Epigenetic factors and mitochondrial biology in yeast: A new paradigm for the study of cancer metabolism?

Bidirectional cross-talk between nuclear and mitochondrial DNA is fundamental for cell homeostasis. Epigenetic mechanisms regulate the inter-organelle communication between nucleus and mitochondria. Recent research highlights not only the retrograde activation of nuclear gene transcription in case of mitochondria dysfunction, but also the role of post-translational modifications of mitochondrial proteins in respiratory metabolism. Here we discuss some aspects and novel findings in Saccharomyces cerevisiae. In yeast, KAT-Gcn5 and DUB-Ubp8 have a role in respiration and are localized, as single proteins, into mitochondria. These findings, beside the canonical and widely known nuclear activity of SAGA complex in chromatin regulation, provide novel clues on promising aspects linking evolutionary conserved epigenetic factors to the re-programmed metabolism of cancer cells

Angiopoietin decoy secreted at tumor site impairs tumor growth and metastases by inducing local inflammation and altering neoangiogenesis

The extracellular domain of the receptor tyrosine kinase Tie2/TEK (exTEK) has been used as an angiopoietin decoy to study the role of angiopoietins in the tumor-host interactions, using a syngeneic model of experimental metastases and subcutaneous tumor. Soluble exTEK secreted by transfected tumor cells inhibited HUVECs from forming tubes in Matrigel. ExTEK-transfected C26 colon carcinoma and TS/A mammary tumor cells displayed reduced growth rate when injected subcutaneously, and reduced ability to form experimental metastases when injected intravenously. Immunohistochemical analysis of tumors and metastases showed increased leukocytes infiltration and signs of inflammation in exTEK-secreting compared to parental tumor, as well as impairment in neo-vessel growth and organization. However, while neoangiogenesis eventually rescued in the subcutis, it failed to organize in the experimental metastases of exTEK-secreting tumor, contributing to the hampering of metastatic growth and to increased mice survival. The reactive infiltrate of C26TEK contained a different percentage of leukocytes and was responsible for the tumor inhibition. In fact, leukopenia induced by gamma-irradiation of recipient mice or injection into interferon gamma (IFN-gamma) gene knockout (GKO) mice resulted in reduced mouse survival and an increased number of lung metastases. On the other hand, interleukin (IL)-12 treatment prolonged the survival of mice bearing subcutaneous C26TEK but not of those bearing lung metastases, suggesting that IL-12 could exert further antiangiogenic effects at the site where the tumor can restore neoangiogenesis. These results show in vivo that reduced angiopoietin availability at the tumor site induces a local inflammatory response and impairment of neoangiogenesis which act synergistically to limit tumor growth and metastasis

Stem-like and highly invasive prostate cancer cells expressing CD44v8-10 marker originate from CD44-negative cells

In human prostate cancer (PCa), the neuroendocrine cells, expressing the prostate cancer stem cell (CSC) marker CD44, may be resistant to androgen ablation and promote tumor recurrence. During the study of heterogeneity of the highly aggressive neuroendocrine PCa cell lines PC3 and DU-145, we isolated and expanded in vitro a minor subpopulation of very small cells lacking CD44 (CD44neg). Unexpectedly, these sorted CD44neg cells rapidly and spontaneously converted to a stable CD44high phenotype specifically expressing the CD44v8-10 isoform which the sorted CD44high subpopulation failed to express. Surprisingly and potentially interesting, in these cells expression of CD44v8-10 was found to be induced in stem cell medium. CD44 variant isoforms are known to be more expressed in CSC and metastatic cells than CD44 standard isoform. In agreement, functional analysis of the two sorted and cultured subpopulations has shown that the CD44v8-10pos PC3 cells, resulting from the conversion of the CD44neg subpopulation, were more invasive in vitro and had a higher clonogenic potential than the sorted CD44high cells, in that they produced mainly holoclones, known to be enriched in stem-like cells. Of interest, the CD44v8-10 is more expressed in human PCa biopsies than in normal gland. The discovery of CD44v8-10pos cells with stem-like and invasive features, derived from a minoritarian CD44neg cell population in PCa, alerts on the high plasticity of stem-like markers and urges for prudency on the approaches to targeting the putative CSC

HOXB7: a key factor for tumo-associated angiogenic switch.

We had demonstrated previously a functional bridge between altered homebox (HOX) gene expression and tumor progression through HOXB7 transactivation of basic fibroblast growth factor. Here, we have studied whether HOXB7, in addition to basic fibroblast growth factor, may induce other genes directly or indirectly related to neoangiogenesis and tumor invasion. Parental, beta-galactosidase-transduced, and HOXB7-transduced SkBr3 cell lines were examined for the expression of several growth factors and growth factor receptors involved in the proliferative and angiogenic processes. Vascular endothelial growth factor, melanoma growth-stimulatory activity/growth-related oncogenene alpha, interleukin-8, and angiopoietin-2 were up-regulated by HOXB7 transduction. The exception was angiopoietin-1 expression that was abrogated. Additional analyses included the expression levels of enzymes such as matrix metalloprotease (MMP)-2 and MMP-9 and heparanase, capable of proteolytic degradation of extracellular matrix and basement membranes. Results showed an induction of only MMP-9. The functional implication of such a finding was tested using an in vitro coculture assay in a three-dimensional matrix. A delay of differentiation with persistent nests of proliferating cells was found in endothelial cells cocultured with HOXB7-transduced SkBr3 cells. Tumorigenicity of these cells has been evaluated in vivo. Xenograft into athymic nude mice showed that SkBr3/HOXB7 cells developed tumors in mice, either irradiated or not, whereas parental SkBr3 cells did not show any tumor take unless mice were sublethally irradiated. Comparison of tumor nodules for vascularization by CD-31 and CD-34 immunostaining revealed an increased number of blood vessels in tumors expressing HOXB7. Together, the results indicate HOXB7 as a key factor up-regulating a variety of proangiogenic stimuli. Thus, HOXB7 gene or protein is a target to aim at to inhibit tumor-associated neoangiogenesis, considering the number and the redundancy of proangiogenic molecules that should be targeted one by one to theoretically achieve the same effect

The chemokine receptor CCR8 is preferentially expressed in Th2 but not Th1 cells

In this paper we report on the cloning and characterization of mouse CCR8. Like its human homologue, it is predominantly expressed in the thymus. In the periphery, murine CCR8 mRNA was found most abundantly expressed in activated Th2-polarized cells and in NK1.1+ CD4+ T cells. Human CCR8 is also preferentially expressed in human Th2-polarized cells and clones. This pattern of expression suggests that CCR8 is part of a Th2-specific gene expression program. The CCR8 ligands I-309 and its mouse homologue T cell activation gene 3 (TCA-3) are potent chemoattractants for Th2-polarized cells. Taken together, these observations strongly suggest that CCR8 plays a role in the control of Th2 responses, and may represent a potential target for treatment of allergic diseases

Regulation of TCL1 expression in B- and T-cell lymphomas and reactive lymphoid tissues

Chromosomal rearrangements observed in T-cell prolymphocytic leukemia involve the translocation of one T-cell receptor gene to either chromosome 14q32 or Xq28, deregulating the expression of cellular proto-oncogenes of unknown function, such as TCL1 or its homologue, MTCP1. In the human hematopoietic system, TCL1 expression is predominantly observed in developing B lymphocytes, whereas its overexpression in T cells causes mature T-cell proliferation in transgenic mice. In this study, using a newly generated monoclonal antibody against recombinant TCL1 protein, we extended our analysis mainly by immunohistochemistry and also by fluorescence-activated cell sorting and Western blot to a large tumor lymphoma data bank including 194 cases of lymphoproliferative disorders of B- and T-cell origin as well as reactive lymphoid tissues. The results obtained show that in reactive lymphoid tissues, TCL1 is strongly expressed by a subset of mantle zone B lymphocytes and is expressed to a lesser extent by follicle center cells and by scattered interfollicular small lymphocytes. In B-cell neoplasia, TCL1 was expressed in the majority of the cases, including lymphoblastic lymphoma, chronic lymphocytic leukemia, mantle cell lymphoma, follicular lymphoma, Burkitt lymphoma, diffuse large B-cell lymphoma (60%), and primary cutaneous B cell lymphoma (55%). TCL1 expression was observed in both the cytoplasmic and nuclear compartments, as confirmed by Western blot analysis. Conversely, TCL1 was not expressed in Hodgkin/Reed-Sternberg cells, multiple myelomas, marginal zone B-cell lymphomas, CD30+ anaplastic large cell lymphoma, lymphoblastic T-cell lymphoma, peripheral T-cell lymphoma, and mycosis fungoides. These data indicate that TCL1 is expressed in more differentiated B cells, under both reactive and neoplastic conditions, from antigen committed B cells and in germinal center B cells and is down-regulated in the latest stage of B-cell differentiation

Novel ACTA1 mutation causes late-presenting nemaline myopathy with unusual dark cores

ACTA1 gene encodes the skeletal muscle alpha-actin, the core of thin filaments of the sarcomere. ACTA1 mutations are responsible of several muscle disorders including nemaline, cores, actin aggregate myopathies and fiber-type disproportion. We report clinical, muscle imaging, histopatological and genetic data of an Italian family carrying a novel ACTA1 mutation. All affected members showed a late-presenting, diffuse muscle weakness with sternocleidomastoideus and temporalis atrophy. Mild dysmorphic features were also detected. The most affected muscles by muscle MRI were rectus abdominis, gluteus minimus, vastus intermedius and both gastrocnemii. Muscle biopsy showed the presence of nemaline bodies with several unusual dark areas at Gomori Trichrome, corresponding to unstructured cores with abundant electrodense material by electron microscopy. The molecular analysis revealed missense variant c.148G>A; p.(Gly50Ser) in the exon 3 of ACTA1, segregating with affected members in the family. We performed a functional essay of fibre contractility showing a higher pCa50 (a measure of the calcium sensitivity of force) of type 1 fibers compared to control subjects’ type 1 muscle fibers. Our findings expand the clinico-pathological spectrum of ACTA1-related congenital myopathies and the genetic spectrum of core-rod myopathies

Neutrophils in cancer: neutral no more

Neutrophils are indispensable antagonists of microbial infection and facilitators of wound healing. In the cancer setting, a newfound appreciation for neutrophils has come into view. The traditionally held belief that neutrophils are inert bystanders is being challenged by the recent literature. Emerging evidence indicates that tumours manipulate neutrophils, sometimes early in their differentiation process, to create diverse phenotypic and functional polarization states able to alter tumour behaviour. In this Review, we discuss the involvement of neutrophils in cancer initiation and progression, and their potential as clinical biomarkers and therapeutic targets