scholarly journals Control of Expression of Key Cell Cycle Enzymes Drives Cell Line-Specific Functions of CDK7 in Human PDAC Cells

2022 ◽  
Vol 23 (2) ◽  
pp. 812
Author(s):  
Lina Kolloch ◽  
Teresa Kreinest ◽  
Michael Meisterernst ◽  
Andrea Oeckinghaus
Keyword(s):  
Cell Cycle ◽  
Cell Line ◽  
Specific Growth ◽  
Cell Cycle Control ◽  
Growth Control ◽  
Dual Function ◽  
Regulatory Pathways ◽  
Molecule Inhibitor ◽  
Extended Exposure ◽  
Higher Sensitivity

Inhibition of the dual function cell cycle and transcription kinase CDK7 is known to affect the viability of cancer cells, but the mechanisms underlying cell line-specific growth control remain poorly understood. Here, we employed a previously developed, highly specific small molecule inhibitor that non-covalently blocks ATP binding to CDK7 (LDC4297) to study the mechanisms underlying cell line-specific growth using a panel of genetically heterogeneous human pancreatic tumor lines as model system. Although LDC4297 diminished both transcription rates and CDK T-loop phosphorylation in a comparable manner, some PDAC lines displayed significantly higher sensitivity than others. We focused our analyses on two well-responsive lines (Mia-Paca2 and Panc89) that, however, showed significant differences in their viability upon extended exposure to limiting LDC4297 concentrations. Biochemical and RNAseq analysis revealed striking differences in gene expression and cell cycle control. Especially the downregulation of a group of cell cycle control genes, among them CDK1/2 and CDC25A/C, correlated well to the observed viability differences in Panc89 versus Mia-Paca2 cells. A parallel downregulation of regulatory pathways supported the hypothesis of a feedforward programmatic effect of CDK7 inhibitors, eventually causing hypersensitivity of PDAC lines.

Presence or absence of a G1 period in the cell cycle and growth control in a Chinese hamster cell line

1985 ◽  
Vol 158 (1) ◽  
pp. 276-279 ◽  
Author(s):  
D. Wynford-Thomas ◽  
G. Marin ◽  
A. LaMontagne ◽  
David M. Prescott
Keyword(s):  
Cell Cycle ◽  
Cell Line ◽  
Chinese Hamster ◽  
Growth Control ◽  
Chinese Hamster Cell ◽  
Chinese Hamster Cell Line

scholarly journals Characterization of a mutant rat kangaroo cell line with alterations in the cell cycle and DNA repair

2000 ◽  
Vol 23 (3) ◽  
pp. 689-694
Author(s):  
E.N. Miyaji ◽  
R.T. Johnson ◽  
C.S. Downes ◽  
E. Eveno ◽  
M. Mezzina ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Line ◽  
Excision Repair ◽  
Uv Light ◽  
Cell Metabolism ◽  
Cell Cycle Control ◽  
Pyrimidine Dimers ◽  
Dna Replication And Repair ◽  
Increased Sensitivity

Using a positive selection system for isolating DNA replication and repair related mutants, we isolated a clone from a rat kangaroo cell line (PtK2) that has increased sensitivity to UV light. Characterization of this clone indicated normal post-replication repair after UV irradiation, and normal removal rates of cyclobutane pyrimidine dimers and pyrimidine(6-4)pyrimidone photoproducts by excision repair. However, this cell line has decreased ability to make early incisions on damaged DNA, possibly indicating a defect in preferential repair of actively transcribed genes, and a slower cell proliferation rate, including a longer S-phase. This phenotype reinforces the present notion that control of key mechanisms in cell metabolism, such as cell cycle control, repair, transcription and cell death, can be linked.

Molecular Mechanisms of Cell Cycle Control in the Mouse Y1 Adrenal Cell Line

2004 ◽  
Vol 30 (4) ◽  
pp. 503-509 ◽  
Author(s):  
Érico T. Costa ◽  
Fábio L. Forti ◽  
Kátia M. Rocha ◽  
Miriam S. Moraes ◽  
Hugo A. Armelin
Keyword(s):  
Cell Cycle ◽  
Cell Line ◽  
Molecular Mechanisms ◽  
Cell Cycle Control ◽  
Adrenal Cell

scholarly journals Cell Cycle Dysregulation in Oral Cancer

2002 ◽  
Vol 13 (1) ◽  
pp. 51-61 ◽  
Author(s):  
R. Todd ◽  
P.W. Hinds ◽  
K. Munger ◽  
A.K. Rustgi ◽  
O.G. Opitz ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Cell Cycle Control ◽  
Metabolic Stress ◽  
Regulatory Proteins ◽  
Regulatory Pathways ◽  
Oral Cancers ◽  
Molecular Alterations ◽  
Oral Carcinogenesis ◽  
Retinoblastoma Tumor

The dysregulation of the molecular events governing cell cycle control is emerging as a central theme of oral carcinogenesis. Regulatory pathways responding to extracellular signaling or intracellular stress and DNA damage converge on the cell cycle apparatus. Abrogation of mitogenic and anti-mitogenic response regulatory proteins, such as the retinoblastoma tumor suppressor protein (pRB), cyclin D1, cyclin-dependent kinase (CDK) 6, and CDK inhibitors (p21WAF1/CIP1, p27KIP1, and p16INK4a), occur frequently in human oral cancers. Cellular responses to metabolic stress or genomic damage through p53 and related pathways that block cell cycle progression are also altered during oral carcinogenesis. In addition, new pathways and cell cycle regulatory proteins, such as p12DOC-1, are being discovered. The multistep process of oral carcinogenesis likely involves functional alteration of cell cycle regulatory members combined with escape from cellular senescence and apoptotic signaling pathways. Detailing the molecular alterations and understanding the functional consequences of the dysregulation of the cell cycle apparatus in the malignant oral keratinocyte will uncover novel diagnostic and therapeutic approaches.

scholarly journals Role of Human Cytomegalovirus Immediate-Early Proteins in Cell Growth Control

2000 ◽  
Vol 74 (17) ◽  
pp. 8028-8037 ◽  
Author(s):  
Jonathan P. Castillo ◽  
Andrew D. Yurochko ◽  
Timothy F. Kowalik
Keyword(s):  
Cell Cycle ◽  
Human Cytomegalovirus ◽  
P53 Protein ◽  
Cell Cycle Control ◽  
Growth Control ◽  
S Phase ◽  
Immediate Early ◽  
Cell Cycle Distribution ◽  
Cell Cycle Exit ◽  
Delay Cell

ABSTRACT Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus that has been implicated in several disorders, including an association between HCMV reactivation and the overproliferation of arterial smooth muscle cells observed in restenosis. Although HCMV can mediate a growth-arrest phenotype in infected cells, the virus can also promote an environment conducive to proliferation. Here, we present evidence that the HCMV immediate-early (IE) proteins, IE1-72 and IE2-86, may be responsible for inducing this proliferative environment by altering cell cycle control. We find that expression of either of these IE proteins can alter the cell cycle distribution of randomly cycling cells towards S and G2/M phases. Additionally, we find that expression of IE2-86, but not IE1-72, induces quiescent cells into S phase and delays cell cycle exit. In the absence of p53, IE1-72 expression can induce S phase and delay cell cycle exit. We also demonstrate that p53 protein levels increase in fibroblasts following the expression of IE1-72. The observed accumulation of p53 protein in IE1-72-expressing cells may account for the inability of IE1-72 to induce S phase and delay cell cycle exit. Our data suggest that expression of HCMV IE1-72 and IE2-86 is sufficient to alter the cell cycle to generate an environment conducive to proliferation.

scholarly journals Human Keratinocytes That Express hTERT and Also Bypass a p16INK4a-Enforced Mechanism That Limits Life Span Become Immortal yet Retain Normal Growth and Differentiation Characteristics

2000 ◽  
Vol 20 (4) ◽  
pp. 1436-1447 ◽  
Author(s):  
Mark A. Dickson ◽  
William C. Hahn ◽  
Yasushi Ino ◽  
Vincent Ronfard ◽  
Jenny Y. Wu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Epithelial Cells ◽  
Life Span ◽  
Cell Cycle Control ◽  
Growth Control ◽  
Cell Types ◽  
Mesothelial Cells ◽  
Population Doubling ◽  
Htert Expression ◽  
Normal Human

ABSTRACT Normal human cells exhibit a limited replicative life span in culture, eventually arresting growth by a process termed senescence. Progressive telomere shortening appears to trigger senescence in normal human fibroblasts and retinal pigment epithelial cells, as ectopic expression of the telomerase catalytic subunit, hTERT, immortalizes these cell types directly. Telomerase expression alone is insufficient to enable certain other cell types to evade senescence, however. Such cells, including keratinocytes and mammary epithelial cells, appear to require loss of the pRB/p16INK4a cell cycle control mechanism in addition to hTERT expression to achieve immortality. To investigate the relationships among telomerase activity, cell cycle control, senescence, and differentiation, we expressed hTERT in two epithelial cell types, keratinocytes and mesothelial cells, and determined the effect on proliferation potential and on the function of cell-type-specific growth control and differentiation systems. Ectopic hTERT expression immortalized normal mesothelial cells and a premalignant, p16INK4a-negative keratinocyte line. In contrast, when four keratinocyte strains cultured from normal tissue were transduced to express hTERT, they were incompletely rescued from senescence. After reaching the population doubling limit of their parent cell strains, hTERT+ keratinocytes entered a slow growth phase of indefinite length, from which rare, rapidly dividing immortal cells emerged. These immortal cell lines frequently had sustained deletions of the CDK2NA/INK4A locus or otherwise were deficient in p16INK4a expression. They nevertheless typically retained other keratinocyte growth controls and differentiated normally in culture and in xenografts. Thus, keratinocyte replicative potential is limited by a p16INK4a-dependent mechanism, the activation of which can occur independent of telomere length. Abrogation of this mechanism together with telomerase expression immortalizes keratinocytes without affecting other major growth control or differentiation systems.

scholarly journals Modified Cross-Linking, Ligation, and Sequencing of Hybrids (qCLASH) Identifies Kaposi's Sarcoma-Associated Herpesvirus MicroRNA Targets in Endothelial Cells

2018 ◽  
Vol 92 (8) ◽  
Author(s):  
Lauren A. Gay ◽  
Sunantha Sethuraman ◽  
Merin Thomas ◽  
Peter C. Turner ◽  
Rolf Renne
Keyword(s):  
Cell Cycle ◽  
Endothelial Cells ◽  
Endothelial Cell ◽  
Cell Line ◽  
Kaposi's Sarcoma ◽  
Cell Cycle Control ◽  
Kaposi’S Sarcoma ◽  
Cross Linking ◽  
Wild Type ◽  
Latently Infected

ABSTRACTKaposi's sarcoma (KS) tumors are derived from endothelial cells and express Kaposi's sarcoma-associated herpesvirus (KSHV) microRNAs (miRNAs). Although miRNA targets have been identified in B cell lymphoma-derived cells and epithelial cells, little has been done to characterize the KSHV miRNA targetome in endothelial cells. A recent innovation in the identification of miRNA targetomes, cross-linking, ligation, and sequencing of hybrids (CLASH), unambiguously identifies miRNAs and their targets by ligating the two species while both species are still bound within the RNA-induced silencing complex (RISC). We developed a streamlined quick CLASH (qCLASH) protocol that requires a lower cell input than the original method and therefore has the potential to be used on patient biopsy samples. Additionally, we developed a fast-growing, KSHV-negative endothelial cell line derived from telomerase-immortalized vein endothelial long-term culture (TIVE-LTC) cells. qCLASH was performed on uninfected cells and cells infected with either wild-type KSHV or a mutant virus lacking miR-K12-11/11*. More than 1,400 cellular targets of KSHV miRNAs were identified. Many of the targets identified by qCLASH lacked a canonical seed sequence match. Additionally, most target regions in mRNAs originated from the coding DNA sequence (CDS) rather than the 3′ untranslated region (UTR). This set of genes includes some that were previously identified in B cells and some new genes that warrant further study. Pathway analysis of endothelial cell targets showed enrichment in cell cycle control, apoptosis, and glycolysis pathways, among others. Characterization of these new targets and the functional consequences of their repression will be important in furthering our understanding of the role of KSHV miRNAs in oncogenesis.IMPORTANCEKS lesions consist of endothelial cells latently infected with KSHV. Cells that make up these lesions express KSHV miRNAs. Identification of the targets of KSHV miRNAs will help us understand their role in viral oncogenesis. The cross-linking and sequencing of hybrids (CLASH) protocol is a method for unambiguously identifying miRNA targetomes. We developed a streamlined version of CLASH, called quick CLASH (qCLASH). qCLASH requires a lower initial input of cells than for its parent protocol. Additionally, a new fast-growing KSHV-negative endothelial cell line, named TIVE-EX-LTC cells, was established. qCLASH was performed on TIVE-EX-LTC cells latently infected with wild-type (WT) KSHV or a mutant virus lacking miR-K12-11/11*. A number of novel targets of KSHV miRNAs were identified, including targets of miR-K12-11, the ortholog of the cellular oncogenic miRNA (oncomiR) miR-155. Many of the miRNA targets were involved in processes related to oncogenesis, such as glycolysis, apoptosis, and cell cycle control.

Deconstructing the molecular mechanisms of cell cycle control in a mouse adrenocortical cell line: Roles of ACTH

2003 ◽  
Vol 61 (3) ◽  
pp. 268-274 ◽  
Author(s):  
K�tia M. Rocha ◽  
F�bio L. Forti ◽  
Ana P. Lepique ◽  
Hugo A. Armelin
Keyword(s):  
Cell Cycle ◽  
Cell Line ◽  
Molecular Mechanisms ◽  
Cell Cycle Control ◽  
Adrenocortical Cell
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