This bystander effect occurs when the therapeutic protein binds to certain receptors on nearby cancer cells. This activity in breast cancer cells is another mechanism by which INGN 241 exerts its multiple anticancer activities, which also include inhibition of angiogenesis, induction of apoptosis (cell death) and inhibition of cell growth and metastasis.
The studies were conducted in laboratory models of breast cancer. Treatment of human breast cancer cells with INGN 241 arrested cell growth and increased cell killing. Both of these anti-cancer effects correlated with the secretion of MDA-7 protein. The mda-7 gene is the active component of INGN 241.
Addition of MDA-7 protein to human breast cancer cells not treated with INGN 241 also resulted in tumor cell death. This suggests that MDA-7 protein secreted by cells treated with INGN 241 can kill nearby untreated cells. Cancer cell killing was blocked by the addition of antibodies against MDA-7 or the MDA-7 receptor, suggesting that this effect is mediated through the binding of MDA-7 to its receptor.
The data were presented at the thirteenth International Conference on Gene Therapy of Cancer.
“Cancer is a difficult disease to treat because even a single remaining cancer cell can lead to the relapse or metastasis of cancer,” said Dr Mingzhong Zheng, research scientist at Introgen and an author of the study. “The bystander effect observed with secreted MDA-7 protein may be important in the treatment of cancer because it may increase our ability to eliminate as many cancer cells as possible, even cells that have not been directly treated with INGN 241.”