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Updated: Apr 19, 2026

Antibiotic Dereplication Using the Antibiotic Resistance Platform
Published on: October 17, 2019
When will resistance be futile?
1Department of Pathology and Cell Biology, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Canada. katherine.borden@umontreal.ca.
Abstract:
Cancer cells rapidly evolve a multitude of defense mechanisms to evade the effects of the oncologist's drug arsenal. Unfortunately, clinical strategies to overcome these lag far behind. This mismatch likely underlies our inability to implement new durable treatment strategies. Here, a new form of multidrug resistance, inducible drug glucuronidation, is discussed. This form was discovered while developing means to target a specific oncogene, the eukaryotic translation initiation factor 4E (eIF4E), with its inhibitor ribavirin. In two clinical studies, ribavirin treatment led to substantial clinical responses, but all responding patients eventually relapsed. In most cases, this was due to the overexpression of the sonic hedgehog transcription factor Gli1, which elevated the UDP glucuronsyltransferase UGT1A enzymes. UGT1As add glucuronic acid to many drugs. Indeed, these cells are resistant to not only ribavirin, but also Ara-C, and likely other drugs. Inhibition of Gli1 reduced UGT1As, eliminated drug glucuronides, and renewed sensitivity to ribavirin and Ara-C. These studies highlight that cancer cells and their resistant counterparts metabolize drugs differently from each other as well as from normal cells. Likely, these inducible modifications go beyond glucuronidation. Understanding the extent of inducible drug modifications and the pathways that drive expression of the corresponding enzymatic machinery will better position us to finally make resistance futile.
Insights
Cancer cells develop drug resistance through inducible drug glucuronidation, driven by Gli1 and UGT1A enzymes. Inhibiting Gli1 restores drug sensitivity, offering new strategies against cancer treatment failure.
Area of Science:
- Oncology
- Cancer Biology
- Pharmacology
Background:
- Cancer cells develop resistance to chemotherapy drugs.
- Existing strategies to overcome drug resistance are insufficient for durable treatment.
- Inducible drug modifications represent a significant challenge in cancer therapy.
Purpose of the Study:
- To investigate a novel form of multidrug resistance: inducible drug glucuronidation.
- To explore the role of eukaryotic translation initiation factor 4E (eIF4E) and its inhibitor ribavirin in cancer.
- To understand the mechanisms underlying relapse in patients treated with ribavirin.
Main Methods:
- Clinical studies involving ribavirin treatment for cancer patients.
- Investigating the role of the sonic hedgehog transcription factor Gli1 and UDP glucuronsyltransferase (UGT1A) enzymes.
- Assessing the impact of Gli1 inhibition on drug metabolism and sensitivity.
Main Results:
- Ribavirin treatment initially showed clinical responses but patients relapsed due to drug resistance.
- Overexpression of Gli1 led to elevated UGT1A enzymes, causing drug glucuronidation and resistance to ribavirin and Ara-C.
- Inhibition of Gli1 reduced UGT1A levels, decreased drug glucuronides, and restored sensitivity to chemotherapy.
Conclusions:
- Cancer cells metabolize drugs differently than normal cells, particularly under resistance conditions.
- Inducible drug glucuronidation, mediated by Gli1 and UGT1As, is a key mechanism of acquired multidrug resistance.
- Targeting Gli1 and understanding inducible drug modifications are crucial for developing effective, durable cancer treatments.
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