Human breast development

Volumetric analysis of the terminal ductal lobular unit architecture and cell phenotypes in the human breast

The major lactiferous ducts of the human breast branch out and end at terminal ductal lobular units (TDLUs). Despite their functional and clinical importance, the three-dimensional (3D) architecture of TDLUs has remained undetermined. Our quantitative and volumetric imaging of healthy human breast tissue demonstrates that highly branched TDLUs, which exhibit increased proliferation, are uncommon in the resting tissue regardless of donor age, parity, or hormonal contraception. Overall, TDLUs have a consistent shape and branch parameters, and they contain a main subtree that dominates in bifurcation events and exhibits a more duct-like keratin expression pattern. Simulation of TDLU branching morphogenesis in three dimensions suggests that evolutionarily conserved mechanisms regulate mammary gland branching in humans and mice despite their anatomical differences. In all, our data provide structural insight into 3D anatomy and branching of the human breast and exemplify the power of volumetric imaging in gaining a deeper understanding of breast biology.

The mammary hair of Monodelphis domestica and homology of the mammary pilosebacous unit

The unitary mammary gland is a synapomorphy of therian mammals and is thought to have evolved from the pilosebaceous organ in the mammalian stem lineage from which the lactogenic patch of monotremes is also derived. One of the key lines of evidence for the homology of the nipple and the lactogenic patch is that marsupials have retained a transient hair associated with developing mammary glands. However, these structures have not been documented since the early 20th-century drawings of Ernst Bresslau. In this study, we examine the developing mammary organs of Monodelphis domestica and document the presence of mammary hairs in 12-week-old females, as well as their absence after 18 weeks of age. Histochemical staining for cystine confirms the structures as keratinized hairs. Milk ducts of both juvenile and adult nipples show a division between KRT18+ luminal epithelium and KRT14+ ACTA2+ myoepithelium. These patterns match those in eutherians and suggest a conserved ductal morphology and mechanism of milk expulsion. Finally, PTHLH, a peptide hormone which promotes homeotic transformation of hairy skin into hairless nipples in the mouse, was detected in the Monodelphis milk duct during the mammary hair stage, suggesting that the mutual exclusivity of "hairless nipple" and "hair" organ identity is derived in eutherian mammals. These results reveal shared characteristics of the M. domestica nipple with both the eutherian nipple and the pilosebaceous organ, consistent with the evolutionary derivation of the mammary gland from an ancestral hair organ via developmental individualization of pilosebaceous and mammary identities.

Stem Cell Division and Its Critical Role in Mammary Gland Development and Tumorigenesis: Current Progress and Remaining Challenges

The origin of breast cancer (BC) has traditionally been a focus of medical research. It is widely acknowledged that BC originates from immortal mammary stem cells and that these stem cells participate in two division modes: symmetric cell division (SCD) and asymmetrical cell division (ACD). Although both of these modes are key to the process of breast development and their imbalance is closely associated with the onset of BC, the molecular mechanisms underlying these phenomena deserve in-depth exploration. In this review, we first outline the molecular mechanisms governing ACD/SCD and analyze the role of ACD/SCD in various stages of breast development. We describe that the changes in telomerase activity, the role of polar proteins, and the stimulation of ovarian hormones subsequently lead to two distinct consequences: breast development or carcinogenesis. Finally, gene mutations, abnormalities in polar proteins, modulation of signal-transduction pathways, and alterations in the microenvironment disrupt the balance of BC stem cell division modes and cause BC. Important regulatory factors such as mammalian Inscuteable mInsc, Numb, Eya1, PKCα, PKCθ, p53, and IL-6 also play significant roles in regulating pathways of ACD/SCD and may constitute key targets for future research on stem cell division, breast development, and tumor therapy.

Association between early-life mosquito repellents exposure and ADHD-like behaviours

BACKGROUND

Limited research has explored the impact of mosquito repellents exposure during early life on ADHD symptoms. This study aimed to explore the associations of exposure to mosquito repellents from pregnancy to 3 years old and the prevalence of ADHD-like behaviours among children aged 3-9 years, and further identify the sensitive exposure period.

METHODS

A cross-sectional study was conducted, including 12 275 children in Hefei City, China. Exposure was self-reported via primary caregivers. ADHD-like behaviours were measured by the Swanson, Nolan and Pelham, version IV scale (SNAP-IV), and Conners' Parent Rating Scale (CPRS). Cross-over analysis, binary logistic regression and linear regression were employed.

RESULTS

After adjusting for confounding variables, early-life exposure to mosquito repellents was associated with a higher risk of ADHD-like behaviours (OR = 1.81, 95% CI = 1.49-2.19). By comparing the strength of the association for each subgroup, we found exposure during 1-3 years old was a sensitive period (OR = 1.89, 95% CI = 1.25-2.87) by the cross-over analysis. Furthermore, we found a dose-response relationship in which the likelihood of ADHD-like behaviours increased with children's early-life mosquito repellents exposure dose.

CONCLUSIONS

Early-life exposure to mosquito repellents is linked with an elevated risk of ADHD-like behaviours in children, with a sensitive period identified during 1-3 years old.

Dorsal ectopic breast-a cutaneous marker of occult spinal dysraphism

Ectopic breasts represent uncommon medical anomalies characterized by the presence of additional breasts situated outside the typical milk line. In this case report, we present a case encompassing dorsal ectopic breasts accompanied by three nipples. A 14-year-old teen girl presented with a significant dorsal mass, exhibiting no clinical manifestations except mild pain and a sense of heaviness. She underwent investigations, and a magnetic resonance imaging scan revealed a large, inadequately encapsulated congenital mass with a fatty composition, alongside intraspinal epidural engagement and a bony structure bridging the spinous processes from the C6 to the T3 vertebral bodies. She subsequently underwent excision of the entire mass. The histopathological analysis identified the presence of a mammary hamartoma. Follow-up at 2 weeks postoperatively showed that there were no further complications. Dorsal ectopic breast necessitates careful and comprehensive evaluation to either confirm or exclude the presence of occult spinal dysraphism prior to intervention to avoid complications.

Imaging the Male Breast: Gynecomastia, Male Breast Cancer, and Beyond

The number of men undergoing breast imaging has increased in recent years, according to some reports. Most male breast concerns are related to benign causes, most commonly gynecomastia. The range of abnormalities typically encountered in the male breast is less broad than that encountered in women, given that lobule formation rarely occurs in men. Other benign causes of male breast palpable abnormalities with characteristic imaging findings include lipomas, sebaceous or epidermal inclusion cysts, and intramammary lymph nodes. Male breast cancer (MBC) is rare, representing up to 1% of breast cancer cases, but some data indicate that its incidence is increasing. MBC demonstrates some clinical features that overlap with those of gynecomastia, including a propensity for the subareolar breast. Men with breast cancer tend to present at a later stage than do women. MBC typically has similar imaging features to those of female breast cancer, often characterized by an irregular mass that may have associated calcifications. Occasionally, however, MBC has a benign-appearing imaging phenotype, with an oval shape and circumscribed margins, and therefore most solid breast masses in men require tissue diagnosis. Histopathologic evaluation may alternatively reveal other benign breast masses found in men, including papillomas, myofibroblastomas, and hemangiomas. Radiologists must be familiar with the breadth of male breast abnormalities to meet the rising challenge of caring for these patients. ©RSNA, 2024 Supplemental material is available for this article.

Adipo-Epithelial Transdifferentiation in In Vitro Models of the Mammary Gland

Subcutaneous adipocytes are crucial for mammary gland epithelial development during pregnancy. Our and others' previous data have suggested that adipo-epithelial transdifferentiation could play a key role in the mammary gland alveolar development. In this study, we tested whether adipo-epithelial transdifferentiation occurs in vitro. Data show that, under appropriate co-culture conditions with mammary epithelial organoids (MEOs), mature adipocytes lose their phenotype and acquire an epithelial one. Interestingly, even in the absence of MEOs, extracellular matrix and diffusible growth factors are able to promote adipo-epithelial transdifferentiation. Gene and protein expression studies indicate that transdifferentiating adipocytes exhibit some characteristics of milk-secreting alveolar glands, including significantly higher expression of milk proteins such as whey acidic protein and β-casein. Similar data were also obtained in cultured human multipotent adipose-derived stem cell adipocytes. A miRNA sequencing experiment on the supernatant highlighted mir200c, which has a well-established role in the mesenchymal-epithelial transition, as a potential player in this phenomenon. Collectively, our data show that adipo-epithelial transdifferentiation can be reproduced in in vitro models where this phenomenon can be investigated at the molecular level.

Epithelial IL-2 is critical for NK cell-mediated cancer immunosurveillance in mammary glands

Interleukin 2 (IL-2) is the first identified cytokine and its interaction with receptors has been known to shape the immune responses in many lymphoid or non-lymphoid tissues for more than four decades. Active T cells are the primary cellular source for IL-2 production and epithelial cells have never been considered the major cellular source of IL-2 under physiological conditions. It is, however, tempting to speculate that epithelial cells could potentially express IL-2 that regulates the intricate interactions between epithelial cells and lymphocytes. Datamining our recently published single-cell RNAseq in the mouse mammary gland identified IL-2 expression in mammary epithelial cells, which is induced by prolactin via the STAT5 signaling pathway. Furthermore, epithelial IL-2 plays a crucial role in maintaining the physiological functions of natural killer (NK) cells within the mammary glands. IL-2 deletion in the mammary epithelial cells leads to a significant reduction in the number and function of NK cells, which in turn results in defective immunosurveillance, expansion of luminal epithelial cells, and tumor development. Interestingly, T cells in the mammary glands are not changed, indicating the specific regulation of NK cells by epithelial IL-2 production. In agreement, we also found that human epithelial cells express IL-2 and NK cells express the highest level of IL2RB among all the immune cells. Here, we provide the first evidence that epithelial cells produce IL-2, which is critical for maintaining the physiological functions of NK cells in immunosurveillance.

Untargeted serum metabolomic profiles and breast density in young women

PURPOSE OF THE STUDY

Breast density is an established risk factor for breast cancer. However, little is known about metabolic influences on breast density phenotypes. We conducted untargeted serum metabolomics analyses to identify metabolic signatures associated with breast density phenotypes among young women.

METHODS

In a cross-sectional study of 173 young women aged 25-29 who participated in the Dietary Intervention Study in Children 2006 Follow-up Study, 449 metabolites were measured in fasting serum samples using ultra-high-performance liquid chromatography-tandem mass spectrometry. Multivariable-adjusted mixed-effects linear regression identified metabolites associated with magnetic resonance imaging measured breast density phenotypes: percent dense breast volume (%DBV), absolute dense breast volume (ADBV), and absolute non-dense breast volume (ANDBV). Metabolite results were corrected for multiple comparisons using a false discovery rate adjusted p-value (q).

RESULTS

The amino acids valine and leucine were significantly inversely associated with %DBV. For each 1 SD increase in valine and leucine, %DBV decreased by 20.9% (q = 0.02) and 18.4% (q = 0.04), respectively. ANDBV was significantly positively associated with 16 lipid and one amino acid metabolites, whereas no metabolites were associated with ADBV. Metabolite set enrichment analysis also revealed associations of distinct metabolic signatures with %DBV, ADBV, and ANDBV; branched chain amino acids had the strongest inverse association with %DBV (p = 0.002); whereas, diacylglycerols and phospholipids were positively associated with ANDBV (p ≤ 0.002), no significant associations were observed for ADBV.

CONCLUSION

Our results suggest an inverse association of branched chain amino acids with %DBV. Larger studies in diverse populations are needed.

Increasing Breast Support is Associated With a Distal-to-Proximal Redistribution of Joint Negative Work During a Double-Limb Landing Task

Female athletes exhibit greater rates of anterior cruciate ligament injury compared with male athletes. Biomechanical factors are suggested to contribute to sex differences in injury rates. No previous investigation has evaluated the role of breast support on landing biomechanics. This study investigates the effect of breast support on joint negative work and joint contributions to total negative work during landing. Thirty-five female athletes performed 5 landing trials in 3 breast support conditions. Lower-extremity joint negative work and relative joint contributions to total negative work were calculated. Univariate analyses of variance were used to determine the effect of breast support on negative joint work values. Increasing levels of breast support were associated with lower ankle negative work (P < .001) and ankle relative contributions (P < .001) and increases in hip negative work (P = .008) and hip relative contributions (P < .001). No changes were observed in total negative work (P = .759), knee negative work (P = .059), or knee contributions to negative work (P = .094). These data demonstrate that the level of breast support affects lower-extremity biomechanics. The distal-to-proximal shift in negative joint work and relative joint contributions may be indicative of a more protective landing strategy for anterior cruciate ligament injuries.

Nonmass Lesions on Breast US: An International Perspective on Clinical Use and Outcomes

Nonmass lesions (NMLs) on breast US are defined as discrete areas of altered echotexture compared to surrounding breast tissue and lack the 3-dimensionality of a mass. They are not a component of American College of Radiology BI-RADS, but they are a finding type included in the Japan Association of Breast and Thyroid Sonology lexicon. Use of the NML finding is routine in many Asian practices, including the Samsung Medical Center and Seoul National University Hospital, and their features and outcomes have been investigated in multiple studies. Nonmass lesions are most often observed when US is used to evaluate mammographic asymmetries, suspicious calcifications, and nonmass enhancement on MRI and contrast-enhanced mammography. Nonmass lesions can be described by their echogenicity, distribution, presence or absence of associated calcifications, abnormal duct changes, architectural distortion, posterior shadowing, small cysts, and hypervascularity. Malignant lesions, especially ductal carcinoma in situ, can manifest as NMLs on US. There is considerable overlap between the US features of benign and malignant NMLs, and they also must be distinguished from normal variants. The literature indicates that NMLs with linear or segmental distribution, associated calcifications, abnormal duct changes, posterior shadowing, and hypervascularity are suggestive of malignancy, whereas NMLs with only interspersed small cysts are usually benign fibrocystic changes. In this article, we introduce the concepts of NMLs, illustrate US features suggestive of benign and malignant etiologies, and discuss our institutional approach for evaluating NMLs and an algorithm that we use to guide interpretation in clinical practice.

Modeling Mammary Organogenesis from Biological First Principles: A Systems Biology Approach

Stromal-epithelial interactions mediate mammary gland development and the formation and progression of breast cancer. To study these interactions in vitro, 3D models are essential. We have successfully developed novel 3D in vitro models that allow the formation of mammary gland structures closely resembling those found in vivo and that respond to the hormonal cues that regulate mammary gland morphogenesis and function. Due to their simplicity when compared to in vivo studies, and to their accessibility to visualization in real time, these models are well suited to conceptual and mathematical modeling.

Changes in the mammary gland during aging and its links with breast diseases

The functional capacity of organisms declines in the process of aging. In the case of breast tissue, abnormal mammary gland development can lead to dysfunction in milk secretion, a primary function, as well as the onset of various diseases, such as breast cancer. In the process of aging, the terminal duct lobular units (TDLUs) within the breast undergo gradual degeneration, while the proportion of adipose tissue in the breast continues to increase and hormonal levels in the breast change accordingly. Here, we review changes in morphology, internal structure, and cellular composition that occur in the mammary gland during aging. We also explore the emerging mechanisms of breast aging and the relationship between changes during aging and breast-related diseases, as well as potential interventions for delaying mammary gland aging and preventing breast disease.

Axillary accessory breast cancer reconstructed by a thoracodorsal artery perforator flap: A case report

INTRODUCTION

Primary accessory breast cancer is rare and most commonly occurs in the axilla. Due to its low incidence, few studies have discussed axillary reconstruction after accessory breast cancer resection. In the present report, we describe a patient who underwent axillary reconstruction with a thoracodorsal artery perforator (TAP) flap after resection, and reconstruction methods after resection of axillary accessory breast cancer are discussed based on current and previous reports.

PATIENT CONCERNS

A 60-year-old woman presented with a 7-year history of a gradually growing lump in the left axilla.

DIAGNOSIS

The patient was diagnosed with latent breast cancer, axillary lymph node metastasis, or carcinoma of the accessory axillary breast with axillary lymph node metastasis.

INTERVENTIONS

After preoperative chemotherapy, tumor resection and axillary lymph node dissection were performed, followed by immediate axillary reconstruction using a TAP flap. The patient received postoperative adjuvant endocrine and radiation therapy (50 Gy).

OUTCOMES

No recurrence or metastasis was observed for 5 years postoperatively. The reconstructed axilla was not bulky, and scar contracture was not observed, with a full range of motion of the shoulder joint.

CONCLUSION

We described a patient who underwent immediate TAP flap reconstruction after resection of accessory breast cancer and axillary lymph node dissection, followed by postoperative radiation, which could cause scar contracture. The patient was followed up for more than 5 years after the operation and radiation therapy, and the appearance of the axilla and range of motion of the shoulder were good despite postoperative radiation.

Analysis of background echotexture on automated breast ultrasound using BI-RADS and modified classification: Association with clinical features and mammographic density

PURPOSE

To analyze BE on ABUS using BI-RADS and a modified classification in association with mammographic density and clinical features.

METHODS

Menopausal status, parity, and family history of breast cancer were collected for 496 women who underwent ABUS and mammography. Three radiologists independently reviewed all ABUS BE and mammographic density. Statistical analyses including kappa statistics (κ) for interobserver agreement, Fisher's exact test, and univariate and multivariate multinomial logistic regression were performed.

RESULTS

BE distribution between the two classifications and between each classification and mammographic density were associated (P < 0.001). BI-RADS homogeneous-fibroglandular (76.8%) and modified heterogeneous BE (71.3%, 75.7%, and 87.5% of mild, moderate, and marked heterogeneous background echotexture, respectively) tended to be dense. BE was correlated between BI-RADS homogeneous-fat and modified homogeneous background (95.1%) and between BI-RADS homogeneous-fibroglandular or heterogeneous (90.6%) and modified heterogeneous (86.9%) (P < 0.001). In multinomial logistic regression, age < 50 years was independently associated with heterogeneous BE (OR, 8.89, P = 0.003, in BI-RADS; OR, 3.74; P = 0.020 in modified classification).

CONCLUSION

BI-RADS homogeneous-fat and modified homogeneous BE on ABUS was likely to be mammographically fatty. However, BI-RADS homogeneous-fibroglandular or heterogeneous BE might be classified as any modified BE. Younger age was independently associated with heterogeneous BE.

Hormonal regulation of mammary gland development and lactation

Lactation is critical to infant short-term and long-term health and protects mothers from breast cancer, ovarian cancer and type 2 diabetes mellitus. The mammary gland is a dynamic organ, regulated by the coordinated actions of reproductive and metabolic hormones. These hormones promote gland development from puberty onwards and induce the formation of a branched, epithelial, milk-secreting organ by the end of pregnancy. Progesterone withdrawal following placental delivery initiates lactation, which is maintained by increased pituitary secretion of prolactin and oxytocin, and stimulated by infant suckling. After weaning, local cytokine production and decreased prolactin secretion trigger large-scale mammary cell loss, leading to gland involution. Here, we review advances in the molecular endocrinology of mammary gland development and milk synthesis. We discuss the hormonal functions of the mammary gland, including parathyroid hormone-related peptide secretion that stimulates maternal calcium mobilization for milk synthesis. We also consider the hormonal composition of human milk and its associated effects on infant health and development. Finally, we highlight endocrine and metabolic diseases that cause lactation insufficiency, for example, monogenic disorders of prolactin and prolactin receptor mutations, maternal obesity and diabetes mellitus, interventions during labour and delivery, and exposure to endocrine-disrupting chemicals such as polyfluoroalkyl substances in consumer products and other oestrogenic compounds.

First report of bilateral synchronous male accessory breast cancer

Accessory breast occurs due to the persistence of milk line in the non-thoracic region. Malignant transformation in male accessory breast is very rare, with 16 reports documented across the world. No bilateral synchronous accessory male breast cancer has been reported. We present the first case reported globally of a man in his 70s with a complaint of left axillary lump and chronic rash for 3 years. About 1 year ago, additional reddish rash was detected in the right axilla. Initial skin biopsy from a private hospital confirmed mammary carcinoma with skin invasion. Subsequent left breast mastectomy with left axillary lymph node dissection and right wide excision was performed. Final pathological result was grade 2 invasive ductal carcinoma in the left accessory breast and Paget's disease in the contralateral axilla. Postoperative treatment of adjuvant paclitaxel and trastuzumab was prescribed, which was followed by adjuvant radiation therapy.

Comparison of the background echotexture between automated breast ultrasound and handheld breast ultrasound

This study aimed to compare the background echotexture (BE) between automated breast ultrasound (ABUS) and handheld breast ultrasound (HHUS) and evaluate the correlation of BE with mammographic (MG) density and background parenchymal enhancement (BPE) on magnetic resonance imaging (MRI). A total of 212 women with newly diagnosed breast cancer who had undergone preoperative ABUS, HHUS, MG, and MRI were included. Two breast radiologists blinded to the menopausal status analyzed the BE of the contralateral breasts of the patients with breast cancer in consensus. The MG density and BPE of breast MRI on the radiologic reports were compared with the BE in the ultrasound. We used the cumulative link mixed model to compare the BE and Spearman rank correlation to evaluate the association between BE with MG density and BPE. BE was more heterogeneous in ABUS than in HHUS (P < .001) and in the premenopausal group than in the postmenopausal group (P < .001). The heterogeneity of BE in the premenopausal group was higher with ABUS than with HHUS (P = .013). BE and MG density showed a moderate correlation in the postmenopausal group, but a weak correlation in the premenopausal group. BE and BPE showed moderate correlations only in the premenopausal group. ABUS showed a more heterogeneous BE, especially in the premenopausal group. Therefore, more attention is required to interpret ABUS screening in premenopausal women.

Ectopic Breast Tissue in the Inguinal Region: A Case Report and Suggestion of Indications for Excision

We report a rare case of ectopic breast tissue situated in a unique location. A 50-year-old female patient came to our institution complaining of a bulge in the inguinal area. CT was unremarkable other than a benign-looking conglomeration of lymph nodes around the inguinal canal. However, excisional biopsy proved otherwise, with strong expression of breast-related immunohistochemical markers on pathology. Based on histological findings, the diagnosis of ectopic breast tissue was made. Since the vast majority of ectopic breast tissue is found around the breast mound, axilla, and along the milk line, this case is peculiar in its location. This report shares our experience and provides indications for excision of incidental ectopic breast tissue.

Mammary gland physiology and farm management of dairy mares and jennies

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The equid udder has a lower storage capacity than the ruminant udder.

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Milking frequency is one of the most important factors affecting milk yield.

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Foals can be partly artificially suckled during lactation.

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Mechanical milking has been used in equids but our understanding of machine milking remains poor.

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Automated milking systems for equids represent a great challenge for the future.

Equid milk is arousing increasing interest in consumers and researchers because of its similarity in composition to human milk. The low and different protein content makes equid milk it suitable for children with cow milk protein allergy. Both horse and milk production, in many farms, still follow a characteristic and traditional method of separating the foal from the mother to allow milking procedures. This separation lasts at least 2 to 3 h before milking, a time in which the foal remains fasting. This operation is repeated several times a day, as the equid udder has little collection capacity, and milking frequency is one of the most important parameters to increase milk production; it must be emptied often. New partial artificially suckling techniques have been developed that allow the foal to be separated from its mother for many hours without starving. Furthermore, mechanical milking has been introduced in equid milk production, although in-depth knowledge is lacking on milking parameters and how these aspects affect milk production and udder health. Moreover, in some farms, new milking parlors for Equidae have been developed, ensuring that stress is minimized and production and animal welfare are ensured. It is important to develop and apply technologies for equid milk production, evaluating potential effects on welfare, health, and milk production. This represents the broadest perspective and the greatest challenge because of the need to understand management best practices, thinking to the possibility to introduce as soon as possible automatic milking systems that could ensure a good milking frequency.

Functional annotation of breast cancer risk loci: current progress and future directions

Genome-wide association studies coupled with large-scale replication and fine-scale mapping studies have identified more than 150 genomic regions that are associated with breast cancer risk. Here, we review efforts to translate these findings into a greater understanding of disease mechanism. Our review comes in the context of a recently published fine-scale mapping analysis of these regions, which reported 352 independent signals and a total of 13,367 credible causal variants. The vast majority of credible causal variants map to noncoding DNA, implicating regulation of gene expression as the mechanism by which functional variants influence risk. Accordingly, we review methods for defining candidate-regulatory sequences, methods for identifying putative target genes and methods for linking candidate-regulatory sequences to putative target genes. We provide a summary of available data resources and identify gaps in these resources. We conclude that while much work has been done, there is still much to do. There are, however, grounds for optimism; combining statistical data from fine-scale mapping with functional data that are more representative of the normal "at risk" breast, generated using new technologies, should lead to a greater understanding of the mechanisms that influence an individual woman's risk of breast cancer.

The Mammary Gland: Basic Structure and Molecular Signaling during Development

The mammary gland is a compound, branched tubuloalveolar structure and a major characteristic of mammals. The mammary gland has evolved from epidermal apocrine glands, the skin glands as an accessory reproductive organ to support postnatal survival of offspring by producing milk as a source of nutrition. The mammary gland development begins during embryogenesis as a rudimentary structure that grows into an elementary branched ductal tree and is embedded in one end of a larger mammary fat pad at birth. At the onset of ovarian function at puberty, the rudimentary ductal system undergoes dramatic morphogenetic change with ductal elongation and branching. During pregnancy, the alveolar differentiation and tertiary branching are completed, and during lactation, the mature milk-producing glands eventually develop. The early stages of mammary development are hormonal independent, whereas during puberty and pregnancy, mammary gland development is hormonal dependent. We highlight the current understanding of molecular regulators involved during different stages of mammary gland development.

Exocrine gland structure-function relationships

Fluid secretion by exocrine glandular organs is essential to the survival of mammals. Each glandular unit within the body is uniquely organized to carry out its own specific functions, with failure to establish these specialized structures resulting in impaired organ function. Here, we review glandular organs in terms of shared and divergent architecture. We first describe the structural organization of the diverse glandular secretory units (the end-pieces) and their fluid transporting systems (the ducts) within the mammalian system, focusing on how tissue architecture corresponds to functional output. We then highlight how defects in development of end-piece and ductal architecture impacts secretory function. Finally, we discuss how knowledge of exocrine gland structure-function relationships can be applied to the development of new diagnostics, regenerative approaches and tissue regeneration.

Mammary Fibrocystic Change in a Pre-Pubertal child- A Case Report with a Histopathological Perspective

Fibrocystic change in the breast is one of the entities under the spectrum of benign breast disease. It occurs primarily in females of the reproductive age group. Though the exact etiology is unknown, estrogen-progesterone imbalance is possibly one of the causative factors. Its occurrence in the pediatric age group is infrequent and is hitherto unreported in the pre-pubertal age group. Case report: We present the case of a 2-year-old female presenting with an ill -defined lump approximately 4 cm in diameter, with an unremarkable hormonal status for the age. Histopathology revealed fibrocystic change in the resected tissue. Conclusion: Fibrocystic breast change in children may represent an exaggeration of the normal developmental involution process.

Breast development in pediatric patients from birth to puberty: physiology, pathology and imaging correlation

Breast tissue undergoes a series of changes from birth to puberty. The majority of the changes are transient, related to physiological hormonal changes. Although the breast is identical in both sexes at birth, its histology and development will eventually differ. It is important for radiologists to have a basic understanding of endocrinological changes and appearance on imaging to avoid potential pitfalls, particularly on ultrasound, which is the primary modality used to evaluate the breast.

Developing ovine mammary terminal duct lobular units have a dynamic mucosal and stromal immune microenvironment

The human breast and ovine mammary gland undergo striking levels of postnatal development, leading to formation of terminal duct lobular units (TDLUs). Here we interrogate aspects of sheep TDLU growth as a model of breast development and to increase understanding of ovine mammogenesis. The distributions of epithelial nuclear Ki67 positivity differ significantly between younger and older lambs. Ki67 expression is polarised to the leading edge of the developing TDLUs. Intraepithelial ductal macrophages exhibit periodicity and considerably increased density in lambs approaching puberty. Stromal macrophages are more abundant centrally than peripherally. Intraepithelial T lymphocytes are more numerous in older lambs. Stromal hotspots of Ki67 expression colocalize with immune cell aggregates that exhibit distinct organisation consistent with tertiary lymphoid structures. The lamb mammary gland thus exhibits a dynamic mucosal and stromal immune microenvironment and constitutes a valuable model system that provides new insights into postnatal breast development.

The epigenetic role of breastfeeding in mammary differentiation

Maternal milk consumption can cause changes in the mammary epithelium of the offspring that result in the expression of molecules involved in the induction of differentiation, reducing the risk of developing mammary cancer later in life. We previously showed that animals that maintained a higher intake of maternal milk had a lower incidence of mammary cancer. In the present study, we evaluated one of the possible mechanisms by which the consumption of maternal milk could modify the susceptibility to mammary carcinogenesis. We used Sprague Dawley rats reared in litters of 3 (L3), 8 (L8), or 12 (L12) pups per mother in order to generate a differential consumption of milk. Whole mounts of mammary glands were performed to analyze the changes in morphology. Using real-time polymerase chain reaction (PCR), we analyzed the expression of mammary Pinc, Tbx3, Stat6, and Gata3 genes. We use the real-time methylation-specific polymerase chain reaction method to assess the methylation status of Stat6 and Gata3 CpG sites. Our findings show an increase in the size of the epithelial tree and a smaller number of ducts called terminal end buds in L3 vs. L12. We observed an increased expression of mRNA of Stat6, Gata3, Tbx3, and a lower expression of Pinc in L3 with respect to L12. Stat6 and Gata3 are more methylated in the CpG islands of the promoter analyzed in L12 vs. L3. In conclusion, the increased consumption of maternal milk during the postnatal stage generates epigenetic and morphological changes associated with the differentiation of the mammary gland.

The evolution of perennially enlarged breasts in women: a critical review and a novel hypothesis

The possession of permanent, adipose breasts in women is a uniquely human trait that develops during puberty, well in advance of the first pregnancy. The adaptive role and developmental pattern of this breast morphology, unusual among primates, remains an unresolved conundrum. The evolutionary origins of this trait have been the focus of many hypotheses, which variously suggest that breasts are a product of sexual selection or of natural selection due to their putative role in assisting in nursing or as a thermoregulatory organ. Alternative hypotheses assume that permanent breasts are a by-product of other evolutionary changes. We review and evaluate these hypotheses in the light of recent literature on breast morphology, physiology, phylogeny, ontogeny, sex differences, and genetics in order to highlight their strengths and flaws and to propose a coherent perspective and a new hypothesis on the evolutionary origins of perennially enlarged breasts in women. We propose that breasts appeared as early as Homo ergaster, originally as a by-product of other coincident evolutionary processes of adaptive significance. These included an increase in subcutaneous fat tissue (SFT) in response to the demands of thermoregulatory and energy storage, and of the ontogenetic development of the evolving brain. An increase in SFT triggered an increase in oestradiol levels (E2). An increase in meat in the diet of early Homo allowed for further hormonal changes, such as greater dehydroepiandrosterone (DHEA/S) synthesis, which were crucial for brain evolution. DHEA/S is also easily converted to E2 in E2-sensitive body parts, such as breasts and gluteofemoral regions, causing fat accumulation in these regions, enabling the evolution of perennially enlarged breasts. Furthermore, it is also plausible that after enlarged breasts appeared, they were co-opted for other functions, such as attracting mates and indicating biological condition. Finally, we argue that the multifold adaptive benefits of SFT increase and hormonal changes outweighed the possible costs of perennially enlarged breasts, enabling their further development.

Development and Pathology of the Equine Mammary Gland

An understanding of the anatomy, histology, and development of the equine mammary gland underpins study of the pathology of diseases including galactorrhoea, agalactia, mastitis, and mammary tumour development. This review examines the prenatal development of the equine mammary gland and the striking degree to which the tissue undergoes postnatal development associated with the reproductive cycle. The gland is characterised by epithelial structures arranged in terminal duct lobular units, similar to those of the human breast, supported by distinct zones of intra- and interlobular collagenous stroma. Mastitis and mammary carcinomas are two of the most frequently described equine mammary pathologies and have an overlap in associated clinical signs. Mastitis is most frequently associated with bacterial aetiologies, particularly Streptococcus spp., and knowledge of the process of post-lactational regression can be applied to preventative husbandry strategies. Equine mammary tumours are rare and carry a poor prognosis in many cases. Recent studies have used mammosphere assays to reveal novel insights into the identification and potential behaviour of mammary stem/progenitor cell populations. These suggest that mammospheres derived from equine cells have different growth dynamics compared to those from other species. In parallel with studying the equine mammary gland in order to advance knowledge of equine mammary disease at the interface of basic and clinical science, there is a need to better understand equine lactational biology. This is driven in part by the recognition of the potential value of horse and donkey milk for human consumption, particularly donkey milk in children with 'Cow Milk Protein Allergy'.

The Cellular Organization of the Mammary Gland: Insights From Microscopy

Despite rapid advances in our knowledge of the cellular heterogeneity and molecular regulation of the mammary gland, how these relate to 3D cellular organization remains unclear. In addition to hormonal regulation, mammary gland development and function is directed by para- and juxtacrine signaling among diverse cell-types, particularly the immune and mesenchymal populations. Precise mapping of the cellular landscape of the breast will help to decipher this complex coordination. Imaging of thin tissue sections has provided foundational information about cell positioning in the mammary gland and now technological advances in tissue clearing and subcellular-resolution 3D imaging are painting a more complete picture. In particular, confocal, light-sheet and multiphoton microscopy applied to intact tissue can fully capture cell morphology, position and interactions, and have the power to identify spatially rare events. This review will summarize our current understanding of mammary gland cellular organization as revealed by microscopy. We focus on the mouse mammary gland and cover a broad range of immune and stromal cell types at major developmental stages and give insights into important tissue niches and cellular interactions.

Nonhuman primate model in mammary gland biology and neoplasia research

Research on breast cancer pathogenesis, prevention and drug development remains an important field as this disease is still one of the leading causes of cancer death worldwide. Nonhuman primates, particularly macaque species, may serve as a highly translational animal model in breast cancer studies due to their similarity with humans in genetics, anatomy, reproductive and endocrine physiology including mammary gland development profile. The use of nonhuman primates in biomedical research, however, requires high ethical standards and an increasing expectation to improve strategies to replace, reduce and refine their use. Here, we discuss some key features of nonhuman primate mammary gland biology relevant to their strengths and limitations as models in studies of breast development and cancer risk.

Progesterone Receptor Signaling in the Breast Tumor Microenvironment

The tumor microenvironment (TME) is a complex infrastructure composed of stromal, epithelial, and immune cells embedded in a vasculature ECM. The microenvironment surrounding mammary epithelium plays a critical role during the development and differentiation of the mammary gland, enabling the coordination of the complex multihormones and growth factor signaling processes. Progesterone/progesterone receptor paracrine signaling interactions in the microenvironment play vital roles in stem/progenitor cell function during normal breast development. In breast cancer, the female sex hormones, estrogen and progesterone, and growth factor signals are altered in the TME. Progesterone signaling modulates not only breast tumors but also the breast TME, leading to the activation of a series of cross-communications that are implicated in the genesis of breast cancers. This chapter reviews the evidence that progesterone and PR signaling modulates not only breast epitheliums but also the breast TME. Furthermore, crosstalk between estrogen and progesterone signaling affecting different cell types within the TME is discussed. A better understanding of how PR and progesterone affect the TME of breast cancer may lead to novel drugs or a therapeutic approach for the treatment of breast cancer shortly.

Feed intake-dependent and -independent effects of heat stress on lactation and mammary gland development

With a growing population, a reliable food supply is increasingly important. Heat stress reduces livestock meat and milk production. Genetic selection of high-producing animals increases endogenous heat production, while climate change increases exogenous heat exposure. Both sources of heat exacerbate the risk of heat-induced depression of production. Rodents are valuable models to understand mechanisms conserved across species. Heat exposure suppresses feed intake across homeothermic species including rodents and production animal species. We assessed the response to early-mid lactation or late-gestation heat exposure on milk production and mammary gland development/function, respectively. Using pair-fed controls we experimentally isolated the feed intake-dependent and -independent effects of heat stress on mammary function and mass. Heat exposure (35°C, relative humidity 50%) decreased daily feed intake. When heat exposure occurred during lactation, hypophagia accounted for approximately 50% of the heat stress-induced hypogalactia. Heat exposure during middle to late gestation suppressed feed intake, which was fully responsible for the lowered mammary gland weight of dams at parturition. However, the impaired mammary gland function in heat-exposed dams measured by metabolic rate and lactogenesis could not be explained by depressed feed consumption. In conclusion, mice recapitulate the depressed milk production and mammary gland development observed in dairy species while providing insight regarding the role of feed intake. This opens the potential to apply genetic, experimental, and pharmacological models unique to mice to identify the mechanism by which heat is limiting animal production.

A Rare Presentation of an Invasive Ductal Carcinoma of Ectopic Axillary Breast Tissue

Ectopic breast tissue (EBT) is a rare entity and can present anywhere along the milk line, including the axilla, inframammary region, thighs, perineum, groin, and vulva. However, the axilla is the most common area of presentation. EBT can present as supernumerary breasts or aberrant breast tissue. Malignancy arising in EBT is rare, but the most common morphological variant is invasive ductal carcinoma. We report a case of a 43-year-old woman, a smoker with a family history of breast cancer, who presented to our clinic with a small mass in the right axillary area. After monitoring it for one year, the mass increased in size, so she returned to the clinic and decided with her care team to excise the mass. Histopathology showed invasive mammary adenocarcinoma arising in EBT and was diagnosed as right accessory stage I breast cancer. This case illustrates the imperative that any mass in the axillary region should be thoroughly assessed to rule out carcinoma in the accessory axillary tissue for timely management. 

Breast Milk, a Source of Beneficial Microbes and Associated Benefits for Infant Health

Human breast milk is considered the optimum feeding regime for newborn infants due to its ability to provide complete nutrition and many bioactive health factors. Breast feeding is associated with improved infant health and immune development, less incidences of gastrointestinal disease and lower mortality rates than formula fed infants. As well as providing fundamental nutrients to the growing infant, breast milk is a source of commensal bacteria which further enhance infant health by preventing pathogen adhesion and promoting gut colonisation of beneficial microbes. While breast milk was initially considered a sterile fluid and microbes isolated were considered contaminants, it is now widely accepted that breast milk is home to its own unique microbiome. The origins of bacteria in breast milk have been subject to much debate, however, the possibility of an entero-mammary pathway allowing for transfer of microbes from maternal gut to the mammary gland is one potential pathway. Human milk derived strains can be regarded as potential probiotics; therefore, many studies have focused on isolating strains from milk for subsequent use in infant health and nutrition markets. This review aims to discuss mammary gland development in preparation for lactation as well as explore the microbial composition and origins of the human milk microbiota with a focus on probiotic development.

Progesterone and Breast Cancer

Synthetic progestogens (progestins) have been linked to increased breast cancer risk; however, the role of endogenous progesterone in breast physiology and carcinogenesis is less clearly defined. Mechanistic studies using cell culture, tissue culture, and preclinical models implicate progesterone in breast carcinogenesis. In contrast, limited epidemiologic data generally do not show an association of circulating progesterone levels with risk, and it is unclear whether this reflects methodologic limitations or a truly null relationship. Challenges related to defining the role of progesterone in breast physiology and neoplasia include: complex interactions with estrogens and other hormones (eg, androgens, prolactin, etc.), accounting for timing of blood collections for hormone measurements among cycling women, and limitations of assays to measure progesterone metabolites in blood and progesterone receptor isotypes (PRs) in tissues. Separating the individual effects of estrogens and progesterone is further complicated by the partial dependence of PR transcription on estrogen receptor (ER)α-mediated transcriptional events; indeed, interpreting the integrated interaction of the hormones may be more essential than isolating independent effects. Further, many of the actions of both estrogens and progesterone, particularly in "normal" breast tissues, are driven by paracrine mechanisms in which ligand binding to receptor-positive cells evokes secretion of factors that influence cell division of neighboring receptor-negative cells. Accordingly, blood and tissue levels may differ, and the latter are challenging to measure. Given conflicting data related to the potential role of progesterone in breast cancer etiology and interest in blocking progesterone action to prevent or treat breast cancer, we provide a review of the evidence that links progesterone to breast cancer risk and suggest future directions for filling current gaps in our knowledge.

Endocrine-Disrupting Chemicals and Their Effects during Female Puberty: A Review of Current Evidence

Puberty is the process of physical changes between childhood and adulthood during which adolescents reach sexual maturity and become capable of reproduction. It is considered one of the main temporal windows of susceptibility for the influence of the endocrine-disrupting chemicals (EDCs). EDCs may act as single chemical agents or as chemical mixtures; they can be pubertal influencers, accelerating and anticipating the processing of maturation of secondary sexual characteristics. Moreover, recent studies have started to point out how exposure to EDCs during puberty may predispose to breast cancer later in life. In fact, the estrogen-mimicking endocrine disruptors (EEDs) may influence breast tissue development during puberty in two main ways: the first is the action on the proliferation of the breast stromal cells, the second concerns epigenetic mechanisms. The aim of this mini-review was to better highlight what is new and what is not completely known regarding the role of EDCs during puberty.

Does Direct and Indirect Exposure to Ionising Radiation Influence the Metastatic Potential of Breast Cancer Cells

Ionising radiation (IR) is commonly used for cancer therapy; however, its potential influence on the metastatic ability of surviving cancer cells exposed directly or indirectly to IR remains controversial. Metastasis is a multistep process by which the cancer cells dissociate from the initial site, invade, travel through the blood stream or lymphatic system, and colonise distant sites. This complex process has been reported to require cancer cells to undergo epithelial-mesenchymal transition (EMT) by which the cancer cells convert from an adhesive, epithelial to motile, mesenchymal form and is also associated with changes in glycosylation of cell surface proteins, which may be functionally involved in metastasis. In this paper, we give an overview of metastatic mechanisms and of the fundamentals of cancer-associated glycosylation changes. While not attempting a comprehensive review of this wide and fast moving field, we highlight some of the accumulating evidence from in vitro and in vivo models for increased metastatic potential in cancer cells that survive IR, focusing on angiogenesis, cancer cell motility, invasion, and EMT and glycosylation. We also explore the indirect effects in cells exposed to exosomes released from irradiated cells. The results of such studies need to be interpreted with caution and there remains limited evidence that radiotherapy enhances the metastatic capacity of cancers in a clinical setting and undoubtedly has a very positive clinical benefit. However, there is potential that this therapeutic benefit may ultimately be enhanced through a better understanding of the direct and indirect effects of IR on cancer cell behaviour.

Basal-like Breast Cancers: From Pathology to Biology and Back Again

Human breast cancers referred to as "basal-like" are of interest because they lack effective therapies and their biology is poorly understood. The term basal-like derives from studies demonstrating tumor gene expression profiles that include some transcripts characteristic of the basal cells of the normal adult human mammary gland and others associated with a subset of normal luminal cells. Elucidating the mechanisms responsible for the profiles of basal-like tumors is an active area of investigation. More refined molecular analysis of patients' samples and genetic strategies to produce breast cancers de novo from defined populations of normal mouse mammary cells have served as complementary approaches to identify relevant pathway alterations. However, both also have limitations. Here, we review some of the underlying reasons, including the unifying concept that some normal luminal cells have both luminal and basal features, as well as some emerging new avenues of investigation.

Stem Cells and the Differentiation Hierarchy in Mammary Gland Development

The mammary gland is a highly dynamic organ that undergoes profound changes within its epithelium during puberty and the reproductive cycle. These changes are fueled by dedicated stem and progenitor cells. Both short- and long-lived lineage-restricted progenitors have been identified in adult tissue as well as a small pool of multipotent mammary stem cells (MaSCs), reflecting intrinsic complexity within the epithelial hierarchy. While unipotent progenitor cells predominantly execute day-to-day homeostasis and postnatal morphogenesis during puberty and pregnancy, multipotent MaSCs have been implicated in coordinating alveologenesis and long-term ductal maintenance. Nonetheless, the multipotency of stem cells in the adult remains controversial. The advent of large-scale single-cell molecular profiling has revealed striking changes in the gene expression landscape through ontogeny and the presence of transient intermediate populations. An increasing number of lineage cell-fate determination factors and potential niche regulators have now been mapped along the hierarchy, with many implicated in breast carcinogenesis. The emerging diversity among stem and progenitor populations of the mammary epithelium is likely to underpin the heterogeneity that characterizes breast cancer.

Connexin43 as a Tumor Suppressor: Proposed Connexin43 mRNA-circularRNAs-microRNAs Axis Towards Prevention and Early Detection in Breast Cancer

Breast cancer (BC) is a global public health burden, constituting the highest cancer incidence in women worldwide. Connexin43 (Cx43) is a member of a family of transmembrane proteins responsible in part for intercellular communication between adjacent breast epithelial cells, via gap junctions. Cx43 plays key role in mammary gland development and differentiation and its spatio-temporal perturbation contributes to tumorigenesis. Thus, Cx43 acts as a breast tumor-suppressor. Signaling pathways and phenotypes downstream of Cx43 mRNA loss/mis-localization in breast cells have been well-studied. However, axes parallel to Cx43 loss are less understood. microRNAs (miRNAs) are small endogenous non-coding RNAs that repress translation and circularRNAs (circRNAs) are a class of endogenous RNAs that originate from RNA splicing and act as miRNA "sponges". CircRNAs and miRNAs are dysregulated in cancers and are highly abundant and stable in the circulation. Thus, they present as attractive liquid biopsy cancer biomarkers. Here, an axis for Cx43 mRNA-circRNAs-miRNAs interactions along BC initiation (denoted by loss of breast epithelial polarity and development of hyperplastic phenotypes) is proposed to potentially serve as a signature biomarker toward BC early-onset detection and prevention.

Invasive carcinoma in accessory axillary breast tissue: A case report

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Accessory breast cancer is a rare entity with incidence of around 0.2%–0.6%.

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Routine mammograms can miss accessory breast tissue due to its location.

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General lack of awareness of accessory breast cancer among clinicians has potentially dangerous implications.

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Accessory breast cancer does not require mastectomy unless involved by cancer.

Introduction

Accessory or ectopic breast tissue is an aberration of normal breast development. It is known to be a rare entity present anywhere along the embryologic mammary streak or milk line but more common in axilla.

Presentation of case

We report a case of 36 year old female with accessory breast carcinoma who presented with a progressive lump in her left axilla for 1 year. On examination a 2 cm solitary mass was palpable in axilla. Ultrasound confirmed a 19 mm mass with no other lesion in breast and axilla. Core biopsy showed invasive ductal carcinoma. She was discussed in multidisciplinary board meeting and was offered upfront surgery with excision of accessory breast tissue and sentinel lymph node biopsy. Axillary lymph node dissection was omitted following ACOSG Z0011 criteria. She was offered adjuvant chemotherapy and radiation post operatively along with endocrine treatment as she was hormone receptor positive.

Discussion

Accessory breast development is hormone dependent just like normal breast. Breast cancer in accessory breast tissue is very rare. The incidence is around 6%. Most common pathology is invasive ductal carcinoma (50–75%). The most common location is axilla (60–70%) although it can present in other less common locations like infra-mammary region (5–10%) and rarely in thighs, perineum, groin, and vulva.

Conclusion

Since accessory axillary breast tissue is out of the image of screening breast examination, it is necessary for the oncologists to be aware of this entity and associated pathologies. Their preventive excision in high risk women can also be considered.

Gap Junctions and Wnt Signaling in the Mammary Gland: a Cross-Talk?

Connexins (Cxs), the building blocks of gap junctions (GJs), exhibit spatiotemporal patterns of expression and regulate the development and differentiation of the mammary gland, acting via channel-dependent and channel-independent mechanisms. Impaired Cx expression and localization are reported in breast cancer, suggesting a tumor suppressive role for Cxs. The signaling events that mediate the role of GJs in the development and tumorigenesis of the mammary gland remain poorly identified. The Wnt pathways, encompassing the canonical or the Wnt/β-catenin pathway and the noncanonical β-catenin-independent pathway, also play important roles in those processes. Indeed, aberrant Wnt signaling is associated with breast cancer. Despite the coincident roles of Cxs and Wnt pathways, the cross-talk in the breast tissue is poorly defined, although this is reported in a number of other tissues. Our previous studies revealed a channel-independent role for Cx43 in inducing differentiation or suppressing tumorigenesis of mammary epithelial cells by acting as a negative regulator of the Wnt/β-catenin pathway. Here, we provide a brief overview of mammary gland development, with emphasis on the role of Cxs in development and tumorigenesis of this tissue. We also discuss the role of Wnt signaling in similar contexts, and review the literature illustrating interplay between Cxs and Wnt pathways.

The tributyltin leads to obesogenic mammary gland abnormalities in adult female rats

Tributyltin chloride (TBT) is an obesogen associated with several complications. However, few investigations have evaluated TBT effects on adult mammary glands (MG). In this investigation, we assessed whether TBT's obesogenic effects resulted in abnormal MG fat pad expansion and other irregularities. TBT was administered to female rats (100 ng/kg/day for 15 days via gavage), and their MG morphophysiological development was assessed. We further assessed the MG fat pad for PPARγ, ERα, and aromatase protein expression, as well as inflammation, oxidative stress (OS), apoptosis and fibrosis. Irregular MG morphological development such as lower TEB number, alveolar (AB), lobule and differentiation (DF) score were observed in TBT rats. TBT rats had abnormal MG fat accumulation as evidenced by increased numbers of hypertrophic adipocytes, triglyceride (TG) levels and PPARγ expression. A strong negative correlation between the MG obesogenic makers and TEB number, AB and DF score were observed in TBT rats. MG inflammation was observed in TBT rats. A positive correlation between the MG obesogenic markers and inflammation were observed. High ERα and aromatase expression were observed in MG of TBT rats. MG OS, apoptosis and fibrosis were present in the TBT rats. Additionally, a positive correlation between the MG obesogenic markers and OS were observed in TBT rats. Thus, these data suggest that obesogenic TBT effects led to MG irregularities in the adult female rats.

Reduced Breast Tumor Growth after Immunization with a Tumor-Restricted MUC1 Glycopeptide Conjugated to Tetanus Toxoid

Preventive vaccination against tumor-associated endogenous antigens is considered to be an attractive strategy for the induction of a curative immune response concomitant with a long-lasting immunologic memory. The mucin MUC1 is a promising tumor antigen, as its tumor-associated form differs from the glycoprotein form expressed on healthy cells. Due to aberrant glycosylation in tumor cells, the specific peptide epitopes in its backbone are accessible and can be bound by antibodies induced by vaccination. Breast cancer patients develop per se only low levels of T cells and antibodies recognizing tumor-associated MUC1, and clinical trials with tumor-associated MUC1 yielded unsatisfactory therapeutic effects, indicating an urgent need to improve humoral immunity against this tumor entity. Herein, we demonstrate that preventive vaccination against tumor-associated human MUC1 results in a specific humoral immune response, a slowdown of tumor progression and an increase in survival of breast tumor-bearing mice. For preventive vaccination, we used a synthetic vaccine containing a tumor-associated glycopeptide structure of human MUC1 coupled to Tetanus Toxoid. The glycopeptide consists of a 22mer huMUC1 peptide with two immune dominant regions (PDTR and GSTA), glycosylated with the sialylated carbohydrate ST_N on serine-17. PyMT (polyomavirus middle T-antigen) and human MUC1 double-transgenic mice expressing human tumor-associated MUC1 on breast tumor tissue served as a preclinical breast cancer model.

Incidence of Breast Cancer in the Life Span Study of Atomic Bomb Survivors: 1958-2009

The importance of reproductive history in breast tissue development and etiology of sporadic breast cancer in females is well established. However, there is limited evidence of factors, other than age, that modify risk of radiation-related breast cancer. In this study, we evaluated breast cancer incidence in the Life Span Study cohort of atomic bomb survivors, adding 11 years of follow-up and incorporating reproductive history data. We used Poisson regression models to describe radiation risks and modifying effects of age and reproductive factors. Among 62,534 females, we identified 1,470 breast cancers between 1958 and 2009. Of 397 new cases diagnosed since 1998, 75% were exposed before age 20. We found a strong linear dose response with excess relative risk (ERR) of 1.12 per Gy [95% confidence interval (CI): 0.73 to 1.59] for females at age 70 after exposure at age 30. The ERR decreased with increasing attained age ( P = 0.007) while excess absolute rate (EAR) increased with attained age up to age 70 ( P < 0.001). Age at menarche was a strong modifier of the radiation effect: for a given dose, both the ERR and EAR decreased with increasing age at menarche ( P = 0.007 and P < 0.001). Also, independently, age-at-exposure effects on ERR and EAR differed before and after menarche ( P = 0.043 and P = 0.015, respectively, relative to log-linear trends), with highest risks for exposures around menarche. Despite the small number of male breast cancers (n = 10), the data continue to suggest a dose response (ERR per Gy = 5.7; 95% CI: 0.3 to 30.8; P = 0.018). Persistently increased risk of female breast cancer after radiation exposure and its modification pattern suggests heightened breast sensitivity during puberty.