Overexpression of the Cytokine Osteopontin Identifies Aggressive Laryngeal Squamous Cell Carcinomas and Enhances Carcinoma Cell Proliferation and Invasiveness

Abstract

Purpose: Osteopontin is a secreted cytokine that binds to the cell surface CD44v6 receptor.We studied osteopontin and CD44v6 expression in laryngeal squamous cell carcinomas and correlated osteopontin expression levels with clinicopathologic tumor features. Experimental Design: We used immunohistochemistry, immunoblotting, and reverse transcription-PCR to study osteopontin expression in 58 laryngeal squamous cell carcinomas. Cultured squamous carcinoma cells were treated with exogenous osteopontin or with RNA interference to knockdown osteopontin expression. Results: Osteopontin expression was higher in all the invasive carcinomas than in patientmatched normal mucosa. Its expression levels were significantly correlated with tumor stage and grade and with the presence of lymph node and distant metastases. Osteopontin positivity was negatively correlated with overall survival (P = 0.03). Osteopontin expression was paralleled by intense cell surface reactivity for CD44v6. Treatment of squamous carcinoma cells with recombinant osteopontin sharply increased proliferation and Matrigel invasion in comparison with the untreated cells parallel to activation of the mitogen-activated protein kinase/extracellular signalregulated kinase kinase/mitogen-activated protein kinase signaling cascade. Osteopontin knockdown by RNA interference, anti-CD44 antibodies, and mitogen-activated protein kinase/ extracellular signal-regulated kinase kinase inhibition prevented these effects. Conclusions: These results identify osteopontin as a marker and a potential therapeutic target in cases of aggressive laryngeal squamous cell carcinomas.Head and neck squamous cell carcinoma (HNSCC) is the sixth most frequent cancer. Laryngeal squamous cell carcinoma (LSCC) is the most common HNSCC (1 -3). Notwithstanding primary prevention, screening, surgical treatment, and radiotherapy, the long-term survival rate of LSCC patients has remained substantially unchanged in the last two decades (4, 5). Stage and histologic grade are prognostic factors in LSCC but do not always distinguish between high-risk and low-risk patients (1-5). Various biological prognostic markers have been identified for LSCC and other HNSCC types: mutation in the p53 tumor suppressor gene (6), amplification of cyclin D1 (7, 8), overexpression of the epidermal growth factor receptor (9) and vascular endothelial growth factor (10), and reduced expression of the CIP/KIP cell cycle inhibitory proteins (11). However, little is known about the molecular mechanisms that govern the establishment and maintenance of the LSCC neoplastic phenotype.Osteopontin, also known as secreted phosphoprotein 1, is a highly acidic calcium-binding glycosylated phosphoprotein. It is a cytokine (early T lymphocyte antigen-1 or interleukin-28) that regulates T helper cell-1 function (12, 13). In addition, osteopontin binds to the cell surface receptors a v -or h 1 -containing integrins and CD44 (14, 15), thereby supporting chemotaxis, attachment, and migration of many epithelial cell types (16,17)...

Secreted phosphoprotein 1 (osteopontin) is expressed by stromal macrophages in cyclic and pregnant endometrium of mice, but is induced by estrogen in luminal epithelium during conceptus attachment for implantation

“…Both cell proliferation and apoptosis, which profoundly impact conceptus development during the peri-implantation period, are influenced by Spp1 (Khan et al 2002, Celetti et al 2005, Caers et al 2006. Further, it is well documented that Spp1 binds integrins to influence cell attachment and migration (Senger & Perruzzi 1996, Smith & Giachelli 1998, Al-Shamiri et al 2005, Celetti et al 2005, Kolb et al 2005, Caers et al 2006. In addition, due to its flexible nature in solution and the prominence of polymerized Spp1 cross-linked by tissue transglutaminase, self-assembly of protein complexes to expose multiple RGD sequences for simultaneous interaction with integrins on trophectoderm and LE to bridge conceptus to uterus is highly plausible , Goldsmith et al 2002.…”

Prognostic Value of Osteopontin in Patients Treated with Primary Radiotherapy for Head and Neck Cancer

“…OPN expression was found to be 58% by Coppola et al (2004) 67% by Devoll (1999) and 93% by Celetti et al (2005). These rates indicate that OPN is a marker frequently expressed in SCHNC.…”

Segment-specific targeting via RNA interference mediates down-regulation of OPN expression in hepatocellular carcinoma cells

“…In this, RISC is positioned by base pairing to homologous mRNA transcripts, so that target gene transcription is blocked, generating the corresponding loss of functional phenotype. Therefore, this process has also been called posttranscriptional gene silencing Celetti et al, 2005). RNAi technology has been widely applied to various fields in the life sciences, and is a revolutionary scientific development.…”