In-Silico Discovery of Novel Small-Molecule Inhibitors Targeting Transgelin-2-Actin Interaction Inhibits Proliferation, Invasion and Improves Chemo-Radiation Response in Human Glioblastoma

• Published in: International journal of radiation oncology, biology, physics Vol. 111; no. 3; p. e593
• Main Authors: Kumar, A., Rajasekera, P., Biehn, S., Beyer, S., McElroy, J., Becker, A., Johnson, B., Cui, T., Sebastian, E., Grosu, A., Lindert, S., Bell, E.H., Haque, S.J., Chakravarti, A.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-11-2021
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/j.ijrobp.2021.07.1587

Transgelin-2 (TAGLN2) is an oncogene and actin-binding protein known to induce actin polymerization, thereby playing a critical role in cell proliferation, migration/invasion, and therapeutic resistance in GBM and other malignancies. In our clinical correlative studies, TAGLN2 was found to be one of the top candidate genes associated with worse survival response and its expression at significantly higher level in GBM patients with wild-type IDH1/2 compared to mutant IDH1/2 patients. The standard treatment has remained relatively ineffective partly due to their invasive phenotype leading to tumor recurrence. Currently, there is no bonafide pharmacologic inhibitor that specifically blocks the Transgelin-2 functions. We hypothesize that targeting Transgelin-2 by small molecule inhibitors (SMIs) may improve patient outcome by circumventing therapeutic resistance mechanisms. This study aims to identify novel SMIs of Transgelin-2 and demonstrate the potential of these inhibitors as a novel strategy for therapeutic intervention in human glioblastoma.
Structure-based computational screening of SMIs libraries using docking algorithms- AutoDock Vina and Glide XP was employed to identify SMIs of Transgelin-2, which can bind to Transgelin-2. The compounds were further screened for their ability to be able to permeate BBB, using SwissADME webtool. A series of in-vitro binding and functional assays were employed to measure the potential of these inhibitors to bind and inhibit Transgelin-2-dependent actin-polymerization and subsequent cell proliferation/survival, invasion, neurosphere and colony formation in PDX GBM cell lines. Further, the potential of these inhibitors to sensitize these cells towards standard TMZ and/or RT was evaluated.
In-silico virtual screenings identified potential Transgelin-2 binding small molecule compounds that bind to Transgelin-2. These candidate molecules were predicted to permeate BBB using in-silico approach. In vitro binding study confirmed that these compounds bind to Transgelin-2 and inhibit the Transgelin-2-dependent actin-polymerization. We found that these compounds significantly compromised the proliferation, survival, migration/invasion and clonal expansion of GBM 08-387 and 3359 PDX cell lines. These compounds however showed no toxicity to normal human cells. These inhibitors also reduced the level of Transgelin-2 protein in these two cell lines in a dose- and time- dependent fashion. Our in-vitro data also suggest that these inhibitors significantly sensitized these GBM PDX cell lines towards temozolamide and/or radiation treatment in a dose- and time-dependent fashion.
Our study identified novel SMIs of Transgelin-2 and validated their potential to bind and significantly inhibit Transgelin-2-actin mediated cell proliferation, invasion and therapeutic resistance without any normal cell toxicity, thereby serving as potential candidates for preclinical trials.
A. Kumar: None. P. Rajasekera: None. S. Biehn: None. S. Beyer: None. J. McElroy: None. A. Becker: None. B. Johnson: None. T. Cui: None. E. Sebastian: None. A. Grosu: None. S. Lindert: None. E.H. Bell: None. S.J. Haque: None. A. Chakravarti: None.