Metformin and tenovin‐6 synergistically induces apoptosis through LKB1‐independent SIRT1 down‐regulation in non‐small cell lung cancer cells

Sirtuin 1 (SIRT1) is known to play a role in a variety of tumorigenesis processes by deacetylating histone and non‐histone proteins; however, antitumour effects by suppressing SIRT1 activity in non‐small cell lung cancer (NSCLC) remain unclear. This study was designed to scrutinize clinicopathological significance of SIRT1 in NSCLC and investigate effects of metformin on SIRT1 inhibition. This study also evaluated new possibilities of drug combination using a SIRT1 inhibitor, tenovin‐6, in NSCLC cell lines. It was found that SIRT1 was overexpressed in 300 (62%) of 485 formalin‐fixed paraffin‐embedded NSCLC tissues. Its overexpression was significantly associated with reduced overall survival and poor recurrence‐free survival after adjusted for histology and pathologic stage. Thus, suppression of SIRT1 expression may be a reasonable therapeutic strategy for NSCLC. Metformin in combination with tenovin‐6 was found to be more effective in inhibiting cell growth than either agent alone in NSCLC cell lines with different liver kinase B1 (LKB1) status. In addition, metformin and tenovin‐6 synergistically suppressed SIRT1 expression in NSCLC cells regardless of LKB1 status. The marked reduction in SIRT1 expression by combination of metformin and tenovin‐6 increased acetylation of p53 at lysine 382 and enhanced p53 stability in LKB1‐deficient A549 cells. The combination suppressed SIRT1 promoter activity more effectively than either agent alone by up‐regulating hypermethylation in cancer 1 (HIC1) binding at SIRT1 promoter. Also, suppressed SIRT1 expression by the combination synergistically induced caspase‐3‐dependent apoptosis. The study concluded that metformin with tenovin‐6 may enhance antitumour effects through LKB1‐independent SIRT1 down‐regulation in NSCLC cells.     

Susceptibility of irradiated B6D2F1/J mice to Klebsiella pneumoniae administered intratracheally: a pulmonary infection model in an immunocompromised host

Bacteria such as Klebsiella pneumoniae can invade and colonize an immunocompromised host and complicate clinical recovery. In the study reported here, an experimental model of induced pneumonia was developed in 60Co gamma-photon-irradiated mice for the purpose of evaluating efficacy of therapeutic agents. The model was characterized by use of probit analysis of bacterial dose, and microbiologic, and histopathologic results. Bacterial colony-forming-unit (CFU) values producing 50% mortality within 30 days (LD50/30) and their 95% confidence intervals were 4.0 x 10(4) [1.7 x 10(4) - 8.9 x 10(4)] for 0-Gray (Gy)-irradiated mice, 1.9 x 10(4) [7.0 x 10(3) - 4.8 x 10(4)] for 5-Gy-irradiated mice, and 1.0 x 10(3) [2.8 x 10(2) - 3.3 x 10(3)] for 7-Gy-irradiated mice. Probit regression line fits calculated by use of an iterative, weighted least-squares fit, were used to assess a dose-modifying factor (DMF). The DMFs for mortality, compared with that for the 0-Gy dose, with their 95% confidence intervals, were 2.2 [0.63 - 7.7] for the 5-Gy and 38.9 [9.6 -165.0] for 7-Gy doses. The 5-Gy probit line did not significantly differ (P = 0.21) from the 0-Gy probit line (dose ratios did not significantly differ from 1), whereas the 7-Gy probit line differed significantly from the 0-Gy probit line (P < 0.001). These results demonstrate that 7-Gy 60Co gamma-photon radiation in combination with intratracheal K. pneumoniae challenge induces a valid pulmonary infection model in immunocompromised female B6D2F1/J mice.     

Two juvenile hormone esterase-like carboxylesterase cDNAs from a Pandalus shrimp (Pandalopsis japonica): cloning, tissue expression, and effects of eyestalk ablation

Methyl farnesoate (MF), a crustacean juvenile hormone (JH) analog, plays important roles in the regulation of a number of physiological processes such as molting, metamorphosis, and reproduction. Understanding its metabolic pathway is a key for various potential applications in crustacean aquaculture, including artificial seed production and enhancement of growth. Although the synthetic pathway of MF is well established, little is known about its degradation and recycling in crustaceans. In insects, juvenile hormone esterase (JHE), a carboxylesterase, is responsible for JH inactivation. Two cDNAs, encoding JHE-like carboxylesterases (CXEs) from the hepatopancreas and ovary of Pandalopsis japonica, were isolated by using a combination of in-silico data mining from an expressed sequence tag (EST) database and traditional PCR-based cloning. The full length Pj-CXE1 (2084bp) and Pj-CXE2 (1985bp) cDNAs encoded proteins composed of 584 and 581 amino acids, respectively. The active site sequence and domain organization of the Pj-CXEs were highly conserved, including the catalytic triad and other motifs, which suggested that both Pj-CXEs are biologically active carboxylesterases. Phylogenetic analysis of the deduced sequences of Pj-CXEs showed that both were most closely related to the JHEs from non-lepidopteran insects. End-point RT-PCR showed that Pj-CXE1 was expressed primarily in the gonad, whereas Pj-CXE2 was expressed in both the hepatopancreas and hindgut. Quantitative PCR showed that Pj-CXE1 was upregulated in the gonads by eyestalk ablation (ESA). In contrast, ESA had no significant effect on Pj-CXE2 expression in hepatopancreas or gonad. This is the first report of the cloning of two JHE-like CXE cDNAs in decapods and the upregulation of Pj-CXE1 by acute withdrawal of eyestalk neuropeptides. Further study is needed to understand the function of CXEs in MF metabolism and its regulation by eyestalk neuropeptides.     

Biological effects of G1 phase arrest compound,sesquicillin, in human breast cancer cell lines

Sesquicillin, isolated from fungal fermentation broth, strongly induced G1 phase arrest in human breast cancer cells. During G1 phase arrest, the expression level of cyclin D1, cyclin A, and cyclin E was decreased, and the expression of CDK (cyclin-dependent-kinase) inhibitor, protein p21(Waf1/Cip1), was increased in a time-dependent manner in a breast cancer cell MCF-7. Interestingly, the G1 phase arrest induced by sesquicillin also occurred independently of the tumor suppressor protein, p53. Sesquicillin inhibits the proliferation of MCF-7 via G1 phase arrest in association with the induction of CDK inhibitor protein, p21(Waf1/Cip1), and the reduction of G1 phase related-cyclin proteins.     

The 18p11.22 locus is associated with never smoker non-small cell lung cancer susceptibility in Korean populations

The proportion of never smoker non-small cell lung cancer (NSCLC) in Asia is about 30-40%. Despite the striking demographics and high prevalence of never smoker NSCLC, the exact causes still remain undetermined. Although several genome wide association (GWA) studies were conducted to find susceptibility loci for lung cancer in never smokers, no regions were replicated except for 5p15.33, suggesting locus heterogeneity and different environmental toxic effects. To identify genetic loci associated with susceptibility of lung cancer in never smokers, we performed a GWA analysis using the Affymetrix 6.0 SNP array. For discovery GWA set, we recruited 446 never smoking Korean patients with NSCLC and 497 normal subjects. We tested association of SNPs with lung cancer susceptibility using the Cochran-Armitage trend test. For validation, 39 SNPs were selected from the top 50 SNPs and five additional SNPs were selected in the DAB1 gene region which showed significant associations in the GWA analysis. The validation SNPs were genotyped in an independent sample including 434 patients and 1,000 controls. Among the 44 validation SNPs, two SNPs (rs11080466 and rs11663246) near the APCDD1, NAPG and FAM38B genes in the 18p11.22 region were replicated. P value of rs11080466 was 1.08 × 10(-6) in the combined sets (2.68 × 10(-5) in the discovery set and 2.60 × 10(-3) in the validation set) and odds ratio was 0.68 (0.58-0.79). We observed similar association for rs11663246. Our result suggests the 18p11.22 region as a novel lung cancer susceptibility locus in never smokers.     

Synthesis and Release of Dopamine in Rat Striatal Slices: Requirement for Exogenous Tyrosine in the Medium

When incubated in a tyrosine-free medium, the tissue dopamine (DA) level of rat striatal slices increased by about 921 ± 15 pmol/mg protein during 90 min of preincubation. In contrast, the tissue-free tyrosine level declined only 130 pmol/mg protein in the same assay period. Depolarization of the slices with high K⁺ increased both DA and DOPAC outputs and depleted tissue DA level by about 75%. Although 60 min of resting after high K⁺ depolarization significantly restored the tissue DA levels, neither this restoration nor depolarization-induced DA release was altered by exogenous tyrosine. Similarly, failure of exogenous tyrosine was also observed during three successive depolarization periods of striatal slices. These results indicate that nigrostriatal dopaminergic neurons are able to synthesize and release the DA in the absence of exogenous tyrosine in the medium. Since the free tyrosine level in the slices does not seem to be a sufficient source, it is likely that tyrosine mobilized from its bound source(s) supports the DA synthesis under in vitro experimental conditions.     

EGFR Mutation Testing in Patients with Advanced Non-Small Cell Lung Cancer: A Comprehensive Evaluation of Real-World Practice in an East Asian Tertiary Hospital

Introduction

Guidelines for management of non-small cell lung cancer (NSCLC) strongly recommend EGFR mutation testing. These recommendations are particularly relevant in Asians that have higher EGFR mutation prevalence. This study aims to explore current testing practices, logistics of testing, types of EGFR mutation, and prevalence of EGFR mutations in patients with advanced NSCLC in a large comprehensive cancer center in Korea.

Methods

Our retrospective cohort included 1,503 NSCLC patients aged ≥18 years, with stage IIIB/IV disease, who attended the Samsung Medical Center in Seoul, Korea, from January 2007 through July 2010. Trained oncology nurses reviewed and abstracted data from electronic medical records.

Results

This cohort had a mean age (SD) of 59.6 (11.1) years, 62.7% were males, and 52.9% never-smokers. The most common NSCLC histological types were adenocarcinoma (70.5%) and squamous cell carcinoma (18.0%). Overall, 39.5% of patients were tested for EGFR mutations. The proportion of patients undergoing EGFR testing during January 2007 through July 2008, August 2008 through September 2009, and October 2009 through July 2010 were 23.3%, 38.3%, and 63.5%, respectively (P<0.001). The median time elapsed between cancer diagnoses and receiving EGFR testing results was 21 days. EGFR testing was most frequently ordered by oncologists (57.7%), pulmonologists (31.9%), and thoracic surgeons (6.6%). EGFR testing was more commonly requested for women, younger patients, stage IV disease, non-smokers, and adenocarcinoma histology. Of 586 cases successfully tested for EGFR mutations, 209 (35.7%) were positive, including 118 cases with exon 19 deletions and 62 with L858R mutations. EGFR mutation positive patients were more likely to be female, never-smokers, never-drinkers and to have adenocarcinoma.

Conclusions

In a large cancer center in Korea, the proportion of EGFR testing increased from 2007 through 2010. The high frequency of EGFR mutation positive cases warrants the need for generalized testing in Asian NSCLC patients.     

Mito-Tempol and Dexrazoxane Exhibit Cardioprotective and Chemotherapeutic Effects through Specific Protein Oxidation and Autophagy in a Syngeneic Breast Tumor Preclinical Model

Several front-line chemotherapeutics cause mitochondria-derived, oxidative stress-mediated cardiotoxicity. Iron chelators and other antioxidants have not completely succeeded in mitigating this effect. One hindrance to the development of cardioprotectants is the lack of physiologically-relevant animal models to simultaneously study antitumor activity and cardioprotection. Therefore, we optimized a syngeneic rat model and examined the mechanisms by which oxidative stress affects outcome. Immune-competent spontaneously hypertensive rats (SHRs) were implanted with passaged, SHR-derived, breast tumor cell line, SST-2. Tumor growth and cytokine responses (IL-1A, MCP-1, TNF-α) were observed for two weeks post-implantation. To demonstrate the utility of the SHR/SST-2 model for monitoring both anticancer efficacy and cardiotoxicity, we tested cardiotoxic doxorubicin alone and in combination with an established cardioprotectant, dexrazoxane, or a nitroxide conjugated to a triphenylphosphonium cation, Mito-Tempol (4) [Mito-T (4)]. As predicted, tumor reduction and cardiomyopathy were demonstrated by doxorubicin. We confirmed mitochondrial accumulation of Mito-T (4) in tumor and cardiac tissue. Dexrazoxane and Mito-T (4) ameliorated doxorubicin-induced cardiomyopathy without altering the antitumor activity. Both agents increased the pro-survival autophagy marker LC3-II and decreased the apoptosis marker caspase-3 in the heart, independently and in combination with doxorubicin. Histopathology and transmission electron microscopy demonstrated apoptosis, autophagy, and necrosis corresponding to cytotoxicity in the tumor and cardioprotection in the heart. Changes in serum levels of 8-oxo-dG-modified DNA and total protein carbonylation corresponded to cardioprotective activity. Finally, 2D-electrophoresis/mass spectrometry identified specific serum proteins oxidized under cardiotoxic conditions. Our results demonstrate the utility of the SHR/SST-2 model and the potential of mitochondrially-directed agents to mitigate oxidative stress-induced cardiotoxicity. Our findings also emphasize the novel role of specific protein oxidation markers and autophagic mechanisms for cardioprotection.