Moesin-Mediated P-Glycoprotein Activation During Snail-Induced Epithelial-Mesenchymal Transition in Lung Cancer Cells

Epithelial-mesenchymal transition (EMT) plays a role in not only cancer metastasis, but also drug resistance, which is associated with increased levels of efflux transporters such as P-glycoprotein (P-gp). Here, we examined whether P-gp activation during Snail-induced EMT of lung cancer cells is mediated by ezrin, radixin, and moesin (ERM), which regulate transporter localization. HCC827 lung cancer cells overexpressing the transcription factor Snail showed increased Rhodamine123 efflux and increased paclitaxel resistance, reflecting increased P-gp activity. Concomitantly, the expression level of moesin, but not ezrin or radixin, was significantly increased. The increase of P-gp activity was suppressed by knockdown of moesin. Thus, the increase of P-gp activity associated with Snail-induced EMT may be mediated mainly by moesin in HCC827 cells. On the other hand, the Snail mRNA expression level was correlated with the expression level of each ERM in 4 non-small-cell lung cancer cell lines (HCC827, A549, H441, H1975) and in tumor tissues, but not normal tissues, of patients with lung cancer. These results suggest that P-gp activation during EMT is at least partially due to increased expression of moesin. Coadministration of moesin inhibitors with anticancer drugs might block P-gp-mediated drug efflux organ-specifically, improving treatment efficacy and minimizing side effects on other organs.

Fasudil increases temozolomide sensitivity and suppresses temozolomide-resistant glioma growth via inhibiting ROCK2/ABCG2

Resistance to temozolomide (TMZ) is a major clinical challenge in glioma treatment, but the mechanisms of TMZ resistance are poorly understood. Here, we provided evidence that ROCK2 acted redundantly to maintain resistance of TMZ in TMZ-resistant gliomas, and as a ROCK2 phosphorylation inhibitor, fasudil significantly suppressed proliferation of TMZ-resistant gliomas in vivo and vitro via enhancing the chemosensitivity of TMZ. Additionally, the membrane translocation of ABCG2 was decreased with fasudil by ROCK2/moesin pathway. We also showed that fasudil suppressed the expression of ABCG2 via ROCK2/moesin/β-catenin pathway. Our results reveal an indispensable role for ROCK2 and provide strong evidence for the therapeutic use of fasudil in the clinical setting for TMZ-resistant gliomas.