Formation Of Acinar Structures Research Articles

Abstract A40: A novel, biosynthetic 3D hydrogel system for breast cancer mechanobiology studies

Abstract Breast tumor cell-extracellular matrix (ECM) interactions drive malignant transformation, invasion, and metastasis of breast cancer cells and contribute to treatment resistance. The tumor microenvironment, composed of multiple ECM components, activate mechanochemical pathways associated with breast cancer progression and signaling of runt-related transcription factor 2 (Runx2). There is an urgent need to model these interactions in physiologically relevant three-dimensional (3D) models in vitro. We recently demonstrated that we can create 3D PEG hydrogel systems, containing type I collagen, Arg-Gly-Asp (RGD), and hyaluronic acid, whose stiffness can be tuned independent of the number of ECM components incorporated. In this study, we demonstrate that these hydrogels can be utilized to mimic the in vivo tumor microenvironment. We examined the behavior of breast cancer cell lines MDA-MB-231 (invasive) and MCF7 (non-invasive) as well as MCF10A (non-tumorigenic mammary epithelial cells) in our novel, biosynthetic hydrogel systems. We showed that these hydrogels supported growth for each cell line and formation of acinar structures over a 23-day period in vitro. In future studies, we will assess the migratory behaviors of these cell lines in vitro using microfluidic devices as well as Runx2 expression and activity to determine the influence of matrix physiochemical properties on the invasive potential of breast tumor cells. This novel, biosynthetic system represents a reproducible framework where tumor cell behavior may be quantified as a function of a complex system in which combined microenvironmental parameters, including matrix stiffness, ECM composition, and their interactions, are systematically varied. Citation Format: Amy Elissa Blatt, Bita Carrion, Rhima M. Coleman. A novel, biosynthetic 3D hydrogel system for breast cancer mechanobiology studies. [abstract]. In: Proceedings of the AACR Special Conference on Engineering and Physical Sciences in Oncology; 2016 Jun 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2017;77(2 Suppl):Abstract nr A40.

Persistence of γ-H2AX and 53BP1 foci in proliferating and non-proliferating human mammary epithelial cells after exposure to γ-rays or iron ions

Purpose: To investigate γ-H2AX (phosphorylated histone H2AX) and 53BP1 (tumour protein 53 binding protein No. 1) foci formation and removal in proliferating and non-proliferating human mammary epithelial cells (HMEC) after exposure to sparsely and densely ionising radiation under different cell culture conditions.Material and methods: HMEC cells were grown either as monolayers (2D) or in extracellular matrix to allow the formation of acinar structures in vitro (3D). Foci numbers were quantified by image analysis at various time points after exposure.Results: Our results reveal that in non-proliferating cells under 2D and 3D cell culture conditions, iron-ion induced γ-H2AX foci were still present at 72 h after exposure, although 53BP1 foci returned to control levels at 48 h. In contrast in proliferating HMEC, both γ-H2AX and 53BP1 foci decreased to control levels during the 24–48 h time interval after irradiation under 2D conditions. Foci numbers decreased faster after γ-ray irradiation and returned to control levels by 12 h regardless of marker, cell proliferation status, and cell culture condition.Conclusions: The disappearance of radiation-induced γ-H2AX and 53BP1 foci in HMEC has different dynamics that depend on radiation quality and proliferation status. Notably, the general patterns do not depend on the cell culture condition (2D versus 3D). We speculate that the persistent γ-H2AX foci in iron-ion irradiated non-proliferating cells could be due to limited availability of double-strand break (DSB) repair pathways in G0/G1-phase, or that repair of complex DSB requires replication or chromatin remodelling.

Mesotrypsin promotes malignant growth of breast cancer cells through shedding of CD109

Serine proteases have been implicated in many stages of cancer development, facilitating tumor cell growth, invasion, and metastasis, and naturally occurring serine protease inhibitors have shown promise as potential anticancer therapeutics. Optimal design of inhibitors as potential therapeutics requires the identification of the specific serine proteases involved in disease progression and the functional targets responsible for the tumor-promoting properties. Here, we use the HMT-3522 breast cancer progression series grown in 3D organotypic culture conditions to find that serine protease inhibitors cause morphological reversion of the malignant T4-2 cells, assessed by inhibition of proliferation and formation of acinar structures with polarization of basal markers, implicating serine protease activity in their malignant growth behavior. We identify PRSS3/mesotrypsin upregulation in T4-2 cells as compared to their nonmalignant progenitors, and show that knockdown of PRSS3 attenuates, and treatment with recombinant purified mesotrypsin enhances, the malignant growth phenotype. Using proteomic methods, we identify CD109 as the functional proteolytic target of mesotrypsin. Our study identifies a new mediator and effector of breast cancer growth and progression.

Pulmonary lesions produced in A-strain mice by long-term exposure to peroxyacetyl nitrate.

Exposure of male mice, strain A, to 15 ppm of peroxyacetyl nitrate for 130 daily six-hour periods over the course of six months caused weight loss and 18 per cent mortality, the latter primarily by predisposition to severe exudative bronchopneumonia of bacterial origin. Uncomplicated lesions produced by peroxyacetyl nitrate consisted essentially of chronic hyperplastic tracheobronchitis, bronchiolitis, and pneumonitis. There were metaplastic epithelial changes, the nature of which varied with the level of respiratory tract involvement. The most noteworthy feature of the bronchial response was the formation of acinar structures within the walls, occasionally with superimposed atypical epithelial changes. Foci of squamous metaplasia were observed in the trachea and mainstem bronchi in approximately 50 per cent of the mice. Peribronchial epithelial hyperplasia was prominent, but adenomas were not produced during the course of the study. Additional components of the response to peroxyacetyl nitrate were bronc...