Search bioRxiv⌕ Search

bioRxiv · 10.1101/2020.07.06.188284

Screening predictors of weight loss: an Integromics Approach

Abstract

Obesity has reached epidemic proportions in the United States but little is known about the mechanisms of weight gain and weight loss. Integration of “omics” data is becoming a popular tool to increase understanding in such complex phenotypes. Biomarkers come in abundance from high-throughput experiments, but small sample size is still is a serious limitation in clinical trials. It makes assessment of more realistic assumptions for complex relationships such as nonlinearity, interaction and normality more difficult. In the present study, we developed a strategy to screen predictors of weight loss from a multi-omics, high-dimensional and longitudinal dataset from a small cohort of subjects. Our proposal explores the combinatorial space of candidate biomarkers from different data sources with the use of first-order Spearman partial correlation coefficients. Statistics derived from the sample correlations are used to rank and select biomarkers, and to evaluate the relative importance of each data source. We tackle the small sample size problem by combining nonparametric statistics and dimensionality reduction techniques useful for omics data. We applied the proposed strategy to assess the relative importance of biomarkers from 6 different data sources: RNA-seq, RT-qPCR, metabolomics, fecal microbiome, fecal bile acid, and clinical data used to predict the rate of weight loss in 10 obese subjects provided an identical low-calorie diet in a hospital metabolic facility. The strategy has reduced an initial set of more than 40K biomarkers to a set of 61 informative ones across 3 time points: pre-study, post-study and changes from pre- to post-study. Our study sheds light on the relative importance of different omics to predict rates of weight loss. We showed that baseline fecal bile acids, and changes in RT-qPCR biomarkers from pre- to post-study are the most predictive data sources for the rate of weight loss.Competing Interest StatementThe authors have declared no competing interest.AbbreviationsBPSBiomarker Predictive ScoreGSEAGene Set Enrichment AnalysisGSVAGene Set Variation AnalysisRT-qPCRReal Time quantitative Polymerase Chain ReactionSATSubcutaneous Adipose TissueVLCDVery Low Calorie DietWLWeight LossView Full Text

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Joel Correa da Rosa, Jose O. Aleman, Jason Mohabir, Yupu Liang, Jan L Breslow, Peter R. Holt. 2020-07-10. Screening predictors of weight loss: an Integromics Approach. https://doi.org/10.1101/2020.07.06.188284

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

Accelerating discovery and integration from RNA to Protein with R2T2P

Integrating transcriptomics and proteomics data remains an unmet challenge in the post-genomics era, discouraging researchers from pursuing integrative approaches to molecular biology research. Leveraging the power of translation profiling, we present RNA to Translation to Protein (R2T2P), a computational platform integrating genome-guided transcriptome assembly with identification of translation and proteins, including a tailored differential analysis framework and support for multiple reference transcriptomes. We applied R2T2P to investigate a cellular model of facioscapulohumeral muscular dystrophy (FSHD), where ectopic expression of the DUX4 retrogene in skeletal muscle triggers significant alterations in transcription and RNA metabolism. We uncovered hundreds of uncharacterized, highly overexpressed RNAs, including antisense and alternative transcripts, and quantified their contribution to translatome and proteome. Re-analysis of expression datasets from patient-derived myotubes and muscle biopsies validated this alternative transcriptome in FSHD patients, adding a reservoir of bona-fide novel molecular actors in a rare disease. Available at https://github.com/nfdata-omics/R2T2P/, R2T2P is a flexible and powerful workflow in modern integrative biology.

bioinformatics↗

MorphoANOVA: Dissecting Histology-Gene Expression Relationships in Spatial Transcriptomics

Spatial transcriptomics (ST) measures the expression of hundreds to thousands of genes within tissue architecture, often accompanied by histology images. However, it remains challenging to systematically characterize which genes exhibit associations with tissue morphology, whether these associations vary spatially, and which genes show additional spatial expression patterns beyond those captured by morphology. Here we introduce MorphoANOVA, a gene-wise statistical framework for characterizing morphology--expression relationships across genes measured by ST. Using nested spatially varying coefficient models and sequential ANOVA, MorphoANOVA assesses slide-wide associations with an H\&E-derived morphology feature, location-specific changes in these associations, and additional spatial variation after accounting for the selected feature. The resulting statistics enable gene prioritization and pathway enrichment analysis, while spatial component maps support the interpretation of individual genes. Simulations demonstrate MorphoANOVA's ability to distinguish the modeled components and recover their spatial patterns. Applications to human cortex and breast cancer identify biological programs associated with different morphology--expression patterns and reveal distinct relationships with cell composition. Across three HER2-positive breast cancer patients, invasive-cancer marker genes consistently exhibit stronger evidence of location-specific morphology associations. MorphoANOVA thus provides a framework for systematically interpreting spatial gene-expression patterns in relation to tissue morphology.

bioinformatics↗

Evaluation effects can rival reported concordance gains in cross-cancer survival prediction

Studies of cross-cancer learning for survival prediction from tumour omics have reported concordance gains of 0.020 and 0.045, but how such gains compare with evaluation effects remains unclear. We examined these effects across 13 TCGA cancers (5,761 patients, 1,526 disease-specific deaths), using five repeats of five-fold cross-validation and paired bootstrap intervals. When model selection did not use test data, our borrowing model gained 0.009 (95% interval 0.001 to 0.016) over its target-fitted reference when cancers received equal weight (post hoc). Random-effects pooling gave a gain of 0.002 (-0.002 to 0.006), with most weight assigned to cancers where the model made little use of the pretrained score. Choosing the fusion weight on test splits raised the apparent equal-weight gain to 0.017. We reimplemented a published method, VAECox, which showed no pretraining gain over random initialisation at the last or validation-selected training step. Choosing each network's best test step, as the published code does, raised concordance by 0.03 to 0.05 across the 13-cancer and ten-cancer overall-survival settings, but barely changed the difference between networks. In a constructed post hoc experiment, choosing the best test step only for the pretrained network changed the equal-weight mean difference from -0.004 to +0.045 (+0.035 to +0.054). Across seven multi-omics comparisons, estimates from single five-fold runs differed from their cancer's five-run mean by at least 0.02 in 11% to 42% of runs. Concordance was about 0.02 lower at held-out tissue source sites. Interpreting a reported gain therefore requires each model's selection rule, variation across repeated partitions, the weighting of cancers and the evaluation population.

bioinformatics↗