CREB1/Lin28/miR-638/VASP Interactive Network Drives the Development of Breast Cancer

RNA-binding proteins in breast cancer: Biological implications and therapeutic opportunities

RNA-binding proteins (RBPs) refer to a class of proteins that participate in alternative splicing, RNA stability, polyadenylation, localization and translation of RNAs, thus regulating gene expression in post-transcriptional manner. Dysregulation of RNA-RBP interaction contributes to various diseases, including cancer. In breast cancer, disorders in RBP expression and function influence the biological characteristics of tumor cells. Targeting RBPs has fostered the development of innovative therapies for breast cancer. However, the RBP-related mechanisms in breast cancer are not completely clear. In this review, we summarize the regulatory mechanisms of RBPs and their signaling crosstalk in breast cancer. Specifically, we emphasize the potential of certain RBPs as prognostic factors due to their effects on proliferation, invasion, apoptosis, and therapy resistance of breast cancer cells. Most importantly, we present a comprehensive overview of the latest RBP-related therapeutic strategies and novel therapeutic targets that have proven to be useful in the treatment of breast cancer.

The Role of Vasodilator-stimulated Phosphoproteins in the Development of Malignant Tumors

Vasodilator-stimulated phosphoprotein (VASP) is an actin-binding protein that includes three structural domains: Enabled/VASP homolog1 (EVH1), EVH2, and proline-rich (PRR). VASP plays an important role in various cellular behaviors related to cytoskeletal regulation. More importantly, VASP plays a key role in the progression of several malignant tumors and is associated with malignant cell proliferation, invasion, and metastasis. Here, we have summarized current studies on the impact of VASP on the development of several malignant tumors and their mechanisms. This study provides a new theoretical basis for clinical molecular diagnosis and molecular targeted therapy.

PKCζ phosphorylates VASP to mediate chemotaxis in breast cancer cells

Breast carcinoma (BC) is one of the most common malignant cancers in females, and metastasis remains the leading cause of death in these patients. Chemotaxis plays an important role in cancer cell metastasis and the mechanism of breast cancer chemotaxis has become a central issue in contemporary research. PKCζ, a member of the atypical PKC family, has been reported to be an essential component of the EGF-stimulated chemotactic signaling pathway. However, the molecular mechanism through which PKCζ regulates chemotaxis remains unclear. Here, we used a proteomic approach to identify PKCζ-interacting proteins in breast cancer cells and identified VASP as a potential binding partner. Intriguingly, stimulation with EGF enhanced this interaction and induced the translocalization of PKCζ and VASP to the cell membrane. Further experiments showed that PKCζ catalyzes the phosphorylation of VASP at Ser157, which is critical for the biological function of VASP in regulating chemotaxis and actin polymerization in breast cancer cells. Furthermore, in PKCζ knockdown BC cells, the enrichment of VASP at the leading edge was reduced, and its interaction with profilin1 was attenuated, thereby reducing the chemotaxis and overall motility of breast cancer cells after EGF treatment. In functional assays, PKCζ promoted chemotaxis and motility of BC cells through VASP. Our findings demonstrate that PKCζ, a new kinase of VASP, plays an important role in promoting breast cancer metastasis and provides a theoretical basis for expanding new approaches to tumor biotherapy.

MEX3A induces the development of thyroid cancer via targeting CREB1

Thyroid cancer is a prevalent form of endocrine cancer, and its global incidence has been steadily increasing. MEX3A is a protein that is known to be highly expressed in various human malignant tumors, including thyroid cancer, and it has been linked to patient prognosis. However, the molecular mechanisms underlying MEX3A's tumorigenic capabilities in thyroid cancer are not fully understood. In this study, we aimed to investigate the role of MEX3A in thyroid cancer. We confirmed that MEX3A was overexpressed in both thyroid cancer tissues and cell lines. Additionally, we found a positive correlation between high levels of MEX3A and the AJCC stage. To further understand the functional significance of MEX3A in thyroid cancer, we depleted MEX3A expression in B-CPAP and TPC-1 cells. Interestingly, we observed a significant reduction in thyroid cancer cell proliferation and migration, as well as ameliorated cell apoptosis and arrested tumor growth upon MEX3A depletion. These findings strongly suggested that MEX3A played a critical role in the development of thyroid cancer. Furthermore, our study uncovered an important interaction between MEX3A and CREB1 (cAMP response element-binding protein 1). The interaction between MEX3A and CREB1 appeared to contribute to the tumor-promoting effects of MEX3A in thyroid cancer by directly targeting CREB1. Silencing CREB1 was observed to alleviate the malignant phenotypes promoted by MEX3A in thyroid cancer cells. Together, this study highlighted the importance of the MEX3A-CREB1 interaction in thyroid cancer development and suggested the therapeutic potential of targeting MEX3A for the treatment of this disease.

ZNRF2 as an oncogene is transcriptionally regulated by CREB1 in breast cancer models

E3 ubiquitin ligase Zinc and Ring Finger 2 (ZNRF2) has been demonstrated to be engaged in the development of multiple cancers. Nevertheless, the function of ZNRF2 in breast cancer (BC) still unclear. In this work, we firstly analyzed the differentially expressed genes in BC by bioinformatics and found that ZNRF2 was highly expressed in BC. Consistently, we further confirmed that ZNRF2 was upregulated in BC tissues compared with adjacent normal tissues, and this was positively correlated with the poor prognosis and the higher pathological grades of patients with BC. Functional assays performed on HCC1937 and MCF-7 cells indicated that silencing of ZNRF2 suppressed cell proliferation, as evidenced by the decrease in the expression of cyclin A, PCNA and cyclin D1. Flow cytometry and Hoechst staining showed that knockdown of ZNRF2 induced cell apoptosis, which was verified by the upregulation of apoptosis genes such as Bax, cleaved PARP and Bim. ZNRF2 knockdown also inhibited in vivo tumor growth. But, instead, ZNRF2-overexpressed BC cells exhibited obvious malignant phenotypes. Additionally, we observed that cAMP response element binding protein 1 (CREB1) directly bound to the promoter sequence of ZNRF2 and thus activating its transcription, suggesting that ZNRF2 is transcriptionally regulated by CREB1. Additionally, ZNRF2 knockdown could reverse the proliferation-promoting action of CREB1 on BC cells, Hence, this study demonstrated that ZNRF2 might serve as a prospective therapeutic target for BC.

NRF2 signaling pathway: A comprehensive prognostic and gene expression profile analysis in breast cancer

Breast cancer is the most frequently diagnosed malignant tumor in women and a major public health concern. NRF2 axis is a cellular protector signaling pathway protecting both normal and cancer cells from oxidative damage. NRF2 is a transcription factor that binds to the gene promoters containing antioxidant response element-like sequences. In this report, differential expression of NRF2 signaling pathway elements, as well as the correlation of NRF2 pathway mRNAs with various clinicopathologic characteristics, including molecular subtypes, tumor grade, tumor stage, and methylation status, has been investigated in breast cancer using METABRIC and TCGA datasets. In the current report, our findings revealed the deregulation of several NRF2 signaling elements in breast cancer patients. Moreover, there were negative correlations between the methylation of NRF2 genes and mRNA expression. The expression of NRF2 genes significantly varied between different breast cancer subtypes. In conclusion, substantial deregulation of NRF2 signaling components suggests an important role of these genes in breast cancer. Because of the clear associations between mRNA expression and methylation status, DNA methylation could be one of the mechanisms that regulate the NRF2 pathway in breast cancer. Differential expression of Hippo genes among various breast cancer molecular subtypes suggests that NRF2 signaling may function differently in different subtypes of breast cancer. Our data also highlights an interesting link between NRF2 components' transcription and tumor grade/stage in breast cancer.

Fatty acid binding protein 5 promotes the proliferation, migration, and invasion of hepatocellular carcinoma cells by degradation of Krüppel-like factor 9 mediated by miR-889-5p via cAMP-response element binding protein

Mounting evidence has demonstrated that fatty acid binding protein 5 (FABP5) is commonly upregulated in many human malignancies. However, the mechanisms explaining the involvement of FABP5 in hepatocellular carcinoma (HCC) remain unclear. In this study, we demonstrated the involvement of FABP5 and its downstream signaling molecules in HCC progression. We first confirmed that FABP5 expression was upregulated in HCC. Additionally, FABP5 promoted HCC cells proliferation, migration, and invasion. Mechanistic investigation showed that FABP5 could improve cAMP-response element binding protein (CREB) phosphorylation. Meanwhile, CREB, as a transcription factor, upregulated the miR-889-5p expression by binding to the miR-889-5p promoter region. Consequently, miR-889-5p led to downregulation of Krüppel-like factor 9 (KLF9) by binding to the 3ʹ-UTR of the KLF9 mRNA, potentiating the PI3K/AKT signaling pathway and promoting the proliferation, migration, and invasion of HCC cells. Our findings have identified a FABP5/CREB/miR-889-5p/KLF9 axis for HCC progression, and we postulate that blocking this key signaling pathway may represent a promising strategy for HCC treatment.

The functional roles of the circRNA/Wnt axis in cancer

CircRNAs, covalently closed noncoding RNAs, are widely expressed in a wide range of species ranging from viruses to plants to mammals. CircRNAs were enriched in the Wnt pathway. Aberrant Wnt pathway activation is involved in the development of various types of cancers. Accumulating evidence indicates that the circRNA/Wnt axis modulates the expression of cancer-associated genes and then regulates cancer progression. Wnt pathway-related circRNA expression is obviously associated with many clinical characteristics. CircRNAs could regulate cell biological functions by interacting with the Wnt pathway. Moreover, Wnt pathway-related circRNAs are promising potential biomarkers for cancer diagnosis, prognosis evaluation, and treatment. In our review, we summarized the recent research progress on the role and clinical application of Wnt pathway-related circRNAs in tumorigenesis and progression.

PRMT8 Attenuates Cerebral Ischemia/Reperfusion Injury via Modulating Microglia Activation and Polarization to Suppress Neuroinflammation by Upregulating Lin28a

Activation and polarization of microglia are involved in neuroinflammation and regulate ischemic stroke-associated brain injury. Protein arginine methyltransferase 8 functions as a regulatory component of hypoxic stress-induced neuroinflammation. The protective effect of protein arginine methyltransferase 8 (PRMT8) against ischemic stroke-associated brain injury through regulation of microglia activation and polarization was investigated. First, PRMT8 was downregulated in middle cerebral artery occlusion (MCAO)-induced mice and oxygen-glucose deprivation/reoxygenation (OGD/R)-induced SH-SY5Y. Injection with AAV-PRMT8 reduced infarct volumes in MCAO-induced mice. Moreover, injection with AAV-PRMT8 promoted neuronal survival and ameliorated histopathological changes in the brains of MCAO-induced mice. The neuronal apoptosis and neuroinflammation in MCAO-induced mice were suppressed by AAV-PRMT8 injection. Second, PRMT8 overexpression increased cell viability and suppressed the cell apoptosis and inflammation of OGD/R-induced SH-SY5Y. Third, injection with AAV-PRMT8 reduced almost 50% of CD86 + M1 microglia and enhanced about 20% of CD206 + M2 microglia. Furthermore, PRMT8 overexpression attenuated OGD/R-induced M1 phenotype polarization of BV2. Lastly, PRMT8 upregulated Lin28a and loss of Lin28a attenuated PRMT8 overexpression-induced increase in cell viability and decrease in cell apoptosis and inflammation of OGD/R-induced SH-SY5Y. In conclusion, PRMT8 promoted M2 phenotype polarization of microglia and suppressed neuronal apoptosis to ameliorate cerebral ischemia/reperfusion injury through upregulation of Lin28a.

RNA-binding proteins and cancer metastasis

RNA-binding proteins (RBPs) can regulate gene expression through post-transcriptionally influencing all manner of RNA biology, including alternative splicing (AS), polyadenylation, stability, and translation of mRNAs, as well as microRNAs (miRNAs) and circular RNAs (circRNAs) processing. There is accumulating evidence reinforcing the perception that dysregulation or dysfunction of RBPs can lead to various human diseases, including cancers. RBPs influence diverse cancer-associated cellular phenotypes, such as proliferation, apoptosis, senescence, migration, invasion, and angiogenesis, contributing to the initiation and development of tumors, as well as clinical prognosis. Metastasis is the leading cause of cancer-related recurrence and death. Therefore, it is necessary to elucidate the molecular mechanisms behind tumor metastasis. In fact, a growing body of published research has proved that RBPs play pivotal roles in cancer metastasis. In this review, we will summarize the recent advances for helping us understand the role of RBPs in tumor metastasis, and discuss dysfunctions and dysregulations of RBPs affecting metastasis-associated processes including epithelial-mesenchymal transition (EMT), migration, and invasion of cancer cells. Furthermore, we will discuss emerging RBP-based strategy for the treatment of cancer metastasis.

MiR-654-3p Constrains Proliferation, Invasion, and Migration of Sinonasal Squamous Cell Carcinoma via CREB1/PSEN1 Regulatory Axis

Background: MiR-654-3p can repress malignant progression of cancer cells, whereas no relative reports were about its modulatory mechanism in sinonasal squamous cell carcinoma (SNSCC). This research committed to approaching modulatory effect of miR-654-3p on SNSCC cells. Methods: Bioinformatics methods were utilized for analyzing interaction of miR-654-3p/cAMP-responsive element binding protein 1 (CREB1)/presenilin-1 (PSEN1). Expression levels of miR-654-3p, CREB1, and PSEN1 mRNA were assessed by quantitative real-time polymerase chain reaction. Western blot was completed for level assessment of CREB1, PSEN1, and epithelial-mesenchymal transition-related proteins. The targeted relationship between miR-654-3p and CREB1, or CREB1 and PSEN1 was authenticated via dual-luciferase assay and ChIP assay. A trail of experiments in vitro was used for detection of the effects of miR-654-3p/CREB1/PSEN1 axis on malignant progression of SNSCC cells. Results: CREB1 as the downstream target mRNA of miR-654-3p could activate transcription of its downstream target gene PSEN1. Besides, miR-654-3p could target CREB1 to repress PSEN1 expression, thus restraining proliferation, migration, invasion, epithelial-mesenchymal transition, and hastening apoptosis of SNSCC cells. Conclusion: MiR-654-3p as an antitumor gene targeted CREB1 to hamper malignant progression of SNSCC through miR-654-3p/CREB1/PSEN1 axis.

CRTC1-SS18 Fusion Sarcoma With Aberrant Anaplastic Lymphoma Kinase Expression

Undifferentiated small round cell sarcoma (USRCS) represents a highly heterogeneous group of tumors. A variety of specific gene fusions of USRCS have been reported, including CIC-FOXO4, CIC-NUTM1, BCOR-MAML3, and ZC3H7B-BCOR. Here we report a case of sarcoma harboring a rare recurrent CRTC1-SS18 gene fusion, which was considered as USRCS previously. This sarcoma was composed of nests of small round cells encapsulated in a fibrous stroma. Foci of necrosis and hemorrhage were observed in the tumor. Immunohistochemistry for anaplastic lymphoma kinase showed diffuse positivity. RNA-seq results revealed a chromosomal translocation of CRTC1 gene exon 1 on chromosome 19 with SS18 gene exon 2 on chromosome 18. Thereafter, fluorescence in-situ hybridization confirmed the presence of SS18 gene and CRTC1 gene break-apart, which manifested as the splitting of red and green signals into 2 parts. A previous study showed that CRTC1-SS18 fusion sarcoma and EWSR1-CREB1 fusion angiomatoid fibrous histiocytoma were clustered close in the expression profile. However, whether CRTC1-SS18 fusion sarcomas represent a high malignancy has been a matter of debate. Our study is a worthy addition to the series of rare rearrangements associated with sarcomas and may be of therapeutic relevance.

CREB1 acts via the miR‑922/ARID2 axis to enhance malignant behavior of liver cancer cells

There is little information on the role of microRNA (miR)‑922 in the malignant behavior of liver cancer. The present study investigated the regulation of miR‑922 expression levels by cAMP response element binding protein 1 (CREB1) in liver cancer tissue, its role in regulating malignant behavior and its potential targets in liver cancer. miR‑922 expression in liver cancer cells and tissue was determined by reverse transcription‑quantitative PCR. The binding of CREB1 to the promoter region of mir‑922 was tested by chromatin immunoprecipitation‑PCR. The predicted AT‑rich interactive domain 2 (ARID2) and fidgetin, microtubule severing factor targets of miR‑922 were characterized by dual luciferase reporter assay. The effects of altered ARID2 expression levels on miR‑922‑enhanced malignant behavior of liver cancer cells were tested. CREB1 bound to the promoter region of miR‑922. Elevated miR‑922 transcripts were inversely associated with ARID2 expression in liver cancer tissue and cells. miR‑922 inhibited ARID2‑regulated luciferase expression and was present in the miR/argonaute RISC catalytic component 2 complex. ARID2 significantly decreased malignant behavior of liver cancer MHCC97L cells. Similarly, ARID2 over‑expression inhibited growth of xenograft liver cancer tumors and decreased miR‑922, Bcl‑2, proliferating cell nuclear antigen, cyclin D1, MMP3 and MMP9 expression and serum VEGF and TNF‑α levels, but enhanced Bax expression levels in tumors. ARID2 over‑expression abrogated malignant behavior promoted by miR‑922 over‑expression and enhanced miR‑922‑decreased malignant behavior of liver cancer cells. CREB induced miR‑922 transcription, which targeted ARID2 to enhance malignant behavior of liver cancer cells, indicating that the CREB1/miR‑922/ARID2 axis may be a potential target for liver cancer treatment.

Dysregulation of miR-638 in the progression of cancers

MicroRNA (miRNA) is a form of short, single-stranded and non-coding RNA that is important in regulating the post-transcriptional modification of multiple downstream targets. Many miRNAs have been reported to involve in controlling the progression of human diseases, and one of them is miR-638, which play essential roles in regulating the development of human cancer. By targeting the 3'-ends of its targets, miR-638 can regulate cellular processes including proliferation, invasion, metastases, angiogenesis, apoptosis and inflammation. This review was aimed to summarize current findings on the roles of miR-638 in different human cancers based on the results from various in vitro, in vivo and clinical studies. The biogenesis process and tissue expression, followed by the roles of miR-638 in regulating the development of various human cancers by targeting different downstream targets were covered in this review. The potential applications and challenges of employing miR-638 as cancer biomarker and therapeutic agent were also discussed.

LINC01451 drives epithelial-mesenchymal transition and progression in bladder cancer cells via LIN28/TGF-β/Smad pathway

BACKGROUND

The pathogenesis of bladder cancer (BLCa) is still unclear. Long non-coding RNAs (lncRNAs) participate in diverse biological processes across every branch of life, especially in cancer. Dysregulated lncRNAs in BLCa and their biological significance require further investigations.

METHODS

Herein, a differential expression profile of lncRNAs in BLCa was conducted by microarray data. The expression level of lncRNA LINC01451 in 70 pairs of BLCa tissue samples and different BLCa cell lines were analyzed via real-time quantitative PCR. The CRISPR-CAS9 technique was employed to establish the LINC01451 stably transfected cell lines. Loss-of-function, as well as gain-of-function assays were carried out to evaluate the effects of LINC01451 on cell proliferation, migration, and invasion. Patient-derived xenograft (PDX) mouse models were adopted in the in vivo experiments. Western blot, biotinylated RNA probe pull-down assay, fluorescence in situ hybridization, and immunohistochemistry were utilized to assess the underlying molecular mechanisms of LINC01451 in BLCa.

RESULTS

LINC01451 was identified a novel functional lncRNA, whose expression level in BLCa tissues was significantly higher compared with the normal tissues. Furthermore, it was found that LINC01451 directly docked LIN28A and LIN28B, and promoted the proliferation, invasion, and metastasis of BLCa. Mechanistically, LINC0145 was shown to depend on LIN28A and LIN28B, facilitated epithelial-mesenchymal transition (EMT) through activating the TGF-β/Smad signaling pathway, which subsequently aggravated BLCa progression.

CONCLUSIONS

We demonstrates that LINC01451 drives EMT-induced BLCa progression by activating the LIN28/TGF-β/Smad signaling pathway. Promisingly, LINC01451 acts as a prognostic biomarker and a novel therapeutic target for BLCa.