RESUMO
TWIST1, an epithelial-mesenchymal transition (EMT) transcription factor, is critical for oncogene-driven non-small cell lung cancer (NSCLC) tumorigenesis. Given the potential of TWIST1 as a therapeutic target, a chemical-bioinformatic approach using connectivity mapping (CMAP) analysis was used to identify TWIST1 inhibitors. Characterization of the top ranked candidates from the unbiased screen revealed that harmine, a harmala alkaloid, inhibited multiple TWIST1 functions, including single-cell dissemination, suppression of normal branching in 3D epithelial culture, and proliferation of oncogene driver-defined NSCLC cells. Harmine treatment phenocopied genetic loss of TWIST1 by inducing oncogene-induced senescence or apoptosis. Mechanistic investigation revealed that harmine targeted the TWIST1 pathway through its promotion of TWIST1 protein degradation. As dimerization is critical for TWIST1 function and stability, the effect of harmine on specific TWIST1 dimers was examined. TWIST1 and its dimer partners, the E2A proteins, which were found to be required for TWIST1-mediated functions, regulated the stability of the other heterodimeric partner posttranslationally. Harmine preferentially promoted degradation of the TWIST1-E2A heterodimer compared with the TWIST-TWIST1 homodimer, and targeting the TWIST1-E2A heterodimer was required for harmine cytotoxicity. Finally, harmine had activity in both transgenic and patient-derived xenograft mouse models of KRAS-mutant NSCLC. These studies identified harmine as a first-in-class TWIST1 inhibitor with marked anti-tumor activity in oncogene-driven NSCLC including EGFR mutant, KRAS mutant and MET altered NSCLC.Implications: TWIST1 is required for oncogene-driven NSCLC tumorigenesis and EMT; thus, harmine and its analogues/derivatives represent a novel therapeutic strategy to treat oncogene-driven NSCLC as well as other solid tumor malignancies. Mol Cancer Res; 15(12); 1764-76. ©2017 AACR.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Harmina/administração & dosagem , Neoplasias Pulmonares/tratamento farmacológico , Proteínas Nucleares/genética , Proteína 1 Relacionada a Twist/genética , Células A549 , Animais , Apoptose/efeitos dos fármacos , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Proliferação de Células/efeitos dos fármacos , Biologia Computacional , Receptores ErbB/genética , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Camundongos , Camundongos Transgênicos , Mutação , Multimerização Proteica/efeitos dos fármacos , Estabilidade Proteica/efeitos dos fármacos , Proteínas Proto-Oncogênicas p21(ras)/genéticaRESUMO
Epithelial cells are largely immotile under normal circumstances, but become motile during development, repair of tissue damage and during cancer metastasis. Numerous growth factors act to initiate epithelial cell movements. Hepatocyte growth factor (HGF) induces many epithelial cell lines to begin crawling. A number of small GTPases act downstream of HGF to alter cell shape and promote movement. Arf6 is one of these GTPases that can alter the cortical actin cytoskeleton and promote epithelial movement. Activation of Arf6 in MDCK cells by its guanine nucleotide exchange factor cytohesin 2/ARNO produces a scattering response strikingly reminiscent of the action of HGF. We have previously shown that IPCEF1, a scaffold that binds to cytohesin 2, is required for cytohesin-induced scattering. We report here that IPCEF1 is actually the C-terminal half of CNK3. CNKs are scaffolds involved in signal transduction downstream of Ras. We have found that both MDCK and CaCo-2 cells express a fused CNK3/IPCEF1 protein. Knockdown of this protein impairs HGF-induced Arf6 activation and migration in response to HGF treatment.