Breast cancer-associated gene 3 interacts with Rac1 and augments NF-κB signaling in vitro, but has no effect on RANKL-induced bone resorption in vivo

GATA4 regulates the transcription of MMP9 to suppress the invasion and migration of breast cancer cells via HDAC1-mediated p65 deacetylation

GATA-binding protein 4 (GATA4) is recognized for its significant roles in embryogenesis and various cancers. Through bioinformatics and clinical data, it appears that GATA4 plays a role in breast cancer development. Yet, the specific roles and mechanisms of GATA4 in breast cancer progression remain elusive. In this study, we identify GATA4 as a tumor suppressor in the invasion and migration of breast cancer. Functionally, GATA4 significantly reduces the transcription of MMP9. On a mechanistic level, GATA4 diminishes MMP9 transcription by interacting with p65 at the NF-κB binding site on the MMP9 promoter. Additionally, GATA4 promotes the recruitment of HDAC1, amplifying the bond between p65 and HDAC1. This leads to decreased acetylation of p65, thus inhibiting p65's transcriptional activity on the MMP9 promoter. Moreover, GATA4 hampers the metastasis of breast cancer in vivo mouse model. In summary, our research unveils a novel mechanism wherein GATA4 curtails breast cancer cell metastasis by downregulating MMP9 expression, suggesting a potential therapeutic avenue for breast cancer metastasis.

Cathepsin K: A Versatile Potential Biomarker and Therapeutic Target for Various Cancers

Cancer, a common malignant disease, is one of the predominant causes of diseases that lead to death. Additionally, cancer is often detected in advanced stages and cannot be radically cured. Consequently, there is an urgent need for reliable and easily detectable markers to identify and monitor cancer onset and progression as early as possible. Our aim was to systematically review the relevant roles of cathepsin K (CTSK) in various possible cancers in existing studies. CTSK, a well-known key enzyme in the bone resorption process and most studied for its roles in the effective degradation of the bone extracellular matrix, is expressed in various organs. Nowadays, CTSK has been involved in various cancers such as prostate cancer, breast cancer, bone cancer, renal carcinoma, lung cancer and other cancers. In addition, CTSK can promote tumor cells proliferation, invasion and migration, and its mechanism may be related to RANK/RANKL, TGF-β, mTOR and the Wnt/β-catenin signaling pathway. Clinically, some progress has been made with the use of cathepsin K inhibitors in the treatment of certain cancers. This paper reviewed our current understanding of the possible roles of CTSK in various cancers and discussed its potential as a biomarker and/or novel molecular target for various cancers.

A‑kinase interacting protein 1 regulates the cell proliferation, invasion, migration and angiogenesis of clear cell renal cell carcinoma cells and affects the ERK/c‑Myc signaling pathway by binding to Rac1

A-kinase interacting protein 1 (AKIP1) has previously been demonstrated to be overexpressed in clear cell renal cell carcinoma (ccRCC) tissues and is associated with patient prognosis. The aim of the present study was to explore whether AKIP1 can affect the proliferation, invasion, migration and angiogenesis of ccRCC cells via its interaction with Rac1. Furthermore, the influence of AKIP1 and therefore Rac1 on the expression of the downstream ERK/cellular (c)-Myc signaling pathway was explored. The interaction between AKIP1 and Rac1 was determined using co-immunoprecipitation. The mRNA and protein expression levels of AKIP1 and Rac1 in normal renal epithelial cell lines and ccRCC cell lines were detected using reverse transcription-quantitative PCR (RT-qPCR) and western blotting, respectively. The transfection efficiency of small interfering RNA-AKIP1 and the Rac1 overexpression vector were also confirmed using RT-qPCR and western blotting. The viability, proliferation, invasion and migration of ccRCC cells following transfection were analyzed using the Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine staining, Transwell and wound healing assays, respectively. The tube formation ability of HUVECs was assessed using the tube formation assay. The protein expression levels of proliferation, invasion, migration and tube-formation-associated proteins as well as proteins associated with the ERK/c-Myc signaling pathway, were detected via western blotting. The results demonstrated that AKIP1 expression levels were increased in ccRCC cell lines. AKIP1 knockdown inhibited the proliferation, invasion and migration of ccRCC cells and HUVEC tube-formation. In addition, AKIP1 was demonstrated to bind to Rac1 in ccRCC cells and AKIP1 downregulation inhibited Rac1 expression. Furthermore, Rac1 overexpression reversed the effects of AKIP1 knockdown on ccRCC cells. AKIP1 knockdown also suppressed the ERK/c-Myc signaling pathway, which was reversed by Rac1 overexpression. In conclusion, AKIP1 knockdown potentially suppressed the proliferation, invasion, migration and angiogenesis of ccRCC cells and inhibited the ERK/c-Myc signaling pathway by binding to Rac1.

AKIP1 promotes glioblastoma viability, mobility and chemoradiation resistance via regulating CXCL1 and CXCL8 mediated NF-κB and AKT pathways

This study aimed to investigate the interaction of A-kinase-interacting protein 1 (AKIP1) with C-X-C motif chemokine ligand (CXCL)1, CXCL2, CXCL8, and their effects on regulating glioblastoma multiforme (GBM) malignant behaviors. AKIP1 expression was modified by pcDNA and pGPH1 vectors in U-87 MG and U-251 MG cells. Subsequently, multiple compensative experiments were conducted via adding CXCL1, CXCL2 and CXCL8 in the pGPH1-AKIP1 (AKIP1 knockdown) transfected U-87 MG and U-251 MG cells, respectively. Furthermore, AKIP1, CXCL1/2/8 expressions in 10 GBM and 10 low-grade glioma (LGG) tumor samples were detected. AKIP1 was elevated in various GBM cell lines compared to normal human astrocytes. AKIP1 overexpression promoted U-87 MG and U-251 MG cell proliferation and invasion while inhibited apoptosis; and it enhanced chemoresistance to temozolomide (but not cisplatin) and radiation resistance; then AKIP1 knockdown showed the opposite effects. Meanwhile, AKIP1 positively regulated CXCL1/2/8, NF-κB pathway, AKT pathway and PD-L1 expression. Further multiple compensative experiments uncovered that CXCL1 and CXCL8 promoted proliferation, invasion, chemoradiation resistance, NF-κB pathway, AKT pathway and PD-L1 expression in U-87 MG and U-251 MG cells, also in pGPH1-AKIP1 (AKIP1 knockdown) transfected U-87 MG and U-251 MG cells; although CXCL2 exhibited similar treads, but its effect was much weaker. Besides, NF-κB pathway inhibitor and AKT pathway inhibitor attenuated the effect of CXCL1&CXCL8 on promoting GBM cell malignant behaviors. Clinically AKIP1 and CXCL1/8 were elevated in GBM compared to LGG tumor samples, and they were inter-correlated. AKIP1 promotes GBM viability, mobility and chemoradiation resistance via regulating CXCL1 and CXCL8 mediated NF-κB and AKT pathways.

Various AKIP1 expression levels affect its subcellular localization but have no effect on NF-kappaB activation

A-kinase interacting protein 1 (AKIP1) has been shown to interact with a broad range of proteins involved in various cellular processes, including apoptosis, tumorigenesis, and oxidative stress suggesting it might have multiple cellular functions. In this study, we used an epitope-tagged AKIP1 and by combination of immunochemical approaches, microscopic methods and reporter assays we studied its properties. Here, we show that various levels of AKIP1 overexpression in HEK-293 cells affected not only its subcellular localization but also resulted in aggregation. While highly expressed AKIP1 accumulated in electron-dense aggregates both in the nucleus and cytosol, low expression of AKIP1 resulted in its localization within the nucleus as a free, non-aggregated protein. Even though AKIP1 was shown to interact with p65 subunit of NF-kappaB and activate this transcription factor, we did not observe any effect on NF-kappaB activation regardless of various AKIP1 expression level.

Icariin abrogates osteoclast formation through the regulation of the RANKL-mediated TRAF6/NF-κB/ERK signaling pathway in Raw264.7 cells

BACKGROUND

Icariin is pharmacologically active prenylated flavonoid glycoside that has various biologic effects such as antioxidant, anticancer, and anti-inflammatory activities. In addition, icariin has been used in Chinese medicine for thousands of years to treat osteoporosis and it is still being used today. However, direct mechanism of icariin in the treatment of bone disease is not understood.

PURPOSE

The purpose of this study is to investigate whether icariin influences RANKL-induced osteoclast formation in murine macrophages.

METHODS

Osteoclastogenesis was determined by TRAP staining and activity assay. Inhibition of signaling pathways and marker protein expression were evaluated by western blot analysis. The NF-κB (p65) nuclear localization was detected by immunofluorescence assay, and NF-κB/DNA-binding activity was detected by electrophoretic mobility shift assay (EMSA).

RESULTS

In our study, icariin inhibited the differentiation of pre-osteoclast cells into osteoclasts and suppressed expression of various genes involved in osteoclast formation and bone resorption. Also, icariin blocked the osteoclastogenesis induced by MCF7 and MDA-MB-231 breast cancer cells through inhibition of NF-κB activation. We found that icariin inhibited RANKL-stimulated TRAF-6 expression, and subsequently suppressed the phosphorylation of ERK, but icariin did not show an effect on p38, JNK, and Akt activation.

CONCLUSION

These results indicate that icariin is likely to be a candidate for bone-related disease treatment and that icariin provides insights into the molecular mechanisms that influence RANKL-induced osteoclast differentiation.

Compartmentalisation of RAC1 signalling

RAC1 signalling has been implicated in a variety of dynamic cell biological processes that are orchestrated through regulated localisation and activation of RAC1. As a small GTPase, RAC1 switches between active and inactive states at various subcellular locations that include the plasma membrane, nucleus and mitochondria. Once activated, RAC1 interacts with a range of effectors that then mediate various biological functions. RAC1 is regulated by a large number of proteins that can promote its recruitment, activation, deactivation, or stability. RAC1 and its regulators are subject to various post-translational modifications that further fine tune RAC1 localisation, levels and activity. Developments in technologies have enabled the accurate detection of activated RAC1 during processes such as cell migration, invasion and DNA damage. Here, we highlight recent advances in our understanding of RAC1 regulation and function at specific subcellular sites.