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

Deciphering a proteomic signature for the early detection of breast cancer from breast milk: the role of quantitative proteomics

INTRODUCTION

Breast cancer is one of the most prevalent cancers among women in the United States. Current research regarding breast milk has been focused on the composition and its role in infant growth and development. There is little information about the proteins, immune cells, and epithelial cells present in breast milk which can be indicative of the emergence of BC cells and tumors.

AREAS COVERED

We summarize all breast milk studies previously done in our group using proteomics. These studies include 1D-PAGE and 2D-PAGE analysis of breast milk samples, which include within woman and across woman comparisons to identify dysregulated proteins in breast milk and the roles of these proteins in both the development of BC and its diagnosis. Our projected outlook for the use of milk for cancer detection is also discussed.

EXPERT OPINION

Analyzing the samples by multiple methods allows one to interrogate a set of samples with various biochemical methods that complement each other, thus providing a more comprehensive proteome. Complementing methods like 1D-PAGE, 2D-PAGE, in-solution digestion and proteomics analysis with PTM-omics, peptidomics, degradomics, or interactomics will provide a better understanding of the dysregulated proteins, but also the modifications or interactions between these proteins.

Nipple fluid for breast cancer diagnosis using the nanopore of Phi29 DNA-packaging motor

Detection of cancer in its early stage is a challenging task for oncologists. Inflammatory breast cancer has symptoms that are similar to mastitis and can be mistaken for microbial infection. Currently, the differential diagnosis between mastitis and Inflammatory breast cancer via nipple aspirate fluid (NAF) is difficult. Here, we report a label-free and amplification-free detection platform using an engineered nanopore of the phi29 DNA-packaging motor with biomarker Galectin3 (GAL3), Thomsen-Friedenreich (TF) binding peptide as the probe fused at its C-terminus. The binding of the biomarker in NAF samples from breast cancer patients to the probe results in the connector's conformational change with a current blockage of 32 %. Utilization of dwell time, blockage ratio, and peak signature enable us to detect basal levels of biomarkers from patient NAF samples at the single-molecule level. This platform will allow for breast cancers to be resolved at an early stage with accuracy and thoroughness.

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.

A randomized controlled trial of metformin in women with components of metabolic syndrome: intervention feasibility and effects on adiposity and breast density

PURPOSE

Obesity is a known risk factor for post-menopausal breast cancer and may increase risk for triple negative breast cancer in premenopausal women. Intervention strategies are clearly needed to reduce obesity-associated breast cancer risk.

METHODS

We conducted a Phase II double-blind, randomized, placebo-controlled trial of metformin in overweight/obese premenopausal women with components of metabolic syndrome to assess the potential of metformin for primary breast cancer prevention. Eligible participants were randomized to receive metformin (850 mg BID, n = 76) or placebo (n = 75) for 12 months. Outcomes included breast density, assessed by fat/water MRI with change in percent breast density as the primary endpoint, anthropometric measures, and intervention feasibility.

RESULTS

Seventy-six percent in the metformin arm and 83% in the placebo arm (p = 0.182) completed the 12-month intervention. Adherence to study agent was high with more than 80% of participants taking ≥ 80% assigned pills. The most common adverse events reported in the metformin arm were gastrointestinal in nature and subsided over time. Compared to placebo, metformin intervention led to a significant reduction in waist circumference (p < 0.001) and waist-to-hip ratio (p = 0.019). Compared to placebo, metformin did not change percent breast density and dense breast volume but led to a numerical but not significant decrease in non-dense breast volume (p = 0.070).

CONCLUSION

We conclude that metformin intervention resulted in favorable changes in anthropometric measures of adiposity and a borderline decrease in non-dense breast volume in women with metabolic dysregulation. More research is needed to understand the impact of metformin on breast cancer risk reduction.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02028221. Registered January 7, 2014, https://clinicaltrials.gov/ct2/show/NCT02028221.

Evaluation of nipple aspirate fluid as a diagnostic tool for early detection of breast cancer

There has been tremendous progress in detection of breast cancer in postmenopausal women, resulting in two-thirds of women surviving more than 20 years after treatment. However, breast cancer remains the leading cause of cancer-related deaths in premenopausal women. Breast cancer is increasing in younger women due to changes in life-style as well as those at high risk as carriers of mutations in high-penetrance genes. Premenopausal women with breast cancer are more likely to be diagnosed with aggressive tumours and therefore have a lower survival rate. Mammography plays an important role in detecting breast cancer in postmenopausal women, but is considerably less sensitive in younger women. Imaging techniques, such as contrast-enhanced MRI improve sensitivity, but as with all imaging approaches, cannot differentiate between benign and malignant growths. Hence, current well-established detection methods are falling short of providing adequate safety, convenience, sensitivity and specificity for premenopausal women on a global level, necessitating the exploration of new methods. In order to detect and prevent the disease in high risk women as early as possible, methods that require more frequent monitoring need to be developed. The emergence of "omics" strategies over the last 20 years, enabling the characterisation and understanding of breast cancer at the molecular level, are providing the potential for long term, longitudinal monitoring of the disease. Tissue and serum biomarkers for breast cancer stratification, diagnosis and predictive outcome have emerged, but have not successfully translated into clinical screening for early detection of the disease. The use of breast-specific liquid biopsies, such as nipple aspirate fluid (NAF), a natural secretion produced by breast epithelial cells, can be collected non-invasively for biomarker profiling. As we move towards an age of active surveillance, home-based liquid biopsy collection kits are increasingly being applied and these could provide a paradigm shift where NAF biomarker profiling is used for routine breast health monitoring. The current status of established and newly emerging imaging techniques for early detection of breast cancer and the potential for alternative biomarker screening of liquid biopsies, particularly those applied to high-risk, premenopausal women, will be reviewed.

Aluminium, carbonyls and cytokines in human nipple aspirate fluids: Possible relationship between inflammation, oxidative stress and breast cancer microenvironment

The human breast is likely exposed to Al (aluminium) from many sources including diet and personal care products. Underarm applications of aluminium salt-based antiperspirant provide a possible long-term source of exposure, especially after underarm applications to shaved and abraded skin. Al research in breast fluids likely reflects the intraductal microenvironment. We found increased levels of aluminium in noninvasively collected nipple aspirate fluids (NAF) from 19 breast cancer patients compared with 16 healthy control subjects (268 vs 131 μg/l, respectively; p < 0.0001). In the same NAF samples we found significantly increased levels of protein oxidative carbonyls in cancer patients compared to healthy women (2.35 vs 0.41 nmol/mg prot, respectively; p < 0.0001). Aluminium content and carbonyl levels showed a significant positive linear correlation (r(2) 0.6628, p < 0.0001). In cancer NAF samples (containing higher amounts of aluminium salts) we also found a significantly increased levels of pro-inflammatory cytokines (IL-1β, IL-6, IL-12 p70, and TNF-α) and chemoattractant CC and CXC chemokines (IL-8, MIP-1α and MCP-1). In 12 invasive cancer NAF samples we found a significant positive linear correlation among aluminium, carbonyls and pro-inflammatory IL-6 cytokine (Y = 64.79x-39.63, r(2) 0.8192, p < 0.0005), as well as pro-inflammatory monocyte chemoattractant MCP-1 cytokine (Y = 2026x-866, r(2) 0.9495, p < 0.0001). In addition to emerging evidence, our results support the possible involvement of aluminium ions in oxidative and inflammatory status perturbations of breast cancer microenvironment, suggesting aluminium accumulation in breast microenvironment as a possible risk factor for oxidative/inflammatory phenotype of breast cells.

Salivary biomarker development using genomic, proteomic and metabolomic approaches

The use of saliva as a diagnostic sample provides a non-invasive, cost-efficient method of sample collection for disease screening without the need for highly trained professionals. Saliva collection is far more practical and safe compared with invasive methods of sample collection, because of the infection risk from contaminated needles during, for example, blood sampling. Furthermore, the use of saliva could increase the availability of accurate diagnostics for remote and impoverished regions. However, the development of salivary diagnostics has required technical innovation to allow stabilization and detection of analytes in the complex molecular mixture that is saliva. The recent development of cost-effective room temperature analyte stabilization methods, nucleic acid pre-amplification techniques and direct saliva transcriptomic analysis have allowed accurate detection and quantification of transcripts found in saliva. Novel protein stabilization methods have also facilitated improved proteomic analyses. Although candidate biomarkers have been discovered using epigenetic, transcriptomic, proteomic and metabolomic approaches, transcriptomic analyses have so far achieved the most progress in terms of sensitivity and specificity, and progress towards clinical implementation. Here, we review recent developments in salivary diagnostics that have been accomplished using genomic, transcriptomic, proteomic and metabolomic approaches.

Salivary diagnostics

Saliva is a noninvasive and accessible biofluid that permits early detection of oral and systemic diseases. Recent scientific and technologic advances have uncovered specific salivary biomarkers for a number of clinical conditions, including cancers, autoimmune diseases, and cardiovascular disorders. The availability of highly sensitive and high-throughput assays such as microarray, mass spectrometry, reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) and nano-scale sensors that can measure proteins and nucleic acids are poising saliva as an emerging biofluid for translational and clinical applications. This paper will discuss development of salivary biomarkers for the detection of oral and systemic diseases and the translational application of these markers for clinical applications.

Discovery and preclinical validation of salivary transcriptomic and proteomic biomarkers for the non-invasive detection of breast cancer

Background

A sensitive assay to identify biomarkers using non-invasively collected clinical specimens is ideal for breast cancer detection. While there are other studies showing disease biomarkers in saliva for breast cancer, our study tests the hypothesis that there are breast cancer discriminatory biomarkers in saliva using de novo discovery and validation approaches. This is the first study of this kind and no other study has engaged a de novo biomarker discovery approach in saliva for breast cancer detection. In this study, a case-control discovery and independent preclinical validations were conducted to evaluate the performance and translational utilities of salivary transcriptomic and proteomic biomarkers for breast cancer detection.

Methodology/Principal Findings

Salivary transcriptomes and proteomes of 10 breast cancer patients and 10 matched controls were profiled using Affymetrix HG-U133-Plus-2.0 Array and two-dimensional difference gel electrophoresis (2D-DIGE), respectively. Preclinical validations were performed to evaluate the discovered biomarkers in an independent sample cohort of 30 breast cancer patients and 63 controls using RT-qPCR (transcriptomic biomarkers) and quantitative protein immunoblot (proteomic biomarkers). Transcriptomic and proteomic profiling revealed significant variations in salivary molecular biomarkers between breast cancer patients and matched controls. Eight mRNA biomarkers and one protein biomarker, which were not affected by the confounding factors, were pre-validated, yielding an accuracy of 92% (83% sensitive, 97% specific) on the preclinical validation sample set.

Conclusions

Our findings support that transcriptomic and proteomic signatures in saliva can serve as biomarkers for the non-invasive detection of breast cancer. The salivary biomarkers possess discriminatory power for the detection of breast cancer, with high specificity and sensitivity, which paves the way for prediction model validation study followed by pivotal clinical validation.

Nipple Aspirate Fluid Proteome of Healthy Females and Patients with Breast Cancer

Background: The ductal/alveolar system of the female breast constantly secretes and reabsorbs fluid in nonpregnant/nonlactating women. This fluid, referred to as nipple aspirate fluid (NAF), can be obtained by a noninvasive procedure and it is part of the microenvironment where more than 95% of breast cancers arise.

Methods: Using an Orbitrap® mass analyzer coupled to a linear ion trap, we performed an in-depth proteomic analysis of NAF samples obtained from 3 healthy individuals and 3 patients with breast cancer. Multiple fractionation methods such as size-exclusion and anion-exchange chromatography were applied for protein separation before mass spectrometric analysis.

Results: We identified more than 800 unique proteins in total, generating the most extensive NAF proteome thus far. Using gene ontology, we classified the identified proteins by their subcellular localization and found that more than 50% were extracellular or plasma membrane proteins. By searching against the Plasma Proteome Database, we confirmed that 40% of the proteins were also found in the plasma. Unigene database searching for transcripts of the proteins not found in the plasma revealed that the vast majority were expressed in the mammary gland.

Conclusions: Our extensive proteome database for NAF may be helpful in the identification of novel cancer biomarkers.

Microdialysis combined with proteomics for protein identification in breast tumor microenvironment in vivo

Tumor microenvironment constitutes a reservoir for proteins released from tumor cells and the host, which can contribute significantly to tumor growth and invasion. This study aims to apply a method of combining in vivo microdialysis and proteomics to identify proteins in mammary tumor interstitial fluids, a major component of tumor microenvironment. In vivo microdialysis was performed in polyomavirus middle T antigen (PyVmT) transgenic mouse mammary tumors and age-matched control wild-type mammary glands. Over four hundred proteins were identified from the microdialysis perfusates, using the Multidimensional Protein Identification Technology. Osteopontin (OPN) is one of the proteins overexpressed in breast tumor perfusates, as confirmed with immunoassays. OPN was also found to be present in tumor-associated stroma in both PyVmT and human breast tumors, using immunohistochemistry. Specifically, fibroblasts were further shown to express OPN at both mRNA and protein levels. In vitro assays showed that OPN can stimulate PyVmT breast carcinoma cell proliferation and migration. Finally, the expression of OPN was significantly higher in the peripheral blood of mice bearing breast tumors, compared to wild-type mice. Overall, microdialysis combined with proteomics is a unique technique for identifying proteins in a tumor microenvironment in vivo. Mammary fibroblasts can secrete OPN, and its overexpression in mammary tumor microenvironment may contribute significantly to mammary tumor progression.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (doi:10.1007/s12307-010-0046-3) contains supplementary material, which is available to authorized users.

Intracrinology of breast microenvironment: hormonal status in nipple aspirate fluid and its relationship to breast cancer

Breast cancer, a complex and multifactorial disease, is the most commonly diagnosed malignancy affecting women. Methods currently available for breast cancer detection have well-described limitations; in this respect, the intraductal approaches directly assess the microenvironment of the breast. Nipple aspirate fluid (NAF) can be noninvasively obtained from the breast in most women and represents a promising biological tool to assess metabolic, hormonal and molecular changes occurring in the cells lining the ducts, from which breast cancer arises. The aim of this review is to highlight the application of NAF studies in the field of biomarker discovery, which provide results useful for early detection and prevention of breast cancer risk; in fact, the analysis of NAF (mirroring the ductal-lobular microenvironment) is a reliable method for assessment of metabolic/hormonal pathways within the mammary gland, identifying biomolecular mechanisms of breast cancer initiation and progression. The intracrinology of breast microenvironment (i.e., hormonal status in NAF) may provide independent diagnostic/prognostic factors, highlighting the importance of early altered hormonal metabolism (e.g., aromatase, estrogen sulfotransferase and steroid sulfatase pathway) in relation to breast cancer initiation. The possible application of targeted therapies through the inhibition of intratumoral enzymes involved in steroid metabolism is also discussed. The intraductal approach to hormone analyses may provide a further panel of biomarkers providing clinical benefits and strengthening the armory against breast cancer.

Does the new automated "HALO" nipple aspiration fluid system really deliver as promised? The answer is "No, but...": A literature review of the role of breast fluid cytology in cancer risk assessment

The HALO breast Pap test is a new automated nipple aspiration fluid (NAF) system that was recently introduced into the market. In an extensive marketing campaign directed principally toward OB/GYN practices, including endorsements from few local news media, HALO has been promoted as the "new Pap screening test for breast." Physicians are encouraged to perform this test on all women, as part of their annual examination, with claims that HALO will detect breast cancers as early as 10 years before mammography. These arguments are made more appealing to physician's offices by highlighting the potential positive financial impact on their practices, without consuming physician time, as medical assistants or technicians can perform this test. As a result of this directed campaign, cytology laboratories are increasingly confronted with implementing the HALO system and clinicians are increasingly soliciting pathologist's input regarding its validity. Yet, there is no data available regarding this new system, outside rare reports sponsored by the manufacturer. In this discussion, I examine the pros and cons of this new NAF system, including literature review of breast fluid cytology, and how it relates to breast cancer risk assessment.

Nutrients and nipple aspirate fluid composition: the breast microenvironment regulates protein expression and cancer aetiology

The aetiology of breast cancer is complex and multifactorial, and may include diet and xenobiotic compounds. A change in diet affects nutrient levels in blood, but to what extent diet can affect micronutrient concentrations in the breast is not yet well established. Breast nipple aspirate fluids (NAF) can be non-invasively obtained from the breast in most women; it represents a biological tool to assess metabolic changes in the breast ductal microenvironment. A wide variation in biomolecular and hormonal composition of NAFs collected from healthy and breast cancer patient may be due to genetic and nutritional factors; however, micro- and macro-nutrients may influence the secretory status of these women, thus NAF composition and risk of breast carcinoma. The aim of this overview is to highlight the detrimental/beneficial role that diet-related compounds in nipple aspirate fluid can have in breast cancer risk.