Short-term dietary copper deficiency does not inhibit angiogenesis in tumours implanted in striated muscle

A Diet Lacking Selenium, but Not Zinc, Copper or Manganese, Induces Anticancer Activity in Mice with Metastatic Cancers

Selenium, zinc, copper, and manganese are essential components of antioxidant enzymes involved in the elimination of reactive oxygen species (ROS). Given that cancer cells produce high levels of ROS and the accumulation of ROS can lead to cell death, cancer cells may be susceptible to strategies that reduce ROS elimination. In this work, we prepared several artificial diets that contained normal carbohydrate, protein, and lipid levels but lacked selenium, zinc, copper, or manganese. The anticancer activity of these diets was examined in a metastatic ovarian cancer model, established by injecting ID8 Trp53-/- murine ovarian cancer cells into the peritoneal cavity of C57BL/6JRj mice. Treatments started 15 days later and consisted of replacing a normal diet with one of the artificial diets for several weeks. A significant improvement in mice survival was observed when the normal diet was replaced with the selenium-free diet. Diets lacking zinc, copper, or manganese showed no significant impact on mice survival. All diets were very well tolerated. The anticancer efficacy of a diet lacking selenium was confirmed in mice with metastatic colon cancer and in mice with metastatic triple-negative breast cancer. These results suggest that diets lacking selenium hold potential for the treatment of metastatic cancers.

Rapid copper acquisition by developing murine mesothelioma: decreasing bioavailable copper slows tumor growth, normalizes vessels and promotes T cell infiltration

Copper, an essential trace element acquired through nutrition, is an important co-factor for pro-angiogenic factors including vascular endothelial growth factor (VEGF). Decreasing bioavailable copper has been used as an anti-angiogenic and anti-cancer strategy with promising results. However, the role of copper and its potential as a therapy in mesothelioma is not yet well understood. Therefore, we monitored copper levels in progressing murine mesothelioma tumors and analyzed the effects of lowering bioavailable copper. Copper levels in tumors and organs were assayed using atomic absorption spectrophotometry. Mesothelioma tumors rapidly sequestered copper at early stages of development, the copper was then dispersed throughout growing tumor tissues. These data imply that copper uptake may play an important role in early tumor development. Lowering bioavailable copper using the copper chelators, penicillamine, trientine or tetrathiomolybdate, slowed in vivo mesothelioma growth but did not provide any cures similar to using cisplatin chemotherapy or anti-VEGF receptor antibody therapy. The impact of copper lowering on tumor blood vessels and tumor infiltrating T cells was measured using flow cytometry and confocal microscopy. Copper lowering was associated with reduced tumor vessel diameter, reduced endothelial cell proliferation (reduced Ki67 expression) and lower surface ICAM/CD54 expression implying reduced endothelial cell activation, in a process similar to endothelial normalization. Copper lowering was also associated with a CD4(+) T cell infiltrate. In conclusion, these data suggest copper lowering is a potentially useful anti-mesothelioma treatment strategy that slows tumor growth to provide a window of opportunity for inclusion of other treatment modalities to improve patient outcomes.

A requirement for copper in angiogenesis

Although two decades have passed since copper was shown to stimulate blood vessel formation in the avascular cornea of rabbits, only recently have clinical trials established that Cu privation by diet or by Cu chelators diminishes a tumor's ability to mount an angiogenic response. These data have shed new light on the functional role of Cu in microvessel development and, of equal importance, stimulated new nutritional models of cancer therapeutic intervention.

Copper chelation inhibits tumor angiogenesis in the experimental 9L gliosarcoma model

To investigate the effects of copper (Cu)-depletion diet and D-penicillamine treatment (CDPT) on both tumor growth and angiogenesis, we studied Fischer-344 rats in which 9L gliosarcoma cells had been subcutaneously implanted. We focused primarily on the alteration of Cu contents and the vascular density. Compared with the normal diet group, the CDPT group showed a significant reduction of tumor weight and a decrease in Cu concentration. Furthermore, the CDPT group demonstrated smaller blood vessels with significantly lower vascular density. This decrease of tumor growth was achieved by angiosuppression. Our study indicated that CDPT selectively caused Cu chelation from the tumor tissue; the normal brain tissue did not show lower Cu concentration after the treatment. The prevention of tumor angiogenesis by this method may be very useful in cancer therapy and may help elucidate the microenvironmental mechanisms for cancer cells.