Tim4 enables large peritoneal macrophages to cross-present tumor antigens at early stages of tumorigenesis.

Receptors controlling the cross-presentation of tumor antigens by macrophage subsets in cancer tissues are poorly explored. Here, we show that TIM4+ large peritoneal macrophages efficiently capture and cross-present tumor-associated antigens at early stages of peritoneal infiltration by ovarian cancer cells. The phosphatidylserine (PS) receptor TIM4 promotes maximal uptake of dead cells or PS-coated artificial targets and triggers inflammatory and metabolic gene programs in combination with cytoskeletal remodeling and upregulation of transcriptional signatures related to antigen processing. At the cellular level, TIM4-mediated engulfment induces nucleation of F-actin around nascent phagosomes, delaying the recruitment of vacuolar ATPase, acidification, and cargo degradation. In vivo, TIM4 deletion blunts induction of early anti-tumoral effector CD8 T cells and accelerates the progression of ovarian tumors. We conclude that TIM4-mediated uptake drives the formation of specialized phagosomes that prolong the integrity of ingested antigens and facilitate cross-presentation, contributing to immune surveillance of the peritoneum.

Conformational stability of peroxidase from the latex of Artocarpus lakoocha: influence of pH, chaotropes, and temperature.

The latex of the medicinal plant Artocarpus lakoocha (A. lakoocha), which has been shown to have potential anti-inflammatory and wound-healing capabilities, contains a novel heme-peroxidase. This protein was subjected to activity assays, fluorescence spectroscopy, and far-UV circular dichroism to investigate its structure, dynamics, and stability. The results demonstrated the presence of three folding states: the native state (N) at neutral pH, intermediate states including molten globule (MG) at pH 2 and acid-unfolded (UA) at pH 1.5 or lower, and acid-refolded (A) at pH 0.5, along with alkaline denatured (UB) at pH 8-12 and the third denatured state (D) at GuHCl concentrations exceeding 5 M. Absorbance studies indicated the presence of loosely associated form of heme in the pH range of 1-2. The protein showed stability and structural integrity across a wide pH range (3-10), temperature (70°C), and high concentrations of GuHCl (5 M) and urea (8 M). This study is the first to report multiple 'partially folded intermediate states' of A. lakoocha peroxidase, with varying amounts of secondary structure, stability, and compactness. These results demonstrate the high stability of A. lakoocha peroxidase and its potential for biotechnological and industrial applications, making it a valuable model system for further studies on its structure-function relationship.

RNA interference therapeutics for cardiac regeneration.

There is an impelling need to develop new therapeutics for myocardial infarction and heart failure. A novel and exciting therapeutic possibility is to achieve cardiac regeneration through the stimulation of the endogenous capacity of cardiomyocytes to proliferate. Proof-of-concept evidence of microRNA-induced cardiac regeneration is available in both small and large animals using viral vectors. However, a clinically more applicable strategy is the development of lipid-mediated nanotechnologies for the administration of RNA therapeutics as synthetic molecules. The recent success of the Stable Nucleic Acid Lipid Particle (SNALP) platform for the generation of nanosized, efficient and non-inflammatory lipid nanoparticles paves the way to the development of injectable nanoformulations of microRNAs through cardiac catheterisation.

Targeting polyamine biosynthetic pathway through RNAi causes the abrogation of MCF 7 breast cancer cell line.

The diamine putrescine and polyamines, spermidine (triamine) and spermine (tetraamine) are small organic polycations that play an indispensable role in key cellular processes such as the regulation of growth, differentiation, and macromolecular functions. Elevated levels of polyamines (PAs) have been shown to be one of the major factors involved in carcinogenesis. In this study, specific silencing of the expression of three genes of PA biosynthesis pathway, ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (SAMDC), and spermidine synthase (SPDSYN) was achieved using RNA interference in MCF 7 breast cancer cell line. For optimizing the effective small interfering nucleic acid (siNA), three variants of ODC siNA [siRNA, locked nucleic acid (LNA)-modified siRNA, and siHybrid (RNA and DNA hybrid)] were used and a dose- and time-dependent study was conducted. The PA biosynthetic genes were targeted individually and in combination. RNAi-mediated reduction in the expression of PA biosynthesis genes resulted in distorted cell morphology, reduced cancer cell viability, and migration characteristic. The most promising results were observed with the combined treatment of siSPDSYN and siODC with 83 % cell growth inhibition. On analyzing the messenger RNA (mRNA) expression profile of the cell cycle and apoptosis-related genes, it was observed that RNAi against PA biosynthetic genes downregulated the expression of CDK8, CCNE2, CCNH, CCNT1, CCNT2, CCNF, PCNA, CCND1, and CDK2, and upregulated the expression of E2F4, BAX, FAS, TP53, CDKN1A, BAK1, CDKN1B, ATM, GRANB, and ATR genes when compared with control-transfected cells. These results suggest that the targeting polyamine biosynthesis through RNAi approach could be a promising strategy for breast cancer therapy and might be extended for therapy of other cancers.

Potential therapeutic applications of plant toxin-ricin in cancer: challenges and advances.

Cancer is one of the most common devastating disease affecting millions of people per year worldwide. To fight against cancer, a number of natural plant compounds have been exploited by researchers to discover novel anti-cancer therapeutics with minimum or no side effects and plants have proved their usefulness in anti-cancer therapy in past few years. Ricin, a cytotoxic plant protein isolated from castor bean seeds, is a ribosome-inactivating protein which destroys the cells by inhibiting proteins synthesis. Ricin presents great potential as anti-cancer agent and exerts its anti-cancer activity by inducing apoptosis in cancer cells. In this review, we summarize the current information on anti-cancer properties of plant toxin ricin, its potential applications in cancer therapy, challenges associated with its use as therapeutic agent and the recent advances made to overcome these challenges. Nanotechnology could open the doors for quick development of ricin-based anti-cancer therapeutics. Conceivably, ricin may serve as a chemotherapeutic agent against cancer by utilizing nanocarriers for its targeted delivery to cancer cells.

Preparation and characterization of monensin loaded PLGA nanoparticles: in vitro anti-malarial activity against Plasmodium falciparum.

PLGA nanoparticles loaded with monensin (carboxylic ionophore) were prepared by emulsion solvent evaporation method using PLGA of molecular weight (Mw.) 19000 and 110000 Da. The nanoparticles were characterized by applying dynamic light scattering (DLS), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and Fourier transformed infrared spectroscopy (FTIR). Negatively charged and spherical smooth surfaced nanoparticles of size range between 147-167 nm were obtained. The nanoparticles of monensin-PLGA showed no chemical interaction between monensin and the polymer molecules. The release kinetics in vitro studies exhibited biphasic release profile characterized by an initial fast release followed by a slower release. The antimalarial efficacy of monensin-PLGA nanoparticles was also examined. Monensin loaded in nanoparticles was 10-fold more effective in inhibiting the growth of P. falciparum in vitro as compared to free monensin. The antimalarial efficacy of monensin-PLGA nanoparticles was significantly dependent on the Mw. of the polymer.