Keisuke Yokota

RET expression and detection of KIF5B/RET gene rearrangements in Japanese lung cancer

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.

Overexpression of GLUT1 correlates with Kras mutations in lung carcinomas.

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.

Post-operative acute exacerbation of pulmonary fibrosis in lung cancer patients undergoing lung resection

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.

Increased FGFR1 copy number in lung squamous cell carcinomas

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.

Number of recurrent lesions is a prognostic factor in recurrent thymoma

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.

Polymorphisms in intron 1 of the EGFR gene in non‑small cell lung cancer patients

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.

MRP3 gene expression correlates with NRF2 mutations in lung squamous cell carcinomas

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.

Middle lobe preservation and fixation: right upper and lower sleeve bilobectomy. How to do it

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.

Expression of thymidylate synthase and orotate phosphoribosyltransferase in thymic carcinoma

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.

Pedunculated solitary fibrous tumor of the pleura manifesting as a migrating chest mass: report of a case

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.