Satoshi Yoda

Molecular Mechanisms of Resistance to First- and Second-Generation ALK Inhibitors in ALK-Rearranged Lung Cancer

Advanced, anaplastic lymphoma kinase (ALK)-positive lung cancer is currently treated with the first-generation ALK inhibitor crizotinib followed by more potent, second-generation ALK inhibitors (e.g., ceritinib, alectinib) upon progression. Second-generation inhibitors are generally effective even in the absence of crizotinib-resistant ALK mutations, likely reflecting incomplete inhibition of ALK by crizotinib in many cases. Herein, we analyzed 103 repeat biopsies from ALK-positive patients progressing on various ALK inhibitors. We find that each ALK inhibitor is associated with a distinct spectrum of ALK resistance mutations and that the frequency of one mutation - ALK G1202R - increases significantly after treatment with second-generation agents. To investigate strategies to overcome resistance to second-generation ALK inhibitors, we examine the activity of the third-generation ALK inhibitor lorlatinib in a series of ceritinib-resistant, patient-derived cell lines, and observe that the presence of ALK resistance mutations is highly predictive for sensitivity to lorlatinib, whereas those cell lines without ALK mutations are resistant.

Deregulation of histone lysine methyltransferases contributes to oncogenic transformation of human bronchoepithelial cells

BackgroundAlterations in the processing of the genetic information in carcinogenesis result from stable genetic mutations or epigenetic modifications. It is becoming clear that nucleosomal histones are central to proper gene expression and that aberrant DNA methylation of genes and histone methylation plays important roles in tumor progression. To date, several histone lysine methyltransferases (HKMTs) have been identified and histone lysine methylation is now considered to be a critical regulator of transcription. However, still relatively little is known about the role of HKMTs in tumorigenesis.ResultsWe observed differential HKMT expression in a lung cancer model in which normal human bronchial epithelial (NHBE) cells expressing telomerase, SV40 large T antigen, and Ras were immortal, formed colonies in soft agar, and expressed specific HKMTs for H3 lysine 9 and 27 residues but not for H3 lysine 4 residue. Modifications in the H3 tails affect the binding of proteins to the histone tails and regulate protein function and the position of lysine methylation marks a gene to be either activated or repressed. In the present study, suppression by siRNA of HKMTs (EZH2, G9A, SETDB1 and SUV39H1) that are over-expressed in immortalized and transformed cells lead to reduced cell proliferation and much less anchorage-independent colony growth. We also found that the suppression of H3-K9, G9A and SUV39H1 induced apoptosis and the suppression of H3-K27, EZH2 caused G1 arrest.ConclusionOur results indicate the potential of these HKMTs in addition to the other targets for epigenetics such as DNMTs and HDACs to be interesting therapeutic targets.

Activation of the FGF2-FGFR1 Autocrine Pathway: A Novel Mechanism of Acquired Resistance to Gefitinib in NSCLC

Patients with non-small cell lung cancer (NSCLC) that harbors epidermal growth factor receptor (EGFR) mutations initially respond to EGFR-tyrosine kinase inhibitors (TKI) but eventually experience relapse. Acquired resistance to EGFR-TKIs is strongly associated with patient mortality. Thus, elucidation of the mechanism of acquired resistance to EGFR-TKIs is of great importance. In this study, gefitinib-resistant cell line models were established by long-term exposure to gefitinib using the gefitinib-sensitive lung cancer cell lines, PC9 and HCC827. Expression analyses indicated that both FGFR1 and FGF2 were increased in PC9 gefitinib-resistant (PC9 GR) cells as compared with PC9 naïve (PC9 na) cells. Importantly, proliferation of gefitinib-resistant cells was dependent on the FGF2 -FGFR1 pathway. Mechanistically, inhibition of either FGF2 or FGFR1 by siRNA or FGFR inhibitor (PD173074) restored gefitinib sensitivity in PC9 GR cells. These data suggest that FGF2 -FGFR1 activation through an autocrine loop is a novel mechanism of acquired resistance to EGFR-TKIs. Mol Cancer Res; 11(7); 759–67. ©2013 AACR.

The PCR-invader method (structure-specific 5' nuclease-based method), a sensitive method for detecting EGFR gene mutations in lung cancer specimens; comparison with direct sequencing.

BackgroundSeveral sensitive assays, including the PCR-invader method (structure-specific 5′ nuclease-based method), have been used to detect EGFR mutations in non-small-cell lung cancer (NSCLC). However, validation has not been reported. We assessed the detection rate of EGFR mutation by the PCR-invader method and direct sequencing using same clinical specimens.Patients and methodsEGFR mutations were analyzed with the PCR-invader method and compared with direct sequencing using paraffin tissues and pleural and pericardial effusions from NSCLC patients. The relationships between the treatment responses and mutations were evaluated retrospectively.ResultsFifty-four samples from 42 NSCLC patients were studied. EGFR mutations were identified in 52% of the patients and 52% of the samples with the PCR-invader method, but only in 43% of the patients and in 35% of the samples by direct sequencing. In the samples obtained from the same patients at different sites and different times, EGFR mutations were coincident in nine out of ten patients by the PCR-invader method but in six out of ten patients by direct sequencing. Seventeen patients with EGFR mutations were treated with gefitinib; the response rate (RR) and disease control rate (DCR) were 41 and 94%, and median treatment duration was more than 6xa0months. Seven EGFR mutation-negative patients were treated with gefitinib; the RR and DCR were 0 and 14%, and median treatment duration was 1xa0month.ConclusionThe PCR-invader method was useful for detecting EGFR mutations in clinical lung cancer specimens and is more sensitive than direct sequencing.

Identification of microRNAs differentially expressed between lung squamous cell carcinoma and lung adenocarcinoma

Recent advances in the treatment of non-small cell lung cancer (NSCLC) with new agents require accurate histological subtyping at diagnosis to avoid the higher risk of an adverse response and to obtain the maximum therapeutic response. However, interobserver variability, tumor heterogeneity and the degree of differentiation may affect the decision concerning a pathological diagnosis of NSCLC. Therefore, the aim of this study was to identify specific microRNAs (miRNAs) as standardized biomarkers with high sensitivity and specificity in order to distinguish between squamous cell carcinoma (SCC) and adenocarcinoma (AC). Quantitative polymerase chain reaction (qPCR)‑based miRNA array analysis was performed to identify microRNAs differentially expressed between SCC and AC using 86 resected NSCLC samples in addition to adjacent normal tissues. The results were confirmed by independent qRT-PCR assays with the same test samples and 88 additional validation samples, and from this we evaluated the usefulness of the identified miRNAs as biomarkers to distinguish between SCC and AC. Three miRNAs (hsa-miR-196b, hsa-miR-205 and hsa-miR-375) were identified. Discriminant analysis combining the three miRNAs appeared to distinguish SCC from AC accurately in the test and validation samples, demonstrating a sensitivity and specificity of 76 and 80%, and 85 and 83%, respectively. hsa-miR-196b, hsa-miR-205 and hsa-miR-375 were identified as biomarkers capable of distinguishing between lung SCC and lung AC. These newly identified miRNAs may prove to be highly valuable molecular markers for the classification of NSCLC histological subtypes and may contribute to the pathogenesis of each subtype of NSCLC.

The Combination of Multiple Receptor Tyrosine Kinase Inhibitor and Mammalian Target of Rapamycin Inhibitor Overcomes Erlotinib Resistance in Lung Cancer Cell Lines through c-Met Inhibition

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) show antitumor activity in a subset of non–small cell lung cancer (NSCLC) patients. However, the initial tumor response is followed by recurrence. Several studies have suggested the importance of other receptor tyrosine kinases (RTK) and downstream kinases as potential targets in the treatment of NSCLC. We used the multiple-RTK inhibitor AEE788, which inhibits EGFR, vascular endothelial growth factor receptor, and human epidermal growth factor receptor 2, with and without the downstream kinase inhibitor RAD001 (an inhibitor of mammalian target of rapamycin). AEE788 inhibited cell growth more effectively than did erlotinib in three NSCLC cell lines examined (A549, H1650, and H1975). However, in the EGFR-TKI–resistant cell line H1975 harboring T790M resistance mutation, cell growth inhibition by AEE788 was only mild, and the phosphorylation of its leading targets such as EGFR and vascular endothelial growth factor receptor 2 was not inhibited. In H1975, AEE788 induced significantly greater cell growth inhibition when combined with RAD001 than when used alone. This cooperative effect was not seen with the combination of erlotinib and RAD001. We found that c-Met was highly phosphorylated in this cell line, and the phosphorylated c-Met was inhibited effectively by AEE788. Using a phospho-RTK array, the phosphorylation of c-Met and insulin-like growth factor-I receptor was inhibited by AEE788. These results suggest that upstream RTK inhibitor overcomes the acquired resistance to EGFR-TKI when combined with downstream kinase inhibitor. Thus, the combined inhibition of upstream and downstream RTKs is a promising strategy for the treatment of NSCLC. Mol Cancer Res; 8(8); 1142–51. ©2010 AACR.

Expression of fibroblast growth factor 9 is associated with poor prognosis in patients with resected non-small cell lung cancer

OBJECTIVESnFibroblast growth factor (FGF) 9 is a member of the FGF family, which modulates cell proliferation, differentiation, and motility. Recent studies show that the activation of FGF signals including FGF9 is associated with the pathogenesis of several cancers; however, its clinicopathological and biological significance in non-small cell lung cancer (NSCLC) is unclear. The purpose of this study was to clarify the characteristics of NSCLC with FGF9 expression.nnnMATERIALS AND METHODSnWe evaluated the expression of FGF9 in resected NSCLC specimens and corresponding non-tumorous lung tissue samples using cDNA microarray and evaluated its clinicopathological characteristics.nnnRESULTSnNine out of 90 NSCLC specimens (10%) had high FGF9 expression compared with corresponding non-cancerous lung tissues. Histologically, of the 9 NSCLC specimens with high FGF9 expression, 5 were adenocarcinoma, whereas none were squamous cell carcinoma. FGF9 expression was not associated with sex, smoking history, or clinical stage. However, in patients with high and low FGF9 expression, the postoperative recurrence rates were 78% and 24% (p=0.033), respectively. Overall survival was significantly shorter in patients with high FGF9 expression than in those with low FGF9 expression (p<0.001).nnnCONCLUSIONnOur data indicate that FGF9 may be a novel unfavorable prognostic indicator and a candidate therapeutic target of NSCLC.

Impact of EML4-ALK Variant on Resistance Mechanisms and Clinical Outcomes in ALK-Positive Lung Cancer

Purpose Advanced anaplastic lymphoma kinase ( ALK) fusion-positive non-small-cell lung cancers (NSCLCs) are effectively treated with ALK tyrosine kinase inhibitors (TKIs). However, clinical outcomes in these patients vary, and the benefit of TKIs is limited as a result of acquired resistance. Emerging data suggest that the ALK fusion variant may affect clinical outcome, but the molecular basis for this association is unknown. Patients and Methods We identified 129 patients with ALK-positive NSCLC with known ALK variants. ALK resistance mutations and clinical outcomes on ALK TKIs were retrospectively evaluated according to ALK variant. A Foundation Medicine data set of 577 patients with ALK-positive NSCLC was also examined. Results The most frequent ALK variants were EML4-ALK variant 1 in 55 patients (43%) and variant 3 in 51 patients (40%). We analyzed 77 tumor biopsy specimens from patients with variants 1 and 3 who had progressed on an ALK TKI. ALK resistance mutations were significantly more common in variant 3 than in variant 1 (57% v 30%; P = .023). In particular, ALK G1202R was more common in variant 3 than in variant 1 (32% v 0%; P < .001). Analysis of the Foundation Medicine database revealed similar associations of variant 3 with ALK resistance mutation and with G1202R ( P = .010 and .015, respectively). Among patients treated with the third-generation ALK TKI lorlatinib, variant 3 was associated with a significantly longer progression-free survival than variant 1 (hazard ratio, 0.31; 95% CI, 0.12 to 0.79; P = .011). Conclusion Specific ALK variants may be associated with the development of ALK resistance mutations, particularly G1202R, and provide a molecular link between variant and clinical outcome. ALK variant thus represents a potentially important factor in the selection of next-generation ALK inhibitors.

Claudin-1 is a novel target of miR-375 in non-small-cell lung cancer

OBJECTIVESnWe previously reported low expression of miR-375 in squamous-cell carcinoma (SCC) and high expression in adenocarcinoma (AC) of the lung. miR-375s target genes and its function in non-small-cell lung cancer (NSCLC) have not been elucidated. Therefore, the present study was designed to identify the targets of miR-375 and to characterize its function in NSCLC.nnnMATERIALS AND METHODSnCandidate targets of miR-375 were determined using a prediction database and previous data on differential gene expression between SCC and AC. We evaluated miR-375 and target-gene expression levels in 12 NSCLC cell lines. The effect of miR-375 overexpression and knockdown was evaluated in NSCLC cell lines by transfecting them with an miR-375 precursor or inhibitor. A luciferase-reporter assay was performed to confirm a direct interaction between miR-375 and its target gene. Further, a wound-healing assay was performed to evaluate the effect of miR-375 overexpression on the migration of SK-MES-1 cells. Finally, to assess the clinical relevance, 63 clinical NSCLC samples were analyzed.nnnRESULTSnClaudin-1 (CLDN1) has 4 putative miR-375 target sites in its 3-untranslated region, and this gene was determined to be a target of miR-375. CLDN1 messenger RNA and protein expression were attenuated by overexpression of miR-375 and increased by knockdown of miR-375 in NSCLC cell lines. In a luciferase-reporter assay, miR-375 overexpression resulted in a 3-fold repression of luciferase activity (P<0.001). Cell migration was promoted by miR-375 overexpression, suggesting a high potential for invasion and metastasis in NSCLC expressing high levels of miR-375. In clinical NSCLC samples, there was a negative correlation between miR-375 and CLDN1 expression (r=-0.35, P=0.005). In addition, high miR-375 expression was correlated with a shorter survival time among the clinical samples (P=0.043).nnnCONCLUSIONnCLDN1 is a novel target of miR-375, and high miR-375 expression shortens survival in NSCLC.

Bronchoscopic Microsampling is a Useful Complementary Diagnostic Tool for Detecting Lung Cancer

PURPOSEnBronchoscopic microsampling (BMS) is a novel and direct method with which to obtain epithelial lining fluid (ELF) from the lungs. Analysis of DNA hypermethylation of tumor suppressor genes (TSGs) is expected to be a sensitive tool for the early detection of lung cancer. It has been reported that the existence of EGFR mutations and EML4-ALK gene rearrangements are related to the sensitivity of corresponding kinase inhibitors. We aimed to evaluate the suitability of ELF as a sample for analyzing molecular changes specific for lung cancer.nnnPATIENTS AND METHODSnWe collected ELF from 61 lung cancer patients by BMS from the airway close to the peripheral lung nodule and purified the nucleic acids. We performed methylation specific PCR in each ELF as well as matched serum and tumor tissue for TSGs for DNA methylation analysis. We also examined EGFR mutations and EML4-ALK rearrangement.nnnRESULTSnThe sensitivity for detecting DNA hypermethylation in ELF vs serum was 74.1% vs 18.5%. We found 60.1% of patients had at least one hypermethylation in ELF, while only 27.9% had it in serum. Of note, DNA hypermethylation was detected even in stage I patients (60.0%) and the detection rate was almost the same level in each stage. We also found the sensitivity for detecting EGFR mutation in ELF vs serum was 58.3% vs 8.3%. We detected an EML4-ALK fusion gene using ELF in one patient.nnnCONCLUSIONSnBMS is an alternative method to detect cancer specific genetic and epigenetic alterations and will be a useful complementary diagnostic tool for lung cancer.nnnSUMMARYnInvestigation of genetic and epigenetic changes associated with lung cancer has clinical importance for its diagnosis and management. The clinical usefulness of bronchoscopic microsampling (BMS) in lung cancer has not yet been evaluated. This study demonstrates that BMS could be useful for detecting lung cancer specific molecular changes and valuable for early diagnosis and determination of treatment options for lung cancer.