The Bi-steric Inhibitor RMC-5552 Reduces mTORC1 Signaling and Growth in Lymphangioleiomyomatosis
Jilly F Evans1,2, Owen A Ledwell1,2, Yan Tang3
1Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine.
American Journal of Respiratory Cell and Molecular Biology
|November 12, 2024
Summary
New research shows RMC-5552 effectively targets LAM cancer stem-like cells by inhibiting the mTORC1 pathway, offering a more durable treatment than rapamycin for lymphangioleiomyomatosis (LAM).
Area of Science:
- Molecular Biology
- Oncology
- Pulmonology
Background:
- Tuberous sclerosis complex (TSC) gene mutations hyperactivate the mTORC1 pathway in pulmonary cells, leading to lymphangioleiomyomatosis (LAM).
- Rapamycin is the sole approved therapy for LAM but shows limited long-term efficacy upon cessation.
- LAM cells exhibit high expression of eukaryotic translation initiation factor 4E (eIF4E)-dependent genes and low 4E-binding protein 1 (4E-BP1) expression, favoring oncogenic translation.
Purpose of the Study:
- To investigate the role of eIF4E translation initiation in LAM.
- To compare the efficacy of a novel mTORC1 inhibitor, RMC-5552, with rapamycin in LAM models.
Main Methods:
- Analysis of gene expression in pulmonary LAM cancer stem-like state (SLS) cells, focusing on eIF4E and 4E-BP1.
- Treatment of LAM-associated fibroblasts with RMC-5552 and rapamycin.
- Assessment of protein phosphorylation in mTORC1-driven pathways (S6K1/S6 and 4E-BP1/eIF4E).
Main Results:
- LAM SLS cells showed high eIF4E and low 4E-BP1 expression, indicating enhanced oncogenic translation.
- RMC-5552 inhibited LAM-associated fibroblast growth and key mTORC1 pathway phosphorylation, including the 4E-BP1/eIF4E axis.
- RMC-5552 demonstrated more durable inhibition compared to rapamycin, which only affected the S6K1/S6 pathway and showed rapid reversal.
Conclusions:
- RMC-5552 effectively targets the 4E-BP1/eIF4E translation pathway implicated in LAM.
- RMC-5552 shows superior and more durable inhibition of LAM cell growth compared to rapamycin.
- RMC-5552 holds potential for eradicating LAM cancer SLS cells and may benefit LAM and other mTORC1-hyperactive diseases.
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