Crossroad between the Heat Shock Protein and Inflammation Pathway in Acquiring Drug Resistance: A Possible Target for Future Cancer Therapeutics

The development of multidrug resistance (MDR) against chemotherapeutic agents has become a major impediment in cancer therapy. Understanding the underlying mechanism behind MDR can guide future treatment for cancer with better therapeutic outcomes. Recent studies evidenced that crossroads interaction between the heat shock proteins (HSP) and inflammatory responses under the tumor microenvironment plays a pivotal role in modulating drug responsiveness and drug resistance through a complex cytological process. This review aims to investigate the interrelationship between inflammation and HSP in acquiring multiple drug resistance and investigate strategies to overcome the drug resistance to improve the efficacy of cancer treatment. HSP plays a dual regulatory effect as an immunosuppressive and immunostimulatory agent, involving the simultaneous blockade of multiple signaling pathways in acquiring MDR. For example, HSP27 shows biological effects on monocytes by causing IL10 and TNFα secretion and blocking monocyte differentiation to normal dendritic cells and tumor-associated macrophages to promote cancer progression and chemoresistance. Thus, the HSP function and immune-checkpoint release modalities provide a therapeutic target for a therapeutically beneficial approach for enhancing anti-tumor immune responses. The interconnection between inflammation and HSP, along with the tumor microenvironment in acquiring drug resistance, has become crucial for rationalizing the effect of HSP immunomodulatory activity with immune checkpoint blockade. This relationship can overcome drug resistance and assist in the development of novel combinatorial cancer immunotherapy in fighting cancer with decreasing mortality rates.

Recent Developments of Silk-Based Scaffolds for Tissue Engineering and Regenerative Medicine Applications: A Special Focus on the Advancement of 3D Printing

Regenerative medicine has received potential attention around the globe, with improving cell performances, one of the necessary ideas for the advancements of regenerative medicine. It is crucial to enhance cell performances in the physiological system for drug release studies because the variation in cell environments between in vitro and in vivo develops a loop in drug estimation. On the other hand, tissue engineering is a potential path to integrate cells with scaffold biomaterials and produce growth factors to regenerate organs. Scaffold biomaterials are a prototype for tissue production and perform vital functions in tissue engineering. Silk fibroin is a natural fibrous polymer with significant usage in regenerative medicine because of the growing interest in leftovers for silk biomaterials in tissue engineering. Among various natural biopolymer-based biomaterials, silk fibroin-based biomaterials have attracted significant attention due to their outstanding mechanical properties, biocompatibility, hemocompatibility, and biodegradability for regenerative medicine and scaffold applications. This review article focused on highlighting the recent advancements of 3D printing in silk fibroin scaffold technologies for regenerative medicine and tissue engineering.

Immobilization of enzymes for bioremediation: A future remedial and mitigating strategy

Over the years, extensive urbanization and industrialization have led to xenobiotics contamination of the environment and also posed a severe threat to human health. Although there are multiple physical and chemical techniques for xenobiotic pollutants management, bioremediation seems to be a promising technology from the environmental perspective. It is an eco-friendly and low-cost method involving the application of microbes, plants, or their enzymes to degrade xenobiotics into less toxic or non-toxic forms. Moreover, bioremediation involving enzymes has gained an advantage over microorganisms or phytoremediation due to better activity for pollutant degradation with less waste generation. However, the significant disadvantages associated with the application of enzymes are low stability (storage, pH, and temperature) as well as the low possibility of reuse as it is hard to separate from reaction media. The immobilization of enzymes without affecting their activity provides a possible solution to the problems and allows reusability by easing the process of separation with improved stability to various environmental factors. The present communication provides an overview of the importance of enzyme immobilization in bioremediation, carrier selection, and immobilization methods, as well as the pros and cons of immobilization and its prospects.

Isolation and Phytochemical Screening of Endophytic Fungi Isolated from Medicinal Plant Mappia foetida and Evaluation of Its In Vitro Cytotoxicity in Cancer

Isolated endophyte fungi from Mappia foetida have been explored as a potential source for the mass production of anticancer drug lead compounds in the current study. Since medical plants are not feasible economically for mass production of bioactive pharmaceutical important molecules using plant tissue culture due to factors like media design and fungal contamination, endophyte fungal mass culture have been an alternative for the relatively easy and inexpensive production. Two endophytic fungi isolated, Alternaria alternata and Fusarium species were mass cultured and their prepared alcoholic extract subjected to standard procedures to identify the phytochemical screening by gas chromatography-mass spectrometry (GCMS), high-performance liquid chromatography (HPLC), UV visible spectrophotometry (UV-VIS), and Fourier transform infrared spectroscopy (FTIR). GC-MS analysis revealed the presence of three major compounds in the extracts. The phytochemical screening confirmed the presence of an anticancer compound (camptothecin) in their extract. Moreover, the dose-dependent anticancer activity of ethanol extract was demonstrated against cervical carcinoma (HeLa), breast carcinoma (MCF-7), non-small cell lung carcinoma (H1975), and hepatocellular carcinoma cell line (Hep G2) by MTT assay where doxorubicin was used as the positive control. Furthermore, the microscopic examination also confirmed the cytotoxic effect of extract of endophytic fungi Alternaria alternata and Fusarium species against tested cancer cells. Hence, endophytic fungi Alternaria alternata and Fusarium species might be exploited for mass production of phytochemicals having anticancer activity.

Phytochemical Screening and Bioactivity Studies of Endophytes Cladosporium sp. Isolated from the Endangered Plant Vateria Indica Using In Silico and In Vitro Analysis

Vateria indica is persistent tree used in Unani sources for the medication and classified as critically endangered. Thus, endophytes for alternative methods to explore these endangered Plants having rich source pharmaceuticals' active molecules for drug development and production. Endophytes comprises unexplored microbes as a potential source of rich pharmaceutically bioactive compounds attributable to their relationship with the host. In the current study, we have isolated endophyte fungi Cladosporium from the plant Vateria indica and performed phytochemical screening of its ethanolic extract to detect the phytochemicals using thin layer chromatography (TLC), gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), UV-visible spectrophotometry (UV-VIS), and Fourier transform infrared spectroscopy (FTIR). GC-MS analysis revealed the presence of an anticancer compound hydroxymethyl colchicine, antioxidant compound benzoic acid, and antimicrobial 2-(4-chlorophenoxy)-5-nitro in endophyte fungal extract of plant Vateria indica. Moreover, in silico analysis of bioactive compounds identified by GC-MS analysis using the Autodock Vina and SwissADME confirmed excellent anticancer activity methanone, [4-amino-2-[(phenylmethyl) amino]-5-thiazolyl] (4-fluorophenyl)- and hydroxymethyl colchicine against 6VO4 (Bfl-1 protein) as per Lipinski rule. Furthermore, we also demonstrated the excellent antioxidant of endophytic extract compared to plant extract by DPPH and ABTS assay, as well as antimicrobial activity against both Gram (+ ve) and Gram (- ve) bacteria. Moreover, the endophytic extract also showed its antimitotic activity with a mitotic index of 65.32, greater than the plant extract of 32.56 at 10 mg/ml. Thus endophytic fungi Cladosporium species isolated from plant Vateria indica might be used as a potential source for phytochemical anticancer hydroxymethyl colchicine, an antioxidant benzoic acid, and antimicrobial 2-(4-chlorophenoxy)-5-nitro.

Bimetallic p-ZnO/n-CuO nanocomposite synthesized using Aegle marmelos leaf extract exhibits excellent visible-light-driven photocatalytic removal of 4-nitroaniline and methyl orange

In the current study, the photocatalytic activity of bimetallic ZnO-CuO hetero-nanocomposite was evaluated and compared with the monometallic ZnO and CuO nanoparticles using 4-nitroaniline (4-NA) and methyl orange (MO). Bimetallic ZnO-CuO hetero-nanocomposite, ZnO, and CuO nanostructure were synthesized utilizing leaf extract of Aegle marmelos and characterized by transmission electron microscopy, X-ray diffraction, and XPS. Benefiting from the p-n heterostructures formation, bimetallic ZnO-CuO hetero-nanocomposite exhibits an excellent photocatalytic activity against 4-NA as well as MO compared to pure ZnO and CuO. In particular, bimetallic ZnO-CuO hetero-nanocomposite expressed the highest photocatalytic activity by reducing 90% of 4-NA in 20 min and by degrading 96% of MO in 10 min, whereas 65% reduction of 4-NA in 30 min and 93% degradation of MO in 45 min was exhibited by CuO and 48% reduction of 4-NA in 30 min and 98% degradation of MO in 50 min was exhibited by ZnO. Moreover, bimetallic ZnO-CuO hetero-nanocomposite maintains excellent photocatalytic activity even after five cycles indicating its stability as photocatalyst and reusability. Based on the experimental findings, bimetallic ZnO-CuO hetero-nanocomposite could be used as a photocatalyst for wastewater treatment with excellent regeneration efficiency.

Interruption of transmembrane signaling as a novel antisecretory strategy to treat enterotoxigenic diarrhea

Bacteria that produce heat-stable enterotoxins (STs), a leading cause of secretory diarrhea, are a major cause of morbidity and mortality worldwide. ST stimulates guanylyl cyclase C (GCC) and accumulation of intracellular cyclic GMP ([cGMP]i), which opens the cystic fibrosis transmembrane conductance regulator (CFTR)-related chloride channel, triggering intestinal secretion. Although the signaling cascade mediating ST-induced diarrhea is well characterized, antisecretory therapy targeting this pathway has not been developed. 2-ChloroATP (2ClATP) and its cell-permeant precursor, 2-chloroadenosine (2ClAdo), disrupt ST-dependent signaling in intestinal cells. However, whether the ability to disrupt guanylyl cyclase signaling translates into effective antisecretory therapy remains untested. In this study, the efficacy of 2ClAdo to prevent ST-induced water secretion by human intestinal cells was examined. In Caco-2 human intestinal cells, ST increased [cGMP]i, induced a chloride current, and stimulated net basolateral-to-apical water secretion. This effect on chloride current and water secretion was mimicked by the cell-permeant analog of cGMP, 8-bromo-cGMP. Treatment of Caco-2 cells with 2ClAdo prevented ST-induced increases in [cGMP]i, chloride current and water secretion. Inhibition of the downstream consequences of ST-GCC interaction reflects proximal disruption of cGMP production because 8-bromo-cGMP stimulated chloride current and water secretion in 2ClAdo-treated cells. Thus, this study demonstrates that disruption of guanylyl cyclase signaling is an effective strategy for antisecretory therapy and provides the basis for developing mechanism-based treatments for enterotoxigenic diarrhea.

Opening of cardiac sarcolemmal KATP channels by dinitrophenol separate from metabolic inhibition

Opening of ATP-sensitive K+ (KATP) channels by the uncoupler of oxidative phosphorylation, 2,4 dinitrophenol (DNP), has been assumed to be secondary to metabolic inhibition and reduced intracellular ATP levels. Herein, we present data which show that DNP (200 microM) can induce opening of cardiac KATP channels, under whole-cell and inside-out conditions, despite millimolar concentrations of ATP (1-2. 5 mm). DNP-induced currents had a single channel conductance (71 pS), inward rectification, reversal potential, and intraburst kinetic properties (open time constant, tauopen: 4.8 msec; fast closed time constant, tauclosed(f): 0.33 msec) characteristic of KATP channels suggesting that DNP did not affect the pore region of the channel, but may have altered the functional coupling of the ATP-dependent channel gating. A DNP analogue, with the pH-titrable hydroxyl replaced by a methyl group, could not open KATP channels. The pH-dependence of the effect of DNP on channel opening under whole-cell, cell-attached, and inside-out conditions suggested that transfer of protonated DNP across the sarcolemma is essential for activation of KATP channels in the presence of ATP. We conclude that the use of DNP for metabolic stress-induced KATP channel opening should be reevaluated.

Use of the MTT assay in adult ventricular cardiomyocytes to assess viability: effects of adenosine and potassium on cellular survival

This study used the colorimetric MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide)] assay to assess cell viability in isolated quiescent adult guinea-pig ventricular myocytes exposed to different insults or cardioprotective conditions, including adenosine and hyperkalemic-cardioplegia. Optical density (OD), reflecting intracellular reduction of MTT into formazan pigment formation, was a function of the number of viable cells (coefficient of linear correlation approximately 0.99), with MTT reduction preferentially carried out by rod-shaped cardiomyocytes (absorbance at 1.009 +/- 0.013 and 0.006 +/- 0.001 OD units for populations containing 50 and 0% of rod-shaped cells). Following prolonged mechanical (pressure of 1 lb/min for 40 min), chemical (10% DMSO or ethanol) or hypoxic injury (N2-saturated solution), the MTT reductase activity reflected reduction in the number of viable cells by 87%, >50%, and 77%, respectively. In cardiomyocytes exposed to a 40 min hypoxia (with CO2), the MTT reductase activity was 0.056 +/- 0.009 in the absence, and 0.074 +/- 0.008 OD units in the presence of adenosine (1 mM), i.e. adenosine reduced the number of non-viable cells. Also, the MTT assay revealed that the effect of potassium-containing solutions (16 and 32 mM K+) on cellular viability may depend on the extent of insult imposed on cardiomyocytes; i.e. a approximately 24% and 49% increase under mild hypoxia (0.03% CO2), or an 18% decrease in cell viability under severe hypoxia (N2) in pre-injured cells. Thus, the MTT assay used to assess viability of isolated adult cardiomyocytes revealed a direct cytoprotective effect of adenosine and hyperkalemic-cardioplegia by promoting cell survival under certain conditions in vitro.

Interruption of Escherichia coli heat-stable enterotoxin-induced guanylyl cyclase signaling and associated chloride current in human intestinal cells by 2-chloroadenosine

Diarrhea induced by Escherichia coli heat-stable enterotoxin (STa) is mediated by a receptor guanylyl cyclase cascade. The present study establishes that an intracellular nucleotide-dependent pathway disrupts toxin-induced cyclic GMP (cGMP) production and the associated chloride (Cl-) flux that underlie intestinal secretion. Incubation of Caco 2 human intestinal epithelial cells with the nucleoside analog 2-chloroadenosine (2ClAdo) resulted in a concentration- and time-dependent inhibition of toxin-induced cGMP production. Inhibition of cGMP production correlated with the metabolic conversion of 2ClAdo to 2-chloroadenosine triphosphate. The effect of 2ClAdo did not reflect activation of adenosine receptors, inhibition of adenosine deaminase, or modification of the binding or distribution of STa receptors. Guanylyl cyclase activity in membranes prepared from 2ClAdo-treated cells was inhibited, in contrast to membranes from cells not exposed to 2ClAdo, demonstrating that inhibition of guanylyl cyclase C (GCC) was mediated by a noncompetitive mechanism. Treatment of Caco 2 cells with 2ClAdo also prevented STa-induced Cl- current. Application of 8-bromo-cGMP, the cell-permeant analog of cGMP, to 2ClAdo-treated cells reconstituted the Cl- current, demonstrating that inhibition of Cl- flux reflected selective disruption of ligand stimulation of GCC rather than the chloride channel itself. Thus, the components required for adenine nucleotide inhibition of GCC signaling are present in intact mammalian cells, establishing the utility of this pathway to elucidate the mechanisms regulating ST-dependent guanylyl cyclase signaling and intestinal fluid homeostasis. In addition, these data suggest that the adenine nucleotide inhibitory pathway may be a novel target to develop antisecretory therapy for enterotoxigenic diarrhea.

Reversal of the ATP-liganded state of ATP-sensitive K+ channels by adenylate kinase activity

The mechanism that promotes transition from the ATP- to the ADP-liganded state of ATP-sensitive K+ (KATP) channels and consequent channel opening in a cytosolic environment of high ATP concentration has yet to be understood. A mechanism examined here that could reverse the ATP-inhibited state is based on the action of adenylate kinase to catalyze phosphoryl transfer between ATP and AMP, resulting in transformation of ATP into ADP. In membrane patches excised from guinea pig cardiomyocytes, AMP alone did not affect channel behavior but increased the open probability of ATP-inhibited KATP channels. This required MgCl2 and a hydrolyzable form of ATP and was prevented by P1,P5-di-adenosine-5'-pentaphosphate, an inhibitor of adenylate kinase. The single channel amplitude and kinetics of channel openings induced by the ADP-generating substrates of adenylate kinase, AMP and MgATP, were indistinguishable from the biophysical properties of the KATP channel exhibited after addition of MgADP. In whole cell voltage-clamped cardiomyocytes, introduction of exogenous adenylate kinase along with millimolar MgATP and AMP induced a K+ current that was suppressed by a sulfonylurea blocker of KATP channels. Enriched sarcolemmal membrane preparations were found to possess ATP.AMP phosphotransferase activity with properties attributable to an extramitochondrial isoform of adenylate kinase. These results indicate that adenylate kinase is a naturally occurring component of sarcolemmal membranes that could provide dynamic governance of KATP channel opening through its phosphoryl transfer catalytic action in the microenvironment of the channel.

A disrupter of actin microfilaments impairs sulfonylurea-inhibitory gating of cardiac KATP channels

The efficacy with which sulfonylurea drugs inhibit cardiac ATP-sensitive K+ (KATP) channels is reduced during metabolic compromise and cellular contracture. Disruption of the actin microfilament network, which occurs under similar conditions, reduces the sensitivity of the channel toward intracellular ATP. To investigate whether a disrupter of actin microfilaments could also affect the responsiveness of the KATP channel to sulfonylurea drugs, single-channel currents were measured in the inside-out configuration of excised patches from guinea pig ventricular myocytes. Treatment of the internal side of patches with deoxyribonuclease (DNase) I (100 micrograms/ml), which forms complexes with G actin and prevents actin filament formation, antagonized sulfonylurea-induced inhibition of KATP channels that was coupled with a loss of sensitivity to ATP. The apparent dissociation constant and Hill coefficient for the inhibitory effect of glyburide, a prototype sulfonylurea, on KATP-channel opening were, respectively, 0.13 microM and 0.95 before and 2.7 microM and 0.98 after DNase treatment. DNase did not alter intraburst kinetic properties of the channel. When DNase was denatured or coincubated with purified actin (200 micrograms/ml), it no longer decreased glyburide-induced channel inhibition. This suggests that sulfonylurea-inhibitory gating of cardiac KATP channels may also be regulated through a mechanism involving subsarcolemmal actin microfilament networks.

PCR-mediated differential display and cloning of a melanocyte gene decreased in malignant melanoma and up-regulated with sensitization to DNA damage

Characterization of genes expressed in normal cells and decreased in their malignant counterparts is important for detecting candidate tumor suppressor genes. We have now used comparative differential display of MRNAs from B16 melanoma and matched syngeneic normal melanocytes to detect a G0A gene expressed preferentially in resting G0 melanocytes compared to proliferating cells. Cloning and sequencing revealed no homology of G0A in the GenBank Database, suggesting that this is a new gene. Northern blot analysis with the cloned probe, confirmed about a five-fold higher expression in normal melanocytes compared to melanoma. Up-regulation of this gene was not detected by L-tyrosine induction of B16 melanoma terminal differentiation, but was seen in these cells, when exposed to the radiation sensitizer bromodeoxyuridine and subsequent UV radiation. Our differential expression data suggest that the G0A gene is important for melanocytic growth control and for the response of melanoma cells to radiation sensitizers.

Relationship between glial organization and the establishment of nerve tracts in rat spinal cord

Embryo and adult rat spinal cord sections immunostained for S-100 protein, vimentin, glial fibrillary acidic protein (GFAP), or phosphorylated 160 kDa neurofilament protein (NF), were used to study glial participation in nerve tissue assembly. Radial glial fibers (RGF) expressed vimentin since E12. In the peripheral ventral zone, RGF formed cephalocaudal plates (CP) within the white matter, ensheathing developing axonal tracts first expressing NF at E13. As axonal tracts increased, CP became denser and extended ventrolaterally. S-100 protein appeared at E17 in the midline and, at E18, it overlapped vimentin expression. Astrocytes expressed GFAP since E20. We conclude that the pattern found in the spinal cord results from interactions between developing axonal tracts and radial glia, and that it could set the structural basis for the organized assembly of the spinal cord found in adults.

[Cryptosporidium sp in diarrheic feces of immunocompetent patients]

During a 2 year period, 423 diarrheic fecal samples from immunocompetent patients, older than 14 years and assisted at the Hospital Nacional de Clínicas de Córdoba, were screened for Cryptosporidium oocysts. Feces were examined with saline and iodine wet mounts, enriched by the formol-ether method and stained by the modified Kinyoun acid-fast method. Furthermore, leucocytes and erythrocytes per HPF (400 x) were counted. Sixty nine (16.31%) diarrheic stools showed enteroparasites. Cryptosporidium oocysts were detected in 7 (1.65%) patients, second after Giardia intestinalis. Diarrhoea was moderated in 6 patients and severe in the remaining one. Leucocytes were increased only in one case, belonging to a patient with moderate diarrhoea.

Effects of the novel potassium channel opener, UR-8225, on contractile responses in rat isolated smooth muscle

1. The effects of UR-8225 [(1,2-dihydro-4-(1,2-dihydro-2-oxo-1-pyridyl)-2,2-dimethyl-1-oxonapht halen-6- carbonitrile)] and levcromakalim were studied on the electrical and contractile responses induced by noradrenaline and KCl and on 86Rb+ efflux in rat aortic rings and on spontaneous mechanical activity in rat portal vein segments. 2. UR-8225 and levcromakalim, 10(-9) M-10(-5) M, relaxed the contractile responses induced by noradrenaline (IC50 = 2.7 +/- 0.4 x 10(-6) M and 6.6 +/- 1.3 x 10(-7) M, respectively) or 30 mM KCl (IC50 = 1.4 +/- 0.2 x 10(-7) M and 9.4 +/- 1.3 x 10(-8) M, respectively) more effectively than those induced by 80 mM KCl. The relaxant effect on noradrenaline-induced contractions was independent of the presence or absence of functional endothelium. 3. The vasorelaxant effect of UR-8225 and levcromakalim can be competitively antagonized by glibenclamide, an ATP-sensitive K+ channel blocker. There were no differences in the calculated pA2 values for glibenclamide to inhibit UR-8225- and levcromakalim-induced relaxations (7.61 +/- 0.08 and 7.69 +/- 0.10, respectively). The slope of the Schild plot yielded values not significantly different from unity (0.95 +/- 0.06 and 0.96 +/- 0.05, respectively). 4. UR-8225 (10(-5) M) hyperpolarized the resting aortic membrane potential from -50.7 +/- 0.7 mV to -66.0 +/- 2.0 mV and stimulated 86Rb+ efflux. 5. UR-8225 and levcromakalim inhibited the contractions induced by Ca2+ in aortae incubated in Ca(2+)-free PSS containing methoxyverapamil in the presence of noradrenaline. 6. Both drugs inhibited the amplitude of spontaneous activity in portal veins (IC50 = 5.1 +/- 1.4 x 10-8 M and 1.5 +/- 0.7 x 10-8 M, respectively), this effect being competitively antagonized by glibenclamide.7. These results indicated that UR-8225 exhibited qualitatively similar, but slightly less potent,vasorelaxant effects than those exerted by levcromakalim, which suggests that they can be related to its ability to activate ATP-sensitive K+ channels in vascular smooth muscle cells.

Immunocytochemical study of S-100 positive glial cells in the brainstem and spinal cord of the rat embryo

A light and electronmicroscopic immunocytochemical study of the glial cells in the brainstem and spinal cord of the 18th day rat embryo was performed using an anti-S-100 protein antiserum. Only the radial glia and the free immature glial cells are S-100 immunoreactive. Neurons are devoid of S-100 immunoreactivity. The radial glia form two paramedial plates and a great number of lateral plates, uniformly spaced along the ventral portion of the brainstem from the mesencephalon to the medulla. The S-100 protein was also detected in the perivascular membranes and glial limitans. Embryonic glia adopt a highly organized spatial pattern in the brainstem that could set the structural basis for an organized assembly of the developing nervous tissue. The use of the S-100 protein as a glial marker in the embryonic rat brain proved to be of great value. Antibodies to S-100 protein allow the demonstration of immature glial cells and a highly organized spatial pattern in the brainstem and spinal cord of the rat embryo.