Binding-induced, turn-on fluorescence of the EGFR/ERBB kinase inhibitor, lapatinib
James N Wilson1, Wenjun Liu, Adrienne S Brown
1Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida 33124, USA. jnwilson@miami.edu.
Abstract:
We report the photophysical properties, binding-induced turn-on emission, and fluorescence imaging of the cellular uptake and distribution of lapatinib, an EGFR/ERBB inhibitor. Lapatinib, a type II, i.e. inactive state, inhibitor that targets the ATP binding pocket of the EGFR family of receptor tyrosine kinases. DFT calculations predict that the 6-furanylquinazoline core of lapatinib should exhibit an excited state with charge transfer character and an S0 to S1 transition energy of 3.4 eV. Absorption confirms an optical transition in the near UV to violet, while fluorescence spectroscopy shows that photoemission is highly sensitive to solvent polarity. The hydrophobicity of lapatinib leads to fluorescent aggregates in solution, however, binding to the lipid-carrier protein, BSA or to the kinase domain of ERBB2, produces spectroscopically distinct photoemission. Confocal fluorescence microscopy imaging of lapatinib uptake in ERBB2-overexpressing MCF7 and BT474 cells reveals pools of intracellular inhibitor with emission profiles consistent with aggregated lapatinib.
Insights
Lapatinib, an EGFR/ERBB inhibitor, exhibits unique fluorescence properties sensitive to its environment. Its cellular uptake and distribution were visualized using fluorescence imaging, revealing intracellular aggregation.
Area of Science:
- Biophysics
- Chemical Biology
- Molecular Imaging
Background:
- Lapatinib is a type II inhibitor targeting the ATP binding pocket of EGFR family kinases.
- Understanding its photophysical properties is crucial for developing fluorescent probes for biological applications.
Purpose of the Study:
- To investigate the photophysical properties of lapatinib.
- To explore binding-induced changes in lapatinib's fluorescence.
- To visualize the cellular uptake and distribution of lapatinib using fluorescence imaging.
Main Methods:
- Density Functional Theory (DFT) calculations.
- Absorption and fluorescence spectroscopy.
- Confocal fluorescence microscopy.
- Cellular uptake studies in ERBB2-overexpressing MCF7 and BT474 cells.
Main Results:
- DFT predicted an excited state with charge transfer character for lapatinib's core.
- Lapatinib exhibits UV-Vis absorption and fluorescence sensitive to solvent polarity.
- Binding to BSA or ERBB2 kinase domain induced distinct spectral changes.
- Fluorescence imaging revealed intracellular accumulation of aggregated lapatinib in cancer cells.
Conclusions:
- Lapatinib possesses environment-sensitive photophysical properties.
- Its fluorescence can be modulated by molecular binding and cellular localization.
- Lapatinib can serve as a fluorescent probe for studying its own uptake and distribution in cancer cells.
