The HDAC inhibitor panobinostat (LBH589) inhibits mesothelioma and lung cancer cells in vitro and in vivo with particular efficacy for small cell lung cancer

Lung cancer is the leading cause of cancer deaths in the United States. Current therapies are inadequate. Histone deacetylase inhibitors (HDACi) are a recently developed class of anticancer agents that cause increased acetylation of core histones and nonhistone proteins leading to modulation of gene expression and protein activityin - volved in cancer cell growth and survival pathways. We examined the efficacyof the HDACi panobinostat (LBH589) in a wide range of lung cancers and mesotheliomas. Panobinostat was cytotoxic in almost all 37 cancer cell lines tested. IC50 and LD50 values were in the low nmol/L range (4–470 nmol/L; median, 20 nmol/L). Small cell lung cancer (SCLC) cell lines were among the most sensitive lines, with LD50 values consistently <25 nmol/L. In lung cancer and mesothelioma animal models, panobinostat significantlyde creased tumor growth byan average of 62% when compared with vehicle control. Panobinostat was equallye ffective in immunocompetent and severe combined immunodeficiencymic e, indicating that the inhibition of tumor growth by panobinostat was not due to direct immunologic effects.Panobinostat was, however, particularlyeffective in SCLC xenografts, and the addition of the chemotherapyag ent etoposide augmented antitumor effects. Protein analysis of treated tumor biopsies revealed elevated amounts of cell cycle regulators such as p21 and proapoptosis factors, such as caspase 3 and 7 and cleaved poly[ADP-ribose] polymerase, coupled with decreased levels of antiapoptotic factors such as Bcl-2 and Bcl-XL. These studies together suggest that panobinostat maybe a useful adjunct in the treatment of thoracic malignancies, especiallySCLC

Class dynamics of development: a methodological note

This article argues that class relations are constitutive of developmental processes and central to understanding inequality within and between countries. In doing so it illustrates and explains the diversity of the actually existing forms of class relations, and the ways in which they interplay with other social relations such as gender and ethnicity. This is part of a wider project to re- vitalise class analysis in the study of development problems and experiences

Acute activation, desensitization and smoldering activation of human acetylcholine receptors.

The behavioral effects of nicotine and other nicotinic agonists are mediated by AChRs in the brain. The relative contribution of acute activation versus chronic desensitization of AChRs is unknown. Sustained "smoldering activation" occurs over a range of agonist concentrations at which activated and desensitized AChRs are present in equilibrium. We used a fluorescent dye sensitive to changes in membrane potential to examine the effects of acute activation and chronic desensitization by nicotinic AChR agonists on cell lines expressing human α4β2, α3β4 and α7 AChRs. We examined the effects of acute and prolonged application of nicotine and the partial agonists varenicline, cytisine and sazetidine-A on these AChRs. The range of concentrations over which nicotine causes smoldering activation of α4β2 AChRs was centered at 0.13 µM, a level found in smokers. However, nicotine produced smoldering activation of α3β4 and α7 AChRs at concentrations well above levels found in smokers. The α4β2 expressing cell line contains a mixture of two stoichiometries, namely (α4β2)2β2 and (α4β2)2α4. The (α4β2)2β2 stoichiometry is more sensitive to activation by nicotine. Sazetidine-A activates and desensitizes only this stoichiometry. Varenicline, cytisine and sazetidine-A were partial agonists on this mixture of α4β2 AChRs, but full agonists on α3β4 and α7 AChRs. It has been reported that cytisine and varenicline are most efficacious on the (α4β2)2α4 stoichiometry. In this study, we distinguish the dual effects of activation and desensitization of AChRs by these nicotinic agonists and define the range of concentrations over which smoldering activation can be sustained

Agonist Efficacy and Sensitivity for Activation and Desensitization.

<p>The EC50’s for activation of α4β2, α3β4 and α7 AChRs are expressed in µM. In cases where the dose response curves fit with a two-site competition model, the EC50 for the higher sensitivity component is listed first. For desensitization, cell lines expressing various human AChRs were incubated overnight in the presence of a range of concentrations of agonists, and then tested for activation by ACh. For α4β2 AChRs, two concentrations of ACh were tested, namely 3 µM (to test the more sensitive stoichiometry (α4β2)₂β2), and 100 µM ACh (to assay function of both stoichiometries). For the other AChRs, saturating concentrations of ACh were used (1.0 mM for α3β4 and 10 µM for α7).</p

Responses of human α4β2, α3β4 and α7-expressing cell lines to various concentrations of nicotinic agonists.

<p>Responses were measured using the FLEXStation with an indicator sensitive to changes in membrane potential. Results are expressed as a percent of maximal fluorescence. Each data point is an average of the peak fluorescence of 4–8 individual dose-response curves. Nicotine and ACh are full agonists on α4β2, whereas varenicline, cytisine and sazetidine-A are partial agonists. All of the tested compounds are full agonists on α3β4 and α7 AChRs.</p

Activation and Desensitization of α4β2 AChRs by Various Agonists.

<p>Responses were measured using the FLEXStation with an indicator sensitive to changes in membrane potential. Results are expressed as a percentage of maximum fluorescence. Activity remaining after 16 hours desensitization by the indicated concentrations of agonist was assayed using 3 µM ACh (to assay function of the more sensitive stoichiometry (α4β2)₂β2), and 100 µM ACh (to assay function of both stoichiometries). Each data point is the average of the peak fluorescence of 4–8 dose-response curves. The responses to acute application of agonists are the same as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079653#pone-0079653-g002" target="_blank">Figure 2</a>. The extent of smoldering activation (shaded area) was calculated by multiplying the extent of acute activation by the extent of sustained desensitization at each concentration. For nicotine, the area of overlap for the more sensitive (α4β2)₂β2 stoichiometry was centered at 0.13 µM, which is a concentration typically found in smokers. Likewise for varenicline, the area of overlap for the more sensitive (α4β2)₂β2 stoichiometry was centered at 0.16 µM, which corresponds to peak concentrations achieved in humans. Sazetidine-A was highly potent at activating as well as desensitizing α4β2 AChRs. The area of overlap for (α4β2)₂β2 AChRs was centered at 1.5 nM. When 100 µM ACh was used for desensitization, there was a plateau on the dose response curve beginning at around 10 nM.</p

Acute responses of AChRs to application of saturating concentrations of ACh.

<p>Fluorescent responses were measured using the FLEXStation with a membrane potential-sensitive indicator. The kinetics of responses of α4β2 (to 300 µM ACh) and α3β4 AChRs (to 1.0 mM ACh) were very similar, with a maximum response reached within 45 seconds of agonist application. The response of α7 AChRs (to 10 µM ACh) was more rapid, with a peak response within 5 seconds, followed by rapid desensitization. Each data point represents the average of 4 individual response curves. The absolute values of responses of saturating concentrations of ACh (expressed as relative fluorescence units) were similar for α4β2 (167,000+/−18,000) and α3β4 (161,000+/−14,000), but significantly lower for α7 AChRs (54,00+/−3000), probably as a result of rapid desensitization.</p

Activation and Desensitization of α7 AChRs by Various Agonists.

<p>Responses were measured using the FLEXStation with an indicator sensitive to changes in membrane potential. Results were expressed as a percentage of maximum fluorescence. Activity remaining after 16 hours desensitization by the indicated concentrations of agonist was assayed using 10 µM ACh. The extent of smoldering activation (shaded area) was calculated by multiplying the extent of acute activation by the extent of sustained desensitization at each concentration. For nicotine, the intercept of the activation and desensitization curves was 1.7 µM (well above the clinically achievable range). However, for varenicline, the intercept of the activation and desensitization curves was 0.4 µM, a concentration which can be reached with therapeutic doses of this drug.</p

Identification of a KRAS mutation in a patient with non-small cell lung cancer treated with chemoradiotherapy and panitumumab

RTOG 0839 is a Phase II study of pre-operative chemoradiotherapy with or without panitumumab in potentially operable locally advanced non-small cell lung cancer (NS CLC). The investigational agent, panitumumab, is an anti-epithelial growth factor receptor (EGFR) antibody that improves progression-free survival in chemorefractory metastatic colorectal cancer (mCRC). Recently, both KRAS mutational status (i.e., mutated or not) and subtype (i.e., activating or inactivating) have been shown to be predictive of response to anti-EGFR therapy in mCRC. However, in NS CLC, it is unknown if KRAS mutational status or subtype predict benefit to anti-EGFR therapies because of unique genetic and epigenetic factors unique to each cancer. We present a patient with stage III NS CLC containing a KRAS G12D activating mutation who had a partial pathologic response, with disappearance of a minor KRAS mutant clone. This case suggests possible eradication of the G12D KRAS lung cancer clones by concurrent chemoradiation with panitumumab. © 2013 Landes Bioscience