Pretubulysin: a new option for the treatment of metastatic cancer

Tubulin-binding agents such as taxol, vincristine or vinblastine are well-established drugs in clinical treatment of metastatic cancer. However, because of their highly complex chemical structures, the synthesis and hence the supply issues are still quite challenging. Here we set on stage pretubulysin, a chemically accessible precursor of tubulysin that was identified as a potent microtubule-binding agent produced by myxobacteria. Although much simpler in chemical structure, pretubulysin abrogates proliferation and long-term survival as well as anchorage-independent growth, and also induces anoikis and apoptosis in invasive tumor cells equally potent to tubulysin. Moreover, pretubulysin posseses in vivo efficacy shown in a chicken chorioallantoic membrane (CAM) model with T24 bladder tumor cells, in a mouse xenograft model using MDA-MB-231 mammary cancer cells and finally in a model of lung metastasis induced by 4T1 mouse breast cancer cells. Pretubulysin induces cell death via the intrinsic apoptosis pathway by abrogating the expression of pivotal antiapoptotic proteins, namely Mcl-1 and Bcl-x_L, and shows distinct chemosensitizing properties in combination with TRAIL in two- and three-dimensional cell culture models. Unraveling the underlying signaling pathways provides novel information: pretubulysin induces proteasomal degradation of Mcl-1 by activation of mitogen-activated protein kinase (especially JNK (c-Jun N-terminal kinase)) and phosphorylation of Mcl-1, which is then targeted by the SCF^Fbw7 E3 ubiquitin ligase complex for ubiquitination and degradation. In sum, we designate the microtubule-destabilizing compound pretubulysin as a highly promising novel agent for mono treatment and combinatory treatment of invasive cancer.     

Drosophila female germline stem cells undergo mitosis without nuclear breakdown

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JAR human placental choriocarcinoma cells actively synthesize,take up and release polyamines

Uptake of polyamines has been investigated extensively in many cells, but not in placenta, where the polyamine– polyamine oxidase system is supposed to have an immunoregulatory function in pregnancy. Due to the importance of the transfer in this tissue, we have started this study. JAR human placental choriocarcinoma cells in monolayer at confluency were used as a model for measuring the key enzymes of polyamine synthesis and interconversion, rate of uptake and efflux, and the polyamine content. Polyamines were taken up by JAR cells and released by an independent mechanism. Ornithine decarboxylase and spermidine acetyltransferase activities and the rate of transport in and out of the cell were much higher than in other cells, such as L1210 cells. However the systems used for uptake and release appear in many respects to be similar to those observed in L1210 cells, but different from others. The uptake appears to be regulated by an inhibitory protein. Moreover, protein kinase C appears to be involved in the process. The efflux also is regulated as in L1210 cells, through control of H⁺ and Ca²⁺ concentration. In conclusion, this study shows that, in JAR cells, ornithine decarboxylase and spermidine acetyltransferase activities were much higher than in other cells, and so was the rate of transport in and out of the cells. As a result, a much higher polyamine content was observed.     

Heterogeneous phenotype of human glioblastoma: In vitro study

Glioblastomas (GBMs) are the most lethal primary brain tumours. Increasing evidence shows that brain tumours contain the population of stem cells, so‐called cancer stem cells (CSCs). Stem cell marker CD133 was reported to identify CSC population in GBM. Further studies have indicated that CD133 negative cells exhibiting similar properties and are able to initiate the tumour, self‐renew and undergo multilineage differentiation. GBM is a highly heterogeneous tumour and may contain different stem cell populations with different functional properties. We characterized five GBM cell lines, established from surgical samples, according to the marker expression, proliferation and differentiation potential. CD133 positive cell lines showed increased proliferation rate in neurosphere condition and marked differentiation potential towards neuronal lineages. Whereas two cell lines low‐expressing CD133 marker showed mesenchymal properties in vitro, that is high proliferation rate in serum condition and differentiation in mesenchymal cell types. Further, we compared therapy resistance capacity of GBM cell lines treated with hydroxyurea. Our results suggest that CSC concept is more complex than it was believed before, and CD133 could not define entire stem cell population within GBM. At least two different subtypes of GBM CSCs exist, which may have different biological characteristics and imply different therapeutic strategies. Copyright © 2013 John Wiley & Sons, Ltd.     

NanoDam identifies Homeobrain (ARX) and Scarecrow (NKX2.1) as conserved temporal factors in the Drosophila central brain and visual system

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YAP1 and PRDM14 converge to promote cell survival and tumorigenesis

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Carbonic Anhydrases in Chick Extra-embryonic Structures: A Role for CA in Bicarbonate Reabsorption Through the Chorioallantoic Membrane

The villus cavity cells, a specific cell type of the chick chorioallantoic membrane, express both cytosolic carbonic anhydrase in their cytoplasm and [Formula: See Text] anion exchangers at their basolateral membranes. By immunohistochemical analysis, we show here that villus cavity cells specifically react with antibodies directed against the membrane-associated form of carbonic anhydrase, CAIV. Staining is restricted to the apical cell membranes, characteristically invaginated toward the shell membrane, as well as to endothelia of blood vessels present in the mesodermal layer. The occurrence of a membrane-associated CA form at the apical pole of villus cavity cells, when definitively confirmed, would be fairly consistent with the role proposed for these cells in bicarbonate reabsorption from the eggshell so to prevent metabolic acidosis in the embryo during development.     

Effect of Conditioned Media from Several Cell Types on Invasion by Eimeria adenoeides Sporozoites1

ABSTRACT. The effect of conditioned media (media aspirated from a variety of cell cultures after 4 d of growth) on cellular invasion by sporozoites of the turkey coccidium, Eimeria adenoeides, was examined. Conditioned medium from turkey kidney cells and baby hamster kidney cells failed to alter invasion. However, conditioned medium from turkey cecal cell cultures produced a significant (P ≤ 0.05), two-fold increase in invasion over control medium in a variety of cell types. Retentates of conditioned medium from the turkey cecal cells that were passed through microconcentrators having molecular mass cutoffs of 50, 100, and 300 kDa similarly enhanced invasion over retentates from control medium. However, retentates from microconcentrators with a cutoff of 1,000 kDa failed to enhance invasion. Pretreatment in conditioned medium, followed by washing of sporozoites prior to inoculation into cultures, did not result in enhanced invasion. Moreover, when the interval between inoculation of sporozoites into cells and fixation of cultures was reduced to less than 3 h, no enhancement of invasion occurred. Conditioned medium from turkey cecal cells that were grown in the presence of ³⁵S-translabel had at least two labeled bands at 150 kDa and > 200 kDa that were absent in conditioned media from turkey kidney and baby hamster kidney cells.     

Determination of optimal planning target volume margins in patients with gynecological cancer

PurposeTo define optimal planning target volume (PTV) margins for intensity modulated radiotherapy (IMRT) ± knee-heel support (KHS) in patients treated with adjuvant radiotherapy.MethodsComputed tomography (CT) scans ± KHS of 10 patients were taken before and at 3rd and 5th week of treatment, fused and compared with initial IMRT plans.ResultsA PTV margin of 15 mm in anteroposterior (AP) and superoinferior (SI) directions and 5 mm in lateral directions were found to be adequate without any difference between ± KHS except for the SI shifts in CTV-primary at the 3rd week. Five mm margin for iliac CTV was found to be inadequate in 10–20% of patients in SI directions however when 7 mm margin was given for iliac PTV, it was found to be adequate. For presacral CTV, it was found that the most striking shift of the target volume was in the direction of AP. KHS caused significantly less volume of rectum and bladder in the treated volume.ConclusionsPTV margin of 15 mm in SI and AP, and 5 mm in lateral directions for CTV-primary were found to be adequate. A minimum of 7 mm PTV margin should be given to iliac CTV. The remarkable shifting in presacral CTV was believed to be due to the unforeseen hip malposition of obese patients. The KHS seems not to provide additional beneficial effect in decreasing the shifts both in CTV-primary and lymphatic, however it may have a beneficial effect of decreasing the OAR volume in PTV margins.