Role of Lipoproteins in the Pathophysiology of Breast Cancer.

Breast cancer is one of the most common malignancies in women and the leading cause of cancer mortality. Hypercholesterolemia and obesity are potential risk factors for the incidence of breast cancer, and their detection can enhance cancer prevention. In this paper, we discuss the current state of investigations on the importance of lipoproteins, such as low denisity lipoproteins (LDL) and high density lipoproteins (HDL), and cholesterol transporters in the progression of breast cancer, and the therapeutic strategies to reduce breast cancer mortality. Although some research has been unsuccessful at uncovering links between the roles of lipoproteins and breast cancer risk, major scientific trials have found a straight link between LDL levels and incidence of breast cancer, and an inverse link was found between HDL and breast cancer development. Cholesterol and its transporters were shown to have significant importance in the development of breast cancer in studies on breast cancer cell lines and experimental mice models. Instead of cholesterol, 27-hydroxycholesterol, which is a cholesterol metabolite, is thought to promote propagation and metastasis of estrogen receptor-positive breast cancer cell lines. Alteration of lipoproteins via oxidation and HDL glycation are thought to activate many pathways associated with inflammation, thereby promoting cellular proliferation and migration, leading to metastasis while suppressing apoptosis. Medications that lower cholesterol levels and apolipoprotein A-I mimics have appeared to be possible therapeutic agents for preventing excessive cholesterol's role in promoting the development of breast cancer.

Role of dietary iron revisited: in metabolism, ferroptosis and pathophysiology of cancer.

Iron is the most abundant metal in the human body. No independent life forms on earth can survive without iron. However, excess iron is closely associated with carcinogenesis by increasing oxidative stress via its catalytic activity to generate hydroxyl radicals. Therefore, it is speculated that iron might play a dual role in cells, by both stimulating cell growth and causing cell death. Dietary iron is absorbed by the intestinal enterocytes in the form of ferrous ion which forms cLIP. Excess iron stored in the form of Ferritin serves as a reservoir under iron depletion conditions. Ferroptosis, is an iron-dependent non-mutational form of cell death process and is suppressed by iron-binding compounds such as deferoxamine. Blocking transferrin-mediated iron import or recycling of iron-containing storage proteins (i.e., ferritin) also attenuates ferroptosis, consistent with the iron-dependent nature of this process. Unsurprisingly, ferroptosis also plays a role in the development of cancer and maybe a beneficial strategy for anticancer treatment. Different lines of evidence suggest that ferroptosis plays a crucial role in the suppression of tumorigenesis. In this review, we have discussed the pros and cons of iron accumulation, utilization and, its role in cell proliferation, ferroptosis and pathophysiology of cancer.

Novel antiviral effects of chloroquine, hydroxychloroquine, and green tea catechins against SARS CoV-2 main protease (Mpro) and 3C-like protease for COVID-19 treatment.

OBJECTIVES: Coronaviruses are globally emerging viruses that threaten our health care systems and have become a popular pandemic around the world. This causes a sudden rise in positive coronavirus cases and related deaths to occur worldwide, representing a significant health hazard to humans and the economy. METHODS: We examined predominantly catechins of green tea include epigallocatechin-3-gallate (EGCG), epicatechin-3-gallate (ECG), and drugs of chloroquine (CQ), and hydroxychloroquine (HCQ) appearing to reveal anti-viral activities. Data were collected from PubMed, Google Scholar, and Science Direct databases. To investigate the role of antiviral effects (CQ and HCQ), green tea catechins, beneficial use of convalescent plasma; covaxin in COVID-19 patients faced a dangerous healthiness issue. Computational docking analysis has been used for this purpose. RESULTS: The lead compounds are EGCG and ECG act as potential inhibitors bind to the active site region of the HKU4-CoV 3CL protease and M-Pro protease enzymes of coronavirus. Conclusions: SARS-COV-2 is a pathogen of substantial vigour concern and the review unveils the role of catechins associated with many viral diseases. We suggested that the function of green tea catechins, novel drugs of CQ, and HCQ exhibit antiviral activities against positive-sense single-stranded RNA viruses (CoVs).

Molecular docking analysis of imine stilbene analogs and evaluation of their anti-aging activity using yeast and mammalian cell models.

The NAD+-dependent histone deacetylase SIRT1 was shown to be associated with aging and longevity. A stilbene, resveratrol (RV) was shown to exert anti-aging activity by stimulating the SIRT1 activity. However, the utility of RV is limited by its low bioavailability and structural instability. It is thus envisaged to test imine stilbene (IMS) analogs of RV for their potential anti-aging activity. In the present study, molecular docking analysis of five IMS analogs (3a, 3b, 3c, 3d and 3e) against the SIRT1 protein has been carried out. All the five IMS analogs displayed enhanced binding affinity towards SIRT1; three out of five IMS analogs (3a, 3 b, 3e) showed significantly higher affinity with lower binding energies (-9.58, -9.54, and -9.82 kcal mol-1) than RV (-8.11 kcal mol-1). Further, experimental validation of anti-aging activity was performed by measuring the chronological life span in vitro using yeast and cellular replicative senescence (CRS) in mammalian cell line models. All IMS analogs extended the chronological life span in yeast as compared to untreated cells as well as RV treated cells. Enhanced anti-aging activity was also observed in an analogous mammalian cell line model upon treatment with either RV or IMS analogs. The results thus suggest that most of the IMS analogs tested may serve as potent drug lead molecules with anti-aging activity.

Characterization and molecular modeling of polygalacturonase isoforms from Saccharomyces cerevisiae.

Earlier, low-temperature-active polygalacturonase isoforms from Saccharomyces cerevisiae PVK4 were isolated and purified. Substrate specificity of polygalacturonase isoforms indicated high affinity for pectins and very low enzyme activity towards non-pectic polysaccharides. To characterize the polygalacturonase isoforms, biochemical, spectral, and in silico approaches were used. The apparent Km and Vmax values for hydrolysis of pectin and galacturonic acid were 0.31 mg/ml and 3.15 mmol min/mg, respectively. Interestingly, the polygalacturonase isoforms were found to be more stable at optimal pH and temperature of 4.5 and 40 °C, respectively. These isoforms were reacted with different metal ions; Cd2+ and Ni2+ severely inhibited the enzyme activity, while Mg2+, Zn2+, Cd2+, Fe2+ Cu2+, and Ni2+ inhibited to a lesser extent, which clearly demonstrated that variations in enzyme activity were due to their differential binding affinity of metal ions. Furthermore, decrease in the viscosity of polygalacturonic acid and citrus pectin by these isoforms was approximately four and six times higher than the rate of release of reducing sugars. This indicates that polygalacturonase isoforms have an endo-mode of action. In addition to the above, thermostability of purified polygalacturonase isoforms was studied by circular dichroism and fluorescence spectroscopy. Circular dichroism showed 18% alpha helix and 57% beta sheets at pH 5, while at pH 7, 8, and 9 there was an increase of random coil. Fluorescence studies revealed small conformational changes, which were observed at 30-50 °C, while unfolding transition region was noticed between 60 and 70 °C. The purified enzyme fractions were analyzed by MALDI-TOF MS. Finally, 3D model structures for isoenzymes of polygalacturonase of S. cerevisiae were generated and validated as good quality models, which are also suitable for molecular interaction studies.

ß-N-oxalyl-L-α, ß- diaminopropionic acid induces HRE expression by inhibiting HIF-prolyl hydroxylase-2 in normoxic conditions.

Hypoxia inducible factor (HIF)-1α, a subunit of HIF transcription factor, regulates cellular response to hypoxia. In normoxic conditions, it is hydroxylated by prolyl hydroxylase (PHD)-2 and targeted for proteosomal degradation. Drugs which inhibit PHD-2 have implications in conditions arising from insufficient blood supply. ß-ODAP (ß-N- oxalyl-L-α, ß- diaminopropionic acid), a non-protein excitatory amino acid present in Lathyrus sativus, is an α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor agonist known to activate conventional protein kinase C and stabilize HIF-1α under normoxic conditions. However, the mechanism of HIF-1α stabilization by this compound is unknown. In silico approach was used to understand the mechanism of stabilization of HIF-1α which revealed ß-ODAP interacts with key amino acid residues and Fe2+ at the catalytic site of PHD-2. These results were further corroborated with luciferase HRE (hypoxia response element) reporter system in HeLa cells. Different chemical modulators of PHD-2 activity and HIF-1α levels were included in the study for comparison. Results obtained indicate that ß-ODAP inhibits PHD-2 and facilitates HIF dependent HRE expression and hence, might be helpful in conditions arising from hypoxia.

Effects of ellipticine on ALDH1A1-expressing breast cancer stem cells--an in vitro and in silico study.

Targeting breast cancer stem cells (BCSCs) offers a promising strategy for breast cancer treatment. We examined the plant alkaloid ellipticine for its efficacy to inhibit the expression of aldehyde dehydrogenase 1 class A1 (ALDH1A1)-positive BCSCs by in vitro and in silico methods. At 3 mM concentration, ellipticine decreased the expression of ALDH1A1-positive BCSCs by 62% (p = 0.073) in the MCF7 cell line and by 53% (p = 0.024) in the SUM159 cell line compared to vehicle-treated cultures. Ellipticine significantly reduced the formation of mammospheres, whereas paclitaxel enhanced mammosphere formation in both the treated cell lines. Interestingly, when treated with a combination of ellipticine and paclitaxel, the percentage of ALDH1A1-positive BCSCs dropped by several fold in vitro. A homology model of Homo sapiens ALDH1A1 was built using the crystal structure of NAD-bound sheep liver class I aldehyde dehydrogenase [PDB ID: 1BXS] as a template. Molecular simulation and docking studies revealed that the amino acids Asn-117 and Asn-121, Glu-249, Cys-302, and Gln-350, present in the active site of human ALDH1A1, played a vital role in interacting with the drug. The present study suggests that ellipticine reduces the proliferation and self-renewal ability of ALDH1A1-positive BCSCs and can be used in combination with a cytotoxic drug like paclitaxel for potential targeting of BCSCs.

Molecular docking and dynamics simulations of A.niger RNase from Aspergillus niger ATCC26550: for potential prevention of human cancer.

The aim of the present research was to study the anticancer effects of Aspergillus niger (A.niger) RNase. We found that RNase (A.niger RNase) significantly and dose dependently inhibited invasiveness of breast cancer cell line MDA MB 231 by 55 % (P<0.01) at 1 µM concentration. At a concentration of 2 µM, the anti invasive effect of the enzyme increased to 90 % (P<0.002). Keeping the aim to determine molecular level interactions (molecular simulations and protein docking) of human actin with A.niger RNase we extended our work in-vitro to in-silico studies. To gain better relaxation and accurate arrangement of atoms, refinement was done on the human actin and A.niger RNase by energy minimization (EM) and molecular dynamics (MD) simulations using 43A(2) force field of Gromacs96 implemented in the Gromacs 4.0.5 package, finally the interaction energies were calculated by protein-protein docking using the HEX. These in vitro and in-silico structural studies prove the effective inhibition of actin activity by A.niger RNase in neoplastic cells and thereby provide new insights for the development of novel anti cancer drugs.

Protein-protein docking on molecular models of Aspergillus niger RNase and human actin: novel target for anticancer therapeutics.

The 3D models of human actin protein and A.niger RNase were designed using the templates ACTBIND (PDB ID: 3D3Z) and crystalline profilin-beta-actin (PDB ID: 2BTF), respectively in Modeller9v5. These models are testified using several validation methods including PROCHECK, ERRAT, WHAT-IF, PROSA2003 and VERIFY-3D. The stereo-chemical quality of the models was judged by Ramachandran plot with PROCHECK. The total quality G-factor -0.2, shows a good quality model. The ERRAT score for the human actin and A.niger RNase models are 86.104 and 84.615, respectively, fit well within the range of a high quality model. The ERRAT score for the templates 2BTF and 3D3Z are 91.111 and 97.391, respectively. The WHAT-IF evaluation justifies a reasonable homology model structure as none of the scores for each residue in the homology model is lower than -5.0. The energy-minimized model of human actin with PROSA reveals the Z-score value -10.52 between native conformations of the crystal structures. The VERIFY 3D average score is 0.36. All evidence suggests that the geometric quality of the backbone conformation, the residue interaction, the residue contact and the energy profile of the structures were well within the limits of reliable structures. The interaction energy of docking was calculated using the HEX server. The Etotal, lowest docked energy, and calculated RMSD values were -1.608 kcal mol(-1), -8.369 kcal mol(-1) and 0.617 Å, respectively. The study presented in the current project may be useful to design molecules that may have anticancer activity.