Class I Phosphoinositide 3-Kinase PIK3CA/p110α and PIK3CB/p110β Isoforms in Endometrial Cancer

The phosphoinositide 3-kinase (PI3K) signalling pathway is highly dysregulated in cancer, leading to elevated PI3K signalling and altered cellular processes that contribute to tumour development. The pathway is normally orchestrated by class I PI3K enzymes and negatively regulated by the phosphatase and tensin homologue, PTEN. Endometrial carcinomas harbour frequent alterations in components of the pathway, including changes in gene copy number and mutations, in particular in the oncogene PIK3CA, the gene encoding the PI3K catalytic subunit p110α, and the tumour suppressor PTEN. PIK3CB, encoding the other ubiquitously expressed class I isoform p110β, is less frequently altered but the few mutations identified to date are oncogenic. This isoform has received more research interest in recent years, particularly since PTEN-deficient tumours were found to be reliant on p110β activity to sustain transformation. In this review, we describe the current understanding of the common and distinct biochemical properties of the p110α and p110β isoforms, summarise their mutations and highlight how they are targeted in clinical trials in endometrial cancer.

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The catR gene encoding a catalase from Aspergillus niger primary structure and elevated expression through increased gene copy number and use of a strong promoter

Molecular Microbiology ◽

10.1111/j.1365-2958.1993.tb01228.x ◽

1993 ◽

Vol 9 (5) ◽

pp. 989-998 ◽

Cited By ~ 41

Author(s):

Timothy Fowler ◽

Michael W. Rey ◽

Peka Vähä-Vahe ◽

Scott D. Power ◽

Randy M. Berka

Keyword(s):

Aspergillus Niger ◽

Primary Structure ◽

Copy Number ◽

Gene Copy Number ◽

Gene Copy ◽

Gene Encoding ◽

Strong Promoter ◽

Elevated Expression

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The Class II Phosphoinositide 3-Kinase C2β Is Not Essential for Epidermal Differentiation

Molecular and Cellular Biology ◽

10.1128/mcb.25.24.11122-11130.2005 ◽

2005 ◽

Vol 25 (24) ◽

pp. 11122-11130 ◽

Cited By ~ 47

Author(s):

Kazutoshi Harada ◽

Amy B. Truong ◽

Ti Cai ◽

Paul A. Khavari

Keyword(s):

Class Ii ◽

Epidermal Cells ◽

Epidermal Differentiation ◽

Class I ◽

Differentiation Markers ◽

Cellular Processes ◽

Targeted Gene Deletion ◽

Epidermal Growth ◽

Phosphoinositide 3 Kinase

ABSTRACT Phosphoinositide 3-kinases (PI3Ks) regulate an array of cellular processes and are comprised of three classes. Class I PI3Ks include the well-studied agonist-sensitive p110 isoforms; however, the functions of class II and III PI3Ks are less well characterized. Of the three class II PI3Ks, C2α and C2β are widely expressed in many tissues, including the epidermis, while C2γ is confined to the liver. In contrast to the class I PI3K p110α, which is expressed throughout the epidermis, C2β was found to be localized in suprabasal cells, suggesting a potential role for C2β in epidermal differentiation. Overexpressing C2β in epidermal cells in vitro induced differentiation markers. To study a role for C2β in tissue, we generated transgenic mice overexpressing C2β in both suprabasal and basal epidermal layers. These mice lacked epidermal abnormalities. Mice deficient in C2β were then generated by targeted gene deletion. C2β knockout mice were viable and fertile and displayed normal epidermal growth, differentiation, barrier function, and wound healing. To exclude compensation by C2α, RNA interference was then used to knock down both C2α and C2β in epidermal cells simultaneously. Induction of differentiation markers was unaffected in the absence of C2α and C2β. These findings indicate that class II PI3Ks are not essential for epidermal differentiation.

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A novel phosphatidylinositol(3,4,5)P3 pathway in fission yeast

The Journal of Cell Biology ◽

10.1083/jcb.200404150 ◽

2004 ◽

Vol 166 (2) ◽

pp. 205-211 ◽

Cited By ~ 64

Author(s):

Prasenjit Mitra ◽

Yingjie Zhang ◽

Lucia E. Rameh ◽

Maria P. Ivshina ◽

Dannel McCollum ◽

...

Keyword(s):

Fission Yeast ◽

Mammalian Cells ◽

Class I ◽

Unexpected Finding ◽

Class Iii ◽

Growth And Survival ◽

Higher Eukaryotes ◽

Phosphoinositide 3 Kinase ◽

Phosphatidylinositol 4 ◽

Phosphatase And Tensin Homologue

The mammalian tumor suppressor, phosphatase and tensin homologue deleted on chromosome 10 (PTEN), inhibits cell growth and survival by dephosphorylating phosphatidylinositol-(3,4,5)-trisphosphate (PI[3,4,5]P3). We have found a homologue of PTEN in the fission yeast, Schizosaccharomyces pombe (ptn1). This was an unexpected finding because yeast (S. pombe and Saccharomyces cerevisiae) lack the class I phosphoinositide 3-kinases that generate PI(3,4,5)P3 in higher eukaryotes. Indeed, PI(3,4,5)P3 has not been detected in yeast. Surprisingly, upon deletion of ptn1 in S. pombe, PI(3,4,5)P3 became detectable at levels comparable to those in mammalian cells, indicating that a pathway exists for synthesis of this lipid and that the S. pombe ptn1, like mammalian PTEN, suppresses PI(3,4,5)P3 levels. By examining various mutants, we show that synthesis of PI(3,4,5)P3 in S. pombe requires the class III phosphoinositide 3-kinase, vps34p, and the phosphatidylinositol-4-phosphate 5-kinase, its3p, but does not require the phosphatidylinositol-3-phosphate 5-kinase, fab1p. These studies suggest that a pathway for PI(3,4,5)P3 synthesis downstream of a class III phosphoinositide 3-kinase evolved before the appearance of class I phosphoinositide 3-kinases.

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Quantitative proteomic analysis reveals posttranslational responses to aneuploidy in yeast

eLife ◽

10.7554/elife.03023 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 141

Author(s):

Noah Dephoure ◽

Sunyoung Hwang ◽

Ciara O'Sullivan ◽

Stacie E Dodgson ◽

Steven P Gygi ◽

...

Keyword(s):

Protein Complexes ◽

Redox Homeostasis ◽

Gene Copy Number ◽

Gene Copy ◽

Developmental Defects ◽

Protein Levels ◽

Cellular Processes ◽

Universal Feature ◽

Altered Metabolism ◽

Encoding Genes

Aneuploidy causes severe developmental defects and is a near universal feature of tumor cells. Despite its profound effects, the cellular processes affected by aneuploidy are not well characterized. Here, we examined the consequences of aneuploidy on the proteome of aneuploid budding yeast strains. We show that although protein levels largely scale with gene copy number, subunits of multi-protein complexes are notable exceptions. Posttranslational mechanisms attenuate their expression when their encoding genes are in excess. Our proteomic analyses further revealed a novel aneuploidy-associated protein expression signature characteristic of altered metabolism and redox homeostasis. Indeed aneuploid cells harbor increased levels of reactive oxygen species (ROS). Interestingly, increased protein turnover attenuates ROS levels and this novel aneuploidy-associated signature and improves the fitness of most aneuploid strains. Our results show that aneuploidy causes alterations in metabolism and redox homeostasis. Cells respond to these alterations through both transcriptional and posttranscriptional mechanisms.

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Metabolic switching of PI3K-dependent lipid signals

Biochemical Society Transactions ◽

10.1042/bst0350188 ◽

2007 ◽

Vol 35 (2) ◽

pp. 188-192 ◽

Cited By ~ 12

Author(s):

C.P. Downes ◽

N.R. Leslie ◽

I.H. Batty ◽

J. van der Kaay

Keyword(s):

Suppressor Gene ◽

Tumour Suppressor Gene ◽

Metabolic Switch ◽

Inositol Phosphatase ◽

Lipid Phosphatase ◽

Metabolic Switching ◽

Pi3k Signalling ◽

Src Homology ◽

Phosphoinositide 3 Kinase ◽

Phosphatase And Tensin Homologue

The lipid phosphatase, PTEN (phosphatase and tensin homologue deleted on chromosome 10), is the product of a major tumour suppressor gene that antagonizes PI3K (phosphoinositide 3-kinase) signalling by dephosphorylating the 3-position of the inositol ring of PtdIns(3,4,5)P3. PtdIns(3,4,5)P3 is also metabolized by removal of the 5-phosphate catalysed by a distinct family of enzymes exemplified by SHIP1 [SH2 (Src homology 2)-containing inositol phosphatase 1] and SHIP2. Mouse knockout studies, however, suggest that PTEN and SHIP2 have profoundly different biological functions. One important reason for this is likely to be that SHIP2 exists in a relatively inactive state until cells are exposed to growth factors or other stimuli. Hence, regulation of SHIP2 is geared towards stimulus dependent antagonism of PI3K signalling. PTEN, on the other hand, appears to be active in unstimulated cells and functions to maintain basal PtdIns(3,4,5)P3 levels below the critical signalling threshold. We suggest that concomitant inhibition of cysteine-dependent phosphatases, such as PTEN, with activation of SHIP2 functions as a metabolic switch to regulate independently the relative levels of PtdIns(3,4,5)P3 and PtdIns(3,4)P2.

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Effects of oncogenic p110α subunit mutations on the lipid kinase activity of phosphoinositide 3-kinase

Biochemical Journal ◽

10.1042/bj20070681 ◽

2007 ◽

Vol 409 (2) ◽

pp. 519-524 ◽

Cited By ~ 89

Author(s):

Jeffrey D. Carson ◽

Glenn Van Aller ◽

Ruth Lehr ◽

Robert H. Sinnamon ◽

Robert B. Kirkpatrick ◽

...

Keyword(s):

Kinase Activity ◽

Hot Spot ◽

Fold Increase ◽

Biochemical Activity ◽

Gene Encoding ◽

Lipid Kinase ◽

Kinase Activation ◽

Pi3k Signalling ◽

Transforming Activity ◽

Phosphoinositide 3 Kinase

The PIK3CA gene, encoding the p110α catalytic subunit of Class IA PI3Ks (phosphoinositide 3-kinases), is frequently mutated in many human tumours. The three most common tumour-derived alleles of p110α, H1047R, E542K and E545K, were shown to potently activate PI3K signalling in human epithelial cells. In the present study, we examine the biochemical activity of the recombinantly purified PI3K oncogenic mutants. The kinetic characterizations of the wt (wild-type) and the three ‘hot spot’ PI3K mutants show that the mutants all have approx. 2-fold increase in lipid kinase activities. Interestingly, the phosphorylated IRS-1 (insulin receptor substrate-1) protein shows activation of the lipid kinase activity for the wt and H1047R but not E542K and E545K PI3Kα, suggesting that these mutations represent different mechanisms of lipid kinase activation and hence transforming activity in cancer cells.

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Increased or Decreased Levels of Caenorhabditis elegans lon-3, a Gene Encoding a Collagen, Cause Reciprocal Changes in Body Length

Genetics ◽

10.1093/genetics/161.1.83 ◽

2002 ◽

Vol 161 (1) ◽

pp. 83-97 ◽

Cited By ~ 2

Author(s):

Josefin Nyström ◽

Zai-Zhong Shen ◽

Margareta Aili ◽

Anthony J Flemming ◽

Armand Leroi ◽

...

Keyword(s):

Body Length ◽

Gene Copy Number ◽

Gene Copy ◽

Loss Of Function ◽

Gene Encoding ◽

C Elegans ◽

Morphometric Analyses ◽

Genes Encoding ◽

New Mutations

Abstract Body length in C. elegans is regulated by a member of the TGFβ family, DBL-1. Loss-of-function mutations in dbl-1, or in genes encoding components of the signaling pathway it activates, cause worms to be shorter than wild type and slightly thinner (Sma). Overexpression of dbl-1 confers the Lon phenotype characterized by an increase in body length. We show here that loss-of-function mutations in dbl-1 and lon-1, respectively, cause a decrease or increase in the ploidy of nuclei in the hypodermal syncytial cell, hyp7. To learn more about the regulation of body length in C. elegans we carried out a genetic screen for new mutations causing a Lon phenotype. We report here the cloning and characterization of lon-3. lon-3 is shown to encode a putative cuticle collagen that is expressed in hypodermal cells. We show that, whereas putative null mutations in lon-3 (or reduction of lon-3 activity by RNAi) causes a Lon phenotype, increasing lon-3 gene copy number causes a marked reduction in body length. Morphometric analyses indicate that the lon-3 loss-of-function phenotype resembles that caused by overexpression of dbl-1. Furthermore, phenotypes caused by defects in dbl-1 or lon-3 expression are in both cases suppressed by a null mutation in sqt-1, a second cuticle collagen gene. However, whereas loss of dbl-1 activity causes a reduction in hypodermal endoreduplication, the reduction in body length associated with overexpression of lon-3 occurs in the absence of defects in hypodermal ploidy.

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A Prediction Model for Preoperative Risk Assessment in Endometrial Cancer Utilizing Clinical and Molecular Variables

International Journal of Molecular Sciences ◽

10.3390/ijms20051205 ◽

2019 ◽

Vol 20 (5) ◽

pp. 1205 ◽

Cited By ~ 2

Author(s):

Erin Salinas ◽

Marina Miller ◽

Andreea Newtson ◽

Deepti Sharma ◽

Megan McDonald ◽

...

Keyword(s):

Endometrial Cancer ◽

High Risk ◽

Prediction Model ◽

Somatic Mutation ◽

Mirna Expression ◽

Prediction Models ◽

Gene Copy Number ◽

The Cancer Genome Atlas ◽

Gene Copy ◽

Mutation Data

The utility of comprehensive surgical staging in patients with low risk disease has been questioned. Thus, a reliable means of determining risk would be quite useful. The aim of our study was to create the best performing prediction model to classify endometrioid endometrial cancer (EEC) patients into low or high risk using a combination of molecular and clinical-pathological variables. We then validated these models with publicly available datasets. Analyses between low and high risk EEC were performed using clinical and pathological data, gene and miRNA expression data, gene copy number variation and somatic mutation data. Variables were selected to be included in the prediction model of risk using cross-validation analysis; prediction models were then constructed using these variables. Model performance was assessed by area under the curve (AUC). Prediction models were validated using appropriate datasets in The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. A prediction model with only clinical variables performed at 88%. Integrating clinical and molecular data improved prediction performance up to 97%. The best prediction models included clinical, miRNA expression and/or somatic mutation data, and stratified pre-operative risk in EEC patients. Integrating molecular and clinical data improved the performance of prediction models to over 95%, resulting in potentially useful clinical tests.

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Cloning of the PYR3 gene of Ustilago maydis and its use in DNA transformation.

Molecular and Cellular Biology ◽

10.1128/mcb.8.12.5417 ◽

1988 ◽

Vol 8 (12) ◽

pp. 5417-5424 ◽

Cited By ~ 24

Author(s):

G R Banks ◽

S Y Taylor

Keyword(s):

Dna Sequences ◽

Gene Copy Number ◽

Mutant Gene ◽

Ustilago Maydis ◽

Gene Copy ◽

Wild Type ◽

Gene Encoding ◽

E Coli ◽

Multiple Transcripts ◽

Different Types

The Ustilago maydis PYR3 gene encoding dihydroorotase activity was cloned by direct complementation of Escherichia coli pyrC mutations. PYR3 transformants of E. coli pyrC mutants expressed homologous transcripts of a variety of sizes and regained dihydroorotase activity. PYR3 also complemented Saccharomyces cerevisiae ura4 mutations, and again multiple transcripts were expressed in transformants, and enzyme activity was regained. A 1.25-kilobase poly(rA)+ PYR3 transcript was detected in U. maydis itself. Linear DNA carrying the PYR3 gene transformed a U. maydis pyr3-1 pyrimidine auxotroph to prototrophy. Hybridization analysis revealed that three different types of transformants could be generated, depending on the structure of the transforming DNA used. The first type involved exchange of chromosomal mutant gene sequences with the cloned wild-type plasmid sequences. A second type had integrated linear transforming DNA at the chromosomal PYR3 locus, probably via a single crossover event. The third type had integrated transforming DNA sequences at multiple sites in the U. maydis genome. In the last two types, tandemly reiterated copies of the transforming DNA were found to have been integrated. All three types had lost the sensitivity of the parental pyr3-1 mutant to UV irradiation. They had also regained dihydroorotase activity, although its level did not correlate with the PYR3 gene copy number.

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