Inhibition of CDK8 Mediator Kinase Suppresses Estrogen Dependent Transcription and the Growth of Estrogen Receptor Positive Breast Cancer

Hormone therapy targeting estrogen receptor (ER) is the principal treatment for ER-positive breast cancers. However, many cancers develop resistance to hormone therapy while retaining ER expression. Identifying new druggable mediators of ER function can help to increase the efficacy of ER-targeting drugs. Cyclin-dependent kinase 8 (CDK8) is a Mediator complex-associated transcriptional regulator with oncogenic activities. Expression of CDK8, its paralog CDK19 and their binding partner Cyclin C are negative prognostic markers in breast cancer. Meta-analysis of transcriptome databases revealed an inverse correlation between CDK8 and ERα expression, suggesting that CDK8 could be functionally associated with ER. We have found that CDK8 inhibition by CDK8/19-selective small-molecule kinase inhibitors, by shRNA knockdown or by CRISPR/CAS9 knockout suppresses estrogen-induced transcription in ER-positive breast cancer cells; this effect was exerted downstream of ER. Estrogen addition stimulated the binding of CDK8 to the ER-responsive GREB1 gene promoter and CDK8/19 inhibition reduced estrogen-stimulated association of an elongation-competent phosphorylated form of RNA Polymerase II with GREB1. CDK8/19 inhibitors abrogated the mitogenic effect of estrogen on ER-positive cells and potentiated the growth-inhibitory effects of ER antagonist fulvestrant. Treatment of estrogen-deprived ER-positive breast cancer cells with CDK8/19 inhibitors strongly impeded the development of estrogen independence. In vivo treatment with a CDK8/19 inhibitor Senexin B suppressed tumor growth and augmented the effects of fulvestrant in ER-positive breast cancer xenografts. These results identify CDK8 as a novel downstream mediator of ER and suggest the utility of CDK8 inhibitors for ER-positive breast cancer therapy

Brixsino High-Flux Dual X-Ray and THz Radiation Source Based on Energy Recovery Linacs

We present the conceptual design of a compact light source named BriXSinO. BriXSinO was born as demonstrator of the Marix project, but it is also a dual high flux radiation source Inverse Compton Source (ICS) of X-ray and Free-Electron Laser of THz spectral range radiation conceived for medical applications and general applied research. The accelerator is a push-pull CW-SC Energy Recovery Linac (ERL) based on superconducting cavities technology and allows to sustain MW-class beam power with almost just one hundred kW active power dissipation/consumption. ICS line produces 33 keV monochromatic X-Rays via Compton scattering of the electron beam with a laser system in Fabry-Pérot cavity at a repetition rate of 100 MHz. The THz FEL oscillator is based on an undulator imbedded in optical cavity and generates THz wavelengths from 15 to 50 micron

Molecular-genetics of the hypoalphalipoproteinemias in Italy

The molecular bases of hypoalphalipoproteinemia (HA), which is associated with premature coronary heart disease (pCAD) in most cases, were investigated in 80 Italian probands. ABCA1, Apo AI, LCAT, LPL and GBA were the candidate genes. The molecular defect was found in 64% of probands (4% ABCA1, 4% Apo AI, 11% LCAT, 44% LPL and 1% GBA mutations). Premature CAD was found in homozygotes for ABCA1 and Apo AI gene mutations and in heterozygotes who also carried other cardiovascular risk factors. In heterozygous subjects for LCAT mutations, there was no clear evidence of an increase in cardiovascular risk. A high prevalence of pCAD was found in males over 40 carrying LPL gene mutations. © 2003 Elsevier Science B.V

Relationship between surface properties and cellular responses to crystalline silica: Studies with heat-treated cristobalite

A fibrogenic sample of cristobalite dust, CRIS (crystalline silica of mineral origin), was heated to 1300 degrees C (CRIS-1300) to relate induced physicochemical modifications to cytotoxicity. Heating did not affect dust micromorphology and crystallinity, except for limited sintering and decreased surface area of CRIS-1300. Thermal treatments deeply affected surface properties. Electron paramagnetic resonance showed surface radicals progressively annealed by heating, mostly disappearing at greater than or equal to 800 degrees C. Surface hydrophilicity or hydrophobicity, evaluated with water vapor adsorption, still showed some hydrophilic patches in CRIS-800, but CRIS-1300 was fully hydrophobic. Heating modified the biological activity of cristobalite. Cytotoxicity, tested on proliferating cells of the mouse monocyte macrophage cell line J774, showed that CRIS was cytotoxic and CRIS-800 was still cytotoxic, but CRIS-1300 was substantially inert. Cytotoxicity of CRIS to the rat lung alveolar epithelial cell line, AE6, as measured by colony forming efficiency, was greatly reduced for CRIS-800 and eliminated for CRIS-1300. The rate of lactate dehydrogenase release by rat alveolar macrophages was lowered for CRIS-800, and release was completely inactivated for CRIS-1300. The absence of surface radicals and the onset of hydrophobicity may both account for the loss of cytotoxicity upon heating. Differences observed between CRIS-800 and CRIS-1300, both fully deprived of surface radicals, indicate that hydrophobicity is at least one of the surface properties determining the cytotoxic potential of a dust