Kazuhiro Tanaka

microRNA-93 promotes cell proliferation via targeting of PTEN in Osteosarcoma cells

BackgroundAberrant microRNA (miRNA) expression plays an essential role in osteosarcoma (OS) pathogenesis. Recent studies have shown that dysregulation of miRNA expression is associated with increased tumorigenesis and poor prognosis in several types of cancers, including OS. The aim of this study was to investigate the relevant microRNAs involved in the development of OS.MethodsTo explore possible oncogenic factors in OS, we used a microarray-based approach to profile changes in the expression of miRNAs and their target mRNAs in five OS cell lines and human mesenchymal stem cells (hMSCs). An miRNA, miR-93, was significantly up-regulated, whereas phosphatase and tensin homologue (PTEN) expression was significantly down-regulated in all tested OS cells, when compared with hMSCs.ResultsWhen anti-miR-93 was transfected into OS cell lines, PTEN expression was greatly increased, suggesting that PTEN might be a target of miR-93 in ES cells. The expression of phosphorylated Akt protein, which is known to be inversely correlated with that of PTEN, was significantly down-regulated in anti-miR-93-transfected cells. Furthermore, transfection of anti-miR-93 inhibited the proliferation and cell cycle progression of ES cells. In addition, the down-regulation of miR-93 in these cells significantly suppressed tumor growth in vivo.ConclusionEctopic expression of miR-93 decreased PTEN protein levels. Furthermore, miR-93 increased proliferation and decreased apoptosis in OS cells, whereas its silencing in these cells inhibited such carcinogenic processes. Taking these observations together, miR-93 can be seen to play a critical role in carcinogenesis through suppression of PTEN, and may serve as a therapeutic target for the treatment of OS.

c-Myc Represses Tumor-Suppressive microRNAs, let-7a, miR-16 and miR-29b, and Induces Cyclin D2-Mediated Cell Proliferation in Ewing’s Sarcoma Cell Line

Myc oncogenic transcription factor is known to inhibit tumor suppressive microRNAs (miRNAs), resulting in greater expression of their target protein related to cell cycle, invasion or anti-apoptotic factors in human cancer cells. To explore possible oncogenic factors in Ewing’s sarcoma (ES), we conducted microarray-based approach to profile the changes in the expression of miRNAs and its downstream mRNAs in five ES cell lines and human mesenchymal stem cells (hMSCs). Three miRNAs, let-7a, miR-16 and miR-29b were significantly down-regulated, whereas c-Myc and cyclin D2 (CCND2) were significantly up-regulated in all tested ES cells compared with hMSCs. To verify that let-7a, miR-16 and miR-29b were the targets of c-Myc in ES cell lines, we transfected siRNA against c-Myc and confirmed the coordinate up-regulation of let-7a, miR-16 and miR-29b through the repression of c-Myc. The ES cells transfected with c-Myc-siRNA and let-7a, miR-16 and miR-29b exhibited the inhibition of the cell cycle progression. The increased expression of let-7a, miR-16 and miR-29b resulted in the reduction of CCND2 protein expression. We also demonstrated that c-Myc-siRNA treatment of ES cells was associated with the decreased expression of CCND2 as a down-stream of three miRNAs. Furthermore, the introduction of let-7a, miR-16 and miR-29b in ES cells could inhibit the c-Myc-mediated up-regulation of CCND2 resulted in the prevention of cell cycle progression. In addition, the transfection of let-7a, miR-16 and miR-29b in ES cells suppressed tumor growth ex vivo treatment. These findings suggests that the up-regulation of c-Myc inhibited the expression of let-7a, miR-16 and miR-29b subsequently induced CCND2 expression in ES cells. The present study might identify a novel oncogenic axis that c-Myc regulates the expression of CCND2 via let-7a, miR-16 and miR-29b, leading to the development new therapeutic targets for ES.

Perioperative chemotherapy with ifosfamide and doxorubicin for high-grade soft tissue sarcomas in the extremities (JCOG0304)

OBJECTIVEnThe efficacy of perioperative chemotherapy for soft tissue sarcomas is controversial and only a few prospective studies of pre-operative chemotherapy for soft tissue sarcomas in the extremities have been reported. We therefore carried out Phase II study of perioperative chemotherapy for patients with soft tissue sarcomas in the extremities.nnnMETHODSnPatients with Stage III non-round cell soft tissue sarcomas in the extremities were eligible. The patients were treated with pre-operative chemotherapy consisting doxorubicin 60 mg/m(2) and ifosfamide 10 g/m(2) for three courses. After the tumor resection, two additional courses of the same regimen were carried out.nnnRESULTSnA total of 72 patients were enrolled and 70 patients were eligible. The median age of the patients was 49 years. The major pathological subtypes were synovial sarcoma in 20 and undifferentiated pleomorphic sarcoma in 17 patients. The protocol treatments were completed in 74% of the eligible cases. The 2 and 5-year progression-free survival rates were 75.7% (95% CI, 63.9-84.1%) and 63.8% (95% CI, 51.3-73.9%), respectively. The 5-year overall survival was 82.6% (95% CI, 71.3-89.7%). There was no treatment-related death. Grade 3 or 4 hematological toxicities (leukopenia and neutropenia) were observed in most of the patients.nnnCONCLUSIONSnAlthough the toxicities of the regimen were significant, pre-operative chemotherapy followed by post-operative chemotherapy using doxorubicin and high-dose ifosfamide was feasible. The outcome of the trial for the patients with high-grade soft tissue sarcomas in the extremities was favorable, and this regimen is promising for further investigation. This trial was registered at the UMIN Clinical Trials Registry (www.umin.ac.jp/ctr/) as C000000096.

Tumor-suppressive microRNA-let-7a inhibits cell proliferation via targeting of E2F2 in osteosarcoma cells.

MicroRNAs (miRNAs) regulate cell proliferation and differentiation by silencing gene expression at the post-transcriptional level; moreover, by binding to the complementary sequences within mRNAs in cancer cells, these small non-coding RNA molecules can function as tumor suppressors or oncogenes. Recently, the dysregulation of miRNA expression has been found to be associated with increased tumorigenicity and poor prognosis in several cancer types, including osteosarcoma (OS). To identify potential oncogenic factors in OS, we analyzed changes in the expression profile of miRNAs and its downstream mRNAs in five OS cell lines and human mesenchymal stem cells (hMSCs) by a microarray-based approach. The expression of an miRNA-let‑7a was significantly downregulated and E2F2 was significantly upregulated in all tested OS cells compared with hMSCs. When let-7a was transfected into OS cell lines, the expression of E2F2 in the cells was greatly suppressed, suggesting that E2F2 is a target of miRNA-let-7a in OS cells. The transfection of let-7a further inhibited cell cycle progression and proliferation of OS cells. In addition, let-7a overexpression in OS cells significantly suppressed the tumor growth inxa0vivo. The present study demonstrates the novel mechanism that regulates E2F2 expression via miRNA-let-7a in OS cells. Because E2F2 is pivotal in promoting cell growth through the regulation of several genes, our results might facilitate the development of new therapeutic targets for the treatment of OS.

Tumor suppressive microRNA-138 inhibits metastatic potential via the targeting of focal adhesion kinase in Ewing's sarcoma cells

Short non-coding RNAs, called microRNAs (miRNAs), regulate cell biology by affecting the expression of target genes. However, we know little about the miRNAs regulating the growth and progression of Ewings sarcoma (ES). To identify possible oncogenic factors in ES, we used a microarray-based approach to profile the changes in the expression of miRNAs and the downstream mRNAs in five ES cell lines. One miRNA, miR‑138, was significantly downregulated, whereas the expression of focal adhesion kinase (FAK) was significantly upregulated in all tested ES cells. When miR‑138 was transfected into ES cell lines, the expression of FAK in these cells was greatly suppressed and inhibited the proliferation and mobility of ES cells. Overexpression of miR‑138 in vitro resulted in further inhibition of the cell cycle at the G1 phase and in the induction of anoikis, in a dose- and time-dependent manner. Moreover, miR‑138 overexpression in ES cells significantly suppressed the number of distant metastases in vivo. The data in the present study demonstrates for the first time a novel mechanism that regulates the expression of FAK via miR‑138 in ES cells.

MicroRNA-301a promotes cell proliferation via PTEN targeting in Ewing's sarcoma cells

MicroRNAs (miRNAs) regulate cell proliferation and differentiation by affecting gene expression at the post-transcriptional level by binding to complementary sequences within mRNAs in cancer cells, indicating that miRNAs can function as tumor suppressors or oncogenes. Recent studies showed that dysregulation of miRNA expression was associated with increased tumorigenicity and poor prognosis in several types of cancers, including Ewings sarcoma (ES). To explore possible oncogenic factors in ES, we conducted microarray-based investigation and profiled the changes in miRNA expression and their effects on downstream mRNAs in five ES cell lines and human mesenchymal stem cells (hMSCs). miR-301a was significantly upregulated, while the phosphatase and tensin homolog (PTEN) expression was significantly downregulated in all tested ES cells as compared to hMSCs. When anti-miR-301a was transfected into ES cell lines, PTEN expression was significantly enhanced, suggesting that PTEN might be a target of miR-301a in ES cells. The expression of protein kinase B (Akt), which is inversely correlated with PTEN expression, was significantly downregulated in anti-miR-301a-transfected cells. Additionally, the transfection of anti-miR-301a inhibited ES cell proliferation and cell cycle progression. Furthermore, downregulation of miR-301a in ES cells significantly suppressed tumor growth in vivo. Our results demonstrated the novel mechanism controlling PTEN expression via miR-301a in ES cells. Given that PTEN is a pivotal phosphatase factor that regulates cell cycle progression, apoptosis, and proliferation, these results might lead to development of new ES-related therapeutic targets.

A Randomized Phase II/III Trial of Perioperative Chemotherapy with Adriamycin Plus Ifosfamide Versus Gemcitabine Plus Docetaxel for High-grade Soft Tissue Sarcoma: Japan Clinical Oncology Group Study JCOG1306

A randomized Phase II/III trial was planned to commence in March 2014. Perioperative chemotherapy with adriamycin plus ifosfamide is the current standard treatment for T2bN0M0 high-grade non-round cell soft tissue sarcoma. The purpose of this study is to confirm the non-inferiority of perioperative chemotherapy with gemcitabine and docetaxel to adriamycin plus ifosfamide for patients with T2bN0M0 or any TN1M0 non-round cell soft tissue sarcoma in the extremities and body wall. A total of 140 patients will be accrued from 28 Japanese institutions over 6 years. The primary endpoint in the Phase II part is the proportion of completion of pre-operative chemotherapy without progressive disease and overall survival in the Phase III part. The secondary endpoints are progression-free survival, response rate of pre-operative chemotherapy, pathological response rate, proportion of preservation of diseased limbs, disease control rate and proportion of adverse events. This trial has been registered in the UMIN Clinical Trials Registry as UMIN000013175 [http://www.umin.ac.jp/ctr/index.htm].

Feasibility and efficacy of gemcitabine and docetaxel combination chemotherapy for bone and soft tissue sarcomas: multi-institutional retrospective analysis of 134 patients

BackgroundBone and soft tissue sarcomas (BSTS) are rare malignant tumors. Recently, the combination of gemcitabine and docetaxel (GD) was shown to have activity as second-line setting in BSTS. However, the efficacy as first-line and adjuvant settings and precise profiles of adverse events in Japanese patients are not known yet. In the present study, the feasibility and efficacy of GD in patients with BSTS were investigated.MethodsPatients with BSTS treated with GD in our institutions were retrospectively analyzed. Information regarding clinical features, adverse events, and outcome was collected and statistically studied. Factors related to survival were analyzed using log-rank test and Cox proportional hazard regression method.ResultsA total of 134 patients were analyzed. GD was carried out as adjuvant setting in 9, first-line in 23, second-line in 56, and third-or-greater line in 46 patients. The response rate (RR) for all patients was 9.7%. RR for the patients treated as adjuvant or first-line setting was 18.8%, whereas that as second-or-greater line was 6.9%. The median progression-free survival (PFS) and overall survival (OS) of all patients were 4.8 (95% CI 3.5–6.1) and 16.4 (95% CI 9.8–22.9) months, respectively. Survival tended to be better in the patients treated as first-line than in those treated as second-or-greater line. Multivariate analysis demonstrated that history of prior chemotherapy (pu2009=u20090.046) and response to GD (pu2009=u20090.009) was significantly associated with PFS and OS, respectively. The leucopenia and neutropenia were the most frequent adverse events, and grade 3 or 4 leucopenia and neutropenia were observed in 69.4 and 72.4% of the patients. Grade 2 or 3 pneumonitis was observed in one (0.7%) and four (3.0%) patients, respectively. All the patients with pneumonitis had experienced prior chemotherapy and/or radiotherapy.ConclusionsGD used as both first- and second/later line is effective chemotherapy for a proportion of patients with advanced BSTS. Higher response rate and better outcome was achieved in chemotherapy-naïve patients. This regimen is associated with high incidence of severe hematological toxicity, as well as the risk of severe pneumonitis, especially in pre-treated patients. GD is promising for further analysis by phase III study for the patients with BSTS.

Dendritic cells combined with anti-GITR antibody produce antitumor effects in osteosarcoma

We attempted to enhance the antitumor effects of tumor lysate-pulsed dendritic cells by eliminating regulatory T cells. The combinatorial effects of dendritic cells and agonist anti-glucocorticoid-induced tumor necrosis factor receptor (anti-GITR) antibodies were investigated with respect to enhancement of the systemic immune response, elimination of regulatory T cells, and inhibition of tumor growth. To determine whether the combination of dendritic cells and anti‑GITR antibodies could enhance systemic immune responses and inhibit primary tumor growth in a murine osteosarcoma (LM8) model. We established the following 4 groups of C3H mice (20 mice in total): i), control IgG-treated mice; ii), tumor lysate-pulsed dendritic cell‑treated mice; iii), agonist anti-GITR antibody-treated mice; and iv), agonist anti-GITR antibody- and tumor lysate-pulsed dendritic cell‑treated mice.The mice that received the agonist anti-GITR antibodies and tumor lysate-pulsed dendritic cells displayed inhibited primary growth, prolonged life time, reduced numbers of regulatory T lymphocytes in the spleen, elevated serum interferon-γ levels, increased number of CD8+ T lymphocytes. The mice that received combined therapy had reduced level of immunosuppressive cytokines in tumor tissue and serum. Combining agonist anti-GITR antibodies with tumor lysate-pulsed dendritic cells enhanced the systemic immune response. These findings provide further support for the continued development of agonist anti-GITR antibodies as an immunotherapeutic strategy for osteosarcoma. We suggest that our proposed immunotherapy could be developed further to improve osteosarcoma treatment.

MicroRNA-181c prevents apoptosis by targeting of FAS receptor in Ewing’s sarcoma cells

BackgroundMicroRNAs (miRNAs) are endogenous, small non-coding RNAs that play important roles in multiple biological processes. Here, we show that miRNAs play an important function in the down-regulation of FAS expression in Ewing’s sarcoma (ES) cells.MethodsTo identify and characterize possible oncogenic factors in ES, we employed a microarray-based approach to profile the changes in the expression of miRNAs and their target mRNAs in five ES cell lines and human mesenchymal stem cells (hMSCs).ResultsMiRNA, miR-181c, was significantly up-regulated, whereas FAS receptor expression was significantly down-regulated in all tested ES cells compared with hMSCs. Introducing anti-miR-181c into ES cell lines resulted in an increased expression of FAS2. Additionally, anti-miR-181c prohibited cell growth and cell cycle progression in ES cells. Anti-miR-181c also promoted apoptosis in ES cells. Furthermore, the down-regulation of miR-181c in ES cells significantly suppressed tumor growth in vivo.ConclusionsThese results suggest that unregulated expression of miR-181c could contribute to ES by targeting FAS. Reduction of miR181c increased expression of FAS. This proves that retardation of cell cycle progression removes apoptosis resistance, thereby repressing the growth of Ewing sarcoma. Since FAS signaling is involved in regulation of apoptosis and tumor proliferation, our findings might contribute to new therapeutic targets for ES.