Silencing Osteopontin Expression Inhibits Proliferation, Invasion and Induce Altered Protein Expression in Melanoma Cells

Abstract

Osteopontin (OPN) is a multifunctional phosphoprotein that is expressed in different types of cancers, including melanoma. OPN overexpression is associated with tumor progression and metastasis formation; however, the role of OPN in cell invasion and metastasis formation is not completely understood. In this study we aimed to define OPN expression in melanoma tissues and cell lines and investigate the effect of OPN expression on cell proliferation and invasion after inhibiting OPN expression with small interfering RNA (siRNA). OPN gene expression was determined by qRT-PCR, while protein expression was examined using a Proteome Profiler Oncology Array. siRNA-mediated OPN knockdown led to decreased OPN expression in melanoma cell lines, which was associated with decreased cell proliferation and invasion. Proteome profile analysis revealed significantly different protein expression between the original and transfected cell lines. The altered expression of the differently expressed proteins was validated at the mRNA level. Furthermore, OPN-specific siRNA was able to reduce OPN expression and inhibit the invasiveness of melanoma cells. Our results revealed for the first time that silencing the OPN gene influences proliferation and invasion of melanoma cells by effecting EGFR, tenascin C, survivin, galectin-3 and enolase 2 expression. To predict protein-protein interactions along with putative pathways we used STRING analysis for the differentially expressed proteins. These proteins formed multiple clusters, including extracellular matrix organization, regulation of angiogenesis, cell death and cell migration, PI3K-Akt, MAPK and focal adhesion signaling pathways. Taken together these data suggest that OPN might be an ideal target for drug development and therapies.

Gene Expression Patterns of Osteopontin Isoforms and Integrins in Malignant Melanoma

“…Osteopontin (OPN), a multifunctional protein, has been widely studied as a promising biomarker in various types of tumors for monitoring tumor progression, invasion, metastasis formation and drug resistance (13,25). The association between the aberrant expression of osteopontin and melanoma invasion, metastasis formation, and radio/drug resistance has been recently described (1,3,(25)(26)(27). The biological functions of tumor-associated gene products are extensively regulated via pre-and posttranscriptional modifications, resulting in alternative splicing of OPN.…”

Osteopontin as a Biomarker in Chronic Kidney Disease

“…It was initially found in bone, but later research revealed that it is expressed in several tissues [2,3]. OPN mediates a multitude of biological processes and plays significant roles in biomineralization, and a number of physiological processes involved in cellular homeostasis, as well as in pathologies such as chronic inflammation and tumor biology [4][5][6]. OPN was also known as early T-lymphocyte activation 1 protein, and bone sialoprotein 1 [7] and was reported to activate immune cells, including T-cells, B-cells, macrophages, natural killer and Kupffer cells [1,[8][9][10].…”

Identification of Key Biomarkers and Candidate Molecules in Non-Small-Cell Lung Cancer by Integrated Bioinformatics Analysis

“…SPP1 mediates chemotherapy resistance in prostate cancer [ 41 ]. In addition, some scholars have demonstrated that inhibition of SPP1 expression can inhibit the progression of melanoma [ 42 ]. These evidences suggest that SPP1 plays a role in promoting the progression of various cancers.…”