Jose Russo

Endocrine Influences on the Mammary Gland

The mammary gland is an organ whose morphology and physiology are constantly during the life span of an animal. Therefore, the study of the mammary gland has to be done taking into consideration the four major phases of its development: (a) prenatal; (b) postnatal, divided into pre- and postpubertal phases; (c) pregnancy-mediated, encompassing pseudopregnancy, pregnancy, lactation, and postlactational involution; and (d) age-related involution (Cowie and Folley 1961; Munford 1963).

Morphology and Development of the Rat Mammary Gland

The mammary gland is an organ whose description in either morphology, physiology, or biochemistry requires one to specify the species, sex, age, reproductive history, and physiologic condition of the host before any definitive conclusion can be drawn. These variables pose a great burden on researchers in the field, since the massive literature available in some species might not apply to others, and extrapolations become necessary, though speculative and subject to further corroboration.

Classification of Neoplastic and Nonneoplastic Lesions of the Rat Mammary Gland

The rat mammary gland is one of the most widely studied and useful models of mammary carcinogenesis (Dao 1962, 1964; Gullino et al. 1975; Huggins et al. 1959; Huggins and Yang 1962; Ito 1981; Russo IH and Russo J 1978; Russo J and Russo IH 1978, 1980; Russo J et al. 1982; Shirai et al. 1981; Van Zwieten 1984; Young and Hallowes 1973). Many strains of rats develop spontaneous tumors and respond to a variety of chemical carcinogens and radiation with the development of hormone-dependent mammary tumors. The classification presented attempts to provide a working framework for diagnosing the type of lesions found in the mammary glands of rats treated with chemical carcinogens or radiation, and to clarify criteria for establishing two basic characteristics of tumors: (a) whether they are epithelial or stromal in origin, and (b) whether they are benign or malignant.

Hormone Production by Tumors: Ectopia or Gene Derepression

That tumors are capable of synthesizing particular hormones or hormone subunits not normally produced by the specific tissue of origin of the tumor has been known since Brown described the diabetes of a bearded woman in Lancet in 1928 (13). However, even though in the autopsy of this obese, diabetic, hirsute and hypertensive patient the presence of bilateral adrenal hyperplasia and oat cell carcinoma of the lung were observed, the clinical syndrome was not correlated with the presence of the tumor. Only did in 1932 Harvey Cushing (18) describe the clinical syndrome, caused by the secretions of adenomatous or hyperplastic pituitary basophil cells stimulating bilateral adrenocortical hyperplasia (43). The characterization of cortisol, and human adrenocorticotropin (ACTH) led to realization that the pituitary is the site of the primary disorder in bilateral adrenal hyperplasia, thus defining ‘Cushing’s disease’, whereas ‘Cushing’s syndrome’ was reserved for the clinical entity caused by extra-hypophyseal secretion of ACTH.

Abstract 3676: The use of r-hCG changes the transcriptome profile of nulliparous women carrying BRCA1 mutation

Nulliparity and inheritance of BRCA1 or BRCA2 mutations are conditions associated with a greater risk of developing breast cancer. The knowledge that early parity reduces a woman9s lifetime cancer risk and the demonstration in preclinical studies that the protective effect of pregnancy is mediated by the differentiation of the breast, which is manifested as permanent changes in the genomic/transcriptomic profile of this organ, led us to hypothesize that the transcriptomic profile of breast tissue of nulliparous BRCA1 mutation carriers would revert from high risk to lower risk after a short treatment with recombinant human chorionic gonadotropin (r-hCG). For this purpose we designed a pilot study for determining whether treatment of sexually mature, from 20 to 40 years of age, nulliparous women carriers of BRCA1 mutations with the r-hCG changes their breast epithelium9s genomic profile to one similar to that identified in cancer-free postmenopausal women with a history of full term pregnancy. After signing an informed consent form, eligible candidates received 250 micrograms r-hCG applied as a subcutaneous injection 3 times a week for 12 weeks. Before initiation of treatment (T0), at the end (T12), and 24 weeks post-treatment (T24) a breast core needle biopsy (CNB) was performed by the study surgeon. In this proof of concept, tissues obtained from two volunteers were divided for histopathological and RNA analyses. Total RNA was extracted, prepared for hybridization using Two-Cycle Target Labeling and Control Reagents kits from Affymetrix, and hybridization to Affymetrix Human Genome U133 Plus 2.0 chips. The chips were analyzed using GeneSpring GX v11.0 software (Agilent Technologies). Comparison of gene expression between T0 and T24 revealed 425 probes (254 up- and 171 down-regulated), representing 349 unique differentially expressed genes (p-value Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3676. doi:10.1158/1538-7445.AM2011-3676

Abstract 3672: Defining the genomic signature of the parous breast

Epidemiological data have consistently shown that a pregnancy early in life confer mothers lifetime protection against breast cancer, which is enhanced by subsequent pregnancies. Previous studies have demonstrated that the protection conferred by pregnancy is mediated by the differentiation of the breast, which is expressed as a specific genomic profile detectable in breast cells of postmenopausal parous women that serves as a biomarker indicative of reduced cancer risk. For further confirming these observations we designed a multidisciplinary study for determining whether the pattern of gene expression differed between nulliparous and parous postmenopausal women from an ethnically homogeneous population residing in Norrbotten County, Sweden; the study was approved by the IRB/Ethical Board of the University of Umea, Sweden. Volunteer women from 50-69 years of age, belonging to one of the following categories based on reproductive history: parous (G≥1/P≥1), nulligravida nullipara (G0/P0) or gravida nullipara (G≥1/P0). The subjects signed an informed consent to participate in the study and donated core needle biopsies (CNB) of breast. CNB were taken from the upper outer quadrant of the breast and divided for 70% ethanol fixation for histopathological analysis and RNA extraction for subsequent genomic analysis. Total RNA was isolated using the Qiagen Allprep RNA/DNA Mini Kit. RNA quantity and quality were determined and the GeneChip Expression 3’-Amplification Two-Cycle cDNA Synthesis Kit (Affymetrix, Santa Clara, CA) was used to prepare the cRNA for hybridization; samples were hybridized to Affymetrix HG_U133 Plus 2.0 oligonucleotide arrays; 71 parous and 42 nulliparous satisfied quality control thresholds based on standard Affymetrix quality control measures. Probesets for which the proportion of Present calls was less than 75% in both samples were filtered out. A variance filter was also applied, removing all probesets whose variance across all samples fell below the first quartile, remaining 18,694 probesets for further analysis using both a p-value of 0.001 from the empirical Bayes moderated t-statistics, and a minimum log2 fold-change of 0.3 threshold as criteria of significance. Two hundred and eight genes were found to be differentially expressed between parous and nulliparous women. Gene ontology and pathway analyses revealed enrichment of biological processes related to regulation of transcription, RNA splicing, cell cycle control, adhesion and differentiation. IGF-like growth factor signaling and somatic stem cell maintenance were significantly downregulated. These results demonstrated that the breast of parous postmenopausal women exhibits a transcriptomic profile that differs from that of nulliparous women, representing a genomic signature induced by full term pregnancy that is indicative of breast differentiation. Work supported by Avon Foundation Women Breast Cancer Research Program grant 02-2008-034. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3672. doi:10.1158/1538-7445.AM2011-3672