Loss Of Imprinting Of The Igf2 And Its Significance In Renal Cell Carcinoma

Objective: To investigate the imprinting status of Insulin-like growth factor 2 (IGF2) in renal cell carcinoma (RCC) and explore its relationship with the development of RCC. Methods: Thirty cases of matched tumor (Ca) and tumor-adjacent kidney tissues (N) were obtained from Peking University Shenzhen Hospital with informed consent forms. Based on a polymorphism of Apa1 site in exon 9 of IGF2 gene, polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) was used to select the heterozygous allele. Loss of imprinting (LOI) of IGF2 was further examined with RT-PCR-RFLP. Results: Nineteen IGF2 heterozygous cases were selected among 30 RCC patients (63.3%, 19/30). Among 19 heterozygous genotype cases, 13 cases have IGF2 LOI in both of matched Ca and N tissues (68.4%, 13/19). Only one case had LOI of IGF2 in Ca but not in N tissue (5.3%, 1/19). In 22 cases of CCRCC, 10 cases showed LOI of IGF2 (45.45%, 10/22); in 5 cases of PRCC, 2 cases showed LOI of IGF2 (40%, 2/5); in 2 cases of CRCC, one case showed LOI of IGF2 (50 %, 1/2). Specially, the unique one case of MTSCC showed LOI of IGF2 in Ca but not in N tissue. LOI of IGF-II gene was distributed in non age-dependent and non pathological type-dependent patterns. Moreover, 6 cases of T1 phases RCC showed LOI of IGF2 in all T1 heterozygous RCC cases (75%, 6/8). In addition, female to male ratio is 10/4 in IGF2 LOI group and 3/2 in non IGF2 LOI group, which suggests LOI of IGF2 gene is more likely to occur in female patients. Conclusions: LOI of IGF2 may be relate to RCC.