Shyr-Te Ju, PhD
Expression and function of Fas ligand in apoptosis and chemotaxis
Immunotherapy of cancers with broadly human tumor-specific scFv-FasL fusion proteins:
The Ju laboratory has generated two scFv-FasL and two scFv-TRAIL fusion proteins. The scFv used are derived from cc49 and TAL-6 mAb each has specificity against an antigen that are broadly expressed on various human cancer cells. They have characterized these fusion proteins biochemically and immunologically. The fusion proteins are present in soluble form in culture supernatants of transfected cells but are heterogeneous in micro-aggregates of various molecular sizes between 350 kd to ~1,400 kd. They display tumor antigen-specific killing as well as antigen-independent killing. With tumor antigen-bearing target cells, the enhancement of killing ranged from 30-fold to 10,000 fold. Jurkat cells are the most sensitive target identified so far. They established a tumor model using Ras-transfected Jurkat cells (untransfected cells don't grow as tumor) in SCID mice. They injected 1 ml of cc49scFv-FasL culture medium (containing approximately 1 ug of scFv-FasL) every day for the first week and every other day thereafter, starting one day after tumor cell transfer IP. They eliminated tumor growth completely in 7 out of 8 mice. These mice lived longer than 3 months after transfer while control group that received culture medium all died at one month after transfer. Prolongation of lifespan from 12 days to 28 days was also observed with HeLa cells treated with ~5 ug of TAL6-scFv-FasL every other day after transfer, although the mice eventually succumbed to tumor cells.
They are testing the ability of transfected macrophages and/or dendritic cells that are themselves quite resistant to FasL as an in vivo factory to produce these fusion proteins. SCID mice transferred with these cells should produce scFv-FasL continuously to confer them resistance to transferred tumor cells or protective against tumor cell formation. This study was supported by a development grant from CCSG.
The other research program involves FasL and CD4+CD25+ T regulatory (Treg) cells. Their research in FasL has progressed to understanding the structure and function of FasL in terms of FasL expression control, trafficking, and cytotoxic potential.<