Boric acid induces cytoplasmic stress granule formation, eIF2α phosphorylation, and ATF4 in prostate DU-145 cells

Boric Acid Affects the Expression of DNA Double-Strand Break Repair Factors in A549 Cells and A549 Cancer Stem Cells: An In Vitro Study

DNA double-strand break (DSB) repair genes interact with tumor stemness- and resistance-associated processes in cancer stem cells (CSCs). Therefore, targeting DNA DSB genes in cancer treatment is important for the CSC phenotype. Although the anti-cancer effect of boric acid (BA) has been studied, its effect on DNA DSB is unclear. Moreover, no studies investigate BA's effects on DNA DSB of lung cancer stem cells (LC-SCs). To fill the gap, we aimed to assess the effects of BA on A549 cancer stem cells. CSCs were isolated from human non-small cell lung cancer cells (A549) and characterized by flow cytometry. Different concentrations of BA (at doses ranging from 1 to 100 mM) were applied to cancer stem cells. Cytotoxic activities were determined using the cell viability assay (MTT assay) at 24 and 48 h. Expression levels of DNA DSB genes that BRCA1, BRCA2, RAD51, KU70/80, ATM, and XRCC4 were evaluated by RT-qPCR. Additionally, immunofluorescence staining analysis was exploited for caspase-3 and E-cadherin. ATM expression increased significantly (p < 0.001). No significant change was observed in the expression of other genes. Moreover, BA up-regulated caspase-3 and E-cadherin expression. Consequently, we can say that BA affects DNA DSB and the apoptotic abilities of LC-SCs.

Boric Acid Alters the Expression of DNA Double Break Repair Genes in MCF-7-Derived Breast Cancer Stem Cells

Breast cancer pathology ranks second in mortality among women worldwide due to the resistance of cancer stem cells in tumor tissue to radiotherapy and chemotherapy and their effective DNA damage response system (DDR). Targeting the expression of DNA double-strand break (DSB) repair genes in breast cancer stem cells (BC-SCs) is essential for facilitating their elimination with conventional therapies. This study aims to investigate the effects of boric acid (BA) on the expression of DNA DSB repair genes in BC-SCs, which has not been studied in the literature before. BS-SCs were isolated by the MACS method and characterized by flow cytometry. The effects of BA on BC-SCs' DNA DSB repair genes were deciphered by cell viability assay, inverted microscopy, and RT-qPCR. While the expression of the BRCA1 and BRCA2 was upregulated, the expression of the ATM (p < 0.001), RAD51 (p < 0.001), and KU70 (p < 0.001) was downregulated in dose-treated BC-SCs (p < 0.001) to the qPCR results. Consequently, BA affects some of the DNA DSB repair genes of breast cancer stem cells. Findings from this study could provide new insights into the potential therapeutic application of BA in BC-SC elimination and cancer intervention.

Boric Acid Affects Cell Proliferation, Apoptosis, and Oxidative Stress in ALL Cells

T-cell acute lymphoblastic leukemia (T-ALL) is a type of acute lymphoblastic leukemia from early T-cell progenitors. Interest grows in creating less toxic agents and therapies for chemo-resistant T-ALL cancer. Recently, elemental boron has special properties useful in the creation of new drugs. Studies have revealed the cytotoxic properties of boric acid (BA) on cancer, but not fully understood. We aimed to investigate the effect of BA on cell proliferation, apoptosis, and oxidative stress in the Jurkat cells. The effects of BA on cell viability were determined by 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay for 24-48-72 h. The impact of BA on apoptosis was analyzed by acridine orange/ethidium bromide. Expression of apoptosis regulatory genes (Bcl-2, Bax, Caspase-3-8-9) and apoptotic miRNA (miR-21) was used by real-time quantitative polymerase chain reaction (RT-qPCR). The total oxidant status (TOS), total antioxidant status (TAS), and the oxidative stress index (OSI) value were calculated for oxidative stress. We determined the cytotoxic activity of BA on Jurkat cells by using XTT and defined the IC50 concentration (802.7 μg/mL) of BA. The findings clearly show that BA inhibited Jurkat cell proliferation dose-dependently. BA induced apoptosis through downregulated anti-apoptotic genes, and upregulated pro-apoptotic genes. Additionally, we found that BA significantly reduced the expression of miR-21 (p<0.001). Our findings demonstrated that different doses of BA increased TAS levels while decreasing TOS levels in Jurkat cells. Our study suggests that BA might be potential anti-cancer agent candidate in ALL via inhibition of cell proliferation, induced apoptosis, and reducing the amounts of anti-oxidants in cells.

Borax affects cellular viability by inducing ER stress in hepatocellular carcinoma cells by targeting SLC12A5

Hepatocellular carcinoma (HCC) presents a persistent challenge to conventional therapeutic approaches. SLC12A5 is implicated in an oncogenic capacity and facilitates the progression of cancer. The objective of this investigation is to scrutinize the inhibitory effects of borax on endoplasmic reticulum (ER)-stress and apoptosis mediated by SLC12A5 in HepG2 cells. Initially, we evaluated the cytotoxic impact of borax on both HL-7702 and HepG2 cell lines. Subsequently, the effects of borax on cellular morphology and the cell cycle of these lines were examined. Following this, we explored the impact of borax treatment on the mRNA and protein expression levels of SLC12A5, C/EBP homologous protein (CHOP), glucose-regulated protein-78 (GRP78), activating transcription factor-6 (ATF6), caspase-3 (CASP3), and cytochrome c (CYC) in these cellular populations. The determined IC50 value of borax for HL-7702 cells was 40.8 mM, whereas for HepG2 cells, this value was 22.6 mM. The concentrations of IC50 (22.6 mM) and IC75 (45.7 mM) of borax in HepG2 cells did not manifest morphological aberrations in HL-7702 cells. Conversely, these concentrations in HepG2 cells induced observable morphological and nuclear abnormalities, resulting in cell cycle arrest in the G1/G0 phase. Additionally, the levels of SLC12A5, ATF6, CHOP, GRP78, CASP3, and CYC were elevated in HepG2 cells in comparison to HL-7702 cells. Moreover, SLC12A5 levels decreased following borax treatment in HepG2 cells, whereas ATF6, CHOP, GRP78, CASP3, and CYC levels exhibited a significant increase. In conclusion, our data highlight the potential therapeutic effects of borax through the regulation of ER stress in HCC by targeting SLC12A5.

In Vitro Effects of Boric Acid on Cell Cycle, Apoptosis, and miRNAs in Medullary Thyroid Cancer Cells

Medullary thyroid cancer (MTC) is a highly aggressive and chemotherapy-resistant cancer originating from the thyroid's parafollicular C cells. Due to its resistance to conventional treatments, alternative therapies such as boric acid have been explored. Boric acid, a boron-based compound, has shown anticarcinogenic effects, positioning it as a potential treatment option for MTC. TT medullary thyroid carcinoma cell line (TT cells) and human thyroid fibroblast (HThF cells) were utilized for the cell culture experiments. Cell viability was assessed using the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay. Total RNA was extracted using Trizol reagent for gene expression and microRNA (miRNA) analysis via reverse transcription-polymerase chain reaction (RT-PCR). The extent of apoptosis induced by boric acid was determined using the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Colony formation assays were conducted to evaluate the impact of boric acid on the colony-forming ability of MTC cells. At 48 h, 50% inhibitory concentration (IC50) of boric acid was found to be 35 μM. Treatment with boric acid resulted in significant modulation of apoptosis-related genes and miRNAs, including increased expression of phorbol-12-myristate-13-acetate-induced protein 1(NOXA), apoptotic protease activating factor 1 (APAF-1), Bcl-2-associated X protein (Bax), caspase-3, and caspase-9. In contrast, the expression of B cell lymphoma 2 (Bcl2), B cell lymphoma- extra-large (Bcl-xl), and microRNA-21 (miR-21), which are linked to the aggressiveness of MTC, was significantly reduced. The TUNEL assay indicated a 14% apoptosis rate, and there was a 67.9% reduction in colony formation, as shown by the colony formation assay. Our study suggests that boric acid may have anticancer activity in MTC by modulating apoptotic pathways. These findings suggest that boric acid could be a potential therapeutic agent for MTC and possibly for other malignancies with similar pathogenic mechanisms.

Redox Mechanisms Underlying the Cytostatic Effects of Boric Acid on Cancer Cells-An Issue Still Open

Boric acid (BA) is the dominant form of boron in plasma, playing a role in different physiological mechanisms such as cell replication. Toxic effects have been reported, both for high doses of boron and its deficiency. Contrasting results were, however, reported about the cytotoxicity of pharmacological BA concentrations on cancer cells. The aim of this review is to briefly summarize the main findings in the field ranging from the proposed mechanisms of BA uptake and actions to its effects on cancer cells.

Boric Acid Inhibits RANKL-Stimulated Osteoclastogenesis In Vitro and Attenuates LPS-Induced Bone Loss In Vivo

Boron and boric acid (BA) can promote osteogenic differentiation and reduce bone resorption, which controls bone growth and maintenance of bone tissue. It has been reported that BA activates PERK-eIF2α signaling to induce cytoplasmic stress granules and cell senescence in human prostate DU-145 cells. However, whether BA can affect osteoclasts formation and LPS-induced inflammatory bone loss, and the role of the PERK-eIF2α pathway in the process, remains unknown. In vitro, RAW264.7 cells were pre-treated with boric acid (BA, 1, 10, 100 μmol/L) for 4 h, and then incubated with receptor activator of nuclear factor-kappaB ligand (RANKL, 50 ng/mL) in the presence or absence of BA for 5 days. CCK-8 and tartrate-resistant acid phosphatase (TRAP) were used to examine cell viability, osteoclastogenesis, and bone resorption; quantitative real-time PCR was performed to examine mRNA levels of c-Fos, nuclear factor of activated T cells, cytoplasmic 1 (NFATc1), TRAP, and cathepsin K; western blotting was used to examine protein expressions of glucose-regulated protein 78 (GRP78), protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), phosphorylated PERK (p-PERK), eukaryotic initiation factor 2α (eIF2α), and phosphorylated eIF2α (p-eIF2α). In vivo, lipopolysaccharide (LPS)-induced bone loss model in mice was established, and micro-computed tomography (micro-CT) scanning, bone biochemical analysis, and osteoclastogenic cytokines were detected to evaluate the effect of BA on LPS-induced bone loss. In our vitro results showed that BA treatment for 5 days inhibited osteoclasts formation as well as osteoclastic bone resorption in a dose-dependent manner. The expression of osteoclasts marker genes c-Fos, NFATc1, TRAP, and cathepsin K were attenuated by BA. Immunoblotting analysis demonstrated that BA attenuated RANKL-induced PERK-eIF2α pathway activation. The in vivo data indicated that BA significantly prevented lipopolysaccharide (LPS)-induced bone loss. Our findings strongly suggest that BA may be a promising agent for the treatment of bone destructive diseases caused by excessive osteoclastogenesis.

Nail Mineral Composition Changes Do Not Reflect Bone Mineral Changes Caused by Boron Supplementation

Nails have been found to be a non-invasive and readily available tissue whose mineral content can change because of a change in dietary mineral intake. Thus, this study was undertaken to determine whether boron (B) supplementation would change the concentrations of some mineral elements in nails and whether these changes correlated with changes induced in bone. Female New Zealand White rabbits (aged 8 months, 2-2.5 kg weight) were fed a grain-based, high-energy diet containing 3.88 mg B/kg. The rabbits were divided into four treatment groups: controls receiving no supplemental B (N: 7; C) and three groups supplemented with 30 mg B/L in drinking water as borax decahydrate (Na₂B₄O₇∙10H₂O, N: 10; BD), borax anhydrous (Na₂B₄O₇, N: 7; Bah), and boric acid (H₃BO₃, N: 7; BA). Boron, calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), phosphorus (P), potassium (K), sodium (Na), sulfur (S), and zinc (Zn) concentrations in nails were determined by inductively coupled plasma atomic emission spectroscopy. Parametric and non-parametric multiple group comparisons and post hoc tests were performed and whether a correlation between nail and tibia and femur mineral elements concentrations were determined. A p-value of < 0.05 was considered statistically significant. Boron was not detectable in control nails but was found in the nails of the three B supplemented groups. Boron supplementation markedly increased the Ca concentration in nails with the effect greatest in the BA and BD groups. The P and Mg concentrations also were increased by B supplementation with the effect most marked in the BA group. In contrast, B supplementation decreased the Na concentration with the effect most noticeable in the BD and Bah groups. The Zn concentration in nails was not affected by BA and BD supplementation but was decreased by Bah supplementation. Boron supplementation did not significantly affect the concentrations of Cu, Fe, Mo, K, and S in nails. No meaningful significant correlations were found between nail mineral elements and tibia and femur mineral elements found previously. Nails can be an indicator of the response to boron supplementation but are not useful to indicate changes in mineral elements in bone in response to B supplementation.

Multiple functions of stress granules in viral infection at a glance

Stress granules (SGs) are distinct RNA granules induced by various stresses, which are evolutionarily conserved across species. In general, SGs act as a conservative and essential self-protection mechanism during stress responses. Viruses have a long evolutionary history and viral infections can trigger a series of cellular stress responses, which may interact with SG formation. Targeting SGs is believed as one of the critical and conservative measures for viruses to tackle the inhibition of host cells. In this systematic review, we have summarized the role of SGs in viral infection and categorized their relationships into three tables, with a particular focus on Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Moreover, we have outlined several kinds of drugs targeting SGs according to different pathways, most of which are potentially effective against SARS-CoV-2. We believe this review would offer a new view for the researchers and clinicians to attempt to develop more efficacious treatments for virus infection, particularly for the treatment of SARS-CoV-2 infection.

Stress granules dynamics: benefits in cancer

Stress granules (SGs) are stress-induced subcellular compartments, which carry out a particular function to cope with stress. These granules protect cells from stress-related damage and cell death through dynamic sequestration of numerous ribonucleoproteins (RNPs) and signaling proteins, thereby promoting cell survival under both physiological and pathological condition. During tumorigenesis, cancer cells are repeatedly exposed to diverse stress stimuli from the tumor microenvironment, and the dynamics of SGs is often modulated due to the alteration of gene expression patterns in cancer cells, leading to tumor progression as well as resistance to anticancer treatment. In this mini review, we provide a brief discussion about our current understanding of the fundamental roles of SGs during physiological stress and the effect of dysregulated SGs on cancer cell fitness and cancer therapy. [BMB Reports 2022; 55(12): 577-586].

How do RNA binding proteins trigger liquid-liquid phase separation in human health and diseases?

RNA-binding proteins (RBPs) lie at the center of post-transcriptional regulation and protein synthesis, adding complexity to RNA life cycle. RBPs also participate in the formation of membrane-less organelles (MLOs) via undergoing liquid-liquid phase separation (LLPS), which underlies the formation of MLOs in eukaryotic cells. RBPs-triggered LLPS mainly relies on the interaction between their RNA recognition motifs (RRMs) and capped mRNA transcripts and the heterotypic multivalent interactions between their intrinsically disordered regions (IDRs) or prion-like domains (PLDs). In turn, the aggregations of RBPs are also dependent on the process of LLPS. RBPs-driven LLPS is involved in many intracellular processes (regulation of translation, mRNA storage and stabilization and cell signaling) and serves as the heart of cellular physiology and pathology. Thus, it is essential to comprehend the potential roles and investigate the internal mechanism of RPBs-triggered LLPS. In this review, we primarily expound on our current understanding of RBPs and they-triggered LLPS and summarize their physiological and pathological functions. Furthermore, we also summarize the potential roles of RBPs-triggered LLPS as novel therapeutic mechanism for human diseases. This review will help understand the mechanisms underlying LLPS and downstream regulation of RBPs and provide insights into the pathogenesis and therapy of complex diseases.

Stress granules dynamics: benefits in cancer

Stress granules (SGs) are stress-induced subcellular compartments, which carry out a particular function to cope with stress. These granules protect cells from stress-related damage and cell death through dynamic sequestration of numerous ribonucleoproteins (RNPs) and signaling proteins, thereby promoting cell survival under both physiological and pathological condition. During tumorigenesis, cancer cells are repeatedly exposed to diverse stress stimuli from the tumor microenvironment, and the dynamics of SGs is often modulated due to the alteration of gene expression patterns in cancer cells, leading to tumor progression as well as resistance to anticancer treatment. In this mini review, we provide a brief discussion about our current understanding of the fundamental roles of SGs during physiological stress and the effect of dysregulated SGs on cancer cell fitness and cancer therapy. [BMB Reports 2022; 55(12): 577-586].

The Possible Protective Effect of Boric Acid in an Alkaline-Induced Corneal Neovascularization Rat Model

It is known that boric acid (BA) exerts it antioxidant and anti-inflammatory effects by activating the activating transcription factor 4 (ATF4) and nuclear factor-erythroid 2-related factor 2 (Nrf2) pathway. This pathway has been reported to control antioxidant status in the eye. The aim of this study was to investigate the possible preventive effects of boric acid administration on oxidative damage and corneal neovascularization (CNV). Sixteen adult female Wistar albino rats were divided into two groups: (I) control (n = 8); the CNV model was applied to the right eye of the rats, and the left eyes were used as healthy controls. (II) CNV + BA (n = 8): After the CNV model was applied to the right eyes, a single subconjunctival dose (0.05 mL) of 0,018 g/mL BA was injected into the right and left eyes of the rats. Biochemical, histopathological, and immunohistochemical analyses were performed. Moderate VEGF positivity was observed in the vessels of the CNV group, a decrease in vessel proliferation, and weak VEGF positivity in the CNV + BA group. The TAS level in the CNV + BA group was significantly higher than that in the other groups. The TOS level was significantly higher in all groups than it is in the control group. The OSI value was increased in all groups when compared to the control group, but only the CNV and BA groups were statistically significant. BA not only reduced alkaline-induced corneal damage histologically but also showed a protective effect on oxidative stress biochemically.

Boric acid exert anti-cancer effect in poorly differentiated hepatocellular carcinoma cells via inhibition of AKT signaling pathway

BACKGROUND

The possible anti-cancer properties of boron, a trace element for humans, have been demonstrated in various experimental and epidemiological studies, although the effects of boron on liver cancer are unclear. In the present study we evaluate the effects of boric acid on the cell lines of hepatocellular carcinoma (HCC) of the liver, as the leading form of liver cancer, for which a poorly-differentiated HCC cell line (Mahlavu cell line) was used.

METHODS

The anti-cancer effect of boric acid was investigated with a cell viability assay, apoptosis analysis, cell migration analysis, cell morphology analysis, colony formation assay and 3D cell culture techniques. Also, the effect of boric acid on the AKT signaling pathway was determined through a western blot analysis.

RESULTS

Boric acid was found to reduce cell viability in a dose- and time-dependent manner, and decreased survival, colony formation ability, migration capability and HCC cell tumor spheroid growth in HCC cell lines, while also inducing apoptosis, autophagy and morphological alteration. Furthermore, boric acid inhibited AKT phosphorylation, and anticancer biological responses in HCC cells were observed only in cells in which AKT phosphorylation was suppressed by boric acid.

CONCLUSION

Our results suggest that boric acid might be a promising therapeutic candidate in hepatocellular carcinoma via the inhibition of AKT signaling pathway.

Transcriptome Profiling of Duodenum Reveals the Importance of Boron Supplementation in Modulating Immune Activities in Rats

As an essential trace element, appropriate boron supplementation can promote immune function of animals. To illustrate the effects of boron in a rat model, RNA-Seq was conducted for the RNA from duodenum after treatment with different concentration of boron in which boron was given in the form of boric acid. More than 47 million reads were obtained in 0, 10, and 320 mg/L boron (0, 57.21, and 1830.66 mg/L boric acid) treatment groups that produced 58 965 402, 48 607 328, and 46 760 660 clean reads, respectively. More than 95% of the clean reads were successfully matched to the rat reference genome and assembled to generate 32 662 transcripts. A total of 624 and 391 differentially expressed candidate genes (DEGs) were found between 0 vs.10 and 0 vs. 320 mg/L boron comparison groups. We also identified transcription start site, transcription terminal site, and skipped exons as the main alternative splicing events. GO annotations revealed most of DEGs were involved in the regulation of immune activity. The DEGs were enriched in influenza A, herpes simplex infection, cytosolic DNA-sensing pathway, and antigen processing and presentation signaling pathways. The expression levels of genes enriched in these signaling pathways indicate that lower doses of boron could achieve better effects on promoting immune response in the duodenum. These effects on the immune system appear to be mediated via altering the expression patterns of genes involved in the related signaling pathways in a dose-dependent pattern. These data provide more insights into the molecular mechanisms of immune regulation in rats in response to dietary boron treatment.

Stress Granules in the Anti-Cancer Medications Mechanism of Action: A Systematic Scoping Review

Stress granule (SG) formation is a well-known cellular mechanism for minimizing stress-related damage and increasing cell survival. In addition to playing a critical role in the stress response, SGs have emerged as critical mediators in human health. It seems logical that SGs play a key role in cancer cell formation, development, and metastasis. Recent studies have shown that many SG components contribute to the anti-cancer medications' responses through tumor-associated signaling pathways and other mechanisms. SG proteins are known for their involvement in the translation process, control of mRNA stability, and capacity to function in both the cytoplasm and nucleus. The current systematic review aimed to include all research on the impact of SGs on the mechanism of action of anti-cancer medications and was conducted using a six-stage methodological framework and the PRISMA guideline. Prior to October 2021, a systematic search of seven databases for eligible articles was performed. Following the review of the publications, the collected data were subjected to quantitative and qualitative analysis. Notably, Bortezomib, Sorafenib, Oxaliplatin, 5-fluorouracil, Cisplatin, and Doxorubicin accounted for the majority of the medications examined in the studies. Overall, this systematic scoping review attempts to demonstrate and give a complete overview of the function of SGs in the mechanism of action of anti-cancer medications by evaluating all research.

Cross species multi-omics reveals cell wall sequestration and elevated global transcript abundance as mechanisms of boron tolerance in plants

Boron toxicity is a world-wide problem for crops, yet we have a limited understanding of the genetic responses and adaptive mechanisms to this stress in plants. We employed a cross-species comparison between boron stress-sensitive Arabidopsis thaliana and its boron stress-tolerant extremophyte relative Schrenkiella parvula, and a multi-omics approach integrating genomics, transcriptomics, metabolomics and ionomics to assess plant responses and adaptations to boron stress. Schrenkiella parvula maintains lower concentrations of total boron and free boric acid than Arabidopsis when grown with excess boron. Schrenkiella parvula excludes excess boron more efficiently than Arabidopsis, which we propose is partly driven by SpBOR5, a boron transporter that we functionally characterize in this study. Both species use cell walls as a partial sink for excess boron. When accumulated in the cytoplasm, excess boron appears to interrupt RNA metabolism. The extremophyte S. parvula facilitates critical cellular processes while maintaining the pool of ribose-containing compounds that can bind with boric acid. The S. parvula transcriptome is pre-adapted to boron toxicity. It exhibits substantial overlaps with the Arabidopsis boron-stress responsive transcriptome. Cell wall sequestration and increases in global transcript levels under excess boron conditions emerge as key mechanisms for sustaining plant growth under boron toxicity.

Targeting stress granules: A novel therapeutic strategy for human diseases

Stress granules (SGs) are assemblies of mRNA and proteins that form from mRNAs stalled in translation initiation in response to stress. Chronic stress might even induce formation of cytotoxic pathological SGs. SGs participate in various biological functions including response to apoptosis, inflammation, immune modulation, and signalling pathways; moreover, SGs are involved in pathogenesis of neurodegenerative diseases, viral infection, aging, cancers and many other diseases. Emerging evidence has shown that small molecules can affect SG dynamics, including assembly, disassembly, maintenance and clearance. Thus, targeting SGs is a potential therapeutic strategy for the treatment of human diseases and the promotion of health. The established methods for detecting SGs provided ready tools for large-scale screening of agents that alter the dynamics of SGs. Here, we describe the effects of small molecules on SG assembly, disassembly, and their roles in the disease. Moreover, we provide perspective for the possible application of small molecules targeting SGs in the treatment of human diseases.

Understanding the roles of stress granule during chemotherapy for patients with malignant tumors

The assembly of stress granules (SGs) is a conserved mechanism to regulate protein synthesis under cell stress, where the translation of global protein is silenced and selective protein synthesis for survival maintains. SG formation confers survival advantages and chemotherapeutic resistance to malignant cells. Targeting SG assembly may represent a potential treatment strategy to overcome the primary and acquired chemotherapeutic resistance and enhance curative effect. We conduct a comprehensive review of the published literatures focusing on the drugs that potentially induce SGs and the related mechanism, retrospect the relationship between SGs and drug resistance related proteins, illuminate the regulated pathways and potential targets for SG assembly, and discuss future directions of overcoming the resistance to chemotherapy.

The Effect of Boron-Containing Nano-Hydroxyapatite on Bone Cells

Metabolic diseases or injuries damage bone structure and self-renewal capacity. Trace elements and hydroxyapatite crystals are important in the development of biomaterials to support the renewal of bone extracellular matrix. In this study, it was assumed that the boron-loaded nanometer-sized hydroxyapatite composite supports the construction of extracellular matrix by controlled boron release in order to prevent its toxic effect. In this context, boron release from nanometer-sized hydroxyapatite was calculated by ICP-MS as in large proportion within 1 h and continuing release was provided at a constant low dose. The effect of the boron-containing nanometer-sized hydroxyapatite composite on the proliferation of SaOS-2 osteoblasts and human bone marrow-derived mesenchymal stem cells was evaluated by WST-1 and compared with the effects of nano-hydroxyapatite and boric acid. Boron increased proliferation of mesenchymal stem cells at high doses and exhibited different effects on osteoblastic cell proliferation. Boron-containing nano-hydroxyapatite composites increased osteogenic differentiation of mesenchymal stem cells by increasing alkaline phosphatase activity, when compared to nano-hydroxyapatite composite and boric acid. The molecular mechanism of effective dose of boron-containing hydroxyapatite has been assessed by transcriptomic analysis and shown to affect genes involved in Wnt, TGF-β, and response to stress signaling pathways when compared to nano-hydroxyapatite composite and boric acid. Finally, a safe osteoconductive dose range of boron-containing nano-hydroxyapatite composites for local repair of bone injuries and the molecular effect profile in the effective dose should be determined by further studies to validation of the regenerative therapeutic effect window.

Cancer and ER stress: Mutual crosstalk between autophagy, oxidative stress and inflammatory response

The endoplasmic reticulum (ER) acts as a moving organelle with many important cellular functions. As the ER lacks sufficient nutrients under pathological conditions leading to uncontrolled protein synthesis, aggregation of unfolded/misfolded proteins in the ER lumen causes the unfolded protein response (UPR) to be activated. Chronic ER stress produces endogenous or exogenous damage to cells and activates UPR, which leads to impaired intracellular calcium and redox homeostasis. The UPR is capable of recognizing the accumulation of unfolded proteins in the ER. The protein response enhances the ability of the ER to fold proteins and causes apoptosis when the function of the ER fails to return to normal. In different malignancies, ER stress can effectively induce the occurrence of autophagy in cells because malignant tumor cells need to re-use their organelles to maintain growth. Autophagy simultaneously counteracts ER stress-induced ER expansion and has the effect of enhancing cell viability and non-apoptotic death. Oxidative stress also affects mitochondrial function of important proteins through protein overload. Mitochondrial reactive oxygen species (ROS) are produced by calcium-enhanced ER release. The accumulation of toxic substances in ER and mitochondria in mitochondria destroys basic organelle function. It is known that sustained ER stress can also trigger an inflammatory response through the UPR pathway. Inflammatory response is thought to be associated with tumor development. This review discusses the emerging links between UPR responses and autophagy, oxidative stress, and inflammatory response signals in ER stress, as well as the potential development of targeting this multifaceted signaling pathway in various cancers.

Boron's neurophysiological effects and tumoricidal activity on glioblastoma cells with implications for clinical treatment

Purpose: To define the actions of boron on normal neurophysiology and glioblastoma growth. Materials and Methods: PubMed and other relevant databases were searched. Results: Discovery of novel boron compounds in treatment of glioblastoma is being actively investigated, but the majority of such studies is focused on the synthesis of boron compounds as sensitizers to Boron Neutron Capture Therapy (BNCT). Nonetheless, the translational functionality of boron compounds is not limited to BNCT as many boron compounds possess direct tumoricidal activity and there is substantial evidence that certain boron compounds can cross the blood-brain barrier. Moreover, boron-containing compounds interfere with several tumorigenic pathways including intratumoral IGF-I levels, molybdenum Fe-S containing flavin hydroxylases, glycolysis, Transient Receptor Potential (TRP) and Store Operated Calcium Entry (SOCE) channels. Conclusions: Boron compounds deserve to be studied further in treatment of systemic cancers and glioblastoma due to their versatile antineoplastic functions.

Boric Acid Activation of eIF2α and Nrf2 Is PERK Dependent: a Mechanism that Explains How Boron Prevents DNA Damage and Enhances Antioxidant Status

Boron is abundant in vegetables, nuts, legumes, and fruit and intake is associated with reduced risk of cancer and DNA damage and increased antioxidant status. Blood boric acid (BA) levels are approximately 10 μM BA in men at the mean US boron intake. Treatment of DU-145 human prostate cancer cells with 10 μM BA stimulates phosphorylation of elongation initiation factor 2α (eIF2α) at Ser51 leading to activation of the eIF2α/ATF4 pathway which activates the DNA damage-inducible protein GADD34. In the present study, we used MEF WT and MEF PERK (±) cells to test the hypothesis that BA-activated eIF2α phosphorylation requires protein kinase RNA-like endoplasmic reticulum kinase (PERK) and activates Nrf2 and the antioxidant response element (ARE). BA (10 μM) increased phosphorylation of eIF2α Ser51 in MEF WT cells at 1 h, but not in MEF Perk -/- cells exposed for as long as 6 h. GCN2 kinase-dependent phosphorylation of eIF2α Ser51 was activated in MEF PERK -/- cells by amino acid starvation. Nrf2 phosphorylation is PERK dependent and when activated is translocated from the cytoplasm to the nucleus where it acts as a transcription factor for ARE. DU-145 cells were treated with 10 μM BA and Nrf2 measured by immunofluorescence. Cytoplasmic Nrf2 was translocated to the nucleus at 1.5-2 h in DU-145 and MEF WT cells, but not MEF PERK -/- cells. Real-time PCR was used to measure mRNA levels of three ARE genes (HMOX-1, NQO1, and GCLC). Treatment with 10 μM BA increased the mRNA levels of all three genes at 1-4 h in DU-145 cells and HMOX1 and GCLC in MEF WT cells. These results extend the known boric acid signaling pathway to ARE-regulated genes. The BA signaling pathway can be expressed using the schematic [BA + cADPR → cADPR-BA → [[ER]_i Ca²⁺↓] → 3 pathways: PERK/eIF2αP → pathways ATF4 and Nrf2; and [[ER]_i Ca²⁺↓] → ER stress → ATF6 pathway. This signaling pathway provides a framework that links many of the molecular changes that underpin the biological effects of boron intake.

The Physiological Role of Boron on Health

Boron is an essential mineral that plays an important role in several biological processes. Boron is required for growth of plants, animals, and humans. There are increasing evidences of this nutrient showing a variety of pleiotropic effects, ranging from anti-inflammatory and antioxidant effects to the modulation of different body systems. In the past few years, the trials showed disease-related polymorphisms of boron in different species, which has drawn attention of scientists to the significance of boron to health. Low boron profile has been related with poor immune function, increased risk of mortality, osteoporosis, and cognitive deterioration. High boron status revealed injury to cell and toxicity in different animals and humans. Some studies have shown some benefits of higher boron status, but findings have been generally mixed, which perhaps accentuates the fact that dietary intake will benefit only if supplemental amount is appropriate. The health benefits of boron are numerous in animals and humans; for instance, it affects the growth at safe intake. Central nervous system shows improvement and immune organs exhibit enhanced immunity with boron supplementation. Hepatic metabolism also shows positive changes in response to dietary boron intake. Furthermore, animals and human fed diets supplemented with boron reveal improved bone density and other benefits including embryonic development, wound healing, and cancer therapy. It has also been reported that boron affects the metabolism of several enzymes and minerals. In the background of these health benefits, low or high boron status is giving cause for concern. Additionally, researches are needed to further elucidate the mechanisms of boron effects, and determine the requirements in different species.

High Doses of Boron Have No Protective Effect Against Nephrolithiasis or Oxidative Stress in a Rat Model

Boron plays roles in the metabolism of calcium, vitamin D, steroid hormones, healthy bone development, and maintenance of cell membranes. The biological effects of boron are dose-dependent but follow a U-shaped pattern, rendering it important to define the active range. The studies of Bahadoran et al. on rats and Naghii et al. on humans showed that low doses of boron (3 and 10 mg/day) prevented kidney stone formation. The aim of this study was to determine whether high doses of boron have an anti-urolithiatic or antioxidant effect on nephrolithiasis in an experimental rat model. The study was conducted on 50 adult male Wistar rats randomized to five groups. Nephrolithiasis was induced with water containing 0.75% ethylene glycol (EG) and 2% ammonium chloride (AC). This treatment was given to animals in all groups for 10 days, except the positive and negative controls. Simultaneously, groups 2, 3, and 4 were given boric acid via gavage at doses of 25, 50, and 100 mg/kg/day (equivalent to 4/8/16 mg boron respectively) as the source of boron. Animals in the negative and positive control groups were given 6 μL/g distilled water without boric acid. At day 10, intra-cardiac blood samples were drawn from all animals. The right and left kidneys were removed for biochemical and histopathological examinations, respectively. The groups were compared with respect to serum urea, creatinine, calcium, phosphorous, total antioxidant status (TAS), total oxidant status (TOS), serum paraoxonase (PON1) activity, tissue calcium and oxalate levels, and stone burden as determined by histopathological examination. Serum urea and creatinine levels were significantly higher (p < 0.001 and p < 0.05, respectively), while serum calcium and phosphorous levels were significantly lower (p < 0.001 and p < 0.001, respectively), in animals given EG/AC compared to negative controls. No significant differences were detected in serum calcium, phosphorous, urea, or creatinine levels between animals treated with boron and positive controls (p > 0.05). Serum PON1 activity was significantly lower in animals given EG/AC than in negative controls (p < 0.001), while no significant difference in serum PON1 level was detected between rats treated with boron and positive controls. No significant differences were detected in vitamin D, TAS, TOS, tissue calcium, or tissue oxalate levels among groups. No stone formation was detected on histopathological examination in negative controls. No significant differences were found in stone formation between rats treated with boron and positive controls. Based on this study, high doses of boron had no protective effect against nephrolithiasis and oxidative stress.

The Effect of Boric Acid and Borax on Oxidative Stress, Inflammation, ER Stress and Apoptosis in Cisplatin Toxication and Nephrotoxicity Developing as a Result of Toxication

The development of treatment protocols that can reduce side effects in chemotherapy applications is extremely important in terms of cancer treatment. In this context, it was aimed to investigate the effects of boric acid and borax on cisplatin toxicity (nephrotoxicity) in rats. In the experimental phase, eight groups were formed from rats. Boric acid and borax were given to the treatment groups with three different doses using gavage. On the fifth day of the study, cisplatin (10 mg/kg) was administered to all rats except the control group. At the end of the study, oxidative stress-related (GSH, MDA, PCO, GPx, 8-OHdG), inflammation-related (TNF-α, IL-1β, IL-18, MCP-1, ICAM, TGF-β), apoptosis-related (p53, caspase 1, 3, 8, 12, bcl-2, bcl-xL, NFkB), and ER stress-related (GRP78, ATF-6, PERK) basic parameters were analyzed in serum, erythrocyte, and kidney tissues. Kidney tissues were also examined by histopathological and immunohistochemical methods. Borax and boric acid at different doses decreased inflammation and oxidative stress caused by cisplatin toxicity and increased ER stress. As a result of the treatments applied to experimental animals, it was determined that boric acid and borax reduced apoptotic damage in kidney tissue, but the decrease was statistically significant only in 200 mg/kg boric acid-administered group. In the study, low anti-apoptotic effects of borate doses with the anti-inflammatory and antioxidant effect may be due to increased ER stress at the relevant doses. Further studies on the effects of boron compounds on ER stress and apoptotic mechanisms may clarify this issue. Thus, possible side effects or if there are new usage areas of borone compounds which have many usage areas in clinics can be detected.

The importance of boron in biological systems

Boron is an essential element for plants and probably essential for human and animal health. Boron has a broad range of physiological effects on biological systems at low concentrations, whereas it is toxic to at high concentrations. Eventhough there are many studies on boron's biological effects and toxicity, more information is needed to understand the mechanisms of its action. The aim of the current work is to review boron's function, transport and toxicity in different biological systems.

Influence of boron supplementation on performance, immunity and antioxidant status of lambs fed diets with or without adequate level of calcium

Little is known about biological significance of effects of dietary Boron (B) and Calcium (Ca) interaction on health and production of farm animals. This is a preliminary investigation to evaluate the effects of B supplementation in lambs fed diets with (normal) or without adequate (low) levels of Ca. Twenty-four crossbred ram lambs were randomly distributed into four groups with six animals each in a 2x2 factorial design namely, normal-Ca diet (NCa) and low-Ca diet (LCa) fed without or with 40 ppm B (NCaB-40 and LCaB-40). The lambs were fed paddy straw and hybrid napier hay-based total mixed ration (60 roughage: 40 concentrate) during 180 days experimental period. Compared to control, the LCa diet lowered (P<0.01) average daily gain of lambs, but B-supplementation (LCaB-40) of the same nullified the effect. The lowered (P<0.05) total antioxidant activity and humoral immune response in lambs fed LCa diet were restored (P>0.05) to become at par with the control (NCa) upon supplementation of B (LCaB-40). The mRNA expression of SOD1 was lowered (P<0.05) due to LCa diet feeding which too was normalized on B-supplementation to become at par (P>0.05) with the control (NCa). Further, B-supplementation restored lowered (P<0.05) SOD1 gene expression on LCa diet, but enhanced (P<0.05) that in NCaB-40 group, when compared to the control (NCa) diet fed animals. However, these variations were not reflected in the SOD activity in the erythrocytes. The cell-mediated immune response was higher (P<0.05) in lambs fed LCa and LCaB-40 groups and there was no significant interaction between the levels of either Ca or B in diets with the period of immune response measurement. B- supplementation of LCa diet ameliorated tissue degenerative changes in liver and kidney. It was concluded that feeding LCa diet to lambs resulted in reduced growth rate, total antioxidant activity, humoral immune response along with degenerative changes in liver and kidney tissues, but B-supplementation of such diet restored most of these changes and ameliorated histopathological alterations.

Activation of the EIF2α/ATF4 and ATF6 Pathways in DU-145 Cells by Boric Acid at the Concentration Reported in Men at the US Mean Boron Intake

Fruits, nuts, legumes, and vegetables are rich sources of boron (B), an essential plant nutrient with chemopreventive properties. Blood boric acid (BA) levels reflect recent B intake, and men at the US mean intake have a reported non-fasting level of 10 μM. Treatment of DU-145 prostate cancer cells with physiological concentrations of BA inhibits cell proliferation without causing apoptosis and activates eukaryotic initiation factor 2 (eIF2α). EIF2α induces cell differentiation and protects cells by redirecting gene expression to manage endoplasmic reticulum stress. Our objective was to determine the temporal expression of endoplasmic reticulum (ER) stress-activated genes in DU-145 prostate cells treated with 10 μM BA. Immunoblots showed post-treatment increases in eIF2α protein at 30 min and ATF4 and ATF6 proteins at 1 h and 30 min, respectively. The increase in ATF4 was accompanied by an increase in the expression of its downstream genes growth arrest and DNA damage-induced protein 34 (GADD34) and homocysteine-induced ER protein (Herp), but a decrease in GADD153/CCAAT/enhancer-binding protein homologous protein (CHOP), a pro-apoptotic gene. The increase in ATF6 was accompanied by an increase in expression of its downstream genes GRP78/BiP, calreticulin, Grp94, and EDEM. BA did not activate IRE1 or induce cleavage of XBP1 mRNA, a target of IRE1. Low boron status has been associated with increased cancer risk, low bone mineralization, and retinal degeneration. ATF4 and BiP/GRP78 function in osteogenesis and bone remodeling, calreticulin is required for tumor suppressor p53 function and mineralization of teeth, and BiP/GRP78 and EDEM prevent the aggregation of misfolded opsins which leads to retinal degeneration. The identification of BA-activated genes that regulate its phenotypic effects provides a molecular underpinning for boron nutrition and biology.

A new hope for obesity management: Boron inhibits adipogenesis in progenitor cells through the Wnt/β-catenin pathway

Obesity is a worldwide medical problem resulting in serious morbidity and mortality involving differentiation of pre-adipocytes into mature adipocytes (adipogenesis). Boron treatment has been reported to be associated with weight reduction in experimental animals; however, its effects on pre-adipocyte differentiation and anti-adipogenic molecular mechanisms are unknown. In this study, we demonstrate the inhibitory activities of boric acid (BA) and sodium pentaborate pentahydrate (NaB) on adipogenesis using common cellular models. Boron treatment repressed the expression of adipogenesis-related genes and proteins, including CCAAT-enhancer-binding protein α and peroxisome proliferator-activated receptor γ, by regulating critical growth factors and the β-catenin, AKT, and extracellular signal-regulated kinase signaling pathways. In addition, although boron treatment did not induce apoptosis in pre-adipocytes, it depressed mitotic clonal expansion by regulation of cell cycle genes. Overall, these data offer promising insights into the prevention/treatment of obesity and associated diseases.

Marchantin M Induces Apoptosis of Prostate Cancer Cells Through Endoplasmic Reticulum Stress

BACKGROUND Apoptosis is mediated by the endoplasmic reticulum (ER) stress pathway, mitochondrial pathway, and death receptor. Data herein suggested an inhibitory effect of marchantin M on tumor formation in nude mice as well as the impact on CHOP and GRP78 expression. MATERIAL AND METHODS The role of marchantin M on proliferation and apoptosis of DU145 cells were measured by MTT and flow cytometry, respectively. Western blot was applied to detect the expression of GRP78 and CHOP. The mice received abdominal injection at 1 time/2 d and 2 ml/time. Tumor volume was measured every 6 days. The mice were euthanatized 30 days after marchantin injection and tumor weight was measured. Cell apoptosis was determined by TUNEL. The expressions of CHOP and GRP78 were detected by immunohistochemistry. RESULTS Tumor size and weight in marchantin groups were significantly lower than in the control group (A, B) (P<0.05), and the inhibitory rate presented a dose-dependent increase. Compared with controls, the levels of CHOP and GRP78 expression elevated obviously following the treatment with marchantin (P<0.05). It showed statistically significant difference among groups C, D, E, with different levels of apoptosis indexes incremented in groups of marchantin H, M, L, compared with groups A and B (P<0.05). CONCLUSIONS Overall, this study shows that marchantin M circumvents the growth of prostate cancer PC-3 tumor and up-regulates expressions of CHOP and GRP78. Our data also indicate that marchantin M limits the proliferation and favors apoptosis of DU145 cells in a time- and dose-dependent manner.