Klotho Overexpression Is Frequently Associated With Upstream Rearrangements in Fusion-Negative Phosphaturic Mesenchymal Tumors of Bone and Sinonasal Tract.

Phosphaturic mesenchymal tumors (PMT) are uncommon neoplasms that cause hypophosphatemia/osteomalacia mainly by secreting fibroblast growth factor 23. We previously identified FN1::FGFR1/FGF1 fusions in nearly half of the PMTs and frequent KL (Klotho or α-Klotho) overexpression in only those with no known fusion. Here, we studied a larger cohort of PMTs for KL expression and alterations. By FN1 break-apart fluorescence in situ hybridization (FISH) and reappraisal of previous RNA sequencing data, 6 tumors previously considered "fusion-negative" (defined by negative results of FISH for FN1::FGFR1 fusion and FGF1 break-apart and/or of RNA sequencing) were reclassified as fusion-positive PMTs, including 1 containing a novel FN1::ZACN fusion. The final cohort of fusion-negative PMTs included 33 tumors from 32 patients, which occurred in the bone (n = 18), soft tissue (n = 10), sinonasal tract (n = 4), and brain (n = 1). In combination with previous work, RNA sequencing, RNA in situ hybridization, and immunohistochemistry showed largely concordant results and demonstrated KL/α-Klotho overexpression in 17 of the 28 fusion-negative and none of the 10 fusion-positive PMTs studied. Prompted by a patient in this cohort harboring germline KL upstream translocation with systemic α-Klotho overexpression and multifocal PMTs, FISH was performed and revealed KL rearrangement in 16 of the 33 fusion-negative PMTs (one also with amplification), including 14 of the 17 cases with KL/α-Klotho overexpression and none of the 11 KL/α-Klotho-low fusion-negative and 11 fusion-positive cases studied. Whole genomic sequencing confirmed translocation and inversion in 2 FISH-positive cases involving the KL upstream region, warranting further investigation into the mechanism whereby these rearrangements may lead to KL upregulation. Methylated DNA immunoprecipitation and sequencing suggested no major role of promoter methylation in KL regulation in PMT. Interestingly, KL-high/-rearranged cases seemed to form a clinicopathologically homogeneous group, showing a predilection for skeletal/sinonasal locations and typically matrix-poor, cellular solitary fibrous tumor-like morphology. Importantly, FGFR1 signaling pathways were upregulated in fusion-negative PMTs regardless of the KL status compared with non-PMT mesenchymal tumors by gene set enrichment analysis, perhaps justifying FGFR1 inhibition in treating this subset of PMTs.

Identification of COL1A1/2 Mutations and Fusions With Noncoding RNA Genes in Bizarre Parosteal Osteochondromatous Proliferation (Nora Lesion).

Bizarre parosteal osteochondromatous proliferation (BPOP) (Nora lesion) is a benign bone surface lesion, which most commonly occurs in the digits of young patients and has a high rate of recurrence. Histologically, it is composed of a mixture of disorganized bone, cartilage, and spindle cells in variable proportions and characterized by amorphous "blue bone" mineralization. Recurrent chromosomal abnormalities, including t(1;17)(q32-42;q21-23) and inv(7)(q21.1-22q31.3-32), have been reported in BPOP. However, the exact genes involved in the rearrangements remain unknown. In this study, we analyzed 8 BPOP cases affecting the fingers, toe, ulna, radius, and fibula of 5 female and 3 male patients, aged 5 to 68 years. RNA sequencing of 5 cases identified genetic fusions between COL1A2 and LINC-PINT in 3 cases and COL1A1::MIR29B2CHG fusion in 1, both validated using fluorescence in situ hybridization and reverse transcription (RT)-PCR. The remaining fusion-negative case harbored 3 COL1A1 mutations as revealed by whole-exome sequencing and confirmed using Sanger sequencing. All these genetic alterations were predicted to cause frameshift and/or truncation of COL1A1/2. The chromosomal locations of COL1A2 (7q21.3), LINC-PINT (7q32.3), COL1A1 (17q21.33), and MIR29B2CHG (1q32.2) were consistent with the breakpoints identified in the previous cytogenetic studies. Subsequent screening of 3 BPOPs using fluorescence in situ hybridization identified 1 additional case each with COL1A1 or COL1A2 rearrangement. Our findings are consistent with reported chromosomal abnormalities and implicate the disruption of type I collagen, and perhaps of either noncoding RNA gene as a tumor suppressor, in the tumorigenesis of BPOP. The prevalence and tumorigenic mechanisms of these COL1A1/2 alterations in BPOP require further investigation.

Can imaging distinguish between low-grade and dedifferentiated parosteal osteosarcoma?

BACKGROUND: Most instances of the parosteal osteosarcoma (OGS) are low-grade tumors. However, some parosteal OGSs undergo dedifferentiated transformation. Dedifferentiated parosteal OGS can cause distant metastasis and poor survival, and preoperative chemotherapy may be warranted. This study provides imaging clues for dedifferentiated parosteal OGS before treatment. METHODS: The study retrospectively enrolled 23 patients with histologically proven parosteal OGS, including 69.6% (n = 16) low-grade and 30.4% (n = 7) dedifferentiated types. Preoperative images including radiography and magnetic resonance imaging were reviewed. The following imaging parameters and clinical outcomes were evaluated: 1) average age; 2) sex; 3) tumor size; 4) presence of string sign; 5) necrosis; 6) hemorrhage; 7) solid soft tissue component; 8) perforating vessels; 9) ossification grade; 10) marginal ossification; 11) periosteal reaction; 12) sunburst reaction; 13) bone marrow edema; 14) bone marrow invasion; 15) perifocal soft tissue edema; 16) adjacent joint involvement; 17) adjacent neurovascular bundle compression; 18) regional lymph node; 19) bone metastasis; 20) preoperative lung metastasis; 21) follow-up lung metastasis; and 22) recurrence. RESULTS: The average maximal tumor sizes were 7.1 cm and 10.9 cm in low-grade and dedifferentiated types, respectively (p = 0.033). Sunburst periosteal reaction was visualized in two cases of low-grade type (12.5%) and four cases of the dedifferentiated type (57.1%) (p = 0.025) of parosteal OGS. None of our studied cases revealed preoperative lung metastasis. In the follow-up chest computed tomography, lung metastasis was noted in two cases of conventional type (14.2%), and four cases of dedifferentiated type (57.1%) (p = 0.040) of parosteal OGS. In receiver operating characteristic (ROC) curve analysis, the average tumor size and sunburst periosteal reaction showed good specificity (AUC = 0.070 and 0.072, respectively). CONCLUSION: Compared with low-grade types, dedifferentiated parosteal OGS exhibits a considerably larger tumor size, more sunburst periosteal reaction, and a more frequent development of lung metastasis in the disease course. Tumor size and sunburst periosteal reaction are the most crucial imaging diagnostic factors.

Alveolar soft part sarcoma: Clinical presentation, treatment, and outcome in a series of 13 patients.

BACKGROUND: Alveolar soft part sarcoma (ASPS) is a rare soft tissue tumor that typically affects young patients. Similar to other soft tissue sarcomas, it has high pulmonary metastasis ability, whereas compared with other soft tissue sarcomas, it has high brain metastasis ability. Because of the rarity of the disease, most studies on ASPS have been case reports and small series studies. METHOD: We performed a retrospective study to evaluate the clinical and pathological features and oncological results in a consecutive series of patients with localized or metastatic ASPS treated at our institute between 1994 and 2014. Demographics, location, severity of disease, treatment provided, progression-free survival, and overall survival were evaluated. RESULTS: A total of 13 patients were investigated. The most common locations of primary tumor were the thigh (n = 6, 47%), followed by the flank (n = 3, 23%), forearm (n = 2, 15%), and calf (n = 2, 15%). Three patients were initially diagnosed as having hemangiomas elsewhere. These patients received unplanned intralesional excision. All the patients received wide tumor resection at our institute. Over the average follow-up period of 80.5 months (range: 36-133 months), the 5-year overall survival rate was 67.5%. Four patients were continuously disease free (31%), six were living with disease (46%), and three died of disease (23%). Of nine patients who presented with distant pulmonary metastasis, two had bony and brain metastases. The 5-year survival rate was 66.7% in patients who received chemotherapy and those who did not (p = 0.941). CONCLUSION: The treatment strategy for ASPS is wide resection, and postoperative chemotherapy may be crucial for long-term survival. In addition, this type of tumor has a high distant metastasis rate at the time of diagnosis, particularly in the lungs and brain.

Conditioned medium derived from mesenchymal stem cells overexpressing HPV16 E6E7 dramatically improves ischemic limb.

Mesenchymal stem cells (MSCs) have been shown to secrete cytokines and growth factors required for angiogenesis. Previously, we demonstrated that MSCs expressing HPV16 E6E7 mRNA (E6E7-MSCs) increase life span and differentiation potential and maintain without neoplastic transformation. Whether E6E7-MSCs are sources of molecules for enhancing angiogenesis is unknown. We demonstrated that E6E7-MSC-derived conditioned medium (E6E7-CM) enhanced endothelial cell migration and tube formation compared to primary MSC-derived conditioned medium (primary-CM). Moreover, E6E7-MSCs increased AKT activation and enhanced the release of Interleukin-1ß (IL-1ß) and vascular endothelial growth factor A (VEGFA). Neutralization of E6E7-CM with antibodies against IL-1ß or VEGFA abrogated its effect in enhancing endothelial migration and tube formation. Primary-CM, added with IL-1ß and VEGFA, enhanced its ability to increase endothelial migration and tube formation. E6E7-CM was shown to increase the ability to improve blood perfusion in a mouse limb ischemia model. Histological analysis revealed that E6E7-CM prohibited muscle loss or fibrosis and increased endothelial cell counts compared to primary-CM. Similarly, the effects of E6E7-CM in improving perfusion in ischemic limb were also contributed by the increase of IL-1ß or VEGFA levels. These results suggest that E6E7-MSCs increase the ability to secrete angiogenic factors via AKT activation, and E6E7-CM is abundant in IL-1ß and VEGFA levels and thereby increases the ability to improve blood perfusion and prohibit muscle loss or fibrosis in a mouse limb ischemia model.