[CANCER RESEARCH 64, 2918 –2922, April 15, 2004] Sequence Variants of Toll-Like Receptor 4 Are Associated with Prostate Cancer Risk: Results from the CAncer Prostate in Sweden Study S. Lilly Zheng, 1 Katarina Augustsson-Ba ¨lter, 2 Baoli Chang, 1 Maria Hedelin, 2 Liwu Li, 1 Hans-Olov Adami, 2 Jeanette Bensen, 1 Ge Li, 1 Jan-Erik Johnasson, 4 Aubrey R. Turner, 1 Tamara S. Adams, 1 Deborah A. Meyers, 1 William B. Isaacs, 5 Jianfeng Xu, 1 and Henrik Gro ¨nberg 3 1 Center for Human Genomics, Wake Forest University School of Medicine, Winston-Salem, North Carolina; 2 Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; 3 Department of Radiation Sciences, Oncology, University of Umeå, Umeå, Sweden; 4 Department of Urology and Clinical Medicine, O ¨ rebro University Hospital, Sweden, and Regional Oncological Center, University Hospital, Uppsala, Sweden; and 5 Department of Urology, Johns Hopkins Medical Institutions, Baltimore, Maryland ABSTRACT Inflammation has been implicated as an etiological factor in several human cancers. Growing evidence suggests that chronic inflammation may also play a role in the etiology of prostate cancer. Considering that genetic susceptibility is a major risk factor for this disease, we hypothesize that sequence variants in genes that regulate inflammation may modify individual susceptibility to prostate cancer. The lipopolysaccharide recep- tor Toll-like receptor 4 (TLR4) is a central player in the signaling path- ways of the innate immune response to infection by Gram-negative bac- teria and is an important candidate inflammatory gene. We performed a systematic genetic analysis of TLR4 sequence variants by evaluating eight single-nucleotide polymorphisms that span the entire gene among 1383 newly diagnosed prostate cancer patients and 780 age- and residence- matched controls in Sweden. We found an association between a sequence variant (11381G/C) in the 3-untranslated region of the TLR4 gene and prostate cancer risk. The frequency of the variant genotypes (CG or CC) was significantly higher in the patients (24.1%) than in the controls (19.7%; P  0.02). The frequency of risk genotypes among patients diagnosed before the age of 65 years was even higher (26.3%). Compared with men who had the wild-type genotype of this single-nucleotide poly- morphism (GG), those with GC or CC genotypes had a 26% increased risk for prostate cancer (odds ratio, 1.26; 95% confidence interval, 1.01– 1.57) and 39% increased risk increased risk for early onset prostate cancer (before age 65 years; odds ratio, 1.39; 95% confidence interval, 1.02–1.91). The risk attributable to this variant for prostate cancer in Sweden was estimated to be 4.9%. Although the biological mechanism of the observed association remains to be elucidated, our finding supports a role for a bacteria-associated response pathway, possibly acting via in- flammation, in the development of prostate cancer. INTRODUCTION Chronic or recurrent inflammation is known to play a causative role in the development of many human cancers, including cancers of the liver, esophagus, stomach, large intestine, and urinary bladder (1). Inflammatory changes have long been recognized in prostate tissues, leading to speculation that chronic inflammation might contribute to prostate cancer development (2). The role of prostate inflammation in prostate cancer was strongly implicated in the recently proposed theory that proliferative inflammatory atrophy serves as a precursor to prostatic intraepithelial neoplasia and to prostate cancer (3, 4). The identification of two candidate prostate cancer susceptibility genes (RNASEL and MSR1) that encode proteins with critical functions in host responses to infections provides additional support for a role of inflammation in prostate cancer development (5, 6). Chronic infection and inflammatory processes that may lead to tumorigenesis are mediated in part through recognition of various stimuli by Toll-like receptors (TLRs; Ref. 7). Among these TLRs, TLR4 recognizes Gram-negative bacterial products, including lipopo- lysaccharide (8), the antitumor compound taxol in the mouse but not in humans (9), and human heat shock protein 60 (10). Differential activation of TLR4 by this array of naturally occurring or synthetic ligands subsequently induces distinct downstream processes, includ- ing the expression of inflammatory genes as well as regulation of cell growth/apoptosis. Conceivably, improper regulation or compromised function of TLR4 may contribute to various inflammatory diseases, including cancer. On the basis of the potential importance of inflammation and inflammatory genes in prostate cancer development, we hypothesized that sequence variants of TLR4 are associated with prostate cancer susceptibility. To test this hypothesis, we performed a systematic genetic analysis in a large population-based prostate cancer case– control study in Sweden. MATERIALS AND METHODS Study Population. The cases studied came from the large-scale, popula- tion-based case– control study CAncer Prostate in Sweden (CAPS). The case participants were recruited from four of the six regional cancer registries that cover the entire population of Sweden. Each of these four registries serves one health care region (Northern, Central, Stockholm, and South Eastern); the four registries altogether encompass 6 millions inhabitants (67% of Sweden’s population). Reporting of newly diagnosed cancer cases to the registries is required by law for both the attending physician and pathologist; therefore, the registries include almost 100% of all cancers diagnosed in Sweden. In the CAPS study, the source-person-time comprises men living in the area of O ¨ rebro and the northern part of Sweden (Va ¨sternorrland, Ja ¨mtland, Va ¨ster- botten, and Norrbotten) from January 1, 2001, as well as men living in the areas of Va ¨stmanland, So ¨dermanland, Ga ¨vleborg, Dalarna, Va ¨rmland, and Uppland from July 1, 2001, until September 2002 (except for Ja ¨mtland and the county of Lycksele in Va ¨sterbotten, where the source-person-time ended March 1, 2002). The source-person-time was divided into two age-specific study bases. The first study base included men age 35– 65 years of age living in all of the regions mentioned above. The second study base included men 66 –79 years of age living only in the areas of O ¨ rebro, Va ¨stmanland, So ¨der- manland, and the northern part of Sweden. The inclusion criterion for cases in CAPS was pathologically or cytologi- cally verified adenocarcinoma of the prostate (International Classification of Disease for Oncology = C61). After receiving notification of a new case, the administrator at the regional cancer registry mailed a letter to the treating physician informing him or her about the study. The physician was asked to indicate whether the patient was able to participate in the study. If so, the physician mailed a letter to the patient to introduce the study and asked him to send a reply letter to the administrator at the cancer registry. After approval from both the physician and the patient, the study secretaries sent a question- naire and a kit with tubes for blood sampling to the eligible case. The self-administered questionnaire included questions concerning such items as Received 10/18/03; revised 2/6/04; accepted 2/9/04. Grant support: Grants from the Swedish Cancer Foundation and Spear Grant from the Umeå University Hospital (Umeå, Sweden). Also partially funded by the Center for Human Genomics at Wake Forest University School of Medicine. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Requests for reprints: Jianfeng Xu, Wake Forest University School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157. Phone: (336) 713-7500; Fax: (336) 713-7566; E-mail: jxu@wfubmc.edu. 2918 Downloaded from http://aacrjournals.org/cancerres/article-pdf/64/8/2918/2528992/zch00804002918.pdf by guest on 24 June 2022