Naomasa Ishida

SOX2 suppresses CDKN1A to sustain growth of lung squamous cell carcinoma

Since the SOX2 amplification was identified in lung squamous cell carcinoma (lung SCC), SOX2 transcriptional downstream targets have been actively investigated; however, such targets are often cell line specific. Here, in order to identify highly consensus SOX2 downstream genes in lung SCC cells, we used RNA-seq data from 178 lung SCC specimens (containing tumor and tumor-associated cells) and analyzed the correlation between SOX2 and previously-reported SOX2-controlled genes in lung SCC. In addition, we used another RNA-seq dataset from 105 non-small cell lung cancer cell lines (NSCLC; including 4 lung SCC cell lines) and again analyzed the correlation between SOX2 and the reported SOX2-controlled genes in the NSCLC cell lines (no tumor-associated cells). We combined the two analyses and identified genes commonly correlated with SOX2 in both datasets. Among the 99 genes reported as SOX2 downstream and/or correlated genes, we found 4 negatively-correlated (e.g., CDKN1A) and 11 positively-correlated genes with SOX2. We used biological studies to demonstrate that CDKN1A was suppressed by SOX2 in lung SCC cells. G1 cell cycle arrest induced by SOX2 siRNA was rescued by CDKN1A siRNA. These results indicate that the tumorigenic effect of SOX2 in lung SCC cells is mediated in part by suppression of CDKN1A.

A novel PI3K inhibitor iMDK suppresses non-small cell lung Cancer cooperatively with A MEK inhibitor.

The PI3K-AKT pathway is expected to be a therapeutic target for non-small cell lung cancer (NSCLC) treatment. We previously reported that a novel PI3K inhibitor iMDK suppressed NSCLC cells in vitro and in vivo without harming normal cells and mice. Unexpectedly, iMDK activated the MAPK pathway, including ERK, in the NSCLC cells. Since iMDK did not eradicate such NSCLC cells completely, it is possible that the activated MAPK pathway confers resistance to the NSCLC cells against cell death induced by iMDK. In the present study, we assessed whether suppressing of iMDK-mediated activation of the MAPK pathway would enhance anti-tumorigenic activity of iMDK. PD0325901, a MAPK inhibitor, suppressed the MAPK pathway induced by iMDK and cooperatively inhibited cell viability and colony formation of NSCLC cells by inducing apoptosis in vitro. HUVEC tube formation, representing angiogenic processes in vitro, was also cooperatively inhibited by the combinatorial treatment of iMDK and PD0325901. The combinatorial treatment of iMDK with PD0325901 cooperatively suppressed tumor growth and tumor-associated angiogenesis in a lung cancer xenograft model in vivo. Here, we demonstrate a novel treatment strategy using iMDK and PD0325901 to eradicate NSCLC.

False-Positive Cases of Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomographic Scans in Metastasis of Esophageal Cancer

Of 129 esophagectomies at our institute from June 2010 to March 2015, we experienced three preoperative positron emission tomography-computed tomographic (PET/CT) false positives. Bone metastasis was originally suspected in 2 cases, but they were later found to be bone metastasis negative after a preoperative bone biopsy and clinical course observation. The other cases suspected of mediastinal lymph node metastasis were diagnosed as inflammatory lymphadenopathy by a pathological examination of the removed lymph nodes. Conducting a PET/CT is useful when diagnosing esophageal cancer metastasis, but we need to be aware of the possibility of false positives. Therapeutic decisions should be made based on appropriate and accurate diagnoses, with pathological diagnosis actively introduced if necessary.

Abstract 2085: Development of a novel targeted therapy for malignant mesothelioma carcinoma by a midkine inhibitor

Malignant pleural mesothelioma is an aggressive tumor of mesenchymal origin and is increasing worldwide as a result of widespread exposure to asbestos. The median survival of patients with mesothelioma from time of diagnosis ranges between 1 and 2 years. The mortality is expected to increase, at least until 2020, which is mainly due to the long latency (30-50 years) of the disease. Despite considerable advances in the understanding of its pathogenesis and etiology, malignant mesothelioma remains largely unresponsive to standard modalities of cancer therapy. Thus, there is an urgent need for new therapeutic options for mesothelioma.Midkine (MDK) is a heparin-binding growth factor that is highly expressed in many malignant tumors, including lung cancers. We have previously reported that a MDK inhibitor, iMDK, suppresses non-small cell lung cancer expressing MDK without harming normal cells. Importantly, iMDK inhibits the PI3 kinase / Akt pathway and induces apoptosis in MDK expressing non-small cell lung cancer cells. In the present study, we have investigated the antitumor effect of iMDK against malignant mesothelioma both in vitro and in vivo. 48 hours after treatment, iMDK dose-dependently inhibited cell growth of MDK expressing malignant mesothelioma cells. iMDK also suppressed colony formation of MSTO-211H mesothelioma cells. TUNEL positive cells were significantly increased in MSTO-211H cells 48 hours after iMDK treatment in a dose-dependent manner, confirming the induction of apoptosis in mesothelioma cells by iMDK. Combination treatment of iMDK and Bcl-2 inhibitor ABT-263 is more effective than each drug alone in MSTO-211H mesothelioma cells. Moreover, systemic administration of iMDK significantly inhibited tumor growth in a mesothelioma xenograft tumor in vivo. Inhibition of MDK with iMDK provides a potential therapeutic approach for the treatment of malignant mesothelioma that is driven by MDK. Citation Format: Takuya Fukazawa, Yuitaka Maeda, Tomoki Yamatsuji, Munenori Takaoka, Masakazu Yoshida, Naomasa Ishida, Miki Iwai, Etsuko Yokota, Takuro Yukawa, Minoru Haisa, Noriko Miyake, Tomoko Ikeda, Nagio Takigawa, Jeffery Whitsett, Yoshio Naomoto. Development of a novel targeted therapy for malignant mesothelioma carcinoma by a midkine inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2085. doi:10.1158/1538-7445.AM2017-2085

Abstract 2694: Esophageal cancer exhibits a resistance to the chemical inhibition of IGF-1R with a maintained Ras-MAPK activity

The type 1 insulin-like growth factor receptor (IGF-1R) and its associated signaling system play a significant role in carcinogenesis and progression of gastrointestinal malignancies, and thus have provoked great interest as a promising target for cancer treatment. The aim of our study was to assess the effects of a novel IGF-1R inhibitor, NVP-AEW541, on the cell proliferation and signal transduction of esophageal squamous cell carcinoma. Five human esophageal squamous carcinoma cell lines (TE-1, TE-4, TE-8, TE-10 and T.Tn) were treated with this inhibitor and the IC50 of NVP-AEW541 for each cell line was more than 1μM, exhibiting that these cells were less sensitive to this compound. The activation of IGF-1R and AKT were dose dependently blocked by NVP-AEW541. However, the activities of the key molecules in Ras-MAPK pathway was not significantly inhibited by NVP-AEW541 without any major mutation of Ras. These results indicate that esophageal squamous cell carcinoma may be resistant to targeting IGF-IR due to its maintenance of Ras-MAPK signaling. Thus, to explore the potential mechanism of resistance will contribute to the therapeutic application for NVP-AEW541. Citation Format: Munenori Takaoka, XiaoHong Bao, Huifang Hao, Naomasa Ishida, Takuya Fukazawa, Tomoki Yamatsuji, Minoru Haisa, Yoshio Naomoto. Esophageal cancer exhibits a resistance to the chemical inhibition of IGF-1R with a maintained Ras-MAPK activity. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2694. doi:10.1158/1538-7445.AM2015-2694

Abstract 3616: Development of a Sox2 targeting therapy for the treatment of lung squamous cell carcinoma

Despite the recent development of several effective molecular targeted agents, lung cancer is the most common cause of cancer related deaths worldwide. Recently, molecular targeted therapies for pulmonary adenocarcinoma with mutant EGFR or ALK fusions have reduced non-tumor toxicity and have extended patient survival time compared to conventional chemotherapies. However, the development of molecular targeting drugs for NSCLC has made apparent the fact that histology is an important factor and molecularly targeted therapies have been more effective in pulmonary adenocarcinoma than in lung squamous cell carcinoma. Therefore, specific therapies that target lung squamous cell carcinoma are desperately needed. Sox2 is a master pluripotency controller that was recently identified as a novel major oncogene, recurrently amplified and activated in lung squamous cell carcinoma. Immunohistochemistry shows that Sox2 expression is seen in approximately 55% of human pulmonary adenocarcinoma sections. On the other hand Sox2 expression is detected in more than 90% of lung squamous cell carcinoma sections. Inhibition of Sox2 by siRNA suppresses cell viability and colony formation of Sox2 expressing EBC2 and LK2 lung squamous cell carcinoma cells. Moreover, Sox2 siRNA inhibits lung squamous cell carcinoma growth in vivo in a xenograft mouse model derived from EBC2 cells. Flowcytometric analysis demonstrated that Annexin V positive and PI negative cell populations were not changed 48 hours after Sox2 silencing in EBC2 lung squamous cell carcinoma cells. Microarray analysis demonstrated that the expression of several cell cycle related genes were changed after Sox2 silencing in Sox2 expressing lung squamous cell carcinoma cells. Cell cycle analysis showed that Sox2 silencing significantly increased the G1 population in the cells. These results indicate that Sox2 silencing might produce an antitumor effect via G1 cell cycle arrest. Citation Format: Naomasa Ishida, Takuya Fukazawa, Munenori Takaoka, Tomoki Yamatsuji, Ichiro Morita, Minoru Haisa, Nagio Takaoka, Yoshio Naomoto. Development of a Sox2 targeting therapy for the treatment of lung squamous cell carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3616. doi:10.1158/1538-7445.AM2015-3616

Abstract 744: Effective use of MDK/Midkine and MEK inhibitor to treat KRas mutated pulmonary adenocarcinoma cells

Lung cancer is the leading cause of cancer-related mortality worldwide. Although a platinum-doublet regimen has become the standard of care, the benefit is modest and the 5-year survival rate has remained essentially unchanged over the past 3 decades. Recently, several molecular alterations have been defined as “driver mutations,“ such as mutations in epidermal growth factor receptor (EGFR), KRas, chimeric tyrosine kinases involving ALK, RET, ROS1. And molecular targeting therapies for lung adenocarcinoma, targeting mutant EGFR or ALK, RET and ROS1 fusions, limit non-tumor toxicity and extend survival time compared to the conventional chemotherapies. However, there is no effective molecularly targeted therapy for mutant KRas-driven lung adenocarcinoma, the most frequent type of lung adenocarcinoma in the Caucasian population. Therefore, specific therapies that target various lung tumor types are desperately needed. Midkine (MDK) is a heparin-binding growth factor that is highly expressed in many malignant tumors, including lung cancers. We have previously reported that a MDK inhibitor: iMDK suppresses non-small cell lung cancer expressing MDK in vitro and in vivo without harming normal cells. Importantly, iMDK inhibits the PI3 kinase / Akt pathway and induces apoptosis in MDK expressing non-small cell lung cancer cells. In the present study, we have investigated the combination effect of iMDK and a mitogen-activated protein/extracellular signal-regulated kinase (MEK) inhibitor PD0325901. The combination treatment of iMDK and PD0325901 more effectively suppressed cell viability and colony formation, increased caspase-3 activity and induced apoptosis than those of single use in H441 and H2009 pulmonary adenocarcinoma cells harboring a G12 KRas mutation. Here, we describe the efficacy of the use of iMDK and PD0325901 for patients with inoperable advanced lung cancer including pulmonary adenocarcinoma harboring KRas mutations. Citation Format: Takuya Fukazawa, Yutaka Maeda, Naomasa Ishida, Tomoki Yamatsuji, Munenori Takaoka, Minoru Haisa, Nagio Takigawa, Jeffery Whitsett, Yoshio Naomoto. Effective use of MDK/Midkine and MEK inhibitor to treat KRas mutated pulmonary adenocarcinoma cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 744. doi:10.1158/1538-7445.AM2014-744