scholarly journals Mutation-Associated Phenotypic Heterogeneity in Novel and Canonical PIK3CA Helical and Kinase Domain Mutants

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1116
Author(s):  
Arman Ali Ghodsinia ◽  
J-Ann Marie T. Lego ◽  
Reynaldo L. Garcia
Keyword(s):  
Cellular Proliferation ◽  
Acquired Resistance ◽  
Kinase Domain ◽  
Cellular Migration ◽  
Regulatory Subunit ◽  
Cytoskeletal Reorganization ◽  
Apoptosis Resistance ◽  
Pik3ca Mutations ◽  
In Silico Docking ◽  
Mutational Hotspots

Phosphatidylinositol 3-kinase, catalytic subunit alpha (PIK3CA) is an oncogene often mutated in colorectal cancer (CRC). The contribution of PIK3CA mutations in acquired resistance to anti-epidermal growth factor receptor (EGFR) therapy is well documented, but their prognostic and predictive value remain unclear. Domain- and exon-specific mutations are implicated in either favorable or poor prognoses, but there is paucity in the number of mutations characterized outside of the mutational hotspots. Here, two novel non-hotspot mutants—Q661K in exon 13 and C901R in exon 19—were characterized alongside the canonical exon 9 E545K and exon 20 H1047R mutants in NIH3T3 and HCT116 cells. Q661K and E545K both map to the helical domain, whereas C901R and H1047R map to the kinase domain. Results showed variable effects of Q661K and C901R on morphology, cellular proliferation, apoptosis resistance, and cytoskeletal reorganization, with both not having any effect on cellular migration. In comparison, E545K markedly promoted proliferation, survival, cytoskeletal reorganization, migration, and spheroid formation, whereas H1047R only enhanced the first three. In silico docking suggested these mutations negatively affect binding of the p85 alpha regulatory subunit to PIK3CA, thereby relieving PIK3CA inhibition. Altogether, these findings support intra-domain and mutation-specific variability in oncogenic readouts, with implications in degree of aggressiveness.

Molecular characterization of a thyroid tumor-specific transforming sequence formed by the fusion of ret tyrosine kinase and the regulatory subunit RI alpha of cyclic AMP-dependent protein kinase A

1993 ◽  
Vol 13 (1) ◽  
pp. 358-366
Author(s):  
I Bongarzone ◽  
N Monzini ◽  
M G Borrello ◽  
C Carcano ◽  
G Ferraresi ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Tyrosine Kinase ◽  
Kinase Domain ◽  
Regulatory Subunit ◽  
Tyrosine Kinase Domain ◽  
Papillary Thyroid ◽  
Thyroid Carcinomas ◽  
Kinase A

The ret oncogene frequently has been found activated in papillary thyroid carcinomas. A previous characterization of ret activation revealed recombination of its tyrosine kinase domain and sequences derived from an uncharacterized locus (D10S170). The mechanism leading to this recombination was identified as a paracentric inversion of the long arm of chromosome 10, inv(10)(q11.2q21), with the breakpoints occurring where ret and D10S170 were mapped. To further characterize the activation of ret in papillary thyroid carcinomas, we have now isolated and sequenced a second type of ret oncogenic rearrangement not involving the D10S170 locus. The nucleotide sequence indicated that the transforming activity was created by the fusion of the ret tyrosine kinase domain with part of the RI alpha regulatory subunit of protein kinase A (PKA). This is the first example of an oncogenic activity involving a PKA gene. PKA is the main intracellular cyclic AMP receptor, and its RI alpha subunit gene is located on chromosome 17q. RI alpha-ret transcripts encode two isoforms of the chimeric protein (p76 and p81), which display constitutive tyrosine phosphorylation as well as a tyrosine kinase enzymatic activity. Under nonreducing conditions, both isoforms are found in a dimeric configuration because of both homo- and heterodimer formation. Thus, the in vivo activation of ret in human papillary thyroid carcinomas is provided by the fusion of its tyrosine kinase domain with different genes and can be mediated by different mechanisms of gene rearrangement.

scholarly journals Restoration of Retinoid Sensitivity by MDR1 Ribozymes in Retinoic Acid–Resistant Myeloid Leukemic Cells

Blood ◽  
1998 ◽  
Vol 91 (7) ◽  
pp. 2452-2458 ◽  
Author(s):  
Hiromichi Matsushita ◽  
Masahiro Kizaki ◽  
Hiroyuki Kobayashi ◽  
Hironori Ueno ◽  
Akihiro Muto ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Cellular Proliferation ◽  
Therapeutic Potential ◽  
Acquired Resistance ◽  
Leukemic Cells ◽  
Dependent Manner ◽  
P Glycoprotein ◽  
All Trans Retinoic Acid ◽  
Mdr1 Mrna

Complete remission is achieved in a high proportion of patients with acute promyelocytic leukemia (APL) after all-trans retinoic acid (RA) treatment, but most patients relapse and develop RA-resistant APL. We have previously reported that both RA-resistant HL-60 (HL-60R) and APL cells express P-glycoprotein and MDR1 transcripts; and these cells differentiate to mature granulocytes after culture with RA and P-glycoprotein antagonist. Ribozymes have been shown to be able to intercept a target RNA by catalytic activity. To address the role of MDR1 in overcoming RA-resistance in APL cells, we investigated the biologic effects of ribozymes against the MDR1 transcript in HL-60R cells. These ribozymes efficiently cleaved MDR1 mRNA at a specific site in vitro. The 196 MDR1 ribozyme was cloned into an expression vector, and stably transfected (HL-60R/196Rz) cells were obtained. Expression of MDR1 transcripts was decreased in HL-60R/196Rz cells compared with parental HL-60R and empty vector-transfected (HL-60R/neo) cells. Interestingly, RA inhibited cellular proliferation and induced differentiation of HL-60R/196Rz cells in a dose-dependent manner, suggesting reversal of drug resistance in HL-60R cells by the MDR1 ribozyme. These data are direct evidence that P-glycoprotein/MDR1 is responsible in part for acquired resistance to RA in myeloid leukemic cells. The MDR1 ribozyme may be a useful tool for investigating the biology of retinoid resistance and may have therapeutic potential for patients with RA-resistant APL.

scholarly journals Normalization of enzyme expression and activity regulating vitamin A metabolism increases RAR-beta expression and reduces cellular migration and proliferation in diseases caused by tuberous sclerosis gene mutations

2020 ◽  
Author(s):  
ElHusseiny MM Abdelwahab ◽  
Judit Bovari-Biri ◽  
Gabor Smuk ◽  
Tunde Harko ◽  
Janos Fillinger ◽  
...  
Keyword(s):  
Cell Migration ◽  
Retinoic Acid ◽  
Vitamin A ◽  
Tuberous Sclerosis ◽  
Cell Lines ◽  
Cellular Proliferation ◽  
Cellular Migration ◽  
Immunofluorescent Staining ◽  
Vitamin A Metabolism ◽  
Expression And Activity

Abstract Background Mutation in a tuberous sclerosis gene (TSC1 or 2) leads to continuous activation of the mammalian target of rapamycin (mTOR). mTOR activation alters cellular including vitamin A metabolism and retinoic acid receptor beta (RARβ) expression. The goal of the present study was to investigate the molecular connection between vitamin A metabolism and TSC mutation. We also aimed to investigate the effect of the FDA approved drug rapamycin and the vitamin A metabolite retinoic acid (RA) in cell lines with TSC mutation. Methods Expression and activity of vitamin A associated metabolic enzymes and RARβ were assessed in human kidney angiomyolipoma derived cell lines, primary lymphangioleiomyomatosis (LAM) tissue derived LAM cell lines as well as RARβ protein levels were tested in primary LAM lung tissue sections. TaqMan arrays, enzyme activities, qRT-PCRs, immunohistochemistry, immunofluorescent staining and western blotting were performed and analysed. The functional effects of retinoic acid (RA) and rapamycin were tested in a scratch and a BrDU assay to assess cell migration and proliferation. Results Metabolic enzyme arrays revealed a general deregulation of many enzymes involved in vitamin A metabolism including aldehyde dehydrogenases (ALDHs), alcohol dehydrogenases (ADHs) and Cytochrome P450 2E1 (CYP2E1). Furthermore, RARβ downregulation was a characteristic feature of all TSC-deficient cell lines and primary tissues. Combination of the two FDA approved drugs -RA for acute myeloid leukaemia and rapamycin for TSC mutation- normalised ALDH and ADH expression and activity, restored RARβ expression and reduced cellular proliferation and migration. Conclusion Deregulation of vitamin A metabolizing enzymes is a feature of TSC mutation. RA can normalize RARβ levels and limit cell migration, but does not have a significant effect on proliferation. Based on our data, translational studies could confirm whether combination of RA with reduced dosage of rapamycin would have more beneficial effects to higher dosage of rapamycin monotherapy meanwhile reducing adverse effects of rapamycin for patients with TSC mutation.

scholarly journals Role of B-Cell Translocation Gene 1 in the Pathogenesis of Endometriosis

2019 ◽  
Vol 20 (13) ◽  
pp. 3372
Author(s):  
Jeong Sook Kim ◽  
Young Sik Choi ◽  
Ji Hyun Park ◽  
Jisun Yun ◽  
Soohyun Kim ◽  
...  
Keyword(s):  
B Cell ◽  
Cellular Proliferation ◽  
Suppressor Gene ◽  
Cellular Migration ◽  
Matrix Metalloproteinase 2 ◽  
Control Group ◽  
Endometrial Stromal Cells ◽  
Eutopic Endometrium ◽  
Ectopic Endometrium

Estrogen affects endometrial cellular proliferation by regulating the expression of the c-myc gene. B-cell translocation gene 1 (BTG1), a translocation partner of the c-myc, is a tumor suppressor gene that promotes apoptosis and negatively regulates cellular proliferation and cell-to-cell adhesion. The aim of this study was to determine the role of BTG1 in the pathogenesis of endometriosis. BTG1 mRNA and protein expression was evaluated in eutopic and ectopic endometrium of 30 patients with endometriosis (endometriosis group), and in eutopic endometrium of 22 patients without endometriosis (control group). The effect of BTG1 downregulation on cellular migration, proliferation, and apoptosis was evaluated using transfection of primarily cultured human endometrial stromal cells (HESCs) with BTG1 siRNA. BTG1 mRNA expression level of eutopic and ectopic endometrium of endometriosis group were significantly lower than that of the eutopic endometrium of the control group. Migration and wound healing assays revealed that BTG1 downregulation resulted in a significant increase in migration potential of HESCs, characterized by increased expression of matrix metalloproteinase 2 (MMP2) and MMP9. Downregulation of BTG1 in HESCs significantly reduced Caspase 3 expression, indicating a decrease in apoptotic potential. In conclusion, our data suggest that downregulation of BTG1 plays an important role in the pathogenesis of endometriosis.

scholarly journals Roles of TrkC Signaling in the Regulation of Tumorigenicity and Metastasis of Cancer

Cancers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 147 ◽  
Author(s):  
Wook Jin
Keyword(s):  
Fusion Proteins ◽  
Epithelial Mesenchymal Transition ◽  
Tumor Regression ◽  
Acquired Resistance ◽  
Cell Lineage ◽  
Kinase Domain ◽  
Tyrosine Kinase Domain ◽  
Acquired Drug Resistance ◽  
Mesenchymal Transition ◽  
Trk Inhibitors

Tropomyosin receptor kinase (Trk) C contributes to the clinicopathology of a variety of human cancers, and new chimeric oncoproteins containing the tyrosine kinase domain of TrkC occur after fusion to the partner genes. Overexpression of TrkC and TrkC fusion proteins was observed in patients with a variety of cancers, including mesenchymal, hematopoietic, and those of epithelial cell lineage. Both microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) were involved in the regulation of TrkC expression through transcriptional and posttranscriptional alteration. Aberrant activation of TrkC and TrkC fusion proteins markedly induces the epithelial-mesenchymal transition (EMT) program, growth rate, tumorigenic capacity via constitutive activation of Ras-MAP kinase (MAPK), PI3K-AKT, and the JAK2-STAT3 pathway. The clinical trial of TrkC or TrkC fusion-positive cancers with newly developed Trk inhibitors demonstrated that Trk inhibitors were highly effective in inducing tumor regression in patients who do not harbor mutations in the kinase domain. Recently, there has been a progressive accumulation of mutations in TrkC or the TrkC fusion protein detected in the clinic and its related cancer cell lines caused by high-throughput DNA sequencing. Despite given the high overall response rate against Trk or Trk fusion proteins-positive solid tumors, acquired drug resistance was observed in patients with various cancers caused by mutations in the Trk kinase domain. To overcome acquired resistance caused by kinase domain mutation, next-generation Trk inhibitors have been developed, and these inhibitors are currently under investigation in clinical trials.

scholarly journals Minireview: Cyclin D1: Normal and Abnormal Functions

Endocrinology ◽  
2004 ◽  
Vol 145 (12) ◽  
pp. 5439-5447 ◽  
Author(s):  
Maofu Fu ◽  
Chenguang Wang ◽  
Zhiping Li ◽  
Toshiyuki Sakamaki ◽  
Richard G. Pestell
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Chromatin Remodeling ◽  
Original Description ◽  
Cellular Migration ◽  
Regulatory Subunit ◽  
Cyclin Dependent Kinase ◽  
Fat Cell ◽  
Independent Functions ◽  
Cancer Côlon

Abstract Cyclin D1 encodes the regulatory subunit of a holoenzyme that phosphorylates and inactivates the retinoblastoma protein and promotes progression through the G1-S phase of the cell cycle. Amplification or overexpression of cyclin D1 plays pivotal roles in the development of a subset of human cancers including parathyroid adenoma, breast cancer, colon cancer, lymphoma, melanoma, and prostate cancer. Of the three D-type cyclins, each of which binds cyclin-dependent kinase (CDK), it is cyclin D1 overexpression that is predominantly associated with human tumorigenesis and cellular metastases. In recent years accumulating evidence suggests that in addition to its original description as a CDK-dependent regulator of the cell cycle, cyclin D1 also conveys cell cycle or CDK-independent functions. Cyclin D1 associates with, and regulates activity of, transcription factors, coactivators and corepressors that govern histone acetylation and chromatin remodeling proteins. The recent findings that cyclin D1 regulates cellular metabolism, fat cell differentiation and cellular migration have refocused attention on novel functions of cyclin D1 and their possible role in tumorigenesis. In this review, both the classic and novel functions of cyclin D1 are discussed with emphasis on the CDK-independent functions of cyclin D1.

scholarly journals Significance of EGFR/HER2 Expression and PIK3CA Mutations in Giant Cell Tumour of Bone Development

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Raja Amri ◽  
Slim Charfi ◽  
Mohamed Jemaà ◽  
Nabil Miled ◽  
Fathia Slimi ◽  
...  
Keyword(s):  
Giant Cell ◽  
Giant Cell Tumour ◽  
Bone Development ◽  
Bone Tumour ◽  
Growth Factor Receptor ◽  
Kinase Domain ◽  
Cell Tumour ◽  
Pten Gene ◽  
Pik3ca Mutations ◽  
The Stability

Giant Cell Tumour of Bone (GCTB) is a rare bone tumour. Locally aggressive and recurrent, it might evolve into pulmonary metastases. Our present work is aimed at investigating the involvement of the epidermal growth factor receptor (ErbB) family and its downstream effectors in the development and recurrence of GCTB. For this purpose, we used a cohort of 32 GCTB patients and we evaluated the clinicohistological features and the expression of RANKL, EGFR, and HER2. The mutation status of KRAS, PI3KCA, and PTEN gene as potential oncogene involved in GCTB was also evaluated. We found a significant correlation between advanced histological stages, overexpression of EGFR/HER2, and tumour recurrence. Moreover, two mutations were found in the PIK3CA gene: a missense mutation, 1634A>C, detected for the first time in GCTB patients, without influencing the stability of the protein, and a frameshift mutation, c.1658_1659delGTinsC, causing the loss of the protein kinase domain. Altogether, these results suggest that overexpression of HER2/EGFR, Campanacci, and histological stages could be used as a novel prognostic marker for GCTB recurrence.

BCR-ABL point mutants isolated from patients with imatinib mesylate–resistant chronic myeloid leukemia remain sensitive to inhibitors of the BCR-ABL chaperone heat shock protein 90

Blood ◽  
2002 ◽  
Vol 100 (8) ◽  
pp. 3041-3044 ◽  
Author(s):  
Mercedes E. Gorre ◽  
Katharine Ellwood-Yen ◽  
Gabriela Chiosis ◽  
Neal Rosen ◽  
Charles L. Sawyers
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Imatinib Mesylate ◽  
Acquired Resistance ◽  
Philadelphia Chromosome ◽  
Heat Shock Protein 90 ◽  
Resistant Mutant ◽  
Kinase Domain ◽  
Molecular Features ◽  
Clinical Resistance

Clinical resistance to imatinib mesylate is commonly observed in patients with advanced Philadelphia chromosome– positive (Ph+) leukemias. Acquired resistance is typically associated with reactivation of BCR-ABL due to kinase domain mutations or gene amplification, indicating that BCR-ABL remains a viable target for inhibition in these patients. Strategies for overcoming resistance can be envisioned through exploitation of other molecular features of the BCR-ABL protein, such as its dependence on the molecular chaperone heat shock protein 90 (Hsp90). To determine whether inhibition of Hsp90 could induce degradation of imatinib mesylate–resistant, mutant BCR-ABL proteins, hematopoietic cells expressing 2 mutant BCR-ABL proteins found in imatinib mesylate–resistant patients (T315I and E255K) were examined for sensitivity to geldanamycin and 17-allylaminogeldanamycin (17-AAG). Both compounds induced the degradation of wild-type and mutant BCR-ABL and inhibited cell growth, with a trend indicating more potent activity against mutant BCR-ABL proteins. These data support clinical investigations of 17-AAG in imatinib mesylate–resistant Ph+ leukemias.

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