Browsing by Author "Lu, Tao"

Now showing 1 - 10 of 53
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    A complex signature network that controls the upregulation of PRMT5 in colorectal cancer
    (Elsevier, 2022-03) Wei, Han; Hartley, Antja-Voy; Motolani, Aishat; Jiang, Guanglong; Safa, Ahmad; Prabhu, Lakshmi; Liu, Yunlong; Lu, Tao; Pharmacology and Toxicology, School of Medicine
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    Adapting AlphaLISA high throughput screen to discover a novel small-molecule inhibitor targeting protein arginine methyltransferase 5 in pancreatic and colorectal cancers
    (Impact Journals, 2017-05-23) Prabhu, Lakshmi; Wei, Han; Chen, Lan; Demir, Özlem; Sandusky, George; Sun, Emily; Wang, John; Mo, Jessica; Zeng, Lifan; Fishel, Melissa; Safa, Ahmad; Amaro, Rommie; Korc, Murray; Zhang, Zhong-Yin; Lu, Tao; Pharmacology and Toxicology, School of Medicine
    Pancreatic ductal adenocarcinoma (PDAC) and colorectal cancer (CRC) are notoriously challenging for treatment. Hyperactive nuclear factor κB (NF-κB) is a common culprit in both cancers. Previously, we discovered that protein arginine methyltransferase 5 (PRMT5) methylated and activated NF-κB. Here, we show that PRMT5 is highly expressed in PDAC and CRC. Overexpression of PRMT5 promoted cancer progression, while shRNA knockdown showed an opposite effect. Using an innovative AlphaLISA high throughput screen, we discovered a lead compound, PR5-LL-CM01, which exhibited robust tumor inhibition effects in both cancers. An in silico structure prediction suggested that PR5-LL-CM01 inhibits PRMT5 by binding with its active pocket. Importantly, PR5-LL-CM01 showed higher anti-tumor efficacy than the commercial PRMT5 inhibitor, EPZ015666, in both PDAC and CRC. This study clearly highlights the significant potential of PRMT5 as a therapeutic target in PDAC and CRC, and establishes PR5-LL-CM01 as a promising basis for new drug development in the future.
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    Aging: Cancer – an unlikely couple
    (Impact Journals, 2017-09-20) Hartley, Antja-Voy; Martin, Matthew; Lu, Tao; Pharmacology and Toxicology, School of Medicine
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    Analysis of the Combined Effect of rs699 and rs5051 on Angiotensinogen Expression and Hypertension
    (bioRxiv, 2023-04-08) Powell, Nicholas R.; Shugg, Tyler; Leighty, Jacob; Martin, Matthew; Kreutz, Rolf P.; Eadon, Michael T.; Lai, Dongbing; Lu, Tao; Skaar, Todd C.; Medicine, School of Medicine
    Hypertension (HTN) involves genetic variability in the renin-angiotensin system and characterizing this variability will help advance precision antihypertensive treatments. We previously reported that angiotensinogen (AGT) mRNA is endogenously bound by mir-122-5p and that rs699 A>G significantly decreases reporter mRNA in the functional mirSNP assay PASSPORT-seq. The AGT promoter variant rs5051 C>T is in linkage disequilibrium (LD) with rs699 A>G and increases AGT transcription. We hypothesized that the increased AGT by rs5051 C>T counterbalances AGT decrease by rs699 A>G, and when these variants occur independently, would translate to HTN-related phenotypes. The independent effect of each of these variants is understudied due to their LD, therefore, we used in silico, in vitro, in vivo, and retrospective clinical and biobank analyses to assess HTN and AGT expression phenotypes where rs699 A>G occurs independently from rs5051 C>T. In silico, rs699 A>G is predicted to increase mir-122-5p binding strength by 3%. Mir-eCLIP assay results show that rs699 is 40-45 nucleotides from the strongest microRNA binding site in the AGT mRNA. Unexpectedly, rs699 A>G increases AGT mRNA in a plasmid cDNA HepG2 expression model. GTEx and UK Biobank analyses demonstrate that liver AGT expression and HTN phenotypes were not different when rs699 A>G occurs independently from rs5051 C>T, allowing us to reject the original hypothesis. However, both GTEx and our in vitro experiments suggest rs699 A>G confers cell-type specific effects on AGT mRNA abundance. We found that rs5051 C>T and rs699 A>G significantly associate with systolic blood pressure in Black participants in the UK Biobank, demonstrating a 4-fold larger effect than in White participants. Further studies are warranted to determine if the altered antihypertensive response in Black individuals might be due to rs5051 C>T or rs699 A>G. Studies like this will help clinicians move beyond the use of race as a surrogate for genotype.
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    AP2IX-4, a cell cycle regulated nuclear factor, modulates gene expression during bradyzoite development in toxoplasma gondii
    (2017-01-10) Huang, Sherri Y.; Arrizabalaga, Gustavo; Sullivan, William J., Jr.; Lu, Tao; Takagi, Yuichiro; Zhang, Jian-Ting
    Toxoplasma gondii is a ubiquitous, protozoan parasite contributing significantly to global human and animal health. In the host, this obligate intracellular parasite converts into a latent tissue cyst form known as the bradyzoite, which is impervious to the immune response. The tissue cysts facilitate wide-spread transmission through the food chain and give rise to chronic toxoplasmosis in immune compromised patients. In addition, they may reactivate into replicating tachyzoites which cause tissue damage and disseminated disease. Current available drugs do not appear to have appreciable activity against latent bradyzoites. Therefore, a better understanding of the molecular mechanisms that drive interconversion between tachyzoite and bradyzoite forms is required to manage transmission and pathogenesis of Toxoplasma. Conversion to the bradyzoite is accompanied by an altered transcriptome, but the molecular players directing this process are largely uncharacterized. Studies of stage-specific promoters revealed that conventional cis-acting mechanisms operate to regulate developmental gene expression during tissue cyst formation. The major class of transcription factor likely to work through these cis-regulatory elements appears to be related to the Apetala-2 (AP2) family in plants. The Toxoplasma genome contains nearly 70 proteins harboring at least one predicted AP2 domain, but to date only three of these T. gondii AP2 proteins have been linked to bradyzoite development. We show that the putative T. gondii transcription factor, AP2IX-4, is localized to the parasite nucleus and exclusively expressed in tachyzoites and bradyzoites undergoing division. Knockout of AP2IX-4 had negligible effect on tachyzoite replication, but resulted in a reduced frequency of bradyzoite cysts in response to alkaline stress induction – a defect that is reversible by complementation. Microarray analyses revealed an enhanced activation of bradyzoite-associated genes in the AP2IX-4 knockout during alkaline conditions. In mice, the loss of AP2IX-4 resulted in a modest virulence defect and reduced brain cyst burden. Complementation of the AP2IX-4 knockout restored cyst counts to wild-type levels. These findings illustrate the complex role of AP2IX-4 in bradyzoite development and that certain transcriptional mechanisms responsible for tissue cyst development operate across parasite division.
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    Biological Functions of Intracellular Hepatitis B e Antigen
    (2019-09) Mitra, Bidisha; Guo, Haitao; Androphy, Elliot J.; Kaplan, Mark; Yu, Andy; Lu, Tao
    The function(s) of the intracellular form of HBeAg, previously reported as the preCore protein intermediate (p22) without the N-terminal signal peptide, remains elusive. Here, we propose to elucidate the translocation of p22 during its formation from endoplasmic reticulum (ER) to cytosol, how it differs from core in its inability to form a capsid and the biological functions of cytoplasmic and nuclear p22. Firstly, we have identified that a portion of p22, after the cleavage of its signal peptide in ER, is released back into the cytosol through an ERAD-independent mechanism, as neither wildtype nor dominant-negative p97 affected the ER-to-cytosol translocation of p22 or ER-Golgi secretion of HBeAg. Secondly, despite sharing the same sequence with core protein except for the extended 10 amino acid precore region at the N-terminus, we observed that p22 wildtype and C-7Q mutant are unable to form a capsid. Thirdly, we report that p22 but not the secreted HBeAg significantly reduced interferon stimulated response element (ISRE) activity and expression of interferon stimulated genes (ISGs) upon interferon-alpha (IFN- α) stimulation. Furthermore, in line with this, RNA-seq analysis of ISG induction profile from IFN-α treated patients showed that HBeAg(+) patients exhibited reduced and weak antiviral ISG upregulations compared to HBeAg(-) patients. Further, mechanistic study indicated that while p22 did not alter the total STAT1 or p-STAT1 levels in IFN-α treated cells, it blocked the nuclear translocation of p-STAT1 by interacting with karyopherin α1, indicating that the cytoplasmic p22 may impede JAK-STAT signaling to help the virus evade host innate immune response and cause resistance to IFN therapy in patients. Additionally, nuclear p22 and nuclear core were found to interact with the promoter regions (ISRE – containing) of ISGs, suggesting a new mechanism of inhibition of ISG expression upon stimulation. Finally, we found that the nuclear p22 can bind to cccDNA minichromosome and affects cccDNA maintenance and/or transcription. Thus, our results indicate that there is a novel ER sorting mechanism for the distribution of the intracellular and secretory HBeAg, and the intracellular HBeAg may contribute to HBV persistence by interfering with IFN-α elicited JAK-STAT signaling and regulating cccDNA metabolism.
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    CDK8/19 Mediator kinases potentiate induction of transcription by NFκB
    (National Academy of Sciences, 2017-09-19) Chen, Mengqian; Liang, Jiaxin; Ji, Hao; Yang, Zhengguan; Altilia, Serena; Hu, Bing; Schronce, Adam; McDermott, Martina S. J.; Schools, Gary P.; Lim, Chang-uk; Oliver, David; Shtutman, Michael S.; Lu, Tao; Stark, George R.; Porter, Donald C.; Broude, Eugenia V.; Roninson, Igor B.; Pharmacology and Toxicology, School of Medicine
    Nuclear factor-κB (NFκB) transcription factors have been implicated in several major diseases, including inflammatory disorders, viral infections, and cancer. NFκB-inhibiting drugs typically have side effects, possibly due to sustained NFκB suppression. The ability to affect induced, but not basal, NFκB activity could provide therapeutic benefit without associated toxicity. We report that the transcription-regulating kinases CDK8/19 potentiate NFκB activity, including the expression of tumor-promoting proinflammatory cytokines, by enabling the completion of NFκB-initiated transcription. CDK8/19 inhibitors suppress the induction of gene expression by NFκB or other transcription factors, but generally do not affect basal expression of the same genes. The role of CDK8/19 in newly induced transcription identifies these kinases as mediators of transcriptional reprogramming, a key aspect of development, differentiation, and pathological processes., The nuclear factor-κB (NFκB) family of transcription factors has been implicated in inflammatory disorders, viral infections, and cancer. Most of the drugs that inhibit NFκB show significant side effects, possibly due to sustained NFκB suppression. Drugs affecting induced, but not basal, NFκB activity may have the potential to provide therapeutic benefit without associated toxicity. NFκB activation by stress-inducible cell cycle inhibitor p21 was shown to be mediated by a p21-stimulated transcription-regulating kinase CDK8. CDK8 and its paralog CDK19, associated with the transcriptional Mediator complex, act as coregulators of several transcription factors implicated in cancer; CDK8/19 inhibitors are entering clinical development. Here we show that CDK8/19 inhibition by different small-molecule kinase inhibitors or shRNAs suppresses the elongation of NFκB-induced transcription when such transcription is activated by p21-independent canonical inducers, such as TNFα. On NFκB activation, CDK8/19 are corecruited with NFκB to the promoters of the responsive genes. Inhibition of CDK8/19 kinase activity suppresses the RNA polymerase II C-terminal domain phosphorylation required for transcriptional elongation, in a gene-specific manner. Genes coregulated by CDK8/19 and NFκB include IL8, CXCL1, and CXCL2, which encode tumor-promoting proinflammatory cytokines. Although it suppressed newly induced NFκB-driven transcription, CDK8/19 inhibition in most cases had no effect on the basal expression of NFκB-regulated genes or promoters; the same selective regulation of newly induced transcription was observed with other transcription signals potentiated by CDK8/19. This selective role of CDK8/19 identifies these kinases as mediators of transcriptional reprogramming, a key aspect of development and differentiation as well as pathological processes.
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    Critical role of NF-κB in pancreatic cancer
    (Impact Journals, 2014-11-30) Prabhu, Lakshmi; Mundade, Rasika; Korc, Murray; Loehrer, Patrick J.; Lu, Tao; Department of Pharmacology and Toxicology, IU School of Medicine
    Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers, and in spite of intense efforts there are limited therapeutic options for patients with PDAC. PDACs harbor a high frequency of Kras mutations and other driver mutations that lead to altered signaling pathways and contribute to therapeutic resistance. Importantly, constitutive activation of nuclear factor κB (NF-κB) is frequently observed in PDAC. An increasing body of evidence suggests that both classical and non-classical NF-κB pathways play a crucial role in PDAC development and progression. In this review, we update the most recent advances regarding different aspects of NF-κB involvement in PDAC development and progression, emphasizing its potential as a therapeutic target and the need to discover pathway-specific cytosolic NF-κB regulators which could be used to design novel therapeutic strategies for PDAC.
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    Critical Role of Novel O-GlcNAcylation of S550 and S551 on the p65 Subunit of NF-κB in Pancreatic Cancer
    (MDPI, 2023-09-27) Motolani, Aishat; Martin, Matthew; Wang, Benlian; Jiang, Guanglong; Alipourgivi, Faranak; Huang, Xiumei; Safa, Ahmad; Liu, Yunlong; Lu, Tao; Pharmacology and Toxicology, School of Medicine
    Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, with a mere 5-year survival of ~10%. This highlights the urgent need for innovative treatment options for PDAC patients. The nuclear factor κB (NF-κB) is a crucial transcription factor that is constitutively activated in PDAC. It mediates the transcription of oncogenic and inflammatory genes that facilitate multiple PDAC phenotypes. Thus, a better understanding of the mechanistic underpinnings of NF-κB activation holds great promise for PDAC diagnosis and effective therapeutics. Here, we report a novel finding that the p65 subunit of NF-κB is O-GlcNAcylated at serine 550 and 551 upon NF-κB activation. Importantly, the overexpression of either serine-to-alanine (S-A) single mutant (S550A or S551A) or double mutant (S550A/S551A) of p65 in PDAC cells impaired NF-κB nuclear translocation, p65 phosphorylation, and transcriptional activity, independent of IκBα degradation. Moreover, the p65 mutants downregulate a category of NF-κB-target genes, which play a role in perpetuating major cancer hallmarks. We further show that overexpression of the p65 mutants inhibited cellular proliferation, migration, and anchorage-independent growth of PDAC cells compared to WT-p65. Collectively, we discovered novel serine sites of p65 O-GlcNAcylation that drive NF-κB activation and PDAC phenotypes, thus opening new avenues by inhibiting the NF-κB O-GlcNAcylation enzyme, O-GlcNAc transferase (OGT), for PDAC treatment in the future.
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    Critical role of phosphorylation of serine 165 of YBX1 on the activation of NF- B in colon cancer
    (Office of the Vice Chancellor for Research, 2015-04-17) Prabhu, Lakshmi; Mundade, Rasika; Wang, Benlian; Wei, Han; Hartley, Antja-Voy; McElyea, Kyle; Temm, Constance J.; Sandusky, George; Liu, Yunlong; Lu, Tao
    Y-box binding protein 1 (YBX1) is a multifunctional protein known to facilitate many of the hallmarks of cancer. Elevated levels of YBX1 protein are highly correlated with cancer progression, making it an excellent marker in cancer. The connection between YBX1 and the important nuclear factor B (NF-B), has never been previously reported. Here, we show that overexpression of wild type YBX1 (wtYBX1) activates NF-B, suggesting that YBX1 is a potential NF-B activator. Furthermore, using mass spectrometry analysis, we identified novel phosphorylation of serine 165 (S165) on YBX1. Overexpression of the S165A-YBX1 mutant in either 293 cells or colon cancer HT29 cells showed dramatically reduced NF-B activating ability as compared to that of wtYBX1, confirming that S165 phosphorylation is critical for the activation of NF-B by YBX1. We further show that expression of the S165A-YBX1 mutant dramatically decreased the expression of NF-B-inducible genes, reduced cell growth, and compromised tumorigenic ability as compared to wtYBX1. Taken together, we provide the first evidence that YBX1 functions as a tumor promoter via NF-B activation, and phosphorylation of S165 of YBX1 is critical for this function. Therefore, our important discovery may lead to blocking S165 phosphorylation as a potential therapeutic strategy to treat colon cancer.