Influence of fatty acid diets on gene expression in rat mammary epithelial cells

BACKGROUND

This study examines the impact of dietary fatty acids on regulation of gene expression in mammary epithelial cells before and during puberty.

METHODS

Diets primarily consisted of n-9 monounsaturated fatty acids (olive oil), n-6 polyunsaturated fatty acids (safflower), saturated acids (butter), and the reference AIN-93G diet (soy oil). The dietary regimen mimics the repetitive nature of fatty acid exposure in Western diets. Diet-induced changes in gene expression were examined in laser capture microdissected mammary ductal epithelial cells at day of weaning and end of puberty. PCNA immunohistochemistry analysis compared proliferation rates between diets.

RESULTS

Genes differentially expressed between each test diets and the reference diet were significantly enriched by cell cycle genes. Some of these genes were involved in activation of the cell cycle pathway or the G2/M check point pathway. Although there were some differences in the level of differential expression, all diets showed qualitatively the same pattern of differential expression compared to the reference diet. Cluster analysis identified an expanded set of cell cycle as well as immunity and sterol metabolism related clusters of differentially expressed genes.

CONCLUSION

Fatty acid-enriched diets significantly upregulated proliferation above normal physiological levels during puberty. Higher cellular proliferation during puberty caused by enriched fatty acid diets poses a potential increase risk of mammary cancer in later life. The human homologs of 27 of 62 cell cycle rat genes are included in a human breast cancer cluster of 45 cell cycle genes, further emphasizing the importance of our findings in the rat model.

In vitro Paclitaxel and Radiation Effects on the Cell Types Responsible for Vascular Stenosis: A Preliminary Analysis

Hemodialysis vascular access dysfunction as a result of venous neointimal hyperplasia in dialysis access grafts and fistulae is currently a huge clinical problem. The aim of this study was to assess the effects of paclitaxel and radiation, both singly and in combination on the proliferation of cell types present within the lesion of venous neointimal hyperplasia (vascular smooth muscle cells, fibroblasts and endothelial cells within the neointimal microvessels). Vascular smooth muscle cells, fibroblasts and endothelial cells were plated onto 96-well plates and exposed to different concentrations and doses of paclitaxel and radiation, respectively (both individually and in combination). Growth inhibition was assessed with an MTT assay. Both paclitaxel and radiation resulted in significant growth inhibition of all three cell types. However, even small doses of paclitaxel appeared to attenuate the antiproliferative effect of radiation on these cell types. Further experiments to elucidate the mechanism behind these findings could result in a better understanding of combination antiproliferative therapies.

Epidermal growth factor receptor expression in neurofibromatosis type 1-related tumors and NF1 animal models

We have found that EGF-R expression is associated with the development of the Schwann cell-derived tumors characteristic of neurofibromatosis type 1 (NF1) and in animal models of this disease. This is surprising, because Schwann cells normally lack EGF-R and respond to ligands other than EGF. Nevertheless, immunoblotting, Northern analysis, and immunohistochemistry revealed that each of 3 malignant peripheral nerve sheath tumor (MPNST) cell lines from NF1 patients expressed the EGF-R, as did 7 of 7 other primary MPNSTs, a non-NF1 MPNST cell line, and the S100(+) cells from each of 9 benign neurofibromas. Furthermore, transformed derivatives of Schwann cells from NF1(-/-) mouse embryos also expressed the EGF-R. All of the cells or cell lines expressing EGF-R responded to EGF by activation of downstream signaling pathways. Thus, EGF-R expression may play an important role in NF1 tumorigenesis and Schwann cell transformation. Consistent with this hypothesis, growth of NF1 MPNST lines and the transformed NF1(-/-) mouse embryo Schwann cells was greatly stimulated by EGF in vitro and could be blocked by agents that antagonize EGF-R function.

Graduate education in microscopic anatomy

One of the most striking changes to affect the direction of current biomedical research is the increasing use of transgenic or gene-targeted mice as models of gene function and human disease. The proliferation of transgenic and gene-targeting technology has contributed to a rebirth of histology as an important research tool and is driving the need for broadly trained investigators with expertise at both the molecular and organismal levels. Since the ultimate goal of graduate-student education is the training of the next generation of independent scientists, it is important that graduate training programs provide students with the background required to take advantage of the unique resources provided by these mouse models. Anatomists are well suited to provide such training by incorporating mouse anatomy, physiology, and genetics into traditional coursework in microscopic anatomy.

Amplification and expression of the cyclin D1 gene in anal and esophageal squamous cell carcinomas

Cyclin D1 is a cell-cycle regulator and candidate proto-oncogene implicated in the pathogenesis of numerous tumor types. Amplification of the cyclin D1 gene occurs commonly in esophageal squamous cell carcinomas. However, no studies have examined the role of cyclin D1 in anal carcinogenesis. We examined 20 esophageal squamous cell carcinomas and 24 anal carcinomas for cyclin D1 alterations. Protein expression was evaluated by immunohistochemistry using the cyclin DIGM antibody (Novocastra, Newcastle upon Tyne, UK). Cyclin D1 amplification was examined by fluorescent in situ hybridization (FISH), using a cyclin D1 probe obtained from Toshiya Inaba at St. Jude Children's Research Hospital, Memphis, TN. The FISH sections were analyzed using a Leica (Deerfield, IL) confocal microscope. By immunohistochemistry, 75% of esophageal carcinomas showed evidence of cyclin D1 expression. Cyclin D1 amplification was detected by FISH in 65% of esophageal cancers. There was good correlation between cyclin D1 protein expression and gene amplification, although some tumors showed protein overexpression in the absence of gene amplification. Among the 24 anal carcinomas studied, 8% showed weak cyclin D1 immunoreactivity in rare tumor cells. None of the anal tumors showed cyclin D1 amplification. We conclude that cyclin D1 alterations are common in esophageal carcinomas but do not appear to be important in anal carcinogenesis. Immunohistochemical detection of cyclin D1 protein overexpression is a good predictor of cyclin D1 amplification.

Foreign body reaction to exogenous pulmonary surfactant in an infant with hydrops and cardiomyopathy

We present a hydropic infant who received exogenous surfactant and who had Noonan phenotype with hypertrophic cardiomyopathy. The infant had clinically diagnosed stridor for which bronchoscopy did not identify an origin. He died at 30 days of age. The bronchioles showed numerous eosinophilic plugs with a foreign body giant cell reaction. The plugs were positively immunostained with anti-aposurfactant protein B.

Increased phosphotyrosine in breast cancer tissue is associated with a worse prognosis

We have previously demonstrated that phosphotyrosine can be identified in breast cancer cells using an immunohistochemical stain. We have subsequently used this technique to characterize 106 women with breast cancer (46 with Stage 1 and 60 with Stage 2) who have been followed for at least four years by one oncologist. We analyzed all primary breast cancer tissue using immunohistochemical staining and the amount of phosphotyrosine (PT) was scored on a 0 to 3 range. The PT score of the primary tumor was unrelated to either breast cancer stage or estrogen and progesterone receptor analysis, as high PT scores were noted in both disease stages and all receptor categories. We did find that patients with either no or trace (1+) amounts of PT survived longer than those patients with higher amounts of PT. The patients with low PT had significantly lower chance of relapse (Chi Square = 15.8, p < 0.001) and a lower mortality (Chi Square = 13.1, p = 0.001). We conclude that immunohistochemical methods to determine the PT score may identify patients at higher risk for disease relapse independent of tumor stage or hormonal status.

"Alcoholic hepatitis" in a hepatic adenoma

A unique hepatic adenoma developed in a 26-year-old woman who had used oral contraceptives for 10 years and Tolinase (tolazamide sulfonylurea) for adult-onset diabetes mellitus for five years. Clinically, radiographically, and grossly, the neoplasm showed the usual features of a hepatic adenoma, but microscopically it strongly resembled alcoholic hepatitis with steatonecrosis and Mallory bodies. The surrounding hepatic parenchyma was entirely normal. On transmission electron microscopy these Mallory bodies appeared to be tangles of intermediate filaments. They stained readily with antibodies to cytokeratin but not with antibodies to epidermal keratin or vimentin, just as in "alcoholic" hyalin.

Pulmonary vascular changes associated with prolonged prostaglandin E1 treatment

Prostaglandin E's (PGEs) are used therapeutically in newborn infants to maintain an open ductus arteriosus when there is obstruction to systemic or pulmonary arterial blood flow. These prostaglandins have been shown to have other systemic physiologic effects, such as vasodilation, inhibition of platelet aggregation, and enhancement of chemotactic-factor-mediated polymorphonuclear leukocyte infiltration, with resultant loss of lysosomal granules and possibly the generation of free radicals. We have recently seen previously unreported vascular lesions in 3 infants with hypoplastic left heart syndrome treated with usual therapeutic doses of PGE1 for prolonged periods. At autopsy, pulmonary vascular changes reflecting increased flow were present in each infant. One infant had a necrotizing vasculitis, sometimes associated with infarcts, in the lungs and in small muscular arteries in other organs. The form and severity of the vascular changes appear to be related to the duration of PGE1 administration.