Masahiro Mitsuoka

Co-existence of positive MET FISH status with EGFR mutations signifies poor prognosis in lung adenocarcinoma patients

MET, a receptor tyrosine kinase for hepatocyte growth factor, is associated with tumor progression and acquired resistance to epidermal growth factor tyrosine kinase inhibitors (EGFR-TKI). Therefore, MET gene alterations could be both prognostic and predictive. Fluorescence in situ hybridization (FISH) is one method for assessing gene alteration, but the frequency of positive cases varies due to a lack of standardized criteria. We evaluated MET gene copy number in lung adenocarcinoma and its association with clinicopathological characteristics. FISH was applied to evaluate high MET gene copy number and true amplification in 138 lung adenocarcinoma patients using two criteria: the Cappuzzo scoring system and PathVysion. MET positive cases according to the Cappuzzo scoring system evidenced both aneuploidy and true amplification, whereas PathVysion revealed only amplification. Proportion of MET FISH positive cases was 15% and 4% determined by the Cappuzzo system and PathVysion, respectively. PathVysion demonstrated higher frequencies of MET FISH positives among men and smokers and evidenced no MET FISH positives in patients with bronchioloalveolar carcinoma. Prognosis was significantly associated with MET FISH positive only as defined by the PathVysion system (gene amplification), not by the Cappuzzo system. However, progression-free survival time of patients with both EGFR mutations and MET FISH positive defined by the Cappuzzo scoring system was significantly shorter than with EGFR mutations alone. These results suggest that MET FISH is a potential prognostic factor and coexistence of MET FISH with EGFR mutations signifies worse prognosis.

Mina53, a novel c-Myc target gene, is frequently expressed in lung cancers and exerts oncogenic property in NIH/3T3 cells.

PurposeMina53, whose expression is directly induced by c-Myc, is overexpressed in various cancers and plays an important role in cell growth. To clarify the involvement of Mina53 in lung cancers, we investigated its expression in human lung cancer tissues as well as in various lung cancer cell lines.MethodsMina53 expression was determined by real-time RT-PCR, western blotting, and immunohistochemistry using lung cancer cell lines, normal human bronchial epithelial cells, and lung cancer tissues. Biological effects of Mina53 were evaluated by soft agar colony formation assay and tumorigenicity in nude mice using Mina53-transfected NIH/3T3 cells. cDNA microarray analysis was performed to determine the gene alteration by Mina53 and confirmation was made using real-time RT-PCR with mina53 expression plasmid or mina53 shRNA-transfected NIH/3T3 cells.ResultsWe observed that 62% of patients evidenced overexpression of Mina53 from the early clinical stages of lung cancer. Differences according to gender, smoking status, or histologic type were not statistically significant. Forced expression of Mina53 in NIH/3T3 cells induced cell transformation, and mina53-transfected NIH/3T3 clones produced tumors in nude mice, demonstrating that Mina53 has oncogenic potential. cDNA microarray revealed that 254 genes had altered expression in a mina53-transfected NIH/3T3 clone. Mina53 regulates several genes related to cell adhesion and metabolism, which have also been reported to be regulated by c-Myc. Genes regulated by Mina53, but not by c-Myc included cytokine/growth factor related genes such as EGFR, IL-6, and HGF.ConclusionOur results suggest that Mina53 plays an important role in carcinogenesis and may be a target for cancer prevention.

Expression of Mina53, a novel c-Myc target gene, is a favorable prognostic marker in early stage lung cancer.

Mina53, a novel target gene product of c-Myc, is overexpressed in various malignancies. We previously demonstrated that Mina53 is overexpressed in lung cancer patients from the early clinical stages. In this paper, the association between disease prognosis and Mina53 expression in lung cancer patients is analyzed; we found that overexpression of Mina53 in lung cancer patients is associated with favorable prognosis. Statistical analysis using the Kaplan-Meier method showed that patients with negative staining for Mina53 had significantly shorter survival than patients with positive staining for Mina53, especially in stage I or with squamous cell carcinoma. Because the major cause of death in lung cancer patients after surgery is distant metastasis, the effect on cancer cell invasiveness was analyzed for the mechanisms involved in the association with favorable outcome. Overexpression of Mina53 in H226B, a lung squamous cell carcinoma cell line, inhibited cancer cell invasion. Transfection with mina53 shRNA increased the number of invading cells. These results suggest that Mina53 immunostaining is a useful prognostic marker--especially in the early stage of lung cancer--and that Mina53 negative patients should be managed particularly carefully after surgery.

The utility of a reusable bipolar sealing instrument, BiClamp®, for pulmonary resection

OBJECTIVE To assess the use of a combination of bipolar sealing and electrosurgical coagulation for pulmonary resection. METHODS The procedure was used in both dogs and humans. Initially, lung wedge resections were performed on six healthy, Beagle dogs using a voltage controlled electrosurgical system. The area of lung tissue to be resected was first coagulated to provide a distinct line of seal. The lung was then resected along the peripheral site of the sealing scar. Efficiency of sealing was assessed using a tracheally applied air pressure of 30cmH(2)O. The electro-cauterized tissue was compared histologically to tissue sealed by a standard stapling technique. In the clinical phase, lung resections were performed after cauterization in 17 patients. Bullectomies were performed using video-assisted thoracic surgery in 4 patients, and thoracotomic procedures in 13 (1 bullectomy, 5 wedge resections, and 7 fissure separations). RESULTS Dogs: Tissue sealing was highly successful, without any air leakage, in all six dogs. Histologically, the clamped lesion showed tissue-fusion probably due to both the compression and thermal effects. The proximal zone adjacent to the clamped lesion revealed both collapsed alveolar spaces and fused alveolar walls. In comparison, the stapled lesions showed no tissue-fusion. Humans: There were no major complications. The median operation time was 189min, and estimated median hemorrhage volume was 67ml. Median chest drainage duration was 3 days (range: 1-7) and no patient suffered from prolonged air leakage (>7 days). CONCLUSIONS Lung parenchymal tissue resection following bipolar sealing and electrosurgical coagulation instead of staples was efficient and simple. Furthermore, the technique reduced the use of staples, reducing the cost of the surgery.

Exon 19 of EGFR mutation in relation to the CA-repeat polymorphism in intron 1.

Epidermal growth factor receptor (EGFR) mutations in lung cancer enhance tyrosine kinase activity and increase sensitivity to the EGFR tyrosine kinase inhibitor, gefitinib. Mutation analysis of the EGFR gene is therefore indispensable for predicting gefitinib response. We investigated a CA‐repeat polymorphism in the EGFR gene related to EGFR mutations. Because an increasing number of CA‐repeats at intron 1 of the EGFR gene has been reported to reduce transcription activity, we examined the relationship between EGFR mutations and this CA‐repeat polymorphism. EGFR mutations at exon 19 were closely associated with shorter CA‐repeat length in the shorter allele, but this was not the case for EGFR mutations at exons 18 or 21. Increased intrinsic EGFR mRNA expression in non‐cancerous lung tissues from lung adenocarcinoma patients was also significantly associated with shorter CA‐repeat length. A higher frequency of EGFR mutations at exon 19 was associated with shorter CA‐repeat length only in patients with high levels of EGFR mRNA expression. To determine the phenotypes of cells possessing shorter CA‐repeats, an in vitro study using human bronchial epithelial cells with different CA‐repeat lengths was performed; more rapid cell growth and activated EGF/EGFR signaling were found more often in the cells having both shorter CA‐repeats and increased EGFR mRNA expression. These results suggest that CA‐repeat length in the EGFR gene may be a genetic factor related to cancer in the case of EGFR mutations at exon 19. The mechanism likely involves enhanced intrinsic expression of EGFR mRNA and activated EGF/EGFR signaling that accompany shorter CA‐repeats. (Cancer Sci 2008; 99: 1180–1187)

Dramatic hemostasis of the transected pulmonary artery model using SOFT COAG electrosurgical output

We report the use of low-voltage, automatically regulated, electrosurgical coagulation to seal the bleeding from pulmonary arteries inadvertently during surgical intervention. Conventional electrosurgical coagulation uses high voltage, which generates intensive heat in the tissue. The heat results in carbonized eschar formation that can be easily broken by mechanical stress and lead to postoperative bleeding. SOFT COAG output automatically regulates the output voltage to a maximum of 200 Volts, preventing the generation of sparking. Thus, there is no formation of carbonized eschar. The instrument generates Joule heat alone in the tissue and the temperature rises to below boiling point, which effectively coagulates protein. Initial experiments, using a beagle model, clearly demonstrated the effectiveness and reliability of sealing both macroscopically and histopathologically. SOFT CAOG can be easily adopted both in open thoracotomy as well as in thoracoscopic procedures.

A fully integrated, automated and rapid detection system for KRAS mutations.

KRAS mutations are detected in tumors of various organs, and they are also markers of resistance for epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors and monoclonal antibodies against the EGFR. Thus, the accurate and rapid detection of KRAS mutations is crucial, not only for screening, but also for the prediction of the efficacy of molecular-targeted therapy. The aim of the present study was to establish a novel automated detection system for KRAS mutations. One hundred and thirty-six lung adenocarcinoma patients were genotyped for KRAS mutations with both the conventional direct sequence (DS) method and with the newly developed quenching probe (QP) method that obtains data automatically within 60 min. The detection limit of the QP method using a control plasmid containing the KRAS mutation was 50 copies, and 10% mutant plasmid was detected in the mixture of wild-type and mutants. The results obtained by the QP and DS methods were identical in all but two of the 136 cases. The two differentially identified samples, which consisted of substantially fewer lung cancer cells, were positive according to the QP method but negative as determined by DS for KRAS mutations. These findings characterize the QP method as an accurate and rapid detection system for KRAS mutations.

Magnetic resonance imaging features of spontaneously regressed thymoma: report of 2 cases.

The authors describe 2 cases in which thymoma spontaneously regressed. The first patient was a 49-year-old woman with myasthenia gravis. A chest radiograph on admission showed an anterior mediastinal mass that spontaneously decreased in size as shown on a radiograph obtained 2 weeks later. Surgical removal of the mass was performed and the histopathologic examination showed a type B2 thymoma with marked coagulation necrosis in the central area. The second patient was a 46-year-old woman who was hospitalized due to chest and back pain. A chest radiograph on admission showed an anterior mediastinal mass and bilateral pleural effusion. The mass decreased in size and the effusion disappeared as shown on a chest radiograph obtained 2 months later. Computed tomography-guided biopsy was performed, and histopathologic examination revealed thymoma with marked necrosis. In both cases, dynamic contrast-enhanced magnetic resonance images showed peripheral ringlike enhancement of the mass. The clinical and radiologic features of spontaneously regressed thymoma may be different from those of common thymoma.

Total cricoidectomy and laryngotracheal reconstruction for subglottic stenosis with glottic involvement

We present a case of subglottic stenosis involving the glottis with inflammatory destruction of the cricoid cartilage after prolonged endotracheal intubation. Total cricoidectomy and laryngotracheal anastomosis were performed with T-tube placement that was retained for five months postoperatively. After decannulation of the T-tube, the airway was well restored, with good vocal cord opening. Good respiratory and phonatory results were obtained during normal daily activity, although a slightly hoarse voice was present, but no aspiration was observed. Total cricoidectomy and laryngotracheal reconstruction may be considered suitable for subglottic stenosis with glottic involvement, if accompanied by inflammatory destruction of the cricoid cartilage.

Surgical resection of extramedullary haematopoiesis in the posterior mediastinum: Extramedullary haematopoiesis

Extramedullary haematopoiesis is a rare disease that is usually associated with haematologic disorders such as thalassemia, myelodysplastic syndrome, and hereditary spherocytosis. It frequently occurs in the liver, spleen, and lymph nodes. Rarely, it occurs in the posterior mediastinum. We report the case of a 59‐year‐old man with lateral posterior mediastinal masses that were incidentally detected during treatment for hereditary spherocytosis. We performed video‐assisted thoracic surgery to confirm the diagnosis and differentiate the masses from neurogenic tumours and other posterior mediastinal diseases. The pathological findings were consistent with intrathoracic extramedullary haematopoiesis. Although extramedullary haematopoiesis can be managed without interventions, surgery may be required in some cases. In such cases, video‐assisted thoracoscopic surgery is advised because it is a useful and less invasive procedure.