Figure 1 - available via license: Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported
Content may be subject to copyright.
Determination of pH by phenol red absorption. The concentration of phenol red was 0.1 mM and the path length was 0.62 cm in each case. ( A ) Absorption versus wavelength spectrum for the deprotonated ( pH = 11 ) and protonated ( pH = 3 ) forms of phenol red showing maximum absorbance at 550 and 435 nm, respectively. ( B ) Absorbance of phenol red at 562 nm ( o ) and 450 nm ( ^) as a function of pH. ( C ) Ratio of phenol red absorption, A( 562 nm ) / A( 450 nm ), as a function of pH. ( D ) Calibration of pH determination by comparing values from potentiometric and phenol red absorption pH determinations. R = 0.99 between pH values of 6.0 and 7.5 ( filled circles ).
Source publication
The tumor microenvironment is hypoxic and acidic. These conditions have a significant impact on tumor progression and response to therapies. There is strong evidence that tumor hypoxia results from inefficient perfusion due to a chaotic vasculature. Consequently, some tumor regions are well oxygenated and others are hypoxic. It is commonly believed...
Contexts in source publication
Context 1
... production rates were measured by monitoring the optical absorbance of phenol red at two wavelengths in the buffer solution overlying the cell monolayers in 96 -well plates, similar to that described previously [ 31 ]. The absorbance spectra for phenol red at low and high pH are shown in Figure 1A, showing maxima at 435 and 550 nm, respectively, with isosbestic points at 369 and 482 nm. From these data, it can be seen that absorbance changes reciprocally between pH 6 and 10 at 450 and 562 nm ( Figure 1B ). ...
Context 2
... absorbance spectra for phenol red at low and high pH are shown in Figure 1A, showing maxima at 435 and 550 nm, respectively, with isosbestic points at 369 and 482 nm. From these data, it can be seen that absorbance changes reciprocally between pH 6 and 10 at 450 and 562 nm ( Figure 1B ). These values were chosen to match the filter set available in the plate reader. ...
Context 3
... values were chosen to match the filter set available in the plate reader. Thus, the ratio of absorbance at 562 / 450 nm can be used to generate a titration curve ( Figure 1C ) that can be fitted by: ...
Context 4
... 10.5 is the ratio at high pH and 0.38 is a correction factor representing the ratio of absorbance at high to low pH at the denominator wavelength ( 450 nm ). The reliability of this method is shown in Figure 1D, which shows the correlation ( r 2 > 0.99 ) between the pH meas- ured by phenol red and by electrode in the pH range 6.0 to 7.5. At the time of an experiment, an aliquot of glucose -MHB was thawed and dilutions were made with mannitol -MHB to various glucose concentrations with a total osmotically active sugar concentration of 40 mM. ...
Citations
... , " ?, ( ! , "34 ), ( !34 , " ), and ( !34 , "34 ) surrounding the cell. The total cell oxygenation level in this case is defined by Eq. (16). ...
A hybrid off-lattice agent-based model has been developed to reconstruct the tumor tissue oxygenation landscape based on histology images and simulated interactions between vasculature and cells with microenvironment metabolites. Here, we performed a robustness sensitivity analysis of that model's physical and computational parameters. We found that changes in the domain boundary conditions, the initial conditions, and the Michaelis constant are negligible and, thus, do not affect the model outputs. The model is also not sensitive to small perturbations of the vascular influx or the maximum consumption rate of oxygen. However, the model is sensitive to large perturbations of these parameters and changes in the tissue boundary condition, emphasizing an imperative aim to measure these parameters experimentally.
... The tumor microenvironment (TME) is characterized by a complex environment, where tumor cells gain a growth advantage through aerobic glycolysis or the "Warburg effect" [2]. Consequently, this leads to increased pericellular accumulation of organic acids, such as lactic acid, and decreased extracellular pH [3]. Additionally, Adenosine triphosphate (ATP) is released during local tumor cell death caused by oxygen and nutrient deprivation [4], which is then catalyzed by CD73 and CD39 on various cells to produce adenosine [5]. ...
Aims: This study aims to investigate the impact of lactate and adenosine, present in the tumor microenvironment (TME), on the immune cell immunity. Methodology: Five groups included Adenosine concentration screening groups, L-lactic acid and Sodium L-lactate concentration groups, Adenosine + L-lactic acid and Adenosine + sodium L-lactate concentration groups were chosen to evaluate the NK92 cell functions. The proliferation ability and morphological observations of NK92 cells were assessed using a hemocytometer. The CCK-8 assay measured the inhibition of NK92 cell activity in the treatment group, while the crystal violet method evaluated the effect of NK92 cells on the killing ability of A549 cells. Results: A concentration of 50 μM adenosine served as a reference for high adenosine experimental concentrations, demonstrating a significant impact on NK92 immune cells within the TME. The functional entity "lactic acid" revealed independent effects of lactate [La-] and hydrogen ions [H+]. Lactate enhanced cell viability but reduced NK92 cytotoxicity. Conversely, lactic acid containing hydrogen ions caused a sharp decrease in cell viability and cytotoxicity to tumor cells. Conclusion: Elevated adenosine concentration and acidification of the tumor microenvironment significantly inhibit the ability of NK cells to kill tumor cells.
... Briefly speaking, the extracellular pH of cancer cells is usually 0.5 pH units less than normal cells [9][10][11][12]. Generally, if the pH remains below 7.1, then the normal cells begin to die due to a dependent apoptosis pathway which facilitates the tumor invasion [13][14][15]. Based on these facts and other results from the literature [4], Gatenby and Gawlinski [16] proposed the first mathematical model for acid-mediated tumor invasion. ...
Tumor invasion follows a complex mechanism which involves cell migration and proliferation. To study the processes in which primary and secondary metastases invade and damage the normal cells, mathematical models are often extremely useful. In this manuscript, we present a mathematical model of acid-mediated tumor growth consisting of radially symmetric reaction-diffusion equations. The assumption on the radial symmetry of the solutions is imposed here in view that tumors present spherical symmetry at the microscopic level. Moreover, we consider various empirical mechanisms which describe the propagation of tumors by considering cancer cells, normal cells, and the concentration of H + ions. Among other assumptions, we suppose that these components follow logistic-type growth rates. Evidently, this is an important difference with respect to various other mathematical models for tumor growth available in the literature. Moreover, we also add competition terms of normal and tumor cells growth. We carry out a balancing study of the equations of the model, and a numerical model is proposed to produce simulations. Various practical remarks derived from our assumptions are provided in the discussion of our the simulations. Response to Reviewers: % In LaTeX format. Please, compile the file. \documentclass[letterpaper,10pt]{article} \usepackage{color} \usepackage{amssymb} \setlength{\leftmargini}{0.3in} % \setlength{\parindent}{0.5in} % \setlength{\topmargin}{-0.75in} % Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation
... where V max = 0.05 mol/(m 3 •s) [40] is the maximum consumption rate, K m = 2 mol/m 3 [40] is the Michaelis-Menten constant, and I is a Boolean indicator that takes on the value of 1 or 0 for lattice points that may or may not contain a cell. Because, in our model, two different cell phenotypes (active and starved, see subsequent section) able to consume glucose can occupy LPs, the indicator I in Equation (6) is calculated as the sum of two Dirac delta functions, one for each cell phenotype: ...
... where V max = 0.05 mol/(m 3 •s) [40] is the maximum consumption rate, K m = 2 mol/m 3 [40] is the Michaelis-Menten constant, and I is a Boolean indicator that takes on the value of 1 or 0 for lattice points that may or may not contain a cell. Because, in our model, two different cell phenotypes (active and starved, see subsequent section) able to consume glucose can occupy LPs, the indicator I in Equation (6) is calculated as the sum of two Dirac delta functions, one for each cell phenotype: ...
Simple Summary
In recent years, mathematical models have revolutionized cancer research, illuminating the complex dynamics of tumor growth and aiding drug development. These models, reflecting biological and physical processes, are increasingly used in clinical practice, offering precise patient-specific predictions. Our work introduces an innovative in silico model to simulate tumor growth and invasiveness. The automated hybrid cell, replicating key tumor cell features, enables exploration of 3D tumor spheroid evolution. Sensitivity analyses reveal that tumor growth is primarily influenced by cell replication speed and adhesion, while invasiveness relies on chemotaxis. These insights shed light on tumor development mechanisms, guiding effective strategies against tumor progression. Our model serves as a valuable tool for advancing cancer biology research and potential therapeutic interventions.
Abstract
Purpose: In recent years, mathematical models have become instrumental in cancer research, offering insights into tumor growth dynamics, and guiding the development of pharmacological strategies. These models, encompassing diverse biological and physical processes, are increasingly used in clinical settings, showing remarkable predictive precision for individual patient outcomes and therapeutic responses. Methods: Motivated by these advancements, our study introduces an innovative in silico model for simulating tumor growth and invasiveness. The automated hybrid cell emulates critical tumor cell characteristics, including rapid proliferation, heightened motility, reduced cell adhesion, and increased responsiveness to chemotactic signals. This model explores the potential evolution of 3D tumor spheroids by manipulating biological parameters and microenvironment factors, focusing on nutrient availability. Results: Our comprehensive global and local sensitivity analysis reveals that tumor growth primarily depends on cell duplication speed and cell-to-cell adhesion, rather than external chemical gradients. Conversely, tumor invasiveness is predominantly driven by chemotaxis. These insights illuminate tumor development mechanisms, providing vital guidance for effective strategies against tumor progression. Our proposed model is a valuable tool for advancing cancer biology research and exploring potential therapeutic interventions.
... Our proposed model is 38 a valuable tool for advancing cancer biology research and exploring potential therapeutic interven-39 tions. 40 ...
... )[40] is the maximum consumption rate, = 243 2 mol m 3 ⁄[40] is the Michaelis-Menten constant, and I is a Boolean indicator that takes on 244 the value of 1 or 0 for lattice points that contain or not a cell. Because in our model two 245 different cell phenotype (active and starved, see next section) able to consume glucose can 246 occupy LPs, the indicator I in Equation 6 is calculated as the sum of two Dirac delta func-247 tions, one for each cell phenotypexact, yact) and (xstar, ystarv) are the coordinates of the LPs where active and starv-252 ing cells are located. ...
... )[40] is the maximum consumption rate, = 243 2 mol m 3 ⁄[40] is the Michaelis-Menten constant, and I is a Boolean indicator that takes on 244 the value of 1 or 0 for lattice points that contain or not a cell. Because in our model two 245 different cell phenotype (active and starved, see next section) able to consume glucose can 246 occupy LPs, the indicator I in Equation 6 is calculated as the sum of two Dirac delta func-247 tions, one for each cell phenotypexact, yact) and (xstar, ystarv) are the coordinates of the LPs where active and starv-252 ing cells are located. ...
Purpose: In recent years, mathematical models have become instrumental in cancer research, offering insights into tumor growth dynamics, and guiding the development of pharmacological strategies. These models, encompassing diverse biological and physical processes, are increasingly used in clinical settings, showing remarkable predictive precision for individual patient outcomes and therapeutic responses. Methods: Motivated by these advancements, our study introduces an innovative in silico model for simulating tumor growth and invasiveness. The Automated Hybrid Cell emulates critical tumor cell characteristics, including rapid proliferation, heightened motility, reduced cell adhesion, and increased responsiveness to chemotactic signals. This model explores the potential evolution of 3D tumor spheroids by manipulating biological parameters and microenvironment factors, focusing on nutrient availability. Results: Our comprehensive Global and Local Sensitivity Analyses reveal that tumor growth primarily depends on cell duplication speed and cell-to-cell adhesion, rather than external chemical gradients. Conversely, tumor invasiveness is predominantly driven by chemotaxis. These insights illuminate tumor development mechanisms, providing vital guidance for effective strategies against tumor progression. Our proposed model is a valuable tool for advancing cancer biology research and exploring potential therapeutic interven-tions.
... Tumor metabolism is characterized by anaerobic glycolysis since cancer cells preferentially convert the glycolysis-induced pyruvate into lactic acid even in the presence of oxygen [59], resulting in elevated pericellular accumulation of organic acids, such as lactic acid, and low pyruvate status [81]. Our results also suggest a lower level of pyruvic acid in prostate cancer plasma samples if compared to healthy controls; however, contrary to our expectations, in our study, the levels of lactic acid were 56% lower in prostate cancer patients than in the healthy controls. ...
An oxidative degradation product of the polyunsaturated fatty acids, 4-hydroxynonenal (4-HNE), is of particular interest in cancer research due to its concentration-dependent pleiotropic activities affecting cellular antioxidants, metabolism, and growth control. Although an increase in oxidative stress and lipid peroxidation was already associated with prostate cancer progression a few decades ago, the knowledge of the involvement of 4-HNE in prostate cancer tumorigenesis is limited. This study investigated the appearance of 4-HNE-protein adducts in prostate cancer tissue by immunohistochemistry using a genuine 4-HNE monoclonal antibody. Plasma samples of the same patients and samples of the healthy controls were also analyzed for the presence of 4-HNE-protein adducts, followed by metabolic profiling using LC-ESI-QTOF-MS and GC-EI-Q-MS. Finally, the analysis of the metabolic pathways affected by 4-HNE was performed. The obtained results revealed the absence of 4-HNE-protein adducts in prostate carcinoma tissue but increased 4-HNE-protein levels in the plasma of these patients. Metabolomics revealed a positive association of different long-chain and medium-chain fatty acids with the presence of prostate cancer. Furthermore, while linoleic acid positively correlated with the levels of 4-HNE-protein adducts in the blood of healthy men, no correlation was obtained for cancer patients indicating altered lipid metabolism in this case. The metabolic pathway of unsaturated fatty acids biosynthesis emerged as significantly affected by 4-HNE. Overall, this is the first study linking 4-HNE adduction to plasma proteins with specific alterations in the plasma metabolome of prostate cancer patients. This study revealed that increased 4-HNE plasma protein adducts could modulate the unsaturated fatty acids biosynthesis pathway. It is yet to be determined if this is a direct result of 4-HNE or whether they are produced by the same underlying mechanisms. Further mechanistic studies are needed to grasp the biological significance of the observed changes in prostate cancer tumorigenesis.
... Inclusion criteria included menopause for at least 12 consecutive months, habitation in Tabriz, ability to communicate verbally to answer questions, and no history of pathological fractures during the past 10 years. Exclusion criteria included body mass index (BMI) less than 18.5, postmenopausal women under 40 years, vitamin D deficiency (<20 ng/ml), hypocalcemia, inherited diseases (hemophilia, thalassemia, hemochromatosis), use of hormonal drugs or corticosteroids during the study, drugs affecting bone metabolism including intravenous use of bisphosphonates in the last 5 years, use of oral bisphosphonates in the last 6 months, excessive use of oral bisphosphonates for more than 3 years or more than 1 month between 6 and 12 months before the study, use of parathyroid hormone analogs during the previous 12 months, renal failure, gastrointestinal diseases (such as complete gastric lavage, Crohn's disease, primary biliary cirrhosis, gastric surgery, celiac disease), bone disease other than osteoporosis, metastatic bone disease, and malignancy (Schornack & Gillies, 2003). ...
Abstract This study aimed to investigate the association between dietary acid load (DAL) and primary osteoporosis. This was a cross‐sectional study. Among 850 randomly selected postmenopausal women aged 50–65 years, 232 women consisted of 124 women with normal bone mineral density (BMD) and 108 with primary osteoporosis were selected after examining the eligibility criteria. Demographic characteristics, anthropometric indices, and physical activity were collected through questionnaires. Osteoporosis was diagnosed using the dual‐energy X‐ray absorptiometry method. DAL was assessed by a valid and reliable semiquantitative food frequency questionnaire during the last year. Independent t‐test, Mann–Whitney, Chi‐square, and adjusted binary logistic regression were used for data analysis through SPSS/24. There were significant differences between the two groups in terms of age, body mass index (BMI), number of deliveries, and years after menopause (p
... Cancer cells undergo significant metabolic reorganization during disease progression, tailored to their energy demands and fluctuating environmental conditions. Indeed, a series of metabolic changes occur during tumor development that favors its growth, including (i) increased glycolysis, decreased activity of the Krebs cycle, and acidification of the interstitium due to the release of lactate [46,47]. (ii) Cancer cells show increased glutamine and other amino acid utilization [48]. ...
Metabolic changes that facilitate tumor growth are one of the hallmarks of cancer. These changes are not specific to tumors but also take place during the physiological growth of tissues. Indeed, the cellular and tissue mechanisms present in the tumor have their physiological counterpart in the repair of tissue lesions and wound healing. These molecular mechanisms have been acquired during metazoan evolution, first to eliminate the infection of the tissue injury, then to enter an effective regenerative phase. Cancer itself could be considered a phenomenon of antagonistic pleiotropy of the genes involved in effective tissue repair. Cancer and tissue repair are complex traits that share many intermediate phenotypes at the molecular, cellular, and tissue levels, and all of these are integrated within a Systems Biology structure. Complex traits are influenced by a multitude of common genes, each with a weak effect. This polygenic component of complex traits is mainly unknown and so makes up part of the missing heritability. Here, we try to integrate these different perspectives from the point of view of the metabolic changes observed in cancer.
... The ramp up of glycolysis where glucose is converted to lactate, otherwise known as aerobic glycolysis or the "Warburg effect" [26], is a characteristic shared by many proliferating cells including cancer cells [27]. Increased glycolysis leads to the secretion of protons and lactate rendering the surroundings of the cells more acidic [28]. The increased glycolysis and its concurrent extra-cellular acidification upon activation presents a unique handle for the early isolation of activated T-cells. ...
A label-free, fixation-free and passive sorting method is presented to isolate activated T-cells shortly after activation and prior to the display of activation surface markers. It uses a recently developed sorting platform dubbed “Sorting by Interfacial Tension” (SIFT) that sorts droplets based on pH. After polyclonal (anti-CD3/CD28 bead) activation and a brief incubation on chip, droplets containing activated T-cells display a lower pH than those containing naive cells due to increased glycolysis. Under specific surfactant conditions, a change in pH can lead to a concurrent increase in droplet interfacial tension. The isolation of activated T-cells on chip is hence achieved as flattened droplets are displaced as they encounter a micro-fabricated trench oriented diagonally with respect to the direction of flow. This technique leads to an enrichment of activated primary CD4+ T-cells to over 95% from an initial mixed population of naive cells and cells activated for as little as 15 min. Moreover, since the pH change is correlated to successful activation, the technique allows the isolation of T-cells with the earliest activation and highest glycolysis, an important feature for the testing of T-cell activation modulators and to determine regulators and predictors of differentiation outcomes.
... We already know that PSA on the extracellular side of cancer cells favors metastases [39], and that hypoxia stimulates the migration of GBM cells [8,42]. One possible explanation for this apparent contradictory situation is that hypoxic microenvironments cause a change of the extracellular pH, which in turn alters extracellular charges [43,44]. It therefore becomes plausible to speculate that in conditions of low oxygen concentrations PSA expression needs to be elevated and confined inside the cell for an energetic and/or electrostatically reason, giving advantage to GBM cells. ...
Gliomas are the most common primary malignant brain tumors. Glioblastoma, IDH-wildtype (GBM, CNS WHO grade 4) is the most aggressive form of glioma and is characterized by extensive hypoxic areas that strongly correlate with tumor malignancy. Hypoxia promotes several processes, including stemness, migration, invasion, angiogenesis, and radio- and chemoresistance, that have direct impacts on treatment failure. Thus, there is still an increasing need to identify novel targets to limit GBM relapse. Polysialic acid (PSA) is a carbohydrate composed of a linear polymer of α2,8-linked sialic acids, primarily attached to the Neural Cell Adhesion Molecule (NCAM). It is considered an oncodevelopmental antigen that is re-expressed in various tumors. High levels of PSA-NCAM are associated with high-grade and poorly differentiated tumors. Here, we investigated the effect of PSA inhibition in GBM cells under low oxygen concentrations. Our main results highlight the way in which hypoxia stimulates polysialylation in U87-MG cells and in a GBM primary culture. By lowering PSA levels with the sialic acid analog, F-NANA, we also inhibited GBM cell migration and interfered with their differentiation influenced by the hypoxic microenvironment. Our findings suggest that PSA may represent a possible molecular target for the development of alternative pharmacological strategies to manage a devastating tumor like GBM.
