Targeting the EMT transcription factor Snail overcomes resistance to osimertinib in EGFR-mutant non-small cell lung cancer.

The resistance mechanism of the third generation of epidermal growth factor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib is complex. Epithelial mesenchymal transition (EMT) is a common mechanism of EGFR-TKI acquired resistance. Snail is an important transcription factor related to EMT. Whether targeting Snail can reverse the resistance of osimertinib by downregulating Snail is unknown. The presence of EMT in H1975/OR (osimertinib resistance) cells was confirmed by transwell assay. To explore the EMT role in resistance, the expression levels of EMT markers were detected in both parental cells H1975 and resistant cells H1975OR. We used RNA interference technology to knockdown the key regulator Snail in resistant cells. After the interference efficiency was confirmed, changes in EMT-related molecules of Snail were explicitly downregulated, and changes in sensitivity and migration and invasion ability were also examined. We used CDK4/6 inhibitor to test the ability of reversing drug resistance by downregulating Snail. Compared with the H1975 cell line, the H1975/OR resistant cell line showed increased invasiveness, upregulated expression of vimentin and downregulation of E-cadherin. EMT occurred in the H1975/OR resistant cell line. The expression of Snail was upregulated in the osimertinib-resistant cell line H1975/OR. Knockdown of Snail increased the sensitivity of H1975/OR cells to osimertinib. CDK4/6 inhibitor palbociclib could downregulate the expression of Snail. CDK 4/6 inhibitor palbociclib combined with osimertinib could reverse the resistance of osimertinib in H1975/OR. Snail plays an important role in the third generation of EGFR-TKI osimertinib resistance, which may be reversed by downregulating Snail.

Qin Q ，Li X ，Liang X ，Zeng L ，Wang J ，Sun L ，Zhong D ... -  《-》

CDK4/6 inhibitor palbociclib overcomes acquired resistance to third-generation EGFR inhibitor osimertinib in non-small cell lung cancer (NSCLC).

The third-generation EGFR-TKI, represented by osimertinib, has been widely used in clinical practice; however, resistance eventually emerges. At present, it remains unclear whether an abnormal cell cycle is involved in acquired resistance, and whether the combination of palbociclib (CDK4/6 inhibitor) and osimertinib can overcome the third-generation TKI resistance. We established osimertinib-resistant cells (H1975 OR) derived from EGFR-mutant NSCLC cells H1975. Drug effects on cells were assessed with Cell Counting Kit-8 (CCK8). Protein alterations were detected with western blot analysis. RT-PCR was used to evaluate the differences of gene mRNA. Cell cycle distribution of H1975 S and H1975 OR cells was compared using flow cytometry. Compared with H1975, the sensitivity of H1975OR to the CDK4/6 inhibitor was increased and the proportion of cells in G1 phase was decreased. The mRNA level of CDK4, CDK 6 and the protein level of CDK4, pRB were increased in H1975OR. In the H1975OR cells, palbociclib significantly increased the proportion of G1 phase cells. The combination of osimertinib and palbociclib synergistically decreased the survival of H1975OR by cell cycle arrest. Combined treatment was found to inhibit the initial phosphorylation of RB by inhibiting the function of CDK4/6, significantly reducing the level of p-RB, and blocking cell proliferation. An osimertinib acquired resistance cell line (H1975 OR) was successfully established. The expression of cell cycle related genes was altered in H1975OR. The expression of CDK4 and the phosphorylation of Rb, the downstream molecule of CDK4/6, was increased in H1975OR cells. The combination of CDK4/6 inhibitor palbociclib and osimertinib could overcome the acquired resistance of osimertinib.

Qin Q ，Li X ，Liang X ，Zeng L ，Wang J ，Sun L ，Zhong D ... -  《-》

Let-7c regulated epithelial-mesenchymal transition leads to osimertinib resistance in NSCLC cells with EGFR T790M mutations.

Li XF ，Shen WZ ，Jin X ，Ren P ，Zhang J ... -  《Scientific Reports》

ID1 mediates resistance to osimertinib in EGFR T790M-positive non-small cell lung cancer through epithelial-mesenchymal transition.

Liu K ，Chen X ，Wu L ，Chen S ，Fang N ，Cai L ，Jia J ... -  《BMC Pulmonary Medicine》

PIM1 kinase promotes EMT-associated osimertinib resistance via regulating GSK3β signaling pathway in EGFR-mutant non-small cell lung cancer.

Acquired resistance is inevitable in the treatment of non-small cell lung cancer (NSCLC) with osimertinib, and one of the primary mechanisms responsible for this resistance is the epithelial-mesenchymal transition (EMT). We identify upregulation of the proviral integration site for Moloney murine leukemia virus 1 (PIM1) and functional inactivation of glycogen synthase kinase 3β (GSK3β) as drivers of EMT-associated osimertinib resistance. Upregulation of PIM1 promotes the growth, invasion, and resistance of osimertinib-resistant cells and is significantly correlated with EMT molecules expression. Functionally, PIM1 suppresses the ubiquitin-proteasome degradation of snail family transcriptional repressor 1 (SNAIL) and snail family transcriptional repressor 2 (SLUG) by deactivating GSK3β through phosphorylation. The stability and accumulation of SNAIL and SLUG facilitate EMT and encourage osimertinib resistance. Furthermore, treatment with PIM1 inhibitors prevents EMT progression and re-sensitizes osimertinib-resistant NSCLC cells to osimertinib. PIM1/GSK3β signaling is activated in clinical samples of osimertinib-resistant NSCLC, and dual epidermal growth factor receptor (EGFR)/PIM1 blockade synergistically reverse osimertinib-resistant NSCLC in vivo. These data identify PIM1 as a driver of EMT-associated osimertinib-resistant NSCLC cells and predict that PIM1 inhibitors and osimertinib combination therapy will provide clinical benefit in patients with EGFR-mutant NSCLC.

Zhou J ，Wang X ，Li Z ，Wang F ，Cao L ，Chen X ，Huang D ，Jiang R ... -  《Cell Death & Disease》