乳癌病人B7H4基因多型性之相關性研究

The study of the B7H4 polymorphisms in patients with breast cancer in Taiwan

楊和翰(Ho-Han Yang)

指導教授 ： 蔡麗玉

高雄醫學大學/健康科學院/醫學檢驗生物技術學研究所/碩士(2011年)

摘要

在台灣，乳癌為女性癌症發生率第一，死亡率第四，是國人女性健康的一大問題。免疫系統監控在防禦癌症上扮演重要的角色，個體在免疫系統監控下，會將腫瘤細胞辨識成一種危險性的干擾因子，可以將這些腫瘤細胞消滅以阻止腫瘤的生成。因此，當免疫系統監測能力失調時，可能會促使癌症的生成。文獻指出B7家族及其相對應的受體在抗原特異性的免疫反應調節中扮演重要的角色。B7H4為B7家族中新的分子，被發現與負向免疫調控反應有關。因此，本實驗將評估B7H4基因多型性 (Single nucleotide polymorphisms；SNP) 與罹患乳癌風險及乳癌臨床表徵之相關性。
本實驗分為兩個部分。第一部分實驗：收集283位乳癌病患及與其平均年齡相近且無乳癌家族史200位女性作為對照組。利用聚合酶鏈鎖反應與限制脢片段長度多型性，進行B7H4基因多型性之研究，利用卡方檢定評估B7H4基因多型性與罹患乳癌風險及乳癌臨床表徵之相關性。第二部分實驗：在283位乳癌病患之中275位乳癌病患腫瘤組織檢體，利用免疫組織化學染色法，觀察乳癌腫瘤組織中B7H4表現量，且利用卡方檢定評估其表現量與基因多型性及乳癌病患臨床表徵之相關性。
第一部分實驗結果發現：1. SNP- rs10801935具C基因型者 (A/C 及 C/C) 相較於具A /A基因型 (wild type) 者，罹患乳癌風險增加1.63倍 (OR = 1.63、P < 0.05) 2. 具GCG (rs10754339G、rs10801935C、rs3738414G) 單體型 (haplotype) 者，相較於AAG (wild type) 單體型者則罹患乳癌風險增高2倍 (OR = 2.00、P < 0.05)。3. 具SNP-rs10754339 G基因型與SNP-rs10801935 C基因型者相較於具SNP-rs10754339 A基因型與SNP-rs10801935 A基因型者 (wild type)，罹患乳癌風險增加1.67倍 (OR= 1.67、P < 0.05) 。第二部分實驗結果發現：B7H4基因多型性與乳癌組織腫瘤中B7H4表現量之間無相關性。但另一方面，乳癌腫瘤組織內B7H4表現量與病患臨床表徵：乳癌病患雌激素受體 (estrogen receptor；ER) 、黃體激素受體 (progesterone receptor；PR) 、病患癌化程度為負相關 (P < 0.05；P < 0.05；P < 0.05)。
綜合實驗結果，發現：B7H4基因變異可能與罹患乳癌風險有關，且ER及PR與乳癌腫瘤組織中B7H4表現量之間具有相關性，但其詳細機轉尚未明瞭。因此，本研究希冀藉由了解台灣婦女B7H4基因多型性及其表現量影響，未來可作為臨床上之乳癌預防及預後參考指標。

關鍵字

乳癌 ； 基因多型性

並列摘要

In Taiwan, breast cancer is one of the major health problems for women; the incidence of breast cancer ranks the first, and its mortality ranks the fourth in female cancer cases. Cancer cells in individuals under the supervision of the immune system can be found and eliminated in general. Upon the dysfunctional supervision of the immune system, the generation of cancer may be developed. Recent studies have showed that the B7 family and their receptors play an important role in antigen-specific regulation of immune responses. B7H4, a molecule of the new B7 family, was found to be related to the negative regulation of immune responses. Therefore, the aim of this study is to investigate whether B7H4 polymorphisms are associated with the expression of B7H4 in breast cancer tissues, which lead to influence the immune surveillance that increases the risk of breast cancer. In addition, the association between B7H4 polymorphisms and clinical pathological features is also analyzed.
There were two experimental stages in this study. Firstly, we collected 283 patients with breast cancer from Kaohsiung Medical University Hospital and a control group consisting of 200 cases with matched sex and age in the study. The B7H4 polymorphisms; namely, the rs10754339 (G > A), the rs10801935(C > A), and the rs3738414 (A > G) were analyzed by the PCR-RFLP technique. The association between the B7H4 polymorphisms and the risk of breast cancer were evaluated by the chi-square test. Subsequently, we analyzed the expression of B7H4 by Immunohistochemical staining, and correlated the results with the B7H4 polymorphisms and the relationships of clinical parameters by chi-square test. In the first stage, the results showed that: 1. The rs10801935 C carriers were associated with a significantly increased risk of breast cancer compared with the A carriers (OR=1.63、P < 0.05). 2. We found that the GCG haplotype (rs10754339G, rs10801935C, and rs3738414G) was associated with a significantly increased risk of breast cancer compared with the AAG haplotype (OR= 2.00、P < 0.05). 3. The genotype with the combination of rs10754339 G and rs10801935 C was associated with a significantly increased risk of breast cancer compared with that with the combination of rs10754339 A and rs10801935 A (OR= 1.67、P < 0.05). In the second stage, the results showed that the B7H4 polymorphisms were not associated with the expression of B7H4 in breast cancer tissues. It might be due to the fact that the expression of B7H4 had been regulated at the transcription stage. However, we found that there was lower expression of B7H4 in terms of the correlation among breast cancer tissues and the clinicopathologic features, including estrogen receptor-positive (ER+), progesterone receptor- positive (PR+). In addition, we found that the expression of B7H4 was lower in breast cancer patients with a higher proportion of tumor tissues.
Taken together, we have found that the B7H4 polymorphisms are associated with the risk of breast cancer. Moreover, our findings indicate that ER and PR may play important roles in regulating the expression of B7H4 in breast cancer tissues, but the mechanism is still unclear. This study may provide clinical applications of the B7H4 polymorphisms and expressions in breast cancer prevention and serve as prognostic biomarkers among Taiwanese women.

並列關鍵字

breast cancer ； B7H4 ； polymorphisms

參考文獻

American cancer society.

(2005). "breast cancer treatment guidelines for patients." american cancer society.

AJCC (2004). "American Joint Committee on Cancer ".

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