10540 Background: Mutations of the receptors KIT and PDGFRA in GIST are the oncogenetic events of disease as well as the targets of molecular therapies. Within the PDGFRA mutations, the D842V mutation in exon 18 confers in vitro and in vivo resistance to imatinib. Next generation sequencing techniques may completely dissect all the possible somatic mutations and genomic rearrangements in order to identify novel therapeutic targets in this patients population. Methods: Five patients with gastric GIST were analyased (3 M, 2 F; mean age 65,5 years, range 51-77). The tumor dimension ranged between 3 and 15 cm, MI < 2 and 8 /50 HPF. No metastases were present in all cases. The KIT and PDGFRA anlysis showed a D842V mutation in exon 18 of PDGFRA in all cases. Whole transcriptome sequencing was performed with Illumina HiScanSQ platform with a paired-end strategy (75x2). After performing quality controls, the short reads were mapped with Tophat-Botie pipeline against the human reference genome (HG19). The variations, such as Single nucleotide variants (SNVs) and InDels, were called by SNVMix2 (a software suited for SNVs discovery in tumor samples) implementing an accurate filtering procedures developed in our laboratory. Two predictors of mutations effect at protein level (SNPs&GO and Provean) were employed in order to prioritize the emerging variation. Results: An average of 206 coding non-synonymous variants were highlighted in the five GIST samples, of which ~ 30% were predicted as deleterious with at least one predictor. In addition to PDGFRA D842V mutation, in all five patients were found mutations on different receptor tyrosine kinases, such as FGFR4 and DDR2. Moreover three out of five patients harboured mutations on members of the MDR/TAP subfamily that are involved in multidrug resistance, in particular on ABCB1, ABCB4 and on ABCB6 genes. Other mutations were found on the hedgehog and MAPK signaling pathway and on SNF/SWI chromatin remodeling complex. Conclusions: New molecular events have been identified in PDGFRA D842V mutant GIST. These data should be validated in larger series and the role of these mutations as therapeutic targets should be further investigated.
Identification of novel therapeutic targets in the PI3K/AKT/mTOR pathway in hepatocellular carcinoma using targeted next generation sequencing
