The 41-kDa and 43-kDa mitogen-activated protein (MAP) kinases play a pivotal role in the mitogenic signal transduction pathway and are essential components of the MAP kinase cascade, which includes MAP kinase kinase (MEK) and Raf-1. As aberrant activation of signal transducing molecules such as Ras and Raf-1 has been linked with cancer, we examined whether constitutive activation of the 41-/43-kDa MAP kinases is associated with the neoplastic phenotype of 138 tumor cell lines and 102 primary tumors derived from various human organs. Constitutive activation of the MAP kinases was observed in 50 tumor cell lines (36.2%) in a rather tissue-speci®c manner: cell lines derived from pancreas, colon, lung, ovary and kidney showed especially high frequencies with a high degree of MAP kinase activation, while those derived from brain, esophagus, stomach, liver and of hematopoietic origin showed low frequencies with a limited degree of MAP kinase activation. We also detected constitutive activation of the 41-/43-kDa MAP kinases in a relatively large number of primary human tumors derived from kidney, colon and lung tissues but not from liver tissue. Many tumor cells, in which point mutations of ras genes were detected, showed constitutive activation of MAP kinases, however, there were also many exceptions to this observation. In contrast, the activation of the 41-/43-kDa MAP kinases was accompanied by the activation of Raf-1 in the majority of tumor cells and was completely associated with the activation of MEK and p90 rsk in all the tumor cells examined. These results suggest that the constitutive activation of 41-/43-kDa MAP kinases in tumor cells is not due to the disorder of MAP kinases themselves, but is due to the disorder of Raf-1, Ras, or some other signaling molecules upstream of Ras.

Adjuvant chemotherapy with uracil-tegafur improves survival among patients with completely resected pathological stage I adenocarcinoma of the lung.

Epidermal growth factor (EGF) receptor (EGFR) signalling is implicated in tumour invasion and metastasis. However, whether there are EGFR signalling pathways specifically used for tumour invasion still remains elusive. Overexpression of Arf6 and its effector, AMAP1, correlates with and is crucial for the invasive phenotypes of different breast cancer cells. Here we identify the mechanism by which Arf6 is activated to induce tumour invasion. We found that GEP100/BRAG2, a guanine nucleotide exchanging factor (GEF) for Arf6, is responsible for the invasive activity of MDA-MB-231 breast cancer cells, whereas the other ArfGEFs are not. GEP100, through its pleckstrin homology domain, bound directly to Tyr1068/1086-phosphorylated EGFR to activate Arf6. Overexpression of GEP100, together with Arf6, caused non-invasive MCF7 cells to become invasive, which was dependent on EGF stimulation. Moreover, GEP100 knockdown blocked tumour metastasis. GEP100 was expressed in 70% of primary breast ductal carcinomas, and was preferentially co-expressed with EGFR in the malignant cases. Our results indicate that GEP100 links EGFR signalling to Arf6 activation to induce invasive activities of some breast cancer cells, and hence may contribute to their metastasis and malignancy.

Identification of the molecular machinery employed in cancer invasion, but not in normal adult cells, will greatly contribute to cancer therapeutics. Here we found that an ArfGAP, AMAP1/PAG2, is expressed at high levels in highly invasive breast cancer cells, but at very low levels in noninvasive breast cancer cells and normal mammary epithelial cells. siRNA-mediated silencing of AMAP1 effectively blocked the invasive activities. AMAP1 expression in human breast primary tumors also indicated its potential correlation with malignancy. Paxillin and cortactin have been shown to colocalize at invadopodia and play a pivotal role in breast cancer invasion. We found that AMAP1 is also localized at invadopodia, and acts to bridge paxillin and cortactin. This AMAP1-mediated trimeric protein complex was detected only in invasive cancer cells, and blocking this complex formation effectively inhibited their invasive activities in vitro and metastasis in mice. Our results indicate that AMAP1 is a component involved in invasive activities of different breast cancers, and provide new information regarding the possible therapeutic targets for prevention of breast cancer invasion and metastasis.

Thioredoxin‐2 (Trx‐2) is a mitochondria‐specific member of the thioredoxin superfamily. Mitochondria have a crucial role in the signal transduction for apoptosis. To investigate the biological significance of Trx‐2, we cloned chicken TRX‐2 cDNA and generated clones of the conditional Trx‐2‐deficient cells using chicken B‐cell line, DT40. Here we show that TRX‐2 is an essential gene and that Trx‐2‐deficient cells undergo apoptosis upon repression of the TRX‐2 transgene, showing an accumulation of intracellular reactive oxygen species (ROS). Cytochrome c is released from mitochondria, while caspase‐9 and caspase‐3, but not caspase‐8, are activated upon inhibition of the TRX‐2 transgene. In addition, Trx‐2 and cytochrome c are co‐immunoprecipitated in an in vitro assay. These results suggest that mitochondrial Trx‐2 is essential for cell viability, playing a crucial role in the scavenging ROS in mitochondria and regulating the mitochondrial apoptosis signaling pathway.

Our study indicates that 18F-FDG uptake in lung cancer correlates well with the Glut-1, HK-II, and PCNA expression. For nonmalignant lesions, the presence of a higher inflammatory process correlated with 18F-FDG uptake.

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This meta-analysis showed that postoperative adjuvant chemotherapy with UFT was associated with improved 5- and 7-year survival in a Japanese patient population composed primarily of stage I adenocarcinoma patients.