结直肠癌K-ras基因突变与临床病理特征的相关性分析

 【摘要】 目的：研究结直肠癌组织中K-ras基因的突变情况与临床病理特性之间的相关性。 目的　研究结直肠癌组织中K-ras基因的突变情况与临床病理特性之间的相关性。方法　采用直接测序法对90例结直肠癌石蜡标本进行K-ras基因突变检测,并对K-ras基因的突变情况及其与结直肠癌患者临床病理特征的关系进行统计学分析。结果　90例结直肠癌患者组织中,K-ras基因12、13密码子总突变者31例,总突变率为34.4 %。12密码子单突变21例,突变率为23.3 %;双突变1例。13密码子突变者9例,突变率为10.0 %。结直肠癌K-ras基因突变率与肿瘤部位有明显相关性（P＝0.042）。12密码子单突变和13密码子突变与临床病理参数均无明显相关性（P＞0.05）。结论　不同肿瘤部位患者的K-ras基因突变率存在明显不同。     

结直肠癌患者KRAS和BRAF基因突变检测及其临床意义

目的探讨结直肠癌患者组织中KRAS和BRAF基因突变情况,分析突变与临床病理特征的关系。方法应用荧光PCR-优化寡核苷酸探针法检测304例结直肠癌石蜡包埋标本中KRAS基因2号外显子的12和13密码子、BRAF基因的15号外显子的突变情况,分析KRAS和BRAF基因突变与临床病理特征的关系。结果 KRAS和BRAF基因在结直肠癌的突变率分别为38.8%(118/304)和4.3%(13/304)。KRAS基因突变阳性标本中12密码子的突变率为78.0%,其中p.G12D发生率最高,占总突变的45.3%;13密码子的突变率为22.0%。高年龄组(≥60岁)患者的KRAS基因突变率为47.2%(58/123),高于低年龄组(<60岁)的33.1%(60/181),差异有统计学意义(P<0.05)。转移性结直肠癌患者19例,其KRAS基因突变率为36.8%(7/19),与285例原发性结直肠癌患者的突变率(38.9%,111/285)差异无统计学意义(P>0.05)。BRAF基因在结肠、低分化、黏液腺癌患者中的突变率明显高于直肠、中或高分化和管状腺癌的患者。结论结直肠癌患者中KRAS基因突变的发生率较高,与年龄相关,而与性别、部位、病理类型和分化程度不相关。BRAF基因突变与肿瘤部位、病理类型和分化程度有关。原发性与转移性结直肠癌患者KRAS基因突变率无明显差异。     

结直肠癌原发灶、相应肝转移灶K-ras基因状态的研究

目的 观察结直肠癌患者原发肿瘤组织及相应肝转移灶K-ras基因突变情况,分析二者的一致性.探讨结直肠癌K-ras基因状态与肝转移关系.方法 实时荧光定量PCR技术和基因测序技术检测76例结直肠癌患者原发肿瘤组织及其中22例肝转移灶K-ras基因突变,结合其临床资料分析.结果 76例结直肠癌组织中25例(32.9%)发现K-ras基因突变;22例肝转移灶中11例(50%)发现K.ras基因突变,其中10例对应原发癌组织也发现K-ras基因突变.1例对应原发癌组织未发现突变.原发癌组织与肝转移灶K-ras基因状态一致率为90.9%.肝转移患者原发癌组织K-ras基因突变率明显高于无肝转移患者(P<0.05).原发肿瘤组织和7例同时性、2例异时性肝转移灶的K-ras基因突变类型基本一致(即K-ras基因12密码子GGT突变为GAT或GTr).1例异时性和1例同时性肝转移灶K-ras基因突变类型为13密码子GGC突变为GAC.结论 结直肠癌的原发癌组织与肝转移灶的K-ras基因状态较为一致,原发癌组织有K-ras基因的突变,预示着肿瘤有肝脏转移倾向.     

国人结直肠癌k-ras基因突变状态及其对抗EGFR单抗联合化疗的反应

 目的　观察国人结直肠癌k-ras基因突变情况,及抗表皮生长因子受体（EGFR）单抗联合化疗治疗晚期结直肠癌的近期疗效和患者不良反应。方法　收集139例结直肠癌手术或肠镜标本,采用焦磷酸测序法检测k-ras突变状态。应用抗EGFR单抗联合化疗治疗晚期结直肠癌23例,初治3例,复治20例。23例患者中西妥昔单抗联合化疗者18例,尼妥珠单抗联合化疗者5例。西妥昔单抗首次给予负荷剂量400 mg／m2,而后每周维持量为250 mg／m2。尼妥珠单抗首剂400 mg,以后200 mg／周维持治疗。23例中有8例联合依立替康单药;12例为联合FOLFIRI方案;3例联合FOLFOX4方案。结果　全组139例患者检测k-ras的突变状态,其中突变型55例（39.6 %）;野生型 84例（60.4 %）。全组22例可评价疗效,其中PR 5 例,SD 9例,RR率22.7 %,DCR率63.6 %。中位疾病进展时间（TTP）为124 d。共有13例患者送检k-ras检测。11例k-ras野生型的患者中,4例获得PR;4例SD;3例PD。2例k-ras突变型的患者治疗2个周期后PD。18例应用西妥昔单抗中,15例（83.3 %）出现痤疮样皮疹,3例出现甲沟炎。尼妥珠单抗应用者未出现皮疹和甲沟炎。2例应用西妥昔单抗患者出现Ⅲ度超敏反应。1例第2周期换用尼妥珠单抗后未出现过敏反应。结论　国人结直肠癌k-ras基因突变率与西方人相似。西妥昔单抗与化疗联合在晚期结直肠癌的治疗上疗效确切,尼妥珠单抗联合化疗治疗晚期结直肠癌苗头喜人,并且不良反应轻微,值得进一步研究。     

结直肠癌原发灶与转移灶K-ras基因突变的比较分析

背景与目的：K-ras基因突变是抗表皮生长因子受体(epidermal growth factor receptor,EGFR)靶向治疗的重要负性预测因子。本研究拟对结直肠癌原发灶与转移灶中K-ras基因状态的一致性进行比较,以探讨目前临床K-ras检测的科学性与严谨性。方法：收集复旦大学附属肿瘤医院手术切除的结直肠癌原发灶及转移灶石蜡包埋组织76对,提取DNA,经过PCR扩增后,对产物进行基因序列分析,检测结直肠癌中K-ras基因外显子2基因序列。结果：76例患者中有15例结直肠癌原发灶与转移灶的K-ras基因突变情况不一致。76例结直肠癌原发灶有31例发生突变,突变率为40.8%,其中第13号密码子突变16例,第12号密码子突变15例;76例结直肠癌转移灶有31例发生突变,突变率为40.8%,其中第13号密码子突变15例,第12号密码子突变16例。结论：结直肠癌原发灶和转移灶中K-ras基因状态并不一致,且存在19.7%的表达差异率,提示通过检测原发灶K-ras基因表达状态来确定针对转移灶的西妥昔单克隆抗体药物选择存在不严谨性,需要进一步完善。     

高分辨率熔解曲线技术检测结直肠癌患者KRAS基因突变

目的探讨高分辨率熔解曲线技术(HRM)检测结直肠癌患者KRAS基因突变的可行性及其临床意义。方法采用HRM技术检测60例结直肠癌患者石蜡包埋组织标本KRAS基因2号外显子12和13位密码子突变,并与Sanger测序法检测结果进行对比分析。结果 HRM法检测结直肠癌患者KRAS基因2号外显子12和13位密码子突变检出率为36.67%(22/60),Sanger测序法检测突变检出率为33.33%(20/60)。HRM法检测突变检出率高于Sanger测序法,HRM法检测敏感性为100%,特异性为95.24%。结论 HRM法检测KRAS基因突变,灵敏度高,敏感性和特异性好,具有操作简便、节约时间、成本低的特点,方法可行。     

中国非小细胞肺癌患者K-Ras和EGFR基因突变与临床病理特征的关系

目的 探讨中国非小细胞肺癌（NSCLC）患者中K-Ras和表皮生长因子受体（EGFR）基因突变情况及其与临床病理特征的关系。方法 回顾性分析2011年7月至2013年8月广州医科大学附属第一医院收治的381例NSCLC患者的临床病理特征,并应用扩增突变阻滞系统（ARMS）检测其癌组织中EGFR基因18、19、20、21外显子共21个点突变和K-Ras基因12、13密码子共6个点突变,分析其突变情况及与临床病理特征的相关性。结果 21例（5.5％）存在K-Ras基因突变,其中20例12密码子,1例13密码子Asp突变;146例（38.3％）存在EGFR突变,其中4例18外显子突变（G719S）,52例19号外显子序列缺失突变,3例20外显子序列缺失突变,85例21外显子突变（81例L858R,4例L861Q）,2例双突变。男性患者K-Ras基因突变率高于女性患者,差异有统计学意义（6.8％ vs. 2.5％, P=0.018）。EGFR基因突变与性别、吸烟史、临床分期、全身转移、病理类型均有关（P＜0.05）。二分类Logistic回归分析显示,病理类型和性别与EGFR基因突变密切相关。结论 中国NSCLC患者中EGFR突变常见,该突变与腺癌有关;K-Ras基因突变率较低,多见于男性,其他相关因素尚需进一步研究。     

结直肠癌Ras、BRAF和PIK3CA基因突变分析及与临床病理特征的关系

目的 分析结直肠癌患者中Ras（K-Ras／N-Ras）、BRAF和PIK3CA基因突变情况及其与临床病理特征的关系。方法 回顾性分析2013年12月至2014年10月于北京大学肿瘤医院消化肿瘤内科接受诊治的200例结直肠癌患者的肿瘤组织标本,采用PCR扩增-直接测序法检测Ras,包括K-Ras（第2、3、4外显子）、N-Ras（第2、3、4外显子）、BRAF（第15外显子）及PIK3CA（第9、20外显子）基因的突变状态,分析其与结直肠癌临床病理特征的关系。结果 200例患者中存在Ras基因突变92例（46.0％）,其中K-Ras基因突变87例（43.5％）,主要发生在外显子2,N-Ras基因突变5例（2.5％）;其中1例患者存在K-Ras、N-Ras基因同时突变。存在BRAF基因突变15例（7.5％）,突变类型均为V600E,且与K-Ras突变存在排他性。存在PIK3CA基因突变9例（4.5％）,可与Ras或BRAF基因突变共存。Ras（K-Ras／N-Ras）基因在年龄≥65岁患者中的突变率明显高于＜65岁者（P＜0.05）,其表达与性别、原发部位、组织学类型、分化程度、TNM分期、区域淋巴结转移、远处转移、术后复发转移均无关（P均＞0.05）。BRAF、PIK3CA基因在原发部位为右半结肠患者中的突变率明显升高（P＜0.05）,但与年龄、性别、组织学类型、分化程度、TNM分期、区域淋巴结转移、远处转移、术后复发转移均无关（P＞0.05）。结论 N-Ras、PIK3CA基因在中国结直肠癌患者中的突变率较低。K-Ras、N-Ras基因突变与年龄相关,BRAF、PIK3CA基因与肿瘤原发部位相关;对结直肠癌患者进行Ras（K-Ras／N-Ras）、BRAF及PIK3CA基因的联合检测将会为提高临床靶向治疗的疗效提供更加可靠的依据。     

169例国人结直肠癌患者BRAF基因的突变状态分析

目的 探讨国人结直肠癌患者鼠类肉瘤病毒癌基因同源物B1（BRAF）基因的突变状态,以期能为针对表皮生长因子受体（EGFR）的靶向治疗提供指导。方法 采用PCR测序法检测169例结直肠癌组织BRAF基因的突变情况。结果 在169例结直肠癌组织中,BRAF基因在第600位密码子（V600E）发生突变,突变频率为5.3％。BRAF基因在84例男性结直肠癌患者中的突变频率为7.1％,在85例女性患者中为3.5％,差异无统计学意义（P=0.329）。在17例结直肠癌年轻患者（25～44岁）中未检测到BRAF基因突变,在67例中年患者（45～59岁）中BRAF基因的突变频率为3.0％,在85例老年患者（60～90岁）中为8.2％,三者之间差异无统计学意义（P=0.211）。结论 BRAF基因的突变频率与结直肠癌患者的性别和年龄无关。     

结直肠癌NRAS基因突变检测及其临床意义结直肠癌NRAS基因突变检测及其临床意义

目的:探索结直肠癌NRAS基因突变的特征及其临床意义。方法:收集214例江南大学附属医院2014年3月至2015年1月收治的结直肠癌患者术后石蜡包埋组织标本,采用扩增受阻突变体系检测上述标本的NRAS基因第二、三、四外显子的突变情况,结合临床病理参数分析该项检测的意义。结果:214例结直肠癌患者中有8例NRAS基因发生突变,NRAS基因突变率3.74%。第二、三外显子均突变四例,尚未发现第四号外显子的突变。NRAS突变状况在不同的性别、分化程度、组织学类型和淋巴结转移情况中尚未观察到明显差异。结直肠癌患者中NRAS基因的突变状况与其免疫表型ALK、Ki67、CAM5.2、Her-2无明显相关性。结论:结直肠癌NRAS基因的突变较低,主要为第二、三外显子的突变。NRAS基因的突变状况与性别、年龄、分化程度、免疫表型的相关性有待进一步证实。     

Clinical Significance of Somatic Mutations in RAS/RAF/MAPK Signaling Pathway in Moroccan and North African Colorectal Cancer Patients

Background: Mutations in RAS (KRAS, NRAS) and BRAF genes are the main biomarker predicting response to anti-EGFR monoclonal antibodies in targeted therapy in colorectal cancer (CRC). Objective: Our study aims to evaluate the frequencies of KRAS, NRAS and BRAF mutations and their possible associations with clinico-pathological features in CRC patients from Morocco. Methods: DNA was extracted from 80 FFPE samples using the QIAamp DNA FFPE-kit. RAS and BRAF mutations were assessed by pyrosequencing assays using Qiagen, KRAS Pyro®kit 24.V1, Ras-Extension Pyro®kit 24.V1 and BRAF Pyro®Kit 24.V1, respectively, and carried out in the PyroMark-Q24. Results: RAS mutations were identified in 57.5% (56.2% in KRAS, 8.8% in NRAS). In KRAS gene, exon 2 mutations accounted for 93.3% (68.9% in codon 12, 24.4% in codon 13). Within codon 12, G12D was the most prevalent mutation (37.7%), followed by G12C (13.4%), G12S (8.9%) and G12V (6.6%). Within codon 13, the most frequently observed mutation was G13D (22.3%). The mutation rates of exon 3 and 4 were 15.6% and 13.3%, respectively. In exon 3 codon 61, 2.3% patients were detected with two concurrent mutations (Q61R, Q61H), and 4.4% with three concurrent mutations (Q61R, Q61H, Q61L). In NRAS gene, the mutation rates of exon 2, 3 and 4 were 57.1%, 28.6%, and 14.3%, respectively. G13A and Q61H were the most common mutations, accounting for 42.9% and 28.5%, respectively. There were 13% patients with concurrent KRAS/NRAS mutation and 4.3% wt KRAS with NRAS mutations. No mutations were identified in BRAF gene. In both sexes, KRAS codon 12 mutations were associated with higher stage III/IV tumors. Moreover, Patients whose tumor is in the proximal colon (56.3%) are more likely to harbor KRAS mutations than those tumor located in rectum (25%). Conclusion: RAS mutations could be useful in future target anti-EGFR therapy and molecular CRC screening strategy in Morocco.     

Somatic Mutations of K-Ras and BRAF in Thai Colorectal Cancer and their Prognostic Value

Background: The study aimed to determine the incidence of K-ras and BRAF mutations in colorectal cancers(CRCs) in Thai patients and evaluate association with clinicopathological parameters including treatmentoutcomes in terms of event free survival (EFS). Materials and Methods: Two-hundred colorectal cancer specimenswere collected for studies of K-Ras codon 12, 13 and 61, and BRAF codon 600 by polymerase chain reaction anddirect nucleotide sequencing. Results: The overall incidence of K-Ras mutations in our patients was 23%. K-rasmutation frequencies in CRC stages (AJCC) I, II, III and IV were 6.7%, 16.1%, 23.3% and 26.6%, respectively(p-value>0.05). The three most common mutation forms were G12D, G12V and G13D. K-Ras mutation status wasassociated with poorer EFS in stage I-III CRCs (p-value 0.03). Conclusions: The study found a lower mutationfrequency of K-Ras and BRAF compared to reports involving other ethnic groups. However, K-Ras mutationsdid have a negative prognostic value in early-stage CRCs.     

Mutational analysis of ras gene family in lung cancer in Thai

H-, K- and N-ras gene mutations were analyzed in lung cancer from Thai patients. Thirteen out of 58 cases (22%) harbored the mutations. Ten cases showed K-ras gene mutations at codon 12, 1 case presented a mutation at codon 13 and another case exhibited a mutation at codon 63. Silent mutations of N-ras gene in codons 57 and 62 were seen in one patient, whilst no H-ras mutation was found in these patients. Bases change in K-ras gene were G right curved arrow T transversion (62%), G right curved arrow A transition (15%) and G right curved arrow C transition (15%), whereas T right curved arrow G transversion and A right curved arrow G transition were detected in N-ras mutant gene.     

Molecular spectrum of KRAS,BRAF, and PIK3CA gene mutation: determination of frequency,distribution pattern in Indian colorectal carcinoma

Molecular evaluation of KRAS, BRAF, and PIK3CA mutation has become an important part in colorectal carcinoma evaluation, and their alterations may determine the therapeutic response to anti-EGFR therapy. The current study demonstrates the evaluation of KRAS, BRAF, and PIK3CA mutation using direct sequencing in 204 samples. The frequency of KRAS, BRAF, and PIK3CA mutations was 23.5, 9.8, and 5.9 %, respectively. Five different substitution mutations at KRAS codon 12 (G12S, G12D, G12A, G12V, and G12C) and one substitution type at codon 13 (G13D) were observed. KRAS mutations were significantly higher in patients who were >50 years, and were associated with moderate/poorly differentiated tumors and adenocarcinomas. All mutations in BRAF gene were of V600E type, which were frequent in patients who were ≤50 years. Unlike KRAS mutations, BRAF mutations were more frequent in well-differentiated tumors and right-sided tumors. PIK3CA–E545K was the most recurrent mutation while other mutations detected were T544I, Q546R, H1047R, G1049S, and D1056N. No significant association of PIK3CA mutation with age, tumor differentiation, location, and other parameters was noted. No concomitant mutation of KRAS and BRAF mutations was observed, while, interestingly, five cases showed concurrent mutation of KRAS and PIK3CA mutations. In conclusion, to our knowledge, this is the first study to evaluate the PIK3CA mutation in Indian CRC patients. The frequency of KRAS, BRAF, and PIK3CA was similar to worldwide reports. Furthermore, identification of molecular markers has unique strengths, and can provide insights into the pathogenic process and help optimize personalized prevention and therapy.     

结直肠癌组织中KRAS和BRAF基因突变与临床病理特征及预后的关系

目的:探讨结直肠癌组织中KRAS和BRAF基因突变与临床病理和预后的关系。方法:采用扩增阻滞突变系统（ARMS）方法对134例结直肠癌组织进行回顾性分析。结果:134例CRC组织中KRAS基因突变率49.3%（66/134）,第2外显子突变率42.5%（57/134）,其中12及13密码子突变率分别为35.1%（47/134）和7.5%（10/134）,第3外显子61密码子突变率1.5%（2/134）,第4外显子117/146密码子突变率5.2%（7/134）,BRAF V600E突变率4.5%（6/134）。左半结肠KRAS基因突变率54.5%（54/99）高于右半结肠34.3%（12/35）,差异有统计学意义（P＜0.05）,右半结肠BRAF基因突变率14.3%（5/35）高于左半结肠1.0%（1/99）,差异有统计学意义（P＜0.05）,而KRAS和BRAF基因突变与性别、年龄、民族、肿块大小、分化程度、淋巴结转移及病理分期等临床病理特征,差异均无统计学意义（P＞0.05）。KRAS基因突变型CRC患者的中位生存时间48个月（39.9%）,与野生型47个月（46.2%）相比较,差异无统计学意义（P＞0.05）。BRAF基因突变型CRC患者的中位生存时间21个月（26.7%）,与野生型48个月（44.7%）相比较,差异有统计学意义（P＜0.05）。多因素COX回归风险模型结果显示,BRAF基因突变型是CRC患者预后不良的独立危险因素（B=1.664,OR=5.278,95%CI:1.505~18.516, P＜0.05）,而性别、年龄、民族、肿块大小、分化程度、肿瘤部位、淋巴结转移及病理分期均不是CRC患者生存时间的独立危险因素（P＞0.05）。结论:CRC组织中KRAS基因突变率高,BRAF基因突变率低。KRAS和BRAF基因突变型与肿瘤部位有关。BRAF基因突变型是CRC预后不良的独立危险因素。     

Distribution of KRAS and BRAF Mutations in Metastatic Colorectal Cancers in Turkish Patients

The results of this study demonstrate the potential prognostic and predictive values of KRAS and BRAF gene mutations in patients with colorectal cancer (CRC). It has been proven that KRAS and BRAF mutations are predictive biomarkers for resistance to anti-EGFR monoclonal antibody treatment in patients with metastatic CRC (mCRC). We demonstrated the distribution of KRAS (codons 12, 13 and 61) and BRAF (codon 600) gene mutations in 50 mCRCs using direct sequencing and compared the results with clinicopathological data. KRAS and BRAF mutations were identified in 15 (30%) and 1 (2%) patients, respectively. We identified KRAS mutations in codon 12, 13 and 61 in 73.3% (11/15), 20% (3/15) and 6.67% (1/15) of the positive patients, respectively. The KRAS mutation frequency was significantly higher in tumors located in the ascending colon (p=0.043). Thus, we found that approximately 1/3 of the patients with mCRC had KRAS mutations and the only clinicopathological factor related to this mutation was tumor location. Future studies with larger patient groups should yield more accurate data regarding the molecular mechanism of CRC and the association between KRAS and BRAF mutations and clinicopathological features.     

The prognostic value of KRAS mutations in patients with colorectal cancer

Our aim was to evaluate the KRAS genotypes of Japanese colorectal cancer (CRC) patients and to assess the effect of these genotypes on clinical outcome. A total of 99 patients with stage I-IV CRC who underwent resection were prospectively studied for KRAS mutations by direct sequencing. KRAS mutations were found in 37 (37.4%) of 99?patients. Of these, 11.1% were the KRAS p.G13D mutation and the remaining 26.2% were other KRAS mutations. The cumulative 5-year survival rates for patients with wild-type KRAS, KRAS 12 and KRAS p.G13D mutations were 81.4, 61.4 and 42.0%, respectively (P=0.0397). The KRAS genotype had no effect on stage IV patient prognosis without anti-epithelial growth factor receptor (EGFR) antibody therapy. However, in stage I-III patients significant or trends in prognostic factors for disease-free survival (DFS) were pathological T stage, lymphatic vessel involvement and KRAS p.G13D. Multivariate analysis identified T4 pathological stage (P=0.0076) and the KRAS p.G13D mutation (P=0.0499) as the most significant independent prognostic factors associated with DFS. In Japanese CRC patients KRAS p.G13D had prognostic impact on DFS in stage I-III disease, while the prognosis of stage IV patients without anti-EGFR antibody therapy was unaffected by KRAS status.     

NAD(P)H:quinone oxidoreductase-dependent risk for colorectal cancer and its association with the presence of K-ras mutations in tumors

NAD(P)H:quinone oxidoreductase (NQO1) is a polymorphic enzyme involved in the detoxification of potentially mutagenic and carcinogenic quinones. The homozygous C609T NQO1 genotype resulting in loss of reductase activity is found in 2-20% of individuals. In the present study, the NQO1-dependent risk for sporadic colorectal cancer (CRC) was studied in 247 incident CRC cases and 296 hospital-based controls recruited during 1996-1997. Four subgroups of cases were studied: (i) all CRCs; (ii) a molecular CRC subgroup (n = 117, cases with molecular tumor analyses); (iii) within the molecular subgroup those tumors with K-ras mutations in codon 12 (CRC K12); (iv) within the molecular subgroup those tumors with K-ras mutations in codon 13 (CRC K13). The C609T NQO1 genotype was found to be twice as prevalent in all CRC patients (6.8%) compared with controls (3%) and six times more common in the subset CRC K12 (20%). Multivariant analyses in the overall population of 247 cases and 296 controls showed a significant age and gender adjusted risk for CRC associated with the C609T NQO1 genotype (OR 2.9, 95% CI 1.19-6.97; P = 0.01) or with any variant genotype (the low activity allele frequency, i.e. heterozygotes plus homozygotes) (OR 1.41, 95% CI 1.02-1.92; P = 0.03). Within cases of the molecular subgroup (n = 117) the C609T NQO1 genotype was associated with the presence of K-ras codon 12 mutation (OR 6.5 95%, CI 1.39-34.9; P = 0.003). Logistic regression showed an age and gender adjusted risk for K-ras codon 12 mutant CRC associated with the C609T NQO1 genotype (OR 10.5, 95% CI 2.99-36.7; P: = 0.0002) or with any variant NQO1 genotype (OR 2.23, 95% CI 1.23-4.00; P = 0.007) compared with the control group. Genetically determined variations in NQO1 may modify the risk for CRC and these risks may be greatest for tumors containing K-ras codon 12 mutations. CRC with K-ras codon 12 mutations may represent a distinct and etiologically more homogeneous subtype of the disease, which may be associated with toxicants that are metabolized via a NQO1-dependent pathway.     

Common KRAS and NRAS gene mutations in sporadic colorectal cancer in Northeastern Iranian patients

ObjectivesMutation analysis of the Epidermal Growth Factor Receptor downstream has been a main part of colorectal carcinoma evaluation. Large prospective clinical trials have shown only colorectal cancer (CRC) with wild-type KRAS and NRAS responds to anti-Epidermal Growth Factor Receptor treatment. Hence, mutation analysis is necessary prior to treatment. It is essential to conduct studies to learn about the mutation signature of such tumors. The aim of this study was to evaluate the frequency of hotspot mutations in KRAS and NRAS genes in Iranian CRC patients and to explore their correlations with clinicopathologic parameters.MethodsWe detected mutations in exon 2 (codons 12 and 13) of the KRAS and NRAS genes using high resolution melting analysis, Intplex design and Sanger sequencing in 87 Iranian CRC patients. Genomic DNA was isolated from fresh tissue samples of CRC patients.ResultsFrom 87 eligible cases, 51 were male and 36 were females. KRAS mutations in codons 12 and 13 were present in 28.7% of all analyzed CRCs. Our findings suggested that the tumors with KRAS mutations are not with well- and moderately differentiated tumors compared to poorly differentiated tumors (P value = 0.32). The most frequent types of mutations were glycine to aspartate on codon 12 (p.G12D), and glycine to aspartate on codon 13 (p.G13D). No mutation was found in the NRAS gene in our patients.ConclusionsBased on this study, the frequency of KRAS mutations seems to be in the spectrum of frequencies of other countries such as China, Japan, India, USA, France, and Germany and NRAS was similar to the West of Iran.