NRF2 Is One of the Players Involved in Bone Marrow Mediated Drug Resistance in Multiple Myeloma

Hypoxia induces chemoresistance to proteasome inhibitors through orchestrating deSUMOylation and ubiquitination of SRC-3 in multiple myeloma

The bone marrow microenvironment in multiple myeloma (MM) is hypoxic and provides multi-advantages for the initiation of chemoresistance, but the underlying mechanisms and key regulators are still indistinct. In the current study, we found that hypoxia stimulus easily induced chemoresistance to proteasome inhibitors (PIs), and the steroid receptor coactivator 3 (SRC-3) expression was remarkably augmented at posttranslational level. Protein interactome analysis identified SENP1 as a key modifier of SRC-3 stability, as SENP1-mediated deSUMOylation attenuated the K11-linked polyubiquitination of SRC-3. SENP1 depletion in the SENP1^fl/flCD19^Cre/+ B cells showed impaired SRC3 stability, and knockdown of SENP1 in MM cells by CRISPR/cas9 sgRNA accelerated the degradation of SRC-3 and remarkably overcame the resistance to PIs. In the Vk*Myc and 5TGM1 mouse models as well as patient-derived xenograft (PDX) of myeloma, SENP1 inhibitor Momordin Ιc (Mc) increased the sensitivity to PIs in MM cells. Importantly, SENP1 level was positively correlated with SRC-3 level in the tissues from refractory/relapsed MM, as well as in xenograft tissues from mice treated with bortezomib and Mc. Taken together, our findings suggest that hypoxia-induced SENP1 is a crucial regulator of chemoresistance to PIs, and shed light on developing therapeutic strategies to overcome chemoresistance by using small molecules targeting SENP1 or SRC-3.

Interaction of saffron and its constituents with Nrf2 signaling pathway: A review

Saffron (Crocus sativus) is a natural compound and its constituents such as crocin, crocetin, and safranal have many pharmacological properties such as anti-oxidant, anti-inflammatory, antitumor, antigenotoxic, anti-depressant, hepatoprotective, cardioprotective, and neuroprotective. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway plays an important role against inflammation, oxidative stress, and carcinogenesis. In the regulation of the Nrf2 signaling pathway, kelch-like ECH-associated protein 1 (keap1) is the most studied pathway. In this review, we gathered various studies and describe the pharmacological effects of saffron and its constituents with their related mechanisms of action, particularly the Nrf2 signaling pathway. In this review, we used search engines or electronic databases including Scopus, Web of Science, and Pubmed, without time limitation. The search keywords contained saffron, "Crocus sativus", crocetin, crocin, safranal, picrocrocin, "nuclear factor erythroid 2-related factor 2", and Nrf2. Saffron and its constituents could have protective properties through various mechanisms particularly the Nrf2/HO-1/Keap1 signaling pathway in different tissues such as the liver, heart, brain, pancreas, lung, joints, colon, etc. The vast majority of studies discussed in this review indicate that saffron and its constituents could induce the Nrf2 signaling pathway leading to its anti-oxidant and therapeutic effects.

Solute Carrier Family 27 Member 6 (SLC27A6) Possibly Promotes the Proliferation of Papillary Thyroid Cancer by Regulating c-MYC

To investigate the expression and mechanism of LSC27A6 in papillary thyroid cancer (PTC). We analyzed the differential expression of SLC27A6 in PTC tissues and normal tissues based on the TCGA database and validated it using immunohistochemistry. Wilcoxon rank sum, chi-square test, or Fisher exact exam were used to analyze the relationship between the expression of SLC27A6 and clinicopathological information. Samples were divided into two groups according to whether BRAF was mutated or not, and Wilcoxon rank sum was used to determine whether the expression of SLC27A6 was related to BRAF mutation. The effects of SLC27A6 on the proliferation, migration, and apoptosis of PTC cells were detected by cell counting kit-8 (CCK8), colony formation assay, transwell assay, and flow cytometry. Spearman correlation analysis was used to evaluate the relationship between SLC27A6 and c-MYC. Protein expression was detected by Western blot. The expression of SLC27A6 was higher in PTC and positively correlated with N stage. SLC27A6 expression was higher in samples with BRAF mutations. Down-regulation of SLC27A6 inhibited cell proliferation, migration, and invasion and induced apoptosis. Spearman correlation analysis showed that SLC27A6 was positively correlated with c-MYC. Knockdown of SLC27A6 inhibited c-MYC expression. Our results suggest that SLC27A6 is overexpressed in PTC tissues and affects the progression of PTC by regulating c-MYC.

The role of the Nrf2/Keap1 signaling cascade in mechanobiology and bone health

In conjunction with advancements in modern medicine, bone health is becoming an increasingly prevalent concern among a global population with an ever-growing life expectancy. Countless factors contribute to declining bone strength, and age exacerbates nearly all of them. The detrimental effects of bone loss have a profound impact on quality of life. As such, there is a great need for full exploration of potential therapeutic targets that may provide antiaging benefits and increase the life and strength of bone tissues. The Keap1-Nrf2 pathway is a promising avenue of this research. The cytoprotective and antioxidant functions of this pathway have been shown to mitigate the deleterious effects of oxidative stress on bone tissues, but the exact cellular and molecular mechanisms by which this occurs are not yet fully understood. Presently, refined animal and loading models are allowing exploration into the effect of the Keap1-Nrf2 pathway in a tissue-specific or even cell-specific manner. In addition, Nrf2 activators currently undergoing clinical trials can be utilized to investigate the particular cellular mechanisms at work in this cytoprotective cascade. Although the timing and dosing of treatment with Nrf2 activators need to be further investigated, these activators have great potential to be used clinically to prevent and treat osteoporosis.

Microribonucleic Acid-15a-5p Alters Adriamycin Resistance in Breast Cancer Cells by Targeting Cell Division Cycle-Associated Protein 4

Objective

Although chemotherapy is one of the first line clinical treatment of tumors, the efficacy of chemotherapy has been severely restricted by the frequent occurrence of drug resistance phenomenon. Multiple studies found that miRNAs can regulate the chemosensitivity of tumor cells. Here, this study aimed to assess the potential role of the miR-15a-5p/cell division cycle-related protein 4 (CDCA4) axis in breast cancer (BC) resistance to Adriamycin.

Methods

In the present study, the relative expression of miRNA-15a-5p in MCF-7/ADR, MCF-7 and Hs578Bst was measured by qRT-PCR. MCF-7/ADR cells underwent transfection with an miR-15a-5p mimic and inhibitor, respectively. Transwell assays, flow cytometry and CCK8 were performed to examine the potential effects of the abnormal expression of miR-15a-5p. The association of aberrant miR-15a-5p expression with Adriamycin resistance in BC was determined in cultured MCF-7/ADR cells. Bioinformatics was employed to predict the genes targeted by miR-15a-5p. Moreover, the correlation between miR-15a-5p and its target gene, CDCA4, was evaluated based on qRT-PCR data.

Results

The expression of miR-15a-5p was significantly downregulated in MCF/ADR cells compared with MCF-7 and Hs578Bst cell lines. In the presence of Adriamycin, miR-15a-5p overexpression significantly increased cell chemosensitivity, as well as MCF-7/ADR cell proliferation, invasion, and migration, while promoting apoptosis and inducing cell-cycle arrest in the synthesis phase. CDCA4 RNA interference enhanced these effects as shown in our previous study. Bioinformatics identified CDCA4 as an miR-15a-5p target gene. qRT-PCR further demonstrated that CDCA4 and miR-15a-5p expression levels were inversely correlated.

Conclusion

Adriamycin resistance in BC cells was, at least in part, altered by mRNA-15a-5p via regulation of its target gene, CDCA4, by controlling the cell cycle, which may provide some novel ideas for BC chemotherapy in the future.

An Overview of the Genomic Characterization of Hepatocellular Carcinoma

Tumor classifications based on alterations in the genome, epigenome, or proteome have revealed distinct tumor subgroups that are associated with clinical outcomes. Several landmark studies have demonstrated that such classifications can significantly improve patient outcomes by enabling tailoring of therapy to specific alterations in cancer cells. Since cancer cells accumulate numerous alterations in many cancer-related genes, it is a daunting task to find and confirm important cancer-promoting alterations as therapeutic targets or biomarkers that can predict clinical outcomes such as survival and response to treatments. To aid further advances, we provide here an overview of the current understanding of molecular and genomic subtypes of hepatocellular carcinoma (HCC). System-level integration of data from multiple studies and development of new technical platforms for analyzing patient samples hold great promise for the discovery of new targets for treatment and correlated biomarkers, leading to personalized medicine for treatment of HCC patients.

Identification of Beilschmiedia tsangii Root Extract as a Liver Cancer Cell-Normal Keratinocyte Dual-Selective NRF2 Regulator

Transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) plays a crucial role in regulating the expression of genes participating in cellular defense mechanisms against oxidative or xenobiotic insults. However, there is increasing evidence showing that hyperactivation of NRF2 is associated with chemoresistance in several cancers, including hepatocellular carcinoma (HCC), thus making NRF2 an attractive target for cancer therapy. Another important issue in cancer medication is the adverse effects of these substances on normal cells. Here, we attempted to identify a dual-selective NRF2 regulator that exerts opposite effects on NRF2-hyperactivated HCC cells and normal keratinocytes. An antioxidant response element driven luciferase reporter assay was established in Huh7 and HaCaT cells as high-throughput screening platforms. Screening of 3,000 crude extracts from the Taiwanese Indigenous Plant Extract Library resulted in the identification of Beilschmiedia tsangii (BT) root extract as a dual-selective NRF2 regulator. Multiple compounds were found to contribute to the dual-selective effects of BT extract on NRF2 signaling in two cell lines. BT extract reduced NRF2 protein level and target gene expression levels in Huh7 cells but increased them in HaCaT cells. Furthermore, notable combinatory cytotoxic effects of BT extract and sorafenib on Huh7 cells were observed. On the contrary, sorafenib-induced inflammatory reactions in HaCaT cells were reduced by BT extract. In conclusion, our results suggest that the combination of a selective NRF2 activator and inhibitor could be a practical strategy for fine-tuning NRF2 activity for better cancer treatment and that plant extracts or partially purified fractions could be a promising source for the discovery of dual-selective NRF2 regulators.

Management of Myeloma Bone Lesions

Multiple myeloma (MM) is a B-cell neoplasm characterized by clonal plasma-cell proliferation. The survival and prognosis of this condition have been significantly improved by treatment with active anti-MM drugs such as bortezomib or lenalidomide. Further, the discovery of novel agents has recently paved the way for new areas of investigation. However, MM, including myeloma-related bone diseases, remains fatal. Bone disease or bone destruction in MM is a consequence of skeletal involvement with bone pain, spinal cord compression, and bone fracture resulting from osteolytic lesions. These consequences affect disease outcomes, including patients' quality of life and survival. Several studies have sought to better understand MM bone disease (MBD) through the classification of its molecular mechanisms, including osteoclast activation and osteoblast inhibition. Bisphosphonates and the receptor activator of the nuclear factor-kappa B (NF-κB) ligand (RANKL) inhibitor, denosumab, prevent skeletal-related events in MM. In addition, several other bone-targeting agents, including bone-anabolic drugs, are currently used in preclinical and early clinical evaluations. This review summarizes the current knowledge of the pathogenesis of MBD and discusses novel agents that appear very promising and will soon enter clinical development.

Amino acid depletion triggered by ʟ-asparaginase sensitizes MM cells to carfilzomib by inducing mitochondria ROS-mediated cell death

Metabolic reprogramming is emerging as a cancer vulnerability that could be therapeutically exploitable using different approaches, including amino acid depletion for those tumors that rely on exogenous amino acids for their maintenance. ʟ-Asparaginase (ASNase) has contributed to a significant improvement in acute lymphoblastic leukemia outcomes; however, toxicity and resistance limit its clinical use in other tumors. Here, we report that, in multiple myeloma (MM) cells, the DNA methylation status is significantly associated with reduced expression of ASNase-related gene signatures, thus suggesting ASNase sensitivity for this tumor. Therefore, we tested the effects of ASNase purified from Erwinia chrysanthemi (Erw-ASNase), combined with the next-generation proteasome inhibitor (PI) carfilzomib. We observed an impressive synergistic effect on MM cells, whereas normal peripheral blood mononuclear cells were not affected. Importantly, this effect was associated with increased reactive oxygen species (ROS) generation, compounded mitochondrial damage, and Nrf2 upregulation, regardless of the c-Myc oncogenic-specific program. Furthermore, the cotreatment resulted in genomic instability and DNA repair mechanism impairment via increased mitochondrial oxidative stress, which further enhanced its antitumor activity. Interestingly, carfilzomib-resistant cells were found to be highly dependent on amino acid starvation, as reflected by their higher sensitivity to Erw-ASNase treatment compared with isogenic cells. Overall, by affecting several cellular programs, Erw-ASNase makes MM cells more vulnerable to carfilzomib, providing proof of concept for clinical use of this combination as a novel strategy to enhance PI sensitivity in MM patients.

Pathogenic Mechanisms of Myeloma Bone Disease and Possible Roles for NRF2

Osteolytic bone lesions are one of the central features of multiple myeloma (MM) and lead to bone pain, fractures, decreased quality of life, and decreased survival. Dysfunction of the osteoclast (OC)/osteoblast (OB) axis plays a key role in the development of myeloma-associated osteolytic lesions. Many signaling pathways and factors are associated with myeloma bone diseases (MBDs), including the RANKL/OPG and NF-κB pathways. NRF2, a master regulator of inflammatory signaling, might play a role in the regulation of bone metabolism via anti-inflammatory signaling and decreased reactive oxygen species (ROS) levels. The loss of NRF2 expression in OCs reduced bone mass via the RANK/RANKL pathway and other downstream signaling pathways that affect osteoclastogenesis. The NRF2 level in OBs could interfere with interleukin (IL)-6 expression, which is associated with bone metabolism and myeloma cells. In addition to direct impact on OCs and OBs, the activity of NRF2 on myeloma cells and mesenchymal stromal cells influences the inflammatory stress/ROS level in these cells, which has an impact on OCs, OBs, and osteocytes. The interaction between these cells and OCs affects the osteoclastogenesis of myeloma bone lesions associated with NRF2. Therefore, we have reviewed the effects of NRF2 on OCs and OBs in MBDs.

Baicalein enhanced cisplatin sensitivity of gastric cancer cells by inducing cell apoptosis and autophagy via Akt/mTOR and Nrf2/Keap 1 pathway

Baicalein is a natural flavonoid with various pharmacological activities including antitumor. The synergistic anti-cancer effect of the combination of baicalein and Cisplatin (DDP) on gastric cancer (GC) has not been reported. MTT assay and colony formation assay were used to determine the inhibitory effect of the combination of baicalein and DDP on cell survival. Invasive assay was performed to test the effects of baicalein and DDP on cell invasive capability. A flow cytometric analysis was conducted to determine the apoptosis-induced effects of baicalein on GC cells, especially SGC-7901/DDP (resistant to DDP). Confocal laser microscope and real-time PCR were used to test autophagy-induced effects of baicalein on SGC-7901 and SGC-7901/DDP cells. Western blotting was performed to investigate the molecular mechanisms of baicalein inducing apoptosis and autophagy. Our study showed that baicalein could inhibit cell proliferation of MGC-803, HGC-27, SGC-7901 and SGC-7901/DDP, and the inhibitory effect was extremely enhanced when combining with DDP. Additionally, combination of baicalein and DDP suppressed the invasive capability and induced apoptosis and autophagy in both SGC-7901 and SGC-7901/DDP, and the effect was stronger than that of DDP or baicalein alone. The further molecular mechanism analysis indicated that baicalein modulated the activities of Akt/mTOR and Nrf2/Keap 1 signaling. Our study demonstrated that baicalein enhanced DDP sensitivity of SGC-7901/DDP gastric cancer cells by inducing apoptosis and autophagy via Akt/mTOR and Nrf2/Keap 1 pathway.

Discovery of 4-Anilinoquinolinylchalcone Derivatives as Potential NRF2 Activators

Activation of nuclear factor erythroid-2-related factor 2 (NRF2) has been proven to be an effective means to prevent the development of cancer, and natural curcumin stands out as a potent NRF2 activator and cancer chemopreventive agent. In this study, we have synthesized a series of 4-anilinoquinolinylchalcone derivatives, and used a NRF2 promoter-driven firefly luciferase reporter stable cell line, the HaCaT/ARE cells, to screen a panel of these compounds. Among them, (E)-3-{4-[(4-acetylphenyl)amino]quinolin-2-yl}-1-(4-fluorophenyl)prop-2-en-1-one (13b) significantly increased NRF2 activity in the HaCaT cell with a half maximal effective concentration (EC₅₀) value of 1.95 μM. Treatment of compound 13b upregulated HaCaT cell NRF2 expression at the protein level. Moreover, the mRNA level of NRF2 target genes, heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic subunit (GCLC), and glucose-6-phosphate dehydrogenase (G6PD) were significantly increased in HaCaT cells upon the compound 13b treatment. The molecular docking results exhibited that the small molecule 13b is well accommodated by the bound region of Kelch-like ECH-associated protein 1 (Keap1)-Kelch and NRF2 through stable hydrogen bonds and hydrophobic interaction, which contributed to the enhancement of affinity and stability between the ligand and receptor. Compound 13b has been identified as the lead compound for further structural optimization.

Chemical Constituents with GNMT-Promoter-Enhancing and NRF2-Reduction Activities from Taiwan Agarwood Excoecaria formosana

Hepatocellular carcinoma (HCC) is considered to be a silent killer, and was the fourth leading global cause of cancer deaths in 2018. For now, sorafenib is the only approved drug for advanced HCC treatment. The introduction of additional chemopreventive agents and/or adjuvant therapies may be helpful for the treatment of HCC. After screening 3000 methanolic extracts from the Formosan plant extract bank, Excoecaria formosana showed glycine N-methyltransferase (GNMT)-promoter-enhancing and nuclear factor erythroid 2-related factor 2 (NRF2)-suppressing activities. Further, the investigation of the whole plant of E. formosana led to the isolation of a new steroid, 7α-hydroperoxysitosterol-3-O-β-d-(6-O-palmitoyl)glucopyranoside (1); two new coumarinolignans, excoecoumarin A (2) and excoecoumarin B (3); a new diterpene, excoeterpenol A (4); and 40 known compounds (5-44). Among them, Compounds 38 and 40-44 at a 100 μM concentration showed a 2.97 ± 0.27-, 3.17 ± 1.03-, 2.73 ± 0.23-, 2.63 ± 0.14-, 6.57 ± 0.13-, and 2.62 ± 0.05-fold increase in GNMT promoter activity, respectively. In addition, Compounds 40 and 43 could reduce NRF2 activity, a transcription factor associated with drug resistance, in Huh7 cells with relative activity of 33.1 ± 0.2% and 45.2 ± 2.5%. These results provided the basis for the utilization of Taiwan agarwood for the development of anti-HCC agents.

Therapeutic and biological activities of berberine: The involvement of Nrf2 signaling pathway

Since the beginning of the 21st century, studies have focused on developing drugs from naturally occurring compounds. Berberine (Brb) as a plant-derived compound is of interest. It is an isoquinone alkaloid which is derived from Berberis aristata, Berberis aquifolium and Berberis vulgaris. This plant-derived compound has a variety of pharmacological effects such as antioxidant, anti-inflammatory, antidiabetic, antidiarrheal, antitumor, antimicrobial, and anti-inflammatory. Various studies have demonstrated the therapeutic and biological activities of Brb, but there is a lack of a precise review to manifest the signaling pathway of action of Brb. The nuclear factor erythroid 2-related factor 2 (Nrf2) is a highly conserved pathway which mainly involves in preservation of redox balance. At the present review, we describe the therapeutic and biological activities of Brb as well as the relevant mechanisms specially focused on the Nrf2 signaling pathway.

New approach to evaluating the effects of a drug on protein complexes with quantitative proteomics, using the SILAC method and bioinformatic approach

Protein-protein interactions (PPIs) lead the formation of protein complexes that perform biochemical reactions that maintain the living state of the living cell. Although therapeutic drugs should influence the formation of protein complexes in addition to PPI network, the methodology analyzing such influences remain to be developed. Here, we demonstrate that a new approach combining HPLC (high performance liquid chromatography) for separating protein complexes, and the SILAC (stable isotope labeling using amino acids in cell culture) method for relative protein quantification, enable us to identify the protein complexes influenced by a drug. We applied this approach to the analysis of thalidomide action on HepG2 cells, assessed the identified proteins by clustering data analyses, and assigned 135 novel protein complexes affected by the drug. We propose that this approach is applicable to elucidating the mechanisms of actions of other therapeutic drugs on the PPI network, and the formation of protein complexes.