Requirement of inositol 1,4,5-trisphosphate receptors for tumor-mediated lymphocyte apoptosis.

Tumor cells strategically down-regulate Fas receptor expression to evade immune attack and up-regulate expression of Fas ligand to promote apoptosis of infiltrating T lymphocytes. Many pathways leading to apoptotic cell death require calcium release from inositol 1,4,5-trisphosphate receptors (IP3Rs). Here, we show that Fas-dependent killing of Jurkat T lymphoma cells by SW620 colon cancer cells requires calcium release from IP3R.