Timosaponin AIII (TAIII), a steroidal saponin, exerts potent anti-tumor activity in various cancers, especially breast cancer. However, the concrete molecular mechanisms of TAIII against breast cancer are still unclear. Here, we find that TAIII triggers DNA damage, leads to G2/M arrest, and ultimately induces apoptosis in breast cancer both in vitro and in vivo. TAIII induced G2/M phase arrest and apoptosis in MDA-MB-231 and MCF7 cells accompanied with down-regulation of CyclinB1, Cdc2 and Cdc25C. Further data showed that the ATM/Chk2 and p38 pathways were activated representing by up-regulated levels of p-H2A.X and p-p38, which indicated an induction of DNA damage by TAIII, leading to cell cycle arrest and apoptosis. The effects of TAIII were further confirmed by employing inhibitors of ATM and p38 pathways. In vivo, TAIII suppressed the growth of subcutaneous xenograft tumor without obvious toxicity, which indicated by Ki67 and TUNEL analysis. Data also showed that TAIII stimulated the ATM/Chk2 and p38 MAPK pathways in vivo, which in consistent with the effects in vitro. Hence, our data demonstrate that TAIII triggers DNA damage and activates ATM/Chk2 and p38 MAPK pathways, and then induces G2/M phase arrest and apoptosis in breast cancer, which provide theoretical evidence for TAIII utilized as drug against breast cancer.

Inflammatory burden is a primary cellular event in many liver diseases, and the overall capacity of drug elimination is decreased. PXR (pregnane X receptor) and CAR (constitutive androstane receptor) are two master regulators of genes encoding drug-metabolizing enzymes and transporters. DEC1 (differentiated embryonic chondrocyte-expressed gene 1) is a ligand-independent transcription factor and reportedly is induced by many inflammatory cytokines including IL-6. In this study, we used primary hepatocytes (human and mouse) as well as HepG2 cell line and demonstrated that IL-6 increased DEC1 expression and decreased the expressions of PXR, CAR, and their target genes. Overexpression of DEC1 had similar effect as IL-6 on the expression of these genes, and knockdown of DEC1 reversed their downregulation by IL-6. Interestingly, neither IL-6 nor DEC1 altered the expression of RXRα, a common dimerization partner for many nuclear receptors including PXR and CAR. Instead, DEC1 was found to interact with RXRα and IL-6 enhanced the interaction. These results conclude that DEC1 uses diverse mechanisms of action and supports IL-6 downregulation of drug-elimination genes and their regulators.

1. In this study, we report that gambogic acid (GA), a promising anticancer agent, potentiates clopidogrel-induced apoptosis and attenuates CPT-11-induced apoptosis by down-regulating human carboxylesterase (CES) 1 and -2 via ERK and p38 MAPK pathway activation, which provides a molecular explanation linking the effect of drug combination directly to the decreased capacity of hydrolytic biotransformation. 2. The expression levels of CES1 and CES2 decreased significantly in a concentration- and time-dependent manner in response to GA in Huh7 and HepG2 cells; hydrolytic activity was also reduced. 3. The results showed that pretreatment with GA potentiated clopidogrel-induced apoptosis by down-regulating CES1. Moreover, the GA-mediated repression of CES2 attenuated CPT-11-induced apoptosis. 4. Furthermore, the ERK and p38 MAPK pathways were involved in the GA-mediated down-regulation of CES1 and CES2. 5. Taken together, our data suggest that GA is a potent repressor of CES1 and CES2 and that combination with GA will affect the metabolism of drugs containing ester bonds.

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases and affects almost 1% of the population. Differentiated embryo-chondrocyte expressed gene-1 (DEC1) has been associated with both osteogenesis and osteoclastogenesis. RA condition is marked by inflammatory hyperplasia, and DEC1 is known to support inflammatory reactions and implicated in antiapoptosis and cell invasion. Here, our goal was to test the hypothesis that DEC1 enhances RA development induced by collagen-induced arthritis (CIA), a well-recognized protocol for developing RA animal models. DEC1^+/+ and DEC1^-/- mice were subjected to CIA protocol, and the development of RA condition was monitored. We found that CIA robustly induced RA phenotypes (e.g., synovial hyperplasia) and greatly increased the expression of proinflammatory cytokines such as TNF-α. However, these changes were detected in DEC1^+/+ but not DEC1^-/- mice. Interestingly, these very cytokines strongly induced DEC1, and such a dual role of DEC1, as an inducer for and being induced by proinflammatory cytokines, constitutes a DEC1-amplifying circuit for inflammation. Knockdown of DEC1 in human MH7A cells strongly decreased cell migration and invasion as well as the expression of genes related to RA phenotypes. The combination of DEC1-directed migration and invasion in vitro with synovial hyperplasia in vivo mechanistically establishes cellular bases on how DEC1 is involved in the development of RA phenotypes. In addition to inflammatory signaling, DEC1 functionally interacted with PI3KCA(p110α)/Akt/GSK3β, Wnt/β-catenin, and NFATc1. Such engagement in multiple signaling pathways suggests that DEC1 plays coordinated and integral roles in developing RA, one of the most common autoimmune diseases.

Bone metastasis is the primary cause of mortality in breast cancer (BC) patients. This study elucidates the functional role of DEC1 (differentiated embryonic chondrocyte expressed gene 1) in promoting BC bone metastasis. Analysis of patient-derived samples and public databases revealed significant upregulation of DEC1 and CXCR4 in breast tumors compared to adjacent normal tissues, with elevated levels correlating with increased metastatic potential, suggesting their synergistic involvement in BC progression. Intracardiac injection experiments demonstrated that 4T1-WT cells induced more severe osteolysis and larger metastatic lesions than 4T1-DEC1-KD cells. In MDA-MB-231 cells, DEC1 overexpression (OE) upregulated CXCR4 and proliferation/migration-related genes, whereas DEC1 knockdown (KD) suppressed these effects. Notably, AMD3100 (a CXCR4 antagonist) partially reversed the DEC1-OE-induced upregulation of CXCR4 and associated pro-metastatic genes. Mechanistically, DEC1 was found to bind the CXCR4 promoter region (-230 to -326) and activate its transcription, corroborated by ChIP-seq data. Furthermore, pharmacological inhibition of AKT (LY294002) or JAK2 (AZD1480), but not ERK (PD98059), attenuated DEC1-mediated CXCR4 upregulation, although all three inhibitors mitigated DEC1-driven migration-related gene expression. Additionally, DEC1 enhanced CXCL12 secretion from mesenchymal stromal cells and osteoblasts, amplifying the CXCR4/CXCL12 axis within the bone microenvironment. Collectively, our findings demonstrate that DEC1 promotes breast cancer (BC) bone metastasis by directly transactivating CXCR4 expression, providing a molecular basis for targeting DEC1 to prevent and treat BC bone metastasis.