On-tissue chemical derivatization enables spatiotemporal heterogeneity visualization of oxylipins in esophageal cancer xenograft via ambient mass spectrometry imaging

On-tissue chemical derivatization(OTCD)effectively enhances ionization efficiency of low abundant and poorly ionized functional molecules to improve detection sensitivity and coverage of mass spectrometry imaging(MSI).Combination OTCD and MSI provides a novel strategy for visualizing previously undisclosed metabolic heterogeneity in tumor.Herein,we present a method to visualize heterogeneous metabolism of oxylipins within tumor by coupling OTCD with airflow-assisted desorption electrospray ionization(AFADESI)-MSI.Taking Girard’s P as a derivatization reagent,easily ionized hydrazide and quaternary amine groups were introduced into the structure of carbonyl metabolites via condensation reaction.Oxylipins,including 127 fatty aldehydes(FALs)and 71 oxo fatty acids(FAs),were detected and imaged in esophageal cancer xenograft with AFADESI-MSI after OTCD.Then t-distributed stochastic neighbor embedding and random forest were exploited to precisely locate the distribution of oxylipins in heterogeneous tumor tissue.With this method,we surprisingly found almost all FALs and oxo FAs significantly accumulated in the core region of tumor,and exhibited a gradual increase trend in tumor over time.These results reveal spatiotemporal heterogeneity of oxylipins in tumor progression,highlighting the value of OTCD combined with MSI to gain deeper insights into understanding tumor metabolism.

Mass Spectrometry and Mass Spectrometry Imaging-based Thyroid Cancer Analysis

Thyroid carcinoma is one of the most common endocrine malignant diseases worldwide.With the rapid development of medical technology,early and effective diagnostic methods could be able to improve the survival rate and quality of life of patients suffering from the disease.Considering the complexity of cancer,some specific detection method is desired for diagnosis and treatment.Mass spectrometry imaging(MSI)is an emerging technique for acquiring molecular information from biological tissues without staining and labeling,including qualitative,quantitative and spatial distribution information.Over the past several decades,MSI has been widely used for pharmacological monitoring,biomolecular imaging of cells and tissues.In this review,we introduce the tumor progression and histological characteristics of thyroid cancer,and focus mainly on the preparation of biological specimens for MSI and mass spectrometry(MS)analysis,as well as the recent progress in MS and MSI-based thyroid cancer research.This review thoroughly discusses the importance of MS and MSI for clinical diagnosis,identification and prognosis of thyroid cancer,and provides some new clues for molecular mechanisms research and tumor metastasis.