Fosfataasien avulla syövän kimppuun

Syöpäsolujen sisäisten viestiverkostojen toiminnan muuttuminen on tärkeä syövän syntymekanismi ja vaikuttaa monien syöpälääkkeiden vasteisiin. Tärkein viestiverkostojen toimintaa säätelevä biokemiallinen mekanismi on viestintään osallistuvien proteiinien fosforylaatio, joka muuttaa kohdeproteiinin aktiivisuutta. Proteiinien fosforylaatiota säätelee kinaasiproteiinien ja fosforylaatiota poistavien fosfataasien välinen tasapaino. Useita onkogeenisia kinaaseja vastaan on kehitetty lääkkeitä, mutta valitettavasti niiden kliininen teho jää useimmiten hyvinkin lyhytaikaiseksi. Sen sijaan useiden fosfataasien merkitys syövässä on toistaiseksi ollut huonosti tunnettu. Viimeaikaiset tutkimukset ovat osoittaneet, että fosfataaseilla on tärkeä merkitys syövässä ja että niiden aktiivisuuden lääkkeellinen muokkaaminen voisi tarjota täysin uusia mahdollisuuksia syövän hoitoon

Differential Regulation of Decorin and Biglycan Gene Expression by Dexamethasone and Retinoic Acid in Cultured Human Skin Fibroblasts

Proteoglycans participate in the assembly of extracellular matrix, directly by interacting with other matrix components and indirectly by regulating cellular growth-factor responses. We have studied the regulation of gene expression of two small extracellular matrix chondroitin/dermatan sulfate proteoglycans, decorin and biglycan, by dexamethasone and retinoic acid In cultured human skin fibroblasts. Dexamethasone increased decorin production, maximally 4,8- fold, and decorin mRNA levels up to 2.3-fold, but had no effect on biglycan production or mRNA levels. Dexamethasone also prevented transforming growth factor-β-elicited down-regulation of decorin mRNA levels and production by dermal fibroblasts. In addition, dexamethasone potently inhibited enhancement of biglycan production and mRNA levels by transforming growth factor-β. Retinoic acid dose dependently reduced decorin mRNA levels (by 51%) and production (by 72%), but had no effect on biglycan gene expression. Retinoic acid did not alter the effect of transforming growth factor-β on decorin or biglycan production or mRNA levels. These results provide evidence that tile effects of glucocorticoids and retinoids on dermal connective tissue are partially mediated via altered expression of decorin and biglycan, which both in turn regulate the activity of transforming growth factor-β, the most potent stimulator of connective tissue deposition

Good guy in bad company: How STRNs convert PP2A into an oncoprotein

Certain Protein Phosphatase 2A (PP2A) complexes are human tumor suppressors. In contrast, a paper in this issue of Cancer Cell and two other recent studies demonstrate that PP2A-STRN3/4 complexes inactivate Hippo tumor suppressor pathway, resulting in YAP activation and tumorigenesis. Furthermore, this new oncogenic phosphatase mechanism may be druggable</p

Cancer stem cell phosphatases

Cancer stem cells (CSCs) are involved in the initiation and progression of human malignancies by enabling cancer tissue self-renewal capacity and constituting the therapy-resistant population of tumor cells. However, despite the exhausting characterization of CSC genetics, epigenetics, and kinase signaling, eradication of CSCs remains an unattainable goal in most human malignancies. While phosphatases contribute equally with kinases to cellular phosphoregulation, our understanding of phosphatases in CSCs lags severely behind our knowledge about other CSC signaling mechanisms. Many cancer-relevant phosphatases have recently become druggable, indicating that further understanding of the CSC phosphatases might provide novel therapeutic opportunities. This review summarizes the current knowledge about fundamental, but yet poorly understood involvement of phosphatases in the regulation of major CSC signaling pathways. We also review the functional roles of phosphatases in CSC self-renewal, cancer progression, and therapy resistance; focusing particularly on hematological cancers and glioblastoma. We further discuss the small molecule targeting of CSC phosphatases and their therapeutic potential in cancer combination therapies

SHARPIN S146 phosphorylation mediates ARP2/3 interaction, cancer cell invasion and metastasis

SHARPIN is involved in several cellular processes and promotes cancer progression. However, how the choice between different functions of SHARPIN is post-translationally regulated is unclear. Here, we characterized SHARPIN phosphorylation by mass spectrometry and in vitro kinase assay. Focusing on S131 and S146, we demonstrate that they have a role in SHARPIN-ARP2/3 complex interaction, but play no role in integrin inhibition or LUBAC activation. Consistent with its novel role in ARP2/3 regulation, S146 phosphorylation of SHARPIN promoted lamellipodia formation. We also demonstrate that SHARPIN S146 phosphorylation-mediated ARP2/3 interaction is sensitive to inhibition of ERK1/2 or reactivation of protein phosphatase 2A (PP2A). Notably, CRISPR/Cas9-mediated knockout of SHARPIN abrogated three-dimensional (3D) invasion of several cancer cell lines. The 3D invasion of cancer cells was rescued by overexpression of the wild-type SHARPIN, but not by SHARPIN S146A mutant. Finally, we demonstrate that inhibition of phosphorylation at S146 significantly reduces in vivo metastasis in a zebrafish model. Collectively, these results map SHARPIN phosphorylation sites and identify S146 as a novel phosphorylation switch defining ARP2/3 interaction and cancer cell invasion. This article has an associated First Person interview with the first author of the paper.</p

Evaluation of prognostic biomarkers in a population-validated Finnish HNSCC patient cohort

Introduction Prognostic biomarkers and novel therapeutic approaches have been slow to emerge in the treatment of head and neck squamous cell carcinoma (HNSCC). In this study, an HNSCC patient cohort is created and performance of putative prognostic biomarkers investigated in a population-validated setting. The overall goal is to develop a novel way to combine biomarker analyses with population-level clinical data on HNSCC patients and thus to improve the carryover of biomarkers into clinical practice. Materials and methods To avoid selection biases in retrospective study design, all HNSCC patients were identified and corresponding clinical data were collected from the Southwest Finland geographical area. A particular emphasis was laid on avoiding potential biases in sample selection for immunohistochemical staining analyses. Staining results were evaluated for potential prognostic resolution. Results After comprehensive evaluation, the patient cohort was found to be representative of the background population in terms of clinical characteristics such as patient age and TNM stage distribution. A negligible drop-out of 1.3% (6/476) was observed during the first follow-up year. By immunohistochemical analysis, the role of previously implicated HNSCC biomarkers (p53, EGFR, p16, CIP2A, Oct4, MET, and NDFIP1) was investigated.Discussion ​​​​​​​Our exceptionally representative patient material supports the use of population validation to improve the applicability of results to real-life situations. The failure of the putative prognostic biomarkers emphasizes the need for controlling bias in retrospective studies, especially in the heterogenous tumor environment of HNSCC. The resolution of simple prognostic examination is unlikely to be sufficient to identify biomarkers for clinical practice of HNSCC.</p

PRELI is a mitochondrial regulator of human primary T-helper cell apoptosis, STAT6, and Th2-cell differentiation

The identification of novel factors regulating human T helper (Th)–cell differentiation into functionally distinct Th1 and Th2 subsets is important for understanding the mechanisms behind human autoimmune and allergic diseases. We have identified a protein of relevant evolutionary and lymphoid interest (PRELI), a novel protein that induces oxidative stress and a mitochondrial apoptosis pathway in human primary Th cells. We also demonstrated that PRELI inhibits Th2-cell development and down-regulates signal transducer and activator of transcription 6 (STAT6), a key transcription factor driving Th2 differentiation. Our data suggest that calpain, an oxidative stress–induced cysteine protease, is involved in the PRELI-induced down-regulation of STAT6. Moreover, we observed that a strong T-cell receptor (TCR) stimulus induces expression of PRELI and inhibits Th2 development. Our results suggest that PRELI is involved in a mechanism wherein the strength of the TCR stimulus influences the polarization of Th cells. This study identifies PRELI as a novel factor influencing the human primary Th-cell death and differentiation

Cancer cell line microarray as a novel screening method for identification of radioresistance biomarkers in head and neck squamous cell carcinoma

Background: Currently, no clinically useful biomarkers for radioresistance are available in head and neck squamous cell carcinoma (HNSCC). This study assesses the usefulness of Cell Line Microarray (CMA) method to enhance immunohistochemical screening of potential immunohistochemical biomarkers for radioresistance in HNSCC cell lines.Methods: Twenty-nine HNSCC cell lines were cultured, cell pellets formalin-fixed, paraffin-embedded, and arrayed. Radioresistance features of the cell lines were combined to immunohistochemical stains for p53, NDFIP1, EGFR, stem cell marker Oct4, and PP2A inhibitor CIP2A.Results: Expression of p53, EGFR or CIP2A did not indicate intrinsic radioresistance in vitro. Stem cell marker Oct4 nuclear positivity and NDFIP1 nuclear positivity was correlated with increased intrinsic radioresistance.Conclusion: The usefulness of CMA in analysis of HNSCC cell lines and discovery of biomarkers is demonstrated. CMA is very well adapted to both testing of antibodies in a large panel of cell lines as well as correlating staining results with other cell line characteristics. In addition, CMA-based antibody screening proved an efficient and relatively simple method to identify potential radioresistance biomarkers in HNSCC.</p