Circumventing Multidrug Resistance in Cancer by β-Galactoside Binding Protein, an Antiproliferative Cytokine

Intrinsic S phase checkpoint enforced by an antiproliferative oncosuppressor cytokine

The cell cycle is strictly programmed with control mechanisms that dictate order in cell cycle progression to ensure faithful DNA replication, whose deviance may lead to cancer. Checkpoint control at the G1/S, S/G2 and G2/M portals have been defined but no statutory time-programmed control for securing orderly transition through S phase has so far been identified. Here we report that in normal cells DNA synthesis is controlled by a checkpoint sited within the early part of S phase, enforced by the βGBP cytokine an antiproliferative molecule otherwise known for its oncosuppressor properties that normal cells constitutively produce for self-regulation. Suppression of active Ras and active MAPK, block of cyclin A gene expression and suppression of CDK2-cyclin A activity are events which while specific to the control of a cell cycle phase in normal cells are part of the apoptotic network in cancer cells.

Sourcing the immune system to induce immunogenic cell death in Kras-colorectal cancer cells

Background

Current approaches aimed at inducing immunogenic cell death (ICD) to incite an immune response against cancer neoantigens are based on the use of chemotherapeutics and other agents. Results are hampered by issues of efficacy, combinatorial approaches, dosing and toxicity. Here, we adopted a strategy based on the use of an immunomolecule that overcomes pharmachemical limitations.

Methods

Cytofluorometry, electron microscopy, RT-PCR, western blotting, apotome immunofluorescence, MLR and xenografts.

Results

We report that an ICD process can be activated without the use of pharmacological compounds. We show that in Kras-mut/TP53-mut colorectal cancer cells the 15 kDa βGBP cytokine, a T cell effector with onco-suppressor properties and a potential role in cancer immunosurveillance, induces key canonical events required for ICD induction. We document ER stress, autophagy that extends from cancer cells to the corresponding xenograft tumours, CRT cell surface shifting, ATP release and evidence of dendritic cell activation, a process required for priming cytotoxic T cells into a specific anticancer immunogenic response.

Conclusions

Our findings provide experimental evidence for a rationale to explore a strategy based on the use of an immunomolecule that as a single agent couples oncosuppression with the activation of procedures necessary for the induction of long term response to cancer.

An array of possibilities in cancer research using cytokine antibody arrays

Protein arrays have shown potential applications in cancer research. After several decades of research, it has become evident that many cytokines are central to the development of cancer and its treatment. Cytokine antibody arrays that have been designed to simultaneously detect multiple cytokines are not only available, but show a diversity of applications in the study of many diseases in addition to cancer. This review will focus on the implementation of cytokine antibody arrays in many aspects of cancer research, such as biomarker discovery, molecular mechanisms of cancer development, preclinical studies and the effects of cancer compounds.

The end of KRAS, and other, cancers? A new way forward

Mutant KRAS, as well as other mutant driver genes and epidriver genes, is a dominant determinant of resistance to cancer therapeutics. The recent introduction of targeting therapies based on drugs that inhibit the kinase catalytic function of nodal points along the Ras/extracellular-signal-regulated kinase (ERK) and the phosphatidylinositol-3-kinase (PI3K)/Akt cascades is meeting with limited success. Against this background, recent evidence shows that the β-galactoside-binding protein (βGBP) molecule, a physiological PI3K inhibitor, is a potent inducer of apoptosis in KRAS-mutant cancer cells (along with other aggressive cancer cells of different genetic makeup) and that it is therapeutically effective in vivo. Absence of p53 or phosphatase and tensin homolog (PTEN) tumor suppressor function or added activating PI3K mutations does not affect βGBP function. In contrast to the concept of one drug against one target, βGBP operates through alternative physiological routes.

Killing of Kras-mutant colon cancer cells via Rac-independent actin remodeling by the βGBP cytokine, a physiological PI3K inhibitor therapeutically effective in vivo

Activating mutations in Kras are the most frequent mutations in human cancer. They define a subset of patients who do not respond to current therapies and for whom prognosis is poor. Oncogenic Kras has been shown to deregulate numerous signaling pathways of which the most intensively studied are the Ras/extracellular signal-regulated kinase cascade and the phosphoinositide 3-kinase (PI3K)/Akt cascade. However, to date, there are no effective targeted therapies in the clinic against Kras-mutant cancers. Here, we report that the β-galactoside-binding protein (βGBP) cytokine, a physiologic inhibitor of class I PI3Ks, is a potent activator of apoptosis in Kras-mutant colorectal cancer cells, even when coharboring mutant-activated PIK3CA. Our study unveils an elective route to intrinsic and extrinsic apoptosis, which involves the cytoskeleton. Early events are inhibition of PI3K activity and Rac-independent actin rearrangement assignable to phosphoinositide changes at the plasma membrane. Cyclin E deregulation, arrest of DNA synthesis, and checkpoint kinase 2 activation underscore events critical to the activation of an intrinsic apoptotic program. Clustering of CD95/Fas death receptors underscore events critical to the activation of extrinsic apoptosis. In nude mice, we present the first evidence that xenograft tumor development is strongly inhibited by Hu-r-βGBP. Taken together, our results open a new therapeutic opportunity to a subset of patients refractive to current treatments. This first demonstration of therapeutic efficacy against Kras-mutant colon cancer suggests that Hu-r-βGBP may also be therapeutically effective against other cancers harboring activating Ras mutations as well as PIK3CA mutations.

Neoplastic "Black Ops": cancer's subversive tactics in overcoming host defenses

Metastatic cancer is usually an incurable disease. Cancers have a broad repertoire of subversive tactics to defeat the immune system. They mimic self, they down-regulate MHC molecules so that T cells are blind to their presence, they interfere with antigen presentation, and they produce factors that can kill T cells or paralyze their response to antigens. Furthermore, the same powerful machinery designed to prevent harmful autoimmune responses is also acting to protect cancers. In particular, cancer is protected with the help of so-called regulatory immune cells. These unique subsets of cells, represented by almost every immune cell type, function to control responses of effector immune cells. In this review, we will discuss the evidence that cancer actively promotes cross-talk of regulatory immune cells to evade immunosurveillance. We will also discuss the role of a newly described cell type, regulatory B cells, by emphasizing their importance in suppression of antitumor immune responses. Thus, cancer not only directly suppresses immune function, but also recruits components of the immune system to become traitors and protect the tumor from immune attack.

Epithelial-mesenchymal transition and breast cancer: role, molecular mechanisms and clinical impact

Epithelial-mesenchymal transition (EMT) is defined by the loss of epithelial characteristics and the acquisition of a mesenchymal phenotype. In this process, cells acquire molecular alterations that facilitate dysfunctional cell-cell adhesive interactions and junctions. These processes may promote cancer cell progression and invasion into the surrounding microenvironment. Such transformation has implications in progression of breast carcinoma to metastasis, and increasing evidences support most tumors contain a subpopulation of cells with stem-like and mesenchymal features that is resistant to chemotherapy. This review focuses on the physiological and pathological role of EMT process, its molecular related network, its putative role in the metastatic process and its implications in response/resistance to the current and/or new approaching drugs in the clinical management of breast cancer.

Tregs utilize beta-galactoside-binding protein to transiently inhibit PI3K/p21ras activity of human CD8+ T cells to block their TCR-mediated ERK activity and proliferation

Regulatory T cells (Tregs) and beta-galactoside-binding protein (betaGBP), a regulatory protein often found expressed at sites of immunological privilege, have similar functions. Their presence affects the outcome of harmful autoimmunity and cancers, including experimental autoimmune encephalomyelitis and malignant gliomas. Here we report a novel pathway by which Tregs express and utilize betaGBP to control CD8(+) T cell responses partially activating TCR signaling but blocking PI3K activity. As a result, this leads to a loss of p21(ras), ERK and Akt activities despite activation of TCR proximal signals, such as phosphorylation of CD3zeta, Zap70, Lat and PKCtheta. Although non-processive TCR signaling often leads to cell anergy, Tregs/betaGBP did not affect cell viability. Instead, betaGBP/Tregs transiently prevented activation of CD8(+) T cells with self-antigens, while keeping their responses to xenogeneic antigens unaffected.

Breast cancer lung metastasis requires expression of chemokine receptor CCR4 and regulatory T cells

Cancer metastasis is a leading cause of cancer morbidity and mortality. More needs to be learned about mechanisms that control this process. In particular, the role of chemokine receptors in metastasis remains controversial. Here, using a highly metastatic breast cancer (4T1) model, we show that lung metastasis is a feature of only a proportion of the tumor cells that express CCR4. Moreover, the primary tumor growing in mammary pads activates remotely the expression of TARC/CCL17 and MDC/CCL22 in the lungs. These chemokines acting through CCR4 attract both tumor and immune cells. However, CCR4-mediated chemotaxis was not sufficient to produce metastasis, as tumor cells in the lung were efficiently eliminated by natural killer (NK) cells. Lung metastasis required CCR4(+) regulatory T cells (Treg), which directly killed NK cells using beta-galactoside-binding protein. Thus, strategies that abrogate any part of this process should improve the outcome through activation of effector cells and prevention of tumor cell migration. We confirm this prediction by killing CCR4(+) cells through delivery of TARC-fused toxins or depleting Tregs and preventing lung metastasis.

Functional inhibition of PI3K by the betaGBP molecule suppresses Ras-MAPK signalling to block cell proliferation

The mechanisms of signal transduction from cell surface receptors to the interior of the cell are fundamental to the understanding of the role that positive and negative growth factors play in cell physiology and in human diseases. Here, we show that a functional link between phosphatidylinositol-3-OH kinase (PI3K) and Ras is suppressed by the beta-galactoside binding protein (betaGBP) molecule, a cytokine and a negative cell-cycle regulator. Ras-mitogen-activated protein kinase (MAPK) signalling is blocked by betaGBP owing to its ability to inhibit the p110 catalytic subunit of PI3K, whose basal activity is required for Ras activation. Functional inhibition of p110 by betaGBP results in downregulation of PI3K activity, suppression of Ras-GTP loading, consequent loss of MAPK activation and block of cell proliferation. This study sheds light on the molecular mechanisms whereby betaGBP can control cell proliferation and, by extension, may potentially control tumorigenesis by controlling PI3K.

Overcoming drug-resistant cancer by a newly developed copper chelate through host-protective cytokine-mediated apoptosis

PURPOSE

Previously, we have synthesized and characterized a novel Cu(II) complex, copper N-(2-hydroxy acetophenone) glycinate (CuNG). Herein, we have determined the efficacy of CuNG in overcoming multidrug-resistant cancer using drug-resistant murine and human cancer cell lines.

EXPERIMENTAL DESIGN

Action of CuNG following single i.m. administration (5 mg/kg body weight) was tested in vivo on doxorubicin-resistant Ehrlich ascites carcinoma (EAC/Dox)-bearing mice and doxorubicin-resistant sarcoma 180-bearing mice. Tumor size, ascitic load, and survival rates were monitored at regular intervals. Apoptosis of cancer cells was determined by cell cycle analysis, confocal microscopy, Annexin V binding, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay ex vivo. IFN-gamma and tumor necrosis factor-alpha were assayed in the culture supernatants of in vivo and in vitro CuNG-treated splenic mononuclear cells from EAC/Dox-bearing mice and their apoptogenic effect was determined. Source of IFN-gamma and changes in number of T regulatory marker-bearing cells in the tumor site following CuNG treatment were investigated by flow cytometry. Supernatants of in vitro CuNG-treated cultures of peripheral blood mononuclear cells from different drug-insensitive cancer patients were tested for presence of the apoptogenic cytokine IFN-gamma and its involvement in induction of apoptosis of doxorubicin-resistant CEM/ADR5000 cells.

RESULTS

CuNG treatment could resolve drug-resistant cancers through induction of apoptogenic cytokines, such as IFN-gamma and/or tumor necrosis factor-alpha, from splenic mononuclear cells or patient peripheral blood mononuclear cells and reduce the number of T regulatory marker-bearing cells while increase infiltration of IFN-gamma-producing T cells in the ascetic tumor site.

CONCLUSION

Our results show the potential usefulness of CuNG in immunotherapy of drug-resistant cancers irrespective of multidrug resistance phenotype.

Targeted induction of apoptosis for cancer therapy: current progress and prospects

Important breakthroughs in cancer therapy include clinical application of antibodies, such as Rituximab, and small inhibitory molecules, such as Iressa and Velcade. In addition, recent reports have indicated the therapeutic potential of physiological pro-apoptotic proteins such as TRAIL and galectin-1. Although unrelated at first glance, each strategy relies on the deliberate and selective induction of apoptosis in malignant cells. Importantly, therapy-resistance in cancer is frequently associated with de-regulation in the mechanisms that control apoptosis. However, cancer cells are often reliant on these molecular aberrations for survival. Therefore, selective induction of apoptosis in cancer cells but not normal cells seems feasible. Here, we review recent progress and prospects of selected novel anti-cancer approaches that specifically target and sensitize cancer cells to apoptosis.