MicroRNA expression profiling identifies miR-328 regulates cancer stem cell-like SP cells in colorectal cancer

Br J Cancer. 2012 Mar 27;106(7):1320-30. doi: 10.1038/bjc.2012.88.


Background: Side population (SP) cells and their relationship to stem cell-like properties have been insufficiently studied in colorectal cancer (CRC). MicroRNAs (miRNAs) have attracted much attention but their roles in the maintenance of SP phenotype remain unclear.

Methods: The SPs from CRC cell lines and primary cell cultures were analysed for stem cell-like properties. MiRNA microarray analysis identified miR-328 as a potential stemness miRNA of SP phenotype. The level of miR-328 expression in clinical samples and its correlation with SP fraction were determined. Gain-of-function and loss-of-function studies were performed to examine its roles in cancer stem-like SP cells. Furthermore, bioinformatics prediction and experimental validation were used to identify miR-328 target genes.

Results: The SP cells sorted from CRC possess cancer stem cell (CSC)-like properties, including self-renewal, differentiation, resistance to chemotherapy, invasive and strong tumour formation ability. MiR-328 expression was significantly reduced in SP cells compared with Non-SP cells (P<0.05). Moreover, miR-328 expression was downregulated in CRC (n=33, P<0.05) and low miR-328 expression tend to correlate with high SP fraction (n=15, r=0.6559, P<0.05, Pearson's correlation). Functional studies indicated that miR-328 expression affects the number of SP cells. In addition, miR-328 overexpression reversed drug resistance and inhibited cell invasion of SP cells. Furthermore, luciferase reporter assay demonstrated that miR-328 directly targets ABCG2 and MMP16 and affects the levels of mRNA and protein expression in SP cells.

Conclusion: These findings indicate that CRC contain cancer stem-like SP cells. MiR-328 has an important role in maintaining cancer stem-like SP phenotype that may be a potential target for effective CRC therapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily G, Member 2
  • ATP-Binding Cassette Transporters / genetics
  • Cell Differentiation
  • Cell Line, Tumor
  • Cell Transformation, Neoplastic
  • Colorectal Neoplasms / genetics*
  • Colorectal Neoplasms / pathology
  • Down-Regulation
  • Drug Resistance, Neoplasm
  • Flow Cytometry
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Matrix Metalloproteinase 16 / genetics
  • MicroRNAs / metabolism
  • MicroRNAs / physiology*
  • Neoplasm Invasiveness
  • Neoplasm Proteins / genetics
  • Neoplastic Stem Cells / physiology*


  • ABCG2 protein, human
  • ATP Binding Cassette Transporter, Subfamily G, Member 2
  • ATP-Binding Cassette Transporters
  • MIRN328 microRNA, human
  • MMP16 protein, human
  • MicroRNAs
  • Neoplasm Proteins
  • Matrix Metalloproteinase 16