High specific activity estradiol labeled with iodine-125 was used to detect approximately 200 saturable, high-affinity (dissociation constant approximately equal to 1.0 nM) nuclear binding sites in rat (ROS 17/2.8) and human (HOS TE85) clonal osteoblast-like osteosarcoma cells. Of the steroids tested, only testosterone exhibited significant cross-reactivity with estrogen binding. RNA blot analysis with a complementary DNA probe to the human estrogen receptor revealed putative receptor transcripts of 6 to 6.2 kilobases in both rat and human osteosarcoma cells. Type I procollagen and transforming growth factor-beta messenger RNA levels were enhanced in cultured human osteoblast-like cells treated with 1 nM estradiol. Thus, estrogen can act directly on osteoblasts by a receptor-mediated mechanism and thereby modulate the extracellular matrix and other proteins involved in the maintenance of skeletal mineralization and remodeling.

Purpose: In patients with suspected giant cell arteritis (GCA), a search for the perivascular halo sign, a sophisticated color duplex ultrasound (CDU) finding, at experienced centers reliably identifies inflamed temporal arteries (TA). We tested whether TA compression in patients with GCA, a simple, largely operator-independent maneuver, elicits contrasting echogenicity between the diseased artery wall and the surrounding tissue (compression sign). Materials and Methods: 80 individuals with suspected GCA were prospectively enrolled in this single-center study. In all study participants, bilateral ultrasound examination of the TA established the presence/absence of the halo and compression sign. A positive compression sign was defined as visibility of the TA upon transducer-imposed compression of the artery. Based on ACR criteria, a team of specialized physicians independently grouped patients as GCA versus non-GCA. Results: 43/80 study participants were grouped as GCA. Both the halo sign and the compression sign were positive in 34/43 patients in the GCA group, and negative in all 37/37 of the non-GCA group, resulting in a sensitivity of 79?% and a specificity of 100?% for both the halo and the compression sign. Conclusion: In this cohort of individuals with suspected GCA, the halo sign and the compression sign were equal in their diagnostic performance. The simplicity of the compression sign suggests a level of reliability warranting further evaluation.

There is strong experimental evidence that oxidized low density lipoprotein (Ox-LDL) plays an important role in atherosclerosis. However, the mechanisms by which Ox-LDL is formed in vivo are unknown. To test whether 15-lipoxygenase (15-LO) could play a role in oxidation of LDL by cells, we expressed 15-LO activity in murine fibroblasts, which do not normally have 15-LO activity, and tested their ability to modify LDL. Using a retroviral vector, we prepared fibroblasts that expressed 2- to 20-fold more 15-LO activity than control fibroblasts infected with a vector containing beta-galactosidase (lacZ). Compared with LDL incubated with lacZ cells, LDL incubated with 15-LO-containing cells were enriched with lipid hydroperoxides. When these LDL samples were subsequently subjected to oxidative stress, they were more susceptible to further oxidative modification, as judged by increased conjugated diene formation and by increased ability to compete with 125I-Ox-LDL for uptake by macrophages. These findings establish that cellular 15-LO can contribute to oxidative modification of LDL, but the quantitative significance of these findings to the in vivo oxidation of LDL remains to be established.

Clinical observations have demonstrated a positive effect of estrogens and androgens on the maintenance of structural bone integrity. This study examines the direct effects of androgenic hormones on the osteoblast-like human osteosarcoma cell line, HOS TE85. Employing radiolabeled dihydrotestosterone (DHT), 2800 saturable, high-affinity (dissociation constant = 0.66 nM) androgen binding sites were detected per HOS TE85 cell. Androgen binding was specific in that DHT and testosterone (T) displayed significantly greater competition than the progestins, progesterone and medroxyprogesterone. The expression of androgen receptors in HOS TE85 cells was further substantiated by Northern analysis. A human androgen receptor complementary DNA probe revealed a 9.5 kilobase transcript which corresponds to the predominant human androgen receptor transcript detected in human male reproductive tissues. Androgens were also found to elicit biological responses in HOS TE85 cells. Physiological concentrations of DHT and T decreased HOS TE85 cell proliferation as assessed by cell count. This finding suggests that DHT may also play a role in osteoblast differentiation. In support of this hypothesis, treatment with T (24 h, 10 nM) enhanced the abundance of both alpha 1(I)-procollagen messenger RNA (mRNA) (5-fold) and transforming growth factor-beta mRNA (2.2 fold). The nonaromatizable androgen DHT (24 h, 10 nM) elicited an increase in the steady state concentration of alpha 1(I)-procollagen mRNA similar to the increase observed with T treatment. Thus, in addition to the recent discovery of estradiol receptors and estrogenic regulation of HOS TE85 cells, it is now evident that these osteoblast-like osteosarcoma cells also express high affinity androgen binding sites and can respond biologically to androgens.

BACKGROUND: HMGA1 is a non-histone nuclear protein that regulates cellular proliferation, invasion and apoptosis and is overexpressed in many carcinomas. In this study we sought to explore the expression of HMGA1 in HCCs and cirrhotic tissues, and its effect in in vitro models. METHODS: We evaluated HMGA1 expression using gene expression microarrays (59 HCCs, of which 37 were matched with their corresponding cirrhotic tissue and 5 normal liver donors) and tissue microarray (192 HCCs, 108 cirrhotic tissues and 79 normal liver samples). HMGA1 expression was correlated with clinicopathologic features and patient outcome. Four liver cancer cell lines with stable induced or knockdown expression of HMGA1 were characterized using in vitro assays, including proliferation, migration and anchorage-independent growth. RESULTS: HMGA1 expression increased monotonically from normal liver tissues to cirrhotic tissue to HCC (P < .01) and was associated with Edmondson grade (P < .01). Overall, 51% and 42% of HCCs and cirrhotic tissues expressed HMGA1, respectively. Patients with HMGA1-positive HCCs had earlier disease progression and worse overall survival. Forced expression of HMGA1 in liver cancer models resulted in increased cell growth and migration, and vice versa. Soft agar assay showed that forced expression of HMGA1 led to increased foci formation, suggesting an oncogenic role of HMGA1 in hepatocarcinogenesis. CONCLUSIONS: HMGA1 is frequently expressed in cirrhotic tissues and HCCs and its expression is associated with high Edmondson grade and worse prognosis in HCC. Our results suggest that HMGA1 may act as oncogenic driver of progression, implicating it in tumor growth and migration potential in liver carcinogenesis.