Abstract 3158: TUSC2 suppresses energy metabolism in lung cancer cells with opposite effects in normal bronchial epithelial cells
Authors: Tonello Jane , Berger Mark , Shanker Anil , Ivanova Alla 
Published: March 2024

Introduction: TUSC2 (TUmor Suppressor Candidate 2) is a tumor suppressor gene from the human 3p21.3 chromosomal region frequently deleted in lung cancers. Independently of deletion, reduced expression of TUSC2 is observed in ~ 80% of lung cancers, mesothelioma, breast, head-and neck, osteosarcoma, glioblastoma, and other cancers, suggesting a critical anti-tumor role of TUSC2. TUSC2 resides in mitochondria and is involved mitochondrial respiration/energy metabolism, ROS production, Ca2+ flux to/from mitochondria, etc. Studies on tumor-bearing mice treated with TUSC2-containing plasmid encapsulated in lipid nanoparticles (quaratusugene ozeplasmid) and Phase I and II clinical trials of quar oze in lung cancer patients provides a strong rationale to further study the tumor-protective mechanisms of TUSC2 protein. Main scientific question. We asked if and how human lung cancer cells, A549 and H358, that have ~80-90% decrease in TUSC2 expression, change their energy metabolism in response to re-introduction of TUSC2 as compared to Beas2B, a normal bronchial epithelial cell line. Cancer cells rely heavily on anaerobic glycolysis, while normal epithelial cells use mitochondrial respiration as a primary way of energy production.

Methods: Transient transfection of TUSC2-expressing plasmid to 3 cell lines; qPCR to confirm TUSC2 delivery; Seahorse analysis of energy production that measures in real time Oxygen Consumption Rate (OCR) and Extracellular Acidification Rate (ECAR) in different conditions.

Results: All three cell lines demonstrated high transfection efficiency. Seahorse analysis revealed that TUSC2 re-introduction to TUSC2-deficient cancer cells consistently suppressed both glycolytic and mitochondrial ATP production, thus leaving cells without sufficient energy to support their vital functions. We found a significant decrease in basal and maximal respiration, spare respiratory capacity, ATP production, glycolysis and glycolytic capacity in cancer cell lines transfected with TUSC2-expressing plasmid. Unlike cancer cells, both glycolytic and mitochondrial metabolism of normal epithelial cells Beas2B were significantly strengthened after the introduction of TUSC2, suggesting a beneficial role of TUSC2 for the metabolic health of normal cells. The experiments were repeated four times; Student T-test was used to calculate statistical significance.

Therapeutic Significance: These experiments suggest that TUSC2 plasmid delivery to cancer patients, and thus quar oze therapeutic use, may target and disrupt the metabolism of cancer cells, triggering either senescence or apoptotic pathways, while on the other hand, supporting the metabolism of normal epithelial cells. These data have high therapeutic significance, suggesting that one of the anti-tumor mechanisms of quar oze action in patients is the suppression of cancer cell metabolism resulting in cancer cell death.

Citation Format: Jane Tonello, Mark Berger, Anil Shanker, Alla Ivanova. TUSC2 suppresses energy metabolism in lung cancer cells with opposite effects in normal bronchial epithelial cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3158.