PTEN inactivation in lung cancer cells and the effect of its recovery on treatment with epidermal growth factor receptor tyrosine kinase inhibitors.

To understand the mechanisms of PTEN inactivation, which is reported to be involved in tumor progression and drug resistance in lung cancer, we analyzed the expression levels of PTEN at mRNA and protein levels, along with the genetic and epigenetic status of the PTEN gene, in a panel of lung cancer cell lines. Western blot analysis showed that six out of 25 (24%) cell lines displayed low expression of PTEN protein. The level of PTEN mRNA correlated well with corresponding protein expression in each of these six cell lines. In two of the six cell lines genomic analysis revealed homozygous deletions of the PTEN gene. Another two of the six cell lines displayed hypermethylation of the PTEN gene promoter assessed by methylation-specific PCR. The levels of PTEN mRNA and protein expression in PC9/f9 and PC9/f14 cells, which are gefitinib-resistant derivatives of the gefitinib-sensitive cell line, PC9, were reduced compared to the parental line. After treatment with the demethylating agent 5-aza-2'deoxycytidine (5-AZA) and the histone deacetyltransferase (HDAC) inhibitor Trichostatin A (TSA), the expression levels of PTEN mRNA and protein in these four cell lines (PC9/f9, PC9/f14, PC10 and PC14) were actually restored. In summary, reduction in PTEN protein expression was regulated by histone deacetylation and hypermethylation of the gene promoter, as well as homozygous deletion. In addition, we demonstrated that the combination treatment of gefitinib and TSA induced significant growth inhibition in gefitinib-resistant PC9/f9 and PC9/f14 cells. These findings suggest that the combination of the epidermal growth factor receptor tyrosine kinase inhibitor gefitinib with the demethylating agent 5-AZA and the HDAC inhibitor TSA may be a useful strategy for the treatment of some lung cancers.

Gefitinib (IRESSA) sensitive lung cancer cell lines show phosphorylation of Akt without ligand stimulation.

BACKGROUND: Phase III trials evaluating the efficacy of gefitinib (IRESSA) in non-small cell lung cancer (NSCLC) lend support to the need for improved patient selection in terms of gefitinib use. Mutation of the epidermal growth factor receptor (EGFR) gene is reported to be associated with clinical responsiveness to gefitinib. However, gefitinib-sensitive and prolonged stable-disease-defined tumors without EGFR gene mutation have also been reported. METHODS: To identify other key factors involved in gefitinib sensitivity, we analyzed the protein expression of molecules within the EGFR family, PI3K-Akt and Ras/MEK/Erk pathways and examined the sensitivity to gefitinib using the MTT cell proliferation assay in 23 lung cancer cell lines. RESULTS: We identified one highly sensitive cell line (PC9), eight cell lines displaying intermediate-sensitivity, and 14 resistant cell lines. Only PC9 and PC14 (intermediate-sensitivity) displayed an EGFR gene mutation including amplification. Eight out of the nine cell lines showing sensitivity had Akt phosphorylation without ligand stimulation, while only three out of the 14 resistant lines displayed this characteristic (P = 0.0059). Furthermore, the ratio of phosphor-Akt/total Akt in sensitive cells was higher than that observed in resistant cells (P = 0.0016). Akt phosphorylation was partially inhibited by gefitinib in all sensitive cell lines. CONCLUSION: These results suggest that Akt phosphorylation without ligand stimulation may play a key signaling role in gefitinib sensitivity, especially intermediate-sensitivity. In addition, expression analyses of the EGFR family, EGFR gene mutation, and FISH (fluorescence in situ hybridization) analyses showed that the phosphorylated state of EGFR and Akt might be a useful clinical marker of Akt activation without ligand stimulation, in addition to EGFR gene mutation and amplification, particularly in adenocarcinomas.

Phase I/II study of paclitaxel + carboplatin for refractory or recurrent non-small cell lung cancer.

A gene-drug correlation analysis was previously performed in lung cancer cell lines using the NC160 program. On the basis of this work, a phase I/II pilot study of weekly paclitaxel and carboplatin (CBDCA) was subsequently planned for refractory or recurrent non-small cell lung cancer (NSCLC). Safety and antitumor effects were evaluable in all 30 patients registered for this study. Seven patients were stage IIIB and 23 were stage IV. At level 5 (paclitaxel 100 mg/m2 and CBDCA AUCS), toxicities were not dose-limiting factors, but three out of the initial six cases had infusion skips. Our recommended dose was paclitaxel 100 mg/m2 and CBDCA AUC5. The response rate was 50% (9/18)(95% CI: 27-73%) in step 5. The median survival time was 12 months. This combination showed a promising clinical activity with mild toxicity and should be selected for the investigational arm of phase III trials to be compared with either docetaxel or pemetrexed.

Alterations in novel candidate tumor suppressor genes, ING1 and ING2 in human lung cancer.

The ING1 gene is involved in the regulation of the cell cycle, senescence, and apoptosis and is a novel candidate tumor suppressor gene. ING2, another gene in the ING family, was identified and cloned. The functions of ING1 and ING2 largely depend on the activity of p53. To determine whether an alteration in these genes plays a role in carcinogenesis and tumor progression in lung cancer, we screened 30 human lung cancer cell lines and 31 primary lung cancer tumors for mutations in these genes using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and direct sequencing. Our findings failed to uncover any mutations in these genes. We also examined the expression of ING1 and ING2 in lung cancer cell lines that either had or lacked a p53 mutation, and in a control bronchial epithelium cell line, using quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR). ING1 expression was up-regulated in all 7 lung cancer cell lines that had a p53 mutation, while the expression of ING2 was down-regulated in 6 of 7 lung cancer cell lines that had a p53 mutation. These results suggest that the ING1 and ING2 genes have different roles in lung carcinogenesis and progression, and the ING2 gene may be an independent tumor suppressor candidate on p53.

Influence of daily low-dose 14-membered-ring macrolide therapy on Helicobacter pylori infection in patients with chronic inflammatory disease of the airway.

Our aim was to evaluate the effects of eradication and the incidence of secondary resistance by long-term low-dose daily 14-membered-ring macrolide therapy on Helicobacter pylori ( H. pylori) infection in patients with chronic lower respiratory tract inflammatory disease. In a retrospective analysis, we studied the seroprevalence of H. pylori IgG in 90 patients with inflammation of the lower respiratory tract (68 had been treated with macrolide and 22 served as controls). Then, in a prospective analysis, we evaluated the eradication effect of macrolide therapy by the decline of IgG values and the (13)C-urea breath test. Only long-term macrolide use significantly affected the seroprevalence of H. pylori IgG. However, macrolide therapy did not reduce the H. pylori IgG values in 24 patients and did not eradicate H. pylori in (13)C-urea breath tests. Chemosensitivity testing was performed on three H. pylori strains obtained by gastric biopsy from patients in whom the disease could not be eradicated. Only one strain demonstrated a resistant character. Daily long-term low-dose 14-membered-ring macrolide therapy for patients with lower respiratory inflammatory disease may not be sufficient to eradicate H. pylori, but some strains do not acquire a resistant nature.

Mutational analysis of the macrophage scavenger receptor 1 (MSR1) gene in primary lung cancer.

Allelic deletion at chromosome 8p21-25 is an early and frequent event in the carcinogenesis and development of various cancers. To facilitate investigation of alterations of the macrophage scavenger receptor 1 (MSR1), which is located on 8p22, and to determine the role of this gene in human carcinogenesis and tumor progression, we determined intronic primers designed to amplify the coding region. Since frequent deletion of 8p21-23 has been previously reported in lung cancer, we searched for mutations throughout the coding sequence of the MSR1 gene within a panel of genomic DNA samples obtained from 30 primary lung cancers. Our approach, which involved polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and direct DNA sequencing, revealed nucleotide variants of the MSR1 gene in only one of the 30 cases examined, with this sample displaying both a 6 bp deletion and a thymine-to-cytosine substitution, the latter occurring within intron 7. The 6 bp deletion was located at a DNA microsatellite region and the thymine-to-cytosine substitution seemed to be a polymorphism. These results suggest that the MSR1 gene is not commonly mutated in lung cancer and not important in susceptibility to lung cancer. Further studies may focus on alternative mechanisms through which the MSR1 gene might be inactivated, such as aberrant DNA methylation, and/or pursue analyses of other genes on 8p21-23 for mutational events. Nevertheless, the panel of intronic PCR primer pair sequences presented here will facilitate future studies to determine the full spectrum and frequency of genetic events that may affect expression/activity of the MSR1 gene in human tumors.

A novel matrix metalloproteinase inhibitor, FYK-1388 suppresses tumor growth, metastasis and angiogenesis by human fibrosarcoma cell line.

The matrix metalloproteinases (MMPs) are likely to contribute to tumor cell invasion, metastasis and angiogenesis. Several MMP inhibitors have been developed, recently and their anti-tumor efficacy is being evaluated in clinical trials. FYK-1388 is a novel broad MMP inhibitor which blocks the activity of MMP-1, -2, -3, -7, -9, -13 and -14 (MT-MMP-1). It is especially effective against MMP-2 and -9 more so than other MMP inhibitors such as Marimastat, Ro 32-3555 and D-2163. Here, we investigated the anti-tumor efficacy of FYK-1388 using the human fibrosarcoma cell line HT-1080. These cells produced MMP-2 and -9, which FYK-1388 inhibited at a dose of 10(-8) M. FYK-1388 at 0.2 mg/mouse/day significantly suppressed tumor growth when given by s.c. injection for 22 days, experimental lung metastasis after 5 days s.c. injection and also suppressed tumor-induced angiogenesis in the dorsal air sac assay after 7 days s.c. injection. In the MTT assay, FYK-1388 had no effect on the in vitro growth of HT-1080 cells. These results suggest that FYK-1388 possesses anti-tumor efficacy as a result of inhibiting angiogenesis through the suppression of MMP-2 and -9 activity.

[The frequency profiles of size of two-step tuberculin skin tests with histories of BCG vaccinations and tuberculin tests among hospital employees].

In 1998, Prevention Committee of the Japanese Society for Tuberculosis announced guidelines for dealing with nosocomial tuberculosis infections. These guidelines recommended the two-step tuberculin tests (TST) as baseline data for each medical employee when they started to work. If accurate records of previous TSTs are available in addition to baseline data, they are useful to evaluate the presence of tuberculosis infection when they started to work. We therefore studied the frequency profile of size of TST among medical employees in INBA-HITEC Medical Center and discussed methods to improve investigative measures for tuberculosis infection, and prior to skin testing we asked self-reporting questionnaires regarding history of previous BCG vaccinations and TSTs. We expected that their records of previous TSTs were accurately preserved, however, records of previous TSTs reported by medical employees were found to be inaccurate. From two-step TSTs results, the magnitude of booster phenomenon was defined by diameter of erythema and induration. Results demonstrated that the increase of induration size was larger in subjects > or = 41-years-old than in subjects < 41-years-old. Regarding booster phenomenon, no statistically significant differences were detected according to type of duty post. Many subjects with size of TST erythema > or = 30 mm on the first test showed increase erythema > or = 10 mm on the second test. We therefore suggest that the second test be made for those showing reaction size > or = 30 mm on the first test.