MicroRNA 183 family profiles in pheochromocytomas are related to clinical parameters and SDHB expression

From diagnosis to resistance: a symphony of miRNAs in pheochromocytoma progression and treatment response

Pheochromocytoma (PCC) is a neuroendocrine tumor that produces and secretes catecholamine from either the adrenal medulla or extra-adrenal locations. MicroRNAs (miRNAs, miR) can be used as biomarkers to detect cancer or the return of a previously treated disease. Blood-borne miRNAs might be envisioned as noninvasive markers of malignancy or prognosis, and new studies demonstrate that microRNAs are released in body fluids as well as tissues. MiRNAs have the potential to be therapeutic targets, which would greatly increase the restricted therapy options for adrenal tumors. This article aims to consolidate and synthesize the most recent studies on miRNAs in PCC, discussing their potential clinical utility as diagnostic and prognostic biomarkers while also addressing their limitations.

A long noncoding RNA-microRNA expression signature predicts metastatic signature in pheochromocytomas and paragangliomas

PURPOSE

In hopes of discovering new markers for metastatic or aggressive phenotypes of pheochromocytomas and paragangliomas (PCPG), we analyzed the noncoding transcriptome from patient gene expression data in The Cancer Genome Atlas.

METHODS

Differential expression of miRNAs was observed between PCPG molecular subtypes. We specifically characterized candidate miRNAs that are upregulated in pseudohypoxic PCPGs with mutations in succinate dehydrogenase complex subunits, B and/or D (SDHB and/or SDHD, respectively), which are mutations associated with unfavorable clinical outcomes.

RESULTS

Our computational analysis identified four candidate miRNAs that showed elevated expression in metastatic compared to non-metastatic PCPGs: miR-182, miR-183, miR-96, and miR-383. We also found six candidate lncRNAs harboring opposite expression patterns from the miRNAs when we analyzed the expression profiles of their predicted target lncRNAs. Three of these lncRNA candidates, USP3-AS1, LINC00877, and AC009312.1, were validated to have reduced expression in metastatic compared to non-metastatic PCPGs. Finally, using univariate and multivariate analysis, we found miRNA miR-182 to be an independent predictor of metastasis-free survival in PCPGs.

CONCLUSIONS

We identified candidate miRNA and lncRNAs associated with metastasis-free survival in PCPGs.

What Have We Learned from Molecular Biology of Paragangliomas and Pheochromocytomas?

Recent advances in molecular genetics and genomics have led to increased understanding of the aetiopathogenesis of pheochromocytomas and paragangliomas (PPGLs). Thus, pan-genomic studies now provide a comprehensive integrated genomic analysis of PPGLs into distinct molecularly defined subtypes concordant with tumour genotypes. In addition, new embryological discoveries have refined the concept of how normal paraganglia develop, potentially establishing a developmental basis for genotype-phenotype correlations for PPGLs. The challenge for modern pathology is to translate these scientific discoveries into routine practice, which will be based largely on histopathology for the foreseeable future. Here, we review recent progress concerning the cell of origin and molecular pathogenesis of PPGLs, including pathogenetic mechanisms, genetic susceptibility and molecular classification. The current roles and tools of pathologists are considered from a histopathological perspective, including differential diagnoses, genotype-phenotype correlations and the use of immunohistochemistry in identifying hereditary predisposition and validating genetic variants of unknown significance. Current and potential molecular prognosticators are also presented with the hope that predictive molecular biomarkers will be integrated into risk stratification scoring systems to assess the metastatic potential of these intriguing neoplasms and identify potential drug targets.

Comprehensive Analysis of Aberrantly Expressed Competitive Endogenous RNA Network and Identification of Prognostic Biomarkers in Pheochromocytoma and Paraganglioma

Background

Long non-coding RNA (lncRNA) functions as a competitive endogenous RNA (ceRNA) and plays an important role in the biological processes underlying tumorigenesis. However, studies describing the function of lncRNA in pheochromocytoma and paraganglioma (PCPG) remain largely unknown. Our study aims to construct a regulatory ceRNA network and explore prognostic biomarkers for PCPG through a comprehensive analysis.

Methods

PCPG data from The Cancer Genome Atlas (TCGA) were utilized to obtain differentially expressed lncRNAs (DElncRNAs), microRNAs (DEmiRNAs), and mRNAs (DEmRNAs). Kaplan–Meier analysis was used to detect prognostic biomarkers and Cytoscape was utilized to construct a regulatory network of ceRNA. Potential lncRNA–miRNA–mRNA axes were inferred by correlation analysis. GO and KEGG pathways were constructed using “clusterProfiler” and “DOSE” R-packages. Immunohistochemistry (IHC) staining was performed to validate differential protein expression levels of genes in the axes. Finally, the GSE19422 dataset and Pan-Cancer data were applied to validate the expression pattern and survival status of mRNAs, respectively.

Results

A total of 334 DElncRNAs, 116 DEmiRNAs, and 3496 DEmRNAs were identified and mainly enriched in hormone secretion, metabolism signaling, metastatic and proliferative pathways. Among these differentially expressed genes, 16 mRNAs, six lncRNAs, and two miRNAs were associated with overall survival of patients with PCPG and sequentially enrolled in the ceRNA network. Two lncRNA–miRNA–mRNA regulatory axes were predicted: AP001486.2/hsa-miR-195-5p/RCAN3 and AP006333.2/hsa-miR-34a-5p/PTPRJ. The GSE19422 dataset and IHC analysis validated that mRNA and protein levels of RCAN3 and PTPRJ were upregulated in PCPG tissues compared with adjacent adrenal gland medulla tissues. Pan-Cancer data showed that the upregulated expression of RCAN3 and PTPRJ was associated with favorable overall survival and disease-free survival.

Conclusion

A regulatory lncRNA–miRNA–mRNA ceRNA network was successfully constructed and 24 prognostic biomarkers were identified for PCPG patients. These findings may contribute toward a better understanding of the biological mechanism of tumorigenesis and enable further evaluation of the prognosis of patients with PCPG.

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.

Circulating microRNAs in adrenal tumors

PURPOSE OF REVIEW

Circulating microRNAs represent promising minimally invasive markers of several diseases including tumors. As the preoperative diagnosis of different adrenal tumors is difficult, for example, diagnosis of adrenocortical or adrenomedullary malignancy, circulating microRNAs might be helpful in their clinical management.

RECENT FINDINGS

Observations regarding the applicability of circulating microRNAs isolated both from unfractionated plasma or serum and from extracellular vesicle preparations for the diagnosis of adrenocortical malignancy have been published. Data show that circulating microRNA might be exploited for monitoring adrenocortical cancer progression. Circulating microRNA profiles of adrenal myelolipoma have also been published that might be useful for differentiating adrenocortical cancer and adrenal myelolipoma in dubious cases.

SUMMARY

In this review, recent advances in the field of circulating microRNAs in adrenal tumors are discussed.