A metabolic intervention strategy to break evolutionary adaptability of tumor for reinforced immunotherapy.

The typical hallmark of tumor evolution is metabolic dysregulation. In addition to secreting immunoregulatory metabolites, tumor cells and various immune cells display different metabolic pathways and plasticity. Harnessing the metabolic differences to reduce the tumor and immunosuppressive cells while enhancing the activity of positive immunoregulatory cells is a promising strategy. We develop a nanoplatform (CLCeMOF) based on cerium metal-organic framework (CeMOF) by lactate oxidase (LOX) modification and glutaminase inhibitor (CB839) loading. The cascade catalytic reactions induced by CLCeMOF generate reactive oxygen species "storm" to elicit immune responses. Meanwhile, LOX-mediated metabolite lactate exhaustion relieves the immunosuppressive tumor microenvironment, preparing the ground for intracellular regulation. Most noticeably, the immunometabolic checkpoint blockade therapy, as a result of glutamine antagonism, is exploited for overall cell mobilization. It is found that CLCeMOF inhibited glutamine metabolism-dependent cells (tumor cells, immunosuppressive cells, etc.), increased infiltration of dendritic cells, and especially reprogrammed CD8+ T lymphocytes with considerable metabolic flexibility toward a highly activated, long-lived, and memory-like phenotype. Such an idea intervenes both metabolite (lactate) and cellular metabolic pathway, which essentially alters overall cell fates toward the desired situation. Collectively, the metabolic intervention strategy is bound to break the evolutionary adaptability of tumors for reinforced immunotherapy.

Vascular responses of penetrating vessels during cortical spreading depolarization with ultrasound dynamic ultrafast Doppler imaging.

The dynamic vascular responses during cortical spreading depolarization (CSD) are causally related to pathophysiological consequences in numerous neurovascular conditions, including ischemia, traumatic brain injury, cerebral hemorrhage, and migraine. Monitoring of the hemodynamic responses of cerebral penetrating vessels during CSD is motivated to understand the mechanism of CSD and related neurological disorders. Six SD rats were used, and craniotomy surgery was performed before imaging. CSDs were induced by topical KCl application. Ultrasound dynamic ultrafast Doppler was used to access hemodynamic changes, including cerebral blood volume (CBV) and flow velocity during CSD, and further analyzed those in a single penetrating arteriole or venule. The CSD-induced hemodynamic changes with typical duration and propagation speed were detected by ultrafast Doppler in the cerebral cortex ipsilateral to the induction site. The hemodynamics typically showed triphasic changes, including initial hypoperfusion and prominent hyperperfusion peak, followed by a long-period depression in CBV. Moreover, different hemodynamics between individual penetrating arterioles and venules were proposed by quantification of CBV and flow velocity. The negative correlation between the basal CBV and CSD-induced change was also reported in penetrating vessels. These results indicate specific vascular dynamics of cerebral penetrating vessels and possibly different contributions of penetrating arterioles and venules to the CSD-related pathological vascular consequences. We proposed using ultrasound dynamic ultrafast Doppler imaging to investigate CSD-induced cerebral vascular responses. With this imaging platform, it has the potential to monitor the hemodynamics of cortical penetrating vessels during brain injuries to understand the mechanism of CSD in advance.

pH and charge reversal-driven nanoplatform for efficient delivery of therapeutics.

Nanomedicine which delivers therapeutics to tumours holds great potential for cancer treatment. However, endosomal trapping and uncontrollable release usually limit the efficiency of nanomedicine. Herein, a smart mesoporous silica based nanoplatform was constructed, in which mesoporous silica nanoparticles (MSNs) serve as the core, capped with pH-induced charge-reversal polymer -PAH-cit- and cationic polyelectrolyte polyethyleneimine (PEI). The oppositely charged polymer can not only act as a gatekeeper for controlled release, but also mediated efficient endosomal escape of the therapeutics. Under the acidic endosomal environment, the hydrolysis of acid-cleavable bonds in PAH-Cit would trigger the charge reversal and endosomal escape of the nanoplatform for efficient drug release. Furthermore, the prepared nanoplatform demonstrated a higher tumor cell proliferation inhibition rate than free theruputics in vitro assays and significantly inhibited tumour growth in the 4T1 tumour model in mice. Therefore, our strategy offers a simple and general nanoplatform to delivery therapeutics to tumours with efficient endosomal escape and controlled release.

Reversal of multidrug resistance in KB cells with tea polyphenol antioxidant capacity.

Tea polyphenol (TP), (-)-epigallocatechin gallate (EGCG) in particular, were examined for their reversal effects on multidrug resistance (MDR) with their antioxidant capacities. TP and EGCG were proved to exert reversal effects on drug resistance KB-A-1 cells by 5.2 and 2.5 times, respectively, but no such effects were found on drug sensitive KB-3-1 cells. With a redox indicator 6-carboxy-2',7'-dichlorodihydrofluorescein (CDCFH), it could be found that the intracellular reactive oxygen species (ROS) decreased in the KB-3-1 cells, which was induced by different concentrations of doxorubicin, whereas the intracellular ROS induced by doxorubicin in KB-A-1 cells maintained a high level. Such observation suggests that drug resistant cells undergo oxidative stress. Furthermore, this elevated redox level in KB-A-1 cells was inhibited by either TP or EGCG. These results demonstrate that the reversal effect of TP and EGCG on MDR acts, at least in part, regulating the doxorubicin induced intracellular concentration of ROS.

Modulation effect of tea polyphenol toward N-methyl-N'-nitro-N-nitrosoguanidine-induced precancerous gastric lesion in rats.

The chemopreventive effect of tea polyphenol (TP) on precancerous gastric lesion was examined. A rat model was established by gavage of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), and different concentrations of TP were given to Wistar rats in drinking water during the 16 weeks of the experiment. The histopathological data showed an effect of TP to lighten the lesions induced by MNNG. By flow cytometry, we demonstrated that TP treatment decreased the proliferation and apoptosis index (AI) induced by MNNG. The arrest in the G0-G1 phase of the cell cycle was also obtained. The results suggested that TP had preventive effect against gastric carcinogenesis at the preinitiation stage and such prevention may be related to the modulation of the balance of cell death and cell proliferation.

Reversal of cancer multidrug resistance by green tea polyphenols.

The aim of this study was to examine the effect and mechanism of green tea polyphenols (TP) on reversal of multidrug resistance (MDR) in a carcinoma cell line. Using the MTT assay, TP was examined for its modulating effects on the drug-resistant KB-A-1 cells and drug-sensitive KB-3-1 cells. When 10 microg mL(-1) (-)-epigallocatechin gallate (EGCG) or 40 microg mL(-1) TP were present simultaneously with doxorubicin (DOX), the IC50 of DOX on KB-A-1 cells decreased from 10.3 +/- 0.9 microg mL(-1) to 4.2 +/- 0.2 and 2.0 +/- 0.1 microg mL(-1), respectively. TP and EGCG enhanced the DOX cytotoxicity on KB-A-1 cells by 5.2- and 2.5-times, respectively, but did not show a modulating effect on KB-3-1 cells. This indicated that both TP and EGCG had reversal effects on the MDR phenotype in-vitro. A KB-A-1 cell xenograft model was established, and the effect of TP on reversing MDR in-vivo was determined. Mechanistic experiments were conducted to examine the uptake, efflux and accumulation of DOX. Cloning and expression of the nucleotide binding domain of the human MDR1 gene in Escherichia coli was established, and by using colorimetry to examine the activity of ATPase to hydrolyse ATP, the ATPase activity of target nucleotide binding domain protein was determined. TP exerted its reversal effects through the inhibition of ATPase activity, influencing the function of P-glycoprotein, and causing a decreased extrusion of anticancer drug and an increased accumulation of anticancer drug in drug resistant cells. Using reverse transcription-polymerase chain reaction, the inhibitory effect of TP on MDR1 gene expression was investigated. Down-regulation of MDR1 gene expression was the main effect, which resulted in the reversal effect of TP on the MDR phenotype. TP is a potent MDR modulator with potential in the treatment of P-glycoprotein mediated MDR cancers.

Quantification of doxorubicin and validation of reversal effect of tea polyphenols on multidrug resistance in human carcinoma cells.

HPLC was used to analyze doxorubicin in multidrug-resistance (MDR) human carcinoma cells. This method is novel, simple, sensitive, linear, accurate and precise. The minimal detectable concentration is 0.2 microg ml(-1). The reversal effects of tea polyphenols on MDR are elucidated by this method. The results indicate that the tea polyphenol, (-)-epigallocatechin gallate, is a potential modulator of MDR.