Effect of Asian dust on pulmonary function in adult asthma patients in western Japan: A panel study.

BACKGROUND: Asian dust (AD) has become a major health concern. The concentration of AD is typically expressed in particulate matter less than 10 µm (PM10) and 2.5 µm (PM2.5). However, PM10 and PM2.5 consist of various substances besides AD. Light detection and ranging (LIDAR) systems can selectively measure the quantity of AD particles to distinguish non-spherical airborne particles from spherical airborne particles. The objective of this study was to investigate the relationship between pulmonary function in adult asthma patients and AD using LIDAR data. METHODS: Subjects were 231 adult asthma patients who had their morning peak expiratory flow (PEF) measured from March to May 2012. A linear mixed model was used to estimate the association of PEF with sand dust particles detected by LIDAR. RESULTS: Increases in the interquartile range of AD particles (0.018 km(-1)) led to changes in PEF of -0.42 L/min (95% confidence interval [CI], -0.85 to 0.01). An increase of 11.8 µg/m(3) in suspended particulate matter and 6.9 µg/m(3) in PM2.5 led to decreases of -0.17 L/min (-0.53 to 0.21) and 0.03 L/min (-0.35 to 0.42), respectively. A heavy AD day was defined as a day with a level of AD particles >0.032 km(-1), which was the average plus one standard deviation during the study period, and six heavy AD days were identified. Change in PEF after a heavy AD day was -0.97 L/min (-1.90 to -0.04). CONCLUSIONS: Heavy exposure to AD particles was significantly associated with decreased pulmonary function in adult asthma patients.

Effects on asthma and induction of interleukin-8 caused by Asian dust particles collected in western Japan.

OBJECTIVE: Asian dust storms (ADS) contain various airborne particles that may augment airway inflammation by increasing the level of interleukin-8. The objective of the study was to investigate the association of exposure to an ADS with worsening of symptoms of adult asthma and the effect of ADS particles on interleukin-8 transcriptional activity. METHODS: The subjects were 112 patients with mild to moderate asthma who recorded scores for their daily upper and lower respiratory tract symptoms and measured morning peak expiratory flow (PEF) from March to May 2011. Interleukin-8 transcriptional activity was assessed in THP-G8 cells that were exposed to airborne particles collected during days of ADS exposure. RESULTS: Of the 112 patients, 31 had comorbid allergic rhinitis (AR) and/or chronic sinusitis (CS), and had worsened scores for upper respiratory tract symptoms on ADS days compared to non-ADS days. Scores for lower respiratory tract symptoms during ADS days were higher than non-ADS days in all patients. Three patients also had unscheduled hospital visits for exacerbation of asthma on ADS days. However, there was no significant difference in daily morning PEF between ADS and non-ADS days. Airborne particles collected on ADS days induced interleukin-8 transcriptional activity in THP-G8 cells compared to the original soil of the ADS. CONCLUSION: Exposure to an ADS aggravates upper and lower tract respiratory symptoms in patients with adult asthma. ADS airborne particles may increase airway inflammation through enhancement of interleukin-8 transcriptional activity.

[A case of lung abscess due to Aspergillus viridinutans in a patient with aplastic anemia].

A 75-year-old woman with aplastic anemia was admitted to our university hospital because of a dry cough that had persisted for a month. Chest computed tomography showed a mass shadow with a central low attenuation area in the lower lobe of the left lung. Filamentous fungus resembling Aspergillus fumigatus was cultured from the specimens obtained by transthoracic needle aspiration biopsy and bronchoalveolar lavage. The initial diagnosis was a lung abscess due to A. fumigatus, although the patient did not respond well to antifungal agents. Subsequently, the filamentous fungus was identified as Aspergillus viridinutans by sequence analysis of the ß-tubulin gene, and the patient was successfully treated with combination therapy along with granulocyte colony-stimulating factor. The incidence of A. viridinutans infection is very rare. A. viridinutans is morphologically similar to A. fumigatus; however, the response to antifungal agents is generally worse than that observed in A. fumigatus infections. Therefore, the selection of agents and supplemental therapy is of vital importance in cases of A. viridinutans infection.

Diagnostic and prognostic impact of serum-soluble UL16-binding protein 2 in lung cancer patients.

UL16-binding protein 2 (ULBP2) is one of the ligands for NKG2D (NKG2DL). ULBP2 expression is induced in transformed cells and is recognized by immune effector cells via the activating NKG2D immunoreceptor. Soluble forms of NKG2DL have been reported in the serum of patients with several types of cancer. The present study investigated the diagnostic and prognostic significance of serum-soluble ULBP2 (sULBP2) in lung cancer patients. We used flow cytometry to evaluate the surface expression of NKG2DL by various lung cancer cells, while sULBP2 was measured using our original ELISA. In addition, the immunological effect of sULBP2 on peripheral blood mononuclear cells (PBMC) was examined by the (51) Cr release assay. We found that ULBP2 was highly expressed and that the sULBP2 level was elevated in supernatants of cultured non-small-cell lung cancer (NSCLC) cells as well as in the serum of NSCLC patients. ULBP2 levels were especially high in squamous cell carcinoma (SQ) patients. Clinical stage IIIB and IV NSCLC patients with a sULBP2 level ≥ 8.7 pg/mL showed significantly shorter survival than patients with sULBP2 <8.7 pg/mL. In multivariate analysis, a sULBP2 level ≥ 8.7 pg/mL (hazard ratio [HR], 2.13; P = 0.038) and clinical stage IV (HR, 2.65; P = 0.019) were independent determinants of a poor outcome. As a possible mechanism, we demonstrated that sULBP2 directly suppresses the cytolytic activity of PBMC. In conclusion, ULBP2 is the most significant NKG2DL for lung cancer, and sULBP2 is useful in the diagnosis of SQ and as a prognostic indicator for patients with advanced NSCLC.

Pollen augments the influence of desert dust on symptoms of adult asthma patients.

BACKGROUND: East Asian desert dust storms that occur during mainly spring are called Asian dust storms (ADS). Our objective was to study the association of pollen and ADS with symptoms of adult asthma patients in Japan. METHODS: We designed a telephone survey to investigate the upper and lower respiratory, ocular, and skin symptoms of asthma patients during ADS in February, March, and December on 2009. Peak expiratory flow (PEF) was also measured from February to May. RESULTS: We surveyed 106 patients in February, 101 patients in March, and 103 patients in December. In February and March, Japanese cedar and/or cypress pollen was also in the atmosphere during ADS, but no pollen was identified during December survey. Worsening of upper or lower respiratory, ocular, or skin symptoms was noted by 20.8% of patients in February, 33.7% in March, and 16.5% in December. Worsening of symptoms was significantly more common in March than in February or December. Two patients needed emergency treatment for exacerbation during ADS in March, but no patient needed hospitalization in any period. There was no significant difference of the daily morning PEF/personal best PEF ratio between ADS days and control days. However, in patients with worsening of upper and/or lower respiratory tract symptoms, the daily morning PEF/personal best ratio was significantly associated with the atmospheric level of particulate matter, but not with levels of pollen or other air pollutants. CONCLUSIONS: Pollen augmented symptoms in adult asthma patients, but ADS on its own also were able to aggravate symptoms and pulmonary function.

Correlation between Asian dust storms and worsening asthma in Western Japan.

BACKGROUND: Severe wind storms during spring in East Asia, called Asian dust storms (ADS), have been assessed in the past for their effect on health in Asian countries. Our objective was to study the ADS association with asthma symptoms in adult patients in Japan. METHODS: We designed a telephone survey to assess ADS influence on upper and lower respiratory, ocular and cutaneous symptoms in 98 patients with adult asthma from April to May 2007. Peak expiratory flow (PEF) was also measured from February to May. RESULTS: Worsening lower respiratory symptoms were noted by 22 of 98 patients during ADS in April, when Japanese cedar pollen levels also increased. During ADS in May, however, Japanese cedar and cypress pollen levels were not elevated, 11 patients had worsening of lower respiratory symptoms. None required emergency treatment for the exacerbation. Lower respiratory symptoms worsening most were cough and sputum; this was more common in patients with allergic rhinitis or atopy than in those without (P < 0.05). Min%Max differed significantly at 88.7 ± 6.6% during dust dispersion period, defined as the ADS day plus the next 6 days, versus 92.0 ± 5.3% during the 7-day period before a dust storm. CONCLUSIONS: We found that ADS aggravated lower respiratory symptoms in adult patients with asthma, but this influence was mild.

[High-sensitivity C-reactive protein and changes over time in forced expiratory volume in 1 second in adult-onset asthma].

PURPOSE: To study the possibility that changes in high-sensitivity C-reactive protein (hs-CRP) may be a predictor of forced expiratory volume in 1 second (FEV1) decline over time in adult asthmatic subjects. METHODS: Subjects with adult-onset asthma with no smoking history underwent complete medical evaluation at Yoka Public Hospital in both 2005 and in 2008 (n = 26). We analyzed the correlation between hs-CRP levels and FEV1 changes over time, in relation to whether or not they received inhaled corticosteroid (ICS) therapy. We also measured the cardio-ankle vascular index (CAVI), intima-media-thickness (IMT), and fraction of exhaled nitric oxide (FeNO) of hospital staff members who acted as non ICS asthmatic subjects (n = 11), and also performed multiple regression analysis. RESULTS: In the non-ICS asthmatic subjects group (n = 19), there was a significant correlation between log (hs-CRP) levels and FEV1 changes (R = -0.734, P < 0.001). After controlling for age, body mass index, CAVI, IMT, and FeNO, hs-CRP was found to be an independent risk factor. CONCLUSION: Hs-CRP levels are a predictor of FEV1 decline over time in adult-onset asthmatic patients with no smoking history, who are not receiving ICS therapy.

Synergistic cell growth inhibition by the combination of amrubicin and Akt-suppressing tyrosine kinase inhibitors in small cell lung cancer cells: implication of c-Src and its inhibitor.

Small cell lung cancer (SCLC) is one of the intractable malignancies. The goal of this study was to clarify whether Akt activity is involved with chemo-resistance and to improve the sensitivity of SCLC cells to the current standard chemotherapeutic drugs with agents that are expected to suppress Akt activity through tyrosine kinase inhibition. Although Akt activity seemed to be involved with the sensitivity of SCLC cells to chemotherapeutic agents (cisplatin, etoposide, SN38 and amrubicin), in Akt-activated N417 cells, only amrubicin exerted synergistic cell growth inhibition when combined with an Akt inhibitor, LY294002. A non-specific tyrosine kinase inhibitor, genistein, suppressed Akt and showed synergistic interaction in combination with amrubicin in N417 cells. Among tyrosine kinases (insulin-like growth factor I receptor, c-Kit and c-Src), only c-Src was activated in N417 cells compared with Akt-inactive H209 cells. A c-Src-specific inhibitor, PP2, and a clinically available multi-tyrosine kinase inhibitor, dasatinib, suppressed Akt activity in parallel with c-Src inhibition. Both PP2 and dasatinib exerted synergistic growth inhibition of N417 cells in the combination with amrubicin. In immunohistochemical analysis, c-Src was expressed in 17 of 19 of the SCLC tumor tissues. These observations suggested that Akt suppression enhances the cytotoxicity of amrubicin, and for the purpose of Akt suppression, c-Src is a promising target in SCLC.

Environmental tobacco smoke and its effect on the symptoms and medication in children with asthma.

Environmental tobacco smoke (ETS) worsens asthmatic symptoms. We analyzed the relationship between levels of ETS and asthmatic symptoms and medication. We asked parents of 282 asthmatic children about the general condition, smoke exposure and medication. Patients were classified into three groups: no-ETS (no smoking), mild-ETS (smoking in the house but not in the same room as patient), and heavy-ETS (smoking in the same room as patient). We classified 116 children in no-ETS group, 124 children in mild-ETS group and 42 children in heavy-ETS group. The symptoms were worst and prevalence of leukotriene receptor antagonist and long-acting beta(2)-agonist use were highest in heavy-ETS group. However, there was no statistical difference between no-ETS and mild-ETS groups in prevalence of anti-asthmatic drug use and symptoms. We conclude that a smoking ban in rooms used by asthmatic children is an easy way to reduce ETS, asthmatic symptoms and the use of anti-asthmatic drugs.

[Acute bird-related hypersensitivity pneumonitis: radiological findings in a case in the early phase after onset].

A 71-year-old woman was admitted to our hospital four times because of high fever and dyspnea from September to November in 2007. We treated her with antibiotics on her first two admissions. HOwever, we suspected hypersensitivity pneumonitis on the third admission because she suffered from fever and dyspnea soon after she had been discharged and returned home. She recovered only with the oxygen therapy on the last two admissions. Computed tomography of the chest showed early phase localized consolidation but changed to ground-glass opacities spreading over the entire lung field later during her third and fourth admissions. Bronchial alveolar lavage showed increases in total cell count, lymphocytes and IgA of pigeon-dropping extracts' and budgerigar-dropping extracts. TBLB showed epithelioid cell granulomas without caseous necrosis and alveolar septal inflammation. Inhalation challenge test using freeze-dried pigeon-dropping extracts was positive, therefore we finally established a diagnosis of acute bird related hypersensitivity pneumonitis. This is apparently the first report of acute bird-related hypersensitivity pneumonitis showing localized consolidation initially and later changing to diffuse ground-glass opacities. These radiological observations are significant in considering the onset and the progression of this disease.

Nivolumab-induced cholangitis in patients with non-small cell lung cancer: Case series and a review of literature.

Immune checkpoint inhibitors (ICIs), including nivolumab, have exhibited substantial benefits in the treatment of several types of cancers. However, treatment with ICIs is often accompanied by immune-related adverse events (irAEs), and a clear understanding of the precise indications and management of irAEs is important for harnessing the full potential of these agents. While skin- or gastrointestinal-associated irAEs have been relatively well studied, there are few reports regarding nivolumab-induced cholangitis. We retrospectively reviewed data from patients with advanced or recurrent non-small cell lung cancer who were treated with nivolumab between December 2015 and December 2018 at Tottori University in Japan. Among the 59 patients, we identified four patients who experienced nivolumab-induced cholangitis. Of these four patients, stable disease (SD) was observed in two patients (50%), while partial response (PR) was achieved in two patients (50%) under nivolumab treatment. Patients were treated with corticosteroid alone (n=2) or in combination with mycophenolate mofetil (MMF) (n=2); these treatments resulted in improvements in nivolumab-induced cholangitis in three patients. In conclusion, the present retrospective study identified four cases of nivolumab-induced cholangitis. The combination of corticosteroid and MMF was effective in two cases with grade 4 nivolumab-induced cholangitis. Further reports are needed to establish the optimal management of patients with this irAE.

Dexamethasone interferes with trastuzumab-induced cell growth inhibition through restoration of AKT activity in BT-474 breast cancer cells.

The combination of trastuzumab with paclitaxel (PTX) is an important option for the treatment of HER2-positive breast cancer. Dexamethasone (Dex) premedication is routinely used in the treatment with PTX. The interactions among Dex, PTX and trastuzumab were evaluated in BT-474 cells. Dex interfered with trastuzumab-induced cell growth inhibition without clear effects on PTX-induced cytotoxicity. Trastuzumab dephosphorylated retinoblastoma protein (pRB). Dex restored this trastuzumab-induced dephosphorylation of pRB and released trastuzumab-induced G1 arrest. Trastuzumab suppressed AKT activity without affecting ERK activity. A specific inhibitor for the phosphatidylinositol 3-kinase/AKT pathway, LY294002, inhibited cell growth and AKT and pRB phosphorylation. Dex restored the trastuzumab-induced suppression of AKT without affecting ERK activity. It was concluded that Dex interferes with trastuzumab-induced cell growth inhibition, at least partially, through the restoration of trastuzumab-induced AKT suppression and subsequent pRB dephosphorylation in BT-474 breast cancer cells. These observations support the development of new chemotherapeutic regimens without glucocorticoid premedication.

Sequential treatment with SN-38 followed by 5-fluorouracil shows synergistic cytotoxic activity in small cell lung cancer cells.

Despite the high response rates of small cell lung cancer (SCLC) to first-line cisplatin-based chemotherapies, most patients with SCLC will eventually experience disease progression. Accordingly, novel chemotherapeutic regimens are desired. This in vitro study was carried out in order to develop novel chemotherapeutic regimens containing 5-fluorouracil (5-FU) or oral fluoropyrimidine for SCLC. 5-FU was combined with other standard drugs for SCLC (cisplatin, etoposide, an active metabolite of irinotecan and amrubicin) in different schedules. The combination effects were analyzed by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and an isobologram method using H69 SCLC cells. Among the examined combinations, synergistic growth inhibition was observed only when H69 cells were treated with 7-ethyl-10-hydroxycamptothecin (SN-38; an active metabolite of irinotecan) followed by 5-FU. The findings of a flow cytometric analysis were consistent with the enhancement of apoptotic cell death by this sequential treatment. This synergism was observed in 4 out of 5 SCLC cell lines tested. The effects of 5-FU and SN-38 on thymidylate synthase (TS) protein expression, an important determinant of 5-FU sensitivity, were assessed by Western blot analysis in H69 cells. Treatment with SN-38 for 24 h suppressed TS protein expression and this low level of TS was maintained for at least 72 h. Pretreatment with SN-38 inhibited the 5-FU-induced increase of TS protein. The synergistic effect induced by the combination of SN-38 and 5-FU may be attributable to the SN-38-induced suppression of TS protein. Furthermore, uracil and 5-chloro-2,4-hydroxypyridine, which are clinically available dihydropyrimidine dehydrogenase inhibitors, enhanced 5-FU-induced growth inhibition. These observations provide evidence supporting the clinical applications of the combination chemotherapy using irinotecan and 5-FU or oral fluoropyrimidines against SCLC.

Early Intensive Nutrition Intervention with Dietary Counseling and Oral Nutrition Supplement Prevents Weight Loss in Patients with Advanced Lung Cancer Receiving Chemotherapy: A Clinical Prospective Study.

BACKGROUND: Weight loss in patients with cancer is caused by cancer cachexia and chemotherapy-induced nausea and vomiting (CINV). Recent developments in antiemetic drugs have substantially improved CINV, but nutritional intervention did not improve body weight. This study aimed to investigate the effects of nutrition intervention with appropriate antiemetic treatment in patients with non-small-cell lung cancer during chemotherapy. METHODS: Patients received individualized nutrition counseling by a registered dietitian and were provided with oral supplements for 90 days. Body weight and other parameters were measured at baseline and after 90-day intervention. To evaluate this nutrition intervention, patients were also retrospectively set as control, and then body weight change was compared with inverse probability of treatment weights (IPTW) analysis. RESULTS: Ten patients received individualized nutrition counseling and were provided with oral supplements for 90 days. Of them, 7 patients consumed nutritional supplements, and the mean intake was 130 kcal/day. After 90-day intervention, the patients did not show significant weight and BMI loss during the course of cytotoxic chemotherapy. A total of 38 patients were retrospectively enrolled as controls. The number of the patients who gain the body weight after 90 days in the study cohort was significantly larger than that in the retrospective controls with the IPTW analysis (Odds Ratio (OR) = 8.4; 95% Confidence Interval (CI): 1.6-42; P = 0.01). CONCLUSION: Early intensive nutrition intervention with appropriate antiemetic treatment prevents weight loss. Nutrition interventions might be also beneficial for quality of life, treatment response and survival.

Acute-phase reaction induced by zoledronate and its effect on prognosis of patients with advanced non-small cell lung cancer.

OBJECTIVES: Zoledronate (ZOL) is usually used for prevention of skeletal-related events in cancer patients with bone metastases. The first administration of ZOL is occasionally associated with development of acute-phase reaction (APR), which is due to activation of γδ T cells. ZOL-related APR was associated with better overall survival (OS) of patients with non-small cell lung cancer (NSCLC) in our previous retrospective study. However, it remains to be clarified whether γδ T cells are more activated in patients who experienced ZOL-related APR, and whether γδ T cell activation is involved in prolongation of OS. MATERIALS AND METHODS: Twenty-three patients with advanced NSCLC were recruited between 2012 and 2014 in this study. We administered ZOL to participants with standard care. The patient characteristics, change in γδ T cell counts and cytokines, OS, and skeletal-related event-free survival were compared between patients with APR (APR group) and those without APR (non-APR group). RESULTS: Ten patients (43.5%) experienced a ZOL-related APR. The number of γδ T cells at baseline in the APR group was significantly higher than that in the non-APR group. Serum interleukin-6 and tumor necrosis factor-α in the APR group were significantly increased, but no change in the number of γδ T cells was observed after the first administration of ZOL in both groups. OS in the APR group was significantly longer than that in the non-APR group (median survival time: 23.1 vs. 14.5 months, p < 0.01). CONCLUSION: We showed that APR is related to higher numbers of γδ T cells at baseline and increased cytokines after the first ZOL administration, but not to proliferative responses of γδ T cells. In addition, better OS was observed in the APR group. Therefore, the number of γδ T cells might be a prognostic marker in patients with NSCLC.

Dexamethasone inhibits paclitaxel-induced cytotoxic activity through retinoblastoma protein dephosphorylation in non-small cell lung cancer cells.

Paclitaxel is used frequently for the treatment of patients with non-small cell lung cancer. Hypersensitivity reactions remain one of the major adverse events in the clinical use of paclitaxel. Glucocorticoids are used to prevent these adverse events. This study was carried out in order to clarify the effect of glucocorticoids on paclitaxel-induced cytotoxity of cancer cells. Pretreatment with 10 microM of dexamethasone inhibited ERK activation and subsequent retinoblastoma protein (pRB) phosphorylation, and reduced sensitivity to paclitaxel in A549 cells. Then, we utilized ERK (PD98059) and AKT (LY294002) inhibitors. PD98059 and LY294002 effectively suppressed pRB phosphorylation in A549 cells. Dexamethasone (10 microM) suppressed ERK activity as well as PD98059, although it did not affect AKT activity. Furthermore, the combinations of paclitaxel with PD98059 or LY294002 were similarly antagonistic. Our observation in this study raised the possibility that dexamethasone pretreatment antagonizes paclitaxel-induced cytotoxicity through ERK suppression and pRB dephosphorylation. These observations support the development of new generation taxane-based chemotherapy without glucocorticoid premedication.

Diverse activation states of RhoA in human lung cancer cells: contribution of G protein coupled receptors.

Rho GTPases play an essential role in the control of various cellular functions. Accumulating evidence suggests that RhoA overexpression contributes to human cancer development. However, the activation states of RhoA are poorly defined in cancer cells. In this study, we examined both the expression levels and the activation states of RhoA in various lung cancer cells by quantitative real-time reverse transcriptase-polymerase chain reaction and in vivo Rho guanine nucleotide exchange assay, respectively. Moreover, we dissected the signaling pathway from the cell surface receptors to RhoA using a broad-spectrum G protein coupled receptor (GPCR) antagonist, [D-Arg1,D-Trp5,7,9,Leu11]Substance P (SP), and a recently reported Galphaq/11-selective inhibitor, YM-254890. We found that RhoA was expressed highly in large cell carcinoma cells but only weakly in adenocarcinoma cells. The activation states of RhoA are considerably different from its expression profiles. We found that four of six small cell lung carcinoma (SCLC) cell lines exhibited a moderate to high activation rate of RhoA. The addition of [D-Arg1,D-Trp5,7,9,Leu11]SP reduced RhoA activity by almost 60% in H69 SCLC cells. The addition of YM-254890 had no effect on RhoA activity in H69 cells. Our results suggest that RhoA is activated in various lung cancer cells independent of its expression levels, and the high activation state of RhoA in SCLC cells mainly depends on a neuroendocrine peptide autocrine system which signals through Galpha12 coupled GPCR to RhoA. This study provides new insights into RhoA signaling in lung cancer cells and may help in developing novel therapeutic strategies against lung cancer.

A case of lung abscess successfully treated by transbronchial drainage using a guide sheath.

A 51-year-old man was diagnosed with colon cancer in September 2011, and a solitary pulmonary nodule was detected by computed tomography (CT) scan. We performed a transbronchial biopsy with endobronchial ultrasonography using a guide sheath (GS) and diagnosed lung metastasis of colon cancer. The patient experienced remittent fever after the biopsy in spite of intravenous antibiotic therapies. Moreover, his CT scan showed a large lung abscess at the biopsy site. We performed transbronchial drainage using a GS as salvage therapy. The bloody pus was successfully aspirated, and chest X-ray following the procedure showed dramatic shrinkage of the abscess.

A novel SLC34A2 mutation in a patient with pulmonary alveolar microlithiasis.

Pulmonary alveolar microlithiasis (PAM) is a rare autosomal recessive disease caused by mutations in SLC34A2 and characterized by intra-alveolar accumulation of microliths. We diagnosed a case of PAM in a 27-year-old Japanese female and identified a novel mutation in SLC34A2 (c.1390 G>C [G464R] in exon 12).

DNA-PK Inhibition by NU7441 Enhances Chemosensitivity to Topoisomerase Inhibitor in Non-Small Cell Lung Carcinoma Cells by Blocking DNA Damage Repair.

BACKGROUND: DNA double-strand breaks (DSBs) are the most cytotoxic form of DNA damage and are induced by ionizing radiation and specific chemotherapeutic agents, such as topoisomerase inhibitors. Cancer cells acquire resistance to such therapies by repairing DNA DSBs. A major pathway for the repair of DNA DSBs is non-homologous end-joining (NHEJ), which requires DNA-dependent protein kinase (DNA-PK) activity. In this study, we investigated the effect of NU7441, a synthetic small-molecule compound, as a specific inhibitor of DNA-PK on the chemosensitization of non-small cell lung carcinoma (NSCLC) A549 cells. METHODS: The combined effects of chemotherapeutic agents and NU7441 were evaluated by isobologram analysis using Cell Counting Kit-8. DNA DSBs were assessed by immunofluorescence assay. Apoptosis was examined by flow cytometry using an Annexin V apoptosis kit. Activation of DNA-PK was assayed by western blotting. RESULTS: The combination of NU7441 and topoisomerase inhibitors such as amrubicin and irinotecan had a synergistic effect on cell proliferation in A549 cells. NU7441 increased 53BP1 foci and apoptosis induced by topoisomerase inhibitors and decreased phospho-DNA-dependent protein kinase, catalytic subunit (pDNA-PKcs) (S2056) protein expression caused by topoisomerase inhibitors. Interestingly, mitotic inhibitors such as pacritaxel did not cause the pDNA-PKcs (S2056) protein expression and the combination of NU7441 and pacritaxel had an only additive effect. CONCLUSION: NU7441 inhibited the growth of NSCLC cells and enhanced the chemosensitization to topoisomerase inhibitors by blocking DNA repair. A combination of NU7441 and topoisomerase inhibitor may be a promising treatment for NSCLC.