Detection of epidermal growth factor receptor (EGFR) exon 19 E746-A750 deletion and EGFR exon 21 point mutations in lung adenocarcinoma by immunohistochemistry: a comparative study to EGFR exons 19 and 21 mutations analysis using PCR followed by high-resolution melting and pyrosequencing

Activating mutations in the epidermal growth factor receptor (EGFR) gene in non-small cell lung cancer (NSCLC) with adenocarcinoma histology confers susceptibility to treatment with EGFR tyrosine kinase inhibitors (TKI). Analysis of these activating mutations is typically performed by molecular techniques including polymerase chain reaction (PCR) amplification followed by deoxyribonucleic acid (DNA) melting curve analysis and/or direct sequencing. Recently developed mutation-specific immunohistochemical stains for the L858R point mutation in exon 21 and an E746-A750 deletion in exon 19 of the EGFR gene may offer a fast, cost-effective alternative to molecular testing. In this study, EGFR exons 19 and 21 mutations were analyzed using EGFR E746-A750 del and EGFR L585R point mutation-specific antibodies and the results were compared with the exon 19 deletions and exon 21 L588R point mutation as detected by molecular testing. The findings demonstrate a high concordance rate (100% in 12 cases) between the two methodologies for EGFR exon 21 L585R point mutation but a low concordance rate (54% in 22 cases) for exon 19 deletions when using EGFR E746-A750 mutation-specific antibody compared to molecular testing. This low concordance rate between the two methods is due to the fact that EGFR exon 19 mutations include deletions other than E746-A750 as well as insertion/deletions that will not be covered by exon 19 E746-A750 del mutation-specific antibody. Despite this limitation, the current EGFR mutation-specific antibodies can prove useful as an alternative to molecular tests for exon 21 L585R mutations as well as a subset of EGFR exon 19 deletion mutations, particularly in cases with low percentage of tumor concentration and in decalcified tissue specimens that are not suitable for DNA-based molecular assays.     

两种突变特异性抗体用于肺腺癌EGFR基因突变的评价

目的：验证EGFR 19delE746-A750和21L858R突变抗体的灵敏度和特异性以及免疫组织化学与RT-PCR方法的一致性,并探讨免疫组化在肺腺癌EGFR基因突变状态评价中的应用。方法：采用免疫组织化学方法对139例经过RT-PCR验证EGFR基因突变状态的病例进行检测。并采用SPSS19.0软件对两种方法的检测结果进行一致性分析。结果：与RT-PCR结果相比,EGFR delE746-A750和L858R突变抗体的总体敏感性为78.5%,特异性为93%。分别分析EGFR delE746-A750和L858R特异抗体,前者的敏感性和特异性分别是64.3%和97.8%,后者为90.3%和95.2%。采用SPSS19.0软件进行Kappa检验显示免疫组化和RT-PCR的结果高度一致。结论：EGFR delE746-A750和L858R突变抗体具有良好的灵敏度和特异性,结合全自动免疫组化仪进行EGFR基因突变检测是一种经济便捷可靠的方法。     

A simple and sensitive method for detecting major mutations within the tyrosine kinase domain of the epidermal growth factor receptor gene in non-small-cell lung carcinoma.

The detection of mutations in the epidermal growth factor receptor (EGFR) gene impacts therapeutic decision-making for non-small-cell lung carcinoma (NSCLC). Although direct sequencing has been most frequently used to detect EGFR mutations, this method displays several disadvantages. We set up simple mutation-specific polymerase chain reaction (PCR) for common delE746-A750 and L858R mutations of EGFR using primers specific to these mutations. Both mutation-specific PCR and direct sequencing methods were used to investigate 62 samples of NSCLC, and the results were compared. To evaluate the sensitivity of mutation-specific PCR, DNA mixtures containing various proportions of mutant alleles were analyzed. Mutation-specific PCR revealed delE746-A750 in 8 samples and L858R in 14 samples. All samples with either delE746-A750 or L858R mutation revealed by direct sequencing also displayed positive results for mutation-specific PCR. Conversely, mutations in 3 samples revealed by L858R-specific PCR were barely detectable by direct sequencing. In DNA mixture analysis, DNA mixtures containing 2.5% of delE746-A750 allele or 0.25% of L858R allele yielded positive results with mutation-specific PCR. Our mutation-specific PCR showed satisfactory sensitivity and reliability for detecting major EGFR mutations in clinical NSCLC samples. Given the practical availability, this method could be widely applicable to the treatment of lung cancers.     

Detecting EGFR alterations in clinical specimens—pitfalls and necessities

We investigated the epidermal growth factor receptor (EGFR) status in early stage lung cancer in Southern Sweden, a population for which there are no previous reports on the EGFR mutation frequency. Three hundred fifty small cell lung cancers, adenocarcinomas (AC), squamous cell carcinomas (SqCC), and large cell carcinomas were analyzed using a combination of techniques for the analysis of protein expression, gene copy numbers, and mutations. Immunohistochemical (IHC) staining with antibodies for the EGFR mutations L858R and del E746-A750 revealed intratumoral heterogeneity and several discrepant cases when compared to mutation-specific polymerase chain reaction (PCR)-based analysis. The frequencies of these two mutations, when considering IHC staining with mutation-specific antibodies in a cohort of 298 cases and subsequent confirmation by PCR, were 10 % in AC and <2 % in SqCC. Furthermore, screening by sequencing of EGFR in a cohort of 52 lung AC and squamous carcinomas demonstrated a more diverse mutation spectrum, not covered by the mutation-specific antibodies. High expression of total EGFR protein was correlated to high gene copy numbers but did not reflect the mutational status of the tumors. We believe that the mutation spectra in a Southern Swedish population is too diverse to be covered by the mutation-specific antibodies, and we also raise some other issues regarding the use of the mutation-specific antibodies, for example concerning heterogeneous expression of the mutated protein, optimal antibody dilution, and discrepancies between staining results and PCR.     

非小细胞肺癌表皮生长因子受体基因突变与临床病理特征的关系

目的探讨非小细胞肺癌(NSCLC)表皮生长因子受体(EGFR)基因突变的临床病理学意义。方法应用即时荧光定量聚合酶链反应(PCR)法检测1444例NSCLC患者肺癌组织中EGFR基因第19号和21号外显子突变状况,分析EGFR基因突变与年龄、性别、吸烟状况、组织学分级及临床分期之间的关系。结果1410例成功分型的NSCLC肿瘤组织中401例存在EGFR突变,突变检出率为27.8％,其中193例第19号外显子发生缺失突变,208例第21号外显子发生替代突变。EGFR突变更常见于腺癌、不吸烟或女性患者[突变率分别为33.5％ (367/1094)]、37.6％( 321/853)及43.2％ (225/521)。细支气管肺泡癌及伴细支气管肺泡癌分化特征的腺癌突变率显著高于普通腺癌[突变率分别为61.3％( 19/31)、48.0％( 12/25)及32.4％ (336/1038)]。随着吸烟暴露水平的增加,EGFR突变率呈下降趋势;女性、不吸烟、腺癌为EGFR基因突变状况的独立影响因素。结论NSCLC患者女性、不吸烟、腺癌患者突变率较高。即时荧光定量PCR技术可快速、敏感、准确地检测EGFR基因突变。     

应用蝎形探针扩增阻滞突变系统检测非小细胞肺癌表皮生长因子受体基因突变与病理改变的关系

目的 探讨非小细胞肺癌(NSCLC)肿瘤组织中表皮生长因子受体(EGFR)基因突变的检出率,比较蝎形探针扩增阻滞突变系统(scorpions amplifieation refractory mutation system,以下简称Scorpions ARMS)即时荧光PCR和直接测序检测EGFR基因突变的敏感性.方法 应用显微切割术、Scorpions ARMS及直接测序检测82例NSCLC石蜡包埋肿瘤组织以及癌旁正常肺组织中EGFR基因的第18、19、20和2l外显子的突变.结果 Scorpions ARMS检测82例NSCLC中42例的瘤组织中存在EGFR突变,突变检出率为51.2%,其中20例为EGFR第19外显子框架内多核苷酸的缺失,18例为EGFR第21外显子L858R点突变,1例为EGFR第21外显子L861Q点突变,2例为EGFR第20外显子插入突变,另外1例为EGFR第20外显子$7681点突变.而PCR反应后行直接测序,82例标本中仅58例得到可分析的测序结果,其中25例瘤组织中出现EGFR突变,因此82例的突变检出率为30.5%,25例中13例为EGFR第19外显子框架内多核苷酸的缺失,10例为EGFR第21外显子L858R点突变,1例为EGFR第21外显子L861Q点突变,另外1例为EGFR第20外显子$768I点突变.直接测序检测出25例突变模式与Scorpions ARMS检测结果一致.结果 显示Scorpions ARMS具有很高的敏感度,部分直接测序阴性的病例经Scorpions ARMS检测出EGFR突变.结论 EGFR基因的点突变或缺失在中国NSCLC的患者中的检出率明显高于其他国家,以女性、腺癌和细支气管肺泡以及不吸烟患者突变率较高.Scorpions ARMS技术能快速、敏感、准确检测EGFR突变,能为临床冶疗及预后提供重要信息.     

EGFR-Mutationsanalyse beim nichtkleinzelligen Lungenkarzinom

Background

Some patients with non-small cell lung cancer (NSCLC) respond well to therapy with tyrosine kinase inhibitors (TKI). Somatic mutation of the epidermal growth factor receptor (EGFR) gene is an important predictive marker for TKI response.

Patients and methods

We performed EGFR mutation analysis in 307 NSCLC (exon 18-21). The data were analyzed for associations with clinical-pathological parameters.

Results

Relevant EGFR mutations were found in 25/307 NSCLC (8.1%; 178 biopsies and 129 cytologies). Most mutations were found in exon 19 (50%) followed by the L858R point mutation in exon 21 (12.5%). EGFR mutations were significantly more common in women than in men (16.8% vs. 2.7%; p<0.001) and in adenocarcinoma than in other carcinoma subtypes (11.4% vs. 3.8%; p=0.017). EGFR mutation was associated with TTF-1 positivity (p<0.041). Almost all (96%) mutated NSCLC were TTF-1 positive.

Conclusion

In Central Europe, the prevalence of relevant EGFR mutations in NSCLC is <10% of patients with NSCLC. EGFR mutations are more common in women and TTF-1 positive adenocarcinomas. Mutation analysis can be performed both from biopsies and cytologies.     

Clinical and molecular predictors of response to EGFR tyrosine kinase inhibitors in non-small cell lung cancer

Up to 10% of patients with non-small cell lung carcinoma (NSCLC) achieve an objective response to EGFR tyrosine kinase inhibitors (EGFR-TKI) such as erlotinib or gefitinib. This rate of response is related to non-smoker status, female gender, adenocarcinoma subtype, and Asian ethnicity. Molecular analysis showed that EGFR tyrosine kinase domain somatic mutations appear to be a strong predictor of response to EGFR-TKI. The L858R point mutation and the E746-A750 deletion represent 90% of the mutations encountered in responding patients. The amplification of EGFR gene also seems to be predictive of the response to EGFR-TKI, whereas T790M point mutation induces secondary resistance to EGFR-TKI. Nevertheless, objective responses or strong long-term stabilizations are observed in patients without any EGFR abnormality. Thus, the assessment of the EGFR status in patients with NSCLC remains controversial for clinical practice. The assessment of EGFR abnormalities should be targeted to identify reliable biomarkers of the NSCLC response to EGFR-TKI. This review presents the current knowledge on predictive biomarkers of NSCLC response to EGFR-TKI and the methods available for the assessment of EGFR status.     

肺鳞状细胞癌EGFR/ALK的基因状态

目的:探讨肺鳞状细胞癌各亚型中EGFR和ALK的基因状态.方法:应用ARMS方法检测肺鳞状细胞癌石蜡组织中EGFR基因突变和ALK融合基因情况.结果:218例肺鳞状细胞癌样本中,E GFR基因突变率为4.59％(10/218),19del和L858R各为2.29％(5/218).ALK融合基因阳性率为6.14％(7/114).结论:肺鳞状细胞癌存在一定比例EGFR基因突变和ALK融合基因阳性,肺鳞状细胞癌EGFR基因和ALK融合基因常规检测不可忽视.     

Analysis of multigene detection in patients with advanced lung adenocarcinoma using cytological specimens

ObjectiveTo investigate the mutation status and clinical characteristics of multigene detection in advanced lung adenocarcinoma using cytological specimens.Materials and Methods137 advanced lung adenocarcinoma patients with 10 driver genes detection in the Fourth Hospital Hebei Medical University from January 2019 to November 2019 was analysized. 137 cytological specimens including fine-needle aspiration specimens and maligant serous cavity effusion (pleural effusion, peritoneal and pericardial effusion). Ten driver mutations of EGFR, ALK, ROS1, BRAF, KRAS, NRAS, HER2, RET, PIK3CA and MET were detected by the amplification refractory mutation system (ARMS). Meanwhile, 90 of 137 patients were detected with biopsies for parallel gene detection.Results78.10 % (107/137) of patients with advanced lung adenocarcinoma harbored at least one of 10 driver mutations. The three main mutations were EGFR (69.16 %, 74/137), ALK (6.57 %, 9/137)and ROS1 (3.65 %, 5/137) mutations. Besides, we found 6 cases including two concomitant mutations: EGFR Exon19 del/HER2 (1/137), EGFR Exon21 L858R/PIK3CA (2/137), EGFR Exon21 L858R/RET (1/137), and ALK/KRAS (2/137). Among 137 patients, women aged 64 or older were more likely to have the mutations (P < 0.05). Female patients (P = 0.003) older or equal to 64 years (P = 0.015) with non-smoking habbit (P = 0.027) were more detected with EGFR mutations, while ALK was more detectable in patients yonger than 64 years. Parallel analysis showed that rates of single EGFR, ALK, ROS1, RET, KRAS, NRAS, HER2, MET mutations and concomitant different mutations were not significantly different between cytological specimens and matched histological specimens.ConclusionsIn the study, cytological specimens and biopsy samples have a very high coincidence rate of gene detection. EGFR, ALK and ROS1 mutations were the main driver mutations in patients with advanced lung adenocarcinoma.We speculate that EGFR and ALK are more prone to concomitant mutations respectively and the treatment of advanced lung adenocarcinoma patients with concomitant mutations deserves further study. The rate of KRAS, NRAS, BRAF, PIK3CA, RET and MET exon14 skipping mutation were low but may had a significant impact on the targeted therapy of patients with advanced lung adenocarcinoma.     

Expression of Ki-67, p53, bcl-2, estrogen receptors alpha in patients with clear cell renal carcinoma and epidermal growth factor receptor mutation

Three hundred and thirty-six cases of clear-cell renal carcinoma (CCRC) were examined for epidermal growth factor receptor (EGFR) mutation: exon 19 deletion and L858R mutation in exon 21 of the EGFR gene. The expression of Ki-67, bcl-2, p53, and estrogen receptors alpha was studied in CCRC with EGFR mutation. There were 4 cases of CCRC with EGFR exon 19 deletion. The frequency of EGFR gene mutations was 1.2%. L858R missense mutations in exon 21 of the EGFR gene were absent. In CCRC, EGFR gene mutation (exon 19 deletion) was detected in 3 men and 1 woman with an age range of 50 to 60 years and Fuhrman differentiation grade 2 or 3. The Ki-67 index varied from 4 to 23%. The expression of bcl-2 and p53 was negative. A moderate estrogen receptor alpha expression was revealed in 1 of 4 cases.     

Detection of EGFR mutations in archived cytologic specimens of non-small cell lung cancer using high-resolution melting analysis

Mutations of the epidermal growth factor receptor (EGFR), particularly deletional mutations (DEL) in exon 19 and L858R in exon 21, are reportedly correlated with clinical outcome in patients with non-small cell lung cancer (NSCLC) receiving the EGFR tyrosine kinase inhibitors gefitinib and erlotinib, suggesting that detection of EGFR mutations would have an important role in clinical decision making. We established and validated an easy, inexpensive, and rapid method for detecting DEL and L858R from cytologic material by high-resolution melting analysis (HRMA). Dilution for sensitivity studies revealed that DEL and L858R were detectable in the presence of at least 10% and 0.1% EGFR-mutant cells, respectively. We analyzed 37 archived cytological slides of specimens from 29 patients with advanced NSCLC and compared the results with direct sequencing data obtained previously. Of 37 samples, 34 (92%) yielded consistent results with direct sequencing, 2 were false negative, and 1 was indeterminate. The sensitivity of this analysis was 90% (19/21) and specificity, 100% (15/15). These results suggest that HRMA of archived cytologic specimens of advanced NSCLC is useful for detecting EGFR mutations in clinical practice.     

276例手术切除肺腺癌亚型与EGFR/ALK基因状态

目的:探讨手术切除肺腺癌各亚型EGFR和ALK基因状态分布.方法:应用ARMS方法检测手术切除肺腺癌石蜡组织中EGFR基因突变和ALK融合基因情况.结果:276例肺腺癌手术样本中,EGFR基因突变率为54.71％(151/276),其中19del为28.99％(80/276),L858R为23.19％(64/276),20-ins为0.72％(2/276),L861Q为0.72％(2/276),G719X为1.09％(3/276),S768I为0.36％(1/276)和T790M为0.72％(2/276),其中包含G719X+S768I,19del+T790M,L858R+T790M各1例,ALK基因融合阳性率为5.80％(12/207),在肺腺癌各亚型中EGFR基因突变附壁状腺癌,腺泡状腺癌,乳头状腺癌,实体状腺癌和浸润性黏液腺癌之间差异有统计学意义(P＜0.001,P=0.009,P=0.023,P＜0.001和P=0.030),与其他类型之间差异均无统计学意义(P＞0.05);在肺腺癌各亚型中ALK融合基因突变各亚型之间差异均无统计学意义(P＞0.05).结论:肺腺癌组织学亚型与EGFR基因突变有关,附壁状腺癌、腺泡状腺癌和乳头状腺癌出现EGFR基因突变比其他亚型更加明显.     

肺腺癌EGFR基因19、21号外显子突变分析

目的 探讨肺腺癌表皮生长因子受体(EGFR)基因19、21号外显子突变特点及其临床意义.方法 对肺腺癌手术组织提取DNA,采用聚合酶链式反应(PCR)和直接测序法检测EGFR基因19号与21号外显子突变状态,分析与临床病理参数之间的相关性.结果 在54例被测肺腺癌肿瘤中,发现29例患者存在EGFR基因突变,占53.7％ (29/54).其中,19号外显子突变13例(24.1％),均为缺失突变;21号外显子突变病例为16例(29.6％),均为L858R点突变.高、中分化肿瘤的EGFR突变率均达60％以上,明显高于低分化肿瘤突变率44％.结论 肺腺癌存在较高频率的EGFR基因突变,在高、中分化肿瘤的突变率有高于低分化肿瘤的趋势.     

非小细胞肺癌290例表皮生长因子受体基因突变和拷贝数的检测分析

目的 检测非小细胞肺癌(NSCLC)组织中表皮生长因子受体(EGFR)基因突变和拷贝数,明确中国NSCLC人群中EGFR基因状态.方法 应用显微切割技术和蝎形探针扩增阻滞突变系统(Scorpions ARMS)联合检测290例石蜡包埋、甲醛固定的NSCLC组织中其EGFR基因突变状态,并应用荧光原位杂交(FISH)技术检测其中209例EGFR基因拷贝数的情况,分析EGFR基因突变和EGFR摹因拷贝数二者之间的关系,探讨EGFR基因状态与肺癌临床病理特点的相关性.结果 NSCLC组织EGFR突变率为41.7%(121/290),其中腺癌为48.4%,大细胞癌为16.7%,鳞癌为0.EGFR基因突变以第19、21外显子突变为主(92/121),其中6例存在两种类型的突变.EGFR基因FISH阳性率为51.2%(107/209),包括29例扩增,78例高多体性.其中腺癌FISH阳性率为52.1%,大细胞癌为75.0%,鳞癌为11.1%.检测结果显示NSCLC组织EGFR基因突变与EGFR基因高拷贝数主要存在于腺癌,EGFR基因突变与EGFR基因拷贝数之间有显著的相关性.结论 中国人NSCLC组织具有较高的EGFR基因突变率和FISH阳性率;联合检测EGFR基因拷贝数和基因突变可能更有利于靶向药物的筛选.     

Epidermal growth factor receptor gene mutations in atypical adenomatous hyperplasias of the lung.

Activating epidermal growth factor receptor (EGFR) gene mutations are frequently detected in lung adenocarcinomas, especially adenocarcinomas with a nonmucinous bronchioloalveolar carcinoma component. EGFR-mutated lung adenocarcinomas respond well to EGFR tyrosine kinase inhibitors. We previously found that most (88%) pure nonmucinous bronchioloalveolar carcinomas (adenocarcinoma in situ) already harbor EGFR mutations, indicating that the mutations are an early genetic event in the pathogenesis. We examined 54 atypical adenomatous hyperplasias, precursor lesions of lung adenocarcinomas, obtained from 28 Japanese patients for the hotspot mutations of EGFR exons 19 and 21 and K-ras codon 12. EGFR mutations were observed in 17 of the 54 (32%) atypical adenomatous hyperplasias examined: Ten and seven atypical adenomatous hyperplasias had deletion mutations at exon 19 or point mutations (L858R) at exon 21, respectively. We did not observe apparent histological differences between atypical adenomatous hyperplasias with and without EGFR mutations. K-ras mutation (G12S) was detected in only one atypical adenomatous hyperplasia. As EGFR mutational frequency of atypical adenomatous hyperplasias was much lower than that of nonmucinous bronchioloalveolar carcinomas, we surmise that EGFR-mutated atypical adenomatous hyperplasias, but not atypical adenomatous hyperplasias with wild-type EGFR, are likely to progress to nonmucinous bronchioloalveolar carcinomas.     

Can EGFR mutation status be reliably determined in pre‐operative needle biopsies from adenocarcinomas of the lung?

The identification of EGFR mutations in non‐small‐cell lung cancer is important for selecting patients, who may benefit from treatment with EGFR tyrosine kinase inhibitors. The analysis is usually performed on cytological aspirates and/or histological needle biopsies, representing a small fraction of the tumour volume. The aim of the present investigation was to evaluate the diagnostic performance of this molecular test. We retrospectively included 201 patients with primary adenocarcinoma of the lung. EGFR mutation status (exon 19 deletions and exon 21 L858R point mutation) was evaluated on both pre‐operative biopsies (131 histological and 70 cytological) and on the surgical specimens, using PCR. Samples with low tumour cell fraction were assigned to laser micro‐dissection (LMD). We found nine (4.5%) patients with EGFR mutation in the lung tumour resections, but failed to identify mutation in one of the corresponding pre‐operative, cytological specimens. Several (18.4%) analyses of the pre‐operative biopsies were inconclusive, especially in case of biopsies undergoing LMD and regarding exon 21 analysis. Discrepancy of mutation status in one patient may reflect intra‐tumoural heterogeneity or technical issues. Moreover, several inconclusive results in the diagnostic biopsies reveal that attention must be paid on the suitability of pre‐operative biopsies for EGFR mutation analysis.     

双环探针特异引物荧光聚合酶链反应法检测非小细胞肺癌表皮生长因子受体基因突变

目的探讨双环探针特异引物荧光聚合酶链反应法(BPSP-qPCR)检测非小细胞肺癌( NSCLC)表皮生长因子受体(EGFR)基因突变的敏感性和稳定性。方法采用BPSP-qPCR法检测NSCLC中EGFR基因第18～21号外显子突变,分析突变与临床病理特征、不同检测样本间的关系。结果265例NSCLC样本中19-del和（或）L858R突变占30.2％( 80/265)。资料完整的184例中,女性、不吸烟者、腺癌有更高的19-del和（或）L858R突变率,分别为39.7％ (31/78)、41.0％ (43/105)、37.8％ (51/135) (P ＜0.05);T790M合并19-del和（或）L858R占3.3％(6/184);男性转移灶、女性和不吸烟者胸腔积液样本有较高的19-del和（或）L858R阳性突变率,分别为29.6％( 8/27)、42.9％(9/21)和40.7％(11/27),而非腺癌转移灶为0(P＞0.05)。结论BPSP-qPCR法检测EGFR基因突变稳定、敏感。EGFR基因敏感突变多见于女性、非吸烟、腺癌,胸腔积液样本和转移灶少量样本能够检出EGFR突变,指导临床治疗。     

Correlation between EGFR gene mutation pattern and Akt phosphorylation in pulmonary adenocarcinomas

The detection of gene mutation of epithelial growth factor receptor (EGFR) is important to predict the therapeutic effect of gefitinib. Recently, it was reported that examination of the activation of the downstream protein of EGFR is useful in the same way as the EGFR mutation. Therefore the purpose of the present paper was to determine whether activation of Akt and Erk, which are downstream proteins, and the EGFR gene mutation pattern was correlated. A total of 130 pulmonary adenocarcinomas were studied for the gene mutations of EGFR in exon 19 and 21, and the phosphorylation of Akt and Erk was investigated by immunostaining. The EGFR mutation was detected in 32%, the positivity of p-Akt was 51%, and the rate of p-Erk was 27%. The EGFR mutation-positive cases were the minority in p-Akt-negative cases, and the p-Akt expression was significantly associated with the mutation of EGFR (P=0.0014). In addition, there was a significant correlation between the L858R mutation and the expression of p-Akt (P=0.040). It is suggested that the activation of Akt is dependent on EGFR mutation pattern.     

Mutation status of somatic EGFR and KRAS genes in Chinese patients with prostate cancer (PCa)

Activating mutations of the epidermal growth factor receptor (EGFR) confers sensitivity to tyrosine kinase inhibitors (TKIs). In colorectal cancer and in lung adenocarcinomas, clinical trials have shown a lack of response to anti-EGFR therapy when KRAS gene mutations are present. In this study, the mutation status of specified exons of the EGFR and KRAS genes was profiled in patients with prostate cancer (PCa). Direct Sanger sequencing was used to screen for mutations in exons 19–21 of EGFR and in exon 2 of KRAS in 88 Chinese patients diagnosed with prostate adenocarcinomas. Mutations were detected in 11 patients. In nine cases (10 %), activating mutations in the region of EGFR encoding the tyrosine kinase (TK) domain were present. Deletions in exon 19 and the L858R substitution in exon 21 were “hotspot” mutations, together accounting for five (55 %) of nine cases. Many synonymous substitutions were also detected. KRAS mutations were found in two cases (2.3 % of 88). There were no cases with mutations in both EGFR and KRAS, suggesting that mutations in the two genes might be mutually exclusive. Although prognostic relevance of EGFR expression by immunohistochemistry (IHC) was observed in PCa patients in previous studies, we found no statistically significant association between EGFR or KRAS mutations and clinicopathological features (including age, smoking status, preoperative prostate-specific antigen, Gleason scores, and tumor stage). We contend that accurate profiling of the mutation status of EGFR and KRAS could improve prognostic stratification, and we suggest a potential anti-EGFR therapy for patients with PCa with EGFR mutations.