HOXA9 gene promotor methylation and copy number variation of SOX2 and HV2 genes in cell free DNA: A potential diagnostic panel for non-small cell lung cancer

BACKGROUND: Most cases of lung cancer are diagnosed at advanced stage. Detection of genetic and epigenetic markers in cell-free DNA (cfDNA) is a promising tool for the diagnosis of lung cancer at an early stage. The aim of this study was to identify non-invasive diagnostic markers in cell free DNA (cfDNA) for non-small cell lung cancer (NSCLC) as it is the most common type of lung cancer. METHODS: We investigated the cfDNA HOXA9 gene promotor methylation by pyrosequencing. Copy number variation of SOX2 and HV2 genes were detected by real-time PCR in cfDNA extracted from plasma samples of 25 newly diagnosed NSCLC patients and 25 age and sex matched controls. RESULTS: Methylation level of HOXA9 was significantly higher in NSCLC patients than controls (p > 0.001). SOX2 showed significantly higher CNV and HV2 showed lower CNV in patients than controls (p > 0.001, p = 0.001 respectively). Receiver Operating Characteristic (ROC) curve analysis for HOXA9 methylation, SOX2 CNV and HV2 CNV showed a discrimination power of 79.4%, 80% and 77.5% respectively and the area under the curve for the combined analysis of the three genes was 0.958 with 88% sensitivity and 100% specificity. CONCLUSIONS: In this study, we suggest a potentially diagnostic panel that may help in detection of lung cancer with high sensitivity and specificity using cell free DNA. This Panel included HOXA9 gene methylation and the CNV of SOX2 and HV2 genes.