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Tumor necrosis factor receptor superfamily member 10 (TNFRSF10), includes TNFRSF10A (DR4), TNFRSF10B (DR5), TNFRSF10C (DcR1) and TNFRSF10D (DcR2) TNFRSF10 family contains TNFRSF10A (also known as DR4, Apo2, TRAIL-R1, CD261), TNFRSF10B (also known as DR5, KILLER, TRICK2A, TRAIL-R2, TRICKB, CD262), TNFRSF10C (also known as DcR1, TRAIL-R3, LIT, TRID, CD263), and TNFRSF10D (also known as DcR2, TRUNDD, TRAIL-R4, CD264). Tumor necrosis factor-related apoptosis inducing ligand (TNFSF10/TRAIL) binds to all 4 receptors. DR4 (TRAIL-R1) and DR5 (TRAIL-R2) are membrane-bound and contain a death domain in their intracellular portion, which is able to transmit an apoptotic signal, thus often called death receptors. In contrast, DcR1 (TRAIL-R3), which lacks the complete intracellular portion and DcR2 (TRAIL-R4), which has a truncated cytoplasmic death domain, do not transmit an apoptotic signal, thus known as decoy receptors. Apoptosis mediated by DR4 and DR5 requires Fas (TNFRSF6)-associated via death domain (FADD), a death domain containing adaptor protein. Two transcript variants encoding different isoforms and one non-coding transcript have been found for TNFRSF10B/DR5. DcR1 appears to function as an antagonistic receptor that protects cells from TRAIL-induced apoptosis; it has been found to be a p53-regulated DNA damage-inducible gene. The expression of this gene is detected in many normal tissues but not in most cancer cell lines, which may explain the specific sensitivity of cancer cells to the apoptosis-inducing activity of TRAIL. DcR2 has been shown to play an inhibitory role in TRAIL-induced cell apoptosis. The membrane expression of all of these receptors (DR4, DR5, DcR1, and DcR2) is greater in normal endometrium (NE) than in endometrioid adenocarcinoma (EAC). In EAC patients, membrane expression of these receptors are not independent predictors of survival. DcR1 and DcR2 expression is critical in cell growth and apoptosis in cutaneous or uveal melanoma; DcR1 and DcR2 are frequently methylated in both, leading to loss of gene expression and melanomagenesis. On the other hand, DR4 and DR5 methylation is rare in cutaneous melanoma and frequent in uveal melanoma; their expression is wholly independent of the promoter methylation status. DcR1 and DcR2 genes are also reported to be hyper-methylated in prostate cancer. The TRAIL ligand, a potent and specific inducer of apoptosis in cancer cells, has been explored as a therapeutic drug; experimental data has shown that DR4 specific TRAIL variants are more efficacious than wild-type TRAIL in pancreatic cancer.
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