Ruvbl1 And Rubvl2 Are Chromatin Remodelers That Represent Prognostic And Novel Therapeutic Targets For A Subset Of Non-Small Cell Lung Cancers (Nsclcs)

RUVBL1 and RUVBL2 (collectively referred to as RUVBL1/2) are AAA+ ATPases that function in various chromatin remodeling complexes. We found that RUVBL1/2 are overexpressed (n = 224) and prognostic of patient outcome in NSCLC patients (n = 697) who undergo surgical resection (combined TCGA, KMPlot.com, and SPORE P50CA70907 dataset analyses). To assess the importance and biological functions of RUVBL1/2 in NSCLC, we measured cell growth following depletion of RUVBL1/2 in 24 NSCLC lines, representing a spectrum of oncogenotypes and histologies, and 2 normal human bronchial epithelial cell lines (HBECs) using two independent RNAi reagents. Growth inhibitory phenotypes ranged from 19-87% and were “rescued” by exogenous expression of an RNAi-resistant cDNA construct, indicating “on-target” siRNA effects. Four of the 23 NSCLCs were very sensitive (u003e75% growth inhibition), while 88% of NSCLCs were more growth inhibited than HBECs, indicating a therapeutic window. To establish molecular biomarkers of RUVBL1/2 dependency, we correlated whole exome mutation status, whole transcriptome mRNA levels, and a number of other parameters to sensitivity to RUVBL1/2 depletion. Sensitivity to RUVBL1/2 knockdown did not correlate with the mutation status or expression of any genes. However, sensitivity to RUVBL1/2 depletion did correlate with doubling time. Flow cytometry analysis in NSCLC lines sensitive to RUVBL1/2 KD revealed that RUVBL1/2 depletion resulted in a G2/M arrest (but not apoptosis), and a decrease in cell cycle related transcripts, such as CDKN3, AURKA, CIT and CDC20, whereas resistant cell lines do not exhibit these changes. Initial ChIP-seq analysis suggests that RUVBL1/2 preferentially occupies cell cycle related genes and are depleted in nucleosome free regions (i.e. transcription start sites). These results, combined with results from others demonstrating the necessity of ATP hydrolysis for RUVBL1/29s function(s), indicate that the chromatin remodelers RUVBL1/2 are potential therapeutic targets in a subset of NSCLCs. (Supported by UTSW Green Center Fellowship, CPRIT RP120732, SPORE P50CA70907) Citation Format: Paul M. Yenerall, Rahul Kollipara, Ryan Carstens, Kenneth Huffman, Luc Girard, Jaime Rodriguez, Ignacio Wistuba, David Mangelsdorf, John Minna, Ralf Kittler. RUVBL1 and RUBVL2 are chromatin remodelers that represent prognostic and novel therapeutic targets for a subset of non-small cell lung cancers (NSCLCs). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4779. doi:10.1158/1538-7445.AM2015-4779