Abstract
We have previously shown that glioblastoma stem cells (GSCs) are enriched in the hypoxic tumor microenvironment, and that monocarboxylate transporter-4 (MCT4) is critical for mediating GSC signaling in hypoxia. Basigin is involved in many physiological functions during early stages of development and in cancer and is required for functional plasma membrane expression of MCT4. We sought to determine if disruption of the MCT-Basigin interaction may be achieved with a small molecule. Using a cell-based drug-screening assay, we identified Acriflavine (ACF), a small molecule that inhibits the binding between Basigin and MCT4. Surface plasmon resonance and cellular thermal-shift-assays confirmed ACF binding to basigin in vitro and in live glioblastoma cells, respectively. ACF significantly inhibited growth and self-renewal potential of several glioblastoma neurosphere lines in vitro, and this activity was further augmented by hypoxia. Finally, treatment of mice bearing GSC-derived xenografts resulted in significant inhibition of tumor progression in early and late-stage disease. ACF treatment inhibited intratumoral expression of VEGF and tumor vascularization. Our work serves as a proof-of-concept as it shows, for the first time, that disruption of MCT binding to their chaperon, Basigin, may be an effective approach to target GSC and to inhibit angiogenesis and tumor progression.
Highlights
Glioblastoma (GBM) are the most common and lethal brain tumors in adults, claiming about 14,000 lives annually in the U.S alone[1]
Robust Renilla luciferase (Rluc) activity was detected in cells expressing NhRL-MCT1 or NhRL-monocarboxylate transporter-4 (MCT4) and Basigin-ChRL, but not when either NhRL-MCT1, NhRL-MCT4, or Basigin-ChRL were expressed alone (Fig. 1B)
Attempts to reconstitute Rluc activity with NhRL fused to the cytoplasmic tails of MCT1 (59aa) or MCT4 (60aa) with the ChRL fused to the cytoplasmic tail (41aa) of Basigin were unsuccessful
Summary
Glioblastoma (GBM) are the most common and lethal brain tumors in adults, claiming about 14,000 lives annually in the U.S alone[1]. We demonstrated that targeting MCT4, using short-hairpin RNAs (shRNAs), resulted in a significant growth inhibition in vitro and in vivo These effects were augmented by hypoxic culture conditions and did not involve perturbations in lactate homeostasis, which led us to conclude that MCT4 signaling relies on lactate export-independent mechanism for growth inhibition in GBMs9. Given their crucial roles in cancer and the known dependency of MCTs on Basigin for functional plasma membrane expression, we, set out to investigate whether disruption of the MCT-Basigin interaction may be achieved with a small molecule. Our work confirms that small molecules can effectively disrupt protein-protein interaction between integral cell-surface proteins in vitro and in vivo and serve as effective antitumor agents
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
