Role of 67 kDa cell surface laminin binding protein of Leishmania donovani in pathogenesis

The role that interaction with laminin may play in Leishmania donovani infection was investigated. Binding of 125 I-radiolabeled laminin, in a liquid-phase assay, by the parasite was rapid, saturable, specific, reversible, and of high affinity. Using a Western blotting procedure, a 67 kDa laminin-binding protein (LBP) was identified from the membrane of both the promastigote and amastigote forms of L. donovani. Subsequently, the protein was purified by affinity chromatography. Immunofluorescence with a polyclonal anti-body against LBP as well as flow cytometric analysis demonstrated its presence at the parasite surface. After stimulation with phorbol-12-myristate-13-acetate (PMA), U937 cells exhibited the ability to adhere to laminin and LBP specifically inhibited this adhesion. The reduced parasite adhesion after tunicamycin treatment suggested the importance of sugar residues in cell adhesion. Although co-administration of either laminin or LBP or anti LBP antibody reduced parasite virulence, resulting in a lower level of infection in the BALB/c mouse model, an in vitro macrophage culture-enhanced level of infection was observed in the case of laminin-coated parasites. The results collectively suggest a role for LBP in the interaction of the parasite with extracellular matrix elements, which may constitute a basis for the homing of the parasite to its physiological address

Doxorubicin in Combination with a Small TGFβ Inhibitor: A Potential Novel Therapy for Metastatic Breast Cancer in Mouse Models

Recent studies suggested that induction of epithelial-mesenchymal transition (EMT) might confer both metastatic and self-renewal properties to breast tumor cells resulting in drug resistance and tumor recurrence. TGFbeta is a potent inducer of EMT and has been shown to promote tumor progression in various breast cancer cell and animal models.We report that chemotherapeutic drug doxorubicin activates TGFbeta signaling in human and murine breast cancer cells. Doxorubicin induced EMT, promoted invasion and enhanced generation of cells with stem cell phenotype in murine 4T1 breast cancer cells in vitro, which were significantly inhibited by a TGFbeta type I receptor kinase inhibitor (TbetaRI-KI). We investigated the potential synergistic anti-tumor activity of TbetaR1-KI in combination with doxorubicin in animal models of metastatic breast cancer. Combination of Doxorubicin and TbetaRI-KI enhanced the efficacy of doxorubicin in reducing tumor growth and lung metastasis in the 4T1 orthotopic xenograft model in comparison to single treatments. Doxorubicin treatment alone enhanced metastasis to lung in the human breast cancer MDA-MB-231 orthotopic xenograft model and metastasis to bone in the 4T1 orthotopic xenograft model, which was significantly blocked when TbetaR1-KI was administered in combination with doxorubicin.These observations suggest that the adverse activation of TGFbeta pathway by chemotherapeutics in the cancer cells together with elevated TGFbeta levels in tumor microenvironment may lead to EMT and generation of cancer stem cells resulting in the resistance to the chemotherapy. Our results indicate that the combination treatment of doxorubicin with a TGFbeta inhibitor has the potential to reduce the dose and consequently the toxic side-effects of doxorubicin, and improve its efficacy in the inhibition of breast cancer growth and metastasis

"The fruits of independence": Satyajit Ray, Indian nationhood and the spectre of empire

Challenging the longstanding consensus that Satyajit Ray's work is largely free of ideological concerns and notable only for its humanistic richness, this article shows with reference to representations of British colonialism and Indian nationhood that Ray's films and stories are marked deeply and consistently by a distinctively Bengali variety of liberalism. Drawn from an ongoing biographical project, it commences with an overview of the nationalist milieu in which Ray grew up and emphasizes the preoccupation with colonialism and nationalism that marked his earliest unfilmed scripts. It then shows with case studies of Kanchanjangha (1962), Charulata (1964), First Class Kamra (First-Class Compartment, 1981), Pratidwandi (The Adversary, 1970), Shatranj ke Khilari (The Chess Players, 1977), Agantuk (The Stranger, 1991) and Robertsoner Ruby (Robertson's Ruby, 1992) how Ray's mature work continued to combine a strongly anti-colonial viewpoint with a shifting perspective on Indian nationhood and an unequivocal commitment to cultural cosmopolitanism. Analysing how Ray articulated his ideological positions through the quintessentially liberal device of complexly staged debates that were apparently free, but in fact closed by the scenarist/director on ideologically specific notes, this article concludes that Ray's reputation as an all-forgiving, ‘everybody-has-his-reasons’ humanist is based on simplistic or even tendentious readings of his work

Isolation and Characterization of a Metastatic Hybrid Cell Line Generated by ER Negative and ER Positive Breast Cancer Cells in Mouse Bone Marrow

BACKGROUND: The origin and the contribution of breast tumor heterogeneity to its progression are not clear. We investigated the effect of a growing orthotopic tumor formed by an aggressive estrogen receptor (ER)-negative breast cancer cell line on the metastatic potential of a less aggressive ER-positive breast cancer cell line for the elucidation of how the presence of heterogeneous cancer cells might affect each other's metastatic behavior. METHODS: ER positive ZR-75-1/GFP/puro cells, resistant to puromycin and non-tumorigenic/non-metastatic without exogenous estrogen supplementation, were injected intracardiacally into mice bearing growing orthotopic tumors, formed by ER negative MDA-MB-231/GFP/Neo cells resistant to G418. A variant cell line B6, containing both estrogen-dependent and -independent cells, were isolated from GFP expressing cells in the bone marrow and re-inoculated in nude mice to generate an estrogen-independent cell line B6TC. RESULTS: The presence of ER negative orthotopic tumors resulted in bone metastasis of ZR-75-1 without estrogen supplementation. The newly established B6TC cell line was tumorigenic without estrogen supplementation and resistant to both puromycin and G418 suggesting its origin from the fusion of MDA-MB-231/GFP/Neo and ZR-75-1/GFP/puro in the mouse bone marrow. Compared to parental cells, B6TC cells were more metastatic to lung and bone after intracardiac inoculation. More significantly, B6TC mice also developed brain metastasis, which was not observed in the MDA-MB-231/GFP/Neo cell-inoculated mice. Low expression of ERα and CD24, and high expression of EMT-related markers such as Vimentin, CXCR4, and Integrin-β1 along with high CD44 and ALDH expression indicated stem cell-like characteristics of B6TC. Gene microarray analysis demonstrated a significantly different gene expression profile of B6TC in comparison to those of parental cell lines. CONCLUSIONS: Spontaneous generation of the novel hybrid cell line B6TC, in a metastatic site with stem cell-like properties and propensity to metastasize to brain, suggest that cell fusion can contribute to tumor heterogeneity

Activation of Proinflammatory Response in Human Intestinal Epithelial Cells Following Vibrio Cholerae Infection Through PI3K/Akt Pathway

Vibrio cholerae activates proinflammatory response in cultured intestinal epithelial cells. In this study, we demonstrate that V. cholerae O395 infection of intestinal epithelial cells results in the activation of Akt. Inhibition of Akt significantly decreases IL-1a, IL-6, and TNF-a production in V. cholerae infected Int407 cells. Analysis of the mechanisms of Akt influences on cytokine response demonstrates that Akt promotes NF-kB activation. We have extended these findings to show that Akt activation may be regulated by bacterial genes associated with virulence, adherence, or motility. Insertion mutants in the virulence genes coding for CtxA, ToxT, and OmpU of V. cholerae modulate the activation of PI3K/ Akt signaling pathway, whereas an aflagellate non-motile mutant (O395FLAN) and a adherent and less motile mutant (O395Y3N/O395Y4N) of V. cholerae both show very significant down-regulation of Akt activity in Int407 cells. Together, these observations indicate that Akt promotes proinflammatory cytokine production by V. cholerae infected human intestinal epithelial cells through its influences on NF-kB

Groove pancreatitis presenting as recurrent acute pancreatitis

A middle aged male presented with recurrent acute pancreatitis without any feature of extrahepatic biliary obstruction. Evaluation revealed mass in groove area with duodenal lumen compromise without any features of chronic pancreatitis. He underwent classical Whipple′s operation with the suspicion of periampullary tumor but histopathology was suggestive of groove pancreatitis ruling out malignancy. This case is first case to report recurrent acute pancreatitis as presentation of groove pancreatitis

The p14ARF Alternate Reading Frame Protein Enhances DNA Binding of Topoisomerase I by Interacting with the Serine 506-Phosphorylated Core Domain

<div><p>In addition to its well-characterized function as a tumor suppressor, p14ARF (ARF) is a positive regulator of topoisomerase I (topo I), a central enzyme in DNA metabolism and a target for cancer therapy. We previously showed that topo I hyperphosphorylation, a cancer-associated event mediated by elevated levels of the protein kinase CK2, increases topo I activity and the cellular sensitivity to topo I-targeted drugs. Topo I hyperphosphorylation also increases its interaction with ARF. Because the ARF−topo I interaction could be highly relevant to DNA metabolism and cancer treatment, we identified the regions of topo I involved in ARF binding and characterized the effects of ARF binding on topo I function. Using a series of topo I deletion constructs, we found that ARF interacted with the topo I core domain, which encompasses most of the catalytic and DNA-interacting residues. ARF binding increased the DNA relaxation activity of hyperphosphorylated topo I by enhancing its association with DNA, but did not affect the topo I catalytic rate. In cells, ARF promoted the chromatin association of hyperphosphorylated, but not basal phosphorylated, topo I, and increased topo I-mediated DNA nicking under conditions of oxidative stress. The aberrant nicking was found to correlate with increased formation of DNA double-strand breaks, which are precursors of many genome destabilizing events. The results suggest that the convergent actions of oxidative stress and elevated CK2 and ARF levels, which are common features of cancer cells, lead to a dysregulation of topo I that may contribute both to the cellular response to topo I-targeted drugs and to genome instability.</p> </div

Correlation of CK2 activity, PS506 expression, and camptothecin sensitivity in cancer cell lines.

<p>(<b>A</b>) CK2 activity in cell lysates of the indicated cell lines. (<b>B</b>) Western analysis of PS506, total topo I, and actin in lysates of the indicated cell lines. Each lane contains 75 µg of cell lysate. Numbers below lanes refer to the intensities of the PS506 band relative to H358, as determined digitally. (<b>C</b>) Day 3 viability assays of the indicated cell lines following exposure to the indicated doses of camptothecin (CPT) for the first 18 h of the incubation.</p

Model summarizing how oncogene-induced ARF expression and CK2-mediated topo I hyperphosphorylation can converge to enhance topo I–DNA association and topo I-facilitated DNA damage.

<p>Cancer cells with elevated CK2 levels (CK2^hi) accumulate a PS506-hyperphosphorylated form of topo I with increased DNA binding properties. Chronic oncogene activation in the absence of wild-type p53 leads to sustained elevation of ARF (ARF^hi), which is unable to promote p53-mediated apoptosis but is available to bind to PS506-hyperphosphorylated topo I, further promoting the association of topo I with DNA. The enhanced binding increases the potential for topo I-facilitated DNA double-strand break (DSB) formation in the presence of elevated levels of reactive oxygen species (ROS) that accompany oncogene activation.</p