Rashmi Bharti

Cancer development, chemoresistance, epithelial to mesenchymal transition and stem cells: A snapshot of IL-6 mediated involvement

Interleukin-6 (IL-6) is a cytokine present in tumor microenvironment. Elevated level of IL-6 is associated with cancer cell proliferation, angiogenesis and metastasis through fueling STAT3, MAPK and Akt signaling. It promotes epithelial to mesenchymal transition (EMT) through altered expression of N-cadherin, vimentin, snail, twist and E-cadherin leading to cancer metastasis. IL-6 boosts mammosphere formation, self-renewal of stem cells, stemness properties of cancer cells and recruitment of mesenchymal stem cells. IL-6 is also a contributing factor for multidrug resistance in cancer due to gp130/MAPK/STAT3 mediated activation of transcription factors C/EBPβ/δ, overexpression of p-glycoprotein, EMT transition and expansion of stem cells. The in-depth investigation of IL-6 mediated cellular effects and its signaling pathway can provide the new window for future research and clinical development of IL-6 targeted therapy in cancer. Thus, an overview is delivered in this review deciphering the emerging aspect of the predominant influence of IL-6 in malignant transformation, EMT, cancer-associated stem cells and chemoresistance.

Marine lipopeptide Iturin A inhibits Akt mediated GSK3β and FoxO3a signaling and triggers apoptosis in breast cancer

Akt kinase is a critical component of the PI3K/Akt signaling pathway, which is frequently over expressed in human cancers including breast. Therapeutic regimens for inhibiting breast cancer with aberrant Akt activity are essential. Here, we evaluated antitumor effect of a marine bacteria derived lipopeptide ‘Iturin A’ on human breast cancer in vitro and in vivo through disrupting Akt pathway. Proliferation of MDA-MB-231 and MCF-7 breast cancer cells were significantly inhibited by Iturin A and it induced apoptosis as confirmed by increased Sub G1 populations, DNA fragmentation, morphological changes and western blot analysis. Furthermore, Iturin A inhibited EGF induced Akt phosphorylation (Ser473 and Thr308) and its downstream targets GSK3β and FoxO3a. Iturin A inactivated MAPK as well as Akt kinase leading to the translocation of FoxO3a to the nucleus. Gene silencing of Akt in MDA-MB-231 and MCF-7 cells reduced the sensitivity of cancer cells to Iturin A. Interestingly, overexpression of Akt with Akt plasmid in cancer cells caused highly susceptible to induce apoptosis by Iturin A treatment. In a xenograft model, Iturin A inhibited tumor growth with reduced expressions of Ki-67, CD-31, P-Akt, P-GSK3β, P-FoxO3a and P-MAPK. Collectively, these findings imply that Iturin A has potential anticancer effect on breast cancer.

Microbial amphiphiles: a class of promising new-generation anticancer agents

Developing new classes of anticancer molecules has always been a major scientific challenge owing to multidrug resistance of cancer cells to conventional chemotherapeutic agents. Microbial amphiphiles, particularly lipopeptides and glycolipids, have recently emerged as potential new-generation anticancer agents, owing to low toxicity, high efficacy and easy biodegradability. They exhibit anticancer activities by retarding cell cycle progression, inhibiting crucial signaling pathways such as Akt, extracellular signal-regulated kinase/c-Jun N-terminal kinase (ERK/JNK) and Janus kinase/signal transducer and activator of transcription (JAK/STAT), reducing angiogenesis, activating natural killer T (NKT) cells and inducing apoptosis through death receptors in cancer cells. It has been well established that the oncogenic signals of cancer cells are amplified by the overexpression of various membrane-bound receptors such as epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR) and insulin-like growth factor receptor (IGFR). Microbial amphiphiles, upon interaction with the cell membrane, are believed to suppress the activities of these cell surface receptors by fatty acid chain mediated membrane destabilization. This review analyzes the modes and mechanisms of action of these green molecules for application as potential anticancer agents.

Identification of multifunctional peptides from human milk.

Pharmaceutical industries have renewed interest in screening multifunctional bioactive peptides as a marketable product in health care applications. In this context, several animal and plant peptides with potential bioactivity have been reported. Milk proteins and peptides have received much attention as a source of health-enhancing components to be incorporated into nutraceuticals and functional foods. By using this source, 24 peptides have been fractionated and purified from human milk using RP-HPLC. Multifunctional roles including antimicrobial, antioxidant and growth stimulating activity have been evaluated in all 24 fractions. Nevertheless, only four fractions show multiple combined activities among them. Using a proteomic approach, two of these four peptides have been identified as lactoferrin derived peptide and kappa casein short chain peptide. Lactoferrin derived peptide (f8) is arginine-rich and kappa casein derived (f12) peptide is proline-rich. Both peptides (f8 and f12) showed antimicrobial activities against both Gram-positive and Gram-negative bacteria. Fraction 8 (f8) exhibits growth stimulating activity in 3T3 cell line and f12 shows higher free radical scavenging activity in comparison to other fractions. Finally, both peptides were in silico evaluated and some insights into their mechanism of action were provided. Thus, results indicate that these identified peptides have multiple biological activities which are valuable for the quick development of the neonate and may be considered as potential biotechnological products for nutraceutical industry.

Tailor-Made Temperature-Sensitive Micelle for Targeted and On-Demand Release of Anticancer Drugs

The design of nanomedicines from the tuned architecture polymer is a leading object of immense research in recent years. Here, smart thermoresponsive micelles were prepared from novel architecture four-arm star block copolymers, namely, pentaerythritol polycaprolactone-b-poly(N-isopropylacrylamide) and pentaerythritol polycaprolactone-b-poly(N-vinylcaprolactam). The polymers were synthesized and tagged with folic acid (FA) to render them as efficient cancer cell targeting cargos. FA-conjugated block copolymers were self-assembled to a nearly spherical (ranging from 15 to 170 nm) polymeric micelle (FA-PM) with a sufficiently lower range of critical micelle concentration (0.59 × 10(-2) to 1.52 × 10(-2) mg/mL) suitable for performing as an efficient drug carrier. The blocks show lower critical solution temperature (LCST) ranging from 30 to 39 °C with high DOX-loading content (24.3%, w/w) as compared to that reported for a linear polymer in the contemporary literature. The temperature-induced reduction in size (57%) of the FA-PM enables a high rate of DOX release (78.57% after 24 h) at a temperature above LCST. The DOX release rate has also been tuned by on-demand administration of temperature. The in vitro biocompatibilities of the blank and DOX-loaded FA-PMs have been studied by the MTT assay. The cellular uptake study proves selective internalization of the FA-PM into cancerous cells (C6 glioma) compared that into normal cells (HaCaT). In vivo administration of the DOX-loaded FA-PMs into the C6 glioma rat tumor model resulted in significant accumulation in tumor sites, which drastically inhibited the tumor volume by ∼83.9% with respect to control without any significant systemic toxicity.

Self-assembled cardanol azo derivatives as antifungal agent with chitin-binding ability

Cardanol is a non-isoprenoic phenolic lipid-mixture of distilled cashew nut shell liquid obtained from Anacardium occidentale. Herein, cardanol is purified from cashew nut shell liquid (CNSL) and synthesized to new compounds with different azo amphiphiles. These synthesized compounds are allowed to self-assembled in hydrophobic environment and checked antifungal activity against Candida albicans. Self-assembled structure of CABA showed higher antifungal activity (16μg/mL) and chitin-binding ability in comparison to CAP and CANB. Furthermore, the self-assembled azo amphiphiles are immobilized with silver ions to prepare hydrogel which showed eight folds enhanced antifungal activity. Toxicity is reduced by several folds of self-assembled or hydrogel structure in comparison to pure compounds. Thus, the self-assembled structure of amphiphiles and their hydrogels have been found to be new macromolecules of interest with potential use as antifungal drugs.

Diacerein-mediated inhibition of IL-6/IL-6R signaling induces apoptotic effects on breast cancer

Interleukin-6 (IL-6) signaling network has been implicated in oncogenic transformations making it attractive target for the discovery of novel cancer therapeutics. In this study, potent antiproliferative and apoptotic effect of diacerein were observed against breast cancer. In vitro apoptosis was induced by this drug in breast cancer cells as verified by increased sub-G1 population, LIVE/DEAD assay, cell cytotoxicity and presence of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells, as well as downregulation of antiapoptotic proteins Bcl-2 and Bcl-xL and upregulation of apoptotic protein Bax. In addition, apoptosis induction was found to be caspase dependent. Further molecular investigations indicated that diacerein instigated apoptosis was associated with inhibition of IL-6/IL-6R autocrine signaling axis. Suppression of STAT3, MAPK and Akt pathways were also observed as a consequence of diacerein-mediated upstream inhibition of IL-6/IL-6R. Fluorescence study and western blot analysis revealed cytosolic accumulation of STAT3 in diacerein-treated cells. The docking study showed diacerein/IL-6R interaction that was further validated by competitive binding assay and isothermal titration calorimetry. Most interestingly, it was found that diacerein considerably suppressed tumor growth in MDA-MB-231 xenograft model. The in vivo antitumor effect was correlated with decreased proliferation (Ki-67), increased apoptosis (TUNEL) and inhibition of IL-6/IL-6R-mediated STAT3, MAPK and Akt pathway in tumor remnants. Taken together, diacerein offered a novel blueprint for cancer therapy by hampering IL-6/IL-6R/STAT3/MAPK/Akt network.

Overcoming Akt Induced Therapeutic Resistance in Breast Cancer through siRNA and Thymoquinone Encapsulated Multilamellar Gold Niosomes.

Akt overexpression in cancer causes resistance to traditional chemotherapeutics. Silencing Akt through siRNA provides new therapeutic options; however, poor in vivo siRNA pharmacokinetics impede translation. We demonstrate that acidic milieu-sensitive multilamellar gold niosomes (Nio-Au) permit targeted delivery of both Akt-siRNA and thymoquinone (TQ) in tamoxifen-resistant and Akt-overexpressing MCF7 breast cancer cells. Octadecylamine groups of functionalized gold nanoparticles impart cationic attribute to niosomes, stabilized through polyethylene glycol. TQs aqueous insolubility renders its encapsulation within hydrophobic core, and negatively charged siRNA binds in hydrophilic region of cationic niosomes. These niosomes were exploited to effectively knockdown Akt, thereby sensitizing cells to TQ. Immunoblot studies revealed enhanced apoptosis by inducing p53 and inhibiting MDM2 expression, which was consistent with in vivo xenograft studies. This innovative strategy, using Nio-Au to simultaneously deliver siRNA (devoid of any chemical modification) and therapeutic drug, provides an efficacious approach for treating therapy-resistant cancers with significant translational potential.

Correction: Dietary flavone chrysin (5,7-dihydroxyflavone ChR) functionalized highly-stable metal nanoformulations for improved anticancer applications

Nanomaterials of noble metals with unique size, shape and composition receives much attention owing to their versatile functionality in personalized cancer nanomedicine. Chrysin (ChR), a natural anticancer bioflavonoid, emerged as a potential drug therapy for almost all types of cancer, however it has poor solubility and bioavailability. Herein, we report a new approach to formulate biofunctionalized metallic silver (ChR–AgNPs) and gold (ChR–AuNPs) nanoparticles using ChR as a direct bioreductant and capping agent. Size and dispersity of nanoparticles (NPs) were controlled through fixing different reaction conditions such as the temperature, pH, concentration of metal ion, stoichiometric proportion of the reaction mixture and incubation time based on their optical properties and SPR effect in UV-visible spectroscopy. The role of hydroxyl and carbonyl groups in functionalizing the metal ions with ChR was confirmed with Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. It was also substantiated that the oxygen group from ChR donates electrons to metal ion and results in complexation; ionic Ag+ and Au3+ were reduced to Ag0 and Au0 nano-forms. The physiochemical state of obtained NPs was characterized through different exclusive instrumentation, which shows the presence of highly-stable, spherical, crystalline ChR–AgNPs and ChR–AuNPs with an average size of 14 ± 6 nm and 6 ± 2 nm respectively. In vitro anticancer results revealed that the formulated metallic NPs exhibit enhanced cytotoxicity over ChR in the treatment of two different breast carcinoma cell lines (MDA-MB-231 and MDA-MB-468). Furthermore, it was evident that the NPs cause cell death via the induction of apoptosis. A hemolysis assay with human erythrocytes demonstrates good blood biocompatibility of the NPs. Thus, the ChR functionalized metal NPs can be potentially employed as a combinational drug-nano platform for breast cancer therapy.

Mechanistic attributes of S100A7 (psoriasin) in resistance of anoikis resulting tumor progression in squamous cell carcinoma of the oral cavity

BackgroundSquamous cell carcinoma of the oral cavity (SCCOC) is the dominant origin of cancer associated mortality. Previous findings by our study reported that acquisition of anoikis resistance has a significant role in tumor progression of oral cavity. Several genes were over-expressed in anoikis-resistant cells under detached conditions which we confirmed earlier by microarray. Normal oral squamous epithelia grow adherent to a basement membrane, and when detached from the extracellular matrix, undergoes programmed cell death. The acquisition of anoikis-resistance is crucial phenomena in oral tumor advancement. In the current study, we have identified S100A7 expression as contributing factor for anoikis resistance and tumorigenicity in human oral cancer cells. Further, we have explored that elevated S100A7 expression in anoikis-sensitive oral keratinocytes and cancer cells reshape them more resistant to anoikis and apoptosis inducers via activation of cellular intrinsic and extrinsic avenue.MethodsA subset of human cancer cell lines TU167, JMAR, JMARC39, JMARC42 and MDA-MB-468 were utilized for the generation of resistant stable cell lines. Further, immunohistochemistry, western blot and immunoprecipitation, assays of apoptosis, soft agar assay, orthotopic animal model and signaling elucidation were performed to establish our hypothesis.ResultsS100A7 gene is found to be responsible for anoikis resistance and tumorigenicity in human oral cancer cells. We have observed up-regulation of S100A7 in anoikis resistant cell lines, orthotropic model and patients samples with head and neck cancer. It is also noticed that secretion of S100A7 protein in conditioned medium by anoikis resistant head & neck cancer cell and in saliva of head and neck cancer patients. Up-regulation of S100A7 expression has triggered enhanced tumorigenicity and anchorage-independent growth of cancer cells through Akt phosphorylation leading to development of aniokis resistance in head and neck cancer cells.ConclusionsThese data have led us to conclude that S100A7 is the major contributing factor in mediating anoikis-resistance of oral cancer cells and local tumor progression, and S100A7 might be useful as diagnostic marker for early detection of primary and recurrent squamous cell cancer.