title: Upregulated long intergenic noncoding RNA KRT18P55 acts as a novel biomarker for the progression of intestinal-type gastric cancer.
abstract: BACKGROUND
  Long noncoding RNAs (lncRNAs) with dysregulated expression levels have been investigated in numerous types of different cancer. Whether lncRNAs can predict the progression of gastric cancer (GC) still remains largely unclear. The aim of our study was to investigate whether KRT18P55, a novel intergenic lncRNA, can be a predictive biomarker for GC.
  
  
  METHODS
  To determine the expression levels of KRT18P55 in GC, we evaluated it in five GC cell lines (SGC-7901, MGC-803, BGC-823, AGS, and HG27) and 97 GC tissue samples in comparison with a normal control by quantitative polymerase chain reaction. In addition, the association with patient clinicopathological characteristics was analyzed to identify the clinical significance of KRT18P55. We also used publicly accessible data from The Cancer Genome Atlas (TCGA) to further verify the expression levels and clinical significance of KRT18P55. Furthermore, a receiver operating characteristic curve was also conducted to evaluate the diagnostic value of KRT18P55 for GC.
  
  
  RESULTS
  A significant upregulation was observed in GC cell lines (P<0.01) and tissue samples (P<0.01). This finding was consistent with the results of 29 pairs of GC tissue samples from TCGA (P<0.01). Additionally, we indicated that the increased expression of KRT18P55 was related to the progression of intestinal type (P=0.032), which was also supported by results of independent GC cohorts from TCGA (P<0.01). However, we did not find significant difference in prognosis between patients with high and low expression of KRT18P55 (P>0.05). Finally, KRT18P55 showed potential diagnostic value for GC with an area under the receiver operating characteristic curve of 0.733 (P<0.01).
  
  
  CONCLUSIONS
  Upregulated KRT18P55 was a novel biomarker for the progression of GC, especially for the intestinal type.
authors: Department of Surgical Oncology and General Surgery, The First Hospital of China Medical University, Shenyang, People's Republic of China.
authors: Bin
authors: B
authors: Ma
authors: Department of Surgical Oncology and General Surgery, The First Hospital of China Medical University, Shenyang, People's Republic of China.
authors: Jiajun
authors: J
authors: Wang
authors: Department of Surgical Oncology and General Surgery, The First Hospital of China Medical University, Shenyang, People's Republic of China.
authors: Yongxi
authors: Y
authors: Song
authors: Department of Surgical Oncology and General Surgery, The First Hospital of China Medical University, Shenyang, People's Republic of China.
authors: Peng
authors: P
authors: Gao
authors: Department of Surgical Oncology and General Surgery, The First Hospital of China Medical University, Shenyang, People's Republic of China.
authors: Jingxu
authors: J
authors: Sun
authors: Department of Surgical Oncology and General Surgery, The First Hospital of China Medical University, Shenyang, People's Republic of China.
authors: Xiaowan
authors: X
authors: Chen
authors: Department of Surgical Oncology and General Surgery, The First Hospital of China Medical University, Shenyang, People's Republic of China.
authors: Yuchong
authors: Y
authors: Yang
authors: Department of Surgical Oncology and General Surgery, The First Hospital of China Medical University, Shenyang, People's Republic of China.
authors: Zhenning
authors: Z
authors: Wang
keywords: KRT18P55; biomarker; gastric cancer; intestinal type; long noncoding RNA