Application of serum proteomic patterns by ProteinChip SELDI system in diagnosis of gastric cancer

Abstract

[한글]위암은 전 세계적으로 가장 흔한 암중의 하나이고, 우리 나라에서도 주요한 암 관련 사망원인 중 하나이다. 대부분의 진행성 위암에 대한 치료효과는 제한적이고, 중앙생존값이 10개월에 불과하다. 조기에 진단되는 경우 완치율이 높지만 진행 위암인 경우는 예후가 매우 불량하여 효과적인 조기선별 검사법이 절실히 필요하다. 위내시경검사는 위암의 조기진단에 가장 중요한 수단이지만 침습적이고 비용이 많이 든다. 최근 여러 암에 대해 생물학적지표를 적용함으로써 종양 진단율은 향상되었다. 단백질칩 Surface-Enhanced Laser Desorption/ Ionization Time-of-flight Mass Spectrometry (SELDI-TOF-MS) system은 다양한 생화학 샘플 들을 한 번에 처리할 수 있는 혁신적인 단백질체학 기술로, 샘플로부터 단백질을 신속히 정리, 감지, 분석하여 질병 특이적인 생물학적 지표를 발견해 내는데 사용되고 있다. 본 연구에서는 단백질칩 SELDI system에 의한 혈청 단백질 패턴으로 위암 환자와 정상인을 감별할 수 있는지 알아보고자 하였다.위암 환자 60명과 동일 연령의 정상 대조군 40명으로부터 혈청 샘플을 얻어 단백질칩 SELDI system을 사용해 단백질 패턴을 조사한 결과 두 그룹간에 차이를 보이는 단백 최고점을 발견하였다. 이를 이용해 위암 환자와 정상인을 감별할 수 있는 의사결정 계통도를 완성하였고 96.7% (58/60)의 민감도와 97.5% (39/40)의 특이도를 보였다. 무작위적으로 위암 환자 30명과 정상인 20명의 혈청을 분석, 비교한 결과에서는 위암 진단에 대한 93.3% (28/30) 민감도와 90% (18/20) 특이도를 보였다. 본 연구의 결과는 단백질칩 SELDI System이 높은 정확성으로 위암을 진단해 낼 수 있음을 증명하였다.

[영문]Gastric cancer is one of the most common malignancy in the world and one of the leading causes of cancer related death in Korea. Most treatments for advanced gastric cancer have limited efficacy, and the median survival is just 10 months. So early detection of gastric cancer could have profound impact on the successful treatment. While endoscopic evaluation has been the gold standard for screening for gastric cancer, endoscopy is an invasive and expensive procedure. Therefore, development of novel screening methods that reduce costs and risks is critical in impacting mortality rates from gastric cancer. Application of multiple biomarkers may improve the diagnostic prediction to distinguish cancer from non-cancer. ProteinChip Surface-Enhanced Laser Desorption/Ionization Time-of-flight Mass Spectrometry (SELDI-TOF-MS) system is one of the currently used techniques to identify biomarkers for cancers and other diseases. This study was performed to identify whether the serum proteomic patterns by ProteinChip SELDI system can differentiate gastric cancers from non-cancer cohorts.The protein profiles of 100 serum samples obtained from 60 gastric cancer patients and 40 age-matched healthy individuals were screened by SELDI-TOF-MS system. Protein expression profiles were expressed on CM10 ProteinChip (weak cation exchange) Array and analyzed by Ciphergen PreoteinChip Reader (model PBS II). Peak intensities were normalized by total ion currency and analyzed by the Biomarker Wizard Software to identify the peaks showing significantly different intensities between normal and cancer groups. Classification analysis and construction of decision trees were done with the Biomarker Pattern Software 5.0.SELDI-TOF-MS by averaging 50 laser spots collected at a laser intensity setting of 160, a detector sensitivity of 6, and mean mass range of 30 kDa. Seventeen protein peaks shown significant differences between two groups were chosen to make a protein biomarker pattern. The decision tree which gives the highest discrimination for the training set includes four peaks at 5919, 8583, 10286, and 13758 as splitters. The sensitivity and the specificity for classification of the training set with the decision tree giving the highest discrimination were 96.7% (58/60) and 97.5% (39/40), respectively. When the protein biomarker pattern was tested with the blinded test set including 30 gastric cancer patients and 20 healthy individuals and, it yielded a sensitivity of 93.3% (28/30) and a specificity of 90% (18/20). These results suggest that serum-protein profiling pattern by SELDI system may distinguish gastric cancer patients from normal counterparts with relatively high sensitivity and specificity.