Decreased expression of cell adhesion genes in cancer stem-like cells isolated from primary oral squamous cell carcinomas

Tumour Biol. 2018 May;40(5):1010428318780859. doi: 10.1177/1010428318780859.


The goal of this study was to isolate cancer stem-like cells marked by high expression of CD44, a putative cancer stem cell marker, from primary oral squamous cell carcinomas and identify distinctive gene expression patterns in these cells. From 1 October 2013 to 4 September 2015, 76 stage III-IV primary oral squamous cell carcinoma of the gingivobuccal sulcus were resected. In all, 13 tumours were analysed by immunohistochemistry to visualise CD44-expressing cells. Expression of CD44 within The Cancer Genome Atlas-Head and Neck Squamous Cell Carcinoma RNA-sequencing data was also assessed. Seventy resected tumours were dissociated into single cells and stained with antibodies to CD44 as well as CD45 and CD31 (together referred as Lineage/Lin). From 45 of these, CD44+Lin- and CD44-Lin- subpopulations were successfully isolated using fluorescence-activated cell sorting, and good-quality RNA was obtained from 14 such sorted pairs. Libraries from five pairs were sequenced and the results analysed using bioinformatics tools. Reverse transcription quantitative polymerase chain reaction was performed to experimentally validate the differential expression of selected candidate genes identified from the transcriptome sequencing in the same 5 and an additional 9 tumours. CD44 was expressed on the surface of poorly differentiated tumour cells, and within the The Cancer Genome Atlas-Head and Neck Squamous Cell Carcinoma samples, its messenger RNA levels were higher in tumours compared to normal. Transcriptomics revealed that 102 genes were upregulated and 85 genes were downregulated in CD44+Lin- compared to CD44-Lin- cells in at least 3 of the 5 tumours sequenced. The upregulated genes included those involved in immune regulation, while the downregulated genes were enriched for genes involved in cell adhesion. Decreased expression of PCDH18, MGP, SPARCL1 and KRTDAP was confirmed by reverse transcription quantitative polymerase chain reaction. Lower expression of the cell-cell adhesion molecule PCDH18 correlated with poorer overall survival in the The Cancer Genome Atlas-Head and Neck Squamous Cell Carcinoma data highlighting it as a potential negative prognostic factor in this cancer.

Keywords: CD44; Oral squamous cell carcinoma; PCDH18; RNA-sequencing; cancer stem cells; gingivobuccal sulcus.

MeSH terms

  • Aspartic Acid Endopeptidases / biosynthesis
  • Biomarkers, Tumor / immunology
  • Cadherins / biosynthesis*
  • Calcium-Binding Proteins / biosynthesis
  • Carcinoma, Squamous Cell / genetics*
  • Carcinoma, Squamous Cell / pathology
  • Cell Adhesion / genetics*
  • Cell Line, Tumor
  • Extracellular Matrix Proteins / biosynthesis
  • Flow Cytometry
  • Gene Expression Regulation, Neoplastic / genetics
  • Human papillomavirus 16 / genetics
  • Human papillomavirus 16 / isolation & purification
  • Human papillomavirus 18 / genetics
  • Human papillomavirus 18 / isolation & purification
  • Humans
  • Hyaluronan Receptors / genetics*
  • Hyaluronan Receptors / immunology
  • Hyaluronan Receptors / metabolism
  • Leukocyte Common Antigens / immunology
  • Mouth Neoplasms / genetics*
  • Mouth Neoplasms / pathology
  • Neoplastic Stem Cells / pathology*
  • Platelet Endothelial Cell Adhesion Molecule-1 / immunology
  • Protocadherins
  • RNA, Messenger / genetics
  • Reverse Transcriptase Polymerase Chain Reaction


  • Biomarkers, Tumor
  • CD44 protein, human
  • Cadherins
  • Calcium-Binding Proteins
  • Extracellular Matrix Proteins
  • Hyaluronan Receptors
  • PCDH18 protein, human
  • Platelet Endothelial Cell Adhesion Molecule-1
  • Protocadherins
  • RNA, Messenger
  • SPARCL1 protein, human
  • matrix Gla protein
  • Leukocyte Common Antigens
  • PTPRC protein, human
  • Aspartic Acid Endopeptidases