Transcriptional-program-based deciphering of the MET exon 14 skipping regulation network
The MET exon 14 skipping mutation (named METex14del) described in lung cancer leads to prolonged activation of signaling pathways and aberrant cell responses, but the link between HGF signaling and cell responses remains unclear. A putative regulatory network of influential regulators of target genes was constructed from the transcriptomes of lung cancer cell lines. Overlaying this reference network with transcriptomic data from METex14del-expressing cells, stimulated or not by HGF, revealed a major regulatory node consisting mainly of the transcription factors ETS1, FOSL1 and SMAD3. HGF activation of METex14del induced the phosphorylation of these master regulators and the expression of their predicted target genes in a RAS-ERK pathway-dependent manner. Furthermore, most of the transcription factors in the regulatory node are known regulators of epithelial-mesenchymal transition, consistent with their involvement in migration and invasion. New modeling with transcriptomic data from MEK inhibitor-treated METex14del cells validated the key role of RAS-ERK pathway regulators and their target genes in METex14del receptor activation. Thus, we report an original strategy to identify key transcriptional nodes associated with specific signaling pathways that may become novel therapeutic targets.