Granulocyte colony-stimulating factor receptor signals for β1-integrin expression and adhesion in bladder cancer

A review of granulocyte colony-stimulating factor receptor signaling and regulation with implications for cancer

Granulocyte colony-stimulating factor receptor (GCSFR) is a critical regulator of granulopoiesis. Studies have shown significant upregulation of GCSFR in a variety of cancers and cell types and have recognized GCSFR as a cytokine receptor capable of influencing both myeloid and non-myeloid immune cells, supporting pro-tumoral actions. This systematic review aims to summarize the available literature examining the mechanisms that control GCSFR signaling, regulation, and surface expression with emphasis on how these mechanisms may be dysregulated in cancer. Experiments with different cancer cell lines from breast cancer, bladder cancer, glioma, and neuroblastoma are used to review the biological function and underlying mechanisms of increased GCSFR expression with emphasis on actions related to tumor proliferation, migration, and metastasis, primarily acting through the JAK/STAT pathway. Evidence is also presented that demonstrates a differential physiological response to aberrant GCSFR signal transduction in different organs. The lifecycle of the receptor is also reviewed to support future work defining how this signaling axis becomes dysregulated in malignancies.

Identification and functional analysis of risk-related microRNAs for the prognosis of patients with bladder urothelial carcinoma

The aim of the present study was to investigate risk-related microRNAs (miRs) for bladder urothelial carcinoma (BUC) prognosis. Clinical and microRNA expression data downloaded from the Cancer Genome Atlas were utilized for survival analysis. Risk factor estimation was performed using Cox's proportional regression analysis. A microRNA-regulated target gene network was constructed and presented using Cytoscape. In addition, the Database for Annotation, Visualization and Integrated Discovery was used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway enrichment, followed by protein-protein interaction (PPI) network analysis. Finally, the K-clique method was applied to analyze sub-pathways. A total of 16 significant microRNAs, including hsa-miR-3622a and hsa-miR-29a, were identified (P<0.05). Following Cox's proportional regression analysis, hsa-miR-29a was screened as a prognostic marker of BUC risk (P=0.0449). A regulation network of hsa-miR-29a comprising 417 target genes was constructed. These target genes were primarily enriched in GO terms, including collagen fibril organization, extracellular matrix (ECM) organization and pathways, such as focal adhesion (P<0.05). A PPI network including 197 genes and 510 interactions, was constructed. The top 21 genes in the network module were enriched in GO terms, including collagen fibril organization and pathways, such as ECM receptor interaction (P<0.05). Finally, 4 sub-pathways of cysteine and methionine metabolism, including paths 00270_4, 00270_1, 00270_2 and 00270_5, were obtained (P<0.01) and identified to be enriched through DNA (cytosine-5)-methyltransferase (DNMT)3A, DNMT3B, methionine adenosyltransferase 2α (MAT2A) and spermine synthase (SMS). The identified microRNAs, particularly hsa-miR-29a and its 4 associated target genes DNMT3A, DNMT3B, MAT2A and SMS, may participate in the prognostic risk mechanism of BUC.

Granulocyte colony-stimulating factor (G-CSF) upregulates β1 integrin and increases migration of human trophoblast Swan 71 cells via PI3K and MAPK activation

Multiple cytokines and growth factors expressed at the fetal-maternal interface are involved in the regulation of trophoblast functions and placental growth, but the role of G-CSF has not been completely established. Based on our previous study showing that G-CSF increases the activity of matrix metalloproteinase-2 and the release of vascular endothelial growth factor in Swan 71 human trophoblast cells, in this work we explore the possible contribution of G-CSF to cell migration and the G-CSF-triggered signaling pathway. We found that G-CSF induced morphological changes on actin cytoskeleton consistent with a migratory cell phenotype. G-CSF also up-regulated the expression levels of β1 integrin and promoted Swan 71 cell migration. By using selective pharmacological inhibitors and dominant negative mutants we showed that PI3K, Erk 1/2 and p38 pathways are required for promoting Swan 71 cell motility. It was also demonstrated that PI3K behaved as an upstream regulator of Erk 1/2 and p38 MAPK. In addition, the increase of β1 integrin expression was dependent on PI3K activation. In conclusion, our results indicate that G-CSF stimulates β1 integrin expression and Swan 71 cell migration by activating PI3K and MAPK signaling pathways, suggesting that G-CSF should be considered as an additional regulatory factor that contributes to a successful embryo implantation and to the placenta development.

RAD9 enhances radioresistance of human prostate cancer cells through regulation of ITGB1 protein levels

BACKGROUND

Mouse embryonic stem cells null for Rad9 are sensitive to deleterious effects of ionizing radiation exposure. Likewise, integrin β1 is a known radioprotective factor. Previously, we showed that RAD9 downregulation in human prostate cancer cells reduces integrin β1 protein levels and ectopic expression of Mrad9 restores inherent high levels.

METHODS

We used RNA interference to knockdown Rad9 expression in PC3 and DU145 prostate cancer cells. These cells were then exposed to ionizing radiation, and integrin β1 protein levels were measured by immunoblotting. Survival of irradiated cells was measured by clonogenicity, cell cycle analysis, PARP-1 cleavage, and trypan blue exclusion.

RESULTS

The function of RAD9 in controlling integrin β1 expression is unique and not shared by the other members of the 9-1-1 complex, HUS1 and RAD1. RAD9 or integrin β1 silencing sensitizes DU145 and PC3 cells to ionizing radiation. Irradiation of DU145 cells with low levels of RAD9 induces cleavage of PARP-1 protein. High levels of ionizing radiation have no effect on integrin β1 protein levels. However, when RAD9 downregulation is combined with 10 Gy of ionizing radiation in DU145 or PC3 cells, there is an additional 50% downregulation of integrin β1 compared with levels in unirradiated RAD9 knockdown cells. Finally, PC3 cells growing on fibronectin display increased radioresistance. However, PC3 cells with RAD9 knockdown are no longer protected by fibronectin after treatment with ionizing radiation.

CONCLUSIONS

Downregulation of RAD9 when combined with ionizing radiation results in reduction of ITGB1 protein levels in prostate cancer cells, and increased lethality.

G-CSF does not influence C2C12 myogenesis despite receptor expression in healthy and dystrophic skeletal muscle

Granulocyte-colony stimulating factor (G-CSF) increases recovery of rodent skeletal muscles after injury, and increases muscle function in rodent models of neuromuscular disease. However, the mechanisms by which G-CSF mediates these effects are poorly understood. G-CSF acts by binding to the membrane spanning G-CSFR and activating multiple intracellular signaling pathways. Expression of the G-CSFR within the haematopoietic system is well known, but more recently it has been demonstrated to be expressed in other tissues. However, comprehensive characterization of G-CSFR expression in healthy and diseased skeletal muscle, imperative before implementing G-CSF as a therapeutic agent for skeletal muscle conditions, has been lacking. Here we show that the G-CSFR is expressed in proliferating C2C12 myoblasts, differentiated C2C12 myotubes, human primary skeletal muscle cell cultures and in mouse and human skeletal muscle. In mdx mice, a model of human Duchenne muscular dystrophy (DMD), G-CSF mRNA and protein was down-regulated in limb and diaphragm muscle, but circulating G-CSF ligand levels were elevated. G-CSFR mRNA in the muscles of mdx mice was up-regulated however steady-state levels of the protein were down-regulated. We show that G-CSF does not influence C₂C₁₂ myoblast proliferation, differentiation or phosphorylation of Akt, STAT3, and Erk1/2. Media change alone was sufficient to elicit increases in Akt, STAT3, and Erk1/2 phosphorylation in C₂C₁₂ muscle cells and suggest previous observations showing a G-CSF increase in phosphoprotein signaling be viewed with caution. These results suggest that the actions of G-CSF may require the interaction with other cytokines and growth factors in vivo, however these data provides preliminary evidence supporting the investigation of G-CSF for the management of muscular dystrophy.

Role of the interleukin 6 receptor family in epithelial ovarian cancer and its clinical implications

Ovarian cancer is the most lethal gynecological malignancy, with few effective treatment options in most cases. Therefore, understanding the biology of ovarian cancer remains an important area of research in order to improve clinical outcomes. Cytokine receptor signaling through the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway is an essential component of normal development and homeostasis. However, numerous studies have implicated perturbation of this pathway in a range of cancers. In particular, members of the IL-6R family acting via the downstream STAT3 transcription factor play an important role in a number of solid tumors - including ovarian cancer - by altering the expression of target genes that impact on key phenotypes. This has led to the development of specific inhibitors of this pathway which are being used in combination with standard chemotherapeutic agents. This review focuses on the role of IL-6R family members in the etiology of epithelial ovarian cancer, and the application of therapies specifically targeting IL-6R signaling in this disease setting.

Granulocyte colony-stimulating factor receptor signalling via Janus kinase 2/signal transducer and activator of transcription 3 in ovarian cancer

Background:

Ovarian cancer remains a major cause of cancer mortality in women, with only limited understanding of disease aetiology at the molecular level. Granulocyte colony-stimulating factor (G-CSF) is a key regulator of both normal and emergency haematopoiesis, and is used clinically to aid haematopoietic recovery following ablative therapies for a variety of solid tumours including ovarian cancer.

Methods:

The expression of G-CSF and its receptor, G-CSFR, was examined in primary ovarian cancer samples and a panel of ovarian cancer cell lines, and the effects of G-CSF treatment on proliferation, migration and survival were determined.

Results:

G-CSFR was predominantly expressed in high-grade serous ovarian epithelial tumour samples and a subset of ovarian cancer cell lines. Stimulation of G-CSFR-expressing ovarian epithelial cancer cells with G-CSF led to increased migration and survival, including against chemotherapy-induced apoptosis. The effects of G-CSF were mediated by signalling via the downstream JAK2/STAT3 pathway.

Conclusion:

This study suggests that G-CSF has the potential to impact on ovarian cancer pathogenesis, and that G-CSFR expression status should be considered in determining appropriate therapy.

Most purported antibodies to the human granulocyte colony-stimulating factor receptor are not specific

OBJECTIVE

Antibodies to human granulocyte colony-stimulating factor receptor (HuG-CSFR) are widely available and have been used in numerous studies to evaluate the expression of this protein on normal and malignant cells of hematopoietic and nonhematopoietic origin. Spurred by recent studies that demonstrated that two commonly used antibodies against the erythropoietin and thrombopoietin receptors can in fact bind to completely unrelated and more broadly expressed proteins, we screened 27 commercially available monoclonal and polyclonal antibodies with claimed specificity to HuG-CSFR to determine if they are specific to this receptor.

MATERIALS AND METHODS

Antibodies were evaluated by Western blotting, flow cytometry, and immunohistochemistry using 293T cells engineered to overexpress HuG-CSFR protein, immortalized human hematopoietic cell lines expressing endogenous G-CSFR, and purified human neutrophils.

RESULTS

Only two monoclonal antibodies and one polyclonal antibody could be employed using defined Western blotting or flow cytometry protocols to detect G-CSFR protein in cell lysates or on the surface of cells that express G-CSFR messenger RNA with no binding to cells that did not express the gene. None of the antibodies were suitable for immunohistochemistry. Competitive inhibition with soluble G-CSFR extracellular domain and small inhibitory RNA-mediated knock-down of G-CSFR messenger RNA further demonstrated the limited specificity of these antibodies for HuG-CSFR expressed on the cell surface.

CONCLUSIONS

Most commercially available anti-HuG-CSFR antibodies do not bind specifically to this protein. These studies highlight the need for investigators to validate antibodies in their own systems to avoid the inadvertent use of nonspecifically binding antibodies that could lead, as exemplified in this case with a hematopoietic growth factor receptor, to erroneous conclusions about protein expression.

Granulocyte colony stimulating factor alters the phenotype of neuroblastoma cells: implications for disease-free survival of high-risk patients

INTRODUCTION

Granulocyte colony stimulating factor (GCSF) is commonly used for the treatment of chemotherapy-induced neutropenia. Despite high-dose intensive chemotherapy for advanced-stage neuroblastoma, the survival rate remains poor. Granulocyte colony stimulating factor therapy is quite common in these children; thus, we questioned its effect on neuroblastoma cells. We hypothesized that exogenous GCSF stimulates the proliferation and invasive character of neuroblastoma cells.

METHODS

Expression of a GCSF receptor in 5 different neuroblastoma cell lines was determined by polymerase chain reaction. In addition, we determined the effect of increasing doses of GCSF (0, 1 ng/mL, 10 ng/mL, 1 microg/mL, and 10 microg/mL) on DNA synthesis (BrdU assay), invasiveness (Matrigel invasion chambers), and cell proliferation.

RESULTS

We tested 5 neuroblastoma cell lines; all expressed the GCSF receptor. Granulocyte colony stimulating factor treatment resulted in significantly increased proliferation of SK-N-SH, SK-N-AS, and SHSY-5Y cells. Likewise, increased invasiveness of SK-N-SH cells was observed with GCSF treatment.

CONCLUSIONS

Our results indicate that neuroblastoma cell lines express the GCSF receptor and respond to exogenous GCSF by increased proliferation and invasiveness. These findings suggest that GCSF may stimulate the growth of neuroblastoma cells in patients undergoing high-dose chemotherapy with GCSF rescue and could have a significant impact on the ability to eradicate these tumors.

Granulocyte colony-stimulating factor/granulocyte colony-stimulating factor receptor biological axis promotes survival and growth of bladder cancer cells

OBJECTIVES

A significant fraction of invasive bladder carcinomas express both granulocyte colony-stimulating factor (G-CSF) and granulocyte colony-stimulating factor receptor (G-CSFR). We sought to determine whether G-CSF/G-CSFR signaling promotes survival and growth of bladder cancer cells. The bladder carcinoma cell line 5637 constitutively secretes G-CSF but lacks G-CSFR expression. In contrast, TCC-SUP lacks expression of both G-CSF and G-CSFR. Using these bladder cancer cell lines as our model systems, we studied the effects of G-CSFR expression on cell proliferation, survival, and growth in vivo.

METHODS

The TCC-SUP and 5637 cells were transiently transfected with either empty vector (3.1) or G-CSFR (GR). Cell proliferation was assessed with or without G-CSF by MTT assay in TCC-SUP-3.1 and TCC-SUP-GR cells. Apoptosis was examined by flow cytometry in 5637-GR with or without anti-G-CSF antibody and in TCC-SUP-GR in the presence of increasing concentrations of G-CSF. We examined the effects of STAT3 (signal transducer and activator of transcription 3) dominant-negative expression on G-CSF/G-CSFR-mediated STAT3 phosphorylation by Western blotting in TCC-SUP-3.1 and TCC-SUP-GR cells. We characterized the effects of STAT3-dominant-negative expression on G-CSF/G-CSFR-mediated survivin expression by flow cytometry in TCC-SUP-3.1 and TCC-SUP-GR cells. We also examined tumor growth using 5637-3.1 and 5637-GR in the nude mice xenograft model.

RESULTS

The G-CSF/G-CSFR loop significantly increased proliferation in TCC-SUP-GR cells. Anti-G-CSF antibody significantly increased apoptosis in serum-starved 5637-GR cells, G-CSF abrogated apoptosis in serum-starved TCC-SUP-GR cells in a dose-dependent manner. STAT3-dominant-negative expression blocked G-CSF-mediated STAT3 phosphorylation and survivin expression in TCC-SUP-GR cells. Furthermore, 5637-GR cells produced a significantly larger tumor in the subcutaneous nude mice xenograft model.

CONCLUSIONS

The G-CSF/G-CSFR autocrine/paracrine signaling loop significantly promotes survival and growth of bladder cancer cells.

A gene expression profile for vascular invasion can predict the recurrence after resection of hepatocellular carcinoma: a microarray approach

BACKGROUND

Recurrence after hepatocellular carcinoma (HCC) resection is the major obstacle to improved survival. The presence of vascular invasion (VI) in pathology specimens is a well-known unfavorable prognostic factor for HCC recurrence. Though some VI-related genes have been reported, their association with recurrence-free survival is not known. We hypothesized that a gene expression profile for VI can predict the recurrence of HCC after liver resection.

METHODS

Eighteen patients receiving complete HCC resection were included as a "training group". Genome-wide gene expression profile was obtained for each tumor using a microarray technique. Datasets were subjected to clustering analysis supervised by the presence or absence of VI to obtain 14 discriminative genes. We then applied those genes to execute pattern recognition using the k-Nearest Neighbor (KNN) classification method, and the best model for this VI gene signature to predict recurrence-free survival in the training group was obtained. The resulting model was then tested in an independent "test group" of 35 patients.

RESULTS

A 14-gene profile was extracted which could accurately separate ten patients with VI and eight patients without VI in the "training group". In the "test group", significant difference in disease-free survival was found between patients predicted to have and not to have recurrence (P = .02823). In patients with stage_I disease, this model can also predict outcomes (P = .000205).

CONCLUSIONS

Using the 14-gene expression profile extracted from microarrays based on the presence of VI can effectively predict recurrence after HCC resection. This approach might facilitate "personalized medicine" for HCC patients after surgical resection.

Granulocyte colony-stimulating receptor promotes beta1-integrin-mediated adhesion and invasion of bladder cancer cells

OBJECTIVES

To determine whether granulocyte colony-stimulating factor receptor (G-CSFR) autocrine signaling promotes endothelial cell adhesion and invasion of bladder cancer cells through a beta1-integrin-mediated pathway. A significant fraction of invasive bladder carcinomas express both G-CSF and G-CSFR. Bladder carcinoma cell line 5637 constitutively secretes G-CSF but lacks G-CSFR expression. Thus, we studied the effects of G-CSFR expression on cell adhesion and invasion in this unique model system.

METHODS

Flow cytometry and adhesion assay were performed to detect expression of beta1-integrin in G-CSFR-expressing 5637 cells and adhesion of these cells to human umbilical vein endothelial cell, respectively. Furthermore, an invasion chamber assay was done with the 5637 cells. Next, we used the G-CSF-specific antibody, siRNA, and a truncated version of G-CSFR (GR19) to block G-CSFR autocrine loop in these cells. We also used a beta1-integrin-specific neutralizing antibody in the adhesion and invasion assays with the 5637 cells.

RESULTS

G-CSFR-mediated increased expression (approximately threefold) of beta1-integrin is significantly abrogated by G-CSF specific antibody or siRNA in 5637 cells. GR19 also completely blocked beta1-integrin expression. G-CSFR signaling increased adhesion (approximately 2.5-fold) of 5637 cells to human umbilical vein endothelial cells, which are potently blocked by beta1-integrin-specific antibody. G-CSF/G-CSFR autocrine signaling significantly increased the invasiveness of 5637 cells (approximately 10-fold), which was reduced by either attenuating G-CSF production (G-CSF-specific antibody and siRNA) or interfering with G-CSFR signaling (GR19). Furthermore, beta1-integrin-specific antibody completely blocked G-CSFR-mediated invasion of 5637 cells.

CONCLUSIONS

Autocrine G-CSF/G-CSFR signaling in bladder cancer can significantly contribute to cancer cell adhesion and invasion in a beta1-integrin-dependent manner.

High dose fractionated ionizing radiation inhibits prostate cancer cell adhesion and beta(1) integrin expression

BACKGROUND

The effect of ionizing radiation on extracellular matrix (ECM)-mediated cellular functions is an important area of research for translational science. Mechanisms of tumor cell ability to proliferate, migrate, and survive appear dependent on integrin-mediated adhesion to the ECM; however, the exact role therapeutic radiation plays in altering signaling pathways and promoting cell death within remains less well established.

METHODS

To examine these effects on prostate carcinoma cell lines, cells were irradiated at sub-lethal doses. We have studied two human prostate cancer cell lines (PC3 and DU-145) irradiated with different fractionated radiation schedules. Three groups were compared to non-irradiated controls. Group A was given a single dose of 5 Gy. Group B was given 5 Gy the first week and then 10 Gy the second week for a total of 15 Gy. Group C was given 5 Gy the first week, and then 10 Gy the second and third week for a total of 25 Gy. Cells were analyzed at their prescribed total dose. At 48 hr post irradiation, cells were detached from culture dishes and were subsequently used for adhesion assays and immunoblotting analysis.

RESULTS

Our findings revealed that two prostate carcinoma cell lines, PC3 and DU-145, had a reduced cellular adhesion to fibronectin (FN) compared to the non-irradiated control groups. Both prostate cancer cell lines showed decreased adhesion to FN and reduced beta(1) integrin protein levels at a total dose of 25 Gy, but not at the doses of 15 and 5 Gy. In a parallel analysis, at the maximum total dose of 25 Gy, both PC3 and DU-145 demonstrated a significant decrease in cell proliferation.

CONCLUSIONS

High dose radiation treatment of prostate cancer cell lines inhibits integrin expression. Our study suggests that promoting a synergistic decrease in adhesion could bring additional therapeutic benefit to patients treated with radiation therapy.