Bcl-xL silencing induces alterations in hsa-miR-608 expression and subsequent cell death in A549 and SK-LU1 human lung adenocarcinoma cells

PLoS One. 2013 Dec 10;8(12):e81735. doi: 10.1371/journal.pone.0081735. eCollection 2013.

Abstract

Bcl-xL is an anti-apoptotic protein that is frequently found to be overexpressed in non-small cell lung cancer leading to an inhibition of apoptosis and poor prognosis. Recently, the role of miRNAs in regulating apoptosis and cell survival during tumorigenesis has become evident, with cancer cells showing perturbed expression of various miRNAs. In this study, we utilized miRNA microarrays to determine if miRNA dysregulation in bcl-xL silenced lung adenocarcinoma cells could be involved in regulating cell death. Short interfering RNA-based transfection of A549 and SK-LU1 lung adenocarcinoma cells was successful in inducing a reduction in bcl-xL expression levels, resulting in a decrease in cell viability. A total of 10 miRNAs were found to be significantly differentially expressed when compared between siRNA-transfected and non-transfected cells including hsa-miR-181a, hsa-miR-769-5p, hsa-miR-361-5p, hsa-miR-1304 and hsa-miR-608. When overexpression studies on hsa-miR-608 was performed via transfection of miRNA mimics, cell death was found to be induced in A549 and SK-LU1 cells in comparison to untreated cells. This effect was reversed when knockdown studies involving anti-sense inhibitors were introduced. Combination of siRNA based silencing of bcl-xL (siBcl-xL) followed by anti-sense inhibitor transfection led to a decrease in the apoptotic population of A549 and SK-LU1 cells in comparison to cells only treated with siBcl-xL, illustrating the connection between bcl-xL, hsa-miR-608 and cell death. Gene target prediction analysis implicated the PI3K/AKT, WNT, TGF-β, and ERK signaling pathways as targets of bcl-xL induced miRNA alterations. We have demonstrated that bcl-xL silencing in A549 and SK-LU1 cells leads to the occurrence of cell death through the dysregulation of specific miRNAs. This study also provides a platform for anti-sense gene therapy whereby miRNA expression can be exploited to increase the apoptotic properties in lung adenocarcinoma cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / genetics
  • Adenocarcinoma / pathology*
  • Adenocarcinoma / therapy
  • Adenocarcinoma of Lung
  • Base Sequence
  • Cell Death / genetics
  • Cell Line, Tumor
  • Cell Survival / genetics
  • Gene Expression Regulation, Neoplastic / genetics*
  • Gene Silencing*
  • Genetic Therapy
  • Humans
  • Lung Neoplasms / genetics
  • Lung Neoplasms / pathology*
  • Lung Neoplasms / therapy
  • MicroRNAs / genetics*
  • RNA, Antisense / genetics
  • Up-Regulation / genetics
  • bcl-X Protein / deficiency*
  • bcl-X Protein / genetics*

Substances

  • MIRN608 microRNA, human
  • MicroRNAs
  • RNA, Antisense
  • bcl-X Protein

Grants and funding

This study was supported by University of Malaya Postgraduate Research Grants (PPP) (PS295/2010A and PV058/2011B), the University of Malaya Research Grant (UMRG) (RG037-10BIO) and the High Impact Research Grant (HIR) (H-50001-A000041). All funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.