title: Decreased expression of microRNA let-7i and its association with chemotherapeutic response in human gastric cancer.
abstract: BACKGROUND
  MicroRNA let-7i has been proven to be down-regulated in many human malignancies and correlated with tumor progression and anticancer drug resistance. Our study aims to characterize the contribution of miRNA let-7i to the initiation and malignant progression of locally advanced gastric cancer (LAGC), and evaluate its possible value in neoadjuvant chemotherapeutic efficacy prediction.
  
  
  METHODS
  Eighty-six previously untreated LAGC patients who underwent preoperative chemotherapy and radical resection were included in our study. Let-7i expression was examined for pairs of cancer tissues and corresponding normal adjacent tissues (NATs), using quantitative RT-PCR. The relationship of let-7i level to clinicopathological characteristics, pathologic tumor regression grades after chemotherapy, and overall survival (OS) was also investigated.
  
  
  RESULTS
  Let-7i was significantly down-regulated in most tumor tissues (78/86: 91%) compared with paired NATs (P < 0.001), and low levels of let-7i were significantly correlated with local invasion, lymphatic metastasis, and poor pathologic tumor response. Multivariate Cox regression analysis revealed that low let-7i expression was an unfavorable prognostic factor of OS (hazard ratio (HR) = 2.316, P = 0.024) independently of other clinicopathological factors, including tumor node metastasis (TNM) stage (HR = 3.226, P = 0.013), depth of infiltration (HR = 4.167, P < 0.001), and lymph node status (HR = 2.245, P = 0.037).
  
  
  CONCLUSIONS
  These findings indicate that let-7i may be a good candidate for use a therapeutic target and a potential tissue marker for the prediction of chemotherapeutic sensitivity and prognosis in LAGC patients.
authors.affiliation: Department of General Surgery, Changzhou No, 2 Hospital, Nanjing Medical University, Nanjing, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Liu
authors.forename: Tao
authors.initials: T
authors.lastname: Qian
authors.forename: Liming
authors.initials: L
authors.lastname: Tang
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.forename: Haohua
authors.initials: H
authors.lastname: Yang
authors.forename: Jun
authors.initials: J
authors.lastname: Ren
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000032:analysis*; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D016016:Proportional Hazards Models; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality / Q000473:pathology
chemical_list: D035683:MicroRNAs; C487931:mirnlet7 microRNA, human