ANTICOPPER TREATMENT INHIBITS PSEUDOPODIAL PROTRUSION AND THE INVASIVE SPREAD OF 9L GLIOSARCOMA CELLS IN THE RAT-BRAIN

The copper ion, a cofactor of angiogenesis, is sequestered in human brain tumors and the adjacent brain. The invasive spread of neoplastic cells has been linked to angiogenesis and involves similar mechanisms of migration and tumor-matrix interaction. In this report, copper depletion inhibited the infiltrative spread of the normally invasive 9L gliosarcoma. Twenty male Fischer 344 rats were each injected with 1 x 105 9L cells; 10 rats were treated with a low-copper diet and penicillamine. In the normocupremic control rats, a 'diffuse' invasive pattern was observed in all 10 animals. In the hypocupremic group, a 'nodular' pattern, with a discrete border between tumor and brain, was found in 7 of 10 rats (P<0.01). In a second experiment, the brains of 16 tumor-bearing rats were studied by electron microscopy. In the 8 normocupremic control rats, cytoplasmic extensions and pseudopodial protrusions, cytological markers of invasive cells, were prominent at the tumor-brain interface. In striking contrast, pseudopodia were absent along the border of the tumors in the 8 hypocupremic rats. These findings suggest a biological role of copper in the neoplastic spread of brain tumor cells. Pharmacological and metabolic alteration of the cellular microenvironment to inhibit invasiveness represents a novel therapeutic approach, especially for tumors of the brain in which malignancy is a function of regional invasiveness.