Bone Metastasis Of Cancer Cells Research Articles

Inhibition of tumor formation by snake venom disintegrin

The metastasis of tumor cells to bone involves migration, invasion and adhesion to bone. Breast and prostate cancer cells have predilection for spreading to bone. Snake venom-derived arginine-glycine-aspartic acid (RGD)-containing disintegrins (e.g. rhodostomin) have been demonstrated to inhibit cell adhesion. Here, we found that rhodostomin inhibited the adhesion of breast and prostate carcinoma cells to both unmineralized and mineralized bone extracellular matrices in a dose-dependent manner, without affecting the viability of tumor cells. In addition, rhodostomin also inhibited the migration and invasion of breast and prostate carcinoma cells. It specifically inhibited the binding of monoclonal antibody (MoAb) 7E3, which recognizes integrin αvβ3, to tumor cells, but not those of other MoAbs against other integrin subunits such as α2, α3, α5 and β1. As breast cancer cells MDA-MB-231 were locally injected into tibia in nude mice, histological examination of the tibia of control group revealed that most of the cancellous bone had been replaced by the breast cancer cells after 28 days' inoculation. In contrast, co-administration of trigramin with cancer cells markedly inhibited tumor growth and bone destruction. Taken together, disintegrins strongly inhibit the adhesion, migration, invasion of tumor cells and also tumor growth of human breast cancer cells in bone as well. Therefore, disintegrins may be developed as alternate therapy for bone metastasis of cancer cells.

Structure-Based Design of Specific Cathepsin Inhibitors and Their Application to Protection of Bone Metastases of Cancer Cells

We report the antihypercalcemic and antimetastatic effects of CLIK-148 in vivo, which is a specific inhibitor of cathepsin L. The decalcification during bone absorption is followed by the degradation of type-1 collagen by osteoclastic cathepsins. Tumor-bearing osteoclasts or TNF-α-activated osteoclasts secrete large amounts of cysteine proteases, especially procathepsin L, which powerfully degrade type-1 collagen leading to tumor-associated bone absorption and release of bone calcium. The bone pit formations in vitro, which are caused by osteoclasts derived from human bone marrow cells activated by RANKL and M-CSF and also by mice osteoclasts activated by TNF-α, are significantly prevented by CLIK-148 treatment. We evaluated the in vivo inhibitory effect of malignant hypercalcemia induced by LJC-1 human mandibular cancer inoculation by CLIK-148 treatment, and the CLIK-148 treatment significantly protected against the tumor-induced hypercalcemia. On the protection of bone metastasis of colon 26 PMF-15 implanted to mouse calvaria, CLIK-148 treatment significantly inhibited calvaria bone absorption (direct metastasis). The CLIK-148 treatment also reduced distant bone metastasis to the femur and tibia of melanoma A375 tumors implanted into the left ventricle of the heart.

Suppression of interleukin-11-mediated bone resorption by cyclooxygenases inhibitors.

We previously found that human melanoma (A375M) and human breast cancer (MDA-MB-231) cells formed osteolytic bone metastasis in vivo. These cancer cells produced interleukin-11 (IL-11) by themselves and stimulated its production from osteoblasts. Interleukin-11 could increase the number of osteoclasts and raise the calcium concentration in the medium of neonatal murine calvaria organ culture, indicating bone resorption in vitro. Therefore, IL-11 could play an important role in the promotion of osteolysis at the site of bone metastasis. In the present study, we used the calvaria culture system to try to clarify the mechanisms of IL-11-mediated bone resorption. The murine calvaria expressed both the specificity-determining alpha subunit and the signal-transducing beta subunit (gp130) of the IL-11 receptor. When IL-11 was added to the calvaria culture, the concentrations of prostaglandin E2 (PGE2) was elevated. Pretreatment of calvaria with cyclooxygenases inhibitors (e.g., indomethacin, NS-398, and dexamethasone) suppressed the production of PGE2 and the bone resorption induced by IL-11. Addition of exogenous PGE2 overcame the inhibitory effect of cyclooxygenases inhibitors and promoted bone resorption. These results indicate that IL-11 promotes bone resorption through a PGE2 synthesis-dependent mechanism and that cyclooxygenases inhibitors could be interesting drugs to suppress IL-11-mediated osteolytic bone metastasis of cancer cells.