Pituitary Adenomas with Changing Phenotype: A Systematic Review

Phenotype Transformation of PitNETs

Phenotype transformation in pituitary neuroendocrine tumors is a little-known and unpredictable clinical phenomenon. Previous studies have not clearly defined and systematically concluded on the causes of this rare phenomenon. Additionally, the mechanisms of phenotype transformation are not well known. We reviewed cases reported in the literature with the aim of defining phenotype transformation in pituitary neuroendocrine tumors. We present an overview of the wide spectrum of phenotype transformation and its clinical features. We also discuss findings on the potential mechanism of this rare transformation, which may be related to PC1/3, the bioactivity of secretory hormones, gene mutations and the plasticity of pituitary neuroendocrine tumors. Clinicians should be aware of this rare phenomenon and more studies on the underlying mechanisms are required.

Spontaneous remission of Cushing's disease: A systematic review

Spontaneous remission is rare in Cushing's disease. We describe one illustrative case and provide a systematic review of cases previously reported in the literature. Case report: A 51-year-old woman diagnosed with Cushing's disease underwent 9 months' isolated metyrapone treatment. Two months after end of treatment, she was admitted with acute kidney failure. After another 4 months, in June 2020, there was no evidence of hypercortisolism, either clinically or biochemically, or of hypocortisolism. At the time of writing, 1 year later, she was still in remission. Cases reported in the literature: 23 patients were reported, including the present case. 87% were female with a median age of 32 years. Ten of those with radiologically visible tumors had microadenoma (44%) and 7 had macroadenoma (30%). Mean time from diagnosis to spontaneous remission was 5 months, and was shorter in macroadenoma (1 month) than in microadenoma (13.5 months). Treatments before spontaneous remission were: no treatment (65%), steroidogenesis enzyme inhibitors (22%), bilateral adrenalectomy and adrenal autotransplantation (5%), partial bilateral adrenalectomy (4%), and incomplete pituitary surgery (4%). Pituitary tumor apoplexy was the most frequently incriminated event (91%), radiologically documented in 43% of patients. Mean remission during follow-up was 28 months (range, 6-130 months). Recurrence occurred in 39% (n=9) of patients. Although several mechanisms responsible for this phenomenon have been proposed, clinical or subclinical pituitary tumor apoplexy, the latter sometimes presenting atypically, seems to be the most frequently incriminated event. Doctors should be aware of this, and regular follow-up is mandatory due to its unpredictability.

LncRNA PCAT6 regulates the progression of pituitary adenomas by regulating the miR-139-3p/BRD4 axis

BACKGROUND

Dysregulated lncRNA PCAT6 was discovered in many cancers excluding pituitary adenomas (PA). Therefore, we explored the role of PCAT6 in PA in this research.

METHODS

Abnormally expressed miRNAs were analyzed by bioinformatics and RT-qPCR. The target and regulator of miR-139-3p were determined by bioinformatics, dual-luciferase reporter assay, or RIP. The correlation among PCAT6, miR-139-3p, and BRD4 was further analyzed. The viability, apoptosis, cell cycle distribution of PA cells, as well as their ability to invade, migrate, and proliferate, were tested after transfection through CCK-8, flow cytometry, transwell, wound healing, and colony formation assays. After construction of transplanted-tumor model in nude mice, cell apoptosis in the tumor was detected by TUNEL. The expressions of PCAT6, BRD4, miR-139-3p, and apoptosis-related factors in PA tissues, cells, or tumor tissues were detected by RT-qPCR, Western blot, or IHC.

RESULTS

PCAT6 and BRD4 were high-expressed but miR-139-3p was low-expressed in PA. Both the 3'-untranslated regions of PCAT6 and BRD4 mRNAs were demonstrated to contain a potential binding site for miR-139-3p. PCAT6 was positively correlated to BRD4, and miR-139-3p was negatively correlated to PCAT6 and BRD4. MiR-139-3p mimic, shPCAT6 and siBRD4 inhibited the viability, migration, invasion, and proliferation of PA cells while inducing apoptosis. MiR-139-3p mimic and shPCAT6 inhibited the cell cycle progression of PA cells, decreased the weight and volume of the xenotransplanted tumor, and reduced the levels of Bcl-2 and BRD4 while enhancing the levels of Bax, miR-139-3p, and Cleaved caspase-3. MiR-139-3p inhibitor caused the opposite effect of miR-139-3p mimic and further reversed the effect of shPCAT6 on on PA cells.

CONCLUSION

PCAT6 regulated the progression of PA via modulating the miR-139-3p/BRD4 axis, which might provide a novel biomarker for the prevention, diagnosis, and treatment of PA.