Clinical Characteristics and Prognosis of Cervical Cancer Patients with Human Immunodeficiency Virus Infection: A Retrospective Study.

OBJECTIVES: Cervical cancer (CC) is one of the human immunodeficiency virus (HIV)-related cancers. The objective of this retrospective observational cohort study was to explore the treatment response, survival, and independent prognostic predictors for HIV-positive patients with CC. Design/Participants/Materials/Setting/Methods: This is a retrospective case-control study. Patients with primary CC, treated at Xiangyang Central Hospital, Hubei, China, from June 2013 to June 2019, were reviewed. All included patients were divided into the HIV-positive and HIV-negative groups. The primary outcome was overall survival (OS). A Kaplan-Meier curve was used to evaluate the survival condition. Univariate and multivariate Cox proportional hazard regression was used to determine the prognostic predictors for HIV-positive CC patients. RESULTS: A total of 1,319 patients were included in the study, with 30 in the HIV-positive group and 1,289 in the HIV-negative group. The HIV-negative group had statistically better OS than the HIV-positive group (hazard ratio [HR] 2.68, 95% confidence interval [CI]: 1.78-4.04, p < 0.001). The recurrence rate of HIV-negative was lower than that of HIV-positive patients (p < 0.001). Concurrent radiotherapy and chemotherapy seemed to be less effective for HIV-positive patients than for HIV-negative patients among nonsurgical treatment patients (p = 0.046). The independent predictors for HIV-negative patients were recurrence (HR 3.08, 95% CI: 1.17-8.13, p = 0.023) and CD4 count ≥410/µL (HR 1.84, 95% CI: 1.07-3.19, p = 0.040). LIMITATIONS: First, some potential confounding factors, such as HIV-related co-infections, cannot be avoided, which may decrease the power of our findings. Second, as the sample size of HIV-positive CC patients was relatively small, the baseline characteristics of the two groups were not balanced, which can cause bias in the results to some degree. Finally, some useful data for the analyses were missing for some cases in the present study, which is inevitable for a retrospective study. CONCLUSION: There is a significantly lower survival and higher recurrence rate in CC patients with HIV infection, compared with those without HIV infection. Furthermore, inoperable HIV-positive CC patients are less likely to benefit from concurrent radiotherapy and chemotherapy than HIV-negative patients. Recurrence and blood CD4 count are independent prognostic factors for HIV-positive CC patients.

Engineered exosomes for targeted co-delivery of miR-21 inhibitor and chemotherapeutics to reverse drug resistance in colon cancer.

BACKGROUND: 5-Fluorouracil (5-FU) has been commonly prescribed for patients with colorectal cancer (CRC), but resistance to 5-FU is one of the main reasons for failure in CRC. Recently, microRNAs (miRNAs) have been established as a means of reversing the dilemma by regulating signaling pathways involved in initiation and progression of CRC. However, how to safely and effectively deliver miRNA to target cells becomes a main challenge. RESULTS: In this study, Engineered exosomes were exploited to simultaneously deliver an anticancer drug 5-FU and miR-21 inhibitor oligonucleotide (miR-21i) to Her2 expressing cancer cells. Purified engineered exosomes from the donor cells loaded with 5-FU and miR-21i via electroporation to introduce into 5-FU-resistant colorectal cancer cell line HCT-1165FR. Furthermore, systematic administration of 5-FU and miR-21i loaded exosomes in tumor bearing mice indicated a significantly anti-tumor effect. The results showed that the engineered exosome-based 5-FU and miR-21i co-delivery system could efficiently facilitate cellular uptake and significantly down-regulate miR-21 expression in 5-FU resistant HCT-1165FR cell lines. Consequently, the down-regulation of miR-21 induced cell cycle arrest, reduced tumor proliferation, increased apoptosis and rescued PTEN and hMSH2 expressions, regulatory targets of miR-21. Of particular importance was the significant reduction in tumor growth in a mouse model of colon cancer with systematic administration of the targeting miR-21i. More excitedly, the combinational delivery of miR-21i and 5-FU with the engineered exosomes effectively reverse drug resistance and significantly enhanced the cytotoxicity in 5-FU-resistant colon cancer cells, compared with the single treatment with either miR-21i or 5-FU. CONCLUSION: The strategy for co-delivering the functional small RNA and anticancer drug by exosomes foreshadows a potential approach to reverse the drug resistance in CRC and thus to enhance the efficacy of the cancer treatment.

Exosomes Transfer Among Different Species Cells and Mediating miRNAs Delivery.

Exosomes, the natural vehicles of intercellular communication, transfer proteins, mRNAs, and microRNAs (miRNAs) and mediate many physiological and pathological processes. It is not clear that whether exosomal miRNAs could regulate gene expression across species, though some studies suggest interactions of exosomal miRNAs between cells. In this report, we have isolated exosomes from rat PC12 cells and assessed their internalization by human cancer Hela cells. The internalized exosomes were located in Hela lysosomes. Human PTEN expression was significantly deregulated due to miR-21 delivered by rat cell exosomes. Our results prove that exosomes could incorporate between cells of different species and could regulate the protein expressions in the recipient cells by delivering the enclosed miRNAs. Thus our study foreshadows a futuristic treatment approach of utilizing miRNA enclosed exosome vehicles sans species concerns in combating various diseases/ regulating abnormal proteins. J. Cell. Biochem. 118: 4267-4274, 2017. © 2017 Wiley Periodicals, Inc.

Exosome uptake through clathrin-mediated endocytosis and macropinocytosis and mediating miR-21 delivery.

Exosomes are nanoscale membrane vesicles secreted from many types of cells. Carrying functional molecules, exosomes transfer information between cells and mediate many physiological and pathological processes. In this report, utilizing selective inhibitors, molecular tools, and specific endocytosis markers, the cellular uptake of PC12 cell-derived exosomes was imaged by high-throughput microscopy and statistically analyzed. It was found that the uptake was through clathrin-mediated endocytosis and macropinocytosis. Furthermore, PC12 cell-derived exosomes can enter and deliver microRNAs (miRNAs) into bone marrow-derived mesenchymal stromal cells (BMSCs), and decrease the expression level of transforming growth factor ß receptor II (TGFßRII) and tropomyosin-1 (TPM1) through miR-21. These results show the pathway of exosome internalization and demonstrate that tumor cell-derived exosomes regulate target gene expression in normal cells.

Highly sensitive graphene-Pt nanocomposites amperometric biosensor and its application in living cell H2O2 detection.

A sensitive hydrogen peroxide (H2O2) sensor was constructed based on graphene-Pt (RGO-Pt) nanocomposites and used to measure the release of H2O2 from living cells. The graphene and Pt nanoparticles (Pt NPs) were modified on glassy carbon electrode (GCE) by the physical adsorption and electrodeposition of K2PtCl6 solution, respectively. Through characterization by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), it was observed that the electrodeposited Pt NPs were densely covered and well distributed on the entire graphene surface. Electrochemical study demonstrates that the RGO-Pt nanocomposites modified glassy carbon electrode exhibited a high peak current and low overpotential toward the reduction of H2O2. The relevant detection limit of H2O2 is ∼0.2 µM with a wide linear range from 0.5 µM to 3.475 mM, displaying a much higher sensitivity (459 ± 3 mA M(-1) cm(-2), n = 5) than that of Pt nanoparticles or graphene modified electrode. This novel biosensor can measure the H2O2 release from living cells because of its low detection limit, wide linear range, and higher sensitivity.

Dynamics of exosome internalization and trafficking.

Cells release exosomes into extracellular medium. Although the important roles of exosomes in many physiological and pathological processes are being revealed, the mechanism of exosome-cell interaction remains unclear. In this article, employing real-time fluorescence microscopy, the motion of exosomes on the plasma membrane or in the cytoplasm of recipient PC12 cells was observed directly. In addition, several motion modes of exosomes were revealed by single particle tracking (SPT). The changes between motion modes were also detected, presenting the dynamic courses of exosome attachment onto plasma membrane and exosome uptake. Octadecyl rhodamine B chloride (R18) was found to be useful to distinguish endocytosis from fusion during exosome uptake. Colocalization with organelle markers showed exosomes were sorted to acidic vesicles after internalization. The results provide new sight into the exosome-cell interaction mode and the intercellular trafficking of exosomes. This study will help to understand the roles of exosomes at cell level.

Decoupling economic development from municipal solid waste generation in China's cities: Assessment and prediction based on Tapio method and EKC models.

This study uses the Tapio elastic decoupling analysis method and an empirical model of the environmental Kuznets curve (EKC) to analyze the decoupling between municipal solid waste (MSW) generation and economic development in 285 of China's cities from 2002 to 2017. The decoupling analysis results show that the decoupling states in China's cities generally improved first and then deteriorated in 2002-2017. The proportion of cities experiencing deterioration of decoupling states had increased to 60.00% by 2014-2017, and cities with a higher economic development level generally had more serious deterioration. The empirical test results support the N-shaped EKC hypothesis of MSW, which can explain why the decoupling state changed from improvement to deterioration. The difference of the economic level of sample cities (which determines their position on EKC) can also explain the spatial heterogeneity of the decoupling state and its changes; for example, the proportion of cities that have crossed the inflection point of Tapio decoupling elasticity (the per capita GDP is 13,130.89 yuan) to enter the deterioration stage is highest (100/101) in the economically developed eastern region, and is lowest (66/75) in the economically backward western region of China. In general, the empirical results of EKC can effectively support and explain the results of decoupling analysis.

A Pan-Histone Deacetylase Inhibitor Enhances the Antitumor Activity of B7-H3-Specific CAR T Cells in Solid Tumors.

PURPOSE: The limited efficacy of chimeric antigen receptor (CAR) T-cell therapies with solid malignancies prompted us to test whether epigenetic therapy could enhance the antitumor activity of B7-H3.CAR T cells with several solid cancer types. EXPERIMENTAL DESIGN: We evaluated B7-H3 expression in many human solid cancer and normal tissue samples. The efficacy of the combinatorial therapy with B7-H3.CAR T cells and the deacetylase inhibitor SAHA with several solid cancer types and the potential underlying mechanisms were characterized with in vitro and ex vivo experiments. RESULTS: B7-H3 is expressed in most of the human solid tumor samples tested, but exhibits a restricted expression in normal tissues. B7-H3.CAR T cells selectively killed B7-H3 expressing human cancer cell lines in vitro. A low dose of SAHA upregulated B7-H3 expression in several types of solid cancer cells at the transcriptional level and B7-H3.CAR expression on human transgenic T-cell membrane. In contrast, the expression of immunosuppressive molecules, such as CTLA-4 and TET2, by T cells was downregulated upon SAHA treatment. A low dose of SAHA significantly enhanced the antitumor activity of B7-H3.CAR T cells with solid cancers in vitro and ex vivo, including orthotopic patient-derived xenograft and metastatic models treated with autologous CAR T-cell infusions. CONCLUSIONS: Our results show that our novel strategy which combines SAHA and B7-H3.CAR T cells enhances their therapeutic efficacy with solid cancers and justify its translation to a clinical setting.

Engineering of HN3 increases the tumor targeting specificity of exosomes and upgrade the anti-tumor effect of sorafenib on HuH-7 cells.

Safe, efficient and cancer cell targeted delivery of CRISPR/Cas9 is important to increase the effectiveness of available cancer treatments. Although cancer derived exosomes offer significant advantages, the fact that it carries cancer related/inducing signaling molecules impedes them from being used as a reliable drug delivery vehicle. In this study, we report that normal epithelial cell-derived exosomes engineered to have HN3 (HN3LC9-293exo), target tumor cells as efficiently as that of the cancer cell-derived exosomes (C9HuH-7exo). HN3LC9-293exo were quickly absorbed by the recipient cancer cell in vitro. Anchoring HN3 to the membrane of the exosomes using LAMP2, made HN3LC9-293exo to specifically enter the GPC3+ HuH-7 cancer cells than the GPC3- LO2 cells in a co-culture model. Further, sgIQ 1.1 plasmids were loaded to exosomes and surprisingly, in combination with sorafenib, synergistic anti-proliferative and apoptotic effect of loaded HN3LC9-293exo was more than the loaded C9HuH-7exo. While cancer-derived exosomes might induce the drug resistance and tumor progression, normal HEK-293 cells-derived exosomes with modifications for precise cancer cell targeting like HN3LC9-293exo can act as better, safe and natural delivery systems to improve the efficacy of the cancer treatments.

Enhanced Suppression of Disulfide Cross-Linking Micelles Nanocarriers Loaded miR-145 Delivering System via Down-Regulation of MYC and FSCN1 in Colon Cancer Cells.

Colorectal carcinoma is a complex disease accounting for adenoma tumors and an aggressive phenotype, and the third leading cause of cancer death. In the past decades, miRNAs have been associated with molecular pathways of cancer and other diseases. The dysregulated miRNAs play an inhibitory or promoting role in tumorigenesis. Therefore, restoration of tumor-suppressed microRNAs (miRNA) may offer novel therapeutic approaches for cancer treatment. Nevertheless, the poor bioavailability of miRNA due to their rapid enzymatic degradation is a critical barrier in cancer gene therapy. To overcome this dilemma, we designed disulfide cross-linking micelles (DCM) nanocarrier for delivery of miR-145 to colon cancer cells and investigated its therapeutic efficacy in vitro and in vivo. Results indicated that the presence of DCM nanocarrier loaded with miR-145 enhanced selective delivery of miR-145 and facilitated cellular uptake, significantly up-regulating miR-145 expression in HCT-116 cell lines. Consequently, the cell proliferation was inhibited by arresting cell cycle at the G1 phase. Further, apoptosis of HCT-116 cells treated with miR-145 complex nanoparticles may be via downregulation of oncogenes MYC and FSCN1, predicting regulatory targets for miR-145. These results pave the way for further investigations into the potential of miR-145 complex nanocarrier for cancer gene therapy.

miR-124 participates in the proliferation and differentiation of brain glioma stem cells through regulating Nogo/NgR expression.

The effect of miR-124 on the proliferation and differentiation of brain glioma stem cells and Nogo/NgR signaling pathway were investigated. miR-124 mimic, miR-124 inhibitor and miR-control expression vector were designed and produced to transfect U87 glioma stem cells. The results of transfection were tested via RT-qPCR and the expression of protein was detected by western blot analysis. Cell proliferation was detected by MTT proliferation and the proportion of CD133+ cells was detected by immunomagnetic beads to determine cell differentiation. The correlation between miR-124 and Nogo-A, and NgR protein expression was analyzed by Spearman correlation analysis. The relative expression of miR-124 in cells of miR-124 mimic group was significantly higher than that of miR-124 inhibitor and miR-control groups (P<0.05). The relative expression of Nogo-A and NgR protein in cells of the miR-124 mimic group was significantly lower than that of miR-124 inhibitor and miR-control groups (P<0.05). Absorbance values of the cells in the miR-124 mimic and miR-control groups were significantly lower than those in the miR-124 inhibitor group at each time point (P<0.05), while the values of the cells in the miR-124 mimic group were significantly lower than that in miR-control group (P<0.05). The level of CD133+ cells in miR-124 mimic group was significantly lower than that in miR-124 inhibitor and miR-control groups (P<0.05), while the level of CD133+ cells in miR-124 inhibitor group was higher than that in miR-control group (P<0.05). Correlation analysis revealed that there was a negative correlation between miR-124 and the expression of Nogo-A and NgR protein (P<0.05). miR-124 may participate in the differentiation of brain glioma stem cells through the Nogo/NgR pathway, which may bring a new direction for the clinical treatment of brain glioma.

Engineered exosome-mediated delivery of functionally active miR-26a and its enhanced suppression effect in HepG2 cells.

INTRODUCTION: Exosomes are closed-membrane nanovesicles that are secreted by a variety of cells and exist in most body fluids. Recent studies have demonstrated the potential of exosomes as natural vehicles that target delivery of functional small RNA and chemotherapeutics to diseased cells. METHODS: In this study, we introduce a new approach for the targeted delivery of exosomes loaded with functional miR-26a to scavenger receptor class B type 1-expressing liver cancer cells. The tumor cell-targeting function of these engineered exosomes was introduced by expressing in 293T cell hosts, the gene fusion between the transmembrane protein of CD63 and a sequence from Apo-A1. The exosomes harvested from these 293T cells were loaded with miR-26a via electroporation. RESULTS: The engineered exosomes were shown to bind selectively to HepG2 cells via the scavenger receptor class B type 1-Apo-A1 complex and then internalized by receptor-mediated endocytosis. The release of miR-26a in exosome-treated HepG2 cells upregulated miR-26a expression and decreased the rates of cell migration and proliferation. We also presented evidence that suggest cell growth was inhibited by miR-26a-mediated decreases in the amounts of key proteins that regulate the cell cycle. CONCLUSION: Our gene delivery strategy can be adapted to treat a broad spectrum of cancers by expressing proteins on the surface of miRNA-loaded exosomes that recognize specific biomarkers on the tumor cell.

Surface functionalized exosomes as targeted drug delivery vehicles for cerebral ischemia therapy.

The safe and effective delivery of drugs is a major obstacle in the treatment of ischemic stroke. Exosomes hold great promise as an endogenous drug delivery nanosystem for the treatment of cerebral ischemia given their unique properties, including low immunogenicity, innate stability, high delivery efficiency, and ability to cross the blood-brain barrier (BBB). However, exosome insufficient targeting capability limits their clinical applications. In this study, the c(RGDyK) peptide has been conjugated to the exosome surface by an easy, rapid, and bio-orthogonal chemistry. In the transient middle cerebral artery occlusion (MCAO) mice model, The engineered c(RGDyK)-conjugated exosomes (cRGD-Exo) target the lesion region of the ischemic brain after intravenous administration. Furthermore, curcumin has been loaded onto the cRGD-Exo, and administration of these exosomes has resulted in a strong suppression of the inflammatory response and cellular apoptosis in the lesion region. The results suggest a targeting delivery vehicle for ischemic brain based on exosomes and provide a strategy for the rapid and large-scale production of functionalized exosomes.

MiR-218 Induces Neuronal Differentiation of ASCs in a Temporally Sequential Manner with Fibroblast Growth Factor by Regulation of the Wnt Signaling Pathway.

Differentiation of neural lineages from mesenchymal stem cells has raised the hope of generating functional cells as seed cells for nerve tissue engineering. As important gene regulators, microRNAs (miRNAs) have been speculated to play a vital role in accelerating stem cell differentiation and repairing neuron damage. However, miRNA roles in directing differentiation of stem cells in current protocols are underexplored and the mechanisms of miRNAs as regulators of neuronal differentiation remain ambiguous. In this study, we have determined that miR-218 serves as crucial constituent regulator in neuronal differentiation of adipose stem cells (ASCs) through Wnt signaling pathway based on comprehensive annotation of miRNA sequencing data. Moreover, we have also discovered that miR-218 and Fibroblast Growth Factor-2 (FGF2) modulate neuronal differentiation in a sequential manner. These findings provide additional understanding of the mechanisms regulating stem cell neuronal differentiation as well as a new method for neural lineage differentiation of ASCs.

Colorectal cancer characterization and therapeutic target prediction based on microRNA expression profile.

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers and a major cause of cancer death. However, the molecular mechanisms underlying CRC initiation, growth and metastasis are poorly understood. In this study, based on our previous work for comprehensively analyzing miRNA sequencing data, we examined a series of colorectal cancer microRNAs expression profiles data. Results show that all these CRC samples share the same four pathways including TGF-beta signaling pathway, which is important in colorectal carcinogenesis. Twenty-one microRNAs that evolved in the four overlapped pathways were then discovered. Further analysis selected miR-21 as an important regulator for CRC through TGF-beta pathways. This study develops methods for discovering tumor specific miRNA cluster as biomarker and for screening new cancer therapy targets based on miRNA sequencing.

A novel type of self-assembled nanoparticles as targeted gene carriers: an application for plasmid DNA and antimicroRNA oligonucleotide delivery.

In this study, a new type of amphiphilic cetylated polyethyleneimine (PEI) was synthesized, and then polylactic-co-glycolic acid (PLGA)/cetylated PEI/hyaluronic acid nanoparticles (PCPH NPs) were developed by self-assembly as a novel type of gene-delivering vehicle. The PCPH NPs showed good DNA-condensation ability by forming polyplexes with small particle size and positive zeta potential. The transfection efficiency and cytotoxicity of PCPH NPs were evaluated as plasmid DNA vectors to transfect HepG2 in vitro. PCPH NPs exhibited much lower cytotoxicity and higher gene-transfection efficiency than PEI (25,000) and commercial transfection reagents. Furthermore, PCPH NPs were used as an anti-miR-221 vector for transfecting HepG2 cells, and anti-miR-221 was effectively transfected into cells and produced a greater inhibitory effect on cancer-cell growth by PCPH NPs. These results demonstrate that PCPH NPs can be a promising nonviral vector for gene-delivery systems.

Exosomes: decreased sensitivity of lung cancer A549 cells to cisplatin.

Exosomes are small extracellular membrane vesicles of endocytic origin released by many cells that could be found in most body fluids. The main functions of exosomes are cellular communication and cellular waste clean-up. This study was conducted to determine the involvement of exosomes in the regulation of sensitivity of the lung cancer cell line A549 to cisplatin (DDP). When DDP was added to A549 cells, exosomes secretion was strengthened. Addition of the secreted exosomes to other A549 cells increased the resistance of these A549 cells to DDP. Upon exposure of A549 to DDP, the expression levels of several miRNAs and mRNAs reportedly associated with DDP sensitivity changed significantly in exosomes; these changes may mediate the resistance of A549 cells to DDP. Exosomes released by A549 cells during DDP exposure decreased the sensitivity of other A549 cells to DDP, which may be mediated by miRNAs and mRNAs exchange by exosomes via cell-to-cell communication. Although the detailed mechanism of resistance remains unclear, we believed that inhibition of exosomes formation and release might present a novel strategy for lung cancer treatment in the future.

Assessing the survival of exogenous plant microRNA in mice.

MicroRNAs (miRNAs), a class of small RNAs, are important molecules that influence several developmental processes and regulate RNA interference (RNAi), and are abundant in animals, plants, and plant tissues that are traditionally consumed in the diet. The survival of plant small RNAs from the diet in animals, however, remains unclear, and the persistence of miRNAs from dietary plants in the animal gastrointestinal (GI) tract is still under debate. In this study, ICR mice were fed plant total RNAs in quantities of 10-50 µg, extracted from Brassica oleracea. Serum, feces, and various tissues were collected from the mice after RNA consumption and analyzed for several miRNAs. Exogenous plant miRNAs were present in the sera, feces, and tissues of animals and these exogenous plant miRNAs were primarily acquired orally. MiR-172, the most highly enriched exogenous plant miRNA in B. oleracea, was found in the stomach, intestine, serum, and feces of mice that were fed plant RNA extracts including miR-172. The amount of miR-172 that survived passage through the GI tract varied among individuals, with a maximum of 4.5% recovered at the stomach of one individual, and had a range of 0.05-4.5% in different organs. Furthermore, miR-172 was detected in the blood, spleen, liver, and kidney of mice.

Effects of epidermal growth factor and basic fibroblast growth factor on the proliferation and osteogenic and neural differentiation of adipose-derived stem cells.

Stem cells used for clinical tissue regeneration therapy should have the capacity of self-renewal, high proliferation, and differentiation and be able to be transplanted in large numbers. Although high concentrations of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) may induce the differentiation of stem cells, these factors have been widely used to enhance the propagation of stem cells, including adipose-derived mesenchymal stem cells (ASCs). However, the effects of low concentrations of EGF and bFGF on stem cells need to be evaluated carefully. This study illustrates that low concentrations of EGF (5 ng/mL) and bFGF (10 ng/mL) increase the proliferative ability of ASCs and induce the typical spindle-shaped cell morphology. EGF and bFGF added to medium promoted neural lineage differentiation and impaired the mesodermal differentiation ability of ASCs. This study demonstrates that even low concentrations of EGF and bFGF may limit the differentiation ability of stem cells during stem cell expansion in vitro. EGF and bFGF supplementation should be carefully considered in stem cells for clinical applications.

Layer-by-layer assembly of graphene, Au and poly(toluidine blue O) films sensor for evaluation of oxidative stress of tumor cells elicited by hydrogen peroxide.

High level of oxidative stress is involved in formation of incipient tumor and carcinomatous cells. Here in this contribution we have explored a facile strategy to assess the oxidative stress elicited by hydrogen peroxide (H(2)O(2)) in cells with amperometric current-time technique in vitro. An electrochemical biosensor exhibiting high sensitivity and selectivity to H(2)O(2) is fabricated by integration of graphene with gold nanoparticles and poly(toluidine blue O) films. The efflux of H(2)O(2) from several representative tumor cells and normal cells on exposure to ascorbic acid could be detected by using the graphene-based nanocomposite films. The results indicate that tumor cells release much more H(2)O(2) than do the normal cells. The novel sensor raises the possibility for clinical diagnostic application to evaluate the higher level of intracellular oxidative stress of tumor cells in comparison with normal cells.