Background: Tumor necrosis factors (TNFs) and heat shock protein 70 (hsp70) are determining factors in immunologic mechanisms to tumor cells. The authors designed a case-controlled study to investigate the potential association of the polymorphisms of TNF-alpha and of hsp70-2 and hsp70-hom genes with malignant tumors.
Methods: The authors used an allele specific polymerase chain reaction to characterize the variation of the TNF-alpha promotor region in 124 unrelated Tunisian patients with malignant tumors (non-Hodgkin's lymphoma, breast carcinoma, and other tumors) and 106 healthy control subjects. Using polymerase chain reaction and restriction enzyme digestion, polymorphic analysis of hsp70-2 and hsp70-hom genes was performed in patients with non-Hodgkin's lymphoma, in those with breast carcinoma, and in control subjects.
Results: Analysis of TNF-alpha polymorphism in patients with malignant tumors and in control subjects demonstrated a high relative frequency of the TNF2 allele in the cancer patients. The relative risk (RR) of lymphoma was especially high in association with TNF1/TNF2 heterozygotes (RR = 6.7; P < or = 0.0001). Polymorphism analysis of the hsp70-2 and hsp70-hom genes in patients with lymphoma and in those with breast carcinoma revealed that these patients had highly significant differences in the genotypic distribution of these biallelic loci compared with the control subjects. Homozygosity for one hsp70-2 allele was significantly associated with lymphoma (RR = 18.2; P < or = 0.0001) and with breast carcinoma (RR = 16.3; P < or = 0.001).
Conclusions: Tunisian persons carrying the TNF2 allele may have an increased risk of cancer. In this study, non-Hodgkin's lymphoma and breast carcinoma were significantly associated with polymorphism in hsp70 genes.