VPA mediates bidirectional regulation of cell cycle progression through the PPP2R2A-Chk1 signaling axis in response to HU.

Cell cycle checkpoint kinases play a pivotal role in protecting against replicative stress. In this study, valproic acid (VPA), a histone deacetylase inhibitor (HDACi), was found to promote breast cancer MCF-7 cells to traverse into G2/M phase for catastrophic injury by promoting PPP2R2A (the B-regulatory subunit of Phosphatase PP2A) to facilitate the dephosphorylation of Chk1 at Ser317 and Ser345. By contrast, VPA protected normal 16HBE cells from HU toxicity through decreasing PPP2R2A expression and increasing Chk1 phosphorylation. The effect of VPA on PPP2R2A was at the post-transcription level through HDAC1/2. The in vitro results were affirmed in vivo. Patients with lower PPP2R2A expression and higher pChk1 expression showed significantly worse survival. PPP2R2A D197 and N181 are essential for PPP2R2A-Chk1 signaling and VPA-mediated bidirectional effect on augmenting HU-induced tumor cell death and protecting normal cells.

Histone deacetylase inhibitor 2-hexyl-4-pentynoic acid enhances hydroxyurea therapeutic effect in triple-negative breast cancer cells.

Triple-negative breast cancer (TNBC) treatment has only limited effect, and it causes a significant number of deaths. Histone deacetylase inhibitors (HDACis) are emerging as promising anti-tumor agents in many types of cancers. We thus hypothesized that 2-hexyl-4-pentynoic acid (HPTA), a novel HDACi, could sensitize TNBC to hydroxyurea (HU, a ribonucleotide reductase inhibitor). In the present study, we investigated the effect of HPTA, alone or in combination with HU on cell survival, DNA double-strand breaks (DSBs), key homologous recombination (HR) repair proteins and cell cycle progression in MDA-MB-468 and MDA-MB-231 human TNBC cell lines. HPTA and HU synergistically inhibited the survival of TNBC cell lines and resulted in the accumulation of DNA double-strand breaks (DSBs). HPTA can sensitize TNBC cells to HU by inhibiting replication protein A2 (RPA2) hyperphosphorylation-mediated HR repair, and lessen cell accumulation in S-phase by inhibiting ATR-CHK1 signaling pathway. Taken together, our data suggested that HPTA enhances HU therapeutic effect by blocking the HR repair and regulating cell cycle progression in TNBC.

Valproic Acid Regulates HR and Cell Cycle Through MUS81-pRPA2 Pathway in Response to Hydroxyurea.

Breast cancer is the primary problem threatening women's health. The combined application of valproic acid (VPA) and hydroxyurea (HU) has a synergistic effect on killing breast cancer cells, but the molecular mechanism remains elusive. Replication protein A2 phosphorylation (pRPA2), is essential for homologous recombination (HR) repair and cell cycle. Here we showed that in response to HU, the VPA significantly decreased the tumor cells survival, and promoted S-phase slippage, which was associated with the decrease of pCHK1 and WEE1/pCDK1-mediated checkpoint kinases phosphorylation pathway and inhibited pRPA2/Rad51-mediated HR repair pathway; the mutation of pRPA2 significantly diminished the above effect, indicating that VPA-caused HU sensitization was pRPA2 dependent. It was further found that VPA and HU combination treatment also resulted in the decrease of endonuclease MUS81. After MUS81 elimination, not only the level of pRPA2 was abolished in response to HU treatment, but also VPA-caused HU sensitization was significantly down-regulated through pRPA2-mediated checkpoint kinases phosphorylation and HR repair pathways. In addition, the VPA altered the tumor microenvironment and reduced tumor burden by recruiting macrophages to tumor sites; the Kaplan-Meier analysis showed that patients with high pRPA2 expression had significantly worse survival. Overall, our findings demonstrated that VPA influences HR repair and cell cycle through down-regulating MUS81-pRPA2 pathway in response to HU treatment.

The Effect of Flavonoids on Chronic Prostatitis: A Meta-analysis of Published Randomized Controlled Trials.

OBJECTIVE: To assess the effect of flavonoids on chronic prostatitis, a meta-analysis of randomized controlled trials was performed. METHODS: Through using subject word and random word, PubMed, Scopus, Web of Science, and Cochrane Library were searched for related records up to July 2018. The response rate and National Institutes of Health-Chronic Prostatitis Symptom Index (NIH-CPSI) were used to evaluate the therapeutic efficacy of the flavonoids. The Cochrane handbook for systematic reviews of interventions version was used to evaluate the quality of included studies. The model of determining odds ratio (OR) was chose according to the value of I2. RESULTS: A total of 11 studies involving 975 subjects (experiment 516, control 459) were included. The overall OR of response rate was 0.31 (95%CI 0.11-0.89, P = 0.03). At the subgroup analysis, the OR of response rate of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) was 0.57 (95%CI 0.18-1.77, P = 0.33), while the OR of response rate of chronic bacterial prostatitis (CBP) was 0.08 (95%CI 0.02-0.33, P = 0.0005). The OR of response rate of CP/CPPS (control was placebo) was 0.29 (95%CI 0.16-0.52, P < 0.0001). The overall OR of baseline NIH-CPSI was -0.1 (95%CI -0.61-0.41, P = 0.70). The overall OR of posttreatment NIH-CPSI was -6.96 (95%CI -8.32∼ -5.60, P < 0.00001). CONCLUSIONS: This meta-analysis indicates that the flavonoids may be clinically beneficial through significantly improving the response rate and NIH-CPSI in chronic prostatitis patients and short-lasting antibiotics therapy in association with the flavonoids could be a better choose for CBP. Moreover, the flavonoids therapy has an excellent safety profile with minor adverse effects.

The relation of passive smoking with cervical cancer: A systematic review and meta-analysis.

BACKGROUND: Published studies about passive smoking and cervical cancer have found inconsistent results. Hence, the present meta-analysis was performed to assess this association. METHODS: A systematical search was performed to identify eligible cohort and case-control studies in PubMed, Scopus, Elsevier ScienceDirect, and Web of Science databases (up to March, 2018). The quality of included studies was assessed by the Newcastle-Ottawa quality scale (NOS). The random effects model (REM) was used to calculate the pooled odds ratio (ORs). Subgroup and sensitivity analyses were performed. Publication bias was assessed by funnel plot, using Begg's test and Egger's test. RESULTS: Around 14 eligible studies were included for analysis, which included a total of 384,995 participants. The pooled ORs of passive smoking with cervical cancer risk was 1.70 (95% CI: 1.40-2.07, I = 64.3%). Subgroups stratified by continent, study design, quality score, and cervical cancer types/phases suggested that the result was robust. For instance, the pooled ORs for the cohort and case-control studies was 1.37 (95% CI: 1.16-1.62, I = 0%) and 2.09 (95% CI: 1.52-2.89, I = 76.6%), respectively. The pooled ORs ranged from 1.61 (95%CI: 1.34-1.92) to 1.77 (95%CI: 1.44-2.16) after one study was removed each time in the sensitivity analyses, indicating that the result was stable. Publication bias was detected by funnel plot and Egger's tests. The recalculated ORs were 1.33 (95% CI: 1.21-1.47). CONCLUSIONS: This meta-analysis provides evidence that passive smoking is associated with an increased risk of cervical cancer.

The neurotoxicity of nanoparticles: A bibliometric analysis.

The aim of this study was to evaluate the global scientific output of neurotoxicity of nanoparticles (NPs) and explore their hot spots and research trends. Articles about the neurotoxicity of NPs between 2008 and 2017 were taken from the Web of Science Core Collection database. The VOSviewer was used to analyze annual publications, countries/institutions, funding agencies, research objects, major journals, and international cooperation. The reference co-citation map and keywords were used to analyze the mechanisms of neurotoxicity of NPs. Six hundred and forty-one eligible studies were included for analysis, and the annual publications increased with time in the past decade. Based on the bibliometric analysis, China and the United States were the main countries in this field. Metals and metal oxides were the main types of NPs. Cell, rat, and mouse were the primary research objects of NPs. The main research hot spots might focus on the pathogenesis of NPs, such as oxidative stress and apoptosis. This study will help researchers understand the research status, hot spots, and trends of neurotoxicity of NPs.

Protective effect of calpeptin on acrylamide-induced microtubule injury in sciatic nerve.

The present study aimed to investigate the protective effect and mechanism of calpeptin (CP) on acrylamide (ACR)-induced microtubule (MT) injury in the sciatic nerve of rats. All rats were divided into four groups (control, CP, ACR, and ACR + CP):1 ml/kg saline, 200 µg/kg CP, 30 mg/kg ACR, and 30 mg/kg ACR plus 200 µg/kg CP were administered to the corresponding rats for 4 weeks through intraperitoneal injection. Body weight and neurobehavioral indicators were measured weekly and α-tubulin, ß-tubulin, and other concerned proteins were estimated by western blotting and immunohistochemistry. At 4 weeks, decreased body weight, increased gait scores, increased hindlimb splay, and decreased time of fall of ACR rats were observed compared with those of control rats. All these mentioned changes were restored in the ACR + CP group compared with the ACR group. After 4 weeks of administration, western blotting and immunohistochemistry revealed significant increase in the protein levels of ß-tubulin, calpain I, calpain II, Tau, microtubule-associated protein 2 (MAP2), protein kinase C, and cyclin-dependent kinase 5 in the ACR group compared with the control group; these increases were significantly lower in the ACR + CP group than in the ACR group. Furthermore, histopathological examination revealed loose arrangement, disorganised structure, uneven density, and exfoliated perineurium in the ACR group, and CP administration improved these changes significantly. The present results suggest that CP has an intervening effect on ACR-induced MT injury. A possible mechanism is that calpain maintains the stability of MTs by regulating the metabolism of Tau and MAP2.

Calpeptin is neuroprotective against acrylamide-induced neuropathy in rats.

The aim of this study is to explore the potent neuroprotective effect of calpeptin (CP) on neuron damage induced by acrylamide (ACR) and its mechanism. Behavioural indicators such as hind limb splay, rota-rod performance, and gait analysis were assessed weekly to evaluate neurobehavioural changes after ACR and/or CP administration. The histopathological alterations and the changes of µ-calpain, m-calpain, microtubule-associated protein 2 (MAP2), and α-tubulin and ß-tubulin protein levels in spinal cord were determined. Results showed that after administration of 30 mg/kg ACR, decreased body weight, attenuated neurobehavioural function, injury of motor neuron, increased protein levels of m-calpain and ß-tubulin, suppressed MAP2 protein level, and no significant changes of µ-calpain and α-tubulin protein levels were observed compared with the control group rats. After administration of 200 µg/kg CP, partially restored body weight and neurobehavioural function, improvement of motor neuron injury, decreased protein levels of m- calpain and ß-tubulin, and reversed effects of MAP2 protein level were observed compared with the ACR group rats. Our results suggested that CP alleviates neuropathy induced by ACR in rats. The calpain's overactivation causes the degrading of MAP2 and eventually leads to the destruction of microtubules (MTs), which may be one of the mechanisms of cytoskeletal damage induced by ACR.

Resonance light scattering technique for the determination of protein with rutin and cetylpyridine bromide system.

A new resonance light scattering (RLS) assay of protein is presented. In Tris-NaOH (pH = 10.93) buffer, the RLS of rutin-cetylpyridine bromide (CPB) system can be greatly enhanced by protein, including bovine serum albumin (BSA) and human serum albumin (HSA). The enhanced RLS intensities are in proportion to the concentration of proteins in the range of 5 x 10(-9) to 2.5 x 10(-6) g ml(-1) for BSA and 2.5 x 10(-8) to 3.5 x 10(-6) g ml(-1) for HSA. The detection limits (S/N = 3) are 3.0 ng ml(-1) for BSA and 10.0 ng ml(-1) for HSA. Samples are determined satisfactorily.

The fluorescence enhancement effect of Tb-Gd-adenosine triphosphate-phen system and its analytical application.

It is found that the fluorescence of Tb-adenosine triphosphate (ATP)-phenanthroline (phen) system can be enhanced by Gd(3+). The fluorescence enhancement of the Tb-Gd-ATP-phen system is considered to originate from intramolecular and intermolecular energy transfers, and the energy-insulating sheath effect of Gd-ATP-phen complex. In addition, a new energy transfer pathway in Tb-ATP-phen system is proposed. As a mediator, phen can transfer the energy absorbed by ATP to Tb(3+) through the stacking action between aromatic ring of phen and purine ring of ATP. The proposed method has been used to determine trace amount of ATP. The detection limit is 5.4 x 10(-9)mol/l, which is about 40 times lower than that of the Tb-ATP-phen system. The proposed method is one of the most sensitive fluoremetries of ATP.

Study of the reaction between the nucleic acid and Y-BPMPHD-CTMAB complex and its analytical application.

The fluorescence quenching of the Y-BPMPHD-CTMAB by nucleic acids is reported. It is considered that the Y-BPMPHD-CTMAB can form a large complex with nucleic acid through the electrostatic attraction in the pH range of 4.2-6.8. Under optimal conditions, the difference of fluorescence intensity between the system without and with nucleic acids is proportional to the concentration of nucleic acids over the range of 4.5 x 10(-8)-1.2 x 10(-5) g/mL for fsDNA and 3.2 x 10(-8)-3.0 x 10(-5) g/mL for yRNA, respectively. The detection limits are 14.0 ng/mL for fsDNA and 21.0 ng/mL for yRNA. The method is applied for the determination of nucleic acids in actual sample, and the result obtained is satisfactory.

Study on the fluorescent enhancement effect in terbium-gadolinium-protein-sodium dodecyl benzene sulfonate system and its application on sensitive detection of protein at nanogram level.

The co-luminescence effect in a terbium-gadolinium-protein-sodium dodecyl benzene sulfonate (SDBS) system is reported here. Based on it, the sensitive quantitative analysis of protein at nanogram levels is established. The co-luminescence mechanism is studied using fluorescence, resonance light scattering (RLS), absorption spectroscopy and NMR measurement. It is considered that protein could be unfolded by SDBS, then a efficacious intramolecular fluorescent energy transfer occurs from unfolded protein to rare earth ions through SDBS acting as a "transfer bridge" to enhance the emission fluorescence of Tb3+ in this ternary complex of Tb-SDBS-BSA, where energy transfer from protein to SDBS by aromatic ring stacking is the most important step. Cooperating with the intramolecular energy transfer above is the intermolecular energy transfer between the simultaneous existing complexes of both Tb3+ and Gd3+. The fluorescence quantum yield is increased by an energy-insulating sheath, which is considered to be another reason for the resulting enhancement of the fluorescence. Förster theory is used to calculate the distribution of enhancing factors and has led to a greater understanding of the mechanisms of energy transfer.

The fluorescence enhancement effect of the Tb-Gd-guanosine-5'-triphosphate-phen system and its analytical application.

It has been found that Tb(3+) can react with guanosine-5'-triphosphate (GTP) and o-phenanthroline (phen), resulting in the intrinsic fluorescence of Tb(3+). This fluorescence can be enhanced by adding La(3+), Gd(3+), Lu(3+), Sc(3+), Y(3+), and so on, among which Gd(3+) produces the greatest enhancement. These are new co-luminescence systems. The experiments indicate under optimum conditions, the fluorescence intensity of the Tb-Gd-GTP-phen system is proportional to the concentration of GTP over the range 1x10(-9) to 3x10(-5) mol/l. The detection limit is 3.1x10(-10) mol/l. The proposed method provides the most sensitive fluorimetry of GTP so far. The mechanism of the Tb-Gd-GTP-phen system has also been studied. The data indicates that there is a large congeries of Tb-Gd-GTP-phen, and the fluorescence enhancement of the Tb-Gd-GTP-phen system is considered to originate from intramolecular and intermocular energy transfers, and the energy-insulating sheath of the Gd complex.

Study on the interaction between nucleic acids and cationic surfactants.

The interactions of nucleic acids and cationic surfactants (cetylpyridine bromide (CPB) and cetyltrimethylammonium bromide (CTMAB)) in aqueous solution have been studied using the techniques of resonance light scattering (RLS) spectroscopy, the absorption spectroscopy, zeta potential assay and NMR assignment measurement. It is considered that CPB or CTMAB can assemble on the surface of nucleic acid via electrostatic and hydrophobic forces, which results in the formation of large associate of nucleic acid-cationic surfactant and RLS enhancement of nucleic acid. Besides these forces, the pi-pi stacking force between CPB and nucleic acid also exists in the associate. In comparison with CTMAB, CPB has larger enhancement on RLS of nucleic acid, which is attributed to that the enhancement of the former is only due to the absorption of the bases of nucleic acid, while the enhancement of the latter is own to the synergetic resonance caused by the absorption of both bases of nucleic acid and the pyridyl in CPB. These results have important implication for understanding the influence of surfactants on nucleic acid functionality in life science.

Analysis of tryptophan at nmoll(-1) level based on the fluorescence enhancement of terbium-gadolinium-tryptophan-sodium dodecyl benzene sulfonate system.

It is found that Tb(3+) can react with tryptophan (Trp) and sodium dodecyl benzene sulfonate (SDBS), and emits the intrinsic fluoresence of Tb(3+). The fluorescence intensity can be enhanced by La(3+), Gd(3+), Lu(3+), Sc(3+) and Y(3+), among which Gd(3+) has the greatest enhancement. This is a new co-luminescence system. The studies indicate that in the Tb-Gd-Trp-SDBS system, there is both Tb-Trp-SDBS and Gd-Trp-SDBS complexes, and they aggregate together and form a large congeries. The fluorescence enhancement of the Tb-Gd-Trp-SDBS system is considered to originate from intramolecular and intermolecular energy transfers, and the energy-insulating sheath effect of Gd-Trp-SDBS complex. Under the optimum conditions, the enhanced intensity of fluorescence is in proportion to the concentration of Trp in the range from 4x10(-8) to 4x10(-5)moll(-1). The detection limit is 10(-9)moll(-1). The proposed method is one of the most sensitive fluoremetries of Trp.