High-efficiency EGFR genotyping using cell-free DNA in bronchial washing fluid.

BACKGROUND: EGFR mutation testing is required for treatment of lung adenocarcinoma using epidermal growth factor receptor-tyrosine kinase inhibitor. However, the amounts of tumor tissue or tumor cells obtained by bronchoscopy are often insufficient. Bronchial washing fluid, obtained by lavage with saline after tumor biopsy or brushing, and the supernatant of bronchial washing fluid are thought to contain cell-free DNA that would be potentially applicable for EGFR testing. METHODS: From among patients with suspected adenocarcinoma or non-small cell lung carcinoma diagnosed from biopsy or surgical specimens at the University of Tsukuba Hospital between 2015 and 2019, cell-free DNAs from 80 specimens of supernatant of bronchial washing fluid (50 with EGFR mutation and 30 with wild type EGFR) and 8 blood serum samples were examined for EGFR mutation using droplet digital PCR. RESULTS: Among the 50 patients harboring EGFR mutation, the rate of positivity for cell-free DNA extracted from supernatant of bronchial washing fluid was 80% (40/50). In nine of the EGFR mutation-positive cases, tumor cells were not detected by either biopsy or cytology, but the mutation was detected in four cases (4/9, 44%). Comparison of the cell-free DNA mutation detection rate between supernatant of bronchial washing fluid and blood serum in six cases showed that mutations were detected from the former in all cases (6/6, 100%), but from the latter in only one case (1/6, 17%). CONCLUSIONS: Using supernatant of bronchial washing fluid samples, the detection rate of EGFR mutation was high, and EGFR mutations were detectable even when no tumor cells had been detectable by biopsy or cytology. Supernatant of bronchial washing fluid might be an effective sample source for EGFR mutation testing.

Difference in susceptibility to morphological changes in the nucleus to aneugens between p53-competent and p53-abrogated lymphoblastoid cell lines (TK6 and NH32 cells) in the in vitro micronucleus assay.

We previously reported that the proportion of large-size micronuclei (MN) can be a reliable parameter to discriminate aneugens from clastogens in the in vitro MN assay using Chinese hamster lung cells. The frequencies of polynuclear (PN) and mitotic (M) cells are also supposed to be useful parameters for the same purpose since they are known to be increased by aneugens. In the present study, we investigated whether morphological observations of the cell nucleus can be applied for the in vitro MN assay using the p53-competent human lymphoblastoid cell line, TK6 cells. Our present MN assay with six clastogens and six aneugens revealed that the frequencies of large-size MN or PN cells cannot distinguish aneugens from clastogens, while the frequencies of M cells can distinguish them, suggesting that the M-cell frequency is a recommended parameter to determine a mode of action for MN induction in the in vitro MN assay using TK6 cells. Our further investigation using p53-null mutant NH32 cells showed that the frequencies of large-size MN or PN cells induced by aneugen treatments were higher than those in TK6 cells but not by clastogen treatments. These findings suggest that p53 abrogation promotes the susceptibility for morphological changes in the nucleus to aneugens and that morphological observation of the cell nucleus including size-classifying MN counting could distinguish aneugens from clastogens in the MN assay using NH32 cells.

Involvement of p53 function in different magnitude of genotoxic and cytotoxic responses in in vitro micronucleus assays.

In in vitro micronucleus (MN) assays the sensitivity to MN induction or cytotoxicity can vary depending on the kind of cells employed. This study was conducted to examine the involvement of the p53 function in the different sensitivities between Chinese hamster lung (CHL) cells and human lymphoblastoid TK6 cells in MN assays. MN induction and cytotoxicity were compared using MN-inducing chemicals reported as DNA reactive clastogens, non-DNA reactive clastogens or aneugens. The study revealed that the maximum levels of MN induction in p53-compromised CHL cells were higher than those in p53-competent TK6 cells, but MN were significantly induced in TK6 cells at lower concentrations than in CHL cells. Most of the test chemicals produced a more severe cytotoxicity in TK6 cells, suggesting TK6 cells are more sensitive for cytotoxicity than CHL cells. An additional experiment with 9 MN inducers revealed that the magnitude of MN induction and cytotoxicity were comparable between p53-competent TK6 cells and its p53-null mutant NH32 cells at the same concentrations. Furthermore, the MN frequencies induced by methylmethane sulfonate, aphidicolin and hydroxyurea in NH32 cells were identical to those in TK6 cells at different recovery times. From these results, it is suggested that the p53 abrogation does not explain the difference in sensitivity to MN induction or cytotoxicity between CHL and TK6 cells. In this regard, p53 abrogated NH32 cells can be an option for the in vitro MN assay.

Comparison of four different treatment conditions of extended exposure in the in vitro micronucleus assay using TK6 lymphoblastoid cells.

In the OECD Guideline 487, a total of four extended exposure treatment conditions are proposed for the in vitro micronucleus (MNvit) assay in the presence and absence of a cytokinesis block and with or without a recovery period. This guideline also states that rodent cell lines and human lymphocytes can be used as shown by many validated studies but that human cell lines such as TK6 and HepG2 are not yet validated. In this present study each extended exposure condition was characterized by investigation using TK6 cells and nine chemicals known to be able to induce micronucleus (MN) in rodent cell lines. The results revealed two concerns: six chemicals did not show significant MN induction in the 'cytokinesis block without recovery period'; two aneugens showed no dose-dependent cytotoxicity in the 'cytokinesis block with recovery period'. Further investigation revealed that 3-4 times higher spontaneous MN frequency than that in the other conditions is a possible reason for the low sensitivity, and this high spontaneous MN frequency was not observed in Chinese hamster lung cells under the identical treatment condition. With regard to the two conditions without cytokinesis block, two negative substances were evaluated and found to be negative, suggesting the validity of the TK6 test system for these conditions. Although our findings showed a few concerns for the treatment with cytokinesis block, the TK6 cells were considered to be a reliable cell line to be used for detecting potential inducers of MN in the in vitro micronucleus assay based on the overall results.

An in vitro micronucleus assay with size-classified micronucleus counting to discriminate aneugens from clastogens.

In the in vitro micronucleus (MN) assay, genotoxic chemicals can be characterized as aneugens and clastogens by the presence and absence of kinetochore protein or centromere regions in the micronuclei, respectively. Aneugens preferentially induce kinetochore- or centromere-positive micronuclei which can be detected by the immunofluorescence staining method or the fluorescence in situ hybridization (FISH) method. Both methods are robust and reliable; however, these assays require a definite period of time and cost to obtain a result that suggests that the genotoxic chemicals cause aneuploidy. This is why these methods are not adequate to evaluate dozens of chemicals which are mixtures of aneugens and clastogens. To evaluate a batch of chemicals, a quicker and more convenient assay is desirable. In the present study, we examined whether the size-classified counting of MN is as effective as the FISH method to characterize aneuploidy in the in vitro MN assay using Chinese hamster lung (CHL) cell lines. As aneugens, 9 substances (colcemid, vincristine sulfate, paclitaxel, thiabendazole, diethylstilbestrol, griseofulvin, bisphenol A, fisetin and okadaic acid) were used; as clastogens 6 substances (methylmethane sulfonate, N-methyl-N'-nitro-N-nitroso-guanidine, etoposide, mitomycin C, hydroxyurea and actinomycin D) were used. The size-classified counting revealed that all the 9 aneugens increased both the frequency and proportion of large-size MN as compared with the vehicle control. Although N-methyl-N'-nitro-N-nitroso-guanidine, etoposide and mitomycin C increased the frequency, no increase was observed in the proportion. Meanwhile, with the FISH method, all the aneugens induced centromere-positive micronuclei but the clastogens did not. Based on these results, it is considered that the frequency of large-size MN in the in vitro MN assay is an alerting index for aneugenic effects and that its proportion is a simple and reliable index which is as effective as the FISH analysis for discrimination of aneugens from clastogens.

Individual differences in rate-limiting reactions during metabolism of irinotecan hydrochloride.

UNLABELLED: Irinotecan hydrochloride (CPT-11) is converted to SN-38 by carboxylesterase, SN-38 is conjugated by UDP-glucuronosyl- transferase (UGT) to SN-38G. Individual differences in enzyme activity influence the efficacy of this anticancer agent and the adverse reactions it induces. In this study, individual differences in the metabolism of this drug were determined by calculating its c 1 on version (CPT-11 to SN-38) and conjugation ratios (SN-38 to SN-38G) from blood concentrations of CPT-11, SN-38, and SN-38G at immediately and 60 min after a 90-min intravenous infusion of CPT-11. Changes in conversion and conjugation during long-term infusion of CPT-11 were also investigated. The median conversion and conjugation ratios were 0.0155 and 2.812, respectively (n=48). Based on these values, the patients were classified into four types: low-low type (10.4%), low-high type (31.2%), high-low type (31.2%), and high high type (27.1%). Prolongation of infusion time resulted in an increase in the conversion ratio in the low-high type and an increase in the conjugation ratio in the high-low type. These changes, however, were very slight in the high-high type. Thus, a longer infusion time made it possible to increase the number of doses in the low-high type and minimize adverse reactions in the high-low type. CONCLUSION: In patients found to have a low SN-38 conversion ratio or SN-38G conjugation ratio based on simple assessment of data obtained by 2-point blood sampling, modification of infusion time may allow pharmacokinetic changes that confer a clinical benefit.

[Significance of urinary uracil measurement following administration of DPD inhibitory fluoropyrimidine(DIF)products].

Individual differences in 5-FU metabolism are mainly attributed to individual differences in the activity of DPD, an enzyme that can metabolize more than 85% of 5-FU. Because urinary uracil is a reflection of DPD activity, it is measured to predict and prevent the occurrence of side effects caused by pyrimidine-type chemotherapeutic agents. From urinary uracil values measured in 84 gastrointestinal cancer patients, 0-60 mmol/g.creatinine was set as a standard. In patients whose urinary uracil values exceeded the standard, 5-FU tended to be accumulated when S-1, a DIF product, was administered and side effects, such as anorexia, vomiting and diarrhea occurred immediately after the start of S-1 administration. If an appropriate DIF product is selected and its dosage set based on the patient's urinary uracil value, the occurrence of side effects would be reduced. Subsequently, a continuation of medication would be possible.

[Clinical pathway for management of patients with acute asthma attack].

BACKGROUND: There have been few reports of clinical pathway (CP) for treatment of asthma attack, because patients with asthma always admit emergently and the severity varies. We introduced CP so that standard asthma treatment can be widely used, and investigated its clinical usefulness. METHODS: We designed a new CP for treating asthma attack according to the guideline (Japanese guideline (JGL) and Global Initiative for Asthma (GINA)). 136 patients who admitted to our hospital due to asthma attack from January 1999 to November 2006, were enrolled our study. Excluding cases complicated with pneumonia, COPD or cardiac failure, we evaluated 46 cases treated with the CP comparing with 19 cases treated without the CP. The clinical evaluations include systemic and inhaled steroid use, FEV1.0%, history of asthma, and the duration of asthma attack. Furthermore, we investigated difference between cases with and without prolonged admission. RESULTS: While the rates of systemic and inhaled steroid use in cases without the CP were 57.9% and 52.6% respectively, those in cases with the CP were approximately 100%. Employing the CP, FEV 1.0% at discharge time was elevated from 71.7% to 76.3% and the duration of hospitalization was shortened from 14.2 days to 11.5 days. Mean age of the cases with prolonged admission was higher than the rest. CONCLUSION: The asthma CP is an effective way for the standard treatment according to the guideline to be used widely even by doctors who are not familiar with asthma treatment. It improves the efficacy of in-hospital treatment.

Involvement of PEG10 in human hepatocellular carcinogenesis through interaction with SIAH1.

Through a genome-wide cDNA microarray, we identified that the paternally expressed gene 10 (PEG10) was highly expressed in a great majority of hepatocellular carcinomas, although its expression was absent in normal liver cells. Exogenous expression of PEG10 conferred oncogenic activity and transfection of hepatoma cells with antisense S-oligonucleotides suppressing PEG10 resulted in their growth inhibition. Additional experiments revealed that PEG10 protein associated with SIAH1, a mediator of apoptosis, and that overexpression of PEG10 decreased the cell death mediated by SIAH1. These findings suggested that development of drug(s) inhibiting PEG10 activity could be a novel approach for the treatment of hepatocellular carcinomas.