Andrew Beharry – 2021 Research Grant Recipient
Generously Funded by the DUNN with Cancer Research Fund
Andrew Beharry – University of Toronto, Mississauga, ON
Project Title: “Predicting Temozolomide Resistance in Glioblastoma using an Activitybased Fluorescent chemosensor for MGMT”
Description of Project:
A clinicians’ goal is to accurately predict what drug{s) will be most effective on a patient in order to minimize time the patient may not have and eliminate exposure to toxic treatments without benefiting from a positive outcome. In glioblastoma (GBM), the most common brain cancer in adults, the first-line treatments are typically surgery and radiotherapy, followed by chemotherapy using the drug temozolomide (TMZ). Unfortunately, TMZ is ineffective on a large number of GBM patients as a consequence of the action of the DNA repair protein, 06- Methylguanine DNA Methyltransferase {MGMT). It is well established that patients having high levels of MGMT have a poorer response to TMZ therapy compared to those that have low levels. As such, MGMT has been well regarded as a predictive and prognostic marker of TMZ-based therapy. Our project describes the development and application of a small molecule fluorescent chemosensor that directly monitors the activity of MGMT. Our vision is to use our sensor on fresh biopsied tissue samples for GBM patients and predict patient response to TMZ-based therapy. As such, clinicians around the world can routinely and accurately assess the MGMT status in GBM patients to help govern their decision making in chemotherapeutic treatments.
What receiving this award means:
“It is a great honor to receive a research grant from Brain Tumour Foundation of Canada. This funding will allow our team to optimize and validate our fluorescent chemosensor technology so that we can ultimately help clinicians choose the most effective drugs for glioblastoma patients”.
Mid/Final Report – March 2024
Our proposed project was to validate our recently developed small molecule fluorescent chemosensor of the DNA repair enzyme, O6-methylguanine DNA methyltransferase (MGMT). Our preliminary data outlined in the proposal had installed a red-emitting fluorophore to a covalent inhibitor of MGMT. SDS-PAGE revealed successful labelling of MGMT at its active site cysteine residue (C145), and live cell imaging in T98G cells (high MGMT protein) showed high fluorescent signals, while U251 cells (no MGMT protein) showed lower fluorescent signals.
For the first 12 months, we spent time and effort into validating the selectivity of this probe. We first had to scale up the synthesis of the inhibitor and the red-emitting fluorophore (JF-646). Although the cell work in our preliminary data revealed a reproducible fluorescence difference between cell lines with two extremes of MGMT protein (i.e., high protein and no protein), gel-based assays on whole cell lysates revealed labeling of several proteins. We also generated lysates from our live cell imaging experiments which also revealed poor selectivity for MGMT. Thus, we devoted year 2 to improving selectivity as outlined in aim 1 – “potential pitfall”.
Publication – April 2024
