Alkaline Phosphatase Pathophysiology with Emphasis on the Seldom-Discussed Role of Defective Elimination in Unexplained Elevations of Serum ALP – A Case Report and Literature Review

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.

Emerging potential approaches in alkaline phosphatase (ALP) activatable cancer theranostics

Alkaline phosphatase (ALP) is known as one of the most crucial members of the phosphatase family and encompasses the enormous ability to hydrolyze the phosphate group in various biomolecules; by this, it regulates several events in the pool of biological medium. Owing to its overexpression in various cancer cells, recently, its potential has evolved as a prominent biomarker in cancer research. In this article, we have underlined the recent advances (2019 onwards) of alkaline phosphatase in the arena of emerging cancer theranostics. Herein, we mainly focused on phosphate-locked molecular systems such as peptides, prodrugs, and aggregation-induced emission (AIE)-based molecules. When these theranostics encounter cancer cell-overexpressed ALP, it results in the hydrolysis of the phosphate group, which leads to the release of highly cytotoxic agents along with turn-on fluorophore/pre-existing fluorophore.

A Case of Hypophosphatasia With Normal Alkaline Phosphatase Levels

Background/Objective

Hypophosphatasia (HPP) is a rare disease associated with low serum alkaline phosphatase (ALP) activity. Here, we present a case of a patient with normal serum ALP levels diagnosed with HPP.

Case Report

A 36-year-old woman presented with progressive fatigue, weakness, and joint pain. She had been evaluated in the past for genetic disorders due to these symptoms and was found to have a history of several total ALP levels within normal limits but elevated vitamin B6 levels. She also reported having loose teeth and "gray gums" during her childhood. Bone-specific ALP was tested for suspicion of HPP and returned at 4.4 μ/L (reference range, 5.3-19.5 μg/L), which prompted genetic testing. Genetic testing confirmed a positive pathogenetic variant of the ALPL gene, the c.542C>T (p.Ser181Leu) variant. She started asfotase alfa treatment to improve her symptoms.

Discussion

HPP was diagnosed based on clinical suspicion supported by laboratory findings, which can cause it to be underdiagnosed or misdiagnosed. Current literature reports that a low total ALP level is the main biochemical marker of HPP and the only level needed to diagnose the disease. However, bone-specific ALP, a common marker used for bone turnover, has not been required to be tested.

Conclusion

This case highlights a patient with normal total ALP, but low bone-specific ALP diagnosed with HPP confirmed by genetic testing. This case warrants future investigation into the diagnostic approach to HPP and the diagnostic utility between ALP and bone-specific ALP.

Echinodorus macrophyllus: Acute toxicological evaluation of hydroxycinnamoyl derivatives from SF1 subfractions

ETHNOPHARMACOLOGICAL RELEVANCE

Echinodorus macrophyllus (Kunth.) Micheli (Alismataceae), known as chapéu-de-couro in Brazil, is popularly used to treat inflammatory diseases. We have previously demonstrated a significant reduction in the acute inflammation for the aqueous extract of E. macrophyllus (AEEm) and its ethanolic fraction (Fr20) and described that hydroxycinnamoyl derivatives present in SF1 (Fr20 subfraction) showed higher anti-inflammatory properties by mechanisms that include a reduction of TNF-α, IL-1β, CKCL1/KC, LTB4, and PGE2 levels in exudate.

AIM OF THE STUDY

This work describes the acute toxicological effect of SF1 subfraction on SW mice treated orally for five days in the air pouch model by evaluating the hematological and biochemical determinations on the blood samples; the relative organ weight and its histopathological analysis; the liver genotoxicity assessment and the activity of liver enzymes from xenobiotic metabolism.

MATERIALS AND METHODS

Fr20 was earlier fractionated on the Sephadex LH-20 column, yielding mainly four subfractions, including SF1. The SF1 toxicity was evaluated in mice challenged with carrageenan on the air pouch inflammation model and orally treated for five days. The body weight was monitored daily, and the organs were weighed after the euthanasia. Hematological and biochemical determinations were carried out using specific commercial kits and following the protocols provided by the manufacturers. The organs were fixed, sectioned, processed for hematoxylin and eosin staining, and analyzed by light microscopy. Genotoxicity assessment was performed by the alkaline single-cell gel electrophoresis. Livers were processed for ethoxyresorufin-O-deethylase (EROD) and Glutathione S-transferase (GST) assays.

RESULTS

SF1 exhibited low toxicity, as no significant discrepancy was observed in the relative weight of the body organs of mice. Moreover, the daily treatment with SF1 did not alter the number and percentage of red blood cells or hemoglobin concentration in the blood. The treatment with SF1 did not affect the creatinine concentration, but the 25 mg/kg dose reduced the plasma urea level and uric acid, suggesting its use in treating acute renal failure. The parameters analyzed did not present biochemical alterations indicative of liver disease. Regarding serum triglyceride and cholesterol levels, a significant decrease was detected in both parameters in mice treated with SF1. In addition, the histopathological analysis showed that inflammatory focus in the livers seemed more relevant in the control groups than in those treated. There were no significant changes in the renal or splenic tissues of animals treated with SF1. Treatment with SF1 also does not have a genotoxic effect on liver cells.

CONCLUSION

Treatment with SF1 showed no toxicity in mice at doses equivalent to those recommended for humans, which provides evidence of the safety of the therapeutic use of this subfraction.

Anti-enzymatic and DNA docking studies of montelukast: A multifaceted molecular scaffold with in vitro investigations, molecular expression analysis and molecular dynamics simulations

Montelukast, an approved leukotriene receptor 1 (Cys-LT 1) antagonist with anti-inflammatory properties is used for the treatment of asthma and allergic rhinitis. In the present studies, montelukast was subjected to in vitro inhibitory assays followed by kinetic and in silico investigations. Montelukast demonstrated inhibitory activity against yeast α-glucosidase (IC50 44.31 ± 1.21 μM), jack bean urease (JB urease, IC50 8.72 ± 0.23 μM), human placental alkaline phosphatase (hPAP, IC50 17.53 ± 0.19 μM), bovine intestinal alkaline phosphatase (bIAP, IC50 15.18 ± 0.23 μM) and soybean 15-lipoxygenase (15-LOX, IC50 2.41 ± 0.13 μM). Kinetic studies against α-glucosidase and urease enzymes revealed its competitive mode of inhibition. Molecular expression analysis of montelukast in breast cancer cell line MCF-7 down-regulated AP by a factor of 0.27 (5 μM) compared with the 0.26 value for standard inhibitor levamisole (10 μM). Molecular docking estimated a binding affinity ranging -8.82 to -15.65 kcal/mol for the enzymes. Docking against the DNA dodecamer (ID: 1BNA) observed -9.13 kcal/mol via minor groove binding. MD simulations suggested stable binding between montelukast and the target proteins predicting strong inhibitory potential of the ligand. Montelukast features a chloroquinoline, phenyl ring, a cyclopropane group, a carboxylic group and a sulfur atom all of which collectively enhance its inhibitory potential against the said enzymes. These in vitro and computational investigations demonstrate that it is possible and suggested that the interactions of montelukast with more than one targets presented herein may be linked with the side effects presented by this drug and necessitate additional work. The results altogether suggest montelukast as an important structural scaffold possessing multitargeted features and warrant further investigations in repurposing beyond its traditional pharmacological use.

β-TCP from 3D-printed composite scaffolds acts as an effective phosphate source during osteogenic differentiation of human mesenchymal stromal cells

Introduction: Human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) are often combined with calcium phosphate (CaP)-based 3D-printed scaffolds with the goal of creating a bone substitute that can repair segmental bone defects. In vitro, the induction of osteogenic differentiation traditionally requires, among other supplements, the addition of β-glycerophosphate (BGP), which acts as a phosphate source. The aim of this study is to investigate whether phosphate contained within the 3D-printed scaffolds can effectively be used as a phosphate source during hBM-MSC in vitro osteogenesis. Methods: hBM-MSCs are cultured on 3D-printed discs composed of poly (lactic-co-glycolic acid) (PLGA) and β-tricalcium phosphate (β-TCP) for 28 days under osteogenic conditions, with and without the supplementation of BGP. The effects of BGP removal on various cellular parameters, including cell metabolic activity, alkaline phosphatase (ALP) presence and activity, proliferation, osteogenic gene expression, levels of free phosphate in the media and mineralisation, are assessed. Results: The removal of exogenous BGP increases cell metabolic activity, ALP activity, proliferation, and gene expression of matrix-related (COL1A1, IBSP, SPP1), transcriptional (SP7, RUNX2/SOX9, PPARγ) and phosphate-related (ALPL, ENPP1, ANKH, PHOSPHO1) markers in a donor dependent manner. BGP removal leads to decreased free phosphate concentration in the media and maintained of mineral deposition staining. Discussion: Our findings demonstrate the detrimental impact of exogenous BGP on hBM-MSCs cultured on a phosphate-based material and propose β-TCP embedded within 3D-printed scaffold as a sufficient phosphate source for hBM-MSCs during osteogenesis. The presented study provides novel insights into the interaction of hBM-MSCs with 3D-printed CaP based materials, an essential aspect for the advancement of bone tissue engineering strategies aimed at repairing segmental defects.

Loss of N-acetylglucosaminyl transferase V is involved in the impaired osteogenic differentiation of bone marrow mesenchymal stem cells

The imbalance of bone resorption and bone formation causes osteoporosis (OP), a common skeletal disorder. Decreased osteogenic activity was found in the bone marrow cultures from N-acetylglucosaminyl transferase V (MGAT5)-deficient mice. We hypothesized that MGAT5 was associated with osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and involved in the pathological mechanisms of osteoporosis. To test this hypothesis, the mRNA and protein expression levels of MGAT5 were determined in bone tissues of ovariectomized (OVX) mice, a well-established OP model, and the role of MGAT5 in osteogenic activity was investigated in murine BMSCs. As expected, being accompanied by the loss of bone mass density and osteogenic markers (runt-related transcription factor 2, osteocalcin and osterix), a reduced expression of MGAT5 in vertebrae and femur tissues were found in OP mice. In vitro, knockdown of Mgat5 inhibited the osteogenic differentiation potential of BMSCs, as evidenced by the decreased expressions of osteogenic markers and less alkaline phosphatase and alizarin red S staining. Mechanically, knockdown of Mgat5 suppressed the nuclear translocation of β-catenin, thereby downregulating the expressions of downstream genes c-myc and axis inhibition protein 2, which were also associated with osteogenic differentiation. In addition, Mgat5 knockdown inhibited bone morphogenetic protein (BMP)/transforming growth factor (TGF)-β signaling pathway. In conclusion, MGAT5 may modulate the osteogenic differentiation of BMSCs via the β-catenin, BMP type 2 (BMP2) and TGF-β signals and involved in the process of OP.

Development and application of a simple pharmacokinetic model that quantitatively describes the distribution and elimination of the commonly measured proteins

Increased plasma concentrations of a variety of cellular enzymes (alanine transaminase, aspartate aminotransferase, alkaline phosphatase, amylase, etc.) are commonly used as routine screening tests for a range of conditions. An increased concentration usually is assumed to result from an increased rate of delivery to the plasma. Factors such as decreased metabolism or excretion or altered extravascular distribution usually are ignored. As a prelude to a detailed analysis of all the factors producing altered plasma enzyme levels, we have reviewed the relevant literature describing the pharmacokinetics (PK) of 13 of the commonly measured plasma proteins and developed a PK model that provides a simple physiological description of all the data. Our model starts with the general 3-compartment, 6-parameter system previously developed for albumin and interprets the fluxes in terms of unidirectional sieved protein convectional volume flows from the plasma to the two tissue compartments and equal lymph flows returning to the plasma. This greatly constrains the model such that each protein is characterized by only two adjustable parameters (plasma clearance and sieving factor). In addition to accurately fitting the plasma kinetics, the model can accurately describe the tissue and lymph protein PK. For example, it can describe the thoracic duct lymph protein concentration following an intravenous infusion or the plasma concentration following a subcutaneous tissue injection. This simple model provides a satisfactory framework for the PK of 12 of the 13 proteins investigated. The glycoprotein intestinal alkaline phosphatase is the exception, requiring the addition of a liver recycling compartment involving the asialoglycoprotein receptor.

Genome-wide association and Mendelian randomization study of fibroblast growth factor 21 reveals causal associations with hyperlipidemia and possibly NASH

BACKGROUND

Fibroblast growth factor 21 (FGF21) is a hepatokine that produces metabolic benefits, such as improvements of lipid profile. We performed a genome-wide association study (GWAS) to identify genetic variants associated with circulating FGF21 and investigated the causal effects of FGF21 on pertinent outcomes using Mendelian randomization (MR).

METHODS

We conducted a GWAS testing ∼7.8 million DNA sequence variants with circulating FGF21 in a discovery cohort of 6259 Swedish adults with replication in 4483 Swedish women. We then performed two-sample MR analyses of genetically predicted circulating FGF21 in relation to alcohol and nutrient intake, cardiovascular and metabolic biomarkers and diseases, and liver function biomarkers using publicly available GWAS summary statistics data.

RESULTS

Our GWAS identified multiple single-nucleotide polymorphisms with genome-wide significant associations (P < 5 × 10^-8) with circulating FGF21 on chromosomes 2 and 19 in or near the GCKR and FGF21 genes, respectively. The strongest signal at the FGF21 locus (rs2548957, β = 0.181, P < 2.18 × 10^-42) displayed in two-sample MR analyses robust associations with lower alcohol intake, lower circulating low-density lipoprotein cholesterol, apolipoprotein B, C-reactive protein, gamma-glutamyl transferase, and galectin-3 concentrations, and higher circulating insulin-like growth factor-I and alkaline phosphatase concentrations after correcting for multiple testing (P < 0.0018) whereas associations with fat mass, type 2 diabetes, and cardiovascular disease were largely null.

CONCLUSIONS

We identified robust associations of certain genetic variants in or near the GCKR and FGF21 genes with circulating FGF21 concentrations. Furthermore, our results support a strong causal effect of FGF21 on improved lipid profile, reduced alcohol consumption and C-reactive protein concentrations, and liver function biomarkers including fibrosis. We found largely null or weak positive associations with fat mass, diabetes, and cardiovascular disease as well as higher insulin-like growth factor-I concentrations, which could indicate a compensatory increase to regulate the above FGF21 resistant states in humans.

Ratiometric detection and imaging of endogenous alkaline phosphatase activity by fluorescein-coumarin-based fluorescence probe

Alkaline phosphatase (ALP) is a type of enzyme that widely exists in various tissues of the human body; it plays an important role in regulating many cell functions. The development of a sensitive and accurate tool to detect the changes of ALP activity in organisms can contribute to research in the fields of biochemistry, cytology, clinical medicine, etc. In this paper, a small organic molecule-based ratiometric fluorescent probe (FCP) was designed based on the hydroxyl electron-donating group in fluorescein-coumarin protected by the phosphate group. ALP can trigger the fluorescence change through the enzyme-catalyzed cleavage of phosphoryl ester groups, and the ratio of ALP can be measured at wavelengths of 465 nm and 530 nm. The probe had high selectivity and sensitivity to ALP, and the detection limit measured under the optimal conditions in an aqueous medium reached 0.006 mU/mL. The ALP activity of human serum samples was determined using the probe and found to be in good agreement with that measured using commercial ALP kits. Finally, the probe was also successfully applied to image ALP in living hepatocytes with good selectivity and sensitivity.

Preoperative Alkaline Phosphatase-adjusted CA19-9 as a Superior Prognosticator for Extrahepatic Biliary Tract Cancer With Jaundice

BACKGROUND/AIM

The major limitation of carbohydrate antigen (CA)19-9 as a tumor marker is the high incidence of false-positive results during cholestasis. We evaluated preoperative CA19-9 and its adjusted values [ratios of CA19-9 to total-bilirubin (TB), direct-bilirubin (DB), and alkaline phosphatase (ALP)] to investigate the most suitable prognostic parameter in extrahepatic biliary tract cancer (eBTC) patients with or without jaundice.

PATIENTS AND METHODS

eBTC patients (n=140) who underwent resection were divided based on the absence (TB <2.0 mg/dl, n=90) or presence (TB ≥2.0 mg/dl, n=50) of preoperative jaundice. Within each group, the associations with overall survival (OS) were assessed for CA19-9, CA19-9/TB, CA19-9/DB and CA19-9/ALP ratios using Cox regression, receiver operating characteristic (ROC) analyses, and area under the curve (AUC) estimates.

RESULTS

In univariate analysis in the group without jaundice, both high CA19-9 and high CA19-9/TB ratio were associated with poor OS, whereas other parameters were not. ROC-AUC for OS prediction was greater in CA19-9 than in the CA19-9/TB ratio, and CA19-9 was identified as an independent prognosticator in multivariate analysis. In the group with jaundice, CA19-9 was not significant; however, CA19-9/TB, CA19-9/DB, and CA19-9/ALP ratios were all associated with poor OS. In ROC-AUC analysis, CA19-9/ALP ratio showed the highest predictive value; furthermore, it was an independent prognosticator in multivariate analysis.

CONCLUSION

Adjustment of the CA19-9 value was less useful as a predictor in the absence of jaundice. On the other hand, the CA19-9/ALP ratio showed superior prognostic value in jaundiced patients with eBTC.