Takehiro Uemura

Significance of thymidylate synthase for resistance to pemetrexed in lung cancer

Pemetrexed (MTA) is a multitargeted antifolate with promising clinical activity in lung cancer. We exposed the small cell lung cancer cell line PC6 to stepwise‐increasing pemetrexed concentrations of 0.4, 1.6, and 4.0 μm, and established three pemetrexed‐resistant lung cancer cell lines: PC6/MTA‐0.4, PC6/MTA‐1.6, and PC6/MTA‐4.0 cells. To investigate the mechanisms of acquired resistance to pemetrexed, we measured the expression levels of the thymidylate synthase (TS), reduced folate carrier (RFC), and folylpoly‐gamma‐glutamate synthetase (FPGS) genes. TS gene expression was significantly increased in PC6/MTA‐1.6 and PC6/MTA‐4.0 cells relative to parental cells in a pemetrexed dose‐dependent manner. In contrast, the levels of RFC gene expression in PC6/MTA‐0.4 cells and FPGS in PC6/MTA‐1.6 cells were significantly decreased, whereas the levels of both genes were restored in PC6/MTA‐4.0 cells. Knockdown of TS expression using siRNA enhanced pemetrexed cytotoxicity in PC6/MTA‐4.0 cells. The expression level of the TS gene was significantly correlated with the concentration of pemetrexed for 50% cell survival (IC50) in 11 non‐small cell lung cancer cell lines. These results suggest that the alteration of molecular pharmacological factors in relation with pemetrexed resistance is dose‐dependent, and that up‐regulation of the expression of the TS gene may have an important role in the acquired resistance to pemetrexed. In addition, TS may be a predictive marker for pemetrexed sensitivity in lung cancer. (Cancer Sci 2009)

MRP7/ABCC10 expression is a predictive biomarker for the resistance to paclitaxel in non-small cell lung cancer.

We used the paclitaxel-resistant human small cell lung cancer subline PC-6/TAX1-1, selected from PC-6 cells by paclitaxel, to test whether MRP7/ABCC10 (ABCC10) confers paclitaxel resistance. We found that gene expression of both ABCB1/MDR1 (ABCB1) and ABCC10 was higher in PC-6/TAX1-1 cells than in PC-6 cells. The expression levels of ABCC10 showed a significant inverse correlation with paclitaxel sensitivity (r = 0.574; P < 0.05) in 17 non-small cell lung cancer (NSCLC) cells unlike the expression levels of ABCB1. Pretreatment with the ABCC10 inhibitor sulfinpyrazone altered the sensitivity to paclitaxel in ABCC10-expressing NSCLC cells, concomitant with increased intracellular paclitaxel accumulation. These findings suggest that expression of the ABCC10 gene is induced by paclitaxel and that ABCC10 confers paclitaxel resistance by enhancing the efflux for paclitaxel. To confirm this hypothesis, we tested the effect on paclitaxel cytotoxicity of decreasing the expression of ABCC10 by small interfering RNA and found that this enhanced paclitaxel cytotoxicity in NCI-H23 cells concomitant with increased intracellular paclitaxel accumulation. These data indicate that ABCC10 may be one of the biomarkers for paclitaxel resistance in NSCLC. [Mol Cancer Ther 2008;7(5):1150–5]

ABCC11/MRP8 confers pemetrexed resistance in lung cancer

We have previously shown that overexpression of thymidylate synthetase (TS) resulted in pemetrexed (MTA) resistance. To investigate another mechanism of MTA resistance, we investigated the expression of ATP‐binding cassette (ABC)‐transporters in MTA‐resistant lung cancer cell lines and found that the gene and protein expression of ABCC11/MRP8 (ABCC11) was higher in MTA‐resistant cells than in the parental cells. The MTA resistant cells showed cross‐resistance to methotrexate (MTX), which is a substrate for ABCC11, and intracellular MTX accumulation in MTA‐resistant cells was lower than in the parental cells. We then tested the effect of decreasing the expression of ABCC11 by siRNA and found that decreased expression of ABCC11 enhanced MTA cytotoxicity and increased intracellular MTX accumulation in MTA‐resistant cells. These findings suggested that ABCC11 directly confers resistance to MTA by enhancing efflux of the intracellular anti‐cancer drug. Next, we analyzed the relationship between ABCC11 gene expression and MTA sensitivity of 13 adenocarcinoma cells, but there was no correlation. The ABCC11 gene has been shown to have a functional single‐nucleotide polymorphism (SNP), 538G>A. We then classified 13 lung adenocarcinoma cell lines into three groups based on the genotype of this ABCC11 SNP: G/G, G/A and A/A. The A/A group showed a significant reduction in the IC50 of MTA compared with the combined G/G and G/A groups, indicating that the SNP (538G>A) in the ABCC11 gene is an important determinant of MTA sensitivity. These results showed that ABCC11 may be one of the biomarkers for MTA treatment in adenocarcinomas. (Cancer Sci 2010; 101: 2404–2410)

Significance of c-MET overexpression in cytotoxic anticancer drug-resistant small-cell lung cancer cells

The c‐MET receptor tyrosine kinase is the receptor for hepatocyte growth factor. Recently, activation of the c‐MET/hepatocyte growth factor signaling pathway was associated with poor prognosis in various solid tumors and was one of the mechanisms of acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitor, gefitinib. But the link between c‐MET activation and the cytotoxic anticancer drug has not been fully examined. Here, we found that the enhanced expression and activation of c‐MET in cytotoxic anticancer agent‐resistant small‐cell lung cancer cells. Downregulation of c‐MET expression by siRNA against the c‐MET gene or inhibition of c‐MET activation by SU11274, a c‐MET inhibitor, in the resistant cells altered resistance to the cytotoxic anticancer agent. These results indicated that c‐MET overexpression might play an important role in acquired resistance to cytotoxic anticancer drugs. Furthermore, the number of c‐MET gene loci was increased in the resistant cells compared to the parental cells. In conclusion, increased c‐Met expression through an increase in the number of c‐MET gene loci is one of the mechanisms of acquired resistance to cytotoxic anticancer drugs. Our results add a new strategy, the targeting of c‐MET, for overcoming resistance to cytotoxic agents in small‐cell lung cancer.

Serum Periostin as a Biomarker for Comorbid Chronic Rhinosinusitis in Patients with Asthma

Rationale: Periostin is a matricellular protein that is involved in the pathophysiology of allergic rhinitis, chronic rhinosinusitis, and asthma. Associations of serum periostin with systemic and airway eosinophilic inflammation and comorbid chronic rhinosinusitis in patients with asthma have been demonstrated. Although serum periostin is positioned as a marker of helper T cell 2 immune responses, its implication regarding the presence of comorbid upper airway diseases in patients with asthma remains unclear. Objectives: To investigate the utility of serum periostin as a diagnostic biomarker for upper airway disease in patients with asthma. Methods: We prospectively enrolled 65 patients with stable asthma, 20 without upper airway disease, 22 with rhinitis, and 23 with chronic rhinosinusitis (13 with nasal polyps, 10 without). Serum periostin, eotaxin, total IgE, fractional exhaled nitric oxide, and blood and sputum eosinophil levels were measured and compared between upper airway disease subtypes. We evaluated the utility of each biomarker in detecting upper airway disease, associations among the biomarkers, and severity of upper airway disease as measured by the Lund‐Mackay score for sinus computed tomography. Results: Serum periostin levels were higher in patients with asthma who had chronic rhinosinusitis (109.6 ± 47.4 ng/ml) than in those without upper airway disease (83.2 ± 22.9 ng/ml) (P = 0.04). Serum periostin levels in patients with asthma who had chronic rhinosinusitis and nasal polyps were significantly higher (130.0 ± 46.6 ng/ml) than in those without nasal polyps (87.9 ± 37.7 ng/ml) (P = 0.001). Serum periostin levels were not associated with the presence or the severity of rhinitis. In contrast, receiver operating characteristic curve analyses showed moderate diagnostic accuracy for detecting chronic rhinosinusitis (area under the curve, 0.71; P = 0.01) and high accuracy for chronic rhinosinusitis with nasal polyps (area under the curve, 0.86; P = 0.0002). When we compared patients with asthma who had comorbid chronic rhinosinusitis and nasal polyps with patients with asthma without these comorbidities, we found serum periostin to be the sole biomarker among those tested for detecting the presence of nasal polyps. Serum periostin was also the sole biomarker that significantly correlated with Lund‐Mackay score in patients with chronic rhinosinusitis (r = 0.44; P = 0.04). Conclusions: Serum periostin is useful for detecting chronic rhinosinusitis with nasal polyps and predicting radiological chronic rhinosinusitis severity in patients with asthma. Clinical trial registered with the UMIN Clinical Trials Registry (UMIN000017533).

C609T Polymorphism of NAD(P)H Quinone Oxidoreductase 1 As a Predictive Biomarker for Response to Amrubicin

Introduction: Amrubicin is a promising agent in the treatment of lung cancer, but predictive biomarkers have not yet been described. NAD(P)H:quinone oxidoreductase 1 (NQO1) is an enzyme known to metabolize amrubicinol, the active metabolite of amrubicin, to an inactive compound. We examined the relationship between NQO1 and amrubicinol cytotoxicity. Methods: Gene and protein expression of NQO1, amrubicinol cytotoxicity, and C609T single-nucleotide polymorphism of NQO1 were evaluated in 29 lung cancer cell lines: 14 small cell lung cancer (SCLC) and 15 non-SCLC (NSCLC). The involvement of NQO1 in amrubicinol cytotoxicity was evaluated by small interfering RNA against NQO1. Results: A significant inverse relationship between both gene and protein expression of NQO1 and amrubicinol cytotoxicity was found in all cell lines. Treatment with NQO1 small interfering RNA increased amrubicinol cytotoxicity and decreased NQO1 expression in both NSCLC and SCLC cells. Furthermore, cell lines genotyped homozygous for the 609T allele showed significantly lower NQO1 protein expression and higher sensitivity for amrubicinol than those with the other genotypes in both NSCLC and SCLC cells. Conclusions: NQO1 expression is one of the major determinants for amrubicinol cytotoxicity, and C609T single-nucleotide polymorphism of NQO1 could be a predictive biomarker for response to amrubicin treatment.

Involvement of intermediate filament nestin in cell growth of small-cell lung cancer

BACKGROUND Nestin is a class VI intermediate filament protein expressed in stem/progenitor cells during the development of the central nervous system. Nestin is detected in various types of tumors and is involved in malignant processes. This study investigated the expression and function of nestin in small-cell lung cancer (SCLC). METHODS Expression of nestin and achaete-scute homolog 1 (ASH1) was studied in 21 lung cancer cell lines. To assess the function of nestin, a short hairpin RNA (shRNA) targeting nestin was transfected into two SCLC cell lines (DMS53 and SBC3), and cloned cells that showed apparent down-regulation of nestin were obtained. Nestin expression was also studied immunohistochemically in surgically resected SCLC primary tumors and metastatic SCLC tumors obtained from autopsy cases. RESULT Nestin was expressed in nine of 10 SCLC cell lines. The nestin expression level was significantly higher in SCLC cell lines than in NSCLC cell lines (P < 0.01). There was a statistically significant positive correlation between the expression levels of nestin and ASH1 in SCLC cell lines. Nestin knock-down cells created by transfection with shRNA exhibited decreased invasion and cell proliferation capabilities. Furthermore, nestin was detected in SCLC tumor cells and tumor vessels in all clinical tumor specimens. CONCLUSION Nestin is expressed in SCLC in association with neuroendocrine features and participates in malignant phenotypes, including cell growth. Therefore, nestin may be a novel therapeutic target for SCLC.

Over-expression of MDR1 in amrubicinol-resistant lung cancer cells

PurposeAmrubicin, a totally synthetic 9-aminoanthracycline anticancer drug, has shown promising activity for lung cancer, but little is known about the mechanism of resistance for this agent. This study was aimed to clarify the role of P-glycoprotein (P-gp) in amrubicinol, an active metabolite of amrubicin, resistance in lung cancer cells.MethodsAmrubicinol-resistant cell line PC-6/AMR-OH was developed by continuously exposing the small-cell lung cancer cell line PC-6 to amrubicinol. Gene expression level of MDR1, which encodes P-gp, and intracellular accumulation of amrubicinol were evaluated by PC-6 and PC-6/AMR-OH cells. The involvement of MDR1 in amrubicinol resistance was evaluated by treatment with P-gp inhibitor verapamil and small interfering RNA (siRNA) against MDR1. Also, expression levels and single-nucleotide polymorphisms (SNPs) of MDR1 in 22 lung cancer cell lines were examined, and the relationships between these factors and sensitivity to amrubicinol were evaluated.ResultsThe MDR1 gene was increased approximately 4,500-fold in PC-6/AMR-OH cells compared with PC-6 cells, and intracellular accumulation of amrubicinol in PC-6/AMR-OH cells was decreased to about 15 percent of that in PC-6 cells. Treatment with verapamil and siRNA against MDR1 significantly increased the sensitivity to amrubicinol in PC-6/AMR-OH cells with increased cellular accumulation of amrubicinol. Meanwhile, neither MDR1 gene expression levels nor SNPs of the gene were associated with amrubicinol sensitivity.ConclusionsResults of this study indicate that increased MDR1 expression and P-gp activity confer acquired resistance to amrubicinol. In contrast, neither expression level nor SNPs of MDR1 are likely to be predictive markers for amrubicin activity.

Organic cation transporter OCT6 mediates cisplatin uptake and resistance to cisplatin in lung cancer

PurposeThe purposes of this study were to determine whether organic cation transporters (OCTs) can mediate platinum uptake, and whether OCT down-regulation confers resistance against cisplatin (CDDP) in cancer cells.MethodsTwo lung cancer cell lines, PC-6 and PC-14, and their CDDP-resistant derivatives, PC-6/CDDP and PC-14/CDDP, were analyzed. OCT expression levels were assayed using quantitative RT-PCR and Western blotting. Additionally, the effect of OCT6 overexpression, induced by transfection of the OCT6 gene SLC22A16 using a forced expression vector, on cellular sensitivity to CDDP and on intracellular platinum accumulation was measured using PC-14/CDDP cells.ResultsBoth gene and protein expression of OCT6 were decreased in both CDDP-resistant cell lines compared with their expression in their respective parental cells. Intracellular accumulation of platinum was decreased in PC-14/CDDP cells compared with the parental cells after CDDP treatment. Furthermore, OCT6 overexpression induced by transfection of the OCT6 gene (SLC22A16) forced expression vector-sensitized PC-14/CDDP cells to CDDP and oxaliplatin (L-OHP) concomitant with increased intracellular concentration of platinum.ConclusionOCT6 is a mediator of platinum uptake in cancer cells, and down-regulation of OCT6 is possibly one of the mechanisms of resistance against cisplatin in lung cancer.

Analgesic effect of switching from oral opioids to a once-a-day fentanyl citrate transdermal patch in patients with lung cancer.

A new once-a-day fentanyl citrate transdermal patch was developed in Japan. We retrospectively investigated analgesic and adverse effects of this drug in 24 patients with lung cancer. All patients were started on this patch by switching from an oral opioid. The mean pain score before switching was 2.45 (0-5); 48 hours after switching, 15 of the 24 patients showed a decreased pain score and the mean score (2.00) was significantly lower than that before switching. Of the 16 patients who had adverse effects of oral opioids, 7 patients showed improvement in their symptoms after switching. Two patients showed adverse effects of the drug but their symptoms were mild, and no patient required dose decrease. This new transdermal patch could be a useful treatment option for cancer pain.