Modification of expression of stem cell factor by various cytokines

The senescence-associated secretory phenotype promotes benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is characterized by increased tissue mass in the transition zone of the prostate, which leads to obstruction of urine outflow and considerable morbidity in a majority of older men. Senescent cells accumulate in human tissues, including the prostate, with increasing age. Expression of proinflammatory cytokines is increased in these senescent cells, a manifestation of the senescence-associated secretory phenotype. Multiplex analysis revealed that multiple cytokines are increased in BPH, including GM-CSF, IL-1α, and IL-4, and that these are also increased in senescent prostatic epithelial cells in vitro. Tissue levels of these cytokines were correlated with a marker of senescence (cathepsin D), which was also strongly correlated with prostate weight. IHC analysis revealed the multifocal epithelial expression of cathepsin D and coexpression with IL-1α in BPH tissues. In tissue recombination studies in nude mice with immortalized prostatic epithelial cells expressing IL-1α and prostatic stromal cells, both epithelial and stromal cells exhibited increased growth. Expression of IL-1α in prostatic epithelial cells in a transgenic mouse model resulted in increased prostate size and bladder obstruction. In summary, both correlative and functional evidence support the hypothesis that the senescence-associated secretory phenotype can promote the development of BPH, which is the single most common age-related pathology in older men.

c-Jun induces mammary epithelial cellular invasion and breast cancer stem cell expansion

The molecular mechanisms governing breast tumor cellular self-renewal contribute to breast cancer progression and therapeutic resistance. The ErbB2 oncogene is overexpressed in approximately 30% of human breast cancers. c-Jun, the first cellular proto-oncogene, is overexpressed in human breast cancer. However, the role of endogenous c-Jun in mammary tumor progression is unknown. Herein, transgenic mice expressing the mammary gland-targeted ErbB2 oncogene were crossed with c-jun(f/f) transgenic mice to determine the role of endogenous c-Jun in mammary tumor invasion and stem cell function. The excision of c-jun by Cre recombinase reduced cellular migration, invasion, and mammosphere formation of ErbB2-induced mammary tumors. Proteomic analysis identified a subset of secreted proteins (stem cell factor (SCF) and CCL5) induced by ErbB2 expression that were dependent upon endogenous c-Jun expression. SCF and CCL5 were identified as transcriptionally induced by c-Jun. CCL5 rescued the c-Jun-deficient breast tumor cellular invasion phenotype. SCF rescued the c-Jun-deficient mammosphere production. Endogenous c-Jun thus contributes to ErbB2-induced mammary tumor cell invasion and self-renewal.

Intra-arterial transplantation of adult bone marrow cells restores blood flow and regenerates skeletal muscle in ischemic limbs

OBJECTIVE

Bone marrow cell therapy promotes angiogenesis, but the cellular fate of bone marrow cells (BMCs) in the absence of immunosuppressant interventions is unclear. We created a model of severe hind limb ischemia to address whether BMCs form new blood vessels or differentiate into other tissues.

METHODS AND RESULTS

After ligating the common femoral artery in ApoE knockout mice, we injected either phosphate buffered saline (PBS) or 5 x 10(7) adult unfractionated BMCs obtained from green fluorescent protein-positive mice. Laser Doppler imaging of the ischemic limbs revealed that intra-arterial BMCs significantly increased blood flow recovery in ischemic limbs beginning 21 days after surgery and peaking at 27 days (61.8% +/- 15% vs. 41.9% +/- 13.9%, respectively, for BMCs and PBS, P < .05). The BMCs differentiated into small blood vessels, skeletal myofibers, and supporting membranes, and these changes were associated with increased serum levels of vascular endothelial growth factor (VEGF), fibroblast growth factor 2 (FGF-2), transforming growth factor beta (TGFbeta), interleukin 4 (IL-4), and tumor necrosis factor alpha (TNF-alpha).

CONCLUSIONS

Adult BMCs injected into ischemic limbs without immunosuppressant therapy differentiated into blood vessels and skeletal myofibers, and this was associated with accelerated blood flow restoration and increased serum levels of VEGF, FGF-2, TGF-beta, IL-4, and TNF-alpha. Skeletal muscle formation may provide benefits beyond angiogenesis to patients with chronic peripheral arterial disease or to patients with low cardiac output states who also suffer from skeletal muscle atrophy.

Proteomic changes associated with diabetes in the BB-DP rat

These studies were structured with the aim of utilizing emerging technologies in two-dimensional (2D) gel electrophoresis and mass spectrometry to evaluate protein expression changes associated with type 1 diabetes. We reasoned that a broad examination of diabetic tissues at the protein level might open up novel avenues of investigation of the metabolic and signaling pathways that are adversely affected in type 1 diabetes. This study compared the protein expression of the liver, heart, and skeletal muscle of diabetes-prone rats and matched control rats by semiquantitative liquid chromatography-mass spectrometry and differential in-gel 2D gel electrophoresis. Differential expression of 341 proteins in liver, 43 in heart, and 9 (2D gel only) in skeletal muscle was detected. These data were assembled into the relevant metabolic pathways affected primarily in liver. Multiple covalent modifications were also apparent in 2D gel analysis. Several new hypotheses were generated by these data, including mechanisms of net cytosolic protein oxidation, formaldehyde generation by the methionine cycle, and inhibition of carbon substrate oxidation via reduction in citrate synthase and short-chain acyl-CoA dehydrogenase.

Fibroblast growth factor-2 and cardioprotection

Boosting myocardial resistance to acute as well as chronic ischemic damage would ameliorate the detrimental effects of numerous cardiac pathologies and reduce the probability of transition to heart failure. Experimental cardiology has pointed to ischemic and pharmacological pre- as well as post-conditioning as potent acute cardioprotective manipulations. Additional exciting experimental strategies include the induction of true regenerative and/or angiogenic responses to the damaged heart, resulting in sustained structural and functional beneficial effects. Fibroblast growth factor-2 (FGF-2), an endogenous multifunctional protein with strong affinity for the extracellular matrix and basal lamina and well-documented paracrine, autocrine and intracellular modes of action, has been shown over the years to exert acute and direct pro-survival effects, irrespectively of whether it is administered before, during or after an ischemic insult to the heart. FGF-2 is also a potent angiogenic protein and a crucial agent for the proliferation, expansion, and survival of several cell types including those with stem cell properties. Human clinical trials have pointed to a good safety record for this protein. In this review, we will present a case for the low molecular weight isoform of fibroblast growth factor-2 (lo-FGF-2) as a very promising therapeutic agent to achieve powerful acute as well as sustained benefits for the heart, due to its cytoprotective and regenerative properties.

Somatic excision demonstrates that c-Jun induces cellular migration and invasion through induction of stem cell factor

Cancer cells arise through sequential acquisition of mutations in tumor suppressors and oncogenes. c-Jun, a critical component of the AP-1 complex, is frequently overexpressed in diverse tumor types and has been implicated in promoting cellular proliferation, migration, and angiogenesis. Functional analysis of candidate genetic targets using germ line deletion in murine models can be compromised through compensatory mechanisms. As germ line deletion of c-jun induces embryonic lethality, somatic deletion of the c-jun gene was conducted using floxed c-jun (c-jun(f/f)) conditional knockout mice. c-jun-deleted cells showed increased cellular adhesion, stress fiber formation, and reduced cellular migration. The reduced migratory velocity and migratory directionality was rescued by either c-Jun reintroduction or addition of secreted factors from wild-type cells. An unbiased analysis of cytokines and growth factors, differentially expressed and showing loss of secretion upon c-jun deletion, identified stem cell factor (SCF) as a c-Jun target gene. Immunoneutralizing antibody to SCF reduced migration of wild-type cells. SCF addition rescued the defect in cellular adhesion, cellular velocity, directional migration, transwell migration, and cellular invasion of c-jun(-/-) cells. c-Jun induced SCF protein, mRNA, and promoter activity. Induction of the SCF promoter required the c-Jun DNA-binding domain. c-Jun bound to the SCF promoter in chromatin immunoprecipitation assays. Mutation of the c-Jun binding site abolished c-Jun-mediated induction of the SCF promoter. These studies demonstrate an essential role of c-Jun in cellular migration through induction of SCF.

Stem cell factor has a suppressive activity to IgE-mediated chemotaxis of mast cells

Stem cell factor (SCF), which is well known as a cytokine capable of amplifying development and functions of mast cells, is mainly released from fibroblasts in the peripheral tissue. To investigate whether SCF controlled chemotactic migration of mast cells induced by IgE-specific Ag, murine bone marrow-derived cultured mast cells (BMCMC) and human cord blood-derived cultured mast cells (HuCMC) were preincubated with SCF. Although BMCMC and HuCMC sensitized with IgE directly moved toward specific Ag, preincubation for even 1 h with an optimal dose of SCF suppressed the IgE-mediated chemotactic movement. No or little inhibitory effect of SCF was detected in BMCMC derived from c-kit receptor-defect WBB6F1-W/Wv mice. In contrast, preincubation of BMCMC and HuCMC with SCF enhanced beta-hexosaminidase release and Ca2+ mobilization in response to Ag after sensitization with IgE. Using the real-time record of chemotactic migration, BMCMC preincubated with SCF manifested motionless without degranulation. These results suggest that locally produced SCF may have an inhibitory effect on chemotaxis of mast cells, contributing to their accumulation and enhancement of functions at the peripheral site in allergic and nonallergic conditions.

Deletion of membrane-bound steel factor results in osteopenia in mice

To examine the functional role of membrane-bound SLF, we evaluated the growing skeletons of WT and SLF mutant (Sl/Sl(d)) mice that do not produce this protein using DXA, bone histomorphometry, cell culture, and flow cytometry. Deletion of membrane-bound SLF delays bone growth, decreases bone mass and BMD, impairs osteoblast function, and increases osteoclast surface in young mice.

INTRODUCTION

Mutations at the murine steel locus lead to a defect in the development of hematopoietic stem cells, mast cells, and germ cells. Two isoforms of steel factor (SLF), soluble and membrane-associated, have been reported. Soluble SLF increases osteoclast formation and activity in cell culture. The effects of deletion of membrane-bound SLF on bone metabolism in mice have yet to be determined and are the subject of this study.

MATERIALS AND METHODS

Five-, 7-, and 12-week-old male and 5-week-old female WCB6F1/J-Kitl(Sl)/Kitl(Sl-d) (Sl/Sl(d)) mice and wildtype (WT) littermates were used. BMD and bone mass, growth, architecture, and turnover were evaluated by DXA (males and females) and histomorphometry (males only). Primary osteoblasts isolated from humeri of 5-week-old male WT and Sl/Sl(d) mice were used to determine osteoblast function, and bone marrow cells from tibias and femurs of these mice were analyzed to determine cell surface expression of osteoclast precursors.

RESULTS AND CONCLUSIONS

Young Sl/Sl(d) mice grew more slowly, had a reduced bone mass, and had shorter bones than WT littermates. Male mutants had significantly decreased whole body BMD in all age groups, largely because of a reduction in BMC. Tibial cross-sectional, cortical, and marrow area of cortical bone and cancellous bone volume was reduced in the mutants at all ages. The osteopenia in Sl/Sl(d) was caused by increased osteoclast surface at all ages and decreased osteoblast surface at 5 weeks of age. [(3)H]thymidine incorporation studies showed that proliferation of osteoblasts derived from mutant mice was significantly suppressed (56%). Moreover, a decrease in mineralization was observed in Sl/Sl(d) osteoblast culture. Fluorescence-activated cell sorting analysis of bone marrow cells from Sl/Sl(d) mice revealed a 65% increase in the percentage of c-Fms(+)CD11b(+)RANK(+) cells compared with WT controls. These findings suggest that membrane-bound SLF/c-Kit signaling plays a role in the regulation of peak bone mass.

Transforming growth factor-beta signaling in normal and malignant hematopoiesis

Transforming growth factor-beta (TGF-beta) is perhaps the most potent endogenous negative regulator of hematopoiesis. The intracellular signaling events mediating the effects of TGF-beta are multiple, involving extensive crosstalk between Smad-dependent and MAP-kinase-dependent pathways. We are only beginning to understand the importance of the balance between these cascades as a determinant of the response to TGF-beta, and have yet to determine the roles that disruption in TGF-beta signaling pathways might play in leukemogenesis. This review summarizes current knowledge regarding the function of TGF-beta in normal and malignant hematopoiesis. The principal observations made by gene targeting studies in mice are reviewed, with an emphasis on how a disruption of this pathway in vivo can affect blood cell development and immune homeostasis. We overview genetic alterations that lead to impaired TGF-beta signaling in hematopoietic neoplasms, including the suppression of Smad-dependent transcriptional responses by oncoproteins such as Tax and Evi-1, and fusion proteins such as AML1/ETO. We also consider mutations in genes encoding components of the core cell cycle machinery, such as p27(Kip1) and p15(INK4A), and emphasize their impact on the ability of TGF-beta to induce G1 arrest. The implications of these observations are discussed, and opinions regarding important directions for future research on TGF-beta in hematopoiesis are provided.

Marsupialization inhibits interleukin-1α expression and epithelial cell proliferation in odontogenic keratocysts

BACKGROUND

Marsupialization results in the reduction of odontogenic cyst size. Interleukin-1alpha (IL-1alpha) is thought to play a crucial role for the expansion of odontogenic keratocysts. The aim of this study was to investigate the effects of marsupialization on the expression of IL-1alpha and on the proliferating activity of a lining epithelium in odontogenic keratocysts.

METHODS

The concentrations of IL-1alpha, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) in the intracystic fluids of odontogenic keratocysts were measured by the enzyme-linked immunosorbent assay (ELISA). The expression of IL-1alpha mRNA in odontogenic keratocysts was measured before and after marsupialization by in situ hybridization. The expression of IL-1alpha and epithelial cell-proliferating activities in odontogenic keratocysts were also measured by immunohistochemistry using antibodies for human IL-1alpha and Ki-67 antigen, respectively.

RESULTS

The intracystic fluid levels of IL-1alpha were significantly higher than those of IL-6 and TNF-alpha in odontogenic keratocysts. In situ hybridization and immunohistochemistry showed that strong expression of IL-1alpha mRNA and protein was mainly detected in the epithelial cells of odontogenic keratocysts. After marsupialization, the signal intensities for IL-1alpha mRNA and protein were significantly decreased. In addition, the Ki-67 labeling index of the epithelial cells was decreased proportionally with the grade of IL-1alpha mRNA expression after the marsupialization.

CONCLUSION

Our findings suggest that marsupialization may reduce the size of odontogenic keratocyst by inhibiting IL-1alpha expression and the epithelial cell proliferation.

Stem cell factor stimulates neurogenesis in vitro and in vivo

Cerebral ischemia stimulates neurogenesis in proliferative zones of the rodent forebrain. To identify the signaling factors involved, cerebral cortical cultures prepared from embryonic mouse brains were deprived of oxygen. Hypoxia increased bromodeoxyuridine (BrdU) incorporation into cells that expressed proliferation markers and immature neuronal markers and that lacked evidence of DNA damage or caspase-3 activation. Hypoxia-conditioned medium and stem cell factor (SCF), which was present in hypoxia-conditioned medium at increased levels, also stimulated BrdU incorporation into normoxic cultures. The SCF receptor, c-kit, was expressed in neuronal cultures and in neuroproliferative zones of the adult rat brain, and in vivo administration of SCF increased BrdU labeling of immature neurons in these regions. Cerebral hypoxia and ischemia may stimulate neurogenesis through trophic factors, including SCF.

In vivo effects of IL-4, IL-10, and amifostine on cytokine production in patients with acute myelogenous leukemia

Both IL-4 and IL-10 have been shown in vitro to inhibit leukemia cell secretion of IL-1beta, GM-CSF, and TNFalpha, and increase leukemia cell release of IL-1ra. In this study, we have investigated the in vivo effects of IL-4, IL-10, and amifostine on cytokine production in patients with acute myelogenous leukemia (AML). Serum IL-1ra, IL-1beta, TNFalpha, GM-CSF, and SCF levels were measured in AML patients who received IL-4, IL-10, or amifostine. No significant changes in the serum levels of IL-1ra, IL-1beta, TNFalpha, GM-CSF, and SCF were found in AML patients who received amifostine. Both IL-4 and IL-10 were found to increase serum IL-1ra. This data is in accord with the in vitro studies. However, IL-4 increased serum GM-CSF levels and IL-10 increased serum IL-1beta and TNFalpha levels. These in vivo effects of the two cytokines differ from their in vitro effects. Despite the similar effects of IL-4 and IL-10 on cytokine production by AML cells in vitro, different effects were observed in AML patients in vivo. IL-4 increased serum SCF levels, whereas IL-10 decreased serum SCF levels. IL-4 increased serum GM-CSF levels, whereas IL-10 had no effect on them. Although IL-10 increased serum IL-1beta and TNFalpha levels, IL-4 had no effect on them. These findings indicate that the in vitro effects of IL-4 and IL-10 do not necessarily reflect their in vivo effects, and that the complex effects of the two cytokines on serum cytokine levels make it difficult to predict their therapeutic potential.