Podoplanin promotes progression of malignant pleural mesothelioma by regulating motility and focus formation.

Malignant pleural mesothelioma (MPM) is characterized by dissemination and aggressive growth in the thoracic cavity. Podoplanin (PDPN) is an established diagnostic marker for MPM, but the function of PDPN in MPM is not fully understood. The purpose of this study was to determine the pathogenetic function of PDPN in MPM. Forty-seven of 52 tumors (90%) from Japanese patients with MPM and 3/6 (50%) MPM cell lines tested positive for PDPN. Knocking down PDPN in PDPN-high expressing MPM cells resulted in decreased cell motility. In contrast, overexpression of PDPN in PDPN-low expressing MPM cells enhanced cell motility. PDPN stimulated motility was mediated by activation of the RhoA/ROCK pathway. Moreover, knocking down PDPN with short hairpin (sh) RNA in PDPN-high expressing MPM cells resulted in decreased development of a thoracic tumor in mice with severe combined immune deficiency (SCID). In sharp contrast, transfection of PDPN in PDPN-low expressing MPM cells resulted in an increase in the number of Ki-67-positive proliferating tumor cells and it promoted progression of a thoracic tumor in SCID mice. Interestingly, PDPN promoted focus formation in vitro, and a low level of E-cadherin expression and YAP1 activation was observed in PDPN-high MPM tumors. These findings indicate that PDPN is a diagnostic marker as well as a pathogenetic regulator that promotes MPM progression by increasing cell motility and inducing focus formation. Therefore, PDPN might be a pathogenetic determinant of MPM dissemination and aggressive growth and may thus be an ideal therapeutic target.

Akt Kinase-Interacting Protein 1 Signals through CREB to Drive Diffuse Malignant Mesothelioma.

Diffuse malignant mesothelioma (DMM) is a tumor of serosal membranes with propensity for progressive local disease. Because current treatment options are largely ineffective, novel therapeutic strategies based on molecular mechanisms and the disease characteristics are needed to improve the outcomes of patients with this disease. Akt kinase interacting protein 1 (Aki1; Freud-1/CC2D1A) is a scaffold protein for the PI3K-PDK1-Akt signaling module that helps determine receptor signal selectivity for EGFR. Aki1 has been suggested as a therapeutic target, but its potential has yet to be evaluated in a tumor setting. Here, we report evidence supporting its definition as a therapeutic target in DMM. In cell-based assays, Aki1 silencing decreased cell viability and caused cell-cycle arrest of multiple DMM cell lines via effects on the PKA-CREB1 signaling pathway. Blocking CREB activity phenocopied Aki1 silencing. Clinically, Aki1 was expressed in most human DMM specimens where its expression correlated with phosphorylated CREB1. Notably, Aki1 siRNA potently blocked tumor growth in an orthotopic implantation model of DMM when administered directly into the pleural cavity of tumor-bearing mice. Our findings suggest an important role for the Aki1-CREB axis in DMM pathogenesis and provide a preclinical rationale to target Aki1 by intrathoracic therapy in locally advanced tumors.

Therapeutic activity of glycoengineered anti-GM2 antibodies against malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is a rare and highly aggressive neoplasm that arises from the pleural, pericardial, or peritoneal lining. Although surgery, chemotherapy, radiotherapy, and combinations of these therapies are used to treat MPM, the median survival of such patients is dismal. Therefore, there is a compelling need to develop novel therapeutics with different modes of action. Ganglioside GM2 is a glycolipid that has been shown to be overexpressed in various types of cancer. However, there are no published reports regarding the use of GM2 as a potential therapeutic target in cases of MPM. In this study, we evaluated the efficacy of the anti-GM2 antibody BIW-8962 as an anti-MPM therapeutic using in vitro and in vivo assays. Consequently, the GM2 expression in the MPM cell lines was confirmed using flow cytometry. In addition, eight of 11 cell lines were GM2-positive (73%), although the GM2 expression was variable. BIW-8962 showed a significant antibody-dependent cellular cytotoxicity activity against the GM2-expressing MPM cell line MSTO-211H, the effect of which depended on the antibody concentration and effector/target ratio. In an in vivo orthotropic mouse model using MSTO-211H cells, BIW-8962 significantly decreased the incidence and size of tumors. Additionally, the GM2 expression was confirmed in the MPM clinical specimens. Fifty-eight percent of the MPM tumors were positive for GM2, with individual variation in the intensity and frequency of staining. These data suggest that anti-GM2 antibodies may become a therapeutic option for MPM patients.

Snail expression is associated with a poor prognosis in malignant pleural mesotheliomas.

BACKGROUND: Malignant pleural mesotheliomas (MPMs) are aggressive tumors with a poor prognosis. We aimed to clarify the mechanisms of epithelial-to-mesenchymal transition (EMT) in MPMs by analyzing the expressions of EMT-associated transcription factors and E-cadherin in relation to tumor proliferation rates and patient survival. METHODS: One hundred nine patients with MPMs were investigated. Among these patients, there were 61 epithelioid tumors, 21 sarcomatoid tumors, 20 biphasic tumors, and 7 desmoplastic tumors. Immunohistochemical analyses were performed to evaluate the expressions of Snail, ZEB1, Twist, E-cadherin, and the Ki-67 proliferation index. RESULTS: The expressions of Snail and ZEB1 were significantly higher in the nonepithelioid tumors than in the epithelioid tumors (p<0.0001 and p=0.0051, respectively). Furthermore, the E-cadherin expression was significantly lower in the Snail-high tumors than in the Snail-low tumors (p=0.0423). The E-cadherin expression was significantly lower in the nonepithelioid tumors than in the epithelioid tumors (p=0.0126). The Ki-67 proliferation index was significantly higher in the nonepithelioid tumors than in the epithelioid tumors (p=0.025). Patient survival was significantly lower in patients with Snail-high MPMs than in those with Snail-low MPMs (p=0.0016), especially in patients with nonepithelioid tumors (p=0.0089). The multivariate analysis also demonstrated that nuclear Snail expression was a significant predictor of poor prognosis in patients with MPMs (p=0.0142). CONCLUSIONS: The Snail expression is associated with EMT and a poor prognosis in MPMs. Snail could be a potential molecular target for the treatment of patients with MPMs.

Intratumoral Wnt2B expression affects tumor proliferation and survival in malignant pleural mesothelioma patients.

Malignant pleural mesothelioma (MPM) is an aggressive thoracic tumor with a poor prognosis. We performed a comprehensive clinical study on the intratumoral expression of Wnt1, Wnt2B and Wnt5A in MPM. One hundred and seven MPM patients were investigated. Immunohistochemistry was performed to evaluate the intratumoral expression of Wnt1, Wnt2B, Wnt5A, survivin and c-Myc, and the Ki-67 proliferation index. The apoptotic index was evaluated by the TUNEL method. Among the 107 MPMs, 23 MPMs (21.5%) were Wnt1-high tumors, 72 MPMs (67.3%) were Wnt2B-high tumors and 54 MPMs (50.5%) were Wnt5A-high tumors. There was no correlation among the levels of Wnt expression. The percentage of Wnt2B-positive tumors was significantly higher compared to that of the other Wnts (p<0.0001). Furthermore, intratumoral Wnt2B expression significantly correlated with the expression of survivin (p<0.001) and c-Myc (p<0.001). Regarding tumor biology, the Ki-67 proliferation index was significantly higher in the Wnt2B-high tumors than in the Wnt2B-low tumors (p=0.0438). In addition, the overall survival was significantly lower in patients with Wnt2B-high tumors than in those with Wnt2B-low tumors (p=0.0238). A Cox multivariate analysis also demonstrated the Wnt2B status to be a significant prognostic factor in MPM patients (p=0.0042). Intratumoral Wnt2B expression was associated with the expression of survivin and c-Myc, tumor proliferation and patient survival in MPM. Wnt2B is a potential molecular target for the treatment of Wnt2B-overexpressing MPMs.

Pleural mesothelioma instigates tumor-associated fibroblasts to promote progression via a malignant cytokine network.

The tumor microenvironment is crucial to the progression of various malignancies. Malignant pleural mesothelioma (MPM), which originates from the pleura, grows aggressively in the thoracic cavity. Here we describe an orthotopic implantation SCID mouse model of MPM and demonstrate that α-SMA-positive fibroblast-like cells accumulate in the tumors produced by the human MPM cell lines MSTO-211H and Y-Meso-14. We assessed the interaction between MPM cells and their microenvironments, focusing on tumor-associated fibroblasts. MSTO-211H and Y-Meso-14 cells produced fibroblast growth factor-2 (FGF-2) and/or platelet-derived growth factor-AA (PDGF-AA); they also enhanced growth, migration, and production of hepatocyte growth factor (HGF) by human lung fibroblast MRC-5 cells. MRC-5 cells stimulated HGF-mediated growth and migration of MSTO-211H and Y-Meso-14 cells in an in vitro coculture system. In the orthotopic model, tumor formation by MSTO-211H and Y-Meso-14 cells was significantly inhibited by TSU-68, an inhibitor of FGF, VEGF, and PDGF receptors; imatinib, an inhibitor of PDGF receptors; and NK4, an antagonist of HGF. Histological analyses of clinical specimens from 51 MPM patients revealed considerable tumor-associated fibroblasts infiltration and expression of HGF, together with FGF-2 or PDGF-AA, in tumors. These findings indicate that MPM instigates tumor-associated fibroblasts, promoting tumor progression via a malignant cytokine network. Regulation of this cytokine network may be therapeutically useful for controlling MPM.

Mutations in Keap1 are a potential prognostic factor in resected non-small cell lung cancer.

BACKGROUND: Mutations in Kelch-like ECH-associated protein 1 (Keap1) have been reported to protect tumor cells from chemotherapeutic agents. However, their prognostic significance in nonsmall cell lung cancer (NSCLC) is still unclear. In this study, we examined the effect of Keap1 gene mutations on survival and disease-free interval using resected primary NSCLC tissue. METHODS: We retrospectively analyzed the tumors from 79 patients with completely resected pathological Stage I-II NSCLC for the presence of Keap1 gene mutations and examined the prognosis of the patients. RESULTS: Keap1 gene mutations were detected in four patients (5.1%). The postoperative 5-year survival rate for patients with Keap1 mutations was significantly lower than those without a mutation (25% vs. 76%, P = 0.038). The postoperative 5-year disease-free survival rate for patients with a mutant Keap1 tumor was slightly lower than for patients with Keap1 wild-type tumors (25% vs. 66%, P = 0.057). CONCLUSIONS: Keap1 gene mutations are likely to be associated with a worse prognosis and lower postoperative disease-free survival rates in pathological Stage I-II NSCLC.

Clinicopathologic features of non-small-cell lung cancer with EML4-ALK fusion gene.

BACKGROUND: A fusion gene between echinoderm microtubule-associated protein-like 4 (EML4) and the anaplastic lymphoma kinase (ALK) has recently been identified in nonsmall-cell lung cancers (NSCLCs). We screened for EML4-ALK fusion genes and examined the clinicopathological and genetic characteristics of fusion-harboring NSCLC tumors. METHODS: We examined 313 NSCLC samples from patients who underwent resection at our hospital between May 2001 and July 2005. We screened for the fusion genes using reverse-transcription polymerase chain reaction (RT-PCR) assay and confirmed the results with direct sequencing. We also examined mutations in the epidermal growth factor receptor (EGFR), KRAS, and ERBB2 genes. RESULTS: Five EML4-ALK fusion genes were detected (four from 111 female samples and one from 202 male samples; 1.6% overall). All five genes were found in adenocarcinomas and accounted for 2.4% of the 211 adenocarcinoma samples. One EML4-ALK fusion was variant 1, and two were variant 3. In addition, we also found two new fusion variants. Patients with fusion-positive tumors were nonsmokers or light smokers. Among the 211 adenocarcinomas, mutations in EGFR, KRAS, and ERBB2 were detected in 105, 29, and 7 tumors, respectively. Interestingly, all of the fusion-positive NSCLCs had no mutations within these genes. CONCLUSIONS: EML4-ALK fusion genes were observed predominantly in adenocarcinomas, in female or nonsmoking populations. Additionally, the EML4-ALK fusions were mutually exclusive with mutations in the EGFR, KRAS, and ERBB2 genes.

A disintegrin and metalloprotease 12 (ADAM12) is a prognostic factor in resected pathological stage I lung adenocarcinoma.

BACKGROUND AND OBJECTIVES: A disintegrin and metalloprotease 12 (ADAM12) has multiple domains and functions, and it plays important roles in the development of cancer. We conducted a retrospective study to determine whether the expression of the membrane type of ADAM12 (ADAM12-L) could be a prognostic factor in resected pathological (p-) stage I lung adenocarcinoma. METHODS: ADAM12-L mRNA expression was quantified by a reverse-transcription polymerase chain reaction in tissue samples from 84 completely resected p-stage I lung adenocarcinoma patients. The patients were divided into ADAM12-L-Low and ADAM12-L-High groups, and correlations with clinicopathologic features were obtained. RESULTS: Five-year survival rates of the ADAM12-L-Low and ADAM12-L-High groups were 95.1% and 71.9%, respectively. The postoperative prognosis for the ADAM12-L-High group was significantly poorer than for the ADAM12-L-Low group (P = 0.006). Multivariate analysis confirmed that high expression of ADAM12-L was an independent factor for poor prognosis (P = 0.007, hazard ratio 8.288). The ADAM12-L-High group was less differentiated and had a significantly higher rate of cancer recurrence. CONCLUSIONS: ADAM12-L mRNA expression is an independent prognostic factor in resected p-stage I lung adenocarcinoma, and is significantly correlated with tumor differentiation stage and postoperative cancer recurrence.

D2-40-positive lymphatic vessel density is a poor prognostic factor in squamous cell carcinoma of the lung.

BACKGROUND: Experimental studies have revealed that D2-40 is useful in identifying the presence of lymphatic invasion in various malignant neoplasms, but the clinical significance remains unclear. The purpose of this study is to assess the clinical significance of D2-40 status in completely resected non-small cell lung cancer. METHODS: A total of 215 consecutive patients with resected pathological stage I-IIIA non-small cell lung cancer were reviewed. Expression of D2-40 in tumor cells and in endothelial cells was examined immunohistochemically, and D2-40-positive lymphatic vessel density (LVD) at the tumor periphery were quantitatively evaluated. RESULTS: D2-40 expression on tumor cells was positive in 55 (25.6%) of 215 patients, and the incidence was significantly higher in squamous cell carcinoma (SCC) patients than in adenocarcinoma patients (48.8% vs. 8.6%, P < .001). D2-40 was also seen on lymphatic vessels in tumor tissues, and the mean number of D2-40-LVD was significantly decreased along with differentiation of tumor cells (P = .038). For all histologic types of tumors, there was no difference in the postoperative survival between higher D2-40-LVD patients and lower D2-40-LVD patients. For SCC, however, lower D2-40-LVD patients showed a significantly better survival than higher D2-40-LVD patients (5-year survival rates, 52.9% vs. 78.9%, P = .040), which was confirmed by a multivariate analyses (P = .048). CONCLUSIONS: D2-40 expression on tumor cells was more frequently seen in SCC than in adenocarcinoma of the lung. In addition, D2-40 expression on lymphatic vessels in tumor tissues was a statistically significant prognostic factor in SCC.

Higher expression of chemokine receptor CXCR7 is linked to early and metastatic recurrence in pathological stage I nonsmall cell lung cancer.

BACKGROUND: The authors elucidated particular chemokine receptors that are expressed on lung cancer cells, as well as the clinical significance of the expression of these chemokine receptors in completely resected nonsmall cell lung cancer (NSCLC). METHODS: The authors examined gene expression of chemokine receptors (CCR1-11, CXCR1-7, XCR1, and CX3CR1) in 11 cell lines of lung cancer, and gene expression of CXCR3, CXCR4, and CXCR7 (CXCR3/4/7) in surgical specimens of 127 patients who underwent complete resection for their NSCLC between May 2001 and December 2002, using quantitative real-time reverse transcriptase-polymerase chain reaction (PCR). Mutation detection analysis of the EGFR genes using the PCR single-strand conformational polymorphism method was evaluated in patients with pathological (p-) stage I adenocarcinoma. RESULTS: Substantial expression of CXCR3/4/7 mRNA was observed in all NSCLC cell lines examined. In p-stage I NSCLC, CXCR4 and CXCR7 expression values in patients with postoperative metastatic recurrence (Rec-Distant) were significantly higher than in those without recurrences (P = .003 and P = .007, respectively). In addition, the 5-year disease-free survival (DFS) rate of high CXCR7-expressing patients (63.2%) was significantly lower than that of low CXCR7-expressing patients (84.8%) (P = .033). The EGFR mutation was significantly more frequent in patients with higher CXCR7 expression (14 of 21 patients) than in those with lower CXCR7 expression (12 of 32 patients) (P = .038). A multivariate analysis confirmed that high CXCR7 expression was an independent and significant factor predicting a poor DFS in p-stage I NSCLC patients (P = .041). CONCLUSIONS: Higher expression of CXCR7 is associated with Rec-Distant and poor DFS in patients with p-stage I NSCLC.

Expression status of folate receptor alpha is significantly correlated with prognosis in non-small-cell lung cancers.

BACKGROUND: To evaluate the prognostic value of folate receptor alpha (FOLR1) and/or reduced folate carrier (RFC1) expression, which are well-characterized folate transporters, in completely resected non-small-cell lung cancer (NSCLC). METHODS: We quantitatively examined gene expression of FOLR1 and RFC1 in surgical specimens resected from NSCLC patients. A total of 119 consecutive patients from January 2003 to June 2004 were included. RESULTS: In adenocarcinoma, the FOLR1 gene expression was downregulated in smokers and male patients (P = 0.006 and P < 0.001, respectively). In addition, FOLR1 expression values in patients with well-differentiated, early p-stage, pT1, pN0, EGFR mutant, and p53 wild-type cancers were significantly higher than those for poorly differentiated, advanced p-stage, pT2-4, pN1-3, EGFR wild-type, and p53 mutant (P < 0.001, P < 0.001, P < 0.001, P = 0.002, P < 0.001 and P = 0.023, respectively). In squamous cell carcinoma, FOLR1 expression values in patients with pN1-3 was significantly higher than those with pN0 (P = 0.037). Moreover, the 3-year survival rate and disease-free survival rate of high-FOLR1-expressing patients (94.7% and 75.4%) were significantly higher than those of low-FOLR1-expressing patients (80.9% and 60.8%) (P = 0.008 and P = 0.038). A multivariate analysis confirmed that high FOLR1 expression was an independent and significant factor predicting a favorable prognosis (P = 0.043). CONCLUSIONS: Higher levels of FOLR1 appear to be associated with better prognoses for patients with lung adenocarcinomas.

[Placement of an ultraflex nitinol stent for severe tracheobronchial obstruction in a case of relapsing polychondritis].

A 59-year-old man, who had been treated for bronchial asthma since 2000, was hospitalized with high fever and productive cough in November 2003. Chest radiography on admission showed consolidations in both lower lung fields, and computed tomography demonstrated anteroposterior narrowing of both main bronchi. A physical examination revealed deformity of auricular cartilage and saddle nose, and we diagnosed him relapsing polychondritis (RP). When he was readmitted 4 months later because of severe tracheobronchial stenosis and respiratory failure he required mechanical ventilation, but it was difficult to wean him from the ventilator. Self-expandable metallic stents were placed in the left main bronchus and the trachea. After the procedure, he was successfully weared from mechanical ventilation. Since airway complications of RP can be fatal, stent implantation should be considered in the management of RP with airway manifestations.