# Inhibition of NPC1L1 disrupts adaptive responses of drug‐tolerant persister cells to chemotherapy

## TL;DR

This study shows that blocking NPC1L1 weakens cancer cells' survival during chemotherapy by disrupting their redox balance.

## Contribution

The study reveals NPC1L1's role in drug-tolerant cancer cells and proposes a triple-combination therapy to prevent tumor recurrence.

## Key findings

- NPC1L1 promotes vitamin E uptake to reduce chemotherapy-induced oxidative stress in drug-tolerant persister cells.
- Inhibiting NPC1L1 with ezetimibe enhances chemotherapy by inducing methuosis and disrupting redox homeostasis.
- A triple-combination therapy including ezetimibe significantly reduced tumor recurrence in mice.

## Abstract

Entering a drug‐tolerant persister (DTP) state of cancer cells is a transient self‐adaptive mechanism by which a residual cell subpopulation accelerates tumor progression. Here, we identified the acquisition of a DTP phenotype in multidrug‐resistant (MDR) cancer cells as a tolerance response to routine combination treatment. Characterization of MDR cancer cells with a DTP state by RNA‐seq revealed that these cells partially prevented chemotherapy‐triggered oxidative stress by promoting NPC1L1‐regulated uptake of vitamin E. Treatment with the NPC1L1 inhibitor ezetimibe further enhanced the therapeutic effect of combinatorial therapy by inducing methuosis. Mechanistically, we demonstrated that NRF2 was involved in transcriptional regulation of NPC1L1 by binding to the −205 to −215 bp site on its promoter. Decreased DNA methylation was also related partially to this process. Furthermore, we confirmed that a triple‐combination of chemotherapeutic agents, verapamil, and ezetimibe, had a significant anti‐tumor effect and prevented tumor recurrence in mice. Together, our study provides a novel insight into the role of DTP state and emphasizes the importance of disrupting redox homeostasis during cancer therapy.

Drug‐tolerant persister (DTP) state is a driver of therapy failure and cancer relapse. This study identified a key role for NPC1L1 in multidrug‐resistant (MDR) cancer cells with the DTP state, where NPC1L1 orchestrated a redox signaling against the harsh environment caused by cancer therapy.