Human breast adenocarcinoma (MDA-231) and human lung squamous cell carcinoma (Hara) do not have the ability to cause bone resorption by themselves during the establishment of bone metastasis.

Osteolysis is an important process in the establishment of bone metastasis. The role which cancer cells play in this process is not fully understood. In this study, we first established a reproducible in vivo bone metastasis model using two types of tumor cells, human breast adenocarcinoma (MDA-231) and human lung squamous cell carcinoma (Hara cells), and examined in vitro characteristics of the tumor cells. Tumor cells injected into the left heart ventricle of nude mice preferentially metastasized to bone, 6 weeks after the inoculation. Histological observation of the bone metastatic lesion showed that tumor cells invaded the bone marrow, and osteoclasts adjacent to fibroblasts were actively resorbing the bone matrix. In vitro analysis of the tumor cells showed that MDA-231 cells express cathepsin K, matrix metalloproteinase 9 (MMP-9), and membrane type-1 matrix metalloproteinase (MT1-MMP), all of which are believed to play an important role in osteoclastic bone resorption. In contrast, Hara cells do not express cathepsin K and MT1-MMP. MMP-9 was expressed at a low level. To assess the osteolytic activity of the tumor cells, an in vitro pit assay was performed. The rabbit osteoclasts formed numerous pits on a dentin slice after 18 h of incubation, whereas tumor cells by themselves did not. Taken together, we conclude that MDA-231 and Hara cells, which metastasize to the bone in vivo, do not have enough ability to achieve bone resorption by themselves, but rather achieve it through activation of fibroblast like cells and osteoclasts.

Dihydroquercetin (DHQ) ameliorated concanavalin A-induced mouse experimental fulminant hepatitis and enhanced HO-1 expression through MAPK/Nrf2 antioxidant pathway in RAW cells.

Autoimmune hepatitis represents a ubiquitous human health problem and has a poor prognosis. Dihydroquercetin (DHQ), a well-known antioxidant, significantly inhibits fulminant hepatitis through anti-oxidant and anti-inflammation mechanisms. In this study, we show that administration of DHQ ameliorated concanavalin A (ConA)-induced mouse liver injury by increasing the survival rate, reducing the serum ALT and AST level, preventing histopathological injuries and decreasing pro-inflammatory cytokine mRNA expression in hepatic tissue. As macrophages/Kupffer cells in oxidative stress and pro-inflammatory mediators play an important role in the pathogenesis of immune-mediated hepatitis, we further exposed mouse RAW264 macrophage cell lines to ConA in vitro and found that DHQ significantly inhibited mRNA expression and secretion of IFN-γ and TNF-α in cell culture supernatant. In addition, DHQ significantly enhanced heme oxygenase-1 (HO-1) expression in a dose- and time-dependent manner via increased Nrf2 expression in cytoplasm and nuclear translocation. Furthermore, DHQ enhanced phosphorylation of three members of the mitogen-activated protein kinase (MAPK) family, and cell treatment with MEK/ERK (PD98059), p38 (SB203580) and JNK (SP600125) inhibitors reduced DHQ-induced HO-1 expression. These results indicate that DHQ possesses hepatoprotective properties against ConA-induced liver injury, which are attributed to its ability to scavenge oxidative stress and to inhibit the release of inflammatory mediators via upregulation of HO-1 activity through the MAPK/Nrf2 signaling pathway in macrophages/Kupffer cells.