Sphingosine 1-Phosphate Receptor 4 Uses HER2 (ERBB2) to Regulate Extracellular Signal Regulated Kinase-1/2 in MDA-MB-453 Breast Cancer Cells

Abstract

We demonstrate here that the bioactive lipid sphingosine 1-phosphate (S1P) uses sphingosine 1-phosphate receptor 4 (S1P 4 ) and human epidermal growth factor receptor 2 (HER2) to stimulate the extracellular signal regulated protein kinase 1/2 (ERK-1/2) pathway in MDA-MB-453 cells. This was based on several lines of evidence. First, the S1P stimulation of ERK-1/2 was abolished by JTE013, which we show here is an S1P 2/4 antagonist and reduced by siRNA knockdown of S1P 4 . Second, the S1P-stimulated activation of ERK-1/2 was almost completely abolished by a HER2 inhibitor (ErbB2 inhibitor II) and reduced by siRNA knockdown of HER2 expression. Third, phyto-S1P, which is an S1P 4 agonist, stimulated ERK-1/2 activation in an S1P 4 -and HER2-dependent manner. Fourth, FTY720 phosphate, which is an agonist at S1P 1,3,4,5 but not S1P 2 stimulated activation of ERK-1/2. Fifth, S1P stimulated the tyrosine phosphorylation of HER2, which was reduced by JTE013. HER2 which is an orphan receptor tyrosine kinase is the preferred dimerization partner of the EGF receptor. However, EGF-stimulated activation of ERK-1/2 was not affected by siRNA knockdown of HER2 or by ErbB2 (epidermal growth factor receptor 2 (or HER2)) inhibitor II in MDA-MB-453 cells. Moreover, S1P-stimulated activation of ERK-1/2 does not require an EGF receptor. Thus, S1P and EGF function in a mutually exclusive manner. In conclusion, the magnitude of the signaling gain on the ERK-1/2 pathway produced in response to S1P can be increased by HER2 in MDA-MB-453 cells. The linkage of S1P with an oncogene suggests that S1P and specifically S1P 4 may have an important role in breast cancer progression.There is increasing evidence that suggests a role for the bioactive lipid sphingosine 1-phosphate (S1P) 2 in breast cancer. S1P binds to a family of five GPCR, termed S1P n (where n ϭ 1-5), that are differentially coupled to heterotrimeric G proteins (G i , G q , and G 12/13 ) to regulate various effectors such as MAP kinases linked to diverse cellular processes such as proliferation, cell survival, and differentiation (1-13). The specificity of signaling in terms of which kinase modules are activated is dependent upon the receptor sub-type involved and is cell context-specific. S1P is produced by the enzyme sphingosine kinase (SK), which catalyzes the phosphorylation of sphingosine to produce S1P. SK (which exists as two isoforms termed SK1 and SK2) is activated by agonists such as antigen, plateletderived growth factor, nerve growth factor, tumor necrosis factor ␣, and epidermal growth factor (EGF), resulting in an increase in intracellular S1P. SK1 activation and/or translocation is regulated by phosphorylation catalyzed by ERK-1/2 and by CIB1 (calcium and integrin-binding protein 1) (14,15). S1P has an important role in breast cancer cells in terms of regulating survival, proliferation, and migration (16 -18). For instance, ectopic expression of SK1 increased S1P levels, estrogen-dependent tumorigenesis, and blocked apoptosis of MCF-7 cells induced by anticancer drug...

Sphingosine-1-phosphate promotes expansion of cancer stem cells via S1PR3 by a ligand-independent Notch activation

“…S1PR2 expression was lower in the ALDH-positive cell population compared with MCF-7 cells, and other types of S1PR are yet to be detected in MCF-7 cells ( Supplementary Fig. 2) 19,20 . Stimulation with S1P increased the proportion of ALDH-positive cell population in a dose-dependent manner, with a maximal response observed at 100 nM (Fig.…”

Behavior of Sphingosine 1-Phosphate Receptor 4 Gene Expression in Patients with Neuroblastoma

“…Long et al, in their study on cell lines, reported that S1P4 induced cellular migration. 21 In the literature, there was no study clarifying the high levels of S1P4 gene expression in neuroblastoma patients. The interaction between various cancer cell types and S1P4 gene expression are described in various studies of cell lines.…”

Involvement of Sphingosine Kinases/Sphingosine-1-Phosphate (S1P)/S1P Receptors in Breast Cancer Subtypes

“…In addition, inhibition of SphK1 reduced S1P/S1P4-induced activation of ERK1/2 and altered HER2 trafficking in these cells [18]. Furthermore, inhibition of SphK1 reduced and treatment with a S1P 4 agonist, phyto-S1P, stimulated ERK activation via a mechanism that involves HER2, suggesting synergistic interactions between S1P 4 and HER2 in these cells [18,69]. In contrast to the findings in ER-positive cells where HER2 and SphK1 interact in a negative feedback mechanism to induce tolerance against cancer progression, the interactions of SphK1, S1P and S1P 4 with HER2 suggest sphingolipids act together with HER2 to enhance ER-negative breast cancer progressions.…”

“…These cells express abundant S1P 3 , small quantities of S1P 2/4 and very limited S1P 1/5 . Despite predominant expression of S1P 3 , the less abundant S1P 4 interact with HER2 to regulate S1P-induced ERK [69]. This was evidenced by reduced S1P-stimulated ERK activity through independent downregulation of S1P 4 and HER2 expressions.…”

“…In these cells, SphK1 expression is increased in a HER-2 dependent manner compared to MCF-7 cells with control vector [57]. SphK1 in turn leads to reduction in HER2 expression and limits p21-activated protein kinase1 (p65 PAK1, downstream of HER2 and upstream regulator of ERK) and ERK expressions, both of which are known to induce migratory phenotype upon S1P treatment [59,69]. Upon S1P stimulus, HER2-overexpressed MCF-7 cells hold the capability of phosphorylating ERK in a S1P 3 -dependent mechanism [57].…”