Long Non-Coding RNA XLOC_006753 Promotes the Development of Multidrug Resistance in Gastric Cancer Cells Through the PI3K/AKT/mTOR Signaling Pathway

Cell Physiol Biochem. 2018;51(3):1221-1236. doi: 10.1159/000495499. Epub 2018 Nov 27.


Background/aims: The development of multidrug resistance (MDR), which results in disease recurrence and metastasis, is a crucial obstacle to successful chemotherapy for patients with gastric cancer (GC). Long non-coding RNAs (lncRNAs) have been found to play various roles in cancer. This study aimed to investigate the effect of XLOC_006753 on the development of MDR in GC cells.

Methods: The expression levels of XLOC_006753 in GC patients and MDR GC cell lines (SGC-7901/5-FU and SGC-7901/DDP cell line) were assessed by qRT-PCR. Statistical analyses were conducted to determine the relationship between XLOC_006753 expression and clinical features and to assess the prognostic value of XLOC_006753 for overall survival and progression-free survival. Then, a CCK-8 assay was used to detect cell proliferation ability and chemosensitivity. Flow cytometry was used to detect cell cycle and cell apoptosis. A wound-healing assay and transwell assay were used to detect cell migration. The expression of markers for MDR, G1/S transition, epithelial-mesenchymal transition (EMT) and PI3K/ AKT/mTOR signaling pathway were examined by western blot.

Results: XLOC_006753 was highly expressed in GC patients and MDR GC cell lines (SGC-7901/5-FU and SGC-7901/DDP cell lines), and its high expression was positively associated with metastasis, TNM stage, tumor size, and poor survival in GC patients. Moreover, XLOC_006753 was an independent prognostic biomarker of overall survival and progression-free survival for gastric cancer patients. Knocking down XLOC_006753 in the two MDR GC cell lines significantly inhibited cell proliferation, cell viability, cell cycle G1/S transition, and migration. XLOC_006753 knockdown also promoted apoptosis. Furthermore, western blots showed that XLOC_006753 knockdown decreased some markers of MDR, G1/S transition, and EMT expression, while increasing caspase9 expression and inhibiting the PI3K/AKT/mTOR signaling pathway in SGC-7901/5-FU and SGC-7901/DDP cells.

Conclusion: High expression of XLOC_006753 promoted the development of MDR, which was activated by the PI3K/AKT/mTOR pathway in GC cells.

Keywords: Gastric cancer; Multidrug resistance; PI3K/AKT/mTOR; Xloc_006753.

MeSH terms

  • Drug Resistance, Multiple
  • Drug Resistance, Neoplasm*
  • Epithelial-Mesenchymal Transition / drug effects
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Male
  • Middle Aged
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Prognosis
  • Proto-Oncogene Proteins c-akt / metabolism*
  • RNA, Long Noncoding / genetics*
  • Signal Transduction
  • Stomach Neoplasms / diagnosis
  • Stomach Neoplasms / drug therapy*
  • Stomach Neoplasms / genetics*
  • Stomach Neoplasms / metabolism
  • TOR Serine-Threonine Kinases / metabolism*
  • Up-Regulation


  • RNA, Long Noncoding
  • MTOR protein, human
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases