Mechanisms of AXL overexpression and function in Imatinib-resistant chronic myeloid leukemia cells

AXL is a receptor tyrosine kinase of the TAM family, the function of which is poorly understood. We previously identified AXL overexpression in Imatinib (IM)-resistant CML cell lines and patients. The present study was conducted to investigate the role of AXL and the mechanisms underlying AXL overexpression in Tyrosine Kinase Inhibitor (TKI)-resistant CML cells. We present evidence that high AXL expression level is a feature of TKI-resistant CML cells and knockdown of AXL sensitized TKI-resistant cells to IM. In addition, expression of wild-type AXL but not a dominant negative form of AXL confers IM-sensitive CML cells the capacity to resist IM effect. AXL overexpression required PKCα and β and constitutive activation of ERK1/2. Accordingly, GF109203X a PKC inhibitor, U0126 a MEK1 inhibitor and PKCα/β knockdown restore sensitivity to IM while PKCα or PKCβ overexpression in CML cells promotes protection against IM-induced cell death. Finally, using luciferase promoter activity assays we established that AXL is regulated transcriptionally through the AP1 transcription factor. Our findings reveal an unexpected role of AXL in resistance to TKI in CML cells, identify the molecular mechanisms involved in its overexpression and support the notion that AXL is a new marker of resistance to TKI in CML

Anti-tumor Activity of Novel Compounds Targeting BCR-ABL, c-SRC and BCR-ABLT315I in Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a hematological stem-cell disorder characterized by the expression of the BCR-ABL fusion protein, a constitutively active tyrosine kinase that causes pathogenesis. The development of tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL oncogene has proven an effective approach to treat CML, but a non-negligible proportion of patients develop a resistance to this class of drugs. Of note, the T315I mutant of BCR-ABL is resistant to all known TKIs, with the noticeable exception of ponatinib. To address this unmet medical need, a new series of compounds was designed and tested for anti-tumor effects against BCR-ABLT315I CML. The effects of three OriBase Pharma compounds (OR1001, OR1002 and OR1003) on the kinase activity of wild-type and mutant BCR-ABL proteins, on cell proliferation and on the growth of subcutaneous xenografts of CML cells in athymic mice were investigated. In vitro, the three compounds were potent inhibitors of both ABL and c-SRC kinases and of the main mutants of ABL, including T315I. The three compounds inhibited the proliferation of cell lines expressing the wild-type and several mutated forms of BCR-ABL, including T315I. Finally, in a mouse xenograft model, OR1001, was found to significantly reduce tumor growth. These data support the potential of OR1001 as an effective therapy for the treatment of de novo and TKI-resistant patients

BCL2L10 is a predictive factor for resistance to Azacitidine in MDS and AML patients

Azacitidine is the leading compound to treat patients suffering myelodysplastic syndrome (MDS) or AML with less than 30% of blasts, but a majority of patients is primary refractory or rapidly relapses under treatment. These patients have a drastically reduced life expectancy as compared to sensitive patients. Therefore identifying predictive factors for AZA resistance is of great interest to propose alternative therapeutic strategies for non-responsive patients. We generated AZA-resistant myeloid cell line (SKM1-R) that exhibited increased expression of BCL2L10 an anti-apoptotic Bcl-2 family member. Importantly, BCL2L10 knockdown sensitized SKM1-R cells to AZA effect suggesting that increased BCL2L10 expression is linked to AZA resistance in SKM1-R. We next established in 77 MDS patients that resistance to AZA is significantly correlated with the percentage of MDS or AML cells expressing BCL2L10. In addition, we showed that the proportion of BCL2L10 positive bone marrow cells can predict overall survival in MDS or AML patients. We propose a convenient assay in which the percentage of BCL2L10 expressing cells as assessed by flow cytometry is predictive of whether or not a patient will become resistant to AZA. Therefore, systematic determination of BCL2L10 expression could be of great interest in newly diagnosed and AZA-treated MDS patients

DIFFERENTIAL EFFECTS OF PROTONTHERAPY AND PHOTONTHERAPY ON HEAD AND NECK SQUAMOUS CELL CARCINOMA (HNSCC) POST-TREATMENT AGGRESSIVENESS

International audienceHead and neck cancers, the 7 th cause of death worldwide, are currently treated with a combination of surgical resection of the primary tumor, chemotherapy and radiotherapy, depending on the disease stage. Conventional photontherapy nevertheless remains difficult to apply to tumors such as head and neck squamous cell carcinomas (HNSCC), due to the proximity of numerous organs at risk (i.e. salivary glands, esophagus, larynx). Protontherapy has been proposed to treat such sensitive tumors, due to its high precision in tumor targeting. Despite the current therapeutic strategies, the five-year overall survival rate of HNSCC patients is only 53%, with a high percentage of poor response to therapy and a high recurrence rate. Lymph node metastasis, the first sign of tumor progression, has been directly correlated to Vascular Endothelial Growth Factor-C (VEGF-C) expression levels in HNSCC and to VEGF-C-dependent tumoral lymphatic vessel development. In the present study, we investigated the hypothesis that, beside the advantage in dose deposition, protontherapy may show distinct biological properties than photontherapy (at similar doses). We thus examined several in vitro biological behaviors of HNSCC-derived cells when exposed to photons or protons, focusing on molecules with key roles in the progression and prognosis of HNSCC, such as genes/proteins involved in (lymph)angiogenesis/metastasis, inflammation, tumor cell proliferation and anti-tumor immunity, tumorigenic potential. We showed that cell proliferation decreased with the irradiation dose, both in proton and photon irradiated cells. Proton and photon irradiations increased VEGF-C and PD-L1 expression in HNSCC cells. In cells surviving multiple irradiation, key (lymph)angiogenesis and inflammation genes were down-regulated (except for VEGF-C) after protontherapy and up-regulated after photontherapy. Both irradiation types stimulated VEGF-C promoter activity via NF-kB-dependent transcriptional regulation. We conclude that cell resistance, tumor progression and lymphangiogenesis induction is less pronounced after proton irradiation than after photon irradiation. We validated these results by in vivo experiments: Photon-or proton-irradiated HNSCC-derived cells were xenografted subcutaneously into immunodeficient mice. Cells surviving to multiple irradiations by protons or photons generated tumors with higher volume, anarchic architecture and increased density of blood vessels than non-irradiated cells. Increased lymphangiogenesis and a transcriptomic analysis in favor of a more aggressive phenotype were observed in tumors generated with X irradiated cells. Detection of a denser lymphatic vessel network in relapsed tumors from patients receiving conventional X radiotherapy is consistent with these results

A New Hydroxylated Nonaprenylhydroquinone from the Mediterranean Marine Sponge Sarcotragus spinosulus

Chemical investigation of the Mediterranean sponge Sarcotragus spinosulus led to the isolation of a new hydroxylated nonaprenylhydroquinone, along with two known metabolites, hepta- and octaprenylhydroquinones. The structure of the new metabolite was assigned by extensive 1D and 2D NMR analyses and MS studies. The antileukemic effect of the three compounds towards the chronic myelogenous leukemia (CML) cells line K562 was also evaluated

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Caractérisation des mécanismes de résistances aux inhibiteurs de tyrosines kinases et nouvelles approches pharmacologiques, dans la Leucémie Myéloïde Chronique

La Leucémie Myéloïde Chronique (LMC) est un syndrome myéloprolifératif lié à une anomalie des cellules souches hématopoïétiques. Les patients atteints de LMC sont porteurs de la translocation t(9;22)(q34-q11). Cette translocation code pour une protéine chimérique, BCR-ABL, dotée d une activité tyrosine kinase constitutive responsable de cette pathologie. L Imatinib, traitement de référence, induit la mort des cellules de LMC. Malgré l efficacité de ce traitement, environ 20% des patients développe des résistances à l Imatinib. Les mécanismes moléculaires à l origine de cette résistance ne sont que partiellement identifiés. Le premier axe de mon projet de thèse a été de mettre en évidence de nouveaux mécanismes de résistance à l Imatinib. AXL est un récepteur à activité tyrosine kinase qui est dérégulé dans de nombreux cancer. Nous avons pu montrer que la surexpression d AXL dans des cellules de LMC est, en partie, responsable de la résistance à l Imatinib de ces cellules. Le second axe de mon projet a consisté à identifier de nouvelles stratégies thérapeutiques pour lutter contre ces résistances. Nos expériences montrent que le Foretinib, un inhibiteur de nombreuses kinases, est aussi efficace sur les cellules sensibles que résistantes à l Imatinib, alors qu il n a pas d effet sur des cellules saines. Cette molécule induit la catastrophe mitotique et l apoptose des cellules de LMC. En conclusion, nos résultats ont permis une meilleure compréhension des mécanismes moléculaires permettant la résistance aux inhibiteurs de BCR-ABL. En parallèle, nous avons développé une approche visant à induire la mort des cellules résistantes par un inducteur de la catastrophe mitotique.NICE-BU Sciences (060882101) / SudocSudocFranceF

Experimental Models in Neovascular Age Related Macular Degeneration

Neovascular age-related macular degeneration (vAMD), characterized by the neo-vascularization of the retro-foveolar choroid, leads to blindness within few years. This disease depends on angiogenesis mediated by the vascular endothelial growth factor A (VEGF) and to inflammation. The only available treatments consist of monthly intravitreal injections of antibodies directed against VEGF or VEGF/VEGFB/PlGF decoy receptors. Despite their relative efficacy, these drugs only delay progression to blindness and 30% of the patients are insensitive to these treatments. Hence, new therapeutic strategies are urgently needed. Experimental models of vAMD are essential to screen different innovative therapeutics. The currently used in vitro and in vivo models in ophthalmic translational research and their relevance are discussed in this review

Experimental Models in Neovascular Age Related Macular Degeneration

Neovascular age-related macular degeneration (vAMD), characterized by the neo-vascularization of the retro-foveolar choroid, leads to blindness within few years. This disease depends on angiogenesis mediated by the vascular endothelial growth factor A (VEGF) and to inflammation. The only available treatments consist of monthly intravitreal injections of antibodies directed against VEGF or VEGF/VEGFB/PlGF decoy receptors. Despite their relative efficacy, these drugs only delay progression to blindness and 30% of the patients are insensitive to these treatments. Hence, new therapeutic strategies are urgently needed. Experimental models of vAMD are essential to screen different innovative therapeutics. The currently used in vitro and in vivo models in ophthalmic translational research and their relevance are discussed in this review