SUMOylation is associated with aggressive behavior in chondrosarcoma of bone

Simple Summary SUMO is a ubiquitin-like post-translational modification important for many cellular processes and is suggested to play a role in cancer cell cycle progression. The aim of our study is to understand the role of SUMOylation in tumor progression and aggressiveness. Chondrosarcoma of bone was employed as a model to investigate if SUMOylation contributes to its aggressiveness. We confirmed that SUMO expression levels correlate with aggressiveness of chondrosarcoma and disease outcome. Inhibition of SUMOylation showed promising effects on reduction of chondrosarcoma growth in vitro. Our study implies that SUMO expression could be used as a potential biomarker for disease outcome in chondrosarcoma. Multiple components of the SUMOylation machinery are deregulated in various cancers and could represent potential therapeutic targets. Understanding the role of SUMOylation in tumor progression and aggressiveness would increase our insight in the role of SUMO in cancer and clarify its potential as a therapeutic target. Here we investigate SUMO in relation to conventional chondrosarcomas, which are malignant cartilage forming tumors of the bone. Aggressiveness of chondrosarcoma increases with increasing histological grade, and a multistep progression model is assumed. High-grade chondrosarcomas have acquired an increased number of genetic alterations. Using immunohistochemistry on tissue microarrays (TMA) containing 137 chondrosarcomas, we showed that higher expression of SUMO1 and SUMO2/3 correlates with increased histological grade. In addition, high SUMO2/3 expression was associated with decreased overall survival chances (p = 0. 0312) in chondrosarcoma patients as determined by log-rank analysis and Cox regression. Various chondrosarcoma cell lines (n = 7), especially those derived from dedifferentiated chondrosarcoma, were sensitive to SUMO inhibition in vitro. Mechanistically, we found that SUMO E1 inhibition interferes with cell division and as a consequence DNA bridges are frequently formed between daughter cells. In conclusion, SUMO expression could potentially serve as a prognostic biomarker.MTG6Molecular tumour pathology - and tumour genetic

Inhibition of PARP Sensitizes Chondrosarcoma Cell Lines to Chemo- and Radiotherapy Irrespective of the IDH1 or IDH2 Mutation Status

Chondrosarcomas are chemo- and radiotherapy resistant and frequently harbor mutationsin isocitrate dehydrogenase (IDH1 or IDH2), causing increased levels of D-2-hydroxyglutarate(D-2-HG). DNA repair defects and synthetic lethality with poly(ADP-ribose) polymerase (PARP)inhibition occur in IDH mutant glioma and leukemia models. Here we evaluated DNA repairand PARP inhibition, alone or combined with chemo- or radiotherapy, in chondrosarcoma celllines with or without endogenous IDH mutations. Chondrosarcoma cell lines treated with thePARP inhibitor talazoparib were examined for dose–response relationships, as well as underlyingcell death mechanisms and DNA repair functionality. Talazoparib was combined with chemo- orradiotherapy to evaluate potential synergy. Cell lines treated long termwith an inhibitor normalizingD-2-HG levels were investigated for synthetic lethality with talazoparib. We report that talazoparibsensitivity was variable and irrespective of IDH mutation status. All cell lines expressed AtaxiaTelangiectasia Mutated (ATM), but a subset was impaired in poly(ADP-ribosyl)ation (PARylation)capacity, homologous recombination, andO-6-methylguanine-DNAmethyltransferase (MGMT) expression.Talazoparib synergized with temozolomide or radiation, independent of IDH1 mutant inhibition.This study suggests that talazoparib combined with temozolomide or radiation are promisingtherapeutic strategies for chondrosarcoma, irrespective of IDH mutation status. A subset ofchondrosarcomas may be deficient in nonclassical DNA repair pathways, suggesting that PARPinhibitor sensitivity is multifactorial in chondrosarcoma.Toxicolog

A murine mesenchymal stem cell model for initiating events in osteosarcomagenesis points to CDK4/CDK6 inhibition as a therapeutic target

Osteosarcoma is a high-grade bone-forming neoplasm, with a complex genome. Tumours frequently show chromothripsis, many deletions, translocations and copy number alterations. Alterations in the p53 or Rb pathway are the most common genetic alterations identified in osteosarcoma. Using spontaneously transformed murine mesenchymal stem cells (MSCs) which formed sarcoma after subcutaneous injection into mice, it was previously demonstrated that p53 is most often involved in the transformation towards sarcomas with complex genomics, including osteosarcoma. In the current study, not only loss of p53 but also loss of p16(Ink4a) is shown to be a driver of osteosarcomagenesis: murine MSCs with deficient p15(Ink4b), p16(Ink4a), or p19(Arf) transform earlier compared to wild-type murine MSCs. Furthermore, in a panel of nine spontaneously transformed murine MSCs, alterations in p15(Ink4b), p16(Ink4a), or p19(Arf) were observed in eight out of nine cases. Alterations in the Rb/p16 pathway could indicate that osteosarcoma cells are vulnerable to CDK4/CDK6 inhibitor treatment. Indeed, using two-dimensional (n = 7) and three-dimensional (n = 3) cultures of human osteosarcoma cell lines, it was shown that osteosarcoma cells with defective p16(INK4A) are sensitive to the CDK4/CDK6 inhibitor palbociclib after 72-hour treatment. A tissue microarray analysis of 109 primary tumour biopsies revealed a subset of patients (20-23%) with intact Rb, but defective p16 or overexpression of CDK4 and/or CDK6. These patients might benefit from CDK4/CDK6 inhibition, therefore our results are promising and might be translated to the clinic.Osteosarcoma is a tumour with a highly complex genome, which hampers the identification of driver genes. Using a model of murine mesenchymal stem cells (MSCs) with deficient p15(Ink4b), p16(Ink4a), or p19(Arf) that transform earlier compared to wild-type MSCs, the authors demonstrated that loss of p16(Ink4a) is a driver of osteosarcomagenesis. This can be exploited with a CDK4/CDK6 inhibitor, as osteosarcoma cells showed sensitivity to palbociclib which might be used as a novel therapeutic option.Molecular tumour pathology - and tumour geneticsMTG

Targeting the NAD salvage synthesis pathway as a novel therapeutic strategy for osteosarcomas with low NAPRT expression

For osteosarcoma (OS), the most common primary malignant bone tumor, overall survival has hardly improved over the last four decades. Especially for metastatic OS, novel therapeutic targets are urgently needed. A hallmark of cancer is aberrant metabolism, which justifies targeting metabolic pathways as a promising therapeutic strategy. One of these metabolic pathways, the NAD+ synthesis pathway, can be considered as a potential target for OS treatment. Nicotinamide phosphoribosyltransferase (NAMPT) is the rate-limiting enzyme in the classical salvage pathway for NAD+ synthesis, and NAMPT is overexpressed in OS. In this study, five OS cell lines were treated with the NAMPT inhibitor FK866, which was shown to decrease nuclei count in a 2D in vitro model without inducing caspase-driven apoptosis. The reduction in cell viability by FK866 was confirmed in a 3D model of OS cell lines (n = 3). Interestingly, only OS cells with low nicotinic acid phosphoribosyltransferase domain containing 1 (NAPRT1) RNA expression were sensitive to NAMPT inhibition. Using a publicly available (Therapeutically Applicable Research to Generate Effective Treatments (TARGET)) and a previously published dataset, it was shown that in OS cell lines and primary tumors, low NAPRT1 RNA expression correlated with NAPRT1 methylation around the transcription start site. These results suggest that targeting NAMPT in osteosarcoma could be considered as a novel therapeutic strategy, where low NAPRT expression can serve as a biomarker for the selection of eligible patients.Molecular tumour pathology - and tumour geneticsMTG

High-Throughput Screening of Myxoid Liposarcoma Cell Lines: Survivin Is Essential for Tumor Growth

MTG6Molecular tumour pathology - and tumour genetic

Targeting survivin as a potential new treatment for chondrosarcoma of bone

Chondrosarcomas are malignant cartilage-forming bone tumors, which are intrinsically resistant to chemo- and radiotherapy, leaving surgical removal as the only curative treatment option. Therefore, our aim was to identify genes involved in chondrosarcoma cell survival that could serve as a target for therapy. siRNA screening for 51 apoptosis-related genes in JJ012 chondrosarcoma cells identified BIRC5, encoding survivin, as essential for chondrosarcoma survival. Using immunohistochemistry, nuclear as well as cytoplasmic survivin expression was analyzed in 207 chondrosarcomas of different subtypes. Nuclear survivin has been implicated in cell-cycle regulation while cytoplasmic localization is important for its anti-apoptotic function. RT-PCR was performed to determine expression of the most common survivin isoforms. Sensitivity to YM155, a survivin inhibitor currently in phase I/II clinical trial for other tumors, was examined in 10 chondrosarcoma cell lines using viability assay, apoptosis assay and cell-cycle analysis. Survivin expression was found in all chondrosarcoma patient samples. Higher expression of nuclear and cytoplasmic survivin was observed with increasing histological grade in central chondrosarcomas. Inhibition of survivin using YM155 showed that especially TP53 mutant cell lines were sensitive, but no caspase 3/7 or PARP cleavage was observed. Rather, YM155 treatment resulted in a block in S phase in two out of three chondrosarcoma cell lines, indicating that survivin is more involved in cell-cycle regulation than in apoptosis. Thus, survivin is important for chondrosarcoma survival and chondrosarcoma patients might benefit from survivin inhibition using YM155, for which TP53 mutational status can serve as a predictive biomarker.Toxicolog

HEMATOPOIESIS-SPECIFIC T-CELLS MAY CONTRIBUTE TO GVHD REACTIVITY BY INDUCTION OF COLLATERAL DAMAGE TO NON-HEMATOPOIETIC TISSUES DURING AN ONGOING PROFOUND GVL REACTION

Immunobiology of allogeneic stem cell transplantation and immunotherapy of hematological disease

Haematopoiesis- specific T-cells may induce GvHD via induction of collateral damage to non-haematopoietic cells

Immunobiology of allogeneic stem cell transplantation and immunotherapy of hematological disease

Exploration of the chondrosarcoma metabolome; the mTOR pathway as an important pro-survival pathway

Molecular tumour pathology - and tumour geneticsMTG