SphK2/S1P promotes metastasis in triple negative breast cancer through PAK1/LIMK1/Cofilin1 signaling pathway

Abstract Background: Triple negative breast cancer (TNBC) features poor prognosis which partialy attributed to the high metastasis rate. However, there is no effective target for systemic TNBC therapy due to the absence of estrogen, progesterone, and human epidermal growth factor 2 receptors (ER, PR, HER-2) up to date. In the present study, we evaluated the role of sphingosine kinase 2 (SphK2) and its catalysate sphingosine-1-phosphate (S1P) in TNBC metastasis, and the antitumor activity of SphK2 specific inhibitor ABC294640 in TNBC metastasis. Methods: The function of SphK2 and S1P in migration of TNBC cells was evaluated by Transwell migration and wound healing assays. The molecular mechanisms of SphK2/S1P mediating TNBC metastasis were investigated using cell line establishment, western blot, histological examination and immunohistochemistry assays. The antitumor activity of ABC294640 was examined in TNBC lung metastasis model in vivo. Results: SphK2 regulated TNBC cells migration through the generation of S1P. Targeting SphK2 with ABC294640 inhibited TNBC lung metastasis in vivo . p21-activated kinase 1 (PAK1), p-Lin-11/Isl-1/Mec-3 kinase 1 (LIMK1) and Cofilin1 was the downstream signaling cascade of SphK2/S1P. Inhibition of PAK1 suppressed SphK2/S1P induced TNBC cells migration. Concusion: SphK2/S1P promotes TNBC metastasis through the activation of the PAK1/LIMK1/Cofilin1 signaling pathway. ABC294640 potently inhibits TNBC metastasis in vivo which could be developed as a novel agent for the clinical treatment of TNBC.