Effect of 11-Deoxycorticosterone in the Transcriptomic Response to Stress in Rainbow Trout Skeletal Muscle.

In aquaculture, many stressors can negatively affect growth in teleosts. It is believed that cortisol performs glucocorticoid and mineralocorticoid functions because teleosts do not synthesize aldosterone. However, recent data suggest that 11-deoxycorticosterone (DOC) released during stress events may be relevant to modulate the compensatory response. To understand how DOC modifies the skeletal muscle molecular response, we carried out a transcriptomic analysis. Rainbow trout (Oncorhynchus mykiss) were intraperitoneally treated with physiological doses of DOC in individuals pretreated with mifepristone (glucocorticoid receptor antagonist) or eplerenone (mineralocorticoid receptor antagonist). RNA was extracted from the skeletal muscles, and cDNA libraries were constructed from vehicle, DOC, mifepristone, mifepristone plus DOC, eplerenone, and eplerenone plus DOC groups. The RNA-seq analysis revealed 131 differentially expressed transcripts (DETs) induced by DOC with respect to the vehicle group, mainly associated with muscle contraction, sarcomere organization, and cell adhesion. In addition, a DOC versus mifepristone plus DOC analysis revealed 122 DETs related to muscle contraction, sarcomere organization, and skeletal muscle cell differentiation. In a DOC versus eplerenone plus DOC analysis, 133 DETs were associated with autophagosome assembly, circadian regulation of gene expression, and regulation of transcription from RNA pol II promoter. These analyses indicate that DOC has a relevant function in the stress response of skeletal muscles, whose action is differentially modulated by GR and MR and is complementary to cortisol.

New-D-homoandrost-4,6-diene derivatives as potent progesterone receptor antagonist.

The aim of this study was to synthesize three different D-homoandrostadiene derivatives (2-4) and study their biological activity. We carried out in vivo and in vitro experiments using female cycling mice, which were synchronized for estrus with luteinizing hormone-releasing hormone (LHRH) and injected with the steroidal compounds. It was also determined the binding of these compounds to the progesterone receptors (PR). Since these steroids have a new D-homoandrostandienone skeleton in their molecular structure, it was of interest also to study their binding to the androgen receptors (AR). After LHRH treatment, the mice of the control group showed the presence of 14+/-4 corpus lutea in the ovary whereas the animals treated with steroids 2-4, with RBAs of 100%, exhibited 11+/-7, 12+/-2, and 10+/-4 respectively. As a result of this study, it is evident that these steroids did not inhibit the ovulation in these animals. The uterus of the control group, showed the typical progestational activity with an enlarged endometrial thickness with a secretory activity. However, the endometrium of the mice treated with steroids 2-4 did not show an enlargement of the endometrium and no secretory activity could be detected. This fact indicates that compounds 2-4 had antagonistic activity in this tissue. The overall data show that steroids 2-4 are antagonists of the PR. However, they do not bind to the AR. These results also demonstrate that 2-4 have an antiprogestational activity in vivo, but do not decrease the number of corpus lutea in the ovary of mice treated with LHRH.

New lead compounds in the search for pure antiglucocorticoids and the dissociation of antiglucocorticoid effects.

Antiglucocorticoids that act as antagonists at the glucocorticoid receptor (GR) level may be used to block or modulate the undesirable effects of glucocorticoid excess (from endogenous or exogenous origin). RU486 developed in the early 80s, is an antiglucocorticoid but also a potent antiprogestin and abortifacient, nevertheless it still remains as the only GR antagonist drug in the market. Further on, in view of the variety of physiological processes in which glucocorticoids are involved, selective antiglucocorticoids that can block only some of these processes (eventually with tissue specificity) would be highly desirable. The bridged pregnane 21-hydroxy-6,19-epoxyprogesterone, was developed as an alternative lead being an antagonist of the GR with no affinity for mineralocorticoid and progesterone receptors. Antagonistic activity was evidenced by partial blocking of dexamethasone induction of tyrosine aminotransferase (TAT) and thymocyte apoptosis. Replacement of the oxygen bridge by a sulfur bridge gave a less bent, more flexible molecule. 21-Hydroxy-6,19-epithioprogesterone exhibited improved antiapoptotic activity on thymocytes but was not effective blocking TAT induction. This selectivity was improved further by oxidation to the sulfone. The sulfone but not the reduced compound also reverted the dexamethasone-mediated inhibition of NFkappaB activity in HeLa cells. Blocking of the apoptotic effect of TNFalpha by dexamethasone in the L929 cell line (mouse fibroblasts), was only reverted partially by the sulfone which exhibited a mild agonistic/antagonistic activity in this assay. None of these compounds showed antiprogestin activity. Similar overall molecular shapes but more lipophylic and with higher metabolic stability were obtained by introduction of a methylene bridge (6,19-methanoprogesterone) or by a direct bond between C-6 and C-19 (6,19-cycloprogesterone and its 21-hydroxy derivative). The latter highly bent steroids showed affinity for the GR. Recently we performed molecular dynamics simulations of GR-ligand complexes to investigate the molecular basis of the passive antagonism exhibited by 21-hydroxy-6,19-epoxyprogesterone. On the basis of our findings, we proposed that the passive antagonist mode of action of this antiglucocorticoid analog resides, at least in part, in the incapacity of GR-21-hydroxy-6,19-epoxyprogesterone complex to dimerize, making the complex unable to activate gene transcription.

Isolation of a stromal cell line from an early passage of a mouse mammary tumor line: a model for stromal parenchymal interactions.

We have developed a murine mammary tumor cell line, MC4-L4, and after 15 passages, a spindle-shaped population became evident. The cuboidal cells, MC4-L4E, cloned by limit dilution, proved to be epithelial tumor cells. When inoculated in syngeneic mice, they gave rise to invasive metastatic carcinomas expressing estrogen and progesterone receptors. These tumors regressed after anti-progestin treatment and stopped growing after 17-beta-estradiol administration. In vitro, they were insensitive to medroxyprogesterone acetate (MPA), 17-beta-estradiol, and EGF and were inhibited by TGFbeta1. They expressed mutated p53 and estrogen receptors alpha; progesterone receptors were undetectable. Cells were polyploid and shared the same four common marker chromosomes present in the parental tumor in addition to an exclusive marker. Spindle-shaped cells, MC4-L4F, were selected by differential attachment and detachment and proved to be non-epithelial non-tumorigenic cells. They were cytokeratin negative, showed mesenchymal features by electron microscopy, differentiated to adipocytes when treated with an adipogenic cocktail, were stimulated by TGFbeta1 and EGF, showed a wild-type p53, and did not exhibit the marker chromosomes of the parental tumor. Although they expressed estrogen receptors alpha, they were insensitive to 17-beta-estradiol in proliferation assays. Co-cultures of both cell types had a synergic effect on progesterone receptors expression and on cell proliferation, being the epithelial cells, the most responsive ones, and 17-beta-estradiol increased cell proliferation only in co-cultures. Cytogenetic studies and data on p53 mutations rule out the possibility of an epithelial mesenchymal transition. Their unique characteristics make them an excellent model to be used in studies of epithelial-stromal interactions in the context of hormone responsiveness in hormone related tumors.