Stem cell marker (Nanog) and Stat-3 signaling promote MicroRNA-21 expression and chemoresistance in hyaluronan CD44-activated head and neck squamous cell carcinoma cells

• Published in: Oncogene Vol. 31; no. 2; pp. 149 - 160
• Main Authors: Bourguignon, L Y W, Earle, C, Wong, G, Spevak, C C, Krueger, K
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12.01.2012; Nature Publishing Group
• Subjects: Apoptosis; Carcinoma, Squamous Cell - genetics; Carcinoma, Squamous Cell - metabolism; Carcinoma, Squamous Cell - pathology; CD44 antigen; Cell Biology; Cell Line, Tumor; Cell Nucleus - metabolism; Cell survival; Chemoresistance; Chemotherapy; Chromatin; Drug resistance; Drug Resistance, Neoplasm; Gene expression; Genetic aspects; Head & neck cancer; Head and neck cancer; Head and Neck Neoplasms - genetics; Head and Neck Neoplasms - metabolism; Head and Neck Neoplasms - pathology; Homeodomain Proteins - metabolism; Human Genetics; Humans; hyaluronan; Hyaluronan Receptors - metabolism; Hyaluronic Acid - metabolism; IAP protein; Immunoprecipitation; Internal Medicine; Medicine; Medicine & Public Health; MicroRNA; MicroRNAs - genetics; MicroRNAs - metabolism; miRNA; Nanog Homeobox Protein; Nuclear transport; Oncology; original-article; Physiological aspects; Promoter Regions, Genetic; Promoters; Signal Transduction; siRNA; squamous cell carcinoma; Stat3 protein; STAT3 Transcription Factor - metabolism; Stem cells; Transcription activation; Tumor cells; Tumor suppressor genes; Tumors; Tyrosine; United States; nanog; Stat-3; miR-21; hyaluronan; CD44; head & neck cancer
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/onc.2011.222

MicroRNAs are often associated with the pathogenesis of many cancers, including head and neck squamous cell carcinoma (HNSCC). In particular, microRNA-21 (miR-21) appears to have a critical role in tumor cell survival, chemoresistance and HNSCC progression. In this study, we investigated matrix hyaluronan (HA)-induced CD44 (a primary HA receptor) interaction with the stem cell markers, Nanog and Stat-3, in HNSCC cells (HSC-3 cells). Our results indicate that HA binding to CD44 promotes Nanog–Stat-3 (also tyrosine phosphorylated Stat-3) complex formation, nuclear translocation and transcriptional activation. Further analyses reveal that miR-21 is controlled by an upstream promoter containing Stat-3 binding site(s), while chromatin immunoprecipitation assays demonstrate that stimulation of miR-21 expression by HA/CD44 signaling is Nanog/Stat-3-dependent in HNSCC cells. This process results in a decrease of a tumor suppressor protein (PDCD4), and an upregulation of i nhibitors of the apoptosis family of proteins (IAPs) as well as chemoresistance in HSC-3 cells. Treatment of HSC-3 cells with Nanog- and/or Stat-3-specific small interfering RNAs effectively blocks HA-mediated Nanog–Stat-3 signaling events, abrogates miR-21 production and increases PDCD4 expression. Subsequently, this Nanog–Stat-3 signaling inhibition causes downregulation of survival protein (IAP) expression and enhancement of chemosensitivity. To further evaluate the role of miR-21 in tumor cell-specific functions, HSC-3 cells were also transfected with a specific anti-miR-21 inhibitor in order to silence miR-21 expression and block its target functions. Our results demonstrate that anti-miR-21 inhibitor not only upregulates PDCD4 expression but also decreases IAP expression and enhances chemosensitivity in HA-treated HNSCC cells. Together, these findings indicate that the HA-induced CD44 interaction with Nanog and Stat-3 has a pivotal role in miR-21 production leading to PDCD4 reduction, IAP upregulation and chemoresistance in HNSCC cells. This novel Nanog/Stat-3 signaling pathway-specific mechanism involved in miR-21 production is significant for the formation of future intervention strategies in the treatment of HA/CD44-activated HNSCC.