The Tumor Suppressor Gene TUSC2 (FUS1) Sensitizes NSCLC to the AKT Inhibitor MK2206 in LKB1-dependent Manner

Abstract

TUSC2-defective gene expression is detected in the majority of lung cancers and is associated with worse overall survival. We analyzed the effects of TUSC2 re-expression on tumor cell sensitivity to the AKT inhibitor, MK2206, and explored their mutual signaling connections, in vitro and in vivo. TUSC2 transient expression in three LKB1-defective non-small cell lung cancer (NSCLC) cell lines combined with MK2206 treatment resulted in increased repression of cell viability and colony formation, and increased apoptotic activity. In contrast, TUSC2 did not affect the response to MK2206 treatment for two LKB1-wild type NSCLC cell lines. In vivo, TUSC2 systemic delivery, by nanoparticle gene transfer, combined with MK2206 treatment markedly inhibited growth of tumors in a human LKB1-defective H322 lung cancer xenograft mouse model. Biochemical analysis showed that TUSC2 transient expression in LKB1-defective NSCLC cells significantly stimulated AMP-activated protein kinase (AMPK) phosphorylation and enzymatic activity. More importantly, AMPK gene knockdown abrogated TUSC2-MK2206 cooperation, as evidenced by reduced sensitivity to the combined treatment. Together, TUSC2 re-expression and MK2206 treatment was more effective in inhibiting the phosphorylation and kinase activities of AKT and mTOR proteins than either single agent alone. In conclusion, these findings support the hypothesis that TUSC2 expression status is a biological variable that potentiates MK2206 sensitivity in LKB1-defective NSCLC cells, and identifies the AMPK/AKT/mTOR signaling axis as an important regulator of this activity.

TUSC2 Immunogene Therapy Synergizes with Anti–PD-1 through Enhanced Proliferation and Infiltration of Natural Killer Cells in Syngeneic Kras-Mutant Mouse Lung Cancer Models

“…Several reports have revealed a critical role for this pathway in a broad range of CD8 + T cells and IL15-induced NK cell proliferation and cytotoxicity. This is compatible with our previous reports that TUSC2 inhibits mTOR signaling in EGFR wildtype NSCLC (2). TUSC2 enhanced IL15/ IL15R, IL18, and Th1, all of which are regulated by mTOR, and perhaps mTOR inhibition by TUSC2 promotes constitutive release of these cytokines and others, therefore promoting enhanced proliferation and activation of NK and CT8 + T cells.…”

“…Researchers reported that NSCLC patients with loss of TUSC2 expression had significantly worse overall survival (OS) than did those with normal TUSC2 expression (1). TUSC2, a mitochondrial protein, is multifactorial in its mechanism of action and is involved in a wide array of cellular processes, including induction of apoptosis, inhibition of many kinases, mitochondrial calcium homeostasis, inhibition of reactive oxygen species (ROS) response, and increase of immune stimulation (2–6). In a previous study, we developed nanovesicles encapsulating an optimized TUSC2 expression plasmid.…”

Exogenous Restoration of TUSC2 Expression Induces Responsiveness to Erlotinib in Wildtype Epidermal Growth Factor Receptor (EGFR) Lung Cancer Cells through Context Specific Pathways Resulting in Enhanced Therapeutic Efficacy

“…We focused on FGFR2 expression because its level was reduced to the greatest extent. In addition, a previous study has highlighted FGFR2 signaling as a mechanism of acquired resistance to EGFR TKIs, and suggested that treatment of NSCLC patients with combinations of EGFR and FGFR specific TKIs may be a strategy to enhance efficacy of single EGFR inhibitors [ 23 ]. We found a significant inhibition of FGFR2 expression by TUSC2 transient transfection alone, suggesting a functional role for TUSC2 in the observed cooperative effect.…”

TUSC2(FUS1)-erlotinib Induced Vulnerabilities in Epidermal Growth Factor Receptor(EGFR) Wildtype Non-small Cell Lung Cancer(NSCLC) Targeted by the Repurposed Drug Auranofin

“…AMPK activation was proposed to sensitize NSCLC cells to erlotinib23. It is worth noting that TUSC2 directly activates AMPK allowing AMPK to drive cell dearth more effectively524.…”