Myeloid cell-derived PROS1 inhibits tumor metastasis by regulating inflammatory and immune responses via IL-10.

Stimulation of TAM (TYRO3, AXL, and MERTK) receptor tyrosine kinases promotes tumor progression through numerous cellular mechanisms. TAM cognate ligands GAS6 and PROS1 (for TYRO3 and MERTK) are secreted by host immune cells, an interaction which may support tumor progression. Here, we revealed an unexpected antimetastatic role for myeloid-derived PROS1: suppressing metastatic potential in lung and breast tumor models. Pros1 deletion in myeloid cells led to increased lung metastasis, independent of primary tumor infiltration. PROS1-cKO bone marrow-derived macrophages (BMDMs) led to elevated TNF-α, IL-6, Nos2, and IL-10 via modulation of the Socs3/NF-κB pathway. Conditioned medium from cKO BMDMs enhanced EMT, ERK, AKT, and STAT3 activation within tumor cells and promoted IL-10-dependent invasion and survival. Macrophages isolated from metastatic lungs modulated T cell proliferation and function, as well as expression of costimulatory molecules on DCs in a PROS1-dependent manner. Inhibition of MERTK kinase activity blocked PROS1-mediated suppression of TNF-α and IL-6 but not IL-10. Overall, using lung and breast cancer models, we identified the PROS1/MERTK axis within BMDMs as a potent regulator of adaptive immune responses with a potential to suppress metastatic seeding and revealed IL-10 regulation by PROS1 to deviate from that of TNF-α and IL-6.

PKA Activates AMPK Through LKB1 Signaling in Follicular Thyroid Cancer.

Thyroid cancer affects about one percent of the population, and has seen rising incidence in recent years. Follicular thyroid cancer (FTC) comprises 10-15% of all thyroid cancers. Although FTC is often localized, it can behave aggressively with hematogenous metastasis, leading to an increased risk of cancer death. We previously described a mouse model for FTC caused by tissue-specific ablation of the Protein Kinase A (PKA) regulatory subunit Prkar1a, either by itself or in combination with knockout of Pten. Loss of Prkar1a causes enhanced activity of PKA, whereas ablation of Pten causes activation of Akt signaling. At the molecular level, these genetic manipulations caused activation of mTOR signaling, which was also observed in human FTC cases. To understand the mechanism by which PKA activates mTOR, we began by studying intracellular kinases known to modulate mTOR function. Although AMP-activated kinase (AMPK) has been characterized as a negative regulator of mTOR activity, our tumor model exhibited activation of both AMPK and mTOR. To understand the mechanism by which AMPK was turned on, we next studied kinases known to cause its phosphorylation. In this paper, we report that PKA leads to AMPK activation through the LKB1 kinase. Although LKB1 has traditionally been considered a tumor suppressor, our data indicates that it may have a complex role in the thyroid gland, where its activation appears to be frequently associated with follicular thyroid carcinoma in both mice and humans.

Protein S drives oral squamous cell carcinoma tumorigenicity through regulation of AXL.

The TAM family of proto-oncogenic receptor protein tyrosine kinases, comprising of TYRO3, AXL, and MERTK, is implicated in many human cancers. Their activation leads to cancer cell proliferation, enhanced migration, invasion, and drug resistance; however how TAMs are activated in cancers is less understood. We previously showed that Protein S (PROS1) is a ligand of the TAM receptors. Here we identify PROS1 as a mediator of Oral Squamous Cell Carcinoma (OSCC) in proliferation, cell survival and migration. We demonstrate that excess PROS1 induces OSCC proliferation and migration. Conversely, blocking endogenous PROS1 expression using shRNA significantly inhibits cell proliferation and migration in culture. This inhibition was rescued by the addition of purified PROS1. Moreover, PROS1 knockdown reduced anchorage-independent growth in-vitro, reduced tumor xenograft growth in nude mice and altered their differentiation profile. Mechanistically, we identify the downregulation of AXL transcripts and protein following PROS1 knockdown. Re-introducing PROS1 rescues AXL expression both at the protein and transcriptional levels. The anti-proliferative effect of the AXL inhibitor R428 was significantly reduced following PROS1 inhibition, indicating the functional significance of PROS1-mediated regulation of AXL in OSCC. Taken together, we identify PROS1 as a driver of OSCC tumor growth and a modulator of AXL expression. Our results point to PROS1 as a potential novel anti-cancer therapeutic target.

Antimicrobial and immunomodulatory efficacy of extracellularly synthesized silver and gold nanoparticles by a novel phosphate solubilizing fungus Bipolaris tetramera.

BACKGROUND: Particulates of nanometers size have occupied a significant area in the field of medicinal and agricultural purposes due to their large surface-to-volume ratio and exceptional physicochemical, electronic and mechanical properties. Myconanotechnology, an interface between mycology and nanotechnology is budding nowadays for nanoparticle-fabrication using fungus or its metabolites. In the present study, we have isolated and characterized a novel phosphate solubilizing fungus B. tetramera KF934408 from rhizospheric soil. This phosphatase releasing fungus was subjected to extracellular synthesis of metal nanoparticles by redox reaction. RESULTS: Silver (AgNPs) and gold nanoparticles (AuNPs) were characterized by dynamic light scattering and transmission electron microscopic analysis. The formulated AgNPs were irregular shaped with a size ranging between 54.78 nm to 73.49 nm whereas AuNPs were spherical or hexagonal, with a size of 58.4 and 261.73 nm, respectively. The nanoparticles were assessed for their antibacterial and antifungal efficacy. The results showed effective antimicrobial activity of AgNPs against Bacillus cereus, Staphylococcus aureus, Enterobacter aeroginosa and Trichoderma sp. at higher concentrations, however, AuNPs possessed only moderate antibacterial efficacy while they found no antifungal activity. Cytotoxicity analysis of nanoparticles on J774 and THP1 α cell lines revealed the dose dependence in case of AgNPs, while AuNPs were non-toxic at both low and high doses. Furthermore, significant elevation of intracellular ROS was observed after 4 h of incubation with both the nanoparticles. The capping of fungal proteins on the particulates might be involved in the activities demonstrated by these inert metal nanoparticles. CONCLUSION: In conclusion, the findings showed that the metal nanoparticles synthesized by fungus B. tetramera could be used as an antimicrobial agents as well as cost effective and nontoxic immunomodulatory delivery vehicle.

Cytogenomics of hexavalent chromium (Cr 6+) exposed cells: a comprehensive review.

The altered cellular gene expression profile is being hypothesized as the possible molecular basis navigating the onset or progress of various morbidities. This hypothesis has been evaluated here in respect of Cr 6+ induced toxicity. Several studies using gene microarray show selective and strategic dysregulations of cellular genes and pathways induced by Cr 6+. Relevant literature has been reviewed to unravel these changes in different test systems after exposure to Cr 6+ and also to elucidate association if any, of the altered cytogenomics with Cr 6+ induced toxicity or carcinogenicity. The aim was to verify the hypothesis for critical role of altered cytogenomics in onset of Cr 6+ induced biological/clinical effects by identifying genes modulated commonly by the toxicant irrespective of test system or test concentrations/doses, and by scrutinizing their importance in regulation of the flow of mechanistically linked events crucial for resultant morbidities. Their probability as biomarkers to monitor the toxicant induced biological changes is speculative. The modulated genes have been found to cluster under the pathways that manage onset of oxidative stress, DNA damage, apoptosis, cell-cycle regulation, cytoskeleton, morphological changes, energy metabolism, biosynthesis, oncogenes, bioenergetics, and immune system critical for toxicity. In these studies, the identity of genes has been found to differ remarkably; albeit the trend of pathways' dysregulation has been found to remain similar. We conclude that the intensity of dysregulation of genes or pathways involved in mechanistic events forms a sub-threshold or threshold level depending upon the dose and type (including speciation) of the toxicant, duration of exposure, type of target cells, and niche microenvironment of cells, and the intensity of sub-threshold or threshold level of the altered cytogenomics paves way in toxicant exposed cells eventually either to opt for reversal to differentiation and growth, or to result in toxicity like dedifferentiation and apoptosis, respectively.

Diethyl maleate inhibits MCA+TPA transformed cell growth via modulation of GSH, MAPK, and cancer pathways.

Murine or human cancer cells have high glutathione levels. Depletion of the elevated GSH inhibits proliferation of cancer cells. Molecular basis for this observation is little understood. In an attempt to find out the underlying mechanism, we reproduced these effects in transformed C3H10T1/2 and BALB/c 3T3 cells using diethyl maleate and studied cytogenomic changes in the whole mouse genome using spotted 8 × 60 K arrays. Transformed cells revealed an increase in GSH levels. GSH depletion by DEM inhibited the growth of transformed cells. The non-cytotoxic dose of DEM (0.25 mM) resulted in GSH depletion, ROS generation, cell cycle arrest, apoptosis, decrease in anchorage independent growth, gene expression changes and activation of all three members of the MAPK family. Increase in intracellular GSH levels by GSHe countered the effect of DEM. These results support the physiological importance of GSH in regulation of gene expression for transformed cell growth restraint. This study is of interest in not only understanding the molecular biology of the transformed cells, but also in identifying new targets for development of gene therapy together with the chemotherapy.

Lipoic acid prevents Cr(6+) induced cell transformation and the associated genomic dysregulation.

Investigation of the transcription profile of cells transformed by Cr(6+) in vivo was undertaken. The objective was to elucidate genomic changes underlying the mechanism of action of the carcinogenic dose of Cr(6+)and their prevention using metabolic antioxidant lipoic acid (LA). Cr(6+) was administered intraperitoneally to LPS+TPA challenged Swiss albino mice in host mediated cell transformation assay using peritoneal macrophages in vivo. The cell transforming potential of Cr(6+) test doses was validated by gain of anchorage independent growth potential in soft agar and loss of Fc receptor on target cells. LA was administered in equimolar doses. Compared to non-transformed cells, the gene expression profile of transformed cells was found to be dysregulated substantially and in dose dependent manner. Genes showing down regulation were found to be involved in tumour suppression, apoptosis, DNA repair, and cell-cycle. A similar response was noted in the genes pertaining to immune system, morphogenesis, cell-communication, energy-metabolism, and biosynthesis. The co-administration of lipoic acid prevented the transcription dysregulation and cell transformation by Cr(6+) in vivo. The influenced pathways seem to be crucial for progression as well as mitigation of Cr toxicity; and their response to LA indicated their critical role in mechanism of anti-carcinogenic action of LA. Results are of importance to mitigate Cr(6+) induced occupational cancer hazard.

Dysregulation of pathways involved in the processing of cancer and microenvironment information in MCA + TPA transformed C3H/10T1/2 cells.

The two-stage cell transformation assay is an in vitro model cell culture system to identify the ability of chemicals to act as initiators or promoters of cell transformation and also to study the cellular and molecular mechanisms of chemically induced morphological and neoplastic cell transformation. The global gene expression profiles of 3-methylcholanthrene (MCA) + 12-O-tetradecanoylphorbol-13-acetate (TPA)-transformed C3H/10T1/2 cells are not known. Therefore, we have investigated the global transcriptional profile of MCA + TPA-transformed C3H10T1/2 cells using an 8 × 60 k probe microarray. The study revealed a differential regulation of pathways and gene expressions. Multifold dysregulation was seen in pathways of cancer, phagosomal activity, and tumor cell microenvironment information processing systems, notably the neuroactive ligand-receptor interaction, actin cytoskeleton regulation, tight junction, axon guidance, and cell adhesion molecules. The genes FGF1, EIF4E1B, MAGI1, and GRIA3 showed upregulation; these encoded the pluripotent fibroblast growth factor, the translation initiation factor, the tight junction scaffolding protein, and the antiapoptotic as well as the enhancer of proliferation and migration, respectively. The genes CXCL7/CXCL5/CXCL12, H2DMB1, and HSPA1A showed downregulation; these encoded the chemotactic agent protein, the protein involved in MHC class II antigen processing/presentation or participating in cell adhesion/phagosomal activity/autoimmune disorder, and the chaperone protein stabilizing the existing as well as newly translated cytosolic/organelle proteins against aggregation, respectively. By loss or gain of function, these dysregulated genes apparently seem to reprogram cells for apoptosis or proliferation and support their transformation into the tumor cell phenotype. The observed molecular changes can be seen as molecular signatures of transformed cells and can be of use as objective evidences to C3H/10T1/2 cell transformation assay in investigations on the carcinogenic potential of chemicals and their mechanism of actions using in vitro carcinogenesis method.

Cytoprotection against Cr(6+)-induced DNA damage by alpha-lipoic acid: implications in reducing occupational cancer risk.

Alpha-lipoic acid (LA), the metabolic antioxidant, was evaluated for its potential to protect against Cr(6+)-induced DNA damage. Potassium dichromate was administered to Swiss albino mice orally ad libitum at the doses of 5, 10 or 25 mg/kg body weight in drinking water to set DNA damage in cells, which was characterized in mouse peripheral blood mononuclear cells and bone marrow cells using single-cell gel electrophoresis and analyses of generated comets for Tail moment, Tail DNA and Tail length. DNA damage was dose dependent. Cytoprotection by LA was remarkable. LA (5, 10 and 25 mg/kg body weight intraperitoneally) in pre-, co- and post-toxicant administration schedule abrogated DNA damage substantially in both cell types. Protection by LA was also dose dependent. LA annulled DNA damage by Cr(6+) in plasmid relaxation assay. A negligible DNA damage resulted during interaction of Cr(6+) and LA. Compared to ascorbate, LA emerged as a better antioxidant and least DNA damaging. In conclusion, our study advocated an experimental therapeutic research potential in LA against Cr(6+)-induced DNA damage for reduction of occupational cancer risk in humans.