Continuum Variability of Active Galactic Nuclei in the Optical-Ultraviolet Range

The variability of the continuum spectral energy distribution has been analyzed for a complete magnitude-limited sample of quasars in Selected Area 57, observed at two epochs in the photographic U, BJ, F, and N bands with the Mayall 4 m telescope at Kitt Peak National Observatory. Changes δα of the spectral slope α appear correlated with brightness variations δ log fν, indicating an average hardening of the spectrum in the bright phases. This confirms that the correlation of variability with redshift, found in a single observing band, is due to intrinsic spectral changes. The average observed δα-δ log fν relation is consistent with the spectral change due to temperature variation of a blackbody of about 2.5 × 104 K

Low Concentrations of Bisphenol A Induce Mouse Spermatogonial Cell Proliferation by G Protein–Coupled Receptor 30 and Estrogen Receptor-α

Background: Bisphenol A (BPA) is one of the most prevalent chemicals in daily-use materials; therefore, human exposure to BPA is ubiquitous. The estrogenicity of BPA is generally mediated by nuclear estrogen receptors (ERs). However, low concentrations of BPA stimulate seminoma cell proliferation by an uncertain mechanism that does not involve activation of ERs

Vascular endothelial growth factor-C expression and its relationship to pelvic lymph node status in invasive cervical cancer

Vascular endothelial growth factor-C (VEGF-C) has been implicated in lymphangiogenesis, the process of new lymphatics formation. The present study investigated VEGF-C mRNA expression in invasive cervical cancer tissue. Additionally, the association of VEGF-C mRNA with clinicopathological features was examined. VEGF-C mRNA expression was assessed by reverse transcription-polymerase chain reaction using β-action as an internal control. 75 patients presenting with invasive cervical cancer were included in the trial. VEGF-C mRNA expression was markedly higher in tumours in which pelvic lymph node metastasis was diagnosed by magnetic resonance (MR) imaging (P = 0.002). 53 patients displaying stage Ib–IIb cervical cancer underwent radical hysterectomy and pelvic lymphadenectomy. VEGF-C expression was significantly higher in tumours exhibiting deep stromal invasion, pelvic lymph node metastasis and lymph-vascular space involvement (P = 0.016, P = 0.006 and P = 0.036, respectively). Multivariate analysis revealed VEGF-C mRNA expression to be the sole independent factor influencing pelvic lymph node metastasis. Subjects demonstrating VEGF-C mRNA expression displayed significantly poorer prognoses than those lacking VEGF-C mRNA expression (P = 0.049). These findings provide evidence supporting the involvement of VEGF-C expression in the promotion of lymph node metastasis in cervical cancer. Furthermore, examination of VEGF-C expression in biopsy specimens may be beneficial in the prediction of pelvic lymph node metastasis. © 2001 Cancer Research Campaign http://www.bjcancer.co

p66 Shc and tyrosine-phosphorylated Shc in primary breast tumors identify patients likely to relapse despite tamoxifen therapy

INTRODUCTION: Shc adapter proteins are secondary messenger proteins involved in various cellular pathways, including those mediating receptor tyrosine kinase signaling and apoptosis in response to stress. We have previously reported that high levels of tyrosine-phosphorylated Shc (PY-Shc) and low levels of its inhibitory p66 Shc isoform are strongly prognostic for identifying both early node-negative and more advanced, node-positive, primary breast cancers with high risk for recurrence. Because aberrant activation of tyrosine kinases upstream of Shc signaling proteins has been implicated in resistance to tamoxifen – the most widely prescribed drug for treatment of estrogen receptor-positive breast cancer – we hypothesized that Shc isoforms may identify patients at increased risk of relapsing despite tamoxifen treatment. METHODS: Immunohistochemical analyses of PY-Shc and p66 Shc were performed on archival primary breast cancer tumors from a population-based cohort (60 patients, 9 relapses) and, for validation, an independent external cohort (31 patients, 13 relapses) in which all patients received tamoxifen as a sole systemic adjuvant prior to relapse. RESULTS: By univariate and multivariate analyses, the Shc proteins were very strong and independent predictors of treatment failure in both the population-based cohort (interquartile hazard ratio = 8.3, 95% confidence interval [CI] 1.8 to 38, P = 0.007) and the validating cohort (interquartile relative risk = 12.1, 95% CI 1.7 to 86, P = 0.013). CONCLUSION: These results suggest that the levels of PY-Shc and p66 Shc proteins in primary tumors identify patients at high risk for relapsing despite treatment with tamoxifen and therefore with further validation may be useful in guiding clinicians to select alternative adjuvant treatment strategies

Phosphorylation of estrogen receptor α serine 167 is predictive of response to endocrine therapy and increases postrelapse survival in metastatic breast cancer

INTRODUCTION: Endocrine therapy is the most important treatment option for women with hormone-receptor-positive breast cancer. The potential mechanisms for endocrine resistance involve estrogen receptor (ER)-coregulatory proteins and crosstalk between ER and other growth factor signaling networks. However, the factors and pathways responsible for endocrine resistance are still poorly identified. METHODS: Using immunohistochemical techniques, we focused on the expression and phosphorylation of hormone receptors themselves and examined the phosphorylation of ER-α Ser118 and ER-α Ser167 and the expression of ER-α, ER-β1, ER-βcx/β2, progesterone receptor (PR), PRA, and PRB in the primary breast carcinomas of 75 patients with metastatic breast cancer who received first-line treatment with endocrine therapy after relapse. RESULTS: Phosphorylation of ER-α Ser118, but not Ser167, was positively associated with overexpression of HER2, and HER2-positive tumors showed resistance to endocrine therapy. The present study has shown for the first time that phosphorylation of ER-α Ser167, but not Ser118, and expression of PRA and PRB, as well as ER-α and PR in primary breast tumors are predictive of response to endocrine therapy, whereas expression of ER-β1 and ER-βcx/β2 did not affect response to the therapy. In addition, patients with either high phosphorylation of ER-α Ser167, or high expression of ER-α, PR, PRA, or PRB had a significantly longer survival after relapse. CONCLUSION: These data suggest that phosphorylation of ER-α Ser167 is helpful in selecting patients who may benefit from endocrine therapy and is a prognostic marker in metastatic breast cancer

The balance of VEGF-C and VEGFR-3 mRNA is a predictor of lymph node metastasis in non-small cell lung cancer

A positive association between vascular endothelial growth factor-C (VEGF-C) expression and lymph node metastasis has been reported in several cancers. However, the relationship of VEGF-C and lymph node metastasis in some cancers, including non-small cell lung cancer (NSCLC), is controversial. We evaluated the VEGF-C and vascular endothelial growth factor receptor-3 (VEGFR-3) expression in NSCLC samples from patients who had undergone surgery between 1998 and 2002 using real-time quantitative RT–PCR and immunohistochemical staining. We failed to find a positive association between VEGF-C and VEGFR-3 mRNA expression and lymph node metastasis in NSCLC. An immunohistological study demonstrated that VEGF-C was expressed not only in cancer cells, but also in macrophages in NSCLC, and that VEGFR-3 was expressed in cancer cells, macrophages, type II pneumocytes and lymph vessels. The VEGF-C/VEGFR-3 ratio of the node-positive group was significantly higher than that of the node-negative group. Immunohistochemical staining showed that VEGFR-3 was mainly expressed in cancer cells. The immunoreactivity of VEGF-C and VEGFR-3 was roughly correlated to the mRNA levels of VEGF-C and VEGFR-3 in real-time PCR. VEGF-C mRNA alone has no positive association with lymph node metastasis in NSCLC. The VEGF-C/VEGFR-3 ratio was positively associated with lymph node metastasis in NSCLC. This suggests that VEGF-C promotes lymph node metastasis while being influenced by the strength of the VEGF-C autocrine loop, and the VEGF-C/VEGFR-3 ratio can be a useful predictor of lymph node metastasis in NSCLC

Activation of Estrogen Receptor-α by E2 or EGF Induces Temporally Distinct Patterns of Large-Scale Chromatin Modification and mRNA Transcription

Estrogen receptor-α (ER) transcription function is regulated in a ligand-dependent (e.g., estradiol, E2) or ligand-independent (e.g., growth factors) manner. Our laboratory seeks to understand these two modes of action. Using a cell line that contains a visible prolactin enhancer/promoter array (PRL-HeLa) regulated by ER, we analyzed ER response to E2 and EGF by quantifying image-based results. Data show differential recruitment of GFP-ER to the array, with the AF1 domain playing a vital role in EGF-mediated responsiveness. Temporal analyses of large-scale chromatin dynamics, and accumulation of array-localized reporter mRNA over 24 hours showed that the EGF response consists of a single pulse of reporter mRNA accumulation concomitant with transient increase in array decondensation. Estradiol induced a novel cyclical pattern of mRNA accumulation with a sustained increase in array decondensation. Collectively, our work shows that there is a stimuli-specific pattern of large-scale chromatin modification and transcript levels by ER

New targets for therapy in breast cancer: Farnesyltransferase inhibitors

Current systemic therapies for breast cancer are often limited by their nonspecific mechanism of action, unwanted toxicities on normal tissues, and short-term efficacy due to the emergence of drug resistance. However, identification of the molecular abnormalities in cancer, in particular the key proteins involved in abnormal cell growth, has resulted in development of various signal transduction inhibitor drugs as new treatment strategies against the disease. Protein farnesyltransferase inhibitors (FTIs) were originally designed to target the Ras signal transduction pathway, although it is now clear that several other intracellular proteins are dependent on post-translational farnesylation for their function. Preclinical data revealed that although FTIs inhibit the growth of ras-transformed cells, they are also potent inhibitors of a wide range of cancer cell lines that contain wild-type ras, including breast cancer cells. Additive or synergistic effects were observed when FTIs were combined with cytotoxic agents (in particular the taxanes) or endocrine therapies (tamoxifen). Phase I trials with FTIs have explored different schedules for prolonged administration, and dose-limiting toxicities included myelosuppression, gastrointestinal toxicity and neuropathy. Clinical efficacy against breast cancer was seen for the FTI tipifarnib in a phase II study. Based on promising preclinical data that suggest synergy with taxanes or endocrine therapy, combination clinical studies are now in progress to determine whether FTIs can add further to the efficacy of conventional breast cancer therapies