A miR-375/YAP axis regulates neuroendocrine differentiation and tumorigenesis in lung carcinoid cells

Netrin-1 and UNC5B Cooperate with Integrins to Mediate YAP-Driven Cytostasis

Opposite expression and pro- or anti-cancer function of YAP and its paralog TAZ/WWTR1 stratify cancers into binary YAPon and YAPoff classes. These transcriptional coactivators are oncogenic in YAPon cancers. In contrast, YAP/TAZ are silenced epigenetically along with their integrin and extracellular matrix adhesion target genes in neural and neuroendocrine YAPoff cancers (e.g., small cell lung cancer, retinoblastoma). Forced YAP/TAZ expression induces these targets, causing cytostasis in part through Integrin-αV/β5, independent of the integrin-binding RGD ligand. Other effectors of this anticancer YAP function are unknown. Here, using clustered regularly interspaced short palindromic repeats (CRISPR) screens, we link the Netrin receptor UNC5B to YAP-induced cytostasis in YAPoff cancers. Forced YAP expression induces UNC5B through TEAD DNA-binding partners, as either TEAD1/4-loss or a YAP mutation that disrupts TEAD-binding (S94A) blocks, whereas a TEAD-activator fusion (TEAD(DBD)-VP64) promotes UNC5B induction. Ectopic YAP expression also upregulates UNC5B relatives and their netrin ligands in YAPoff cancers. Netrins are considered protumorigenic, but knockout and peptide/decoy receptor blocking assays reveal that in YAPoff cancers, UNC5B and Netrin-1 can cooperate with integrin-αV/β5 to mediate YAP-induced cytostasis. These data pinpoint an unsuspected Netrin-1/UNC5B/integrin-αV/β5 axis as a critical effector of YAP tumor suppressor activity.

SIGNIFICANCE

Netrins are widely perceived as procancer proteins; however, we uncover an anticancer function for Netrin-1 and its receptor UNC5B.

Possible Role of miR-375-3p in Cervical Lymph Node Metastasis of Oral Squamous Cell Carcinoma

No clinically useful predictors of latent cervical lymph node metastasis (LNM) in early oral squamous cell carcinoma (OSCC) are available. In this study, we focused on the microRNAs (miRNAs) involved in the expression of numerous genes and explored those associated with latent cervical LNM in early OSCC (eOSCC). First, microarray and RT-PCR analyses revealed a significant downregulation of miR-375-3p expression in primary eOSCC tissues with latent cervical LNM. Next, we examined the effects of miR-375-3p mimics on the growth and migration of four human OSCC cell lines that do not express miR-375-3p. The overexpression of miR-375-3p significantly suppressed the cell proliferation and migration of human OSCC cells in vitro. Furthermore, miR-375-3p mimics markedly inhibited the subcutaneously xenografted human OSCC tumors. Finally, we found the genes involved in the PI3K-AKT pathway and cell migration as target gene candidates of miR-375-3p in human OSCC cells. These findings suggest that miR-375-3p functions as a tumor suppressive-miRNA in OSCC and may serve as a potential biomarker for the prediction of latent cervical LNM in eOSCC and a useful therapeutic target to suppress OSCC progression.

A plasma miRNA-based classifier for small cell lung cancer diagnosis

Introduction

Small cell lung cancer (SCLC) is characterized by poor prognosis and challenging diagnosis. Screening in high-risk smokers results in a reduction in lung cancer mortality, however, screening efforts are primarily focused on non-small cell lung cancer (NSCLC). SCLC diagnosis and surveillance remain significant challenges. The aberrant expression of circulating microRNAs (miRNAs/miRs) is reported in many tumors and can provide insights into the pathogenesis of tumor development and progression. Here, we conducted a comprehensive assessment of circulating miRNAs in SCLC with a goal of developing a miRNA-based classifier to assist in SCLC diagnoses.

Methods

We profiled deregulated circulating cell-free miRNAs in the plasma of SCLC patients. We tested selected miRNAs on a training cohort and created a classifier by integrating miRNA expression and patients' clinical data. Finally, we applied the classifier on a validation dataset.

Results

We determined that miR-375-3p can discriminate between SCLC and NSCLC patients, and between SCLC and Squamous Cell Carcinoma patients. Moreover, we found that a model comprising miR-375-3p, miR-320b, and miR-144-3p can be integrated with race and age to distinguish metastatic SCLC from a control group.

Discussion

This study proposes a miRNA-based biomarker classifier for SCLC that considers clinical demographics with specific cut offs to inform SCLC diagnosis.

The uprise of RNA biology in neuroendocrine neoplasms: altered splicing and RNA species unveil translational opportunities

Neuroendocrine neoplasms (NENs) comprise a highly heterogeneous group of tumors arising from the diffuse neuroendocrine system. NENs mainly originate in gastrointestinal, pancreatic, and pulmonary tissues, and despite being rare, show rising incidence. The molecular mechanisms underlying NEN development are still poorly understood, although recent studies are unveiling their genomic, epigenomic and transcriptomic landscapes. RNA was originally considered as an intermediary between DNA and protein. Today, compelling evidence underscores the regulatory relevance of RNA processing, while new RNA molecules emerge with key functional roles in core cell processes. Indeed, correct functioning of the interrelated complementary processes comprising RNA biology, its processing, transport, and surveillance, is essential to ensure adequate cell homeostasis, and its misfunction is related to cancer at multiple levels. This review is focused on the dysregulation of RNA biology in NENs. In particular, we survey alterations in the splicing process and available information implicating the main RNA species and processes in NENs pathology, including their role as biomarkers, and their functionality and targetability. Understanding how NENs precisely (mis)behave requires a profound knowledge at every layer of their heterogeneity, to help improve NEN management. RNA biology provides a wide spectrum of previously unexplored processes and molecules that open new avenues for NEN detection, classification and treatment. The current molecular biology era is rapidly evolving to facilitate a detailed comprehension of cancer biology and is enabling the arrival of personalized, predictive and precision medicine to rare tumors like NENs.

Deregulation of miR-375 Inhibits HOXA5 and Promotes Migration, Invasion, and Cell Proliferation in Breast Cancer

Breast cancer (BC) is a highly aggressive tumour and one of the women's leading causes of cancer-related deaths in worldwide. MiR-375 overexpressed in BC cells, and its biological relevance is largely unknown. Here in, we explored the function of miR-375 in BC. MicroRNA-375 targets were predicted by online target prediction tools and found that HOXA5 is one of the potential targets. MTT assay was employed to assess the effect of miR-375 on cell proliferation, where migration and invasion transwell assays were applied to detect cell migratory and invasive ability. Besides, relative expression of miR-375 and HOXA5 was measured in BC and HEK-293 cells, and its downstream gene target expressions were evaluated by qRT-PCR and western blot. In this study, we found that miR-375 expression was higher in BC cell lines than in the HEK-293 cell line, whereas HOXA5 expression was significantly lower. Our study showed that exogenous inhibition of miR-375 promoted HOXA5 expression; on the contrary, miR-375 mimics down-regulated HOXA5 expression level. Knockdown of miR-375 expression in BC cells reduces cell proliferation, migration, and invasion by inverse correlation expression of HOXA5. Our findings associated that miR-375 accelerated apoptosis evasion, proliferation, migration, and invasion by targeting HOXA5. In addition, nucleolin interferes in miR-375 biogenesis while silencing of nucleolin significantly reduced miR-375 expression and increased HOXA5 expression in BC. Thus, miR-375/HOXA5 axis may represent a potential therapeutic target for BC treatment.

Prognostic significance of YAP1 expression and its association with neuroendocrine markers in resected pulmonary large cell neuroendocrine carcinoma (LCNEC)

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It is the first study to determine the prognostic relevance of YAP1 in pulmonary LCNEC. And we found YAP1 is a prognostic factor for worse survival, especially for DFS.

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We investigated the relationship between YAP1 and NE markers (INSM1, DLL3, NeuroD1) and found that YAP1 expression was negatively correlated with INSM1 and DLL3, but not significantly correlated with NeuroD1.

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Our sample size is large and the clinical data is complete.

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The exploration of the prognostic mechanism of LCNEC is of great significance to its subtype classification and stratification of treatment and prognosis.

Background

YAP1 (Yes-associated protein 1), an important effector of the Hippo pathway, acts as an oncogene and is overexpressed in various malignant tumors. However, the function and expression pattern of YAP1 in pulmonary large cell neuroendocrine carcinoma (LCNEC) have not been systematically established. This study aimed to explore the relationship between YAP1 expression and neuroendocrine differentiation markers and their prognostic significance in LCNEC.

Materials and methods

YAP1 protein and neuroendocrine markers (INSM1, NeuroD1 and DLL3) expression were examined by immunohistochemical (IHC) staining in 80 resected pulmonary LCNEC cases. The possible association between these markers and clinicopathological features was evaluated and survival analyses were performed.

Results

YAP1 was highly expressed in 25% LCNECs (20/80) , especially at a relatively higher T stage (p = 0.015). YAP1 expression was negatively correlated with INSM1 (χ²=11.53, p = 0.001) and DLL3(χ²=8.55, p = 0.004), but not with NeuroD1 (p = 0.482). For survival analyses, YAP1 expression was associated with worse disease-free survival (DFS) and overall survival (OS) (median DFS: 13 months vs. not reached (NR), p = 0.0096; median OS: not reached, NR vs. NR, p = 0.038), and was an unfavorable prognostic factor for DFS (HR:3.285; 95%CI: 1.526-7.071, p = 0.002) and OS (HR: 2.864, 95% CI: 0.932-8.796, p = 0.066).

Conclusions

YAP1 was found to be conversely correlated with neuroendocrine markers and a prognostic factor for worse survival in resected LCNEC patients, and mechanisms need to be further investigated.

Intermittent Hypoxia Increased the Expression of DBH and PNMT in Neuroblastoma Cells via MicroRNA-375-Mediated Mechanism

Sleep apnea syndrome (SAS), characterized by recurrent episodes of oxygen desaturation and reoxygenation (intermittent hypoxia (IH)), is a risk factor for hypertension and insulin resistance. We report a correlation between IH and insulin resistance/diabetes. However, the reason why hypertension is induced by IH is elusive. Here, we investigated the effect of IH on the expression of catecholamine-metabolizing enzymes using an in vitro IH system. Human and mouse neuroblastoma cells (NB-1 and Neuro-2a) were exposed to IH or normoxia for 24 h. Real-time RT-PCR revealed that IH significantly increased the mRNA levels of dopamine β-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) in both NB-1 and Neuro-2a. Western blot showed that the expression of DBH and PNMT in the NB-1 cells was significantly increased by IH. Reporter assays revealed that promoter activities of DBH and PNMT were not increased by IH. The miR-375 level of IH-treated cells was significantly decreased relative to that of normoxia-treated cells. The IH-induced up-regulation of DBH and PNMT was abolished by the introduction of the miR-375 mimic, but not by the control RNA. These results indicate that IH stress increases levels of DBH and PNMT via the inhibition of miR-375-mediated mRNA degradation, potentially playing a role in the emergence of hypertension in SAS patients.

The Role of miRNA in the Pathophysiology of Neuroendocrine Tumors

Neuroendocrine tumors (NETs) represent a tumor group that is both rare and heterogeneous. Prognosis is largely determined by the tumor grading and the site of the primary tumor and metastases. Despite intensive research efforts, only modest advances in diagnostic and therapeutic approaches have been achieved in recent years. For patients with non-respectable tumor stages, prognosis is poor. In this context, the development of novel diagnostic tools for early detection of NETs and prediction of tumor response to therapy as well as estimation of the overall prognosis would greatly improve the clinical management of NETs. However, identification of novel diagnostic molecules is hampered by an inadequate understanding of the pathophysiology of neuroendocrine malignancies. It has recently been demonstrated that microRNA (miRNA), a family of small RNA molecules with an established role in the pathophysiology of quite different cancer entities, may also play a role as a biomarker. Here, we summarize the available knowledge on the role of miRNAs in the development of NET and highlight their potential use as serum-based biomarkers in the context of this disease. We discuss important challenges currently preventing their use in clinical routine and give an outlook on future directions of miRNA research in NET.