Oridonin Could Inhibit Inflammation and T-cell Immunoglobulin and Mucin-3/Galectin-9 (TIM-3/Gal-9) Autocrine Loop in the Acute Myeloid Leukemia Cell Line (U937) as Compared to Doxorubicin

The T-cell immunoglobulin and mucin-3 (TIM-3)/galectin-9 (Gal-9) autocrine loop is an indispensable signaling in acute myeloid leukemia (AML) cells, which induces their self-renewal through activation of nuclear factor-kappa b (NF-kB) and β-catenin pathways. In this study, we evaluated the effects of oridonin and doxorubicin on the TIM-3/Gal-9 autocrine loop. We also evaluated oridonin anti-inflammatory and anti-cancer properties on U937 cells, as an AML cell line in comparison to doxorubicin as a common anthracycline drug for AML treatment. Cell counting kit-8 (CCK-8) was applied to evaluate the cytotoxicity of oridonin and doxorubicin on U937 cells and also to determine the impact of galectin-9 (Gal-9) on their proliferation. The effects of oridonin and doxorubicin on Gal-9, TIM-3, and interleukin-1β (IL-1β) gene expression were determined by real-time polymerase chain reaction (RT-PCR). The Gal-9 secretion level was measured by enzyme-linked immunosorbent assay (ELISA) and activation of NF-kB pathway was assessed by western blotting. In a dose-dependent manner, oridonin and doxorubicin were capable to eradicate U937 cells while Gal-9 expanded them. Following the treatment of U937 cells with oridonin, the expression of Gal-9, TIM-3, and IL-1β genes was down-regulated, and the Gal-9 secretion and NF-kB phosphorylation were diminished, whereas doxorubicin increased all of these factors. Doxorubicin is a common treatment agent in AML, but it may induce inflammation and upregulate the TIM3/Gal-9 autocrine loop, consequently can enhance the possibility of disease relapse. Meanwhile, oridonin is capable to inhibit the essential signaling pathways in AML cells and reduce the inflammation and expansion of tumor cells and postpone AML recurrence.