Michiyuki Hakozaki

Prognostic significance of AKT/mTOR and MAPK pathways and antitumor effect of mTOR inhibitor in NF1-related and sporadic malignant peripheral nerve sheath tumors

Purpose: Malignant peripheral nerve sheath tumor (MPNST) is a rare soft tissue sarcoma with poor prognosis. MPNSTs occur frequently in patients with neurofibromatosis type 1 (NF1), in which NF1 gene deficiency leads to Ras hyperactivation. Ras activation causes the subsequent activation of the AKT/mTOR and Raf/MEK/ERK pathways and regulates cellular functions. However, the activation profiles of the AKT/mTOR and MAPK pathways in MPNSTs are poorly understood. The purposes of this study are to examine the correlation between the activation of these pathways and clinicopathologic or prognostic factors and to identify candidate target molecules in MPNST. Moreover, we assessed the antitumor effects of the inhibitor of candidate target. Experimental Design: Immunohistochemistry was conducted to evaluate the activation profiles of AKT/mTOR and MAPK pathways using 135 tumor specimens. Immunohistochemical expressions were confirmed by Western blotting. Then, an in vitro study was conducted to examine the antitumor effect of the mTOR inhibitor on MPNST cell lines. Results: Phosphorylated-AKT (p-AKT), p-mTOR, p-S6RP, p-p70S6K, p-4E-BP1, p-MEK1/2, and p-ERK1/2 expressions were positive in 58.2%, 47.3%, 53.8%, 57.1%, 62.6%, 93.4%, and 81.3% of primary MPNSTs, respectively. Positivity for each factor showed no difference between NF1-related and sporadic MPNSTs. Univariate prognostic analysis revealed that p-AKT, p-mTOR, and p-S6RP expressions were associated with poor prognosis. Furthermore, activation of each p-mTOR and p-S6RP was an independent poor prognostic factor by multivariate analysis. mTOR inhibition by Everolimus showed antitumor activity on MPNST cell lines in vitro. Conclusion: mTOR inhibition is a potential treatment option for both NF1-related and sporadic MPNSTs. Clin Cancer Res; 19(2); 450–61. ©2012 AACR.

Radiological and pathological characteristics of giant cell tumor of bone treated with denosumab

We describe a case of giant cell tumor of the proximal tibia with skip bone metastases of the ipsilateral femur in a 20-year-old man. After the neoadjuvant treatment with denosumab, plain radiographs and computed tomography showed marked osteosclerosis and sclerotic rim formation, and 18F-FDG PET/CT showed a decreased standardized uptake value, whereas magnetic resonance imaging showed diffuse enhancement of the tumor, nearly the same findings as those at pretreatment. Pathological findings of the surgical specimen after the denosumab treatment showed benign fibrous histiocytoma-like features with complete disappearance of both mononuclear stromal cells and multinuclear osteoclast-like giant cells.Virtual SlidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1090602085125068

Expression and regulation of toll-like receptors (TLRs) in human intervertebral disc cells.

PurposeAlthough inflammatory processes play an essential role in painful intervertebral disc (IVD) degeneration, the underlying regulatory mechanisms are not well understood. This study was designed to investigate the expression, regulation and importance of specific toll-like receptors (TLRs)—which have been shown to play an essential role e.g. in osteoarthritis—during degenerative disc disease.MethodsThe expression of TLRs in human IVDs was measured in isolated cells as well as in normal or degenerated IVD tissue. The role of IL-1β or TNF-α in regulating TLRs (expression/activation) as well as in regulating activity of down-stream pathways (NF-κB) and expression of inflammation-related genes (IL-6, IL-8, HSP60, HSP70, HMGB1) was analyzed.ResultsExpression of TLR1/2/3/4/5/6/9/10 was detected in isolated human IVD cells, with TLR1/2/4/6 being dependent on the degree of IVD degeneration. Stimulation with IL-1β or TNF-α moderately increased TLR1/TLR4 mRNA expression (TNF-α only), and strongly increased TLR2 mRNA expression (IL-1β/TNF-α), with the latter being confirmed on the protein level. Stimulation with IL-1β, TNF-α or Pam3CSK4 (a TLR2-ligand) stimulated IL-6 and IL-8, which was inhibited by a TLR2 neutralizing antibody for Pam3CSK4; IL-1β and TNF-α caused NF-κB activation. HSP60, HSP70 and HMGB1 did not increase IL-6 or IL-8 and were not regulated by IL-1β/TNF-α.ConclusionWe provide evidence that several TLRs are expressed in human IVD cells, with TLR2 possibly playing the most crucial role. As TLRs mediate catabolic and inflammatory processes, increased levels of TLRs may lead to aggravated disc degeneration, chronic inflammation and pain development. Especially with the identification of more endogenous TLR ligands, targeting these receptors may hold therapeutic promise.

Identification and Metastatic Potential of Tumor-Initiating Cells in Malignant Rhabdoid Tumor of the Kidney

Purpose: Malignant rhabdoid tumor of the kidney (MRTK) is a rare and highly aggressive malignancy of infanthood. In an effort to delineate MRTK progression, we investigated the metastatic fate of some MRTK cells using xenotransplantation animal models and the tumor-initiating potential of CD133+ MRTK cells. Experimental Design: We established two MRTK cell lines (JMU-RTK-1 and JMU-RTK-2) from patients with MRTK. We generated five luciferase-expressing MRTK cells for in vivo luminescent imaging and evaluated the metastatic fate in an orthotopic xenotransplantation model. Capacities of MRTK-initiating cells were examined in nonobese diabetic/severe combined immunodeficient mice after antibody-mediated magnetic bead sorting. Use of chemokine receptor CXCR4 expression as a metastatic marker was evaluated by flow cytometry and Western blotting. Results: MRTK cell lines showed distant organ metastasis. JMU-RTK-1, JMU-RTK-2, and G401 cells showed considerable aggressiveness compared with SWT-1 and SWT-2 cells (P < 0.05). Moreover, as few as 1,000 CD133+ MRTK cells initiated tumor development in nonobese diabetic/severe combined immunodeficient mice by 21 days (60-100%) in all examined cell lines, although the same number of CD133− MRTK cells could not form tumors (0%). Interestingly, the metastatic potential of the CD133+ population remained unaffected compared with a nonenriched population. The potential metastatic marker CXCR4 was expressed in CD133+ and CD133− MRTK cells, and CD133− cells seemed to play a cooperative role in terms of tumorigenicity and metastasis. Conclusions: These results suggest that CD133+ cells may determine the metastatic fate of MRTK cells and that CD133− cells may play an auxiliary role in tumor progression and metastasis.

Imatinib mesylate inhibits cell growth of malignant peripheral nerve sheath tumors in vitro and in vivo through suppression of PDGFR-β

BackgroundMalignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive and associated with poor prognosis. Basic research to develop new treatment regimens is critically needed.MethodsThe effects of imatinib mesylate on MPNSTs were examined in six human MPNST cell lines and in a xenograft mouse model.ResultsThe results showed expression of platelet-derived growth factor receptor-β and suppression of its phosphorylation by imatinib mesylate in all six cell lines. Imatinib mesylate effectively suppressed MPNST cell growth in vitro at concentrations similar to those used clinically (1.46 − 4.6 μM) in three of six cell lines. Knockdown of PDGFR-β by transfection with a specific siRNA also caused significant reduction in cell proliferation in the sensitive cell lines, but not in the resistant cell lines. Furthermore, imatinib mesylate also significantly suppressed colony formation within soft agar and tumor growth in xenograft models using two of the three sensitive MPNST cell lines. There was excellent agreement between in vitro and in vivo sensitivity to imatinib mesylate, suggesting possible selection of imatinib-sensitive tumors by in vitro analysis.ConclusionsThe results suggest that imatinib mesylate may be useful in the treatment of MPNST patients and in vitro studies may help select cells that are sensitive to imatinib mesylate in vivo.

Remitting seronegative symmetrical synovitis with pitting edema syndrome caused by crystal-induced arthritis of the wrist: a case report.

Objective: To describe a rare case of remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome caused by gouty arthritis. Clinical Presentation and Intervention: A 76-year-old man presented with swelling and pain in the dorsum of feet and hands bilaterally. From the laboratory and radiologic findings, the diagnosis of gout-induced RS3PE syndrome was made. Conservative therapy with nonsteroidal anti-inflammatory drugs (NSAIDs) and intra-articular corticosteroid injection in the wrist joint completely and rapidly resolved all symptoms. The patient was successfully treated with oral administration of NSAIDs and a one-time intra-articular corticosteroid injection in the left wrist joint. Conclusion: This case demonstrated the importance of considering the possibility of crystal-induced arthritis such as gout and pseudogout, as well as malignant disease, when diagnosing the primary disease responsible for RS3PE syndrome.

Intramuscular Castleman’s disease of the deltoid: a case report and review of the literature

Castleman’s disease (CD), a rare benign disease characterized by lymphoid hyperplasia, typically arises in the mediastinum as a solitary tumor. We describe herein a rare case of intramuscular CD occurring in the left deltoid in a 28-year-old woman. The present case is instructive in the differential diagnosis of primary soft tissue tumors, for which the possibility of CD should be considered.

Overexpression of Cyclooxygenase-2 in Malignant Peripheral Nerve Sheath Tumor and Selective Cyclooxygenase-2 Inhibitor-Induced Apoptosis by Activating Caspases in Human Malignant Peripheral Nerve Sheath Tumor Cells

Background Cyclooxygenase-2 (COX-2) is a key enzyme in the conversion of arachidonic acid to prostanoids, and its activation is associated with carcinogenesis as well as inflammation. The antitumor effect of selective COX-2 inhibitors has been noted in various malignancies. Malignant peripheral nerve sheath tumor (MPNST) is a rare and aggressive soft tissue sarcoma for which effective treatments have not yet been established. The purpose of this study was to investigate a potential therapeutic role of COX-2 in MPNST. Methods We evaluated the expression of COX-2 in 44 cases of high-grade MPNST using immunohistochemical staining and compared the staining results with the characteristics and outcome of the patients. We also investigated the antitumor effect of etodolac, a selective COX-2 inhibitor, on MPNST cells in vitro using the MPNST cell line, FMS-1. Results Overexpression of COX-2 (≥50% positive cells) was observed in 29 cases (65.9%), was significantly associated with a poor overall survival (P = 0.0495), and was considered an independent risk factor for a poor outcome by the results of both univariate and multivariate analysis. Etodolac induced apoptosis of FMS-1 cells through the activation of caspase-8, -9, and -3. Moreover, several caspase inhibitors significantly inhibited etodolac-induced apoptosis. Conclusions Selective COX-2 inhibitors including etodolac had an antitumor effect on MPNST cells, and their use holds promise as a novel therapeutic strategy for patients with MPNST to improve their prognoses.

Phosphorylation of STAT3 in Undifferentiated Pleomorphic Sarcoma Is Correlated with a Favorable Prognosis

Objective: The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway plays a role in various biological processes. Phosphorylated STAT3 (p-STAT3) functions as a transcriptional factor, and suppressor of cytokine signaling 3 (SOCS3) is a potential inhibitor of STAT3. Here, we analyzed the status of the JAK-STAT pathway in undifferentiated pleomorphic sarcoma (UPS). Methods: We performed immunohistochemistry in 79 samples of UPS and Western blotting in 10 frozen samples. We also examined alterations in protein expression in the JAK-STAT pathway after the inhibition of phosphorylated Akt (p-Akt) or extracellular signal-regulated kinase (p-Erk) in vitro. Results: Immunohistochemically, p-STAT3 and SOCS3 were positive in 59.7 and 55.8%, respectively. Positivity for p-STAT3 was significantly correlated with a better prognosis (p = 0.0006) and negatively with SOCS3 expression (p = 0.0223). Positivity for SOCS3 was significantly correlated with a worse prognosis (p = 0.0001). Western blotting analysis revealed that p-STAT3 expression was lower in tumor than in normal tissue. In vitro results demonstrated that there was no detectable change in the expression of p-STAT3 regardless of the status of p-Akt or p-Erk. Conclusion: p-STAT3 may be a useful prognostic factor for UPS.

Missed causative tumors in diagnosing tumor-induced osteomalacia with (18)F-FDG PET/CT: a potential pitfall of standard-field imaging.

OBJECTIVE We describe herein two tumor-induced osteomalacia (TIO) cases for whom the causative lesions, located in their popliteal fossa, that were not identified in the standard field of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT), which usually images only the head, trunk, and proximal parts of the extremities. CLINICAL PRESENTATION AND INTERVENTION A 47 years old Japanese man with multiple pathological fractures due to osteomalacia, accompanied by muscle weakness, hypophosphatemia, and an elevation of alkaline phosphatase (ALP) was referred to our hospital. A (18)F-FDG PET/CT scan was performed, but no (18)F-FDG uptake was detected in the standard field of imaging. Magnetic resonance imaging revealed a small subcutaneous tumor (1.9×1.2×0.6cm) of the left posteriomedial knee, displaying uniform enhancement on gadolinium-enhanced T1-weighted fat-suppression imaging. The tumor was resected widely and diagnosed as phosphaturic mesenchymal tumor, mixed connective tissue variant (PMTMCT). The other patient was a 31 years old Japanese woman with multiple pathological fractures, hypophosphatemia and elevated of ALP and was referred to our hospital on suspicion of TIO. Although the causative lesion was not identified in the standard field of (18)F-FDG PET/CT, (18)F-FDG uptake (SUVmax 2.9) was detected on the right knee in the additional whole-body (18)F-FDG PET/CT. Magnetic resonance imaging revealed a soft-tissue tumor (6.4×4.1×2.9cm) in the right posterior knee. Following biopsy, the tumor was marginally resected, and was pathologically diagnosed as PMTMCT. CONCLUSION Once patients are suspected to have TIO, a whole-body nuclear imaging study such as (18)F-FDG PET/CT should be performed, in order not to miss the hidden causative tumor, especially occurring in the distal extremities.