Measurement of KIT ligand/stem cell factor: clinical and biochemical significance

Pathway analysis of spermidine anti-oxidative stress and inducing autophagy in granulosa cells of Sichuan white geese

Spermidine, a natural polyamine, has been proven antioxidant function, but its pathway and mechanism of action remain unclear. Based on the oxidative stress model by 3-nitropropionic acid (3-NPA), the study explored the pathways by spermidine to rescue oxidative stress via autophagic process in goose granulosa cells by RNA-seq and RNA interference. In transcriptional regulation, in addition to KEGG pathways related to cell proliferation and differentiation, lots of KEGG pathways associated with inflammation, metabolism, and signaling were also significantly enriched in 3-NPA vs. 3-NPA + spermidine treatments. Six key genes (JUN, CD44, KITLG, RND2, BMP4 and KALRN) involved in spermidine-mediated anti-oxidative stress were screened. Furthermore, the experimental results showed that spermidine (80 μmol/L) significantly increased autophagic gene expression in goose granulosa cells, while EP300-siRNA or MAP1S-siRNA also significantly increased autophagic process. The autophagic gene expressions were no difference between EP300-siRNA and EP300-siRNA + spermidine treatments, although spermidine significantly increased autophagic process of granulosa cells compared to MAP1S-siRNA alone. In addition, inhibition of mTOR pathway significantly increased autophagic gene expression, which was further enhanced by spermidine in combined with mTOR inhibitor. These results suggest that spermidine can alleviate oxidative stress by inducing autophagy regulated by EP300, MAP1S and mTOR as well as regulating other independent gene expressions in goose granulosa cells.

KITLG Promotes Glomerular Endothelial Cell Injury in Diabetic Nephropathy by an Autocrine Effect

Diabetic nephropathy (DN) is an increasing threat to human health. The impact of hyperglycemia or its metabolites, advanced glycation end-products (AGEs), on glomerular endothelial cells (GECs) and their pathophysiologic mechanisms are not well explored. Our results reveal that AGEs increased the expression and secretion of the KIT ligand (KITLG) in GECs. Both AGEs and KITLG promoted endothelial-to-mesenchymal transition (EndoMT) in GECs and further increased the permeability of GECs through the AKT/extracellular-signal-regulated kinase pathway. Inhibition of KITLG’s effects by imatinib prevented AGE-medicated EndoMT in GECs, supporting the belief that KITLG is a critical factor for GEC injury. We found higher KITLG levels in the GECs and urine of db/db mice compared with db/m mice, and urinary KITLG levels were positively correlated with the urinary albumin-to-creatinine ratio (ACR). Furthermore, type 2 diabetic patients had higher urinary KITLG levels than normal individuals, as well as urinary KITLG levels that were positively correlated with urinary ACR and negatively correlated with the estimated glomerular filtration rate. KITLG plays a pathogenic role in GEC injury in DN and might act as a biomarker of DN progression.

Curative Effect and Mechanism of Guiren Runchang Granules on Morphine-Induced Slow Transit Constipation in Mice

Recent studies have identified the curative effects of traditional Chinese medicine for constipation. The mechanism of action of Guiren Runchang granules (GRGs) in the treatment of slow transit constipation (STC) was evaluated in this study. Here, we assessed the efficacy of GRG by comparing the differences in fecal characteristics, stool weight, and intestinal transit rate (ITR) among 6 groups (n = 12/group), which were administered three concentrations of GRG, mosapride, and saline. The influence of GRG on the SCF/c-kit pathway, AQP4, and serum motilin of mice was assessed through ELISA, western blot, and immunohistochemical analysis. The dry weight of mouse feces at 24 hr and ITR in the MD (medium-dose GRG; 9.44 g/kg/d) and HD (high-dose GRG; 18.88 g/kg/d) groups was higher than that in the MC (model control) group. The serum motilin of morphine-induced mice level was lower in the MC group than in the NC (normal control) group, and this condition was improved in the HD group. The HD group expressed significantly higher levels of SCF and c-kit protein but lower levels of AQP4 and simultaneously presented more SCF-positive and c-kit-positive cells. However, no differences in the serum SCF level were found among the six groups. Certain concentrations of GRG are effective in STC mice, the potential mechanism of which may be associated with repairing the SCF/c-kit pathway and reducing the expression of AQP4 in the colon. GRG improved the serum motilin level but had no influence on the serum SCF level.

Bone Marrow and Peripheral Blood C-kit Ligand Concentrations in Patients with Thrombocytosis and Thrombocytopenia

C-kit ligand (stem cell factor, SCF) is a hematopoietic growth factor with diverse effects. It has stimulatory effects on megakaryocytopoiesis acting in synergism with interleukin-3 (IL-3), thrombopoietin (TPO) and granulocyte-macrophage colony stimulating factor (GM-CSF). The relationship between SCF and megakaryocytopoiesis, especially the correlations between blood and bone marrow SCF levels have been not clearly established in the literature. We therefore, investigated peripheral and bone marrow SCF levels in patients with thrombocytosis and thrombocytopenia. Subjects were divided into three groups: those with (i) thrombocytopenia, (ii) thrombocytosis and (iii) healthy adults as controls. When the three groups were compared, the mean peripheral blood SCF level of the thrombocytosis group (2149±197) was significantly higher than the thrombocytopenia (1586±178) and normal control groups (1371±68; p<0.05) and the bone marrow SCF level was higher (2694±267) than the thrombocytopenia group (1700±182; p<0.05). In the correlation analysis, considering all the groups together the bone marrow and peripheral blood SCF concentrations were positively and significantly correlated (p<0.01; r=0.93). Correlations between platelet number and both bone marrow SCF concentration (p<0.01; r=0.51) and peripheral blood concentrations (p<0.01; r=0.40) were also shown. Our results indicate that SCF is operative in the pathological megakaryopoiesis of clonal origin and reactive thrombocytosis both in the local bone marrow microenvironment and the peripheral circulating blood. We feel that further studies on the platelet-SCF relationship and SCF levels in different disease states are required.

Role of KIT-Positive Interstitial Cells of Cajal in the Urinary Bladder and Possible Therapeutic Target for Overactive Bladder

In the gastrointestinal tract, interstitial cells of Cajal (ICCs) act as pacemaker cells to generate slow wave activity. Interstitial cells that resemble ICCs in the gastrointestinal tract have been identified by their morphological characteristics in the bladder. KIT is used as an identification marker of ICCs. ICCs in the bladder may be involved in signal transmission between smooth muscle bundles, from efferent nerves to smooth muscles, and from the urothelium to afferent nerves. Recent research has suggested that not only the disturbance of spontaneous contractility caused by altered detrusor ICC signal transduction between nerves and smooth muscle cells but also the disturbance of signal transduction between urothelial cells and sensory nerves via suburothelial ICC may induce overactive bladder (OAB). Recent reports have suggested that KIT is not only a detection marker of these cells, but also may play a crucial role in the control of bladder function. Research into the effect of a c-kit receptor inhibitor, imatinib mesylate, on bladder function implies that KIT-positive ICCs may be therapeutic target cells to reduce bladder overactivity and that the blockage of c-kit receptor may offer a new therapeutic strategy for OAB treatment, although further study will be needed.

Transforming growth factor-beta binding receptor endoglin (CD105) expression in esophageal cancer and in adjacent nontumorous esophagus as prognostic predictor of recurrence

BACKGROUND

We hypothesized that the potent neovascularization marker endoglin (CD105), by differentially highlighting a subset of microvessels (MV) in esophageal cancer (EC), could provide better prognostic/therapeutic information than the panendothelial marker CD34, which also highlights MV.

METHODS

Endoglin messenger ribonucleic acid (mRNA) expression in normal, malignant, and adjacent nontumorous esophagus tissue was quantified by real-time reverse-transcription polymerase chain reaction (RT-PCR). Sections of formalin-fixed, paraffin-embedded tissues were analyzed immunohistochemically for CD105 and CD34. MV density was counted following a standard protocol. Circulating soluble endoglin levels were determined in patient and control sera, and compared with clinical outcome.

RESULTS

CD105 mRNA was upregulated by a median factor of 2.89 in ECs versus controls. In 28% of patients, CD105 mRNA was upregulated by a median factor of 2.65 in adjacent non-tumorous versus normal tissue. In tumor tissues, CD105 was stained negatively or positively only in a subset of MV. CD34 always showed positive extensive MV staining. In adjacent nontumorous esophagus, CD105 rarely showed diffuse MV staining, while CD34 stained blood-vessel endothelial cells in all non-neoplastic tissue. CD105 expression was high in residual highly dysplastic Barrett's-type mucosa associated with some adenocarcinomas. No statistically significant difference in endoglin serum levels appeared between patients and normal subjects. Correlation with clinicopathological data showed higher intra-tumor MV-CD105+ scores at more-advanced clinical stages. High-scoring MV-CD105+ patients had significantly shorter disease-free and overall survival; MV-CD34+ density was not survival related. Diffuse CD105 expression in adjacent nontumorous esophagus predicted poorer disease-free and overall survival.

CONCLUSIONS

Our findings could help identify EC patients who may benefit from targeted anti-angiogenic therapies.

Effect of human WEE1 and stem cell factor on human CD34+ umbilical cord blood cell damage induced by chemotherapeutic agents

Myelosuppression is one of the major side-effects of most anticancer drugs. To achieve myeloprotection, one bicistronic vector encoding anti-apoptotic protein human WEE1 (WEE1Hu) and proliferation-stimulating stem cell factor (SCF) was generated. In this study, we selected human umbilical cord blood CD34+ cells as the in vitro model in an attempt to investigate whether WEE1Hu, rather than conventional drug-resistant genes, can be introduced to rescue cells from the damage by chemotherapeutic agents such as cisplatin, adriamycin, mitomycin-c and 5-fluorouracil. Cell viability and cytotoxicity assay, colony-forming units in culture assay and externalization of phospholipid phosphatidylserine analysis showed that the expression of WEE1Hu and SCF in CD34+ cells provided the cells with some protection. These findings suggest that the expression of WEE1Hu and SCF might rescue CD34+ cells from chemotherapy-induced myelosuppression.

Neuroprotection by stem cell factor in rat cortical neurons involves AKT and NFκB

Stem cell factor (SCF) is a highly expressed cytokine in the central nervous system. In the present study, we demonstrate a neuroprotective role for SCF and its tyrosine kinase receptor, c-kit, against camptothecin-induced apoptosis and glutamate excitotoxicity in rat cortical neurons. This protection was blocked by pharmacological or molecular inhibition of either the MEK/ERK or PI3K/Akt signaling pathways. The importance of these pathways was further confirmed by the activation of both ERK, in a MEK-dependent manner, and Akt, via PI3K. Activation of Akt increased the binding of the p50 and p65 subunits of NFkappaB, which was also important for neuroprotection. Akt inhibition prevented NFkappaB binding, suggesting a role for Akt in SCF-induced NFkappaB. Pharmacological inhibition of NFkappaB or dominant negative IkappaB also prevented neuroprotection by SCF. SCF up-regulated the anti-apoptotic genes, bcl-2 and bcl-xL in an NFkappaB-dependent manner. Together, these findings demonstrate a neuroprotective role for SCF in cortical neurons, an effect that was mediated by Akt and ERK, as well as NFkappaB-mediated gene transcription. SCF represents a novel therapeutic target in the treatment of neurodegenerative disease.

c-Kit receptor (CD117) expression on myeloblasts and white blood cell counts in acute myeloid leukemia

BACKGROUND

The c-Kit receptor is considered to play a crucial role in hematopoiesis. Induction of mobilization of hematopoietic cells in the bone marrow requires cooperative signaling through c-Kit and c-Kit ligand pathway, and these interactions are important in the retention of stem cells within the bone marrow. Therefore, we analyzed c-Kit density on the leukemic myeloblasts of patients with acute myeloid leukemia (AML) in relation to white blood cell count (WBC) in the peripheral blood.

METHODS

Bone marrow aspirates collected from patients with AML and bone marrow aspirates and leukapheresis products after granulocyte colony-stimulating factor blood mobilization from adult volunteers were studied. To determine the level of c-Kit receptor expression, we applied quantitative (relative fluorescence intensity and antibody binding per cell) cytometric methods.

RESULTS

Our data showed negative correlation between the level of c-Kit expression intensity on myeloblasts and the number of leukocytes in blood of AML patients. The c-Kit receptor density on myeloblasts in patients with low WBC was significantly stronger than that on myeloblasts in patients with high WBC. In the latter patient group, the density c-Kit receptor on myeloblasts was similar to that on CD34(+) cells in mobilized peripheral blood.

CONCLUSIONS

The obtained data suggest an involvement of c-Kit receptor in the regulation of leukemic myeloblasts egress to the peripheral blood.

Decreased expression of stem cell factor in esophageal and gastric mucosa after esophagogastric anastomosis for cancer: potential relevance to motility

BACKGROUND

Esophageal replacement with gastric tube is a well-established reconstruction of the alimentary tract after esophagectomy in cancer patients. The resulting molecular events in the transposed gastric tube and residual esophagus have yet to be investigated. Stem cell factor (SCF) was recently shown to be critical for signaling in gastrointestinal motility. SCF expression is here correlated with changes in mucosal morphology, acid and biliary reflux, and motility in the residual esophagus and gastric tube.

METHODS

Thirteen patients surgically resected for squamous esophageal carcinoma with gastric tube replaced by esophagogastric anastomosis underwent upper endoscopy, esophageal manometry, 24-hour pH monitoring, and bile reflux detection. Esophageal and gastric mucosa samples were examined for SCF expression by immunohistochemical and semiquantitative reverse transcriptase-polymerase chain reaction analysis and for SCF serum levels by enzyme-linked immunosorbent assay.

RESULTS

All patients showed severe residual esophagus hypoperistalsis and no gastric tube motor activity. The 24-hour pH monitoring was positive in most; 24-hour bile detection was mostly negative. SCF levels in the residual esophageal and gastric tube mucosa were dramatically decreased compared with those of normal subjects. The correlation between SCF and slow-wave activity was positive.

CONCLUSIONS

Hypomotility of the residual esophagus and gastric tube seems closely associated with disruption of the SCF/c-kit signaling pathway. However, the absence of notable relations between mucosal changes after chronic exposure to acid, biliary gastric content, and SCF expression indicates that this analysis cannot be considered part of endoscopic follow-up.

Stem cell factor: laboratory and clinical aspects

Stem cell factor is an essential haemopoietic progenitor cell growth factor with proliferative and anti-apoptotic functions. Molecular biologists have now dissected some of the various pathways through which this cytokine signals to the nucleus. At the same time, new molecules have become available which can inhibit SCF signalling. This provides an exciting prospect for the treatment of Kit+ malignancies such as acute myeloblastic leukaemia. The capacity of SCF to synergize with other cytokines has been exploited in the ex vivo expansion of haemopoietic progenitors and dendritic cells, which may also hold therapeutic promise. In this review the last 5 years' literature on these issues is reviewed and collated.