Cachexia is a multifactorial wasting syndrome most common in patients with cancer that is characterized by the uncontrolled loss of adipose and muscle mass. We show that the inhibition of lipolysis through genetic ablation of adipose triglyceride lipase (Atgl) or hormone-sensitive lipase (Hsl) ameliorates certain features of cancer-associated cachexia (CAC). In wild-type C57BL/6 mice, the injection of Lewis lung carcinoma or B16 melanoma cells causes tumor growth, loss of white adipose tissue (WAT), and a marked reduction of gastrocnemius muscle. In contrast, Atgl-deficient mice with tumors resisted increased WAT lipolysis, myocyte apoptosis, and proteasomal muscle degradation and maintained normal adipose and gastrocnemius muscle mass. Hsl-deficient mice with tumors were also protected although to a lesser degree. Thus, functional lipolysis is essential in the pathogenesis of CAC. Pharmacological inhibition of metabolic lipases may help prevent cachexia.

No abstract

The HIV-1 Rev protein plays a key role in the late phase of virus replication. It binds to the Rev Response Element found in underspliced HIV mRNAs, and drives their nuclear export by the CRM1 receptor pathway. Moreover, mounting evidence suggests that Rev has additional functions in viral replication. Here we employed proteomics and statistical analysis to identify candidate host cell factors that interact with Rev. For this we studied Rev complexes assembled in vitro with nuclear or cytosolic extracts under conditions emulating various intracellular environments of Rev. We ranked the protein-protein interactions by combining several statistical features derived from pairwise comparison of conditions in which the abundance of the binding partners changed. As a validation set, we selected the eight DEAD/H box proteins of the RNA helicase family from the top-ranking 5% of the proteins. These proteins all associate with ectopically expressed Rev in immunoprecipitates of cultured cells. From gene knockdown approaches, our work in combination with previous studies indicates that six of the eight DEAD/H proteins are linked to HIV production in our cell model. In a more detailed analysis of infected cells where either DDX3X, DDX5, DDX17, or DDX21 was silenced, we observed distinctive phenotypes for multiple replication features, variously involving virus particle release, the levels of unspliced and spliced HIV mRNAs, and the nuclear and cytoplasmic concentrations of these transcripts. Altogether the work indicates that our top-scoring data set is enriched in Rev-interacting proteins relevant to HIV replication. Our more detailed analysis of several Revinteracting DEAD proteins suggests a complex set of functions for the helicases in regulation of HIV mRNAs. HIV-1 utilizes many host cell factors for its replication (1-3), similar to other viruses. There is strong interest in identifying and understanding these components to shed light on the molecular mechanisms of virus replication. Moreover, this can provide the potential for developing new therapeutics. The HIV Rev protein is a key regulator of viral replication that is critical for the late stages of virus replication (4, 5). The bestcharacterized function of Rev involves its potent stimulation of the nuclear export of unspliced and singly spliced ("underspliced") HIV transcripts that encode the viral structural proteins and accessory factors (5). In the absence of Rev, these transcripts are retained in the nucleus because of their incomplete splicing. At the molecular level, Rev binds and oligomerizes along the 351-nt Rev Response Element (RRE) 1 (6) in the env gene that is present in all underspliced HIV transcripts. Rev contains a classical leucine-rich nuclear export sequence that recruits CRM1, a transport receptor of the karyopherin family (7,8). CRM1 commonly is used for nuclear export of cellular proteins, and only infrequently is involved in cellular mRNA export (9, 10). Upon binding to the RRE together with the GTP-bound form of Ran, CRM1 forms the core ...

Anaplastic Large Cell Lymphoma (ALCL) is a Non-Hodgkin lymphoma found in children and young adults with poor survival rates. ALCLs frequently carry a chromosomal translocation that results in expression of the oncoprotein nucleophosmin-anaplastic lymphoma kinase (NPM-ALK). The key molecular downstream events required for NPM-ALK triggered lymphoma growth are still not entirely clear. Here we show that the AP-1 proteins cJun and JunB promote lymphoma development and tumor dissemination in a murine NPM-ALK lymphomagenesis model via transcriptional regulation of PDGFRB. Therapeutic inhibition of PDGFRB markedly prolonged survival of NPM-ALK transgenic mice and increased the efficacy of an ALK-specific inhibitor in transplanted NPM-ALK tumors. Remarkably, inhibition of PDGFRs in a late stage patient with refractory NPM-ALK-positive ALCL resulted in complete and sustained remission within 10 days of treatment. Our data identify PDGFRB as novel cJun/JunB target that could be utilized for a highly effective therapy to cure ALCL. 3ALCLs are T-cell lymphomas 1,2 that comprise 10-20% of all Non-Hodgkin's lymphoma cases in children and 3% in adults 3 . About half of ALCL cases are positive for NPM-ALK fusion proteins caused by t(2;5)(p23;q35) translocation 4 . ALK translocations or point mutations have also been described in DLBCLs (diffuse large B-cell lymphomas) and in several nonlymphoid neoplasms [5][6][7][8] . Inhibition of ALK fusion proteins by specific compounds such as crizotinib showed promising clinical responses in ALCL and NSCLC (non-small cell lung cancer) 9,10 . However, ALK mutations conferring resistance to crizotinib have also been reported 11 .Recent studies have linked NPM-ALK expression to induction of AP-1 transcription factors JunB and cJun 12,13 . To investigate their role in NPM-ALK-driven T-cell lymphomas, we conditionally deleted cJun and/or JunB in T-cells of transgenic mice carrying the human NPM-ALK fusion-tyrosine-kinase under the control of the murine CD4-promotor 14 (CD4-NPM-ALK) (Fig. 1a). Gene deletion was confirmed by DNA genotyping (data not shown), real-time PCR, Western blotting and immunohistochemistry (IHC) (Suppl. (Fig.1b), however, inactivation of both, cJun and JunB, in CD4-NPM-ALK-CD4 ΔΔJun mice resulted in significantly prolonged survival (Fig. 1b). CD4-NPM-ALK-CD4 ΔΔJun lymphomas showed markedly reduced proliferation and significantly increased apoptosis when compared to CD4-NPM-ALK lymphomas ( Fig. 1c; Suppl. Fig. S2a,b). Consistently, (Fig. 2d) suggesting a transcriptional regulation of PDGFRB by Jun proteins. Consistently, AP-1 consensus sequences were identified within the murine PDGFRB promoter and first intron that were conserved among other species (Suppl. Fig. S3b,c) 15,16 . Moreover, analysis of ENCODE transcription factor binding tracks revealed binding of cJun and JunB to the PDGFRB intronic AP-1 site in the human K562 leukemia cell line (Suppl. Fig. S3d) 15,17 . CD4-NPM-ALK-CD4EMSA analysis of nuclear extracts from NPM-ALK lymphomas demonstrated AP-1 DNA ...