Bruno Nervi

Chemosensitization of acute myeloid leukemia (AML) following mobilization by the CXCR4 antagonist AMD3100

The CXCR4-SDF-1 axis plays a central role in the trafficking and retention of normal and malignant stem cells in the bone marrow (BM) microenvironment. Here, we used a mouse model of acute promyelocytic leukemia (APL) and a small molecule competitive antagonist of CXCR4, AMD3100, to examine the interaction of mouse APL cells with the BM microenvironment. APL cells from a murine cathepsin G-PML-RARalpha knockin mouse were genetically modified with firefly luciferase (APL(luc)) to allow tracking by bioluminescence imaging. Coculture of APL(luc) cells with M2-10B4 stromal cells protected the leukemia cells from chemotherapy-induced apoptosis in vitro. Upon injection into syngeneic recipients, APL(luc) cells rapidly migrated to the BM followed by egress to the spleen then to the peripheral blood with death due to leukostasis by day 15. Administration of AMD3100 to leukemic mice induced a 1.6-fold increase in total leukocytes and a 9-fold increase of circulating APL blast counts, which peak at 3 hours and return to baseline by 12 hours. Treatment of leukemic mice with chemotherapy plus AMD3100 resulted in decreased tumor burden and improved overall survival compared with mice treated with chemotherapy alone. These studies provide a proof-of-principle for directing therapy to the critical tethers that promote AML-niche interactions.

Cytokines and hematopoietic stem cell mobilization

Hematopoietic stem cell transplantation (HSCT) has become the standard of care for the treatment of many hematologic malignancies, chemotherapy sensitive relapsed acute leukemias or lymphomas, multiple myeloma; and for some non‐malignant diseases such as aplastic anemia and immunodeficient states. The hematopoietic stem cell (HSC) resides in the bone marrow (BM). A number of chemokines and cytokines have been shown in vivo and in clinical trials to enhance trafficking of HSC into the peripheral blood. This process, termed stem cell mobilization, results in the collection of HSC via apheresis for both autologous and allogeneic transplantation. Enhanced understanding of HSC biology, processes involved in HSC microenvironmental interactions and the critical ligands, receptors and cellular proteases involved in HSC homing and mobilization, with an emphasis on G‐CSF induced HSC mobilization, form the basis of this review. We will describe the key features and dynamic processes involved in HSC mobilization and focus on the key ligand‐receptor pairs including CXCR4/SDF1, VLA4/VCAM1, CD62L/PSGL, CD44/HA, and Kit/KL. In addition we will describe food and drug administration (FDA) approved and agents currently in clinical development for enhancing HSC mobilization and transplantation outcomes. J. Cell. Biochem. 99: 690–705, 2006.

AMD3100: CXCR4 antagonist and rapid stem cell-mobilizing agent

As hematopoietic stem cells collected from peripheral blood are increasingly used for autologous and allogeneic stem cell transplantation, new approaches for the mobilization of stem cells are needed. These should have the goal of improving stem cell collection and reducing the duration and toxicity of the mobilization process. AMD3100, a specific inhibitor of CXCR4, one of the key molecules that tethers hematopoietic stem cells to the bone marrow microenvironment, is a promising new agent currently in clinical development for autologous and allogeneic stem cell mobilization. Early clinical trials have demonstrated that AMD3100 rapidly mobilizes stem cells to the peripheral blood, with minimal side effects. In Phase II trials, mobilization with the combination of AMD3100 and granulocyte colony-stimulating factor (G-CSF) results in the collection of more progenitor cells than G-CSF alone.

Molecular classification of gastric cancer: Towards a pathway-driven targeted therapy

Gastric cancer (GC) is the third leading cause of cancer mortality worldwide. Although surgical resection is a potentially curative approach for localized cases of GC, most cases of GC are diagnosed in an advanced, non-curable stage and the response to traditional chemotherapy is limited. Fortunately, recent advances in our understanding of the molecular mechanisms that mediate GC hold great promise for the development of more effective treatment strategies. In this review, an overview of the morphological classification, current treatment approaches, and molecular alterations that have been characterized for GC are provided. In particular, the most recent molecular classification of GC and alterations identified in relevant signaling pathways, including ErbB, VEGF, PI3K/AKT/mTOR, and HGF/MET signaling pathways, are described, as well as inhibitors of these pathways. An overview of the completed and active clinical trials related to these signaling pathways are also summarized. Finally, insights regarding emerging stem cell pathways are described, and may provide additional novel markers for the development of therapeutic agents against GC. The development of more effective agents and the identification of biomarkers that can be used for the diagnosis, prognosis, and individualized therapy for GC patients, have the potential to improve the efficacy, safety, and cost-effectiveness for GC treatments.

Bone marrow stromal cells modulate mouse ent1 activity and protect leukemia cells from cytarabine induced apoptosis

Background Despite a high response rate to chemotherapy, the majority of patients with acute myeloid leukemia (AML) are destined to relapse due to residual disease in the bone marrow (BM). The tumor microenvironment is increasingly being recognized as a critical factor in mediating cancer cell survival and drug resistance. In this study, we propose to identify mechanisms involved in the chemoprotection conferred by the BM stroma to leukemia cells. Methods Using a leukemia mouse model and a human leukemia cell line, we studied the interaction of leukemia cells with the BM microenvironment. We evaluated in vivo and in vitro leukemia cell chemoprotection to different cytotoxic agents mediated by the BM stroma. Leukemia cell apoptosis was assessed by flow cytometry and western blotting. The activity of the equilibrative nucleoside transporter 1 (ENT1), responsible for cytarabine cell incorporation, was investigated by measuring transport and intracellular accumulation of 3H-adenosine. Results Leukemia cell mobilization from the bone marrow into peripheral blood in vivo using a CXCR4 inhibitor induced chemo-sensitization of leukemia cells to cytarabine, which translated into a prolonged survival advantage in our mouse leukemia model. In vitro, the BM stromal cells secreted a soluble factor that mediated significant chemoprotection to leukemia cells from cytarabine induced apoptosis. Furthermore, the BM stromal cell supernatant induced a 50% reduction of the ENT1 activity in leukemia cells, reducing the incorporation of cytarabine. No protection was observed when radiation or other cytotoxic agents such as etoposide, cisplatin and 5-fluorouracil were used. Conclusion The BM stroma secretes a soluble factor that significantly protects leukemia cells from cytarabine-induced apoptosis and blocks ENT1 activity. Strategies that modify the chemo-protective effects mediated by the BM microenvironment may enhance the benefit of conventional chemotherapy for patients with AML.

CXCR4 and mobilization of hematopoietic precursors.

The binding of the chemokine [C-X-C motif] ligand 12 (CXCL12 or stromal cell-derived factor 1alpha [SDF-1alpha]) constitutively produced by bone marrow stromal cells and osteoblasts, to the CXC receptor (CXCR) 4, a transmembrane chemokine receptor expressed on hematopoietic stem and progenitor cells (HSPCs), has emerged as a key signal for HSPC trafficking to and from the bone marrow. Disruption of CXCL12/CXCR4 signaling causes leukocytosis, with the release of HSPCs, neutrophils, and lymphocytes into the peripheral blood. Although mobilized peripheral blood has become the preferred source of stem cells for both autologous and allogeneic transplantation, the optimum strategy for obtaining mobilized products from donors is the subject of ongoing study. Granulocyte colony-stimulating factor (G-CSF) and plerixafor (AMD3100) are two agents used clinically to induce HSPC mobilization by disruption of the CXCL12/CXCR4 interaction. This chapter describes current procedures used to phenotypically and functionally characterize murine and human HSPCs mobilized by G-CSF or plerixafor.

Targeting specific molecular pathways holds promise for advanced gallbladder cancer therapy

Gallbladder cancer is the most common and aggressive malignancy of the biliary tract. The complete surgical resection is the only potentially curative approach in early stage; however, most cases are diagnosed in advanced stages and the response to traditional chemotherapy and radiotherapy is extremely limited, with modest impact in overall survival. The recent progress in understanding the molecular alterations of gallbladder cancer has shown great promise for the development of more effective treatment strategies. This has mainly resulted from the identification of molecular alterations in relevant intracellular signaling pathways-Hedgehog, PI3K/AKT/mTOR, Notch, ErbB, MAPK and angiogenesis-which are potential tailored targets for gallbladder cancer patients. This review discusses the recent remarkable progress in understanding the molecular alterations that represent novel prognosis molecular markers and therapeutic targets for gallbladder cancer, which will provide opportunities for research and for developing innovative strategies that may enhance the benefit of conventional chemotherapy, or eventually modify the fatal natural history of this orphan disease.

Tratamiento y prevención de la mucositis oral asociada al tratamiento del cáncer

One of the most common and troublesome complications of modern intensive anticancer treatments is oral mucositis. The purpose of this review is to summarize current evidence and clinical guidelines regarding its prevention and therapy. The use of keratinocyte growth factor-1, supplementary glutamine and other recently developed treatment modalities are discussed. The injury of the oral mucosa caused by antineoplastic agents promotes the local expression of multiple pro-inflammatory and pro-apoptotic molecules and eventually leads to the development of ulcers. Such lesions predispose patients to several infectious and nutritional complications. Also, they lead to modification of treatment schedules, potentially affecting overall prognosis. Local cryotherapy with ice chips and phototherapy with low energy laser may be useful as preventive measures. Mouthwashes with allopurinol and phototherapy with low energy laser can be used as treatment. In radiotherapy, special radiation administration techniques should be used to minimize mucosal injury. Pain control should always be optimized, with the use of patient controlled analgesia and topical use of morphine. Supplemental glutamine should not be used outside of research protocols. Lastly, thorough attention should be paid to general care and hygiene measures.

Symptom Control and Palliative Care in Chile

As in other developed and developing countries, the most common chronic disorders affecting the Chilean population are cardiovascular disease, cancer, cirrhosis, diabetes, chronic obstructive pulmonary disease and external injuries. Availability of oncology services is not extensive and there are no academic programs to adequately train practitioners in either palliative medicine or comprehensive palliative care for allied health professionals including nurses, psychologists and chaplains. Major efforts have been made to incorporate palliative care as an important health care focus in the last decade and in the development of effective policies for opioid availability. Chile now meets 84% of the 17 criteria outlined by the World Health Organization and the International Narcotics Control Board for opioid availability. Postgraduate medical education in symptom control, clinical use of opioids and end-of-life care remains relatively poor as judged by the results of a questionnaire administered to 158 resident physicians at the Pontificia Universidad Católica de Chile. Improvements in symptom control and the development of palliative care in Chile will depend on the effective assessment of symptom control effectiveness and improved education and training of health professionals in clinical pharmacology, symptom control, clinical ethics, and end-of-life care.

The CCL2/CCR2 Axis Affects Transmigration and Proliferation but Not Resistance to Chemotherapy of Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) has a high mortality rate despite chemotherapy and transplantation. Both CXCR4/SDF-1 and VLA-4/VCAM1 axes are involved in leukemia protection but little is known about the role of CCL2/CCR2 in AML biology and protection against chemotherapy. We measured CCR2 expression in AML cell lines and primary AML cells by flow cytometry (FCM), real time PCR (RT-PCR) and western blot (WB). CCL2 production was quantified by solid phase ELISA in peripheral blood (PB) and bone marrow (BM) serum. We measured chemotaxis in a transwell system with different concentrations of CCL2/CCR2 blockers; cell cycle with BrDU and propidium iodide and proliferation with yellow tetrazolium MTT. We determined synergy in in vitro cell apoptosis combining chemotherapy and CCL2/CCR2 blockade. Finally, we performed chemoprotection studies in an in vivo mouse model. Of 35 patients, 23 (65%) expressed CCR2 by FCM in PB. Two cell lines expressed high levels of CCR2 (THP-1 and murine AML). RT-PCR and WB confirmed CCR2 production. CCL2 solid phase ELISA showed significantly lower levels of CCL2 in PB and BM compared to normal controls. Chemotaxis experiments confirmed a dose-dependent migration in AML primary cells expressing CCR2 and THP-1 cells. A significant inhibition of transmigration was seen after CCL2/CCR2 blockade. Proliferation of CCR2+ AML cell lines was slightly increased (1.4-fold) after axis stimulation. We observed a non-significant increase in phase S THP-1 cells exposed to CCL2 and a concomitant decrease of cells in G1. The chemotherapy studies did not show a protective effect of CCL2 on cytarabine-induced apoptosis or synergy with chemotherapy after CCL2/CCR2 blockade both in vitro and in vivo. In conclusion, CCL2/CCR2 axis is expressed in the majority of monocytoid AML blasts. The axis is involved in cell trafficking and proliferation but no in vitro and in vivo chemotherapy protective effect was seen.