PROSTATIC ACID PHOSPHATASE IS A NON-SELECTIVE ECTONUCLEOTIDASE IN RIP 1 DEFICIENT HUMAN JURKAT T CELL LEUKEMIA AND EG7 MURNINE THYMOMA TUMOR CELLS

Chemotherapies are used to induce apoptosis on a select number of tumor cells and initiate an anti-tumor immune response. Signaling for this response is characterized by pannexin 1 mediated release of apoptotic adenosine triphosphate (ATP). ATP acts as a "find me" signal for macrophages. Macrophages then phagocytize the dying tumor cell and present tumor antigen to cytotoxic T-cells. In RIP1 "/- Jurkat Human T-cell leukemia and EG7 murine thymoma cells, apoptotic extracellular ATP accumulation is degraded by plasma membrane ectonucleotidases. Prostatic acid phosphatase (PAP) is a known plasma membrane protein in prostate cancer. I hypothesized that PAP is a non-selective ectonucleotidase in Jurkat RIP1 7- and EG7 cells because PAP was recently shown to be a nonselective phosphatase and to hydrolyze the nucleotide thymine monophospate (TMP) into thymine. Through etheno adenosine monophosphate (e-AMP) and etheno adenosine triphosphate (e-ATP) hydrolysis assays, AMPase and ATPase activity of PAP in Jurkat control, Jurkat RIP1 -/- and EG7 cells was measured with and without the presence of the selective PAP inhibitor, l-tartrate. 2x106 cells/mL were re-suspended in basal salt solution (BSS) media + 10mM glucose + .1%BSA. 10mM l-tartrate was added to certain wells, followed by 10pM e-AMP and 10pM e-ATP. Cells were incubated for one hour and supernatants were collected and evaluated using ion exchange high performance liquid chromatography. The presence of l-tartrate inhibited e-AMP hydrolysis and partially inhibited e-ATP hydrolysis in Jurkat RIP1 7- and EG7 cells. PAP was also identified through western blot analysis. These results suggest that PAP is a non-selective ectonucleotidase present in not only prostate cancer, but also certain strands of leukemia and lymphoma.