Growth Factor Receptors and Apoptosis Regulators: Signaling Pathways, Prognosis, Chemosensitivity and Treatment Outcomes of Breast Cancer

Biomarkers of breast cancer are necessary for prognosis and prediction to chemotherapy. Prognostic biomarkers provide information regarding outcome irrespective of therapy, while predictive biomarkers provide information regarding response to therapy. Candidate prognostic biomarkers for breast cancers are growth factor receptors, steroid receptors, Ki-67, cyclins, urokinase plasminogen activator, p53, p21, pro- and anti-apoptotic factors, BRCA1 and BRCA2. But currently, the predictive markers are Estrogen and Progesterone receptors responding to endocrine therapy, and HER-2 responding to herceptin. But there are numerous breast cancer cases, where tamoxifen is ineffective even after estrogen receptor positivity. This lead to search of new prognostic and predictive markers and the number of potential markers is constantly increasing due to proteomics and genomics studies. However, most biomarkers individually have poor sensitivity or specificity, or other clinical value. It can be resolved by studying various biomarkers simultaneously, which will help in better prognosis and increasing sensitivity for chemotherapeutic agents. This review is focusing on growth factor receptors, apoptosis markers, signaling cascades, and their correlation with other associated biomarkers in breast cancers. As our knowledge regarding molecular biomarkers for breast cancer increases, prognostic indices will be developed that combine the predictive power of individual molecular biomarkers with specific clinical and pathologic factors. Rigorous comparison of these existing as well as emerging markers with current treatment selection is likely to see an escalation in an era of personalized medicines to ensure the breast cancer patients receive optimal treatment. This will also solve the treatment modalities and complications related to chemotherapeutic regimens

Bcl-2 modulates telomerase activity

Apoptosis is a physiological mechanism of cell death that plays an important role in the regulation of tissue homeostasis. The regulation of apoptosis is a complex process and involves a number of gene products including the survival factor Bcl-2, which has been found to be frequently deregulated in human cancers. In addition to deregulation of apoptosis, the process of neoplasia is also believed to be driven by the activation of telomerase, a ribonucleoprotein complex that adds telomeric repeats (hexanucleotide 5′-TTAGGG-3′) to the ends of replicating chromosomes. Activation of telomerase has been detected in a vast majority of human cancer cells. Although recent studies have demonstrated the wide occurrence of telomerase activation and Bcl-2 deregulation in human cancer cells, it remains unclear whether there is any linkage between the deregulation of Bcl-2 and telomerase activity in cancer cells. In the studies presented here, we report that the stable overexpression of Bcl-2 in human cancer cells with low Bcl-2 expression was accompanied by increased levels of telomerase activity. In addition, using an IL-2-dependent cytotoxic T-cell line, CTLL-2, we demonstrated that IL-2 deprivation (8 h), which is known to down-regulate Bcl-2 expression, also resulted in concurrent inhibition of telomerase activity in the absence of any detectable apoptosis and accumulation of cells in the G0/G1phase of the cell cycle. Re-exposure of IL-2-deprived CTLL-2 cells to the recombinant IL-2 led to the up-regulation of both Bcl-2 expression and telomerase activity. Taken together, these findings establish a close linkage between the modulation of telomerase activity by survival factor Bcl-2, and provide a model to study regulation of telomerase activity by an anti-apoptotic pathway that is widely deregulated in cancer cells

Antiproliferative Effects of Honey and of Its Polyphenols: A Review

Honey has been used since long time both in medical and domestic needs, but only recently the antioxidant property of it came to limelight. The fact that antioxidants have several preventative effects against different diseases, such as cancer, coronary diseases, inflammatory disorders, neurological degeneration, and aging, led to search for food rich in antioxidants. Chemoprevention uses various dietary agents rich in phytochemicals which serve as antioxidants. With increasing demand for antioxidant supply in the food, honey had gained vitality since it is rich in phenolic compounds and other antioxidants like ascorbic acid, amino acids, and proteins. Some simple and polyphenols found in honey, namely, caffeic acid (CA), caffeic acid phenyl esters (CAPE), Chrysin (CR), Galangin (GA), Quercetin (QU), Kaempferol (KP), Acacetin (AC), Pinocembrin (PC), Pinobanksin (PB), and Apigenin (AP), have evolved as promising pharmacological agents in treatment of cancer. In this review, we reviewed the antiproliferative and molecular mechanisms of honey and above-mentioned polyphenols in various cancer cell lines

Azurin synthesis from pseudomonas aeruginosa MTCC 2453, properties, induction of reactive oxygen species and p53 stimulated apoptosis in breast carcinoma cells

Breast cancers are usually treated with surgery and radiation excretes adverse effects. Azurin, a potent anticancer redox protein secreted by Pseudomonas aeruginosa (P. aeruginosa) species has been reported to have activity against breast cancer cell lines; this had prompted researchers to search for novel methods to enhance this protein's production. Researchers previously have reported on the synthesis of blue copper protein azurin from different microbial sources specifically from P. aeruginosa. Our investigation used customized methods to focus on synthesizing azurin from different strains of P. aeruginosa with apparent homogeneity. We screened the growth of different P. aeruginosa strains (1934, 741, 2453 and 1942) for the synthesis of azurin and for enhanced azurin production. We exposed azurin properties using matrix-assisted laser desorption/ionization, sodium dodecyl sulfate polyacrylamide gel electrophoresis and Fourier transform infrared spectroscopy. Additional studies of possible molecular mechanisms and Reactive Oxygen Species (ROS) generation of P. aeruginosa 2453 secreted azurin are needed. We examined which strain among P. aeruginosa strains 1934, 741, 2453 and 1942 best enhanced azurin production. Our current study also revealed which strain of the four had the strongest antiproliferative effect of azurin. P. aeruginosa MTCC (Microbial Type Culture Collection) 2453 was the strain that secreted the most azurin and showed remarkable apoptosis in breast carcinoma cells like T- 47D and ZR-75-1. This study demonstrates customized methods to synthesize azurin from different strains of P. aeruginosa with apparent homogeneity and their apoptotic effects on breast carcinoma cells with possible molecular mechanisms and ROS

Nuclear targeting of Bax during apoptosis in human colorectal cancer cells

Homeostasis in colonic epithelial cells is regulated by the balance between proliferative activity and cell loss by apoptosis. Because epithelial cells at the apex of colonic crypts undergo apoptosis and proliferative activity is usually restricted to the base of the crypts, it has been proposed that the limited availability of growth factor-signals at the upper portions of the crypts may trigger apoptosis. In the present studies, we investigate the mechanism of apoptosis mediated by growth factor deprivation in colorectal carcinoma cells by delineating the possible involvement of Bax and its subcellular localization. We report that inhibition of Epidermal Growth Factor Receptor (EGFR) tyrosine kinase activity and downregulation of EGFR by anti-EGFR mAb 225 induces apoptosis in human colorectal carcinoma DiFi and FET cells. Induction of apoptosis was preceded by enhanced expression of newly synthesized Bax protein, and required protein synthesis. In the mAb 225-treated cells, Bax was redistributed from the cytosol to the nucleus and subsequently, to the nuclear membranes. The observed induction of Bax expression by mAb 225 was not associated with p53 induction. However, mAb 225 treatment also triggered relocalization of p53 from the cytosol to a nuclear membrane-bound form. Induction of Bax and its redistribution to the nucleus of DiFi cells during apoptosis was also demonstrated in response to butyrate, a physiological relevant molecule in colonic epithelial cells as it is the principal short-chain fatty acid produced by bacterial fermentation of dietary fiber in colonic epithelium. Using immunofluorescence and confocal microscopy, we observed that Bax is predominantly localized in the cytosol, but during apoptosis it is localized both inside and along the nuclear membrane. Taken together, these findings suggest that apoptosis induced by growth factor-deprivation or butyrate may involve the subcellular redistribution of Bax in human colorectal carcinoma cells

Heregulin induces expression, DNA binding activity and transactivating functions of basic leucine zipper activating transcription factor 4

Heregulin β1 (HRG), a combinatorial ligand for human epidermal growth factor receptor 3 and human epidermal growth factor receptor 4 receptors, is a regulatory secretory polypeptide with distinct biological effects such as growth stimulation, differentiation, invasiveness and migration in breast cancer cells. The mechanism underlying the diverse functions of HRG is not well established, but it is believed to be dependent on the induced changes in expression of specific cellular gene products, their modification, or both. The binding of basic leucine zipper transcription factors to the cAMP response element is known to activate a variety of gene products with a role or roles in growth regulation. In the studies presented here, we identified basic leucine zipper Activating Transcription Factor (ATF) 4 as one of the HRG-inducible gene product. We demonstrated that HRG stimulation of human cancer cells induces expression of ATF4 mRNA and protein, ATF4 DNA binding activity and ATF4 transactivating function. Consistent with its role as a transcriptional activator, HRG-stimulated ATF4 protein stimulated the transcription from an artificial promoter with three tandem ATF sites or from a naturally occurring promoter with ATF4 sites such as E-selectin. We also demonstrated a preferential role of the HRG-stimulated mitogen-activated protein kinase pathway, but not the phosphatidylinositol 3′-kinase pathway, in supporting the observed increase in ATF4 DNA binding activity and transcription from E-selectin promoter in HRG-stimulated cells. Because ATF4 binding sites are present in a variety of growth-regulating cellular genes, these findings suggest that the stimulation of ATF4 expression and its transactivating functions may constitute an important mechanism of HRG-mediated regulation of putative genes with diversified functions. The present study is the first demonstration of regulation of expression and transactivation ability of ATF4 by any polypeptide growth factor

Biocompatible L-Cysteine Capped MoS2_2 Nanoflowers for Antibacterial Applications: Mechanistic Insights

The development of multi-drug-resistant bacterial infections seriously threatens public health, so efforts are needed to develop a new class of safe and effective antibacterial agents. Here, we report a bio-inspired synthesis of surface-modified MoS$_2$ Nanoflowers with L-cysteine (MoS$_2$-cys NFs) that show good colloidal stability in an aqueous medium. The FE-SEM and TEM data confirm the flower-like morphology and determine the size of NFs (537+-12 nm); the XRD data predicts the hexagonal crystal structure of the NFs. The XPS peaks confirm the formation of MoS$_2$ NFs with surface modification by L-cysteine. FTIR measurements also confirm the presence of L-cysteine in the NFs. The antibacterial activity of as-prepared MoS$_2$-cys NFs examined over gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria shows inhibition of nearly 97% and 90%, respectively, at concentrations 250 $\mu$g/mL each after incubation of 6 hrs. The antibacterial mechanism is mainly attributed to the generation of oxidative stress, which can occur through both ROS-dependent and ROS-independent pathways. The ROS-dependent and ROS-independent oxidative stresses were measured using flow cytometry and fluorescence imaging using DCFH-DA staining, and Ellman's assay, respectively. Moreover, the toxicity studies of the MoS$_2$-cys NFs towards HFF cell lines suggested the high biocompatibility of the nanomaterial with a cell viability of nearly 90%. We report the intrinsic antibacterial efficiency of MoS$_2$-cys NFs without any external stimulus (light, H2O2, etc.), doping, or drug loading. Our study indicates that the proper surface modification can enhance the colloidal stability and antibacterial potency of MoS$_2$-based nanomaterials for further applications such as antibacterial coatings, water disinfection, and wound healing.Comment: 32 pages, 9 figures and 1 tabl