Characteristics of Purinergic Receptor Expressed in Human Retinoblastoma Cells

Abstract

Recently, much attention has been paid to human retinoblastoma since it provide a good model system for studying mechanisms underlying cell growth, differentiation, proliferation, and apoptosis, and for developing cancer therapy. However, until now it is unclear whether purinergic receptors are involved in the calcium mobilization in the retinoblastoma cells. In this regard, we measured possible purinergic signaling in WERI-Rb-1 cells using Ca2+ imaging technique and RT-PCR method. ATP-induced [Ca2+]i transients was maintained to about 90.7±1.0% of the control (n=48) even in the absence of extracellular calcium. The ATP-induced intracellular calcium response was only attained to 10.4±1.8% (n=55) of peak amplitude of the control after preincubation of 1 μM U-73122, a PLC inhibitor, but it was not affected by 1 μM U-73343, a inactive form of U-73122. And also ATP-induced [Ca2+]i rise was almost attenuated by 20 μM 2-APB, a putative IP3 receptor inhibitor. Two subtypes of IP3 receptor (IP3-1R, IP3-2R) were identified by a RT-PCR method. These findings suggest that purinergic stimuli can cause calcium mobilization via PLC-IP3 pathway after the activation of P2Y receptors in the retinoblastoma cells, which may play important roles in cell proliferation, differentiation, growth, and cell death.