TUSC2, the Gene Delivered by Genprex’s REQORSA®, Functions as a Novel Tumor Suppressor for Glioblastoma

Genprex, a clinical-stage gene therapy company focused on developing life-changing therapies for patients with cancer and diabetes, today announced that independent researchers recently presented preclinical data on the tumor suppressor gene, TUSC2, reporting that it functions as a novel tumor suppressor for glioblastoma. TUSC2 is the tumor suppressor gene that is reexpressed in tumors using REQORSA® Therapy treatment, Genprex’s lead drug candidate. Genprex has no affiliation with these researchers.

The independent researchers presented their abstract, titled, “Investigating TUSC2 for its tumor suppressive functions in glioblastoma and its role in gliomagenesis,” at the 2023 American Association for Cancer Research Annual Meeting on April 17. The abstract reports TUSC2 protein expression, but not mRNA expression, to be significantly decreased in glioblastoma as compared to normal brain. TUSC2 protein is destabilized in glioblastoma due to polyubiquitination by E3 ligase, neural precursor cell-expressed developmentally downregulated gene 4 (NEDD4), and degradation by the proteasome. The researchers determined that NEDD4 targets TUSC2 on lysine residue K71.

The researchers also reported that TUSC2 overexpression reduced colony formation and neurosphere formation and promoted apoptosis of glioblastoma cells in vitro, and suppressed tumor growth in vivo. Further, glioblastoma cells with CRISPR-mediated knockout (KO) of TUSC2 were highly aggressive in vitro and in vivo, demonstrating the role of TUSC2 as a novel tumor suppressor for glioblastoma. In the study, researchers performed immunoprecipitation-mass spectrometry analysis to identify TUSC2-interacting proteins in both normal human astrocytes and glioblastoma cell lines.

“This research supports the growing body of studies evaluating TUSC2 as a target in oncology, and potentially an effective treatment, for many types of cancer,” said Rodney Varner, Chairman, President and Chief Executive Officer of Genprex. “We are encouraged by the increasing number of research institutions and independent researchers producing positive data on TUSC2, which provide additional support for REQORSA® and its therapeutic potential against cancers.”

REQORSA® Therapy is currently in development for the treatment of non-small cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). REQORSA® consists of the TUSC2 gene expressing plasmid encapsulated in non-viral nanoparticles made from lipid molecules (the Company’s ONCOPREX® Nanoparticle Delivery System) with a positive electrical charge. REQORSA® is injected intravenously and specifically targets cancer cells, taking advantage of leaky tumor vascularity, increased tumor pinocytosis, and attraction of positively charged lipid nanoparticles to negatively charged cancer cells. REQORSA is designed to deliver the functioning TUSC2 gene to cancer cells while minimizing their uptake by normal tissue.