細胞激素基因多形性與B型肝炎相關之肝細胞癌的研究

The association of cytokine genetic polymorphisms and hepatitis B-related hepatocellular carcinoma

陳俊傑(Chun-Chieh Chen)

指導教授 ： 李孟智

中山醫學大學/醫學院/醫學研究所/博士(2007年)

摘要

研究背景與目的：肝細胞癌是全世界重要的癌症之一，在台灣，肝細胞癌的形成主要與B型肝炎病毒經由慢形肝炎的過程有關，因此，B型肝炎帶原與慢性發炎反應相關之細胞激素，可能在肝細胞癌形成過程中扮演重要地位，同時，慢性發炎與細胞激素誘發之氧化壓力，可能會造成DNA缺損，因此DNA修補基因，也可能在肝細胞癌形成過程中扮演重要地位。本研究探討細胞激素基因多形性與肝細胞癌之相關性，也探討肝細胞癌形成過程，細胞激素、DNA修補和代謝基因多形性，以及基因與基因間之交互作用與修飾作用，同時進一步探討抽菸與這些基因多形性間的交互作用。

研究方法：本病例對照研究，包括577位B型肝炎相關肝細胞癌個案，以及389位未發生肝細胞癌之B型肝炎帶原者，分析細胞激素基因(IL-1RN、IL-1B-31、IL-1B-511、IL-1B+3954、TNF-α-308)、DNA修補基因(XRCC1-Arg399Gln、hMLH1-93和XPD-Lys751Gln)與代謝基因(GSTTI、GSTM1)等基因多形性，以邏輯式多變項回歸分析，探討細胞激素、DNA修補和代謝基因多形性與肝細胞癌的相關性，也探討基因與基因之交互作用與修飾作用，以及抽菸與這些基因多形性間的交互作用。

研究結果：本研究發現在所有基因多形性中，包括IL-1RN、IL-1B-31、IL-1B-511、 IL-1B+3954、TNF-α-308、XRCC1-Arg399Gln、XPD-Lys751Gln、GSTT1和GSTM1，僅hMLH1-93的A/A基因會明顯增加肝細胞癌的機會(P = 0.011, 調整後勝算比為1.93，95%信賴區間為1.29至2.87)。進一步分析發現，在有IL-1RN*2基因時，hMLH1的A基因、IL-1B-31的T基因和IL-1B-511的C基因會明顯增加肝細胞癌的機會，但沒有IL-1RN*2基因，不會增加肝細胞癌的機會。在IL-1RN*2基因的修飾作用下，IL-1B-31會增加肝細胞癌的機會(調整後交互作用之P值為0.0045)，同時IL-1B-31攜帶T基因數目與罹患肝細胞癌之間，存在劑量關係(調整後P值為0.0030)。本研究發現在有IL-1RN*2基因時，IL-1B、TNF-α、hMLH1和XRCC1高危險基因的數目，與罹患肝細胞癌之間存在著劑量關係。與沒有或僅攜帶一個高危險基因相比，B型肝炎帶原者攜帶二個高危險基因，會有中度增加罹患肝細胞癌的機會(調整後勝算比為3.19，95%信賴區間1.11至9.21)，B型肝炎帶原者攜帶三個或三個以上高危險基因，會有達9.7倍的機會罹患肝細胞癌(95%信賴區間2.90至32.13)，而且在未攜帶IL-1RN*2基因的B型肝炎帶原者，並未發現此現象。本研究也發現抽菸會修飾IL-1B、TNF-α、hMLH1、XRCC和IL-1RN等多重基因的影響，此現象也僅見於抽菸者會增加肝細胞癌的機會(調整後勝算比為4.86，95%信賴區間1.70至13.94)。與非吸菸者相比，抽菸者攜帶IL-1B、TNF-α、hMLH1、XRCC和IL-1RN等高危險基因，會增加11倍罹患肝細胞癌的機會(調整後勝算比為11.54，95%信賴區間4.09至32.39)。

研究結論：本研究發現細胞激素基因多形性，會增加B型肝炎罹患肝細胞癌的易感受性，同時，也發現在肝細胞癌形成過程，細胞激素與DNA修補基因多形性，存在修飾作用與基因基因之交互作用。抽菸也可能因為細胞激素與氧化壓力，增加B型肝炎罹患肝細胞癌的易感受性。

關鍵字

細胞激素基因多形性 ； B型肝炎 ； 肝細胞癌

並列摘要

Background and Objectives: Hepatocellular carcinoma (HCC) is one of an important cancer in the world. In Taiwan, hepatitis B virus (HBV) induced HCC mainly by chronic necroinflammatory hepatic disease. Hepatitis B surface antigen (HBsAg) carriers and chronic inflammation associated with cytokines may play an important role in the process of developing HCC. We hypothesize and investigate that genetic polymorphisms of cytokines are associated with cancer risk of HCC and further investigate the synergic interaction and combined effects of genetic polymorphisms of cytokine, DNA repair and metabolism. Further, we investigated whether the smoking might be interactions between these genetic polymorphisms in HCC risk.

Methods: Our case-control study included 573 case subjects of HBsAg carriers diagnosed with HCC and 388 controls of HBsAg carriers without HCC. We analyzed genetic polymorphisms of interleukin-1B (IL-1B-511, +3954), interleukin-1 receptor antagonist (IL-1RN), XRCC1-Arg399Gln and hMLH1-93 by PCR-based restriction fragment length polymorphism and genetic polymorphisms of IL-1B-31, TNF-α-308, and XPD-Lys751Gln by real time PCR. Multivariate logistic regression was estimated between genetic polymorphisms and HCC by using SPSS software.

Results: Only genotype A/A of the hMLH1-93 polymorphism was associated with increased risk for HCC (P = 0.011, adjusted OR = 1.93, 95% CI = 1.29-2.87), but there were no statistically significant differences in the distributions of genotype of IL-1RN, IL-1B-31, IL-1B-511, IL-1B+3954, TNF-α-308, XRCC1-Arg399Gln, XPD-Lys751Gln, GSTT1 and GSTM1 polymorphisms between HCC and controls. In the presence of IL-1RN*2, A allele of hMLH1, T allele of IL1B-31 and C allele of IL1B-511 were associated with increasing risk of HCC, but no such association in the absence of IL-1RN*2. The association between IL-1B-31 and HCC was modified by the IL-1RN genotype (adjusted P-value for interaction = 0.0045) and a dose-dependent association was observed with increasing number of T allele of IL-1B-31 and HCC in the presence of IL-1RN*2 (adjusted P-value for linear trend = 0.0030). Compared with none or 1 putative high-risk genotype, a moderately increased risk of HCC was observed among those with 2 high-risk genotypes of IL-1B, TNF-α, hMLH1 and XRCC1 gene in the presence of IL-1RN*2 (adjusted OR = 3.19, 95% CI = 1.11-9.21). Further, a 9.7-fold increased risk of HCC was observed among those with more than 3 putative high-risk genotypes (adjusted OR = 9.66, 95% CI = 2.90-32.13). When considering high-risk genotype of IL-1B, TNF-α, hMLH1, XRCC1 and IL-1RN together, an increased risk of HCC associated with high-risk multilocus genotype was higher for smokers (adjusted OR = 4.86, 95% CI = 1.70-13.94) than non-smokers (adjusted OR = 1.23, 95% CI = 0.67-2.26). Compared with non-smokers, an 11-fold increased risk for developing HCC was observed for the smokers with all high-risk genotype of IL-1B, TNF-α, hMLH1, XRCC1 and IL-1RN (adjusted OR = 11.54, 95% CI = 4.09-32.39).

Conclusions: Our results imply that the association of genetic polymorphisms of inflammatory cytokines in the formation of hepatocarcinogenesis. We also demonstrated that modification effect and complex gene-gene interaction of cytokine genes and DNA repair genes in development of HCC. Smoke, an environmental and external source of oxidative DNA damage, may induce inflammatory cytokines and oxidative stress that can increase the susceptibility to HBV-related HCC.

並列關鍵字

cytokine genetic polymorphisms ； hepatitis B ； hepatocellular carcinoma

參考文獻

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