Nucleotide substitution in the ectodomain of TRAIL receptor DR4 is associated with lung cancer and head and neck cancer

Allelic loss of chromosome 8p21-22 occurs frequently in cancer, including l ung and head and neck squamous cell cancer. The tumor necrosis factor-relat ed apoptosis-inducing ligand (TRAIL) receptors, including proapoptotic DR4 and KILLER/DR5, are located on 8p21-22, TRAIL, receptors are candidate tumo r suppressor genes, because their inactivation would be expected to result in deficient apoptotic signaling. To investigate the involvement of DR4 in human cancer, we have determined the genomic structure of DR4 and screened 31 lung cancer cell lines [14 small cell lung cancer and 17 non-small cell lung cancer (NSCLC)], many with deletions at 8p21-22, and 21 primary NSCLC samples for mutations in DR4. We found two missense alterations in the ecto domain of DR4, One, at nucleotide 626, changes a cytosine to a guanine (C62 6G) and results in a substitution of an arginine for threonine, The other, at nucleotide 422, changes a guanine to adenine (G422A) and results in a su bstitution of a histidine for arginine. Using genomic DNA sequencing and RF LP analysis, we show that these two alterations cosegregated in 96% of all of the samples (n = 243) evaluated (tumor and normal), The frequency of bei ng homozygous for both altered alleles was 35% in the lung cancer cell line s but only 13% in age- and race-matched controls, which was a significant i ncrease (chi (2) = 5.2, P = 0.023). The frequency of homozygosity for both alleles was also significantly increased in the primary NSCLC samples (chi (2) = 9.2, P = 0.002) as compared with the age- and race-matched controls, To determine whether the altered alleles are specific for lung cancer, we e valuated 19 head and neck squamous cell cancer and 25 gastric adenocarcinom a samples. Forty-seven % of the former and 44% of the latter were homozygou s for both the C626G and G422A alterations, and this was significantly elev ated relative to age- and race-matched controls (chi (2) = 8.6, P = 0.003 a nd chi (2) = 8.2, P = 0.004). These alterations result in amino acid change s in or near the ligand-binding domain of DR4 and, based on the crystal str ucture of DR5 and its homology with DR4, have the potential to affect TRAIL binding to DR4, Our results suggest that the altered DR4 alleles may be as sociated with, and should be investigated additionally as potential markers for, predisposition to common malignancies.