Shin-ichiro Iwakami

Mutation analysis of the TSC1 and TSC2 genes in Japanese patients with pulmonary lymphangioleiomyomatosis

AbstractPulmonary lymphangioleiomyomatosis (LAM) is a destructive lung disease characterized by a diffuse hamartomatous proliferation of smooth muscle cells (LAM cells) in the lungs. Pulmonary LAM can occur as an isolated form (sporadic LAM) or in association with tuberous sclerosis complex (TSC) (TSC-LAM), a genetic disorder with autosomal dominant inheritance with various expressivity resulting from mutations of either the TSC1 or TSC2 gene. We examined mutations of both TSC genes in 6 Japanese patients with TSC-LAM and 22 patients with sporadic LAM and identified six unique and novel mutations. TSC2 germline mutations were detected in 2 (33.3%) of 6 patients with TSC-LAM and TSC1 germline mutation in 1 (4.5%) of 22 sporadic LAM patients. In accordance with the tumor-suppressor model, loss of heterozygosity (LOH) was detected in LAM cells from 3 of 4 patients with TSC-LAM and from 4 of 8 patients with sporadic LAM. Furthermore, an identical LOH or two identical somatic mutations were demonstrated in LAM cells microdissected from several tissues, suggesting LAM cells can spread from one lesion to another. Our results from Japanese patients with LAM confirmed the current concept of pathogenesis of LAM: TSC-LAM has a germline mutation but sporadic LAM does not; sporadic LAM is a TSC2 disease with two somatic mutations; and a variety of TSC mutations causes LAM. However, our study indicates that a fraction of sporadic LAM can be a TSC1 disease; therefore, both TSC genes should be examined, even for patients with sporadic LAM.

Clinical and genetic spectrum of Birt–Hogg–Dubé syndrome patients in whom pneumothorax and/or multiple lung cysts are the presenting feature

Background Birt–Hogg–Dubé syndrome (BHDS) is an inherited autosomal genodermatosis characterised by fibrofolliculomas of the skin, renal tumours and multiple lung cysts. Genetic studies have disclosed that the clinical picture as well as responsible germline FLCN mutations are diverse. Objectives BHDS may be caused by a germline deletion which cannot be detected by a conventional genetic approach. Real-time quantitative polymerase chain reaction (qPCR) may be able to identify such a mutation and thus provide us with a more accurate clinical picture of BHDS. Methods This study analysed 36 patients with multiple lung cysts of undetermined causes. Denaturing high performance liquid chromatography (DHPLC) was applied for mutation screening. If no abnormality was detected by DHPLC, the amount of each FLCN exon in genome was quantified by qPCR. Results An FLCN germline mutation was found in 23 (63.9%) of the 36 patients by DHPLC and direct sequencing (13 unique small nucleotide alterations which included 11 novel mutations). A large genomic deletion was identified in two of the remaining 13 patients by qPCR (one patient with exon 14 deletion and one patient with a deletion encompassing exons 9 to 14). Mutations including genomic deletions were most frequently identified in the 3′-end of the FLCN gene including exons 12 and 13 (13/25=52.0%). The BHDS patients whose multiple cysts prompted the diagnosis in this study showed a very low incidence of skin and renal involvement. Conclusions BHDS is due to large deletions as well as small nucleotide alterations. Racial differences may occur between Japanese and patients of European decent in terms of FLCN mutations and clinical manifestations.

Characteristics of pulmonary cysts in Birt–Hogg–Dubé syndrome: Thin-section CT findings of the chest in 12 patients

PURPOSE To describe in detail the characteristic chest computed tomography (CT) findings of Birt-Hogg-Dubé (BHD) syndrome. MATERIALS AND METHODS Thin-section chest CT scans of consecutive 12 patients with genetically diagnosed BHD syndrome were retrospectively evaluated by two observers, especially about the characteristics (distribution, number, size, shape and relation to pleura) of pulmonary cysts. Interobserver agreement in the identification of abnormalities on the CT images was achieved using the κ statistic, and the degree of interobserver correlation for the characterization of pulmonary cysts was assessed using the Spearman rank correlation coefficient. RESULTS Multiple pulmonary cysts were seen in all patients. The number of cysts in each patient was various (range, 29-407), and cysts of various sizes (from a few mm to 2 cm or more) were seen in all patient. 76.6% (mean) of cysts were irregular-shaped, and 40.5% (mean) of cysts were located along the pleura. The mean extent score of cysts was 13% of the whole lung, and the distribution of cysts was predominantly in the lower medial zone. Finally, cysts abutting or including the proximal portions of lower pulmonary arteries or veins were also seen in all patients. CONCLUSION Multiple, irregular-shaped cysts of various sizes with lower medial lung zone predominance are characteristic CT findings of BHD syndrome. Cysts abutting or including the proximal portions of lower pulmonary arteries or veins may also exist in this syndrome in a high probability.

Hypoxia increases gefitinib-resistant lung cancer stem cells through the activation of insulin-like growth factor 1 receptor.

Accumulating evidence indicates that a small population of cancer stem cells (CSCs) is involved in intrinsic resistance to cancer treatment. The hypoxic microenvironment is an important stem cell niche that promotes the persistence of CSCs in tumors. Our aim here was to elucidate the role of hypoxia and CSCs in the resistance to gefitinib in non-small cell lung cancer (NSCLC) with activating epidermal growth factor receptor (EGFR) mutation. NSCLC cell lines, PC9 and HCC827, which express the EGFR exon 19 deletion mutations, were exposed to high concentration of gefitinib under normoxic or hypoxic conditions. Seven days after gefitinib exposure, a small fraction of viable cells were detected, and these were referred to as “gefitinib-resistant persisters” (GRPs). CD133, Oct4, Sox2, Nanog, CXCR4, and ALDH1A1–all genes involved in stemness–were highly expressed in GRPs in PC9 and HCC827 cells, and PC9 GRPs exhibited a high potential for tumorigenicity in vivo. The expression of insulin-like growth factor 1 (IGF1) was also upregulated and IGF1 receptor (IGF1R) was activated on GRPs. Importantly, hypoxic exposure significantly increased sphere formation, reflecting the self-renewal capability, and the population of CD133- and Oct4-positive GRPs. Additionally, hypoxia upregulated IGF1 expression through hypoxia-inducible factor 1α (HIF1α), and markedly promoted the activation of IGF1R on GRPs. Knockdown of IGF1 expression significantly reduced phosphorylated IGF1R-expressing GRPs under hypoxic conditions. Finally, inhibition of HIF1α or IGF1R by specific inhibitors significantly decreased the population of CD133- and Oct4-positive GRPs, which were increased by hypoxia in PC9 and HCC827 cells. Collectively, these findings suggest that hypoxia increased the population of lung CSCs resistant to gefitinib in EGFR mutation-positive NSCLC by activating IGF1R. Targeting the IGF1R pathway may be a promising strategy for overcoming gefitinib resistance in EGFR mutation-positive NSCLC induced by lung CSCs and microenvironment factors such as tumor hypoxia.

Hydration with magnesium and mannitol without furosemide prevents the nephrotoxicity induced by cisplatin and pemetrexed in patients with advanced non-small cell lung cancer

BACKGROUND The aim of this study was to examine the effect of hydration with magnesium and mannitol without furosemide on the nephrotoxocity accompanying combination chemotherapy using cisplatin and pemetrexed in patients with advanced non-small cell lung cancer (NSCLC). METHODS Fifty patients with NSCLC who received cisplatin plus pemetrexed, using either old hydration protocol including normal saline with mannitol and furosemide, or a new one including normal saline with magnesium and mannitol without furosemide were retrospectively analyzed. Nephrotoxicity was compared between patients treated using the old protocol and those treated with the new protocol. Univariate and multivariate analyses were performed to identify the independent factors associated with protection against nephrotoxicity in patients with NSCLC who received cisplatin plus pemetrexed. RESULTS Thirty patients received the old hydration protocol, while 20 patients were treated using the new hydration protocol. The patients treated using the new hydration protocol showed a significantly greater increase in creatinine clearance (P=0.0004) and a decrease in the serum creatinine level (P=0.0148) after one course of chemotherapy compared with those treated using the old hydration protocol. There were no differences in the chemotherapeutic response or overall survival between the groups (P=0.572). The new hydration protocol with supplemented magnesium with mannitol without furosemide was an independent factor for the protection against nephrotoxicity induced by cisplatin and pemetrexed in patients with advanced NSCLC [HR 0.232 (95% CI: 0.055-0.986), P=0.039]. CONCLUSIONS These results demonstrate that the new hydration protocol comprising supplementation with magnesium without furosemide could prevent the nephrotoxicity induced by cisplatin and pemetrexed without affecting the treatment outcome.

Osteopontin-mediated enhanced hyaluronan binding induces multidrug resistance in mesothelioma cells

Malignant pleural mesothelioma (MPM) is resistant to chemotherapy and thus shows a dismal prognosis. Osteopontin (OPN), a secreted noncollagenous and phosphoprotein, is suggested to be involved in the pathogenesis of MPM. However, the precise role of OPN, especially in the multidrug resistance of MPM, remains to be elucidated. We therefore established stable transfectants (ACC-MESO-1/OPN), which constitutively express OPN, to determine its role in the chemoresistance observed in MPM. The introduction of the OPN gene provides MPM cells with upregulated multidrug resistance through the mechanism of enhanced hyaluronate (HA) binding. The expression of CD44 variant isoforms, which inhibit HA binding, significantly decreased in ACC–MESO–1/OPN cells in comparison to control transfectants. Interestingly, the inhibition of the HA-CD44 interaction abrogated multidrug resistance in the ACC–MESO–1/OPN, thus suggesting the involvement of the surviving signal emanating from the HA-CD44 interaction. An enhanced level of the p-Akt in ACC–MESO–1/OPN cells was observed, and was diminished by CD44 siRNA. Inhibition of the Akt phosphorylation increased in number of the cells underwent apoptosis induced by NVB, VP-16 and GEM. Collectively, these results indicate that OPN is strongly involved in multidrug resistance by enhancing the CD44 binding to HA.

Osteopontin is involved in the formation of malignant pleural effusion in lung cancer

Malignant pleural effusion (MPE) is associated with advanced-stage lung cancer and is a poor prognostic sign for these patients. Osteopontin (OPN) is a multifunctional cytokine that is involved in the tumor progression and angiogenesis of lung cancer cells. The purpose of this study is to investigate and provide evidence for the role of OPN in the formation of MPE associated with lung cancer. In this study, we established an OPN knockdown murine lung cancer cell line, 3LL cells, utilizing the small interfering RNA (siRNA) technique. To reveal the effect of OPN on the formation of MPE associated with lung cancer, we directly injected OPN knockdown 3LL cells, 3LL/OPN siRNA, or control cells, 3LL/control siRNA, into the pleural space of C57BL/6 mice. OPN knockdown significantly reduced the formation of MPE, but did not inhibit in vivo tumor growth of 3LL cells in mice. Vascular endothelial growth factor (VEGF) concentration in MPE was markedly decreased in the 3LL/OPN siRNA in comparison with that of the 3LL/control siRNA. In vitro, recombinant OPN protein enhanced VEGF secretion from human umbilical vein endothelial cell (HUVEC) or human mesothelial cell line, Met5A cells, in a concentration-dependent manner. These results suggest that OPN is positively involved in the formation of MPE of lung cancer presumably by promoting VEGF secretion from vascular endothelial cells or mesothelial cells. OPN could be an effective target molecule for reducing MPE in lung cancer patients.

Osteopontin is involved in the development of acquired chemo-resistance of cisplatin in small cell lung cancer

Osteopontin (OPN) is a multi-functional cytokine involved in cell survival, migration and adhesion which is associated with tumorigenesis, progression and metastasis. However, the role of OPN in chemo-sensitivity of human lung cancer has not yet been elucidated. The purpose of this study is to investigate the role of OPN in chemo-sensitivity of lung cancer cells. We developed a stable OPN transfectant (SBC-3/OPN) and a control transfectant (SBC-3/NEO) from human small cell lung cancer cell line, SBC-3. SBC-3/OPN cells were more resistant to cisplatin than SBC-3/NEO cells. Multi-drug resistance-associated protein (MRP) does not appear to be involved in the development of acquired chemo-resistance, since MRP inhibitor did not alter chemo-sensitivity. After exposure to cisplatin, the apoptotic SBC-3/OPN cells were reduced in number compared to SBC-3/NEO cells. Treatment with cisplatin revealed that the expression of anti-apoptotic protein, bcl-2, was down-regulated in SBC-3/NEO cells, while that of SBC-3/OPN cells was not altered. In contrast, pro-apoptotic protein, bax, was not altered in both SBC-3/OPN and SBC-3/NEO cells, thus bcl-2/bax ratio was decreased in SBC-3/NEO but not altered in SBC-3/OPN cells. Activation of caspase-3 and caspase-9 was increased in SBC-3/NEO cells, but not in SBC-3/OPN cells. Our results suggest that OPN enhances chemo-resistance of cisplatin in SBC-3 cells by suppressing bcl-2 protein down-regulation, thereby blocking the caspase-9- and caspase-3-dependent cell apoptosis.

Diagnostic significance of cerebrospinal fluid EGFR mutation analysis for leptomeningeal metastasis in non-small-cell lung cancer patients harboring an active EGFR mutation following gefitinib therapy failure

BACKGROUND Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have been successfully used to treat patients with non-small cell lung cancer (NSCLC) harboring EGFR mutations. However, despite an initial excellent response, recurrence within one or two years is common. Diagnosis and treatment of leptomeningeal metastasis (LM), a form of NSCLC recurrence, remains particularly difficult. Here, we analyzed the EGFR mutation status of cerebrospinal fluid (CSF) directly using real-time polymerase chain reaction (PCR) and evaluated the efficacy of therapy with erlotinib, an EGFR TKI. PATIENTS AND METHODS Seven NSCLC patients harboring activating EGFR mutations who had developed LM during or after therapy with gefitinib, an EGFR TKI, were retrospectively analyzed. CSF was obtained and subjected to cytological examination and EGFR mutation analysis, including detection of the resistance-associated T790M mutation, using real-time PCR. RESULTS In all seven cases, the EGFR mutation detected in the CSF was the same as that detected in the primary tumor (sensitivity, 100%). Conversely, cytology results were positive in only two patients (sensitivity, 28.6%). No additional T790M mutations were detected. Erlotinib was efficacious in all cases, and improved performance status was achieved for five of the seven patients. The effect of erlotinib treatment was temporary, however, with time to treatment failure (TTF) ranging from 29 to 278 days (median, 65 days) and the interval between commencement of erlotinib treatment and death ranging from 45 to 347 days (median, 168 days). CONCLUSIONS Analysis of EGFR mutations in CSF using a highly sensitive real-time PCR assay is a potentially powerful diagnostic method for LM.

High prevalence of gene abnormalities in young patients with lung cancer

BACKGROUND Recently, driver oncogenes in adenocarcinoma of the lung were identified, and several molecular target agents were introduced in the clinical setting. However, there are few reports on the frequency of gene abnormalities in young patients with lung cancer. MATERIALS AND METHODS Twelve patients with lung adenocarcinoma aged 40 or younger at Juntendo University Urayasu Hospital or Juntendo University Hospital from July 2004 to March 2010 were analyzed for driver oncogene status including EGFR activating mutation, EML4-ALK fusion gene, and K-ras mutation. RESULTS Four patients showed EGFR gene mutation. Five out of 7 EGFR mutation-negative patients showed positive results for EML4-ALK gene fusion. One case whose EGFR mutation was indeterminate. CONCLUSIONS Driver oncogene including EGFR mutation and EML4-ALK fusion gene was identified in 9 of 12 cases (75%). Examination of gene abnormalities is essential in young patients with non-small cell lung cancer to provide the best treatment.