Insulin-like growth factor binding protein-3 in breast cyst fluid: relationships with insulin-like growth factors I and II and transforming growth factor-beta 1 and 2

Transforming Growth Factor Beta 1 Serum Levels in Patients with Preinvasive and Invasive Lesions of the Breast

Transforming growth factor beta (TGF-β)1 is thought to be involved in breast carcinogenesis. TGF-β1 acts in an antiproliferative manner in the early stages of breast carcinogenesis, but promotes tumor progression and metastases in the advanced stages of the disease. No data have been published on serum TGF-β1 in breast cancer. We investigated TGF-β1 serum levels in patients with breast cancer (n=135), ductal carcinoma in situ (DCIS) I to III (n=67) or fibroadenoma (n=35), and in healthy women (n=40) to determine its value as a differentiation marker between malignant, pre-invasive and benign diseases and as a predictive marker for metastatic spread. Median (range) TGF-β1 serum levels in patients with breast cancer, DCIS I-III or benign breast lesions and in healthy women were 48.8 (18–82.4) pg/mL, 45.3 (26.9–58.3) pg/mL, 47.2 (17.2–80.5) pg/mL and 51.6 (30.9–65.1) pg/mL, respectively (p=0.2). In breast cancer patients TGF-β1 serum levels showed no statistically significant correlation with tumor stage, lymph node involvement, histological grade, estrogen receptor status and progesterone receptor status. Our data fail to indicate any correlation between serum TGF-β1 levels and clinicopathological parameters of breast diseases. Serum TGF-β1 levels do not provide clinical information in addition to established tumor markers.

IGF binding proteins (IGFBPs) and regulation of breast cancer biology

The IGFBP family comprises six proteins with high affinity for the IGFs. Changes in the balance of the components of the IGF system may contribute to the progression of breast cancer. In tumours the abundance of IGFBPs relates to the estrogen receptor status and their production in the breast is controlled by hormones, principally estrogen and progesterone. Important interactions occur between IGFBPs and key growth regulators such as TGF-beta, PTEN and EGF which are reviewed. The conflicting observations between the effects of IGFBPs on the risk of breast cancer, in particular IGFBP-3, obtained from epidemiology studies in comparison to in vivo observations are highlighted and potential explanations provided. The functional activity of IGFBPs can also be affected by proteolysis, phosphorylation and glycosylation and the implications of these are described. The IGFs are generally present at levels far in excess of that required for maximal receptor stimulation, and the IGFBPs are critical regulators of their cellular actions. IGFBPs can affect cell function in an IGF-dependent or independent manner. The key mechanisms underlying the intrinsic actions of the IGFBPs are still in debate. IGF bioactivity locally in the breast is influenced not only by local tissue expression and regulation of IGFs, IGFBPs and IGFBP proteases, but also by these factors delivered from the circulation. Finally, the therapeutic potential of IGFBPs-2 and -3 are considered together with key questions that still need to be addressed.

Human gross cyst breast disease and cystic fluid: bio-molecular, morphological, and clinical studies

For more than one and a half century the cystic disease of the breast has been recognized as the most frequent female benign breast lesion. Although some conundrums and controversies exist about the relation between gross cysts and breast cancer, recent evidence suggests that the multidisciplinary study of gross cystic breast disease (GCBD) may be a powerful tool for predicting the natural history of the multifaceted gross cyst pathology. A lot of papers have been published on breast cyst fluids (BCF) concerning biochemical, hormonal and morphological aspects, demonstrating that the intracystic fluid contains a wide variety of components (such as ions, lipids, proteins, enzymes, growth factors and antigens) and suggesting that their profile provides additional knowledge on both physiopathology and etiologic pathways of human gross cystic breast disease. The aim of this overview is the critical evaluation of all data accumulated in the last thirty years, in order to highlight the utility of biochemical and epidemiological studies to identify gross cysts, if any, at higher breast cancer risk.

Apocrine cysts of the breast: biomarkers, origin, enlargement, and relation with cancer phenotype

Up to one-third of women aged 30-50 years have cysts in their breasts and are presumed to be at increased risk of developing breast cancer. Here we present an extensive proteomic and immunohistochemistry (IHC) study of breast apocrine cystic lesions aimed at generating specific biomarkers and elucidating the relationship, if existent, of apocrine cysts with cancer phenotype. To this end we compared the expression profiles of apocrine macrocysts obtained from mastectomies from high risk cancer patients with those of cancerous and non-malignant mammary tissue biopsies collected from the same patients. We identified two biomarkers, 15-hydroxyprostaglandin dehydrogenase and 3-hydroxymethylglutaryl-CoA reductase, that were expressed specifically by apocrine type I cysts as well as by apocrine metaplastic cells in type II microcysts, terminal ducts, and intraductal papillary lesions. No expression of these markers was observed in non-malignant terminal ductal lobular units, type II flat cysts, stroma cells, or fat tissue as judged by IHC analysis of matched non-malignant tissue samples collected from 93 high risk patients enrolled in our cancer program. IHC analysis of the corresponding 93 primary tumors indicated that most apocrine changes have little intrinsic malignant potential, although some may progress to invasive apocrine cancer. None of the apocrine lesions examined, however, seemed to be a precursor of invasive ductal carcinomas, which accounted for 81% of the tumors analyzed. Our studies also provided some insight into the origin, development, and enlargement of apocrine cysts in mammary tissue. The successful identification of differentially expressed proteins that characterize specific steps in the progression from early benign lesions to apocrine cancer opens a window of opportunity for designing and testing new approaches for pharmacological intervention, not only in a therapeutic setting but also for chemoprevention, to inhibit cyst development as both 15-hydroxyprostaglandin dehydrogenase and 3-hydroxymethylglutaryl-CoA reductase are currently being targeted for chemoprevention strategies in various malignancies.

Insulin-like growth factor binding proteins (IGFBPs) in breast cancer

The IGFBP family comprises six proteins with high affinity for the IGFs and several lower affinity IGFBP-related proteins. Their production in the breast is controlled by hormones, other local regulators and in tumors relates to the estrogen receptor status. Their functional activity can also be affected by various post-translational modifications. The IGFs are generally present at levels far in excess of that required for maximal receptor stimulation, and the IGFBPs are critical regulators of cellular action. IGFBPs can affect cell function in an IGF-dependent or independent manner. IGF bioactivity locally in the breast is influenced not only by local tissue expression and regulation of IGFs, IGFBPs, and IGFBP proteases, but also by these factors delivered from the circulation. Changes in the balance of the components of the IGF system may lead to a disruption of tissue homeostasis.

Serum levels of insulin-like growth factor binding protein-3 in benign and malignant breast disease

BACKGROUND

The insulin-like growth factors IGF-I and IGF-II and their major binding protein IGFBP-3 influence the growth of breast cancer cells in vitro. Some benign non-breast tumours appear to be associated with increased serum IGFBP-3 levels which would tend to reduce bioactive-free IGF concentrations. The present study investigates whether this pattern also occurs in neoplastic breast disease.

METHODS

Serum IGF-I, IGF-II and IGFBP-3 were measured by specific radioassay in 12 women with benign breast disease, 31 patients with breast cancer and in age-matched controls.

RESULTS

The mean (+/-SD) serum IGFBP-3 concentration was higher in benign breast disease (3.6+/-0.7 mg/L) than in controls (2.7+/-0.6 mg/L) or in breast cancer patients (2.7+/-0.5 mg/L) (P = 0.001). Serum IGF-I and IGF-II levels were not significantly different among the groups. However, the index of free unbound IGF measured as the molar ratio of IGF-I plus IGF-II divided by IGFBP-3 was significantly lower in benign breast disease than in the other subjects.

CONCLUSIONS

Either the production or clearance of IGFBP-3 is altered in benign breast disease so that there is less free IGF available to cells. This may serve to protect against malignant transformation in patients with benign breast disorders.