A novel molecular target, superoxide dismutase 1, in ALK inhibitor-resistant lung cancer cells, detected through proteomic analysis.

BACKGROUNDS: To the best of our knowledge, there are no reports of proteomic analysis for the identification of unknown proteins involved in resistance to anaplastic lymphoma kinase (ALK) inhibitors. In this study, we investigated the proteins involved in resistance to alectinib, a representative ALK inhibitor, through proteomic analysis and the possibility of overcoming resistance. METHODS: An ALK-positive lung adenocarcinoma cell line (ABC-11) and the corresponding alectinib-resistant cell line (ABC-11/CHR2) were used. Two-dimensional difference gel electrophoresis (2D DIGE) was performed; the stained gel was scanned and the spots were analyzed using DeCyder TM2D 7.0. Mass spectrometry (MS) with the UltrafleXtreme matrix-assisted laser desorption ionization-tandem time-of-flight (MALDI-TOF/TOF) MS system was performed. For the MS/MS analysis, the samples were spotted on an AnchorChipTM 600 TF plate. The peptide masses obtained in the reflector positive mode were acquired at m/z of 400-6000. MS/MS data were searched against the NCBI protein databases. Growth inhibition was measured using an MTT assay. The isobologram and combination index were calculated based on the median-effect analysis. Western blotting was performed using antibodies, including superoxide dismutase (SOD) 1, MET, ERK, PARP, AKT, and BRCA1. RESULTS: The 2D DIGE for ABC-11 and ABC-11/CHR2 showed different expression levels in about 2000 spots. SOD was identified from spots highly expressed in resistant strains. Western blotting also confirmed SOD1 overexpression in ABC-11/CHR2. siSOD1 enhanced the growth inhibitory effects of alectinib, increased cleaved PARP levels, and decreased pERK, pAKT, and BRCA1 levels with a combination of alectinib. In addition, the combination of LCS-1, an SOD1 inhibitor, and alectinib synergistically suppressed the growth in ABC-11/CHR2, but not in ABC-11. CONCLUSIONS: SOD1 overexpression is thought to be a mechanism for alectinib resistance, suggesting the possibility of overcoming resistance using SOD1 inhibitors.

The complexity of EGFR exon 19 deletion and L858R mutant cells as assessed by proteomics, transcriptomics, and metabolomics.

Most lung adenocarcinoma-associated EGFR tyrosine kinase mutations are either an exon 19 deletion (19Del) or L858R point mutation in exon 21. Although patients whose tumors contain either of these mutations exhibit increased sensitivity to tyrosine kinase inhibitors, progression-free and overall survival appear to be longer in patients with 19Del than in those with L858R. In mutant-transfected Ba/F3 cells, 19Del and L858R were compared by multi-omics analyses including proteomics, transcriptomics, and metabolomics. Proteome analysis identified increased plastin-2, TKT, PDIA5, and ENO1 expression in L858R cells, and increased EEF1G expression in 19Del cells. RNA sequencing showed significant differences between 19Del and L858R cells in 112 genes. Metabolome analysis showed that amino acids, adenylate, guanylate, NADPH, lactic acid, pyruvic acid glucose 6-phosphate, and ribose 5-phosphate were significantly different between the two mutant cells. Because GSH was increased with L858R, we combined osimertinib with the GSH inhibitor buthionine sulfoximine in L858R cells and observed synergistic effects. The complexity of EGFR 19Del and L858R mutant cells was demonstrated by proteomics, transcriptomics, and metabolomics analyses. Therapeutic strategies for lung cancer with different EGFR mutations could be considered because of their different metabolic phenotypes.

Effect of a Cyclooxygenase-2 Inhibitor in Combination with (-)-Epigallocatechin Gallate or Polyphenon E on Cisplatin-Induced Lung Tumorigenesis in A/J Mice.

We investigated the effects of celecoxib combined with (-)-epigallocatechin-3-gallate (EGCG) or polyphenon E in a cisplatin-induced lung tumorigenesis model. Four-week-old female A/J mice were divided into seven groups: (i) Control, (ii) 150 mg/kg celecoxib (150Cel), (iii) 1,500 mg/kg celecoxib (1500Cel), (iv) EGCG+150 mg/kg celecoxib (EGCG+150Cel), (v) EGCG+1,500 mg/kg celecoxib (EGCG+1500Cel), (vi) polyphenon E+150 mg/kg celecoxib (PolyE+150Cel), and (vii) polyphenon E+1,500 mg/kg celecoxib (PolyE+1500Cel). All mice were administered cisplatin (1.62 mg/kg of body weight, i.p.) 1×/week for 10 weeks and sacrificed at week 30; the numbers of tumors on the lung surface were then determined. The tumor incidence and multiplicity (no. of tumors/mouse, mean±SD) were respectively 95% and 2.15±1.50 in Control, 95% and 2.10±1.29 in 150Cel, 86% and 1.67±1.20 in 1500Cel, 71% and 1.38±1.24 in EGCG+150Cel, 67% and 1.29±1.38 in EGCG+1500Cel, 80% and 1.95±1.36 in PolyE+150Cel, and 65% and 1.05±0.10 in PolyE+1500Cel. The combination of high-dose celecoxib with EGCG or polyphenon E significantly reduced multiplicity in cisplatin-induced lung tumors.

[Three Cases of Appendiceal Goblet Cell Adenocarcinoma in Our Institution].

Appendiceal goblet cell adenocarcinoma(AGCA)is a newly designated pathological term adopted in the 5th edition of the WHO classification. It is synonymous with goblet cell carcinoid, which was previously categorized as a part of appendiceal carcinoid. However, since 2018, it has been classified as a subtype of adenocarcinoma. We have experienced 3 cases of this relatively rare tumor, of which 2 were initially diagnosed with acute appendicitis and were diagnosed with AGCA by pathological examination after an emergency appendectomy. Each of them underwent additional ileocolic resection with lymph node dissection as the second surgery. In the 3rd case, an appendiceal tumor was detected during preoperative examinations for an ovarian tumor. Staging laparoscopy revealed comorbid peritoneal dissemination, and only the appendix and right ovary were removed in the consecutive surgery. The ovarian tumor was pathologically diagnosed as a metastasis of AGCA. In this case, the introduction of oxaliplatin-based systemic chemotherapy after surgery achieved a complete response after more than 2 years. Although no recurrence has been observed in all 3 cases to date, AGCA is considered highly malignant compared to conventional appendiceal carcinoids. Therefore, it is crucial to practice multidisciplinary treatments, including sufficient radical surgery based on a precise diagnosis of AGCA, as is performed for advanced colorectal cancer.

Targeting ROR1 in combination with osimertinib in EGFR mutant lung cancer cells.

Lung cancer that exhibits epidermal growth factor receptor (EGFR) gene mutation is sensitive to EGFR-tyrosine kinase inhibitors (TKIs), such as osimertinib. Receptor tyrosine kinase-like orphan receptor 1 (ROR1) may be involved in overcoming EGFR-TKI resistance. Growth inhibition, colony formation, apoptosis, and mRNA/protein levels in four osimertinib-sensitive and resistant cell lines transfected with small interfering RNA (siRNA) targeting ROR1 (siROR1) were evaluated. Cell growth and colony formation were suppressed and apoptosis was increased in all cell lines treated with siROR1. Although EGFR, AKT, and ERK phosphorylation were not suppressed in all cell lines, TGF-ß2, AXL, CDH2, PARP1, PEG10, and TYMS mRNA expression levels were reduced. The combination of osimertinib with siROR1 was effective for the four cell lines, particularly in the two osimertinib-sensitive lines. In conclusion, targeting ROR1 in combination with osimertinib in EGFR mutant lung cancer may be a novel therapeutic option.

Survival of chemo-naïve patients with EGFR mutation-positive advanced non-small cell lung cancer after treatment with afatinib and bevacizumab: updates from the Okayama Lung Cancer Study Group Trial 1404.

BACKGROUND: In a phase I study, afatinib (30 mg/body daily) plus bevacizumab (15 mg/kg every 3 weeks) was well tolerated and showed favourable outcomes in patients with epidermal growth factor receptor (EGFR)-mutant advanced non-small-cell lung cancer. Herein, we report the 2-year progression-free survival, overall survival and safety profile of these patients. METHODS: Chemo-naïve patients with EGFR-mutant advanced non-small-cell lung cancer were enrolled. One group of patients received 40 mg afatinib daily and 15 mg/kg bevacizumab every 3 weeks (level 0) until disease progression or severe toxicity. Another group of patients received 30 mg afatinib daily and the same dose of bevacizumab (level 1). Dose-limiting toxicity was the primary endpoint, whereas long-term progression-free survival, overall survival and tolerability were secondary endpoints. Survival rates were estimated using the Kaplan-Meier method. RESULTS: The study included 19 patients (level 0: 5; level - 1: 14). Until the data cut-off date, seven patients continued the treatment, whereas 12 discontinued due to disease progression (n = 5) or toxicity (n = 7). The median PFS was 24.2 months, while the median overall survival was not reached. All patients developed adverse effects. Diarrhoea and skin rash were frequently observed as severe adverse events (grade 3). A secondary EGFR mutation (T790M) was detected in two patients after progression. CONCLUSIONS: Prolonged follow-up revealed that combination therapy with afatinib and bevacizumab might improve survival outcomes in EGFR-mutant advanced non-small-cell lung cancer patients and seems to be promising. TRIAL REGISTRATION: UMIN000015944.

A randomized trial of sodium alginate prevention of esophagitis in LA-NSCLC receiving chemoradiotherapy: OLCSG1401.

BACKGROUND: Radiation esophagitis is a critical adverse event that needs to be appropriately managed while administering thoracic irradiation. This trial aimed to investigate whether sodium alginate has preventative effects on esophagitis in patients with non-small-cell lung cancer (NSCLC) receiving concurrent chemoradiotherapy (CRT). METHODS: Patients with untreated stage III NSCLC who were eligible for concurrent CRT were randomly assigned at a 1:1:1 ratio to receive one of the following treatments: initial or late use of oral sodium alginate (arms A and B) or water as control (arm C). The primary endpoint was the proportion of patients developing G3 or worse esophagitis. RESULTS: Overall, 94 patients were randomly assigned between February 2014 and September 2018. The study was prematurely terminated because of slow accrual. The proportions of patients with G3 or worse esophagitis were 12.5%, 9.8%, and 19.4% in arms A, B, and C, respectively. Patients receiving sodium alginate had fewer onsets of G3 esophagitis; however, differences compared with arm C were not significant (A vs. C: p = 0.46; B vs. C: p = 0.28). The rates of grade 3 or worse non-hematologic toxicities besides esophagitis were 29%, 26%, and 43% in arms A, B, and C, respectively. Interestingly, compared with arm C, a low rate of febrile neutropenia was observed in arm A (3.1% vs. 19.4%: p = 0.04). CONCLUSIONS: Sodium alginate did not show significant preventative effects on radiation-induced esophagitis in patients with NSCLC. The frequency of CRT-induced febrile neutropenia was lower in the early use sodium alginate arm. TRIAL REGISTRATION: ClinicalTrials.gov Identifier Registry number: UMIN000013133.

De Novo Carborane-Containing Macrocyclic Peptides Targeting Human Epidermal Growth Factor Receptor.

l-Carboranylalanine (LCba) is a unique artificial amino acid containing a cluster of 10 boron atoms. Since the three-dimensional aromaticity and charge distributions of the carborane side chain are quite different from any side chains of proteinogenic amino acids, there is no report whether LCba can be a substrate for the translation machinery. Here, we report studies on the ribosomal incorporation of LCba into peptide via initiation and elongation using the flexizyme-assisted translation system. Our results indicate that only the initiation step could tolerate LCba incorporation, but the elongation steps could not, very likely due to its steric bulkiness of the side chain. Based on this knowledge, we have designed a library of macrocyclic peptides initiated by α-N-(2-choloroacetyl)-l-carboranylalanine (ClAc-LCba) and selected molecules capable of binding to human epidermal growth factor receptor (hEGFR). Two peptides that were forwarded to deeper studies exhibited affinities with KD values at 16 and 20 nM against hEGFR. Computational modeling of one of the peptides suggested that the carborane side chain might be directly involved in the interaction with the hydrophobic ß-sheet core in the EGF binding site of hEGFR, which is consistent with the mutational data where replacing LCba residue with LPhe completely eliminated the binding activity. Cell lines that stably express hEGFR could be stained by incubation with the C-terminal fluorescein-labeled peptides, whereas hEGFR-negative cells could not be stained. This study provides a general strategy for the de novo discovery of carborane-containing macrocyclic peptides targeting various tumor biomarker proteins, potentially applicable to boron neutron capture therapy.

Chemoradiotherapy for locally advanced lung cancer patients with interstitial lung abnormalities.

INTRODUCTION: Although chemoradiotherapy for locally advanced lung cancer has the potential for cure, treatment is avoided in patients with interstitial lung disease because of the risk for severe radiation pneumonitis. Interstitial lung abnormalities (ILA) can be evaluated using high-resolution computed tomography (HRCT) to assess interstitial changes. In this study, we retrospectively examined the feasibility and efficacy of chemoradiotherapy for locally advanced lung cancer patients with ILA. METHODS: Patients who underwent chemoradiotherapy for locally advanced lung cancer at Okayama University Hospital between 2012 and 2015 were reviewed retrospectively. HRCT prior to treatment was evaluated by one pulmonologist and two radiologists using a sequential reading method. RESULTS: Of the 77 patients enrolled in this study, ILA was present in 25 (32.5%) and indeterminate ILA in 24 patients; 28 patients did not have ILA. Desaturation at rest (SpO2 < 95%) and honeycombing on HRCT were not observed in ILA patients. Only one patient with ILA had a low vital capacity (%VC < 80%). Severe radiation pneumonitis (≥Grade 2) occurred in 36.0% of the patients with ILA, but it was controllable; Grade 4 or 5 was not observed. Multivariate analysis showed that >25% of the lung volume receiving >20 Gy was risk factors of severe radiation pneumonitis, but ILA was not. The 2-year survival rates of patients with and without ILA were 56.8% and 74.1%, respectively, but the difference was not significant (P = 0.33). CONCLUSIONS: Chemoradiotherapy was feasible and effective in some patient population with ILA without desaturation, low VC and honeycombing on HRCT.

Publication of lung cancer clinical trials in the Japanese Clinical Trial Registry.

INTRODUCTION: Since June 2005, the University Hospital Medical Information Network-Clinical Trial Registry (UMIN-CTR) has been an International Committee of Medical Journal Editors (ICMJE)-approved clinical trial registry in Japan. The number of clinical trials registered in the UMIN-CTR has increased annually. To date, no report exists regarding the publishing of clinical trials registered in the UMIN-CTR. Therefore, we evaluated the publication frequency of clinical trials registered in the UMIN-CTR in Japan. METHODS: We targeted trials that assessed the treatment effect of chemotherapy or molecular targeting drugs for lung cancer. We included trials registered between June 2005 and January 2010, and identified published trials through a computer-based search of MEDLINE and Google Scholar. The cumulative publication rate of the trials was calculated using Kaplan-Meier analysis. RESULTS: In our study, 179 trials met the inclusion criteria. Of these, 46.4% (83/179) trials were published by the end of the cut-off period. With regard to publication, differences existed between the information recorded in the UMIN-CTR database and the actual searched results. The publication rate between groups was insignificantly different; however, whether a clinical study group did or did not conduct a trial differed significantly (53.3% vs. 36.1%; P = 0.024). Phase II studies with positive results were more likely to be published (84.4%); however, the overall publication rate was low (41.8%), which may reflect publication bias. CONCLUSIONS: The UMIN-CTR fundamentally functions as the unique ICMJE-approved clinical trial registry in Japan. However, it seems insufficient to require it as the official clinical database.

Second primary cancer in survivors of locally advanced non-small cell lung cancer treated with concurrent chemoradiation followed by surgery.

The standard treatment for patients with locally advanced non-small-cell lung cancer (LA-NSCLC) is chemoradiotherapy (CRT), but surgical resection following induction CRT can extend overall survival in a select population. However, patients who survive longer are at risk of developing a second primary cancer (SPC). This is the first report to determine the incidence of SPC in survivors with LA-NSCLC after trimodal therapy. Between October 1997 and October 2013, 112 Stage III NSCLC patients underwent trimodal therapy in our hospital. The 5-year overall survival rate was 71.8%. SPC developed in 10 of the 112 patients 0.60-15.0 (median 5.49) years after initiating CRT. The observed incidence of SPC was 1.8 per 100 patient-years. Although trimodal therapy can prolong patient survival, the estimated incidence of SPC does not increase. A large prospective study with a longer follow-up time is required to determine the effects of trimodal therapy, including the development of SPC.

Discomfort during bronchoscopy performed after endobronchial intubation with fentanyl and midazolam: a prospective study.

OBJECTIVE: Although endobronchial intubation during a bronchoscopic examination is useful for invasive procedures, it is not routine practice in Japan. The present study evaluated discomfort due to endobronchial intubation using fentanyl and midazolam sedation during bronchoscopy. METHODS: Thirty-nine patients were enrolled prospectively from November 2014 to September 2015 at Okayama University Hospital. Fentanyl (20 µg) was administered to the patients just before endobronchial intubation, and fentanyl (10 µg) and midazolam (1 mg) were added as needed during the procedure. A questionnaire survey was administered 2 h after the examination. In the questionnaire, patient satisfaction was scored using a visual analog scale as follows: excellent (1 point), good (2 points), normal (3 points), uncomfortable (4 points) and very uncomfortable (5 points). An additional question ('Do you remember the bronchoscopic examination?') was also asked. Predefined parameters (blood pressure, heart rate, oxygen saturation and complications) were recorded. RESULTS: The enrolled patients included 22 males and 17 females; their median age was 70 (range: 28-88) years. The patients received a mean dose of 47.9 µg of fentanyl (range: 30-90 µg) and 2.79 mg of midazolam (range: 1-7 mg). In total, 28 patients (71.7%) agreed to undergo a second bronchoscopic examination; the mean levels of discomfort and for the re-examination were 2.07 points each. About 41% of the patients remembered the bronchoscopic examination. No severe complications were reported. CONCLUSION: Endobronchial intubation using fentanyl and midazolam sedation during an invasive bronchoscopic procedure might be recommended. CLINICAL TRIAL REGISTRATION: UMIN000015578 in the UMIN Clinical Trials Registry.

Synergistic effect of pacritinib with erlotinib on JAK2-mediated resistance in epidermal gowth factor receptor mutation-positive non-small cell lung Cancer.

The combination effect of pacritinib, a novel JAK2/FLT3 inhibitor, with erlotinib, the epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), on non-small cell lung cancer cells with EGFR activating mutations was investigated. The combination showed synergistic effects on JAK2-mediated EGFR TKI-resistant PC-9/ER3 cells in some cases. The combination markedly suppressed pAKT and pERK although pSTAT3 expression was similar regardless of treatment with the pacritinib, pacritinib + erlotinib, or control in PC-9/ER3 cells. Receptor tyrosine kinase array profiling demonstrated that pacritinib suppressed MET in the PC-9/ER3 cells. The combined treatment of pacritinib and erlotinib in PC-9/ER3 xenografts showed more tumor shrinkage compared with each drug as monotherapy. Western blotting revealed that pMET in tumor samples was inhibited. These results suggest MET suppression by pacritinib may play a role in overcoming the EGFR-TKI resistance mediated by JAK2 in the PC-9/ER3 cells. In conclusion, pacritinib combined with EGFR-TKI might be a potent strategy against JAK2-mediated EGFR-TKI resistance.

Endobronchial ultrasound-guided transbronchial needle aspiration of hilar and mediastinal lymph nodes detected on 18F-fluorodeoxyglucose positron emission tomography/computed tomography.

OBJECTIVE: Endobronchial ultrasound-guided transbronchial needle aspiration is of diagnostic value in hilar/mediastinal (N1/N2) lymph node staging. We assessed the utility of endobronchial ultrasound-guided transbronchial needle aspiration in lung cancer patients with N1/N2 lymph nodes detected on (18)F-fluorodeoxyglucose positron emission tomography/computed tomography. METHODS: Fifty lung cancer patients with N1/N2 disease on (18)F-fluorodeoxyglucose positron emission tomography/computed tomography underwent endobronchial ultrasound-guided transbronchial needle aspiration for pathological lymph nodes between November 2012 and April 2015. The diagnostic performance of endobronchial ultrasound-guided transbronchial needle aspiration, lymph node site and size, number of needle passes and complications were evaluated retrospectively from patients' medical records. Malignancy was defined as a maximum standardized uptake value (SUVmax) >2.5. RESULTS: The median longest diameter of the 61 lymph nodes (29 subcarinal, 21 right lower paratracheal, 6 left lower paratracheal, 4 right hilar and 1 upper paratracheal) was 23.4 mm (range: 10.4-45.7); the median number of needle passes was 2 (range: 1-5). There were no severe complications. A definitive diagnosis was made by endobronchial ultrasound-guided transbronchial needle aspiration in 39 patients (31 adenocarcinomas, 3 small-cell carcinomas, 2 squamous-cell carcinomas, 3 large-cell neuroendocrine carcinomas). In the remaining 11 patients, the diagnosis was indefinite: insufficient endobronchial ultrasound-guided transbronchial needle aspiration material was collected in two patients and non-specific lymphadenopathy was confirmed by endobronchial ultrasound-guided transbronchial needle aspiration or thoracotomy in the other nine patients. The mean lymph node SUVmax was 7.09 (range: 2.90-26.9) and was significantly higher in true-positive than in false-positive nodes (P < 0.05, t-test). Non-specific lymphadenopathy was diagnosed by expert visual interpretation of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography images in five of the nine patients. CONCLUSION: Endobronchial ultrasound-guided transbronchial needle aspiration accurately diagnoses N1/N2 disease detected on (18)F-fluorodeoxyglucose positron emission tomography/computed tomography.

Safety and discomfort during bronchoscopy performed under sedation with fentanyl and midazolam: a prospective study.

OBJECTIVE: Although sedation with fentanyl and midazolam during bronchoscopic examination is widely accepted in the USA and Europe, it is not routine practice in Japan. The objective of the present study was to evaluate sedation with fentanyl and midazolam during bronchoscopy. METHODS: Thirty-seven patients were enrolled prospectively between November 2014 and July 2015 at Okayama University Hospital. Fentanyl (20 µg) was administered to the patients just before the examination, and fentanyl (10 µg) and midazolam (1 mg) were added as needed during the procedure. A questionnaire was administered 2 hours after the examination. In the questionnaire, patient satisfaction was scored using a visual analog scale as follows: great (1 point), good (2 points), normal (3 points), uncomfortable (4 points) and very uncomfortable (5 points). An additional question ('Do you remember the bronchoscopic examination?') was also used. Predefined matters for investigation (e.g. blood pressure, heart rate, oxygen saturation and complications) were recorded. RESULTS: The enrolled patients included 13 males and 24 females; the median age was 67 (range: 31-87) years. The patients received a median dose of fentanyl of 45.4 µg (range: 30-100 µg) and midazolam of 2.56 mg (range: 1-10 mg). Twenty-six patients (70.2%) agreed to undergo a second bronchoscopic examination, and the average levels of discomfort and re-examination were 2.02 points for each. Only 37.8% of the patients remembered the bronchoscopic examination. No severe complications were reported. CONCLUSIONS: Sedation with fentanyl and midazolam during bronchoscopic examination should be recommended for use in Japan.

A novel PI3K inhibitor iMDK suppresses non-small cell lung Cancer cooperatively with A MEK inhibitor.

The PI3K-AKT pathway is expected to be a therapeutic target for non-small cell lung cancer (NSCLC) treatment. We previously reported that a novel PI3K inhibitor iMDK suppressed NSCLC cells in vitro and in vivo without harming normal cells and mice. Unexpectedly, iMDK activated the MAPK pathway, including ERK, in the NSCLC cells. Since iMDK did not eradicate such NSCLC cells completely, it is possible that the activated MAPK pathway confers resistance to the NSCLC cells against cell death induced by iMDK. In the present study, we assessed whether suppressing of iMDK-mediated activation of the MAPK pathway would enhance anti-tumorigenic activity of iMDK. PD0325901, a MAPK inhibitor, suppressed the MAPK pathway induced by iMDK and cooperatively inhibited cell viability and colony formation of NSCLC cells by inducing apoptosis in vitro. HUVEC tube formation, representing angiogenic processes in vitro, was also cooperatively inhibited by the combinatorial treatment of iMDK and PD0325901. The combinatorial treatment of iMDK with PD0325901 cooperatively suppressed tumor growth and tumor-associated angiogenesis in a lung cancer xenograft model in vivo. Here, we demonstrate a novel treatment strategy using iMDK and PD0325901 to eradicate NSCLC.

Effect of Vandetanib on Lung Tumorigenesis in Transgenic Mice Carrying an Activating Egfr Gene Mutation.

Vandetanib (ZactimaTM) is a novel, orally available inhibitor of both vascular endothelial growth factor receptor-2 (VEGFR-2) and epidermal growth factor receptor (EGFR) tyrosine kinase. In the present study, a line of transgenic mice with a mouse Egfr gene mutation (delE748-A752) corresponding to a human EGFR mutation (delE746-A750) was established. The transgenic mice developed atypical adenomatous hyperplasia to adenocarcinoma of the lung at around 5 weeks of age and died of lung tumors at approximately 17 weeks of age. In the mice treated with vandetanib (6mg/kg/day), these lung tumors disappeared and the phosphorylations of EGFR and VEGFR-2 were reduced in lung tissues to levels comparable to those of non-transgenic control mice. The median overall survival time of the transgenic mice was 28 weeks in the vandetanib-treated group and 17 weeks in the vehicle-treated group. Vandetanib significantly prolonged the survival of the transgenic mice (log-rank test, p＜ 0.01); resistance to vandetanib occurred at 20 weeks of age and the animals died from their lung tumors at about 28 weeks of age. These data suggest that vandetanib could suppress the progression of tumors harboring an activating EGFR mutation.

Downregulation of TBXAS1 in an iron-induced malignant mesothelioma model.

Malignant mesothelioma is an aggressive and therapy-resistant neoplasm arising from mesothelial cells. Evidence suggests that the major pathology associated with asbestos-induced mesothelioma is local iron overload. In the present study, we induced iron-induced mesothelioma in rats based on previous reports. Ten Wistar rats were given ferric saccharate and nitrilotriacetate i.p. for 5 days a week. Five of the ten rats exhibited widespread mesotheliomas in the peritoneum and tunica vaginalis. The tumor cells showed positive immunostaining for calretinin, wilms tumor-1, podoplanin and the oxidative DNA marker 8-hydroxy-2'-deoxyguanosine. In three of the five rats with mesothelioma, array-based comparative genomic hybridization analysis identified a common chromosomal deletion mapped to the chromosomal 4q31 locus, which encompasses the TBXAS1 gene. Downregulation of the TBXAS1 gene was confirmed using quantitative PCR. TBXAS1 gene expression was also reduced in three of four human malignant pleural mesothelioma cell lines compared with normal bronchial epithelial cells. Immunohistochemistry revealed that TBXAS1 expression was weakly positive and positive in five and three out of eight human malignant mesothelioma samples, respectively. In conclusion, TBXAS1 gene expression was downregulated in rats with iron-induced mesothelioma. The relationship between iron overload and TBXAS1 downregulation should be pursued further.

Src mediates ERK reactivation in gefitinib resistance in non-small cell lung cancer.

To study epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) resistance mechanisms, we established a novel gefitinib-resistant lung cancer cell line derived from an EGFR-mutant non-small cell lung cancer cell line (PC-9) pretreated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (designated PC9-GR). We found that gefitinib substantially suppressed the EGFR signaling pathway, whereas ERK was reactivated after several hours in PC9-GR but not in PC-9. The combination of gefitinib with ERK inhibition (by U0126) restored gefitinib susceptibility in PC9-GR, but PI3K-Akt inhibition with LY294002 did not. Although the levels of phosphorylated Src were up-regulated simultaneously with ERK reactivation, neither ERK suppression using U0126 nor an ERK-specific siRNA induced Src phosphorylation. Furthermore, dual inhibition of EGFR and Src restored gefitinib sensitivity in PC9-GR in vitro and in vivo. In conclusion, our results indicate that Src-mediated ERK reactivation may play a role in a novel gefitinib resistance mechanism, and that the combined use of gefitinib with a Src inhibitor may be a potent strategy to overcome this resistance.

Everolimus prolonged survival in transgenic mice with EGFR-driven lung tumors.

Everolimus is an orally administered mTOR inhibitor. The effect, and mechanism of action, of everolimus on lung cancers with an epidermal growth factor receptor (EGFR) mutation remain unclear. Four gefitinib-sensitive and -resistant cell lines were used in the present work. Growth inhibition was determined using the MTT assay. Transgenic mice carrying the EGFR L858R mutation were treated with everolimus (10 mg/kg/day), or vehicle alone, from 5 to 20 weeks of age, and were then sacrificed. To evaluate the efficacy of everolimus in prolonging survival, everolimus (10 mg/kg/day) or vehicle was administered from 5 weeks of age. The four cell lines were similarly sensitive to everolimus. Expression of phosphorylated (p) mTOR and pS6 were suppressed upon treatment with everolimus in vitro, whereas the pAKT level increased. The numbers of lung tumors with a long axis exceeding 1mm in the everolimus-treated and control groups were 1.9 ± 0.9 and 9.4 ± 3.2 (t-test, p<0.001), respectively. pS6 was suppressed during eve r olimus treatment. Although apoptosis and autophagy were not induced in everolimus-treated EGFR transgenic mice, angiogenesis was suppressed. The median survival time in the everolimus-treated group (58.0 weeks) was significantly longer than that in the control group (31.2 weeks) (logrank test, p<0.001). These findings suggest that everolimus had an indirect effect on tumor formation by inhibiting angiogenesis and might be effective to treat lung tumors induced by an activating EGFR gene mutation.