MET exon 14 skipping alteration (METΔ14Ex) is an actionable oncogenic driver that occurs in 2% to 4% of non-small cell lung cancer (NSCLC) cases. The precise role of METΔ14Ex in tumor progression of NSCLC is poorly understood. Using multiple isogenic METΔ14Ex cell models established with CRISPR editing, we demonstrate that METΔ14Ex expression increases receptor kinase activity and downstream signaling by impairing receptor internalization and endocytic degradation, significantly boosting cell scatter, migration, and invasion capacity in vitro as well as metastasis in vivo. RNA sequencing analysis revealed that METΔ14Ex preferentially activates biological processes associated with cell movement, providing novel insights into its unique molecular mechanism of action. Activation of PI3K/Akt/Rac1 signaling and upregulation of multiple matrix metallopeptidases (MMP) by METΔ14Ex induced cytoskeleton remodeling and extracellular matrix disassembly, which are critical functional pathways that facilitate cell invasion and metastasis. Therapeutically, MET inhibitors dramatically repressed METΔ14Ex-mediated tumor growth and metastasis in vivo, indicating potential therapeutic options for METΔ14Ex-altered NSCLC patients. These mechanistic insights into METΔ14Ex-mediated invasion and metastasis provide a deeper understanding of the role of METΔ14Ex in NSCLC.These findings reveal the mechanistic function of METΔ14Ex alteration in driving metastasis and define novel metastasis-related pathways that could be targeted for more effective treatment of lung cancer with METΔ14Ex alterations.
The atypical bacterial pathogen Mycoplasma pneumoniae is a leading etiological agent of community-acquired pneumonia in humans; infections are often recalcitrant, recurrent and resistant to antibiotic treatment. These characteristics suggest a mechanism that facilitates long-term colonization in hosts. In an in vitro setting, M. pneumoniae forms biofilms that are unusual in that motility plays no more than a very limited role in their formation and development. Given the unusual nature of M. pneumoniae biofilms, open questions remain concerning phenotypes associated with persistence, such as what properties might favour the bacteria while minimizing host damage. M. pneumoniae also produces several cytotoxic molecules including community-acquired respiratory distress syndrome (CARDS) toxin, H2S and H2O2, but how it deploys these agents during growth is unknown. Whereas several biochemical techniques for biofilm disruption were ineffective, sonication was required for disruption of M. pneumoniae biofilms to generate individual cells for comparative studies, suggesting unusual physical properties likely related to the atypical cell envelope. Nonetheless, like for other bacteria, biofilms were less susceptible to antibiotic inhibition and complement killing than dispersed cells, with resistance increasing as the biofilms matured. CARDS toxin levels and enzymatic activities associated with H2S and H2O2 production were highest during early biofilm formation and decreased over time, suggesting attenuation of virulence in connection with chronic infection. Collectively, these findings result in a model of how M. pneumoniae biofilms contribute to both the establishment and propagation of M. pneumoniae infections, and how both biofilm towers and individual cells participate in persistence and chronic disease.
<div>Abstract<p><i>MET</i> exon 14 skipping alteration (<i>METΔ14Ex</i>) is an actionable oncogenic driver that occurs in 2% to 4% of non–small cell lung cancer (NSCLC) cases. The precise role of <i>METΔ14Ex</i> in tumor progression of NSCLC is poorly understood. Using multiple isogenic <i>METΔ14Ex</i> cell models established with CRISPR editing, we demonstrate that METΔ14Ex expression increases receptor kinase activity and downstream signaling by impairing receptor internalization and endocytic degradation, significantly boosting cell scatter, migration, and invasion capacity <i>in vitro</i> as well as metastasis <i>in vivo</i>. RNA sequencing analysis revealed that <i>METΔ14Ex</i> preferentially activates biological processes associated with cell movement, providing novel insights into its unique molecular mechanism of action. Activation of PI3K/Akt/Rac1 signaling and upregulation of multiple matrix metallopeptidases (MMP) by METΔ14Ex induced cytoskeleton remodeling and extracellular matrix disassembly, which are critical functional pathways that facilitate cell invasion and metastasis. Therapeutically, MET inhibitors dramatically repressed <i>METΔ14Ex</i>-mediated tumor growth and metastasis <i>in vivo</i>, indicating potential therapeutic options for <i>METΔ14Ex</i>-altered NSCLC patients. These mechanistic insights into <i>METΔ14Ex</i>-mediated invasion and metastasis provide a deeper understanding of the role of <i>METΔ14Ex</i> in NSCLC.</p>Significance:<p>These findings reveal the mechanistic function of <i>METΔ14Ex</i> alteration in driving metastasis and define novel metastasis-related pathways that could be targeted for more effective treatment of lung cancer with <i>METΔ14Ex</i> alterations.</p></div>
