A Hormone-responsive 3D Culture Model of the Human Mammary Gland Epithelium

The process of mammary epithelial morphogenesis is influenced by hormones. The study of hormone action on the breast epithelium using 2D cultures is ...

Tufts University School of Medicine

Iatrogenic gestational exposure to diethylstilbestrol (DES) induced alterations of the genital tract and predisposed individuals to develop clear cell carcinoma of the vagina as well as breast cancer later in life. Gestational exposure of rodents to a related compound, the xenoestrogen bisphenol-A (BPA) increases the propensity to develop mammary cancer during adulthood, long after cessation of exposure. Exposure to BPA during gestation induces morphological alterations in both the stroma and the epithelium of the fetal mammary gland at 18 days of age. We postulate that the primary target of BPA is the fetal stroma, the only mammary tissue expressing estrogen receptors during fetal life. BPA would then alter the reciprocal stroma-epithelial interactions that mediate mammogenesis. In addition to this direct effect on the mammary gland, BPA is postulated to affect the hypothalamus and thus in turn affect the regulation of mammotropic hormones at puberty and beyond.

Estrogens in the wrong place at the wrong time: Fetal BPA exposure and mammary cancer.

According to contemporary epidemiological and experimental evidence, we propose a novel classification of cancers based on pathogenesis instead of classifications based on histological appearance of cancer. This new scheme first defines cancers as either 1. inborn errors of development or 2. sporadic ones, and then sub-defines the former into 1A. inborn inherited errors of development, being those due to mutations contributed by one or both parents' gametes to the developing conceptus, and 1B. inborn induced errors of development when the malformations and/or cancers are due to environmental carcinogenic exposure during pregnancy. It is anticipated that the origin of an increasing number of so-called sporadic cancers will turn out to be linked to the inborn induced errors of development group.

A novel pathogenic classification of cancers.

Defining fiber orientation at each voxel within a 3D biomedical image stack is potentially useful for a variety of applications, including cancer, wound healing and tissue regeneration. Current methods are typically computationally intensive or inaccurate. Herein, we present a 3D weighted orientation vector summation algorithm, which is a generalization of a previously reported 2D vector summation technique aimed at quantifying collagen fiber orientations simultaneously at each voxel of an image stack. As a result, voxel-wise fiber orientation information with 4° to 5° accuracy can be determined, and the computational time required to analyze a typical stack with the size of 512x512x100 voxels is less than 5 min. Thus, this technique enables the practical extraction of voxel-specific orientation data for characterizing structural anisotropy in 3D specimens. As examples, we use this approach to characterize the fiber organization in an excised mouse mammary gland and a 3D breast tissue model.

Rapid three-dimensional quantification of voxel-wise collagen fiber orientation.

Endocrine disruptors: DDT, endocrine disruption and breast cancer.

Metastases are tumors that develop at a distance from their primary origin and are responsible for the death of 90% of cancer patients. For over a century the notion of seed (migrating cells) and soil (the locus where those cells anchor) provided an accurate account of which were the protagonists in their genesis. Despite aggressive efforts to unravel the dynamics involving migrating cells and the niche in which they anchor, explanations of this process remain ill-defined and controversial. The controversy is generated by the different premises that researchers adopt to integrate the vast amount of data collected at different levels of biological organization. The so-far hegemonic theory of cancer and its metastases has been the somatic mutation theory (SMT) and a number of its variants: They consider that cancers and their metastases represent a cell-based, genetic and molecular disease. This interpretation has been challenged by the tissue organization field theory (TOFT), which considers instead that cancer is a tissue-based disease, akin to development gone awry. In this Commentary, the merits of both theories are compared now in the context of metastases. Based on the epistemological shortcomings of the SMT and the acknowledged failure of therapeutic approaches based on this theory, we conclude that TOFT explains comprehensibly carcinogenesis and the appearance of metastases.

Cancer Metastases: So Close and So Far.

Along with the well-established effects on fertility and fecundity, perinatal exposure to endocrine disrupting chemicals, and notably to xeno-estrogens, is strongly suspected of modulating general metabolism. The metabolism of a perinatally exposed individual may be durably altered leading to a higher susceptibility of developing metabolic disorders such as obesity and diabetes; however, experimental designs involving the long term study of these dynamic changes in the metabolome raise novel challenges. 1H-NMR-based metabolomics was applied to study the effects of bisphenol-A (BPA, 0; 0.25; 2.5, 25 and 250 μg/kg BW/day) in rats exposed perinatally. Serum and liver samples of exposed animals were analyzed on days 21, 50, 90, 140 and 200 in order to explore whether maternal exposure to BPA alters metabolism. Partial Least Squares-Discriminant Analysis (PLS-DA) was independently applied to each time point, demonstrating a significant pair-wise discrimination for liver as well as serum samples at all time-points, and highlighting unequivocal metabolic shifts in rats perinatally exposed to BPA, including those exposed to lower doses. In BPA exposed animals, metabolism of glucose, lactate and fatty acids was modified over time. To further explore dynamic variation, ANOVA-Simultaneous Component Analysis (A-SCA) was used to separate data into blocks corresponding to the different sources of variation (Time, Dose and Time*Dose interaction). A-SCA enabled the demonstration of a dynamic, time/age dependent shift of serum metabolome throughout the rats' lifetimes. Variables responsible for the discrimination between groups clearly indicate that BPA modulates energy metabolism, and suggest alterations of neurotransmitter signaling, the latter finding being compatible with the neurodevelopmental effect of this xenoestrogen. In conclusion, long lasting metabolic effects of BPA could be characterized over 200 days, despite physiological (and thus metabolic) changes connected with sexual maturation and aging.

Dynamic Metabolic Disruption in Rats Perinatally Exposed to Low Doses of Bisphenol-A.

Lacking an operational theory to explain the organization and behaviour of matter in unicellular and multicellular organisms hinders progress in biology. Such a theory should address life cycles from ontogenesis to death. This theory would complement the theory of evolution that addresses phylogenesis, and would posit theoretical extensions to accepted physical principles and default states in order to grasp the living state of matter and define proper biological observables. Thus, we favour adopting the default state implicit in Darwin's theory, namely, cell proliferation with variation plus motility, and a framing principle, namely, life phenomena manifest themselves as non-identical iterations of morphogenetic processes. From this perspective, organisms become a consequence of the inherent variability generated by proliferation, motility and self-organization. Morphogenesis would then be the result of the default state plus physical constraints, like gravity, and those present in living organisms, like muscular tension.

Carlos Sonnenschein

Department of Integrative Physiology and Pathobiology

Tufts University School of Medicine

A Hormone-responsive 3D Culture Model of the Human Mammary Gland Epithelium

Carlos Sonnenschein

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Integrative Physiology and Pathobiology

Tufts University School of Medicine

A Hormone-responsive 3D Culture Model of the Human Mammary Gland Epithelium

Department of Integrative Physiology and Pathobiology