Enhanced chemosensitization of anoikis-resistant melanoma cells through syndecan-2 upregulation upon anchorage independency

Abstract

Syndecan family proteins are heparan sulfate proteoglycans, which involved in various cellular activities and associating with metastatic potential and chemosensitivity of tumor cells. Melanoma is one of malignant tumors with poor prognosis upon metastasis. Previously, we had shown that melanoma cells remained survived under cell detachment, which was similar to the initial steps of tumor metastasis. Downregulation of syndecan-1 and upregulation of syndecan-2 in melanoma A375 cells were observed by different suspension conditions. Specific gene alterations also increased melanoma malignancy under anchorage independency. Thus, we would like to investigate in further the role of specific gene alteration, so that it could be used to develop novel strategy to treat melanoma.In this paper, we found that syndecan-2 expression level as well the kinase phosphorylation levels increased upon anchorage independency. The pathway to regulate syndecan-2 expression shifted from PKCα/β-dependent under adhesion into PKCδ-dependent under cell suspension. Manipulation of syndecan-2 expression showed that PI3K and ERK phosphorylation as well the migratory ability increased with increased syndecan-2 expression level. In addition, suspended melanoma cells were more sensitive to chemoagents, which correlated with syndecan-2 overexpression, PI3K and ERK activations, serum level, and the presence of glycosaminoglycans.In conclusion, we showed upregulation of syndecan-2 in anoikis-resistant melanoma cells enhanced chemosensitivity through PI3K and ERK activation. This observation would support and refine the strategy of adjuvant chemotherapy to overcome metastatic melanoma.

Anchorage independence altered vasculogenic phenotype of melanoma cells through downregulation in aminopeptidase N /syndecan-1/integrin β4 axis

“…Since SDC1 level also affected the laminin-binding ability and it was downregulated in suspended melanoma, we checked whether SDC1 expression level would affect laminin-binding integrin expression. As seen in Figure 4A , the transfection of SDC1-specific shRNA suppressed SDC1 expression, but upregulated SDC2 expression, which was consistent with our previous observation [ 2 ]. Integrin β3 expression was upregulated, while integrin β2 expression was marginally reduced by SDC1-specific shRNA transfection.…”

“…We simulated the status of melanoma cells that suffered from detachment stress by suspension cell culture. The detachment stress altered the phenotype of cell invasiveness [ 1 ], promoted tumor malignancy [ 3 ], and enhanced chemosensitivity [ 2 ] of melanoma cells. Those pieces of evidence suggested anchorage-independence of malignant melanoma would alter gene/protein expression through several key proteins and pathways.…”

“…Anchorage impairments led to the loss of invasiveness that were driven by PKCδ-mediated downregulation of syndecan-1 (SDC1), reduced expression of matrix metalloprotease-2 (MMP2) protein, and reduced laminin-binding ability [ 1 ]. However, the chemosensitivity of melanoma cells was increased by suspension culture that upregulated syndecan-2 (SDC2) protein expression by PI3K and ERK pathway activation [ 2 ]. This was also associated with elevated PKCδ activation.…”

Anoikis Resistance as a Further Trait of Acidic-Adapted Melanoma Cells

“…PI3 kinase-AKT and ERK activation is reported to characterize melanoma cells upon anchorage independency and syndecan 2 (SDC2) increased expression. SDC2 is also associated with a higher expression of migratory and melanin synthesis [40].…”

Drug-selected population in melanoma A2058 cells as melanoma stem-like cells retained angiogenic features – the potential roles of heparan-sulfate binding ANGPTL4 protein

“…For cell pretreatment with antibody, trypsinized cells were incubated with desired amount of ANGPTL4 antibody for 30 min before plating. For cell pretreatment with chemical inhibitors, drug-selected melanoma cells were pretreated with 50 mM sodium chlorate [ 63 , 64 ] or 2 mM xylopyranoide [ 65 ] for 24 hrs before trypsinization. Melanoma cells (in 1x10 5 cells) were then evenly seeded onto Matrigel surface.…”