Inhibition of PRAME expression causes cell cycle arrest and apoptosis in leukemic cells.

The preferentially expressed antigen of melanoma (PRAME) is known as a tumor-associated antigen, but its function in leukemia remains unclear. We investigated the function with small interfering RNA (siRNA)-induced knockdown of PRAME in a K562 cell line. After PRAME siRNA transfection, proliferation was suppressed and cell cycle analysis showed G(0)/G(1) arrest, followed by apoptosis. PRAME siRNA-treated cells also showed changes in the genes affecting erythroid differentiation. We examined the PRAME expression levels and the S phase population of 32 acute leukemia patients at the time of diagnosis and relapse. An increase of the S phase population was accompanied by an increase of PRAME expression at relapse. Our results suggest that PRAME plays an important role in disease progression in acute leukemia.