Introduction of pro-interleukin-16 inhibits T-lymphoblastic leukemia growth in mice

Purpose Pro-interleukin-16 (pro-IL-16) is the precursor to mature interleukin-16 (IL-16) protein. Previous studies have demonstrated that pro-IL-16 can function as a regulator of cell cycle. A number of human T-cell leukemia and lymphoma cell lines are pro-IL-16 deficient. Intracellular expression of pro-IL-16 causes these cell lines to become quiescent, implicating loss of pro-IL-16 as a contributory step in T-cell malignancy. Therefore, we tested whether or not reintroduction of pro-IL-16 into solid tumors in mice could halt tumor growth. Methods MOLT-4 lymphoblastic leukemia cells were stably transfected with a dsRed-tomato virus and were injected subcutaneously into NOD/SCID/gamma chain-knockout mice. Tumor growth was monitored with an in vivo imaging system. A pro-IL-16-GFP fusion virus or control GFP only virus was injected into the tumors, and mice were monitored for 1 week. Results Injection of the pro-IL-16-containing lentivirus inhibited growth of established MOLT-4 tumors in mice. Tumor explants exhibited diminished proliferative capacity. Conclusions Our data support the concept that restoration of pro-IL-16 expression in malignant T cells may have therapeutic value.