biomarkers for breast cancer diagnosis [20][21][22][23][24]. Their quantification is typically achieved independently by classical methods such as ELISA or RIA assays [18], necessitating blood sample volumes that range between 50 and 200 μL for each assay.…”

Inhibition of Insulin-like Growth Factor–Binding Protein-3 Signaling through Sphingosine Kinase-1 Sensitizes Triple-Negative Breast Cancer Cells to EGF Receptor Blockade

“…In contrast, studies from a number of groups have demonstrated growthpromoting activity of IGFBP-3 in vitro (7)(8)(9)(10)(11) and elevated gene expression of IGFBP3 occurs in a range of malignancies (12)(13)(14). In human breast tumors, expression of IGFBP-3 is correlated with markers of poor prognosis such as ER and PR negativity, S-phase fraction, and tumor size (15)(16)(17)(18). These clinical observations were recapitulated in a xenograft tumor model in which T47D cells expressing IGFBP-3 as a result of cDNA transfection developed larger tumors than control cells in nude mice (19).…”

Transcription Factor Networks as Targets for Therapeutic Intervention of Cancer: The Breast Cancer Paradigm

“…One possible mechanism by which breast cancer cells escape tamoxifeninduced apoptosis may be the activation of the AKT pathway via IGF-mediated signaling, which leads to phosphorylation of ER at serine 167 (Ser-167) and subsequent ligand-independent activation of ER (12). Additionally, IGF-binding protein 2 (IGFBP-2) mRNA and protein levels have been reported to be augmented in cell lines resistant to the antiestrogens fulvestrant and tamoxifen (13). Selective targeting agents are being investigated in combination with endocrine therapy, in an attempt to overcome or prevent endocrine resistance in breast cancer therapeutics.…”