REGγ potentiates TGF-β/Smad signal dependent epithelial-mesenchymal transition in thyroid cancer cells

PA28γ, the ring that makes tumors invisible to the immune system?

PA28γ is a proteasomal interactor whose main and most known function is to stimulate the hydrolytic activity of the 20 S proteasome independently of ubiquitin and ATP. Unlike its two paralogues, PA28α and PA28β, PA28γ is largely present in the nuclear compartment and plays pivotal functions in important pathways such as cellular division, apoptosis, neoplastic transformation, chromatin structure and organization, fertility, lipid metabolism, and DNA repair mechanisms. Although it is known that a substantial fraction of PA28γ is found in the cell in a free form (i.e. not associated with 20 S), almost all of the studies so far have focused on its ability to modulate proteasomal enzymatic activities. In this respect, the ability of PA28γ to strongly stimulate degradation of proteins, especially if intrinsically disordered and therefore devoid of three-dimensional tightly folded structure, appears to be the main molecular mechanism underlying its multiple biological effects. Initial studies, conducted more than 20 years ago, came to the conclusion that among the many biological functions of PA28γ, the immunological ones were rather limited and circumscribed. In this review, we focus on recent evidence showing that PA28γ fulfills significant functions in cell-mediated acquired immunity, with a particular role in attenuating MHC class I antigen presentation, especially in relation to neoplastic transformation and autoimmune diseases.

MicroRNA-130a-3p impedes the progression of papillary thyroid carcinoma through downregulation of KPNB1 by targeting PSME3

BACKGROUND

Papillary thyroid carcinoma (PTC) is the main type of thyroid cancer (THCA). Despite the good prognosis, some PTC patients may deteriorate into more aggressive disease, leading to poor survival. Our study aimed to explore the role of microRNA (miR)-130a-3p in regulating PTC.

METHODS

After transfection with miR-130a-3p-mimic, OE-PSME3, or miR-130a-3p-mimic + OE-KPNB1 in PTC cells (TPC-1), CCK-8, Transwell, scratch, and flow cytometry experiments were performed to analyze TPC-1 cell proliferation, invasion, migration, and apoptosis. Western blotting was used to detect proliferation or invasion-related protein markers (PCNA, E-cadherin, and N-cadherin). The RNA22 database, dual-luciferase reporter assay, and RNA pull-down assay were applied for the prediction and verification of the binding site between miR-130a-3p and PSME3. Pan-cancer software identified a positive correlation between PSME3 and KPNB1 in THCA. Co-immunoprecipitation was utilized to verify the interaction of PSME3 with KPNB1. Nude mice were transplanted with TPC-1 cells overexpressing miR-130a-3p. The tumors were isolated for detection of the expression of miR-130a-3p, PSME3, KPNB1, Ki-67, and CD31.

RESULTS

miR-130a-3p was lowly expressed in PTC cell lines. Upregulation of miR-130a-3p repressed the expression of PSME3 and KPNB1 and reduced the malignancy of TPC-1 cells in vitro, shown by inhibited cell proliferation, invasion, migration, and the expression of PCNA and N-cadherin. Also, overexpressed miR-130a-3p inhibited the growth of xenograft tumors in nude mice. miR-130a-3p bound to PSME3 which interacted with KPNB1.

CONCLUSION

miR-130a-3p impedes the progression of PTC by downregulating PSME3/KPNB1.

circFANCA accelerates the malignant process of OSCC by modulating miR-34a/PA28γ signaling

OBJECTIVES

To investigate the upstream regulatory molecules of proteasomal activator 28γ (PA28γ), and explore its specific regulatory mechanism and potential clinical significance in OSCC.

MATERIALS AND METHODS

qPCR was used to examine miR-34a, circFANCA and PSME3 expression. Western blotting was adopted to detect PA28γ expression. Transwell experiments were conducted to evaluate OSCC cell migration and invasion ability. FISH was used to evaluate the subcellular localization of circFANCA and miR-34a, and RNA pull-down verified the interaction between them. The expression of circFANCA and miR-34a in clinical cohorts was assessed by ISH, and the results were subjected to survival analysis using Kaplan-Meier analysis.

RESULTS

Here, we proved that miR-34a expression is lower in highly aggressive OSCC tissues and cell lines. Notably, miR-34a can downregulate PA28γ expression and inhibit OSCC invasion and migration. Next, we confirmed that circFANCA promoted OSCC cell metastatic ability by sponging miR-34a. Importantly, interfering with miR-34a rescued the malignant progression of OSCC induced by silencing circFANCA. Finally, clinical data showed lower miR-34a expression and higher circFANCA expression were associated with poor prognosis in OSCC patients.

CONCLUSION

The circFANCA/miR-34a/PA28γ axis facilitates the metastasis of OSCC, and circFANCA and miR-34a have potential to serve as prognostic markers for OSCC patients.

E-cadherin on epithelial-mesenchymal transition in thyroid cancer

Thyroid carcinoma is a common malignant tumor of endocrine system and head and neck. Recurrence, metastasis and high malignant expression after routine treatment are serious clinical problems, so it is of great significance to explore its mechanism and find action targets. Epithelial-mesenchymal transition (EMT) is associated with tumor malignancy and invasion. One key change in tumour EMT is low expression of E-cadherin. Therefore, this article reviews the expression of E-cadherin in thyroid cancers (TC), discuss the potential mechanisms involved, and outline opportunities to exploit E-cadherin on regulating the occurrence of EMT as a critical factor in cancer therapeutics.

PA28γ: New Insights on an Ancient Proteasome Activator

PA28 (also known as 11S, REG or PSME) is a family of proteasome regulators whose members are widely present in many of the eukaryotic supergroups. In jawed vertebrates they are represented by three paralogs, PA28α, PA28β, and PA28γ, which assemble as heptameric hetero (PA28αβ) or homo (PA28γ) rings on one or both extremities of the 20S proteasome cylindrical structure. While they share high sequence and structural similarities, the three isoforms significantly differ in terms of their biochemical and biological properties. In fact, PA28α and PA28β seem to have appeared more recently and to have evolved very rapidly to perform new functions that are specifically aimed at optimizing the process of MHC class I antigen presentation. In line with this, PA28αβ favors release of peptide products by proteasomes and is particularly suited to support adaptive immune responses without, however, affecting hydrolysis rates of protein substrates. On the contrary, PA28γ seems to be a slow-evolving gene that is most similar to the common ancestor of the PA28 activators family, and very likely retains its original functions. Notably, PA28γ has a prevalent nuclear localization and is involved in the regulation of several essential cellular processes including cell growth and proliferation, apoptosis, chromatin structure and organization, and response to DNA damage. In striking contrast with the activity of PA28αβ, most of these diverse biological functions of PA28γ seem to depend on its ability to markedly enhance degradation rates of regulatory protein by 20S proteasome. The present review will focus on the molecular mechanisms and biochemical properties of PA28γ, which are likely to account for its various and complex biological functions and highlight the common features with the PA28αβ paralog.

EIF5A2 Is Highly Expressed in Anaplastic Thyroid Carcinoma and Is Associated With Tumor Growth by Modulating TGF- Signals

Anaplastic thyroid carcinoma (ATC) is resistant to standard therapies and has no effective treatment. Eukaryotic translation initiation factor 5A2 (EIF5A2) has shown to be upregulated in many malignant tumors and proposed to be a critical gene involved in tumor metastasis. In this study, we aimed to investigate the expression status of EIF5A2 in human ATC tissues and to study the role and mechanisms of EIF5A2 in ATC tumorigenesis in vitro and in vivo. Expression of EIF5A2 protein was analyzed in paraffin-embedded human ATC tissues and adjacent nontumorous tissues (ANCT) (n=24) by immunochemistry. Expressions of EIF5A2 mRNA and protein were analyzed in fresh-matched ATC and ANCT (n=23) and ATC cell lines by real-time polymerase chain reaction (PCR) and Western blotting. The effect of targeting EIF5A2 with short hairpin RNA (shRNA) or EIF5A2 overexpression on the ATC tumorigenesis and TGF-/Smad2/3 signals in vitro and in vivo was investigated. Expression of EIF5A2 was significantly upregulated in ATC tissues and cell lines compared with ANCT and normal follicular epithelial cell line. Functional studies found that targeting EIF5A2 induced SW1736 cell death in vitro and in vivo, followed by significantly downregulated phosphorylation of Smad2/3 (p-Smad2/3) in SW1736 cells at the protein level. Ectopic expression of EIF5A2 could promote 8505C cell growth in vitro and in vivo, followed by significantly upregulated p-Smad3 at the protein level. Recombinant human TGF-1 (hTGF-1) treatment decreased the antiproliferative activity of the EIF5A2 downexpressing 8505C cells through reversing pSmad2/3. Using the specific inhibitor SB431542 to block TGF- pathway or Smad3 siRNA to knock down Smad3 increased the antiproliferative activity of the EIF5A2-overexpressing 8505C cells through inhibiting pSmad2/3. Our findings indicated that EIF5A2 controled cell growth in ATC cells, and EIF5A/TGF-/Smad2/3 signal may be a potential therapeutic target for ATC treatment.

Role of oncogenic REGγ in cancer

Cancer is a critical global health-care problem with limited therapeutic options. Since cancers are life-threatening illnesses, the identification of a promising oncotarget and its clinical correlates are relevant. Mounting evidence has emerged indicating that REG gamma (REGγ), a member of the 11S proteasome activators, plays a pivotal role in the development of multiple human cancers. However, an elaborate summary on the association between REGγ and cancer is still lacking. In this Review, we discuss how REGγ, through its ATP- and ubiquitin-independent manners, represents a promising cancer biomarker and therapeutic oncotarget for multiple human cancers. Aberrant REGγ expression closely associated with tumorigenesis attributes to its biological functions for controlling and regulating cell cycle, proliferation, migration, invasion, angiogenesis, and metastasis of the cancer cells by degrading proteins of cytosol and nucleus in the eukaryotic cells. REGγ serves as a molecular switch to activate multifarious oncogenic signaling pathways, such as MAPK/p38, TGF-β/Smad, and Wnt/β-catenin. The review describes that targeting REGγ may provide new diagnostic and therapeutic applications in cancer.

EVI5 is an oncogene that regulates the proliferation and metastasis of NSCLC cells

Background

The Ecotropic viral integration site 5 (EVI5), an important protein in regulating cell cycle, cytokinesis and cellular membrane traffic, functions as a stabilizing factor maintaining anaphase-promoting complex/cyclosome (APC/C) inhibitor Emi1 in S/G2 phase. However, the mechanism by which EVI5 promotes malignant transformation of non-small cell lung cancer (NSCLC) remains unknown. In the present study, we addressed the role of EVI5 in NSCLC by regulating tumor growth, migration and invasion.

Methods

The expression levels of EVI5 and miR-486-5p in NSCLC tissues and cells were measured by real-time PCR. Meanwhile, EVI5 and its associated protein expression were analyzed by western blot and co-immunoprecipitation assay. Flow cytometry was performed to determine cell proliferation and apoptosis. CCK-8 and clonogenic assays were used to analyze cell viability. Wound healing, transwell migration and matrigel invasion assays were utilized to assess the motility of tumor cells. To investigate the role of EVI5 in vivo, lung carcinoma xenograft mouse model was applied..

Results

EVI5 was upregulated in NSCLC tissues and cell lines when compared with that in normal tissues and cell line. Knockdown of EVI5 in vitro inhibited tumor cell proliferation, migration and invasion in NSCLC cells. Further, inoculation of EVI5-deficient tumor cells into nude mice suppressed tumor proliferation and metastasis compared to control mice inoculated with unmanipulated tumor cells. These data indicated that EVI5 promote the proliferation of NSCLC cells which was consistent with our previous results. Additionally, we showed that EVI5 was directly regulated by miR-486-5p, and miR-486-5p-EVI5 axis affected the NSCLC migration and invasion through TGF-β/Smad signaling pathway by interacting with TGF-β receptor II and TGF-β receptor I.

Conclusions

Based on these results, we demonstrated a new post-transcriptional mechanism of EVI5 regulation via miR-486-5p and the protumoral function of EVI5 in NSCLC by interacting with Emi1 and/or TGF-β receptors, which provides a new insight into the targeted therapy of NSCLC.

Dexamethasone Inhibits Spheroid Formation of Thyroid Cancer Cells Exposed to Simulated Microgravity

Detachment and the formation of spheroids under microgravity conditions can be observed with various types of intrinsically adherent human cells. In particular, for cancer cells this process mimics metastasis and may provide insights into cancer biology and progression that can be used to identify new drug/target combinations for future therapies. By using the synthetic glucocorticoid dexamethasone (DEX), we were able to suppress spheroid formation in a culture of follicular thyroid cancer (FTC)-133 cells that were exposed to altered gravity conditions on a random positioning machine. DEX inhibited the growth of three-dimensional cell aggregates in a dose-dependent manner. In the first approach, we analyzed the expression of several factors that are known to be involved in key processes of cancer progression such as autocrine signaling, proliferation, epithelial–mesenchymal transition, and anoikis. Wnt/β-catenin signaling and expression patterns of important genes in cancer cell growth and survival, which were further suggested to play a role in three-dimensional aggregation, such as NFKB2, VEGFA, CTGF, CAV1, BCL2(L1), or SNAI1, were clearly affected by DEX. Our data suggest the presence of a more complex regulation network of tumor spheroid formation involving additional signal pathways or individual key players that are also influenced by DEX.

LncRNA-ATB Promotes the Tumorigenesis of Ovarian Cancer via Targeting miR-204-3p

Background

Ovarian cancer ranks fifth among the most prevalent cancer type in females all over the world. It is the second most frequent malignant tumor which accounts for 3% of cancer in females. Therefore, to explore the mechanism of carcinogenesis in ovarian cancer is important to develop new treatment methods. It has been previously found that lncRNA-ATB could promote the tumorigenesis of malignant tumors. However, the role of lncRNA-ATB during the progression of ovarian cancer remains unclear.

Methods

Gene expressions in tissues or cells were detected by using qRT-PCR. Western blot was performed to investigate the protein expressions in ovarian cancer cells. Cell apoptosis was tested by flow cytometry. Moreover, the correction between lncRNA-ATB and miR-204-3p was examined by Dual-luciferase reporter assay and RNA pulldown. Cell proliferation and invasion were detected by CCK-8, Ki-67 staining and transwell assay, respectively. Finally, xenograft mice model was established to confirm the result of in vitro experiments.

Results

LncRNA-ATB silencing significantly inhibited the proliferation and induced apoptosis of ovarian cancer cells. In addition, luciferase activity suggested that lncRNA-ATB negatively regulated miR-204-3p in ovarian cancer. Besides, Nidogen 1 (NID1) was the direct target of miR-204-3p. Overexpression of NID1 could notably reverse the inhibitory effect of lncRNA-ATB knockdown on the progression of ovarian cancer. Finally, lncRNA-ATB silencing notably attenuated the severity of ovarian cancer in vivo.

Conclusion

Downregulation of lncRNA-ATB significantly inhibited the tumorigenesis of ovarian cancer in vitro and in vivo, which may serve as a potential novel target for the treatment of ovarian cancer.

OTUD6B-AS1 Inhibits Viability, Migration, and Invasion of Thyroid Carcinoma by Targeting miR-183-5p and miR-21

Background: The long noncoding RNA (lncRNA) functions as a regulator of initiation, progression, and metastasis of thyroid carcinomas. lncRNA OTUD6B antisense RNA 1 (OTUD6B-AS1) is a tumor-suppressive noncoding RNA in clear cell renal cell carcinoma. The role of OTUD6B-AS1 in thyroid carcinomas has not been reported yet. We aim to investigate the expression and biological functions of OTUD6B-AS1 in thyroid carcinomas. Methods: The expression level of OTUD6B-AS1 was measured in 60 paired human thyroid carcinoma tissues and corresponding adjacent normal thyroid tissues. The correlations between the OTUD6B-AS1 expression levels and clinicopathological features were evaluated using the Mann-Whitney test. The effects of OTUD6B-AS1 on thyroid carcinoma cells were determined via the MTT and transwell assays. The potential targets of OTUD6B-AS1 were screened using the online programs OncomiR and StarBase 3.0, and the LncBase Predicted v.2. Luciferase reporter assay was used to confirm the interactions between OTUD6B-AS1 and its potential targets. Results: OTUD6B-AS1 was downregulated in thyroid carcinoma tissue samples. The expression of OTUD6B-AS1 correlated with tumor size, clinical stage, and lymphatic metastasis of thyroid carcinoma. Overexpression of OTUD6B-AS1 significantly decreased the viability, migration, and invasion of thyroid carcinoma cells. Online programs predicted miR-183-5p and miR-21 as potential targets of OTUD6B-AS1. Luciferase reporter assays showed miR-183-5p and miR-21 bound to OTUD6B-AS1. Moreover, overexpression of miR-183-5p and miR-21 compromised the inhibitory effects of OTUD6B-AS1 on viability, migration, and invasion of thyroid carcinoma cells. Conclusions: Taken together, our findings present in vitro evidence of lncRNA OTUD6B-AS1 as a tumor suppressor in thyroid carcinomas. OTUD6B-AS1 inhibits viability, migration, and invasion of thyroid carcinoma by targeting miR-183-5p and miR-21.