Abstract 4354: A human bronchial epithelial cell model demonstrates a role for glutamine regulation in genomic instability and oncogenic transformation
Authors: Omar Omar M. , Rahman Jamshedur , Massion Pierre 
Published: August 2019

Background: Previous work from our laboratory has investigated the role of solute carrier family A1 member 5 (SLC1A5) as a critical modulator of glutamine (Gln) uptake, cell growth and tumor progression in non-small cell lung cancer (NSCLC). In addition, remarkable metabolic reprogramming was observed in cells from individuals at high risk of lung cancer, including an increased dependence on Gln. However, it remains unclear how these changes in Gln metabolism and other metabolic dysregulations contribute to early events of tumorigenesis such as genomic instability. Given the emerging role of Gln metabolism in cancer and the differential expression of SLC1A5 in NSCLC, we tested the hypothesis that Gln uptake is a key mechanism by which cells with oncogenic potential can transform into a malignant phenotype.

Aims & Strategy: The aim of this study is to evaluate the involvement of SLC1A5 in the process of early oncogenic transformation and survival. To address this aim, we utilized four HBECs immortalized by over-expressing Cdk4 and human telomerase reverse transcriptase (hTERT), along with a series of canonical oncogenic drivers, P53-knocdown, KRAS and MYC overexpression, which drove these cells to exhibit a malignant phenotype. This successful transformation of an in vitro model could be useful in studying the metabolic dysregulation and, in particular, the role of Gln metabolism in contributing to genomic instability in an accessible and employable cell model representative of the oncogenic transformation process.

Results: We found that oncogene driven HBECs exhibited a substantially higher expression of SLC1A5 than unaltered HBEC cells. Inhibition of SLC1A5 by a small molecule inhibitor, gamma-l-Glutamyl-P-NitroAnilide (GPNA), decreased cell survival, Gln uptake and markers of genotoxic stress. The sensitivity to GPNA treatment was significantly correlated with SLC1A5 RNA expression (R2=0.96, P&lt;0.05). We tested the effect of SLC1A5 inhibition on two markers of genomic instability, gamma-H2Ax and 8oxoGuanine, and discovered that GPNA treated cells exhibited higher degree of gamma-H2Ax and 8oxoGuanine staining suggesting that Gln uptake has a protective role against DNA damage. We further investigated the effect of effect of GPNA treatment on apoptotic signaling and found that SLC1A5 inhibition is associated with the activation of Caspase-9.

Conclusion: Overall, Our results indicate that oncogene-transformed HBECs exhibited higher dependence on Gln uptake through SLC1A5 relative to the non-oncogenic clones. Tumor-forming HBECs exhibited higher sensitivity to SLC1A5 inhibition than non-tumorigenic ones. Furthermore, Gln deprivation was implicated in regulation of genomic integrity and apoptosis in this cell model. This works suggests that Gln metabolism regulates aspects of genomic instability and implicates its function in lung tumorigenesis.

Citation Format: Omar M. Omar, Jamshedur Rahman, Pierre Massion. A human bronchial epithelial cell model demonstrates a role for glutamine regulation in genomic instability and oncogenic transformation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4354.