Integrative multi-omics analysis identifies a prognostic miRNA signature and a targetable miR-21-3p/TSC2/mTOR axis in metastatic pheochromocytoma/paraganglioma

Rationale: Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors that present variable outcomes. To date, no effective therapies or reliable prognostic markers are available for patients who develop metastatic PPGL (mPPGL). Our aim was to discover robust prognostic markers validated through in vitro models, and define specific therapeutic options according to tumor genomic features. Methods: We analyzed three PPGL miRNome datasets (n=443), validated candidate markers and assessed them in serum samples (n=36) to find a metastatic miRNA signature. An integrative study of miRNome, transcriptome and proteome was performed to find miRNA targets, which were further characterized in vitro. Results: A signature of six miRNAs (miR-21-3p, miR-183-5p, miR-182-5p, miR-96-5p, miR-551b-3p, and miR-202-5p) was associated with metastatic risk and time to progression. A higher expression of five of these miRNAs was also detected in PPGL patients' liquid biopsies compared with controls. The combined expression of miR-21-3p/miR-183-5p showed the best power to predict metastasis (AUC=0.804, P=4.67·10-18), and was found associated in vitro with pro-metastatic features, such as neuroendocrine-mesenchymal transition phenotype, and increased cell migration rate. A pan-cancer multi-omic integrative study correlated miR-21-3p levels with TSC2 expression, mTOR pathway activation, and a predictive signature for mTOR inhibitor-sensitivity in PPGLs and other cancers. Likewise, we demonstrated in vitro a TSC2 repression and an enhanced rapamycin sensitivity upon miR-21-3p expression. Conclusions: Our findings support the assessment of miR-21-3p/miR-183-5p, in tumors and liquid biopsies, as biomarkers for risk stratification to improve the PPGL patients' management. We propose miR-21-3p to select mPPGL patients who may benefit from mTOR inhibitors.We gratefully acknowledge Manuel Morente and María Jesús Artiga from the CNIO biobank for providing assistance on tumor tissue selection, Joaquín Amat for his advice and great help on data visualization and plotting, as well as María Maroto and Guillermo de Cárcer from the Cell Division and Cancer Group at the CNIO for technical support and fruitful discussions. We are also grateful to Mathieu Madeleine and all members of the Genetics Department, Biological Resources Center and Tumor Bank Platform, Hôpital européen Georges Pompidou (BB-0033-00063) for technical support.This work was supported by the Instituto de Salud Carlos III (ISCIII), Acción Estratégica en Salud, cofounded by FEDER, [grant number PI14/00240, PI17/01796 to M.R., PI15/00783 to A.C], the Paradifference Foundation [no grant number applicable to M.R.], the ANR [ANR-2011-JCJC-00701 MODEOMAPP to AP.G-R], the European Union [FP7/2007-2013 n° 259735, Horizon 2020 n° 633983 to AP.G-R], Epigénétique et Cancer [EPIG201303 METABEPIC to AP.G-R], the the Ligue Nationale contre le Cancer ["Cartes d'Identité des Tumeurs (CIT) program" to AP.G-R], the Institut National du Cancer, the Direction Générale de l’Offre de Soins [PRT-K 2014, COMETE-TACTIC, INCa-DGOS_8663 to AP.G-R], the Deutsche Forschungsgemeinschaft(DFG) [CRC/Transregio 205/1 “The Adrenal: Central Relay in Health and Disease“ to F.B, M.F and G.E], the Rafael del Pino Foundation [Becas de Excelencia Rafael del Pino 2017 to B.C], the Severo Ochoa Excellence Programme [project SEV -2011-0191 to M.C-F], La Caixa Foundation [B004235 to JM.R-R], the Spanish Ministry of Education, Culture and Sport [grant number FPU16/05527 to M.S.], the Site de Recherche Intégré sur le Cancer-SIRIC [CARPEM Project to N.B.] and the AECC Foundation [grant number AIO15152858 to C.M. -CS