scholarly journals Loss of mutant TP53 does not impair the sustained proliferation, survival or metastasis of diverse cancer cells

2020 ◽  
Author(s):  
Zilu Wang ◽  
François Vaillant ◽  
Catherine Chang ◽  
Chris Riffkin ◽  
Elizabeth Lieschke ◽  
...  
Keyword(s):  
Human Cancer ◽  
Hot Spot ◽  
Point Mutations ◽  
Chemotherapeutic Agents ◽  
Dominant Negative ◽  
Loss Of Function ◽  
Negative Effects ◽  
Substantial Impact ◽  
Human Cancer Cell Lines ◽  
Cellular Stresses

AbstractThe tumour suppressor TP53 is the most frequently mutated gene in human cancer and these aberrations confer poor chemotherapeutic responses1-3. Point mutations typically cluster in the DNA binding domain, with certain ‘hot-spot’ residues disproportionally represented1-4 These mutations abrogate binding of the TP53 transcription factor to DNA and thereby prevent upregulation of genes critical for tumour suppression (loss-of-function)1-3. Mutant TP53 is reported to additionally contribute to tumour development, sustained growth and metastasis not only through dominant-negative effects on wild-type TP535 but also through neomorphic gain-of-function (GOF) activities6. Understanding the contributions of these postulated attributes of mutant TP53 to the development and expansion of tumours will facilitate the design of rational therapeutic strategies. Here we used CRISPR/CAS9 to delete mutant TP53 in a panel of diverse human cancer cell lines. The loss of mutant TP53 expression had no impact on the survival, proliferative capacity or metabolic state of the tumour cells, nor did it sensitise them to cellular stresses and chemotherapeutic agents. These data suggest that putative GOF effects of mutant TP53 are not universally required for the sustained survival and proliferation of fully malignant cells. Therefore, therapeutic approaches that abrogate expression or function of mutant TP53 would not be expected to have substantial impact.

scholarly journals p53 Mutants Have Selective Dominant-Negative Effects on Apoptosis but Not Growth Arrest in Human Cancer Cell Lines

2000 ◽  
Vol 20 (3) ◽  
pp. 770-778 ◽  
Author(s):  
Oscar N. Aurelio ◽  
Xiao-Tang Kong ◽  
Swati Gupta ◽  
Eric J. Stanbridge
Keyword(s):  
Human Cancer ◽  
Growth Arrest ◽  
Carcinoma Cells ◽  
Dominant Negative ◽  
Wild Type ◽  
Osteosarcoma Cells ◽  
Negative Effects ◽  
Human Cancer Cell Lines ◽  
Lung Carcinoma Cells ◽  
Apoptotic Pathways

ABSTRACT A bidirectional expression vector that allowed equal transcription of cloned wild-type and mutant p53 cDNAs from the same vector was developed. The vector was transfected into CaLu 6 lung carcinoma cells or Saos-2 osteosarcoma cells. All p53 mutants examined were recessive to wild-type p53 transactivation ofp21WAF1/CIP1 but dominant-negative for transactivation of Bax. An examination of effects on growth arrest and apoptotic pathways indicated that all mutants were recessive to wild type for growth arrest but only three of seven mutants were dominant negative for induction of apoptosis.

scholarly journals Defining relative mutational difficulty to understand cancer formation and prevention

2019 ◽  
Author(s):  
Lin Shan ◽  
Jiao Yu ◽  
Zhengjin He ◽  
Shishuang Chen ◽  
Mingxian Liu ◽  
...  
Keyword(s):  
Human Cancer ◽  
Low Frequency ◽  
Dominant Negative ◽  
Missense Mutations ◽  
Nucleotide Change ◽  
P53 Mutations ◽  
Loss Of Function ◽  
Functional Importance ◽  
Negative Effects ◽  
Different Types

SummaryMost mutations in human cancer are low-frequency missense mutations, whose functional status remains hard to predict. Here we show that depending on the type of nucleotide change and the surrounding sequences, the tendency to generate each type of nucleotide mutations varies greatly, even by several hundred folds. Therefore, a cancer-promoting mutation may appear only in a small number of cancer cases, if the underlying nucleotide change is too difficult to generate. We propose a method that integrates both the original mutation counts and their relative mutational difficulty. Using this method, we can accurately predict the functionality of hundreds of low-frequency missense mutations in p53, PTEN and INK4A. Many loss-of-function p53 mutations with dominant negative effects were identified, and the functional importance of several regions in p53 structure were highlighted by this analysis. Furthermore, mutational difficulty analysis also points to potential means of cancer prevention. Our study not only established relative mutational difficulties for different types of mutations in human cancer, but also showed that by incorporating such parameter, we can bring new angles to understanding cancer formation and prevention.

scholarly journals AKT1-CREB stimulation of PDGFRα expression is pivotal for PTEN deficient tumor development

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Xiaofeng Wan ◽  
Meng Zhou ◽  
Fuqiang Huang ◽  
Na Zhao ◽  
Xu Chen ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Human Cancer ◽  
Critical Role ◽  
Tumor Development ◽  
Growth Factor Receptor ◽  
Conditional Knockout ◽  
Loss Of Function ◽  
Akt Inhibitor ◽  
Human Cancer Cell Lines ◽  
Direct Binding

AbstractAs evidenced by the behavior of loss-of-function mutants of PTEN in the context of a gain-of-function mutation of AKT1, the PTEN-AKT1 signaling pathway plays a critical role in human cancers. In this study, we demonstrated that a deficiency in PTEN or activation of AKT1 potentiated the expression of platelet-derived growth factor receptor α (PDGFRα) based on studies on Pten−/− mouse embryonic fibroblasts, human cancer cell lines, the hepatic tissues of Pten conditional knockout mice, and human cancer tissues. Loss of PTEN enhanced PDGFRα expression via activation of the AKT1-CREB signaling cascade. CREB transactivated PDGFRα expression by direct binding of the promoter of the PDGFRα gene. Depletion of PDGFRα attenuated the tumorigenicity of Pten-null cells in nude mice. Moreover, the PI3K-AKT signaling pathway has been shown to positively correlate with PDGFRα expression in multiple cancers. Augmented PDGFRα was associated with poor survival of cancer patients. Lastly, combination treatment with the AKT inhibitor MK-2206 and the PDGFR inhibitor CP-673451 displayed synergistic anti-tumor effects. Therefore, activation of the AKT1-CREB-PDGFRα signaling pathway contributes to the tumor growth induced by PTEN deficiency and should be targeted for cancer treatment.

Cation channel regulation by COOH-terminal cytoplasmic tail of polycystin-1: mutational and functional analysis

2002 ◽  
Vol 8 (2) ◽  
pp. 87-98 ◽  
Author(s):  
David H. Vandorpe ◽  
Sabine Wilhelm ◽  
Lianwei Jiang ◽  
Oxana Ibraghimov-Beskrovnaya ◽  
Marina N. Chernova ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Point Mutations ◽  
Coiled Coil ◽  
Cytoplasmic Tail ◽  
Surface Expression ◽  
Dominant Negative ◽  
Cation Channel ◽  
Loss Of Function ◽  
Cation Current ◽  
Autosomal Dominant Polycystic Kidney

Polycystin-1 (PKD1) mutations account for ∼85% of autosomal dominant polycystic kidney disease (ADPKD). We have shown previously that oocyte surface expression of a transmembrane fusion protein encoding part of the cytoplasmic COOH terminus of PKD1 increases activity of a Ca2+-permeable cation channel. We show here that human ADPKD mutations incorporated into this fusion protein attenuated or abolished encoded cation currents. Point mutations and truncations showed that cation current expression requires integrity of a region encompassing the putative coiled coil domain of the PKD1 cytoplasmic tail. Whereas these loss-of-function mutants did not exhibit dominant negative phenotypes, coexpression of a fusion protein expressing the interacting COOH-terminal cytoplasmic tail of PKD2 did suppress cation current. Liganding of the ectodomain of the PKD1 fusion protein moderately activated cation current. The divalent cation permeability and pharmacological profile of the current has been extended. Inducible expression of the PKD1 fusion in EcR-293 cells was also associated with activation of cation channels and increased Ca2+ entry.

scholarly journals Therapeutic targeting of KSP in preclinical models of high-risk neuroblastoma

2020 ◽  
Vol 12 (562) ◽  
pp. eaba4434
Author(s):  
Karin Hansson ◽  
Katarzyna Radke ◽  
Kristina Aaltonen ◽  
Jani Saarela ◽  
Adriana Mañas ◽  
...  
Keyword(s):  
High Risk ◽  
Human Cancer ◽  
Neuroblastoma Cell ◽  
Human Tumor ◽  
Loss Of Function ◽  
Human Cancer Cell Lines ◽  
Dismal Prognosis ◽  
Tumor Types ◽  
Genome Scale

Neuroblastoma is a childhood malignancy with often dismal prognosis; relapse is common despite intense treatment. Here, we used human tumor organoids representing multiple MYCN-amplified high-risk neuroblastomas to perform a high-throughput drug screen with approved or emerging oncology drugs. Tumor-selective effects were calculated using drug sensitivity scores. Several drugs with previously unreported anti-neuroblastoma effects were identified by stringent selection criteria. ARRY-520, an inhibitor of kinesin spindle protein (KSP), was among those causing reduced viability. High expression of the KSP-encoding gene KIF11 was associated with poor outcome in neuroblastoma. Genome-scale loss-of-function screens in hundreds of human cancer cell lines across 22 tumor types revealed that KIF11 is particularly important for neuroblastoma cell viability. KSP inhibition in neuroblastoma patient-derived xenograft (PDX) cells resulted in the formation of abnormal monoastral spindles, mitotic arrest, up-regulation of mitosis-associated genes, and apoptosis. In vivo, KSP inhibition caused regression of MYCN-amplified neuroblastoma PDX tumors. Furthermore, treatment of mice harboring orthotopic neuroblastoma PDX tumors resulted in increased survival. Our results suggested that KSP inhibition could be a promising treatment strategy in children with high-risk neuroblastoma.

scholarly journals Lrrk regulates the dynamic profile of dendritic Golgi outposts through the golgin Lava lamp

2015 ◽  
Vol 210 (3) ◽  
pp. 471-483 ◽  
Author(s):  
Chin-Hsien Lin ◽  
Hsun Li ◽  
Yi-Nan Lee ◽  
Ying-Ju Cheng ◽  
Ruey-Meei Wu ◽  
...  
Keyword(s):  
Secretory Pathway ◽  
Kinase Activity ◽  
Dominant Negative ◽  
Dendritic Arbor ◽  
Leucine Rich Repeat ◽  
Loss Of Function ◽  
Negative Effects ◽  
Golgi Membranes ◽  
Prominent Component ◽  
Dynamic Profile

Constructing the dendritic arbor of neurons requires dynamic movements of Golgi outposts (GOPs), the prominent component in the dendritic secretory pathway. GOPs move toward dendritic ends (anterograde) or cell bodies (retrograde), whereas most of them remain stationary. Here, we show that Leucine-rich repeat kinase (Lrrk), the Drosophila melanogaster homologue of Parkinson’s disease–associated Lrrk2, regulates GOP dynamics in dendrites. Lrrk localized at stationary GOPs in dendrites and suppressed GOP movement. In Lrrk loss-of-function mutants, anterograde movement of GOPs was enhanced, whereas Lrrk overexpression increased the pool size of stationary GOPs. Lrrk interacted with the golgin Lava lamp and inhibited the interaction between Lva and dynein heavy chain, thus disrupting the recruitment of dynein to Golgi membranes. Whereas overexpression of kinase-dead Lrrk caused dominant-negative effects on GOP dynamics, overexpression of the human LRRK2 mutant G2019S with augmented kinase activity promoted retrograde movement. Our study reveals a pathogenic pathway for LRRK2 mutations causing dendrite degeneration.

Inflammaging of Female Reproductive System: a Molecular Landscape

2020 ◽  
Vol 13 ◽  
Author(s):  
Valeriia Rodichkina ◽  
Igor Kvetnoy ◽  
Victoria Polyakova ◽  
Alexander Arutjunyan ◽  
Ruslan Nasyrov ◽  
...  
Keyword(s):  
Cellular Senescence ◽  
Functional Decline ◽  
Reproductive Function ◽  
Reproductive Age ◽  
Loss Of Function ◽  
Negative Effects ◽  
Age Related ◽  
Complex Biological Process ◽  
Secretory Phenotype ◽  
Cellular Stresses

: Aging is a complex biological process, a major aspect of which is the accumulation of somatic changes throughout the life. Cellular senescence is a condition in which cells undergo an irreversible cell cycle arrest in response to various cellular stresses. Once the cells begin to senesce, they become more resistant to any mutagens, including oncogenic factors. Inflammaging (inflammatory aging) is an age-related, chronic and systemic inflammatory condition realized by cells with the senescence associated secretory phenotype (SASP). These recently recognized senescent phenotypes associated with aging have been reported to promote better wound healing, embryonic development, as well as stimulation and extension of the tumor process. It is assumed that cellular senescence contributes to age-related decline of reproductive function due to the association of senescent cells with aging and age-related diseases. Thus, SASPs have both positive and negative effects, depending on the biological context. SASP cell accumulation in tissues contributes to an age-related functional decline of the tissue and organ state. In this review, the term “cellular senescence” is used to refer the processes of cells irreversible growth inhibition during their viable state, while the term “aging” is used to indicate the deterioration of tissues due to loss of function. Late reproductive age is associated with infertility and possible complications of the onset and maintenance of pregnancy. Senescent cells express pro-inflammatory cytokines, growth factors, and matrix metalloproteinases and some other molecules, collectively called the senescence associated secretory phenotype (SASP).

scholarly journals Dominant-negative effects of human P/Q-type Ca2+ channel mutations associated with episodic ataxia type 2

2006 ◽  
Vol 290 (4) ◽  
pp. C1209-C1220 ◽  
Author(s):  
Chung-Jiuan Jeng ◽  
Yu-Ting Chen ◽  
Yi-Wen Chen ◽  
Chih-Yung Tang
Keyword(s):  
Dominant Negative ◽  
Episodic Ataxia ◽  
Molar Ratio ◽  
Loss Of Function ◽  
Negative Effects ◽  
Autosomal Dominant Disorder ◽  
Episodic Ataxia Type 2 ◽  
Episodic Ataxia Type ◽  
Suppression Effects

Episodic ataxia type 2 (EA2) is an inherited autosomal dominant disorder related to cerebellar dysfunction and is associated with mutations in the pore-forming α1A-subunits of human P/Q-type Ca2+ channels (Cav2.1 channels). The majority of EA2 mutations result in significant loss-of-function phenotypes. Whether EA2 mutants may display dominant-negative effects in human, however, remains controversial. To address this issue, five EA2 mutants in the long isoform of human α1A-subunits were expressed in Xenopus oocytes to explore their potential dominant-negative effects. Upon coexpressing the cRNA of α1A-WT with each α1A-mutant in molar ratios ranging from 1:1 to 1:10, the amplitude of Ba2+ currents through wild-type (WT)-Cav2.1 channels decreased significantly as the relative molar ratio of α1A-mutants increased, suggesting the presence of an α1A-mutant-specific suppression effect. When we coexpressed α1A-WT with proteins not known to interact with Cav2.1 channels, we observed no significant suppression effects. Furthermore, increasing the amount of auxiliary subunits resulted in partial reversal of the suppression effects in nonsense but not missense EA2 mutants. On the other hand, when we repeated the same coinjection experiments of α1A-WT and mutant using a splice variant of α1A-subunit that contained a considerably shorter COOH terminus (i.e., the short isoform), no significant dominant-negative effects were noted until we enhanced the relative molar ratio to 1:10. Altogether, these results indicate that for human WT-Cav2.1 channels comprising the long-α1A-subunit isoform, both missense and nonsense EA2 mutants indeed display prominent dominant-negative effects.

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