Tumor protein expression of the DNA repair gene BRCA1 and lethal prostate cancer.

DNA repair genes are commonly altered in metastatic prostate cancer, but BRCA1 mutations are rare. Preliminary studies suggest that higher tumor expression of the BRCA1 protein may be associated with worse prognosis. We undertook a prospective study among men with prostate cancer in the Health Professionals Follow-up Study and evaluated BRCA1 via immunohistochemical staining on tissue microarrays. BRCA1 was expressed in 60 of 589 tumors. Prevalence of BRCA1 positivity was 43% in the 14 men with metastases at diagnosis compared with 9% in non-metastatic tumors [difference, 33 percentage points; 95% confidence interval (CI), 7-59]. BRCA1-positive tumors had 2.16-fold higher Ki-67 proliferative indices (95% CI, 1.18-3.95), higher tumor aneuploidy as predicted from whole-transcriptome profiling, and higher Gleason scores. Among the 575 patients with non-metastatic disease at diagnosis, we evaluated the association between BRCA1 expression and development of lethal disease (metastasis or cancer-specific death, 69 events) during long-term follow-up (median, 18.3 years). A potential weak association of BRCA1 positivity with lethal disease (hazard ratio, 1.61; 95% CI, 0.82-3.15) was attenuated when adjusting for age, Gleason score and clinical stage (hazard ratio, 1.11; 95% CI, 0.54-2.29). In summary, BRCA1 protein expression is a feature of more proliferative and more aneuploid prostate tumors and is more common in metastatic disease. While not well suited as a prognostic biomarker in primary prostate cancer, BRCA1 protein expression may be most relevant in advanced disease.

RUNX3 facilitates growth of Ewing sarcoma cells.

Ewing sarcoma is an aggressive pediatric small round cell tumor that predominantly occurs in bone. Approximately 85% of Ewing sarcomas harbor the EWS/FLI fusion protein, which arises from a chromosomal translocation, t(11:22)(q24:q12). EWS/FLI interacts with numerous lineage-essential transcription factors to maintain mesenchymal progenitors in an undifferentiated state. We previously showed that EWS/FLI binds the osteogenic transcription factor RUNX2 and prevents osteoblast differentiation. In this study, we investigated the role of another Runt-domain protein, RUNX3, in Ewing sarcoma. RUNX3 participates in mesenchymal-derived bone formation and is a context dependent tumor suppressor and oncogene. RUNX3 was detected in all Ewing sarcoma cells examined, whereas RUNX2 was detected in only 73% of specimens. Like RUNX2, RUNX3 binds to EWS/FLI via its Runt domain. EWS/FLI prevented RUNX3 from activating the transcription of a RUNX-responsive reporter, p6OSE2. Stable suppression of RUNX3 expression in the Ewing sarcoma cell line A673 delayed colony growth in anchorage independent soft agar assays and reversed expression of EWS/FLI-responsive genes. These results demonstrate an important role for RUNX3 in Ewing sarcoma.

Associations of single nucleotide polymorphisms with malignant and borderline bone tumors.

Bone neoplasms - are a rare group of diseases, which ethiology and pathogenesis are not fully understood. We have studied 6 single nucleotide polymorphisms rs792/(GHI), rs7956547(IGFI), rs3761243(GNRH2), rs11737764(FGF2), rs6599400(FGFR3), and rs1690916(MDM2) associations with bone tumors. In our work we've detected significant associations with some single nucleotide polymorphisms: IGFl.rs7956547, GNRH2.rs3761243 and FGFR3.rs6599400 in patients with malignant and borderline bone tumors.

NAD Synthesis Pathway Interference Is a Viable Therapeutic Strategy for Chondrosarcoma.

Nicotinamide phosphoribosyltransferase (NAMPT) and nicotinic acid phosphoribosyltransferase (NAPRT) are rate-limiting enzymes in the NAD+ synthesis pathway. Chondrosarcoma is a malignant cartilage forming bone tumor, in which mutations altering isocitrate dehydrogenase-1 and -2 (IDH1 and IDH2) activity have been identified as potential driver mutations. Vulnerability for NAD+ depletion has been reported for IDH1/2-mutant cells. Here, the potency of NAMPT inhibitors as a treatment of chondrosarcoma was explored. Eleven chondrosarcoma cell lines were treated with NAMPT inhibitors, in which the effect on cell viability, colony formation, and 3D collagen invasion was assessed. The expression level of NAMPT and NAPRT transcripts in chondrosarcoma cells was determined by qRT-PCR. Methylation of the NAPRT promoter was evaluated using a previously published dataset of genome-wide methylation. In addition, a methylation dataset was used to determine methylation of the NAPRT promoter in 20 IDH1/2-mutated cartilage tumors. Chondrosarcoma cells showed a dose-dependent decrease in cell viability, 3D collagen invasion, and colony formation upon treatment with NAMPT inhibitors, in which nearly half of the cell lines demonstrated absolute IC50s in the low nanomolar range. Increasing IC50s correlated to increasing NAPRT expression levels and decreasing NAPRT promoter methylation. No correlation between IDH1/2 mutation status and sensitivity for NAMPT inhibitors was observed. Strikingly, higher methylation of the NAPRT promoter was observed in high-grade versus low-grade chondrosarcomas. In conclusion, this study identified NAMPT as a potential target for treatment of chondrosarcoma.Implications: Chondrosarcoma patients, especially those of high histologic grade with lower expression and hypermethylation of NAPRT, may benefit from inhibition of the NAD synthesis pathway. Mol Cancer Res; 15(12); 1714-21. ©2017 AACR.

Telomerase activity in benign bone tumors and tumor-like lesions.

To assess the role and status of telomerase activity in benign bone tumors and tumor-like lesions, we performed telomerase assays in four giant cell tumors of bone, four fibrous dysplasias, three osteochondromas, three aneurysmal bone cysts, two osteoblastomas, one juvenile bone cyst and one myositis ossificans. A very sensitive non-radioactive TRAP assay was applied. Low level activity was detected in 7 of 18 tumor samples (38.9%), and high level activity was not detected in any of the cases. Telomerase activity was observed in all patients with osteochondromas, in two of the three aneurysmal bone cysts, in one of the four giant cell tumors of bone and in one of the four fibrous dysplasias, but not in osteoblastomas, juvenile bone cyst and myositis ossificans. Although the origin of this enzyme is still unclear, it might play a role in precancerous immortalization of benign bone tumors. Other possible reasons explaining the occurrence of telomerase activity, such as migrating lymphocytes or contamination of immortalized non-tumor cells, should not be ruled out. Telomerase activity, however, does exist in those samples having no malignant phenotype, for which reason telomerase assays are not always useful for the clinical and diagnostic approach in benign bone tumors. Determination of the telomerase status in benign lesions may contribute to a better understanding of the regulation mechanism of telomerase activity during progression of bone tumors.

Localization of genetic elements of intact and derivative chromosome 11 and 22 territories in nuclei of Ewing sarcoma cells.

Recurring chromosomal abnormalities are associated with specific tumour types. The EWSR1 and FLI1 genes are involved in balanced translocation t(11;22)(q24;q12), which is present in more than 85% of Ewing sarcomas. In our previous study, we have found that the fusion genes pertaining to both derivative chromosomes 11 and 22 in Ewing sarcoma cell nuclei are shifted to the midway nuclear position between the native EWSR1 and FLI1 genes. In this contribution we focused our attention at nuclear positioning of other genetic elements of chromosomes 11 and 22 in order to find if the whole derivative chromosomes or only their translocated parts change their nuclear positions in comparison with the native chromosomes. Using repeated fluorescence in situ hybridization and high-resolution cytometry, 2D radial positions of EWSR1, BCR, FLI1, BCL1 genes and fluorescence weight centres of chromosome territories were compared for intact and derivative chromosomes 11 and 22 in nuclei of three Ewing sarcoma samples. Significant radial shift was obtained for the derivative EWSR1, FLI1 and BCL1 genes and for the derivative chromosome 11 compared with the intact ones and not very significant for chromosome 22 and the BCR gene. Our results also suggest that the mean nuclear positions of fusion genes are determined by the final structure of the derivative chromosomes and do not depend on the location of the translocation event.