Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that is activated in response to growth factors and cytokines, and which contributes to the regulation of cell proliferation, apoptosis, and motility in many human tumour types.

MET is a receptor tyrosine kinase (RTK) whose gene is amplified in various tumour types. We investigated the roles and mechanisms of RTK heterodimerisation in lung cancer with MET amplification.

The expression and activity of the epidermal growth factor receptor (EGFR) are determinants of radiosensitivity in several tumour types, including non-small cell lung cancer (NSCLC). However, little is known of whether genetic alterations of EGFR in NSCLC cells affect the therapeutic response to monoclonal antibodies (mAbs) to EGFR in combination with radiation. We examined the effects of nimotuzumab, a humanised mAb to EGFR, in combination with ionising radiation on human NSCLC cell lines of differing EGFR status. Flow cytometry revealed that H292 and Ma-1 cells expressed high and moderate levels of EGFR on the cell surface, respectively, whereas H460, H1299, and H1975 cells showed a low level of surface EGFR expression. Immunoblot analysis revealed that EGFR phosphorylation was inhibited by nimotuzumab in H292 and Ma-1 cells but not in H460, H1299, or H1975 cells. Nimotuzumab augmented the cytotoxic effect of radiation in H292 and Ma-1 cells in a clonogenic assay in vitro, with a dose enhancement factor of 1.5 and 1.3, respectively. It also enhanced the antitumor effect of radiation on H292 and Ma-1 cell xenografts in nude mice, with an enhancement factor of 1.3 and 4.0, respectively. Nimotuzumab did not affect the radioresponse of H460 cells in vitro or in vivo. Nimotuzumab enhanced the antitumor efficacy of radiation in certain human NSCLC cell lines in vitro and in vivo. This effect may be related to the level of EGFR expression on the cell surface rather than to EGFR mutation.

Survivin, a member of the inhibitor of apoptosis protein family, is an attractive target for cancer therapy. We have now investigated the effects of the combination of YM155, a novel small-molecule inhibitor of survivin expression, and platinum compounds (cisplatin and carboplatin) on human non-small cell lung cancer (NSCLC) cell lines.

The purpose of this study was to evaluate the efficacy of gefitinib and the feasibility of screening for epidermal growth factor receptor (EGFR) mutations among select patients with advanced non-small cell lung cancer (NSCLC). Stage IIIB/IV NSCLC, chemotherapy-naive patients or patients with recurrences after up to two prior chemotherapy regimens were eligible. Direct sequencing using DNA from tumour specimens was performed by a central laboratory to detect EGFR mutations. Patients harbouring EGFR mutations received gefitinib. The primary study objective was response; the secondary objectives were toxicity, overall survival (OS), progression-free survival (PFS), 1-year survival (1Y-S) and the disease control rate (DCR). Between March 2005 and January 2006, 118 patients were recruited from 15 institutions and were screened for EGFR mutations, which were detected in 32 patients--28 of whom were enrolled in the present study. The overall response rate was 75%, the DCR was 96% and the median PFS was 11.5 months. The median OS has not yet been reached, and the 1Y-S was 79%. Thus, gefitinib chemotherapy in patients with advanced NSCLC harbouring EGFR mutations was highly effective. This trial documents the feasibility of performing a multicentre phase II study using a central typing laboratory, demonstrating the benefit to patients of selecting gefitinib treatment based on their EGFR mutation status.

Activin A is a multi-functional cytokine belonging to the transforming growth factor-β (TGF-β) superfamily; however, the effect of activin A on angiogenesis remains largely unclear. We found that inhibin β A subunit (INHBA) mRNA is overexpressed in gastric cancer (GC) specimens and investigated the effect of activin A, a homodimer of INHBA, on angiogenesis in GC.

TZT-1027 is a novel anticancer agent that inhibits microtubule polymerisation and manifests potent antitumour activity in preclinical models. We have examined the effect of TZT-1027 on cell cycle progression as well as the anticancer activity of this drug both in vitro and in vivo. With the use of tsFT210 cells, which express a temperature-sensitive mutant of Cdc2, we found that TZT-1027 arrests cell cycle progression in mitosis, the phase of the cell cycle most sensitive to radiation. A clonogenic assay indeed revealed that TZT-1027 increased the sensitivity of H460 cells to gamma-radiation, with a dose enhancement factor of 1.2. Furthermore, TZT-1027 increased the radiosensitivity of H460 and A549 cells in nude mice, as revealed by a marked delay in tumour growth and an enhancement factor of 3.0 and 2.2, respectively. TZT-1027 also potentiated the induction of apoptosis in H460 cells by radiation both in vitro and in vivo. Histological evaluation of H460 tumours revealed that TZT-1027 induced morphological damage to the vascular endothelium followed by extensive central tumour necrosis. Our results thus suggest that TZT-1027 enhances the antitumour effect of ionising radiation, and that this action is attributable in part to potentiation of apoptosis induction and to an antivascular effect. Combined treatment with TZT-1027 and radiation therefore warrants investigation in clinical trials as a potential anticancer strategy.

Thymidylate synthase (TS), a key enzyme in the de novo synthesis of thymidine, is an important chemotherapeutic target for malignant tumours including lung cancer. Although inhibition of TS has an antiproliferative effect in cancer cells, the precise mechanism of this effect has remained unclear.

Somatic mutations of LKB1 tumour suppressor gene have been detected in human cancers including non-small cell lung cancer (NSCLC). The relationship between LKB1 mutations and clinicopathological characteristics and other common oncogene mutations in NSCLC is inadequately described. In this study we evaluated tumour specimens from 310 patients with NSCLC including those with adenocarcinoma, adenosquamous carcinoma, and squamous cell carcinoma histologies. Tumours were obtained from patients of US (n=143) and Korean (n=167) origin and screened for LKB1, KRAS, BRAF, and EGFR mutations using RT-PCR-based SURVEYOR-WAVE method followed by Sanger sequencing. We detected mutations in the LKB1 gene in 34 tumours (11%). LKB1 mutation frequency was higher in NSCLC tumours of US origin (17%) compared with 5% in NSCLCs of Korean origin (P=0.001). They tended to occur more commonly in adenocarcinomas (13%) than in squamous cell carcinomas (5%) (P=0.066). LKB1 mutations associated with smoking history (P=0.007) and KRAS mutations (P=0.042) were almost mutually exclusive with EGFR mutations (P=0.002). The outcome of stages I and II NSCLC patients treated with surgery alone did not significantly differ based on LKB1 mutation status. Our study provides clinical and molecular characteristics of NSCLC, which harbour LKB1 mutations.

Animal cells divide into two daughter cells by the formation of an actomyosin-based contractile ring through a process called cytokinesis. Although many of the structural elements of cytokinesis have been identified, little is known about the signaling pathways and molecular mechanisms underlying this process. Here we show that the human ECT2 is involved in the regulation of cytokinesis. ECT2 catalyzes guanine nucleotide exchange on the small GTPases, RhoA, Rac1, and Cdc42. ECT2 is phosphorylated during G2 and M phases, and phosphorylation is required for its exchange activity. Unlike other known guanine nucleotide exchange factors for Rho GTPases, ECT2 exhibits nuclear localization in interphase, spreads throughout the cytoplasm in prometaphase, and is condensed in the midbody during cytokinesis. Expression of an ECT2 derivative, containing the NH(2)-terminal domain required for the midbody localization but lacking the COOH-terminal catalytic domain, strongly inhibits cytokinesis. Moreover, microinjection of affinity-purified anti-ECT2 antibody into interphase cells also inhibits cytokinesis. These results suggest that ECT2 is an important link between the cell cycle machinery and Rho signaling pathways involved in the regulation of cell division.

Although most non-small-cell lung cancer (NSCLC) patients with the echinoderm microtubule-associated protein-like 4 (EML4) - anaplastic lymphoma kinase (ALK) fusion gene - benefit from ALK tyrosine kinase inhibitors (ALK-TKIs), the efficacy of these drugs varies greatly among individuals.

Although a high level of thymidylate synthase (TS) expression in malignant tumours has been suggested to be related to a reduced sensitivity to the antifolate drug pemetrexed, no direct evidence for such an association has been demonstrated in non-small cell lung cancer (NSCLC). We have now investigated the effect of TS overexpression on pemetrexed sensitivity in NSCLC cells.

CD44 is a widely distributed cell surface adhesion molecule and is implicated in diverse biological processes. However, the nature of intracellular signaling triggered by CD44 remains to be elucidated. Here, we show that CD44 undergoes sequential proteolytic cleavage in the ectodomain and intracellular domain, resulting in the release of a CD44 intracellular domain (ICD) fragment. Consequently, CD44ICD acts as a signal transduction molecule, where it translocates to the nucleus and activates transcription mediated through the 12-O-tetradecanoylphorbol 13-acetate-responsive element, which is found in numerous genes involved in diverse cellular processes. Expression of an uncleavable CD44 mutant as well as metalloprotease inhibitor treatment blocks CD44-mediated transcriptional activation. In search of the underlying mechanism, we have found that CD44ICD potentiates transactivation mediated by the transcriptional coactivator CBP/p300. Furthermore, we show that cells expressing CD44ICD produce high levels of CD44 messenger RNA, suggesting that the CD44 gene is one of the potential targets for transcriptional activation by CD44ICD. These observations establish a novel CD44 signaling pathway and shed new light on the functional link between proteolytic processing of an adhesion molecule at the cell surface and transcriptional activation in the nucleus.