RGCC-mediated PLK1 activity drives breast cancer lung metastasis by phosphorylating AMPKα2 to activate oxidative phosphorylation and fatty acid oxidation.

BACKGROUND: More than 90% of the mortality of triple-negative breast cancer (TNBC) patients is attributed to cancer metastasis with organotropism. The lung is a frequent site of TNBC metastasis. However, the precise molecular mechanism for lung-specific metastasis of TNBC is not well understood. METHODS: RNA sequencing was performed to identify patterns of gene expression associated with lung metastatic behavior using 4T1-LM3, MBA-MB-231-LM3, and their parental cells (4T1-P, MBA-MB-231-P). Expressions of RGCC, called regulator of cell cycle or response gene to complement 32 protein, were detected in TNBC cells and tissues by qRT-PCR, western blotting, and immunohistochemistry. Kinase activity assay was performed to evaluate PLK1 kinase activity. The amount of phosphorylated AMP-activated protein kinase α2 (AMPKα2) was detected by immunoblotting. RGCC-mediated metabolism was determined by UHPLC system. Oxidative phosphorylation was evaluated by JC-1 staining and oxygen consumption rate (OCR) assay. Fatty acid oxidation assay was conducted to measure the status of RGCC-mediated fatty acid oxidation. NADPH and ROS levels were detected by well-established assays. The chemical sensitivity of cells was evaluated by CCK8 assay. RESULTS: RGCC is aberrantly upregulated in pulmonary metastatic cells. High level of RGCC is significantly related with lung metastasis in comparison with other organ metastases. RGCC can effectively promote kinase activity of PLK1, and the activated PLK1 phosphorylates AMPKα2 to facilitate TNBC lung metastasis. Mechanistically, the RGCC/PLK1/AMPKα2 signal axis increases oxidative phosphorylation of mitochondria to generate more energy, and promotes fatty acid oxidation to produce abundant NADPH. These metabolic changes contribute to sustaining redox homeostasis and preventing excessive accumulation of potentially detrimental ROS in metastatic tumor cells, thereby supporting TNBC cell survival and colonization during metastases. Importantly, targeting RGCC in combination with paclitaxel/carboplatin effectively suppresses pulmonary TNBC lung metastasis in a mouse model. CONCLUSIONS: RGCC overexpression is significantly associated with lung-specific metastasis of TNBC. RGCC activates AMPKα2 and downstream signaling through RGCC-driven PLK1 activity to facilitate TNBC lung metastasis. The study provides implications for RGCC-driven OXPHOS and fatty acid oxidation as important therapeutic targets for TNBC treatment.

Treating Autoimmune Inflammatory Diseases with an siERN1-Nanoprodrug That Mediates Macrophage Polarization and Blocks Toll-like Receptor Signaling.

The clinical application of small interfering RNA (siRNA) drugs provides promising opportunities to develop treatment strategies for autoimmune inflammatory diseases. In this study, siRNAs targeting the endoplasmic reticulum to nucleus signaling 1 (ERN1) gene (siERN1) were screened. Two cationic polymers, polyethylenimine (PEI) and poly(ß-amino amine) (PBAA), which can improve the efficiency of the siRNA transfection, were used as siERN1 delivery carriers. They were implemented to construct a nanodrug delivery system with macrophage-targeting ability and dual responsiveness for the treatment of autoimmune inflammatory diseases. In terms of the mechanism, siERN1 can regulate the intracellular calcium ion concentration by interfering with the function of inositol 1,4,5-trisphosphate receptor 1/3 (IP3R1/3) and thus inducing M2 polarization of macrophages. Furthermore, siERN1-nanoprodrug [FA (folic acid)-PEG-R(RKKRRQRRR)-NPs(ss-PBAA-PEI)@siERN1] acts as a conductor of macrophage polarization by controlling the calcium ion concentration and is an inhibitor of MyD88-dependent Toll-like receptor signaling. The results revealed that the FA-PEG-R-NPs@siERN1 has universal biocompatibility, long-term drug release responsiveness, superior targeting properties, and therapeutic effects in mouse collagen-induced arthritis and inflammatory bowel disease models. In conclusion, this study reveals a potential strategy to treat autoimmune inflammatory disorders.

m6A Demethylase FTO Regulates Dopaminergic Neurotransmission Deficits Caused by Arsenite.

Arsenite exposure is known to increase the risk of neurological disorders via alteration of dopamine content, but the detailed molecular mechanisms remain largely unknown. In this study, using both dopaminergic neurons of the PC-12 cell line and C57BL/6J mice as in vitro and in vivo models, our results demonstrated that 6 months of arsenite exposure via drinking water caused significant learning and memory impairment, anxiety-like behavior and alterations in conditioned avoidance and escape responses in male adult mice. We also were the first to reveal that the reduction in dopamine content induced by arsenite mainly resulted from deficits in dopaminergic neurotransmission in the synaptic cleft. The reversible N6- methyladenosine (m6A) modification is a novel epigenetic marker with broad roles in fundamental biological processes. We further evaluated the effect of arsenite on the m6A modification and tested if regulation of the m6A modification by demethylase fat mass and obesity-associated (FTO) could affect dopaminergic neurotransmission. Our data demonstrated for the first time that arsenite remarkably increased m6A modification, and FTO possessed the ability to alleviate the deficits in dopaminergic neurotransmission in response to arsenite exposure. Our findings not only provide valuable insight into the molecular neurotoxic pathogenesis of arsenite exposure, but are also the first evidence that regulation of FTO may be considered as a novel strategy for the prevention of arsenite-associated neurological disorders.

Disruption of glutamate neurotransmitter transmission is modulated by SNAP-25 in benzo[a]pyrene-induced neurotoxic effects.

Benzo[a]pyrene (B[a]P), a ubiquitous chemical contaminant in the environment, is a well-established neurotoxicant to human. However, the molecular mechanisms for B[a]P neurotoxicity are still unclear. In the present study, after treating Sprague-Dawley rats with 0.02, 0.2 and 2.0mg/kg/day B[a]P for 7 weeks [from postnatal day (PND) 5 to PND54], our results showed that B[a]P exposure caused a significant deficits in learning and memory function. By using U87 cells as in vitro model, the significant cytotoxicity and the induction of apoptosis caused by B[a]P were further verified. More importantly, we demonstrated for the first time that B[a]P exposure caused the disruption of glutamate (Glu) neurotransmitter transmission by decreasing the level of Glu, reducing the expression of Glu receptors (GluR1 and GluR2), enhancing the level of SNAP-25, widening the synaptic cleft, and ultimately producing the neurotoxic effects in both cells and animals. Our results will provide novel evidence to reveal the possible role of SNAP-25 in B[a]P-induced neurotoxicity and may be helpful for searching the potential strategy for the prevention measures against B[a]P neurotoxicity.

Cadmium Exposure is Associated with the Prevalence of Dyslipidemia.

BACKGROUND: Cadmium is a widespread environmental and occupational pollutant that accumulates in human body with a biological half-life exceeding 10 years. Cadmium exposure has been demonstrated to increase rates of cardiovascular diseases. Whether occupational cadmium exposure is associated with the increase in the prevalence of dyslipidemia and hence contributes to the risk of cardiovascular diseases is still equivocal. To test the hypothesis that exposure to cadmium is related to the prevalence of dyslipidemia, we examined the associations between blood cadmium concentration and the prevalence of dyslipidemia in workers occupationally exposed to cadmium in China. METHODS: A cross-sectional survey on demographic data, blood cadmium level and lipid profile in cadmium exposed workers from seven cadmium smelting factories in central and southwestern China was conducted. We measured blood cadmium concentration and lipid components of 1489 cadmium exposed workers. The prevalence of dyslipidemia was compared across blood cadmium quartiles. Associations between the blood cadmium concentrations and the prevalence of dyslipidemia were assessed using confounder adjusted linear and logistic regressions. RESULTS: The blood cadmium concentration was 3.61±0.84µg/L ( mean ±SD). The prevalence of dyslipidemia in this occupational population was 66.3%. Mean blood cadmium concentration of workers with dyslipedemia was significantly higher than that of workers without dyslipidemia (p <0.01). The prevalence of dyslipidemia increased dose-dependently with elevations in blood cadmium concentrations (p for trend <0.001). Elevated levels of blood cadmium were associated with BMI, education attainment, income, smoking status and duration of exposure (all p <0.01). Furthermore, the profile of blood lipid was obviously changed in this occupational population. The prevalence of high TC, high TG, Low HDL-C and high LDL-C rose with increases in blood cadmium levels dose-dependently (p for trend <0.001). The odds ratios (95% confidence interval) for dyslipidemia across the increasing blood cadmium quartiles were 1.21(1.16-1.55), 1.56(1.11-1.87), 1.79(1.26-2.25) respectively (referencing to 1.00; p for trend <0.001), after multivariate adjustment for BMI, education attainment, income, lifestyle factors and duration of exposure, the association between blood cadmium concentrations and the prevalence of dyslipidemia remained unchanged (all p for trend <0.001). CONCLUSION: Elevated blood cadmium concentration is associated with prevalence of dyslipidemia. Cadmium exposure could alter lipid metabolism in humans. It is imperative to control cadmium exposure of occupational population in cadmium related industries and reduce adverse health effects.

[Effect of Benzo [α]pryene and Butylated Hydroxylanisole on Learning and Memory in Rats].

OBJECTIVE: To investigate the neurotoxic effect of benzo[α]pryene (B[α]P) and protective effect of butylated hydroxyl anisole (BHA) on learning and memory in hippocampus of rats. METHODS: Ninety male, SD rats were randomly divided into blank control group, solvent control group, B[α]P exposed group [(2 mg/(kg x d)], BRA group [50 mg/(kg x d)] and B[α]P + BHA combined group. Rats were given the appropriate dose oral treatment according to body mass and group (the same volume of saline and peanut oil were given to blank and solvent control group, respectively) for 90 d. After 90 d exposer, Morris water maze (MWM) was conducted to estimate rats' learning and memory ability. The level of malonaldehyde (MDA), superoxide dismutase (SOD) activity, Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activity and Ca2+ concentration were measured after rats were sacrificed and brain tissue were removed. RESULTS: Behavioral test results showed that the escape latency of B[α]P exposed group were significantly increased than other groups (P < 0.05); however, the number of crossing platform (4.13 ± 0.78) were decreased significant. The level of MDA [( 2.46 ± 0.39) nmol/mg prot.] and Ca2+ concentration [(146.3 ± 16.68) nmol/L] in the B[α]P exposed group increased significant, while the activity of Na(+)-K(+)-ATPase and SOD [(76.1 ± 11.42) nmol/mg prot.] were significantly decreased. Compared with B[α]P group, each index in B[α]P+ BHA combined group improved significantly (P < 0.05), besides, there were no statistically difference when compared with solvent control group. CONCLUSION: The neurotoxic effect of B[α]P may be related to the decrease of ATPase activity and the increase of Ca2+ concentration in hippocampus, while BHA can prevent these damages.

[Effects of benzo(a)pyrene exposure on the ATPase activity and content of Ca²âº in the hippocampus of neonatal SD rats].

OBJECTIVE: To investigate the effect of benzo(α)pyrene on the ATPase activity and content of Ca²âº in the hippocampus of neonatal SD rats. METHODS: Sixty male and 60 female 4-days-old neonatal SD rats were randomly divided into 5 groups (n=24): a blank control group, a vehicle control group (peanut oil), 3 benzo(α)pyrene groups (0.02, 0.2 and 2 mg/kg, respectively). SD rats were given benzo(α)pyrene (dissolved in peanut oil) by gavage daily from postnatal day 4 (PND4) to PND20. The nerve reflex, the condition of neuro-muscle development and motion function were examined in the period of treatment. The colorimetric technique was used to detect the activity of Ca²âº-ATPase and Ca²âº-Mg²âº-ATPase in hippocampus after the treatment. The concentration of Ca²âº of synapse in the hippocampus of rats was detected by fluorescent labeling. RESULTS: The results from the behavior tests showed that duration of surface reflex latency in rats with medium dose of benzo(α)pyrene was longer compared with that in the control group in PND12. The duration of surface reflex latency in rats with high dose of benzo(α) pyrene is longer in PND 14 and PND 16 compared with that in the control group (P<0.05). Compared with the rats in the control group, the activities of Ca²âº-Mg²âº-ATPase and Ca²âº-ATPase in hippocampus in rats with high dose benzo(α) pyrene were significantly decreased, and the degree in the decrease of Ca²âº-ATPase activity was dose-dependent (P<0.05). The contents of Ca²âº in the hippocampus in rats with medium or high dose of benzo(α) pyrene were significantly increased compared with that in the control group (P<0.05), which showed a dose-dependent manner (P<0.05). CONCLUSION: Benzo(α)pyrene exposure led to the decrease in ATPase activity as well as Ca²âº overload of the synapse in the hippocampal tissue, which in turn results in the nerve damage of newborn SD rats.

The monitoring results of electromagnetic radiation of 110-kV high-voltage lines in one urban location in Chongqing P.R. China.

To understand electromagnetic radiation field strength and its influencing factors of certain 110-kV high-voltage lines in one urban area of Chongqing by measuring 110-kV high-voltage line's electromagnetic radiation level. According to the methodology as determined by the National Hygienic Standards, we selected certain adjacent residential buildings, high-voltage lines along a specific street and selected different distances around its vertical projection point as monitoring points. The levels of electromagnetic radiations were measured respectively. In this investigation within the frequency of 5-1,000 Hz both the electric field strength and magnetic field strength of each monitoring sites were lower than the public exposure standards as determined by the International Commission on Non-Ionizing Radiation Protection. However, the electrical field strength on the roof adjacent to the high-voltage lines was significantly higher than that as measured on the other floors in the same buildings (p < 0.05). The electromagnetic radiation measurements of different monitoring points, under the same high-voltage lines, showed the location which is nearer the high-voltage line maintain a consistently higher level of radiation than the more distant locations (p < 0.05). Electromagnetic radiation generated by high-voltage lines decreases proportionally to the distance from the lines. The buildings can to some extent shield (or absorb) the electric fields generated by high-voltage lines nearby. The electromagnetic radiation intensity near high-voltage lines may be mitigated or intensified by the manner in which the high-voltage lines are set up, and it merits attention for the potential impact on human health.