Stromal cell-derived factor 1alpha stimulates human glioblastoma cell growth through the activation of both extracellular signal-regulated kinases 1/2 and Akt

In this paper, we describe the role of chemokine receptor CXCR4 activation by its natural ligand, the chemokine stromal cell-derived factor (SDF-1) (CXCL12), in glioblastoma cell growth in vitro. We show that both CXC chemokine receptor 4 (CXCR4) and SDF-1 mRNA are expressed in several human glioblastoma multiforme tumor tissues and in two human glioblastoma cell lines, U87-MG and DBTRG-05MG. These cells are able to secrete SDF-1 under basal conditions, and the rate of secretion is highly increased after lipopolysaccharide or 1% fetal bovine serum treatment. Exogenous SDF-1alpha induces proliferation in a dose-dependent manner in both cell lines. Moreover, we observed that SDF-1alpha-dependent proliferation is correlated with phosphorylation and activation of both extracellular signal-regulated kinases 1/2 and Akt and that these kinases are independently involved in glioblastoma cell proliferation. The role of CXCR4 stimulation in glioblastoma cell growth is further demonstrated by the ability of human monoclonal CXCR4 antibody (clone 12G5) to inhibit the SDF-1alpha-induced proliferation as well as the proliferation induced by SDF-1-releasing treatments (lipopolysaccharide and 1% fetal bovine serum). These data support a role for SDF-1alpha in the regulation of glioblastoma growth in vitro, likely through an autocrine/paracrine mechanism.     

An interleukin-6 gene promoter polymorphism influences the biological phenotype of ovarian cancer

Interleukin (IL)-6 is known to be involved in the pathogenesis of ovarian cancer. We investigated a common G/C polymorphism at position -174 of the IL-6 gene (IL6) promoter in 121 patients with ovarian cancer using pyrosequencing. Presence of at least one mutant allele was associated with early tumor stage as well as an expanded length of disease-free (DFS) and overall survival with a dose-dependent effect regarding the carriage of 0, 1, and 2 alleles. In a multivariate Cox regression model incorporating tumor stage and residual tumor mass, presence of the -174 C allele of IL6 was the best predictor of DFS. We conclude that the mutant -174 C allele of IL6 influences the biological phenotype of ovarian cancer because it is associated with early stage and improved DFS and overall survival.     

Melanoma differentiation-associated gene 7/interleukin (IL)-24 is a novel ligand that regulates angiogenesis via the IL-22 receptor

The melanoma differentiation-associated gene 7 (mda-7), also called interleukin (IL)-24, suppresses the growth of some cancers in vitro and in vivo as a result of the ectopic expression of its protein. However, the function of the secreted form of the protein in cancer has not been previously studied. The purpose of this study was to determine the antiangiogenic function of a secreted form of the MDA-7/IL-24 protein (sMDA-7/IL-24). In vitro, sMDA-7/IL-24 inhibited both endothelial cell differentiation and migration of endothelial cells induced by vascular endothelial growth factor and basic fibroblast growth factor. The sMDA-7/IL-24-mediated inhibitory effect was 10-50 times more potent than endostatin, IFN-gamma, and IFN-inducible protein 10 in vitro. Furthermore, the inhibitory effect was not mediated by IFN or IFN-inducible protein 10. IL-22 receptor mediated the antiangiogenic activity of sMDA-7/IL-24. Administration of a blocking antibody to IL-22 receptor in conjunction with sMDA-7/IL-24 led to abrogation of inhibition of endothelial differentiation. sMDA-7/IL-24 inhibited vascular endothelial growth factor-induced angiogenesis as evidenced by reduced vascularization and hemoglobin content in in vivo Matrigel plug assays. In vivo, the growth of human lung tumor cells was significantly inhibited, and vascularization was reduced when the cells were mixed with 293 cells stably expressing sMDA-7/IL-24. Systemic administration of sMDA-7/IL-24 inhibited lung tumor growth in a mouse xenograft model. Associated with tumor growth inhibition was decreased tumor microvessel density and hemoglobin content, indicating the presence of antiangiogenic activity. These data demonstrate that sMDA-7/IL-24 is a novel and potent antiangiogenic effector and support the development of MDA-7/IL-24-based therapeutics.     

Selective and nonselective toxicity of TRAIL/Apo2L combined with chemotherapy in human bone tumour cells vs. normal human cells

Although TRAIL/Apo2L preferably induces apoptosis in tumour cells without toxicity in normal cells, many tumour cell types display TRAIL/Apo2L resistance. Whether TRAIL/Apo2L in combination with chemotherapy may overcome TRAIL/Apo2L resistance while maintaining tumour selectivity remains to be determined. Here, we report that while ActD, DOX and CDDP sensitised both OS and Ewing's tumour cell lines and normal cells (hOBs, synovial cells, fibroblasts) to TRAIL/Apo2L-induced apoptosis, the combination of etoposide (VP16) and TRAIL/Apo2L was selectively active on tumour cells without affecting normal cells. Sensitisation of OS cells and hOBs to TRAIL/Apo2L did not correlate with a compatible change in the gene expression profile of the receptors for TRAIL/Apo2L determined by quantitative real-time RT-PCR. Also, sensitisation of the TRAIL/Apo2L death pathway did not rely entirely on the chemotherapy-induced, caspase-dependent cytotoxicity. Further, chemotherapy did not cause a compatible change in expression levels of proteins such as Bcl-2, Bcl-x(L), Bax, cIAP2, XIAP and survivin. However, ActD, DOX and CDDP downregulated expression of cFLIP in OS cells as well as expression of p21 in normal hOBs. Interestingly, while VP16 also extinguished cFLIP in OS cells, which were sensitised for TRAIL/Apo2L by VP16, VP16 induced cFLIP and enhanced p21 levels in normal hOBs, which remained refractory to VP16 plus TRAIL/Apo2L. Together, our data reveal that TRAIL/Apo2L combined with certain chemotherapeutic drugs is toxic to bone tumour and normal human cells and suggest that cotreatment with TRAIL/Apo2L and VP16 provides an attractive approach for selective killing of tumour cells while leaving unaffected normal cells.     

Alpha-methylacyl-CoA racemase as an androgen-independent growth modifier in prostate cancer

Alpha-methylacyl-CoA racemase (AMACR) is an enzyme involved in beta-oxidation of branched-chain fatty acids and bile acid intermediates. Recent work has identified AMACR as a new diagnostic marker for prostate cancer (PCa). The data from the present study suggest that AMACR is also functionally important for the growth of PCa cells. Overexpressed AMACR from both clinical tissues and PCa cell lines is wild type by sequence analysis and functionally active by enzymatic assay. Correspondingly, enzyme activity of AMACR increases approximately 4-fold in PCa in comparison with adjacent normal prostate. Small interference RNA (siRNA) against AMACR, but not the control inverted siRNA, reduced the expression of AMACR and significantly impaired proliferation of the androgen-responsive PCa cell line LAPC-4. No effect was observed in HeLaS3 cells, which express AMACR at a low level. Cell cycle analyses revealed a G(2)-M cell cycle arrest in LAPC-4 cells treated with siRNA compared with mock treatment or control inverted siRNA. Expression of a siRNA-resistant form of AMACR in LAPC-4 cells protects the cells from growth arrest after AMACR-specific siRNA treatment. Data from Western blotting and luciferase-based reporter assays suggest that the function and expression of AMACR are independent of androgen receptor-mediated signaling. Moreover, simultaneous inhibition of both the AMACR pathway by siRNA and androgen signaling by means of androgen withdrawal or antiandrogen suppressed the growth of LAPC-4 cells to a greater extent than either treatment alone. Taken together, these data suggest that AMACR is essential for optimal growth of PCa cells in vitro and that this enzyme has the potential to be a complementary target with androgen ablation in PCa treatment.     

Ceramide analogues in apoptosis: a new strategy for anticancer drug development

A survey on the role played by ceramide within the sphingolmyelin pathway is here reported, taking into account its importance as an intracellular effector molecule in apoptosis. Recently, several analogs of ceramide, able to pass the cell membrane and then to induce apoptosis, have been developed as a new potential approach in anticancer therapy.     

Conformationally restrained ceramide analogues: effects of lipophilic modifications on the antiproliferative activity

Conformationally restrained analogues of ceramide containing thiouracil or uracil moieties in their polar head, substituted with an ethyl group in their 6-positions, proved to inhibit cell proliferation and induce apoptosis. A series of new thiouracil and uracil analogues of ceramide possessing several 6-alkyl- or 6-arylalkyl-substituents, were synthesized and tested as inhibitors of cell proliferation. The lipophilic substituents introduced in the 6-position were pure alkyls (n-propyl, n-butyl, i-butyl, neo-pentyl), or aryl-alkyls (2-phenylethyl). Although a significant antiproliferative activity was maintained in most compounds synthesized, none of them showed any improvement with respect to their 6-ethyl-substituted counterparts.     

Chemokines and their receptors in the CNS: expression of CXCL12/SDF-1 and CXCR4 and their role in astrocyte proliferation

The study of chemokine role in the CNS indubitably represents an important step to understanding many aspects of brain pathology, physiology and development. Here we discuss our recent research on the expression of chemokines and chemokine receptors in brain tissues and in cultured CNS cells, with particular regard to the CXCL12/SDF-1-CXCR4 system. We showed their expression in both glial and neuronal cells in basal conditions and their modulation upon stimulation. We demonstrated that CXCL12/SDF-1 in vitro act as a growth factor for astrocytes by stimulating their proliferation, a phenomenon that could represent the basis of pathological conditions such as gliosis and malignant transformation. We investigated the signal transduction pathways, identifying in the sequential activation of G-protein-PI-3Kinase-ERK1/2 the main signaling cascade linked to the CXCL12/SDF-1-induced proliferation in astrocytes.     

Apoptosis in hematological disorders

Apoptosis, the cell's intrinsic death program, plays a critical role in the regulation of tissue homeostasis, especially in cell systems with a high turnover rate such as hematopoietic cells. Imbalances between proliferation and cell death may result in premature death, uncontrolled polyclonal or monoclonal expansion or tumor formation. Also, cytotoxic therapy and immunotherapy of leukemia and lymphoma predominantly mediates cell death through induction of apoptosis. Understanding the molecular events by which tumor cells evade apoptotic deletion and which induce apoptosis by cytotoxic therapies, have provided a paradigm to link normal growth control, malignant transformation and response to therapy.