Biology subjects

Dupre, D. J.

Publications and source records attributed to Dupre, D. J..

4 recordsLinked to original sources

bioRxiv2022

β-catenin interacts with the TAZ1 and TAZ2 domains of CBP/p300 to activate gene transcription

The transcriptional co-regulator {beta}-catenin is a critical effector of the canonical Wnt-signalling pathway, which plays a crucial role in regulating cell fate and maintaining tissue homeostasis. Deregulation of the Wnt/{beta}-catenin pathway is characteristic in the development of major types of cancer, where accumulation of {beta}-catenin promotes cancer cell proliferation and renewal. {beta}-catenin gene expression is facilitated through recruitment of co-activators such as histone acetyltransferases CBP/p300; however, the mechanism of their interaction is not fully understood. Here we investigate the interaction between the C-terminal transactivation domain of {beta}-catenin and CBP/p300. Using a combination of pulldown assays, isothermal titration calorimetry, and nuclear resonance spectroscopy we determine the disordered C-terminal region of {beta}-catenin binds promiscuously to the TAZ1 and TAZ2 domains of CBP/p300. We then map the interaction site of the C-terminal {beta}-catenin transactivation domain onto TAZ1 and TAZ2 using chemical-shift perturbation studies. Luciferase-based gene reporter assays indicate Asp750-Leu781 is critical to {beta}-catenin gene activation, and mutagenesis revealed that acidic and hydrophobic residues within this region are necessary to maintain TAZ1 binding. These results provide a mechanistic understanding of Wnt/{beta}-catenin gene regulation that underlies cell development and provide a framework to develop methods to block {beta}-catenin dependent signalling in the future.

biochemistry↗

bioRxiv2022

Structural basis of CBP/p300 recruitment by the microphthalmia-associated transcription factor

The microphthalmia-associated transcription factor (MITF) is a master regulator of the melanocyte cell lineage. Aberrant MITF activity can lead to multiple malignancies including skin cancer, where it modulates the proliferation and invasiveness of melanoma. MITF-dependent gene expression requires recruitment of transcriptional co-activators such as CBP/p300, but details of this process are not fully defined. Here, we investigate the structural and functional interaction between the MITF N-terminal transactivation domain (MITFTAD) and CBP/p300. A combination of pulldown assays and nuclear magnetic resonance spectroscopy determined that MITF binds both TAZ1 and TAZ2 domains of CBP/p300 with high affinity. The solution-state structure of the MITFTAD:TAZ2 complex reveals that MITF interacts with a hydrophobic surface of TAZ2, while remaining relatively dynamic. Peptide array and mutagenesis experiments determined that an acidic motif is integral to the MITFTAD:TAZ2 interaction and is necessary for transcriptional activity of MITF. Peptides that bind to the same surface of TAZ2 as MITFTAD, such as the adenoviral protein E1A, are capable of displacing MITF from TAZ2 and inhibiting transactivation. These results provide mechanistic insight into co-activator recruitment by MITF that are fundamental to our understanding of MITF targeted gene regulation and melanoma biology.

biochemistry↗

bioRxiv2021

Anti-cancer potential of cannabis terpenes in a taxol-resistant model of breast cancer

Chemotherapeutic resistance can limit breast cancer outcomes; therefore, the exploration of novel therapeutic options is warranted. Isolated compounds found in cannabis have previously been shown to exhibit anti-cancer effects, but little is known about their effects in resistant breast cancer. Our study aims to evaluate the effects of terpenes found in cannabis in in vitro chemotherapy-resistant model of breast cancer. We aimed to identify whether five terpenes found in cannabis produced anti-cancer effects, and if their effects were improved upon co-treatment with cannabinoids and flavonoids also found in cannabis. Nerolidol and {beta}-caryophyllene produced the greatest cytotoxic effects, activated the apoptotic cascade and reduced cellular invasion. Combinations with the flavonoid kaempferol potentiated the cytotoxic effects of ocimene, terpinolene, and {beta}-myrcene. Combinations of nerolidol and {Delta}9-tetrahydrocannabinol or cannabidiol produced variable responses ranging from antagonism and additivity to synergy, depending on concentrations used. Our results indicate that cannabis terpenes, alone or combined with cannabinoids and flavonoids, produced anti-cancer effects in chemotherapy-resistant breast cancer cell lines. This study is a first step in the identification of compounds that could have therapeutic potential in the treatment of resistant breast cancer.

cancer biology↗

bioRxiv2021

Anti-cancer properties of cannabidiol and Δ9-tetrahydrocannabinol and potential synergistic effects with gemcitabine, cisplatin and other cannabinoids in bladder cancer

IntroductionWith the legalization of cannabis in multiple jurisdictions throughout the world, a larger proportion of the population consumes cannabis. Several studies have demonstrated anti-tumor effects of components present in cannabis in different models. Unfortunately, little is known about the potential anti-tumoral effects of cannabinoids in bladder cancer, and how cannabinoids could potentially synergize with chemotherapeutic agents. Our study aims to identify whether a combination of cannabinoids, like cannabidiol and {Delta}9-tetrahydrocannabinol with agents commonly used to treat bladder cancer, such as gemcitabine and cisplatin, is able to produce desirable synergistic effects. We also evaluated whether co-treatment of different cannabinoids also generated synergistic effects. Materials and MethodsWe generated concentration curves with different drugs to identify the range at which they could exert anti-tumor effects. We also evaluated the activation of the apoptotic cascade and whether cannabinoids have the ability to reduce invasion. ResultsCannabidiol, {Delta}9-tetrahydrocannabinol and other cannabinoids reduce cell viability of bladder cancer cell lines, and their combination with gemcitabine or cisplatin may induce differential responses: from antagonistic to additive and synergistic effects, depending on the concentrations used. Cannabidiol and {Delta}9-tetrahydrocannabinol were also shown to induce caspase 3 cleavage and reduce invasion in a Matrigel assay. Cannabidiol and {Delta}9-tetrahydrocannabinol also display synergistic properties with other cannabinoids like cannabichromene or cannabivarin. DiscussionOur results indicate that cannabinoids can reduce human bladder transitional cell carcinoma cell viability, and that they can potentially exert synergistic effects when combined with other agents. Our in vitro results will form the basis for future studies in vivo and in clinical trials for the development of new therapies that could be beneficial for the treatment of bladder cancer in the future.

cancer biology↗