A 2020, 'Combined administration of a small-molecule inhibitor of TRAF6 and Docetaxel reduces breast cancer skeletal metastasis and osteolysis: Running title : TRAF6/NFkB inhibition reduced breast cancer metastasis', Cancer letters.

Background: Cancer-associated bone disease is a serious complication in bone sarcomas and metastatic carcinomas of breast and prostate origin. Monoacylglycerol lipase (MAGL) is an enzyme of the endocannabinoid system, and is responsible for the degradation of the most abundant endocannabinoid in bone, 2-arachidonoyl glycerol (2AG). Methods: The effects of the verified MAGL inhibitor on bone remodelling were assessed in healthy mice and in mouse models of bone disease caused by prostate and breast cancers and osteosarcoma. Findings: JZL184 reduced osteolytic bone metastasis in mouse models of breast and prostate cancers, and inhibited skeletal tumour growth, metastasis and the formation of ectopic bone in models of osteosarcoma. Additionally, JZL184 suppressed cachexia and prolonged survival in mice injected with metastatic osteosarcoma and osteotropic cancer cells. Functional and histological analysis revealed that the osteoprotective action of JZL184 in cancer models is predominately due to inhibition of tumour growth and metastasis. In the absence of cancer, however, exposure to JZL184 exerts a paradoxical reduction of bone volume via an effect that is mediated by both Cnr1 and Cnr2 cannabinoid receptors. Interpretation: MAGL inhibitors such as JZL184, or its novel analogues, may be of value in the treatment of bone disease caused by primary bone cancer and bone metastasis, however, activation of the skeletal endocannabinoid system may limit their usefulness as osteoprotective agents.

Background Cancer-associated bone disease is a serious complication in bone sarcomas and metastatic carcinomas of breast and prostate origin. Monoacylglycerol lipase (MAGL) is an enzyme of the endocannabinoid system, and is responsible for the degradation of the most abundant endocannabinoid in bone, 2-arachidonoyl glycerol (2AG). Methods The effects of the verified MAGL inhibitor on bone remodelling were assessed in healthy mice and in mouse models of bone disease caused by prostate and breast cancers and osteosarcoma. Findings JZL184 reduced osteolytic bone metastasis in mouse models of breast and prostate cancers, and inhibited skeletal tumour growth, metastasis and the formation of ectopic bone in models of osteosarcoma. Additionally, JZL184 suppressed cachexia and prolonged survival in mice injected with metastatic osteosarcoma and osteotropic cancer cells. Functional and histological analysis revealed that the osteoprotective action of JZL184 in cancer models is predominately due to inhibition of tumour growth and metastasis. In the absence of cancer, however, exposure to JZL184 exerts a paradoxical reduction of bone volume via an effect that is mediated by both Cnr1 and Cnr2 cannabinoid receptors. Interpretation MAGL inhibitors such as JZL184, or its novel analogues, may be of value in the treatment of bone disease caused by primary bone cancer and bone metastasis, however, activation of the skeletal endocannabinoid system may limit their usefulness as osteoprotective agents.

NFκB is implicated in cancer and bone remodelling, and we have recently reported that the verified NFκB inhibitor Parthenolide (PTN) reduced osteolysis and skeletal tumour growth in models of metastatic breast cancer. Here, we took advantage of in vitro and ex vivo bone cell and organ cultures to study the effects of PTN on the ability of prostate cancer cells and their derived factors to regulate bone cell activity and osteolysis. PTN inhibited the in vitro growth of a panel of human, mouse and rat prostate cancer cells in a concentration-dependent manner with a varying degree of potency. In prostate cancer cell-osteoclast co-cultures, the rat Mat-Ly-Lu, but not human PC3 or mouse RM1-BT, enhanced RANKL stimulated osteoclast formation and PTN reduced these effects without affecting prostate cancer cell viability. In the absence of cancer cells, PTN reduced the support of Mat-Ly-Lu conditioned medium for the adhesion and spreading of osteoclast precursors, and survival of mature osteoclasts. Pre-exposure of osteoblasts to PTN prior to the addition of conditioned medium from Mat-Ly-Lu cells suppressed their ability to support the formation of osteoclasts by inhibition of RANKL/OPG ratio. PTN enhanced the ability of Mat-Ly-Lu derived factors to increase calvarial osteoblast differentiation and growth. Ex vivo, PTN enhanced bone volume in calvaria organ-Mat-Ly-Lu cell co-culture, without affecting Mat-Ly-Lu viability or apoptosis. Mechanistic studies in osteoclasts and osteoblasts confirmed that PTN inhibit NFκB activation related to derived factors from Mat-Ly-Lu cells. Collectively, these findings suggest that pharmacological inhibition of the skeletal NFκB signalling pathway reduces prostate cancer related osteolysis, but further studies in the therapeutic implications of NFκB inhibition in cells of the osteoblastic lineage are needed.

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Due to their biocompatibility and high adsorption properties, mesoporous silica nanoparticles (MSN) represent one of the most promising systems for drug delivery. Previous investigations have shown that both surface functionalization and external stimuli may act in a synergistic way to deliver drugs from nanoparticles. One such stimulus is underwater shock wave-induced sonoporation, a physical method known to transiently permeabilize cell membranes. However, there are some concerns regarding the feasibility to apply shock waves in the presence of dense nanoparticles. In this work, bioinspired supramolecular MSN were prepared by self-assembly of cationic liposomes with 200 nm MCM-41 type silica nanoparticles. The effects of the biomimetic coat on cargo stability, adherence to HEK-293 cells, and shock wave-mediated delivery of plasmid deoxyribonucleic acid were addressed. Compared to bare MSN, structures displaying a lipid coat showed higher cargo retention. Adherence to cell surface was only achieved with a cationic lipid surface, which was related to higher efficient delivery of MSN cargoes, including the release of a green fluorescent protein-codifying transgene. Unexpectedly, MSN covered with a biomimetic coat were found to protect cells from the exacerbated mortality observed after exposure of cells to shock waves in the presence of bare MSN. Further research will be required to understand the mechanisms involved in this combined strategy, which paves the way for the exploration of dense nanoparticles in the field of shock wave-mediated drug delivery.

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