This study found that oridonin, a natural diterpenoid purified from Rabdosia rubescens, inhibited growth of multiple myeloma (MM; U266, RPMI8226), acute lymphoblastic T-cell leukemia (Jurkat), and adult T-cell leukemia (MT-1) cells with an effective dose that inhibited 50% of target cells (ED50) ranging from 0.75 to 2.7 Mg/ mL. Terminal deoxynucleotidyltransferase–mediated dUTP nick end labeling staining showed that oridonin caused apoptosis of MT-1 cells in a time-dependent manner. We explored effects of oridonin on antiapoptotic Bcl-2 family members and found that it down-regulated levels of Mcl-1 and BCL-xL, but not Bcl-2 protein, in both MT-1 and RPMI8226 cells. Further studies found that oridonin inhibited nuclear factor-KB (NF-kB) DNA-binding activity in these cells as measured by luciferase reporter gene, ELISA-based, and electrophoretic mobility shift assays. Oridonin also blocked tumor necrosis factor-α– and lipopolysaccharide-stimulated NF-KB activity in Jurkat cells as well as RAW264.7 murine macrophages. Of note, oridonin decreased survival of freshly isolated adult T-cell leukemia (three samples), acute lymphoblastic leukemia (one sample), chronic lymphocytic leukemia (one sample), non-Hodgkin’s lymphoma (three samples), and MM (four samples) cells from patients in association with inhibition of NF-kB DNA-binding activity. On the other hand, oridonin did not affect survival of normal lymphoid cells from healthy volunteers. Taken together, oridonin might be useful as adjunctive therapy for individuals with lymphoid malignancies, including the lethal disease adult T-cell leukemia. [Mol Cancer Ther 2005; 4(4): 578–86]

Septic shock is the most common cause of death in intensive care units, and no effective treatment is available at present. Lipopolysaccharide (LPS) is the primary mediator of Gramnegative sepsis by inducing the production of macrophagederived proinflammatory cytokines, in which activation of nuclear factor-kB (NF-kB) plays an important role. PC-SPES is an eight-herb mixture active against a variety of malignancies, including prostate cancer and leukemia. In this study, we demonstrated that PC-SPES inhibited the LPS-induced NF-kB reporter activity in RAW264.7 macrophages. Electrophoretic mobility shift assay showed that PC-SPES inhibited the binding of NF-kB to specific DNA sequences; however, it did not affect either degradation of inhibitory kBα or nuclear translocation of NF-kB. Also, we explored the effect of PCSPES on LPS-induced mitogen-activated protein (MAP) kinase signaling; PC-SPES did not affect LPS-induced phosphorylation of MAP kinases, including c-Jun NH2-terminal kinase, p38, and extracellular signal-regulated kinase 1/2. Moreover, PC-SPES decreased the production of proinflammatory cytokines and inducible enzymes, such as tumor necrosis factor (TNF) α, interleukin (IL)-1β, IL-6, cyclooxy-genase-2, as well as inducible nitric-oxide synthase in RAW264.7 macrophages and peritoneal macrophages from C57BL/6 mice after the cells were stimulated by either LPS or LPS and interferon-γ. Furthermore, PC-SPES rescued C57BL/6 mice from death caused by LPS-induced septic shock in conjunction with decreased serum levels of TNFα and IL-1β. Together, PC-SPES is a potent inhibitor of NF-kB and might be useful for the treatment of sepsis and inflammatory diseases.

Proteasome inhibitor PS-341 induces growth arrest and apoptosis of multiple myeloma (MM) cells via inactivation of nuclear factor κB (NF-κB) in vitro. In addition, recent clinical studies of PS-341 have demonstrated some objective responses in individuals with relapsed, refractory MM. However, the activity of PS-341 against non-hematological malignancies remains to be fully elucidated. In this study, we found that PS-341 induced growth arrest and apoptosis of androgen-dependent human prostate cancer LNCaP cells in conjunction with markedly up-regulated levels of p21waf1 and p53. In addition, we found that PS-341 down-regulated both 5α- dihydrotestosterone (DHT)- and interleukin-6 (IL-6)-induced expression of prostate-specific antigen (PSA) as measured by western blot analysis. PS-341 down-regulated basal levels of the androgen receptor (AR) in the nucleus; however, it did not affect DHT-induced nuclear translocation of AR in these cells. Reporter assays using a series of promoters of the PSA gene showed that down-regulation of PSA by PS-341 was caused by inhibition of the transcriptional activity of the androgen receptor response element (ARE) in these cells. Taken together, the results indicate that PS-341 induced growth arrest and apoptosis of LNCaP cells by blockade of the AR signaling pathway. The proteasome may be a molecular target for treatment of a variety of cancers including prostate cancer. (Cancer Sci 2004; 95: 271–275)

Proteasome inhibitor PS-341 induces growth arrest and apoptosis of multiple myeloma (MM) cells via inactivation of NF-κB in vitro and has afforded some objective responses in individuals with relapsed, refractory MM. However, the activity of PS-341 against non-hematological malignancies remains to be fully elucidated. In this study, we found that PS-341 induced growth arrest and apoptosis of NCI-H520 and -H460 non-small cell lung cancer (NSCLC) cells in conjunction with markedly up-regulated levels of p21waf1 and p53, and down-regulation of bcl-2 protein in these cells. Also, PS-341 caused phosphorylation of c-Jun NH2-terminal kinase (JNK) and c-Jun, and enhanced AP-1/DNA binding activities in these cells as measured by western blotting and enzyme-linked immunosorbent assay (ELISA), respectively. Interestingly, when the JNK/ c-Jun/AP-1 signal pathway was disrupted by the JNK inhibitor SP600125, the ability of PS-341 to inhibit the growth of NSCLC cells and to up-regulate the levels of p21waf1 in these cells was blunted, but the expression of p53 was sustained at a high level, suggesting that the JNK/c-Jun/AP-1 signal pathway might mediate the anti-lung cancer effects of PS-341, with p21waf1 playing the central role. Thus, PS-341 might be useful for the treatment of individuals with NSCLC. (Cancer Sci 2004; 95: 176–180)

ZD6474 (Zactima, AstraZeneca, Macclesfield, UK) is an orally available, small-molecule inhibitor of vascular endothelial growth factor receptor-2 and epidermal growth factor receptor tyrosine kinases, with additional activity versus rearranged during transfection (RET). This study explored the effect of ZD6474 in gastrointestinal stromal tumor-T1 (GIST-T1) cells that possess a gain of function mutation in exon 11 of the c-KIT gene. ZD6474 induced growth arrest and apoptosis of GIST-T1 cells in association with blockade of c-Kit and its downstream effectors, including Akt and extracellular signal-regulated kinase (ERK). ZD6474 treatment also blocked the mammalian target of rapamycin (mTOR), which lies downstream of Akt and ERK. Interestingly, when ZD6474 was combined with sunitinib (SU11248; Sutent, Pfizer, Kalamazoo, MI, USA), a class III and V receptor tyrosine kinase inhibitor, the ZD6474-mediated growth inhibition was potentiated in association with further down-regulation of the mTOR targets p-p70S6K and p-4E-BP-1. The combination of ZD6474 and sunitinib should be investigated further. (Cancer Sci 2006; 97: 1404–1409)