title: Loss of imprinting of insulin-like growth factor 2 is associated with increased risk of primary lung cancer in the central China region.
abstract: BACKGROUND
  To determine the imprinting status of the IGF2 in Chinese patients with primary lung cancer and to analyze the clinical significance of the loss of imprinting (LOI) of IGF2.
  
  
  METHODS
  PCR- RFLP and RT-PCR-RFLP were carried out to select heterozygous cases for the ApaI polymorphism within exon 9 of the IGF2 gene and further analyze IGF2 LOI in 64 lung cancer patients, respectively.
  
  
  RESULTS
  Of 64 lung cancer patients, 31 were heterozygous for IGF2. The positive rates of IGF2 LOI of lung cancer foci, matched paracancer tissues, and normal lung tissues were 77.4% (24/31), 61.3% (19/31), and 29.0% (9/31), respectively. The LOI differences for IGF2 among the three groups were statistically significant (χ2=15.267, p=0.000), and the LOI frequency of IGF2 in normal lung tissue was significantly lower than that in lung cancer foci and paracancer tissues (χ2=14.577, p=0.000; χ2=6.513, p=0.011). No statistical difference was observed between the lung tumor group and the matched paracancer group (χ2=1.897, p=0.168). The prevalence of advanced clinical stages (χ2=2.379; p=0.017) and lymph node metastasis (χ2=5.552; p=0.018) was significantly higher for LOI- positive paracancer tissues than for LOI-negative paracancer tissues.
  
  
  CONCLUSIONS
  IGF2 LOI is highly frequent in Chinese primary lung cancer patients, especially those with increased risk of lymph node metastasis and advanced clinical stages. IGF2 LOI may be an early epigenetic event in human lung carcinogenesis.
authors.affiliation: Department of Pathology, Yantai Yantaishan Hospital, Jiefang Road, Yantai, China E-mail : 36005172@qq.com.
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.forename: Cui-Huan
authors.initials: CH
authors.lastname: Wu
authors.forename: Xiao-Ling
authors.initials: XL
authors.lastname: Zhu
authors.forename: You-Jie
authors.initials: YJ
authors.lastname: Wang
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000556:secondary; D014408:Biomarkers, Tumor / Q000235:genetics*; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000556:secondary; D016022:Case-Control Studies; D005500:Follow-Up Studies; D018392:Genomic Imprinting; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D008168:Lung / Q000378:metabolism; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology; D008207:Lymphatic Metastasis; D009367:Neoplasm Staging; D012150:Polymorphism, Restriction Fragment Length; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D014408:Biomarkers, Tumor; C035170:IGF2 protein, human; D012333:RNA, Messenger; D007335:Insulin-Like Growth Factor II