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Updated: Apr 19, 2026
Long-term Live-cell Imaging to Assess Cell Fate in Response to Paclitaxel
Published on: May 14, 2018
A novel biosensor for quantitative monitoring of on-target activity of paclitaxel
H E Townley1, Y Zheng, J Goldsmith
1Department of Engineering Sciences, Parks Road, Oxford, OX1 3PJ, UK. Helen.Townley@eng.ox.ac.uk Peter.Dobson@eng.ox.ac.uk.
Abstract:
This study describes a system for quantifying paclitaxel activity using the C-terminus of α-tubulin as a biomarker. Following stabilization of microtubules with paclitaxel, a specific detyrosination reaction occurs at the C-terminus of α-tubulin which could be used to assess efficacy. A fluorescence resonance energy transfer (FRET) based biosensor was synthesized comprising a short peptide that corresponded to the C-terminus of α-tubulin, a fluorophore (Abz), and a quencher (Dnp). The fluorophore added to the end of the peptide can be released upon enzymatic detyrosination. In addition, a single fluorophore-tagged peptide was also conjugated to mesoporous silica nanoparticles to examine the feasibility of combining the drug with the peptide biomarker. As a proof of concept, we found that the degree of peptide cleavage, and therefore enzymatic activity, was directly correlated with exogenous bovine carboxypeptidase (CPA) an enzyme that mimics endogenous detyrosination. In addition, we show that cell lysates obtained from paclitaxel-treated cancer cells competed with exogenous CPA for biosensor cleavage in a paclitaxel dose-dependent manner. Our work provides strong evidence for the feasibility of combining paclitaxel with a novel biosensor in a multi-load nanoparticle.
Insights
This study introduces a novel biosensor to quantify paclitaxel efficacy by detecting detyrosination of α-tubulin. This method shows a direct correlation between paclitaxel concentration and biomarker activity in cancer cells.
Area of Science:
- Biochemistry
- Molecular Biology
- Nanotechnology
Background:
- Paclitaxel stabilizes microtubules, impacting cancer cell division.
- Assessing paclitaxel efficacy requires reliable biomarkers.
- Post-translational modification of α-tubulin, specifically detyrosination, is linked to microtubule dynamics.
Purpose of the Study:
- To develop and validate a system for quantifying paclitaxel activity.
- To utilize the C-terminus of α-tubulin detyrosination as a biomarker for drug efficacy.
- To explore the feasibility of integrating a paclitaxel drug with a peptide biomarker in nanoparticles.
Main Methods:
- Synthesis of a fluorescence resonance energy transfer (FRET) based biosensor using a peptide mimicking α-tubulin C-terminus, a fluorophore (Abz), and a quencher (Dnp).
- Conjugation of a fluorophore-tagged peptide to mesoporous silica nanoparticles.
- Assaying biosensor cleavage by exogenous bovine carboxypeptidase (CPA) and cell lysates from paclitaxel-treated cancer cells.
Main Results:
- The FRET biosensor demonstrated measurable peptide cleavage upon enzymatic detyrosination.
- Peptide cleavage correlated directly with the activity of exogenous CPA, mimicking endogenous detyrosination.
- Cell lysates from paclitaxel-treated cancer cells showed dose-dependent competition for biosensor cleavage, confirming paclitaxel's effect.
Conclusions:
- The developed FRET biosensor system effectively quantifies paclitaxel activity via α-tubulin detyrosination.
- The study validates the feasibility of combining paclitaxel with a peptide biomarker in a single nanoparticle formulation for potential co-delivery and monitoring.
