Germ cell cysts, a fetal feature in mammals, are constitutively present in the adult armadillo.

Formation and subsequent break down of ovarian germ cell (GC) cysts is a key and an evolutionary-conserved developmental event, described in phylogenetically diverse species of invertebrates and vertebrates. In mammals, cyst break down (CBD) ends at the time of, or soon after, birth with the formation of primordial follicles enclosing single oocytes, which constitute the sole reservoir of gametes available through the whole female's reproductive life. In this study, we challenge this paradigm demonstrating the constitutive presence of a large number of cysts, enclosing two-thirty GCs, in the ovary of the adult armadillo Chaetophractus villosus, belonging to the superorder Xenarthra, one of the earliest offshoots among placentals. We also describe that (a) GCs enclosed within cysts are connected by intercellular bridges-intercellular bridges-markers of their clonal origin; (b) CBD occurs through four main phases, ending with primordial follicles containing single oocytes; (c) GCs encompass meiotic prophase I stages, from leptotene to diplotene; (d) seasonal variations in the number of GCs enclosed within cysts, suggesting the presence of a GC multiplying activity. The armadillo C. villosus''s ovary emerges as an extraordinary resource to investigate folliculogenesis and to explore the evolutionary past of the mammalian ovary.

Protection of radiation-induced damage to the hematopoietic system, small intestine and salivary glands in rats by JNJ7777120 compound, a histamine H4 ligand.

Based on previous data on the histamine radioprotective effect on highly radiosensitive tissues, in the present work we aimed at investigating the radioprotective potential of the H4R ligand, JNJ7777120, on ionizing radiation-induced injury and genotoxic damage in small intestine, salivary glands and hematopoietic tissue. For that purpose, rats were divided into 4 groups. JNJ7777120 and JNJ7777120-irradiated groups received a daily subcutaneous JNJ7777120 injection (10 mg/kg) starting 24 h before irradiation. Irradiated groups received a single dose of 5 Gy on whole-body using Cesium-137 source and were sacrificed 3 or 30 days after irradiation. Tissues were removed, fixed, stained with hematoxylin and eosin or PAS staining and histological characteristics were evaluated. Proliferative and apoptotic markers were studied by immunohistochemistry, while micronucleus assay was performed to evaluate DNA damage. Submandibular gland (SMG) function was evaluated by methacholine-induced salivation. Results indicate that JNJ7777120 treatment diminished mucosal atrophy and preserved villi and the number of crypts after radiation exposure (240±8 vs. 165±10, P<0.01). This effect was associated to a reduced apoptosis and DNA damage in intestinal crypts. JNJ7777120 reduced radiation-induced aplasia, preserving medullar components and reducing formation of micronucleus and also it accelerated bone marrow repopulation. Furthermore, it reduced micronucleus frequency in peripheral blood (27±8 vs. 149±22, in 1,000 erythrocytes, P<0.01). JNJ7777120 completely reversed radiation-induced reduced salivation, conserving glandular mass with normal histological appearance and reducing apoptosis and atrophy of SMG. JNJ7777120 exhibits radioprotective effects against radiation-induced cytotoxic and genotoxic damages in small intestine, SMG and hematopoietic tissues and, thus, could be of clinical value for patients undergoing radiotherapy.

Cytogenetic findings, Trp53 mutations, and hormone responsiveness in a medroxyprogesterone acetate induced murine breast cancer model.

Medroxyprogesterone acetate (MPA)-induced mammary carcinomas express high levels of estrogen (ER) and progesterone receptors (PR) and when transplanted in syngeneic mice they show a progestin-dependent (PD) growth pattern. By successive transplantation, progestin-independent (PI) variants were generated and showed a different response to antihormone therapy. A diploid chromosome number (2n=40) was found in three of five PD tumors, with numbers in the triploid to tetraploid range in the other two. Some PI tumors were diploid, but most were aneuploid (8 of 12 tumors). The most frequent alterations found in PD and PI tumors were gains of chromosomes 3, 4, and 6 and losses of chromosomes 16 and X. Chromosomes 4 and 7 were involved in translocations in three of the four tumor families studied. single-strand conformation polymorphism analysis revealed a point mutation on the Trp53 gene in one of the PD tumors; this showed a stable diploid karyotype, suggesting that mutated Trp53 is not uniquely involved in chromosome instability. We have shown that hormone independence may be acquired without changes in ploidy, suggesting that the increase in ploidy is favored by successive transplantation. In our model, diploid tumors responded to hormone treatment but aneuploid tumors were either responsive or not.

Establishment of two hormone-responsive mouse mammary carcinoma cell lines derived from a metastatic mammary tumor.

We report the establishment of two mouse mammary cancer cell lines, MC7-2A and MC7-2B obtained from a mouse mammary carcinoma induced by medroxyprogesterone acetate (MPA) and maintained by syngeneic transplantation in BALB/c mice. They are epithelial (express cytokeratins) and express both estrogen receptors alpha (ERalpha) and progesterone receptors (PRs) isoforms A and B (western blots). In vitro, MPA inhibited 3H-thymidine uptake, starting from concentrations as low as 10(-13) M in MC7-2A and 10(10) M in MC7-2B; the antiprogestin RU 486 exerted a stimulatory effect at 10(-14) M in both cell lines; 17-beta-estradiol (E2) also exerted a stimulatory effect starting at 10(-10) M in MC7-2A and at 10(-13) M in MC7-2B. When transplanted in syngeneic mice, both cell lines originated adenocarcinomas that gave rise to lung metastases within 3 months. In in vivo studies, in MC7-2A, the antiprogestin inhibited completely tumor growth, E2 induced a slight although significant ( p < 0.05) stimulatory effect and MPA stimulated tumor growth while MC7-2B cells were unresponsive to all treatments. ER and PR were also expressed in tumors as assessed by immunohistochemistry. Two marker chromosomes were identified by FISH as translocations between chromosomes 4 and 7, and between chromosomes X and 2; the third marker chromosome remains unidentified. All these markers were also present in the parental tumor. A new marker, a centric fusion of chromosomes 2, was acquired in both cell lines. Considering that there are very few murine breast carcinoma responsive cell lines, these cells represent new tools in which the regulatory effect of hormones can be studied.

Karyotypic evolution of four novel mouse mammary carcinoma cell lines. Identification of marker chromosomes by fluorescence in situ hybridization.

We studied the karyotypes of four different mammary carcinoma cell lines derived from a medroxy-progesterone acetate (MPA)-induced mouse mammary carcinoma using G-banding and fluorescence in situ hybridization. All the cell lines showed the same four marker chromosomes (M1-M4) as the parental tumor and also acquired new markers. M1 and M2 are Robertsonian translocations between chromosomes 1 and 10 and 2 and 17. M3 is an acrocentric marker derived from chromosomes 4, 5, and 12; M4 is derived from chromosomes 6 and 8. The parental tumor disclosed a modal number of 39, with a trisomy of chromosomes 3, 4, 10, and 11 and monosomies of 9, 13, and 16. MC4-L1 and MC4-L3 lines had a chromosome number similar to that of the parental tumor in early passages, which increased to the triploid range in late passages. MC4-L5 showed a near-diploid modal number in both early and late passages. MC4-L2 cells had a high chromosome number even in early passages. To our knowledge, this is the first study in which a complete characterization of the cytogenetics of murine mammary carcinoma cell lines and of their parental tumor is described. No associations between changes in ploidy, invasiveness, or hormone dependence were found. Conversely, the presence of one exclusive marker chromosome, a translocation between chromosomes 1 and 18 (M5), in the most aggressive and in vivo hormone-independent line suggests that this rearrangement may be associated with these biologic features. The constant presence of common marker chromosomes in both the parental tumor and the derived cell lines suggests that they are involved in the maintenance of this tumor phenotype.