Activation of an IL6 inflammatory loop mediates trastuzumab resistance in HER2+ breast cancer by expanding the cancer stem cell population

Although inactivation of the PTEN gene has been implicated in the development of resistance to the HER2 targeting antibody trastuzumab, the mechanisms mediating this resistance remain elusive. We generated trastuzumab resistant cells by knocking down PTEN expression in HER2 overexpressing breast cancer cell lines and demonstrate that development of trastuzumab resistance in these cells is mediated by activation of an IL6 inflammatory feedback loop leading to expansion of the cancer stem cell (CSC) population. Long term trastuzumab treatment generates highly enriched CSCs which display an EMT phenotype secreting over 100-fold more IL6 than parental cells. An IL6 receptor antibody interrupted this inflammatory feedback loop reducing the cancer stem cell population resulting in decreased tumor growth and metastasis in mouse xenographs. These studies demonstrate that trastuzumab resistance may be mediated by an IL6 inflammatory loop and suggest that blocking this loop may provide alternative strategy to overcome trastuzumab resistance.

HER2 drives luminal breast cancer stem cells in the absence of HER2 amplification: implications for efficacy of adjuvant trastuzumab

Although current breast cancer treatment guidelines limit the use of HER2-blocking agents to tumors with HER2 gene amplification, recent retrospective analyses suggest that a wider group of patients may benefit from this therapy. Using breast cancer cell lines, mouse xenograft models and matched human primary and metastatic tissues, we show that HER2 is selectively expressed in and regulates self-renewal of the cancer stem cell (CSC) population in estrogen receptor-positive (ER(+)), HER2(-) luminal breast cancers. Although trastuzumab had no effects on the growth of established luminal breast cancer mouse xenografts, administration after tumor inoculation blocked subsequent tumor growth. HER2 expression is increased in luminal tumors grown in mouse bone xenografts, as well as in bone metastases from patients with breast cancer as compared with matched primary tumors. Furthermore, this increase in HER2 protein expression was not due to gene amplification but rather was mediated by receptor activator of NF-κB (RANK)-ligand in the bone microenvironment. These studies suggest that the clinical efficacy of adjuvant trastuzumab may relate to the ability of this agent to target the CSC population in a process that does not require HER2 gene amplification. Furthermore, these studies support a CSC model in which maximal clinical benefit is achieved when CSC targeting agents are administered in the adjuvant setting. Cancer Res; 73(5); 1635-46. ©2012 AACR.

Reactive oxygen species generation and mitochondrial dysfunction in the apoptotic cell death of human myeloid leukemia HL-60 cells by a dietary compound withaferin A with concomitant protection by N-acetyl cysteine

Induction of apoptosis in cancer cells has become the major focus of anti-cancer therapeutics development. WithaferinA, a major chemical constituent of Withania somnifera, reportedly shows cytotoxicity in a variety of tumor cell lines while its molecular mechanisms of action are not fully understood. We observed that withaferinA primarily induces oxidative stress in human leukemia HL-60 cells and in several other cancer cell lines. The withanolide induced early ROS generation and mitochondrial membrane potential (Deltapsi(mt)) loss, which preceded release of cytochrome c, translocation of Bax to mitochondria and apoptosis inducing factor to cell nuclei. These events paralleled activation of caspases -9, -3 and PARP cleavage. WA also activated extrinsic pathway significantly as evidenced by time dependent increase in caspase-8 activity vis-à-vis TNFR-1 over expression. WA mediated decreased expression of Bid may be an important event for cross talk between intrinsic and extrinsic signaling. Furthermore, withaferinA inhibited DNA binding of NF-kappaB and caused nuclear cleavage of p65/Rel by activated caspase-3. N-acetyl-cysteine rescued all these events suggesting thereby a pro-oxidant effect of withaferinA. The results of our studies demonstrate that withaferinA induced early ROS generation and mitochondrial dysfunction in cancer cells trigger events responsible for mitochondrial -dependent and -independent apoptosis pathways.

A standardized root extract of Withania somnifera and its major constituent withanolide-A elicit humoral and cell-mediated immune responses by up regulation of Th1-dominant polarization in BALB/c mice

The effects of graded doses of a chemically standardized aqueous alcoholic (1:1) root extract (AGB) of Withania somnifera on the immune system of SRBC immunized BALB/c mice were investigated. Mice were administrated AGB orally for 15 days. AGB stimulated cell mediated immunity, IgM and IgG titers reaching peak value with 30 mg/kg b.wt. Flow cytometric analysis of lymphocyte surface markers of T cells (CD3(+), CD4(+) and CD8(+)) and B cells (CD19(+)) indicated prominent enhancement in proliferation and differentiation of lymphocytes. The extract selectively, induced type 1 immunity because it guided enhanced expression of T helper cells (Th)1 cytokines interferon (IFN)-gamma and interleukin (IL)-2 while Th2 cytokine IL-4 observed a moderate decline. Confirmation of Th1 polarization was obtained from augmented levels of IgG2a over IgG1 in the blood sera of AGB treated groups. Withanolide-A, a major constituent of AGB appeared responsible for Th1 skewing effect of the extract as it significantly increased the levels of Th1 cytokines, decreased moderately IL-4 and significantly restored the selective dexamethasone inhibition of Th1 cytokines in mouse splenocytes cultures in vitro. In addition, AGB also strongly activated macrophage functions ex vivo and in vitro indicated by enhanced secretion of nitrite, IL-12 and TNF-alpha. In contrast IL-10 remained unchanged again suggesting that AGB critically influenced Th1 profile of the cytokines. The studies suggested that AGB supports predominantly Th1 immunity with increase in macrophage functions. The standardized root extract of no toxicological consequences might therefore, find useful applications against the intracellular pathogens and in the management of immune suppressed diseases.

PEGylation of cytokines and other therapeutic proteins and peptides: the importance of biological optimisation of coupling techniques

Polyethylene glycol (PEG) modification, PEGylation, is a well established technique which has the capacity to solve or ameliorate many of the problems of protein and peptide pharmaceuticals. It is one of the most important of the molecule altering structural chemistry (MASC) techniques and in many settings is enabling technology. The use of PEG as a linker molecule is also beginning to make a contribution to the production of exciting new products. We have previously reviewed the marked differences between methods of PEGylation and the surprising and dramatic impact of different coupling techniques (using different activated PEGs) on factors such as retention of bioactivity, stability and immunogenicity of the resulting PEGylated proteins and peptides. Numerous factors play a part in this variation: the presence or absence of linkers between the PEG and the target molecule; the nature and stability of the bond(s) between the PEG, linker and target; the impact of PEG attachment on surface charge; the coupling conditions; and the relative toxicity of the activated polymer and/or coproduct(s). These are not, however, the only sources of qualitative differences in PEGylated products. Our own experience whilst developing a linkerless PEGylation technique (i.e. one attaching only PEG to the target molecule), which we devised to overcome all the major problems of pre-existing PEGylation techniques, was that considerable modification of the prototype method and a process of 'biological optimisation' was required to achieve good results in terms of conservation of bioactivity. Biological optimisation has not, as far as we are aware, been systematically applied by other groups working in PEGylation. It is the term we use to describe an iterative process for examining and refining all the steps in the PEGylation process, including manufacturing the activated polymer, in order to achieve the best possible conservation of bioactivity and other beneficial features of the method. The application of this biologically optimised PEGylation technique, using tresyl monomethoxy PEG (TMPEG), to a variety of target proteins reveals, as outlined in this review, an exceptional ability to conserve biological activity of the target. This, and the benefit of adding nothing other than PEG itself (which has an excellent safety record), to the protein, as well as other manufacturing and practical advantages, makes the method ideal for the modification of cytokines and other therapeutic proteins.

Directional instability of microtubule transport in the presence of kinesin and dynein, two opposite polarity motor proteins

Kinesin and dynein are motor proteins that move in opposite directions along microtubules. In this study, we examine the consequences of having kinesin and dynein (ciliary outer arm or cytoplasmic) bound to glass surfaces interacting with the same microtubule in vitro. Although one might expect a balance of opposing forces to produce little or no net movement, we find instead that microtubules move unidirectionally for several microns (corresponding to hundreds of ATPase cycles by a motor) but continually switch between kinesin-directed and dynein-directed transport. The velocities in the plus-end (0.2-0.3 microns/s) and minus-end (3.5-4 microns/s) directions were approximately half those produced by kinesin (0.5 microns/s) and ciliary dynein (6.7 microns/s) alone, indicating that the motors not contributing to movement can interact with and impose a drag upon the microtubule. By comparing two dyneins with different duty ratios (percentage of time spent in a strongly bound state during the ATPase cycle) and varying the nucleotide conditions, we show that the microtubule attachment times of the two opposing motors as well as their relative numbers determine which motor predominates in this assay. Together, these findings are consistent with a model in which kinesin-induced movement of a microtubule induces a negative strain in attached dyneins which causes them to dissociate before entering a force-generating state (and vice versa); reversals in the direction of transport may require the temporary dissociation of the transporting motor from the microtubule. The bidirectional movements described here are also remarkably similar to the back-and-forth movements of chromosomes during mitosis and membrane vesicles in fibroblasts. These results suggest that the underlying mechanical properties of motor proteins, at least in part, may be responsible for reversals in microtubule-based transport observed in cells.

Alborixin clears amyloid-β by inducing autophagy through PTEN-mediated inhibition of the AKT pathway

Imbalance in production and clearance of amyloid beta (Aβ) is the primary reason for its deposition in Alzheimer disease. Macroautophagy/autophagy is one of the important mechanisms for clearance of both intracellular and extracellular Aβ. Here, through screening, we identified alborixin, an ionophore, as a potent inducer of autophagy. We found that autophagy induced by alborixin substantially cleared Aβ in microglia and primary neuronal cells. Induction of autophagy was accompanied by up regulation of autophagy proteins BECN1/Beclin 1, ATG5, ATG7 and increased lysosomal activities. Autophagy induced by alborixin was associated with inhibition of the phosphoinositide 3-kinase (PI3K)-AKT pathway. A knock down of PTEN and consistent, constitutive activation of AKT inhibited alborixin-induced autophagy and consequent clearance of Aβ. Furthermore, clearance of Aβ by alborixin led to significant reduction of Aβ-mediated cytotoxicity in primary neurons and differentiated N2a cells. Thus, our findings put forward alborixin as a potential anti-Alzheimer therapeutic lead. Abbreviations: Aβ: amyloid beta; ALB: alborixin; ATG: autophagy-related; BECN1: beclin 1; DAPI: 4, 6-diamidino-2-phenylindole; DCFH-DA: 2,7-dichlorodihydrofluorescein diacetate; fAβ: fibrillary form of amyloid beta; GFAP: glial fibrillary acidic protein; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MAP2: microtubule-associated protein 2; MTOR: mechanistic target of rapamycin kinase; PTEN: phosphatase and tensin homolog; ROS: reactive oxygen species; SQSTM1: sequestosome 1; TMRE: tetramethylrhodamine, ethyl ester.

A triterpenediol from Boswellia serrata induces apoptosis through both the intrinsic and extrinsic apoptotic pathways in human leukemia HL-60 cells

A triterpenediol (TPD) comprising of isomeric mixture of 3alpha, 24-dihydroxyurs-12-ene and 3alpha, 24-dihydroxyolean-12-ene from Boswellia serrata induces apoptosis in cancer cells. An attempt was made in this study to investigate the mechanism of cell death by TPD in human leukemia HL-60 cells. It inhibited cell proliferation with IC50 approximately 12 microg/ml and produced apoptosis as measured by various biological end points e.g. increased sub-G0 DNA fraction, DNA ladder formation, enhanced AnnexinV-FITC binding of the cells. Further, initial events involved massive reactive oxygen species (ROS) and nitric oxide (NO) formation, which were significantly inhibited by their respective inhibitors. Persistent high levels of NO and ROS caused Bcl-2 cleavage and translocation of Bax to mitochondria, which lead to loss of mitochondrial membrane potential (Deltapsim) and release of cytochrome c, AIF, Smac/DIABLO to the cytosol. These events were associated with decreased expression of survivin and ICAD with attendant activation of caspases leading to PARP cleavage. Furthermore, TPD up regulated the expression of cell death receptors DR4 and TNF-R1 level, leading to caspase-8 activation. These studies thus demonstrate that TPD produces oxidative stress in cancer cells that triggers self-demise by ROS and NO regulated activation of both the intrinsic and extrinsic signaling cascades.

Nucleotide specificity of the enzymatic and motile activities of dynein, kinesin, and heavy meromyosin

The substrate specificities of dynein, kinesin, and myosin substrate turnover activity and cytoskeletal filament-driven translocation were examined using 15 ATP analogues. The dyneins were more selective in their substrate utilization than bovine brain kinesin or muscle heavy meromyosin, and even different types of dyneins, such as 14S and 22S dynein from Tetrahymena cilia and the beta-heavy chain-containing particle from the outer-arm dynein of sea urchin flagella, could be distinguished by their substrate specificities. Although bovine brain kinesin and muscle heavy meromyosin both exhibited broad substrate specificities, kinesin-induced microtubule translocation varied over a 50-fold range in speed among the various substrates, whereas heavy meromyosin-induced actin translocation varied only by fourfold. With both kinesin and heavy meromyosin, the relative velocities of filament translocation did not correlate well with the relative filament-activated substrate turnover rates. Furthermore, some ATP analogues that did not support the filament translocation exhibited filament-activated substrate turnover rates. Filament-activated substrate turnover and power production, therefore, appear to become uncoupled with certain substrates. In conclusion, the substrate specificities and coupling to motility are distinct for different types of molecular motor proteins. Such nucleotide "fingerprints" of enzymatic activities of motor proteins may prove useful as a tool for identifying what type of motor is involved in powering a motility-related event that can be reconstituted in vitro.

Purification and Characterization of Glutaminase Free Asparaginase from Enterobacter cloacae: In-Vitro Evaluation of Cytotoxic Potential against Human Myeloid Leukemia HL-60 Cells

Asparaginase is an important antileukemic agent extensively used worldwide but the intrinsic glutaminase activity of this enzymatic drug is responsible for serious life threatening side effects. Hence, glutaminase free asparaginase is much needed for upgradation of therapeutic index of asparaginase therapy. In the present study, glutaminase free asparaginase produced from Enterobacter cloacae was purified to apparent homogeneity. The purified enzyme was found to be homodimer of approximately 106 kDa with monomeric size of approximately 52 kDa and pI 4.5. Purified enzyme showed optimum activity between pH 7-8 and temperature 35-40°C, which is close to the internal environment of human body. Monovalent cations such as Na+ and K+ enhanced asparaginase activity whereas divalent and trivalent cations, Ca2+, Mg2+, Zn2+, Mn2+, and Fe3+ inhibited the enzyme activity. Kinetic parameters Km, Vmax and Kcat of purified enzyme were found to be 1.58×10-3 M, 2.22 IU μg-1 and 5.3 × 104 S-1, respectively. Purified enzyme showed prolonged in vitro serum (T1/2 = ~ 39 h) and trypsin (T1/2 = ~ 32 min) half life, which is therapeutically remarkable feature. The cytotoxic activity of enzyme was examined against a panel of human cancer cell lines, HL-60, MOLT-4, MDA-MB-231 and T47D, and highest cytotoxicity observed against HL-60 cells (IC50 ~ 3.1 IU ml-1), which was comparable to commercial asparaginase. Cell and nuclear morphological studies of HL-60 cells showed that on treatment with purified asparaginase symptoms of apoptosis were increased in dose dependent manner. Cell cycle progression analysis indicates that enzyme induces apoptosis by cell cycle arrest in G0/G1 phase. Mitochondrial membrane potential loss showed that enzyme also triggers the mitochondrial pathway of apoptosis. Furthermore, the enzyme was found to be nontoxic for human noncancerous cells FR-2 and nonhemolytic for human erythrocytes.

Dobutamine-atropine stress echocardiography for the detection of coronary artery disease in patients with left ventricular hypertrophy. Importance of chamber size and systolic wall stress

BACKGROUND

Left ventricular hypertrophy is a heterogeneous disorder with distinct morphologies. Changes in wall thickness, left ventricular chamber diameter, and mass alter systolic wall stress of the left ventricle and may influence ischemic threshold. Thus, the goal of this study was to investigate the effect of the different patterns of left ventricular hypertrophy on the accuracy of dobutamine-atropine stress echocardiography.

METHODS AND RESULTS

Three-hundred eighty-six patients underwent multistage dobutamine-atropine stress echocardiography and diagnostic angiography. Echocardiograms were measured for mean and relative wall thicknesses, chamber size, left ventricular mass, and end-systolic wall stress. The patterns of ventricular hypertrophy were concentric hypertrophy (increased wall thickness and mass), eccentric hypertrophy (normal wall thickness and increased mass), and concentric remodeling (increased wall thickness and normal mass). The overall sensitivity, specificity, and accuracy of dobutamine-atropine stress echocardiography for the detection of coronary artery disease were 85%, 87%, and 86%, respectively. Increased left ventricular mass index alone did not affect accuracy. Sensitivity was markedly reduced (36%) only in those with concentric remodeling. The univariate predictors of false-negative studies were single-vessel left circumflex disease, increased wall thickness, small chamber size, hyperdynamic ejection fraction, and left ventricular concentric remodeling. Multivariate predictors were concentric remodeling (P<0.0001; odds ratio, 13.5), left ventricular ejection fraction >2 SD above normal (P<0.0001), and single-vessel left circumflex disease (P<0.0007; odds ratio, 7.6). Sensitivity was excellent in patients with small ventricles and normal wall thickness and in those with normal or large chambers regardless of wall thickness.

CONCLUSIONS

Dobutamine-atropine stress echocardiography is an accurate test in most patients with left ventricular hypertrophy, but it is insensitive in the small subset with concentric remodeling.

Polyethylene glycol modification: relevance of improved methodology to tumour targeting

Of all the polymers applied to molecule altering structural chemistry, polyethylene glycol (PEG) modification has numerous benefits and relatively few drawbacks. PEG is now increasingly being applied to the problems of tumour targeting, both in the context of the passive targeting of PEG-liposomes and in active targeting strategies using PEGylated anti-tumour antibodies. PEG can also serve as a useful linker molecule between targeting moieties and other agents, including cytotoxic or imaging agents and targeted liposomes. Despite these demonstrated benefits and the level of attention which PEGylation has received, relatively little consideration has been given to two key areas: first, the extent to which the coupling method has an impact on both the functionality of the PEG-adduct and the acquisition of beneficial properties; second, that the impact of PEGylation on biodistribution is complex, thus any attempt to optimise a PEG-peptide or PEG-liposome for a particular task must involve an examination of all the individual facets of the effects of PEGylation. Studies investigating the underlying principles of tumour targeting suggest that current views concerning the optimisation of PEGylated vehicles for tumour localisation need to be re-examined.

SOCS3-mediated regulation of inflammatory cytokines in PTEN and p53 inactivated triple negative breast cancer model

Somatic mutations or deletions of TP53 and PTEN in ductal carcinoma in situ (DCIS) lesions have been implicated in progression to invasive ductal carcinomas. A recent molecular and mutational analysis of breast cancers revealed that inactivation of tumor suppressors, p53 and PTEN are strongly associated with triple negative breast cancer. In addition, these tumor suppressors play important roles in regulating self-renewal in normal and malignant stem cells. To investigate their role in breast carcinogenesis, we knocked down these genes in human mammary cells and in non-transformed MCF10A cells. p53 and PTEN knockdown synergized to activate pro-inflammatory IL6/Stat3/NF-κB signaling. This resulted in generation of highly metastatic EMT-like cancer stem cells (CSCs) resulting in tumors whose gene expression profile mimicked that found in basal/claudin-low molecular subtype within the triple negative breast tumors. Constitutive activation of this loop in transformed cells was dependent on proteolytic degradation of SOCS3 resulting in low levels of this protein in basal/claudin low cell lines and primary tumors. In non-transformed cells, transient activation of the IL6 inflammatory loop induced SOCS3 expression leading to pathway inactivation. In transformed cells, enforced expression of SOCS3 or interfering with IL6 pathway via IL6R blockade inhibited tumor growth and metastasis in mouse xenograft models. Furthermore, circulating tumor cells were significantly reduced in tumor bearing animals when treated with anti-IL6R antibodies. These studies uncover important connections between inflammation and carcinogenesis and suggest that blocking pro-inflammatory cytokines may be utilized as an attractive strategy to target triple negative breast tumors which currently lacks molecularly targeted therapies.

Autophagy triggered by magnolol derivative negatively regulates angiogenesis

Angiogenesis has a key role in the tumor progression and metastasis; targeting endothelial cell proliferation has emerged as a promising therapeutic strategy for the prevention of cancer. Previous studies have revealed a complex association between the process of angiogenesis and autophagy and its outcome on tumorigenesis. Autophagy, also known as type-II cell death, has been identified as an alternative way of cell killing in apoptotic-resistant cancer cells. However, its involvement in chemoresistance and tumor promotion is also well known. In this study, we used a derivate of natural product magnolol (Ery5), a potent autophagy inducer, to study the association between the autophagy and angiogenesis in both in vitro and in vivo model system. We found that the robust autophagy triggered by Ery5, inhibited angiogenesis and caused cell death independent of the apoptosis in human umbilical cord vein endothelial cells and PC-3 cells. Ery5 induced autophagy effectively inhibited cell proliferation, migration, invasion and tube formation. We further demonstrated that Ery5-mediated autophagy and subsequent inhibition of angiogenesis was reversed when autophagy was inhibited through 3-methyl adenine and knocking down of key autophagy proteins ATG7 and microtubule-associated protein light chain 3. While evaluating the negative regulation of autophagy on angiogenesis, it was interesting to find that angiogenic environment produced by the treatment of VEGF and CoCl2 remarkably downregulated the autophagy and autophagic cell death induced by Ery5. These studies, while disclosing the vital role of autophagy in the regulation of angiogenesis, also suggest that the potent modulators of autophagy can lead to the development of effective therapeutics in apoptosis-resistant cancer.

Understanding the cell survival mechanism of anoikis-resistant cancer cells during different steps of metastasis

Anchorage-independent survival of cancer cells is associated with metastasis as it enables cells to travel to secondary target sites. Tissue integrity is generally maintained by detachment-induced cell death called 'anoikis', but cancer cells undergoing the multistep metastatic process show resistance to anoikis. Anoikis resistance enables these cells to survive through the extracellular matrix (ECM) deprived phase, which starts when cancer cells detach and move into the circulation till cells reach to the secondary target site. Comprehensive analysis of the molecular and functional biology of anoikis resistance in cancer cells will provide crucial details about cancer metastasis, enabling us to identify novel therapeutic targets against cancer cell dissemination and ultimately secondary tumor formation. This review broadly summarizes recent advances in the understanding of cellular and molecular events leading to anoikis and anoikis resistance. It further elaborates more about the signaling cross-talk in anoikis resistance and its regulation during metastasis.

Role of microRNA221 in regulating normal mammary epithelial hierarchy and breast cancer stem-like cells

Increasing evidence suggests that lineage specific subpopulations and stem-like cells exist in normal and malignant breast tissues. Epigenetic mechanisms maintaining this hierarchical homeostasis remain to be investigated. In this study, we found the level of microRNA221 (miR-221) was higher in stem-like and myoepithelial cells than in luminal cells isolated from normal and malignant breast tissue. In normal breast cells, over-expression of miR-221 generated more myoepithelial cells whereas knock-down of miR-221 increased luminal cells. Over-expression of miR-221 stimulated stem-like cells in luminal type of cancer and the miR-221 level was correlated with clinical outcome in breast cancer patients. Epithelial-mesenchymal transition (EMT) was induced by overexpression of miR-221 in normal and breast cancer cells. The EMT related gene ATXN1 was found to be a miR-221 target gene regulating breast cell hierarchy. In conclusion, we propose that miR-221 contributes to lineage homeostasis of normal and malignant breast epithelium.

Immune modulation and apoptosis induction: Two sides of antitumoural activity of a standardised herbal formulation of Withania somnifera

Deregulated apoptosis and suppressed tumour reactive immunity render tumour cells to grow amok in the host body. Traditionally used botanicals may offer potential anticancer chemo-immunotherapeutic leads. We report in this study a chemically standardised herbal formulation (WSF) of Withania somnifera possessing anticancer and Th1 immune up-regulatory activities. WSF produced cytotoxicity in a panel of human cancer cell lines in vitro. The molecular mechanism of cell cytotoxicity, IC(50) 48h approximately 20mug/ml, was investigated in HL-60, where it induced apoptosis by activating both intrinsic and extrinsic signalling pathways. It induced early generation of reactive nitrogen and oxygen species (RNOS), thus producing oxidative stress mediated mitochondrial membrane potential (MMP) loss leading to the release of cytochrome c, the translocation of Bax to mitochondria and apoptosis-inducing factor to the nuclei. These events paralleled the activation of caspase-9, -3 and PARP cleavage. WSF also activated caspase-8 through enhanced expression of TNF-R1 and DR-4, suggesting also the involvement of extrinsic pathway of apoptosis. WSF at 150mg/kg, i.p., inhibited >50% tumour growth in the mouse tumour models. In tumour-bearing mice, WSF inhibited the expression of pStat-3, with a selective stimulation of Th1 immunity as evidenced by enhanced secretion of IFN-gamma and IL-2. In parallel, it enhanced the proliferation of CD4(+)/CD8(+) and NK cells along with an increased expression of CD40/CD40L/CD80. In addition, WSF also enhanced T cell activation in camptothecin treated tumour-bearing mice. WSF being safe when given orally up to 1500mg/kg to rats for 6 months may be found useful in the management of malignancy by targeting at multiple pathways.

A new vaccine adjuvant (BOS 2000) a potent enhancer mixed Th1/Th2 immune responses in mice immunized with HBsAg

Adjuvants in vaccines are immune stimulants that play an important role in the induction of effective and appropriate immune responses to vaccine component. In search of a potent vaccine adjuvant, the water-soluble biopolymeric fraction BOS 2000 from Boswellia serrata was evaluated for desired activity. We investigated the ability of BOS 2000 to enhance HBsAg specific immune responses. The effect was determined in the form of protective anti-HBsAg titers, neutralizing antibodies (IgG1 and IgG2a), spleen cell lymphocyte proliferation by using MTT assay, Th1 (IFN-gamma and TNF-alpha) and Th2 (IL-4) cytokines as well as T-lymphocyte subsets (CD4/CD8) and intracellular cytokines (IFN-gamma/IL-4), these responses were highest in BOS 2000 immunized mice. Alum induced only a modest enhancement of antibody responses. Reducing the dose of adjuvant by 18.1-fold in comparison to alum, total IgG and its subtypes (IgG1 and IgG2a) antibodies titer in serum was significantly enhanced. Analysis of HBsAg specific cytokines revealed that alum was associated with a predominantly IL-4 response. In contrast, BOS 2000 was associated with production of both IFN-gamma and IL-4. We conclude that BOS 2000 is a potent enhancer of antigen-specific Th1 and Th2 immune responses in comparison to alum with Th2 limitation and is a promising adjuvant for vaccine applications.

Disruption of the PI3K/AKT/mTOR signaling cascade and induction of apoptosis in HL-60 cells by an essential oil from Monarda citriodora

We have isolated an essential oil from Monarda citriodora (MC) and characterized its 22 chemical constituents with thymol (82%), carvacrol (4.82%), β-myrcene (3.45%), terpinen-4-ol (2.78%) and p-cymene (1.53%) representing the major constituents. We have reported for the first time the chemotherapeutic potential of MC in human promyelocytic leukemia HL-60 cells by means of apoptosis and disruption of the PI3K/AKT/mTOR signaling cascade. MC and its major constituent, thymol, inhibit the cell proliferation in different types of cancer cell lines like HL-60, MCF-7, PC-3, A-549 and MDAMB-231. MC was found to be more cytotoxic than thymol in HL-60 cells with an IC50 value of 22 μg/ml versus 45 μg/ml for thymol. Both MC and thymol induce apoptosis in HL-60 cells, which is evident by Hoechst staining, cell cycle analysis and immuno-expression of Bcl-xL, caspase-3,-8,-9 and PARP-1 cleavage. Both induce apoptosis by extrinsic and intrinsic apoptotic pathways that were confirmed by enhanced expression of death receptors (TNF-R1, Fas), caspase-9, loss of mitochondrial membrane potential and regression of Bcl-2/Bax ratio. Interestingly, both MC and thymol inhibit the downstream and upstream signaling of PI3K/AKT/mTOR pathway. The degree of apoptosis induction and disruption of the PI3K signaling cascade by MC was significantly higher when compared to thymol.

Effect of acetazolamide on cerebral blood flow and capillary patency

This study investigated the effects 2 h after administration of acetazolamide on cerebral blood flow and the pattern of cerebral capillary perfusion. Arterial blood pressure, heart rate, arterial blood gases, and pH were recorded in two groups of rats along with either regional cerebral blood flow or the percentage of capillary volume per cubic millimeter and number per square millimeter perfused as determined in cortical, thalamic, pontine, and medullary regions of the brain. Blood pressure, heart rate, and arterial PCO2 were not significantly different between the rats receiving acetazolamide (100 mg/kg) and the controls. Arterial blood pH was significantly lower in the acetazolamide rats. Blood flow increased significantly in the cortical (+ 102%), thalamic (+ 89%), and pontine (+ 88%) regions receiving acetazolamide. In control rats, approximately 60% of the capillaries were perfused in all of the examined regions. The percentage of capillaries per square millimeter perfused was significantly greater in the cortical (+ 52%), thalamic (+ 49%), and pontine (+ 47%) regions of acetazolamide rats compared with controls. In the medulla the increases in blood flow and percentage of capillaries perfused were not significant. Thus in the regions that acetazolamide increased cerebral blood flow, it also increased the percentage of capillaries perfused.

Cancer metastasis: Molecular mechanisms and clinical perspectives

Metastatic progression combined with non-responsiveness towards systemic therapy often shapes the course of disease for cancer patients and commonly determines its lethal outcome. The complex molecular events that promote metastasis are a combination of both, the acquired pro-metastatic properties of cancer cells and a metastasis-permissive or -supportive tumor micro-environment (TME). Yet, dissemination is a challenging process for cancer cells that requires a series of events to enable cancer cell survival and growth. Metastatic cancer cells have to initially detach themselves from primary tumors, overcome the challenges of their intravasal journey and colonize distant sites that are suited for their metastases. The implicated obstacles including anoikis and immune surveillance, can be overcome by intricate intra- and extracellular signaling pathways, which we will summarize and discuss in this review. Further, emerging modulators of metastasis, like the immune-microenvironment, microbiome, sublethal cell death engagement, or the nervous system will be integrated into the existing working model of metastasis.

The synthetic tryptanthrin analogue suppresses STAT3 signaling and induces caspase dependent apoptosis via ERK up regulation in human leukemia HL-60 cells

Tryptanthrin is a natural product which has been reported to have several medicinal properties. In this study, we tried to investigate the detailed molecular mechanism of its bromo analogue (TBr), a potent cytotoxic agent in the induction of cancer cell death. It was found that TBr primarily targets STAT3 and ERK signaling during the induction of apoptosis in several human leukemia cell lines. In HL-60 cells, TBr treatment caused early down regulation of p-STAT3 with concomitant up regulation of p-ERK which led to the activation of intrinsic and extrinsic pathways of apoptosis. The mechanism of TBr mediated inhibition of p-STAT3 was found to be due to the activation of ubiquitin dependent degradation of tyrosine 705 and serine 727 p-STAT3. As IL-6 is the main driver of the STAT3 pathway, the effect of TBr on cell death was subdued when treated in the combination with IL-6 in HL60 cells. Interestingly, PD98059 significantly reduced the apoptotic effects of TBr, thus showing the direct involvement of p-ERK in TBr mediated cell death. It was further shown that apoptotic protein Bax silencing in HL-60 cells resists TBr mediated ERK dependent apoptosis. In summary, for the first time we report the mechanism of TBr mediated cell death in human leukemia cell lines by targeting STAT3 and ERK pathways.

Activation of p53/p21/PUMA alliance and disruption of PI-3/Akt in multimodal targeting of apoptotic signaling cascades in cervical cancer cells by a pentacyclic triterpenediol from Boswellia serrata

Cervical carcinoma is a growing menace to women health worldwide. This study reports the apoptotic cell death in human cervical cancer HeLa and SiHa cells by a pentacyclic triterpenediol (TPD) from Boswellia serrata by a mechanism different from reported in HL-60 cells. It caused oxidative stress by early generation of nitric oxide and reactive oxygen species that robustly up regulated time-dependent expression of p53/p21/PUMA while conversely abrogating phosphatidylinositol-3-kinase (PI3K)/Akt pathways in parallel. TPD also decreased the expression of PI3K/pAkt, ERK1/2, NF-kappaB/Akt signaling cascades which coordinately contribute to cancer cell survival through these distinct pathways. The tumor suppressor p53 pathway predominantly activated by TPD further up-regulated PUMA, which concomitantly decreased the Bcl-2 level, caused mitochondrial membrane potential loss with attendant translocation of Bax and drp1 to mitochondria and release of pro-apoptotic factors such as cytochrome c and Smac/Diablo to cytosol leading to caspases-3 and -9 activation. In addition both the phospho-p53 and p21 were found to accumulate heavily in the nuclear fraction with attendant decrease in topoisomarase II and survivin levels. On the contrary, TPD did not affect the extrinsic signaling transduction pathway effectively through apical death receptors. Interestingly, N-acetyl cysteine, ascorbate and s-methylisothiourea (sMIT) rescued cells significantly from TPD induced DNA damage and caspases activation. TPD may thus find usefulness in managing and treating cervical cancer.