Stimulators of Mineralization Limit the Invasive Phenotype of Human Osteosarcoma Cells by a Mechanism Involving Impaired Invadopodia Formation

Abstract

BackgroundOsteosarcoma (OS) is a highly aggressive bone cancer affecting children and young adults. Growing evidence connects the invasive potential of OS cells with their ability to form invadopodia (structures specialized in extracellular matrix proteolysis).ResultsIn this study, we tested the hypothesis that commonly used in vitro stimulators of mineralization limit the invadopodia formation in OS cells. Here we examined the invasive potential of human osteoblast-like cells (Saos-2) and osteolytic-like (143B) OS cells treated with the stimulators of mineralization (ascorbic acid and B-glycerophosphate) and observed a significant difference in response of the tested cells to the treatment. In contrast to 143B cells, osteoblast-like cells developed a mineralization phenotype that was accompanied by a decreased proliferation rate, prolongation of the cell cycle progression and apoptosis. On the other hand, stimulators of mineralization limited osteolytic-like OS cell invasiveness into collagen matrix. We are the first to evidence the ability of 143B cells to degrade extracellular matrix to be driven by invadopodia. Herein, we show that this ability of osteolytic-like cells in vitro is limited by stimulators of mineralization.ConclusionsOur study demonstrates that mineralization competency determines the invasive potential of cancer cells. A better understanding of the molecular mechanisms by which stimulators of mineralization regulate and execute invadopodia formation would reveal novel clinical targets for treating osteosarcoma.

Differing responses of osteogenic cell lines to β-glycerophosphate

“…Additionally, there was an upregulated expression of PHEX and MEPE 9 both associated with decreased mineral production and differentiation into osteocytes. In contrast, Cmoch et al 7 observed increased mineralisation by Saos-2 cells at a similar β-Gly concentration. However, whilst many studies use β-Gly, some authors recommend avoiding the use of ~ 10 mM β-Gly as it causes non-physiological levels of extracellular phosphate that can alter normal osteogenic gene transcription 10 .…”

“…Valenti et al 6 showed Asc-induced osteogenic differentiation at up to 250 µM with no signs of apoptosis below 750 µM in relatively undifferentiated osteoblast-like MG-63 cells. Whereas Cmoch et al 7 described activated matrix mineralisation accompanied by apoptosis in more fully differentiated Saos-2 cells exposed to 283 µM Asc and 7.5 mM β-Gly. The latter suggested a possible role of β-Gly in apoptosis which was not addressed by the authors.…”

Potential protective role of Grainyhead‐like genes in the development of clear cell renal cell carcinoma

“…ab139418) according to the manufacturer's instructions. Crystal violet staining and annexin V flow cytometry analyses were carried out as described before . For soft agar assay, we followed the protocol published online by Joseph Provost, University of San Diego, California, USA; link: http://home.sandiego.edu/~josephprovost/Research.html, accessed March 2017.…”

Increased phosphorylation of eIF2α in chronic myeloid leukemia cells stimulates secretion of matrix modifying enzymes

“…Migration was assayed by wound healing experiments as previously described [ 63 ]. Time-lapse observations were performed for 48h using Leica AF7000 Live Imaging System (Leica Microsystems) microscope equipped with an environmental chamber, and a 10x/0.40NA objective.…”