Loss of Imprinting of Insulin-Like Growth Factor 2 and Risk of Primary Lung Cancer in Central China

Genomic imprinting is a non-Mendelian inherited epigenetic form of gene regulation that results in the differential expression of maternal and paternal alleles (Feinberg and Tycko, 2004; Livingstone, 2013). Loss of imprinting (LOI) describes mechanisms that either activate the normally silenced allele or inactivate the normally active gene copy. The IGF2 gene is a maternally imprinted proto-oncogene since a cluster of imprinting genes has been identified in chromosome 11p15.5, thus, the LOI of IGF2 may result in twofold to threefold increase in transcription, which is higher than the theoretical twofold increase (Sakatani et al., 2001; Woodson et al., 2004). Our previous study showed that overexpression of the mitogen IGF2 protein has an important function in the progression of primary lung cancer (Zhang et al., 2009). However, the imprinting status of IGF2 and its LOI incidence in primary lung cancer in Asian patients remains unclear. To determine whether the LOI of the IGF2 loci is involved in the pathogenesis of primary lung cancer, we examined the LOI status of IGF2 in lung cancer foci, its