MicroRNA‑542‑3p represses OTUB1 expression to inhibit migration and invasion of esophageal cancer cells

Emerging roles of deubiquitinating enzymes in actin cytoskeleton and tumor metastasis

BACKGROUND

Metastasis accounts for the majority of cancer-related deaths. Actin dynamics and actin-based cell migration and invasion are important factors in cancer metastasis. Metastasis is characterized by actin polymerization and depolymerization, which are precisely regulated by molecular changes involving a plethora of actin regulators, including actin-binding proteins (ABPs) and signalling pathways, that enable cancer cell dissemination from the primary tumour. Research on deubiquitinating enzymes (DUBs) has revealed their vital roles in actin dynamics and actin-based migration and invasion during cancer metastasis.

CONCLUSION

Here, we review how DUBs drive tumour metastasis by participating in actin rearrangement and actin-based migration and invasion. We summarize the well-characterized and essential actin cytoskeleton signalling molecules related to DUBs, including Rho GTPases, Src kinases, and ABPs such as cofilin and cortactin. Other DUBs that modulate actin-based migration signalling pathways are also discussed. Finally, we discuss and address therapeutic opportunities and ongoing challenges related to DUBs with respect to actin dynamics.

OTUB1 Promotes Glioblastoma Growth by Inhibiting the JAK2/STAT1 Signaling Pathway

Background: OTUB1, an essential deubiquitinating enzyme, is upregulated in various types of cancer. Previous studies have shown that OTUB1 may be an oncogene in glioblastoma multiforme (GBM), but its specific regulatory mechanism remains unclear. This study aimed to investigate the mechanism by which OTUB1 and the JAK2/STAT1 signaling pathway co-regulate the growth of GBM. Methods: Using bioinformatics, GBM tissues, and cells, we evaluated the expression and clinical significance of OTUB1 in GBM. Subsequently, we explored the regulatory mechanisms of OTUB1 on malignant behaviors in GBM in vitro and in vivo. In addition, we added the JAK2 inhibitor AZD1480 to explore the regulation of OTUB1 for JAK2/STAT1 pathway in GBM. Results: We found that OTUB1 expression was upregulated in GBM. Silencing OTUB1 promotes apoptosis and cell cycle arrest at G1 phase, inhibiting cell proliferation. Moreover, OTUB1 knockdown effectively inhibited the invasion and migration of GBM cells, and the opposite phenomenon occurred with overexpression. In vivo experiments revealed that OTUB1 knockdown inhibited tumor growth, further emphasizing its crucial role in GBM progression. Mechanistically, we found that OTUB1 was negatively correlated with the JAK2/STAT1 pathway in GBM. The addition of the JAK2 inhibitor AZD1480 significantly reversed the effects of silencing OTUB1 on GBM. Conclusion: Our study reveals a novel mechanism by which OTUB1 inhibits the JAK2/STAT1 signaling pathway. This contributes to a better understanding of OTUB1's role in GBM and provides a potential avenue for targeted therapeutic intervention.

OTUB1/NDUFS2 axis promotes pancreatic tumorigenesis through protecting against mitochondrial cell death

Pancreatic cancer is one of the most fatal cancers in the world. A growing number of studies have begun to demonstrate that mitochondria play a key role in tumorigenesis. Our previous study reveals that NDUFS2 (NADH: ubiquinone oxidoreductase core subunit S2), a core subunit of the mitochondrial respiratory chain complex I, is upregulated in Pancreatic adenocarcinoma (PAAD). However, its role in the development of PAAD remains unknown. Here, we showed that NDUFS2 played a critical role in the survival, proliferation and migration of pancreatic cancer cells by inhibiting mitochondrial cell death. Additionally, protein mass spectrometry indicated that the NDUFS2 was interacted with a deubiquitinase, OTUB1. Overexpression of OTUB1 increased NDUFS2 expression at the protein level, while knockdown of OTUB1 restored the effects in vitro. Accordingly, overexpression and knockdown of OTUB1 phenocopied those of NDUFS2 in pancreatic cancer cells, respectively. Mechanically, NDUFS2 was deubiquitinated by OTUB1 via K48-linked polyubiquitin chains, resulted in an elevated protein stability of NDUFS2. Moreover, the growth of OTUB1-overexpressed pancreatic cancer xenograft tumor was promoted in vivo, while the OTUB1-silenced pancreatic cancer xenograft tumor was inhibited in vivo. In conclusion, we revealed that OTUB1 increased the stability of NDUFS2 in PAAD by deubiquitylation and this axis plays a pivotal role in pancreatic cancer tumorigenesis and development.

MicroRNAs: A novel signature in the metastasis of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a malignant epithelial tumor, characterized by squamous cell differentiation, it is the sixth leading cause of cancer-related deaths globally. The increased mortality rate of ESCC patients is predominantly due to the advanced stage of the disease when discovered, coupled with higher risk of metastasis, which is an exceedingly malignant characteristic of cancer, frequently leading to a high mortality rate. Unfortunately, there is currently no specific and effective marker to predict and treat metastasis in ESCC. MicroRNAs (miRNAs) are a class of small non-coding RNA molecules, approximately 22 nucleotides in length. miRNAs are vital in modulating gene expression and serve pivotal regulatory roles in the occurrence, progression, and prognosis of cancer. Here, we have examined the literature to highlight the intimate correlations between miRNAs and ESCC metastasis, and show that ESCC metastasis is predominantly regulated or regulated by genetic and epigenetic factors. This review proposes a potential role for miRNAs as diagnostic and therapeutic biomarkers for metastasis in ESCC metastasis, with the ultimate aim of reducing the mortality rate among patients with ESCC.

OTUB1-mediated inhibition of ubiquitination: a growing list of effectors, multiplex mechanisms, and versatile functions

Protein ubiquitination plays a pivotal role in protein homeostasis. Ubiquitination may regulate the stability, activity, protein-protein interaction, and localization of a protein. Ubiquitination is subject to regulation by two groups of counteracting enzymes, the E3 ubiquitin ligases and deubiquitinases. Consistently, deubiquitinases are involved in essentially all biological processes. OTUB1, an OTU-family deubiquitinase, is a critical regulator of development, cancer, DNA damage response, and immune response. OTUB1 antagonizes the ubiquitination of a wide-spectrum of proteins through at least two different mechanisms. Besides direct deubiquitination, OTUB1 can also inhibit ubiquitination by non-canonically blocking ubiquitin transfer from certain ubiquitin-conjugases (E2). In this review, we start with a general background of protein ubiquitination and deubiquitination. Next, we introduce the basic characteristics of OTUB1 and then elaborate on the updated biological functions of OTUB1. Afterwards, we discuss potential mechanisms underlying the versatility and specificity of OTUB1 functions. In the end, we discuss the perspective that OTUB1 can be a potential therapeutic target for cancer.

Circ-FNDC3B Functions as an Oncogenic Factor in Esophageal Squamous Cell Carcinoma via Upregulating MYO5A by Absorbing miR-136-5p and miR-370-3p

Circular RNAs (circRNAs) are a class of key regulators in cancers via regulating gene levels by acting as sponges of miRNAs. This study was devoted to explore the functional mechanism of circRNA fibronectin type III domain-containing protein 3B (circ-FNDC3B) in esophageal squamous cell carcinoma (ESCC). RNA levels were examined via reverse transcription-quantitative polymerase chain reaction assay. Cell viability detection was performed using Cell Counting Kit-8 assay. The proliferation ability was determined through colony formation assay and EDU assay. Flow cytometry was applied for analysis of apoptosis. Invasion ability was assessed via transwell assay. Target binding was analyzed by dual-luciferase reporter assay. The protein expression was measured using western blot. In vivo research was conducted via xenograft model in mice. Circ-FNDC3B exhibited significant upregulation in ESCC tissues and cells. Downregulation of circ-FNDC3B inhibited ESCC cell proliferation and invasion but accelerated cell apoptosis. Circ-FNDC3B interacted with miR-136-5p or miR-370-3p. The function of circ-FNDC3B was achieved by sponging miR-136-5p or miR-370-3p. Myosin VA (MYO5A) acted as a downstream target of miR-136-5p or miR-370-3p. MYO5A reversed miR-136-5p/miR-370-3p-induced tumor inhibition in ESCC cells. Circ-FNDC3B targeted miR-136-5p or miR-370-3p to affect MYO5A expression. Circ-FNDC3B knockdown reduced tumor growth in vivo by inhibiting miR-136-5p or miR-370-3p-mediated MYO5A expression. These findings demonstrated that circ-FNDC3B contributed to malignant progression of ESCC cells via miR-136-5p/MYO5A or miR-370-3p/MYO5A axis.

Silencing LncRNA CASC9 inhibits proliferation and invasion of colorectal cancer cells by MiR-542-3p/ILK

Colorectal cancer (CRC) ranks the third in cancers and the second in the reasons of cancer-related death. More evidence indicates that long non-coding RNA participates in tumor initiation and progression. It’s known that cancer susceptibility candidate 9 is an oncogenic long non-coding RNA in CRC. miR-542-3p is a negative regulator of CRC, while integrin-linked kinase could contribute to tumor progression and chemoresistance. However, the correlation among long non-coding RNA cancer susceptibility candidate 9, miR-542-3p and integrin-linked kinase in CRC is still unclear. We demonstrated long non-coding RNA cancer susceptibility candidate 9 in CRC specimens and cell lines overexpressed via real-time quantitative polymerase chain reaction. Once long non-coding RNA cancer susceptibility candidate 9 was knocked down, it significantly inhibited proliferation, invasion, and migration of CRC cells in real-time quantitative polymerase chain reaction, cell counting kit-8, 5-ethynyl-2’-deoxyuridine, and transwell assays, which also was validated in vivo. Long non-coding RNA cancer susceptibility candidate 9 negatively regulates miR-542-3p in a targeted manner, and the function of up-regulated miR-542-3p was confirmed similarly. While miR-542-3p negatively regulates integrin-linked kinase. Thus, we further verified that overexpression of integrin-linked kinase on down-regulated long non-coding RNA cancer susceptibility candidate 9 or up-regulated miR-542-3p significantly restored CRC cell proliferation via bioinformatic analysis, dual-luciferase report assay, real-time quantitative polymerase chain reaction, RNA immunoprecipitation, and western blot. This study testified that silencing long non-coding RNA cancer susceptibility candidate 9 could inhibit proliferation and invasion of CRC cells by miR-542-3p/integrin-linked kinase.

OTUB2 regulates KRT80 stability via deubiquitination and promotes tumour proliferation in gastric cancer

OTUB2 is a deubiquitinating enzyme that contributes to tumor progression. However, the expression of OTUB2 and its prognostic importance in gastric cancer remain unclear. The expression of OTUB2 and KRT80 in GC tissues was investigated using western blotting, qRT-PCR, multiple immunofluorescence staining, and immunohistochemistry. For survival studies, Kaplan-Meier analysis with the log-rank test was used. The role of OTUB2 during GC proliferation was investigated using in vivo and in vitro assays. OTUB2 was found to be overexpressed in GC tissues and to act as an oncogene, which was linked to patients' poor prognosis. Knockdown of OTUB2 inhibited the proliferative capacity of GC cells in vitro and in vivo, although the proliferative capacity was restored upon re-supplementation with KRT80. OTUB2 mechanically stabilized KRT80 by deubiquitinating and shielding it from proteasome-mediated degradation through Lys-48 and Lys-63. Furthermore, by activating the Akt signaling pathway, OTUB2 and KRT80 facilitated GC proliferation. In summary, OTUB2 regulates KRT80 stability via deubiquitination promoting proliferation in GC via activation of the Akt signaling pathway, implying that OTUB2 could be a novel prognostic marker.

Circular RNA circ_0000515 adsorbs miR-542-3p to accelerate bladder cancer progression via up-regulating ILK expression

Background: Bladder cancer (BC) is a common cause of cancer-relevant deaths globally. This study is designed to delve into expressions, biological functions and molecular mechanisms of circ_0000515 in BC.

Methods: Quantitative real-time polymerase chain reaction was accomplished to examine circ_0000515, miR-542-3p and integrin-linked kinase (ILK) mRNA expressions in BC tissues and cell lines. In RT-4 and RT-112 cells with circ_0000515 depletion and UMUC3 and BIU-87 cells with this circ RNA overexpression, a cell counting kit-8 assay was adopted to monitor the viability. Besides, transwell assay was conducted to detect cell migration and aggressiveness, and luciferase reporter gene assay was applied to probe the interplay among circ_0000515, miR-542-3p and ILK mRNA. Additionally, Besides, the regulatory function of circ_0000515 on miR-542-3p expression was under the assay of quantitative real-time polymerase chain reaction, and western blot was fulfilled to determine the regulative function of circ_0000515/miR-542-3p axis on ILK protein expressions. A xenograft animal was modeled to examine lung metastasis in vivo.

Results: Circ_0000515 and ILK expressions were significantly elevated in BC tissues and cell lines, while that of miR-542-3p was dramatically suppressed. Knocking down circ_0000515 could significantly repress the growth, migration and aggressiveness of BC cells while overexpression of circ_0000515 showed opposite effects. Moreover, circ_0000515 knockdown inhibited pulmonary metastasis in vivo. Circ_0000515 was validated to adsorb miR-542-3p, and ILK was testified as the downriver target of miR-542-3p. Circ_0000515 could ascend ILK expression through repressing that of miR-542-3p.

Conclusions: Circ_0000515, as a tumor promoter, strengthens the viability, migration and aggressiveness of BC cells via modulating miR-542-3p/ILK axis.

OTUB1 Promotes Progression and Proliferation of Prostate Cancer via Deubiquitinating and Stabling Cyclin E1

Background: Prostate cancer (PCa) is currently the most common cancer among males worldwide. It has been reported that OTUB1 plays a critical role in a variety of tumors and is strongly related to tumor proliferation, migration, and clinical prognosis. The aim of this research is to investigate the regulatory effect of OTUB1 on PCa proliferation and the underlying mechanism. Methods: Using the TCGA database, we identified that OTUB1 was up-regulated in PCa, and observed severe functional changes in PC3 and C4-2 cells through overexpression or knock down OTUB1. Heterotopic tumors were implanted subcutaneously in nude mice and IHC staining was performed on tumor tissues. The relationship between OTUB1 and cyclin E1 was identified via Western blotting and immunoprecipitations assays. Results: We found that the expression of OTUB1 in PCa was significantly higher than that in Benign Prostatic Hyperplasia (BPH). Overexpression OTUB1 obviously promoted the proliferation and migration of PC3 and C4-2 cells via mediating the deubiquitinated Cyclin E1, while OTUB1 knockout has the opposite effect. The nude mice experiment further explained the above conclusions. We finally determined that OTUB1 promotes the proliferation and progression of PCa via deubiquitinating and stabling Cyclin E1. Conclusions: Our findings reveal the critical role of OTUB1 in PCa, and OTUB1 promotes the proliferation and progression of PCa via deubiquitinating and stabilizing Cyclin E1. Blocking OTUB1/Cyclin E1 axis or applying RO-3306 could significantly repress the occurrence and development of PCa. OTUB1/Cyclin E1 axis might provide a new and potential therapeutic target for PCa.

MicroRNA-103a Curtails the Stemness of Non-Small Cell Lung Cancer Cells by Binding OTUB1 via the Hippo Signaling Pathway

OBJECTIVE

Although microRNA-103a (miR-103a) dysfunction has been implicated in various cancers, its relevance to non-small cell lung cancer (NSCLC) has not been clarified. This study was conducted to examine the molecular mechanism underlying the regulatory role of miR-103a in NSCLC.

METHODS

Kaplan-Meier analysis was carried out to assess the relationship between overall survival of NSCLC patients and miR-103a expression. Reverse-transcription quantitative polymerase chain reaction and western blot analyses were applied to evaluate the expression of relevant genes in tissues and cells. Sphere formation, MTS, flow cytometry, and Transwell assays were performed to characterize stemness. Dual luciferase reporter gene assays were used to clarify the binding relationship between miR-103a and ovarian tumor domain-containing ubiquitin aldehyde binding protein 1 (OTUB1). Finally, western blot analysis was used to assess the involvement of the Hippo pathway in NSCLC.

RESULTS

In NSCLC tissues and cells, miR-103a was expressed at low levels, whereas OTUB1 was expressed at high levels. Higher miR-103 expression levels were associated with a better prognosis for patients with NSCLC. When miR-103a was overexpressed, cell viability and stemness decreased, whereas apoptosis and cell cycle arrest were facilitated. The expression of phosphorylated YAP also decreased significantly. Opposite trends were observed after miR-103a silencing. OTUB1 expression and YAP phosphorylation decreased in the presence of miR-103a, and OTUB1 overexpression blocked the inhibitory effects of miR-103a on NSCLC cells.

CONCLUSION

The miR-103a/OTUB1/Hippo axis may play a role in modulating the malignant behavior and stemness of cancer stem cells and thus could be a potential therapeutic target for the management of NSCLC.