Abstract 2124: Analysis of the functional relevance of novel alternative splicing events in non-small cell lung cancer

Abstract

Abstract Lung cancer is the most common cause of death by cancer worldwide. Deregulation of alternative splicing (AS) is becoming increasingly relevant for the understanding of the molecular mechanisms of lung tumor progression. Genome-wide microarrays containing probes in exons and junctions can be used to identify differential AS events. We developed an algorithm, called ExonPointer, which was optimized to detect AS events using this kind of platforms. Using this technique, we successfully detected splicing events regulated by the oncogene serine/arginine-rich splicing factor 1 (SRSF1) in lung cancer cell lines. Moreover, four of these genes, ATP11C, IQCB1, TUBD1 and PRRC2C, showed a significantly different pattern of AS in primary non-small cell lung cancer (NSCLC) compared with normal lung tissue. In the case of PRRC2C, we also demonstrated that the deregulation of the splicing event was important for tumor progression. We next applied the same technique to target differential AS events in NSCLC primary tissues (13 lung squamous cell carcinomas and 9 lung adenocarcinomas). Their paired normal lung tissues were used as reference. The validation rate for the top 20 events identified by ExonPointer was 70%. Gene cluster analyses showed an enrichment of clusters implicated in cancer development such as Cellular Growth and Proliferation, or Cell Death and Survival. Among others, we observed accumulation of a tumor-specific splice variant in Mitogen-Activated Protein Kinase 9 (MAPK9 or JNK2). The tumor-specific variant for this gene contains an alternative exon 2 which causes a frame shift introducing a premature stop codon. Functional analyses using isoform-specific siRNAs showed that this variant did not affect tumor growth or progression. However, its expression significantly correlated with the expression of Regulator of Nonsense Transcripts 3A and B (UPF3A and UPF3B) in 42 lung cancer cell lines. These proteins belong to the Nonsense Mediated Decay (NMD) pathway, which eliminates aberrant mRNA transcripts, suggesting that the presence of some aberrant AS variants in lung cancer are caused by a malfunction of NMD. In conclusion, we have developed a reliable tool for the high throughput analysis of AS, and have identified new splicing events in lung cancer that can be studied as potential diagnostic markers and therapeutic targets. Citation Format: Fernando J. de Miguel, Ravi D. Sharma, Pablo Reclusa, María J. Pajares, Angel Rubio, Ruben Pio, Luis M. Montuenga. Analysis of the functional relevance of novel alternative splicing events in non-small cell lung cancer. [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 2124. doi:10.1158/1538-7445.AM2015-2124