Comparison of epidermal growth factor receptor mutations between primary and corresponding metastatic tumors in tyrosine kinase inhibitor-naive non-small-cell lung cancer.

BACKGROUND: Mutations of the epidermal growth factor receptor (EGFR) gene in non-small-cell lung cancer (NSCLC) patients predict the patients who will respond to EGFR tyrosine kinase inhibitor (TKI) treatment. A recent study has suggested that 33% of NSCLC showed primary tumor/metastasis discordance of EGFR expression by immunohistochemistry analysis. We intended to find out whether the EGFR mutations of primary lung cancers are concordant to that of corresponding metastatic tumors. MATERIALS AND METHODS: We analyzed EGFR exons 18-21 from paired primary and metastatic tumors in 67 lung cancer patients who had not received TKI before tissues were sampled. RESULTS: Using the direct sequencing method, 9 of 18 (50%) patients with EGFR mutation-positive primary lung tumors had lost the mutations in metastases. For 26 patients who were EGFR mutation positive in the metastatic tumors, 17 (65%) were negative in the primary tumors. We analyzed these paired tissues with discrepant EGFR mutations by the Scorpion Amplified Refractory Mutation System assay. Finally, the discordant rate reached 27% (18 of 67 cases). CONCLUSION: EGFR mutations in primary lung tumors do not always reflect the same situation in metastases. Analysis of EGFR mutations in the primary lung tumor would be inadequate for planning the use of TKI for advanced NSCLC.

Frequent epidermal growth factor receptor gene mutations in malignant pleural effusion of lung adenocarcinoma.

Malignant pleural effusions (MPEs) are often observed in lung cancer, especially adenocarcinoma. Epidermal growth factor receptor (EGFR) gene mutations are usually detected in lung adenocarcinoma. The purpose of the present study was to investigate the EGFR mutation rate in MPEs of lung adenocarcinoma. Between June 2005 and December 2006, 136 MPEs from lung adenocarcinoma were collected for EGFR mutation detection. In addition, between April 2001 and November 2004, 91 surgically resected specimens of lung adenocarcinoma from patients without MPEs were assessed for EGFR mutation. The EGFR mutation rate was significantly higher in the patients with MPEs than in the patients without (68.4% versus 50.5%). The EGFR mutation rate in patients with MPEs was not associated with sex, smoking history, age or cancer stage. By multivariate analysis, an age of <65 yrs, never smoking, Eastern Cooperative Oncology Group performance status 0-1, and EGFR mutation were significantly associated with a longer overall survival for lung adenocarcinoma patients with MPEs. The patients with malignant pleural effusions related to lung adenocarcinoma had a higher epidermal growth factor receptor gene mutation rate than the patients from whom surgically resected specimens were taken. Epidermal growth factor receptor tyrosine kinase inhibitors may be the treatment of choice for lung adenocarcinoma with malignant pleural effusions in east Asia.

Cell Specific Matrix Metalloproteinase-1 Regulates Lung Metastasis Synergistically with Smoke Exposure.

MMP1, a matrix metalloproteinase that degrades the extracellular matrix, is produced not only by cancer cells but also synthesized in stromal and inflammatory cells during tumorigenesis, invasion and lung metastasis. However, the function of MMP1 expression from host cells, especially tumor-associated macrophages (TAMs), and cells in the lung parenchyma remains to be elucidated. Here we demonstrate that in vitro macrophages co-cultured with tumor cells drastically enhance MMP1 expression, which is further exacerbated upon cigarette smoke exposure. In addition, in vivo, macrophage specific MMP1 was found to have a causative role in primary tumor development and lung metastasis, which was enhanced under smoke exposure as demonstrated in a transgenic mouse model that expressed human MMP1 specifically in macrophages (Mac-MMP1). In contrast, MMP1 from lung cells (Lung-MMP1) reduced colonization to the lung despite the fact that collagen deposition decreased in the Lung-MMP1 mouse tumors. These results demonstrate that the varying cellular source of MMP1 in tumors leads to the complexity observed in the tumor microenvironment. Furthermore, macrophage-specific inhibition of MMP1 secretion may be a potential therapy to aid in the reduction of lung metastasis.

Analysis of the Drosophila gene for the laminin B1 chain.

We have isolated and sequenced a Drosophila genomic DNA that encodes the entire coding region of the laminin B1 chain. The genomic DNA sequenced spans 11,787 bp, including a 1.1-kb 5'-flanking region, 5 exons, 4 introns, and a 1.4-kb 3'-flanking region. The open reading frame is within the two largest exons, the exons 3 and 4, while the first two and the last exons are much smaller and are untranslated. The structure of the Drosophila laminin B1 gene is similar to the Drosophila laminin B2 gene. Their exon-intron lengths and Eco RI, Pst I restriction maps are quite conserved. Both of their open reading frames are very compact, and their first introns are much larger than all of the rest of the introns. These results are consistent with the suggestion that the B1 and B2 genes could be derived from an ancestral gene. The similarity of the proximal 5'-flanking regions of the Drosophila B1 and B2 genes is 46.6%. Also, similar sequences of transcriptional regulatory elements, even though not site conserved, are found in both proximal 5'-flanking regions of the B1 and B2 genes. When transfected into Drosophila SL-2 cells, pCAT plasmid containing 1,048 bp of 5'-flanking region shows a strong expression of chloramphenicol acetyltransferase (CAT) activity. The deletion clones that contain sequences between nucleotides -462 to +150, and -282 to +150 all show strong CAT activity. These results suggest that this 5'-flanking promoter region may contain DNA sequences that can promote the expression of the laminin B1 gene.