An integrated and multi-functional droplet-based microfluidic platform for digital DNA amplification.

Digital DNA amplification is a powerful method for detecting and quantifying rare nucleic acids. In this study, we developed a multi-functional droplet-based platform that integrates the traditional digital DNA amplification workflow into a one-step device. This platform enables efficient droplet generation, transition, and signal detection within a 5-min timeframe, distributing the sample into a uniform array of 4 × 104 droplets (variation <2%) within a chamber. Subsequent in-situ DNA amplification, fluorescence detection, and signal analysis were carried out. To assess the platform's performance, we quantitatively detected the human epidermal growth factor receptor (EGFR) mutation and human papillomavirus (HPV) mutation using digital polymerase chain reaction (dPCR) and digital loop-mediated isothermal amplification (dLAMP), respectively. The fluorescence results exhibited a positive, linear, and statistically significant correlation with target DNA concentrations ranging from 101 to 105 copies/µL, demonstrating the capability and feasibility of the integrated device for dPCR and dLAMP. This platform offers high-throughput droplet generation, eliminates droplet fusion and transition, is user-friendly, reduces costs compared to current methods, and holds potential for thermocycling and isothermal nucleic acid quantification with high sensitivity and accuracy.

Targeted destruction of cancer stem cells using multifunctional magnetic nanoparticles that enable combined hyperthermia and chemotherapy.

Cancer stem cells (CSCs) have been implicated in cancer recurrence and therapy resistance. Therefore, a CSC-targeted therapy that disrupts the maintenance and survival of CSCs may offer an effective approach in killing tumor cells in primary tumors and preventing the metastasis caused by CSCs. Nanoparticles (NPs)-based thermotherapy and/or chemotherapy are promising therapeutic methods for cancer treatment. Methods: A silica-based multifunctional NP system was present, which encapsulated a chemotherapeutic agent and magnetic cores and coated with a specific antibody against the lung CSCs. The efficacy of this novel therapeutic strategy was systematically studied both in vitro and in vivo by simultaneous activating the combined thermotherapy and chemotherapy via CSC-targeted NPs. Results: These NPs were systematically administered and activated for targeted chemotherapy and thermotherapy by using an externally applied alternating magnetic field (AMF). The antibody-modified NPs targeted to lung CSCs with enhanced cellular uptake in vitro and extended accumulation in tumor in vivo. Up to 98% of lung CSCs was killed in vitro with 30-min application of AMF, due to the combined effects of hyperthermia and chemotherapeutic drug treatment. In in vivo models, this combined therapy significantly suppressed tumor growth and metastasis in lung CSC xenograft-bearing mice, with minimal side effects and adverse effects. Conclusion: With good biocompatibility and targeting capability, the nanodrug delivery system may offer a promising clinical platform for the combined thermotherapy and chemotherapy. This work demonstrated the feasibility of developing multifunctional nanomedicine targeting CSCs for effective cancer treatment.

Electrotaxis of tumor-initiating cells of H1975 lung adenocarcinoma cells is associated with both activation of stretch-activated cation channels (SACCs) and internal calcium release.

The metastatic potential of cancer cells is related to their migratory ability, which is influenced by in vivo microenvironment possessing specific physiochemical factors including electric properties. In the present study, we isolated two different subsets of lung adenocarcinoma H1975 cells, as side population (SP) and main population (MP). SP cells were demonstrated to have cancer stem cell characteristics. Using a microscale device to provide physiological direct-current electric field (dcEF), we investigated the electrotactic responses of the SP and MP cells. The results showed that both SP and MP cells exhibited enhanced cathodal migration ability with actin reorganization and transient intracellular calcium ions ([Ca2+]i) increase under dcEF stimulation. For SP cells, the treatment of either stretch-activated cation channels (SACCs) inhibitor or the blockage of intracellular Ca2+ release could partially inhibited dcEF-activated [Ca2+]i increase, and the concomitant treatment led to a complete inhibition. For MP cells, SACCs activation was entirely responsible for EF-activated increase of [Ca2+]i. All these results suggested that that intracellular Ca2+ activation may be associated with cancer cell tumorigenicity and metastasis.

Development of Novel Piezoelectric Biosensor Using PZT Ceramic Resonator for Detection of Cancer Markers.

A novel biosensor based on piezoelectric ceramic resonator was developed for direct detection of cancer markers in the study. For the first time, a commercially available PZT ceramic resonator with high resonance frequency was utilized as transducer for a piezoelectric biosensor. A dual ceramic resonators scheme was designed wherein two ceramic resonators were connected in parallel: one resonator was used as the sensing unit and the other as the control unit. This arrangement minimizes environmental influences including temperature fluctuation, while achieving the required frequency stability for biosensing applications. The detection of the cancer markers Prostate Specific Antigen (PSA) and α-Fetoprotein (AFP) was carried out through frequency change measurement. The device showed high sensitivity (0.25 ng/ml) and fast detection (within 30 min) with small samples (1 µl), which is compatible with the requirements of clinical measurements. The results also showed that the ceramic resonator-based piezoelectric biosensor platform could be utilized with different chemical interfaces, and had the potential to be further developed into biosensor arrays with different specificities for simultaneous detection of multiple analytes.

Chemoresistant lung cancer stem cells display high DNA repair capability to remove cisplatin-induced DNA damage.

BACKGROUND AND PURPOSE: The persistence of lung cancer stem cells (LCSCs) has been proposed to be the main factor responsible for the recurrence of lung cancer as they are highly resistant to conventional chemotherapy. However, the underlying mechanisms are still unclear. EXPERIMENTAL APPROACH: We examined the cellular response of a human LCSC line to treatment with cisplatin, a DNA-damaging anticancer drug that is used extensively in the clinic. We compared the response to cisplatin of LCSCs and differentiated LCSCs (dLCSCs) by determining the viability of these cells, and their ability to accumulate cisplatin and to implement genomic and transcription-coupled DNA repair. We also investigated the transcription profiles of genes related to drug transport and DNA repair. KEY RESULTS: LCSCs were found to be more stem-like, and more resistant to cisplatin-induced cytotoxicity than dLCSCs, confirming their drug resistance properties. LCSCs accumulated less cisplatin intracellularly than dLCSCs and showed less DNA damage, potentially due to their ability to down-regulate AQP2 and CTR1. The results of the transcription-coupled repair of cisplatin-DNA cross-links indicated a higher level of repair of DNA damage in LCSCs than in dLCSCs. In addition, LCSCs showed a greater ability to repair cisplatin-DNA interstrand cross-links than dLCSCs; this involved the activation of various DNA repair pathways. CONCLUSIONS AND IMPLICATIONS: Our results further clarify the mechanism of cisplatin resistance in LCSCs in terms of reduced cisplatin uptake and enhanced ability to implement DNA repairs. These findings may aid in the design of the next-generation of platinum-based anticancer drugs.

Au Nanoparticles Decorated TiO2 Nanotube Arrays as a Recyclable Sensor for Photoenhanced Electrochemical Detection of Bisphenol A.

A photorefreshable and photoenhanced electrochemical sensing platform for bisphenol A (BPA) detection based on Au nanoparticles (NPs) decorated carbon doped TiO2 nanotube arrays (TiO2/Au NTAs) is described. The TiO2/Au NTAs were prepared by quick annealing of anodized nanotubes in argon, followed by controllable electrodeposition of Au NPs. The decoration of Au NPs not only improved photoelectrochemical behavior but also enhanced electrocatalytic activities of the resulted hybrid NTAs. Meanwhile, the high photocatalytic activity of the NTAs allowed the electrode to be readily renewed without damaging the microstructures and surface states after a short UV treatment. The electrochemical detection of BPA on TiO2/Au NTAs electrode was significantly improved under UV irradiation as the electrode could provide fresh reaction surface continuously and the further increased photocurrent resulting from the improved separation efficiency of the photogenerated electron-hole pairs derived from the consumption of holes by BPA. The results showed that the refreshable TiO2/Au NTAs electrode is a promising sensor for long-term BPA monitoring with the detection limit (S/N = 3) of 6.2 nM and the sensitivity of 2.8 µA·µM(-1)·cm(-2).

Microfluidic Platform for Studying Chemotaxis of Adhesive Cells Revealed a Gradient-Dependent Migration and Acceleration of Cancer Stem Cells.

Recent studies reveal that solid tumors consist of heterogeneous cells with distinct phenotypes and functions. However, it is unclear how different subtypes of cancer cells migrate under chemotaxis. Here, we developed a microfluidic device capable of generating multiple stable gradients, culturing cells on-chip, and monitoring single cell migratory behavior. The microfluidic platform was used to study gradient-induced chemotaxis of lung cancer stem cell (LCSC) and differentiated LCSC (dLCSC) in real time. Our results showed the dynamic and differential response of both LCSC and dLCSC to chemotaxis, which was regulated by the ß-catenin dependent Wnt signaling pathway. The microfluidic analysis showed that LCSC and dLCSC from the same origin behaved differently in the same external stimuli, suggesting the importance of cancer cell heterogeneity. We also observed for the first time the acceleration of both LCSC and dLCSC during chemotaxis caused by increasing local concentration in different gradients, which could only be realized through the microfluidic approach. The capability to analyze single cell chemotaxis under spatially controlled conditions provides a novel analytical platform for the study of cellular microenvironments and cancer cell metastasis.

Activation of multiple signaling pathways during the differentiation of mesenchymal stem cells cultured in a silicon nanowire microenvironment.

Mesenchymal stem cells (MSC) offer an optimal source for bone tissue engineering due to their capability of undergoing multilineage differentiation, where the mechanical properties of the microenvironment of MSCs are vital for osteochondral formation. However, the mechanisms of how mechanical and microenvironmental cues control osteogenesis and chondrogenesis are yet to be elucidated. In this study, we investigated the effects of vertically aligned silicon nanowire (SiNW) array on the differentiation of MSCs and the associated molecular mechanisms involved in osteogenesis and chandrogenesis. The results showed that the microenvironment of SiNW array activated a number of mechanosensitive pathways (including Integrin, TGF-ß/BMP, Akt, MAPK, Insulin, and Wnt pathways) in MSCs, which converged to stimulate the osteogenesis and chondrogenesis via the Ras-Raf-MEK-ERK cascade. FROM THE CLINICAL EDITOR: This study reports on the mechanisms and microenvironmental influence of osteogenesis and chondrogenesis by mesenchymal stem cells interacting with vertically aligned silicon nanowire scaffolds.

Label-free detection of endocrine disrupting chemicals by integrating a competitive binding assay with a piezoelectric ceramic resonator.

A piezoelectric biosensor for detection of endocrine disrupting chemicals (EDCs) was developed by incorporating chemical/biochemical recognition elements on the ceramic resonator surface for competitive binding assays. A facile electrodeposition was employed to modify the sensor surface with Au nanoparticles, which increased the surface area and enhanced the binding capacity of the immobilized probes. Thiol-labeled long chain hydrocarbon with bisphenol A (BPA) as head group was synthesized and self-assembled on the Au nanoparticle surface as the sensing probes, which showed a linear response upon the binding of estrogen receptor (ER-α) ranging from 1 to 30 nM. Detection of estrone, 17ß-estradiol and BPA was achieved by integrating a competitive binding assay with the piezoelectric sensor. In this detection scheme, different concentrations of EDCs were incubated with 30 nM of ER-α, and the un-bounded ER-α in the solution was captured by the probes immobilized on the ceramic resonator, which resulted in the frequency changes for different EDCs. The biosensor assay exhibited a linear response to EDCs with a low detection limit of 2.4-2.9 nM (S/N=3), and required only a small volume of sample (1.5 µl) with the assay time of 2h. The performance of the biosensor assay was also evaluated for rapid and facile determination of EDCs of environmental relevant concentrations in drinking water and seawater, and the recovery rate was in the range between 94.7% and 109.8%.

Reorganization of cytoskeleton and transient activation of Ca2+ channels in mesenchymal stem cells cultured on silicon nanowire arrays.

Tissue engineering combines biological cells and synthetic materials containing chemical signaling molecules to form scaffolds for tissue regeneration. Mesenchymal stem cells (MSCs) provide an attractive source for tissue engineering due to their versatility of multipotent differentiation. Recently, it has been recognized that both chemical and mechanical stimulations are essential mediators of adhesion and differentiation of MSCs. While significant progress has been made on the understanding of chemical regulatory factors within the extracellular matrix, the effects of mechanical stimulation exerted by nanomaterials on MSCs and the underlying mechanisms are less well-known. The present study showed that the adhesion, proliferation, and differentiation of MSCs cultured on vertically aligned silicon nanowire (SiNW) arrays were significantly different from those on flat silicon wafer and control substrates. The interactions between MSCs and the SiNW arrays caused the stem cells to preferentially differentiate toward osteocytes and chondrocytes but not adipocytes in the absence of supplementary growth factors. Our study demonstrated that Ca(2+) ion channels were transiently activated in MSCs upon mechanical stimulation, which eventually led to activation of Ras/Raf/MEK/ERK signaling cascades to regulate adhesion, proliferation, and differentiation of MSCs. The stretch-mediated transient Ca(2+) ion channel activation and cytoskeleton reorganization during stem cell-nanowire interaction may be early events of lineage-specific potentiation of MSCs in determining the fates of mesenchymal stem cells cultured on microenvironments with specific mechanical properties.

Detection of cancer biomarkers by piezoelectric biosensor using PZT ceramic resonator as the transducer.

A novel piezoelectric biosensor using lead titanate zirconate (PZT) ceramic resonator as transducer was developed for label-free, cost-effective, and direct detection of cancer biomarkers. We designed a dual sensing scheme where two ceramic resonators were connected in parallel, in which one resonator was used as the sensing unit and the other as the control unit, in order to minimize environment influences including temperature fluctuation and to achieve the required frequency stability for biosensing applications. Detection of selected cancer biomarkers, such as prostate specific antigen (PSA) and α-fetoprotein (AFP) was carried out to evaluate the performance of the biosensor. The device showed high sensitivity (0.25 ng/ml) and fast detection (within 30 min) with small amount of sample (1 µl), which is compatible to that required by clinical measurements. The results also showed that the ceramic resonator-based piezoelectric biosensor platform could be utilized with different chemical interfaces, and the miniaturized size of the ceramic resonators makes it suitable for fabricating sensor arrays for multiplex detection.

Herbal formula Astragali Radix and Rehmanniae Radix exerted wound healing effect on human skin fibroblast cell line Hs27 via the activation of transformation growth factor (TGF-ß) pathway and promoting extracellular matrix (ECM) deposition.

Astragali Radix (AR) and Rehmanniae Radix (RR) have long been used in traditional Chinese Medicine and as the principal herbs in treating diabetic foot ulcer. In this study, we investigated the effect of NF3, which comprises of AR and RR in the ratio of 2:1(w/w), on skin fibroblast cell migration and the activation of selected genes and proteins related to wound healing. Human skin fibroblast cell line Hs27 was treated with NF3 at 4 mg/ml for 24h, and in vitro scratch wound healing and quantitative cell migration assays were performed, respectively. The expression of transformation growth factor (TGF-ß1) and bone morphogenetic protein 6 (BMP6) in Hs27 cells with or without NF3 treatment was analyzed by western blot analysis. In addition, the expression of a panel of genes involved in human TGF-ß signaling pathway was analyzed in Hs27 cells upon NF3 treatment (4 mg/ml, 24 h) by quantitative real-time PCR (qRT-PCR). Furthermore, the expression of several genes and proteins associated with ECM synthesis was investigated by qRT-PCR analysis or/and ELISA techniques. The results suggested that NF3 promoted the migration of human skin fibroblast cells. Western blot analysis demonstrated that NF3 up-regulated TGF-ß1 and BMP-6 synthesis. qRT-PCR analysis revealed that the expression of 26 genes in Hs27 cells was changed upon NF3 induction, including TGF-ß superfamily ligands and down stream effectors genes, and genes involved in TGF/Smad pathway, and Ras/MAPK (non-Smad) pathway. Among the extracellular matrix (ECM)-related molecules, it was found that NF3 up-regulated the expression of type I and III collagens, fibronectin as well as TIMP-1, and down-regulated the MMP-9 expression in skin fibroblast cells. This study demonstrated that herb formula NF3 could enhance skin fibroblast cell migration and activated genes involved in TGF-ß1 pathway. NF3 could regulate gene transcription for extracellular matrix synthesis via the Smad pathway, and gene transcription for cell motility via the Ras/MAPK (non-Smad) pathway.

Imipramine inhibits adipogenic differentiation in both 3T3-L1 preadipocytes and mouse marrow stromal cells.

Imipramine (IM) has been widely used clinically for the treatment of mental disorders. Its actions on tissues or organs other than the nervous system also need to be understood for its proper clinical use. In this study, the effects of IM on adipogenic differentiation in both 3T3-L1 preadipocytes and mouse marrow stromal cells (MSCs) were investigated. The results showed that fewer adipocytic cells were developed from 3T3-L1 preadipocytes in the presence of 0.001 to 1 µmol/L of IM as compared to control. Similar inhibitory effect was also observed in mouse MSCs. The decrease in the formation of adipocytes was accompanied with significant down-regulation at mRNA expression of the early adipogenic transcription factor, peroxisome proliferator-activated receptor γ2 (PPARγ2). Western blot analysis further revealed that the protein expression of PPARγ2 was reduced markedly in cells treated with IM at concentrations of 0.01, 0.1 and 1 µmol/L, suggesting that the suppression on PPARγ2 was involved in IM's inhibition on MSCs adipogenesis. Moreover, IM at the above concentrations could stimulate the mRNA expression of ß2-adrenergic receptor (AR) and ß3-AR, which implicated that the effect of IM on adipogenic differentiation was partially mediated by ß-ARs. Our results demonstrated for the first time that the conventional antidepressive imipramine exerts accompanied inhibitory effect on adipocyte formation, which may have possible clinical implications.

Transcriptional profiling of human skin fibroblast cell line Hs27 induced by herbal formula Astragali Radix and Rehmanniae Radix.

ETHNOPHARMACOLOGICAL RELEVANCE: The herbs Astragali Radix (AR) and Rehmanniae Radix (RR) have long been used in traditional Chinese Medicine and serve as the principal herbs in treating diabetic foot ulcer. AIM OF THE STUDY: Chinese herbal formulus comprising Astragali Radix (AR) and Rehmanniae Radix (RR) have been shown to improve the healing of diabetic foot ulcer through enhancing the viability of primary fibroblasts in diabetic patients suffering insulin resistance. Our previous study demonstrated that the herbal formula NF3 comprising of AR and RR in the ratio of 2:1 was effective in promoting wound healing in diabetic rats, and in vitro data indicated that the wound healing effects of NF3 might be due to the regulation and coordination of inflammation, angiogenesis and tissue regeneration. However, the underlying molecular mechanism has not been well investigated. In this study, we investigated the cellular and molecular effects of the herbal formula NF3 on human skin fibroblast cells. MATERIALS AND METHODS: Human skin fibroblast cells Hs27 were treated with NF3 ranging from 0 to 8 mg/ml for 24h, and the cells without NF3 treatment were used as control. Cell proliferation assay and cell cycle analysis were performed. Transcriptional profiles of Hs27 cells upon NF3 treatment were acquired by using a human cDNA microarray containing 10,000 genes, and the signaling pathways differentially regulated by NF3 were identified and analyzed. RESULTS: NF3 promoted Hs27 cell proliferation and cell cycle progression. Microarray analysis revealed that 116 genes were differentially expressed upon NF3 treatment. Functional analysis of the genes indicated that NF3 mainly activated Wnt and angiogenesis related pathways, which are directly related to cell proliferation, angiogenesis, extracellular matrix (ECM) formation and inflammation during the process of wound healing. CONCLUSION: This study provides insight into the molecular mechanism of how the herbal formula Astragali Radix and Rehmanniae Radix may serve as potential therapeutics for wound healing.

Danshen-Gegen decoction exerts proliferative effect on rat cardiac myoblasts H9c2 via MAPK and insulin pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Danshen (root of Salvia miltiorrhiza) and Gegen (roots of Pueraria lobata) are traditional Chinese medicines that have been used in combination for cardiovascular disease treatment. AIM OF THE STUDY: The present study was performed to investigate the effect of Danshen-Gegen decoction on rat myocardium cell line H9c2 and the possible molecular mechanisms. MATERIALS AND METHODS: Rat heart myocardium H9c2 cells were treated with or without Danshen-Gegen decoction (DG) ranging from 10 to 1000µg/ml for 24h. Cell viability was measured by Alarma blue assay and cell proliferation assay was performed by BrdU Cell Proliferation ELISA kit. The activation of mitogen-activated protein kinase and insulin pathways was analyzed by Luminex technology and the growth factors and cytokine expression of H9c2 cells induced by DG was evaluated by protein array. Moreover, a rat functional specific cDNA microarray was constructed to study the gene expression profiles of H9c2 cells upon the DG treatment at 50µg/ml for 24h. RESULTS: DG promoted H9c2 cell viability and cell proliferation at dose-dependent manner within the range between 0 and 250µg/ml. A Bio-Plex assay kit (Bio-Rad Bioscience) was used to detect the expression level of phosphoprotein as well as total proteins involved in the MAPK and insulin pathways. Significant phosphorylation of ERK, c-Jun, JNK, p38, AKT, IGF-IR, IRS-1and I kappa B were observed after DG treatment at 2h or 4h. A rat cytokine antibody array was used to detect and quantify 22 growth factors and cytokines in samples collected from the control and DG treated H9c2 cells. In the category of growth factors, GM-CSF, CNIF and b-NGF were stimulated by DG, while the expression of TIMP-1 was suppressed. For cytokine expression, it was found that DG stimulated three interleukin subclasses, IL-1α, 1X and 6, respectively. However, the expression of pro-inflammatory factors such as TNF-α and IFN-γ were down-regulated significantly. Moreover, the microarray analysis revealed that DG significantly up-regulated anti-apoptosis related genes such as Cdkn2c and Ppp3ca, and several cardiovascular disease suppressers and anti-inflammatory mediators; on the other hand, pro-apoptotic related genes including Caspase and Tnf-α were down-regulated by DG. Based on the results, a tentative scheme was proposed to show that the activation of the MAPK and insulin pathways are involved in the bioactive effect of Danshen-Gegen decoction on cardiomyocytes. CONCLUSION: Our study suggested that Danshen-Gegen decoction has proliferative effect on myocardium cells via MAPK and insulin signaling pathways. The molecular mechanism of the action may include the up-regulation of IRS/AKT and JNK pathways as well as the inhibition of TNF and p38 pathways.

Gold nanoparticles promote osteogenic differentiation of mesenchymal stem cells through p38 MAPK pathway.

Understanding the interaction mechanisms between nanomaterials and biological cells is important for the control and manipulation of these interactions for biomedical applications. In this study, we investigated the cellular effects of gold nanoparticles (AuNPs) on the differentiation of mesenchymal stem cells (MSCs) and the associated molecular mechanisms. The results showed that AuNPs promoted the differentiation of MSCs toward osteoblast cells over adipocyte cells by inducing an enhanced osteogenic transcriptional profile and an attenuated adipogenic transcriptional profile. AuNPs exerted the effects by interacting with the cell membrane and binding with proteins in the cytoplasm, causing mechanical stress on the MSCs to activate p38 mitogen-activated protein kinase pathway (MAPK) signaling pathway, which regulates the expression of relevant genes to induce osteogenic differentiation and inhibit adipogenic differentiation.

Transcriptional analysis of doxorubicin-induced cytotoxicity and resistance in human hepatocellular carcinoma cell lines.

BACKGROUND/AIMS: Hepatoma is either intrinsically resistant to chemotherapy or response to it but later develop resistance. The aim of this study was to clarify the relationship of treatment with doxorubicin (Dox) in hepatoma HepG2 cells and drug resistance developed by Dox. METHODS: We have analysed the bioactivities and gene expression profiles of multidrug resistant (MDR) HepG2/DR cell line and its parental HepG2 cell, which were exposure to Dox. RESULTS: We confirmed that Dox-induced apoptosis of HepG2 cells in a time-dependent manner; cDNA microarray and hierarchical cluster analysis demonstrate that the features of the transcriptional programme of the later response to Dox in HepG2 cells and MDR HepG2/DR cells have a common character, which is upregulation of stress response, cytoskeleton, ubiquitin-proteasome pathway and repressed G-protein signal transduction system; differentially expressed genes in MDR HepG2/DR such as drug transporters and tumour-associated antigens were verified at the levels of mRNA by semiquantitative reverse transcriptase-polymerase chain reaction. CONCLUSIONS: These results reveal novel co-ordinated changes that occurred in resistant HepG2 cells to survive from cell apoptosis elicited by Dox treatment.

Gene expression analysis of human promyelocytic leukemia HL-60 cell differentiation and cytotoxicity induced by natural and synthetic retinoids.

AIMS: This study analyzed gene expression profiles of human promyelocytic leukemia HL-60 cells treated with natural and synthetic retinoids (ATRA, RII and R9158), in an attempt to investigate the structure-function relationship of the retinoids in inducing cell differentiation and cytotoxicity. MAIN METHODS: Flow cytometry was used to determine cell cycle changes in HL-60 cells following treatment (1.0 muM) with natural and synthetic retinoids (ATRA, RII and R9158), and cDNA microarrays were used to monitor the gene expression profiles of HL-60 cells treated with the various retinoids. KEY FINDINGS: Consistent with retinoid-induced cell differentiation, treatment with these three retinoids correlated with an increase in the percentage of cells arrested in the G1/G0 phase of the cell cycle. Microarray analysis showed upregulation of known differentiation genes, adhesion molecules, and the oxidase activation pathway following retinoid treatment. Differential expression of several genes was observed in HL-60 cells treated with the three retinoids. For example, tissue remodeling protein genes, ubiquitin genes, and signal transduction genes were highly expressed in ATRA- and R9158-treated HL-60 cells, but remained unchanged in HL-60 cells treated with RII. SIGNIFICANCE: The above findings suggest that the differentiation of HL-60 cells induced by the three retinoids occurs through similar pathways, and that there exists a structure-function relationship regarding retinoids and the induction of cell differentiation and cytotoxicity.

Cell adhesion and spreading behavior on vertically aligned silicon nanowire arrays.

In this report, we studied the interactions between biological cells and vertically aligned silicon nanowire (SiNW) arrays and focused on how SiNW arrays affected cellular behaviors such as cell adhesion and spreading. We observed that SiNW arrays could support cell adhesion and growth and guide cell adhesion and spreading behaviors. The results also showed that SiNW arrays could not only enhance the cell-substrate adhesion force but also restrict cell spreading. Combining the results from scanning electron microscopy images of cell morphology and the expression analysis of genes and proteins related to cell adhesion and spreading process, we proposed a mechanism on how cell adhesion and spreading was controlled by arrayed SiNWs. The effects of SiNW arrays in guiding cell adhesion and spreading behavior might be useful in the development of cell microarrays, tissue engineering scaffolds, and molecule delivery vehicles in which strong cell-substrate adhesion and reduced cell-cell communication were beneficial.

Gene expression analysis of human promyelocytic leukemia HL-60 cell differentiation and cytotoxicity induced by natural and synthetic retinoids.

AIMS: This study analyzed gene expression profiles of human promyelocytic leukemia HL-60 cells treated with natural and synthetic retinoids (ATRA, RII and R9158), in an attempt to investigate the structure-function relationship of the retinoids in inducing cell differentiation and cytotoxicity. MAIN METHODS: Flow cytometry was used to determine cell cycle changes in HL-60 cells following treatment (1.0 µM) with natural and synthetic retinoids (ATRA, RII and R9158), and cDNA microarrays were used to monitor the gene expression profiles of HL-60 cells treated with the various retinoids. KEY FINDINGS: Consistent with retinoid-induced cell differentiation, treatment with these three retinoids correlated with an increase in the percentage of cells arrested in the G1/G0 phase of the cell cycle. Microarray analysis showed upregulation of known differentiation genes, adhesion molecules, and the oxidase activation pathway following retinoid treatment. Differential expression of several genes was observed in HL-60 cells treated with the three retinoids. For example, tissue remodeling protein genes, ubiquitin genes, and signal transduction genes were highly expressed in ATRA- and R9158-treated HL-60 cells, but remained unchanged in HL-60 cells treated with RII. SIGNIFICANCE: The above findings suggest that the differentiation of HL-60 cells induced by the three retinoids occurs through similar pathways, and that there exists a structure-function relationship regarding retinoids and the induction of cell differentiation and cytotoxicity.