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Hepatocellular carcinoma (HCC) has been known as the second common leading cancer worldwide, as it responds poorly to both chemotherapy and medication. Triptolide (TP), a diterpenoid triepoxide, is a promising treatment agent for its effective anticancer effect on multiple cancers including HCC. However, its clinical application has been limited owing to its severe systemic toxicities, low solubility, and fast elimination in the body. Therefore, to overcome the above obstacles, photo-activatable liposomes (LP) integrated with both photosensitizer Ce6 and chemotherapeutic drug TP (TP/Ce6-LP) was designed in the pursuit of controlled drug release and synergetic photodynamic therapy in HCC therapy. The TP encapsulated in liposomes accumulated to the tumor site due to the enhanced permeability and retention (EPR) effect. Under laser irradiation, the photosensitizer Ce6 generated reactive oxygen species (ROS) and further oxidized the unsaturated phospholipids. In this way, the liposomes were destroyed to release TP. TP/Ce6-LP with NIR laser irradiation (TP/Ce6-LP+L) showed the best anti-tumor effect both in vitro and in vivo on a patient derived tumor xenograft of HCC (PDXHCC). TP/Ce6-LP significantly reduced the side effects of TP. Furthermore, TP/Ce6-LP+L induced apoptosis through a caspase-3/PARP signaling pathway. Overall, TP/Ce6-LP+L is a novel potential treatment option in halting HCC progression with attenuated toxicity.

In chronic infectious diseases caused by gram-negative bacteria, such as osteomyelitis, septic arthritis, and periodontitis, osteoclastic activity is enhanced with elevated inflammation, which disturbs the bone homeostasis and results in osteolysis. Lipopolysaccharide (LPS), as a bacteria product, plays an important role in this process. Recent evidence shows that an antimalarial drug artesunate attenuates LPS-induced osteolysis independent of RANKL. In this study we evaluated the effects of artesunate on LPS-induced osteoclastogenesis in vitro and femur osteolysis in vivo, and explored the mechanisms underlying the effects of artesunate on LPS-induced osteoclast differentiation independent of RANKL. In preosteoclastic RAW264.7 cells, we found that artesunate (1.56−12.5 μM) dose dependently inhibited LPS-induced osteoclast formation accompanied by suppressing LPS-stimulated osteoclast-related gene expression (Fra-2, TRAP, Cathepsin K, β3-integrin, DC-STAMP, and Atp6v0d2). We showed that artesunate (3.125−12.5 µM) inhibited LPS-stimulated nuclear factor of activated T cells c1 (NFATc1) but not NF-κB transcriptional activity; artesunate (6.25, 12.5 μM) significantly inhibited LPS-stimulated NFATc1 protein expression. Furthermore, artesunate treatment markedly suppressed LPS-induced Ca 2+ influx, and decreased the expression of PP2B-Aα (calcineurin) and pPLCγ1 in the cells. In addition, artesunate treatment significantly decreased the expression of upstream signals TLR4 and TRAF6 during LPS-induced osteoclastogenesis. Administration of artesunate (10 mg/kg, ip) for 8 days effectively inhibited serum TNF-α levels and ameliorated LPS (5 mg/kg, ip)-induced inflammatory bone loss in vivo. Taken together, artesunate attenuates LPS-induced inflammatory osteoclastogenesis by inhibiting the expression of TLR4/TRAF6 and the downstream PLCγ1-Ca 2+ -NFATc1 signaling pathway. Artesunate is a valuable choice to treat bone loss induced by gram-negative bacteria infection or inflammation in RANKL-independent pathway.

Background and Purpose: Osteoclasts are unique cells to absorb bone. Targeting osteoclast differentiation is a therapeutic strategy for osteolytic diseases. Natural marine products have already become important sources of new drugs. The naturally occurring nitrobenzoyl sesquiterpenoids first identified from marine fungi in 1998 are bioactive compounds with a special structure, but their pharmacological functions are largely unknown. Here, we investigated six marine fungus-derived nitrobenzoyl sesquiterpenoids on osteoclastogenesis and elucidated the mechanisms. Experimental Approach: Compounds were first tested by RANKL-induced NF-κB luciferase activity and osteoclastic TRAP assay, followed by molecular docking to characterize the structure-activity relationship. The effects and mechanisms of the most potent nitrobenzoyl sesquiterpenoid on RANKL-induced osteoclastogenesis and bone resorption were further evaluated in vitro. Micro-CT and histology analysis were used to assess the prevention of bone destruction by nitrobenzoyl sesquiterpenoids in vivo. Key Results: Nitrobenzoyl sesquiterpenoid 4, with a nitrobenzoyl moiety at C-14 and a hydroxyl group at C-9, was the most active compound on NF-κB activity and osteoclastogenesis. Consequently, nitrobenzoyl sesquiterpenoid 4 exhibited suppression of RANKL-induced osteoclastogenesis and bone resorption from 0.5 μM. It blocked RANKL-induced IκBa phosphorylation, NF-κB p65 and RelB nuclear translocation, NFATc1 activation, reduced DC-STAMP but not c-Fos expression during osteoclastogenesis in vitro. Nitrobenzoyl sesquiterpenoid 4 also ameliorated LPSinduced osteolysis in vivo. Conclusion and Implications: These results highlighted nitrobenzoyl sesquiterpenoid 4 as a novel inhibitor of osteoclast differentiation. This marine-derived sesquiterpenoid is a promising lead compound for the treatment of osteolytic diseases.

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