Summary Cancer cells couple heightened lipogenesis with lipolysis to produce fatty acid networks that support malignancy. Monoacylglycerol lipase (MAGL) plays a principal role in this process by converting monoglycerides, including the endocannabinoid 2-arachidonoylglycerol (2-AG), to free fatty acids. Here, we show that MAGL is elevated in androgen-independent versus androgen-dependent human prostate cancer cell lines, and that pharmacological or RNA-interference disruption of this enzyme impairs prostate cancer aggressiveness. These effects were partially reversed by treatment with fatty acids or a cannabinoid receptor-1 (CB1) antagonist, and fully reversed by co-treatment with both agents. We further show that MAGL is part of a gene signature correlated with epithelial-to-mesenchymal transition and the stem-like properties of cancer cells, supporting a role for this enzyme in pro-tumorigenic metabolism that, for prostate cancer, involves the dual control of endocannabinoid and fatty acid pathways.

A fusion complementary DNA in the T cell line HSB-2 elucidates a provocative mechanism for the disruption of the putative hematopoietic transcription factor SCL. The fusion cDNA results from an interstitial deletion between a previously unknown locus, SIL (SCL interrupting locus), and the 5' untranslated region of SCL. Similar to 1;14 translocations, this deletion disrupts the SCL 5' regulatory region. This event is probably mediated by V-(D)-J recombinase activity, although neither locus is an immunoglobulin or a T cell receptor. Two other T cell lines, CEM and RPMI 8402, have essentially identical deletions. Thus, in lymphocytes, growth-affecting genes other than immune receptors risk rearrangements.

Lapatinib is well tolerated with clinical activity in heavily pretreated HER-2+, but not EGFR+/HER-2-, IBC. In this study, coexpression of pHER-2 and pHER-3 in tumors seems to predict for a favorable response to lapatinib. These findings warrant further investigation of lapatinib monotherapy or combination therapy in HER-2+ IBC.

The frequency of anaerobic bacteremia in our hospitals is much lower than was suggested in several large studies during the 1970s, probably reflecting a real decline in the incidence. The clinical features of our cases are similar to those of previous studies, and the mortality is still high despite the use of antibiotics effective against anaerobes. Since most patients were thought to have anaerobic infections at the time that cultures were obtained, they were usually treated empirically. Subsequent blood cultures positive for anaerobes infrequently influenced clinical management.

The c-fms protooncogene encodes the receptor for macrophage-colony-stimulating factor (CSF-1). Expression vectors containing either normal or oncogenic pointmutated human c-fins genes were transfected into interleukin 3 (IL-3)-dependent 32D cells in order to determine the effects of CSF-1 signaling in this murine clonal myeloid progenitor cell line. CSF-1 was shown to trigger proliferation in association with monocytic differentiation of the 32D-c-fins cells. Monocytic differentiation was reversible upon removal of CSF-1, implying that CSF-1 was required for maintenance of the monocyte phenotype but was not sufficient to induce an irrevocable commitment to differentiation. Human CSF-1 was also shown to be a potent chemoattractant for 32D-c-fms cells, suggesting that CSF-1 may serve to recruit monocytes from the circulation to tissue sites of inflammation or iu'ury. Although c-fms did not release 32D cells from factor dependence, pointmutated c-fms[S301,F969] (Leu-301 --Ser, Tyr-969 -* Phe) was able to abrogate their IL-3 requirement and induce tumorigenicity. IL-3-independent 32D-c-fms[S301,F969J cells also displayed a mature monocyte phenotype, implying that differentiation did not interfere with progression of these cells to the malignant state. All of these rmdings demonstrate that a single growth factor receptor can specifically couple with multiple intracellular signaling pathways and play a critical role in modulating cell proliferation, differentiation, and migration.

The SIL (SCL interrupting locus) gene was initially discovered at the site of a genomic rearrangement in a T-cell acute lymphoblastic leukemia cell line. This rearrangement, which occurs in a remarkably site-specific fashion, is present in the leukemic cells of 16 to 26% of patients with T-cell acute lymphoblastic leukemia. We have now cloned a normal SIL cDNA from a cell line which does not carry the rearrangement. The SIL cDNA has a long open reading frame of 1,287 amino acids, with a predicted molecular size of 143 kDa. The predicted protein is not homologous with any previously described protein; however, a potential eukaryotic topoisomerase I active site was identified. Cross-species hybridization using a SIL cDNA probe indicated that the SIL gene was conserved in mammals. A survey of human and murine cell lines and tissues demonstrated SIL mRNA to be ubiquitously expressed, at low levels, in hematopoietic cell lines and tissues. With the exception of 11.5-day-old mouse embryos, SIL mRNA was not detected in nonhematopoietic tissues. The genomic structure of SIL was also analyzed. The gene consists of 18 exons distributed over 70 kb, with the 5' portion of the gene demonstrating alternate exon utilization.Nonrandom chromosomal translocations or deletions present in specific malignancies have been recognized for the past 30 years, since the association of the Ph chromosome with chronic myelogenous leukemia (20). The analysis of these recurring chromosomal abnormalities at a molecular level has identified numerous proto-oncogenes and growthaffecting genes (for a review, see reference 23). These rearrangements often occur at the sites of transcriptionally active DNA, which may be in a more open chromatin configuration and thus more susceptible to chromosomal breakage and rejoining (17). Chromosomal breakpoints often involve genes that are important for the growth or development of the cell that undergoes the translocation; the classic example is seen in Burkitt's lymphoma, in which the c-myc and immunoglobulin genes are disrupted and brought into chromosomal contiguity (18).Traditionally, these chromosomal abnormalities have been identified cytogenetically on preparations of metaphase chromosomes. Recently, while investigating the genomic structure of the newly described SCL (TCL5, tal-J) gene (6, 7, 9, 13), a member of the basic helix-loop-helix family of transcription factors, we identified a frequent, site-specific chromosomal deletion that involved SCL and a previously unidentified locus that we called SIL (for SCL interrupting locus) (4). This interstitial deletion is the first known instance whereby two genes, neither one of which is an antigen receptor gene, are joined through the action of the V(D)J recombinase system. The deletion occurs below the level of conventional cytogenetic detection and leads to a fusion mRNA between SIL and SCL. A 5.5-kb SIL transcript, distinct from SCL, was identified in normal tissues by Northern (RNA) blot hybridization (4). To better understand how disruption of the SIL g...

A phosphatidylinositol-3 (PI-3) kinase activity of unknown biological function associates with tyrosine kinase-containing proteins, including a number of growth factor receptors after ligand stimulation. In the platelet-derived growth factor (jPDGF) receptor, phosphorylation of a specific tyrosine residue within the kinase insert domain was required for its interaction with this enzyme. We show that substitutions of phenylalanine for tyrosine residue 731 or 742 within the kinase insert domain of the OLPDGF receptor do not impair PDGF-induced tyrosine phosphorylation of the receptor or of an in vivo substrate, phospholipase C-y. Moreover, phosphatidylinositol turnover in response to ligand stimulation is unaffected. However, both lesions markedly impair receptor association with PI-3 kinase. Antiphosphotyrosine antibody-recoverable PI-3 kinase was also dramatically reduced in PDGF-stimulated cells expressing either mutant receptor. Since neither mutation abolished PDGF-induced mitogenesis or chemotaxis, we conclude that oaPDGF receptor-associated PI-3 kinase activity is not required for either of these major PDGF signalling functions.

The SCL gene, initially discovered at the site of a translocation breakpoint associated with the development of a stem cell leukemia, encodes a protein that contains the highly conserved basic helix-loop- helix (bHLH) motif found in a large array of eukaryotic transcription factors. Recently, we have described a nonrandom, site-specific SCL rearrangement in several T-cell acute lymphoblastic leukemia (ALL) cell lines that juxtaposes SCL with a distinct transcribed locus, SIL. The SIL/SCL rearrangement was found in leukemic blasts from 11 of 70 (16%) newly diagnosed T-cell ALL patients, a prevalence substantially higher than that of the t(11;14) translocation, which has previously been reported as the most frequent nonrandom chromosomal abnormality in T- cell ALL. We did not detect the SIL/SCL rearrangement in the leukemic blasts from 30 patients with B-cell precursor ALL, indicating that the rearrangement was specific for T-cell ALL. Analysis of RNA from these patients indicated that an SIL/SCL fusion mRNA was formed, joining SIL and SCL in a head-to-tail fashion. The fusion occurs in the 5′ untranslated region (UTR) of both genes, preserving the SCL coding region. The net result of this rearrangement is that SCL mRNA expression becomes regulated by the SIL promoter, leading to inappropriate SCL expression. The resultant inappropriate expression of this putative transcription factor may then contribute to leukemic transformation in T-cell ALL.