Abstract 5480: NSCLC cells with LKB1 mutation are vulnerable to energetic and oxidative stresses induced by 8-Chloroadenosine

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Background: It has been demonstrated that loss of LKB1 is associated with a higher likelihood of tumor recurrence after surgery and shorter overall survival in early stage NSCLC. We sought to determine whether NSCLC tumor cells with loss of LKB1 are preferentially sensitive or resistant to various therapeutic agents. We tested 23 NSCLC cell lines, and observed that LKB1 mutant NSCLC cells are highly resistant to standard chemotherapy as well as EGFR inhibitors. In contrast, LKB1 mutant NSCLC cells are highly sensitive to 8-Chloroadenosine (8-Cl-Ado). 8-Cl-Ado is an RNA-directed nucleoside analogue, which depletes cellular ATP and triggers apoptosis in sensitive cells. LKB1 is known to play a key role in balancing cellular energy consumption and production. Therefore, we hypothesize that LKB1 mutant NSCLC cells are vulnerable to 8-Cl-Ado induced energetic stress. Method: Cellular ATP level was determined by LC-MS and luminescent based methods. Cell proliferation was measured by Celltiter-Glo assay. IC50 values were calculated by Calcusyn. Oxidative stress was measured by CellRox assay. Result: NSCLC cell lines with LKB1 mutation were significantly more sensitive to 8-Cl-Ado than wild type cell lines (p=0.024). We transfected H460 and A549 cells (both harboring mutant LKB1) with wild-type LKB1. Re-expression of LKB1 rendered cells resistant to 8-Cl-Ado (P<0.05). Knockdown LKB1 resulted in increased sensitivity to 8-Cl-Ado in Calu6 cells (p<0.05). Moreover, 8-Cl-Ado treatment caused a significant decrease in cellular ATP levels in LKB1 mutant cells. However, in A549 and H460 cells overexpressing wild-type LKB1, ATP levels were not decreased. Similarly, in H661 cells (wild-type LKB1) 8-Cl-Ado treatment did not affect ATP levels, whereas when LKB1 was knocked down by shRNA 8-Cl-Ado treatment reduced intracellular ATP levels. Furthermore, 8-Cl-Ado increased ROS levels in A549 cells but not in A549 cells overexpressing wild-type LKB1. Conclusion: Our result indicates that LKB1 mutant NSCLC cells are vulnerable to energetic and oxidative stresses induced by 8-Cl-Ado. LKB1 played a protecting role in cells under 8-Cl-Ado treatment. Citation Format: Chao Yang, Maria Angelica Cortez, Uma Giri, Jayanthi Gudikote, William G. Wierda, Varsha Gandhi, Lauren Averett Byers, John V. Heymach. NSCLC cells with LKB1 mutation are vulnerable to energetic and oxidative stresses induced by 8-Chloroadenosine. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5480. doi:10.1158/1538-7445.AM2014-5480