Loss of E-cadherin, a hallmark of epithelial-mesenchymal transition (EMT), can significantly affect metastatic dissemination. However, the molecular mechanism of EMT-associated metastatic dissemination by loss of E-cadherin still remains unclear in non-small cell lung cancers (NSCLCs). In the present study, we show that the knockdown of E-cadherin was sufficient to convert A549 NSCLC cells into mesenchymal type with the concurrent up-regulation of typical EMT inducers such as ZEB1 and TWIST1. Interestingly, the EMT-induced cells by E-cadherin depletion facilitate invasion in a matrix metalloproteinase-2 (MMP2)-dependent manner with aberrant activation of EGFR signaling. We demonstrated that the elevated invasiveness was a result of the activated EGFR-MEK/ERK signaling, which in turn leads to ZEB1 dependent MMP2 induction. These results suggest that the EGFR-MEK/ERK/ZEB1/MMP2 axis is responsible for promoted invasion in EMT-induced NSCLCs. Consistently, ERK activation and loss of E-cadherin were both observed in the disseminating cancer cells at the invasive tumor fronts in NSCLC cancer tissues. Thereby, these data suggest that the EGFR-MEK/ERK signaling would be a promising molecular target to control aberrant MMP2 expression and consequent invasion in the EMT-induced NSCLCs

No abstract

Chronic exposure to TGFβ, a frequent occurrence for tumor cells in the tumor microenvironment, confers more aggressive phenotypes on cancer cells by promoting their invasion and migration while at the same time increasing their resistance to the growth-inhibitory effect of TGFβ. In this study, a transdifferentiated (TD) A549 cell model, established by chronically exposing A549 cells to TGFβ, showed highly invasive phenotypes in conjunction with attenuation of Smad-dependent signaling. We show that Snail protein, the mRNA expression of which strongly correlates with a poor prognosis in lung cancer patients, was highly stable in TD cells after TGFβ stimulation. The increased protein stability of Snail in TD cells correlated with elevated inhibitory phosphorylation of GSK3β, resulting from the high Akt activity. Notably, integrin β3, whose expression was markedly increased upon sustained exposure to TGFβ, was responsible for the high Akt activity as well as the increased Snail protein stability in TD cells. Consistently, clinical database analysis on lung cancer patients revealed a negative correlation between overall survival and integrin β3 mRNA levels. Therefore, we suggest that the integrin β3-Akt-GSK3β signaling axis plays an important role in non-canonical TGFβ signaling, determining the invasive properties of tumor cells chronically exposed to TGFβ.

While metastasis, the main cause of lung cancer-related death, has been extensively studied, the underlying molecular mechanism remains unclear. A previous clinicogenomic study revealed that expression of N-acetylgalactosaminyltransferase (GalNAc-T14), is highly inversely correlated with recurrence-free survival in those with non-small cell lung cancer (NSCLC). However, the underlying molecular mechanism(s) has not been determined. Here, we showed that GalNAc-T14 expression was positively associated with the invasive phenotype. Microarray and biochemical analyses revealed that HOXB9, the expression of which was increased in a GalNAc-T14-dependent manner, played an important role in metastasis. GalNAc-T14 increased the sensitivity of the WNT response and increased the stability of the β-catenin protein, leading to induced expression of HOXB9 and acquisition of an invasive phenotype. Pharmacological inhibition of β-catenin in GalNAc-T14-expressing cancer cells suppressed HOXB9 expression and invasion. A meta-analysis of clinical genomics data revealed that expression of GalNAc-T14 or HOXB9 was strongly correlated with reduced recurrence-free survival and increased hazard risk, suggesting that targeting β-catenin within the GalNAc-T14/WNT/HOXB9 axis may be a novel therapeutic approach to inhibit metastasis in NSCLC.

Keloids are characterised by the excessive accumulation of extracellular matrix (ECM), especially overabundant collagen formation. In keloid fibroblasts (KFs), transforming growth factor (TGF)‐β‐dependent signalling is closely associated with a variety of keloid pathologic responses such as ECM production and fibroblast overgrowth. Thus, inhibition of TGF‐β signalling would be a potential therapeutic approach to prevent keloid scar formation. Thereby, we aimed to identify a novel TGF‐β signalling blocker among natural products using a simplified screening approach. We discovered that the extract of Aneilema keisak (A.K‐Ex) lowered TGF‐β‐dependent signalling by reducing Smad2 protein levels. Given that KFs showed altered dependency on TGF‐β for survival and proliferation, A.K‐Ex‐mediated reduction in Smad2 protein levels significantly inhibited the major characteristics of KFs such as cell growth, migration and collagen synthesis, suggesting that A.K‐Ex exhibits possible therapeutic activity on keloids.