2058 research outputs found
Sort by
Molecular characterizations of rel and rellike genes of Mycobacterium tuberculosis
No full textMycobacterium tuberculosis (Mtb) is a highly pathogenic bacterium belonging to the Mycobacteriaceae family and the causative agent of tuberculosis (TB), also known as „white plague‟. Robert Koch (Fig. 1) first discovered the pathogen in 1882. Mtb has an unusual, waxy coating on its cell surface (primarily mycolic acid), which makes the cells impervious to Gram staining, therefore, acid-fast detection techniques are used. Mtb is highly aerobic and requires high levels of oxygen. Mtb typically attacks the lungs, but can also affect other tissues of the body. It is transmitted through person to person via aerosols. In healthy people, infection with Mtb often causes no symptoms, since the person's immune system acts to “wall off” the bacteria. The symptoms of active TB of the lung are coughing, sometimes sputum may contain frank blood, chest pains, weakness, weight loss, fever and night sweats. The most frequently used diagnostic methods for TB are the tuberculin skin test, acid-fast stain and chest radiograph
Nanofabrication of methylglyoxal with chitosan biopolymer: a potential tool for enhancement of its anticancer effect
No full textThe normal metabolite methylglyoxal (MG) specifically kills cancer cells by inhibiting glycolysis and mitochondrial respiration without much adverse effect upon normal cells. Though the anticancer property of MG is well documented, its gradual enzymatic degradation in vivo has prompted interest in developing a nanoparticulate drug delivery system to protect it and also to enhance its efficacy.
Materials and methods: MG-conjugated chitosan nanoparticles (Nano-MG) were prepared by conjugating the carbonyl group of MG with the amino group of chitosan polymer (Schiff’s base formation). Nano-MG were characterized in detail using the dynamic light scattering method, zeta potential measurement, Fourier transform infrared spectroscopy, and transmission electron microscopic analysis. Amount of MG anchored to Nano-MG, stability of Nano-MG, and in vitro release of MG from Nano-MG were estimated spectrophotometrically. Ehrlich ascites carcinoma (EAC) cells, human breast cancer cell line HBL-100, and lung epithelial adenocarcinoma cell line A549 were used as test systems to compare Nano-MG with bare MG in vitro. Cytotoxicity to EAC cells was evaluated by the trypan blue dye exclusion test, and cell viability of HBL-100 and A549 cells were studied using 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis of HBL-100 cells was assessed by flow cytometry and confocal microscopy. In vivo studies were performed on both EAC cells inoculated and also in sarcoma-180-induced solid tumor-bearing Swiss albino mice to assess the anticancer activity of Nano-MG in comparison to bare MG with varying doses, times, and administrative routes.
Results: Fourier transform infrared spectroscopy revealed the presence of imine groups in Nano-MG due to conjugation of the amino group of chitosan and carbonyl group of MG with diameters of nanoparticles ranging from 50–100 nm. The zeta potential of Nano-MG was +21 mV and they contained approximately 100 μg of MG in 1 mL of solution. In vitro studies with Nano-MG showed higher cytotoxicity and enhanced rate of apoptosis in the HBL-100 cell line in comparison with bare MG, but no detrimental effect on normal mouse myoblast cell line C2C12 at the concerned doses. Studies with EAC cells also showed increased cell death of nearly 1.5 times. Nano-MG had similar cytotoxic effects on A549 cells. In vivo studies further demonstrated the efficacy of Nano-MG over bare MG and found them to be about 400 times more potent in EAC-bearing mice and nearly 80 times more effective in sarcoma-180-bearing mice. Administration of ascorbic acid and creatine during in vivo treatments augmented the anticancer effect of Nano-MG.
Conclusion: The results clearly indicate that Nano-MG may constitute a promising tool in anticancer therapeutics in the near future
Excited State Proton Transfer in the Lysosome of Live Lung Cells:Normal and Cancer Cells
No full textDynamics of excited state proton transfer(ESPT) in the lysosome region of live lung cells (normaland cancer) is studied by picosecond time-resolved confocal microscopy. For this, we used a fluorescent probe, pyranine (8-
hydroxy-pyrene-1,3,6-trisulfonate, HPTS). From the colocalization of HPTS with a lysotracker dye (lysotracker yellow), we confirmed that HPTS resides in the lysosome for both of the cells. The diffusion coefficient (Dt) in the lysosome region was obtained from fluorescence correlation spectroscopy (FCS). From Dt, the viscosity of lysosome is estimated to be ∼40 and ∼30 cP in the cancer and normal cells, respectively. The rate constants of the elementary steps of ESPT in a normal lung cell (WI38) are compared with those in a lung cancer cell (A549). It is observed that the time constant of the initial proton transfer process in a normal cell (τPT = 40 ps) is similar to that in a cancer cell. The recombination of the geminate ion pair is slightly faster (τrec = 25 ps) in the normal cell than that (τrec = 30 ps) in a cancer cell. The time constant of the dissociation (τdiss) of the geminate ion pair for the cancer cell (τdiss = 80 ps) is 1.5 times
faster compared to that (τdiss = 120 ps) in a normal cell
A Novel Role for Protein Kinase Kin2 in Regulating HAC1 mRNA Translocation, Splicing, and Translation
No full textA signaling network called the unfolded protein response (UPR) resolves the protein-folding defects in the endoplasmic reticulum (ER) from yeasts to humans. In the yeast Saccharomyces cerevisiae, the UPR activation involves (i) aggregation of the ERresident kinase/RNase Ire1 to form an Ire1 focus, (ii) targeting HAC1 pre-mRNA toward the Ire1 focus that cleaves out an inhibitory intron from the mRNA, and (iii) translation of Hac1 protein from the spliced mRNA. Targeting HAC1 mRNA to the Ire1 focus requires a cis-acting bipartite element (3=BE) located at the 3= untranslated leader. Here, we report that the 3=BE plays an
additional role in promoting translation from the spliced mRNA. We also report that a high dose of either of two paralogue kinases, Kin1 and Kin2, overcomes the defective UPR caused by a mutation in the 3=BE. These results define a novel role for Kin kinases in the UPR beyond their role in cell polarity and exocytosis. Consistently, targeting, splicing, and translation of HAC1 mRNA are substantially reduced in the kin1� kin2� strain. Furthermore, we show that Kin2 kinase domain itself is sufficient to activate the UPR, suggesting that Kin2 initiates a signaling cascade to ensure an optimum UPR
Inhibition of nucleoporin member Nup214 expression by miR-133b perturbs mitotic timing and leads to cell death
Get PDFBackground: Nucleoporins mediate nucleocytoplasmic exchange of macromolecules and several have been assigned active mitotic functions. Nucleoporins can participate in various mitotic functions like spindle assembly, kinetochore organisation and chromosome segregation- important for genome integrity. Pathways to genome integrity are frequently deregulated in cancer and many are regulated in part by microRNAs. Indeed, altered levels of numerous microRNAs have frequently been associated with tumorigenesis. Here, we unveil a microRNA-mediated
regulation of the nucleoporin Nup214 and its downstream effect on genome integrity.
Methods: Databases/bioinformatic tools such as miRBase, Oncomine and RNAhybrid predicted Nup214 as a miR-133b
target. To validate this, we used luciferase reporter assays, Real-Time PCR and immuno-blotting. Flow cytometry and immuno-blots of mitotic markers were used to analyse cell cycle pattern upon thymidine synchronization and miR-133b treatment. Mitotic indices and chromosomal abnormalities were assessed by immuno-fluorescence for FITC-tagged phospho-H3 as well as video-microscopy for GFP-tagged histone H4. Annexin V/propidium iodide staining, caspase3/ PARP cleavage and colony formation assays were done to investigate cell death upon either miR-133b transfection or NUP214 knockdown by siRNA. UPCI:SCC084, HCT116, HeLa-H4-pEGFP and HEK293 (human oral squamous cell
carcinoma, colorectal, cervical carcinomas and embryonic kidney cell lines, respectively) were used. miR-133b and
NUP214 expressions were validated in cancer cell lines and tissues by Real-Time PCR.
Results: Examination of head and neck tumour tissues and cancer cell lines revealed that Nup214 and miR-133b
expressions are negatively correlated. In vitro, Nup214 was significantly downregulated by ectopic miR-133b. This
downregulation elevated mitotic indices and delayed degradation of mitotic marker proteins cyclinB1 and cyclinA
and dephosphorylation of H3. Moreover, this mitotic delay enhanced chromosomal abnormalities and apoptosis.
Conclusions: We have identified NUP214, a member of the massive nuclear pore complex, as a novel miR-133b
target. Thus, we have shown a hitherto unknown microRNA regulation of mitosis mediated by a member of the
nucleoporin family. Based on observations, we also raise some hypotheses regarding transport-dependent/independent
functions of Nup214 in this study. Our results hence attempt to explain why miR-133b is generally downregulated in tumours and lay out the potential for Nup214 as a therapeutic target in the treatment of cancer
A potent tumoricidal co-drug ‘Bet-CA’ - an ester derivative of betulinic acid and dichloroacetate selectively and synergistically kills cancer cells
No full textSelective targeting of cancer cells employing multiple combinations as co-drug holds promise for new generation therapeutics. Betulinic acid (BA), a plant secondary metabolite kills cancer cells and Dichloroacetate (DCA) is capable of reversing the Warburg phenotype by inhibiting pyruvate dehydrogenase kinase (PDK). Here, we report synthesis, characterization and tumoricidal potential of a co-drug Bet-CA, where a DCA molecule has been appended on C-3 hydroxyl group of BA to generate an ester derivative for increased solubility and subsequent cleavage by internal esterase(s) to release one unit each of BA and DCA. In vitro studies revealed pronounced synergistic cytotoxicity of Bet-CA against a broad spectrum of cancer cells and it selectively killed them when co-cultured with human fibroblasts. Bet-CA treatment increased reactive oxygen species (ROS) production, significantly altered mitochondrial membrane potential gradient (ΔΨm); followed by the release of cytochrome c (Cyt c) which prompted cells to undergo mitochondria mediated apoptosis. In vivo experimentation expectedly exhibited tumor inhibitory potential of Bet-CA and clinically achievable doses did not produce any apparent toxicity. Taken together, results suggestively raise an important corollary hypothesis stating that Bet-CA selectively and synergistically combats cancer without producing toxic manifestations and emerges to be the prospect for the new generation therapeutic
Role and regulation of RNA helicase p68 in cancer
No full textCancer is one of the leading causes of mortality despite significant advances in therapy and
diagnosis. Colorectal cancer ranks the fourth most common cause of morbidity worldwide. It
accounts for over 9% of all cancer incidences. It is the second most preventable cancer if
diagnosed early. For homeostasis of an organism, cell responds to various signaling cues to
regulate gene expression. Specific stimuli initiate a signaling cascade by binding to cell surface
receptors which convey the signal via several kinase and phosphatase proteins to downstream
transcription factors which ultimately leads to up or downregulation of specific genes. Aberrant
signaling networks deregulate gene expression profile, leading to cancer. Transcriptional
regulation attributes a major control on gene expressio
A Constrained Helical Peptide Against S100A4 Inhibits Cell Motility in Tumor Cells
No full textS100A4, a member of a calcium-regulated protein family,
is involved in various cellular signaling pathways.
From many studies over the last decade or so, it has
become clear that it is involved in tumor metastasis,
probably playing a determinative role. However, except
the phenothiazine group of drugs, no significant inhibitor
of S100A4 has been reported. Even the phenothiazines
are very weak inhibitors of S100A4 action. In this
study, we report design and development of a conformationally constrained helical peptide modeled on the
non-muscle myosin peptide that binds to S100A4. This
conformationally constrained peptide binds to S100A4
with a dissociation constant in the nanomolar range. We
also synthesized a peptide for experimental control that
bears several alanine mutations in the peptide–protein
interface. We demonstrate that the former peptide specifically inhibits motility of H1299 and MCF-7 cells in a
wound-healing assay. Structures of several S100A4–
ligand complexes suggest that it may be possible to
develop a smaller peptide–small molecule conjugate
having high affinity for S100A4. Peptide–drug conjugates
of this kind may play an important role in developing
drug leads against this antimetastasis targe
Novel Hexapeptide Interacts with Tubulin and Microtubules, Inhibits Aβ Fibrillation, and Shows Significant Neuroprotection
No full textHerein, we report a novel hexapeptide, derived from activity
dependent neuroprotective protein (ADNP),that spontaneously selfassembles to form antiparallel β-sheet structure and produces nanovesicles under physiological conditions. This peptide not only strongly binds with β-tubulin in the taxol binding site but also binds with the microtubule lattice in
vitro as well as in intracellular microtubule networks. Interestingly, it shows inhibition of amyloid fibril formation upon co-incubation with Aβ peptide following an interesting mechanistic pathway and excellent neuroprotection in PC12 cells treated with anti-nerve growth factor (NGF). The potential of this hexapeptide opens up a new paradigm in design and development of novel
therapeutics for AD