We have recently identified a tumor suppressor gene TSLC1 on chromosome 11q23.2 by functional complementation of a human lung cancer cell line, A549, through suppression of tumorigenicity in nude mice (1). Furthermore, we have demonstrated the two-hit inactivation of TSLC1 in primary non-small cell lung cancer, hepatocellular carcinoma, and pancreatic cancer, implying its involvement in various human cancers (1). TSLC1 encodes a member of the immunoglobulin superfamily proteins comprising three Ig-like C2-type domains, a single hydrophobic membrane-spanning ␣-helix, and a cytoplasmic domain containing a putative signaling motif (1). From the significant homology of its extracellular domain with those of NCAM1 and NCAM2, 1 we have inferred that TSLC1 is capable of mediating cell-cell interaction.Cell adhesion molecules generally fall into four major classes: the cadherins, the integrins, the selectins, and the Ig superfamily. Among them, Ig superfamily cell adhesion molecules (IgCAMs) are the largest, numbering well over 100 members in vertebrates (2). These well-characterized molecules include NCAMs (3), L1 family CAMs (4), and nectins (5-8). Whereas cadherins and integrins require divalent cations such as Ca 2ϩ or Mg 2ϩ for their adhesive activities (9), IgCAMs are usually Ca 2ϩ -or Mg 2ϩ -independent (10). Moreover, most IgCAMs have preferences for homophilic and/or heterophilic interactions (10). In combination with these interactions, IgCAMs promote a variety of cell-cell associations through cis interaction within the plane of the membranes and/or trans interaction across the membranes (2, 11). For instance, the heterophilic cis interaction between L1 and NCAM appears to enhance the homophilic trans-binding activity of L1 (12, 13). Nectins form cis-homodimers that undergo homophilic and heterophilic trans interactions with each other to mediate cell-cell adhesion (6,11).In this study, the biochemical properties and subcellular localization of TSLC1 were investigated in the cells expressing TSLC1 tagged with GFP or endogenous TSLC1. We report the physiological properties of TSLC1 along with several lines of evidence that TSLC1 is a single transmembrane glycoprotein involved in cell-cell aggregation through homophilic trans interaction.

Canonical Wnt/β-catenin signalling is essential for maintaining intestinal stem cells, and its constitutive activation has been implicated in colorectal carcinogenesis. We and others have previously identified Traf2- and Nck-interacting kinase (TNIK) as an essential regulatory component of the T-cell factor-4 and β-catenin transcriptional complex. Consistent with this, Tnik-deficient mice are resistant to azoxymethane-induced colon tumorigenesis, and Tnik−/−/Apcmin/+ mutant mice develop significantly fewer intestinal tumours. Here we report the first orally available small-molecule TNIK inhibitor, NCB-0846, having anti-Wnt activity. X-ray co-crystal structure analysis reveals that NCB-0846 binds to TNIK in an inactive conformation, and this binding mode seems to be essential for Wnt inhibition. NCB-0846 suppresses Wnt-driven intestinal tumorigenesis in Apcmin/+ mice and the sphere- and tumour-forming activities of colorectal cancer cells. TNIK is required for the tumour-initiating function of colorectal cancer stem cells. Its inhibition is a promising therapeutic approach.

Pulmonary metastasis is the most significant prognostic determinant for osteosarcoma, but methods for its prediction and treatment have not been established. Using oligonucleotide microarrays, we compared the global gene expression of biopsy samples between seven osteosarcoma patients who developed pulmonary metastasis within 4 years after neoadjuvant chemotherapy and curative resection, and 12 patients who did not relapse. We identified argininosuccinate synthetase (ASS) as a gene differentially expressed with the highest statistical significance (Welch's t test, P = 2.2 × 10 −5). Immunohistochemical analysis of an independent cohort of 62 osteosarcoma cases confirmed that reduced expression of ASS protein was significantly correlated with the development of pulmonary metastasis after surgery (log-rank test, P < 0.05). Cox regression analysis revealed that ASS was the sole significant predictive factor (P = 0.039; hazard ratio, 0.319; 95% confidence interval, 0.108-0.945). ASS is one of the enzymes required for the production of a nonessential amino acid, arginine. We showed that osteosarcoma cells lacking ASS expression were auxotrophic for arginine and underwent G 0 -G 1 arrest in arginine-free medium, suggesting that an arginine deprivation therapy could be effective in patients with osteosarcoma. Recently, phase I and II clinical trials in patients with melanoma and hepatocellular carcinoma have shown the safety and efficacy of plasma arginine depletion by stabilized arginine deiminase. Our data indicate that in patients with osteosarcoma, reduced expression of ASS is not only a novel predictive biomarker for the development of metastasis, but also a potential target for pharmacologic intervention. Mol Cancer Ther; 9(3); 535-44. ©2010 AACR.

◥Extracellular vesicles (EV) from cancer-associated fibroblasts (CAF) are composed of diverse payloads. Although CAFs impact the aggressive characteristics of gastric cancer cells, the contribution of CAF-EV to gastric cancer progression has not been elucidated. Here, we investigated the molecular mechanism of the changes in gastric cancer characteristics induced by CAF-EV. CAF abundance in gastric cancer tissues was associated with poor prognosis of patients with gastric cancer receiving chemotherapy. Moreover, CAF-EV induced tubular network formation and drug resistance of gastric cancer cells in the extracellular matrix (ECM). Comprehensive proteomic analysis of CAF-EV identified that Annexin A6 plays a pivotal role in network formation and drug resistance of gastric cancer cells in the ECM via activation of b1 integrin-focal adhesion kinase (FAK)-YAP. A peritoneal metastasis mouse model revealed that CAF-EV induced drug resistance in peritoneal tumors, and inhibition of FAK or YAP efficiently attenuated gastric cancer drug resistance in vitro and in vivo. These findings demonstrate that drug resistance is conferred by Annexin A6 in CAF-EV and provide a potential avenue for overcoming gastric cancer drug resistance through the inhibition of FAK-YAP signaling in combination with conventional chemotherapeutics.Significance: This study elucidates a novel molecular mechanism through which Annexin A6 in CAF-EV activates FAK-YAP by stabilizing b1 integrin at the cell surface of gastric cancer cells and subsequently induces drug resistance.