Circulating Plasma microRNA to Differentiate Cushing's Disease From Ectopic ACTH Syndrome

Abstract

Corticotropinomas and adrenocorticotropic hormone (ACTH)-secreting neuroendocrine tumors exhibit differential levels of some microRNAs (miRs) compared to normal tissue. Because miRs can be released from tissues into circulation, they offer promise as novel disease biomarkers. Objective: To evaluate whether miRs are differentially detected in plasma samples of patients with ACTH-dependent Cushing's syndrome (CS). Design: Case-control study. Methods: Morning fasting plasma samples were collected from 41 consecutive patients with confirmed ACTH-dependent CS and 11 healthy subjects and stored at −80 • C. Twenty-one miRs previously reported to be differentially expressed in ACTH-secreting tumors vs. healthy tissue samples were quantified in plasma by qPCR. Results: Among enrolled subjects, 28 were confirmed to have Cushing's disease (CD), 13 had ectopic ACTH secretion (EAS) and 11 were healthy controls. We found statistically significant differences in the circulating levels of miR-16-5p [45.04 (95% CI 28.77-61.31) in CD vs. 5.26 (2.65-7.87) in EAS, P < 0.001; q = 0.001], miR-145-5p [0.097 (0.027-0.167) in CD vs. undetectable levels in EAS, P = 0.008; q = 0.087] and differences in miR-7g-5p [1.842 (1.283-2.400) in CD vs. 0.847 (0.187-1.507) in EAS, P = 0.02; q = 0.14]. The area under the receiver-operator (ROC) curve was 0.879 (95% CI 0.770-0.987), p < 0.001, when using miR-16-5p to distinguish between CD and EAS. Circulating levels of miR-16-5p in the healthy control group differed from that of both the CD and EAS groups. Conclusions: Plasma miR levels differ in patients with CD and EAS. In particular, miR-16-5p, miR-145-5p and miR-7g-5p are promising biomarkers for further research to differentiate ACTH-dependent CS.

Large Scale Molecular Studies of Pituitary Neuroendocrine Tumors: Novel Markers, Mechanisms and Translational Perspectives

“…MiRNA quantification and differential expression analyses identified three upregulated miRNAs in patients with ACTH-secreting PitNET: miR-16-5p, miR-145-5p, and let-7g-5p. MiR-16-5p and miR-7g-5p were particularly interesting as they were also upregulated in patients with PitNET when compared with healthy controls, further hinting that the source of these miRNAs was the tumor itself [ 143 ].…”

“…Studies on circulating plasma miRNAs in PitNET patients are scarce, with only four proposed candidate markers identified so far: miR-143-3p, miR-16-5p, miR-145-5p, and let-7g-5p [ 140 , 143 ]. By comparing these findings to miRNA studies in tissues of PitNETs and other tumors the expression values of these miRNAs in plasma are inverse to findings in tissue studies ( Table 3 ).…”

“…In several tumor tissue studies, miR-143-3p was significantly downregulated and acted as a tumor suppressor by silencing genes which promoted cell proliferation and invasion, i.e., COX-2 in gastric cancer, FOSL2 in osteosarcoma, and KRAS in PitNET [ 144 , 145 , 146 ]. For miR-145-5p (upregulated in plasma) [ 143 ], an in vitro study demonstrated it increased prolactin-secreting PitNET cell susceptibility to bromocriptine therapy, was downregulated in therapy-resistant tumors, and targeted TPT1 , a cell survival-promoting factor with a crucial role in the p53 pathway [ 147 , 148 ]. Several tumor studies reported miR-16-5p (upregulated in plasma) was downregulated, suggesting this miRNA most likely functioned as a tumor-suppressive miRNA.…”

Circulating microRNA Expression in Cushing’s Syndrome

“…Therefore, we hypothesized that a potential miRNA based diagnostic should aid in the diagnosis of CS or its subtypes as circulating miRNAs have proven their potential as minimal invasive biomarkers in other diseases ( 33 ). Few studies have investigated circulating miRNA profiles in CS, and appropriate controls matched for sex, BMI and comorbidities were missing ( 17 , 34 ). Therefore, in our study we included clinically relevant control samples to identify a unique circulating miRNA signature associated with CS.…”

“…Importantly, circulating miRNAs, miR-34a, and miR-483-5p were identified as candidate serum biomarkers distinguishing between benign and malignant adrenocortical tumors ( 16 ). In ectopic ACTH-dependent CS, there has been a single study reporting differences in plasma miR-expression ( 17 ). However, to the best of our knowledge, studies comparing different types of CS with each other have not yet been performed.…”