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Comprehensive miRNA expression analysis in peripheral blood can diagnose liver disease Yoshiki Murakami (M.D.), Hidenori Toyoda, Toshihito Tanahashi, Junko Tanaka,Takashi Kumada, Yusuke Yoshioka, Nobuyoshi Kosaka, Takahiro Ochiya, Y-h Taguchi. PLoS ONE (2012) 7(10): e48366.
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Comprehensive miRNA expression analysis in peripheral blood can diagnose liver disease Yoshiki Murakami (M.D.), Hidenori Toyoda, Toshihito Tanahashi, Junko Tanaka,Takashi Kumada, Yusuke Yoshioka, Nobuyoshi Kosaka, Takahiro Ochiya, Y-h Taguchi PLoS ONE (2012) 7(10): e48366
Discrimination vs normal liver disease: ※Hepatocellular carcinoma (HCC, liver cancer) ※Chronic hepatitis C (CHC, liver inflammation type C ) ※Chronic hepatitis B (CHB, liver inflammation type B) ※Non-alcoholic fatty liver disease (NAFLD), included Nonalcoholic steatohepatitis (NASH →Cirrhosis → HCC )
Task under the following Conditions: ※Small number of samples (patients). Less than 100, sometimes <10 in each class ※High reproducibility (for clinical application) ※Feature extraction (FE) with stability (hopefully < 10 miRNAs among more than a few hundreds miRNAs [in exosome in blood] ) Cf. Compressive Sensing
What is miRNA? ・miRNA = microRNA ・non-coding RNA ・regulate (suppress) target gene expression via either degradation or translation interruption of target genes
※Why blood? →non-invasive, less stress to patients ※Why miRNA? →possibility to diagnose multiple diseases with miRNAs measurements only. (Cf. YT and YM, SIGBIO28 2012.3)
Number of samples (patients) 887 miRNAs in exosome in blood (Agilent miRNA array) + clinical information (age, sex, BMI, inflammation, fibrosis etc...)
Method: PCA-based Linear discriminant analysis with PCA-based feature extraction without labeling information (YT and YM, SIGBIO28, 2012. 3 at Tohoku U) because of stability requirement Very few researches of FE focusing stability (eg. Varshavsky R et al (2007) Bioinformatics) Unsupervised Feature Filtering (UFF) more computationally massive than ours
Results for training data (Leave-one-out cross validation) Prediction Accuracy : 87.5% with 12 miRNAs up to 13 PCs (up to 16 probes for each miRNA)
Embedding with PCA (2D) +: CHB, ◦: CHC, ×:NASH △: NL.
NEED for increasing samples in silico MCMC miRNA 〜 age + gender + BMI + inflammation stage + fibrosis stage Distribution of coefficient Resampled clinical information miRNA × =
The Advantage of MCMC based resampling y X X x a ↔ b : correlated
Embedding with PCA (2D) +: CHB, ◦: CHC, ×:NASH △: NL.
Results for training data (LOOCV) Resampled Prediction Accuracy : 95.25% with 12 miRNAs up to 5 PCs (up to 16 probes for each miRNA)
Test sample comes …. Requirement : ※Use same miRNAs selected for Training data Ans.: Semi-supervised PCA-based LDA Training + Test → PCA PCA-based LDA with Training sample label → discriminate Test Set ※Validate in silico resmpling by independent data Ans.: validated by HCC data (not shown here)
Conclusions ※From clinical point of views, miRNAs in exsome in blood can diagnose liver diseases ※PCA-based FE is useful one as a unsupervised FE ※MCMC based in silico resampling is useful (only for miRNA?) ※semi-supervised PCA-based LDA can work (only for miRNA?)
BTW, It was press released.... “We will try to make it recognized as a highly advanced medical treatment in three years” (!)