Role of PRPS2 as a prognostic and therapeutic target in osteosarcoma.

AIMS: Osteosarcoma (OS) is the most common primary malignant tumour of the bone. However, further improvement in survival has not been achieved due to a lack of well-validated prognostic markers and more effective therapeutic agents. Recently, the c-Myc-phosphoribosyl pyrophosphate synthetase 2 (PRPS2) pathway has been shown to promote nucleic acid metabolism and cancer cell proliferation in malignant melanoma; phosphorylated mammalian target of rapamycin (p-mTOR) has been upregulated and an effective therapeutic target in OS. However, the p-mTOR-PRPS2 pathway has not been evaluated in OS. METHODS: In this study, the expression level of PRPS2, p-mTOR and marker of proliferation (MKI-67) was observed in a cohort of specimens (including 236 OS cases and 56 control samples) using immunohistochemistry, and the association between expression level and clinicopathological characteristics of patients with OS was analysed. RESULTS: PRPS2 protein level, which is related to tumour proliferation, was higher in OS cells (p=0.003) than in fibrous dysplasia, and the higher PRPS2 protein level was associated with a higher tumour recurrence (p=0.001). In addition, our statistical analysis confirmed that PRPS2 is a novel, independent prognostic indicator of OS. Finally, we found that the expression of p-mTOR was associated with the poor prognosis of patients with OS (p<0.05). CONCLUSIONS: PRPS2 is an independent prognostic marker and a potential therapeutic target for OS.

Glandular differentiation in dedifferentiated chondrosarcoma: molecular evidence of a rare phenomenon.

Epithelial glandular differentiation in dedifferentiated chondrosarcoma has not been described. Our patient was a 64-year-old man with a history of prostate cancer status post-radiation and hormonal therapy. On screening bone scan, he was found to have increased uptake in his right femoral shaft. Biopsy revealed intermediate-grade conventional chondrosarcoma. Subsequent femoral resection was remarkable for an intermediate-grade chondrosarcomatous component juxtaposed to an area composed of anastomosing nests and cords of malignant epithelial cells showing nuclear atypia and increased mitotic activity. A fibroblastic-appearing spindle cell population was intimately associated with the epithelial cells. The epithelial cells labeled with 34bE12, AE1/AE3, EMA, and Vimentin (both spindled and epithelial components) while being negative for prostate-specific antigen, prostate specific acid phosphatase, cytokeratin 20, thyroid transcription factor-1, and CDX2. The patient developed local recurrence 9 months after the initial resection but has had no metastatic disease and consistently undetectable prostate-specific antigen levels. Deep parallel sequencing of the dedifferentiated component showed a nonsynonymous mutation at exon 4 of IDH1 gene at codon R132 leading to a substitution of arginine, with serine confirming glandular differentiation in dedifferentiated chondrosarcoma.

Xanthoma of bone associated with lipoprotein lipase deficiency.

Lipoprotein lipase (LPL) deficiency is an extremely rare congenital metabolic disorder with an accumulation of chylomicrons in the blood. We encountered a patient with an LPL deficiency leading to multiple bone xanthomas associated with hyperlipidemia. Radiographs and MRI of the humerus and femur revealed symmetrical bone lesions, and there is a possibility that these symmetrical lesions may therefore be a characteristic feature for this disorder.

[The comparative biochemical and morphological characteristics of chondrosarcoma and giant-cell tumor of the bone]. / Sravnitel'naia biokhimicheskaia i morfologicheskaia kharakteristika khondrosarkomy i gigantokletochnoi opukholi kosti.

Spectrometry has been employed to assess the levels of collagenase, catepsin D, trypsin-like proteinases and their inhibitors as well as bone acid and alkaline phosphatase both in the center and along the periphery of giant cell tumor of bone (GCTB) and chondrosarcoma. The levels of collagenase, trypsin-like proteinases and their inhibitors in the center of chondrosarcoma were much higher while those of alkaline phosphatase--lower than along tumor periphery. The catepsin D and acid phosphatase concentrations of the center and periphery of chondrosarcoma were similar. It was suggested that an extremely low concentration of trypsin-like inhibitors may contribute to degradation of the matrix in tissues adjacent to chondrosarcoma and, consequently, to tumor invasion development.

Treatment of femoral Ewing's sarcoma.

BACKGROUND: The treatment of Ewing's sarcoma consists of chemotherapy for systemic and local disease. However, the role of radiation therapy, and/or surgical resection for definitive local treatment has yet to be determined. METHODS: A retrospective review of 32 patients (24 males and 8 females) treated for femoral Ewing's sarcoma between 1970 and 1985 was performed. Patients were divided into 3 treatment groups: chemotherapy and radiotherapy (CR) (10); chemotherapy and surgery (CS) (9); and chemotherapy, surgery, and radiotherapy (CSR) (13). Patients in the CR group received a mean of 5320 centigray (cGy) of radiation and patients in the CSR group received a mean of 3590 cGy. Multiagent cyclophosphamide/doxorubicin based chemotherapy was used in all cases. Surgery consisted of wide resection or amputation. RESULTS: Patients in the CR group had a higher risk of local recurrence than patients in the CS and CSR groups (P=0.02, log rank). The combination of local recurrences and treatment complications necessitated surgery for 7 of 10 CR patients, whereas 1 of 9 and 4 of 13 in the CS and CSR groups required additional surgery. The median survival for the entire group was 39 months. Minimum follow-up for surviving patients was 45 months. Five-year survival consisted of 1 of 10 patients in the CR group, 2 of 9 in the CS group, and 7 of 13 in the CSR group. There were no statistically significant differences among the three survival curves. Tumor location within the femur was a significant prognostic variable. Distal femoral location had a survival advantage compared with proximal and mid-femur locations (P = 0.049, log rank). CONCLUSIONS: Femoral Ewing's sarcoma remains a disease with a poor prognosis. Radiation alone for local treatment results in a high rate of local recurrence and complications. Our current local treatment strategy for femoral Ewing's sarcoma includes surgery in all and adjuvant radiotherapy in many of the patients.

High alkaline phosphatase activity of telangiectatic osteosarcoma (TOS) and its diagnostic significance.

Telangiectatic osteosarcoma (TOS) which occurred in the metaphysis of the right femoral bone in a 13-year-old female was reported. It showed osteolytic and cystic lesion without sclerotic change on roentgenogram and consisted histologically of various sized blood-filled spaces lined by layers of round to oval tumor cells in the thin fibrous septa. In some solid areas, a proliferation of atypical tumor cells with large prominent nucleoli was evident, embedded in the lace-like osteoid tissue. Mitotic cells were easily encountered. A large population of tumor cells revealed high alkaline phosphatase activity as well as 5'-nucleotidase activity, indicative of osteogenic cell origin. Ultrastructurally, they showed osteogenic characteristics of well-developed rough endoplasmic reticula, cytoplasmic microfibrils, and dense bodies, but not for those of endothelial cells. In this report, we suggest that alkaline phosphatase activity in biopsy and surgical specimens is useful for distinguishing TOS from other osteolytic bone tumors, with regard to its ontogenic discussion.

Human osteogenic sarcoma: fine structural localization of adenosine triphosphatase.

The localization of ATPases in 7 osteogenic sarcomas of osteoblastic, chondroblastic and fibroblastic type was investigated at the fine structural level using two types of substrates: one with lead as capturing ion and one with strontium (the latter presumed to reveal sites of Na+-K+-dependent transport ATPase). Reaction product with the lead-ATP medium was located on the plasma membrane and the membranes bordering subjacent vesicles and vacuoles in all the various types of osteoblastlike and fibroblastlike cells and also in types 1 and 3 chondroblastlike cells, and multinucleated giant cells believed to be neoplastic. Furthermore, deposits of reaction product were demonstrated in lysosomelike organelles in all the aforementioned cells. Except in the case of chondroblastlike cells, precipitates marking the localization of enzyme were confined to areas of the plasma membrane where adjacent cells were closely applied (the free surface lacked precipitates). In chondroblastlike cells the reaction product was usually deposited along the whole plasma membrane. Presence of L-Homoarginine or L-Tetramisole in the incubation medium in concentrations that have been shown to completely abolish alkaline phosphatase activity did not affect the occurrence of the reaction product with ATP as substrate indicating that the enzyme hydrolysing ATP was substrate-specific. Reaction product marking sites of Na+-K+-dependent ATPase was confined to plasma membranes and lysosomes of cells in vessel walls. The observations strengthen the notion obtained in studies on the localization of alkaline phosphatase, namely that osteoblastlike, chondroblastlike, and fibroblastlike cells in osteogenic sarcomas are histogenetically related to one another and to those multinucleated giant cells that presumably are of a neoplastic nature.

Microphotometric quantitation of enzyme activities in giant cell tumor of bone. A case study.

In a proliferating giant cell tumor of bone the activities of tartrate-resistant acid phosphatase (acPase) and of NADH-tetrazolium reductase were demonstrated by enzyme histochemical methods. Quantitative microphotometry made it possible to determine the relative enzyme activities per given volume unit in the cytoplasm of giant cells of several sizes. The activity of tartrate-resistant acid phosphatase increases with increasing cell size, whereas the activity of tetrazolium reductase will decrease in proportion. This coincidence of high acPase activity and low tetrazolium reductase activity in larger giant cells is interpreted as an expression of degenerative change.

The ultrastructural localization of secretory acid phosphatase in giant cell tumor of bone.

Three cases of giant cell tumor of bone were studied with the light and electron microscopes to determine the histochemical and cytochemical distribution of acid phosphatase isoenzymes. Using beta-glycerophosphate as a nonspecific substrate, acid phosphatase was found in the giant cells as well as the stromal cells. Ultrastructurally, using this substrate, the enzyme was found to be associated with lysosomes in the stromal cells and giant cells and also with the profuse system of tubules and vesicles in the cytoplasm of the giant cells. Using phosphorylcholine and D-ephedrinephosphate, which are substrates for a specific secretory isoenzyme of acid phosphatase, activity was found only in the vesicles of the giant cell cytoplasm. Lysosomes did not show activity with these substrates. Multinucleated cells of giant cell tumor contain a specific secretory type of acid phosphatase which is not present in the stromal cells. This suggests that the giant cells are attempting to form a secretory system similar to osteoclasts and that the vesicles in the cytoplasm which contain this acid phosphates are the morphologic expression of an abortive secretory system.

Giant cell tumor of bone: fine structural localization of acid phosphatase.

The fine structural localization of acid phosphatase in the different cells in a benign giant cell tumor of bone has been studied. Stromal cells type 1 and 2 (fibroblast-like and macrophage-like, respectively) showed the presence of lead phosphate precipitate following incubation in a Gomori-type lead salt medium only in conventional lysosomes. In the multinucleated giant cells, the final product was deposited over lysosome-like organelles, and also over Golgi cisternae, vesicles, and vacuoles. Furthermore, evidence for presence of acid phosphatase was obtained in smooth-surfaced tubular, sausage-, horse-shoe-, and ring-shaped structures and over digestive vacuoles of autophagic or heterophagic origin. Finally, in these cells, many of the tubular and vacuolar elements located subjacent to areas of the plasma membrane with microvillous specializations (abortive brush borders?) were shown to carry acid phosphatase.