Hyaluronan-CD44 Interaction Activates Stem Cell Marker Nanog, Stat-3-mediated MDR1 Gene Expression, and Ankyrin-regulated Multidrug Efflux in Breast and Ovarian Tumor Cells

Abstract

Hyaluronan (HA) is a major glycosaminoglycan in the extracellular matrix whose expression is tightly linked to multidrug resistance and tumor progression. In this study we investigated HA-induced interaction between CD44 (a HA receptor) and Nanog (an embryonic stem cell transcription factor) in both human breast tumor cells (MCF-7 cells) and human ovarian tumor cells (SK-OV-3.ipl cells). Using a specific primer pair to amplify Nanog by reverse transcriptase-PCR, we detected the expression of Nanog transcript in both tumor cell lines. In addition, our results reveal that HA binding to these tumor cells promotes Nanog protein association with CD44 followed by Nanog activation and the expression of pluripotent stem cell regulators (e.g. Rex1 and Sox2). Nanog also forms a complex with the "signal transducer and activator of transcription protein 3" (Stat-3) in the nucleus leading to Stat-3-specific transcriptional activation and multidrug transporter, MDR1 (P-glycoprotein) gene expression. Furthermore, we observed that HA-CD44 interaction induces ankyrin (a cytoskeletal protein) binding to MDR1 resulting in the efflux of chemotherapeutic drugs (e.g. doxorubicin and paclitaxel (Taxol)) and chemoresistance in these tumor cells. Overexpression of Nanog by transfecting tumor cells with Nanog cDNA stimulates Stat-3 transcriptional activation, MDR1 overexpression, and multidrug resistance. Down regulation of Nanog signaling or ankyrin function (by transfecting tumor cells with Nanog small interfering RNA or ankyrin repeat domain cDNA) not only blocks HA/CD44-mediated tumor cell behaviors but also enhances chemosensitivity. Taken together, these findings suggest that targeting HA/CD44-mediated Nanog-Stat-3 signaling pathways and ankyrin/cytoskeleton function may represent a novel approach to overcome chemotherapy resistance in some breast and ovarian tumor cells displaying stem cell marker properties during tumor progression.Multidrug resistance frequently contributes to the failure of chemotherapeutic drug treatments in patients diagnosed with solid tumors such as breast and ovarian cancers (1). It is now certain that oncogenic signaling and cytoskeleton function are directly involved in chemotherapeutic drug resistance and tumor progression (2-4). A number of studies have aimed at identifying those molecules that are expressed specifically by epithelial tumor cells and correlate with metastatic behavior and chemoresistance. Among such molecules is hyaluronan (HA), 2 a major component in the extracellular matrix (ECM) of most mammalian tissues (5, 6). HA is a nonsulfated, unbranched glycosaminoglycan consisting of the repeating disaccharide units, D-glucuronic acid and N-acetyl-D-glucosamine (5, 6). HA is synthesized by specific HA synthases (6, 7) and digested into various smaller sized molecules by various hyaluronidases (8). It is well known that HA is enriched in many types of tumors (9, 10). In cancer patients, HA concentrations are usually higher in malignant tumors than in corresponding benign or normal tissues. Ac...

Diagnostic relevance of overexpressed Nanog gene in early lung cancers

“…We have demonstrated for the first time that Nanog mRNA expression can be detected with high sensitivity and specificity in lung cancer tissues. In addition, experiments on siRNA revealed that the constitutive expression of Nanog in cancer cells maintains proliferation ability; this is consistent with the observation that the overexpression of the Nanog gene promotes tumour cell growth (11). With regard to the expression of Nanog in cancers, Ezeh et al showed that the Nanog protein is expressed in tissues that were obtained from 2 breast cancer patients (12).…”

Hyaluronic Acid Mediated Enrichment of CD44 Expressing Glioblastoma Stem Cells in U251MG Xenograft Mouse Model

“…HA-CD44 interaction was proved to activate Nanog which is principally [20] involved in the stem cell maintenance and self-renewal in the ES cells [21,22]. The activation of CD44 through the PKCε phosphorylates Nanog, with or without the association of Stat3 regulates the expression of other pluripotent, tumorigenic and multidrug resistance genes [21]. Nanog has shown to regulate the expression of Sox2, Oct3/4, and Rex1, the prominent pluripotent transcription factors during embryonic stem cell pluripotency.…”

“…These transcription factors are found to be over-expressed in several of the cancers and were used to identify cancer stem cell-like cells in glioblastoma [19]. HA-CD44 interaction was proved to activate Nanog which is principally [20] involved in the stem cell maintenance and self-renewal in the ES cells [21,22]. The activation of CD44 through the PKCε phosphorylates Nanog, with or without the association of Stat3 regulates the expression of other pluripotent, tumorigenic and multidrug resistance genes [21].…”

Coexpression of invasive markers (uPA, CD44) and multiple drug-resistance proteins (MDR1, MRP2) is correlated with epithelial ovarian cancer progression

“…Specifically, HA binding to CD44 is capable of stimulating MDR1 expression and drug resistance in breast tumour cells through ErbB2 signalling and PI3 kinase/Akt-related survival pathways (Misra et al, 2005). Bourguignon et al (2008) have recently shown that HA -CD44 interaction activates stem cell marker Nanog, Stat-3-mediated MDR1 gene expression and ankyrin-regulated multidrug efflux in breast and ovarian tumour cells. However, a direct link of phenotypes between drug resistance and invasion or metastasis in epithelial ovarian cancer (EOC) is still unclear.…”