The lipid-metabolizing enzymes remain underexplored in gastrointestinal stromal tumors (GISTs). Through transcriptomic reappraisal, hydroxysteroid 11-beta dehydrogenase-1 (HSD11B1) was identified as a top-upregulated, progression-associated gene. To validate the clinical relevance of HSD11B1, the informative results of Sanger sequencing (n = 58), mRNA quantification by branched-chain DNA in situ hybridization assay (n = 70), copy number assay by fluorescent in situ hybridization (n = 350), and immunohistochemistry (n = 350) were correlated with clincopathological variables, KIT/PDGFRA/BRAF genotypes, and disease-free survival (DFS). HSD11B1 was stably silenced to explore its oncogenic function. HSD11B1 mRNA varied between high-risk and non-high-risk groups (p = 0.009) and positively correlated with HSD11B1 immunoexpression (r = 0.783, p < 0.001). HSD11B1 copy-number gain (CNG), including polysomy (5.4%) and amplification (12%), associated with HSD11B1 overexpression (p < 0.001). Predominantly involving the homodimer interface-affecting exon 6 or exon 7, missense HSD11B1 mutations (17.2%) were related to high risk (p = 0.044), age ≥70 years (p = 0.007), and shorter DFS among relapsed cases (p = 0.033). CNG was related to unfavorable KIT/PDGFRA/BRAF genotypes (p = 0.015), while HSD11B1 overexpression was preferential in non-gastric cases (p < 0.001). Both abnormalities strongly associated with risk levels (both p < 0.001) and shorter univariate DFS (both p < 0.0001), and HSD11B1 CNG remained prognostically independent (p < 0.001) with a 3-fold increased hazard ratio. In vitro, HSD11B1 knockdown significantly inhibited proliferation and caused G2/M arrest. In conclusion, HSD11B1 overexpression may occur owing to CNG, confer a pro-proliferative function, and predict a worse prognosis in GISTs.
Keywords: HSD11B1; gain; gastrointestinal stromal tumor; lipid; metabolism; mutation; overexpression; transcriptome.