Eugene Choi

Promoter hypermethylation of the CFTR gene and clinical/pathological features associated with non-small cell lung cancer

Background and objective:  The exact role of the cystic fibrosis transmembrane conductance regulator (CFTR) in pathophysiology, and the mechanisms regulating its expression are poorly understood. The CFTR gene is known to be genetically or epigenetically associated with several cancers. In the present study, the methylation status of the promoter region of the CFTR gene and its expression in primary non‐small cell lung cancer (NSCLC) were investigated.

Quantitative PCR for Etiologic Diagnosis of Methicillin-Resistant Staphylococcus aureus Pneumonia in Intensive Care Unit

Background Ventilator-associated pneumonia (VAP) requires prompt and appropriate treatment. Since methicillin-resistant Staphylococcus aureus (MRSA) is a frequent pathogen in VAP, rapid identification of it, is pivotal. Our aim was to evaluate the utility of quantitative polymerase chain reaction (qPCR) as a useful method for etiologic diagnoses of MRSA pneumonia. Methods We performed qPCR for mecA, S. aureus-specific femA-SA, and S. epidermidis-specific femA-SE genes from bronchoalveolar lavage or bronchial washing samples obtained from clinically-suspected VAP. Molecular identification of MRSA was based on the presence of the mecA and femA-SA gene, with the absence of the femA-SE gene. To compensate for the experimental and clinical conditions, we spiked an internal control in the course of DNA extraction. We estimated number of colony-forming units per mL (CFU/mL) of MRSA samples through a standard curve of a serially-diluted reference MRSA strain. We compared the threshold cycle (Ct) value with the microbiologic results of MRSA. Results We obtained the mecA gene standard curve, which showed the detection limit of the mecA gene to be 100 fg, which corresponds to a copy number of 30. We chose cut-off Ct values of 27.94 (equivalent to 1×104 CFU/mL) and 21.78 (equivalent to 1×105 CFU/mL). The sensitivity and specificity of our assay were 88.9% and 88.9% respectively, when compared with quantitative cultures. Conclusion Our results were valuable for diagnosing and identifying pathogens involved in VAP. We believe our modified qPCR is an appropriate tool for the rapid diagnosis of clinical pathogens regarding patients in the intensive care unit.

Successful Removal of Endobronchial Lipoma by Flexible Bronchoscopy Using Electrosurgical Snare

A 62-year-old man with a chronic cough presented with atelectasis of the left upper lobe on chest X-ray. Chest computed tomography showed an atelectasis in the left upper lobe with bronchial wall thickening, stenosis, dilatation, and mucoid impaction. We performed bronchoscopy and found a well-circumscribed mass on the left upper lobe bronchus. The mass was removed by flexible bronchoscopy using an electrosurgical snare and diagnosed with lipoma. An endobronchial lipoma is a rare benign tumor that can be treated by a surgical or endoscopic approach. We report the successful removal of endobronchial lipoma via flexible bronchoscopic electrosurgical snare.

Tracheal Stenosis after Tracheostomy Treated Successfully with Papillotome Electrocautery

A 39-year-old woman presented with symptoms of dyspnea. Ten years previously, she had received a tracheostomy because of the decision to not continue taking an anticonvulsant drug. Presently, chest computed tomography showed diffuse stenosis and focal web at the cervical trachea. We performed bronchoscopy and found a two-thirds reduction of the upper trachea due to the web-like fibrotic stenosis. Papillotome electrocautery removed the stenotic lesion. Endobronchial electrocautery is a valuable tool with potential for therapy of an endobronchial obstructing airway lesion. We report this case to introduce the successful treatment with papillotome electrocautery.

Abstract 4003: MicroRNA 99b down-regulation in lung cancer tissues leads to fibroblast growth factor receptor 3 up-expression and acceleration of proliferation

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Background: Dysregulation of miRNA expression has been identified in a number of cancers and an accumulating data indicate that some miRNAs can function as tumor suppressors or oncogenes and are important in cancer development. Deletion or loss of function of a tumor-suppressing miRNA results in overexpression of target oncogenes. Conversely, activation or overexpression of an oncogenic miRNA results in silencing of tumor-suppressing target genes. According to miRNA profiles on microarray, miR-99b was down-expressed in Korean lung cancer. FGFR-3 is predicted target of miR-99b through two public algorithms. FGFR-3 has been demonstrated to be involved in the RAS/RAF/MEK/MAPK pathway through activation of p90 ribosomal S6 kinase. It has been reported that FGFRs are frequently overexpressed in NSCLC cell lines, suggesting that an FGFR-dependent autocrine signaling pathway may operate in a subset of NSCLCs. Material & method: We studied expression of miR-99b and FGFR-3 using quantitative reverse transcription PCR (qRT-PCR) in lung cancer tissue. To examine whether miR-99b could regulate FGFR-3 in lung cancer, we performed transient transfection of pre-miR-99b into lung cancer cell line, then we performed qRT-PCR and western blot in HCC1438, HCC95, and H522 cells for analysis of FGFR-3 expression. We hypothesized the miR-99b has a role of inhibitor cell growth in lung cancer. To test this hypothesis, we performed cell proliferation assay. Results: miR-99b was down-regulated and FGFR-3 was up-regulated in lung cancer. Over-expression of miR-99b induced marked reduction of FGFR-3 mRNA levels and protein level in lung cancer cell line HCC1438, HCC95, and H522. The growth rate in miR-99b precursor treated cell was lower than in negative control of miR treated cell. Conclusion: Abnormal down-regulation of miR-99b could lead to the over-expression of FGFR-3 in lung cancer. miR-99b may be a potent tumor suppressor and may be a potential candidate of therapeutic tool in lung cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4003. doi:10.1158/1538-7445.AM2011-4003