Does primary myelofibrosis involve a defective stem cell niche? From concept to evidence.

Primary myelofibrosis (PMF) is the rarest and the most severe Philadelphia-negative chronic myeloproliferative syndrome. By associating a clonal proliferation and a mobilization of hematopoietic stem cells from bone marrow to spleen with profound alterations of the stroma, PMF is a remarkable model in which deregulation of the stem cell niche is of utmost importance for the disease development. This paper reviews key data suggesting that an imbalance between endosteal and vascular niches participates in the development of clonal stem cell proliferation. Mechanisms by which bone marrow niches are altered with ensuing mobilization and homing of neoplastic hematopoietic stem cells in new or reinitialized niches in the spleen and liver are examined. Differences between signals delivered by both endosteal and vascular niches in the bone marrow and spleen of patients as well as the responsiveness of PMF stem cells to their specific signals are discussed. A proposal for integrating a potential role for the JAK2 mutation in their altered sensitivity is made. A better understanding of the cross talk between stem cells and their niche should imply new therapeutic strategies targeting not only intrinsic defects in stem cell signaling but also regulatory hematopoietic niche-derived signals and, consequently, stem cell proliferation.

Elevated serum cytokines correlated with altered behavior, serum cortisol rhythm, and dampened 24-hour rest-activity patterns in patients with metastatic colorectal cancer.

PURPOSE: Incapacitating symptom burden in cancer patients contributes to poor quality of life (QOL) and can influence treatment outcomes because of poor tolerance to therapy. In this study, the role of circulating cytokines in the production symptoms in cancer patients is evaluated. EXPERIMENTAL DESIGN: Eighty patients with metastatic colorectal cancer with either normal (group I, n = 40) or dampened (group II, n = 40) 24-hour rest/activity patterns measured by actigraphy were identified. Actigraphy patterns were correlated with QOL indices, serum cortisol obtained at 8:00 a.m. and 4:00 p.m. and with serum levels of transforming growth factor-alpha, tumor necrosis factor-alpha, and interleukin 6 (IL-6) obtained at 8:00 a.m. and analyzed in duplicate by ELISA. Cytokine levels and survival were also correlated. RESULTS: Group II patients had significantly higher pre treatment levels of all three cytokines, displayed significantly poorer emotional and social functioning, had higher fatigue, more appetite loss, and poorer performance status compared with group I patients. Transforming growth factor-alpha (TGF-alpha) and IL-6 were significantly increased in the patients with WHO performance status >1 and in those with appetite loss. Fatigue was significantly associated with elevated TGF-alpha only. IL-6 was increased in those patients with extensive liver involvement and multiple organ replacement, and it was significantly correlated with dampened cortisol rhythm. In a multivariate analysis, IL-6 was correlated with poor treatment outcome. CONCLUSIONS: Significant correlations were found between serum levels of TGF-alpha and IL-6, circadian patterns in wrist activity and serum cortisol and tumor-related symptoms in patients with metastatic colorectal cancer. These data support the hypothesis that some cancer patient's symptoms of fatigue, poor QOL, and treatment outcome are related to tumor or host generated cytokines and could reflect cytokine effects on the circadian timing system. This interplay between cytokine signaling pathways, the hypothalamic-pituitary-adrenal axis, the autonomic nervous system, and efferent pathways of the suprachiasmatic nucleus that control circadian physiology, opens the way to new rational interventions for symptom management in cancer patients.

[Geriatric oncology: epidemiological evidence]. / Oncogériatrie : une évidence épidémiologique.

In Europe, 60% of all cancers and 75% of all deaths from cancer occur in patients older than 65 years. The incidence of many cancers (prostate, colorectal, and hematological) either increases with age or remains high (breast and lungs). The two principal characteristics of cancer in the elderly are late diagnosis and comorbidity that requires specific geriatric assessment and cooperation between the oncologist and the geriatrician. Academic and pharmaceutical industry research must focus on the specificities of cancers in the elderly and of response to treatment according to functional abilities and comorbidity. Equal access to high quality medical care and procedures must be ensured, regardless of age; this is not currently the case everywhere.

Combined paclitaxel and cetuximab achieved a major response on the skin metastases of a patient with epidermal growth factor receptor-positive, estrogen receptor-negative, progesterone receptor-negative and human epidermal growth factor receptor-2-negative (triple-negative) breast cancer.

The epidermal growth factor receptor, a transmembrane receptor tyrosine kinase of the erbB family, is expressed in 15-30% of all breast cancers. Anti-epidermal growth factor receptor agent cetuximab is an IgG1 chimeric monoclonal antibody with a potent antitumor activity. Cetuximab competes with ligand binding to the epidermal growth factor receptor ectodomain, resulting in an efficient blockade of tumor-promoting downstream signaling pathways. Large clinical studies recently demonstrated cetuximab synergy with radiotherapy and chemotherapy agent irinotecan. Studies in human breast cancer xenografts showed cetuximab synergy with paclitaxel, a potent mitosis spindle-cell stabilizer. In this report, combined paclitaxel and cetuximab achieved a major reduction of the skin metastases of a heavily pretreated patient with epidermal growth factor receptor-positive, estrogen receptor-negative, progesterone receptor-negative and human epidermal growth factor receptor-2-negative (triple-negative) invasive ductal breast carcinoma. Treatment was well-tolerated overall and response was not correlated with the appearance of major cetuximab-induced acneiform rash.

Chronomodulated irinotecan, oxaliplatin, and leucovorin-modulated 5-Fluorouracil as ambulatory salvage therapy in patients with irinotecan- and oxaliplatin-resistant metastatic colorectal cancer.

PURPOSE: To evaluate the activity and tolerability of salvage chronomodulated chemotherapy combining irinotecan (I), 5-fluorouracil/leucovorin (5-FU/LV), and oxaliplatin (O) (chronoIFLO) in patients with metastatic colorectal cancer (MCRC) and prior progression on four drugs. PATIENTS AND METHODS: Seventy-seven nonhospitalized MCRC patients received chronoIFLO every 3 weeks, with day 1: I (180 mg/m2 over 6 hours, with peak infusion rate at 05:00) and days 2-5: 5-FU/LV (700/300 mg/m2 per day over 12 hours, with peak flow rate at 04:00), and O (20 mg/m2 per day over 12 hours, with peak flow rate at 16:00). Toxicity and response were assessed every 3 weeks and every 2 months, respectively. RESULTS. Three or more prior chemotherapy lines were given to 75% of the patients. Two or more organs had metastatic disease in 65% of the patients. A median number of six courses of chronoIFLO was given. The main grade 3-4 toxicities were diarrhea (39% of the patients, 9% of the courses) and neutropenia (30% of the patients and 7% of the courses). Grade 3 peripheral sensory neuropathy occurred in 14% of the patients. Two patients achieved a partial response and 61 had stable disease, resulting in disease control for 82% of the patients. The median time to progression (TTP) was 5.5 months (95% confidence interval, 3.7-6.0). The median overall survival time was 14.2 months (9.8-17.3). Baseline performance status, serum carcinoembryonic antigen (CEA) level, and CEA doubling time were independent prognostic factors of TTP. CONCLUSIONS: ChronoIFLO safely and durably halted tumor progression in most extensively pretreated MCRC patients.

IL-8 and its CXCR1 and CXCR2 receptors participate in the control of megakaryocytic proliferation, differentiation, and ploidy in myeloid metaplasia with myelofibrosis.

Myeloproliferation, myelofibrosis, and neoangiogenesis are the 3 major intrinsic pathophysiologic features of myeloid metaplasia with myelofibrosis (MMM). The myeloproliferation is characterized by an increased number of circulating CD34+ progenitors with the prominent amplification of dystrophic megakaryocytic (MK) cells and myeloid metaplasia in the spleen and liver. The various biologic activities of interleukin 8 (IL-8) in hematopoietic progenitor proliferation and mobilization as well as in neoangiogenesis prompted us to analyze its potential role in MMM. We showed that the level of IL-8 chemokine is significantly increased in the serum of patients and that various hematopoietic cells, including platelets, participate in its production. In vitro inhibition of autocrine IL-8 expressed by CD34+ cells with either a neutralizing or an antisense anti-IL-8 treatment increases the proliferation of MMM CD34(+)-derived cells and stimulates their MK differentiation. Moreover, addition of neutralizing anti-IL-8 receptor (CXC chemokine receptor 1 [CXCR1] or 2 [CXCR2]) antibodies to MMM CD34+ cells cultured under MK liquid culture conditions increases the proliferation and differentiation of MMM CD41+ MK cells and restores their polyploidization. Our results suggest that IL-8 and its receptors participate in the altered MK growth that features MMM and open new therapeutic prospects for this still incurable disease.

Fibroblasts from human spleen regulate NK cell differentiation from blood CD34(+) progenitors via cell surface IL-15.

Besides a structural role in tissue architecture, fibroblasts have been shown to regulate the proliferation and differentiation of other neighboring specialized cell types, but differently according to the anatomic site and pathologic status of their tissue of origin. In this study we report a novel regulatory function of human spleen-derived fibroblasts in the development of NK cells from adult resting blood progenitors. When CD34(+) cells were cocultured with spleen-derived fibroblasts in monolayers, nonadherent CD56(+)CD3(-) NK cells were predominantly produced after 2-3 wk of culture in the absence of exogenous cytokines. Most NK cells expressed class I-recognizing CD94 and NK p46, p44, and p30 receptors as well as perforin and granzyme lytic granules. Moreover, these cells demonstrated spontaneous killing activity. Cell surface immunophenotyping of spleen-derived fibroblasts revealed a low and consistent expression of IL-15, Flt3 ligand, and c-kit ligand. Additionally, low picogram amounts of the three cytokines were produced extracellularly. Neutralizing Abs to IL-15, but not the other two ligands, blocked NK cell development. Additionally, suppressing direct contacts of CD34(+) progenitors and fibroblasts by microporous membrane abrogated NK cell production. We conclude that stromal fibroblasts within the human spleen are involved via constitutive cell surface expression of bioactive IL-15 in the development of functional activated NK cells under physiologic conditions.

Impaired NK cell differentiation of blood-derived CD34+ progenitors from patients with myeloid metaplasia with myelofibrosis.

Cultured blood CD34(+) progenitors from patients with myeloid metaplasia with myelofibrosis (MMM) failed to differentiate into natural killer (NK) cells with recombinant interleukin (IL)-15. No NK cells either could be induced in coculture with IL-15-expressing fibroblasts from MMM patients' spleens. The impaired NK differentiation could be circumvented by using normal blood CD34(+) cells in the coculture. In this case, cell-to-cell contact and IL-15 interaction were crucial for NK cell differentiation. Pretreatment of normal CD34(+) progenitors with anti-IL-15 monoclonal antibody markedly reduced NK cell production while MMM fibroblast pretreatment did not. Both normal and MMM progenitors constitutively expressed IL-15. Analysis of endogenous IL-15 signaling pathway revealed a constitutive gammac/Jak3 association and STAT3 activation in the two types of progenitors. Anti-IL-15 monoclonal antibody treatment caused a downregulation of IL-15 signaling in normal but not MMM blood cells. The impaired NK differentiation in MMM may thus arise from a deregulated control of an endogenous IL-15 involved in hematopoietic progenitors' lymphoid differentiation.

Effects of anti-CD44 monoclonal antibodies on differentiation and apoptosis of human myeloid leukemia cell lines.

Acute myeloid leukemia (AML) is a heterogeneous leukemia characterized by the blockage of myeloid differentiation at different stages, which define distinct AML subtypes. We have recently reported that the ligation of CD44 with 2 activating monoclonal antibodies (mAbs), A3D8 and H90, triggers terminal differentiation of leukemic blasts in AML-M1/2 to AML-M5 subtypes, which are the most frequent ones. However, fresh AML blasts have short in vitro lifespans. Therefore, to find relevant in vitro cellular models for further studying the mechanisms involved in CD44-induced differentiation, we investigated whether CD44 ligation with A3D8 and H90 mAbs can induce terminal differentiation of THP-1, NB4, and HL60 cells, each interesting models of AML-M5 (monoblastic subtype), AML-M3 (promyelocytic subtype), and AML-M2 (myeloblastic subtype), respectively. We also study whether CD44 ligation induces a loss of proliferative capacity, an important feature of late-stage myeloid differentiation. In the second part of our study, we investigated whether A3D8 and H90 anti-CD44 mAbs can induce the differentiation and inhibit the proliferation of KG1a cells, which are very immature AML-M0 blasts. Using functional, antigenic, and cytologic criteria, we presently show that A3D8 and/or H90 induce terminal differentiation of THP-1, HL60, and NB4 cell lines and strongly inhibit their proliferation. Interestingly, cell-specific effects of H90 and A3D8 are observed. We also observe that incubation with A3D8 for 3 to 6 days induces an apoptotic cell death that is moderate in the case of THP-1 and HL60 cells and massive in the case of NB4 cells. Finally, our results demonstrate for the first time that it is possible to reverse the leukemic blockage of KG1a cells by using both an anti-CD44 mAb and retinoic acid. This result may provide a new experimental basis for a differentiative therapy in AML-M0 patients.

Stromal cell-derived factor 1 regulates primitive hematopoiesis by suppressing apoptosis and by promoting G(0)/G(1) transition in CD34(+) cells: evidence for an autocrine/paracrine mechanism.

The stromal cell-derived factor 1 (SDF-1) chemokine has various effects on hematopoietic cell functions. Its role in migration and homing of hematopoietic progenitors is currently well established. Previously it was shown that SDF-1 stimulates myeloid progenitor proliferation in synergy with cytokines. Results of this study indicate that SDF-1 alone promotes survival of purified CD34(+) cells from human unmobilized peripheral blood (PB) by counteracting apoptosis as demonstrated by its capacity to reduce DNA fragmentation, annexin-V(+) cell number, and APO2.7 detection and to modulate bcl-2 homolog protein expression. The study demonstrates that SDF-1, produced by sorted CD34(+)CD38(+) cells and over-released in response to cell damage, exerts an antiapoptotic effect on CD34(+) cells through an autocrine/paracrine regulatory loop. SDF-1 participates in the autonomous survival of circulating CD34(+) cells and its effect required activation of the phosphotidyl inositol 3 kinase (PI3-K)/Akt axis. Cell sorting based on Hoechst/pyroninY fluorescences shows that SDF-1 production is restricted to cycling CD34(+) cells. SDF-1 triggers G(0) quiescent cells in G(1) phase and, in synergy with thrombopoietin or Steel factor, makes CD34(+) cells progress through S+G(2)/M phases of cell cycle. By assessing sorted CD34(+)CD38(-) and CD34(+)CD38(+) in semisolid culture, the study demonstrates that SDF-1 promotes survival of clonogenic progenitors. In conclusion, the results are the first to indicate a role for endogenous SDF-1 in primitive hematopoiesis regulation as a survival and cell cycle priming factor for circulating CD34(+) cells. The proposal is made that SDF-1 may contribute to hematopoiesis homeostasis by participating in the autonomous survival and cycling of progenitors under physiologic conditions and by protecting them from cell aggression in stress situations.