Alpha-hederin induces the apoptosis of oral cancer SCC-25 cells by regulating PI3K/Akt/mTOR signaling pathway

BackgroundOral cancer is one of the common malignant tumors of the head and neck. However, current treatments have numerous side effects, and drugs from natural sources may have better therapeutic potential. This research investigated the induction of apoptosis by α-hederin (α-HN), a constituent of Pulsatilla chinensis (Bunge) Regel, in the oral cancer cell line SCC-25 and its underlying mechanism.ResultsSCC-25 cells were treated with 50, 100, and 200 μmol/L α-HN. Cell proliferation; extent of apoptosis; activities of caspases-3, 8, and 9; and the expression of Bcl-2, Bax, phosphorylated (p)-phosphoinositide 3-kinase (PI3K), p-Akt, and p-mammalian target of rapamycin (mTOR) proteins were determined using the 3-(4,5)-2-thiazole-(2,5)-diphenyl tetrazolium bromide, flow cytometry, caspase activity detection kits, and western blot assays, respectively. The results showed that the proliferation of SCC-25 cells in the α-HN-treated groups decreased significantly, and the inhibitory effect was time and concentration dependent. Compared with cells in the control group, the extent of apoptosis increased significantly, caspase-3 and -9 activities were significantly enhanced, and the Bcl-2 level was lowered and the Bax level was elevated significantly in SCC-25 cells treated with α-HN for 48 h (P < 0.05). The expression of p-PI3K, p-Akt, and p-mTOR was also significantly lower in SCC-25 cells treated with α-HN than that in the control group (P < 0.05).ConclusionThese results indicate that α-HN can inhibit proliferation and induce apoptosis of SCC-25 cells and may exert these effects by inhibiting the PI3K/Akt/mTOR signaling pathway.How to cite: Wang H, Wu B, Wang H. Alpha-hederin induces the apoptosis of oral cancer SCC-25 cells by regulating PI3K/Akt/mTOR signaling pathway. Electron J Biotechnol 2019;38. https://doi.org/10.1016/j.ejbt.2018.12.005     

On-chip assay of the effect of topographical microenvironment on cell growth and cell-cell interactions during wound healing

Wound healing is an essential physiological process for tissue homeostasis, involving multiple types of cells, extracellular matrices, and growth factor/chemokine interactions. Many in vitro studies have investigated the interactions between cues mentioned above; however, most of them only focused on a single factor. In the present study, we design a wound healing device to recapitulate in vivo complex microenvironments and heterogeneous cell situations to investigate how three types of physiologically related cells interact with their microenvironments around and with each other during a wound healing process. Briefly, a microfluidic device with a micropillar substrate, where diameter and interspacing can be tuned to mimic the topographical features of the 3D extracellular matrix, was designed to perform positional cell loading on the micropillar substrate, co-culture of three types of physiologically related cells, keratinocytes, dermal fibroblasts, and human umbilical vein endothelial cells, as well as an investigation of their interactions during wound healing. The result showed that cell attachment, morphology, cytoskeleton distribution, and nucleus shape were strongly affected by the micropillars, and these cells showed collaborative response to heal the wound. Taken together, these findings highlight the dynamic relationship between cells and their microenvironments. Also, this reproducible device may facilitate the in vitro investigation of numerous physiological and pathological processes such as cancer metastasis, angiogenesis, and tissue engineering.     

Enhanced production of glutaminase-free l-asparaginase by marine Bacillus velezensis and cytotoxic activity against breast cancer cell lines

BackgroundThe increasing rate of breast cancer globally requires extraordinary efforts to discover new effective sources of chemotherapy with fewer side effects. Glutaminase-free l-asparaginase is a vital chemotherapeutic agent for various tumor malignancies. Microorganisms from extreme sources, such as marine bacteria, might have high l-asparaginase productivity and efficiency with exceptional antitumor action toward breast cancer cell lines.Resultsl-Asparaginase-producing bacteria, Bacillus velezensis isolated from marine sediments, were identified by 16S rRNA sequencing. l-Asparaginase production by immobilized cells was 61.04% higher than that by free cells fermentation. The significant productivity of enzyme occurred at 72 h, pH 6.5, 37°C, 100 rpm. Optimum carbon and nitrogen sources for enzyme production were glucose and NH₄Cl, respectively. l-Asparaginase was free from glutaminase activity, which was crucial medically in terms of their severe side effects. The molecular weight of the purified enzyme is 39.7 KDa by SDS-PAGE analysis and was ideally active at pH 7.5 and 37°C. Notwithstanding, the highest stability of the enzyme was found at pH 8.5 and 70°C for 1 h. The enzyme kinetic parameters displayed V_max at 41.49 μmol/mL/min and a K_m of 3.6 × 10⁻⁵ M, which serve as a proof of the affinity to its substrate. The anticancer activity of the enzyme against breast adenocarcinoma cell lines demonstrated significant activity toward MDA-MB-231 cells when compared with MCF-7 cells with IC₅₀ values of 12.6 ± 1.2 μg/mL and 17.3 ± 2.8 μg/mL, respectively.ConclusionThis study provides the first potential of glutaminase-free l-asparaginase production from the marine bacterium Bacillus velezensis as a prospect anticancer pharmaceutical agent for two different breast cancer cell lines.How to cite: Mostafa Y, Alrumman S, Alamri S, et al. Enhanced production of glutaminase-free L-asparaginase by marine Bacillus velezensis and cytotoxic activity against breast cancer cell lines. Electron J Biotechnol 2019;42. https://doi.org/10.1016/j.ejbt.2019.10.001.     

Microfluidic cell fragmentation for mechanical phenotyping of cancer cells

Circulating tumor cells (CTCs) shed from the primary tumor undergo significant fragmentation in the microvasculature, and very few escape to instigate metastases. Inspired by this in vivo behavior of CTCs, we report a microfluidic method to phenotype cancer cells based on their ability to arrest and fragment at a micropillar-based bifurcation. We find that in addition to cancer cell size, mechanical properties determine fragmentability. We observe that highly metastatic prostate cancer cells are more resistant to fragmentation than weakly metastatic cells, providing the first indication that metastatic CTCs can escape rupture and potentially initiate secondary tumors. Our method may thus be useful in identifying phenotypes that succumb to or escape mechanical trauma in microcirculation.     

Expression,purification and biological effect of a novel single chain Fv antibody and protamine fusion protein for the targeted delivery of siRNAs to FGFR3 positive cancer cells

BackgroundGain-of-function of fibroblast growth factor receptor 3 (FGFR3) is involved in the pathogenesis of many tumors. More and more studies have focused on the potential usage of therapeutic single-chain Fv (ScFv) antibodies against FGFR3. RNA interference (RNAi) has been considered as a promising therapeutic method against cancer. A tool which can deliver small interference RNAs (siRNAs) into FGFR3 positive cancer cells is very promising for anti-tumor therapy.ResultsIn this study, a novel fusion protein R3P, which consists of FGFR3-ScFv and protamine, was generated in Escherichia coli by inclusion body expression strategy and Ni-NTA chromatography. Its yield reached 10 mg per liter of bacterial culture and its purity was shown to be higher than 95%. 1 μg of R3P could efficiently bind to about 2.5 pmol siRNAs and deliver siRNAs into FGFR3 positive RT112 and K562 cells. Annexin V staining results showed that R3P can deliver the amplified breast cancer 1 (AIB1) siRNAs to induce RT112 cell apoptosis.ConclusionThese results indicated that R3P was a promising carrier tool to deliver siRNAs into FGFR3 positive cancer cells and to exert anti-tumor effect.     

Quantitative impedimetric monitoring of cell migration under the stimulation of cytokine or anti-cancer drug in a microfluidic chip

Cell migration is a cellular response and results in various biological processes such as cancer metastasis, that is, the primary cause of death for cancer patients. Quantitative investigation of the correlation between cell migration and extracellular stimulation is essential for developing effective therapeutic strategies for controlling invasive cancer cells. The conventional method to determine cell migration rate based on comparison of successive images may not be an objective approach. In this work, a microfluidic chip embedded with measurement electrodes has been developed to quantitatively monitor the cell migration activity based on the impedimetric measurement technique. A no-damage wound was constructed by microfluidic phenomenon and cell migration activity under the stimulation of cytokine and an anti-cancer drug, i.e., interleukin-6 and doxorubicin, were, respectively, investigated. Impedance measurement was concurrently performed during the cell migration process. The impedance change was directly correlated to the cell migration activity; therefore, the migration rate could be calculated. In addition, a good match was found between impedance measurement and conventional imaging analysis. But the impedimetric measurement technique provides an objective and quantitative measurement. Based on our technique, cell migration rates were calculated to be 8.5, 19.1, and 34.9 μm/h under the stimulation of cytokine at concentrations of 0 (control), 5, and 10 ng/ml. This technique has high potential to be developed into a powerful analytical platform for cancer research.     

Electrotaxis of lung cancer cells in ordered three-dimensional scaffolds

In this paper, we report a new method to incorporate 3D scaffold with electrotaxis measurement in the microfluidic device. The electrotactic response of lung cancer cells in the 3D foam scaffolds which resemble the in vivo pulmonary alveoli may give more insight on cellular behaviors in vivo. The 3D scaffold consists of ordered arrays of uniform spherical pores in gelatin. We found that cell morphology in the 3D scaffold was different from that in 2D substrate. Next, we applied a direct current electric field (EF) of 338 mV/mm through the scaffold for the study of cells’ migration within. We measured the migration directedness and speed of different lung cancer cell lines, CL1-0, CL1-5, and A549, and compared with those examined in 2D gelatin-coated and bare substrates. The migration direction is the same for all conditions but there are clear differences in cell morphology, directedness, and migration speed under EF. Our results demonstrate cell migration under EF is different in 2D and 3D environments and possibly due to different cell morphology and/or substrate stiffness.     

Effect of vimentin on cell migration in collagen-coated microchannels: A mimetic physiological confined environment

Cancer cell migration through tissue pores and tracks into the bloodstream is a critical biological step for cancer metastasis. Although in vivo studies have shown that expression of vimentin can induce invasive cell lines, its role in cell cytoskeleton reorganization and cell motility under in vitro physical confinement remains unknown. Here, a microfluidic device with cell culture chamber and collagen-coated microchannels was developed as an in vitro model for physiological confinement environments. Using this microchannel assay, we demonstrated that the knockdown of vimentin decreases 3T3 fibroblast cell directional migration speed in confined microchannels. Additionally, as cells form dynamic membranes that define the leading edge of motile cells, different leading edge morphologies of 3T3 fibroblast and 3T3 vimentin knockdown cells were observed. The leading edge morphology change under confinement can be explained by the effect of vimentin on cytoskeletal organization and focal adhesion. The microfluidic device integrated with a time-lapse microscope provided a new approach to study the effect of vimentin on cell adhesion, migration, and invasiveness.     

Label-free isolation of a prostate cancer cell among blood cells and the single-cell measurement of drug accumulation using an integrated microfluidic chip

Circulating tumor cells (CTCs) are found in the blood of patients with cancer. Although these cells are rare, they can provide useful information for chemotherapy. However, isolation of these rare cells from blood is technically challenging because they are small in numbers. An integrated microfluidic chip, dubbed CTC chip, was designed and fabricated for conducting tumor cell isolation. As CTCs usually show multidrug resistance (MDR), the effect of MDR inhibitors on chemotherapeutic drug accumulation in the isolated single tumor cell is measured. As a model of CTC isolation, human prostate cancer cells were mixed with mouse blood cells and the label-free isolation of the tumor cells was conducted based on cell size difference. The major advantages of the CTC chip are the ability for fast cell isolation, followed by multiple rounds of single-cell measurements, suggesting a potential assay for detecting the drug responses based on the liquid biopsy of cancer patients.     

Defensin γ-thionin from Capsicum chinense improves butyrate cytotoxicity on human colon adenocarcinoma cell line Caco-2

BackgroundButyrate is a histone deacetylase inhibitor that induces apoptosis and inhibits cell proliferation of colorectal cancer cells. To improve its anticancer activity, butyrate has been evaluated mixed with drugs and different molecules. Plant antimicrobial peptides are attractive anticancer alternative molecules because they show selective cytotoxic activity against different cancer cell lines. In this work, we explore if the plant defensin γ-thionin (Capsicum chinense) can improve butyrate activity on Caco-2 cell line and we also determined the mechanism of death activated.ResultsThe combined treatment of γ-thionin (3.5 µM) and butyrate (50 mM) showed higher cytotoxicity on Caco-2 cells with respect to single treatments. Also, the combined treatment reduced cell proliferation and exhibited a higher rate of apoptosis than single treatments. Combined treatment induced caspases 8 and 9 activation to an extent comparable with that of butyrate while γ-thionin did not activate caspases. Additionally, reactive oxygen species generation preceded the onset of apoptosis, and superoxide anion production was higher in cells treated with the combined treatment.ConclusionsThe γ-thionin from Habanero chili pepper improved the butyrate cytotoxicity on Caco-2 cells. This effect occurred through apoptosis induction associated with reactive oxygen species production. Therefore, the combination of butyrate with cytotoxic antimicrobial peptides could be an attractive strategy for cancer therapy.How to cite: Velázquez-Hernández ME, Ochoa-Zarzosa A, López-Meza JE, Defensin γ-thionin from Capsicum chinense improves butyrate cytotoxicity on human colon adenocarcinoma cell line Caco-2. Electron J Biotechnol 2021;52. https://doi.org/10.1016/j.ejbt.2021.04.009     

本土企业逆向创新中的专利演化：基于Lotka–Volterra竞争模型

当前逆向创新越来越多地发生在发展中国家的本土企业中,体现为本土企业在海外申请的专利日益增加,其专利的发展演化过程也体现了企业的逆向创新和技术追赶过程。为了深入探讨该过程中的专利演化影响因素及演化结果,本文通过构建一个本土企业逆向创新不同阶段竞争的Lotka–Volterra生态模型,并通过数值仿真,模拟和分析本土企业在逆向创新国内和国外两个不同市场条件下的专利演化情况。研究表明：在逆向创新中,本土企业的专利演化主要由其资源竞争能力来决定;但在国外市场阶段,当企业之间的竞争能力差距不大时,处于劣势的企业有机会在专利的竞争获得一定的发展空间。为此,本文从企业资源竞争能力提升角度提出了相应的对策建议。本文研究可以为促进本土企业的逆向创新和专利发展提供一定的理论和对策依据。     

Protein Thiols and Butryrylcholinestrase in Saliva of Oral Cancer Patients

Oral squamous cell carcinoma is one of the most common malignancies recognized. Biomarkers which can predict presence of cancer and its progression can help in better management of these disorders. Over production of lipid peroxidation byproducts and disturbances in antioxidant defense system have been implicated in the pathogenesis of several diseases including oral cancer. Studies have shown a correlation of butyrylcholinesterase (BChE), with tumourigenesis, cell proliferation and cell differentiation. Earlier we have observed a significant elevation in plasma BChE and protein thiols in oral cancer patients which correlated well with stages of cancer. As it was not clear whether the above markers will be altered in saliva of oral cancer patients this study was undertaken. Institutional Ethics Committee gave permission to carry out this study. Total of 55 subjects comprising healthy controls (n = 30) and biopsy proven oral cancer patients (n = 25) consented to participate in this study. Salivary samples from cases were taken before any definitive treatment. Protein thiols and BChE were estimated in salivary samples using validated assay methods. Oral cancer patients had a significant increase in pre-treatment salivary BChE levels (p ≤ 0.001) and a significant decrease (p ≤ 0.001) in salivary thiols as compared to respective values in controls. Salivary protein thiols and BChE may have a role in pathophysiology of oral cancer. Saliva can be used as a potential non-invasive screening tool in oral cancer patients.     

Targeting HSPA1A in ARID2-deficient lung adenocarcinoma

Somatic mutations of the chromatin remodeling gene ARID2 are observed in ∼7% of human lung adenocarcinomas (LUADs). However, the role of ARID2 in the pathogenesis of LUADs remains largely unknown. Here we find that ARID2 expression is decreased during the malignant progression of both human and mice LUADs. Using two Kras^G12D-based genetically engineered murine models, we demonstrate that ARID2 knockout significantly promotes lung cancer malignant progression and shortens overall survival. Consistently, ARID2 knockdown significantly promotes cell proliferation in human and mice lung cancer cells. Through integrative analyses of ChIP-Seq and RNA-Seq data, we find that Hspa1a is up-regulated by Arid2 loss. Knockdown of Hspa1a specifically inhibits malignant progression of Arid2-deficient but not Arid2-wt lung cancers in both cell lines as well as animal models. Treatment with an HSPA1A inhibitor could significantly inhibit the malignant progression of lung cancer with ARID2 deficiency. Together, our findings establish ARID2 as an important tumor suppressor in LUADs with novel mechanistic insights, and further identify HSPA1A as a potential therapeutic target in ARID2-deficient LUADs.     

Do knowledge conditions make a difference?: Investment, finance and ownership in German industries

This paper examines the impact of industry knowledge conditions, the mode of corporate control and firm size on tangible investments and its financing. Based on a large panel data set of German firms we investigate whether financing constraints exist for tangible investment and whether there is systematic variation across firms engaged in activities reflecting different knowledge conditions. In particular, we compare the extent of financing constraints for firm in knowledge intensive (hi-K) industries with those in less knowledge-based (lo-K) industries. This distinction is important because knowledge-based economic activity tends to be subject to high degrees of uncertainty, asymmetric information and spillovers of newly created knowledge, making access to external sources of finance difficult. Our surprising empirical finding is that firms in hi-K industries are less finance constrained than are their counterparts in lo-K industries. However, the mode of corporate control and firm size play an important role. After controlling for firm size and manager versus owner control, we observe that the small manager-controlled firms in both hi-K and lo-K industries are most finance constrained. By contrast, no financing constraints seem to exist for the smaller owner-controlled firms in hi-K industries. This latter result contrasts sharply with results of Anglo-Saxon studies.     

How to institutionalize innovative clusters? Comparing explicit top-down and implicit bottom-up approaches

The cluster concept has become a popular guideline for regional policies fostering industrial competitiveness and innovativeness based on sectoral specialization and collaboration. This article discusses the issue of effective institutional forms of cluster promotion, juxtaposing two modes: Explicit cluster policies implemented top-down by regional authorities and implicit initiatives that are organized and financed bottom-up by groups of firms. Both approaches are compared from a theoretical and empirical perspective, pointing out differing patterns of effects, relative strengths and weaknesses. Realization of these differences, considered in relation to regional preconditions and objectives, may help to adequately institutionalize cluster support.     

Cytotoxicity and Apoptosis Inducing Activities of 2-Amino-4H-chromene-3-carbonitrile Derivatives Loaded on Gold Nanoparticles Against Human Breast Cancer Cell Line T47D

Chemotherapy drugs, used for prevention of uncontrolled cell proliferation in certain tissues as well as inducing apoptosis in tumor cells, are important candidates for treatment of cancer. The synthesized 2-amino-4H-chromene-3-carbonitrile derivatives effective on cancerous cells resistant to other drugs such as Paclitaxel were used due to their ability in induction of apoptosis. The growth inhibitory and inducing apoptosis activities were determined. In order to make it target-oriented, the best compound was conjugated with gold nanoparticles (NPs) by aspartic acid with chemical reduction method. Cytotoxicity effect of 2-amino-4H-chromene-3-carbonitrile derivatives against the T47D breast cancer cell line was determined by MTT assay. The synthesis of gold NPs was confirmed by transmission electron microscopy, UV–Vis and dynamic light scattering. To assess the effects of compounds on the process of apoptosis, staining methods with acridine orange–ethidium bromide and Hoechst staining by fluorescence microscopy and DNA fragmentation by the diphenylamine method were used. The synthesized compounds containing two NH₂ groups on benzene rings, demonstrated more cytotoxicity effect. The effect of conjugation with gold NPs and the induction of apoptosis were studied with the best compound. The cytotoxicity effects of the synthesized 2-amino-4H-chromene-3-carbonitrile compounds were changed by replacement of NO₂ group on thiol ring with different chemical groups on the benzene ring. Analyses of treated cell lines by conjugated and non-conjugated forms of compounds verified their ability in inducing apoptosis while conjugated form demonstrated higher apoptosis.     

No Association of Matrix Metalloproteinase [MMP]-2 (−735C > T) and Tissue Inhibitor of Metalloproteinase [TIMP]-2 (−418G > C) Gene Polymorphisms with Cervical Cancer Susceptibility

Matrix metalloproteinase [MMP]-2 and tissue inhibitor of metalloproteinase [TIMP]-2 are emerging as pivotal players in inflammation and carcinogenesis. The present study aimed to evaluate the role of MMP-2 (−735C > T) [rs 2285053] and TIMP-2 (−418G > C) [rs 8179090] gene polymorphisms in cervical cancer susceptibility in Indian women. We recruited 200 cervical cancer patients from North India and 200 unrelated, age-matched, cancer-free healthy female controls of similar ethnicity. Genomic DNA extraction from peripheral blood samples, collected from the study subjects, was carried out using salting-out method. MMP-2 and TIMP-2 genotyping was performed using polymerase chain reaction-based restriction fragment length polymorphism. Our findings demonstrated no significant association between MMP-2 (−735C > T) and TIMP-2 (−418G > C) gene polymorphisms and the risk of developing cervical cancer in the study population. Further stratified analysis using a case-only study approach revealed that there was no effect of MMP-2/TIMP-2 polymorphisms on early and advanced stages of cervical cancer. Further MMP-2 and TIMP-2 polymorphisms did not modulate the risk in cervical cancer patients who smoked tobacco/cigarettes. Overall, the present study demonstrated a lack of association between MMP-2 and TIMP-2 gene polymorphisms and cervical cancer susceptibility in women of Northern India.     

Disrupting the wall accumulation of human sperm cells by artificial corrugation

Many self-propelled microorganisms are attracted to surfaces. This makes their dynamics in restricted geometries very different from that observed in the bulk. Swimming along walls is beneficial for directing and sorting cells, but may be detrimental if homogeneous populations are desired, such as in counting microchambers. In this work, we characterize the motion of human sperm cells ∼60 μm long, strongly confined to ∼25 μm shallow chambers. We investigate the nature of the cell trajectories between the confining surfaces and their accumulation near the borders. Observed cell trajectories are composed of a succession of quasi-circular and quasi-linear segments. This suggests that the cells follow a path of intermittent trappings near the top and bottom surfaces separated by stretches of quasi-free motion in between the two surfaces, as confirmed by depth resolved confocal microscopy studies. We show that the introduction of artificial petal-shaped corrugation in the lateral boundaries removes the tendency of cells to accumulate near the borders, an effect which we hypothesize may be valuable for microfluidic applications in biomedicine.     

Effect of corticosteroids on elevated intracellular sodium, plasma lipid peroxide levels and reduced Na+, K+-ATPase activity in patients of bronchial asthma

In view of several reports that there is a lack of balance in free radicals in case of bronchial asthma (1) the effect of free radicals on cell membrane was studied by estimating the membrane bound protein Na⁺, K⁺-ATPase activity and the intracellular sodium level in patients of bronchial asthma before and after a short course (one week) of oral corticosteroid (prednisolone 0.75–1mg/kg body weight) therapy. Results showed that there is a definite statistically significant rise in free radical level and intracellular sodium level and a significant lowering of Na⁺, K⁺-ATPase activity in case of untreated bronchial asthma. After short course of therapy with oral corticosteroids, the free radical level and intracellular sodium level decreased significantly, together with a significant rise of the Na⁺, K⁺-ATPase activity. Also, a significant negative correlation (r=−0.74) between the lipid peroxide level and the Na⁺,-K⁺-ATPase activity was found in these cases.     

A novel microfluidic platform for studying mammalian cell chemotaxis in different oxygen environments under zero-flow conditions

The cell''s micro-environment plays an important role in various physiological and pathological phenomena. To better investigate in vivo cellular behaviors, researchers have expended great effort in building controlled in vitro biophysical and biochemical environments. Because a cell''s gaseous environment affects properties such as its division, metastasis, and differentiation, we developed a zero-flow based platform for studying mammalian cell chemotaxis behavior in different oxygen environments. This platform can construct a linear range of oxygen tensions within one chip (i.e., from 1.4% to 3.6% or 5.5% to 14.5%). To study cell chemotaxis behavior under varying oxygen environments, the chemical gradient direction is established perpendicularly to oxygen change within an observation area. Because the observation area is not subject to flow, shear force is of no concern. In addition, water flow around the cell chambers greatly reduces evaporation and makes long-term microscope imaging possible. In this study, we precisely measure the chemotaxis velocity of MCF-7 human breast cancer cells under different oxygen tension conditions towards CXCL12, which is a stromal cell-derived factor. We find that cell migration rates are not equivalent, even under two close oxygen tensions. We also observed that cells move faster towards high concentrations of chemoattractant when the oxygen tension is below 3% due to the increased expression of HIF-1 (hypoxia-inducible factor 1), which promotes a transition to the amoeboid rather than mesenchymal mode of movement. Our experiments demonstrate that this new microfluidic platform is useful for the quantitative study of mammalian cell chemotaxis under different oxygen conditions in the absence of shear force. We also shed light on the study of chemotaxis under other gaseous environments.