The role of sLZIP in cyclin D3-mediated negative regulation of androgen receptor transactivation and its involvement in prostate cancer

Small leucine zipper protein negatively regulates liver fibrosis by suppressing the expression of plasminogen activator inhibitor-1

Liver fibrosis, which is caused by viral infection, toxic exposure, and autoimmune diseases, is a chronic liver disease. Plasminogen activator inhibitor-1 (PAI-1) is a serine protease inhibitor of tissue-type plasminogen activator (tPA) and urokinase plasminogen activator, which convert plasminogen into plasmin. Therefore, PAI-1 suppresses fibrinolysis by blocking plasmin synthesis and is involved in liver fibrosis via extracellular matrix deposition. Small leucine zipper protein (sLZIP) acts as a transcription factor and plays critical roles in many cellular processes. However, the role of sLZIP in liver fibrosis remains unclear. In this study, we investigated the role of sLZIP in regulating PAI-1 transcription and liver fibrosis. sLZIP knockdown enhanced the expression of PAI-1 at the mRNA and protein levels. sLZIP knockdown also increased PAI-1 secretion and suppressed blood clot lysis by blocking tPA activity. Moreover, conditioned medium derived from sLZIP knockdown cells downregulated the expression of matrix metalloprotease (MMP)-2 and MMP-9 in the presence of tPA in hepatic stellate cells (HSCs). Liver-specific sLZIP knockout mice showed deteriorated liver fibrosis compared to control mice in a bile duct ligation-induced fibrosis model. These findings demonstrate that sLZIP functions as a negative regulator of liver fibrosis by suppressing PAI-1 transcription and HSC activation.

CREB3 suppresses hepatocellular carcinoma progression by depressing AKT signaling through competitively binding with insulin receptor and transcriptionally activating RNA-binding motif protein 38

cAMP responsive element binding protein 3 (CREB3), belonging to bZIP family, was reported to play multiple roles in various cancers, but its role in hepatocellular carcinoma (HCC) is still unclear. cAMP responsive element binding protein 3 like 3 (CREB3L3), another member of bZIP family, was thought to be transcription factor (TF) to regulate hepatic metabolism. Nevertheless, except for being TFs, other function of bZIP family were poorly understood. In this study, we found CREB3 inhibited growth and metastasis of HCC in vitro and in vivo. RNA sequencing indicated CREB3 regulated AKT signaling to influence HCC progression. Mass spectrometry analysis revealed CREB3 interacted with insulin receptor (INSR). Mechanistically, CREB3 suppressed AKT phosphorylation by inhibiting the interaction of INSR with insulin receptor substrate 1 (IRS1). In our study, CREB3 was firstly proved to affect activation of substrates by interacting with tyrosine kinase receptor. Besides, CREB3 could act as a TF to transactivate RNA-binding motif protein 38 (RBM38) expression, leading to suppressed AKT phosphorylation. Rescue experiments further confirmed the independence between the two functional manners. In conclusion, CREB3 acted as a tumor suppressor in HCC, which inhibited AKT phosphorylation through independently interfering interaction of INSR with IRS1, and transcriptionally activating RBM38.

CREB3L4 promotes hepatocellular carcinoma progression and decreases sorafenib chemosensitivity by promoting RHEB-mTORC1 signaling pathway

This study was designed to explore the roles of CREB3L4 in the pathogenesis and drug resistance of hepatocellular carcinoma (HCC). The proliferation of HCC lines was determined in the presence of CREB3L4 over-expression and silencing. Chromatin immunoprecipitation (ChIP) assay and dual-luciferase reporter assay were performed to screen the potential target of CREB3L4 on mTORC1. Xenografted tumor model was established to define the regulatory effects of CREB3L4 in the tumorigenesis. Then we evaluated the roles of CREB3L4 in chemosensitivity to sorafenib treatment. CREB3L4 significantly induced the HCC cell proliferation by modulating the activation of mTROC1-S6K1 signaling pathway via binding with RHEB promoter. Moreover, CREB3L4 dramatically inhibited the chemosensitivity to sorafenib treatment via up-regulating RHEB-mTORC1 signaling. CREB3L4 promoted HCC progression and decreased its chemosensitivity to sorafenib through up-regulating RHEB-mTORC1 signaling pathway, indicating a potential treatment strategy for HCC through targeting CREB3L4.

Regulating Androgen Receptor Function in Prostate Cancer: Exploring the Diversity of Post-Translational Modifications

Androgen receptor (AR) transcriptional activity significantly influences prostate cancer (PCa) progression. In addition to ligand stimulation, AR transcriptional activity is also influenced by a variety of post-translational modifications (PTMs). A number of oncogenes and tumor suppressors have been observed leveraging PTMs to influence AR activity. Subjectively targeting these post-translational modifiers based on their impact on PCa cell proliferation is a rapidly developing area of research. This review elucidates the modifiers, contextualizes the effects of these PTMs on AR activity, and connects these cellular interactions to the progression of PCa.

International Union of Basic and Clinical Pharmacology CXIII: Nuclear Receptor Superfamily-Update 2023

The NR superfamily comprises 48 transcription factors in humans that control a plethora of gene network programs involved in a wide range of physiologic processes. This review will summarize and discuss recent progress in NR biology and drug development derived from integrating various approaches, including biophysical techniques, structural studies, and translational investigation. We also highlight how defective NR signaling results in various diseases and disorders and how NRs can be targeted for therapeutic intervention via modulation via binding to synthetic lipophilic ligands. Furthermore, we also review recent studies that improved our understanding of NR structure and signaling. SIGNIFICANCE STATEMENT: Nuclear receptors (NRs) are ligand-regulated transcription factors that are critical regulators of myriad physiological processes. NRs serve as receptors for an array of drugs, and in this review, we provide an update on recent research into the roles of these drug targets.

Hsa_circ_0007031 promotes the proliferation and migration of osteosarcoma cells by sponging miR-196a-5p to regulate the HOXB6

Circular RNAs (circRNAs), a subclass of noncoding RNAs, have been demonstrated to play an essential role in osteosarcoma (OS) development. However, there is still a significant gap in investigating its biological functions and underlying molecular mechanisms, and novel targets of circRNAs have yet to be fully explored. Herein, we found that hsa_circ_0007031 is noticeably raised in OS clinical tissues and cell lines. Hsa-circ-0007031 accelerates OS cell proliferation and migration in vitro and tumor growth and metastasis in vivo and is strongly linked with the stemness of cancer stem cells in OS. Mechanistically, hsa_circ_0007031 shares miRNA response elements with Homeobox B6 (HOXB6), which is identified as a novel pro-tumorigenic gene of OS. Hsa_circ_0007031 competitively binds to miR-196a-5p to prevent miR-196a-5p from lowering the level of HOXB6, which modulates chemokines of cytokine-cytokine receptor interaction signaling pathway and finally promotes OS malignant behavior. In summary, our data unveiled that hsa_circ_0007031/miR-196a-5p/HOXB6 axis-mediated cytokine-cytokine receptor interaction facilitates the progression of OS and maintains the properties of tumor stem cells, which could be a promising therapeutic target for OS.

The role of cyclins in the development and progression of prostate cancer

The role of cyclins in hormone-dependent neoplasms is crucial in the development of the disease that is resistant to first-line therapy, as the example of breast cancer shows. However, in prostate cancer, cyclins are studied to a lesser extent. There are some well-described molecular pathways, including cyclins A1 and D1 signaling, however the role of other cyclins, e.g., D2, D3, E, and H, still requires further investigation. Recent studies indicate that cyclins regulate various cellular processes, not only the cell cycle. Furthermore, they remain in cross-talk with many other signaling pathways, e.g., MAPK/ERK, PI3K/Akt, and Notch. The androgen signaling axis, which is pivotal in prostate cancer progression, interferes with cyclin pathways at many levels. This article summarizes current knowledge on the influence of cyclins on prostate cancer progression by describing interactions between the androgen receptor and cyclins, as well as mechanisms underlying the development of resistance to currently used therapies.

Small leucine zipper protein functions as a modulator for metabolic reprogramming of colorectal cancer cells by inducing nutrient stress-mediated autophagy

In multiple cancers, autophagy promotes tumor development by recycling intracellular components into metabolic pathways. Autophagy-induced metabolic reprogramming and plasticity lead to cancer cell survival and resistance to anticancer therapy. We investigated the role of small leucine zipper protein (sLZIP) in autophagy and cell survival under nutrient-deficient conditions in colorectal cancer (CRC). sLZIP was induced by nutrient stress and increased the transcription of microtubule-associated protein 1A/1B-light chain 3 (LC3), by directly binding to its promoter. Under nutrient stress conditions, sLZIP activated autophagy and promoted the survival of CRC cells. sLZIP induced metabolic reprogramming of CRC cells, to activate glutaminolysis and the tricarboxylic acid cycle. sLZIP also enhanced the autophagic degradation of Keap1 and the nuclear accumulation of Nrf2, leading to NQO1 expression, for maintenance of redox homeostasis. sLZIP-knockout CRC cells exhibited impaired autophagy induction in the glycolytic inhibition state. Xenograft mice lacking sLZIP showed decreased tumor growth, by rendering CRC cells sensitive to glycolysis inhibition. The expression of sLZIP and LC3B was highly elevated in tumors of CRC patients compared to that in normal tissues, and correlated with the progression of CRC. These findings suggest that sLZIP drives autophagy and metabolic reprogramming to promote colorectal tumorigenesis.

Role of small leucine zipper protein in hepatic gluconeogenesis and metabolic disorder

Hepatic gluconeogenesis is the central pathway for glucose generation in the body. The imbalance between glucose synthesis and uptake leads to metabolic diseases such as obesity, diabetes, and cardiovascular diseases. Small leucine zipper protein (sLZIP) is an isoform of LZIP and it mainly functions as a transcription factor. Although sLZIP is known to regulate the transcription of genes involved in various cellular processes, the role of sLZIP in hepatic glucose metabolism is not known. In this study, we investigated the regulatory role of sLZIP in hepatic gluconeogenesis and its involvement in metabolic disorder. We found that sLZIP expression was elevated during glucose starvation, leading to the promotion of phosphoenolpyruvate carboxylase and glucose-6-phosphatase expression in hepatocytes. However, sLZIP knockdown suppressed the expression of the gluconeogenic enzymes under low glucose conditions. sLZIP also enhanced glucose production in the human liver cells and mouse primary hepatic cells. Fasting-induced cyclic adenosine monophosphate impeded sLZIP degradation. Results of glucose and pyruvate tolerance tests showed that sLZIP transgenic mice exhibited abnormal blood glucose metabolism. These findings suggest that sLZIP is a novel regulator of gluconeogenic enzyme expression and plays a role in blood glucose homeostasis during starvation.

Small leucine zipper protein promotes the metastasis of castration-resistant prostate cancer through transcriptional regulation of matrix metalloproteinase-13

Matrix metalloproteinases (MMPs) function as central modulators of tissue remodeling. Abnormal expression and altered activity of MMPs result in excessive extracellular matrix degradation and increased tumor metastasis in various cancers. Small leucine zipper protein (sLZIP), belonging to the leucine zipper transcription factor family, functions as a transcriptional regulator of genes involved in various cellular processes. However, its role in MMP expression and castration-resistant prostate cancer (CRPC) metastasis remains unclear. In this study, we investigated the role of sLZIP in MMP-13 expression and its involvement in CRPC metastasis. sLZIP increased MMP-13 transcription by directly binding to its promoter in CRPC cells. We found that the expression levels of GR, which represses MMP transcription, were elevated in CRPC cells. However, sLZIP suppressed the inhibitory effect of GR and enhanced the secretion of MMP-13 in CRPC cells. sLZIP promoted cell migration and invasion; however, a specific MMP-13 inhibitor blocked sLZIP-induced cell motility. Depletion of sLZIP using the CRISPR/Cas9 system downregulated MMP-13 mRNA expression in PC3 cells. Mice injected with sLZIP-depleted PC3 cells showed significantly reduced metastatic tumor volume in the lung compared to mice injected with control PC3 cells. Our findings suggest that sLZIP plays an important role in MMP-13 induction and CRPC metastasis. Therefore, sLZIP inhibition could be a novel therapeutic strategy for metastatic GR-enriched CRPC.

Development of a novel transcription factors-related prognostic signature for serous ovarian cancer

Growing evidence suggest that transcription factors (TFs) play vital roles in serous ovarian cancer (SOC). In the present study, TFs mRNA expression profiles of 564 SOC subjects in the TCGA database, and 70 SOC subjects in the GEO database were screened. A 17-TFs related prognostic signature was constructed using lasso cox regression and validated in the TCGA and GEO cohorts. Consensus clustering analysis was applied to establish a cluster model. The 17-TFs related prognostic signature, risk score and cluster models were effective at accurately distinguishing the overall survival of SOC. Analysis of genomic alterations were used to elaborate on the association between the 17-TFs related prognostic signature and genomic aberrations. The GSEA assay results suggested that there was a significant difference in the inflammatory and immune response pathways between the high-risk and low-risk score groups. The potential immune infiltration, immunotherapy, and chemotherapy responses were analyzed due to the significant difference in the regulation of lymphocyte migration and T cell-mediated cytotoxicity between the two groups. The results indicated that patients with low-risk score were more likely to respond anti-PD-1, etoposide, paclitaxel, and veliparib but not to gemcitabine, doxorubicin, docetaxel, and cisplatin. Also, the prognostic nomogram model revealed that the risk score was a good prognostic indicator for SOC patients. In conclusion, we explored the prognostic values of TFs in SOC and developed a 17-TFs related prognostic signature to predict the survival of SOC patients.

miR-138-5p suppresses glioblastoma cell viability and leads to cell cycle arrest by targeting cyclin D3

Although malignant glioblastoma (GBM) treatment has significantly improved in the past few decades, the prognosis of GBM remains unsatisfactory. MicroRNA (miR)-138-5p has been reported as a tumor suppressor in several types of human cancer; however, little is known about the function of miR-138-5p in GBM. The present study aimed to investigate the role of miR-138-5p in GBM as well as the underlying molecular mechanisms. The present study performed bioinformatics analysis, reverse transcription-quantitative (RT-q)PCR, western blotting, cell viability assays, colony formation assays, invasion assays and cell cycle analysis to investigate the biological function of miR-138-5p in both patient tissues and cell lines. In addition, miR-138-5p targets in GBM were predicted using Gene Expression Omnibus website and further validated by a dual luciferase reporter gene assay. The results revealed that miR-138-5p expression levels in patients with GBM from a Gene Expression Omnibus dataset were significantly downregulated. RT-qPCR analysis of miR-138-5p expression levels also revealed similar results in GBM tissues and cell lines. The upregulation of miR-138-5p expression levels using a mimic significantly inhibited the cell viability, colony formation and the G₀/G₁ to S progression in GBM cell lines, suggesting that miR-138-5p may be a tumor suppressor. Moreover, miR-138-5p was discovered to directly target cyclin D3 (CCND3), a protein that serves an important role in the cell cycle, and inhibited its expression. Finally, silencing CCND3 using small interfering RNA suppressed the viability of GBM cells. In conclusion, the results of the present study suggested that miR-138-5p may function as a tumor suppressor in GBM by targeting CCND3, indicating that miR-138-5p may be a novel therapeutic target for patients with GBM.

The role of small leucine zipper protein in osteoclastogenesis and its involvement in bone remodeling

Bone remodeling is critical to maintain the quality of bone tissues and to heal bone tissue injury. Osteoclasts and osteoblasts are special types of cells involved in this event. In particular, the resorption activity of mature osteoclasts is required for the formation of new bones. Human small leucine zipper protein (sLZIP) is known to induce the osteoblast differentiation of mesenchymal stem cells. However, the roles of sLZIP in osteoclast differentiation and bone remodeling have not been explored. In this study, we investigated the roles of sLZIP in regulating osteoclast formation and in the bone remodeling process using sLZIP transgenic (TG) mice. Tibiae from sLZIP TG mice contained more osteoclasts than those from wild type (WT) mice. Bone marrow-derived macrophages (BMM) from sLZIP TG mice showed increased differentiation into osteoclasts compared with BMM from WT mice. sLZIP bound to the promotor and induced the expression of nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) and its target osteoclastogenic genes. To understand the role of sLZIP in bone remodeling, a bone-defect model was generated. Results of micro-CT scanning and histologic analysis demonstrated that sLZIP TG mice have faster bone formation during healing compared with WT mice. Notably, the soft callus around the defect area was replaced faster by hard callus in sLZIP TG mice than in WT mice. These findings suggest that sLZIP promotes osteoclast differentiation and plays an important role in bone remodeling.

Posttranslational regulation of androgen dependent and independent androgen receptor activities in prostate cancer

Prostate cancer (PCa) is the most commonly diagnosed cancer among men in western countries. Androgen receptor (AR) signaling plays key roles in the development of PCa. Androgen deprivation therapy (ADT) remains the standard therapy for advanced PCa. In addition to its ligand androgen, accumulating evidence indicates that posttranscriptional modification is another important mechanism to regulate AR activities during the progression of PCa, especially in castration resistant prostate cancer (CRPC). To date, a number of posttranscriptional modifications of AR have been identified, including phosphorylation (e.g. by CDK1), acetylation (e.g. by p300 and recognized by BRD4), methylation (e.g. by EZH2), ubiquitination (e.g. by SPOP), and SUMOylation (e.g. by PIAS1). These modifications are essential for the maintenance of protein stability, nuclear localization and transcriptional activity of AR. This review summarizes posttranslational modifications that influence androgen-dependent and -independent activities of AR, PCa progression and therapy resistance. We further emphasize that in addition to androgen, posttranslational modification is another important way to regulate AR activity, suggesting that targeting AR posttranslational modifications, such as proteolysis targeting chimeras (PROTACs) of AR, represents a potential and promising alternate for effective treatment of CRPC. Potential areas to be investigated in the future in the field of AR posttranslational modifications are also discussed.

Prognostic significance of cyclin D3 expression in malignancy patients: a meta-analysis

Background

As a pivotal regulator, cyclin D3 gives play to a crucial value in conversion from the G1 stage to the S stage of cell cycle, which is implicated in tumor progression, especially proliferation and migration. Recent literatures have reported that cyclin D3 could predict survival time of malignancy patients. But, its prognostic role of cyclin D3 in neoplasms remains controversial.

Methods

Databases involving EMBASE, PubMed and Web of Science were carefully searched, and literatures investigating the prognostic effect of aberrantly expressing cyclin D3 among human cancers were collected for further analysis. We used both hazards ratios and its corresponding 95% confidence intervals to evaluate the connection among the survival rate of malignancy patients and the expression of cyclin D3.

Results

There were 13 eligible researches involving 16 cohorts and 2395 participants which were included in this study. The outcomes suggested that highly expressing cyclin D3 was significantly correlated with worse clinical prognosis of overall survival (HR 1.88; 95% CI 1.31–2.69) and disease specific survival (HR 2.68; 95% CI 1.35–5.31). But there existed no significant connection between the elevated expression of cyclin D3 with disease free survival (HR 2.65; 95% CI 0.83–8.46), recurrence-free survival (HR 2.86; 95% CI 0.82–9.96) and progression-free survival (HR 5.24; 95% CI 0.46–60.25) of diffident kinds of malignancy patients. Moreover, we discovered that elevated cyclin D3 expression was significantly connected with decreased overall survival in lymphoma (HR 3.72; 95% CI 2.18–6.36) while no significant relevance between highly expressing cyclin D3 and the overall survival in breast cancer was obtained (HR 2.12; 95% CI 0.76–5.91).

Conclusions

This meta-analysis demonstrated that highly expressing cyclin D3 might be an unfavorable prognostic biomarker for various malignancy patients, which can make great contributions to the clinical diagnosis and treatment.

Circular RNA circTADA2A promotes osteosarcoma progression and metastasis by sponging miR-203a-3p and regulating CREB3 expression

BACKGROUND

As a subclass of noncoding RNAs, circular RNAs (circRNAs) have been demonstrated to play a critical role in regulating gene expression in eukaryotes. Recent studies have revealed the pivotal functions of circRNAs in cancer progression. However, little is known about the role of circTADA2A, also named hsa_circ_0043278, in osteosarcoma (OS).

METHODS

CircTADA2A was selected from a previously reported circRNA microarray comparing OS cell lines and normal bone cells. QRT-PCR was used to detect the expression of circTADA2A in OS tissue and cell lines. Luciferase reporter, RNA immunoprecipitation (RIP), RNA pull-down and fluorescence in situ hybridization (FISH) assays were performed to confirm the binding of circTADA2A with miR-203a-3p. OS cells were stably transfected with lentiviruses, and Transwell migration, Matrigel invasion, colony formation, proliferation, apoptosis, Western blotting, and in vivo tumorigenesis and metastasis assays were employed to evaluate the roles of circTADA2A, miR-203a-3p and CREB3.

RESULTS

Our findings demonstrated that circTADA2A was highly expressed in both OS tissue and cell lines, and circTADA2A inhibition attenuated the migration, invasion and proliferation of OS cells in vitro as well as tumorigenesis and metastasis in vivo. A mechanistic study revealed that circTADA2A could readily sponge miR-203a-3p to upregulate the expression of CREB3, which was identified as a driver gene in OS. Furthermore, miR-203a-3p inhibition or CREB3 overexpression could reverse the circTADA2A silencing-induced impairment of malignant tumor behavior.

CONCLUSIONS

CircTADA2A functions as a tumor promoter in OS to increase malignant tumor behavior through the miR-203a-3p/CREB3 axis, which could be a novel target for OS therapy.

Small leucine zipper protein functions as a negative regulator of estrogen receptor α in breast cancer

The nuclear transcription factor estrogen receptor α (ERα) plays a critical role in breast cancer progression. ERα acts as an important growth stimulatory protein in breast cancer and the expression level of ERα is tightly related to the prognosis and treatment of patients. Small leucine zipper protein (sLZIP) functions as a transcriptional cofactor by binding to various nuclear receptors, including glucocorticoid receptor, androgen receptor, and peroxisome proliferator-activated receptor γ. However, the role of sLZIP in the regulation of ERα and its involvement in breast cancer progression is unknown. We found that sLZIP binds to ERα and represses the transcriptional activity of ERα in ERα-positive breast cancer cells. sLZIP also suppressed the expression of ERα target genes. sLZIP disrupted the binding of ERα to the estrogen response element of the target gene promoter, resulting in suppression of cell proliferation. sLZIP is a novel co-repressor of ERα, and plays a negative role in ERα-mediated cell proliferation in breast cancer.

Cyclin D3 predicts disease-free survival in breast cancer

Background

Cyclin D3, which induces progression through the G1 phase of the cell cycle, is a regulator of Cyclin-dependent kinases 4 and 6. Previous studies revealed that abnormal expression of Cyclin D3 was found in many different cancers. However, the role of Cyclin D3 in breast cancer (BC) remains unknown. The aim of this study is to examine the expression pattern of Cyclin D3 in BC and to evaluate its biological role and clinical significance in prognosis prediction. The mechanism involved is also evaluated.

Methods

Immunohistochemical staining was used to detect the expression of Cyclin D3. qRT-PCR was used to detect the mRNA level of Cyclin D3 in BC tissues and BC cell lines. Transwell assay was used to examine the role of Cyclin D3 in the migration and invasion of BC cells. Mass Spectrometry was used to search for the interacting protein with Cyclin D3. Co-Immunoprecipitation assay and GST-Pull Down assay were used to validate the interaction of Cyclin D3 and its interaction protein.

Results

Through detecting Cyclin D3 expression in 243 breast cancer patients’ tissue array, we found Cyclin D3 expression was correlated with ER status (p = 0.000), PR status (p = 0.001), HER2 status (p = 0.002) and tumor differentiation (p = 0.045). The Kaplan–Meier survival curves indicated that the disease free survival (DFS) was significantly poor in high Cyclin D3 expression BC patients (p = 0.004). Furthermore, expression of Cyclin D3 was significantly associated with BC prognosis and was shown to be an independent prognostic marker in breast cancer (p = 0.028). By IHC staining and qPCR detection, Cyclin D3 expression was found to be down-regulated both in BC tissues and in BC cell lines compared with the corresponding normal controls. Further investigation showed Cyclin D3 was involved in the metastasis of BC cells and physically interacted with actin in vivo and in vitro.

Conclusion

Our studies revealed that Cyclin D3 was upregulated in breast cancer and represented a novel predictor of BC prognosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-015-0245-6) contains supplementary material, which is available to authorized users.