Key words: HLA; ␤2m; antigen processing machinery; bladder carcinoma; tumor escape Downregulation of HLA class I molecules is a frequent event observed in human tumors, and it is believed to be related with tumor immune escape. Several types of HLA class I downregulation have been described including total, locus, allele and haplotype loss. 1 Total HLA class I loss is a relatively frequent phenotype (9 -52%) detected in tumors derived from different tissues such as melanoma, head-neck, colorectal, prostate and breast cancer. 2 Molecular mechanisms that have been shown to be responsible for this phenotype include the following. 1) ␤2-microglobulin (␤2-m) gene mutations, which play an important role in assembly of the HLA complex (HLA heavy chain, ␤2-m and peptide). ␤2-microglobulin gene mutations result in failure to assemble the class I molecules for cell surface expression and are therefore responsible for total HLA class I loss. Frequent ␤2-m mutations have been described in colorectal and gastric cancers of the microsatellite mutator phenotype (MMP), 3,4 which exhibit a type of genetic instability characterized by the accumulation of somatic mutations in repeated sequences. 5 The ␤2-m gene contains several repeat sequences and so is a mutational target for mismatch repair deficiency. The frequency of ␤2-m mutations in other tumor types that infrequently display MMP (breast cancer and melanoma) is lower than in colorectal carcinomas. 3 2) Downregulation of proteins involved in the antigen processing pathway is responsible for total HLA class I loss due to a deficiency in peptide formation, loading of MHC molecules and transport. MHC class I presentation of peptides is a multistep process involving several molecules: catalytic ␤ subunits of the proteasome (LMP2, LMP7 and LMP10), transporter associated with antigen processing (TAP-1 and TAP-2) and various endoplasmic reticulum chaperones. Numerous studies have demonstrated deficiencies in the expression of antigen-processing genes in tumor cell lines. 6 -10 Most of the deficits described are combined deficiencies comprising multiple components, 6,9,10 though selective deficiencies have also been described. 7,10 Most of these alterations are corrected by cytokine treatment, particularly by IFNgamma. In contrast, structural defects in antigen-processing genes are very uncommon and only 2 point mutations in TAP-1 gene have been described. 11,12 3) Finally, hypermethylation of HLA class I promotor genes can also repress HLA class I expression, as has been demonstrated in melanoma cell lines. 13 Although HLA class I total loss can be found in histologically different tumor types, carcinogenesis in each tissue present particular characteristics. In despite of the great advances in our knowledge of molecular lesions that produce HLA class I total loss in tumor cell lines, in some particular human tumor tissues the underlying mechanisms remain to be established.Bladder cancer is one of the most common malignancies worldwide, with transitional cell carcinoma (TCC) being ...

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BackgroundInflammation has been implicated as an etiological factor in several human cancers, including prostate cancer. Allelic variants of the genes involved in inflammatory pathways are logical candidates as genetic determinants of prostate cancer risk. The purpose of this study was to investigate whether single nucleotide polymorphisms of genes that lead to increased levels of pro-inflammatory cytokines and chemokines are associated with an increased prostate cancer risk.MethodsA case-control study design was used to test the association between prostate cancer risk and the polymorphisms TNF-A-308 A/G (rs 1800629), RANTES-403 G/A (rs 2107538), IL1-A-889 C/T (rs 1800587) and MCP-1 2518 G/A (rs 1024611) in 296 patients diagnosed with prostate cancer and in 311 healthy controls from the same area.ResultsDiagnosis of prostate cancer was significantly associated with TNF-A GA + AA genotype (OR, 1.61; 95% CI, 1.09–2.64) and RANTES GA + AA genotype (OR, 1.44; 95% CI, 1.09–2.38). A alleles in TNF-A and RANTES influenced prostate cancer susceptibility and acted independently of each other in these subjects. No epistatic effect was found for the combination of different polymorphisms studied. Finally, no overall association was found between prostate cancer risk and IL1-A or MCP-1 polymorphisms.ConclusionOur results and previously published findings on genes associated with innate immunity support the hypothesis that polymorphisms in proinflammatory genes may be important in prostate cancer development.