前列腺癌与雄激素受体基因(CAG)n重复多态性的关系

目的　探讨前列腺癌 (PC)与雄激素受体 (AR)基因 (CAG)n重复多态性的关系。　方法　应用DNA双链循环测序方法对 34例PC组织与癌旁正常组织、2例PC患者外周血白细胞内的AR基因 (CAG)n重复数进行测定。　结果　同一PC患者的癌组织与癌旁正常组织 (CAG)n重复数相同 ;36例患者癌组织AR基因 (CAG)n呈重复多态性 ,平均 2 0 .0 6 ,显著低于正常组织 ,差别有显著性意义 (P <0 .0 5 ) ;不同分化程度的癌组织 (CAG)n重复数差别无显著性意义 (P >0 .0 5 )。　结论　AR基因 (CAG)n重复数改变的体细胞突变在PC癌细胞中罕见 ,该重复数的减少可能与PC发病相关     

雄激素受体基因CAG多态性与迟发性性腺功能减退症的相关性研究

目的:研究雄激素受体基因(AR)重复序列(CAG)n多态性与迟发性性腺功能减退症(LOH)的关系,探讨LOH的发病机制。方法:共调查1 000例40～70岁中老年男性,其中19例迟发性性腺功能减退症患者,随机抽取127例正常健康中老年男性,测定甘油三酯(TG)、空腹血糖(FBG)、血清总睾酮(TT)、游离睾酮(fT),测量身高、体重、腰围(WC)、血压,并采用DNA测序方法进行AR基因外显子1氨基端转录调节区(CAG)n重复序列长度测定,比较两组各指标之间的差异。结果:(CAG)n重复次数为15～32(23.05±2.95)。正常健康中老年男性的体重指数(BMI)、FBG较LOH患者显著下降(P<0.01),而TG、TT及fT较LOH患者显著升高(P<0.01)。正常健康中老年男性AR基因(CAG)n重复数为22.54±3.06;LOH患者AR基因(CAG)n重复数为23.23±2.24;LOH患者(CAG)n重复数略高于正常健康人群,但两者比较无统计学意义(P=0.946)。(CAG)n重复长度显示:长组(n≥22)AR基因(CAG)n在LOH组和正常健康中老年男性组的频率分别为73.68%和48.82%(P<0.05)。相关分析显示:TT、fT与(CAG)n重复序列无明显相关性(r=0.04和r=0.025,P>0.05)。结论:LOH男性AR基因(CAG)n重复序列呈现多态性,长(CAG)n重复多态可能是LOH发病的遗传因素,但仍需进一步扩大样本量证实。     

雄激素不敏感症疑似病例AR基因全长测序位点突变筛查与结果分析

目的对临床疑似雄激素不敏症患者进行AR基因全长测序连锁分析位点突变。方法提取雄激素不敏感(AIS)疑似患者外周血DNA,做染色体核型分析,了解AR基因各外显子缺失或重复突变情况,进行基因全长测序连锁分析位点突变。A组外生殖器异常表型,表现为尿道下裂并阴茎体发育不良,B组无尿道下裂但为小阴茎。结果 A组12例患者中发现3例AR基因突变。第1例发生新的c.D841 CGTAGT(精氨酸丝氨酸)突变,第2例发生c.D172和c.D173插入了TGC三个碱基。第3例存在c.D946 TC,c.D 316络氨酸组氨酸突变。3例均确诊为雄激素不敏感,2例为完全型,1例部分型。B组未发现AR基因突变。结论 AR基因全长测序可从分子水平初步阐明雄激素不敏感症的病因,指导临床诊治。     

前列腺癌组织雄激素受体基因突变的检测

目的：探讨雄激素受体（AR）基因突变与前列腺癌（PCa)发生发展的关系。方法：采用聚合酶链式反应－单链构象多态性分析（PCR－SSCP）和异常片段的双链DNA直接测序,对27例PCa患者石蜡切片组织AR基因的8个外显子（多态性片段除外）进行检测。结果：27例中3例在A、D、G外显子分别显示SSCP异常,测序证实1例A外显子存在一错义突变（C^966→A,Ser296Arg)。结论：突变位于转录激活区,推测可改变AR的转录活性,与PCa的发展有关。     

雄激素受体基因CAG多态性对男性激素避孕有效性影响的研究

目的:分析应用肌注十一酸睾酮酯(TU)进行激素避孕的男性志愿者中起反应者与不起反应者雄激素受体(AR)基因(CAG)n微卫星多态性,并探讨该多态性对激素避孕效果的影响。方法:29例TU不起反应者和34例起反应者分别作为试验组和对照组,应用PCR和DNA测序技术对两组外周血标本进行CAG重复数测定,分析该微卫星多态性对激素避孕效果的影响。结果:试验组和对照组CAG重复数的均数分别为23.62和22.97,均数比较差异无显著性(P>0.05)。短组CAG(n≤22)在试验组和对照组的分布分别为51.7%、50.0%;长组CAG(n>22)在试验组和对照组分布分别为48.3%、50.0%,长短组分布相同。CAG重复数与精子密度之间未见相关性。在FSH浓度>0.2IU/L组中,CAG重复数>22的受试者达到无精子症的机会是其他受试者的1.5倍。结论:受试者AR基因(CAG)n重复数呈多态性,但不反应组与反应组之间不具有显著性差异,AR基因CAG重复数或其他因素与男性激素避孕效果之间的关系有待进一步探讨。     

中国人群雄激素受体基因CAG多态性与前列腺癌关系的研究

目的　探讨国人雄激素受体 (AR)基因CAG多态性分布及与前列腺癌的关系。　方法　采用PCR、DHPLC和直接测序方法 ,对 10 5例前列腺癌和 190例健康老年男性外周血标本进行AR基因CAG重复长度测定 ,分析评价CAG重复长度与前列腺癌易感性的关系。　结果　前列腺癌和对照组ARCAG平均重复长度分别为 2 2 .7和 2 3 .3 ,差异无显著性意义 (P =0 .2 2 )。CAG重复长度<2 2与≥ 2 2相比 ,患前列腺癌的危险性增加 2 .3 9倍 ,差异有显著性意义 (P =0 .0 12 )。　结论　中国男性人群AR基因短的CAG重复长度 (<2 2 )与前列腺癌的危险性有关。与西方人群研究结果相比 ,中国男性有长的CAG重复     

无精或严重少弱精症与雄激素受体基因重复多态性的关系

目的探讨无精或严重少弱精症患者与雄激素受体基因(CAG)n重复多态性的关系。方法应用DNA双链循环测序方法,对32例无精或严重少弱精症患者(不育组)、15例正常生育男性(对照组),进行外周血雄激素受体基因(CAG)n重复数的测定。结果不育组32例患者(CAG)n重复数为17~25,平均21.08±2.1;对照组15例为11~27,平均21.2±2.3。两者比较差异无统计学意义。结论无精或严重少弱精症患者与雄激素受体基因(CAG)n重复数的没有关系。     

尿道下裂患者MID1基因突变的研究

目的：探讨MID1基因在尿道下裂发病中的作用。方法：收集96例先天性尿道下裂患者外周静脉血，提取DNA，采用PCR扩增直接测序的方法检测MID1基因全部外显子序列。结果：在2个患者中发现2种突变，位于第一外显子的T64T同义突变和位于第九外显子的A620V错义突变，均没有报道过。结论：MID1基因在尿道下裂的发病中并不起主要作用。     

胃肠间质瘤KIT和PDGFRA基因突变的检测和意义

目的 探讨中国胃肠间质瘤(GIST)患者KIT和血小板源性生长受体α(PDGFRA)基因突变的特点,分析其临床意义.方法 对136例GIST患者肿瘤组织进行DNA抽提、聚合酶链反应(PCR)扩增和直接测序,检测KIT基因外显子9、11、13、17和PDGFRA基因12、18外显子突变;并对8例取得伊马替尼耐药瘤组织的患者进行2次检测.结果 在136例患者中,KIT突变111例(81.6%).其中外显子11突变95例(69.8%),外显子9突变16例(11.8%),未检测到PDGFRA突变的病例.KIT和PDGFRA野生型25例(18.4%).KIT外显子11突变最常见为5'缺失突变,共60例(60/95,63.2%),其次为点突变21例(21/95,22.1%);KIT外显子9突变均为插入串联重复,其中14例(14/16,87.5%)为常见的密码子502和503重复,而另外2例为罕见的密码子501和502重复.不同性别、年龄以及晚期GIST患者和潜在恶性的GIST患者间突变情况差异无统计学意义(P＞0.05);而不同部位GIST的KIT外显子11突变发生率差异有统计学意义(P＜0.01).伊马替尼耐药GIST的检测中发现1例继发的KIT外显子17点突变(Asp820Val+Tyr823Asp).结论 KIT基因突变在中国GIST患者中常见,不同部位间KIT外显子11突变差异有统计学意义.KIT继发性突变发生于靶向药物伊马替尼耐药的患者.     

多重引物HRMA对成骨不全患者COL1A1/2基因突变的筛查与分析

目的建立多重引物高分辨熔解曲线分析(high resolution melting analysis,HRMA)方法并运用该方法筛查两例成骨不全(osteogenesis imperfecta,OI) COL1A1/2的突变基因。方法收集两例OI患者临床资料,采集患者及50例正常对照的血液标本。设计COL1A1、COL1A2基因103个外显子所对应的引物,将满足一定条件的两对引物相互配对,与单份样本DNA混合作为扩增体系。运用HRMA筛查产物突变情况,基因测序确定突变位点。结果本研究中共涉及到COL1A1和COL1A2的103个外显子,其中成功配对39对,未配对成功的有3个COL1A1外显子和22个COL1A2外显子,成功率为75. 73%。先证者1筛查结果 HRMA熔解曲线在COL1A1 41号外显子上存在异常,测序结果为c.2877delT杂合突变,即c DNA2 877位碱基T缺失,编码的缬氨酸变成色氨酸。先证者2筛查结果 HRMA熔解曲线在COL1A1 16号外显子上存在异常,测序结果为c.1028delC杂合突变,即c DNA1 028位碱基C缺失,编码的脯氨酸变成亮氨酸。两种突变类型在中国人群中均未见报道,为新发现的两种剪切突变,且与传统HRMA筛查结果一致。结论多重引物HRMA方法在传统HRMA基础上进行了创新,将两对引物与单份样本DNA混合作为扩增体系,HRMA筛查产物突变情况,且与传统HRMA筛查结果一致,具有一定创新性和可行性,为成骨不全患者基因突变及其他遗传病致病基因的筛查提供了新的思路。     

The CAG trinucleotide repeat length in the androgen receptor does not predict the early onset of prostate cancer

OBJECTIVE: To relate the repeat length of the androgen-receptor CAG trinucleotide to the age of onset of prostate cancer, stage and grade of disease. PATIENTS AND METHODS: After obtaining ethical approval, 265 patients with locally confined or locally advanced/metastatic prostate cancer were identified and evaluated for age at diagnosis (< 65 years and > 75 years). DNA was extracted from peripheral blood lymphocytes and 1 micro g aliquots subjected to polymerase chain reaction using fluorescently labelled primers. Samples were then run on an ABI 377 gene scan analysis gel with an internal molecular weight marker. The length of the CAG repeat was determined by comparing the gene scan product size to samples where the CAG repeat length had been quantified using direct sequencing. The Kruskal-Wallis, Mann-Whitney and Wilcoxon two sample tests were used to analyse the data. RESULTS: The mean (range) length of the CAG repeat in the androgen receptor was 22.2 (10-31) in the younger and 22.5 (16-32) in the older group, and was not statistically different. There was no significant association between the CAG repeat length and the age of onset of prostate cancer (P = 0.568) or with stage (P = 0.577) and grade (P = 0.891) of prostate cancer. CONCLUSION: These results suggest that there is no correlation between the androgen receptor CAG repeat length and the age of onset, stage and grade of prostate cancer, confirming recent doubts from other similar studies of a suggested correlation between shorter androgen receptor CAG repeat and early onset and aggressiveness of prostate cancer.     

Significance of the CAG repeat polymorphism of the androgen receptor gene in prostate cancer progression

PURPOSE: The CAG repeat polymorphism of the androgen receptor gene has been associated with an increased prostate cancer risk, and the repeat length correlated with cancer stage and grade at presentation. Men with an allele length of 18 CAG repeats, controlling for grade, stage and serum PSA level at diagnosis using Cox proportional hazard modeling. RESULTS: Overall, the CAG repeat allele was not predictive of recurrence; tumor grade, stage and PSA level at diagnosis were the only predictors of recurrence in a multivariate analysis. However, for patients at low risk for recurrence (Gleason score 2 to 6, stage pT2, and PSA 18 CAG repeats. In contrast, for patients at high risk of recurrence (Gleason score >/= 7, stage pT3/4, or PSA >10 ng./ml.), the relative risk associated with the 18 CAG repeat allele. CONCLUSIONS: The length of the CAG repeat polymorphism of the androgen receptor gene may be important for prostate cancer recurrence among patients who are otherwise at low risk for recurrence after radical prostatectomy. These findings have potential implications for patient selection for adjuvant treatment, and for the development of novel treatments.     

The role of an androgen receptor polymorphism in the clinical outcome of patients with metastatic prostate cancer

The androgen receptor plays a major role in the development and function of normal and malignant prostate cells. Due to the relationship of the androgen receptor and prostatic growth, it has been proposed that polymorphisms within the androgen receptor may play a role in an individual's susceptibility to developing prostate cancer. An inverse relationship has been established between a highly polymorphic trinucleotide repeat located in the first exon of the androgen receptor and the transactivaton function of the receptor. Serum samples were collected from 131 patients with histologically confirmed adenocarcinoma of the prostate, DNA was isolated, and the polymorphic CAG repeat was amplified by PCR and sequenced. The CAG repeat lengths were then compared with age at diagnosis, age at time of study, baseline log(10) PSA, Gleason score, time from diagnosis to initiation of hormonal therapy, time to progression after androgen ablation, and overall survival time. No correlation was found between CAG length and time to progression or overall survival time, but a significant correlation was found between Gleason score and CAG length suggesting that shorter CAG lengths may predict a higher histological grade of prostate cancer.     

Germline CAG repeat length of the androgen receptor and time to progression in patients with prostate cancer treated with androgen deprivation therapy

Study Type – Prognosis (retrospective cohort) Level of Evidence 2b What’s known on the subject? and What does the study add? Germline CAG repeat polymorphisms in the androgen receptor (AR‐CAG) have been shown to influence the activity of the androgen receptor, but there has been conflicting data from small retrospective studies evaluating the effect of CAG repeat polymorphisms on response to ADT. This is the largest published study to date investigating the association of germline AR‐CAG repeat lengths and efficacy of ADT in prostate cancer. Germline AR‐CAG repeat lengths do not predict response to ADT.

OBJECTIVES

? Germline CAG repeat polymorphisms in the androgen receptor (AR‐CAG) have been shown to influence the activity of the AR. ? The purpose of the present study was to determine if AR‐CAG repeat length correlates with time to progression on androgen deprivation therapy (ADT).

PATIENTS AND METHODS

? Germline AR‐CAG repeat lengths were determined in a cohort of 480 patients with recurrent or metastatic prostate cancer treated at a single tertiary care institution and correlated to time to progression (TTP) and overall survival.

RESULTS

? There was no significant correlation between differences in the AR‐CAG repeat lengths and TTP or overall survival in patients with prostate cancer receiving ADT. ? AR‐CAG repeat lengths did not significantly correlate with age, prostate‐specific antigen (PSA), Gleason score or clinical stage at diagnosis. ? In patients with metastatic disease, longer AR‐CAG repeat lengths (>23 vs ≤23) were associated with a longer TTP on ADT, but this finding was of borderline significance (median TTP 18.3 vs 15.5 months, P= 0.09; adjusted HR = 0.76, 95% confidence interval = 0.54–1.09).

CONCLUSIONS

? This is the largest published study to date investigating the association of germline AR‐CAG repeat lengths and efficacy of ADT in prostate cancer. ? Germline AR‐CAG repeat lengths do not predict response to ADT.     

Linkage disequilibrium between the androgen receptor gene CAG and GGC repeats in the African-American population

African-American men are at an increased risk of developing prostate cancer when compared with other racial and ethnic groups. In addition, African-Americans display a greater propensity for developing aggressive prostate cancer. There are multiple etiologic factors that likely contribute to the development of prostate cancer; however, one potential factor that may explain differences of prostate cancer risk among ethnic and racial groups is the androgen receptor (AR) gene. Studies have showed that there is correlation between two polymorphic microsatellite regions of the AR receptor gene and its transactivational activity. The CAG and GGC repeats both have been implicated as important loci for variation in differential androgen receptor activity. This review analyzes the available data regarding variation of the CAG and GGC repeat sequences among different racial and ethnic populations, and the implications of these variations for prostate cancer risk.     

A case of spinal and bulbar muscular atrophy with high-stage and high-Gleason Score prostate cancer responded to maximal androgen blockade therapy

Spinal and bulbar muscular atrophy is a hereditary motor neuron disease caused by the expansion of CAG triplets in the androgen receptor. Because the length of CAG repeat is inversely related with androgen receptor function, patients with a longer CAG repeat are expected to have a lower incidence of prostate cancer. Here, we report an extremely rare case of high-stage prostate cancer in a patient with spinal and bulbar muscular atrophy, which responded to maximal androgen blockade therapy.     

CAG polymorphic repeat length in androgen receptor gene combined with pretreatment serum testosterone level as prognostic factor in patients with metastatic prostate cancer

OBJECTIVE: Androgen ablation has been the initial treatment of choice for men with metastatic prostate cancer, but the disease generally relapses to an androgen-independent state thereafter. To understand which groups respond well or poorly to endocrine therapy is thus important. Several studies have shown that pretreatment serum testosterone (T) levels and the length of the CAG repeat at the N-terminal region of the androgen receptor are significant. However, the relevance of a combination of these factors has not been reported. We therefore investigated the clinical significance of CAG repeat length and pretreatment serum T levels among Japanese patients with metastatic prostate cancer (TxNxM1), and analyzed their relevance to survival. METHODS: Fifty-two Japanese patients with metastatic prostate cancer were enrolled in this study. We determined the length of the CAG repeat by both PCR sequencing and fragment analysis. Pretreatment serum T levels were measured using a radioimmunoassay. We examined the clinical significance of the CAG repeats and T levels individually and in combination with respect to several clinical factors. RESULTS: The pretreatment T level in the responder group was significantly higher than that in the non-responders (p=0.009) and the mean was 4.33+/-2.12 ng/ml. Kaplan-Meier analyses revealed that cause-specific survival was significantly enhanced in patients with higher levels of T (p=0.0489). The length of the CAG repeat was positively associated with age at diagnosis (p=0.032). The mean CAG repeat length was 22.5+/-3.0 and this value was significantly shorter in patients with poorly differentiated, than with well and moderately differentiated tumors (p=0.019). Kaplan-Meier analyses revealed a significantly better cause-specific survival rate as well as progression-free survival rate in patients with longer CAG repeats. Cause-specific survival curves were better in patients with higher T levels and longer CAG repeats than with lower T levels and shorter CAG repeats (p=0.0066). A multivariate analysis showed that the most significant prognostic factor was histological grade, followed by EOD grade, marker response and the combination of T and CAG. CONCLUSION: Pretreatment serum T levels together with the length of the N-terminal CAG repeat of the androgen receptor gene can distinguish responders from non-responders to androgen ablation. These parameters appear to be clinically useful, in that therapies appropriate to individual patients could be selected. Further studies are necessary to confirm these results.     

Androgen receptor CAG repeat length contraction in diseased and non-diseased prostatic tissues

To investigate contraction of CAG repeats within the androgen receptor gene (AR) as shorter CAG repeats have been implicated as a possible risk factor in prostate cancer (PCa). AR CAG repeat lengths were analyzed in DNA from microdissected diseased prostates, leukocytes from matched peripheral blood, and control non-diseased prostates. Consistently, all prostatic tissues, whether from benign or cancerous areas of diseased prostates, or from control prostates, showed multiple AR CAG repeat contractions. Germline DNA from blood leukocytes had single CAG repeat lengths in the normal range. AR CAG repeat length contraction may be involved in prostate carcinogenesis and may precede the pathological process.     

Effect of a short CAG (glutamine) repeat on human androgen receptor function

BACKGROUND: The human androgen receptor (AR) gene contains an uninterrupted CAG repeat that is polymorphic in length in the general population (range, 11-31 CAG's; median, 21). The CAG repeat encodes a glutamine repeat in the N-terminal transactivation domain of the AR protein. We previously reported that a 17-CAG AR gene was much more common in a cohort of men with prostate cancer (8.5%) than in the general European American population (1.3%). This suggested that a 17-CAG repeat may have pathophysiological consequences. The goal of the present study was to directly test the hypothesis that a 17-CAG repeat might uniquely affect androgen action in human prostate cancer cells. METHODS: DU145 cells, lacking endogenous AR, were transiently transfected with an AR expression plasmid (with a CAG repeat ranging in length from 14 to 25) and an androgen-responsive reporter plasmid (PSA-luciferase). RESULTS: We found a significant effect of CAG repeat length on AR protein levels per unit amount of DNA transfected (one-way ANOVA, P = 0.02), indicating the need to express transactivation data per unit amount of AR protein. CAG17 AR had 40% more transactivation activity per unit amount of AR protein than CAG21 AR (P < 0.01). CONCLUSIONS: Thus, an AR with a 17-CAG repeat may mediate more efficacious growth stimulation of androgen-dependent prostate epithelial cells, and thereby increase the risk that prostate cancer cells develop more efficiently into a clinically significant cancer.