Cell proliferation and inhibition of apoptosis are related to c-Kit activation in leukaemic lymphoblasts

CD117 expression in canine ovarian tumours

Canine ovarian cancer poses a significant diagnostic and therapeutic challenge. The heterogeneous nature of ovarian tumours makes accurate histological identification difficult, whilst treatment is limited to surgical excision. The tyrosine kinase receptor CD117 is neo-expressed in many tumours and represents a potential diagnostic and prognostic biomarker and therapeutic target. This study aimed to establish if CD117 is neoexpressed in canine ovarian tumours. Immunohistochemistry was employed to assess expression of CD117 in 29 canine ovarian tumour samples. CD117 labelling was assessed with a semiquantitative immunoreactivity score, and the location of labelling was recorded as membranous, focal cytoplasmic or diffuse cytoplasmic. Histological morphology was assessed and used to assign subgroups based on growth pattern. Cytokeratin 7 labelling was used to indicate the tumour type as epithelial or sex-cord stromal in origin. Mitotic index, percentage of necrosis and vascular invasion were also assessed and evaluated for association with CD117 expression. Overall, 81% of ovarian tumours neoexpressed CD117 and normal ovarian tissue did not express CD117. Positive immunolabelling was seen in a subset of cells in both ovarian carcinomas (n = 20) and ovarian granulosa cell tumours (n = 3). There was no association between CD117 expression and patient age, histological subtype, mitotic index, percentage of necrosis or vascular invasion. This is the largest study to identify the expression of CD117 in canine ovarian tumours, but further research is needed to elucidate its prognostic and therapeutic value.

Transformation of primary murine peritoneal mast cells by constitutive KIT activation is accompanied by loss of Cdkn2a/Arf expression

Mast cells (MCs) are immune cells of the myeloid lineage distributed in tissues throughout the body. Phenotypically, they are a heterogeneous group characterized by different protease repertoires stored in secretory granules and differential presence of receptors. To adequately address aspects of MC biology either primary MCs isolated from human or mouse tissue or different human MC lines, like HMC-1.1 and -1.2, or rodent MC lines like L138.8A or RBL-2H3 are frequently used. Nevertheless, cellular systems to study MC functions are very limited. We have generated a murine connective tissue-like MC line, termed PMC-306, derived from primary peritoneal MCs (PMCs), which spontaneously transformed. We analyzed PMC-306 cells regarding MC surface receptor expression, effector functions and respective signaling pathways, and found that the cells reacted very similar to primary wildtype (WT) PMCs. In this regard, stimulation with MAS-related G-protein-coupled receptor member B2 (MRGPRB2) ligands induced respective signaling and effector functions. Furthermore, PMC-306 cells revealed significantly accelerated cell cycle progression, which however was still dependent on interleukine 3 (IL-3) and stem cell factor (SCF). Phenotypically, PMC-306 cells adopted an immature connective tissue-like MCs appearance. The observation of cellular transformation was accompanied by the loss of Cdkn2a and Arf expression, which are both described as critical cell cycle regulators. The loss of Cdkn2a and Arf expression could be mimicked in primary bone marrow-derived mast cells (BMMCs) by sustained SCF supplementation strongly arguing for an involvement of KIT activation in the regulation of Cdkn2a/Arf expression. Hence, this new cell line might be a useful tool to study further aspects of PMC function and to address tumorigenic processes associated with MC leukemia.

Identification of Thiazolo[5,4-b]pyridine Derivatives as c-KIT Inhibitors for Overcoming Imatinib Resistance

c-KIT is a promising therapeutic target against gastrointestinal stromal tumor (GIST). In order to identify novel c-KIT inhibitors capable of overcoming imatinib resistance, we synthesized 31 novel thiazolo[5,4-b]pyridine derivatives and performed SAR studies. We observed that, among these substances, 6r is capable of inhibiting significantly c-KIT and suppressing substantially proliferation of GIST-T1 cancer cells. It is of note that 6r is potent against a c-KIT V560G/D816V double mutant resistant to imatinib. Compared with sunitinib, 6r possesses higher differential cytotoxicity on c-KIT D816V Ba/F3 cells relative to parental Ba/F3 cells. In addition, kinase panel profiling reveals that 6r has reasonable kinase selectivity. It was found that 6r remarkably attenuates proliferation of cancer cells via blockade of c-KIT downstream signaling, and induction of apoptosis and cell cycle arrest. Furthermore, 6r notably suppresses migration and invasion, as well as anchorage-independent growth of GIST-T1 cells. This study provides useful SAR information for the design of novel c-KIT inhibitors overcoming imatinib-resistance.

Global expression profiling of CD10 + /CD19 + pre-B lymphoblasts from Hispanic B-ALL patients correlates with comparative TARGET database analysis

Mexico City has one of the highest incidences of acute lymphoblastic leukemia (ALL) globally, with patients showing low survival, and high relapse rates. To gain more insight into the molecular features of B-ALL in Mexican children, we isolated CD10 + /CD19 + precursor B lymphoblasts from four bone marrow and nine peripheral blood samples of B-ALL patients using a fluorescence-activated cell sorting protocol. The global gene expression profile (BM vs PB) revealed 136 differentially expressed genes; 62 were upregulated (45.6%) and 74 were downregulated (54.4%). Pearson's correlation coefficient was calculated to determine the similarity between pre-B lymphoblast populations. We selected 26 highly significant genes and validated 21 by RT-qPCR (CNN3, STON2, CALN1, RUNX2, GADD45A, CDC45, CDC20, PLK1, AIDA, HCK, LY86, GPR65, PIK3CG, LILRB2, IL7R, TCL1A, DOCK1, HIST1H3G, PTPN14, CD72, and NT5E). The gene set enrichment analysis of the total expression matrix and the ingenuity pathway analysis of the 136 differentially expressed genes showed that the cell cycle was altered in the bone marrow with four overexpressed genes (PLK1, CDC20, CDC45, and GADD45A) and a low expression of IL7R and PIK3CG, which are involved in B cell differentiation. A comparative bioinformatics analysis of 15 bone marrow and 10 peripheral blood samples from Hispanic B-ALL patients collected by the TARGET program, corroborated the genes observed, except for PIK3CG. We conclude the Mexican and the Hispanic B-ALL patients studied present common driver alterations and histotype-specific mutations that could facilitate risk stratification and diagnostic accuracy and serve as potential therapeutic targets.

Promoter methylation and expression of SOCS3 affect the clinical outcome of pediatric acute lymphoblastic leukemia by JAK/STAT pathway

Suppressor of cytokine signaling 3 (SOCS3) has been characterized as one of the most crucial negative regulator in the JAK2/STAT3 signaling pathway. However, there are few studies on the relationship between SOCS3 and pediatric acute lymphoblastic leukemia (ALL). This study analyzes the influence of SOCS3 expression on the risk and the progression of pediatric ALL and the underlying mechanism. The levels of SOCS3, p-JAK2, p-STAT3, SOCS3 methylation, CD4+CD25+CD127lowTreg were detected by PCR, laser confocal microscopy, western blot, bisulfite sequencing and flow cytometry at different progression of ALL. We found that the SOCS3 expression level at initial diagnosis (DG) of ALL patients was significantly lower than that of healthy controls (HC), while the expression of SOCS3 methylation was opposite. The expression of SOCS3 and SOCS3 methylation were returned to normal in the complete remission (CR) stage, and there were no difference between resistance, relapse and initial diagnosis. The expression of SOCS3 decreased and weakened the inhibition of pSTAT3 expression in DG, resistance and relapse groups. The levels of Treg cells in ALL children were significantly higher than those in the HC children. There was a positive correlation between the expression level of STAT3 and the expression level of Treg cells in children with ALL, while that was negatively correlated with the expression levels of Treg cells. Compared with high-level of SOCS3, the low-level of SOCS3 patients had more high risk factors, as higher WBC counts, LDH level and much more poor prognostic genes. SOCS3 methylation leads to low-expression of SOCS3, which can lead to continuous activation of JAK/STAT3 and increased expression of Treg cells, which in turn affects the anti-tumor immunological effect of the body. Taken together, our data show that monitoring the level of SOCS3 can contribute to the understanding of the state of illness and evaluate the risk of progression of ALL.

Dasatinib as an investigational drug for the treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia in adults

INTRODUCTION

Acute lymphoblastic leukemia (ALL) with BCR-ABL1 translocation is an aggressive malignancy that is usually treated with intensive chemotherapy with the possibility of allogeneic stem cell transplantation. The encoded fusion protein may be important for leukemogenesis; clinical studies show that dasatinib has an antileukemic effect in combination with steroids alone or intensive chemotherapy. Areas covered: Relevant publications were identified through literature searches (the used terms being acute lymphoblastic leukemia plus dasatinib) in the PubMed database. We searched for original articles and reviews describing the pharmacology and clinical use of dasatinib in ALL with BCR-ABL1. The mechanism of action, pharmacology and clinical study findings are examined. Expert opinion: Dasatinib is associated with a high complete remission rate in ALL when used alone and in combination with steroids or intensive chemotherapy. However, mutations at T315 and F317 are associated with dasatinib resistance. Overall toxicity has been acceptable in these studies and no unexpected toxicity was observed. It is not known whether the antileukemic effect of dasatinib differs between subsets of BCR-ABL1⁺ patients or is attributed to inhibition of the fusion protein alone, or a combined effect on several kinases, and whether dasatinib-containing combination treatment should be preferred in these patients instead of other emerging strategies, e.g. monoclonal antibodies.

Proteomic Profiling of HL-60 Cells during ATRA-Induced Differentiation

Acute promyelocytic leukemia, a form of acute myeloid leukemia, is characterized by cell differentiation arrest at the promyelocyte stage. Current therapeutic options include administration of all trans-retinoic acid (ATRA), but this treatment produces many side effects. ATRA is known to induce differentiation of leukemic cells into granulocytes, but the mechanism of this process is poorly studied. We performed comparative proteomic profiling of HL-60 promyelocytic cells at different stages of ATRA-induced differentiation to identify differentially expressed proteins by high-resolution mass spectrometry and relative quantitative analysis without isotope labels. A total of 1162 proteins identified by at least two unique peptides were analyzed, among them 46 and 172 differentially expressed proteins were identified in the nuclear and cytosol fractions, respectively. These differentially expressed proteins can represent candidate targets for combination therapy of acute promyelocytic leukemia.