Glioblastoma (GBM), the highest-grade form of gliomas, is the most frequent and the most aggressive. Recently, a subpopulation of cells with stem cells characteristics, commonly named ''tumor-initiating stem cells'' (TISCs) or ''cancer stem cells'' (CSCs) were identified in GBM. These cells were shown to be highly resistant to chemotherapeutic drugs and to ionizing radiations. Consequently, the knowledge of the signals that regulate the functions and survival of TISCs is crucial. In our work, we describe a neurosphere-initiating cell (NS-IC) assay to quantify TISC/CSCs from patients with GBM and show that these cells are tumorigenic in vivo. We demonstrate that the intracellular signal transducer and activator of transcription STAT3 is constitutively activated by phosphorylation preferentially on serine 727 in these cells. Moreover, we demonstrate that the selective inhibition of STAT3 by the chemical compound Stattic or by siRNA STAT3 abrogates TISC/CSC proliferation and NS-IC suggesting that self-renewal of GBM ''stem-like'' cells depends on the presence of STAT3 for their maintenance. Finally, we show that inhibition of STAT3 by Stattic sensitizes TISC/CSCs to the inhibitory action of Temozolomide with a strong synergistic effect of both drugs. Overall, these results suggest that strategies focused on STAT3 inhibition are efficient at the level of ''stem-like'' cells and could be of interest for therapeutic purposes in patients with malignant GBM.

In colorectal cancer, KRAS (exons 2, 3, and 4) and NRAS (exons 2, 3, and 4) mutations are associated with resistance to antiepidermal growth factor receptor monoclonal antibodies, and BRAF mutation is a molecular marker of poor prognosis. KRAS exon 2 and BRAF-mutated colorectal cancers have well-known distinct clinicopathological characteristics. Comparison of tumors with different RAS status (exons 2, 3, and 4 of KRAS and NRAS) based on their clinicopathological characteristics has never been established. All colorectal cancer patients with RAS and BRAF testing from 2011 to 2015 were included in this observational retrospective study. Patient and tumor characteristics were collected and correlation with RAS and BRAF status was evaluated. A total of 1735 patients with colorectal cancer were included. RAS-mutated colorectal cancers (n=1002), compared with RAS wild-type colorectal cancers (n=733), were significantly associated with male gender, classical adenocarcinoma subtype, well/moderately differentiated tumors, and microsatellite stable phenotype. KRAS codon 13-mutated colorectal cancers (n=171), compared with RAS wild-type colorectal cancers, more frequently presented classical adenocarcinoma subtype and microsatellite stable phenotype. In comparison with other RAS mutations, KRAS exon 3-mutated colorectal cancers (n=23) were associated with mucinous/rare histological subtypes and, most likely to located in the rectum. KRAS exon 4-mutated colorectal cancers (n=33) were more frequently associated with mucinous/rare histological subtypes. There was no significant association between NRAS mutation (n=37) and clinicopathological features. Colorectal cancers are associated with different clinicopathological features according to the type of RAS mutation. Consequently, these particular characteristics must be considered when assessing the prognostic value of RAS status in colorectal cancer.

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Recent studies have demonstrated a relationship between the expression of stem cell-associated genes and relapses in glioblastoma (GBM), suggesting a key role for tumor stem cells in this process. Although there is increasing interest in this field, glioma stem cells (GSCs) are still poorly characterized, their ‘stemness' state and factors maintaining these properties remain largely unknown. We performed an expression profiling analysis of pluripotency in gliomaspheres derived from 11 patients. Comparative analysis between GSCs and H1 and H9 human embryonic stem cells as well as H9-derived neural stem cells indicates major variations in gene expression of pluripotency factors Nanog and OCT4, but a stable pattern for SOX2 suggesting its important function in maintaining pluripotency in GSCs. Our results also showed that all GSC lines have the capacity to commit to neural differentiation and express mesenchymal or endothelial differentiation markers. In addition, hierarchical clustering analysis revealed two groups of GSCs reflecting their heterogeneity and identified COL1A1 and IFITM1 as the most discriminating genes. Similar patterns have been observed in tumors from which gliomaspheres have been established. To determine whether this heterogeneity could be clinically relevant, the expression of both genes was further analyzed in an independent cohort of 30 patients with GBM and revealed strong correlation with overall survival. In vitro silencing of COL1A1 and IFTM1 confirmed the effect of these mesenchymal-associated genes on cell invasion and gliomasphere initiation. Our results indicate that COL1A1 and IFITM1 genes could be considered for use in stratifying patients with GBM into subgroups for risk of recurrence at diagnosis, as well as for prognostic and therapeutic evolution.

Two cases of atypical chronic myeloid leukaemia (CML) carrying the t(4;22)(q12;q11) translocation involving the breakpoint cluster region (BCR) and platelet-derived growth factor alpha receptor (PDGFRA) genes have been recently characterized. We report a third case of atypical CML with the same translocation but with a distinct breakpoint fusing BCR exon 1 with PDGFRA exon 13. The patient had a clinical presentation of CML with progressive transformation in B-cell acute lymphoblastic leukaemia. The involvement of PDGFRA led us to treat the patient with the small organic compound imatinib mesylate/STI571 (Glivec) that blocks the ATP binding site of tyrosine kinases such as Abelson, KIT and platelet-derived growth factor receptors. The patient subsequently achieved a rapid clinical and molecular response clearly demonstrating, for the first time, that Glivec is active against PDGFRA in vivo. Therefore, our study expands the list of Glivec targets and has direct biological and also clinical implications.

Summary. In this study, we used subtractive suppression hybridization to compare gene expression between an ALK‐positive anaplastic large cell lymphoma (ALCL)‐derived cell line and a clinical case of ALK‐negative ALCL. Construction and screening of a subtracted library resulted in the cloning of 29 cDNAs which were differentially expressed. Most of these clones corresponded to novel genes with unknown function (EST) or to genes implicated in the differentiation, activation or signalling of T cells such as Ran/TC4, interleukin 1‐receptor, thymosin β4, thymosin β10, moesin and cytohesin‐1. Other genes involved in the regulation of apoptosis, such as human inhibitor of apoptosis‐1 (HIAP‐1), Bax inhibitor‐1 and MCL‐1, or DNA repair, such as poly (ADP‐ribose) polymerase 1 (PARP‐1), X‐associated protein‐1 (XAP‐1), SUMO‐1 (sentrin‐1) and RanGTPase‐activating protein 1 (RanGAP‐1), were isolated. Interestingly, we found that both RNA and protein levels of human sterol isomerase (hSI), also referred to as emopamil binding protein (EBP), were overexpressed in ALK+ tumours. This protein is involved in the biosynthesis of cholesterol and may be activated by NPM‐ALK. Overall, our results suggest that all the genes described above are upregulated in the NPM‐ALK‐driven transformation process, and that moesin and cytohesin‐1 may be more specifically implicated in a signalling pathway involving PLCγ and PI3K.

Glioblastoma (GBM) is the most malignant type of primary brain tumor with a very poor prognosis. The actual standard protocol of treatment for GBM patients consists of radiotherapy and concomitant temozolomide (TMZ). However, the therapeutic efficacy of this treatment is limited due to tumor recurrence and TMZ resistance. Recently isolated, glioma stem-like cells (GSCs) are thought to represent the population of tumorigenic cells responsible for GBM resistance and recurrence following surgery and chemotherapy. In addition, MGMT (O6-methylguanine-methyltransferase) methylation is considered as one of the principal mechanisms contributing to TMZ sensitivity of GBM. In this study we have isolated GSCs from 10 adult GBM patients and investigated the relationship between MGMT methylation status and Temozolomide (TMZ) sensitivity of these lines grown either in stem-like or differentiation promoting conditions. Sensitivity to TMZ was significantly associated with MGMT methylation status in cells committed to differentiation but not in stem-like cells. In addition, patients harboring highly methylated MGMT promoters had a longer overall survival. These results reveal the importance of the differentiation process when considering the predictive value of MGMT status in GSCs for clinical response to TMZ.

Anaplastic large-cell lymphoma (ALCL) is a distinct biological and cytogenetic entity with a broad spectrum of morphological features (common type, small-cell variant and lymphohistiocytic variant). Few cell lines of ALCL are available and they all originate from primary tumors demonstrating the common type morphology (ie large-sized lymphoma cells). We established a new ALCL cell line (COST) from the peripheral blood of a patient with a small-cell variant of ALCL, at diagnosis. Cells growing in vitro and in SCID mice consisted of two populations, that is, small-and large-sized cells as seen in the patient's tumor. Both large and small malignant cells were positive for CD43/MT1 T-cell associated antigen, perforin, granzyme B and TIA-1, but negative for CD2, CD3, CD5, CD7, CD4 and CD8 antigens. Standard cytogenetic studies as well as multiplex FISH confirmed the presence of the canonical t(2;5)(p23;q35) translocation, but also revealed additional numerical and structural abnormalities. The COST cell line is the first ALCL small-cell variant cell line, and thus provides a potentially useful tool for further functional and molecular studies that should improve our understanding of the small-cell variant of ALCL, which is more frequently complicated by a leukemic phase.