The 2013 Incentive Award of the Okayama Medical Association in Cancer Research (2013 Hayashibara Prize and Yamada Prize)

受賞対象論文: Shien K, Toyooka S, Yamamoto H, Soh J, Jida M, Thu KL, Hashida S, Maki Y, Ichihara E, Asano H, Tsukuda K, Takigawa N, Kiura K, Gazdar AF, Lam WL, Miyoshi S：Acquired resistance to EGFR inhibitors is associated with a manifestation of stem cell-like properties in cancer cells. Cancer Res (2013) 73, 3051-3061

Ectopic Cervical Thymoma:A Case Report with 18F-fluorodeoxyglucose Positron Emission Tomography Findings

Ectopic thymoma is considered to arise from ectopic thymus tissue deposited as a result of the abnormal mislocalization of thymus tissue during the embryonic stage. An 86-year-old man visited our hospital with chief complaints of hoarseness and a mass in his anterior neck. A preoperative needle biopsy of the mass did not yield a definitive diagnosis. A positron emission tomography (PET) study revealed heterogeneous accumulation of 18F-fluorodeoxyglucose (FDG) in the tumor. The tumor, affecting the left sternocleidomastoid muscle, the recurrent laryngeal nerve, the internal carotid vein, and the brachiocephalic vein, was resected using a combination of a collar incision in the neck and a median incision in the sternum. Immunohistochemically, the tumor was diagnosed as an ectopic thymoma of the neck. To date, only a few cases of ectopic thymoma presenting with FDG accumulation have been reported. Our experience indicates that ectopic thymoma should be kept in mind during the differential diagnosis of neck tumors with FDG accumulation appearing on PET images

Drug Resistance to EGFR Tyrosine Kinase Inhibitors for Non-small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) harboring an activating mutation within the epidermal growth factor receptor (EGFR) was defined as a clinically distinct molecular group. These lesions show oncogene addiction to EGFR and dramatic responses to the EGFR tyrosine kinase inhibitors (TKIs). Several large Phase III trials have shown that EGFR-TKIs improved the progression-free survival of patients with EGFR mutant NSCLC compared to conventional chemotherapy. However, the long-term effectiveness of EGFR-TKIs is usually limited because of acquired drug resistance. To overcome this resistance to EGFR-TKIs, it will be essential to identify the specific mechanisms underlying the resistance. Many investigators have attempted to identify the mechanisms using preclinical models and drug-resistant clinical samples. As a result, several mechanisms have been showed to be responsible for the resistance, but not all of the relevant mechanisms have been uncovered. In this review, we provide an overview of mechanisms underlying drug-resistance to EGFR-TKIs, focusing on results obtained with preclinical models, and we present some possible strategies to overcome the EGFR-TKI resistance

Robotic Mediastinal Tumor Resections: Position and Port Placement

This study aimed to determine the optimal position and port placement during robotic resection for various mediastinal tumors. For anterior mediastinal tumors, total or extended thymectomy is commonly performed in the supine position using the lateral or subxiphoid approach. Although it is unclear which approach is better during robotic thymectomy, technical advantages of subxiphoid approach are beneficial for patients with myasthenia who require extended thymectomy. Partial thymectomy is performed in the supine position using a lateral approach. Superior, middle, and posterior mediastinal tumors are resected in the decubitus position using the lateral approach, whereas dumbbell tumor resection, which requires a posterior approach, can be performed in the prone position. The position and port placement should be chosen depending on the size, location, and aggressiveness of the tumor. In this study, we describe how to choose which of these different robotic approaches can be used based on our experience and previous reports

Silenced Expression of NFKBIA in Lung Adenocarcinoma Patients with a Never-smoking History

Nuclear factor of κ-light polypeptide gene enhancer in B cells inhibitor α (NFKBIA), which is a tumor suppressor gene, was found to be silenced in lung adenocarcinomas. We examined NFKBIA expression, mutations in the EGFR and K-ras genes, and EML4-ALK fusion in 101 resected lung adenocarcinoma samples from never-smokers. NFKBIA expression was evaluated using immunohistochemistry. NFKBIA expression was negative in 16 of the 101 samples (15.8%). EGFR and K-ras mutations and EML4-ALK fusion were detected in 61 (60.5%), 1 (1.0%), and 2 (2.0%) of the 101 samples, respectively, in a completely mutually exclusive manner. Negative NFKBIA expression was observed significantly more frequently among the tumors with none of the three genetic alterations compared to those with such alterations (p＝0.009). In addition, negative NFKBIA expression was significantly more frequent among the EGFR-wild type samples compared to the EGFR-mutant samples (p＝0.013). In conclusion, NFKBIA expression was silenced in adenocarcinomas without EGFR/K-ras mutations or EML4-ALK fusion, suggesting that the silencing of NFKBIA may play an important role in the carcinogenesis of adenocarcinomas independent of EGFR/K-ras mutations or EML4-ALK fusion

YES1 activation induces acquired resistance to neratinib in HER2-amplified breast and lung cancers

Molecular-targeted therapies directed against human epidermal growth factor receptor 2 (HER2) are evolving for various cancers. Neratinib is an irreversible pan-HER tyrosine kinase inhibitor and has been approved by the FDA as an effective drug for HER2-positive breast cancer. However, acquired resistance of various cancers to molecular-targeted drugs is an issue of clinical concern, and emergence of resistance to neratinib is also considered inevitable. In this study, we established various types of neratinib-resistant cell lines from HER2-amplified breast and lung cancer cell lines using several drug exposure conditions. We analyzed the mechanisms of emergence of the resistance in these cell lines and explored effective strategies to overcome the resistance. Our results revealed that amplification of YES1, which is a member of the SRC family, was amplified in two neratinib-resistant breast cancer cell lines and one lung cancer cell line. Knockdown of YES1 by siRNA and pharmacological inhibition of YES1 by dasatinib restored the sensitivity of the YES1-amplified cell lines to neratinib in vitro. Combined treatment with dasatinib and neratinib inhibited tumor growth in vivo. This combination also induced downregulation of signaling molecules such as HER2, AKT and MAPK. Our current results indicate that YES1 plays an important role in the emergence of resistance to HER2-targeted drugs, and that dasatinib enables such acquired resistance to neratinib to be overcome

Covalent N-arylation by the pollutant 1,2-naphthoquinone activates the EGF receptor

The epidermal growth factor receptor (EGFR) is the most intensively investigated receptor tyrosine kinase. Several EGFR mutations and modifications have been shown to lead to abnormal self-activation, which plays a critical role in carcinogenesis. Environmental air pollutants, which are associated with cancer and respiratory diseases, can also activate EGFR. Specifically, the environmental electrophile 1,2-naphthoquinone (1,2-NQ), a component of diesel exhaust particles and particulate matter more generally, has previously been shown to impact EGFR signaling. However, the detailed mechanism of 1,2-NQ function is unknown. Here, we demonstrate that 1,2-NQ is a novel chemical activator of EGFR but not other EGFR family proteins. We found that 1,2-NQ forms a covalent bond, in a reaction referred to as N-arylation, with Lys80, which is in the ligand-binding domain. This modification activates the EGFR–Akt signaling pathway, which inhibits serum deprivation–induced cell death in a human lung adenocarcinoma cell line. Our study reveals a novel mode of EGFR pathway activation and suggests a link between abnormal EGFR activation and environmental pollutant–associated diseases such as cancer

A Giant Thymic Cyst Accompanied by Acute Mediastinitis

We encountered a rare case of thymic cyst accompanied by mediastinitis. A 39-year-old Japanese male presented with fever and chest pain. The chest CT revealed a mass composed of a lobular cystic lesion with inflammation, suggesting the onset of mediastinitis. A definitive histological diagnosis was not obtained, and we performed a thymectomy. Pathologically, the thymic cyst was accompanied by multiple cavities, mimicking thymic cysts, caused by the inflammatory abscess. The surrounding adipose tissue showed inflammatory cell infiltrations with chronic fibrosis. These findings indicate that clinicians should be aware that thymic cysts may cause severe mediastinitis

Drug repositioning of tranilast to sensitize a cancer therapy by targeting cancer-associated fibroblast

Cancer-associated fibroblasts (CAFs) are a major component of the tumor microenvironment that mediate resistance of cancer cells to anticancer drugs. Tranilast is an antiallergic drug that suppresses the release of cytokines from various inflammatory cells. In this study, we investigated the inhibitory effect of tranilast on the interactions between non-small cell lung cancer (NSCLC) cells and the CAFs in the tumor microenvironment. Three EGFR-mutant NSCLC cell lines, two KRAS-mutant cell lines, and three CAFs derived from NSCLC patients were used. To mimic the tumor microenvironment, the NSCLC cells were cocultured with the CAFs in vitro, and the molecular profiles and sensitivity to molecular targeted therapy were assessed. Crosstalk between NSCLC cells and CAFs induced multiple biological effects on the NSCLC cells both in vivo and in vitro, including activation of the STAT3 signaling pathway, promotion of xenograft tumor growth, induction of epithelial-mesenchymal transition (EMT), and acquisition of resistance to molecular-targeted therapy, including EGFR-mutant NSCLC cells to osimertinib and of KRAS-mutant NSCLC cells to selumetinib. Treatment with tranilast led to inhibition of IL-6 secretion from the CAFs, which, in turn, resulted in inhibition of CAF-induced phospho-STAT3 upregulation. Tranilast also inhibited CAF-induced EMT in the NSCLC cells. Finally, combined administration of tranilast with molecular-targeted therapy reversed the CAF-mediated resistance of the NSCLC cells to the molecular-targeted drugs, both in vitro and in vivo. Our results showed that combined administration of tranilast with molecular-targeted therapy is a possible new treatment strategy to overcome drug resistance caused by cancer-CAF interaction

Diagnostic value of circulating microRNA-21 in chronic lung allograft dysfunction after bilateral cadaveric and living-donor lobar lung transplantation

Background: MicroRNAs (miRNAs) involved in the pathogenesis of pulmonary fibrosis have been shown to be associated with the development of chronic lung allograft dysfunction (CLAD) after lung transplantation (LT). We investigated the role of circulating miRNAs in the diagnosis of CLAD after bilateral LT, including cadaveric LT (CLT) and living-donor lobar LT (LDLLT). Methods: The subjects of this retrospective study were 37 recipients of bilateral CLT (n = 23) and LDLLT (n = 14), and they were divided into a non-CLAD group (n = 24) and a CLAD group (n = 13). The plasma miRNA levels of the two groups were compared, and correlations between their miRNAs levels and percent baseline forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and total lung capacity (TLC) values were calculated from one year before to one year after the diagnosis of CLAD. Results: The plasma levels of both miR-21 and miR-155 at the time of the diagnosis of CLAD were significantly higher in the CLAD group than in the non-CLAD group (miR-21, P = 0.0013; miR155, P = 0.042). The miR-21 levels were significantly correlated with the percent baseline FEV1, FVC, and TLC value of one year before and at the time of diagnosis of CLAD (P Conclusion: Circulating miR-21 appears to be of potential value in diagnosing CLAD after bilateral LT