Differences in the expression of caveolin-1 isoforms in cancer-associated and normal fibroblasts of patients with oral squamous cell carcinoma.

OBJECTIVES: For many years, tumor development has been viewed as a cell-autonomous process; however, today we know that the tumor microenvironment (TME) and especially cancer-associated fibroblasts (CAFs) significantly contribute to tumor progression. Caveolin-1 (Cav-1) is a scaffolding protein which is involved in several cancer-associated processes as important component of the caveolae. Our goal was to shed light on the expression of the two different isoforms of Cav-1 in normal fibroblasts (NFs) and CAFs of patients with oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: Fibroblasts from normal mucosa and CAFs were isolated and propagated in vitro. Gene expression of the different Cav-1 isoforms was assessed via quantitative real-time PCR (qPCR) and supplemented by protein expression analysis. RESULTS: We could show that the Cav-1ß isoform is more highly expressed in NFs and CAFs compared to Cav-1α. Furthermore, the different Cav-1 isoforms tended to be differently expressed in different tumor stages. However, this trend could not be seen consistently, which is in line with the ambiguous role of Cav-1 in tumor progression described in literature. Western blotting furthermore revealed that NFs and CAFs might differ in the oligomerization profile of the Cav-1 protein. CONCLUSION: These differences in expression of Cav-1 between NFs and CAFs of patients with OSCC confirm that the protein might play a role in tumor progression and is of interest for further analyses. CLINICAL RELEVANCE: Our findings support a possible role of the two isoforms of Cav-1 in the malignant transformation of OSCC.

Influence of mechanical compression on human periodontal ligament fibroblasts and osteoblasts.

OBJECTIVES: The aim of this study was to investigate and compare the changes in human periodontal ligament fibroblasts (HPdLFs) and osteoblasts (HOBs) after the application of compressive force (CF) at two different strengths in vitro. MATERIALS AND METHODS: HPdLF and HOB were exposed to CF with various strengths (5 and 10 %) using a Flexercell Compression Unit for 12 h in vitro. Viability was detected via 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide (MTT) and apoptosis rate by transferase dUTP nick end labeling (TUNEL) assay. The gene expression of alkaline phosphatase (ALP), osteocalcin (OCN), osteoprotegerin (OPG), and receptor activator of NF-κB ligand (RANKL) was analyzed using reverse transcriptase polymerase chain reaction (RT-PCR). Osteopontin (OPN), matrix metalloproteinase-8 (MMP-8), and tissue inhibition of metalloproteinase-1 (TIMP-1) were quantified by an ELISA. RESULTS: Ten percent CF decreased viability, particularly in HOBs, but did not induce increased apoptosis. ALP gene expression increased the most after 5 % CF in HPdLFs and after 10 % CF in HOB. OCN was not affected by CF in either cell line. The highest RANKL/OPG ratio was measured after 5 % CF in both cell lines. OPN was upregulated in HOB by 5 %. HPdLFs showed an upregulation of MMP-8-synthesis and an increased MMP-8/TIMP-1 ratio. CONCLUSIONS: HOBs have a greater effect on bone remodeling through the upregulation of OPN, whereas HPdLFs facilitate orthodontic tooth movement by influencing the extracellular matrix via the MMP-8/TIMP-1 ratio. CLINICAL RELEVANCE: High CF in orthodontics should be avoided to prevent tissue damage, whereas moderate CF enables active tissue remodeling and tooth movement.

Extramedullary expansion of hematopoietic progenitor cells in interleukin (IL)-6-sIL-6R double transgenic mice.

Soluble cytokine receptors modulate the activity of their cognate ligands. Interleukin (IL)-6 in association with the soluble IL-6 receptor (sIL-6R) can activate cells expressing the gp130 signal transducer lacking the specific IL-6R. To investigate the function of the IL-6-sIL-6R complex in vivo and to discriminate the function of the IL-6-sIL-6R complex from the function of IL-6 alone, we have established a transgenic mouse model. Double-transgenic mice coexpressing IL-6 and sIL-6R were generated and compared with IL-6 and sIL-6R single-transgenic mice. The main phenotype found in IL-6-sIL-6R mice was a dramatic increase of extramedullary hematopoietic progenitor cells in liver and spleen but not in the bone marrow. In IL-6 single-transgenic mice and sIL-6R single-transgenic mice no such effects were observed. The high numbers of hematopoietic progenitor cells were reflected by a strong increase of peripheral blood cell numbers. Therefore, activators of the gp130 signal transducer like the IL-6-IL-6R complex may represent most powerful stimulators for extramedullary hematopoietic progenitor cells. gp130 activators may become important for the expansion of hematopoietic progenitor cells in vivo and in vitro.

I. A bioactive designer cytokine for human hematopoietic progenitor cell expansion.

Efficient expansion of hematopoietic progenitor cells requires, at least, the simultaneous stimulation of the receptors c-kit and gp130. While c-kit is activated by SCF; gp130, in cells which do not express sufficient amounts of IL-6R, can be activated by the complex of soluble IL-6R (sIL-6R) and IL-6. The therapeutic use of IL-6/sIL-6R, however, has been hampered by the high concentrations of the sIL-6R protein required. We have designed a fusion protein of sIL-6R and IL-6, linked by a flexible peptide chain, that was expressed to high levels. On gp130 expressing cells the fusion protein turned out to be fully active at 100 to 1,000-fold lower concentration than the combination of unlinked IL-6 and IL-6R. The fusion protein was used to effectively expand human hematopoietic progenitor cells ex vivo in a dose dependent fashion.

Potentiation of granulocyte colony-stimulating factor-induced mobilization of circulating progenitor cells by seven-day pretreatment with interleukin-3.

Granulocyte colony-stimulating factor (G-CSF) as a single agent is increasingly used for the mobilization of peripheral blood progenitor cells (PBPCs) for stem cell transplantation. In patients with perturbed hematopoiesis the mobilizing capacity of G-CSF alone may be inadequate. We have shown in rhesus monkeys that interleukin-3 (IL-3) pretreatment markedly potentiated the increase in PBPC numbers by subsequent administration of granulocyte/macrophage-CSF (GM-CSF). Here we studied the effect of IL-3 pretreatment on G-CSF-induced mobilization of PBPCs in 6 patients with Hodgkin's disease (n = 5) or non-Hodgkin's lymphoma (n = 1) who had low progenitor cell numbers because of previous chemotherapy. Patients were treated in cycle 1 with G-CSF at a dose of 5 microgram/kg/d for 5 days and, after a treatment-free interval, received cycle 2 consisting of 5 microgram/kg/d of IL-3 for 7 days followed by G-CSF again at a dose of 5 microgram/kg/d for 5 days. G-CSF alone increased the mean number of circulating colony-forming units-GM (CFU-GM) by 21-fold, the number of burst-forming units-erythroid (BFU-E) by 9-fold, and the number of CFU-mix by 24-fold over pretreatment values. Treatment with 5 microgram/kg/d of IL-3 for 7 days did not mobilize by itself but significantly potentiated G-CSF-induced mobilization of all progenitor cell types leading to a 56-, 15-, and 46-fold increase over baseline of CFU-GM, BFU-E, and CFU-mix numbers, respectively. In 2 patients in whom leukapheresis was performed after G-CSF alone the target number of 2 x 10(6)/kg CD34+ cells was not reached. However, leukapheresis after the IL-3/G-CSF combination obtained > or =2 x 10(6)/kg CD34+ cells in 3 of 6 patients, including both patients who had inadequate collection after G-CSF alone. In one patient adequate function of mobilized progenitors could be shown by the demonstration of rapid trilineage engraftment after infusion of progenitors after myeloablative chemotherapy. Seven-day pretreatment with IL-3 may be a useful mean to augment mobilization of circulating progenitors by G-CSF. The combination of IL-3 and G-CSF seems to allow the procurement of sufficient numbers of PBPCs in some patients who cannot be mobilized adequately by G-CSF alone.

Differential effect of type I interferons on hematopoietic progenitor cells: failure of interferons to inhibit IL-3-stimulated normal and CML myeloid progenitors.

We observed a differential effect of type I interferons (IFNs) in inhibiting the proliferation of various hematopoietic progenitor cell types. Upon stimulation with interleukin-3 (IL-3), IFN-alpha and IFN-beta failed to inhibit colony formation of myeloid progenitors (day-14 colony-forming units-granulocyte/macrophage [CFU-GM]) obtained from peripheral blood (PB) and bone marrow (BM) of untreated chronic myelogenous leukemia (CML) patients in chronic phase even at IFN doses as high as 10,000 U/mL. In contrast, day-7 CFU-GM stimulated with granulocyte colony-stimulating factor (G-CSF) and burst-forming units-erythroid (BFU-E) were readily inhibited by moderate doses of IFNs. IFN-resistant myeloid progenitor cells were also detected in normal BM but not in normal PB cells. When suboptimal doses of IL-3 were used in clonal progenitor cell assays, day-14 CFU-GM were not protected from the inhibitory action of IFN. The failure of IFN to inhibit immature myeloid progenitors was confirmed in normal and CML cells highly enriched in CD34-expressing cells. Combinations of growth factors were required for sufficient colony formation in these cells, whereas IL-3 alone provided only an inadequate stimulation, which was further inhibited by IFN. In purified CD34+ cells, day-14 CFU-GM were protected from IFN-mediated inhibition only upon stimulation with stem cell factor (SCF) in combination with IL-3 or G-CSF.

Effect of interleukin-3 pretreatment on granulocyte/macrophage colony-stimulating factor induced mobilization of circulating haemopoietic progenitor cells.

Recombinant human colony stimulating factors (CSFs) as single agents are increasingly used for mobilizing peripheral blood progenitor cells (PBPCs) for stem cell transplantation. We have shown in rhesus monkeys that interleukin-3 (IL-3) pretreatment markedly potentiated the increase in PBPC numbers of subsequent administration of granulocyte/macrophage-CSF (GM-CSF). Here we studied the effect of IL-3 pretreatment on GM-CSF-induced mobilization of PB progenitors in patients who were potential candidates for autologous stem cell transplantation (n = 16). Patients were treated with GM-CSF at a dose of 5 micrograms/kg/d for 5 d and after a treatment free interval received another cycle of GM-CSF immediately following pretreatment with IL-3 at different doses and duration: 2.5 micrograms/kg/d (n = 4), 5 micrograms/kg/d (n = 3) and 10 micrograms/kg/d (n = 3) for 3 d, 5 micrograms/kg/d for 7 d (n = 4) and 5 micrograms/kg/d for 14 d (n = 2), respectively. Only 7 d pretreatment with IL-3 showed consistent effects. Although IL-3 did not mobilize by itself, pretreatment with 5 micrograms/kg/d of IL-3 for 7 d significantly potentiated GM-CSF-induced mobilization of PB CFU-GM numbers, leading to a mean increase in PB CFU-GM numbers over baseline by 18.5 +/- 5.2 (SEM) fold by IL-3/GM-CSF as compared to a 4.7 +/- 1.7-fold increase by GM-CSF alone. A significant enhancement by the 7 d IL-3 pretreatment was also observed for erythroid (BFU-E) and multipotential progenitor cells (CFU-mix) which were 3.3 +/- 1.3- and 3.4 +/- 0.9-fold, respectively, mobilized by GM-CSF alone, as compared to 8.5 +/- 2.3- and 19.2 +/- 3.4-fold, respectively, by the IL-3/GM-CSF combination. Our results suggest that 7 d pretreatment with IL-3 may be a useful mean to augment mobilization of circulating progenitors by more lineage-restricted CSFs. These findings may be important for the design of mobilization strategies that use growth factors without preceding chemotherapy.

Type-I interferons are potent inhibitors of interleukin-8 production in hematopoietic and bone marrow stromal cells.

Interleukin-8 (IL-8) is produced by many cell types upon stimulation with bacterial products or inflammation-associated cytokines such as tumor necrosis factor-alpha and IL-1. Interferons (IFNs) represent another group of cytokines that are induced by similar stimuli in inflammatory reactions. We show now that type-I IFNs are potent inhibitors of IL-8 expression in vitro and in vivo. A significant reduction of both secretion of IL-8 protein and accumulation of IL-8 mRNA in vitro was observed in several cell types comprising peripheral blood mononuclear cells (PBMNC) from healthy donors and from patients with chronic myelogenous leukemia (CML), the myelomonocytic cell line THP-1, and bone marrow (BM) stromal cells as a representative model for BM microenvironment. By contrast, in lipopolysaccharide-stimulated polymorphonuclear phagocytes IFN failed to suppress IL-8 expression. In untreated patients with CML, a constitutive expression of IL-8 mRNA was detected in freshly isolated PBMNC that was markedly reduced 5 hours after therapeutic application of IFN-alpha. The mechanism of IL-8 downregulation was studied more in detail in the THP-1 cell line. The experiments showed that de novo protein synthesis was not required for the inhibitory effect. RNA decay analysis and nuclear run-on assays suggest that in THP-1 cell line the inhibition of IL-8 expression is predominantly regulated at the posttranscriptional level.