Keisuke Yokota

Nagoya City University, Nagoya, Aichi, Japan

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Publications (17)12.97 Total impact

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    ABSTRACT: Thymoma is the most common tumor of the anterior mediastinum for which surgical resection is currently the primary form of treatment. An increase in the incidence of a small-sized (≤3 cm) thymoma (SST) has recently been noted. Clinicopathological factors and prognosis of SST have not been reported previously. In this study, the clinicopathological data of 21 SST patients were reviewed and podoplanin and Ki67 immunohistochemistry were assessed to determine the biological behavior of SSTs. Pathological diagnosis of SSTs revealed the following types: A (n=1), AB (n=8), B1 (n=5), B2 (n=6) and B3 (n=1). The Masaoka-Koga stages of 21 thymoma patients were I (n=16), II (n=3), III (n=1) and IVb (n=1). In the case of the stage IVb thymoma, phrenic nerve, mediastinal pleura invasion and anterior mediastinal lymph node metastasis were observed. The Ki67 labeling index of this stage IVb was found to be 3.2. This case was also positive for podoplanin and was one of the only 2 cases that were positive for podoplanin. This patient succumbed to thymoma. Advanced stage thymomas are possibly included in SSTs although the majority of SSTs are classified into early stages of disease. Findings of this study suggest that podoplanin analyzed by immunohistochemistry may be useful to determine the malignant behavior of SSTs.
    Molecular and clinical oncology. 01/2013; 1(1):88-92.
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    ABSTRACT: RagD is a member of the small G protein family, which encodes a recently discovered activator of the mTOR pathway. In vitro, RagD plays an important role in the proliferation of NRF2 gene (NFE2L2) mutated cancer cells. We hypothesized that tumor RagD expression may be correlated with the mutation status of NRF2 in lung cancers. RagD mRNA levels were analyzed by quantitative real-time polymerase chain reaction (qPCR) in 90 surgically-treated lung squamous cell cancer cases, including 14 NRF2 mutation cases, and normalized by β-actin mRNA levels. Mean RagD/β-actin mRNA levels of lung squamous cell carcinoma patients did not differ with age (≤65 vs. >65), Brinkman index (<400 vs. ≥400) or gender. RagD/β-actin mRNA levels were significantly higher in stage III samples (3.204±3.623) compared to stage I samples (1.357±1.560) (P= 0.0039). In addition, higher RagD/β-actin mRNA levels were identified in NRF2 mutant samples (3.107±3.633) compared to wild-type samples (1.774±2.301) (P=0.074). These results suggest that RagD induction by NRF2 activation plays a role in the proliferation of lung squamous cell cancers.
    Oncology letters 12/2012; 4(6):1167-1170. · 0.24 Impact Factor
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    ABSTRACT: The epidermal growth factor receptor (EGFR) gene is highly polymorphic and its expression and activity may be affected by various polymorphisms. There have been several studies examining associations between EGFR polymorphisms and clinical outcome of lung cancer therapy; however, the underlying mechanism is largely unknown. The present study investigated EGFR polymorphism status and its correlation with clinicopathological features in Japanese non-small cell lung cancer (NSCLC) patients. We investigated 5 polymorphisms in the EGFR gene (-216G/T, -191C/A, 8227G/A, D994D and R497K) in 274 surgically-treated NSCLC patients. TaqMan single nucleotide polymorphism (SNP) genotyping assays and a PCR-based assay were used to analyze these polymorphisms. In our cohort of patients we did not find any evidence of the -191C/A polymorphism. Our results showed that the patients with the 8227GA or AA type in intron 1 had a significantly better prognosis with the anti-EGFR therapy than the patients with the GG type (p=0.0448) in terms of recurrence of lung cancer. No significant association was observed between 3 other SNPs (-216G/T, D994D and R497K) and clinicopathological features. The EGFR 8227G/A polymorphism in intron 1 may be associated with clinical outcome in NSCLC patients treated with EGFR tyrosine kinase inhibitors.
    Experimental and therapeutic medicine 11/2012; 4(5):785-789. · 0.34 Impact Factor
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    ABSTRACT: Thymic carcinoma is a rare thymic epithelial tumor in which chemotherapy for advanced disease has not yet been established. Thymidylate synthase (TS) and orotate phosphoribosyltransferase (OPRT) protein expression levels in thymic carcinoma were evaluated as possible indicators of the anticancer activity of 5-fluorouracil (5-FU) drugs using immunohistochemistry (IHC). A total of 24 samples of thymic carcinoma were used in the present study. The tumor sections were immunohistochemically stained for TS and OPRT. As a comparison with thymic carcinoma, we also assessed the TS and OPRT protein expression levels in 55 lung cancer samples. The TS expression was positive in 12 of 24 thymic carcinoma samples (50%) and OPRT expression was positive in 10 (42%). The association between TS and OPRT expression and Masaoka stages of thymic carcinoma was analyzed. The TS and OPRT expressions in stage IV were significantly higher compared to that in stages I, II or III. We also compared the TS and OPRT expression levels between thymic carcinoma and lung cancer (33 adenocarcinomas and 22 squamous cell carcinomas). TS expression in thymic carcinoma was significantly lower compared with lung squamous cell carcinoma. OPRT expression in thymic carcinoma was significantly higher compared to lung adenocarcinoma. The combination of a relatively low expression of TS and high expression of OPRT suggests an improved antitumor effect of 5-FU drugs in thymic carcinoma compared to in lung carcinoma.
    Experimental and therapeutic medicine 10/2012; 4(4):589-593. · 0.34 Impact Factor
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    ABSTRACT: RET encodes the tyrosine kinase receptor of growth factors belonging to the glial-derived neurotrophic factor family. Recently, RET gene rearrangements with N-terminal of KIF5B gene were identified in lung adenocarcinomas from large-scale sequencing. We investigated RET mRNA expression by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) assay using LightCycler, and KIF5B/RET gene rearrangements using newly established fluorescence in situ hybridization (FISH) analysis in surgically treated nonsmall cell lung cancer (NSCLC) cases. RET protein expression was also investigated by immunohistochemistry (IHC). This study included 157 surgically removed NSCLC cases for mRNA level analyses. The RET/β actin mRNA levels were not significantly different between lung cancer (6.359 ± 15.268) and adjacent normal lung tissues (8.205 ± 28.931, P = 0.6332). Tumor/normal (T/N) ratio of RET/β actin mRNA levels was not different within gender, stage, smoking status, and pathological subtypes. T/N ratio of RET/β actin mRNA levels was significantly higher in KIF5B/RET rearrangement samples (161.763 ± 123.488) than in wild-type samples (5.9013 ± 17.148, P = 0.044). Although RET IHC positivity was not perfectly correlated with KIF5B/RET arrangement, we have detected the KIF5B/RET rearrangements using FISH analysis. Thus, we have successfully introduced FISH for diagnosing KIF5B/RET positive lung adenocarcinoma. This method facilitates the molecular evaluation for RET fusions and could be applicable in clinical practice to detect lung cancer that may be responsive to RET inhibitors.
    Cancer medicine. 08/2012; 1(1):68-75.
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    ABSTRACT: Recently, a novel fusion gene resulting from a linkage between the kinesin family member 5B gene (KIF5B; 10p11.22) and the rearranged during transfection gene (RET; 10q11.21) was identified in non-small cell lung cancer (NSCLC). However, the correlation between the KIF5B/RET fusion gene status and the clinicopathological features of surgically-treated lung cancer has not been well characterized. In this study, we have independently investigated the KIF5B/RET fusion gene status in 371 surgically-treated NSCLCs (270 were adenocarcinomas and 101 were squamous cell carcinomas), 60 breast cancers, 11 metastatic lung cancers from colon cancers and thyroid papillary adenocarcinoma cases at the Nagoya City University Hospital. The fusion gene status was analyzed by an RT-PCR-based assay and by using direct sequencing. We detected 3 of 270 cases of KIF5B/RET fusion genes in adenocarcinomas (1.1%) consisting of female and never smokers with mixed subtype adenocarcinomas. The fusion genes were detected exclusively with other mutations, such as EGFR, Kras, Braf, erbB2 mutations, and EML4/ALK fusion. KIF5B/RET fusion was not detected in the cases with squamous cell carcinoma or other types of cancers. From the 3 cases, 2 were KIF5B (exon 15); RET (exon 12) fusions with papillary dominant and 1 case was KIF5B (exon 22); RET (exon 12) fusion with solid dominant adenocarcinoma. The matched normal lung tissues did not display translocation. We reported KIF5B/RET fusion genes as a driver somatic mutation of lung adenocarcinomas. The cinicopathological backgrounds of the KIF5B/RET fusion-positive patients were similar with those of the EML4/ALK fusion-positive patients. The chimeric oncogene may be a promising molecular target for the personalized diagnosis and treatment of NSCLC.
    Oncology Reports 07/2012; 28(4):1187-92. · 2.30 Impact Factor
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    ABSTRACT: The expression of multidrug-resistant protein-3 (MRP3), a membrane-bound transporter, has been linked to drug resistance in non-small cell lung cancers (NSCLCs). Recently, we reported that NRF2 gene (NFE2L2) mutations are correlated with poor prognosis for lung squamous cell carcinomas. We hypothesized that tumor MRP3 expression may be correlated with the mutation status of upstream regulators, including NRF2, in NSCLC patients. MRP3 mRNA levels were analyzed by quantitative real-time polymerase chain reaction (qPCR) in 67 surgically-treated lung squamous cell cancer cases from the Nagoya City University Hospital and normalized by β-actin mRNA levels. Fourteen NRF2 mutation cases were included. The mean MRP3/β-actin mRNA levels did not differ according to age (≤65 vs. >65 years), Brinkman index (≤400 vs. >400) or the pathological stage of the lung squamous cell carcinoma. MRP3/β-actin mRNA levels were significantly higher in men (1.200±1.524) than in women (0.179±0.083; p=0.0036). In addition, the MRP3/β-actin mRNA levels were significantly higher in NRF2 mutants (2.598±2.373) than in wild-type NRF2 mutants (0.734±0.820; p=0.0002). These data support the hypothesis that the expression of MRP3 is induced by NRF2 activation in lung squamous cell cancers.
    Molecular Medicine Reports 07/2012; 6(4):705-8. · 1.17 Impact Factor
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    ABSTRACT: Discoidin domain receptor 2, DDR2, is a tyrosine kinase receptor for fibrillar collagen that is involved in postnatal development, tissue repair and primary and metastatic cancer progression. Recently, mutations in the DDR2 kinase gene were identified in squamous cell lung cancer from large-scale Sanger sequencing. The present study investigated the DDR2 gene mutations and mRNA expression in surgically treated non-small cell lung cancer (NSCLC) of squamous histology cases. The presence or absence of DDR2 mutations at the kinase and discoidin domain was analyzed by direct sequencing. In this cohort, DDR2 mutations were not observed in the 166 patients with lung cancer, although DDR2 polymorphisms were observed (H136H, n=14) at the discoidin domain. mRNA levels of DDR2 in lung tumor samples and the adjacent normal lung samples were simultaneously analyzed. DDR2 mRNA levels were significantly decreased in tumor samples compared with normal lung samples. However, the DDR2 mRNA levels were elevated in the DDR2 polymorphism cases.
    Oncology letters 07/2012; 4(1):33-37. · 0.24 Impact Factor
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    ABSTRACT: Nuclear factor (erythroid-derived 2)-like 2 (NRF2) is a transcription factor belonging to the cap 'n' collar subfamily of the basic-leucine zipper (bZIP) family of transcription factors, which plays a significant role in adaptive responses to oxidative stress. Previously, we reported that NRF2 gene (NFE2L2) mutations correlate with poor prognosis of lung squamous cell carcinomas. We therefore hypothesized that an increased NRF2 gene copy number may correlate with clinicopathological features in lung cancer patients. In this study, the increased copy number of the NRF2 gene was analyzed by real-time polymerase chain reaction (real-time-PCR) amplifications in 90 surgically-treated non-small cell lung cancer (NSCLC) cases. In total, 16 NRF2 mutation cases were included. An increased NRF2 gene copy number was found in 7 (7.8%) lung squamous cell carcinoma patients. Increased NRF2 copy number status significantly correlated with mutation status (mutant, 31.25% vs. wild-type, 2.7%; p=0.0017). The mean NRF2 gene copy number was significantly higher in mutant (2.478 ± 0.668) compared to wild-type NRF2 (1.917 ± 0.737) (p=0.0048). However, the copy number did not correlate with smoking status (p=0.3741), gender (p=0.1545), age (≥65 vs. <65, p=0.1237) and pathological stage. Although an increased NRF2 copy number correlates with mutations in squamous cell carcinoma, the percentage of the increased copy number was low; therefore, another mechanism may exist for the activation of NRF2 mutations in cancer.
    Molecular Medicine Reports 05/2012; 6(2):391-4. · 1.17 Impact Factor
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    ABSTRACT: The erbB pathway involves a family of tyrosine kinases and contributes to resistance or sensitivity to chemotherapy in many tumor types. Somatic mutations of the epidermal growth factor receptor (EGFR) gene at the kinase domain have been found in lung cancer patients. These mutations are correlated with clinical response to targeted molecular therapy. Although Caucasian lung cancer patients have been shown to harbor Braf and erbB2 mutations, only a few reports exist concerning Braf and erbB2 mutations in Japanese lung cancer patients. We investigated the Braf and erbB2 mutation status in non-small cell lung cancer (NSCLC) patients by reverse transcription-polymerase chain reaction (RT-PCR) and direct sequencing. The study included 305 surgically removed lung cancer samples from the Nagoya City University Hospital, which were EGFR and Kras wild-type centric. Six Braf mutations were found in the adenocarcinoma cases. Among the adenocarcinoma cases, Braf mutations were more frequently noted in heavy smokers (Brinkman index >400, p=0.0476). We also detected five erbB2 mutations all in the non-smokers. All of these mutations existed exclusively. The erbB2 gene mutations were predominantly found in non-smokers with adenocarcinomas. However, the completely exclusive mutation status could help us design individually tailored targeted molecular therapy for lung cancer.
    Experimental and therapeutic medicine 05/2012; 3(5):771-775. · 0.34 Impact Factor
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    ABSTRACT: We herein report the case of a 65-year-old female with primary lung cancer who underwent a right upper and lower sleeve bilobectomy. The radiological findings revealed that the tumor was located in the superior segment of the right lower lobe and had invaded the posterior segment of the upper lobe and the truncus intermedius. We performed a right upper and lower sleeve bilobectomy. A latissimus dorsi flap was utilized to separate the thoracic cavity into upper and lower portions, and the preserved middle lobe was fixed in the upper portion to prevent torsion. Postoperative radiography showed good expansion of the middle lobe.
    Surgery Today 02/2012; 42(6):610-2. · 0.96 Impact Factor
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    ABSTRACT: The transcription factor Sox2 is necessary for foregut morphogenesis. Sox2 is also required for the normal development of the trachea and lung. Recently, Sox2 amplifications were investigated using large-scale single nucleotide polymorphism arrays in esophageal and lung cancer. We hypothesized that Sox2 overexpression might be correlated with clinicopathological features of lung cancers. The increased copy number of the Sox2 gene was analyzed by real-time polymerase chain reaction amplifications in 127 surgically treated non-small cell lung cancer cases from Nagoya City University Hospital, Japan. A total of 87 squamous cell carcinoma (SCC) cases were involved. An increased Sox2 gene copy number was found in 42 (33.1%) lung cancer patients. Increased Sox2 copy number status was significantly correlated with gender (females, 9.5% vs. males, 34.1%; p=0.0026), smoking status (never smoker, 4.8% vs. smoker, 32.9%; p=0.0003) and pathological subtypes (squamous cell carcinoma, 44.8% vs. non-squamous cell carcinoma, 7.5%; p<0.0001). However, among the SCCs, the Sox2 copy number status was not significantly correlated with gender, smoking status, pathological stage or differentiation status. An increased Sox2 copy number is common within SCC.
    Experimental and therapeutic medicine 01/2012; 3(1):44-48. · 0.34 Impact Factor
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    ABSTRACT: Glucose is the major source of energy for cells, and glucose transporter 1 (GLUT1) is the most common glucose transporter. GLUT1 has been found to be aberrantly expressed in several tumor types. From the results of the microarray and serial analysis of gene expression (SAGE), GLUT1 transcript expression was found to be higher in clones with mutant Kras alleles. We hypothesized that GLUT1 overexpression might be correlated with clinicopathological features of Japanese lung cancers. Immunohistochemistry for GLUT1 was performed in 283 surgically treated non-small cell lung cancer (NSCLC) cases from Nagoya City University Hospital. Thirty-six Kras mutant carcinoma cases were included. GLUT1 overexpression was found in 138 (48.8%) lung cancer patients. The GLUT1 overexpression status was significantly correlated with gender (women 31.9% vs. men 54.5%, P<0.0001), smoking status (never smoker 31.4% vs. smoker 59.4%, P<0.0001) and pathological subtypes (adenocarcinoma 36.4% vs. non‑adenocarcinoma 74.5%, P<0.0001). In addition, the GLUT1 overexpression status was significantly correlated with gene mutation status, including EGFR (mutation-positive 23.4% vs. -negative 58.3%, P<0.0001) and Kras (mutation-positive 66.7% vs. -negative 46.6%, P=0.038). The survival of patients with GLUT1 overexpression (n=137, 50 were deceased) was significantly worse when compared to the patients with normal expression of GLUT1 (n=142, 31 were deceased) (Log-rank test, P=0.0009). Thus, GLUT-1 overexpression correlates with an aggressive phenotype of lung carcinoma.
    Molecular Medicine Reports 12/2011; 5(3):599-602. · 1.17 Impact Factor
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    ABSTRACT: The basic fibroblast growth factor (bFGF), via activation of its receptor, FGFR1, has been postulated to be an important inducer of host stromal response and angiogenesis. More recently, FGFR1 amplifications were investigated using large-scale single nucleotide polymorphism arrays in lung cancer. We hypothesized that FGFR1 overexpression may be correlated with the clinicopathological features of lung cancers. The increased copy number of the FGFR1 gene was analyzed by real-time polymerase chain reaction amplifications in 100 surgically treated non-small cell lung cancer cases from Nagoya City University Hospital. Sixty-five squamous cell carcinoma cases were included. An increased FGFR1 gene copy number was found in 32 (32%) lung cancer patients. The increased FGFR1 copy number status significantly correlated with gender (females 13.8% vs. males 39.4%, p=0.0173), smoking status (never smoker 4.2% vs. smoker 40.8%, p=0.0004) and pathological subtypes (squamous cell carcinoma 41.5% vs. non-squamous cell carcinoma 14.3%, p=0.0066). However, within the squamous cell carcinomas the FGFR1 copy number status did not significantly correlate with gender, smoking status, pathological stages and differentiation status of the lung cancers. Thus, the FGFR1 copy number is common within squamous cell carcinoma.
    Molecular Medicine Reports 12/2011; 5(3):725-8. · 1.17 Impact Factor
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    ABSTRACT: We report the case of solitary fibrous tumor of the pleura, which appeared to change its location. A computed tomography (CT) scan done at a previous hospital showed a tumor in the posterior mediastinum, suggesting that it was neurogenic. However, on the initial preoperative CT scan, the tumor seemed to have moved anteriorly, but when contrast material was injected; the tumor appeared in its original position. Video-assisted thoracoscopic surgery (VATS) revealed a pedunculated and free-moving tumor, originating from the visceral pleura. We diagnosed this unusual migrating tumor as a pedunculated solitary fibrous tumor of the pleura.
    Surgery Today 12/2011; 42(4):395-7. · 0.96 Impact Factor
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    ABSTRACT: Acute exacerbation (AE) of idiopathic pulmonary fibrosis (IPF) in lung cancer patients is a critical factor in post-operative mortality. The cause of AE development is unknown and AE may occur in patients without the diagnosis of IPF. We have conducted a retrospective study of consecutive patients who underwent lung cancer surgery since January 2004. Sixty-two patients with fibrous findings in preoperative high-resolution computed tomography were enrolled in the present study and clinicopathological factors were analysed. AE was observed in 6 of 62 patients. The frequency of AE according to the type of fibrous changes classification was 1/7 in the usual interstitial pneumonia (UIP) pattern, 1/16 in the cellular non-specific interstitial pneumonia (NSIP) pattern, 4/25 in the fibrotic NSIP pattern and 0/14 in the unclassified or focal fibrous changes pattern. Preoperative Krebs von den Lungen-6 (KL-6) was higher in patients with AE than in those without AE. In patients who underwent partial resection, AE did not develop even with high KL-6 levels. In conclusion, in patients with both the UIP and the NSIP patterns, AE development is possible. In patients with a high risk of AE, such as those with high KL-6 values, limited surgery may be an option to prevent AE development.
    Interactive Cardiovascular and Thoracic Surgery 11/2011; 14(2):146-50. · 1.11 Impact Factor
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    ABSTRACT: In advanced stage thymomas, recurrence is not uncommon but prognostic factors in recurrent thymoma have not been determined and standardized treatment for recurrence has not yet been established. A retrospective analysis was conducted on 24 thymoma patients who underwent treatment for recurrence in our institution to determine the prognostic factors for overall survival. Recurrence of thymoma appeared 11.6-109.6 months after the primary operation (34.6±25.7 months). Pleural disseminated recurrence was common (n=21) as the primary recurrent lesions. Single or combined modality therapy was performed in 19 patients; surgical resection in 12, radiotherapy in 10, and chemotherapy in six patients. A third surgical resection was performed in two patients. There was no difference in overall survival between the groups with or without treatment nor in those with or without resection. Old age and chemotherapy were factors for poorer prognosis. Patients with one or two recurrent lesions detected on CT examinations showed better prognosis. Prognosis in thymoma patients with recurrence was reviewed in the present study. Patients with a small number of recurrent lesions showed better prognosis irrespective of the treatment.
    Interactive Cardiovascular and Thoracic Surgery 03/2011; 13(1):21-4. · 1.11 Impact Factor

Publication Stats

44 Citations
12.97 Total Impact Points

Institutions

  • 2011–2012
    • Nagoya City University
      • Department of Oncology, Immunology and Surgery
      Nagoya, Aichi, Japan