The regulation of RNA Polymerase II mediated transcription by Caspase-8 in ovarian cancer.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e18082-e18082
Author(s):  
Sven Becker ◽  
Ranadip Mandal ◽  
Monika Raab ◽  
Mourad Sanhaji ◽  
Klaus Strebhardt
Keyword(s):  
Ovarian Cancer ◽  
Rna Polymerase Ii ◽  
Ex Vivo ◽  
New Drugs ◽  
Caspase 8 ◽  
Low Grade ◽  
Apoptotic Pathway ◽  
Rna Pol Ii ◽  
Pol Ii

e18082 Background: According to the WHO, in 2018, the number of new cases and mortality worldwide due to ovarian cancer, were 295,414 and 184,799, respectively, making it one of the most lethal gynaecological cancers in the world. The standard therapy of ovarian cancers is still comprehensive cytoreductive surgery followed by a combination of platinum-taxane based primary chemotherapy. Second line therapies include Carboplatin or Cisplatin in combination with Paclitaxel, PLD or Gemcitabine, with or without Bevacizumab. Unfortunately, late stage ovarian cancer cases are still incurable, however, several new drugs are under development or are undergoing clinical trials. At present, these new approaches can only stabilize the disease or delay its recurrence. Caspase-8, the predominant initiator of the extrinsic apoptotic pathway, also plays critical roles in a number of other non-apoptotic functions. It is also frequently down-regulated in ovarian cancer and we wanted to understand how this down-regulation could support the development of ovarian cancer. Methods: The analysis of the association between CASP8 expression and patient prognosis in ovarian cancer patients found that low CASP8 expression was significantly correlated with poor OS, with a median OS of 37.43 (low expression) and 49.97 (high expression) months, and higher clinical stages. CRISPR/Cas9 mediated CASP8 KO in multiple high- and low-grade ovarian cancer cell lines resulted in significant increases in their invasiveness. Results: Caspase-8 interactome analysis revealed that it can regulate the RNA Pol II mediated transcription, which was corroborated through multiple in vitro and ex vivo experiments. Global Transcriptomics and Proteomics analysis of the KO cells revealed significant upregulation of genes involved in metastasis, which was again verified in in vitro and ex vivo experiments. Additionally, the KO cells were significantly resistant towards standard chemotherapeutics like Carboplatin, a transcription inhibitor, either alone or in combination with Paclitaxel. Conclusions: Presently, we are working on orthotopic ovarian cancer mouse models to validate - the potential of Caspase-8 to regulate metastasis; and the targeting of RNA Pol II to sensitize them to standard chemotherapeutics. We are also developing organoid banks from patient derived ovarian cancer tissues, with low Caspase-8 expression, to validate the upregulation of genes identified in our ‘omics’ data and the potential of targeting them, along with RNA Pol II, to sensitize them to standard chemotherapeutics.

scholarly journals Newly developed dual topoisomerase inhibitor P8-D6 is highly active in ovarian cancer

2021 ◽  
Vol 13 ◽  
pp. 175883592110598
Author(s):  
Inken Flörkemeier ◽  
Tamara N. Steinhauer ◽  
Nina Hedemann ◽  
Magnus Ölander ◽  
Per Artursson ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Topoisomerase I ◽  
Ex Vivo ◽  
Chemotherapy Resistance ◽  
Membrane Integrity ◽  
Three Dimensional ◽  
New Drugs ◽  
Highly Active ◽  
Gynaecologic Neoplasms

Background: Ovarian cancer (OvCa) constitutes a rare and highly aggressive malignancy and is one of the most lethal of all gynaecologic neoplasms. Due to chemotherapy resistance and treatment limitations because of side effects, OvCa is still not sufficiently treatable. Hence, new drugs for OvCa therapy such as P8-D6 with promising antitumour properties have a high clinical need. The benzo[ c]phenanthridine P8-D6 is an effective inductor of apoptosis by acting as a dual topoisomerase I/II inhibitor. Methods: In the present study, the effectiveness of P8-D6 on OvCa was investigated in vitro. In various OvCa cell lines and ex vivo primary cells, the apoptosis induction compared with standard therapeutic agents was determined in two-dimensional monolayers. Expanded by three-dimensional and co-culture, the P8-D6 treated cells were examined for changes in cytotoxicity, apoptosis rate and membrane integrity via scanning electron microscopy (SEM). Likewise, the effects of P8-D6 on non-cancer human ovarian surface epithelial cells and primary human hepatocytes were determined. Results: This study shows a significant P8-D6-induced increase in apoptosis and cytotoxicity in OvCa cells which surpasses the efficacy of well-established drugs like cisplatin or the topoisomerase inhibitors etoposide and topotecan. Non-cancer cells were affected only slightly by P8-D6. Moreover, no hepatotoxic effect in in vitro studies was detected. Conclusion: P8-D6 is a strong and rapid inductor of apoptosis and might be a novel treatment option for OvCa therapy.

scholarly journals Mechanism of RNA polymerase II stalling by DNA alkylation

2017 ◽  
Vol 114 (46) ◽  
pp. 12172-12177 ◽  
Author(s):  
Stefano Malvezzi ◽  
Lucas Farnung ◽  
Claudia M. N. Aloisi ◽  
Todor Angelov ◽  
Patrick Cramer ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Anticancer Agents ◽  
Excision Repair ◽  
Minor Groove ◽  
Dna Alkylation ◽  
Drug Induced ◽  
Rna Pol Ii ◽  
Pol Ii

Several anticancer agents that form DNA adducts in the minor groove interfere with DNA replication and transcription to induce apoptosis. Therapeutic resistance can occur, however, when cells are proficient in the removal of drug-induced damage. Acylfulvenes are a class of experimental anticancer agents with a unique repair profile suggesting their capacity to stall RNA polymerase (Pol) II and trigger transcription-coupled nucleotide excision repair. Here we show how different forms of DNA alkylation impair transcription by RNA Pol II in cells and with the isolated enzyme and unravel a mode of RNA Pol II stalling that is due to alkylation of DNA in the minor groove. We incorporated a model for acylfulvene adducts, the stable 3-deaza-3-methoxynaphtylethyl-adenosine analog (3d-Napht-A), and smaller 3-deaza-adenosine analogs, into DNA oligonucleotides to assess RNA Pol II transcription elongation in vitro. RNA Pol II was strongly blocked by a 3d-Napht-A analog but bypassed smaller analogs. Crystal structure analysis revealed that a DNA base containing 3d-Napht-A can occupy the +1 templating position and impair closing of the trigger loop in the Pol II active center and polymerase translocation into the next template position. These results show how RNA Pol II copes with minor-groove DNA alkylation and establishes a mechanism for drug resistance.

scholarly journals Newly Developed Dual Topoisomerase Inhibitor P8-D6 is Highly Active in Ovarian Cancer

2021 ◽  
Author(s):  
Inken Flörkemeier ◽  
Tamara N. Steinhauer ◽  
Nina Hedemann ◽  
Magnus Ölander ◽  
Per Artursson ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Topoisomerase I ◽  
Ex Vivo ◽  
Chemotherapy Resistance ◽  
Membrane Integrity ◽  
New Drugs ◽  
Highly Active ◽  
Ovarian Surface Epithelial ◽  
Gynaecologic Neoplasms

Abstract Background: Ovarian cancer (OvCa) constitutes a rare and highly aggressive malignancy and is one of the most lethal of all gynaecologic neoplasms. Due to chemotherapy resistance and treatment limitations because of side effects, OvCa is still not sufficiently treatable. Hence, new drugs for OvCa therapy such as P8-D6 with promising antitumour properties have a high clinical need. The benzo[c]phenanthridine P8-D6 is an effective inductor of apoptosis by acting as a dual topoisomerase I/II inhibitor. Methods: In the present study, the effectiveness of P8-D6 on OvCa was investigated in vitro. In various OvCa cell lines and ex vivo primary cells, the apoptosis induction compared to standard therapeutic agents was determined in 2D monolayers. Expanded by 3D and co-culture, the P8-D6 treated cells were examined for changes in cytotoxicity, apoptosis rate and membrane integrity via scanning electron microscopy (SEM). Likewise, the effects of P8-D6 on non-cancer human ovarian surface epithelial cells and primary human hepatocytes were determined. Results: This study shows a significant P8-D6-induced increase in apoptosis and cytotoxicity in OvCa cells which surpasses the efficacy of standard therapeutic drugs. Non-cancer cells were affected only slightly by P8-D6. Moreover, no hepatotoxic effect in in vitro studies was detected.Conclusions: P8-D6 is a strong and rapid inductor of apoptosis and might be a novel treatment option for OvCa therapy.

scholarly journals The Werner Syndrome Protein Is Involved in RNA Polymerase II Transcription

1999 ◽  
Vol 10 (8) ◽  
pp. 2655-2668 ◽  
Author(s):  
Adayabalam S. Balajee ◽  
Amrita Machwe ◽  
Alfred May ◽  
Matthew D. Gray ◽  
Junko Oshima ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Cell Lines ◽  
Werner Syndrome ◽  
Molecular Defect ◽  
Rna Pol Ii ◽  
Vitro Assay ◽  
Pol Ii ◽  
Cell Extracts

Werner syndrome (WS) is a human progeroid syndrome characterized by the early onset of a large number of clinical features associated with the normal aging process. The complex molecular and cellular phenotypes of WS involve characteristic features of genomic instability and accelerated replicative senescence. The gene involved (WRN) was recently cloned, and its gene product (WRNp) was biochemically characterized as a helicase. Helicases play important roles in a variety of DNA transactions, including DNA replication, transcription, repair, and recombination. We have assessed the role of the WRN gene in transcription by analyzing the efficiency of basal transcription in WS lymphoblastoid cell lines that carry homozygous WRN mutations. Transcription was measured in permeabilized cells by [3H]UTP incorporation and in vitro by using a plasmid template containing the RNA polymerase II (RNA pol II)–dependent adenovirus major late promoter. With both of these approaches, we find that the transcription efficiency in different WS cell lines is reduced to 40–60% of the transcription in cells from normal individuals. This defect can be complemented by the addition of normal cell extracts to the chromatin of WS cells. Addition of purified wild-type WRNp but not mutated WRNp to the in vitro transcription assay markedly stimulates RNA pol II–dependent transcription carried out by nuclear extracts. A nonhelicase domain (a direct repeat of 27 amino acids) also appears to have a role in transcription enhancement, as revealed by a yeast hybrid–protein reporter assay. This is further supported by the lack of stimulation of transcription when mutant WRNp lacking this domain was added to the in vitro assay. We have thus used several approaches to show a role for WRNp in RNA pol II transcription, possibly as a transcriptional activator. A deficit in either global or regional transcription in WS cells may be a primary molecular defect responsible for the WS clinical phenotype.

scholarly journals Flavopiridol Mitigates the Progression of Monocrotaline-Induced Pulmonary Hypertension in Rats by Targeting Cyclin-dependent Kinase 9

2021 ◽  
Author(s):  
Qi Jia ◽  
Zhiqiang Hu ◽  
Nannan Song ◽  
Weike Mao
Keyword(s):  
Pulmonary Hypertension ◽  
Pulmonary Artery ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Therapeutic Potential ◽  
Cyclin Dependent Kinase ◽  
Rna Pol Ii ◽  
Pol Ii ◽  
Pulmonary Arterial

Abstract Purpose: To investigate the role of cyclin-dependent kinase 9 (CDK9) and the therapeutic potential of CDK9 inhibitor (flavopiridol) in monocrotaline (MCT)-induced pulmonary hypertension.Methods: In vivo experiments, pulmonary hypertension rats were established by a single intraperitoneal injection of MCT (60 mg/kg) for 2 weeks and treated with flavopiridol (5 mg/kg, i.p., twice a week) or vehicle for 2 weeks. In vitro experiments, human pulmonary artery smooth muscle cells (HPASMCs) were treated with flavopiridol (0.025-1μM) or vehicle under hypoxic condition. Hemodynamic recording, right ventricle and lung histology, isolation of pulmonary arterial tissues were performed. The expressions of CDK9, RNA polymerase II, c-Myc, Mcl-1 and survivin were determined by qRT-PCR and western blotting, proliferation and apoptosis of PASMCs were also assayed.Results: CDK9 was upregulated in both rat pulmonary arterial tissues and HPASMCs. Upregulation of CDK9 increased the phosphorylation of the C-terminal domain (CTD) of RNA polymerase II (RNA pol II) on serine-2, promoting the expression of prosurvival and antiapoptotic proteins (c-Myc, Mcl-1 and survivin). Furthermore, treatment with flavopiridol (5 mg/kg) significantly alleviated pulmonary artery remodeling and partially reversed the progression of monocrotaline-induced pulmonary hypertension. Consistently, flavopiridol (0.5 μM) treatment decreased the proliferation and induced the apoptosis of cultured HPASMCs under hypoxic conditions. As a result of CDK9 inhibition and subsequent inhibition of RNA pol II CTD phosphorylation at serine 2, flavopiridol decreased c-Myc, Mcl-1 and survivin expressions in isolated pulmonary small arteries, leading to cell growth inhibition and apoptosis. Conclusion: Flavopiridol mitigates the progression of monocrotaline-induced pulmonary hypertension in rats by targeting cyclin-dependent kinase 9.

scholarly journals Transcription recycling assays identify PAF1 as a driver for RNA Pol II recycling

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhong Chen ◽  
William Hankey ◽  
Yue Zhao ◽  
Jeff Groth ◽  
Furong Huang ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Quantitative Measurement ◽  
Rna Pol Ii ◽  
Pol Ii ◽  
Disease States ◽  
Paf1 Complex ◽  
Transcriptional Output ◽  
Cellular Transcription ◽  
Gene Expression Levels

AbstractRNA Polymerase II (Pol II) transcriptional recycling is a mechanism for which the required factors and contributions to overall gene expression levels are poorly understood. We describe an in vitro methodology facilitating unbiased identification of putative RNA Pol II transcriptional recycling factors and quantitative measurement of transcriptional output from recycled transcriptional components. Proof-of-principle experiments identified PAF1 complex components among recycling factors and detected defective transcriptional output from Pol II recycling following PAF1 depletion. Dynamic ChIP-seq confirmed PAF1 silencing triggered defective Pol II recycling in human cells. Prostate tumors exhibited enhanced transcriptional recycling, which was attenuated by antibody-based PAF1 depletion. These findings identify Pol II recycling as a potential target in cancer and demonstrate the applicability of in vitro and cellular transcription assays to characterize Pol II recycling in other disease states.

scholarly journals Cockayne syndrome B protein acts as an ATP-dependent processivity factor that helps RNA polymerase II overcome nucleosome barriers

2020 ◽  
Vol 117 (41) ◽  
pp. 25486-25493 ◽  
Author(s):  
Jun Xu ◽  
Wei Wang ◽  
Liang Xu ◽  
Jia-Yu Chen ◽  
Jenny Chong ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Neurological Diseases ◽  
Transcription Elongation ◽  
Cockayne Syndrome ◽  
Stable Complex ◽  
Loss Of Function ◽  
Pol Ii ◽  
Chromatin Remodelers ◽  
Processivity Factor

While loss-of-function mutations in Cockayne syndrome group B protein (CSB) cause neurological diseases, this unique member of the SWI2/SNF2 family of chromatin remodelers has been broadly implicated in transcription elongation and transcription-coupled DNA damage repair, yet its mechanism remains largely elusive. Here, we use a reconstituted in vitro transcription system with purified polymerase II (Pol II) and Rad26, a yeast ortholog of CSB, to study the role of CSB in transcription elongation through nucleosome barriers. We show that CSB forms a stable complex with Pol II and acts as an ATP-dependent processivity factor that helps Pol II across a nucleosome barrier. This noncanonical mechanism is distinct from the canonical modes of chromatin remodelers that directly engage and remodel nucleosomes or transcription elongation factors that facilitate Pol II nucleosome bypass without hydrolyzing ATP. We propose a model where CSB facilitates gene expression by helping Pol II bypass chromatin obstacles while maintaining their structures.

scholarly journals Evaluating Targeted Therapies in Ovarian Cancer Metabolism: Novel Role for PCSK9 and Second Generation mTOR Inhibitors

Cancers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 3727
Author(s):  
Dafne Jacome Sanz ◽  
Juuli Raivola ◽  
Hanna Karvonen ◽  
Mariliina Arjama ◽  
Harlan Barker ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Lipid Metabolism ◽  
Cell Survival ◽  
Drug Testing ◽  
Cancer Metabolism ◽  
Ex Vivo ◽  
Specific Inhibitor ◽  
Low Grade ◽  
Serous Ovarian Cancer

Background: Dysregulated lipid metabolism is emerging as a hallmark in several malignancies, including ovarian cancer (OC). Specifically, metastatic OC is highly dependent on lipid-rich omentum. We aimed to investigate the therapeutic value of targeting lipid metabolism in OC. For this purpose, we studied the role of PCSK9, a cholesterol-regulating enzyme, in OC cell survival and its downstream signaling. We also investigated the cytotoxic efficacy of a small library of metabolic (n = 11) and mTOR (n = 10) inhibitors using OC cell lines (n = 8) and ex vivo patient-derived cell cultures (PDCs, n = 5) to identify clinically suitable drug vulnerabilities. Targeting PCSK9 expression with siRNA or PCSK9 specific inhibitor (PF-06446846) impaired OC cell survival. In addition, overexpression of PCSK9 induced robust AKT phosphorylation along with increased expression of ERK1/2 and MEK1/2, suggesting a pro-survival role of PCSK9 in OC cells. Moreover, our drug testing revealed marked differences in cytotoxic responses to drugs targeting metabolic pathways of high-grade serous ovarian cancer (HGSOC) and low-grade serous ovarian cancer (LGSOC) PDCs. Our results show that targeting PCSK9 expression could impair OC cell survival, which warrants further investigation to address the dependency of this cancer on lipogenesis and omental metastasis. Moreover, the differences in metabolic gene expression and drug responses of OC PDCs indicate the existence of a metabolic heterogeneity within OC subtypes, which should be further explored for therapeutic improvements.

scholarly journals Direct Interaction between the Subunit RAP30 of Transcription Factor IIF (TFIIF) and RNA Polymerase Subunit 5, Which Contributes to the Association between TFIIF and RNA Polymerase II

2001 ◽  
Vol 276 (15) ◽  
pp. 12266-12273 ◽  
Author(s):  
Wenxiang Wei ◽  
Dorjbal Dorjsuren ◽  
Yong Lin ◽  
Weiping Qin ◽  
Takahiro Nomura ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Middle Part ◽  
Wild Type ◽  
Binding Region ◽  
Pol Ii ◽  
Transcription Factor Iif ◽  
B Virus

The general transcription factor IIF (TFIIF) assembled in the initiation complex, and RAP30 of TFIIF, have been shown to associate with RNA polymerase II (pol II), although it remains unclear which pol II subunit is responsible for the interaction. We examined whether TFIIF interacts with RNA polymerase II subunit 5 (RPB5), the exposed domain of which binds transcriptional regulatory factors such as hepatitis B virus X protein and a novel regulatory protein, RPB5-mediating protein. The results demonstrated that RPB5 directly binds RAP30in vitrousing purified recombinant proteins andin vivoin COS1 cells transiently expressing recombinant RAP30 and RPB5. The RAP30-binding region was mapped to the central region (amino acids (aa) 47–120) of RPB5, which partly overlaps the hepatitis B virus X protein-binding region. Although the middle part (aa 101–170) and the N-terminus (aa 1–100) of RAP30 independently bound RPB5, the latter was not involved in the RPB5 binding when RAP30 was present in TFIIF complex. Scanning of the middle part of RAP30 by clustered alanine substitutions and then point alanine substitutions pinpointed two residues critical for the RPB5 binding inin vitroandin vivoassays. Wild type but not mutants Y124A and Q131A of RAP30 coexpressed with FLAG-RAP74 efficiently recovered endogenous RPB5 to the FLAG-RAP74-bound anti-FLAG M2 resin. The recovered endogenous RPB5 is assembled in pol II as demonstrated immunologically. Interestingly, coexpression of the central region of RPB5 and wild type RAP30 inhibited recovery of endogenous pol II to the FLAG-RAP74-bound M2 resin, strongly suggesting that the RAP30-binding region of RPB5 inhibited the association of TFIIF and pol II. The exposed domain of RPB5 interacts with RAP30 of TFIIF and is important for the association between pol II and TFIIF.

scholarly journals Regulation of P-TEFb Elongation Complex Activity by CDK9 Acetylation

2007 ◽  
Vol 27 (13) ◽  
pp. 4641-4651 ◽  
Author(s):  
Junjiang Fu ◽  
Ho-Geun Yoon ◽  
Jun Qin ◽  
Jiemin Wong
Keyword(s):  
Rna Polymerase Ii ◽  
Elongation Factor ◽  
Transcriptional Elongation ◽  
Elongation Complex ◽  
Complex Activity ◽  
Interacting Protein ◽  
Pol Ii ◽  
Carboxy Terminal

ABSTRACT P-TEFb, comprised of CDK9 and a cyclin T subunit, is a global transcriptional elongation factor important for most RNA polymerase II (pol II) transcription. P-TEFb facilitates transcription elongation in part by phosphorylating Ser2 of the heptapeptide repeat of the carboxy-terminal domain (CTD) of the largest subunit of pol II. Previous studies have shown that P-TEFb is subjected to negative regulation by forming an inactive complex with 7SK small RNA and HEXIM1. In an effort to investigate the molecular mechanism by which corepressor N-CoR mediates transcription repression, we identified HEXIM1 as an N-CoR-interacting protein. This finding led us to test whether the P-TEFb complex is regulated by acetylation. We demonstrate that CDK9 is an acetylated protein in cells and can be acetylated by p300 in vitro. Through both in vitro and in vivo assays, we identified lysine 44 of CDK9 as a major acetylation site. We present evidence that CDK9 is regulated by N-CoR and its associated HDAC3 and that acetylation of CDK9 affects its ability to phosphorylate the CTD of pol II. These results suggest that acetylation of CDK9 is an important posttranslational modification that is involved in regulating P-TEFb transcriptional elongation function.

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