S1P-S1PR3-RAS promotes the progression of S1PR3 hi TAL1 + T-cell acute lymphoblastic leukemia that can be effectively inhibited by an S1PR3 antagonist

TAL1 + T-cell acute lymphoblastic leukemia (T-ALL) is a distinct subtype of leukemia with poor outcomes. Through the cooperation of co-activators, including RUNX1, GATA3, and MYB, the TAL1 oncoprotein extends the immature thymocytes with autonomy and plays an important role in the development of T-ALL. However, this process is not yet well understood. Here, by investigating the transcriptome and prognosis of T-ALL from multiple cohorts, we found that S1PR3 was highly expressed in a subset of TAL1 + T-ALL (S1PR3 hi TAL1 + T-ALL), which showed poor outcomes. Through pharmacological and genetic methods, we identified a specific survival-supporting role of S1P-S1PR3 in TAL1 + T-ALL cells. In T-ALL cells, TAL1-RUNX1 up-regulated the expression of S1PR3 by binding to the enhancer region of S1PR3 gene. With hyperactivated S1P-S1PR3, T-ALL cells grew rapidly, partly by activating the KRAS signal. Finally, we assessed S1PR3 inhibitor TY-52156 in T-ALL patient-derived xenografts (PDXs) mouse model. We found that TY-52156 attenuated leukemia progression efficiently and extended the lifespan of S1PR3 hi TAL1 + T-ALL xenografts. Our findings demonstrate that S1PR3 plays an important oncogenic role in S1PR3 hi TAL1 + T-ALL and may serve as a promising therapeutic target.