IDH mutations in G2-3 conventional central bone chondrosarcoma: a mono institutional experience.

BACKGROUND: Heterozygous isocitrate dehydrogenase (IDH) mutations occur in about half of conventional central bone chondrosarcomas (CCBC). Aim of this study was to assess the frequency and prognostic impact of IDH mutations in high grade CCBC patients. METHODS: 64 patients with G2 and G3 CCBC were included. DNA extraction, PCR amplification of IDH1/2 exon 4s, and sequencing analysis with Sanger were performed. RESULTS: IDH mutations were detected in 24/54 patients (44%): IDH1 in 18, IDH2 in 4, and both IDH1/2 in 2 patients. The frequency of mutations was 37% in G2 vs. 69% in G3 (p = 0.039), and 100% in three Ollier disease associated chondrosarcoma. 5-year overall survival (OS) at 124 months (range 1-166) was 51%, with no significant difference based on the IDH mutational status: 61% in IDHmut vs. 44% in IDH wild type (IDHwt). The 5-year relapse free survival (RFS) was 33% (95% CI:10-57) for IDHmut vs. 57% (95%CI: 30-77) for IDHwt. Progression free survival (PFS) was 25% (95%CI:1-65) IDHmut vs. 16% (95%CI: 0.7-52) IDHwt. 55% (5/9) of IDHmut G2 became higher grade at the recurrence, as compared with 25% (3/12) of G2 IDHwt. CONCLUSIONS: This study shows a higher frequency of IDH mutations in G3 CCBC as compared with G2. No significant differences in OS, RFS, and PFS by mutational status were detected. After relapse, a higher rate of G3 for IDH mutated CCBC was observed.

The effect of extracellular acidosis on the behaviour of mesenchymal stem cells in vitro.

The stem cell fraction of a cell population is finely tuned by stimuli from the external microenvironment. Among these stimuli, a decrease of extracellular pH (pHe) may occur in a variety of physiological and pathological conditions, including hypoxia and inflammation. In this study, by using bone marrow stem cells and dental pulp stem cells, we provided evidence that extracellular acidosis endows the maintenance of stemness in mesenchymal cells. Indeed, continuous exposure for 21 d to low pHe (6.5-6.8) conditions impaired the osteogenic differentiation of both cell types. Moreover, the exposure to low pHe, for 1 and up to 7 d, induced the expression of stemness-related genes and proteins, drove cells to reside in the quiescent G0 alert state and enhanced their ability to form floating spheres. The pre-conditioning with extracellular acidosis for 7 d did not affect the differentiation potential of dental pulp stem cells since, when the cells were cultured again at physiological pHe, their multilineage potential was almost unmodified. Our data provided evidence of the role of extracellular acidosis as a modulator of the stemness of mesenchymal cells. This condition is commonly found both in systemic and local bone conditions, hence underlining the relevance of this phenomenon for a better comprehension of bone healing and regeneration.

Interferon-alpha inhibits in vitro osteoclast differentiation and renal cell carcinoma-induced angiogenesis.

Bone is a common site of osteolytic and richly vascularized metastases of renal cell carcinoma (RCC) and Interferon (IFN)-alpha based therapies have been considered for the treatment of patients affected by this disease. The effects of IFN-alpha on metastatic RCC patients have been related to its immunomodulatory, and cytotoxic activity on tumor cells, but there could be an effect also on tumor induced osteoclast differentiation and bone angiogenesis. When osteoclasts obtained from human peripheral blood mononuclear cells, cultured in the presence of receptor activator of nuclear factor-kappaB (RANKL) and macrophage-colony stimulating factor (M-CSF), were treated with IFN-alpha, the expression of bone tartrate resistant acid phosphatase (TRACP) type 5b was reduced, as well as calcium-phosphate resorption activity and expression of pro-osteoclatic transcription factor c-Fos. IFN-alpha modulation of angiogenesis was studied by analysis of proliferation, survival, and migration of a bone endothelial cell line (BBE), and by the analysis of pro-angiogenic factor expression in RCC cell lines. IFN-alpha inhibited bone endothelial cell proliferation and the expression of FGF-2, while the vascular endothelial growth (VEGF) did not show any significant variation. Moreover, IFN-alpha inhibited the migration induced by the RCC through the impairment of fibroblast growth factor-2 (FGF-2) secretion. These data demonstrate multiple activities of IFN-alpha on renal cancer-induced bone disease, in addition to its recognized role as a cytotoxic and immunomodulatory agent, because they indicate its ability to reduce bone resorption and to impair tumor-associated angiogenesis, and they also suggest the use of IFN-alpha to treat skeletal metastases of other carcinomas.

The influence of alumina and ultra-high molecular weight polyethylene particles on osteoblast-osteoclast cooperation.

Particle-induced macrophage activation, mainly by UHMWPE wear, has been recognized as the biological mechanism leading to periprosthetic bone resorption, which is responsible for the loosening of the total hip replacements (THR). Ceramic-on-ceramic implants have been advocated as a means of reducing wear products. Many studies investigated the effect of alumina (Al(2)O(3)) particles on monocytes/macrophages, but only limited information are available on their participation to bone turnover. An in vitro model was performed to investigate how Al(2)O(3) and UHMWPE particles may influence the osteoblast-osteoclast interaction: human osteoblasts (HOB) were obtained from trabecular bone, while osteoclasts were derived from peripheral blood mononuclear cells (PBMC) of healthy donors. The amount of IL6, TNF alpha, GM-CSF, and other factors acting on the bone turnover, i.e. the 'receptor activator of NF kappa B' ligand (RANKL) and osteoprotegerin (OPG), was detected in culture medium of particle-challenged HOB (HOB-CM). The Al(2)O(3) and UHMWPE particles did not affect either cell viability or TNF and GM-CSF release, while the increase in IL6 release seemed to be dependent on the particle concentration. UHMWPE increased the release of RANKL from HOB, while OPG and OPG-to-RANKL ratio were significantly inhibited. The ability of HOB-CM to promote osteoclastogenesis was tested via osteoblast/monocyte cooperation: after seven days of culture UHMWPE HOB-CM induced a large amount of multinucleated TRAP-positive giant cells, as well as significantly reduced the amount of IL6, GM-CSF and RANKL in the supernatant. With regard to the inductive effect on the osteoclastogenesis, our results show that the Al(2)O(3) wear debris are less active.

Bone-targeted doxorubicin-loaded nanoparticles as a tool for the treatment of skeletal metastases.

Bone metastases contribute to morbidity in patients with common cancers, and conventional therapy provides only palliation and can induce systemic side effects. The development of nanostructured delivery systems that combine carriers with bone-targeting molecules can potentially overcome the drawbacks presented by conventional approaches. We have recently developed biodegradable, biocompatible nanoparticles (NP) made of a conjugate between poly (D,L-lactide-co-glycolic) acid and alendronate, suitable for systemic administration, and directly targeting the site of tumor-induced osteolysis. Here, we loaded NP with doxorubicin (DXR), and analyzed the in vitro and in vivo activity of the drug encapsulated in the carrier system. After confirming the intracellular uptake of DXR-loaded NP, we evaluated the anti-tumor effects in a panel of human cell lines, representative for primary or metastatic bone tumors, and in an orthotopic mouse model of breast cancer bone metastases. In vitro, both free DXR and DXR-loaded NP, (58-580 ng/mL) determined a significant dose-dependent growth inhibition of all cell lines. Similarly, both DXR-loaded NP and free DXR reduced the incidence of metastases in mice. Unloaded NP were ineffective, although both DXR-loaded and unloaded NP significantly reduced the osteoclast number at the tumor site (P = 0.014, P = 0.040, respectively), possibly as a consequence of alendronate activity. In summary, NP may act effectively as a delivery system of anticancer drugs to the bone, and deserve further evaluation for the treatment of bone tumors.