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Expression of autotaxin and lysophosphatidic acid receptors increases mammary tumorigenesis, invasion, and metastases

ABSTRACT: Lysophosphatidic acid (LPA) acts through high-affinity G protein-coupled receptors to mediate a plethora of physiological and pathological activities associated with tumorigenesis. LPA receptors and autotaxin (ATX/LysoPLD), the primary enzyme producing LPA, are aberrantly expressed in multiple cancer lineages. However, the role of ATX and LPA receptors in the initiation and progression of breast cancer has not been evaluated. We demonstrate that expression of ATX or each edg family LPA receptor in mammary epithelium of transgenic mice is sufficient to induce a high frequency of late-onset, estrogen receptor (ER)-positive, invasive, and metastatic mammary cancer. Thus, ATX and LPA receptors can contribute to the initiation and progression of breast cancer.

ORGANISM(S): Mus musculus

PROVIDER: GSE15263 | GEO | 2009/06/11

SECONDARY ACCESSION(S): PRJNA116489

REPOSITORIES: GEO

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Project description:Autotaxin (ATX) has been reported to act as a motility and growth factor in a variety of cancer cells. The ATX protein acts as a secreted lysophospholipase D (lysoPLD) by converting lysophosphatidylcholine (LPC) to lysophosphatidic acid (LPA), which signals via G-protein coupled receptors and has important functions in cell migration and proliferation. The current study demonstrates that ATX expression is upregulated and functionally active in FLT3-ITD+ human blasts. ATX expression was also found in normal human CD34+ progenitor cells and selected myeloid and lymphoid subpopulations. Stable transduction of mutant FLT3-ITD increased ATX mRNA in selected cell lines, whereas inhibition of FLT3-ITD signaling by sublethal doses of PKC412 led to a significant down-regulation of ATX. Moreover, results indicate that the Jun N-terminal kinase (JNK) is an important mediator between FLT3 signaling and ATX. In the presence of LPC, ATX expression led to a significant increase of proliferation. LPA caused proliferation of all tested cell lines, regardless of ATX expression and induced chemotaxis in human leukemic cell lines and human CD34+ progenitors. LPC increased chemotaxis, in cells with high expression of endogenous and exogenous ATX, by at least 80% demonstrating the autocrine effect of ATX expression. Inhibition of ATX using a small molecule inhibitor induced selective killing of ATX-expressing cell lines and reduced the motile phenotype observed in this cells. Our data suggest that the production of bioactive LPA through ATX is involved in controlling proliferation and migration during hematopoiesis and that deregulation contributes to the pathogenesis of AML. AML Classes: Molecular/cytogenetic group of acute myeloid leukemia, either internal tandem duplication (FLT3) or FLT3 point mutation (D835) or normal karyotype (NK) or t(8;21) transclocation (t821) or monosomy 7 (mono7) or inversion on chromosome 16 (inv16) or high leukocyte count normal karyotype (HL). FAB (French-American-British) Classification system for acute myeloid leukemia is provided for each sample.

Project description:Brown adipose tissue (BAT) is a thermogenic organ that dissipates stored energy as heat to maintain body temperature in infants and small mammals. This process may also provide protection from development of diet-induced obesity. We found that the bioactive lipid mediator lysophosphatidic acid (LPA) markedly decreases differentiation of cultured primary brown adipocyte precursors, while potent selective inhibitors of the LPA-generating enzyme autotaxin (ATX) promote differentiation. Transgenic mice overexpressing ATX exhibited reduced expression of BAT-related genes in peripheral white adipose tissue and accumulated significantly more fat than wild-type controls when fed a high fat diet. Our results indicate that ATX and its product LPA are physiologically relevant negative regulators of brown fat adipogenesis and suggest that a decrease in peripheral brown adipose tissue results in increased susceptibility to diet-induced obesity in mice. Primary BAT cell cultures were established as previously reported with some minor modifications (Cannon B., 2001; NÃ©chad M., 1983). Four- to 6-week-old mice were euthanized under aseptic conditions and interscapular BAT (IBAT) dissected, finely minced in digestion buffer containing 123 mM NaCl, 5mM HCl, 1.3 mM CaCl2, 5mM glucose, 1.5% (w/v) crude bovine serum albumin fraction V, 100 mM HEPES, 0.2% collagenase type II (Sigma-Aldrich Corp., St. Louis, MO), pH 7.4, and digested in 10 ml of the same buffer for 30 min at 37Â°C. The supernatant obtained was then filtered using a 250 Âµm nylon mesh and kept in ice for 15 minutes to allow fat droplets and mature cells to float. The resulting infranatant was filtered through a 30 Âµm nylon mesh to enrich the fraction with precursor cells and centrifuged at 700g for 10 min. The pellet obtained was washed once in warm DMEM and resuspended in DMEM medium containing 10% newborn calf serum, 10 mM HEPES, 4mM glutamine, 25 Âµg/ml sodium ascorbate (Sigma-Aldrich Corp., St. Louis, MO)., 100U/ml penicillin and 100mg/ml streptomycin. Cells were seeded onto 35mm dish plates. Insulin treatment was started on day 1 at 50 nM and the concentration increased to 100 nM at day 5 and 200 nM at day 7. Differentiated/confluent cells were collected for biochemical analysis (~day 9). To identify genes regulated by ATX and LPA signaling, 9 DIV primary BAT cultures were treated with the vehicle (DMSO), specific ATX inhibitor HA155 (2.5ÂµM), or LPA (1-Oleoly-LPA, 5ÂµM) (Avanti Polar Lipids, AL, USA) during differentiation. Treatment of the BAT cultures did not affect confluence or markers of proliferation. RNA was extracted from three cultures per condition using TRIzol reagent (Invitrogen, Carlsbad, CA) as described previously (Blalock EM., 2003).

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Expression of autotaxin and lysophosphatidic acid receptors increases mammary tumorigenesis, invasion, and metastases

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