RasGRP3 controls cell proliferation and migration in papillary thyroid cancer by regulating the Akt-MDM2 pathway

Mdm2 requires Sprouty4 to regulate focal adhesion formation and metastasis independent of p53

Although the E3 ligase Mdm2 and its homologue and binding partner MdmX are the major regulators of the p53 tumor suppressor protein, it is now evident that Mdm2 and MdmX have multiple functions that do not involve p53. As one example, it is known that Mdm2 can regulate cell migration, although mechanistic insight into this function is still lacking. Here we show in cells lacking p53 expression that knockdown of Mdm2 or MdmX, as well as pharmacological inhibition of the Mdm2/MdmX complex, not only reduces cell migration and invasion, but also impairs cell spreading and focal adhesion formation. In addition, Mdm2 knockdown decreases metastasis in vivo. Interestingly, Mdm2 downregulates the expression of Sprouty4, which is required for the Mdm2 mediated effects on cell migration, focal adhesion formation and metastasis. Further, our findings indicate that Mdm2 dampening of Sprouty4 is a prerequisite for maintaining RhoA levels in the cancer cells that we have studied. Taken together we describe a molecular mechanism whereby the Mdm2/MdmX complex through Sprouty4 regulates cellular processes leading to increase metastatic capability independently of p53.

Ubiquitin-modifying enzymes in thyroid cancer：Mechanisms and functions

Thyroid cancer is the most common malignant tumor of the endocrine system, and evidence suggests that post-translational modifications (PTMs) and epigenetic alterations play an important role in its development. Recently, there has been increasing evidence linking dysregulation of ubiquitinating enzymes and deubiquitinases with thyroid cancer. This review aims to summarize our current understanding of the role of ubiquitination-modifying enzymes in thyroid cancer, including their regulation of oncogenic pathways and oncogenic proteins. The role of ubiquitination-modifying enzymes in thyroid cancer development and progression requires further study, which will provide new insights into thyroid cancer prevention, treatment and the development of novel agents.

The Analysis of Selected miRNAs and Target MDM2 Gene Expression in Oral Squamous Cell Carcinoma

MiRNAs could play an important role in tumorigenesis and progression. The oncoprotein MDM2 (murine double minute 2) was identified as a negative regulator of the tumour suppressor p53. This study aims to analyse the expression of the MDM2 target miRNA candidates (miR-3613-3p, miR-371b-5p and miR-3658) and the MDM2 gene in oral squamous cell carcinoma tumour and margin samples and their association with the selected socio-demographic and clinicopathological characteristics. The study group consisted of 50 patients. The miRNAs and MDM2 gene expression levels were assessed by qPCR. The expression analysis of the miRNAs showed the expression of only one of them, i.e., miR-3613-3p. We found no statistically significant differences in the miR-3613-3p expression in tumour samples compared to the margin samples. When analysing the effect of smoking on miR-3613-3p expression, we demonstrated a statistically significant difference between smokers and non-smokers. In addition, we showed an association between the miR-3613-3p expression level and some clinical parameters in tumour samples (T, N and G). Our study demonstrates that miR-3613-3p overexpression is involved in the tumour progression of OSCC. This indicates that miR-3613-3p possesses potential prognostic values.

Overarching roles of diacylglycerol signaling in cancer development and antitumor immunity

Diacylglycerol (DAG) is a lipid second messenger that is generated in response to extracellular stimuli and channels intracellular signals that affect mammalian cell proliferation, survival, and motility. DAG exerts a myriad of biological functions through protein kinase C (PKC) and other effectors, such as protein kinase D (PKD) isozymes and small GTPase-regulating proteins (such as RasGRPs). Imbalances in the fine-tuned homeostasis between DAG generation by phospholipase C (PLC) enzymes and termination by DAG kinases (DGKs), as well as dysregulation in the activity or abundance of DAG effectors, have been widely associated with tumor initiation, progression, and metastasis. DAG is also a key orchestrator of T cell function and thus plays a major role in tumor immunosurveillance. In addition, DAG pathways shape the tumor ecosystem by arbitrating the complex, dynamic interaction between cancer cells and the immune landscape, hence representing powerful modifiers of immune checkpoint and adoptive T cell-directed immunotherapy. Exploiting the wide spectrum of DAG signals from an integrated perspective could underscore meaningful advances in targeted cancer therapy.

Recurring Translocations in Barrett's Esophageal Adenocarcinoma

Barrett's esophagus (BE) is a premalignant metaplasia in patients with chronic gastroesophageal reflux disease (GERD). BE can progress to esophageal adenocarcinoma (EA) with less than 15% 5-year survival. Chromosomal aneuploidy, deletions, and duplication are early events in BE progression to EA, but reliable diagnostic assays to detect chromosomal markers in premalignant stages of EA arising from BE are lacking. Previously, we investigated chromosomal changes in an in vitro model of acid and bile exposure-induced Barrett's epithelial carcinogenesis (BEC). In addition to detecting changes already known to occur in BE and EA, we also reported a novel recurring chromosomal translocation t(10:16) in the BE cells at an earlier time point before they undergo malignant transformation. In this study, we refine the chromosomal event with the help of fluorescence microscopy techniques as a three-way translocation between chromosomes 2, 10, and 16, t(2:10;16) (p22;q22;q22). We also designed an exclusive fluorescent in situ hybridization for esophageal adenocarcinoma (FISH-EA) assay that detects these chromosomal breakpoints and fusions. We validate the feasibility of the FISH-EA assay to objectively detect these chromosome events in primary tissues by confirming the presence of one of the fusions in paraffin-embedded formalin-fixed human EA tumors. Clinical validation in a larger cohort of BE progressors and non-progressors will confirm the specificity and sensitivity of the FISH-EA assay in identifying malignant potential in the early stages of EA.

CircTP53 promotes the proliferation of thyroid cancer via targeting miR-1233-3p/MDM2 axis

BACKGROUND

Follicular cells give rise to thyroid cancer. Worldwide thyroid cancer incidence continues to rise in recent decades but the mortality rate remains at a stable level. The discovery of novel molecular mechanisms in the pathogenesis of thyroid cancer will promote new diagnostic or therapeutic strategies. Circular RNA (circRNA) is a type of noncoding RNA which is characterized by the covalently closed loop and non-protein coding capacity. The abnormal expression of circRNAs is an important part during the pathogenesis and development of thyroid cancer. CircTP53 is a novel circRNA, and we aimed to investigate its function in the pathogenesis of thyroid cancer and to further demonstrate the underlying molecular mechanism.

METHODS

The levels of circTP53, miR-1233-3p, and other relative mRNA were analyzed by qRT-PCR. Protein levels were shown by Western blot. RNA-pulldown assay and luciferase assay were employed to examine the interaction between circTP53 and miR-1233-3p. Cell proliferation was analyzed by the MTT assay.

RESULTS

CircTP53 was a circRNA highly expressed in thyroid cancer tissues. CircTP53 promoted cell proliferation and cell viability of TPC-1 cells. Knockdown of circTP53 inhibited the expression of Mouse double minute 2 (MDM2) and increased the protein level of p53. CircTP53 acted as a target of miR-1233-3p to increase MDM2 expression. p53 expression in thyroid cancer tissue exhibited a negative correlation with circTP53 expression.

CONCLUSION

In thyroid cancer, overexpressed circTP53 decreased the protein level of p53 via targeting miR-1233-3p/MDM2 axis and promoted cancer cell proliferation.

Gentiopicroside Inhibits Cell Growth and Migration on Cervical Cancer via the Reciprocal MAPK/Akt Signaling Pathways

Cervical cancer (CC) is a common gynecological malignancy and represents a major global health challenge. Chemotherapeutic agents are commonly applied in treatment of CC, while along various adverse effects and chemotherapy resistance. As an iridoid glycoside compound, gentiopicroside (GPS) possesses the characteristic of the better availability and lower toxicity effect on cancer treatment. In the present study, we investigated that GPS exhibited the anticancer effect on HeLa cells through the inhibition of cell growth, induced apoptosis, cycle arrest, and suppressed migration. Furthermore, the possible mechanism or the targets of GPS was also clarified. The results revealed that GPS exerted an anti-proliferation effect in a dose- and time-dependent manner in HeLa cells, in contrast, with the less inhibiting proliferation effects on normal cell line (HUVEC). Moreover, GPS arrested cells at G2/M phase and induced apoptosis through mitochondrial apoptotic pathway. More significantly, GPS dramatically inhibited the migration of HeLa cells and regulated the matrix metalloproteinase expression through the MAPK and Akt signaling pathways, of which MAPK1 was an underlying target in GPS against HeLa cells.

FOXA1 Suppresses the Growth, Migration, and Invasion of Nasopharyngeal Carcinoma Cells through Repressing miR-100-5p and miR-125b-5p

Background: Nasopharyngeal carcinoma (NPC) is a unique subtype of head and neck cancer, within highest incidence in South China and southeastern Asia but rare in other regions worldwide. FOXA1 is a pioneer factor implicated in various human malignancies. Downregulation of FOXA1 promotes NPC cells proliferation, invasiveness in vitro and tumorigenicity in vivo. However, it is remain elusive to determine whether microRNAs (miRNAs) regulated by FOXA1 contribute to NPC progression.

Methods: In this study, differentially expressed miRNAs and mRNAs induced by FOXA1 expression were determined by microarray. Integrative miRNA-mRNA regulatory networks mediated by FOXA1 in NPC were established. The expressions of differentially expressed miRNAs in NPC cells were measured by quantitative reverse-transcription PCR. Cell viability was determined by CCK-8 assays. Cell migration and invasiveness were measured by Transwell assays. The correlation between miRNAs and its target mRNAs was analyzed.

Results: FOXA1 suppressed the expression of miR-100-5p and miR-125b-5p in NPC cells. Silencing either miR-100-5p or miR-125b-5p inhibited the malignant behaviors of NPC cells, whereas re-expression of miR-100-5p or miR-125b-5p restored the malignancy of NPC cells repressed by FOXA1. Mechanistically, miR-100-5p or miR-125b-5p suppressed RASGRP3 or FOXN3 expression respectively via direct binding to its 3'-UTR. Furthermore, we demonstrated that FOXA1 induced RASGRP3 or FOXN3 expression via inhibiting miR-100-5p or miR-125b-5p. Upregulation of RASGRP3 or FOXN3 contributed to inhibition of NPC by FOXA1. We also demonstrated that the mRNA levels of RASGRP3 and FOXN3 are positively correlated with FOXA1.

Conclusion: Our study provided evidence the first time that FOXA1 suppresses NPC cells via downregulation of miR-100-5p or miR-125b-5p.

Long non-coding RNA XIST expedites lung adenocarcinoma progression through upregulating MDM2 expression via binding to miR-363-3p

Background

Lung adenocarcinoma (LAD) is a highly aggressive malignant tumor which threatens the health and life of the population. Long non‐coding RNA X‐inactive specific transcript (XIST) and mouse double minute clone 2 (MDM2) are connected with the tumorigenesis of LAD. Nevertheless, whether MDM2 is regulated by XIST has not previously been reported in LAD.

Methods

Quantitative real‐time polymerase chain reaction (qRT‐PCR) was employed to detect the expression of XIST, microRNA‐363‐3p (miR‐363‐3p) and MDM2 in LAD tissues and cells. The proliferation, migration, invasion and apoptosis of LAD cells were determined by 3‐(4, 5‐dimethylthiazol‐2‐YI)‐2, 5‐diphenyltetrazolium bromide (MTT), transwell or flow cytometry assay, respectively. MDM2 protein level was detected using western blot analysis. Dual‐luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pulldown assay were performed to determine the interaction among XIST, miR‐363‐3p and MDM2. A xenograft tumor model was constructed to validate the effect of XIST on LAD cells in vivo.

Results

We found that XIST and MDM2 were remarkably elevated while miR‐363‐3p was reduced in LAD tissues and cells. Both XIST and MDM2 downregulation restrained proliferation, migration and invasion, and facilitated apoptosis of LAD cells in vitro. Importantly, XIST bound to miR‐363‐3p to modulate MDM2 expression in LAD cells. Moreover, miR‐363‐3p knockdown or MDM2 elevation reversed the effects of XIST downregulation on the proliferation, migration, invasion and apoptosis of LAD cells. Furthermore, XIST knockdown constrained tumor growth on LAD cells in vivo.

Conclusions

XIST knockdown repressed proliferation, migration and invasion, and accelerated apoptosis of LAD cells by downregulating MDM2 expression via binding to miR‐363‐3p.

Key points

Significant findings of the study

XIST and MDM2 were abnormally enhanced in LAD tissues and cells.

Both downregulation of XIST and MDM2 repressed proliferation, migration and invasion, and boosted apoptosis of LAD cells in vitro.

XIST bound to miR‐363‐3p to regulate MDM2 expression in LAD cells.

Downregulation of XIST impeded tumor growth on LAD cells in vivo.

What this study adds

This study confirmed that XIST was a potential target for inhibiting the development of LAD, and affords a possible strategy for the treatment of LAD in the future.

KLF5 promotes the tumorigenesis and metastatic potential of thyroid cancer cells through the NF-κB signaling pathway

The purpose of the present study was to identify the potential function of Kruppel-like factor 5 (KLF5) in thyroid cancer and investigate the underlying mechanisms. The protein levels of KLF5 in 98 thyroid cancer tissues were analyzed using an immunohistochemistry assay. SW579 cells transfected with small interfering RNA against KLF5 and B-CPAP cells transfected with KLF5 expressing vectors were used for functional studies. Western blot analysis, immunofluorescence and co-immunoprecipitation assays were used to investigate the mechanisms of KLF5. In vivo tumorigenicity was assessed using a subcutaneous xenograft experiment. The results revealed that KLF5 was highly expressed in thyroid cancer tissues and associated with lymph node metastasis. Knockdown of KLF5 in SW579 cells suppressed proliferation, anchorage-independent growth, migration and invasion in vitro, while the overexpression of KLF5 resulted in opposite effects in B-CPAP cells. Mechanistically, it was demonstrated that KLF5 promoted the cytoplasm-nuclear translocation of nuclear factor-κB. Additionally, it was revealed that insufficient F-box/WD repeat-containing protein 7 expression may be responsible for the dysfunction of KLF5 in thyroid cancer. These results revealed that KLF5 promotes the tumorigenesis and metastasis of thyroid cancer cells and may be a potential therapeutic target in patients with thyroid cancer.

Myofibrillogenesis regulator 1 (MR-1): a potential therapeutic target for cancer and PNKD

Human myofibrillogenesis regulator 1 (MR-1) is a functional gene also known as paroxysmal nonkinesigenic dyskinesia (PNKD). It is localised on human chromosome 2q35 and three different isomers, MR-1L, MR-1M and MR-1S, are formed by alternative splicing. MR-1S promotes cardiac hypertrophy and is closely related to cancer. MR-1S is overexpressed in haematologic and solid malignancies, such as hepatoma, breast cancer and chronic myelogenous leukaemia. MR-1S causes disordered cell differentiation, initiates malignant transformation and accelerates metastasis. MR-1S directly phosphorylates and activates the MEK-ERK-RSK pathway to accelerate cancer growth and facilitates metastasis by activating the MLC2-FAK-AKT pathway. Silencing MR-1 inhibits cancer cell proliferation and metastasis. MR-1S causes disordered cell differentiation, initiates malignant transformation and accelerates metastasis. MR-1 interacts with eukaryotic translation initiation factors and MRIP-1, which contains Ras GTPase, PH and zinc-containing ArfGap domains, as well as three ankyrin repeats. Mutations in the N-terminal region of MR-1L and MR-1S are the main causes of PNKD (a hereditary disease characterised by paroxysmal dystonic choreoathetosis) and targeting the mutated protein could provide symptomatic relief. These findings provide compelling evidence that MR-1 might be a diagnostic marker and therapeutic target for solid tumours, myelogenous leukaemia and PNKD.