Expression and regulation of alkaline phosphatases in human breast cancer MCF-7 cells

Identifying alkaline phosphatase inhibitory potential of cyclooxygenase-2 inhibitors: Insights from molecular docking, MD simulations, molecular expression analysis in MCF-7 breast cancer cell line and in vitro investigations

Alkaline phosphatases (APs, EC 3.1.3.1) belong to a superfamily of biological macromolecules that dephosphorylate many phosphometabolites and phosphoproteins and their overexpression is intricated in the spread of cancer to liver and bones, neuronal disorders including Alzheimer's disease (AD), inflammation and others. It was hypothesized that cyclooxygenase-2 (COX-2) selective inhibitors may possess anti-APs potential and may be involved in anticancer proceedings. Three COX-2 inhibitors including nimesulide, piroxicam and lornoxicam were evaluated for the inhibition of APs using in silico and in vitro methods. Molecular docking studies against tissue nonspecific alkaline phosphatase (TNAP) offered the best binding affinities for nimesulide (-11.14 kcal/mol) supported with conventional hydrogen bonding and hydrophobic interactions. MD simulations against TNAP for 200 ns and principal component analysis (PCA) reiterated the stability of ligand-receptor complexes. Molecular expression analysis of TNAP enzyme in the breast cancer cell line MCF-7 exhibited 0.24-fold downregulation with 5 μM nimesulide as compared with 0.26-fold standard 10 μM levamisole. In vitro assays against human placental AP (hPAP) displayed potent inhibitions of these drugs with IC50 values of 0.52 ± 0.02 μM to 3.46 ± 0.13 μM and similar results were obtained for bovine intestinal AP (bIAP). The data when generalized collectively emphasizes that the inhibition of APs by COX-2 inhibitors provides another target to work on the development of anticancer drugs.

A Strategy for the Determination of Alkaline Phosphatase Based on the Self-Triggered Degradation of Metal-Organic Frameworks by Phosphate

Alkaline phosphatase (ALP) is widely present in the human body and is an important biomarker. Numerous ALP detection studies have been carried out, and ascorbic acid (AA) is often used as the reducing component in the sensors to monitor ALP levels since it can be produced from ascorbic acid 2-phosphate (AA2P) hydrolysis in the presence of ALP. However, it is well-known that AA is a strong reducing agent and can be easily oxidized. The disproportion between oxidized AA and reduced AA reactions results in the generation of AA free radicals with single electrons that may lead to inaccurate results in assays. To solve this problem, we synthesized a core-shell metal-organic framework sensor (PATP-Au@ZIF-8 NP) and used it as a sensitive and accurate ALP detection sensor with self-triggered control of phosphate ions (Pi) to avoid the potential inaccuracy of the method that uses AA as the reducing component. By establishing a physical shell on the surface of the gold nanoparticles (Au NPs), the sensor not only can eliminate the random assembly of metal nanoparticles caused by plasma exposure but also can generate self-triggering of Pi caused by ALP. Pi can decompose ZIF-8 through coordination with Zn²⁺ and thus can destroy the ZIF-8 shell structure of the prepared PAZ NPs. Au NPs are released and then become aggregated, in turn causing the SERS "hot spot" area to increase. The enhancement of the SERS signals was found to be directly associated with the level of Pi released from ALP-triggered hydrolysis. The response of the strategy was linear at ALP concentrations ranging from 0.1 to 150 mU/mL (r = 0.996) with a detection limit of 0.03 mU/mL. Lastly, the developed strategy was employed in the evaluation of ALP inhibitors, and the possibility to implement the developed SERS strategy for rapid and selective analysis of ALP in human serum was demonstrated.

In situ reaction-based ratiometric fluorescent assay for alkaline phosphatase activity and bioimaging

Alkaline phosphatase (ALP) is an important biomarker, it is of great significance to develop a sensitive and efficient analytical method for ALP. In this study, an in situ reaction based ratiometric fluorescence assay for ALP was proposed. l-ascorbic acid-2-phosphate (AA2P) was used as a substrate for ALP, and Cu²⁺/o-phenylenediamine (OPD) were involved in this system. Cu²⁺ can oxidize OPD to 2,3-diaminophenazine (OPDox) with an emission centered at 566 nm. The presence of ALP can catalyze the hydrolysis of AA2P to ascorbic acid (AA), which will inhibit the production of OPDox and reduce the corresponding fluorescence intensity, and AA will react with OPD to generate 3-(dihydroxyethyl)furan[3,4-b]quinoxalin-1-one (DFQ) with an emission peak at 447 nm. The fluorescence ratio of F447/F566 has a linear relationship with ALP activity. The proposed method is highly sensitive, finely selective, cost efficiency and easy to operate, it exhibits good linearity in the range of 0.5-22 and 22-40 mU·mL^-1, with a detection limit as low as 0.06 mU·mL^-1. The excellent applicability of this strategy in human serum samples and MCF-7 cells imaging suggests that this method has promising prospects for biomedical research.

Design, Synthesis, and Biological Evaluation of Novel Dihydropyridine and Pyridine Analogs as Potent Human Tissue Nonspecific Alkaline Phosphatase Inhibitors with Anticancer Activity: ROS and DNA Damage-Induced Apoptosis

Small molecules with nitrogen-containing scaffolds have gained much attention due to their biological importance in the development of new anticancer agents. The present paper reports the synthesis of a library of new dihydropyridine and pyridine analogs with diverse pharmacophores. All compounds were tested against the human tissue nonspecific alkaline phosphatase (h-TNAP) enzyme. Most of the compounds showed excellent enzyme inhibition against h-TNAP, having IC₅₀ values ranging from 0.49 ± 0.025 to 8.8 ± 0.53 µM, which is multi-fold higher than that of the standard inhibitor (levamisole = 22.65 ± 1.60 µM) of the h-TNAP enzyme. Furthermore, an MTT assay was carried out to evaluate cytotoxicity against the HeLa and MCF-7 cancer cell lines. Among the analogs, the most potent dihydropyridine-based compound 4d was selected to investigate pro-apoptotic behavior. The further analysis demonstrated that compound 4d played a significant role in inducing apoptosis through multiple mechanisms, including overproduction of reactive oxygen species, mitochondrial dysfunction, DNA damaging, and arrest of the cell cycle at the G1 phase by inhibiting CDK4/6. The apoptosis-inducing effect of compound 4d was studied through staining agents, microscopic, and flow cytometry techniques. Detailed structure–activity relationship (SAR) and molecular docking studies were carried out to identify the core structural features responsible for inhibiting the enzymatic activity of the h-TNAP enzyme. Moreover, fluorescence emission studies corroborated the binding interaction of compound 4d with DNA through a fluorescence titration experiment.

Intestinal Alkaline Phosphatase: A Review of This Enzyme Role in the Intestinal Barrier Function

Intestinal alkaline phosphatase (IALP) has recently assumed a special relevance, being the subject of study in the prevention and treatment of certain diseases related to leaky gut. This brush border enzyme (ecto-enzyme) plays an important role in the maintenance of intestinal microbial homeostasis and intestinal barrier function through its ability to dephosphorylate lipopolysaccharide (LPS). This review addresses how IALP and intestinal barrier dysfunction may be implicated in the pathophysiology of specific diseases such as inflammatory bowel disease, necrotizing enterocolitis, and metabolic syndrome. The use of IALP as a possible biomarker to assess intestinal barrier function and strategies to modulate IALP activity are also discussed.

The activity of alkaline phosphatase in breast cancer exosomes simplifies the biosensing design

This work addresses a biosensor combining the immunomagnetic separation and the electrochemical biosensing based on the intrinsic ALP activity of the exosomes. This approach explores for the first time two different types of biomarkers on exosomes, in a unique biosensing device combining two different biorecognition reaction: immunological and enzymatic. Besides, the intrinsic activity of alkaline phosphatase (ALP) in exosomes as a potential biomarker of carcinogenesis as well as osseous metastatic invasion is also explored. To achieve that, as an in vitro model, exosomes from human fetal osteoblasts are used. It is demonstrated that the electrochemical biosensor improves the analytical performance of the gold standard colorimetric assay for the detection of ALP activity in exosomes, providing a limit of detection of 4.39 mU L^-1, equivalent to 10⁵ exosomes μL^-1. Furthermore, this approach is used to detect and quantify exosomes derived from serum samples of breast cancer patients. The electrochemical biosensor shows reliable results for the differentiation of healthy donors and breast cancer individuals based on the immunomagnetic separation using specific epithelial biomarkers CD326 (EpCAM) combined with the intrinsic ALP activity electrochemical readout.

Metabolic Features of Saliva in Breast Cancer Patients

The aim of the work was to study the metabolic characteristics of saliva in breast cancer and the subsequent assessment of the potential information content of its individual biochemical indicators. The study included 487 patients of the Omsk Clinical Oncology Center with morphologically verified breast cancer and 298 volunteers without breast pathologies. Saliva samples were obtained from all patients before the start of treatment, and the values of 34 biochemical indicators were determined. It has been shown that concentration of total protein, urea, uric acid (UA), the total content of α-amino acids and lipid peroxidation products, and the activity of metabolic and antioxidant enzymes (in particular catalase—CAT) of saliva changed significantly in breast cancer. Biochemical indicators characterizing early breast cancer have been identified, which can be used for timely diagnosis in addition to existing methods. The coefficients UA/Urea and UA·CAT/Urea are proposed, for which the maximum deviation from the norm was observed in the early stages of the disease. It was shown that for ductal breast cancer, changes in the activity of metabolic enzymes of saliva were more pronounced, while, for lobular breast cancer, the indicators of enzymatic and non-enzymatic components of antioxidant protection changed. The results confirmed the potential importance of saliva in the diagnosis of breast cancer.

Azomethine-clubbed thiazoles as human tissue non-specific alkaline phosphatase (h-TNAP) and intestinal alkaline phosphatase (h-IAP) Inhibitors: kinetics and molecular docking studies

Thiazole derivatives are known inhibitors of alkaline phosphatase, but various side effects have reduced their curative efficacy. Conversely, compounds bearing azomethine linkage display a broad spectrum of biological applications. Therefore, combining the two scaffolds in a single structural unit should result in joint beneficial effects of both. A new series of azomethine-clubbed thiazoles (3a-i) was synthesized and appraised for their inhibitory potential against human tissue non-specific alkaline phosphatase (h-TNAP) and human intestinal alkaline phosphatase (h-IAP). Compounds 3c and 3f were found to be most potent compounds toward h-TNAP with IC₅₀ values of 0.15 ± 0.01 and 0.50 ± 0.01 µM, respectively, whereas 3a and 3f exhibited maximum potency for h-IAP with IC₅₀ value of 2.59 ± 0.04 and 2.56 ± 0.02 µM, respectively. Molecular docking studies were also performed to find the type of binding interaction between potential inhibitor and active sites of enzymes. The enzymes inhibition kinetics studies were carried out to define the mechanism of enzyme inhibition. The current study leads to discovery of some potent inhibitors of alkaline phosphatase that is promising toward identification of compounds with druggable properties.

Near-infrared (NIR) fluorescence-emitting small organic molecules for cancer imaging and therapy

We discuss recent advances made in the development of NIR fluorescence-emitting small organic molecules for tumor imaging and therapy.

Monitoring protein conformational changes using fluorescent nanoantennas

Understanding the relationship between protein structural dynamics and function is crucial for both basic research and biotechnology. However, methods for studying the fast dynamics of structural changes are limited. Here, we introduce fluorescent nanoantennas as a spectroscopic technique to sense and report protein conformational changes through noncovalent dye-protein interactions. Using experiments and molecular simulations, we detect and characterize five distinct conformational states of intestinal alkaline phosphatase, including the transient enzyme-substrate complex. We also explored the universality of the nanoantenna strategy with another model protein, Protein G and its interaction with antibodies, and demonstrated a rapid screening strategy to identify efficient nanoantennas. These versatile nanoantennas can be used with diverse dyes to monitor small and large conformational changes, suggesting that they could be used to characterize diverse protein movements or in high-throughput screening applications.

Immunosuppressive metabolites in tumoral immune evasion: redundancies, clinical efforts, and pathways forward

Tumors accumulate metabolites that deactivate infiltrating immune cells and polarize them toward anti-inflammatory phenotypes. We provide a comprehensive review of the complex networks orchestrated by several of the most potent immunosuppressive metabolites, highlighting the impact of adenosine, kynurenines, prostaglandin E2, and norepinephrine and epinephrine, while discussing completed and ongoing clinical efforts to curtail their impact. Retrospective analyses of clinical data have elucidated that their activity is negatively associated with prognosis in diverse cancer indications, though there is a current paucity of approved therapies that disrupt their synthesis or downstream signaling axes. We hypothesize that prior lukewarm results may be attributed to redundancies in each metabolites' synthesis or signaling pathway and highlight routes for how therapeutic development and patient stratification might proceed in the future.

Oral acute and sub-chronic toxicity assessment of aqueous leaf extract of Simarouba glauca DC (Paradise tree)

Simarouba glauca has been widely reported to be effective against a number of diseases and possesses medicinal benefits. Thus, the study was conducted to evaluate the toxic effect of aqueous leaf extract of Simarouba glauca (AESG) on relevant organs of male Wistar rats. The oral acute toxicity of AESG was evaluated according to the method described by Lorke. Sub-chronic toxicity of AESG was carried out in line with the guidelines of the Organization for Economic Co-operation and Development (OECD), using a total of twenty-four (24) male Wistar rats divided into four groups of six rats each. Test rats were orally administered AESG at doses of 500, 1000 and 2000 mg /kg body weight, respectively, daily for thirty (30) days. At the end of the study, rats were fasted overnight and sacrificed; the relevant biochemical and histopathology evaluation was carried out. Statistical analysis was conducted using the GraphPad Prism®, version 7. The data obtained indicated that the LD50 exceeded 5000 mg/kg. There were significant increases (P < 0.05) in percentage (%) body weight of test rats. There were no significant differences (P < 0.05) in mean liver, kidney, and heart weight/body weight (IOW/BWT) ratios. The AST activity was significantly lowered (P < 0.05) in rats administered AESG 2000 mg/kg. The ALP activities were significantly elevated (P < 0.05), while the GGT activities were significantly lowered (P < 0.05) in all groups of rats administered AESG. Plasma conjugated and unconjugated bilirubin were significantly lowered and elevated (P < 0.05), respectively in rats administered AESG 1000 and 2000 mg/kg. Plasma urea was significantly elevated (P < 0.05) in rats given AESG 1000 mg/kg. Test rats given AESG 2000 mg/kg recorded significant reduction (P < 0.05) in plasma sodium ions concentration. Rats given AESG 500 mg/kg recorded significant reduction (P < 0.05) in plasma bicarbonate ion levels. The findings suggest that AESG was not significantly toxic to the liver, kidney, and heart.

Single-Molecule Analysis Determines Isozymes of Human Alkaline Phosphatase in Serum

Alkaline phosphatase (ALP) is an important biomarker, as high levels of ALP in blood can indicate liver disease or bone disorders. However, current clinical blood tests only measure the total concentration of ALP but are unable to distinguish enzyme isotypes. Here, we demonstrate a novel and rapid approach to profile various ALP isozymes in blood via a single-molecule-analysis platform. The microarray platform provides enzyme kinetics of hundreds of individual molecules at high throughput. Using these single molecule kinetics, we characterize the different activity profiles of ALP isotypes. By analyzing both healthy and disease samples, we found the single molecule activity distribution of ALP in serum reflects the health status of patients. This result demonstrates the potential utility of the method for improving the conventional ALP test, as well as for analyzing other enzymatic biomarkers, including enzyme isotypes.

Resazurin-Based Assay for Quantifying Living Cells during Alkaline Phosphatase (ALP) Release

Alkaline phosphatase (ALP) is an important reporter gene in the gene expression system, therefore monitoring cellular behavior including cell viability during ALP release is of significance. This assay produced a quantitative resazurin-based assay for cell viability in embryonic and cancer cells during alkaline phosphatase (ALP) release. A post-confluence culture method was applied to induce ALP in the cells of Balb/c 3T3, A549, MCF-7, and Ht-29. The density of each cell type was optimized using the standard cell culture assay. The main parameters affecting the results of resazurin involve the concentration of resazurin, incubation time, and cell number. The redox reaction, in which resazurin is reduced by the cells, was measured by fluorescence at 544 nm and 590 nm. The obtained data were compared with the hemocytometer assay. ALP release was determined using the optical active substrate p-nitrophenyl phosphate and colorimetric assay.

Aptameric Probe Specifically Binding Protein Heterodimer Rather Than Monomers

Dimerization of proteins occurs frequently and plays integral roles in biological processes. However, no single molecular probe is available for in situ detection of protein dimers on cells and tissues because of the difficulty of isolating complete protein dimers for probe preparation and screening, which has greatly hampered the biomedical study of protein dimers. Herein, a G-rich DNA aptamer (termed BG2) that only binds alkaline phosphatase (AP) heterodimers rather than monomers is reported. This aptamer is generated by the cell-SELEX (systematic evolution of ligands by exponential enrichment) technique and proves to fold into a duplex stabilized antiparallel G-quadruplex structure. Using BG2 as molecular probe, AP heterodimers are found to be expressed on several kinds of cancer cells. As an affinity ligand, BG2 could isolate AP heterodimers from cell lysate. BG2 is also demonstrated to be applicable for tumor imaging in mice xenografted with cells highly expressing AP heterodimers. AP isozymes are found in several tissues and blood throughout the body, but the function and tissue distribution of AP heterodimers are totally unknown; therefore, BG2 could serve as a molecular probe to uncover the mystery of AP heterodimers. The generation of aptameric probes by cell-SELEX will open up a new situation for the study of protein dimers.

Three gold indicators for breast cancer prognosis: a case-control study with ROC analysis for novel ratios related to CBC with (ALP and LDH)

Science is still unable to develop a specific strategy for predicting breast cancer in humans. Several attempts are done to obtain the best and closest prognostic predictive biomarkers for breast cancer. The present study aimed to evaluate the impact of novel ratios calculated between the blood indices with CA15.3, alkaline phosphatase and lactate dehydrogenase as prognostic biomarkers in breast cancer. This study was conducted on two groups (Breast cancer Patients group in comparison to a control group who has no tumor family history). All the volunteers are subjected to the routine analysis included liver and kidney function tests, complete blood count with blood indices, tumor markers (CA15.3) assessment, alkaline phosphatase, and lactate dehydrogenase analysis. Thirty different ratios were calculated in the present research between blood indices and three inexpensive serum biomarkers; CA15.3, alkaline phosphatase and lactate dehydrogenase. Fifteen ratios of them were significant in breast cancer group than the control group. Three ratios (PDW/lymphocytes, MPV/lymphocytes, and ALP/RDW) of them gave a sensitivity of 100% with high specificity as indicators for breast cancer incidence. The correlation between significant ratios was very interesting. The more interesting was in the results of subgroup analysis which showed that the ALP/RDW ratio is more specific for pre-menopause while PDW/lymphocytes ratio is more specific for post-menopause. The ratios PDW/lymphocytes, MPV/lymphocytes, and ALP/RDW can be used as prognostic biomarkers in breast cancer patients. The interesting advantage in the results depends on the availability of these indicators in routine blood analysis and will not increase the cost of the diagnostic plan.

Alkaline Phosphatase Controls Lineage Switching of Mesenchymal Stem Cells by Regulating the LRP6/GSK3β Complex in Hypophosphatasia

Lineage differentiation of bone marrow mesenchymal stem cells (BMMSCs) is the key to bone-fat reciprocity in bone marrow. To date, the regulators of BMMSC lineage switching have all been identified to be transcription factors, and researchers have not determined whether other genes control this process. This study aims to reveal a previously unknown role of tissue-nonspecific alkaline phosphatase (TNSALP) in controlling BMMSC lineage selection.

Methods: We compared the characteristics of cultured BMMSCs from patients with hypophosphatasia (HPP), which is caused by mutations in the liver/bone/kidney alkaline phosphatase (ALPL) gene, and an ALPL knockout (ko) mouse model. We performed ALPL downregulation and overexpression experiments to investigate the regulatory role of ALPL in BMMSC lineage switching. Using the PathScan array, coimmunoprecipitation experiments and pathway-guided small molecule treatments, we explored the possible mechanism underlying the regulatory effects of ALPL on cell differentiation and evaluated its therapeutic effect on ALPL ko mice.

Results: BMMSCs from both patients with HPP and ALPL ko mice exhibited defective lineage differentiation, including a decrease in osteogenic differentiation and a parallel increase in adipogenic differentiation. Mechanistically, TNSALP directly interacted with LRP6 and regulated the phosphorylation of GSK3β, subsequently resulting in lineage switching of BMMSCs. Re-phosphorylation of GSK3β induced by LiCl treatment restored differentiation of BMMSCs and attenuated skeletal deformities in Alpl^+/- mice.

Conclusion: Based on our findings, TNSALP acts as a signal regulator to control lineage switching of BMMSCs by regulating the LRP6/GSK3β cascade.

Tumour-derived alkaline phosphatase regulates tumour growth, epithelial plasticity and disease-free survival in metastatic prostate cancer

BACKGROUND

Recent evidence suggests that bone-related parameters are the main prognostic factors for overall survival in advanced prostate cancer (PCa), with elevated circulating levels of alkaline phosphatase (ALP) thought to reflect the dysregulated bone formation accompanying distant metastases. We have identified that PCa cells express ALPL, the gene that encodes for tissue nonspecific ALP, and hypothesised that tumour-derived ALPL may contribute to disease progression.

METHODS

Functional effects of ALPL inhibition were investigated in metastatic PCa cell lines. ALPL gene expression was analysed from published PCa data sets, and correlated with disease-free survival and metastasis.

RESULTS

ALPL expression was increased in PCa cells from metastatic sites. A reduction in tumour-derived ALPL expression or ALP activity increased cell death, mesenchymal-to-epithelial transition and reduced migration. Alkaline phosphatase activity was decreased by the EMT repressor Snail. In men with PCa, tumour-derived ALPL correlated with EMT markers, and high ALPL expression was associated with a significant reduction in disease-free survival.

CONCLUSIONS

Our studies reveal the function of tumour-derived ALPL in regulating cell death and epithelial plasticity, and demonstrate a strong association between ALPL expression in PCa cells and metastasis or disease-free survival, thus identifying tumour-derived ALPL as a major contributor to the pathogenesis of PCa progression.

Two New Faces of Amifostine: Protector from DNA Damage in Normal Cells and Inhibitor of DNA Repair in Cancer Cells

Amifostine protects normal cells from DNA damage induction by ionizing radiation or chemotherapeutics, whereas cancer cells typically remain uninfluenced. While confirming this phenomenon, we have revealed by comet assay and currently the most sensitive method of DNA double strand break (DSB) quantification (based on γH2AX/53BP1 high-resolution immunofluorescence microscopy) that amifostine treatment supports DSB repair in γ-irradiated normal NHDF fibroblasts but alters it in MCF7 carcinoma cells. These effects follow from the significantly lower activity of alkaline phosphatase measured in MCF7 cells and their supernatants as compared with NHDF fibroblasts. Liquid chromatography-mass spectrometry confirmed that the amifostine conversion to WR-1065 was significantly more intensive in normal NHDF cells than in tumor MCF cells. In conclusion, due to common differences between normal and cancer cells in their abilities to convert amifostine to its active metabolite WR-1065, amifostine may not only protect in multiple ways normal cells from radiation-induced DNA damage but also make cancer cells suffer from DSB repair alteration.

Cardiac and skeletal muscles show molecularly distinct responses to cancer cachexia

Cancer cachexia is a systemic, paraneoplastic syndrome seen in patients with advanced cancer. There is growing interest in the altered muscle pathophysiology experienced by cachectic patients. This study reports the microarray analysis of gene expression in cardiac and skeletal muscle in the colon 26 (C26) carcinoma mouse model of cancer cachexia. A total of 268 genes were found to be differentially expressed in cardiac muscle tissue, compared with nontumor-bearing controls. This was fewer than the 1,533 genes that changed in cachectic skeletal muscle. In addition to different numbers of genes changing, different cellular functions were seen to change in each tissue. The cachectic heart showed signs of inflammation, similar to cachectic skeletal muscle, but did not show the upregulation of ubiquitin-dependent protein catabolic processes or downregulation of genes involved in cellular energetics and muscle regeneration that characterizes skeletal muscle cachexia. Quantitative PCR was used to investigate a subset of inflammatory genes in the cardiac and skeletal muscle of independent cachectic samples; this revealed that B4galt1, C1s, Serpina3n, and Vsig4 were significantly upregulated in cardiac tissue, whereas C1s and Serpina3n were significantly upregulated in skeletal tissue. Our skeletal muscle microarray results were also compared with those from three published microarray studies and found to be consistent in terms of the genes differentially expressed and the functional processes affected. Our study highlights that skeletal and cardiac muscles are affected differently in the C26 mouse model of cachexia and that therapeutic strategies cannot assume that both muscle types will show a similar response.

Estrogenicity of glabridin in Ishikawa cells

Glabridin is an isoflavan from licorice root, which is a common component of herbal remedies used for treatment of menopausal symptoms. Past studies have shown that glabridin resulted in favorable outcome similar to 17β-estradiol (17β-E₂), suggesting a possible role as an estrogen replacement therapy (ERT). This study aims to evaluate the estrogenic effect of glabridin in an in-vitro endometrial cell line -Ishikawa cells via alkaline phosphatase (ALP) assay and ER-α-SRC-1-co-activator assay. Its effect on cell proliferation was also evaluated using Thiazoyl blue tetrazolium bromide (MTT) assay. The results showed that glabridin activated the ER-α-SRC-1-co-activator complex and displayed a dose-dependent increase in estrogenic activity supporting its use as an ERT. However, glabridin also induced an increase in cell proliferation. When glabridin was treated together with 17β-E₂, synergistic estrogenic effect was observed with a slight decrease in cell proliferation as compared to treatment by 17β-E₂ alone. This suggest that the combination might be better suited for providing high estrogenic effects with lower incidences of endometrial cancer that is associated with 17β-E₂.

Alkaline phosphatase: an overview

Alkaline phosphatase (ALP; E.C.3.I.3.1.) is an ubiquitous membrane-bound glycoprotein that catalyzes the hydrolysis of phosphate monoesters at basic pH values. Alkaline phosphatase is divided into four isozymes depending upon the site of tissue expression that are Intestinal ALP, Placental ALP, Germ cell ALP and tissue nonspecific alkaline phosphatase or liver/bone/kidney (L/B/K) ALP. The intestinal and placental ALP loci are located near the end of long arm of chromosome 2 and L/B/K ALP is located near the end of the short arm of chromosome 1. Although ALPs are present in many mammalian tissues and have been studied for the last several years still little is known about them. The bone isoenzyme may be involved in mammalian bone calcification and the intestinal isoenzyme is thought to play a role in the transport of phosphate into epithelial cells of the intestine. In this review, we tried to provide an overview about the various forms, structure and functions of alkaline phosphatase with special focus on liver/bone/kidney alkaline phosphatase.

Reduced L/B/K alkaline phosphatase gene expression in renal cell carcinoma: plausible role in tumorigenesis

Renal cell carcinoma (RCC) is the most common kidney cancer in adults. Although several genes have been found to be involved in carcinogenesis of RCC, more great efforts are needed to identify new genes which are responsible for the process. Clear cell RCC, originates from proximal tubule cells, is the most common pathological type of RCC. Alkaline phosphatase (ALP) is a marker enzyme of brush border membrane of proximal tubular cells. Our previous studies showed a significant decreased activity of Liver/Bone/Kidney (L/B/K) alkaline phosphatase in RCC. In the present study, we explored the molecular basis of the decreased activity of ALP in RCC. Immunohistochemistry, immunofluorescence and flow cytometry analysis showed decreased ALP protein in RCC. Additionally, real time PCR documented significantly reduced ALP gene expression (P = 0.009). Moreover, RCC cell lines (ACHN and A498) transfected with full length L/B/K cDNA showed decreased migratory property as well as viability of these cells as compared with controls (P = 0.000). Further, L/B/K ALP cDNA transfected cells (ACHN and A498) showed significant increased apoptosis as compared to control (P = 0.000). These findings suggest the new role of ALP in cell viability and apoptosis and involvement in RCC tumorigenesis. However, further studies are needed to explore the exact molecular mechanism.

The sodium iodide symporter (NIS): regulation and approaches to targeting for cancer therapeutics

Expression of the sodium iodide symporter (NIS) is required for efficient iodide uptake in thyroid and lactating breast. Since most differentiated thyroid cancer expresses NIS, β-emitting radioactive iodide is routinely utilized to target remnant thyroid cancer and metastasis after total thyroidectomy. Stimulation of NIS expression by high levels of thyroid-stimulating hormone is necessary to achieve radioiodide uptake into thyroid cancer that is sufficient for therapy. The majority of breast cancer also expresses NIS, but at a low level insufficient for radioiodine therapy. Retinoic acid is a potent NIS inducer in some breast cancer cells. NIS is also modestly expressed in some non-thyroidal tissues, including salivary glands, lacrimal glands and stomach. Selective induction of iodide uptake is required to target tumors with radioiodide. Iodide uptake in mammalian cells is dependent on the level of NIS gene expression, but also successful translocation of NIS to the cell membrane and correct insertion. The regulatory mechanisms of NIS expression and membrane insertion are regulated by signal transduction pathways that differ by tissue. Differential regulation of NIS confers selective induction of functional NIS in thyroid cancer cells, as well as some breast cancer cells, leading to more efficient radioiodide therapy for thyroid cancer and a new strategy for breast cancer therapy. The potential for systemic radioiodide treatment of a range of other cancers, that do not express endogenous NIS, has been demonstrated in models with tumor-selective introduction of exogenous NIS.

Stressed Jerusalem artichoke tubers (Helianthus tuberosus L.) excrete a protein fraction with specific cytotoxicity on plant and animal tumour cell

Wounds from Jerusalem artichoke (Helianthus tuberosus L.) tubers excrete bioactive metabolites from a variety of structural classes, including proteins. Here we describe a protein specifically active against tumour cells arising either from human, animal or plant tissues. The non-tumour animal cells or the plant callus cells are not sensitive to these excreta. The active product was only obtained after a wound-drought stress of plant tubers. The cytotoxicity varies according to the tumour cell type. For instance, some human tumour cell lines and especially the human mammary tumour cells MDA-MB-231 were shown to be very susceptible to the active product. The active agent is shown to contain an 18-kDa polypeptide with homology to a superoxide dismutase (SOD). A 28-kDa polypeptide, related to an alkaline phosphatase (AP), was shown to be tightly linked to this 18-kDa polypeptide. The excreted 28-kDa polypeptide also displayed a consensus sequence similar to the group of DING proteins, but with a smaller molecular weight. The superoxide dismutase polypeptide was shown to be involved in the antitumour activity, but the presence of smaller factors (MW<10 kDa), such as salicylic acid, can enhance this activity.

Distinct modulation of alkaline phosphatase isoenzymes by 17beta-estradiol and xanthohumol in breast cancer MCF-7 cells

OBJECTIVES

To examine the effect of 17beta-estradiol and xanthohumol in alkaline phosphatase (ALP) expression and activity in breast cancer MCF-7 cells.

DESIGN AND METHODS

ALP isoenzymes expression was evaluated by RT-PCR and Western blotting. ALP activity was measured by spectrophotometry. Cell proliferation and apoptosis were examined by MTT and immunostaining for KI67 and TUNEL, respectively.

RESULTS

ALP isoenzymes expression and activity were decreased by 1 nM 17beta-estradiol. Pure estrogenic antagonist (ICI 182,780) reversed 17beta-estradiol-inhibiting effect in TNS-ALP expression. RNA and protein expression of IALP, but not TNS-ALP, was also decreased by incubation with 10 microM xanthohumol (IC(50)) and was accompanied by a significant reduction in ALP activity. Treatment with 17beta-estradiol enhanced cell proliferation and decreased apoptosis. Conversely, xanthohumol incubation inhibited cell viability and apoptosis.

CONCLUSION

Estrogens and xanthohumol differently modulate ALP isoenzymes. ALP loss associated with increased cell proliferation. Modulation of this enzyme by 17beta-estradiol and xanthohumol might provide therapeutic strategies against hormone-dependent breast cancer.

Inhibition of growth and increase of alkaline phosphatase activity in cultured human oral cancer cells by all-trans retinoic acid

In this study, the effects of all-trans retinoic acid (ATRA) on human oral cancer cells with regard to cell growth, the cell cycle, and alkaline phosphatase (ALP) activity were evaluated. Human oral cancer KB cells were treated with various concentrations of ATRA, and cell growth was then determined using the MTT viability assay. The cell-cycle distribution and ALP activity were analysed using a flow cytometer and chemical analyser, respectively. The KB cells were inhibited by ATRA at concentrations of 1-16 microM (1 microM, P<0.05; 2 microM, P<0.01; 4, 8 and 16 microM, P<0.001) in a dose-dependent manner. ATRA arrested KB cells in the G0/G1 phase. The ALP activity in KB cells was increased by ATRA. This is one of the first studies to focus on the expression of ALP in human head-and-neck carcinoma cells treated with retinoids. These findings suggest that the anti-tumour effects of ATRA on human oral cancer are associated with G0/G1 phase arrest and an increase in ALP activity.

Differential regulation of sodium/iodide symporter gene expression by nuclear receptor ligands in MCF-7 breast cancer cells

The sodium/iodide symporter (NIS) mediates iodide uptake in lactating breast tissue and is expressed in some breast cancers. We have previously demonstrated that all-trans retinoic acid (tRA) stimulates NIS gene expression and the selective cytotoxic effect of beta-emitting radioiodide-131 ((131)I) in both in vitro and in vivo MCF-7 breast cancer cell systems. We studied the ability of natural and synthetic retinoids, in combination with other nuclear receptor ligands, to achieve greater and more sustained induction of NIS in MCF-7 cells and enhance (131)I-mediated cytotoxicity. Selective stimulation of retinoic acid receptor (RAR) beta/gamma produced marked NIS induction; and selective stimulation of RARalpha, RARgamma, or retinoid X receptor produced more modest induction. Maximal NIS induction was seen with 9-cis retinoic acid and AGN190168, a RAR beta/gamma-agonist. Dexamethasone (Dex), but not the other nuclear receptor ligands, in combination with tRA synergistically induced iodide uptake and NIS mRNA expression, predominantly by prolonging NIS mRNA half-life. The addition of Dex reduced the EC(50) of tRA for NIS stimulation to approximately 7%, such that 10(-7) m tRA with addition of Dex enhanced iodide uptake and selective cytotoxicity of (131)I greater than 10(-6) m tRA alone. AGN190168 combined with Dex synergistically increased iodide uptake and significantly prolonged induction (5 d) of iodide uptake compared with that induced by the combination of tRA/Dex or 9-cis retinoic acid/Dex. The addition of Dex reduced the effective dose of retinoid and prolonged the induction of NIS, especially with AGN190168, suggesting higher efficacy of (131)I after combination treatment.

Alkaline phosphatase retained in HepG2 hepatocarcinoma cells vs. alkaline phosphatase released to culture medium: difference of aberrant glycosylation

Liver tissue is the source of 90% of serum alkaline phosphatase (AP). The serum levels and structures of tumor marker proteins change under many disease conditions as well as cancer. The study was aimed at determining the type of alkaline phosphatase (AP) present in HepG2 hepatocellular carcinoma cell line. Alkaline phosphatase rich extracts of healthy human liver, HepG2 hepatocarcinoma cells, as well as the condition medium of HepG2 cells were prepared by extraction with 40% n-butanol and 30-50% acetone precipitation, and subjected to various chromatographic procedures. Lectin affinity chromatography of the samples with concanavalin A-Sepharose 4B showed considerable differences in the elution patterns. Non-denaturing polyacrylamide gel electrophoresis of the culture medium yielded a relatively slow migrating band of activity that coincided with none of the three bands of activity produced by the normal liver extract, nor with the bands of the cell pellet extract. Inhibition patterns were established by measuring the enzyme activities in the presence of varying concentrations of L-phenylalanine, L-leucine, L-homoarginine, and levamisole. The APs from the cell line were neuraminidase sensitive. According to the results the main AP produced and released to the medium by HepG2 cell line is an aberrantly glycosylated tissue non-specific AP. In addition, the differences between the cell-pellet AP and the culture medium AP seemed to stem from different sugar moieties in their structures.

Functional expression, purification, and characterization of the extra stable human placental alkaline phosphatase in the Pichia pastoris system

Human placental alkaline phosphatase was successfully cloned in the yeast system Pichia pastoris. The recombinant enzyme was over-expressed as a secreted protein in the cultured medium. The enzyme was extremely stable, which resulted in a total recovery of the enzyme activity after the purification process. The purified enzyme preparation was apparently homogeneous as examined by the polyacrylamide gel electrophoresis, analytical gel-permeation chromatography, and analytical ultracentrifugation. The final enzyme preparation showed a purification of 803-fold from the culture medium with a specific activity of 578 U/mg of protein. Fluorescence spectroscopic analyses showed multiple unfolding steps in the urea denaturation process of the homodimeric recombinant enzyme. Extensive conformational change of the enzyme in urea was detected by the analytical ultracentrifugation and the size-exclusive chromatography. The quaternary structure of the enzyme is quite stable. No indication of dissociation was observed after extensive tertiary structural changes.

Effect of Dendrostellera lessertii on the intracellular alkaline phosphatase activity of four human cancer cell lines

The cytotoxicity of an alcoholic extract of Dendrostellera lessertii (Thymelaeaceae) and one of its purified components was evaluated using four different human cancer cell lines. The IC(50) of the crude extract was found to be 28, 33, 31 and 30 microl for K562, CCRF-CEM, HL-60 and LNCaP-FGC-10 cells, respectively. Each microliter of the crude extract corresponds to 0.02 mg of the plant powder material. Similarly the IC(50) of the purified component was 5 x 10(-9), 20 x 10(-9), 8 x 10(-9) and 8 x 10(-9)M for K562, CCRF-CEM, HL-60 and LNCaP-FGC-10 cells, respectively. In addition, besides significant reduction in cell proliferation rates, the crude extract, at a dose of 18 microl/ml and the purified component at a dose of 3.5 x 10(-9)M, were capable of enhancing the intracellular protein content of each of the cell lines by almost 160% while the intracellular alkaline phosphatase activity was increased up to 450%.

Kinetics of mRNA expression of alkaline phosphatase isoenzymes in hepatic tissues from glucocorticoid-treated dogs

OBJECTIVE

To clone segments of the canine liver alkaline phosphatase (LALP) and corticosteroid-induced alkaline phosphatase (CIALP) genes and use those clones to determine the tissue source of CIALP, the kinetics of LALP and CIALP mRNA expression for glucocorticoid-treated dogs, and the correlation between LALP and CIALP transcript concentrations and isoenzyme activities.

SAMPLE POPULATION

Tissues obtained from 7 dogs treated with prednisone (1 mg/kg, SC, q 24 h) for up to 32 days and 1 untreated (control) dog.

PROCEDURE

Gene segments of LALP and CIALP were obtained by reverse transcription-polymerase chain reaction (RT-PCR) assay. The tissue source of CIALP and IALP mRNA was determined by northern blot analysis of tissues from 1 of the glucocorticoid-treated dogs. Hepatic tissues and serum samples were obtained from the 6 remaining glucocorticoid-treated dogs on days 0, 2, 5, 10, and 32 of prednisone treatment, and relative expression of LALP and CIALP mRNA was correlated with LALP and CIALP activity.

RESULTS

A 2,246-base pair (bp) segment of canine LALP and a 1,338-bp segment of CIALP were cloned. Northern blot analysis revealed CIALP mRNA expression in hepatic tissues only after glucocorticoid treatment. Kinetics of LALP and CIALP mRNA expression in the liver of glucocorticoid-treated dogs paralleled liver and serum activities of LALP and CIALP.

CONCLUSIONS AND CLINICAL RELEVANCE

The liver is the most likely source for CIALP in dogs. Analysis of kinetics of serum and hepatic LALP and CIALP mRNA suggests that after glucocorticoid treatment, both are regulated by modification of mRNA transcript concentrations, possibly through differing mechanisms.

Differential regulation of placental and germ cell alkaline phosphatases by glucocorticoid and sodium butyrate in human gastric carcinoma cell line TMK-1

The expression and regulation of alkaline phosphatase (AP) was studied in the human gastric cancer cell line TMK-1. Biochemical analysis, reverse transcription-polymerase chain reaction, and Northern blot analysis demonstrated that the cells express placental, germ cell, and intestinal AP isozymes constitutively. Dexamethasone (Dex), a synthetic glucocorticoid, was shown to specifically induce the placental AP activity to about 10-fold and sodium butyrate (NaBu) induced germ cell AP activity to about 4-fold, respectively. In contrast, these two agents showed little effect on the level of intestinal isozymes. Dex and NaBu also differentially induced the mRNA levels of the placental and germ cell APs. Northern blot analysis of the placental AP transcript in the presence of the transcription inhibitor, 5, 6-dichloro-1-beta-D-ribofuranosyl benzimidazole, revealed that the half-life of placental AP mRNA is about 27 h for both the Dex-treated and untreated cells. Nuclear run-on transcription analysis indicated an apparent increase in the rate of placental AP gene transcription in Dex-treated cells. These results indicated that the effect of Dex occurred primarily by activation of the placental AP gene transcription in the cells. In order to study the direct Dex and NaBu effect on AP gene expression, the proximal promoter regions of AP genes were fused to luciferase reporter vectors. Despite the high similarity in nucleotide sequences of these two genes, transient transfection analysis demonstrated that Dex and NaBu exerted a specific stimulation only through the respective placental and germ cell AP gene promoter. Taken together, this study indicates that the expression of PAP and GCAP isozymes have specific regulatory mechanisms that can be differentially controlled by signals including glucocorticoid and NaBu.