TY - JOUR AB - Our previous study has shown that CD9 knockdown could suppress cell proliferation, adhesion, migration and invasion, and promote apoptosis and the cytotoxicity of chemotherapeutic drugs in the B‑lineage acute lymphoblastic leukemia (B‑ALL) cell line SUP‑B15. In this study, we further investigated the molecular mechanism underlying the effects of CD9 on leukemic cell progression and the efficacy of chemotherapeutic agents in B‑ALL cells. Using the CD9‑knockdown SUP‑B15 cells, we demonstrated that the silencing of the CD9 gene significantly reduced the expression of phosphorylated‑phosphatidylinositol‑3 kinase (p‑PI3K), phosphorylated‑protein kinase B (p‑AKT), P‑glycoprotein (P‑gp), multidrug resistance‑associated protein 1 (MRP1), breast cancer resistance protein (BCRP), matrix metalloproteinase 2 (MMP2) and phosphorylated‑focal adhesion kinase (p‑FAK). In addition, glutathione S‑transferase (GST) pull‑down assay showed the binding between CD9 and both PI3K‑p85α and PI3K‑p85β in vitro, while co‑immunoprecipitation assay showed the binding between CD9 and both PI3K‑p85α and PI3K‑p85β in vivo. Furthermore, the PI3K/AKT inhibitor LY294002 mirrored the effects of CD9 knockdown in SUP‑B15 cells. Taken together, these findings demonstrated that CD9 activates the PI3K/AKT signaling pathway through direct interaction with PI3K‑p85 in B‑ALL cells. Our data provide evidence for the inhibition of the PI3K/AKT pathway as a novel therapeutic option in CD9 antigen‑positive B‑ALL. AD - Department of Hematology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325000, P.R. China Department of Paediatrics, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR 999077, P.R. China AU - Shi,Yi-Fen AU - Huang,Zi-Yang AU - Huang,Yi-Sha AU - Dong,Ru-Jiao AU - Xing,Chong-Yun AU - Yu,Kang AU - Leung,Kam,Tong AU - Feng,Jian-Hua DA - 2021/07/01 DO - 10.3892/or.2021.8091 IS - 1 JO - Oncol Rep KW - B‑lineage acute lymphoblastic leukemia CD9 PI3K‑p85 PI3K/AKT signaling pathway SUP‑B15 cells PY - 2021 SN - 1021-335X 1791-2431 SP - 140 ST - Interaction between CD9 and PI3K‑p85 activates the PI3K/AKT signaling pathway in B‑lineage acute lymphoblastic leukemia T2 - Oncology Reports TI - Interaction between CD9 and PI3K‑p85 activates the PI3K/AKT signaling pathway in B‑lineage acute lymphoblastic leukemia UR - https://doi.org/10.3892/or.2021.8091 VL - 46 ER -