The impact of Ad.mda-7 on the survival of renal cell carcinoma lines (RCC), primary renal epithelial cells, glioblastoma multiforme lines (GBM), and primary rodent astrocytes is unknown. The present studies examine whether the GST fusion protein, GST-MDA-7, and the adenovirus, Ad.mda-7, altered the growth and survival of the A498 and UOK121N RCC lines or radiosensitized GBM, respectively. Due to previous findings that the RCC lines, but not primary renal epithelial cells, were resistant to type 5 adenoviral infection, we used purified GST-MDA-7 protein to show that GST-MDA-7, but not GST, caused a dose-dependent reduction in A498 and UOK121N proliferation but not that of primary renal epithelial cells. Free radical species, generated by clinically relevant concentrations of arsenic trioxide, synergized with subnanomolar concentrations of GST-MDA-7 to inhibit the proliferation, viability, and long-term survival of RCC. We also found that MDA-7 (IL-24), when expressed via a recombinant replication defective adenovirus, Ad.mda-7, exerted anti-proliferative effects on GBM cells, an effect found to be enhanced in a greater than additive fashion when combined with ionizing radiation. These findings argue that MDA-7, in combination with agents that generate free radicals, such as arsenic trioxide and ionizing radiation, may have potential in the treatment of RCC and GBM. Geldanamycins are currently being used in a number of clinical trials in different tumor cell types, such as hepatocellular carcinoma (HCC), targeting the inhibition of the heat shock protein and molecular chaperone Hsp90. Previous studies have demonstrated that geldanamycins have dose limiting toxicity in vivo due to their actions in promoting normal liver dysfunction. These studies show that the geldanamycin derivative, 17-allylamino-17-demethoxygeldanamycin (17-AAG), interacts with the secondary bile acid, deoxycholic acid (DCA), to kill primary rat hepatocytes and HuH7 human hepatoma cells. An effect abolished by the addition of the ROS-quenchers, NAC and Trolox. Collectively, these findings argue that geldanamycins may not be a viable therapy for HCC treatment and that 17-AAG toxicity in primary hepatocytes may be, at least upon initial drug exposure, due to ROS generation and mechanisms independent of Hsp9O inhibition and the down-regulation of "classical" Hsp90 client proteins.

L'interleukine-6 (IL-6) exerce des propriétés biologiques multiples telles que l'activation des cellules immunocompétentes, l'activation de la réponse inflammatoire et l'hématopoïèse. Produite également par les cellules tumorales, l'IL-6 impacte la prolifération, la différenciation et la survie de ces dernières. L'IL-6 représente donc depuis plusieurs années une cible thérapeutique pertinente. Dans la première partie de ce travail, nous avons exploré une nouvelle piste potentielle pour bloquer l'activité biologique de l'IL-6, en utilisant un antagoniste naturel que notre équipe a identifié dans plusieurs lignées d'adénocarcinomes du rein, à savoir la molécule tronquée tIL-6. Suite à l'évaluation comparée de deux systèmes d'expression (E. coli versus CHO), nous avons retenu les cellules CHO comme source de production de fractions enrichies en tIL-6 par chromatographie de gel d'exclusion. Disposant d'un panel d'adénocarcinomes de rein (ACHN, Caki1, CLB CHA, CLB VER) et d'une lignée érythroleucémique (TF1), l'activité fonctionnelle de tIL-6 in vitro a été étudiée sur (1) la signalisation IL-6 induite, (2) la prolifération cellulaire IL-6 induite, la survie cellulaire et (4) la modulation de l'expression de protéines relevantes de l'apoptose. La molécule tIL-6 bloque la phosphorylation de la tyrosine Tyr705 de STAT3, qui est un des éléments clés de la voie de signalisation de l'IL-6. Nous rapportons également une autre observation nouvelle indiquant que tIL-6 exerce un effet pro-apoptotique sur certaines lignées RCC. Dans la seconde partie de notre étude, l'impact d'un Ac Mo anti IL-6 dans la réversion de la résistance aux cytotoxiques ou à la radiothérapie a été étudié. Nos résultats démontrent que la voie IL-6 ne constituerait pas un mécanisme majeur de résistance / Interleukin-6 (IL-6) plays numerous physiological roles including haematopoiesis, immune response and inflammation, but also plays a role in modulating cell growth, differentiation and survival of tumors cells. The first goal of the present study was to investigate on the potential role of the truncated protein IL-6 (tIL-6) encoded by the spliced IL-6 mRNA discovered in renal carcinoma cells (RCC). The R&D program was designed based on an industrial approach, aiming at reaching the decision stage to enter or not into preclinical development. Firstly two different expression systems were investigated (E. coli versus CHO cell line). The mammalian expression system was selected as the protein source since a recombinant glycosylated tIL-6 with a molecular weight similar to the predicted natural molecule was obtained from enriched fractions following size exclusion chromatography. Secondly by using a cell line panel including renal carcinoma cells (ACHN, Caki-1, CLB CHA, CLB-VER ) and an erythroleucemic cell line (TF1), in vitro tIL-6 functional activity were analyzed on (1) IL-6 induced signaling, (2) IL-6 induced cell proliferation, (3) on cell survival and also (4) on expression of specific set of proteins involved in apoptosis pathways. The truncated IL-6 was found inhibit IL-6 induced STAT3 Tyr705 and to induce apoptosis in some RCC cell lines which could be depending on IL-6 expression. Understanding more precisely the role of natural truncated IL-6 and its impact in cell tumour growth control will be a major issue in the development of innovative approach to antagonize directly or not IL6. The second goal of the present study was to investigate on reversing resistance of cancer cell lines to cytotoxics or ionizing radiations through the use of a monoclonal antibody directed against IL-6. Our data support the fact that IL-6 is not the preponderant actor of cell resistance to cytotoxics and ionizing radiations, which seems to be regulated by a complex network of proteins