CD44 Expression in Oro-Pharyngeal Carcinoma Tissues and Cell Lines

Abstract

Expression of CD44, a transmembrane hyaluronan-binding glycoprotein, is variably considered to have prognostic significance for different cancers, including oral squamous cell carcinoma. Although unclear at present, tissue-specific expression of particular isoforms of CD44 might underlie the different outcomes in currently available studies. We mined public transcriptomics databases for gene expression data on CD44, and analyzed normal, immortalized and tumour-derived human cell lines for splice variants of CD44 at both the transcript and protein levels. Bioinformatics readouts, from a total of more than 15,000 analyses, implied an increased CD44 expression in head and neck cancer, including increased expression levels relative to many normal and tumor tissue types. Also, meta-analysis of over 260 cell lines and over 4,000 tissue specimens of diverse origins indicated lower CD44 expression levels in cell lines compared to tissue. With minor exceptions, reverse transcribed polymerase chain reaction identified expression of the four main isoforms of CD44 in normal oral keratinocytes, transformed lines termed DT and HaCaT, and a series of paired primary and metastasis-derived cell lines from oral or pharyngeal carcinomas termed HN4/HN12, HN22/HN8 and HN30/HN31. Immunocytochemistry, Western blotting and flow cytometric assessments all confirmed the isoform expression pattern at the protein level. Overall, bioinformatic processing of large numbers of global gene expression analyses demonstrated elevated CD44 expression in head and neck cancer relative to other cancer types, and that the application of standard cell culture protocols might decrease CD44 expression. Additionally, the results show that the many variant CD44 exons are not fundamentally deregulated in a diverse range of cultured normal and transformed keratinocyte lines.

Breast Cancer Cells Respond Differentially to Modulation of TGFβ2 Signaling after Exposure to Chemotherapy or Hypoxia

“…The induction of CD44 in hypoxia required 3 days, compared with 1 day for induction of VEGF, and therefore CD44 does not appear to be a direct target of hypoxia inducible factor (HIF). As alternatively spliced variants of CD44 yield protein isoforms with different binding specificities for extracellular matrix substrates, cell surface receptors, and other signaling molecules (29), we analyzed the variants by RT-PCR after each treatment with exon-specific primers (30). CD44S and CD44v8-10 were similarly induced in epirubicin and hypoxia compared with untreated cells (Supplementary Fig.…”

Prognostic implications of CD44, NANOG, OCT4, and BMI1 expression in tongue squamous cell carcinoma

“…In a systematic review and meta‐analysis study evaluating the prognosis significance of CD44 expression in oral and pharyngeal cancer, Chen et al surprisingly found that CD44 expression predicts an improved disease‐free survival rate, although no association with clinicopathological features was observed. The conflicting findings regarding CD44 expression as a prognostic marker in OSCC may be related to the heterogeneity of patient cohorts, differences in grading systems, different primary antibodies, and posttranslational modifications that can mask CD44 epitopes leading to a failure in staining …”

“…In a multiple transcriptomics data analysis, CD44 was specifically overexpressed in HNSCC when compared with other solid cancers, suggesting the important role of this cell adhesion molecule in this type of cancer . Some studies have also demonstrated that CD44 spliced variants can participate in OSCC development and progression due to their more restricted distribution in normal and malignant tissue and, possibly, due to their distinct functions . Wang et al have demonstrated that, in HNSCC, including OSCC, CD44v3, CD44v6, and CD44v10, proteins are expressed in greater proportions in metastatic lymph nodes when compared with primary tumors.…”

“…CD44v3 have relevant glycosaminoglycan attachment sites that are involved with the binding of the basic fibroblast growth factor and vascular endothelial growth factor, both of which can promote angiogenesis and contribute to malignant progression . We believe that RT‐qPCR may be considered in future studies aiming to investigate the possible use of CD44 variants as markers in tongue SCC, as the lack of antibody standardization for the detection of CD44 posttranslational changes, such as glycosylation, may mask the expression of the CD44 variants in tongue SCC . Further studies are needed to elucidate the prognostic value of CD44 variants specifically in OSCC as well as their role in identifying the CSC subpopulations.…”

Increased Expression of CD44v9, A Cancer Stem Cell Marker, in Head And Neck Squamous Cell Carcinoma Cells after Irradiation

“…In particular, CD44v6 has come under intense scrutiny, and the expression of CD44v6 is associated with increased tumor progression and metastatic potential [19] . A report demonstrated that CD44v3 is present at higher levels in head and neck cancers than in normal tissues [20] ; another report demonstrated that there is no difference between the expression of CD44s and CD44v6 [21] and that the precise role of CD44 is not yet known. Furthermore, CD44 has been suggested to be a cancer stem cell marker in head and neck cancer [22] .…”