Chronic p53-independent p21 expression causes genomic instability by deregulating replication licensing

The cyclin-dependent kinase inhibitor p21WAF1/CIP1 (p21) is a cell-cycle checkpoint effector and inducer of senescence, regulated by p53. Yet, evidence suggests that p21 could also be oncogenic, through a mechanism that has so far remained obscure. We report that a subset of atypical cancerous cells strongly expressing p21 showed proliferation features. This occurred predominantly in p53-mutant human cancers, suggesting p53-independent upregulation of p21 selectively in more aggressive tumour cells. Multifaceted phenotypic and genomic analyses of p21-inducible, p53-null, cancerous and near-normal cellular models showed that after an initial senescence-like phase, a subpopulation of p21-expressing proliferating cells emerged, featuring increased genomic instability, aggressiveness and chemoresistance. Mechanistically, sustained p21 accumulation inhibited mainly the CRL4–CDT2 ubiquitin ligase, leading to deregulated origin licensing and replication stress. Collectively, our data reveal the tumour-promoting ability of p21 through deregulation of DNA replication licensing machinery—an unorthodox role to be considered in cancer treatment, since p21 responds to various stimuli including some chemotherapy drugs

Induction of APOBEC3 exacerbates DNA replication stress and chromosomal instability in early breast and lung cancer evolution

APOBEC3 enzymes are cytosine deaminases implicated in cancer. Precisely when APOBEC3 expression is induced during cancer development remains to be defined. Here we show that specific APOBEC3 genes are upregulated in breast DCIS, and in pre-invasive lung cancer lesions coincident with cellular proliferation. We observe evidence of APOBEC3-mediated subclonal mutagenesis propagated from TRACERx pre-invasive to invasive NSCLC lesions. We find that APOBEC3B exacerbates DNA replication stress and chromosomal instability through incomplete replication of genomic DNA, manifested by accumulation of mitotic ultrafine bridges and 53BP1 nuclear bodies in the G1 phase of the cell cycle. Analysis of TRACERx NSCLC clinical samples and mouse lung cancer models, revealed APOBEC3B expression driving replication stress and chromosome missegregation. We propose that APOBEC3 is functionally implicated in the onset of chromosomal instability and somatic mutational heterogeneity in pre-invasive disease, providing fuel for selection early in cancer evolution

Role of Cdc6 in cell cycle arrest mediated by sustained p21- induction: the role of this pathway in carcinogenesis.

The cyclin-dependent kinase inhibitor p21WAF1/Cip1 (p21) is a cell-cycle checkpoint effector and inducer of senescence, regulated by p53. Yet, evidence suggests that, through a so-far obscure mechanism, p21 could also be oncogenic. We report that a subset of atypical cancerous-cells strongly expressing p21 showed proliferation features. This occurred predominantly in p53-mutant human-cancers suggesting p53-independent upregulation of p21 selectively in more aggressive tumour cells. Multifaceted phenotypic and genomic analyses of p21-inducible, p53-null, cancerous and near-normal cellular models showed that after an initial senescence-like phase, a subpopulation of p21-expressing proliferating cells emerged, featuring increased genomic instability, aggressiveness and chemo-resistance. Mechanistically, sustained p21-accumulation inhibited CRL4CDT2 and SCFSkp2 ubiquitin-ligases, leading to deregulated origin licensing and replication stress. Collectively, our data shed reveal tumour-promoting ability of p21 through deregulation of DNA replication licensing machinery, an unorthodox role to be considered in cancer treatment, since p21 responds to various stimuli including some chemotherapy drugs.Ο κυκλινο- εξαρτώμενος αναστολέας κινασών p21WAF1/Cip1 (p21) αποτελεί σημαντικό παράγοντα ελέγχου του κυτταρικού κύκλου και επαγωγέα της κυτταρικής γήρανσης, ο οποίος ρυθμίζεται από την πρωτεΐνη p53. Σύμφωνα με τη διεθνή βιβλιογραφία, η πρωτεΐνη p21 έχει κατά κύριο λόγο ογκοκατασταλτικό ρόλο, καθώς οποιαδήποτε αντίθετη λειτουργία συνοδευόταν από αδιευκρίνιστους μηχανισμούς δράσεις. Με την παρούσα εργασία, παρουσιάζουμε έναν υποπληθυσμό καρκινικών κυττάρων με μη τυπικά χαρακτηριστικά, τα οποία εκφράζουν τον p21 παράγοντα ενώ παράλληλα εμφανίζουν πολλαπλασιαστική ικανότητα. Τα συγκεκριμένα κύτταρα εμφανίζονται κυρίως, σε καρκινικές αλλοιώσεις με μεταλλαγμένη την p53, υποδηλώνοντας ότι η p53- ανεξάρτητη έκφραση της p21 μπορεί να οδηγήσει επιλεκτικά στην εμφάνιση πιο επιθετικών καρκινικών κυττάρων. Καρκινικά και προ- καρκινικά, επαγώγιμα της p21, κυτταρικά συστήματα με απούσα την p53 εμφάνισαν υποπληθυσμούς κυττάρων με γενωμική αστάθεια, χαρακτηριστικά επιθετικότητας και ανθεκτικότητα σε χημειοθεραπευτικά φάρμακα μετά την πάροδο περιόδου που τα κύτταρα παρουσίασαν φαινότυπο γήρανσης, με τη βοήθεια της χρήσης ποικίλων μεθόδων μοριακής, βιοχημικής και βιοπληροφορικής ανάλυσης. Ενδελεχώς, προτείνεται μηχανισμός κατά τον οποίο η χρόνια έκφραση της πρωτεΐνης p21 κορεννύει τη δράση των λιγασών- ουβικιτίνης CRL4CDT2 και SCFSkp2, προκαλώντας απορρύθμιση των αδειοδοτικών παραγόντων της αντιγραφής του DNA, Cdc6 και Cdt1, καθώς και αντιγραφικό stress. Συνολικά, τα αποτελέσματά μας αναδεικνύουν ένα μέχρι τώρα άγνωστο και ογκογόνο ρόλο της p21, γεγονός που πρέπει να ληφθεί υπόψη κατά το σχεδιασμό θεραπευτικών αγωγών, εφόσον πολλά χημειοθεραπευτικά φάρμακα προωθούν την έκφραση της p21

MKK7 and ARF: new players in the DNA damage response scenery.

Sensing, integrating, and processing of stressogenic signals must be followed by accurate differential response(s) for a cell to survive and avoid malignant transformation. The DNA damage response (DDR) pathway is vital in this process, as it deals with genotoxic/oncogenic insults, having p53 as a nodal effector that performs most of the above tasks. Accumulating data reveal that other pathways are also involved in the same or similar processes, conveying also to p53. Emerging questions are if, how, and when these additional pathways communicate with the DDR axis. Two such stress response pathways, involving the MKK7 stress-activated protein kinase (SAPK) and ARF, have been shown to be interlocked with the ATM/ATR-regulated DDR axis in a highly ordered manner. This creates a new landscape in the DDR orchestrated response to genotoxic/oncogenic insults that is currently discussed

Platelet-rich Plasma and Mesenchymal Stem Cells Local Infiltration Promote Functional Recovery and Histological Repair of Experimentally Transected Sciatic Nerves in Rats

Introduction Platelet-rich plasma (PRP) products and mesenchymal stem cells (MSCs) seem to have a significant potential as neurogenic therapeutic modulator systems. This study aimed to investigate such biological blood derivatives that could enhance nerve regeneration when applied locally in the primary repair of peripheral nerve transection of an experimental rat model. Methods A total of 42 two-month-old male Wistar rats were divided into three “treatment” groups (control, PRP, and MSCs). All the subjects were operated under anesthesia, and the surgical site was infiltrated with either normal saline, PRP derived from the animal’s peripheral blood, or MSCs derived from the animal’s femoral bone marrow. All three groups were also sub-divided into two sub-groups based on the post-operative administration of Non-steroidal anti-inflammatory drugs (NSAIDs) or not in order to evaluate the effect of NSAIDs on the final outcome. Three months post-surgery, electromyography evaluation of both hind limbs (right operated and left non-operated) was performed. The animals were euthanized, and nerve repair specimens were prepared for histology. Results PRP group had a significant effect (p<0.05) on the sciatic nerve repair when compared with the control group, whereas the MSC group had a positive effect but was not statistically significant (p=0.2). The number of counted neural axons at the area distal to the nerve repair site were significantly repetitive (p<0.05) in both the PRP and MSC groups when compared with the control group. Conclusions Both PRP and MSCs appear to play an essential role in the enhancement of nerve repair in terms of functionality and histology. MSCs group demonstrated a positive effect, whereas the PRP group showed statistically significant better results

The Gersdorffite-Bismuthinite-Native Gold Association and the Skarn-Porphyry Mineralization in the Kamariza Mining District, Lavrion, Greece

Vein-type Pb-Ni-Bi-Au-Ag mineralization at the Clemence deposit in the Kamariza and “km3„ in the Lavrion area, was synchronous with the intrusion of a Miocene granodiorite body and related felsic and mafic dikes and sills within marbles and schists in the footwall of (and within) the Western Cycladic detachment system. In the Serpieri deposit (Kamariza area), a porphyry-style pyrrhotite-arsenopyrite mineralized microgranitic dike is genetically related to a garnet-wollastonite bearing skarn characterized by a similar base metal and Ni (up to 219 ppm) enrichment. The Ni⁻Bi⁻Au association in the Clemence deposit consists of initial deposition of pyrite and arsenopyrite followed by an intergrowth of native gold-bismuthinite and oscillatory zoned gersdorffite. The zoning is related to variable As, Ni, and Fe contents, indicating fluctuations of arsenic and sulfur fugacity in the hydrothermal fluid. A late evolution towards higher sulfur fugacity in the mineralization is evident by the deposition of chalcopyrite, tennantite, enargite, and galena rimming gersdorffite. At the “km3„ locality, Ni sulfides and sulfarsenides, vaesite, millerite, ullmannite, and polydymite, are enclosed in gersdorffite and/or galena. The gersdorffite is homogenous and contains less Fe (up to 2 wt.%) than that from the Clemence deposit (up to 9 wt.%). Bulk ore analyses of the Clemence ore reveal Au and Ag grades both exceeding 100 g/t, Pb and Zn > 1 wt.%, Ni up to 9700 ppm, Co up to 118 ppm, Sn > 100 ppm, and Bi > 2000 ppm. The “km3„ mineralization is enriched in Mo (up to 36 ppm), Ni (>1 wt.%), and Co (up to 1290 ppm). Our data further support a magmatic contribution to the ore-forming fluids, although remobilization and leaching of metals from previous mineralization and/or host rocks, through the late involvement of non-magmatic fluid in the ore system, cannot be excluded

The Gersdorffite-Bismuthinite-Native Gold Association and the Skarn-Porphyry Mineralization in the Kamariza Mining District, Lavrion, Greece

Vein-type Pb-Ni-Bi-Au-Ag mineralization at the Clemence deposit in the Kamariza and “km3” in the Lavrion area, was synchronous with the intrusion of a Miocene granodiorite body and related felsic and mafic dikes and sills within marbles and schists in the footwall of (and within) the Western Cycladic detachment system. In the Serpieri deposit (Kamariza area), a porphyry-style pyrrhotite-arsenopyrite mineralized microgranitic dike is genetically related to a garnet-wollastonite bearing skarn characterized by a similar base metal and Ni (up to 219 ppm) enrichment. The Ni–Bi–Au association in the Clemence deposit consists of initial deposition of pyrite and arsenopyrite followed by an intergrowth of native gold-bismuthinite and oscillatory zoned gersdorffite. The zoning is related to variable As, Ni, and Fe contents, indicating fluctuations of arsenic and sulfur fugacity in the hydrothermal fluid. A late evolution towards higher sulfur fugacity in the mineralization is evident by the deposition of chalcopyrite, tennantite, enargite, and galena rimming gersdorffite. At the “km3” locality, Ni sulfides and sulfarsenides, vaesite, millerite, ullmannite, and polydymite, are enclosed in gersdorffite and/or galena. The gersdorffite is homogenous and contains less Fe (up to 2 wt.%) than that from the Clemence deposit (up to 9 wt.%). Bulk ore analyses of the Clemence ore reveal Au and Ag grades both exceeding 100 g/t, Pb and Zn > 1 wt.%, Ni up to 9700 ppm, Co up to 118 ppm, Sn > 100 ppm, and Bi > 2000 ppm. The “km3” mineralization is enriched in Mo (up to 36 ppm), Ni (>1 wt.%), and Co (up to 1290 ppm). Our data further support a magmatic contribution to the ore-forming fluids, although remobilization and leaching of metals from previous mineralization and/or host rocks, through the late involvement of non-magmatic fluid in the ore system, cannot be excluded.This selected paper is published as Voudouris, Panagiotis; Mavrogonatos, Constantinos; Rieck, Branko; Kolitsch, Uwe; Spry, Paul G.; Scheffer, Christophe; Tarantola, Alexandre; Vanderhaeghe, Olivier; Galanos, Emmanouil; Melfos, Vasilios; Zaimis, Stefanos; Soukis, Konstantinos; Photiades, Adonis. 2018. "The Gersdorffite-Bismuthinite-Native Gold Association and the Skarn-Porphyry Mineralization in the Kamariza Mining District, Lavrion, Greece" Minerals 8, no. 11: 531. doi:10.3390/min8110531.</p