Inactivation of the tumor suppressor gene RASSF1A by promoter hypermethylation represents a key event underlying the initiation and progression of lung cancer. RASSF1A inactivation is also associated with poor prognosis and may promote metastatic spread. In this study, we investigated how RASSF1A inactivation conferred invasive phenotypes to human bronchial cells. RNAi-mediated silencing of RASSF1A induced epithelialto-mesenchymal transition (EMT), fomenting a motile and invasive cellular phenotype in vitro and increased metastatic prowess in vivo. Mechanistic investigations revealed that RASSF1A blocked tumor growth by stimulating cofilin/PP2A-mediated dephosphorylation of the guanine nucleotide exchange factor GEF-H1, thereby stimulating its ability to activate the antimetastatic small GTPase RhoB. Furthermore, RASSF1A reduced nuclear accumulation of the Hippo pathway transcriptional cofactor Yes-associated protein (YAP), which was reinforced by RhoB activation. Collectively, our results indicated that RASSF1 acts to restrict EMT and invasion by indirectly controlling YAP nuclear shuttling and activation through a RhoB-regulated cytoskeletal remodeling process, with potential implications to delay the progression of RASSF1-hypermethylated lung tumors. Cancer Res; 76(6);

Histamine release and mast cell triggering are related to severe reactions. An IgE-related mechanism is strongly suspected. Radiologists should be trained to identify and treat anaphylactic shock in patients who react to iodinated contrast material.

We assessed the prognostic and predictive value of b-tubulin III (TUBB3) expression, as determined by immunohistochemistry, in 412 non-small cell lung cancer (NSCLC) specimens from early-stage patients who received neoadjuvant chemotherapy (paclitaxel-or gemcitabine-based) in a phase III trial (IFCT-0002). We also correlated TUBB3 expression with K-Ras and EGF receptor (EGFR) mutations in a subset of 208 cryopreserved specimens. High TUBB3 protein expression was associated with nonsquamous cell carcinomas (P < 0.001) and K-Ras mutation (P < 0.001). The 127 (30.8%) TUBB3-negative patients derived more than 1 year of overall survival advantage, with more than 84 months median overall survival versus 71.7 months for TUBB3-positive patients [HR, 1.58; 95% confidence interval (CI), 1.11-2.25)]. This prognostic value was confirmed in multivariate analysis (adjusted HR for death, 1.51; 95% CI, 1.04-2.21; P ¼ 0.031) with a bootstrapping validation procedure. TUBB3 expression was associated with nonresponse to chemotherapy (adjusted HR, 1.31; 95% CI, 1.01-1.70; P ¼ 0.044) but had no predictive value (taxane vs. gemcitabine). Taking account of these clinical findings, we further investigated TUBB3 expression in isogenic human bronchial cell lines only differing by K-Ras gene status and assessed the effect of K-Ras short interfering RNA (siRNA) mediated depletion, cell hypoxia, or pharmacologic inhibitors of K-Ras downstream effectors, on TUBB3 protein cell content. siRNA K-Ras knockdown, inhibition of RAF/MEK (MAP-ERK kinase) and phosphoinositide 3-kinase (PI3K)/AKT signaling, and hypoxia were shown to downregulate TUBB3 expression in bronchial cells. This study is the first one to identify K-Ras mutations as determinant of TUBB3 expression, a chemoresistance marker. Our in vitro data deserve studies combining standard chemotherapy with anti-MEK or anti-PI3K drugs in patients with TUBB3-overexpressing tumors.