Characterization of CD44 splicing patterns in normal keratinocytes, dysplastic and squamous carcinoma cell lines.
The CD44 glycoprotein is spliced from a complex gene of 10 constitutive and 10 variant exons. In this study, CD44 splicing patterns and intron 9 retention were investigated by exon-specific RT-PCR for variant exons v1-v10 and intron 9 in normal, immortalized, dysplastic and malignant keratinocytes. Expression of product was determined immunohistochemically for some of the exons. Normal keratinocytes showed one major transcript including exons v2-v10 and 3 minor transcripts. No lines showed a normal CD44 splicing pattern but rather a variety of truncated transcripts of contiguous variant exons which overall correlated with expression. Squamous cell carcinoma (SCC)-4 and SCC-9 lines showed relatively normal transcripts although protein was expressed only by SCC-9. SCC-12B2, SCC-15, SCC-25 and SCC-27 showed a series of shorter overlapping transcripts, with loss of exons v8-v10 in the major transcripts. Intron 9 was not retained in normal keratinocytes or cell lines. Despite the fact that keratinocytes constitutively express all variant exons, splicing patterns are distinctly abnormal and merit investigation as potential markers for epidermal and oral squamous malignancy.
Bloor
B K
BK
Head & Neck Cancer Research Program, Guy's, King's & St. Thomas' Dental Institute, King's College London, UK.
Jelvagharan
M
M
White
K N
KN
Odell
E W
EW
D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D002454:Cell Differentiation; D017931:DNA Primers / Q000737:chemistry; D015870:Gene Expression; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics*; D007124:Immunoenzyme Techniques; D015603:Keratinocytes / Q000378:metabolism; D009062:Mouth Neoplasms / Q000235:genetics*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D018960:Hyaluronan Receptors; D012333:RNA, Messenger