TLR5: A prognostic and monitoring indicator for triple-negative breast cancer

Oncolytic Tanapoxvirus Recombinants Expressing Flagellin C or Mouse Interleukin-2 Are Capable of Regressing Human Triple-Negative Breast Cancer Xenografts in Immuno-Competent BALB/c Nude Mice

Triple-negative breast cancer (TNBC) in humans is the most aggressive and deadly form of BC. Although TNBCs are about 15 percent of the total number of BC cases, they are associated with the highest mortalities. Current treatment options are limited, and most modalities are toxic and have not increased the 5-year survival rates of TNBC. Many oncolytic viruses are emerging as potential therapies for TNBC. In this study, two Tanapoxvirus (TPV) recombinants, one expressing FliC and the other expressing mouse interleukin-2 (mIL-2), were assessed for their efficacy in an immuno-competent xenograft mouse model. MDA-MB-231 tumors were planted in BALB/c nude mice, treated, made immuno-competent via adoptive transfer of splenocytes from healthy BALB/c donors, and then monitored for 40 days. TPV/Δ2L/66R/FliC and TPV/Δ66R/mIL-2 demonstrated significant tumor reduction (p = 0.01602 and p = 0.03890, respectively) compared to the reconstituted control (RC), whereas wtTPV did not. Pathological analyses of treated tumors revealed cells consistent with lymphocyte and plasma cell morphology in reconstituted mice treated with TPV recombinants. Anti-viral plaque reduction assays conducted using harvested serum from treated animals indicated the presence of anti-TPV antibodies in mice reconstituted and treated with TPV that were missing from immune-deficient nude mice, including those exposed to TPV and of statistically equivalent serum concentrations to normal BALB/c mice immunized against TPV. The results suggest immuno-deficient BALB/c nude mice can become immuno-competent via adoptive transfer of splenocytes from genetically identical donors and allow for testing of tumor xenografts in a competent model system. The TPV recombinants tested should be further studied for the potential treatment of human TNBC.

Toll-like receptors in health and disease

Toll-like receptors (TLRs) are inflammatory triggers and belong to a family of pattern recognition receptors (PRRs) that are central to the regulation of host protective adaptive immune responses. Activation of TLRs in innate immune myeloid cells directs lymphocytes to produce the most appropriate effector responses to eliminate infection and maintain homeostasis of the body's internal environment. Inappropriate TLR stimulation can lead to the development of general autoimmune diseases as well as chronic and acute inflammation, and even cancer. Therefore, TLRs are expected to be targets for therapeutic treatment of inflammation-related diseases, autoimmune diseases, microbial infections, and human cancers. This review summarizes the recent discoveries in the molecular and structural biology of TLRs. The role of different TLR signaling pathways in inflammatory diseases, autoimmune diseases such as diabetes, cardiovascular diseases, respiratory diseases, digestive diseases, and even cancers (oral, gastric, breast, colorectal) is highlighted and summarizes new drugs and related clinical treatments in clinical trials, providing an overview of the potential and prospects of TLRs for the treatment of TLR-related diseases.

Tumor acidification and GSH depletion by bimetallic composite nanoparticles for enhanced chemodynamic therapy of TNBC

Chemodynamic therapy (CDT) based on intracellular Fenton reaction to produce highly cytotoxic reactive oxygen species (ROS) has played an essential role in tumor therapy. However, this therapy still needs to be improved by weakly acidic pH and over-expression of glutathione (GSH) in tumor microenvironment (TEM), which hinders its future application. Herein, we reported a multifunctional bimetallic composite nanoparticle MnO2@GA-Fe@CAI based on a metal polyphenol network (MPN) structure, which could reduce intracellular pH and endogenous GSH by remodeling tumor microenvironment to improve Fenton activity. MnO2 nanoparticles were prepared first and MnO2@GA-Fe nanoparticles with Fe3+ as central ion and gallic acid (GA) as surface ligands were prepared by the chelation reaction. Then, carbonic anhydrase inhibitor (CAI) was coupled with GA to form MnO2@GA-Fe@CAI. The properties of the bimetallic composite nanoparticles were studied, and the results showed that CAI could reduce intracellular pH. At the same time, MnO2 could deplete intracellular GSH and produce Mn2+ via redox reactions, which re-established the TME with low pH and GSH. In addition, GA reduced Fe3+ to Fe2+. Mn2+ and Fe2+ catalyzed the endogenous H2O2 to produce high-lever ROS to kill tumor cells. Compared with MnO2, MnO2@GA-Fe@CAI could reduce the tumor weight and volume for the xenograft MDA-MB-231 tumor-bearing mice and the final tumor inhibition rate of 58.09 ± 5.77%, showing the improved therapeutic effect as well as the biological safety. Therefore, this study achieved the high-efficiency CDT effect catalyzed by bimetallic through reshaping the tumor microenvironment.

Genome-wide expression profiling reveals novel biomarkers in epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most aggressive and frequent malignancy detected among women worldwide. The pathophysiology of OC should, therefore be better understood to identify diagnostic, prognostic, and predictive novel biomarkers necessary for early detection, management, and prognostication. In this study, we aimed to investigate transcriptomic landscape and biomarker through RNA-seq data analysis. Further analysis by Protein Protein network identified top 10 Differentially Expressed Genes (DEGs). KEGG pathway enrichment analysis revealed the significant enrichment of DEGs in basal cell carcinoma, cell cycle and FoxO signalling pathway. The RNA-seq results of 10 DEGs were validated by QRT-PCR and TCGA database. Correlation studies were also performed between gene expression and clinical characteristics followed by survival analysis. Finally, 8 DEGs (CDKN1A, BCL6, CDC45, WNT2, TLR5, AQP5) including two novel DEGs (CSN1S1 and NKILA) were identified showing significant correlations with EOC characteristics. These may serve as interesting biomarkers and novel treatment targets and warrant further investigation into the functional outcome of EOC.

Association between TLR2, TLR4, and TLR5 genetic variants and the risk of hepatocellular carcinoma in Moroccan population

Hepatocellular carcinoma (HCC) is the fifth most common human malignancy and the fourth most frequent cause of cancer-related deaths worldwide. Toll-like receptors (TLRs), are known to play a key role in hepatocarcinogenesis through induction of inflammation. We aimed to investigate the association between TLR2 rs3804099, TLR4 rs4986790, rs4986791, and rs11536889 and TLR5 rs5744174 and HCC risk in a total of 306 Moroccan subjects, including 152 HCC patient and 154 controls using a TaqMan allelic discrimination assay. Our result showed that the frequency of TLR4 rs11536889 C allele was higher in control group than in HCC patients (OR = 0.52, 95% CI = 0.30-0.88, p = 0.01). Moreover, under the dominant model, we observed that CG/CC genotypes were protective factors against HCC risk (OR = 0.51, 95% CI = 0.28-0.91, p = 0.02). However, no significant differences were found in the allele and genotype frequencies of TLR4 rs4986790 and rs4986791, between HCC patients and controls. Similarly, genotypic frequencies of TLR2 and TLR5 polymorphisms did not differ significantly between HCC patients and controls. However, TLR4 haplotype analysis revealed that ACC haplotype may be protective of HCC risk in patients with HCC (OR = 0.53, 95% CI = 0.31-0.92, p = 0.02). In conclusion, our result suggest that TLR4 rs11536889 polymorphism and ACC haplotype may decrease risk of hepatocellular carcinoma in Moroccan population.

PA-MSHA induces inflamed tumor microenvironment and sensitizes tumor to anti-PD-1 therapy

A low response rate to immune checkpoint inhibitor (ICI) therapy has impeded its clinical use. As reported previously, an inflamed tumor microenvironment (TME) was directly correlated with patients' response to immune checkpoint blockade (ICB). Thus, restoring the cytotoxic effect of immune cells in the TME is a promising way to improve the efficacy of ICB and overcome primary resistance to immunotherapy. The effect of Pseudomonas aeruginosa mannose-sensitive-hemagglutinin (PA-MSHA) in facilitating T cell activation was determined in vitro and in vivo. Subsets of immune cells were analyzed by flow cytometry. Proteomics was carried out to comprehensively analyze the discriminated cellular kinases and transcription factors. The combinational efficacy of PA-MSHA and αPD-1 therapy was studied in vivo. In this study we demonstrated that PA-MSHA, which is a clinically used immune adjuvant, effectively induced the anti-tumor immune response and suppressed the growth of non-small cell lung cancer (NSCLC) cells. PA-MSHA showed great potential to sensitize refractory "cold" tumors to immunotherapy. It effectively enhanced macrophage M1 polarization and induced T cell activation. In vivo, in combination with αPD-1, PA-MSHA suppressed tumor growth and prolonged the survival time of allograft model mice. These results indicate that PA-MSHA is a potent agent to stimulate immune cells infiltration into the TME and consequently induces inflammation in tumors. The combination of PA-MSHA with αPD-1 is a potential strategy to enhance the clinical response rate to ICI therapy.

Antibacterial activity of peptaibols from Trichoderma longibrachiatum SMF2 against gram-negative Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight on rice

Bacterial leaf blight caused by Gram-negative pathogen Xanthomonas oryzae pv. oryzae (Xoo) is one of the most destructive bacterial diseases on rice. Due to the resistance, toxicity and environmental issues of chemical bactericides, new biological strategies are still in need. Although peptaibols produced by Trichoderma spp. can inhibit the growth of several Gram-positive bacteria and plant fungal pathogens, it still remains unclear whether peptaibols have anti-Xoo activity to control bacterial leaf blight on rice. In this study, we evaluated the antibacterial effects of Trichokonins A (TKA), peptaibols produced by Trichoderma longibrachiatum SMF2, against Xoo. The in vitro antibacterial activity analysis showed that the growth of Xoo was significantly inhibited by TKA, with a minimum inhibitory concentration of 54 μg/mL and that the three TKs in TKA all had remarkable anti-Xoo activity. Further inhibitory mechanism analyses revealed that TKA treatments resulted in the damage of Xoo cell morphology and the release of intracellular substances, such as proteins and nucleic acids, from Xoo cells, suggesting the damage of the permeability of Xoo cell membrane by TKA. Pathogenicity analyses showed that the lesion length on rice leaf was significantly reduced by 82.2% when treated with 27 μg/mL TKA. This study represents the first report of the antibacterial activity of peptaibols against a Gram-negative bacterium. Thus, TKA can be of a promising agent in controlling bacterial leaf blight on rice.

Effect of chronic stress on tumorigenesis and development

Chronic stress activates the sympathetic nervous system (SNS) and hypothalamic-pituitary-adrenal (HPA) axis to aggravates tumorigenesis and development. Although the importance of SNS and HPA in maintaining homeostasis has already attracted much attention, there is still a lot remained unknown about the molecular mechanisms by which chronic stress influence the occurrence and development of tumor. While some researches have already concluded the mechanisms underlying the effect of chronic stress on tumor, complicated processes of tumor progression resulted in effects of chronic stress on various stages of tumor remains elusive. In this reviews we concluded recent research progresses of chronic stress and its effects on premalignancy, tumorigenesis and tumor development, we comprehensively summarized the molecular mechanisms in between. And we highlight the available treatments and potential therapies for stressed patients with tumor.

Noninvasive Evaluation of EGFR Expression of Digestive Tumors Using 99mTc-MAG3-Cet-F(ab ′ )2-Based SPECT/CT Imaging

Purpose. This study is aimed at investigating the feasibility of cetuximab (Cet) F(ab ${}^{\prime }$ )2 fragment- (Cet-F(ab ${}^{\prime }$ )2-) based single photon emission tomography/computed tomography (SPECT/CT) for assessing the epidermal growth factor receptor (EGFR) expression in digestive tumor mouse models. Methods. Cet-F(ab ${}^{\prime }$ )2 was synthesized using immunoglobulin G-degrading enzyme of Streptococcus pyogenes (IdeS) protease and purified with protein A beads. The product and its in vitro stability in normal saline and 1% bovine serum albumin were analyzed with sodium dodecyl sulfate–polyacrylamide gel electrophoresis. The EGFR expression in the human colon tumor cell line HT29 and the human stomach tumor cell line MGC803 were verified using western blotting and immunocytochemistry. Cet-F(ab ${}^{\prime }$ )2 was conjugated with 5(6)-carboxytetramethylrhodamine succinimidyl ester to demonstrate its binding ability to the MGC803 and HT29 cells. Cet-F(ab ${}^{\prime }$ )2 was conjugated with NHS-MAG3 for 99mTc radiolabeling. The best imaging time was determined using a biodistribution assay at 1, 4, 16, and 24 h after injection of the 99mTc-MAG3-Cet-F(ab ${}^{\prime }$ )2 tracer. Furthermore, 99mTc-MAG3-Cet-F(ab ${}^{\prime }$ )2 SPECT/CT was performed on MGC803 and HT29 tumor-bearing nude mice. Results. HT29 cells had low EGFR expression while MGC803 cell exhibited the high EGFR expression. Cet-F(ab ${}^{\prime }$ )2 and intact cetuximab showed similar high binding ability to MGC803 cells but not to HT29 cells. Cet-F(ab ${}^{\prime }$ )2 and 99mTc-MAG3-Cet-F(ab ${}^{\prime }$ )2 showed excellent in vitro stability. The biodistribution assay showed that the target to nontarget ratio was the highest at 16 h ( $17.29\pm 5.72$ , $n=4$ ) after tracer injection. The 99mTc-MAG3-Cet-F(ab ${}^{\prime }$ )2-based SPECT/CT imaging revealed rapid and sustained tracer uptake in MGC803 tumors rather than in HT29 tumors with high image contrast, which was consistent with the results in vitro. Conclusion. SPECT/CT imaging using 99mTc-MAG3-Cet-F(ab ${}^{\prime }$ )2 enables the evaluation of the EGFR expression in murine EGFR-positive tumors, indicating the potential utility for noninvasive evaluation of the EGFR expression in tumors.

Microbial-Derived Toll-like Receptor Agonism in Cancer Treatment and Progression

Simple Summary

Toll like receptors (TLRs) are a group of transmembrane receptors belonging to the class of pattern recognition receptors (PRR), which are involved in recognition of pathogen associated molecular patterns (PAMPs), inducing immune response. During the past decade, a number of preclinical and clinical breakthroughs in the field of TLR agonists has immerged in cancer research and some of these agents have performed exceptionally well in clinical trials. Based on evidence from scientific studies, we draw attention to several microbial based TLR agonists and discuss their relevance in various cancer and explore various microbial based TLR agonists for developing effective immunotherapeutic strategies against cancer.

Abstract

Toll-like receptors (TLRs) are typical transmembrane proteins, which are essential pattern recognition receptors in mediating the effects of innate immunity. TLRs recognize structurally conserved molecules derived from microbes and damage-associated molecular pattern molecules that play an important role in inflammation. Since the first discovery of the Toll receptor by the team of J. Hoffmann in 1996, in Drosophila melanogaster, numerous TLRs have been identified across a wide range of invertebrate and vertebrate species. TLR stimulation leads to NF-κB activation and the subsequent production of pro-inflammatory cytokines and chemokines, growth factors and anti-apoptotic proteins. The expression of TLRs has also been observed in many tumors, and their stimulation results in tumor progression or regression, depending on the TLR and tumor type. The anti-tumoral effects can result from the activation of anti-tumoral immune responses and/or the direct induction of tumor cell death. The pro-tumoral effects may be due to inducing tumor cell survival and proliferation or by acting on suppressive or inflammatory immune cells in the tumor microenvironment. The aim of this review is to draw attention to the effects of TLR stimulation in cancer, the activation of various TLRs by microbes in different types of tumors, and, finally, the role of TLRs in anti-cancer immunity and tumor rejection.

SKA3 is a prognostic biomarker and associated with immune infiltration in bladder cancer

BACKGROUND

Spindle and kinetochore‑associated complex subunit 3 (SKA3) has recently been considered a key regulator of carcinogenesis. However, the connection between SKA3 and immune cell infiltration remains unknown.

METHODS

The current study investigated the expression mode, prognostic effect, and functional role of SKA3 in different tumors, particularly bladder cancer using numerous databases, comprising TIMER, GEPIA, HPA, UALCAN, PrognoScan, and Kaplan-Meier Plotter. Differentially expressed gene and enrichment analyses were implemented on SKA3 using R packages "edgR" and "clusterProfiler". Immunohistochemistry was further used to validate the expression of SKA3 gene in bladder cancer. Following that, the relevance of SKA3 expression to immune infiltration level in bladder cancer was evaluated using TIMER.

RESULTS

Overall, the level of SKA3 expression in tumor tissue significantly increased than in normal tissue. In bladder cancer and other tumors, patients with high SKA3 expression levels had worse overall survival (OS) (p = 0.016), disease-specific survival (DSS) (p = 0.00004), and disease-free survival (DFS) (p = 0.032). Additionally, the major molecular functions for SKA3 included nuclear division, mitotic nuclear division, mitotic sister chromatid segregation, humoral immune response, and cell chemotaxis. Additionally, SKA3 expression was found to be positively associated with enhanced M2 macrophage and T helper (Th) 2 cell infiltration in bladder cancer.

CONCLUSIONS

Our study implies that SKA3 contributes to M2 macrophage and Th2 cell polarization by acting as an oncogene in bladder cancer. SKA3 might be a novel biomarker for evaluating prognosis and immune infiltration in bladder cancer.

Synthesis and Evaluation of 68Ga-NOTA-COG1410 Targeting to TREM2 of TAMs as a Specific PET Probe for Digestive Tumor Diagnosis

Currently, positron emission tomography/computed tomography (PET/CT) is an important method for the discovery and diagnosis of digestive system tumors. However, the shortage of specific imaging tracer limits the effectiveness of PET. Triggering receptor expressed on myeloid cells 2 (TREM2) as an M2-type macrophage biomarker is receiving much attention considering its high abundance and specificity, which could be an ideal target for PET imaging. First, the expression of TREM2 in tumors and corresponding normal tissues was analyzed using a database and was verified by tissue microarrays and murine model slices, and we found that the expression of TREM2 in tumor tissues was significantly higher than that in normal tissues and enteritis tissues. Then, we established a macrophage co-culture system to obtain tumor-associated macrophages (TAMs). Compared with M1-type macrophages and tumor cells, TAMs had a higher expression level of TREM2. The novel radioligand ⁶⁸Ga-NOTA-COG1410 was successfully synthesized for TREM2 targeting PET imaging. The biodistribution and micro-PET/CT results showed high uptake of ⁶⁸Ga-NOTA-COG1410 in the tumor but not in areas of inflammation. The data testified that ⁶⁸Ga-NOTA-COG1410 was a specific radioligand targeting TREM2, which could be used to distinguish tumors from inflammation. Using ⁶⁸Ga-NOTA-COG1410, the effectiveness of PET on digestive tumors imaging may be enhanced.

Down-Regulation of Toll-Like Receptor 5 (TLR5) Increased VEGFR Expression in Triple Negative Breast Cancer (TNBC) Based on Radionuclide Imaging

In this study, GFP-tagged TNBC 4T1 cells with down-regulated TLR5 expression (TLR5- 4T1) and normal TLR5 expression (TLR5+ 4T1) were constructed, respectively. RT-PCR and Western blot studies showed that down-regulation of TLR5 obviously increased the expression of VEGFR in 4T1 cells. Highly stable radio-probes 125I-anti-TLR5 mAb/125I-VEGF/125I-IgG were obtained with labeling rates over 85% and radiochemical purities above 90%. Among these three probes, 125I-anti-TLR5 mAb and 125I-VEGF were used for specifically imaging TNBC, while 125I-IgG was used for comparison. Whole-body phosphorus autoradiography showed clear imaging at 48 h after injection of 125I-anti-TLR5 mAb and 125I-VEGF also provided clear imaging at 24 h. Biodistribution study demonstrated a higher tumor uptake of 125I-anti-TLR5 mAb in TLR5+ group compared with that in TLR5- group (P < 0.05), whereas tumor uptake of 125I-VEGF in TLR5+ group was lower than that in the TLR5- group (P < 0.05). Immunohistochemical staining suggested that the expression of TLR5 was lower, whereas the expression of VEGFR, CD31, and MVD (microvessel density) was higher in TLR5- tumor-bearing mice. In summary, the down-regulation of TLR5 in TNBC promoted the VEGFR expression and angiogenesis, resulting in the proliferation of TNBC cells. TLR5/VEGF might be a better indicator for monitoring the development of TNBC.

Resibufogenin Suppresses Triple-Negative Breast Cancer Angiogenesis by Blocking VEGFR2-Mediated Signaling Pathway

Resibufogenin (RBF), an active compound from Bufo bufonis, has been used for the treatment of multiple malignant cancers, including pancreatic cancer, colorectal cancer, and breast cancer. However, whether RBF could exert its antitumor effect by inhibiting angiogenesis remains unknown. Here, we aimed to explore the antiangiogenic activity of RBF and its underlying mechanism on human umbilical vein endothelial cell (HUVEC), and the therapeutic efficacy with regard to antiangiogenesis in vivo using two triple-negative breast cancer (TNBC) models. Our results demonstrated that RBF can inhibit the proliferation, migration, and tube formation of HUVECs in a dose-dependent manner. Spheroid sprouts were thinner and shorter after RBF treatment in vitro 3D spheroid sprouting assay. RBF also significantly suppressed VEGF-mediated vascular network formation in vivo Matrigel plug assay. In addition, Western blot analysis was used to reveal that RBF inhibited the phosphorylation of VEGFR2 and its downstream protein kinases FAK and Src in endothelial cells (ECs). Molecular docking simulations showed that RBF affected the phosphorylation of VEGFR2 by competitively binding to the ATP-bound VEGFR2 kinase domain, thus preventing ATP from providing phosphate groups. Finally, we found that RBF exhibited promising antitumor effect through antiangiogenesis in vivo without obvious toxicity. The present study first revealed the high antiangiogenic activity and the underlying molecular basis of RBF, suggesting that RBF could be a potential antiangiogenic agent for angiogenesis-related diseases.

Patient-Specific Network for Personalized Breast Cancer Therapy with Multi-Omics Data

The development of new computational approaches that are able to design the correct personalized drugs is the crucial therapeutic issue in cancer research. However, tumor heterogeneity is the main obstacle to developing patient-specific single drugs or combinations of drugs that already exist in clinics. In this study, we developed a computational approach that integrates copy number alteration, gene expression, and a protein interaction network of 73 basal breast cancer samples. 2509 prognostic genes harboring a copy number alteration were identified using survival analysis, and a protein–protein interaction network considering the direct interactions was created. Each patient was described by a specific combination of seven altered hub proteins that fully characterize the 73 basal breast cancer patients. We suggested the optimal combination therapy for each patient considering drug–protein interactions. Our approach is able to confirm well-known cancer related genes and suggest novel potential drug target genes. In conclusion, we presented a new computational approach in breast cancer to deal with the intra-tumor heterogeneity towards personalized cancer therapy.

B7-H3 confers resistance to Vγ9Vδ2 T cell-mediated cytotoxicity in human colon cancer cells via the STAT3/ULBP2 axis

Immunotherapy based on γδT cells has limited efficiency in solid tumors, including colon cancer (CC). The immune evasion of tumor cells may be the main cause of the difficulties of γδT cell-based treatment. In the present study, we explored whether and how B7-H3 regulates the resistance of CC cells to the cytotoxicity of Vγ9Vδ2 (Vδ2) T cells. We observed that B7-H3 overexpression promoted, while B7-H3 knockdown inhibited, CC cell resistance to the killing effect of Vδ2 T cells in vitro and in vivo. Mechanistically, we showed that B7-H3-mediated CC cell resistance to the cytotoxicity of Vδ2 T cells involved a molecular pathway comprising STAT3 activation and decreased ULBP2 expression. ULBP2 blockade or knockdown abolished the B7-H3 silencing-induced increase in the cytotoxicity of Vδ2 T cells to CC cells. Furthermore, cryptotanshinone, a STAT3 phosphorylation inhibitor, reversed the B7-H3 overexpression-induced decrease in ULBP2 expression and attenuated the killing effect of Vδ2 T cells on CC cells. Moreover, there was a negative correlation between the expression of B7-H3 and ULBP2 in the tumor tissues of CC patients. Our results suggest that the B7-H3-mediated STAT3/ULBP2 axis may be a potential candidate target for improving the efficiency of γδT cell-based immunotherapy in CC.

FBI-1 enhanced the resistance of triple-negative breast cancer cells to chemotherapeutic agents via the miR-30c/PXR axis

The factor that binds to the inducer of short transcripts-1 (FBI-1) is a transcription suppressor and an important proto-oncogene that plays multiple roles in carcinogenesis and therapeutic resistance. In the present work, our results indicated that FBI-1 enhanced the resistance of triple-negative breast cancer (TNBC) cells to chemotherapeutic agents by repressing the expression of micoRNA-30c targeting the pregnane X receptor (PXR). The expression of FBI-1 was positively related to PXR and its downstream drug resistance-related genes in TNBC tissues. FBI-1 enhanced the expression of PXR and enhanced the activation of the PXR pathway. The miR-30c decreased the expression of PXR by targeting the 3'-UTR of PXR, and FBI-1 increased the expression of PXR by repressing miR-30c's expression. Through the miR-30c/PXR axis, FBI-1 accelerated the clearance or elimination of antitumor agents in TNBC cells (the TNBC cell lines or the patients derived cells [PDCs]) and induced the resistance of cells to antitumor agents. Therefore, the results indicated that the miR-30c/PXR axis participates in the FBI-1-mediated drug-resistance of TNBC cells.

The relationship between TRAF6 and tumors

Tumor necrosis factor receptor (TNFR)-related factors (TRAFs) are important linker molecules in the tumor necrosis factor superfamily (TNFSF) and the Toll-like/interleukin-1 receptor (TLR/ILR) superfamily. There are seven members: TRAF1-TRAF7, among those members, tumor necrosis factor receptor-associated factor 6 (TRAF6) is upregulated in various tumors, which has been related to tumorigenesis and development. With the in-depth study of the relationship between TRAF6 and different types of tumors, TRAF6 has oncogenic characteristics involved in tumorigenesis, tumor development, invasion, and metastasis through various signaling pathways, therefore, targeting TRAF6 has provided a novel strategy for tumor treatment. This review summarizes and analyzes the role of TRAF6 in tumorigenesis and tumor development in combination with the current research on TRAF6 and tumors.

Combined administration of a small-molecule inhibitor of TRAF6 and Docetaxel reduces breast cancer skeletal metastasis and osteolysis

Tumour necrosis factor receptor-associated factor 6 (TRAF6) has been implicated in breast cancer and osteoclastic bone destruction. Here, we report that 6877002, a verified small-molecule inhibitor of TRAF6, reduced metastasis, osteolysis and osteoclastogenesis in models of osteotropic human and mouse breast cancer. First, we observed that TRAF6 is highly expressed in osteotropic breast cancer cells and its level of expression was higher in patients with bone metastasis. Pre-exposure of osteoclasts and osteoblasts to non-cytotoxic concentrations of 6877002 inhibited cytokine-induced NFκB activation and osteoclastogenesis, and reduced the ability of osteotropic human MDA-MB-231 and mouse 4T1 breast cancer cells to support bone cell activity. 6877002 inhibited human MDA-MB-231-induced osteolysis in the mouse calvaria organ system, and reduced soft tissue and bone metastases in immuno-competent mice following intra-cardiac injection of mouse 4T1-Luc2 cells. Of clinical relevance, combined administration of 6877002 with Docetaxel reduced metastasis and inhibited osteolytic bone damage in mice bearing 4T1-Luc2 cells. Thus, TRAF6 inhibitors such as 6877002 - alone or in combination with conventional chemotherapy - show promise for the treatment of metastatic breast cancer.