结直肠癌组织基因突变与临床病理及MMR蛋白表达的相关性分析

目的分析结直肠癌组织KRAS、NRAS、BRAF和PIK3CA基因突变与临床病理因素及MMR蛋白表达的相关性。方法采用扩增阻碍突变系统(ARMS)和免疫组化法对122例结直肠癌石蜡组织进行回顾性分析。结果 122例结直肠癌组织中KRAS、NRAS、BRAF和PIK3CA基因突变率分别为48.4%(59/122)、4.1%(5/122)、5.7%(7/122)和5.7%(7/122)。检出KRAS与PIK3CA双突变病例3例,BRAF与PIK3CA双突变1例,未发现BRAF与KRAS或NRAS基因同时突变病例。女性患者KRAS突变率高于男性患者(P0.05),低分化腺癌KRAS突变率高于高、中分化腺癌(P0.001)。女性患者、有淋巴结转移者和MLH1蛋白表达缺失者与男性患者、无淋巴结转移和MLH1表达者比(P0.05),PMS2蛋白表达缺失者比表达者的BRAF突变率更高。黏液腺癌PIK3CA突变率较其他肿瘤组织学类型高(P0.05)。结论该4种基因在结直肠癌的突变率依次为KRAS、 BRAF、PIK3CA、NRAS,不存在4种基因全突变及3种基因突变。BRAF与KRAS、NRAS基因突变存在相互排斥现象。KRAS、BRAF、PIK3CA基因突变与结直肠癌临床病理特征存在相关性。     

结直肠癌患者KRAS、NRAS、BRAF及PIK3CA基因突变与其临床病理特征关系的研究

目的 探讨结直肠癌(colorectal cancer, CRC)患者KRAS、NRAS、BRAF、PIK3CA基因突变情况及其与临床病理特征的关系。方法 收集2012—2016年复旦大学附属上海市第五人民医院手术切除的91例原发性CRC患者肿瘤手术切除标本进行回顾性分析,采用扩增阻碍突变系统(ARMS)进行实时荧光定量PCR检测KRAS、NRAS、BRAF、PIK3CA基因突变情况,应用统计学分析其与临床病理学特征的关系。结果 91例CRC患者中,KRAS/NRAS/BRAF/PIK3CA总突变率为53.8%(49/91),其中KRAS突变率为40.7%(37/91),NRAS突变率为4.4%(4/91),BRAF突变率为3.3%(3/91),PIK3CA突变率为2.2%(2/91),KRAS/PIK3CA双突变率为2.2%(2/91),KRAS/NRAS双突变率为1.1%(1/91)。BRAF基因在低分化癌患者中突变率显著高于中-高分化癌患者(P<0.05)。PIK3CA基因突变与肿瘤原发部位有关(P<0.05)。有淋巴结转移患者的KRNS/NRAS/BRAF/PIK3...     

外源性一氧化氮调控MEK/ERK信号通路促进胃溃疡大鼠黏膜修复的实验观察

目的观察外源性一氧化氮(NO)通过调控丝裂原细胞外信号调节激酶(MEK)/细胞外信号调节激酶(ERK)信号通路促进胃溃疡(GU)大鼠黏膜修复作用。方法取40只大鼠以冰醋酸法建立GU大鼠模型,并将其随机分为模型组、低、中、高剂量组,另取10只大鼠注射生理盐水,设为对照组。术后低、中、高剂量组腹腔注射NO外源性供体硝普钠(SNP) 2 mg/kg、4 mg/kg、6 mg/kg,对照组和模型组腹腔注射等体积生理盐水,2次/d,连续3 d。第4天处死大鼠,进行组织病理学观察,对比溃疡面积、溃疡抑制率,并对比表皮生长因子受体(EGFR)、大鼠肉瘤相关因子(Raf)、MEK、ERK mRNA相对表达量、磷酸化EGFR(pEGFR)/EGFR、磷酸化Raf(pRaf)/Raf、磷酸化MEK(pMEK)/MEK、磷酸化ERK(pERK)/ERK及紧密连接蛋白1(ZO-1) mRNA和蛋白相对表达量。结果组织病理学观察发现,3剂量组炎性细胞浸润程度较模型组减轻,且中剂量组减轻程度最为明显;溃疡面积组间比较,中剂量组最低、低、高剂量组其次、模型组最高,除低、高剂量组比较差异无显著性(P 0. 05)外,每两组间比较差异有显著性(P 0. 05),中剂量组溃疡抑制率显著高于低、高剂量组(P 0. 05),低、高剂量组溃疡抑制率比较无显著性(P 0. 05);溃疡组织EGFR、Raf、MEK、ERK mRNA相对表达量、pEGFR/EGFR、pRaf/Raf、p MEK/MEK、pERK/ERK及ZO-1 mRNA和蛋白相对表达量组间比较,对照组最高、中剂量组其次、低、高剂量组稍高、模型组最低,除低、高剂量组比较无显著性(P 0. 05)外,每两组间比较差异均有显著性(P 0. 05)。结论外源性NO供体SNP可促进GU大鼠黏膜修复,其中4 mg/kg的SNP促进效果最佳,推测与上调EGFR、Raf、MEK、ERK mRNA,ZO-1 mRNA和蛋白相对表达量,pEGFR/EGFR、pRaf/Raf、pMEK/MEK、pERK/ERK,激活MEK/ERK信号通路有关。     

左右半结肠癌分子生物学表达与临床病理特征关系

目的分析左右半结肠癌肿瘤组织中KRAS/NRAS/BRAF基因突变状态及错配修复蛋白(MSH2/MSH6/PMS2/MLH1)表达与临床病理的关系。方法选取解放军总医院2014-07—2019-05行手术切除的原发性结肠癌(CC)肿瘤组织标本837例进行回顾性分析,采用实时荧光定量PCR法检测KRAS/NRAS/BRAF基因的体细胞突变热点,采用免疫组化方法检测错配修复蛋白(MSH2/MSH6/PMS2/MLH1)的表达,采用SPSS 21. 0统计软件及卡方检验分析左右半结肠与它们之间的临床病理特征的关系。结果 837例标本中结肠癌与年龄、家族史、大体分型、组织学类型、分化程度、脉管癌栓和临床分期等无显著性差异;左半结肠中男性415例(66. 1%),女性213例(33. 9%);右半结肠中男性114例(54. 6%),女性95例(45. 5%);左半结肠男性占比显著大于右半结肠,右半结肠女性显著大于左半结肠(χ2=8. 975,P=0. 003);左、右半结肠中5 cm的肿瘤分别为409例(65. 1%)、83(39. 7%),5 cm的肿瘤分别为219例(34. 9%)、126例(60. 3%),具有统计学差异性(χ2=41. 803,P=0. 000);左半结肠神经侵犯明显高于右半结肠(χ2=5. 344,P=0. 027);四种错配修复蛋白(MSH2、MSH6、MLH1、PMS2)的缺失率分别为2. 3%(19/837)、2. 9%(24/837)、6. 1%(51/837)、6. 7%(56/837),其中左半结肠中分别为1. 8%、1. 9%、3. 2%、3. 2%,右半结肠中分别为3. 8%、5. 7%、14. 8%、17. 2%,右半结肠的缺失率高于左半结肠,MSH2蛋白表达中无显著性差异(P0. 05),MSH6、MLH1和PMS2中具有统计学差异性(P0. 05); KRAS/NRAS/BRAF基因总的突变率为53. 0%,分别为45. 4%(380/837)、4. 5%(38/837)、3. 1%(26/837),左、右半结肠KRAS/NRAS基因状态无显著性差异,右半结肠BRAF基因突变率显著高于左半结肠(6. 2%vs 2. 1%,χ2=8. 973,P=0. 005)。结论左右半结肠癌患者中KRAS/NRAS/BRAF基因的突变状态和四种错配修复蛋白的表达,与大部分临床病理指标无关,但是左半结肠癌中男性居多、右半结肠癌女性居多。左半结肠癌更易发生神经侵犯,右半结肠癌患者肿瘤比左半结肠大,MSH6、MLH1和PMS2蛋白以右半结肠癌缺失率高,BRAF突变更多地出现在右半结肠癌。     

结直肠癌组织中KRAS、NRAS、BRAF、PIK3CA基因突变与临床病理特征及MMR蛋白、p53蛋白表达的相关性研究

目的 分析结直肠癌组织中KRAS、NRAS、BRAF、PIK3CA基因突变情况,探讨其与临床病理参数及MMR蛋白、p53蛋白表达的关系.方法 回顾性分析140例结直肠癌组织的临床病理特征,应用扩增阻碍突变系统(ARMS)进行实时荧光定量PCR检测140例结直肠癌组织KRAS、NRAS、BRAF、PIK3CA基因突变情况...     

结直肠癌微卫星不稳定状态与KRAS、NRAS、BRAF基因突变和临床病理特征及预后的关系

目的 探讨结直肠癌(CRC)的微卫星不稳定(MSI)状态与KRAS、NRAS、BRAF基因突变、临床病理特征及预后的相关性。方法 选取2015年3月至2020年12月于汕头市中心医院和中山大学肿瘤防治中心收治的经病理确诊为CRC的861例患者作为研究对象,检测其4种错配修复(MMR)蛋白表达、MSI状态,KRAS、NRAS、NRAS基因突变情况。分析MMR蛋白表达、KRAS、NRAS和BRAF基因突变与CRC患者临床病理特征的相关性,MMR蛋白表达与KRAS、NRAS和BRAF基因突变的相关性,并采用COX回归模型探讨CRC患者2年内死亡的独立影响因素。结果 CRC中的MMR蛋白表达总缺失率为12.08%,KRAS基因突变率为42.28%,NRAS基因突变率为2.21%,BRAF基因突变率为6.50%。不同年龄、肿瘤部位、组织学类型、肿瘤最大径、分化程度、TNM分期、淋巴结转移状态、CEA水平的患者MMR蛋白表达比较,差异有统计学意义(P<0.05)。不同性别、肿瘤部位、组织学类型、分化程度、TNM分期、淋巴结转移状态、CA199水平的患者KRAS基因突变比较,差异有统计学意义(...     

丹参酮ⅡA对脓毒症大鼠肺损伤及p38MAPK/ERK信号通路的影响

目的探讨丹参酮ⅡA对脓毒症大鼠肺损伤及p38MAPK/ERK信号通路的影响。方法将30只SD大鼠随机分为对照组、模型组和丹参酮ⅡA组各10只,模型组和丹参酮ⅡA组采用盲肠结扎穿孔手术法制作大鼠脓毒症模型。丹参酮ⅡA组于术后即刻腹腔注射20 mg/kg的丹参酮ⅡA注射液,连续治疗48 h。治疗后,HE染色观察肺组织的病理变化,测定肺组织湿/干质量(W/D)和内毒素(LPS)水平,采用ELISA法测定肺组织中肿瘤坏死因子α(TNF-α)、白介素(IL)-6、丙二醛(MDA)、超氧化物歧化酶(SOD)和谷胱甘肽(GSH)水平,Western blot检测p38MAPK/ERK信号通路的磷酸化水平。结果与对照组相比,模型组和丹参酮ⅡA组肺组织W/D显著升高(P 0. 05),SOD酶活性和GSH水平显著下降(P 0. 01),LPS、MDA、IL-6和TNF-α水平显著升高(P 0. 01),p-p38和p-ERK1/2蛋白的表达显著上调(P 0. 01);与模型组相比,丹参酮ⅡA组肺组织W/D显著下降(P 0. 05),SOD酶活性和GSH水平显著升高(P 0. 01),LPS、MDA、IL-6和TNF-α水平显著下降(P 0. 01),p-p38和p-ERK1/2蛋白的表达显著下调(P 0. 01); HE染色显示肺组织的病理变化明显减轻。结论丹参酮ⅡA可能通过抑制p38MAPK/ERK信号通路,降低脓毒症大鼠炎症因子和氧化应激水平,保护大鼠肺损伤。     

妊娠期糖尿病脂肪细胞转染网膜素1对葡萄糖摄取率的影响及MEK/ERK通路蛋白的参与研究

目的分析妊娠期糖尿病脂肪细胞转染网膜素1对葡萄糖摄取率的影响及MEK/ERK通路蛋白的参与作用。方法构建网膜素1过表达载体转染传代脂肪细胞,分析不同转染浓度(0μg、1.0μg、2.0μg、4.0μg)脂肪细胞的葡萄糖摄取率。采用荧光定量PCR法、Western Blotting法和免疫细胞化学法分析MEK/ERK通路蛋白的表达变化。结果不同网膜素1转染浓度对脂肪细胞葡萄糖摄取率和MEK/ERK通路蛋白及IRS水平有明显影响,且随着网膜素1转染浓度的升高,葡萄糖摄取率逐渐升高(P0.05),MEK、ERK1/2蛋白(P0.05)、mRNA(P0.05)水平逐步降低,而IRS-1蛋白水平明显升高(P0.05)。结论妊娠期糖尿病脂肪细胞转染网膜素1后细胞的葡萄糖摄取率及IRS明显升高而MEK/ERK通路蛋白表达降低,表明网膜素1过表达和MEK/ERK通路蛋白被抑制与葡萄糖葡萄糖摄取和胰岛素抵抗密切相关。     

结直肠癌患者应用ARMS法检测KRAS、NRAS、PIK3CA、BRAF基因突变分析

目的探讨结直肠癌(CRC)患者应用扩增阻碍突变系统(Amplification Refractory Mutation System,ARMS)法检测KRAS、NRAS、PIK3CA及BRAF基因突变情况并分析其与临床病理特征的关系。方法收集中国医科大学附属盛京医院60例结直肠癌患者手术切除组织,采用ARMS法检测KRAS、NRAS、PIK3CA及BRAF基因突变情况。结果 KRAS基因突变23例,突变率为38.3%;NRAS基因突变1例,突变率为1.7%;PIK3CA基因突变4例,突变率为6.7%;BRAF基因突变3例,突变率为5%。检出双突变2例,分别为PIK3CA与KRAS突变,PIK3CA与BRAF突变。有淋巴结转移患者KRAS基因突变率显著高于无淋巴结转移患者(P=0.031)。KRAS、NRAS、PIK3CA、BRAF基因突变之间无明显相关性。结论在结直肠癌患者中,KRAS基因突变率最高,且多发生于有淋巴结转移患者,NRAS、PIK3CA、BRAF基因突变率较低。对结直肠癌患者进行KRAS、NRAS、PIK3CA、BRAF基因联合检测,为临床个体化靶向治疗提供更准确的理论依据。     

结直肠癌组织中MMR蛋白表达、MSI、RAS和BRAF 基因突变与临床病理特征的关系

目的 探讨结直肠癌患者癌组织中错配修复(MMR)蛋白表达、微卫星不稳定性(MSI)、大鼠肉瘤(RAS)基因和致癌同源体B1(BRAF)基因突变与临床病理特征的关系。方法 选取该院2022年1-12月接受根治手术治疗的352例结直肠癌患者的肿瘤组织和血液标本、42例非肠癌患者的实体瘤组织和血液标本，采用免疫组化法检测MMR蛋白表达，一代测序片段分析法检测MSI,实时荧光定量聚合酶链反应检测KRAS、NRAS和BRAF基因突变状态，分析MMR蛋白表达、MSI和3种基因突变状态与结直肠癌临床病理特征的关系。结果 352例CRC患者肿瘤组织中检出MMR缺陷(dMMR)29例(8.2%),高度微卫星不稳定(MSI-H)26例(7.4%),KRAS基因突变161例(45.7%),NRAS基因突变13例(3.7%),BRAF基因突变11例(3.1%)。与dMMR有关因素为低龄、黏液腺癌、原发于右半结肠癌(P<0.05);与MSI-H相关因素包括低龄、肿瘤家族史、原发于右半结肠癌(P<0.05);KRAS和NRAS基因高突变率分别与黏液腺癌和淋巴结转移有关(P<0.05);BRAF基...     

Combinations of BRAF, MEK, and PI3K/mTOR inhibitors overcome acquired resistance to the BRAF inhibitor GSK2118436 dabrafenib, mediated by NRAS or MEK mutations

Recent results from clinical trials with the BRAF inhibitors GSK2118436 (dabrafenib) and PLX4032 (vemurafenib) have shown encouraging response rates; however, the duration of response has been limited. To identify determinants of acquired resistance to GSK2118436 and strategies to overcome the resistance, we isolated GSK2118436 drug-resistant clones from the A375 BRAF(V600E) and the YUSIT1 BRAF(V600K) melanoma cell lines. These clones also showed reduced sensitivity to the allosteric mitogen-activated protein/extracellular signal-regulated kinase (MEK) inhibitor GSK1120212 (trametinib). Genetic characterization of these clones identified an in-frame deletion in MEK1 (MEK1(K59del)) or NRAS mutation (NRAS(Q61K) and/or NRAS(A146T)) with and without MEK1(P387S) in the BRAF(V600E) background and NRAS(Q61K) in the BRAF(V600K) background. Stable knockdown of NRAS with short hairpin RNA partially restored GSK2118436 sensitivity in mutant NRAS clones, whereas expression of NRAS(Q61K) or NRAS(A146T) in the A375 parental cells decreased sensitivity to GSK2118436. Similarly, expression of MEK1(K59del), but not MEK1(P387S), decreased sensitivity of A375 cells to GSK2118436. The combination of GSK2118436 and GSK1120212 effectively inhibited cell growth, decreased ERK phosphorylation, decreased cyclin D1 protein, and increased p27(kip1) protein in the resistant clones. Moreover, the combination of GSK2118436 or GSK1120212 with the phosphoinositide 3-kinase/mTOR inhibitor GSK2126458 enhanced cell growth inhibition and decreased S6 ribosomal protein phosphorylation in these clones. Our results show that NRAS and/or MEK mutations contribute to BRAF inhibitor resistance in vitro, and the combination of GSK2118436 and GSK1120212 overcomes this resistance. In addition, these resistant clones respond to the combination of GSK2126458 with GSK2118436 or GSK1120212. Clinical trials are ongoing or planned to test these combinations.     

结直肠癌患者血清外泌体与组织中KRAS，BRAF，NRAS 和PIK3CA 基因突变检测及临床意义的比较

目的 检测结直肠癌(colorectal cancer, CRC) 患者血清外泌体KRAS,BRAF,NRAS 和PIK3CA 相关基因位点的突变,分析其与癌组织基因突变的一致性及其可能的影响因素。方法 2019 年2 月～ 2021 年1 月中国人民解放军联勤保障部队第九二〇医院100 例结直肠癌患者作为研究对象。提取患者血清外泌体,并用蛋白免疫印迹（Westernblot,WB）法检测外泌体标志物CD63 和TSG101 的蛋白表达;聚合酶链式反应（polymerase chain reaction,PCR）检测血清外泌体及手术切除的癌组织中KRAS,BRAF,NRAS 和PIK3CA 基因突变情况,Kappa 一致性检验分析血清外泌体突变与组织突变的一致性,Logistic 单因素回归分析影响一致性的因素。结果 癌症基因组图谱（the cancer genomeatlas,TCGA）数据显示,KRAS,BRAF,NRAS 和PIK3CA 的结直肠癌突变率分别为35% ～ 96%,5% ～ 15%,5% ～ 30%和18% ～ 36%,且KRAS 和BRAF 的突变与结直肠癌患者的低存活率有关。血清外泌体中KRAS,BRAF,NRAS 和PIK3CA 的突变率分别为94.00%,11.00%,17.00% 和35.00%;结直肠癌组织KRAS,BRAF,NRAS 和PIK3CA 的突变率分别为34.00%,5.00%,6.00% 和16.00%;血清外泌体中KRAS,BRAF,NRAS 和PIK3CA 的突变率均高于组织,差异有统计学意义（χ2=101.027 ～ 256.250,均P ＜ 0.05）。血清外泌体与组织中KRAS 突变的一致率为40.00%（Kappa值=0.064,P>0.05）,BRAF 突变的一致率为99.00%（Kappa 值=0.599,P<0.05）,NRAS 突变的一致率为89.00%（Kappa 值=0.475,P<0.05）,KRAS 突变的一致率为81.00%（Kappa 值=0.523,P<0.05）。ECOG 评分、转移、临床分期是影响外泌体和组织KRAS,BRAF,NRAS 和PIK3CA 的突变检测一致性的因素。结论 结直肠癌患者血清外泌体KRAS,BRAF,NRAS 和PIK3CA 的突变率高于组织,二者BRAF,NRAS 和PIK3CA 的一致性中等,为外泌体的基因检测指导临床靶向治疗提供参考。     

ERK inhibition overcomes acquired resistance to MEK inhibitors

The RAS/RAF/MEK pathway is activated in more than 30% of human cancers, most commonly via mutation in the K-ras oncogene and also via mutations in BRAF. Several allosteric mitogen-activated protein/extracellular signal-regulated kinase (MEK) inhibitors, aimed at treating tumors with RAS/RAF pathway alterations, are in clinical development. However, acquired resistance to these inhibitors has been documented both in preclinical and clinical samples. To identify strategies to overcome this resistance, we have derived three independent MEK inhibitor-resistant cell lines. Resistance to allosteric MEK inhibitors in these cell lines was consistently linked to acquired mutations in the allosteric binding pocket of MEK. In one cell line, concurrent amplification of mutant K-ras was observed in conjunction with MEK allosteric pocket mutations. Clonal analysis showed that both resistance mechanisms occur in the same cell and contribute to enhanced resistance. Importantly, in all cases the MEK-resistant cell lines retained their addiction to the mitogen-activated protein kinase (MAPK) pathway, as evidenced by their sensitivity to a selective inhibitor of the ERK1/2 kinases. These data suggest that tumors with acquired MEK inhibitor resistance remain dependent on the MAPK pathway and are therefore sensitive to inhibitors that act downstream of the mutated MEK target. Importantly, we show that dual inhibition of MEK and ERK by small molecule inhibitors was synergistic and acted to both inhibit the emergence of resistance, as well as to overcome acquired resistance to MEK inhibitors. Therefore, our data provide a rationale for cotargeting multiple nodes within the MAPK signaling cascade in K-ras mutant tumors to maximize therapeutic benefit for patients.     

Knockdown of oncogenic KRAS in non-small cell lung cancers suppresses tumor growth and sensitizes tumor cells to targeted therapy

Oncogenic KRAS is found in more than 25% of lung adenocarcinomas, the major histologic subtype of non-small cell lung cancer (NSCLC), and is an important target for drug development. To this end, we generated four NSCLC lines with stable knockdown selective for oncogenic KRAS. As expected, stable knockdown of oncogenic KRAS led to inhibition of in vitro and in vivo tumor growth in the KRAS-mutant NSCLC cells, but not in NSCLC cells that have wild-type KRAS (but mutant NRAS). Surprisingly, we did not see large-scale induction of cell death and the growth inhibitory effect was not complete. To further understand the ability of NSCLCs to grow despite selective removal of mutant KRAS expression, we conducted microarray expression profiling of NSCLC cell lines with or without mutant KRAS knockdown and isogenic human bronchial epithelial cell lines with and without oncogenic KRAS. We found that although the mitogen-activated protein kinase pathway is significantly downregulated after mutant KRAS knockdown, these NSCLCs showed increased levels of phospho-STAT3 and phospho-epidermal growth factor receptor, and variable changes in phospho-Akt. In addition, mutant KRAS knockdown sensitized the NSCLCs to p38 and EGFR inhibitors. Our findings suggest that targeting oncogenic KRAS by itself will not be sufficient treatment, but may offer possibilities of combining anti-KRAS strategies with other targeted drugs.     

BRAFV600E: implications for carcinogenesis and molecular therapy

The mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway is frequently mutated in human cancer. This pathway consists of a small GTP protein of the RAS family that is activated in response to extracellular signaling to recruit a member of the RAF kinase family to the cell membrane. Active RAF signals through MAP/ERK kinase to activate ERK and its downstream effectors to regulate a wide range of biological activities including cell differentiation, proliferation, senescence, and survival. Mutations in the v-raf murine sarcoma viral oncogenes homolog B1 (BRAF) isoform of the RAF kinase or KRAS isoform of the RAS protein are found as activating mutations in approximately 30% of all human cancers. The BRAF pathway has become a target of interest for molecular therapy, with promising results emerging from clinical trials. Here, the role of the most common BRAF mutation BRAF(V600E) in human carcinogenesis is investigated through a review of the literature, with specific focus on its role in melanoma, colorectal, and thyroid cancers and its potential as a therapeutic target.     

Targeting BRAFV600E in thyroid carcinoma: therapeutic implications

B-Raf is an important mediator of cell proliferation and survival signals transduced via the Ras-Raf-MEK-ERK cascade. BRAF mutations have been detected in several tumors, including papillary thyroid carcinoma, but the precise role of B-Raf as a therapeutic target for thyroid carcinoma is still under investigation. We analyzed a panel of 93 specimens and 14 thyroid carcinoma cell lines for the presence of BRAF mutations and activation of the mitogen-activated protein/ERK kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway. We also compared the effect of a B-Raf small inhibitory RNA construct and the B-Raf kinase inhibitor AAL881 on both B-Raf wild-type and mutant thyroid carcinoma cell lines. We found a high prevalence of the T1799A (V600E) mutation in papillary and anaplastic carcinoma specimens and cell lines. There was no difference in patient age, B-Raf expression, Ki67 immunostaining, or clinical stage at presentation between wild-type and BRAF(V600E) specimens. Immunodetection of phosphorylated and total forms of MEK and ERK revealed no difference in their phosphorylation between wild-type and BRAF(V600E) patient specimens or cell lines. Furthermore, a small inhibitory RNA construct targeting the expression of both wild-type B-Raf and B-Raf(V600E) induced a comparable reduction of viability in both wild-type and BRAF(V600E) mutant cancer cells. Interestingly, AAL881 inhibited MEK and ERK phosphorylation and induced apoptosis preferentially in BRAF(V600E)-harboring cells than wild-type ones, possibly because of better inhibitory activity against B-Raf(V600E). We conclude that B-Raf is important for the pathophysiology of thyroid carcinomas irrespective of mutational status. Small molecule inhibitors that selectively target B-Raf(V600E) may provide clinical benefit for patients with thyroid cancer.     

Coexistence of PIK3CA and other oncogene mutations in lung adenocarcinoma-rationale for comprehensive mutation profiling

Phosphoinositide-3-kinase catalytic alpha polypeptide (PIK3CA) encodes the p110α subunit of the mitogenic signaling protein phosphoinositide 3-kinase (PI3K). PIK3CA mutations in the helical binding domain and the catalytic subunit of the protein have been associated with tumorigenesis and treatment resistance in various malignancies. Characteristics of patients with PIK3CA-mutant lung adenocarcinomas have not been reported. We examined epidermal growth factor receptor (EGFR), Kirsten rate sarcoma viral oncogene homolog (KRAS), v-Raf murine sarcoma viral oncogene homolog B1 (BRAF), human epidermal growth factor receptor 2 (HER2), PIK3CA, v-akt murine thymoma vial oncogene homolog 1 (AKT1), v-ras neuroblastoma viral oncogene homolog (NRAS), dual specificity mitogen-activated protein kinase kinase 1 (MEK1), and anaplastic lymphoma kinase (ALK) in patients with adenocarcinoma of the lung to identify driver mutations. Clinical data were obtained from the medical records of individuals with mutations in PIK3CA. Twenty-three of 1,125 (2%, 95% CI: 1-3) patients had a mutation in PIK3CA, 12 in exon 9 (10 E545K and 2 E542K), and 11 in exon 20 (3 H1047L and 8 H1047R). The patients (57% women) had a median age of 66 at diagnosis (range: 34-78). Eight patients (35%) were never smokers. Sixteen of 23 (70%, 95% CI: 49-86) had coexisting mutations in other oncogenes-10 KRAS, 1 MEK1, 1 BRAF, 1 ALK rearrangement, and 3 EGFR exon 19 deletions. We conclude that PIK3CA mutations occur in lung adenocarcinomas, usually concurrently with EGFR, KRAS, and ALK. The impact of PIK3CA mutations on the efficacy of targeted therapies such as erlotinib and crizotinib is unknown. Given the high frequency of overlapping mutations, comprehensive genotyping should be carried out on tumor specimens from patients enrolling in clinical trials of PI3K and other targeted therapies.     

Molecular profiling of patients with colorectal cancer and matched targeted therapy in phase I clinical trials

Clinical experience increasingly suggests that molecular prescreening and biomarker enrichment strategies in phase I trials with targeted therapies will improve the outcomes of patients with cancer. In keeping with the exigencies of a personalized oncology program, tumors from patients with advanced chemorefractory colorectal cancer were analyzed for specific aberrations (KRAS/BRAF/PIK3CA mutations, PTEN and pMET expression). Patients were subsequently offered phase I trials with matched targeted agents (MTA) directed at the identified anomalies. During 2010 and 2011, tumor molecular analysis was conducted in 254 patients: KRAS mutations (80 of 254, 31.5%), BRAF mutations (24 of 196, 12.2%), PIK3CA mutations (15 of 114, 13.2%), KRAS and PIK3CA mutations (9 of 114, 7.9%), low PTEN expression (97 of 183, 53.0%), and high pMET expression (38 of 64, 59.4%). In total, 68 patients received 82 different MTAs: phosphoinositide 3-kinase (PI3K) pathway inhibitor (if PIK3CA mutation, n = 10; or low PTEN, n = 32), PI3K pathway inhibitor plus MEK inhibitor (if KRAS mutation, n = 10; or BRAF mutation, n = 1), second-generation anti-EGF receptor monoclonal antibodies (if wild-type KRAS, n = 11), anti-hepatocyte growth factor monoclonal antibody (if high pMET, n = 10), mTOR inhibitor plus anti-insulin-like growth factor-1 receptor monoclonal antibody (if low PTEN, n = 5), and BRAF inhibitor (if BRAF mutation, n = 3). Median time-to-treatment failure on MTA was 7.9 versus 16.3 weeks for their prior systemic antitumor therapy (P < 0.001). Partial response was seen in 1 patient [1.2%, PI3K inhibitor with PIK3CA mutation] and stable disease >16 weeks in 10 cases (12.2%). These results suggest that matching chemorefractory patients with colorectal cancer with targeted agents in phase I trials based on the current molecular profile does not confer a significant clinical benefit. Mol Cancer Ther; 11(9); 2062-71. ?2012 AACR.     

Receptor tyrosine kinases exert dominant control over PI3K signaling in human KRAS mutant colorectal cancers

Therapies inhibiting receptor tyrosine kinases (RTKs) are effective against some human cancers when they lead to simultaneous downregulation of PI3K/AKT and MEK/ERK signaling. However, mutant KRAS has the capacity to directly activate ERK and PI3K signaling, and this is thought to underlie the resistance of KRAS mutant cancers to RTK inhibitors. Here, we have elucidated the molecular regulation of both the PI3K/AKT and MEK/ERK signaling pathways in KRAS mutant colorectal cancer cells and identified combination therapies that lead to robust cancer cell apoptosis. KRAS knockdown using shRNA suppressed ERK signaling in all of the human KRAS mutant colorectal cancer cell lines examined. However, no decrease, and actually a modest increase, in AKT phosphorylation was often seen. By performing PI3K immunoprecipitations, we determined that RTKs, often IGF-IR, regulated PI3K signaling in the KRAS mutant cell lines. This conclusion was also supported by the observation that specific RTK inhibition led to marked suppression of PI3K signaling and biochemical assessment of patient specimens. Interestingly, combination of RTK and MEK inhibitors led to concomitant inhibition of PI3K and MEK signaling, marked growth suppression, and robust apoptosis of human KRAS mutant colorectal cancer cell lines in vitro and upon xenografting in mice. These findings provide a framework for utilizing RTK inhibitors in the treatment of KRAS mutant colorectal cancers.