Müller cells are activated in response to retinal outer nuclear layer degeneration in rats subjected to simulated weightlessness conditions

A microgravity environment has been shown to cause ocular damage and affect visual acuity,but the underlying mechanisms remain unclear.Therefore,we established an animal model of weightlessness via tail suspension to examine the pathological changes and molecular mechanisms of retinal damage under microgravity.After 4 weeks of tail suspension,there were no notable alterations in retinal function and morphology,while after 8 weeks of tail suspension,significant reductions in retinal function were observed,and the outer nuclear layer was thinner,with abundant apoptotic cells.To investigate the mechanism underlying the degenerative changes that occurred in the outer nuclear layer of the retina,proteomics was used to analyze differentially expressed proteins in rat retinas after 8 weeks of tail suspension.The results showed that the expression levels of fibroblast growth factor 2(also known as basic fibroblast growth factor)and glial fibrillary acidic protein,which are closely related to Müller cell activation,were significantly upregulated.In addition,Müller cell regeneration and Müller cell gliosis were observed after 4 and 8 weeks,respectively,of simulated weightlessness.These findings indicate that Müller cells play an important regulatory role in retinal outer nuclear layer degeneration during weightlessness.

Abnormally activated wingless/integrated signaling modulates tumor-associated macrophage polarization and potentially promotes hepatocarcinoma cell growth

In this article,we comment on the article by Huang et al.The urgent development of new therapeutic strategies targeting macrophage polarization is critical in the fight against liver cancer.Tumor-associated macrophages(TAMs),primarily of the M2 subtype,are instrumental in cellular communication within the tumor microenvironment and are influenced by various signaling pathways,including the wingless/integrated(Wnt)pathway.Activation of the Wnt signaling pathway is pivotal in promoting M2 TAMs polarization,which in turn can exacerbate hepatocarcinoma cell proliferation and migration.This manuscript emphasizes the burgeoning significance of the Wnt signaling pathway and M2 TAMs polarization in the pathogenesis and progression of liver cancer,highlighting the potential therapeutic benefits of inhibiting the Wnt pathway.Lastly,we point out areas in Huang et al’s study that require further research,providing guidance and new directions for similar studies.

Vaginal clear cell adenocarcinoma in Herlyn-Werner-Wunderlich syndrome:A case report

BACKGROUND Herlyn-Werner-Wunderlich(HWW)syndrome is a rare Müllerian duct anomaly,characterized by a combination of urogenital abnormalities.The occurrence of primary cervico-vaginal carcinomas in patients with HWW syndrome is excep-tionally rare,posing significant challenges for screening,early diagnosis,and effective management.CASE SUMMARY We report a rare case of primary clear cell carcinoma of the vagina complicated in a 40-year-old woman with HWW syndrome.The patient presented with irregular vaginal bleeding for 4 years.On gynecological examination,an oblique vaginal septum was suspected.Surgical resection of the vaginal septum revealed a com-municating fistula and a tumor on the left vagina and the left side of the septum,which was confirmed as clear cell carcinoma.One month later,she underwent a radical hysterectomy,vaginectomy,bilateral salpingo-oophorectomy,and pelvic lymph node dissection.Due to significant side effects,she completed only one course of chemotherapy.A year later,lung metastasis was detected and continued to grow.A thoracoscopic wedge resection of the right upper lobe was performed 4 years after the initial surgery.We also conducted a systemic review of the lite-rature on primary cervical or vaginal carcinoma in HWW syndrome to explore this rare entity.CONCLUSION Cervico-vaginal adenocarcinomas in patients with HWW syndrome are occult,and require early surgical intervention and regular imaging surveillance.

Postnatal development of rat retina:a continuous observation and comparison between the organotypic retinal explant model and in vivo development

The organotypic retinal explant culture has been established for more than a decade and offers a range of unique advantages compared with in vivo experiments and cell cultures.However,the lack of systematic and continuous comparison between in vivo retinal development and the organotypic retinal explant culture makes this model controversial in postnatal retinal development studies.Thus,we aimed to verify the feasibility of using this model for postnatal retinal development studies by comparing it with the in vivo retina.In this study,we showed that postnatal retinal explants undergo normal development,and exhibit a consistent structure and timeline with retinas in vivo.Initially,we used SOX2 and PAX6 immunostaining to identify retinal progenitor cells.We then examined cell proliferation and migration by immunostaining with Ki-67 and doublecortin,respectively.Ki-67-and doublecortin-positive cells decreased in both in vivo and explants during postnatal retinogenesis,and exhibited a high degree of similarity in abundance and distribution between groups.Additionally,we used Ceh-10 homeodomain-containing homolog,glutamate-ammonia ligase(glutamine synthetase),neuronal nuclei,and ionized calcium-binding adapter molecule 1 immunostaining to examine the emergence of bipolar cells,Müller glia,mature neurons,and microglia,respectively.The timing and spatial patterns of the emergence of these cell types were remarkably consistent between in vivo and explant retinas.Our study showed that the organotypic retinal explant culture model had a high degree of consistency with the progression of in vivo early postnatal retina development.The findings confirm the accuracy and credibility of this model and support its use for long-term,systematic,and continuous observation.

Investigating Müller glia reprogramming in mice: a retrospective of the last decade, and a look to the future

Müller glia,as prominent glial cells within the retina,plays a significant role in maintaining retinal homeostasis in both healthy and diseased states.In lower vertebrates like zebrafish,these cells assume responsibility for spontaneous retinal regeneration,wherein endogenous Müller glia undergo proliferation,transform into Müller glia-derived progenitor cells,and subsequently regenerate the entire retina with restored functionality.Conversely,Müller glia in the mouse and human retina exhibit limited neural reprogramming.Müller glia reprogramming is thus a promising strategy for treating neurodegenerative ocular disorders.Müller glia reprogramming in mice has been accomplished with remarkable success,through various technologies.Advancements in molecular,genetic,epigenetic,morphological,and physiological evaluations have made it easier to document and investigate the Müller glia programming process in mice.Nevertheless,there remain issues that hinder improving reprogramming efficiency and maturity.Thus,understanding the reprogramming mechanism is crucial toward exploring factors that will improve Müller glia reprogramming efficiency,and for developing novel Müller glia reprogramming strategies.This review describes recent progress in relatively successful Müller glia reprogramming strategies.It also provides a basis for developing new Müller glia reprogramming strategies in mice,including epigenetic remodeling,metabolic modulation,immune regulation,chemical small-molecules regulation,extracellular matrix remodeling,and cell-cell fusion,to achieve Müller glia reprogramming in mice.

基于METTL3介导的miR-29a-3p的m^(6)A修饰探讨平喘颗粒抑制气道上皮细胞泛凋亡治疗哮喘的机制研究

目的:观察平喘颗粒对METTL3介导的气道上皮细胞中miR-29a-3p的m^(6)A修饰的影响,明确其抑制哮喘气道炎症的分子机制。方法:16HBE采用LPS诱导(50 mg/L)构建细胞模型,并给予平喘颗粒含药血清和地塞米松进行干预。分别采用CCK8法检测细胞活性、ELISA法检测炎症因子(TNF-α、IL-6和IL-8)的含量和miR-29a-3p的m^(6)A修饰水平、Western blot检测METTL3与泛凋亡蛋白的表达和qRT-PCR检测METTL3与miR-29a-3p的表达。结果:与模型组相比,平喘颗粒能够显著增加16HBE的活力,抑制炎症因子TNF-α、IL-6和IL-8的含量,下调泛凋亡相关蛋白p-RIPK3、p-MLKL、cleaved Caspase-1、cleaved Caspase-3的表达和GSDMD-NT/FL-GSDMD与GSDME-NT/FL-GSDME的比值,差异均具有统计学意义(P<0.01)。此外,平喘颗粒能够显著上调细胞中miR-29a-3p和METTL3的表达水平,促进miR-29a-3p的m^(6)A修饰水平,与模型组相比差异均具有统计学意义(P<0.01)。结论:平喘颗粒主要通过METTL3增强miR-29a-3p的m^(6)A修饰水平,抑制气道上皮细胞泛凋亡,改善气道炎症。

Intrinsic apoptotic pathway and G2/M cell cycle arrest involved in tubeimoside I-induced EC109 cell death

Objective： Squamous esophageal carcinoma is highly prevalent in developing countries, especially in China. Tu Bei Mu （TBM）, a traditional folk medicine, has been used to treat esophageal squamous cell carcinoma （ESCC） for a long term. tubeimoside I （TBMS1） is the main component of TBM, exhibiting great anticancer potential. In this study, we investigated the mechanism of TBMS1 cytotoxic effect on EC109 cells. Methods： Comparative nuclear proteomic approach was applied in the current study and we identified several altered protein spots. Further biochemical studies were carried out to detect the mitochondrial membrane potential, cell cycle and corresponding proteins＇ expression and location. Results： Subcellular proteomic study in the nucleus from EC109 cells revealed that altered proteins were associated with mitochondrial function and cell proliferation. Further biochemical studies showed that TBMSl-induced molecular events were related to mitochondria-induced intrinsic apoptosis and P21-cyclin B 1/cdc2 complex-related G2/M cell cycle arrest. Conclusions： Considering the conventional application of TBM in esophageal cancer, TBMS1 therefore may have a great potential as a chemotherapeutic drug candidate for ESCC.

Cadmium Activates Reactive Oxygen Species-dependent AKT/mT OR and Mitochondrial Apoptotic Pathways in Neuronal Cells

Objective To examine the role of Cd-induced reactive oxygen species（ROS） generation in the apoptosis of neuronal cells. Methods Neuronal cells（primary rat cerebral cortical neurons and PC12 cells） were incubated with or without Cd post-pretreatment with rapamycin（Rap） or N-acetyl-L-cysteine（NAC）. Cell viability was determined by MTT assay, apoptosis was examined using flow cytometry and fluorescence microscopy, and the activation of phosphoinositide 3’-kinase/protein kinase B（Akt）/mammalian target of rapamycin（m TOR） and mitochondrial apoptotic pathways were measured by western blotting or immunofluorescence assays. Results Cd-induced activation of Akt/m TOR signaling, including Akt, m TOR, p70 S6 kinase（p70 S6K）, and eukaryotic initiation factor 4E binding protein 1（4E-BP1）. Rap, an m TOR inhibitor and NAC, a ROS scavenger, blocked Cd-induced activation of Akt/m TOR signaling and apoptosis of neuronal cells. Furthermore, NAC blocked the decrease of B-cell lymphoma 2/Bcl-2 associated X protein（Bcl-2/Bax） ratio, release of cytochrome c, cleavage of caspase-3 and poly（ADP-ribose） polymerase（PARP）, and nuclear translocation of apoptosis-inducing factor（AIF） and endonuclease G（Endo G）. Conclusion Cd-induced ROS generation activates Akt/m TOR and mitochondrial pathways, leading to apoptosis of neuronal cells. Our findings suggest that m TOR inhibitors or antioxidants have potential for preventing Cd-induced neurodegenerative diseases.

Clinical applications of squamous cell carcinoma antigenimmunoglobulins M to monitor chronic hepatitis C

Hepatitis C virus(HCV) is the main cause of chronic liver disease and cirrhosis in Western countries. Over time, the majority of cirrhotic patients develop hepatocellular carcinoma(HCC), one of the most common fatal cancers worldwide- fourth for incidence rate. A high public health priority need is the development of biomarkers to screen for liver disease progression and for early diagnosis of HCC development, particularly in the high risk population represented by HCV-positive patients with cirrhosis. Several studies have shown that serological determination of a novel biomarker, squamous cell carcinoma antigen-immunoglobulins M(SCCA-Ig M), might be useful to identify patients with progressive liver disease. In the initial part of this review we summarize the main clinical studies that have investigated this new circulating biomarker on HCV-infected patients, providing evidence that in chronic hepatitis C SCCA-Ig M may be used to monitor progression of liver disease, and also to assess the virological response to antiviral treatment. In the last part of this review we address other, not less important, clinical applications of this biomarker in hepatology.

Overexpressing NeuroD1 reprograms Müller cells into various types of retinal neurons

The onset of retinal degenerative disease is often associated with neuronal loss. Therefore, how to regenerate new neurons to restore vision is an important issue. NeuroD1 is a neural transcription factor with the ability to reprogram brain astrocytes into neurons in vivo. Here, we demonstrate that in adult mice, NeuroD1 can reprogram Müller cells, the principal glial cell type in the retina, to become retinal neurons. Most strikingly, ectopic expression of NeuroD1 using two different viral vectors converted Müller cells into different cell types. Specifically, AAV7 m8 GFAP681::GFP-ND1 converted Müller cells into inner retinal neurons, including amacrine cells and ganglion cells. In contrast, AAV9 GFAP104::ND1-GFP converted Müller cells into outer retinal neurons such as photoreceptors and horizontal cells, with higher conversion efficiency. Furthermore, we demonstrate that Müller cell conversion induced by AAV9 GFAP104::ND1-GFP displayed clear dose-and time-dependence. These results indicate that Müller cells in adult mice are highly plastic and can be reprogrammed into various subtypes of retinal neurons.

Intestinal M cells:The fallible sentinels?

The gastrointestinal tract represents the largest mucosal membrane surface in the human body. The immune system in the gut is the first line of host defense against mucosal microbial pathogens and it plays a crucial role in maintaining mucosal homeostasis. Membranous or microfold cells, commonly referred to as microfold cells, are specialized epithelial cells of the gut-associated lymphoid tissues (GALT) and they play a sentinel role for the intestinal immune system by delivering luminal antigens through the follicle-associated epithelium to the underlying immune cells. M cells sample and uptake antigens at their apical membrane, encase them in vesicles to transport them to the basolateral membrane of M cells, and from there deliver antigens to the nearby lymphocytes. On the flip side, some intestinal pathogens exploit M cells as their portal of entry to invade the host and cause infections. In this article, we briefly review our current knowledge on the morphology, development, and function of M cells, with an emphasis on their dual role in the pathogenesis of gut infection and in the development of host mucosal immunity.

Modulation of TGFβ_2 and dopamine by PKC in retinal Müller cells of guinea pig myopic eye

AIM: To investigate the effect of protein kinase C (PKC) on transforming growth factor-β2 (TGFβ2) and dopamine in retinal Müller cells of guinea pig myopic eye. METHODS: Myopia was induced by translucent goggles in guinea pig, whose retinal Müller cells were cultured using the enzyme-digesting method. Retinal Müller cells were divided into 5 groups: normal control, myopia, myopia plus GF109203X, myopia plus PMA, myopia plus DMSO. PKC activities were detected by the non-radioactive methods. TGFβ2 and tyrosine hydroxylase (TH) proteins were analyzed by Western Blotting in retinal Müller cells. Dopamine was determined by the high-performance liquid chromatography- electrochemical detection in suspensions. RESULTS: After 14 days deprived, the occluded eyes became myopic with ocular axle elongating. Müller cells of guinea pigs were obtained using enzyme digestion. Compared with normal control group, the increase in PKC activity and the up-regulation in TGFβ2 expression were found in retinal Müller cells of myopic eyes, with the decrease of TH and dopamine content (P <0.05). After PKC activated by PMA, TGFβ2 and TH content were up-regulated with the increase of dopamine content (P <0.05). While the PKC activities was inhibited by GF109203X, proteins of TGFβ2 and TH were down-regulated in the myopic eyes, with the decrease of dopamine content (P <0.05). CONCLUSION: TGFβ2 and dopamine are modulated by PKC in Müller cells of the myopic eyes in guinea pig.

Protective effects of curcumin on retinal Müller cell in early diabetic rats

·AIM: To explore the effects and potential mechanisms of curcumin on retinal Müller cell in early diabetic rats. ·METHODS: Diabetic rats were induced by a single intraperitoneal injection of streptozotocin (STZ). Male Sprague-Dawley (SD) rats were randomly assigned into 4 groups: control group (nave SD rats administered with a single intraperitoneal injection of citric buffer), diabetic group (STZ -diabetic rats), dimethyl sulfoxide (DMSO) group (diabetic rats intraperitoneally administered with mixture of DMSO and normal saline, once a day) and curcumin group (diabetic rats intraperitoneally administered with curcumin, 80mg/kg, once a day). Three months after diabetes onset, malondialdehyde (MDA, indication of oxidative stress level) and reduced glutathione (GSH) in retina were detected with kits, glial fibrillary acidic protein (GFAP) in retina was revealed by immunohistochemistry and Western blot, and retinal glutamine synthetase (GS) were observed by Western blot. ·RESULTS: Compared with control group, retinal MDA was increased, and GSH was decreased in diabetic and DMSO groups ( 【0.05, respectively). While, retinal MDA and GSH in curcumin group showed no difference compared with control group ( 】0.05). Furthermore, upregulation of retinal GFAP and down-regulation of retinal GS were detected in diabetic and DMSO groups, and no alteration could be observed in curcumin group revealed with Western blot. Compared with control group, retinal Müller cells showed significant increase in GFAP immunochemistry staining in diabetic and DMSO groups. Moreover, GFAP -positive staining was decreased in curcumin group compared with diabetic group. · CONCLUSION: Curcumin inhibits diabetic retinal oxidative stress, protects Müller cell, and prevents the down -regulation of GS in diabetic retina. Therefore, curcumin has a therapeutic potential in the treatment of diabetic retinopathy (DR).

Targeting lentiviral vectors to primordial germ cells(PGCs):An efficient strategy for generating transgenic chickens

Recent advances in avian transgenic studies highlight the possibility of utilizing lentiviral vectors as tools to generate transgenic chickens. However, low rates of gonadal chimerism and germ line transmission efficiency still limit the broad usage of this method in creating transgenic chickens. In this study, we implemented a simple strategy using modified lentiviral vectors targeted to chicken primordial germ cells(PGCs) to generate transgenic chickens. The lentiviral vectors were pseudotyped with a modified Sindbis virus envelope protein(termed M168) and conjugated with an antibody specific to PGC membrane proteins. We demonstrated that these optimized M168-pseudotyped lentiviral vectors conjugated with SSEA4 antibodies successfully targeted transduction of PGCs in vitro and in vivo. Compared with the control, 50.0%–66.7% of chicken embryos expressed green fluorescent protein(GFP) in gonads transduced by the M168-pseudotyped lentivirus. This improved the targeted transduction efficiency by 30.0%–46.7%. Efficient chimerism of exogenous genes was also observed. This targeting technology could improve the efficiency of germ line transmission and provide greater opportunities for transgenic poultry studies.

Pirfenidone suppresses the abnormal activation of human Müller cells after platelet-derived growth factor-BB stimulation

AIM: To determine the effect of pirfenidone on the activated human Müller cells by platelet-derived growth factor-BB(PDGF-BB). METHODS: The primary human Müller cells were separated from retinal tissues and established the pathogenic model by stimulated with PDGF-BB. The Müller cells behaviour of normal group and the model group was measured by MTT assay, Trypan blue assay, cell migration assay, and collagen contraction assay. The expression of transforming growth factor(TGF)-β1,-β2, and pigment epithelium-derived factor(PEDF) was estimated with realtime polymerase chain reaction(PCR), Western blot and immunofluorescence analyses. RESULTS: A pathogenic/proliferative model of Müller cells was established by stimulating normal cultured Müller cells with 10 ng/mL PDGF-BB for 48 h. After treated with 0.2 and 0.3 mg/mL pirfenidone, the proliferation, migration and collagen contraction was statistically significantly depressed in the model group compared with the normal groups. The expression levels of TGF-β1 and TGF-β2 were significantly down-regulated, while the PEDF expression was significantly up-regulated after treated with 0.2 and 0.3 mg/mL pirfenidone in the model group. CONCLUSION: Pirfenidone effectively suppress the proliferation, migration and collagen contraction of the human Müller cells stimulated with PDGF-BB through down-regulation of TGF-β1/TGF-β2 and up-regulation of PEDF.

Enrichment of retinal ganglion and Müller glia progenitors from retinal organoids derived from human induced pluripotent stem cells-possibilities and current limitations

BACKGROUND Retinal organoids serve as excellent human-specific disease models for conditions affecting otherwise inaccessible retinal tissue from patients.They permit the isolation of key cell types affected in various eye diseases including retinal ganglion cells(RGCs)and Müller glia.AIM To refine human-induced pluripotent stem cells(hiPSCs)differentiated into threedimensional(3D)retinal organoids to generate sufficient numbers of RGCs and Müller glia progenitors for downstream analyses.METHODS In this study we described,evaluated,and refined methods with which to generate Müller glia and RGC progenitors,isolated them via magnetic-activated cell sorting,and assessed their lineage stability after prolonged 2D culture.Putative progenitor populations were characterized via quantitative PCR and immunocytochemistry,and the ultrastructural composition of retinal organoid cells was investigated.RESULTS Our study confirms the feasibility of generating marker-characterized Müller glia and RGC progenitors within retinal organoids.Such retinal organoids can be dissociated and the Müller glia and RGC progenitor-like cells isolated via magnetic-activated cell sorting and propagated as monolayers.CONCLUSION Enrichment of Müller glia and RGC progenitors from retinal organoids is a feasible method with which to study cell type-specific disease phenotypes and to potentially generate specific retinal populations for cell replacement therapies.

Macrophage colony-stimulating factor expressed in non-cancer tissues provides predictive powers for recurrence in hepatocellular carcinoma

AIM To investigate the role of macrophage colony-stimulating factor(M-CSF) in patients with hepatocellular carcinoma(HCC) after surgery. METHODS Expression of M-CSF, distribution of M2 macrophages(Mφs), and angiogenesis were assessed in the liver, including tumors and peritumoral liver tissues. The prognostic power of these factors was assessed. Mouse isolated hepatic Mφs or monocytes were cultured with media containing M-CSF. The concentration of vascular endothelial growth factor(VEGF) in media was assessed. Furthermore, the role of the M-CSF-matured hepatic Mφs on proliferation of the vascular endothelial cell(VEC) was investigated. RESULTS A strong correlation between the expressions of M-CSF and CD163 was observed in the peritumoral area. Also, groups with high density of M-CSF, CD163 or CD31 showed a significantly shorter time to recurrence(TTR) than low density groups. Multivariate analysis revealedthe expression of M-CSF or hepatic M2Mφs in the peritumoral area as the most crucial factor responsible for shorter TTR. Moreover, the expression of M-CSF and hepatic M2Mφs in the peritumoral area had better predictable power of overall survival. Values of VEGF in culture media were significantly greater in the hepatic Mφs compared with the monocytes. Proliferation of the VEC was greatest in the cells co-cultured with hepatic Mφs when M-CSF was present in media.CONCLUSION M-CSF increases hepatocarcinogenesis, most likely by enhancing an angiogenic factor derived from hepatic Mφ and could be a useful target for therapy against HCC.

Rice sl-MH-1 mutant induces cell death and confers blast resistance via the synergistic roles of signaling systems

Serotonin is ubiquitous across all forms of life and functions in responses to biotic and abiotic stresses.In rice,the conversion of tryptamine to serotonin is catalyzed by Sekiguchi lesion(SL).Previous studies have identified an sl mutation(a null mutation of SL)in several rice varieties and confirmed its increase of resistance and cell death.However,a systematic understanding of the reprogrammed cellular processes causing cell death and resistance is lacking.We performed a multi-omics analysis to clarify the fundamental mechanisms at the protein,gene transcript,and metabolite levels.We found that cell death and Magnaporthe oryzae(M.oryzae)infection of the sl-MH-1 mutant activated plant hormone signal transduction involving salicylic acid(SA),jasmonic acid(JA),and abscisic acid(ABA)in multiple regulatory layers.We characterized the dynamic changes of several key hormone levels during disease progression and under the cell death conditions and showed that SA and JA positively regulated rice cell death and disease resistance.SL-overexpressing lines confirmed that the sl-MH-1 mutant positively regulated rice resistance to M.oryzae.Our studies shed light on cell death and facilitate further mechanistic dissection of programmed cell death in rice.

Role of endoplasmic reticulum stress in the loss of retinal ganglion cells in diabetic retinopathy

Endoplasmic reticulum stress is closely involved in the early stage of diabetic retinopathy. In the present study, a streptozotocin-induced diabetic animal model was given an intraperitoneal injection of tauroursodeoxycholic acid. Results from immunofluorescent co-localization experiments showed that both caspase-12 protein and c-Jun N-terminal kinase 1 phosphorylation levels significantly in- creased, which was associated with retinal ganglion cell death in diabetic retinas. The C/ERB ho- mologous protein pathway directly contributed to glial reactivity, and was subsequently responsible for neuronal loss and vascular abnormalities in diabetic retinopathy. Our experimental findings in- dicate that endoplasmic reticulum stress plays an important role in diabetes-induced retinal neu- ronal loss and vascular abnormalities, and that inhibiting the activation of the endoplasmic reticulum stress pathway provides effective protection against diabetic retinopathy.

Overexpression of the M2 isoform of pyruvate kinase is an adverse prognostic factor for signet ring cell gastric cancer

AIM:To investigate M2 isoform of pyruvate kinase(PKM2) expression in gastric cancers and evaluate its potential as a prognostic biomarker and an anticancer target.METHODS:All tissue samples were derived from gastric cancer patients underwent curative gastrectomy as a primary treatment.Clinical and pathological information were obtained from the medical records.Gene expression microarray data from 60 cancer and 19 noncancer gastric tissues were analyzed to evaluate the expression level of PKM2 mRNA.Tissue microarrays were constructed from 368 gastric cancer patients.Immunohistochemistry was used to measure PKM2 expression and PKM2 positivity of cancer was determined by proportion of PKM2-positive tumor cells and staining intensity.Association between PKM2 expression and the clinicopathological factors was evaluated and the correlation between PKM2 and cancer prognosis was evaluated.RESULTS:PKM2 mRNA levels were increased more than 2-fold in primary gastric cancers compared to adjacent normal tissues from the same patients(log transformed expression level:7.6 ± 0.65 vs 6.3 ± 0.51,P < 0.001).Moreover,differentiated type cancers had significantly higher PKM2 mRNA compared to undifferentiated type cancers(log transformed expression level:7.8 ± 0.70 vs 6.7 ± 0.71,P < 0.001).PKM2 protein was mainly localized in the cytoplasm of primary cancer cells and detected in 144 of 368(39.1%) human gastric cancer cases.PKM2 expression was not related with stage(P = 0.811),but strongly correlated with gastric cancer differentiation(P < 0.001).Differentiated type cancers expressed more PKM2 protein than did the undifferentiated ones.Well differentiated adenocarcinoma showed 63.6% PKM2-positive cells;in contrast,signet-ring cell cancers showed only 17.7% PKM2-positive cells.Importantly,PKM2 expression was correlated with shorter overall survival(P < 0.05) independent of stage only in signet-ring cell cancers.CONCLUSION:PKM2 expression might be an adverse prognostic factor for signet-ring cell carcinomas.Its function and potential as a prognostic marker should be further verified in gastric cancer.