The role of lysophosphatidic acid (LPA) in cancer is poorly understood. Here we provide evidence for a role of LPA in the progression of breast cancer bone metastases. LPA receptors LPA1, LPA2, and LPA3 were expressed in human primary breast tumors and a series of human breast cancer cell lines. The inducible overexpression of LPA1 in MDA-BO2 breast cancer cells specifically sensitized these cells to the mitogenic action of LPA in vitro. In vivo, LPA1 overexpression in MDA-BO2 cells enhanced the growth of subcutaneous tumor xenografts and promoted bone metastasis formation in mice by increasing both skeletal tumor growth and bone destruction. This suggested that endogenous LPA was produced in the tumor microenvironment. However, MDA-BO2 cells or transfectants did not produce LPA. Instead, they induced the release of LPA from activated platelets which, in turn, promoted tumor cell proliferation and the LPA1-dependent secretion of IL-6 and IL-8, 2 potent bone resorption stimulators. Moreover, platelet-derived LPA deprivation in mice, achieved by treatment with the platelet antagonist Integrilin, inhibited the progression of bone metastases caused by parental and LPA1-overexpressing MDA-BO2 cells and reduced the progression of osteolytic lesions in mice bearing CHO-β3wt ovarian cancer cells. Overall, our data suggest that, at the bone metastatic site, tumor cells stimulate the production of LPA from activated platelets, which enhances both tumor growth and cytokine-mediated bone destruction.
Ahmed Boucharaba, Claire-Marie Serre, Sandra Grès, Jean Sébastien Saulnier-Blache, Jean-Claude Bordet, Julien Guglielmi, Philippe Clézardin, Olivier Peyruchaud
Prostate cancer is currently the most commonly diagnosed noncutaneous malignancy in American men. When metastatic, usually to the bone, the disease is no longer curable and is usually treated palliatively with androgen ablation. However, after conversion to androgen-independent disease, there is no effective therapy currently available. The “T body” approach, which uses genetically reprogrammed lymphocytes derived from the patient and expressing chimeric receptor genes, combines the effector functions of T lymphocytes and NK cells with the ability of antibodies to recognize predefined surface antigens with high specificity and in a non–MHC-restricted manner. We show here the therapeutic efficacy of human lymphocytes bearing erbB2-specific chimeric receptors on human prostate cancer BM lesions in a SCID mouse model after conditioning of the recipient to allow homing and persistent functioning of the adoptively transferred cells. Induction of stromal cell–derived factor-1 production within the BM using low-dose irradiation or cyclophosphamide combined with IL-2 administration enhanced the homing of systemically delivered T bodies, resulting in decreased tumor growth and prostate-specific antigen secretion, prolongation of survival, and even cure of the treated mice. These preclinical studies strongly support the idea that the T body approach has therapeutic potential in disseminated prostate cancer.
Jehonathan H. Pinthus, Tova Waks, Victoria Malina, Keren Kaufman-Francis, Alon Harmelin, Itzhak Aizenberg, Hannah Kanety, Jacob Ramon, Zelig Eshhar
Aberrant activation of the JAK-STAT pathway has been implicated in tumor formation; for example, constitutive activation of JAK2 kinase or the enforced expression of STAT5 induces leukemia in mice. We show here that the Janus kinase TYK2 serves an opposite function. Mice deficient in TYK2 developed Abelson-induced B lymphoid leukemia/lymphoma as well as TEL-JAK2–induced T lymphoid leukemia with a higher incidence and shortened latency compared with WT controls. The cell-autonomous properties of Abelson murine leukemia virus–transformed (A-MuLV–transformed) TYK2–/– cells were unaltered, but the high susceptibility of TYK2–/– mice resulted from an impaired tumor surveillance, and accordingly, TYK2–/– A-MuLV–induced lymphomas were easily rejected after transplantation into WT hosts. The increased rate of leukemia/lymphoma formation was linked to a decreased in vitro cytotoxic capacity of TYK2–/– NK and NKT cells toward tumor-derived cells. RAG2/TYK2 double-knockout mice succumbed to A-MuLV–induced leukemia/lymphoma faster than RAG2–/–TYK2+/– mice. This defines NK cells as key players in tumor surveillance in Abelson-induced malignancies. Our observations provide compelling evidence that TYK2 is an important regulator of lymphoid tumor surveillance.
Dagmar Stoiber, Boris Kovacic, Christian Schuster, Carola Schellack, Marina Karaghiosoff, Rita Kreibich, Eva Weisz, Michaela Artwohl, Olaf C. Kleine, Mathias Muller, Sabina Baumgartner-Parzer, Jacques Ghysdael, Michael Freissmuth, Veronika Sexl
Scatter factor (SF), also known as hepatocyte growth factor, is ubiquitously present in the extracellular matrix of tissues in the form of an inactive precursor (pro-SF). In order to acquire biological activity, pro-SF must be cleaved by specific proteases present on the cell surface. The mature form of SF controls invasive cues in both physiological and pathological processes through activation of its receptor, the Met tyrosine kinase. By substituting a single amino acid in the proteolytic site, we engineered an unprocessable form of pro-SF (uncleavable SF). Using lentivirus vector technology, we achieved local or systemic delivery of uncleavable SF in mice. We provide evidence that (a) uncleavable SF inhibits both protease-mediated pro-SF conversion and active SF–induced Met activation; (b) local expression of uncleavable SF in tumors suppresses tumor growth, impairs tumor angiogenesis, and prevents metastatic dissemination; and (c) systemic expression of uncleavable SF dramatically inhibits the growth of transplanted tumors and abolishes the formation of spontaneous metastases without perturbing vital physiological functions. These data show that proteolytic activation of pro-SF is a limiting step in tumor progression, thus suggesting a new strategy for the treatment or prevention of the malignant conversion of neoplastic lesions.
Massimiliano Mazzone, Cristina Basilico, Silvia Cavassa, Selma Pennacchietti, Mauro Risio, Luigi Naldini, Paolo M. Comoglio, Paolo Michieli
Multiple myeloma in humans is frequently associated with mast cell infiltration and neovascularization, which correlate directly with disease severity, but the mechanisms underlying this relationship remain unclear. Here, we report that primary murine mast cells express angiopoietin-1 (Ang-1) and low levels of VEGF-A but not Ang-2 and that 2 established murine plasmacytoma cell lines express high levels of VEGF-A but little or no Ang-1 or Ang-2. An in vivo angiogenesis assay using extracellular matrix components shows that mast cells and plasmacytoma cells, together, promote marked neovascularization composed of dilated vessels, which is prevented by neutralization of VEGF-A and Ang-1 but is only partially reduced by neutralization of either VEGF-A or Ang-1. Mast cells within extracellular matrix components express Ang-1, and recombinant Ang-1 together with plasmacytoma cells promotes extracellular matrix neovascularization similar to that induced by mast cells. A transplantation assay shows that primary mast cells accelerate tumor growth by established plasmacytoma cell lines and that neutralization of Ang-1 alone or with VEGF-A reduces significantly the growth of plasmacytomas containing mast cells. These results demonstrate that mast cell–derived Ang-1 promotes the growth of plasmacytomas by stimulating neovascularization and provide further evidence supporting a causal relationship between inflammation and tumor growth.
Takayuki Nakayama, Lei Yao, Giovanna Tosato
Peptide deformylase activity was thought to be limited to ribosomal protein synthesis in prokaryotes, where new peptides are initiated with an N-formylated methionine. We describe here a new human peptide deformylase (Homo sapiens PDF, or HsPDF) that is localized to the mitochondria. HsPDF is capable of removing formyl groups from N-terminal methionines of newly synthesized mitochondrial proteins, an activity previously not thought to be necessary in mammalian cells. We show that actinonin, a peptidomimetic antibiotic that inhibits HsPDF, also inhibits the proliferation of 16 human cancer cell lines. We designed and synthesized 33 chemical analogs of actinonin; all of the molecules with potent activity against HsPDF also inhibited tumor cell growth, and vice versa, confirming target specificity. Small interfering RNA inhibition of HsPDF protein expression was also antiproliferative. Actinonin treatment of cells led to a tumor-specific mitochondrial membrane depolarization and ATP depletion in a time- and dose-dependent manner; removal of actinonin led to a recovery of the membrane potential consistent with indirect effects on the electron transport chain. In animal models, oral or parenteral actinonin was well tolerated and inhibited human prostate cancer and lung cancer growth. We conclude that HsPDF is a new human mitochondrial enzyme that may provide a novel selective target for anticancer therapy by use of actinonin-based antibiotics.
Mona D. Lee, Yuhong She, Michael J. Soskis, Christopher P. Borella, Jeffrey R. Gardner, Paula A. Hayes, Benzon M. Dy, Mark L. Heaney, Mark R. Philips, William G. Bornmann, Francis M. Sirotnak, David A. Scheinberg
Evasion of apoptosis is a hallmark of cancer, but the molecular circuitries of this process are not understood. Here we show that survivin, a member of the inhibitor of apoptosis gene family that is overexpressed in cancer, exists in a novel mitochondrial pool in tumor cells. In response to cell death stimulation, mitochondrial survivin is rapidly discharged in the cytosol, where it prevents caspase activation and inhibits apoptosis. Selective targeting of survivin to mitochondria enhances colony formation in soft agar, accelerates tumor growth in immunocompromised animals, and abolishes tumor cell apoptosis in vivo. Therefore, mitochondrial survivin orchestrates a novel pathway of apoptosis inhibition, which contributes to tumor progression.
Takehiko Dohi, Elena Beltrami, Nathan R. Wall, Janet Plescia, Dario C. Altieri
Phosphorylation of the cell adhesion protein CEACAM1 increases insulin sensitivity and decreases insulin-dependent mitogenesis in vivo. Here we show that CEACAM1 is a substrate of the EGFR and that upon being phosphorylated, CEACAM1 reduces EGFR-mediated growth of transfected Cos-7 and MCF-7 cells in response to EGF. Using transgenic mice overexpressing a phosphorylation-defective CEACAM1 mutant in liver (L-SACC1), we show that the effect of CEACAM1 on EGF-dependent cell proliferation is mediated by its ability to bind to and sequester Shc, thus uncoupling EGFR signaling from the ras/MAPK pathway. In L-SACC1 mice, we also show that impaired CEACAM1 phosphorylation leads to ligand-independent increase of EGFR-mediated cell proliferation. This appears to be secondary to visceral obesity and the metabolic syndrome, with increased levels of output of free fatty acids and heparin-binding EGF-like growth factor from the adipose tissue of the mice. Thus, L-SACC1 mice provide a model for the mechanistic link between increased cell proliferation in states of impaired metabolism and visceral obesity.
George A. Abou-Rjaily, Sang Jun Lee, Denisa May, Qusai Y. Al-Share, Anthony M. DeAngelis, Randall J. Ruch, Michael Neumaier, Holger Kalthoff, Sue-Hwa Lin, Sonia M. Najjar
A mouse model involving the human papillomavirus type-16 oncogenes develops cervical cancers by lesional stages analogous to those in humans. In this study the angiogenic phenotype was characterized, revealing intense angiogenesis in high-grade cervical intraepithelial neoplasias (CIN-3) and carcinomas. MMP-9, a proangiogenic protease implicated in mobilization of VEGF, appeared in the stroma concomitant with the angiogenic switch, expressed by infiltrating macrophages, similar to what has been observed in humans. Preclinical trials sought to target MMP-9 and angiogenesis with a prototypical MMP inhibitor and with a bisphosphonate, zoledronic acid (ZA), revealing both to be antiangiogenic, producing effects comparable to a Mmp9 gene KO in impairing angiogenic switching, progression of premalignant lesions, and tumor growth. ZA therapy increased neoplastic epithelial and endothelial cell apoptosis without affecting hyperproliferation, indicating that ZA was not antimitotic. The analyses implicated cellular and molecular targets of ZA’s actions: ZA suppressed MMP-9 expression by infiltrating macrophages and inhibited metalloprotease activity, reducing association of VEGF with its receptor on angiogenic endothelial cells. Given its track record in clinical use with limited toxicity, ZA holds promise as an “unconventional” MMP-9 inhibitor for antiangiogenic therapy of cervical cancer and potentially for additional cancers and other diseases where MMP-9 expression by infiltrating macrophages is evident.
Enrico Giraudo, Masahiro Inoue, Douglas Hanahan
Constitutive activation of signal transducer and activator of transcription 3 (Stat3) has been found in a wide spectrum of human malignancies. Here, we have assessed the effect of Stat3 deficiency on skin tumor development using the 2-stage chemical carcinogenesis model. The epidermis of Stat3-deficient mice showed a significantly reduced proliferative response following treatment with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) because of a defect in G1-to-S-phase cell cycle progression. Treatment with the tumor initiator 7,12-dimethylbenz[a]anthracene (DMBA) resulted in a significant increase in the number of keratinocyte stem cells undergoing apoptosis in the bulge region of hair follicles of Stat3-deficient mice compared with nontransgenic littermates. Notably, Stat3-deficient mice were completely resistant to skin tumor development when DMBA was used as the initiator and TPA as the promoter. Abrogation of Stat3 function using a decoy oligonucleotide inhibited the growth of initiated keratinocytes possessing an activated Ha-ras gene, both in vitro and in vivo. In addition, injection of Stat3 decoy into skin tumors inhibited their growth. To our knowledge, these data provide the first evidence that Stat3 is required for de novo epithelial carcinogenesis, through maintaining the survival of DNA-damaged stem cells and through mediating and maintaining the proliferation necessary for clonal expansion of initiated cells during tumor promotion. Collectively, these data suggest that, in addition to its emerging role as a target for cancer therapy, Stat3 may also be a target for cancer prevention strategies.
Keith Syson Chan, Shigetoshi Sano, Kaoru Kiguchi, Joanne Anders, Nobuyasu Komazawa, Junji Takeda, John DiGiovanni