Negative regulation of placental fibronectin expression by glucocorticoids and cyclic adenosine 3',5'-monophosphate

Involvement of upregulation of fibronectin in the pro‑adhesive and pro‑survival effects of glucocorticoid on melanoma cells

Glucocorticoids (GCs) are important stress hormones, which are used as a concomitant medication during malignant tumor chemotherapy. Clinical and preclinical studies have linked GCs to melanoma growth and progression. However, the effects and mechanism of action of GCs on the adhesion and survival of melanoma cells are still unknown. In the present study the effect of dexamethasone (Dex), a synthetic GC, on fibronectin (FN) expression and its roles in regulating the adhesion and survival of melanoma cells were investigated. It was revealed that Dex significantly increased the levels of intracellular and secreted FN in melanoma cell lines by increasing glucocorticoid receptor‑mediated FN protein stability. Additionally, it was demonstrated that Dex (100 nM) significantly promoted the adhesion and survival of melanoma cells. Silencing FN expression abrogated the pro‑adhesive and pro‑survival effects of Dex in melanoma cells. Extracellular FN significantly enhanced melanoma cell adhesion and survival in the presence of cisplatin, whereas partially blocking extracellular FN signaling with a CD44 antibody significantly reduced FN‑enhanced adhesion and survival. This indicated that the upregulation of FN contributed to the pro‑survival effect of Dex by enhancing cell adhesion. It was also observed that activation of the PI3K/AKT signaling pathway by extracellular FN was involved in the FN‑mediated increase in melanoma cell survival. These findings increase understanding of the possible mechanisms by which GCs regulate melanoma cell adhesion and survival.

The pro-adhesive and pro-survival effects of glucocorticoid in human ovarian cancer cells

Cell adhesion to extracellular matrix (ECM) is controlled by multiple signaling molecules and intracellular pathways, and is pivotal for survival and growth of cells from most solid tumors. Our previous works demonstrated that dexamethasone (DEX) significantly enhances cell adhesion and cell resistance to chemotherapeutics by increasing the levels of integrin β1, α4, and α5 in human ovarian cancer cells. However, it is unclear whether the components of ECM or other membrane molecules are also involved in the pro-adhesive effect of DEX in ovarian cancer cells. In this study, we demonstrated that the treatment of cells with DEX did not change the expression of collagens (I, III, and IV), laminin, CD44, and its principal ligand hyaluronan (HA), but significantly increased the levels of intracellular and secreted fibronectin (FN). Inhibiting the expression of FN with FN1 siRNA or blocking CD44, another FN receptor, with CD44 blocking antibody significantly attenuated the pro-adhesion of DEX, indicating that upregulation of FN mediates the pro-adhesive effect of DEX by its interaction with CD44 besides integrin β1. Moreover, DEX significantly enhanced cell resistance to the chemotherapeutic agent paclitaxel (PTX) by activating PI-3K-Akt pathway. Finally, we found that DEX also significantly upregulated the expression of MUC1, a transmembrane glycoprotein. Inhibiting the expression of MUC1 with MUC1 siRNA significantly attenuated the DEX-induced effects of pro-adhesion, Akt-activation, and pro-survival. In conclusion, these results provide new data that upregulation of FN and MUC1 by DEX contributes to DEX-induced pro-adhesion and protects ovarian cancer cells from chemotherapy.

Spatial differences in biologic activity of large uterine leiomyomata

OBJECTIVE

To evaluate the growth pattern of the large uterine leiomyomata (ULM), we examined the spatial gene distributions, vessel density, proliferative activity, and hyaline degeneration.

DESIGN

Tissue sections from three-dimensional large ULM, matched myometrium, and small ULM were collected and microarrayed. The spatial difference of the tumor activity was mapped in large ULM.

SETTING

University clinical research laboratory.

PATIENT(S)

Hysterectomy specimens from 7 patients with large (>10 cm) ULM and 3 patients with large (>10 cm) uterine leiomyosarcomas.

INTERVENTION(S)

Tissue microarray analysis by the immunohistochemistry.

MAIN OUTCOME MEASURE(S)

Selected gene products, vessel density, and the percentage of hyaline degeneration were all scored in tissue cores/sections of large and small ULM against matched myometrium.

RESULT(S)

We found that there was a spherical spatial difference of the tumor activities in large ULM. The tumor region next to the periphery, the most biologically active zone, demonstrated higher levels of gene expression, a higher density of vessels, a higher proliferative rate and a lower level of hyaline degeneration. The large ULM have higher levels of gene products (except for estrogen and progesterone receptors) than small ULM.

CONCLUSION(S)

In comparison of the spatial patterns of the gene activity between the large ULM and the large uterine leiomyosarcoma, the large ULM illustrate a growth pattern of nutritional dependence.

TGF‐β signaling and the fibrotic response

The cause of fibrotic diseases, pathologies characterized by excessive production, deposition, and contraction of extracellular matrix, is unknown. To understand the molecular basis of fibrotic disease, it is essential to appreciate how matrix deposition is normally controlled and how this process is dysregulated in fibrogenesis. This review discusses the current state of knowledge concerning interactions among the profibrotic proteins transforming growth factor-beta (TGF-beta), connective tissue growth factor (CTGF, CCN2), and ED-A fibronectin (ED-A FN) and the antifibrotic proteins tumor necrosis factor-alpha (TNF-alpha) and gamma-interferon (IFN-gamma).

Cell type-specific regulation of fetal fibronectin expression in amnion: conservation of glucocorticoid responsiveness in human and nonhuman primates

The appearance of oncofetal fibronectin (FFN) in cervical and vaginal secretions is predictive of human labor. Levels of FFN in amnion increase with the onset of labor in rhesus monkeys. Since glucocorticoid (GC) levels in serum and amniotic fluid increase in association with parturition, we compared GC-mediated regulation of FFN expression in cultures of amnion epithelial cells and fibroblasts isolated from human and baboon amnions. Cells were maintained with and without dexamethasone (DEX), and levels of FFN in the conditioned media were determined by ELISA. We observed that DEX treatment suppressed FFN levels in both human and baboon amnion epithelial cells, whereas it increased FFN levels in amnion fibroblasts. DEX treatment reduced FFN levels in cytotrophoblasts from human placenta and increased FFN levels in placental fibroblasts. Northern blots revealed that DEX reduced levels of fibronectin (FN) mRNA in amnion epithelial cells and cytotrophoblasts, whereas it increased FN mRNA in amnion and placental fibroblasts. We conclude that GC differentially regulates FFN expression in epithelial and mesenchymal cells from amnion and placenta. In addition, this pattern of cell type-specific FFN regulation by GC is conserved in human and nonhuman primates and may be responsible for parturition-dependent changes in FFN expression in gestational tissues.

In vitro modulation of the expression of 15-hydroxy-prostaglandin dehydrogenase by trophoblast differentiation

OBJECTIVE

Our goal was to determine the expression and activity of 15-hydroxy-prostaglandin dehydrogenase, a prostaglandin-metabolizing enzyme, in differentiating trophoblasts in vitro.

STUDY DESIGN

Cytotrophoblasts from placentas of term healthy women were cultured in either Ham's-Waymouth medium, which hinders the process of cytotrophoblast differentiation, or medium 199, which facilitates differentiation into syncytiotrophoblasts. 15-Hydroxy-prostaglandin dehydrogenase expression was determined with Western immunoblotting, and activity was measured by a specific enzyme immunoassay of 13, 14-dihydro-15-keto prostaglandin F2 alpha, an inactive product of 15-hydroxy-prostaglandin dehydrogenase activity.

RESULTS

The expression and activity of 15-hydroxy-prostaglandin dehydrogenase were enhanced during trophoblast differentiation and were higher in cells grown in medium 199 than in those grown in Ham's-Waymouth medium. 8-Bromo-cyclic adenosine monophosphate, which stimulates prostaglandin H synthase-2 expression, diminished the expression and activity of 15-hydroxy-prostaglandin dehydrogenase in concentration- and time-dependent manners.

CONCLUSIONS

15-Hydroxy-prostaglandin dehydrogenase expression and activity are regulated during trophoblast differentiation and by cyclic adenosine monophosphate. Coordinated expression of l5-hydroxy-prostaglandin dehydrogenase and prostaglandin H synthase-2 contributes to the regulation of prostaglandin release from trophoblasts.

Estrogens and glucocorticoids induce the expression of c-erbB2/NEU receptor in Ishikawa human endometrial cells

We investigated the effects of estrogens and other steroid hormones on c-erbB2 gene expression in Ishikawa human endometrial adenocarcinoma cells. We have found that the c-erbB2/NEU transcripts are present in the Ishikawa endometrial cell line as well as in human endometrial adenocarcinoma cells. Both cell types express the 4.6 and 2.3 kb c-erbB2 mRNAs. Estradiol significantly increased in a time- and dose-dependent manner the content of c-erbB2 mRNA and the concentration of NEU protein in Ishikawa cell extracts, while progesterone was devoid of any activity. The effect of estradiol was partially reversed by the antiestrogen 4-hydroxytamoxifen, which, however, given alone exhibited agonist effects. Glucocorticoid dexamethasone augmented in a time- and dose-dependent fashion the content of c-erbB2 mRNA and the concentration of NEU protein in Ishikawa cell extracts. The antiglucocorticoid RU 486 acted as a glucocorticoid agonist increasing c-erbB2 gene activation. To our knowledge, this is the first report documenting the induction by steroid hormones of c-erbB2 gene expression in neoplastic human endometrial cells. Our data support the hypothesis that the oncogenic effect of estrogens on human endometrial cells may be partially mediated by its effect on the expression of the c-erbB2 proto-oncogene. The finding that glucocorticoids may induce endometrial c-erbB2 gene expression suggests that they may participate in the emergence of uterine neoplasias.