Expression of TRAIL (TNF-related apoptosis-inducing ligand) receptors in cervical cancer

Apoptosis is an intrinsic and fundamental biologic process that plays a critical role in the normal development of multicellular organisms and in the maintainance of tissue homeostasis. Some of the well known regulators of apoptosis are cytokines of the tumor necrosis factor (TNF) ligand family, such as Fas ligand (Fas L) and TNF, which induce apoptosis by activation of their corresponding receptors, Fas and TNFR-1. Recently, a new member of the TNF family known as TRAIL (TNF-related apoptosis-inducing ligand) was identified and shown to induce p53-independent apoptosis in a variety of tumor cell lines but not in normal cells. Four human receptors for TRAIL were also recently identified and designated TRAIL-R1, -R2, -R3, and -R4. The aim of this study is to examine whether TRAIL and TRAIL receptors (-R1, -R2, -R3) are expressed in uterine cervical cancer and whether it is correlated with apoptosis, TRAIL, and TRAIL receptors. The subjects were 20 patients who were diagnosed with cervical cancer. Western blotting was performed in nine cases and immunohistochemical staining for TRAIL and TRAIL receptors (-R1, -R2, -R3) and TUNEL method for detection of apoptosis was performed in 11 cases. There were proteins for TRAIL, TRAIL-R1, -R2, and -R3 in tissues from cervical cancer. All TRAIL receptors were expressed in both normal cervical epithelium and tumor cells, and TRAIL-R1 and -R2 were more strongly expressed in tumor cells than normal epithelium (P < 0.05). Apoptosis correlated with expression of TRAIL-R1 and -R2 (P < 0.05). This study suggests that TRAIL induces apoptosis in cervical cancer through its receptors.