Endocrine Abstracts (2017) 49 OC1.1 | DOI: 10.1530/endoabs.49.OC1.1

High resolution tissue mass spectrometry imaging: a new tool for identification of prognostic markers in adrenocortical carcinoma

Thomas Kunzke1, Na Sun1, Silviu Sbiera2,3, Vanessa Wild3, Michaela Aichler1, Cristina Ronchi2, Nicolas Schlegel2, Andreas Rosenwald3, Martin Fassnacht2,3, Axel Walch1 & Matthias Kroiss2,3

1Helmholtz-Center Munich, Munich, Germany; 2University Hospital Würzburg, Würzburg, Germany; 3University of Würzburg, Würzburg, Germany.

Adrenocortical carcinoma (ACC) is an orphan tumor entity the pathogenesis of which is poorly understood. In advanced tumour stages, prognosis is unfavorable, but biomarkers for early diagnosis are lacking. MALDI-Mass Spectrometry Imaging (MALDI-MSI) enables semi-quantitative detection of a broad spectrum of analytes including endogenous cell metabolites in tissue sections. MALDI-MSI was used as a discovery approach to analyse tissue specimens of 72 ACC patients in FFPE tissue arranged in tissue microarrays to identify pathways of pathophysiological relevance and histologic markers related to patient prognosis. We focused on steroid hormones and their metabolites which might also serve as tumour-derived blood biomarkers in the future. 3843 individual endogenous m/z species were obtained of which five were identified as known components of steroid hormone synthesis and metabolism. 2/5 steroid hormone metabolites showed differential abundance between ACC samples. Their low abundance in 5 and 6 of the 72 ACC samples was associated with poor overall survival in Kaplan-Meier analyses (Log rank P=0.0030 and 0.0045, respectively). Based on the type of the steroid hormone modification present, mass spectra were screened for related m/z species. An unusual steroid hormone metabolite (M) was identified and validated by tandem mass spectrometry. After multivariable adjustment for age, tumor stage and sex by using the Cox proportional hazards model, presence of M was associated with poor overall survival (HR 4.54, 95%CI 1.56–13.22; P=0.0056). By using immunohistochemistry we analysed protein expression of two related enzymes which was correlated with metabolites abundance. In conclusion, we demonstrated the utility of MALDI-MSI in detecting and identifying small molecule markers in FFPE tissue samples of ACC. A limited number of compounds related to steroidogenesis with strong prognostic value could be detected. One steroid hormone metabolite and related enzymes were of outstanding prognostic value. The potential of these metabolites as blood biomarkers remains to be investigated.