The tripartite motif protein TRIM24 (tripartite motif-containing 24) has been found to play distinct roles in tumor development and progression, according to different tumor contexts. However, it remains elusive whether TRIM24 plays a role in malignant gliomas that are the most common and deadly primary brain tumors in adults. We report here that TRIM24 expression is positively correlated with glioma malignancy and is negatively associated with prognosis of patients with newly diagnosed glioblastoma, which is the most malignant form of gliomas but displays highly heterogeneous clinical outcome. The multivariate Cox regression analysis demonstrates the independent predictive value of TRIM24 expression level for overall and progression-free survival. Knockdown of TRIM24 suppresses cell proliferation, cell cycle progression, clone formation and in vivo tumor development, whereas overexpression of TRIM24 promotes cell growth. Chromatin immunoprecipitation, real-time reverse transcription-PCR and mutation analyses demonstrate that TRIM24 binds to the PIK3CA promoter via its PHD-Bromo domain to activate the transcription of PIK3CA gene, thus enhancing phosphatidylinositide 3-kinase (PI3K)/Akt signaling. The pan-PI3K inhibitor LY294002 and small interfering RNA targeting PIK3CA both abrogate the growth-promoting effect of TRIM24. Moreover, TRIM24 regulates the expression of DNA repair enzyme O(6)-methylguanine-DNA methyltransferase (MGMT) through PI3K/Akt/nuclear factor-κB signaling transduction and enhances resistance to temozolomide, the standard chemotherapeutic agent for glioblastoma. Finally, glioblastoma patients with low TRIM24 expression benefit from chemotherapy, whereas those with high TRIM24 expression do not have such benefit. Our results suggest that TRIM24 might serve as a potential prognostic marker and therapeutic target for the management of malignant gliomas.

Overexpression of the folate receptor (FR) on cancer cells [1-4] has enabled tumor-selective targeting of folate-drug conjugates to malignant tissues, including cancers of the ovary, cervix, endometrium, kidney, breast, brain, lung, colon, head and neck, and cells of myelogenous origin. Examples of drugs that have been selectively targeted to malignant masses include: i) protein toxins, ii) low molecular weight chemotherapeutic agents, iii) genes, iv) antisense oligonucleotides, v) ribozymes, vi) radioimaging agents, vii) liposomes with entrapped drugs, viii) radiotherapeutic agents, ix) immunotherapeutic agents, x) MRI contrast agents, xi) siRNAs, xii) polymeric drug complexes, and xiv) enzyme constructs for prodrug therapy. In virtually all cases, the folate-targeted drugs have exhibited a significant improvement in potency and cancer cell specificity over nontargeted forms of the same pharmaceutical. Based on this specificity, several folate-targeted drugs are currently in human clinical trials.

28The Gram-negative cell envelope is a remarkable structure with core components that include an 29 inner membrane, an outer membrane, and a peptidoglycan layer in the periplasmic space between. 30Multiple molecular systems function to maintain integrity of this essential barrier between the 31 interior of the cell and its surrounding environment. We show that a conserved DUF1849-family 32 protein, EipB, is secreted to the periplasmic space of Brucella, a monophyletic group of intracellular 33 pathogens. In the periplasm, EipB folds into an unusual fourteen-stranded b-spiral structure that 65 envelope stressors and determines B. abortus virulence in a mouse model of infection (8). In this 66 study, we report a functional and structural analysis of envelope integrity protein B (EipB), a 67 member of the uncharacterized gene family DUF1849. 68 69 3 DUF1849 (Pfam: PF08904, (9)) is widespread among the Rhizobiales, Rhodospirillales and 70 Rhodobacterales (Figure 1). To our knowledge, no functional data have been reported for this gene 71 family other than results from a recent multi-species Tn-seq study that showed stress sensitivity in 72 Sinorhizobium meliloti DUF1849 (locus SMc02102) mutant strains (10). Here we show that the 73 Brucella DUF1849 protein, EipB (locus tag bab1_1186; RefSeq locus BAB_RS21600), is a 280-74 residue periplasmic protein that folds into a 14-stranded, open β-barrel structure containing a 75 conserved disulfide bond. We term this novel barrel structure a β-spiral and show that it resembles 76 the lipoprotein chaperone LolB, though its overall fold is distinct. Replication and survival of a B. 77abortus strain in which we deleted eipB was attenuated in a mouse infection model, and deletion 78 of eipB in both B. abortus and Brucella ovis enhanced sensitivity to compounds that affect the 79 integrity of the cell envelope. We have further shown that B. abortus eipB deletion is synthetically 80 lethal with transposon disruption of gene locus bab1_0430, which encodes a periplasmic 81 tetratricopeptide-repeat (TPR) containing-protein that we have named TtpA. The Brucella 82 melitensis ortholog of TtpA (locus tag BMEI1531) has been previously described as a molecular 83 determinant of mouse spleen colonization (11), while a Rhizobium leguminosarum TtpA homolog 84 (locus tag RL0936) is required for proper cell envelope function (12). We propose that TtpA and 85 EipB coordinately function in the Brucella periplasm to ensure cell envelope integrity and to enable 86 cell survival in the mammalian host niche. 88 Results 89B. abortus eipB is required for maintenance of mouse spleen colonization 90As part of a screen to evaluate the role of conserved Alphaproteobacterial genes of unknown 91 function in B. abortus infection biology, we infected THP-1 macrophage-like cells with wild-type B. 92abortus, an eipB deletion strain (∆eipB), and a genetically complemented ∆eipB strain. Infected 93 macrophages were lysed and colony forming units (CFU) were enumerated on tryptic soy agar 94 plates (TSA) at 1, 24 and...