Prostate-specific antigen and insulin-like growth factor binding protein-3 in nipple aspirate fluid are associated with breast cancer

Nipple Aspirate Fluid at a Glance

Simple Summary

Nipple aspirate fluid (NAF) is a promising source of markers for detection of breast cancer. NAF can be acquired via the nipple by aspiration using a suction device, which is well tolerated by women. Future possible applications of biomarkers for breast cancer derived from NAF could be (1) as a detection tool to identify the initiation of the cancer development process, (2) as an additional tool next to imaging (mammography and breast magnetic resonance imaging) or (3) as a replacement tool for when imaging is not advisable for women, such as during pregnancy and breastfeeding. With this paper, we present a narrative review and perspectives of NAF research at a glance.

Abstract

Nipple aspirate fluid (NAF) is an intraductal mammary fluid that, because of its close proximity to and origin from the tissue from which breast cancer originates, is a promising source of biomarkers for early breast cancer detection. NAF can be non-invasively acquired via the nipple by aspiration using a suction device; using oxytocin nasal spray helps increase yield and tolerability. The aspiration procedure is generally experienced as more tolerable than the currently used breast imaging techniques mammography and breast magnetic resonance imaging. Future applications of NAF-derived biomarkers include their use as a tool in the detection of breast carcinogenesis at its earliest stage (before a tumor mass can be seen by imaging), or as a supporting diagnostic tool for imaging, such as when imaging is less reliable (to rule out false positives from imaging) or when imaging is not advisable (such as during pregnancy and breastfeeding). Ongoing clinical studies using NAF samples will likely shed light on NAF’s content and clinical potential. Here, we present a narrative review and perspectives of NAF research at a glance.

Analysis of nipple aspirate fluid for diagnosis of breast cancer: an alternative to invasive biopsy

Over 40,000 women in the USA will die this year of breast cancer. Current generally accepted techniques to detect breast cancer are limited to breast examination and mammography. Abnormalities found by these techniques require an invasive needle or surgical biopsy to determine if cancer is present. The author's ultimate goal is to determine if a woman has breast cancer without the need for invasive biopsies, and do this before the abnormality is detectable by standard screening techniques. Herein, the technology is reviewed as it was, as it is today, and its future potential is discussed.

Breast cancer biomarkers predict weight loss after gastric bypass surgery

BACKGROUND

Obesity has long been associated with postmenopausal breast cancer risk and more recently with premenopausal breast cancer risk. We previously observed that nipple aspirate fluid (n) levels of prostate specific antigen (PSA) were associated with obesity. Serum (s) levels of adiponectin are lower in women with higher body mass index (BMI) and with breast cancer. We conducted a prospective study of obese women who underwent gastric bypass surgery to determine: 1) change in n- and s-adiponectin and nPSA after surgery and 2) if biomarker change is related to change in BMI. Samples (30-s, 28-n) and BMI were obtained from women 0, 3, 6 and 12 months after surgery.

FINDINGS

There was a significant increase after surgery in pre- but not postmenopausal women at all time points in s-adiponectin and at 3 and 6 months in n-adiponectin. Low n-PSA and high s-adiponectin values were highly correlated with decrease in BMI from baseline.

CONCLUSIONS

Adiponectin increases locally in the breast and systemically in premenopausal women after gastric bypass. s-adiponectin in pre- and nPSA in postmenopausal women correlated with greater weight loss. This study provides preliminary evidence for biologic markers to predict weight loss after gastric bypass surgery.

Cellular and hormonal content of breast nipple aspirate fluid in relation to the risk of breast cancer

In research settings, the measurement of serum and urine hormone concentrations has shown modest positive relationships with breast cancer risk in postmenopausal women. However, the local production of sex steroids in the breast is a significant contributor to the hormonal environment of the breast. Nipple aspiration fluid provides a window into this environment and allows the measurement of hormone and protein content which may show stronger relations to breast cancer risk, and therefore enable both more accurate risk assessment, and the use of preventive measures directed to the lowering of local breast hormonal exposure.

Breast cancer screening and biomarkers

Annual screening mammograms have been shown to be cost-effective and are credited for the decline in mortality of breast cancer. New technologies including breast magnetic resonance imaging (MRI) may further improve early breast cancer detection in asymptomatic women. Serum tumor markers such as CA 15-3, carcinoembyonic antigen (CEA), and CA 27-29 are ordered in the clinic mainly for disease surveillance, and not useful for detection of localized cancer. This review will discuss blood-based markers and breast-based markers, such as nipple/ductal fluid, with an emphasis on biomarkers for early detection of breast cancer. In the future, it is likely that a combination approach to simultaneously measure multiple markers would be most successful in detecting early breast cancer. Ideally, such a biomarker panel should be able to detect breast cancer in asymptomatic patients, even in the setting of normal mammogram and physical examination results.

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.

Urinary levels of Bcl-2 are elevated in ovarian cancer patients

OBJECTIVE(S)

The poor prognosis associated with ovarian cancer is due to the lack of overt early symptoms and the absence of reliable diagnostic screening methods. Since many tumors overexpress anti-apoptotic proteins, the purpose of this study was to determine whether elevated levels of the anti-apoptotic protein Bcl-2 were present in urine from patients with ovarian cancer.

METHODS

Bcl-2 was assayed by ELISA in urine samples from two cohorts consisting of a total of 77 healthy women, 161 women with benign gynecologic disease and 150 women with ovarian cancer, 13 with early and 137 with late stage disease, respectively. Wherever possible, parallel serum samples were measured for CA125 levels by ELISA.

RESULTS

Urinary levels of Bcl-2 from healthy individuals or women with benign disease averaged 0.59 ng/ml+/-0.61 and 1.12 ng/ml+/-0.79, respectively. In contrast, urinary levels of Bcl-2 averaged 2.60 ng/ml+/-2.23 and 3.58 ng/ml+/-1.55 from women with early (N=13) and late (N=137) stage ovarian cancer. Further, urinary levels of Bcl-2 were elevated in ovarian cancer patients regardless of tumor grade, stage, size, histologic subtype, creatinine levels or patient age, but appeared to complement CA125 measurements.

CONCLUSION(S)

Levels of Bcl-2 are elevated in the urine of patients with ovarian cancer and may be of diagnostic and/or prognostic clinical importance. Further studies of urinary Bcl-2 as a biomarker for ovarian cancer alone or in combination with other markers are warranted.

A strong association between body fat mass and protein profiles in nipple aspirate fluid of healthy premenopausal non-lactating women

Fluid can be aspirated from the nipples of most non-lactating women. This nipple aspirate fluid (NAF) is a potential source for the discovery of new breast cancer biomarkers. NAF has two distinct protein profiles. Type I NAF is similar to the fluid associated with cystic disease of the breast, whereas type II NAF is enriched in milk-associated proteins. The prevalence of these two profiles differs in healthy women and in breast cancer patients. This study investigated the relationship of these two NAF profiles to reproductive history, body composition, diet, and levels of lipids, steroids and thyroid hormones in healthy premenopausal women (age 30-40 years) who had regular menstrual cycles and normal mammograms and were not taking contraceptive medications. On average, women with the type I NAF profile were older, had more years since last childbirth, were less likely to have breastfed their babies and had higher dietary saturated fat intake, body mass index, body fat mass, and levels of plasma low density lipoproteins than women with the type II profile (P <0.05). Using multiple logistic regression, type I NAF was predicted independently (P <0.05) by higher body fat mass [Odds Ratio (OR) = 3.0; 95% Confidence Interval (CI): 1.5-6.1], more years since last childbirth (OR = 2.6; 95% CI: 1.3-5.2) and a higher percentage of calories from saturated fat (OR = 4.1; 95% CI: 1.1-14.6). These results suggest that protein profiles of NAF might be influenced by amounts or types of dietary and body fat, but further study of the relationship of the two profiles to breast cancer risk is needed.

The intraductal approach to breast cancer biomarker discovery

Established methods of breast cancer detection have well-described limitations, and new diagnostic techniques are evolving continually to improve diagnostic accuracy. The intraductal approach encompasses the modalities of nipple aspiration, ductal lavage, and duct endoscopy, and is a means of directly accessing the microenvironment of the breast and either sampling or visualizing this intraductal milieu. The aim of sampling this mammary microenvironment is to obtain samples from the physical surroundings of cells that are undergoing malignant transformation, thereby providing a new method of detection before the development of a clinically or radiologically discernible mass. A literature review was conducted to investigate the evolution of the intraductal approach and its particular application in the field of biomarker discovery, primarily using the intraductal technique of nipple aspiration, in combination with emerging protein profiling techniques.

Nipple fluid basic fibroblast growth factor in patients with breast cancer

PURPOSE

It has been shown that early detection of breast cancer could save lives. Recently, there has been increasing interest in nipple fluid as a potential supplemental avenue for breast cancer diagnosis.

EXPERIMENTAL DESIGN

In this study, we determined the levels of an angiogenic factor basic fibroblast growth factor (bFGF) in the nipple fluid of healthy subjects as well as patients with benign breast conditions, those at high risk for breast cancer, and patients with active breast cancer. ELISAs were used to measure bFGF.

RESULTS

Nipple fluid bFGF levels were as follows (mean +/- SE): 158 +/- 17 pg/mL from benign breasts, 561 +/- 277 pg/mL from high-risk breasts, and 1,343 +/- 441 pg/mL from cancerous breasts. One-way ANOVA showed that the bFGF levels from cancerous breasts were significantly higher than those from benign and high-risk breasts (P = 0.0001 and P = 0.0193, respectively). After logarithmic transformation was applied to the data, high-risk breast bFGF levels were higher than those from benign breasts (P = 0.0028). With a cutoff level of 250 pg/mL, the sensitivity was 79.2%, specificity was 82.5%, and correct diagnosis was 66.4%. The area under the receiver operating characteristic curve was 0.86.

CONCLUSIONS

We conclude that nipple fluid bFGF levels are progressively elevated in high-risk and cancerous breasts compared with benign breasts. The sensitivity and specificity of this test are promising compared with current breast cancer screening methods, and this test deserves further studies with larger clinical trials. Potential areas of usefulness include the detection of breast cancer risk or breast cancer, as well as the monitoring and/or prediction of the antiangiogenic effect of preventive therapies.

Proteomic Analysis to Identify Breast Cancer Biomarkers in Nipple Aspirate Fluid

PURPOSE

Proteomic analysis of breast nipple aspirate fluid (NAF) holds promise as a noninvasive method to identify markers of breast cancer. The objectives of the study were to: (a) describe the NAF proteome, (b) identify candidate markers of breast cancer in NAF by using proteomic analysis, and (c) validate the markers identified by using a quantitative, high-throughput ELISA analysis.

EXPERIMENTAL DESIGN

For proteome analysis, NAF proteins from a single subject without breast cancer were separated by two-dimensional PAGE and were subjected to matrix-assisted laser desorption ionization time-of-flight mass spectometry identification. A total of 41 different proteins were identified, 25 of which were known to be secreted. To identify breast cancer markers, we separated 20 NAF samples (10 normal, 10 cancer) by two-dimensional PAGE. Three protein spots were detected that were up-regulated in three or more cancer samples. These spots were identified to be gross cystic disease fluid protein (GCDFP)-15, apolipoprotein D (apoD), and alpha1-acid glycoprotein (AAG). To validate these three potential biomarkers, 105 samples (53 from benign breasts and 52 from breasts with cancer) were analyzed using ELISA.

RESULTS

Among all of the subjects, GCDFP-15 levels were lower (P <0.001) and AAG levels were higher (P=0.001) in breasts with cancer. This was also true in premenopausal (GCDFP-15, P=0.011; AAG, P=0.002) but not in postmenopausal women. GCDFP-15 levels were lowest (P=0.003) and AAG levels highest (P <0.001) in women with ductal carcinoma in situ (DCIS). Menopausal status influenced GCDFP-15 and AAG more in women without breast cancer than in women with breast cancer. apoD levels did not correlate significantly with breast cancer.

CONCLUSIONS

Our study revealed that the NAF proteome, as defined by two-dimensional PAGE, consists of a limited number of proteins, and that the expression of AAG and GCDFP-15 correlates with disease presence and stage.

Tumor antigens for cancer immunotherapy: therapeutic potential of xenogeneic DNA vaccines

Preclinical animal studies have convincingly demonstrated that tumor immunity to self antigens can be actively induced and can translate into an effective anti-tumor response. Several of these observations are being tested in clinical trials. Immunization with xenogeneic DNA is an attractive approach to treat cancer since it generates T cell and antibody responses. When working in concert, these mechanisms may improve the efficacy of vaccines. The use of xenogeneic DNA in overcoming immune tolerance has been promising not only in inbred mice with transplanted tumors but also in outbred canines, which present with spontaneous tumors, as in the case of human. Use of this strategy also overcomes limitations seen in other types of cancer vaccines. Immunization against defined tumor antigens using a xenogeneic DNA vaccine is currently being tested in early phase clinical trials for the treatment of melanoma and prostate cancers, with proposed trials for breast cancer and Non-Hodgkin's Lymphoma.

Nipple aspirate fluid expression of urokinase-type plasminogen activator, plasminogen activator inhibitor-1, and urokinase-type plasminogen activator receptor predicts breast cancer diagnosis and advanced disease

BACKGROUND

Tumor expression of urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor-1 (PAI-1), and uPA receptor (uPAR) are breast cancer prognostic factors. Less is known about their usefulness in breast cancer diagnosis. Nipple aspirate fluid (NAF) is secreted into the breast duct and collected noninvasively, making it potentially useful both in breast cancer diagnosis and prognosis. We determined the association of uPA, PAI-1, and uPAR levels in NAF with breast cancer (1) detection and (2) advanced disease.

METHODS

A total of 88 NAF specimens were collected from women with or without breast cancer, and uPA, PAI-1, and uPAR expression were measured by enzyme-linked immunosorbent assay.

RESULTS

uPA and uPAR were independent predictors of cancer presence; uPAR was also an independent predictor of advanced disease stage. Higher PAI-1 expression in breast cancer that was found with univariate analysis was not observed after logistic regression was applied.

CONCLUSIONS

NAF evaluation of uPA, uPAR, and, perhaps, PAI-1 (significant only in univariate analysis) may provide useful breast cancer diagnostic and prognostic information.

Prostate-specific antigen expression in nipple aspirate fluid is associated with advanced breast cancer

We previously demonstrated that prostate-specific antigen (PSA) is present in breast nipple aspirate fluid (NAF) and its expression is inversely associated with the presence of breast cancer. The purpose of this study was to determine if PSA levels in NAF decrease with disease progression from DCIS to metastatic breast cancer. One hundred and forty-nine women underwent nipple aspiration before or in conjunction with surgery to treat their breast cancer. PSA levels decreased with more advanced disease stage (P = 0.016), larger tumor size (P = 0.031), and nodal involvement (P = 0.041). PSA levels were lower in women with than without distant disease spread (P = 0.049). We also evaluated the association of PSA with these clinical parameters based on menopausal status. In general, PSA predicted disease involvement better in pre- than in post-menopausal women. There was no association between PSA and race. Spearman's rank analysis demonstrated that PSA was inversely related to tumor size (P = 0.009), nodal status (P = 0.005), disease stage (P = 0.004), and distant metastases (P = 0.04). NAF PSA provides useful prognostic information which may assist with breast cancer treatment.

Ductal lavage: clinical utility and future promise

This article discusses the use of ductal lavage to enhance the tolerability, efficiency, and reproducibility of collecting breast duct epithelial cells for analysis for breast cancer risk assessment. Aspects discussed include the rationale for use of ductal lavage, identification of appropriate candidates for the procedure, clinical implications, ongoing evaluation of the procedure, and its future utility.

Association of uPA, PAT-1, and uPAR in nipple aspirate fluid (NAF) with breast cancer

PURPOSE

Urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor (PAI-1), and uPA receptor (uPAR) are prognostic factors in various cancer types, especially breast cancer. Less is known about the usefulness of these markers in breast cancer diagnosis. We sought to determine (1) whether uPA, PAI-1, and uPAR were detectable in breast nipple aspirate fluid (NAF), a physiologic fluid produced by the breast and collected noninvasively, and (2) the association of these markers in NAF with the presence of breast cancer.

PATIENTS AND METHODS

One hundred twenty NAF specimens were collected from women with and women without breast cancer. uPA, PAI-1, and uPAR expression in NAF was measured by enzyme-linked immunosorbent assay.

RESULTS

Median NAF PAI-1, but not uPA or uPAR, expression was higher in subjects with breast cancer than in those without breast cancer, regardless of whether expression was controlled for total NAF protein level. Median expression of PAI-1 per milligram of total NAF protein was higher in both premenopausal and postmenopausal women who had breast cancer than in women who did not. A multiple logistic regression model that included age, race, menopausal status, uPA, PAI-1, and uPAR level to differentiate patients with regard to cancer risk revealed that uPA, PAI-1, and age were each associated with risk (P < or = 0.019). Women whose NAF contained elevated uPA and PAI-1 levels were more likely to have cancer than women in whom both markers were not elevated.

DISCUSSION

Our data suggest that PAI-1, alone or in combination with uPA, may be useful as a noninvasive biologic marker to aid in the detection of breast cancer.