Electron Microscopy Findings inN-Methyl-N-Nitrosourea-Induced Mammary Tumors

Although the rat model of mammary tumors chemically induced byN-methyl-N-nitrosourea (MNU) has been frequently used by several research teams, there is a lack of ultrastructural studies in this field. The main aim of this work was to perform an ultrastructural characterization of MNU-induced mammary tumors in female rats. Some alterations previously reported in human mammary tumors, such as nucleus size and shape, accumulation of heterochromatin in the perinuclear region, and interdigitating cytoplasmic processes between cancer cells were also observed in MNU-induced mammary tumors. Although a low number of samples were analyzed by transmission electron microscopy in the present study, we consider that it may contribute to a better understanding of MNU-induced mammary carcinogenesis in a rat model. The ultrastructural characteristics of the two most frequently diagnosed mammary carcinomas described in the present work can be useful to differentiate them from other histological patterns. In addition, the loss of cytoplasm in neoplastic cells and formation of vacuoles were described.

Association of Prolactin and Its Receptor Gene Regions with Familial Breast Cancer

Context: The contribution of prolactin (PRL) through its receptor (PRLR) to the pathogenesis and progression of human mammary tumors has received recent attention. Objective: We investigated whether genetic variation in the PRL and PRLR genes is associated with the risk of breast cancer (BC). Design: We conducted a case-control study with a total of seven single nucleotide polymorphisms (SNPs). Setting: The study was conducted at an academic research laboratory and university clinics. Patients and Other Participants: A total of 441 German familial, unrelated BC cases and 552 controls matched by age, ethnicity, and geographical region participated in the study. Intervention(s): There were no interventions. Main Outcome Measures(s): SNP genotype and haplotype distributions and haplotype interactions were correlated with the risk of BC. Results: Two SNPs (rs1341239 and rs12210179) within the PRL promoter regions were significantly associated with increased risk in homozygotes for the variant alleles [odds ratio (OR), 1.67 and 95% confidence interval (CI), 1.11–2.50; and OR, 2.09 and 95% CI, 1.23–3.52, respectively]. The PRL haplotype containing the variant alleles of the promoter SNPs increased significantly the risk of BC (OR 1.42, 95%CI 1.07–1.90). A PRLR haplotype was associated with a significant decrease in BC risk (OR 0.69, 95% CI 0.54–0.89). An increasing number of PRL and PRLR risk haplotypes led to a significant trend of increasing risk for BC (χ2 = 12.15; P = 0.007). Conclusions: Genetic variation in the PRL and PRLR genes was shown to influence BC risk. Additional studies are needed to further clarify the role of the PRL and PRLR genes in the risk of BC.