Journal of Mammary Gland Biology and Neoplasia最新文献

Hormone receptor-positive (HR⁺) breast cancer (BC) is the most common type of breast cancer among women worldwide, accounting for 70-80% of all invasive cases. Patients with HR⁺ BC are commonly treated with endocrine therapy, but intrinsic or acquired resistance is a frequent problem, making HR⁺ BC a focal point of intense research. Despite this, the malignancy still lacks adequate in vitro and in vivo models for the study of its initiation and progression as well as response and resistance to endocrine therapy. No mouse models that fully mimic the human disease are available, however rat mammary tumor models pose a promising alternative to overcome this limitation. Compared to mice, rats are more similar to humans in terms of mammary gland architecture, ductal origin of neoplastic lesions and hormone dependency status. Moreover, rats can develop spontaneous or induced mammary tumors that resemble human HR⁺ BC. To date, six different types of rat models of HR⁺ BC have been established. These include the spontaneous, carcinogen-induced, transplantation, hormone-induced, radiation-induced and genetically engineered rat mammary tumor models. Each model has distinct advantages, disadvantages and utility for studying HR⁺ BC. This review provides a comprehensive overview of all published models to date.

The transcription factor STAT3 is activated by multiple cytokines and other extrinsic factors. It plays a key role in immune and inflammatory responses and, when dysregulated, in tumourigenesis. STAT3 is also an indispensable mediator of the cell death process that occurs during post-lactational regression of the mammary gland, one of the most dramatic examples of physiological cell death in adult mammals. During this involution of the gland, STAT3 powerfully enhances the lysosomal system to efficiently remove superfluous milk-producing mammary epithelial cells via a lysosomal-mediated programmed cell death pathway. The lysosome is a membrane-enclosed  cytoplasmic organelle that digests and recycles cellular waste, with an important role as a signalling centre that monitors cellular metabolism. Here, we describe key strategies for investigating the role of STAT3 in regulating lysosomal function using a mammary epithelial cell culture model system. These include protocols for lysosome enrichment and enzyme activity assays, in addition to microscopic analyses of the vesicular compartment in cell lines. Collectively, these approaches provide the tools to investigate multiple aspects of lysosome biogenesis and function, and to define both direct and indirect roles for STAT3.

Signal transducers and activators of transcription (STAT) proteins regulate mammary development. Here we investigate the expression of phosphorylated STAT3 (pSTAT3) in the mouse and cow around the day of birth. We present localised colocation analysis, applicable to other mammary studies requiring identification of spatially congregated events. We demonstrate that pSTAT3-positive events are multifocally clustered in a non-random and statistically significant fashion. Arginase-1 expressing cells, consistent with macrophages, exhibit distinct clustering within the periparturient mammary gland. These findings represent a new facet of mammary STAT3 biology, and point to the presence of mammary sub-microenvironments.

Improved screening and treatment have decreased breast cancer mortality, although incidence continues to rise. Women at increased risk of breast cancer can be offered risk reducing treatments, such as tamoxifen, but this has not been shown to reduce breast cancer mortality. New, more efficacious, risk-reducing agents are needed. The identification of novel candidates for prevention is hampered by a lack of good preclinical models. Current patient derived in vitro and in vivo models cannot fully recapitulate the complexities of the human tissue, lacking human extracellular matrix, stroma, and immune cells, all of which are known to influence therapy response. Here we describe a normal breast explant model utilising a tuneable hydrogel which maintains epithelial proliferation, hormone receptor expression, and residency of T cells and macrophages over 7 days. Unlike other organotypic tissue cultures which are often limited by hyper-proliferation, loss of hormone signalling, and short treatment windows (< 48h), our model shows that tissue remains viable over 7 days with none of these early changes. This offers a powerful and unique opportunity to model the normal breast and study changes in response to various risk factors, such as breast density and hormone exposure. Further validation of the model, using samples from patients undergoing preventive therapies, will hopefully confirm this to be a valuable tool, allowing us to test novel agents for breast cancer risk reduction preclinically.

How cancer patterns in humans compare to those of other species remains largely unknown and there is an even bigger knowledge gap for rare cancers like male breast cancer. One Health is a convergence of human and animal healthcare that encourages cross-pollination of medical research uniting human and veterinary medicine. Recognising that breast cancer occurs spontaneously in other male species (e.g. primates, canines, felines), and knowing that no laboratory models exist for male breast cancer, which limits our ability to perform functional studies, we explored the feasibility of applying One Health to breast cancer in men by conducting a narrative review of the topic. Spontaneous development of breast cancer was reported in captive male primates and in companion canines and felines. Some parallels in tumour biology of human male breast cancer with canines and primates were found. The age distribution, pattern of biomarker expression and metastasis were similar, with mammary tumours typically detected after two-thirds of average lifespan. However, instances of triple negative and inflammatory breast cancer, which are rarely observed in human male breast cancer, were found in canines and histological classification was inconsistent between species. These disparities need redressing to enable full exploration of the One Health paradigm in rare cancers.

This article offers a comprehensive perspective on the transformative role of organoid technology on mammary gland biology research across a diverse array of mammalian species.The mammary gland's unique development and regenerative capabilities render this organ an ideal model for studying developmental evolution, stem cell behavior, and regenerative processes. The discussion extends to the use of cross-species mammary organoids to address key biological inquiries in evolution, tissue regeneration, cancer research, and lactation, highlighting the limitations of traditional mouse models and the benefits of incorporating a more diverse range of animal models.Advances in organoid biology have been critical in overcoming ethical and practical constraints of in-vivo studies, especially in human research. The generation of human and mouse mammary organoids that faithfully recapitulate in-vivo tissues marks a significant stride in this field. Parallel capabilities are now emerging for other mammals, as well.Utilizing mammary organoids from various species has the potential to make invaluable contributions to our understanding of mammary gland biology, with implications for regenerative medicine, cancer research, and lactation studies, thereby contributing to advancements in human health, agriculture, and nutrition science.

The three-dimensional (3D) structure of the ductal epithelium and the surrounding extracellular matrix (ECM) are integral aspects of the breast tissue, and they have important roles during mammary gland development, function and malignancy. However, the architecture of the branched mammary epithelial network is poorly recapitulated in the current in vitro models. 3D bioprinting is an emerging approach to improve tissue-mimicry in cell culture. Here, we developed and optimized a protocol for 3D bioprinting of normal and cancerous mammary epithelial cells into a branched Y-shape to study the role of cell positioning in the regulation of cell proliferation and invasion. Non-cancerous cells formed continuous 3D cell networks with several organotypic features, whereas the ductal carcinoma in situ (DCIS) -like cancer cells exhibited aberrant basal polarization and defective formation of the basement membrane (BM). Quantitative analysis over time demonstrated that both normal and cancerous cells proliferate more at the branch tips compared to the trunk region of the 3D-bioprinted cultures, and particularly at the tip further away from the branch point. The location-specific rate of proliferation was independent of TGFβ signaling but invasion of the DCIS-like breast cancer cells was reduced upon the inhibition of TGFβ. Thus, our data demonstrate that the 3D-bioprinted cells can sense their position in the branched network of cells and proliferate at the tips, thus recapitulating this feature of mammary epithelial branching morphogenesis. In all, our results demonstrate the capacity of the developed 3D bioprinting method for quantitative analysis of the relationships between tissue structure and cell behavior in breast morphogenesis and cancer.

Tumor mass comprises not only cancer cells but also heterogeneous populations of immune and stromal cells, along with the components of the extracellular matrix, collectively called the tumor microenvironment (TME). This diverse population of cells can communicate with each other, which can positively or negatively affect tumor growth and progression to malignancy. The most common type of immune cells in the TME are macrophages. Macrophages continuously differentiate into a broad landscape of tumor-associated macrophages (TAMs) in response to numerous signals from the TME, which makes studies on TAMs quite challenging. Therefore, implementing reliable protocols is a milestone for drawing consistent conclusions about the interactions between cancer cells and TAMs. Here, we provide the details for the polarization of a human leukemia monocytic cell line, THP-1, into M0, M1 and M2 macrophages. We also present a step-by-step protocol for a transwell co-culture using a human breast cancer cell line, HCC1806, and THP-1-derived macrophages. Finally, we describe the colony formation and migration assays performed on the breast cancer cells after the co-culture with macrophages to measure the influence of macrophages on the oncogenic features of cancer cells. In summary, our co-culture-based protocols can be a valuable resource for investigating the interactions between macrophages and cancer cells.

In preclinical studies, accurate monitoring of tumor dynamics is crucial for understanding cancer biology and evaluating therapeutic interventions. Traditional methods like caliper measurements and bioluminescence imaging (BLI) have limitations, prompting the need for improved imaging techniques. This study introduces a fast-scan high-frequency ultrasound (HFUS) protocol for the longitudinal assessment of syngeneic breast tumor grafts in mice, comparing its performance with caliper, BLI measurements and with histological analysis. The E0771 mammary gland tumor cell line, engineered to express luciferase, was orthotopically grafted into immunocompetent C57BL/6 mice. Tumor growth was monitored longitudinally at multiple timepoints using caliper measurement, HFUS, and BLI, with the latter two modalities assessed against histopathological standards post-euthanasia. The HFUS protocol was designed for rapid, anesthesia-free scanning, focusing on volume estimation, echogenicity, and necrosis visualization. All mice developed tumors, only 20.6% were palpable at day 4. HFUS detected tumors as small as 2.2 mm in average diameter from day 4 post-implantation, with an average scanning duration of 47 s per mouse. It provided a more accurate volume assessment than caliper, with a lower average bias relative to reference tumor volume. HFUS also revealed tumor necrosis, correlating strongly with BLI in terms of tumor volume and cellularity. Notable discrepancies between HFUS and BLI growth rates were attributed to immune cell infiltration. The fast HFUS protocol enables precise and efficient tumor assessment in preclinical studies, offering significant advantages over traditional methods in terms of speed, accuracy, and animal welfare, aligning with the 3R principle in animal research.