Outcome of Core Binding Factor Acute Myeloid Leukemia by Receptor Tyrosine Kinase Mutation

BackgroundCore binding factor acute myeloid leukemia (CBF-AML) encodes 2 recurrent cytogenetic abnormalities, t(8;21) and inv(16), which carries an overall good prognosis. However, some patients will develop a relapse. We sought define the unfavorable group of CBF-AML by analysis of (c-KIT and FLT3-ITD) and to correlate them with treatment outcome.Patients and MethodsWe performed a prospective study of 70 patients with CBF-AML diagnosed and managed at the medical oncology department of the (National Cancer Institute), Cairo University, with analysis of c-KIT and FLT3 mutations. All patients had received “3 + 7” induction, followed by 3 to 4 courses of high-dose cytarabine consolidation. The institutional review board approved the present study.ResultsThe median patient age was 31 years (range, 18-60 years), with a male/female ratio of 4:3. Of the 70 patients, 42 (60%) had t(8;21) and 28 had inv(16) (40%). c-KIT mutations (exons 8 and 17) were detected in 10 of 52 tested patients, and FLT3-ITD was detected in 3 of 70 patients. Patients with inv(16) experienced more lymphadenopathy and splenomegaly, had a higher median initial leukocyte count. Hepatitis C antibody positivity (8 of 42) was exclusively present in patients with t(8;21). The median overall survival (OS) was 19.5 months, and the median disease-free survival (DFS) was not reached. Patients with inv(16) had near-significant (P = .07) better DFS than patients with t(8;21). c-KIT mutations had no significant effect on OS or DFS. However, reverse tyrosine kinase mutations had a negative effect on DFS but not OS (P = .04).ConclusionCBF-AML with reverse tyrosine kinase mutation conveys a worse prognosis. Hepatitis C virus antibody positivity might be associated with t(8;21) AML and inv(16) with more extramedullary disease.     

Pathology of malignant skin tumours

The skin gives rise to a diverse spectrum of malignant tumours derived from the varied constituents of the epidermis and dermis. It is possible to discuss only a few of these in this article; the more common lesions derived from the epidermal keratinoctyes (basal and squamous cell carcinomas) together with melanomas (derived mainly from epidermal melanocytes) are presented. Some rarer but biologically aggressive tumours such as Merkel cell carcinoma and angiosarcoma are also discussed. Our understanding of the molecular biology of cutaneous tumours continues to evolve rapidly particularly for melanomas and in the coming years genetic profiling of individual tumours with targeted therapy is likely to play an important role in management.     

干细胞因子受体c-Kit的研究进展

c-Kit作为酪氨酸激酶受体蛋白家族的重要成员之一,其与干细胞因子(SCF)结合作为重要的受体配基复合物通过激活下游信号分子复合物,产生强大的连锁反应,从而在细胞分化增殖等调控中发挥着举足轻重的作用。迄今为止,二聚化结构及磷酯酰肌醇3′-激酶(PI3K)、JAK-STAT等十几条激酶介导的信号通路被陆续证实与c-Kit的活化密切相关,而针对抑制c-Kit活化设计的靶向药物也陆续投入应用,与特异性的单克隆抗体一起在临床相关肿瘤的诊断及治疗等方面起到了关键性的作用。     

Kit/stem cell factor receptor-induced phosphatidylinositol 3''-kinase signalling is not required for normal development and function of interstitial cells of Cajal in mouse gastrointestinal tract

Signalling mediated by the receptor tyrosine kinase c-Kit is required for normal development of interstitial cells of Cajal (ICC). c-Kit activates several signalling pathways, including the phosphatidylinositol 3'-kinase (PI3'-kinase) pathway. The signals required for ICC development and maintenance are not well understood. Studies indicate a role for PI3'-kinase. We studied ICC function and morphology in mice homozygous for the tyrosine 719 to phenylalanine c-Kit mutation, which disrupts all PI3'-kinase binding to c-Kit. Functionally, the electrical slow waves in the jejunum and inhibitory junction potentials were normal in adult mutants. Morphologically, the distribution of ICC was not altered in mutants. There was no difference in the density of ICC in the jejunum of adults or newborns from quantitative analysis of c-Kit immunoreactivity. The number of ICC obtained in culture was the same using mutants or wild-type littermates. The density and organization of nerves in the jejunum of mutants was not affected. Deletion of c-Kit-induced PI3'-kinase signalling does not affect the function or development of ICC in the mouse. This is an important and counterintuitive result, given the role of PI3'-kinase signalling downstream of c-Kit and the role of both c-Kit and PI3'-kinase individually in ICC development.     

c-Kit mutation reduce intestinal epithelial cell proliferation and migration,but not influence intestinal permeability stimulated by lipopolysaccharide

The proto-oncogene c-kit, as a marker of interstitial cells of Cajal (ICCs) in the gastrointestinal tract, plays an important role in the ICCs. Although limited evidences showed c-kit is present in the colonic epithelium but its roles remain unclear. In the present study, we aimed to investigate the expression, location and function of c-kit in the intestinal epithelium. Immunofluorescence, western blotting, and RT-PCR were performed to detect the expression and location of c-kit in the intestinal mucosa of WT mice. We investigated intestinal epithelial proliferation and migration in vivo by performing 5-Bromodeoxyuridine (BrdU) incorporation and Ki-67 staining in WT and Wads ^m/m mice. An Ussing chamber with fluorescein-isothiocyanate dextran 4000 was used to detect the transepithelial electric resistance (TER), short circuit current (ISC) and permeability across ex vivo colon segments under control and endotoxaemia conditions. We demonstrated that c-kit was located and expressed in the gut crypt compartment in WT mice, which was demonstrated in the c-kit mutant mice (Wads ^m/m). In addition, both the number of proliferating cells and the percentage of the distance migrated were lower in the Wads ^m/m mice than those in the WT mice. Moreover, the intestinal permeability, TER and tight junction were unaltered in the Wads ^m/m mice under endotoxic conditions compared with those in both the control condition and the WT mice. Altogether, these observations imply that the expression of c-kit in the colonic epithelium is involved in the proliferation and permeability of the colonic epithelium.     

Signal transduction of c-Kit receptor tyrosine kinase in CHRF myeloid leukemia cells

Purpose The tyrosine kinase receptor c-Kit (stem cell factor receptor, CD117) is a potential target for signal transduction therapy in different cancers. In this study we investigated c-Kit in CHRF cells, a megakaryoblastic cell line of Acute Myeloid Leukemia (FAB M7).Materials and methods We characterized the interactions between c-Kit and PI 3-kinase (p85) after stimulation with SCF (stem cell factor) as well as the regulation of SHP-1 and SHP-2 associated with Kit in this cell line.Results Stimulation with SCF leads to a significant increase in interaction between Kit and p85 as well as in receptor associated PI 3-kinase activity. Interestingly, using different kinds of substances (AG 1295, CGP 53716) to inhibit the tyrosine kinase activity of c-Kit blocked activation of c-Kit, but the association of p85 still increased after SCF stimulation even when the tyrosine kinase activity of the receptor was completely blocked. In contrast, the other known interaction partners of c-Kit, SHP-1 and SHP-2, exhibited a basal association with c-Kit and no change of the association could be detected after stimulation of CHRF cells with SCF or treatment with the kinase inhibitors.Conclusions Therefore, we suggest that association of p85, SHP-1, and SHP-2 to c-Kit in CHRF cells can, at least in part, occur in a c-Kit kinase-activity independent manner. In contrast, the kinase activity of c-Kit is necessary for the activation of receptor-associated PI 3-kinase.     

Inhibition of c-Kit signaling is associated with reduced heat and cold pain sensitivity in humans

The tyrosine kinase receptor c-Kit is critically involved in the modulation of nociceptive sensitivity in mice. Ablation of the c-Kit gene results in hyposensitivity to thermal pain, whereas activation of c-Kit produces hypersensitivity to noxious heat, without altering sensitivity to innocuous mechanical stimuli. In this study, we investigated the role of c-Kit signaling in human pain perception. We hypothesized that subjects treated with Imatinib or Nilotinib, potent inhibitors of tyrosine kinases including c-Kit but also Abl1, PDFGFRα, and PDFGFRβ, that are used to treat chronic myeloid leukemia (CML), would experience changes in thermal pain sensitivity. We examined 31 asymptomatic CML patients (14 male and 17 female) receiving Imatinib/Nilotinib treatment and compared them to 39 age- and sex-matched healthy controls (12 male and 27 female). We used cutaneous heat and cold stimulation to test normal and noxious thermal sensitivity, and a grating orientation task to assess tactile acuity. Thermal pain thresholds were significantly increased in the Imatinib/Nilotinib-treated group, whereas innocuous thermal and tactile thresholds were unchanged compared to those in the control group. In conclusion, our findings suggest that the biological effects of c-Kit inhibition are comparable in mice and humans in that c-Kit activity is required to regulate thermal pain sensitivity but does not affect innocuous thermal and mechanical sensation. The effect on experimental heat pain observed in our study is comparable to those of several common analgesics; thus modulation of the c-Kit pathway can be used to specifically modulate noxious heat and cold sensitivity in humans.     

Frequent c-Kit gene mutations not only in gastrointestinal stromal tumors but also in interstitial cells of Cajal in surrounding normal mucosa

Gastrointestinal stromal tumors (GISTs) are thought to originate from mesenchymal stem cells that differentiate toward the interstitial cells of Cajal (ICCs). The frequent occurrence of activating mutations involving exon 11 of c-Kit gene in sporadic GISTs indicates an important role in genesis of this tumor type. In the present study we examined c-Kit gene mutations in a series of GISTs and also in ICCs of surrounding normal tissues. Samples from 18 patients were monitored immunohistochemically for c-Kit expression and microdissected for sequencing analysis of exons 9, 11, 13, and 17 of the c-Kit gene. It was revealed to be mutated in exon 11 or adjacent introns in 9 out of the total of 18 (50.0%) GISTs. In 6 (33.3%) cases, mutations in ICCs were also detected in the same exon. With stomach GISTs, 8 of 16 (50.0%) cases harbored mutations and 4 had mutations in background ICCs (25.0%). In contrast counterpart ICCs in gastric cancer cases harbored no c-Kit gene mutations (0 out of 24=0%) (P<0.02). ICCs undergoing c-Kit mutation as a possible early initiation step in GIST tumorigenesis may thus have pre-neoplastic potential.     

Distinct progenitors for B-1 and B-2 cells are present in adult mouse spleen

Recent studies by Dorshkind, Yoder, and colleagues show that embryonic (E9) B-cell progenitors located in the yolk sac and intraembryonic hemogenic endothelium before the initiation of circulation give rise to B-1 and marginal zone B cells but do not give rise to B-2 cells. In studies here, we confirm and extend these findings by showing that distinct progenitors for B-1 and B-2 cells are present in the adult spleen. Furthermore, we show that the splenic B-cell progenitor population (lin(-)CD19(+)/B220(lo/-)/CD43(-)) that gives rise to B-1 cells is likely to be heterogeneous because, in some recipients, it also gives rise to B cells expressing the marginal zone phenotype (B220(hi)IgM(hi)IgD(lo)CD21(hi)) and to some (CD19(-)CD5(hi)) T cells. In addition to the well-known function differences between B-1 and B-2, our studies demonstrate that substantial developmental differences separate these B-cell lineages. Thus, consistent with the known dependence of B-2 development on IL-7, all B-2 progenitors express IL-7R. However, >30% of the B-1 progenitors do not express this marker, enabling the known IL-7 independent development of B-1 cells in IL-7(-/-) mice. In addition, marker expression on cells in the early stages of the B-2 development pathway (CD19(-)/c-Kit(lo/-)/Sca-1(lo/-)) in adult bone marrow distinguish it from the early stages of B-1 development (CD19(hi)/c-Kit(+)/Sca-1(+)), which occur constitutively in neonates. In adults, in vivo inflammatory stimulation (LPS) triggers B-1 progenitors in spleen to expand and initiate development along this B-1 developmental pathway.