Trametinib plus 4-Methylumbelliferone Exhibits Antitumor Effects by ERK Blockade and CD44 Downregulation and Affects PD-1 and PD-L1 in Malignant Pleural Mesothelioma

Our plain-English summary of Trametinib plus 4-Methylumbelliferone Exhibits Antitumor Effects by ERK Blockade and CD44 Downregulation and Affects PD-1 and PD-L1 in Malignant Pleural Mesothelioma, by H. Cho, S. Matsumoto, Y. Fujita, et al (Journal of Thoracic Oncology, 2017).

The study

• Authors: H. Cho, S. Matsumoto, Y. Fujita, A. Kuroda, T. Menju, M. Sonobe, N. Kondo, I. Torii, T. Nakano, P.N. Lara, D.R. Gandara, H. Date, S. Hasegawa
• Journal: Journal of Thoracic Oncology
• Published: 2017;12(3):477-490
• Cited by: 37 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: Malignant pleural mesothelioma (MPM) is a highly aggressive malignancy in which the mitogen-activated protein kinase pathway plays a critical role in the regulation of tumorigenesis. Hyaluronic acid (HA) is a major component of the extracellular matrix, and elevated HA levels with a concurrent increase in malignant properties are associated with MPM.

Methods: We evaluated the effects of trametinib, a mitogen-activated protein kinase (MEK) inhibitor, and 4-methylumbelliferone (4-MU), an HA synthesis inhibitor, alone and in combination on MPM cells in vitro and in vivo. We studied the effects of trametinib, 4-MU, and their combination on MPM cells by using cell viability assays, Western blot analysis, and a mouse xenograft model.

Results: Trametinib and 4-MU exhibited antiproliferative activity in MPM cells. Trametinib blocked MEK-dependent extracellular signal-regulated kinase (ERK) phosphorylation and decreased CD44 expression in a concentration-dependent manner. Trametinib inhibited the expression of Fra-1 (the activator protein 1 [AP1] component), inhibited ERK phosphorylation, and decreased CD44 expression. 4-MU inhibited ERK phosphorylation but not CD44 expression. In a mouse xenograft model, trametinib and 4-MU alone suppressed tumor growth compared with a control. The combination had a greater inhibitory effect than either monotherapy. Immunohistochemical analysis showed that trametinib treatment alone significantly reduced expression of programmed cell death 1 ligand 1. Furthermore, the combination of trametinib and 4-MU resulted in higher expression of programmed cell death 1 and programmed cell death 1 ligand 1 than did the 4-MU treatment alone.

Conclusions: Our results suggest that trametinib and 4-MU are promising therapeutic agents in MPM and that further study of the combination is warranted.

Copyright © 2016 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

In plain English

This was a laboratory study. The authors tested two drugs, alone and together: trametinib, which blocks the enzyme MEK, and 4-methylumbelliferone (4-MU), which blocks production of hyaluronan. They used four malignant pleural mesothelioma cell lines and nude mice carrying tumors grown from one of them, NCI-H226. The study did not involve patients or measure asbestos exposure. In cell cultures, trametinib reduced live cells in all four lines. 4-MU reduced them in three lines but not in MSTO-211H. Trametinib blocked activation of the signaling protein ERK and lowered CD44, a hyaluronan receptor. 4-MU did not significantly lower CD44. In mice treated for 32 days, in groups of 4 to 5, each drug significantly slowed tumor growth compared with controls, and the combination slowed it more than either drug alone. In tumor tissue stains, trametinib alone lowered the immune checkpoint protein PD-L1. 4-MU alone raised PD1 and PD-L1, and the combination raised them more than 4-MU alone. The authors concluded that both drugs are promising therapeutic agents for this cancer and that the combination warrants further study.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory study: cell culture (in vitro) experiments and an animal experiment (mouse xenograft model)
• Who was studied: Four human malignant pleural mesothelioma cell lines (NCI-H226, NCI-H2452, NCI-H2052, MSTO-211H) obtained from the American Type Culture Collection. Female nude mice (4 to 5 weeks old, from Clea Japan) were implanted with NCI-H226 cells, in treatment groups of 4 to 5 mice.
• Exposure: Not asbestos. The treatments were the drugs trametinib (a MEK inhibitor) and 4-MU (a hyaluronan synthesis inhibitor), alone and combined. In cells, trametinib was used at 0 to 100 µM and 4-MU at 0 to 1 mM for 72 hours. In mice, trametinib was given at 1 or 3 mg/kg/day orally once daily and 4-MU at 225 mg/kg/day orally twice daily, for 32 days.
• Main results:
  • In cell cultures, trametinib reduced live cells in a concentration-dependent manner. The IC50 values were 11.5 µM for NCI-H226, 11.2 µM for NCI-H2452, 12.7 µM for NCI-H2052 and 0.15 µM for MSTO-211H.
  • 4-MU reduced live cells in three cell lines, with IC50 values between 186 µM and 1.52 mM. MSTO-211H cells were not affected in the concentration range tested.
  • In NCI-H226 and MSTO-211H cells, trametinib inhibited ERK phosphorylation and lowered CD44 protein levels in a concentration-dependent manner. Knocking down ERK1 and ERK2 also decreased CD44.
  • In NCI-H226 cells, 4-MU only slightly inhibited ERK phosphorylation at high concentrations and increased it at low concentrations. CD44 levels did not significantly decrease.
  • In mice with NCI-H226 tumors, both drugs significantly suppressed tumor growth compared with the control: 1 mg/kg/day trametinib, P less than 0.0001; 3 mg/kg/day trametinib, P less than 0.0001; 225 mg/kg/day 4-MU, P less than 0.01.
  • In mice, the combination (1 mg/kg/day trametinib plus 225 mg/kg/day 4-MU) suppressed tumor growth more than either drug alone. Versus trametinib, P less than 0.01; versus 4-MU, P less than 0.0001; versus control, P less than 0.0001.
  • In mouse tumors, only the combination significantly reduced Ki-67, a marker of dividing cells, compared with control (P less than 0.0001). Neither drug alone did so significantly.
  • In tissue stains of mouse tumors, trametinib alone at both 1 and 3 mg/kg significantly reduced PD-L1 (P less than 0.0001 and P less than 0.001 respectively). It caused no significant change in PD1.
  • In tissue stains of mouse tumors, 4-MU alone significantly increased PD1 and PD-L1 (both P less than 0.0001). The combination produced higher PD1 and PD-L1 than 4-MU alone (both P less than 0.0001). In western blot analysis, however, 4-MU alone and the combination produced no significant change in PD-1 or PD-L1.
• The authors' conclusion: The authors concluded that trametinib and 4-MU are promising therapeutic agents in malignant pleural mesothelioma and that further study of the combination is warranted.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: PD-L1, Pleural Mesothelioma, Tumorigenesis, Hyaluronic Acid.

Related studies

• A phase Ib dose-finding, pharmacokinetic study of the focal adhesion kinase inhibitor GSK2256098 and trametinib in patients with advanced solid tumours — G. Mak, J.C. Soria, et al. (2019)
• Downregulation of the PD-1/PD-Ls pathway in peripheral cells correlates with asbestosis severity — M. Qiu, Y. Chen, et al. (2021)
• Immune biomarkers PD-1/PD-L1 and TLR3 in malignant pleural mesotheliomas — C. Combaz-Lair, F. Galateau-Sallé, et al. (2016)
• The PD-L1/PD-1 pathway promotes dysfunction, but not "exhaustion", in tumor-responding T cells from pleural effusions in lung cancer patients — H. Prado-Garcia, S. Romero-Garcia, et al. (2017)
• Downregulation of thymidylate synthase by RNAi molecules enhances the antitumor effect of pemetrexed in an orthotopic malignant mesothelioma xenograft mouse model — A.S. Abu Lila, C. Kato, et al. (2016)
• Downregulation of thymidylate synthase and E2F1 by arsenic trioxide in mesothelioma — S.K. Lam, Y.Y. Li, et al. (2015)

Browse more research in Journal of Thoracic Oncology, or return to medical research.