Quantifying Atomically Dispersed Catalysts Using Deep Learning Assisted Microscopy.

The catalytic performance of atomically dispersed catalysts (ADCs) is greatly influenced by their atomic configurations, such as atom-atom distances, clustering of atoms into dimers and trimers, and their distributions. Scanning transmission electron microscopy (STEM) is a powerful technique for imaging ADCs at the atomic scale; however, most STEM analyses of ADCs thus far have relied on human labeling, making it difficult to analyze large data sets. Here, we introduce a convolutional neural network (CNN)-based algorithm capable of quantifying the spatial arrangement of different adatom configurations. The algorithm was tested on different ADCs with varying support crystallinity and homogeneity. Results show that our algorithm can accurately identify atom positions and effectively analyze large data sets. This work provides a robust method to overcome a major bottleneck in STEM analysis for ADC catalyst research. We highlight the potential of this method to serve as an on-the-fly analysis tool for catalysts in future in situ microscopy experiments.

GAP-43 is involved in the orientation of cell division by interacting with GΑI during neurogenesis.

Purpose: Recent studies have shown that growth-associated protein-43 (GAP-43) may influence the mitotic-spindle orientation of Madin-Darby Canine Kidney (MDCK) cells through interacting with G proteins in vitro. However, whether GAP-43 interacts with the G proteins under the influence of mitotic spindle positioning related to the orientation of cell division during neurogenesis remains unclear. In order to explore the molecular mechanism in vivo, the GAP-43 transgenic mice were produced and the angles of cell division in the ventricular zone (VZ) during neurogenesis (embryonic period between 13.5 and 17.5 days) were measured in both transgenic mice and wild type mice by spindle angle analysis.Materials and methods: The interaction of GAP-43 and Gαi was detected by co-immunoprecipitation (co-IP), whereas the localization of GAP-43 was determined by immunofluorescence.Results: The results obtained using co-IP and immunofluorescence showed that GAP-43 is localized on the cell membrane and interacts with Gαi. This interaction dramatically induced a significant increase in the proportion of horizontally and intermediately dividing cells during the embryonic period of 13.5 days in the transgenic mouse brain, as observed by spindle angle analysis.Conclusions: It can be concluded that GAP-43 is involved in the orientation of cell division by interacting with Gαi, and that this may be an important mechanism for neurogenesis in the mammalian brain.

Investigation into FlhFG reveals distinct features of FlhF in regulating flagellum polarity in Shewanella oneidensis.

Rod-shaped bacterial cells are polarized, with many organelles confined to a polar cellular site. In polar flagellates, FlhF and FlhG, a multiple-domain (B-N-G) GTPase and a MinD-like ATPase respectively, function as a cognate pair to regulate flagellar localization and number as revealed in Vibrio and Pseudomonas species. In this study, we show that FlhFG of Shewanella oneidensis (SoFlhFG), a monotrichous γ-proteobacterium renowned for respiratory diversity, also play an important role in the flagellar polar placement and number control. Despite this, SoFlhFG exhibit distinct features that are not observed in the characterized counterparts. Most strikingly, the G domain of SoFlhF determines the polar placement, contrasting the N domain of the Vibrio cholerae FlhF. The SoFlhF N domain in fact counteracts the function of the G domain with respect to the terminal targeting in the absence of the B domain. We further show that GTPase activity of SoFlhF is essential for motility but not positioning. Overall, our results suggest that mechanisms underlying the polar placement of organelles appear to be diverse, even for evolutionally relatively conserved flagellum.

Effects of FlrBC on flagellar biosynthesis of Shewanella oneidensis.

As a most conserved complex molecular machine made up of a large number of structural subunits, the flagellum is under tight regulation by hierarchical arrangements. Although variations in polar flagellar systems are found, most of them are restricted to multiple-copy components, such as flagellins and stators. Therefore, these features are regarded to be peripheral relative to the comprehensive conservation. In this study, however, we present evidence to show that the difference in highly conserved polar flagellar systems can be surprisingly profound, even at the heart of the classical regulatory hierarchy. In Gram-negative Shewanella oneidensis, two-component system FlrBC, whose counterpart is essential for flagellar biosynthesis and motility by directly controlling expression of class III genes in polarly flagellated bacteria such as Vibrio cholerae, is dispensable for the process. The system directly controls expression of the flaA gene, encoding a flagellin of weak motility. We further show that the ratio of two flagellins, FlaA and FlaB, determines motility of a flagellum. More strikingly, overproduction of FlrC results in a peritrichously multi-flagellated phenotype, and FlrC is likely to function as an activator in its unphosphorylated form for transcription of the flaA gene, contrasting the previously characterized counterpart.

Dual polarization of microglia isolated from mixed glial cell cultures.

Microglia are versatile immune effector cells of the CNS and are sensitive to various stimuli. The different methods used to isolate microglia may affect some of their characteristics, such as their polarization state. The influence of cell sorting methods on the polarization state of microglia has never been studied. Mixed glial culture system (MGCS) and magnetic activated cell sorting (MACS) are two methods that are commonly used to purify microglia. This study compares the immunological states between microglia isolated by MGCS and microglia isolated by MACS. We show that microglia isolated by MGCS exhibit a stronger immune-activated state than microglia isolated by MACS. They present an elevated phagocytic ability and high levels of markers associated with classical activation (M1) and alternative activation (M2). In addition, high levels of M1-type and M2-type chemokine (C-C motif) ligand 2 and transforming growth factor-ß1 were detected in the culture medium of mixed glial cells. Our results show that microglia isolated by MGCS are in an immune-activated state, whereas microglia isolated by MACS appear to be closer to their primary in vivo state. Therefore, the immune status of microglia, depending on the protocol used to purify them, should be carefully considered in neuropathology research.

Distinct roles of major peptidoglycan recycling enzymes in ß-Lactamase production in Shewanella oneidensis.

ß-Lactam antibiotics were the earliest discovered and are the most widely used group of antibiotics that work by inactivating penicillin-binding proteins to inhibit peptidoglycan biosynthesis. As one of the most efficient defense strategies, many bacteria produce ß-lactam-degrading enzymes, ß-lactamases, whose biochemical functions and regulation have been extensively studied. A signal transduction pathway for ß-lactamase induction by ß-lactam antibiotics, consisting of the major peptidoglycan recycling enzymes and the LysR-type transcriptional regulator, AmpR, has been recently unveiled in some bacteria. Because inactivation of some of these proteins, especially the permease AmpG and the ß-hexosaminidase NagZ, results in substantially elevated susceptibility to the antibiotics, these have been recognized as potential therapeutic targets. Here, we show a contrasting scenario in Shewanella oneidensis, in which the homologue of AmpR is absent. Loss of AmpG or NagZ enhances ß-lactam resistance drastically, whereas other identified major peptidoglycan recycling enzymes are dispensable. Moreover, our data indicate that there exists a parallel signal transduction pathway for ß-lactamase induction, which is independent of either AmpG or NagZ.

Evidence for function overlapping of CymA and the cytochrome bc1 complex in the Shewanella oneidensis nitrate and nitrite respiration.

Shewanella oneidensis is an important model organism for its versatility of anaerobic respiration. CymA, a cytoplasmic membrane-bound tetraheme c-type cytochrome, plays a central role in anaerobic respiration by transferring electrons from the quinone pool to a variety of terminal reductases. Although loss of CymA results in defect in respiration of many electron acceptors (EAs), a significant share of the capacity remains in general. In this study, we adopted a transposon random mutagenesis method in a cymA null mutant to identify substituent(s) of CymA with respect to nitrite and nitrate respiration. A total of 87 insertion mutants, whose ability to reduce nitrite was further impaired, were obtained. Among the interrupted genes, the petABC operon appeared to be the most likely candidate given the involvement of the cytochrome bc1 complex that it encodes in electron transport. Subsequent analyses not only confirmed that the complex and CymA were indeed functionally overlapping in nitrate/nitrite respiration but also revealed that both proteins were able to draw electrons from ubiquinone and menaquinone. Furthermore, we found that expression of the bc1 complex was affected by oxygen but not nitrate or nitrite and by global regulators ArcA and Crp in an indirect manner.

Novel pyrazoline derivatives as bi-inhibitor of COX-2 and B-Raf in treating cervical carcinoma.

Twenty four pyrazoline derivatives modified from Celecoxib were designed and synthesized as bi-inhibitor of COX-2 and B-Raf. They were evaluated for their COX-1/COX-2/B-Raf inhibitory and anti-proliferation activities. Compound A3 displayed the most potent activity against COX-2 and HeLa cell line (IC50=0.008 µM; GI50=19.86 µM) and showed superb COX-1/COX-2 selectivity (>500), being more potent and selective than positive control Celecoxib or 5-fluorouracil. Compounds A5 and B5 were introduced best B-Raf inhibitory activities (IC50=0.15 µM and 0.12 µM, respectively). Compound A4 retained superb bioactivity against COX-2 and HeLa cell line (IC50=0.015 µM; GI50=23.82 µM) and displayed moderate B-Raf inhibitory activity (IC50=3.84 µM). Docking simulation was conducted to give binding patterns. QSAR models were built using bioactivity data and optimized conformations to provide a future modification of COX-2/B-Raf inhibitors.

Temporal expression patterns of insulin-like growth factor binding protein-4 in the embryonic and postnatal rat brain.

BACKGROUND: IGFBP-4 has been considered as a factor involving in development of the central nervous system (CNS), but its role needs to be further clarified. In present study, the localization of IGFBP-4 expression in the embryonic forebrain, midbrain and hindbrain was determined using immunohistochemistry, and the levels of IGFBP-4 protein and mRNA were semi-quantified using RT-PCR and Western blot in the embryonic (forebrain, midbrain and hindbrain) and postnatal brain (cerebral cortex, cerebellum and midbrain). RESULTS: A clear immunoreactivity of IGFBP-4 covered almost the entire embryonic brain (forebrain, midbrain, hindbrain) from E10.5 to E18.5, except for the area near the ventricle from E14.5. The change of IGFBP-4 mRNA level was regularly from E10.5 to E18.5: its expression peaked at E13.5 and E14.5, followed by gradual decreasing from E15.5. The expression of IGFBP-4 protein was similar to that of mRNA in embryonic stage. After birth, the pattern of IGFBP-4 expression was shown to be rather divergent in different brain areas. In the cerebral cortex, the IGFBP-4 mRNA increased gradually after birth (P0), while the protein showed little changes from P0 to P28, but decreased significantly at P70. In the cerebellum, the IGFBP-4 mRNA decreased gradually from P0, reached the lowest level at P21, and then increased again. However, its protein level gradually increased from P0 to P70. In the midbrain, the IGFBP-4 mRNA first decreased and reached its lowest level at P28 before it increased, while the protein remained constant from P0 to P70. At P7, P14, P21, P28 and P70, the levels of IGFBP-4 mRNA in the cerebral cortex were significantly higher than that in the cerebellum or in the midbrain. Differently, the protein levels in the cerebellum were significantly higher than that either in the cerebral cortex or in the midbrain at P14, P21, P28 and P70. CONCLUSIONS: The temporal expression pattern of IGFBP-4 in the embryonic brain from E10.5 to E18.5 was consistent with the course of neurogenesis in the ventricular zone, suggesting an important role of IGFBP-4 in regulating differentiation of neural stem cells. A strikingly higher abundance of the IGFBP-4 protein observed in the cerebellum from P14 to P70 suggests that IGFBP-4 may participate in the maintenance of cerebellar plasticity.

A One-Stage Domain Adaptation Network With Image Alignment for Unsupervised Nighttime Semantic Segmentation.

In this paper, we tackle the problem of semantic segmentation for nighttime images that plays an equally important role as that for daytime images in autonomous driving, but is also much more challenging due to very poor illuminations and scarce annotated datasets. It can be treated as an unsupervised domain adaptation (UDA) problem, i.e., applying other labeled dataset taken in the daytime to guide the network training meanwhile reducing the domain shift, so that the trained model can generalize well to the desired domain of nighttime images. However, current general-purpose UDA approaches are insufficient to address the significant appearance difference between the day and night domains. To overcome such a large domain gap, we propose a novel domain adaptation network "DANIA" for nighttime semantic image segmentation by leveraging a labeled daytime dataset (the source domain) and an unlabeled dataset that contains coarsely aligned day-night image pairs (the target daytime and nighttime domains). These three domains are used to perform a multi-target adaptation via adversarial training in the network. Specifically, for the unlabeled day-night image pairs, we use the pixel-level predictions of static object categories on a daytime image as a pseudo supervision to segment its counterpart nighttime image. We also include a step of image alignment to relieve the inaccuracy caused by the misalignment between day-night image pairs by estimating a flow to refine the pseudo supervision produced by daytime images. Finally, a re-weighting strategy is applied to further improve the predictions, especially boosting the prediction accuracy of small objects. The proposed DANIA is a one-stage adaptation framework for nighttime semantic segmentation, which does not train additional day-night image transfer models as a separate pre-processing stage. Extensive experiments on Dark Zurich and Nighttime Driving datasets show that our DANIA achieves state-of-the-art performance for nighttime semantic segmentation.

Long Non-coding RNA UCA1a Promotes Proliferation via PKM2 in Cervical Cancer.

Cervical cancer is a common malignancy that affects women worldwide. The long non-coding RNA (lncRNA) urothelial cancer-associated 1a (UCA1a) is reported to be significantly upregulated in cervical cancer. However, the exact role of UCA1a in cervical cancer remains unknown. This study aimed to identify two core promoter regions in UCA1a, which are essential for CEBPA-dependent transcription and FOXL1-, FOXL4-, and FOXL6-dependent activation, respectively. RNA sequencing results showed that overexpression of UCA1a resulted in extensive changes in the gene expression profile of HeLa cells, especially in the signaling pathway that regulates tumorgenesis. Mass spectrometry assay was conducted to show that pyruvate kinase M2 (PKM2) was a UCA1a-interacting protein. The 400 ~ 800 nt long region of UCA1a at the 5' end and the A1B domain of PKM2 were critical for the UCA1a-PKM2 interaction. Functional assays were performed to show that PKM2 was sufficient and necessary for UCA1a-induced proliferation of HeLa cells, which was partly due to the regulating of nuclear translocation and stabilization of PKM2. These findings provide a novel mechanism for UCA1a to regulate Hela cells by ubiquitination degradation of PKM2 and suggest that UCA1a may play a key role in the progression of cervical cancer.

Strong confinement of gap modes induced by the film modified electric and magnetic modes in dielectric nanoparticle dimers.

Nanogaps are one of the most useful systems in nanooptics. The gap modes in a film coupled dielectric nanoparticle dimer system are influenced by both of the film and the electric and magnetic modes of the particles. In this work, strong confinement of gap modes of dielectric (Si) nanoparticle dimer on Au/Si film is investigated. The results show an abnormal electric field enhancement obtained between Si nanoparticle dimer on metal film, which is attributed to film coupled electric and magnetic dipole modes in dielectric nanoparticle dimer. The results are further analyzed with mode hybridization theory. Furthermore, the surface enhanced Raman spectroscopy (SERS) is performed to demonstrate these theoretical analyses. The film induced electromagnetic field redistribution in dielectric nanoparticle dimer not only extend the knowledge of dielectric gap modes but also has tremendous applications, e.g. light manipulating in subwavelength, light harvest, surface enhanced spectrum, etc.

Optoplasmonic film for SERS.

Combining plasmonic and photonic elements, optoplasmonic hybrid structure exhibits excellent optical properties beyond conventional plasmonic or photonic structures. In this work, the optoplasmonic film consists of SiO2 microsphere and Au film without any nanostructures is investigated. With the help of a microsphere, the intensity of surface enhanced Raman spectroscopy (SERS) on Au film is highly enhanced (~1000 times) compared to bare Au film. The simulated electromagnetic field points out the enhancement caused by the optical lens effect of SiO2 microsphere that high light intensity is generated under the microsphere to excite surface plasmon on Au film. Furthermore, our data demonstrates the microsphere lens enhancement is greatly influenced by the size of the SiO2 microsphere and wavelength of incident light. This interesting film with a simple configuration could overcome the challenges in the fabrication and store process induced by nanostructures, which play an important role in SERS application. Our work not only enlarges the knowledge of the optoplasmonic hybrid structure, but also exhibits excellent application prospective in light harvest field e.g. enhanced spectrum, photocatalysis, optothermal effect, and hot electron generation, etc.

MicroRNA-373-3p inhibits the growth of cervical cancer by targeting AKT1 both in vitro and in vivo.

OBJECTIVE: In this study, we aimed to investigate the function of microRNA-373-3p (miR-373-3p) in the pathogenesis of cervical cancer. METHODS: Human and mouse cervical cancer cell lines were transfected with miR-373-3p mimic and inhibitor. Cell proliferation and viability were evaluated with Cell Counting Kit-8 (CCK-8) assay and Lactate Dehydrogenase (LDH) assay, respectively. The AKT1-targeting role of miR-373-3p was analyzed by qPCR and Western blot. Finally, a mouse xenograft cervical tumor model was adopted to study the in vivo effect of miR-373-3p on tumor growth and the expression of AKT1. RESULTS: Over-expression of miR-373-3p significantly reduced the proliferation of cervical carcinoma cell line in vitro. In addition, miR-373-3p overexpression also inhibited cervical cancer growth in tumor-bearing mice. Mechanistically, we found that AKT1 gene can be targeted by miR-373-3p. MiR-373-3p mimic decreased the mRNA and protein expression of AKT1, while the miR-373-3p inhibitor increased the level of AKT1 in cervical cancer cells. AKT1 overexpression rescued the proliferation of cervical cancer cells transfected with miR-373-3p. CONCLUSION: MiR-373-3p can serve as a novel anti-tumor microRNA in cervical cancer by targeting AKT1.

Effects of miR-218-1-3p and miR-149 on proliferation and apoptosis of non-small cell lung cancer cells.

The aim of the present study was to explore the effects of miR-218-1-3p and miR-149 on the biological function of non-small cell lung cancer (NSCLC) cells A549. Paired NSCLC and adjacent tissues were obtained from 50 NSCLC patients admitted to Shandong Provincial Chest Hospital Affiliated to Shandong University (Jinan, China) from April 2015 to May 2018. The expression levels of miR-218-1-3p and miR-149 were detected by reverse transcription-quantitative PCR (RT-qPCR). The lung adenocarcinoma A549 cells were assigned into the blank group (without transfection), negative control (NC) group (transfected with miRNA NC), and the transfected groups miR-218-1-3p mimic and miR-149 mimic groups. Proliferation and cell growth were determined by CCK-8 assay and cell invasion ability in vitro was assessed by Transwell assay. Flow cytometry was carried out for the detection of cell apoptosis. RT-qPCR results showed that the expression levels of miR-218-1-3p and miR-149 in NSCLC tissues were significantly lower than those in adjacent tissues (P<0.001). At 48 and 72 h, the cell growth of the A549 cells in the miR-218-1-3p mimic and miR-149 mimic groups was significantly lower than that in the NC and blank groups (P<0.05). The number of invasive cells in the miR-218-1-3p mimic and miR-149 mimic groups was significantly lower than that in the NC and blank groups (P<0.05). The apoptotic rate of A549 cells in the miR-218-1-3p mimic and miR-149 mimic groups was significantly higher than that in the NC and blank groups (P<0.05). In conclusion, upregulation of miR-218-1-3p and miR-149 can inhibit the proliferation, invasion and migration of A549 cells in NSCLC, thereby promoting the apoptosis of A549 cells. Thus, miR-218-1-3p and miR-149 can be used as new molecular targets for the diagnosis and treatment of NSCLC.

Eugenol Attenuates Cerebral Ischemia-Reperfusion Injury by Enhancing Autophagy via AMPK-mTOR-P70S6K Pathway.

Eugenol, as an active compound isolated from Acorus gramineus, has been shown to protect against cerebral ischemia-reperfusion (I/R) injury. Nonetheless, the detailed neuroprotective mechanisms of eugenol in cerebral I/R injury have not been elaborated. In the present study, cerebral I/R injury model was established by middle cerebral artery occlusion (MCAO) in rats. HT22 cells were subjected to oxygen-glucose deprivation/reperfusion (OGD/R) to mimic cerebral I/R injury in vitro. The results showed that eugenol pre-treatment relieved cerebral I/R injury as evidenced by improving neurological deficits and reducing infarct volume. Autophagy was induced by MCAO, which was further promoted by eugenol administration. Moreover, rapamycin, an activator of autophagy, promoted eugenol-induced decreases in neurological score, infarct volume, brain water content, and apoptosis. However, pretreatment with 3-MA, an inhibitor of autophagy, led to the opposite results. Similarly, eugenol pretreatment increased the viability and restrained apoptosis of OGD/R-challenged HT22 cells. OGD/R-induced autophagy was strengthened by eugenol. Mechanically, eugenol promoted autophagy through regulating AMPK/mTOR/P70S6K signaling pathway in vivo and in vitro. In conclusion, pretreatment with eugenol attenuated cerebral I/R injury by inducing autophagy via AMPK/mTOR/P70S6K signaling pathway.

An edge-weighted centroidal Voronoi tessellation model for image segmentation.

Centroidal Voronoi tessellations (CVTs) are special Voronoi tessellations whose generators are also the centers of mass (centroids) of the Voronoi regions with respect to a given density function and CVT-based methodologies have been proven to be very useful in many diverse applications in science and engineering. In the context of image processing and its simplest form, CVT-based algorithms reduce to the well-known k -means clustering and are easy to implement. In this paper, we develop an edge-weighted centroidal Voronoi tessellation (EWCVT) model for image segmentation and propose some efficient algorithms for its construction. Our EWCVT model can overcome some deficiencies possessed by the basic CVT model; in particular, the new model appropriately combines the image intensity information together with the length of cluster boundaries, and can handle very sophisticated situations. We demonstrate through extensive examples the efficiency, effectiveness, robustness, and flexibility of the proposed method.

Establishment of an immortalized GABAergic neuronal progenitor cell line from embryonic ventral mesencephalon in the rat.

Effective cell replacement therapies for neurological disease require neuron-restricted precursors as grafted cells. The problem of obtaining sufficient grafts for transplantation can be resolved by creating an appropriate immortalized cell line. In the present study, a thermally controlled immortalized GABAergic neuronal progenitor cell line (RMNE6) was established from E13 rat ventral mesencephalon cells immortalized using the temperature-sensitive mutant of SV40 large T antigen (ts-TAg). RMNE6 cells proliferated rapidly and expressed a neuron-like phenotype at the permissive temperature (33 degrees C), but eventually stopped growing at the non-permissive temperature (39 degrees C). Expression of the neuronal markers PSA-NCAM, beta-tubulin III and MAP2 by RMNE6 cells was confirmed by RT-PCR or immunocytochemistry. Furthermore, these cells exhibited functional GABAergic neuron properties, as evidenced by the expression of glutamate decarboxylase (GAD) as well as the synthesis and release of the neurotransmitter GABA in a calcium-dependent manner. Moreover, RMNE6 cells spontaneously expressed and secreted several neurotrophic factors, such as NGF, BDNF, NT-3, NT-4/5, and GDNF. The cells survived well and kept expression of SV40 Tag, GAD65/67 and GABA in the striatum, at least 28 days after being transplanted in the rat brain. Tumorigenesis assays confirmed the safety of the immortalized cell line in vivo. Taken together, the results support the use of RMNE6 cells as an ideal cell model for transplantation research aimed at the treatment and prevention of neurodegenerative disease.

HPV E6/p53 mediated down-regulation of miR-34a inhibits Warburg effect through targeting LDHA in cervical cancer.

MicroRNAs (miRNA) play crucial roles in regulating cell proliferation, differentiation and developmental timing. Aberrantly expressed miRNAs have recently emerged as key regulators of metabolism. However, little is known about its role in tumor metabolism of cervical cancer. In this study, we determined the oncogenic effects of miRNAs on Warburg effect, a metabolic phenotype that allows cancer cells to utilize glucose even under aerobic conditions. A gain-of-function study was performed in 12 down-regulated miRNAs that frequently reported in cervical cancer. We found that miR-34a plays a suppressive role in Warburg effect as evidenced by decreased lactate production and glucose consumption. Knockdown of oncoprotein E6 expression of human papillomavirus in SiHa and HeLa cells by siRNAs lead to an increased protein level of p53, decreased level of miR-34a, as well as reduced Warburg effect. Subsequently, lactate dehydrogenase A (LDHA), which catalyzes the last key step in glycolysis, was identified as a direct target of miR-34a. Silencing of LDHA or introduction of miR-34a significantly attenuated colony formation ability and invasive capacity of SiHa and HeLa cells, and these effects were fully compromised by reintroduction of LDHA. In conclusion, our findings demonstrated that deregulated miR-34a/LDHA axis induced by HPV E6/p53 signaling facilitates tumor growth and invasion through regulating Warburg effect in cervical cancer, and provided new insights into the mechanism by which miR-34a contributes to the development and progression of cervical cancer.

MicroRNA-497 regulates cisplatin chemosensitivity of cervical cancer by targeting transketolase.

Cervical cancer is one of the most lethal malignancies amongst women, partially because it is unresponsive to many chemotherapeutic drugs. The mechanism underlying cisplatin (DDP) resistance in cervical cancer remains largely elusive. In this study, by detecting the 12 most reported down-regulated miRNAs in chemotherapy-sensitive and -resistant cervical cancer cells, we found that miR-497 was significantly reduced in chemotherapy-resistant HeLa/DDP cells and contributed to DDP chemosensitivity. Transketolase (TKT), a thiamine-dependent enzyme that plays a role in the channeling of excess glucose phosphates to glycolysis in the pentose phosphate pathway, was identified as a direct target of miR-497. TKT expression in clinical specimens was characterized by immunohistochemistry and the result showed that TKT was highly expressed in 81.1% (60/74) of samples examined. Data from Oncomine databases revealed that TKT was significantly up-regulated in cervical cancer tissues compared to normal controls. Gain-of-function and loss-of-function studies showed that the miR-497/TKT axis was a critical modulator in DDP chemosensitivity as demonstrated by cell viability and apoptosis assays. Mechanistically, DDP chemosensitivity induced by the miR-497/TKT axis was associated with glutathione (GSH) depletion and reactive oxygen species (ROS) generation, and GSH treatment effectively abrogated miR-497/TKT-mediated chemosensitivity. In conclusion, these findings suggest that a deregulated miR-497/TKT axis has important implications in the cervical cancer cellular response to DDP, and thus targeting this axis may be a promising way to improve chemosensitivity in cervical cancer.