The ERK–ZEB1 pathway mediates epithelial–mesenchymal transition in pemetrexed resistant lung cancer cells with suppression by vinca alkaloids

Abstract

High thymidylate synthase (TS) level in cancer tissue is considered to result in resistance to pemetrexed therapy for advanced stages of nonsquamous non-small cell lung cancers. To further investigate the mechanism of pemetrexed resistance and potential prognostic outcomes in lung cancer, we established pemetrexed-resistant lung adenocarcinoma cell sublines from CL1 harboring a mutated TP53 gene (R248W) and A549 harboring wild-type TP53. We found the TS expression is upregulated in both pemetrexed-resistant sublines and the reduced TS level achieved through shRNA inhibition resulted in higher pemetrexed sensitivity. We also demonstrated that the acquisitions of pemetrexed resistance enhances epithelial–mesenchymal transition (EMT) in vivo with a mice animal model and in vitro with CL1 and A549 sublines, which was associated with upregulation of ZEB1 which, in turn, downregulates E-cadherin and upregulates fibronectin. When ERK1/2 phosphorylation was reduced by an inhibitor (U0126) or siRNA inhibition, both pemetrexed-resistant sublines reduced their migration and invasion abilities. Therefore, the ERK-mediated pathways induce apoptosis with pemetrexed treatment, and may in turn mediate EMT when cancer cells are resistant to pemetrexed. We further demonstrated that the growth of pemetrexed-resistant tumors could be inhibited by vinblastine in vivo and vincristine in vitro. Our data indicate that pemetrexed resistance could be relieved by non-cross-resistant chemotherapeutic drugs such as vinca alkaloids and might be independent to TP53 status. Furthermore, the phosphorylation of ERK was reduced by vincristine. This finding provides a new insight for overcoming pemetrexed resistance and metastasis by application of vinca alkaloids.

Metformin synergistic pemetrexed suppresses non‐small‐cell lung cancer cell proliferation and invasion in vitro

“…Another study by Chi LY et al. also described the IC50 of pemetrexed for A549 cells (1304.7 ± 94.7 nmol/L) . The concentration range of metformin and pemetrexed used in our study, as previously indicated, is in accordance with the results of the preliminary experiment above.…”

Gemcitabine‐induced epithelial‐mesenchymal transition‐like changes sustain chemoresistance of pancreatic cancer cells of mesenchymal‐like phenotype

“…Our data show that gemcitabine treatment of mesenchymal pancreatic cells exacerbates their EMT‐like phenotype and invasiveness through ERK1/2 mediated ZEB‐1 upregulation. Interestingly, pemetrexed resistance of lung cancer cells was recently shown to be associated with induction of EMT and invasion through activation of ERK1/2‐ZEB‐1 pathway . ZEB‐1 has been shown to be associated with radioresistance and chemoresistance in several cancers including PC .…”

The histone deacetylase inhibitor OBP-801 and eribulin synergistically inhibit the growth of triple-negative breast cancer cells with the suppression of survivin, Bcl-xL, and the MAPK pathway

“…4c, our results interestingly showed that the combination treatment of eribulin and OBP-801 suppressed the MAPK pathway more effectively than single agent alone in TNBC. Recently, vincristine has also been reported in lung cancer to downregulate the phosphorylated ERK protein, resulting in the suppression of the zinc finger E-box binding homeobox 1 (ZEB1), an activator of epithelial-mesenchymal transition [15]. Eribulin has been shown to reverse epithelial-mesenchymal transition both in vitro and in vivo [19,20].…”

“…Among microtubule dynamic inhibitors, vinca alkaloids are known to suppress the MAPK pathway [15], while paclitaxel enhances it in other carcinoma cells [16]. Therefore, we investigated whether eribulin enhanced or suppressed the MAPK pathway in TNBC cells.…”