P-325 Evidence for dysregulation of oncogene pathways at the gene expression level in the epithelium of deep infiltrating endometriosis compared to adenomyosis

Abstract Study question How does the gene expression profile of epithelium cells differ between deep infiltrating endometriosis (DIE) and adenomyosis (FA)? Summary answer The gene expression of epithelial cells from DIE reveals a significant upregulation of the PI3K-pathway and downregulation of the RAS-pathway compared to epithelium from FA. What is known already Both DIE and FA, are histologically considered benign but have features of malignant diseases, such as a tendency for local tissue invasion. Recent next generation sequencing studies have detected driver mutations in cancer-associated genes such as PIK3CA, ARID1A, PPP2R1A and KRAS in the epithelium of DIE, as well as in KRAS in epithelium of FA. Furthermore, identical mutations in the KRAS gene were detected in coexisting adenomyotic and endometriotic lesions, supporting the theory of a common molecular mechanism. The gene expression differences between these two entities were therefore investigated in the present study. Study design, size, duration This is an experimental analysis of 7 adenomyosis and 19 DIE samples (histologically confirmed), that were formalin-fixed and paraffin-embedded (FFPE) collected between 2003 and 2018. These were provided by the tissue bank of the National Centre for Tumour Diseases (Heidelberg, Germany), in accordance with the Ethics Committee of the University of Heidelberg (approval number S-362/2017). In addition, the medical and epidemiological data of the corresponding patients were retrospectively analyzed based on the clinical data collected. Participants/materials, setting, methods For this study, the epithelia of FFPE samples were microdissected in a laser-guided fashion. After RNA extraction, the expression of 770 genes was analyzed using the nCounter Technology with the Human PanCancer Pathways Panel (Nanostring). All genes with an adjusted false discovery rate of p < 0.05 and a fold change of < 0.66 or > 1.5 were considered differentially expressed and subjected to functional annotation and clustering using DAVID bioinformatics resources. Main results and the role of chance Our analysis revealed a total of 162 differentially expressed genes, that were either significantly increased (n = 116) or decreased (n = 46) in epithelium of DIE compared to that of FA (with log2 fold changes of < 0.66 or > 1.5 and an adjusted p-value of < 0.05). Gene ontology and KEGG pathway analysis for genes with increased expression in DIE compared with FA revealed significant upregulation of genes belonging to the PI3K-pathway and the focal adhesion pathway, as well as pathways related to viral infection, endocrine resistance, and malignancy. The upregulated pathways in adenomyosis mainly included the RAS-pathway. Limitations, reasons for caution The average age of DIE patients was lower, but many of them were hormonally inactive due to GnRH analogues, which mitigates any age-related differences. Furthermore, only relative expression was studied between the groups without comparison to normal endometrium. Overall, the sample size is relatively small and further studies are needed. Wider implications of the findings The expression of different signaling pathways in the two entities could, for example, explain the different sensitivity of the two diseases to certain therapeutic approaches. While DIE responds well to therapy with the progestogen dienogest, progesterone resistance is often described in adenomyosis patients. Trial registration number not applicable