Takashi Kanou

MicroRNA-mediated downregulation of mTOR/FGFR3 controls tumor growth induced by Src-related oncogenic pathways.

The tyrosine kinase c-Src is upregulated in various human cancers, but the molecular mechanisms underlying c-Src-mediated tumor growth remain unclear. Here we examined the involvement of microRNAs in the c-Src-mediated tumor growth. Microarray profiling revealed that c-Src activation downregulates a limited set of microRNAs, including miR-99a, which targets oncogenic mammalian target of rapamycin (mTOR) and fibroblast growth factor receptor 3 (FGFR3). Re-expression of miR-99a suppressed tumor growth of c-Src-transformed cells, and this effect was restored by the overexpression of mTOR. The downregulation of miR-99a was also observed in epidermal growth factor- and Ras-transformed cells, and it was suppressed by inhibiting the mitogen-activated protein kinase (MAPK) pathway. Furthermore, miR-99a downregulation is associated with mTOR/FGFR3 upregulation in various human lung cancer cells/tissues. The tumorigenicity of these cells was suppressed by the introduction of miR-99a. These findings suggest that the miR-99a-mTOR/FGFR3 pathway is crucial for controlling tumor growth in a wide range of human cancers that harbor upregulation of the Src-related oncogenic pathways.

The Transmembrane Adaptor Cbp/PAG1 Controls the Malignant Potential of Human Non–Small Cell Lung Cancers That Have c-Src Upregulation

The tyrosine kinase c-Src is upregulated in various human cancers, although the precise regulatory mechanism underlying this upregulation is unclear. We previously reported that a transmembrane adaptor Csk-binding protein (Cbp; PAG1) plays an important role in controlling the cell transformation that is induced by the activation of c-Src. To elucidate the in vivo role of Cbp, we examined the function of Cbp in lung cancer cell lines and tissues. In this study, we found that Cbp was markedly downregulated in human non–small cell lung cancer (NSCLC) cells. The ectopic expression of Cbp suppressed the anchorage-independent growth of the NSCLC cell lines (A549 and Lu99) that had upregulated c-Src, whereas the Cbp expression had little effect on other NSCLC cell lines (PC9 and Lu65) that express normal levels of c-Src. The expression of Cbp suppressed the kinase activity of c-Src in A549 cells by recruiting c-Src and its negative regulator, C-terminal Src kinase (Csk), to lipid rafts. The treatment with Src inhibitors, such as PP2, dasatinib, and saracatinib, also suppressed the growth of A549 cells. Furthermore, Cbp expression attenuated the ability of A549 cells to form tumors in nude mice, invade in vitro, and metastasize in vivo. In addition, we found a significant inverse correlation between the level of Cbp expression and the extent of lymph node metastasis in human lung cancers. These results indicate that Cbp is required for the Csk-mediated inactivation of c-Src and may control the promotion of malignancy in NSCLC tumors that are characterized by c-Src upregulation. Mol Cancer Res; 9(1); 103–14 ©2010 AACR.

Intraoperative pleural lavage cytology after lung resection as an independent prognostic factor for staging lung cancer

OBJECTIVE Although malignant pleural effusion or dissemination is regarded as T4 per TNM classification of lung cancer, the prognostic significance in staging of pleural lavage cytologic examination remains undetermined. The purpose of this study was to clarify the utility of pleural lavage cytologic staging as a prognostic factor in patients with non-small cell lung cancer. METHODS In 1271 patients with lung cancer who underwent curative resection, intraoperative pleural lavage cytologic examination was performed at thoracotomy (first cytologic examination), immediately after pulmonary resection and mediastinal lymph node dissection (second cytologic examination), and after last washing of pleural cavity (third cytologic examination). Positive first cytologic result represented cytologic positive result before lung resection; positive second and third cytologic results were regarded as cytologic positive results after lung resection. RESULTS Eighty-nine patients (7.0%) had positive findings of pleural lavage cytologic examination before or after lung resection. Five-year survivals were 44.1% for patients with positive results before lung resection and 23.4% for patients with positive results after lung resection, both significantly worse than that for patients with negative results. Multivariate analyses revealed that positive lavage result after lung resection was an independent prognostic factor. We found significantly greater pleural recurrence among patients with positive pleural lavage cytologic results after lung resection than among those with negative results. CONCLUSIONS In addition to TNM classification, results of pleural lavage cytologic examination after lung resection should be considered when staging non-small cell lung cancer. Adjuvant systemic therapy may improve outcome for patients with positive results.

Identification of a New Interaction Mode between the Src Homology 2 Domain of C-terminal Src Kinase (Csk) and Csk-binding Protein/Phosphoprotein Associated with Glycosphingolipid Microdomains

Background: Src homology 2 (SH2) domains are known to specifically bind to phosphotyrosine followed by a few amino acids. Results: A novel interaction region was revealed by the solution structure of the C-terminal Src kinase SH2 domain in complex with the Csk-binding protein. Conclusion: The novel interaction region was required for tumor suppression. Significance: The structure sheds new light on the interaction mode of SH2 domains. Proteins with Src homology 2 (SH2) domains play major roles in tyrosine kinase signaling. Structures of many SH2 domains have been studied, and the regions involved in their interactions with ligands have been elucidated. However, these analyses have been performed using short peptides consisting of phosphotyrosine followed by a few amino acids, which are described as the canonical recognition sites. Here, we report the solution structure of the SH2 domain of C-terminal Src kinase (Csk) in complex with a longer phosphopeptide from the Csk-binding protein (Cbp). This structure, together with biochemical experiments, revealed the existence of a novel binding region in addition to the canonical phosphotyrosine 314-binding site of Cbp. Mutational analysis of this second region in cells showed that both canonical and novel binding sites are required for tumor suppression through the Cbp-Csk interaction. Furthermore, the data indicate an allosteric connection between Cbp binding and Csk activation that arises from residues in the βB/βC loop of the SH2 domain.

Prognostic factors in patients with postoperative brain recurrence from completely resected non-small cell lung cancer

Treatment strategies for brain metastasis from lung cancer have been making progress. The aim of this retrospective analysis was to investigate the post‐recurrent prognostic factors in patients with brain metastasis after complete resection of non‐small cell lung cancer (NSCLC).

Radiotherapy for Postoperative Thoracic Lymph Node Recurrence of Non–Small-Cell Lung Cancer Provides Better Outcomes If the Disease Is Asymptomatic and a Single-Station Involvement

Objective: Thoracic lymph node recurrence after complete resection is common in non–small-cell lung cancer but it mostly occurs along with distant metastases. The recurrent disease might be localized and curative intent radiation therapy is the treatment of choice if no evidence of hematogenous metastasis is observed. We sought to describe the outcomes of thoracic radiotherapy for thoracic lymph node recurrences. Methods: Fifty patients who had developed thoracic lymph node recurrence after complete resection received curative intent radiotherapy between 1997 and 2009. The clinical endpoints included the tumor response, overall survival, progression-free survival, locoregional recurrence within the irradiated field, and any other recurrence. Results: The planned total radiotherapy was completed in 49 patients with minor toxicity. The median follow-up time after radiotherapy was 41 (19–98) months among the survivors. The response to treatment was complete response in 65%, partial response in 24%, and progressive disease in 10% of the evaluated patients. The median overall survival after radiotherapy was 37.3 months. The 5-year overall survival, progression-free survival, and local control rate were 36.1%, 22.2%, and 61.1%, respectively. A multivariate analysis revealed that the absence of symptoms and the involvement of a single lymph node station were significant factors associated with a better overall survival. Conclusions: Radiation therapy for thoracic lymph node recurrence after complete resection is safe and provides acceptable disease control. This treatment provides a better outcome if the disease is asymptomatic and has a single-station involvement. Early detection of the recurrence may thus improve the effectiveness of this treatment.

Peritoneovenous Shunt for Chylous Ascites after Lung Transplantation for Lymphangioleiomyomatosis

A 37-year-old woman with lymphangioleiomyomatosis (LAM) who underwent right single-lung transplantation from a cadaveric donor developed persistent chylous ascites. Despite use of diuretics and sirolimus to reduce ascites-associated symptoms and to prevent gastroesophageal reflex triggered by increased abdominal pressure, the ascites were refractory, and periodic paracenteses were required. With placement of a peritoneovenous shunt (Denver shunt), the patients abdominal circumference decreased, and her symptoms abated. Thus, placement of a peritoneovenous shunt can be an effective management strategy for refractory chylous ascites in patients with LAM, even after lung transplantation.

Primary papillary carcinoma of the thymus with invasion into subcutaneous tissue through the sternum

Thymic carcinoma is a rare malignant neoplasm. We present a Japanese case of papillary carcinoma of thymus in a 64-year-old man that invaded into subcutaneous tissue penetrating the sternum. We describe the clinical and pathologic features of this extremely rare thymic epithelial tumor, with disease-free survival at three years of follow-up.

Successful lobectomy for central large pulmonary arteriovenous malformation

A pulmonary arteriovenous malformation (PAVM) is caused by abnormal communications between the pulmonary arteries and veins. In this study, a 64-year old woman presented with a large PAVM in the central upper lobe of the right lung. As feeding vessels were large and short, the patient was scheduled for resection therapy. By clamping the right main pulmonary artery, the blood flow into the PAVM was controlled and lobectomy was performed safely. Although advances in interventional radiology have led to the introduction of obliterative techniques, surgical resection is still an effective first option for patients with a large, centrally located PAVM.

Granulocyte-colony stimulating factor (G-CSF) producing malignant pleural mesothelioma: Report of a case.

This report presents a case of malignant pleural mesothelioma (MPM) producing granulocyte colony‐stimulating factor (G‐CSF) that was treated by tumor resection. A 76‐year‐old male presented with a huge right‐side chest wall tumor, along with a slight fever and chest wall pain. Laboratory findings showed an increased white blood cell count (64600 cells/μL) and C‐reactive protein level (20.57 mg/dL). The patient underwent surgical removal of the tumor along with tissue from the chest wall and histopathological analysis led to a diagnosis of sarcomatous type of MPM. Immunohistochemical findings for both anti‐human G‐CSF and interleukin‐6 monoclonal antibodies were positive. Although the general condition of the patient quickly improved after surgery, local recurrence occurred two months later and he died of respiratory failure seven months after the operation, though surgery provided symptom relief. G‐CSF‐producing MPMs usually show a poor prognosis, though less‐invasive surgery may be considered for relief of symptoms.