Incidental Detection of TFEB-Amplified Renal Cell Carcinoma by Colocated Gene Amplification of CCND3 (6p21): A Case Report and Review of the Literature

TFEB-amplified renal cell carcinoma (RCC), which belongs to the MITF family of RCC, is characterized by genomic amplification at the 6p21.1 locus where the TFEB gene is located. The vascular endothelial growth factor A and cyclin D3 genes are also located at this same locus. When tumors lack classic morphologic features, they may be classified as "RCC not otherwise specified (NOS)." However, it is increasingly important to accurately diagnose the RCC subtype to define the patient's individual prognosis and select the subsequent therapeutic modalities, which now include targeted agents. Therefore, knowledge of the diagnostic features of TFEB-altered RCCs, such as t(6;11) RCCs and TFEB-amplified RCCs, is critical for identifying these tumors. Herein, we present an interesting case of TFEB-amplified RCC that was initially diagnosed as RCC NOS on biopsy of a renal tumor in a community practice setting with available molecular findings demonstrating CCND3 amplification. The genetic abnormality was "accidentally" detected due to the amplification of the colocated CCND3 gene at the 6p21 locus of the TFEB gene on a limited genetic sequencing panel. This case highlights the importance of molecular tests in accurately diagnosing RCC and carefully interpreting molecular findings in the context of histomorphologic features.

The Cyclin D3 Protein Enforces Monogenic TCRβ Expression by Mediating TCRβ Protein-Signaled Feedback Inhibition of Vβ Recombination

In jawed vertebrates, adaptive immunity depends on the process of V(D)J recombination creating vast numbers of T and B lymphocytes that each expresses unique Ag receptors of uniform specificity. The asynchronous initiation of V-to-(D)J rearrangement between alleles and the resulting protein from one allele signaling feedback inhibition of V recombination on the other allele ensures homogeneous receptor specificity of individual cells. Upon productive Vβ-to-DβJβ rearrangements in noncycling double-negative thymocytes, TCRβ protein signals induction of the cyclin D3 protein to accelerate cell cycle entry, thereby driving proliferative expansion of developing αβ T cells. Through undetermined mechanisms, the inactivation of cyclin D3 in mice causes an increased frequency of αβ T cells that express TCRβ proteins from both alleles, producing lymphocytes of heterogeneous specificities. To determine how cyclin D3 enforces monogenic TCRβ expression, we used our mouse lines with enhanced rearrangement of specific Vβ segments due to replacement of their poor-quality recombination signal sequence (RSS) DNA elements with a better RSS. We show that cyclin D3 inactivation in these mice elevates the frequencies of αβ T cells that display proteins from RSS-augmented Vβ segments on both alleles. By assaying mature αβ T cells, we find that cyclin D3 deficiency increases the levels of Vβ rearrangements that occur within developing thymocytes. Our data demonstrate that a component of the cell cycle machinery mediates TCRβ protein-signaled feedback inhibition in thymocytes to achieve monogenic TCRβ expression and resulting uniform specificity of individual αβ T cells.

[LncRNA RPL22P1-201 affects prostate cancer cell proliferation, cell cycle, and sensitivity to docetaxel by regulating miR-216b-5p expression]

OBJECTIVE

Exploring the effects and mechanisms of long non coding RNA (lncRNA) RPL22P1-201 on prostate cancer cell proliferation, cell cycle, and docetaxel sensitivity by regulating miR-216b-5p expression.

METHODS

The Cancer LncRNA Census database was used to analyze the differential expression of RPL22P1-201 between prostate cancer tissue and normal tissue. Real time quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression level of RPL22P1-201 in prostate cancer cell lines (DU-145, C4-2B, PC3, 22Rv1, LNCaP) and normal prostate epithelial cells (RWPE-1). PC3 cells were divided into si-RPL22P1-201 group (transfected with RPL22P1-201 interference sequence) and si-NC group (transfected with si-NC sequence). Colony formation assay was used to detect the proliferation ability of PC3 cells. Flow cytometry was used to detect the PC3 cell cycle. The CCK-8 method was used to detect the proliferation of PC3 cells in each group after treatment with docetaxel. The dual luciferase reporter gene experiment verifies the binding of RPL22P1-201 to the target gene. qRT-PCR was used to detect the expression level of miR-216b-5p. Western blot was used to detect the expression levels of TrkB, CDK4, cyclin D2, cyclin D3, and CDK6 proteins.

RESULTS

The expression level of RPL22P1-201 in prostate cancer tissue was higher than that in normal tissue (P<0.01). The expression level of RPL22P1-201 in prostate cancer cell lines was higher than that in normal prostate epithelial cells (P<0.01). The number of colonies in the si-NC group and si-RPL22P1-201 group was (256.1 ± 28.79) and (78.77 ± 14.52), respectively. The difference was statistically significant (P<0.01). The G0/G1 cell rates in the si-NC group and si-RPL22P1-201 group were (43.18 ± 4.56)% and (68.85 ± 3.40)%, respectively. The S cell rates were (36.84 ± 2.28)% and (24.27 ± 2.74)%, respectively. The G2/M cell rates were (19.98 ± 2.69)% and (6.88 ± 1.57)%, respectively, and the differences were statistically significant (all P<0.05). The cell survival rate of the si-RPL22P1-201 group under the action of docetaxel was lower than that of the si-NC group (all P<0.05). RPL22P1-201 can pair and bind with miR-216b-5p (P<0.01). Compared with the si-NC group, the si-RPL22P1-201 group showed a decrease in miR-216b-5p expression in PC3 cells (P<0.01), and a decrease in TrkB, CDK4, cyclin D2, cyclin D3, and CDK6 protein expression.

CONCLUSIONS

RPL22P1-201 is highly expressed in prostate cancer, and silencing RPL22P1-201 inhibits prostate cancer PC3 cell proliferation and cell cycle by increasing miR-216b-5p expression, and enhances PC3 cell sensitivity to docetaxel.

Overexpression Populus d-Type Cyclin Gene PsnCYCD1;1 Influences Cell Division and Produces Curved Leaf in Arabidopsis thaliana

d-type cyclins (CYCDs) are a special class of cyclins and play extremely important roles in plant growth and development. In the plant kingdom, most of the existing studies on CYCDs have been done on herbaceous plants, with few on perennial woody plants. Here, we identified a Populus&nbsp;d-type cyclin gene, PsnCYCD1;1, which is mainly transcribed in leaf buds and stems. The promoter of PsnCYCD1;1 activated GUS gene expression and transgenic Arabidopsis lines were strongly GUS stained in whole seedlings and mature anthers. Moreover, subcellular localization analysis showed the fluorescence signal of PsnCYCD1;1-GFP fusion protein is present in the nucleus. Furthermore, overexpression of the PsnCYCD1;1 gene in Arabidopsis can promote cell division and lead to small cell generation and cytokinin response, resulting in curved leaves and twisted inflorescence stems. Moreover, the transcriptional levels of endogenous genes, such as ASs, KNATs, EXP10, and PHB, were upregulated by PsnCYCD1;1. Together, our results indicated that PsnCYCD1;1 participates in cell division by cytokinin response, providing new information on controlling plant architecture in woody plants.

CDK11 Promotes Cytokine-Induced Apoptosis in Pancreatic Beta Cells Independently of Glucose Concentration and Is Regulated by Inflammation in the NOD Mouse Model

Background

Pancreatic islets are exposed to strong pro-apoptotic stimuli: inflammation and hyperglycemia, during the progression of the autoimmune diabetes (T1D). We found that the Cdk11(Cyclin Dependent Kinase 11) is downregulated by inflammation in the T1D prone NOD (non-obese diabetic) mouse model. The aim of this study is to determine the role of CDK11 in the pathogenesis of T1D and to assess the hierarchical relationship between CDK11 and Cyclin D3 in beta cell viability, since Cyclin D3, a natural ligand for CDK11, promotes beta cell viability and fitness in front of glucose.

Methods

We studied T1D pathogenesis in NOD mice hemideficient for CDK11 (N-HTZ), and, in N-HTZ deficient for Cyclin D3 (K11HTZ-D3KO), in comparison to their respective controls (N-WT and K11WT-D3KO). Moreover, we exposed pancreatic islets to either pro-inflammatory cytokines in the presence of increasing glucose concentrations, or Thapsigargin, an Endoplasmic Reticulum (ER)-stress inducing agent, and assessed apoptotic events. The expression of key ER-stress markers (Chop, Atf4 and Bip) was also determined.

Results

N-HTZ mice were significantly protected against T1D, and NS-HTZ pancreatic islets exhibited an impaired sensitivity to cytokine-induced apoptosis, regardless of glucose concentration. However, thapsigargin-induced apoptosis was not altered. Furthermore, CDK11 hemideficiency did not attenuate the exacerbation of T1D caused by Cyclin D3 deficiency.

Conclusions

This study is the first to report that CDK11 is repressed in T1D as a protection mechanism against inflammation-induced apoptosis and suggests that CDK11 lies upstream Cyclin D3 signaling. We unveil the CDK11/Cyclin D3 tandem as a new potential intervention target in T1D.

Lymphoma Driver Mutations in the Pathogenic Evolution of an Iconic Human Autoantibody

Pathogenic autoantibodies arise in many autoimmune diseases, but it is not understood how the cells making them evade immune checkpoints. Here, single-cell multi-omics analysis demonstrates a shared mechanism with lymphoid malignancy in the formation of public rheumatoid factor autoantibodies responsible for mixed cryoglobulinemic vasculitis. By combining single-cell DNA and RNA sequencing with serum antibody peptide sequencing and antibody synthesis, rare circulating B lymphocytes making pathogenic autoantibodies were found to comprise clonal trees accumulating mutations. Lymphoma driver mutations in genes regulating B cell proliferation and V(D)J mutation (CARD11, TNFAIP3, CCND3, ID3, BTG2, and KLHL6) were present in rogue B cells producing the pathogenic autoantibody. Antibody V(D)J mutations conferred pathogenicity by causing the antigen-bound autoantibodies to undergo phase transition to insoluble aggregates at lower temperatures. These results reveal a pre-neoplastic stage in human lymphomagenesis and a cascade of somatic mutations leading to an iconic pathogenic autoantibody.

Overexpression of tripartite motif containing 26 inhibits non-small cell lung cancer cell growth by suppressing PI3K/AKT signaling

It has been reported that tripartite motif containing 26 (TRIM26) is involved in the tumorigenesis of some cancers, but its function in non-small cell lung cancer (NSCLC) is still unclear. In this study, we found that TRIM26 was markedly down-regulated in both of NSCLC tumor tissues and cell lines. Additionally, high expression of TRIM26 in NSCLC patients predicted a positive index for patients' overall survival. What is more, overexpression of TRIM26 significantly suppressed NSCLC cell growth. Our further studies indicated that overexpression of TRIM26 inhibited the phosphorylation of PI3K p85 and AKT. And overexpressed TRIM26 regulated cell cycle-related genes' expression, including downregulating CDK4, Cyclin A, Cyclin D1, Cyclin D3, and Cyclin E, and upregulating p27 expression. Finally, we found that TRIM26 up-regulated PTEN expression by stabilizing PTEN protein in NSCLC cells. Collectively, our present study indicated that TRIM26 was decreased in NSCLC and overexpression of TRIM26 inhibited NSCLC cell growth by suppressing PI3K/AKT pathway, which suggested that TRIM26 could be as a potential target for the treatment of NSCLC in the future.

RUNX3 Promotes the Tumorigenic Phenotype in KGN, a Human Granulosa Cell Tumor-Derived Cell Line

Granulosa cell tumors of the ovary (GCT) are the predominant type of ovarian sex cord/stromal tumor. Although prognosis is generally favorable, the outcome for advanced and recurrent GCT is poor. A better understanding of the molecular pathogenesis of GCT is critical to developing effective therapeutic strategies. Here we have examined the potential role of the runt-related transcription factor RUNX3. There are only two GCT cell lines available. While RUNX3 is silenced in the GCT cell line KGN cells, it is highly expressed in another GCT cell line, COV434 cells. Re-expression of RUNX3 promotes proliferation, anchorage-independent growth, and motility in KGN cells in vitro and tumor formation in mice in vivo. Furthermore, expression of a dominant negative form of RUNX3 decreases proliferation of COV434 cells. To address a potential mechanism of action, we examined expression of cyclin D2 and the CDK inhibitor p27^Kip1, two cell cycle regulators known to be critical determinants of GCT cell proliferation. We found that RUNX3 upregulates the expression of cyclin D2 at the mRNA and protein level, and decreases the level of the p27^Kip1 protein, but not p27^Kip1 mRNA. In conclusion, we demonstrate that RUNX proteins are expressed in GCT cell lines and human GCT specimens, albeit at variable levels, and RUNX3 may play an oncogenic role in a subset of GCTs.

Arabidopsis Leaf Flatness Is Regulated by PPD2 and NINJA through Repression of CYCLIN D3 Genes

In Arabidopsis (Arabidopsis thaliana), reduced expression of the transcriptional regulator PEAPOD2 (PPD2) results in propeller-like rosettes with enlarged and dome-shaped leaves. However, the molecular and cellular processes underlying this peculiar phenotype remain elusive. Here, we studied the interaction between PPD2 and NOVEL INTERACTOR OF JAZ (NINJA) and demonstrated that ninja loss-of-function plants produce rosettes with dome-shaped leaves similar to those of ppd mutants but without the increase in size. We showed that ninja mutants have a convex-shaped primary cell cycle arrest front, putatively leading to excessive cell division in the central leaf blade region. Furthermore, ppd and ninja mutants have a similar increase in the expression of CYCLIN D3;2 (CYCD3;2), and ectopic overexpression of CYCD3;2 phenocopies the ppd and ninja rosette and leaf shape phenotypes without affecting the size. Our results reveal a pivotal contribution of NINJA in leaf development, in addition to its well-studied function in jasmonate signaling, and imply a new function for D3-type cyclins in, at least partially, uncoupling the size and shape phenotypes of ppd leaves.

The miR-15 family reinforces the transition from proliferation to differentiation in pre-B cells

Precursor B lymphocytes expand upon expression of a pre-B cell receptor (pre-BCR), but then transit into a resting state in which immunoglobulin light chain gene recombination is initiated. This bi-phasic sequence is orchestrated by the IL-7 receptor (IL-7R) and pre-BCR signaling, respectively, but little is known about microRNAs fine-tuning these events. Here, we show that pre-B cells lacking miR-15 family functions exhibit prolonged proliferation due to aberrant expression of the target genes cyclin E1 and D3. As a consequence, they fail to trigger the transcriptional reprogramming normally accompanying their differentiation, resulting in a developmental block at the pre-B cell stage. Intriguingly, our data indicate that the miR-15 family is suppressed by both IL-7R and pre-BCR signaling, suggesting it is actively integrated into the regulatory circuits of developing B cells. These findings identify the miR-15 family as a novel element required to promote the switch from pre-B cell proliferation to differentiation.

PLC-β1 and cell differentiation: An insight into myogenesis and osteogenesis

Phosphoinositide-phospholipase C-β1 (PLC-β1) plays a crucial role in the initiation of the genetic program responsible for muscle differentiation and osteogenesis. During myogenic differentiation of murine C2C12 myoblasts, PLC-β1 signaling pathway involves the Inositol Polyphosphate Multikinase (IPMK) and β-catenin as downstream effectors. By means of c-jun binding to cyclin D3 promoter, the activation of PLC-β1 pathway determines cyclin D3 accumulation. However, osteogenesis requires PLC-β1 expression and up-regulation but it does not affect cyclin D3 levels, suggesting that the two processes require the activation of different mediators.

Modulation of nuclear PI-PLCbeta1 during cell differentiation

PI-PLCbeta1 plays an important role in cell differentiation, and particularly in myogenesis, osteogenesis and hematopoiesis. Indeed, the increase of PI-PLCbeta1, along with Cyclin D3, has been detected in C2C12 mouse myoblasts induced to differentiate, as well as in human cells obtained from myotonic dystrophy. Also in the case of osteogenic differentiation there is a specific induction of PI-PLCbeta1, but in this case the role of PI-PLCbeta1 seems to be independent from Cyclin D3, so that a different mechanism could be involved. As for the hematopoietic system, PI-PLCbeta1 has a peculiar behavior: it increases during myeloid differentiation and decreases during erythroid differentiation, thus confirming the role of PI-PLCbeta1 as a modulator of hematopoiesis.

IMPORTANCE OF APOPTOSIS MARKERS (MDM2, BCL-2 AND Bax) IN BENIGN PROSTATIC HYPERPLASIA AND PROSTATE CANCER

MDM2, Bcl-2 and Bax are well recognized markers of apoptosis. The goal of the current study was evaluation of the activity of these markers in different cells of BPH, PCa and hormonally treated prostate cancer (CRPCa) tissues. Activity of the markers has been evaluated in: 39 BPH, 28 prostate cancer (PCa) and 10 castration resistant PCa (CRPCa) tissues. Possible association of intensity of the expression with the disease clinical parameters has been assessed. Activity of MDM2 was higher in PCa and CRPCa as compared with BPH. This difference has been detected in epithelial and vascular prostatic cells. Epithelial activity of Bcl-2 was significantly lower in BPH as compared with PCa and CRPCa. Conversely, intensity of pro-apoptotic protein Bax was significantly higher in PBH than in PCa and CRPCa. The Bax activity in acinar and ductal cells of BPH was positively correlated with age. Intensity of Bcl-2 was significantly increasing, while activity of Bax was decreasing with increasing prostate volume. Significant correlation has been detected with the markers' activity and residual urine. In particular, MDM2 activity was increasing while epithelial activity of Bax was decreasing with increasing residual urine. Serum PSA level was positively correlated with MDM2 and negatively correlated with Bax activity. p27(Kip1) cell cycle inhibitor was positively correlated with Bax but negatively correlated with Bcl-2 activities. Proliferation marker Ki67 was positively correlated with MDM2 and Bcl-2. With increasing Ki67, Bax activity was significantly decreasing. Cyclin D3 was positively correlated with Bax. This pilot study has shown importance of apoptosis markers in BPH and PCa. It is the first study showing complex interrelation between apoptosis and cell cycle regulating proteins in BPH and PCa.

A Repressor Protein Complex Regulates Leaf Growth in Arabidopsis

Cell number is an important determinant of final organ size. In the leaf, a large proportion of cells are derived from the stomatal lineage. Meristemoids, which are stem cell-like precursor cells, undergo asymmetric divisions, generating several pavement cells adjacent to the two guard cells. However, the mechanism controlling the asymmetric divisions of these stem cells prior to differentiation is not well understood. Here, we characterized PEAPOD (PPD) proteins, the only transcriptional regulators known to negatively regulate meristemoid division. PPD proteins interact with KIX8 and KIX9, which act as adaptor proteins for the corepressor TOPLESS. D3-type cyclin encoding genes were identified among direct targets of PPD2, being negatively regulated by PPDs and KIX8/9. Accordingly, kix8 kix9 mutants phenocopied PPD loss-of-function producing larger leaves resulting from increased meristemoid amplifying divisions. The identified conserved complex might be specific for leaf growth in the second dimension, since it is not present in Poaceae (grasses), which also lack the developmental program it controls.

Induction of G1 Arrest by SB265610 Involves Cyclin D3 Down-regulation and Suppression of CDK2 (Thr160) Phosphorylation

BACKGROUND/AIM

The current study investigated the mechanisms underlying the antitumor activity of SB265610, a cysteine-amino acid-cysteine (CXC) chemokines receptor 2 (CXCR2) antagonist.

MATERIALS AND METHODS

Cell-cycle progression and regulatory molecules were assessed by flow cytometry, immunoblotting, real-time PCR and immunoprecipitation. Target validation was achieved via RNA interference.

RESULTS

G1 arrest induced by SB265610 occurred at concentrations lacking CXCR2 selectivity, persisted upon interleukin 8 (IL8) challenge, and did not affect IL8 downstream target expression. Profiling of G1 regulators revealed cyclin-dependent kinase 2 (CDK2) (Thr160) hypophosphorylation, cyclin D3 gene down-regulation, and p21 post-translational induction. However, only cyclin D3 and CDK2 contributed towards G1 arrest. Furthermore, SB265610 induced a sustained phosphorylation of the p38MAPK. Pharmacological interference with p38MAPK significantly abrogated SB265610-induced G1 arrest and normalized the expression of cyclin D3, with restoration of its exclusive binding to CDK6, but with weak recovery of CDK2 (Thr160) hypo-phosphorylation.

CONCLUSION

The present study described the mechanisms for the anti-proliferative activity of SB265610 which may be of value in IL8-rich tumor microenvironments.

Actions of 1,25(OH)2-vitamin D3 on the cellular cycle depend on VDR and p38 MAPK in skeletal muscle cells

Previously, we have reported that 1,25(OH)2-vitamin D3 (1,25D) activates p38 MAPK (p38) in a vitamin D receptor (VDR)-dependent manner in proliferative C2C12 myoblast cells. It was also demonstrated that 1,25D promotes muscle cell proliferation and differentiation. However, we did not study these hormone actions in depth. In this study we have investigated whether the VDR and p38 participate in the signaling mechanism triggered by 1,25D. In C2C12 cells, the VDR was knocked down by a shRNA, and p38 was specifically inhibited using SB-203580. Results from cell cycle studies indicated that hormone stimulation prompts a peak of S-phase followed by an arrest in the G0/G1-phase, events which were dependent on VDR and p38. Moreover, 1,25D increases the expression of cyclin D3 and the cyclin-dependent kinase inhibitors, p21(Waf1/Cip1) and p27(Kip1), while cyclin D1 protein levels did not change during G0/G1 arrest. In all these events, p38 and VDR were required. At the same time, a 1,25D-dependent acute increase in myogenin expression was observed, indicating that the G0/G1 arrest of cells is a pro-differentiative event. Immunocytochemical assays revealed co-localization of VDR and cyclin D3, promoted by 1,25D in a p38-dependent manner. When cyclin D3 expression was silenced, VDR and myogenin levels were downregulated, indicating that cyclin D3 was required for 1,25D-induced VDR expression and the concomitant entrance into the differentiation process. In conclusion, the VDR and p38 are involved in control of the cellular cycle by 1,25D in skeletal muscle cells, providing key information on the mechanisms underlying hormone regulation of myogenesis.

Reduced expression of the retinoblastoma protein shows that the related signaling pathway is essential for mediating the antineoplastic activity of erufosine

Erufosine is a new antineoplastic agent of the group of alkylphosphocholines, which interferes with signal transduction and induces apoptosis in various leukemic and tumor cell lines. The present study was designed to examine for the first time the mechanism of resistance to erufosine in malignant cells with permanently reduced expression of the retinoblastoma (Rb) protein. Bearing in mind the high number of malignancies with reduced level of this tumor-suppressor, this investigation was deemed important for using erufosine, alone or in combination, in patients with compromised RB1 gene expression. For this purpose, clones of the leukemic T-cell line SKW-3 were used, which had been engineered to constantly express differently low Rb levels. The alkylphosphocholine induced apoptosis, stimulated the expression of the cyclin dependent kinase inhibitor p27^Kip1 and inhibited the synthesis of cyclin D3, thereby causing a G₂ phase cell cycle arrest and death of cells with wild type Rb expression. In contrast, Rb-deficiency impeded the changes induced by eru-fosine in the expression of these proteins and abrogated the induction of G₂ arrest, which was correlated with reduced antiproliferative and anticlonogenic activities of the compound. In conclusion, analysis of our results showed for the first time that the Rb signaling pathway is essential for mediating the antineoplastic activity of erufosine and its efficacy in patients with malignant diseases may be predicted by determining the Rb status.

Requirement for A-type cyclin-dependent kinase and cyclins for the terminal division in the stomatal lineage of Arabidopsis

The Arabidopsis stoma is a specialized epidermal valve made up of a pair of guard cells around a pore whose aperture controls gas exchange between the shoot and atmosphere. Guard cells (GCs) are produced by a symmetric division of guard mother cells (GMCs). The R2R3-MYB transcription factor FOUR LIPS (FLP) and its paralogue MYB88 restrict the division of a GMC to one. Previously, the upstream regions of several core cell cycle genes were identified as the direct targets of FLP/MYB88, including the B-type cyclin-dependent kinase CDKB1;1 and A2-type cyclin CYCA2;3. Here we show that CDKA;1 is also an immediate direct target of FLP/MYB88 through the binding to cis-regulatory elements in the CDKA;1 promoter region. CDKA;1 activity is required not only for normal GMC divisions but also for the excessive cell overproliferation in flp myb88 mutant GMCs. The impaired defects of GMC division in cdkb1;1 1;2 mutants could be partially rescued by a stage-specific expression of CDKA;1. Although targeted overexpression of CDKA;1 does not affect stomatal development, ectopic expression of the D3-type cyclin CYCD3;2 induces GC subdivision, resulting in a stoma with 3-4 GCs instead of the normal two. Co-overexpression of CDKA;1 with CYCD3;2, but not with CYCA2;3, confers a synergistic effect with respect to GC subdivision. Thus, in addition to a role in stomatal formative asymmetric divisions at early developmental stages, CDKA;1 is needed in triggering GMC symmetric divisions at the late stage of stomatal development. However, timely down-regulation of CDKA;1-CYCD3 activity is required for restriction of GC proliferation.

Cadmium mimics estrogen-driven cell proliferation and prolactin secretion from anterior pituitary cells

Cadmium (Cd) is a heavy metal of considerable occupational and environmental concern affecting wildlife and human health. Recent studies indicate that Cd, like other heavy metals, can mimic effects of 17β-estradiol (E2) involving E2 receptor (ER) activation. Lactotrophs, the most abundant cell type in anterior pituitary gland, are the main target of E2, which stimulates cell proliferation and increases prolactin secretion through ERα. The aim of this work was to examine whether Cd at nanomolar concentrations can induce cell proliferation and prolactin release in anterior pituitary cells in culture and whether these effects are mediated through ERs. Here we show that 10 nM Cd was able to stimulate lactotroph proliferation in anterior pituitary cell cultures from female Wistar rats and also in GH3 lactosomatotroph cell line. Proliferation of somatotrophs and gonadotrophs were not affected by Cd exposure. Cd promoted cell cycle progression by increasing cyclins D1, D3 and c-fos expression. Cd enhanced prolactin synthesis and secretion. Cd E2-like effects were blocked by the pure ERs antagonist ICI 182,780 supporting that Cd acts through ERs. Further, both Cd and E2 augmented full-length ERαexpression and its 46 kDa-splicing variant. In addition, when co-incubated Cd was shown to interact with E2 by inducing ERα mRNA expression which indicates an additive effect between them. This study shows for the first time that Cd at nanomolar concentration displays xenoestrogenic activities by inducing cell growth and stimulating prolactin secretion from anterior pituitary cells in an ERs-dependent manner. Cd acting as a potent xenoestrogen can play a key role in the aetiology of different pathologies of the anterior pituitary and in estrogen-responsive tissues which represent considerable risk to human health.

Notch1 signaling regulates the proliferation and self-renewal of human dental follicle cells by modulating the G1/S phase transition and telomerase activity

Multipotent human dental follicle cells (HDFCs) have been intensively studied in periodontal regeneration research, yet the role of Notch1 in HDFCs has not been fully understood. The aim of the current study is to explore the role of Notch1 signaling in HDFCs self-renewal and proliferation. HDFCs were obtained from the extracted wisdom teeth from adolescent patients. Regulation of Notch1 signaling in the HDFCs was achieved by overexpressing the exogenous intracellular domain of Notch1 (ICN1) or silencing Notch1 by shRNA. The regulatory effects of Notch1 on HDFC proliferation, cell cycle distribution and the expression of cell cycle regulators were investigated through various molecular technologies, including plasmid construction, retrovirus preparation and infection, qRT-PCR, western blot, RBP-Jk luciferase reporter and cell proliferation assay. Our data clearly show that constitutively activation of Notch1 stimulates the HDFCs proliferation while inhibition of the Notch1 suppresses their proliferation in vitro. In addition, the HDFCs proliferation is associated with the increased expression of cell cycle regulators, e.g. cyclin D1, cyclin D2, cyclin D3, cyclin E1, CDK2, CDK4, CDK6, and SKP2 and the decreased expression of p27 (kip1). Moreover, our data show that the G1/S phase transition (indicating proliferation) and telomerase activity (indicating self-renewal) can be enhanced by overexpression of ICN1 but halted by inhibition of Notch1. Together, the current study provides evidence for the first time that Notch1 signaling regulates the proliferation and self-renewal capacity of HDFCs through modulation of the G1/S phase transition and the telomerase activity.

Fluorescence in situ hybridization analysis of CCND3 gene as marker of progression in bladder carcinoma

The aim of this study was to assess patterns of CCND3 gene amplification in bladder cancer and correlate gene status with recurrence-free and progression-free survival. A sequential cohort series of 102 primary bladder tumor samples in which there was enough tissue material to assess CCND3 gene status by fluorescent in situ hybridization (FISH) was the study group. CCND3 gene FISH amplification present in 31.4 percent of bladder carcinomas, was related to tumor progression (p=0.021) and lower time to progression (mean+-SD; 25.75+-15.25 months) as compared to 33.29+-11.0 months in the CCND3 not amplified group (p=0.05). By immunohistochemistry, Cyclin D3 labeling index was higher in the CCND3 amplified group (mean+-SD, 76.69+-27.51) than in not amplified (mean+-SD, 21.57+-7.02) (p less than 0.0001). The univariate survival analysis showed CCND3 gene amplification to be associated to a shorter progression-free survival (p=0.020) together with WHO histological grade (p=0.001) and pT stage category (p less than 0.0001). Cox’s regression analysis selected CCND3 amplification as an independent predictor of progression-free survival (p= 0.030, RR3.561, 95 percent CI 1.128-11.236) together with pT category (p less than 0.0001, RR5.834, 95 percent CI 2.364-14.395). Our FISH analysis suggests that CCND3 gene amplification is a marker of aggressiveness and might be a predictor of tumor progression in bladder urothelial carcinoma.

Overexpression of cyclin D3 improves decidualization defects in Hoxa-10(-/-) mice

Uterine decidualization, a crucial process for implantation, is a tightly regulated process encompassing proliferation, differentiation, and polyploidization of uterine stromal cells. Hoxa (Homeobox A)-10, a homeobox transcription factor, is highly expressed in decidualizing stromal cells. Targeted gene deletion experiments have demonstrated marked infertility resulting from severely compromised decidualization in Hoxa-10(-/-) mice. However, the underlying mechanism by which Hoxa-10 regulates stromal cell differentiation remains poorly understood. Cyclin D3, a G(1) phase cell-cycle regulatory protein involved in stromal cell proliferation and decidualization, is significantly reduced in Hoxa-10(-/-) mice. The expression of cyclin D3 in the pregnant mouse uterus parallels stromal cell decidualization. Here, we show that adenovirus-driven cyclin D3 replacement in Hoxa-10(-/-) mice improves stromal cell decidualization. To address our question of whether cyclin D3 replacement in Hoxa-10(-/-) mice can improve decidualization, both in vitro and in vivo studies were completed after the addition of cyclin D3 or empty (control) viral vectors. Immunostaining demonstrated increased proliferation and decidualization in both in vitro and in vivo studies, and in situ hybridization confirmed increased expression of decidualization markers in vivo. Placentation was demonstrated as well in vivo in the cyclin D3-replaced animals. However, fertility was not restored in Hoxa-10(-/-) mice after d 10 of pregnancy. Finally, we identified several downstream targets of cyclin D3 during decidualization in vitro via proteomics experiments, and these were confirmed using in situ hybridization in vivo. Collectively, these results demonstrate that cyclin D3 expression influences a host of genes involved in decidualization and can improve decidualization in Hoxa-10(-/-) mice.

Effect of blue light on endogenous isopentenyladenine and endoreduplication during photomorphogenesis and de-etiolation of tomato (Solanum lycopersicum L.) seedlings

Light is one of the most important factor influencing plant growth and development all through their life cycle. One of the well-known light-regulated processes is de-etiolation, i.e. the switch from skotomorphogenesis to photomorphogenesis. The hormones cytokinins (CKs) play an important role during the establishment of photomorphogenesis as exogenous CKs induced photomorphogenesis of dark-grown seedlings. Most of the studies are conducted on the plant model Arabidopsis, but no or few information are available for important crop species, such as tomato (Solanum lycopersicum L.). In our study, we analyzed for the first time the endogenous CKs content in tomato hypocotyls during skotomorphogenesis, photomorphogenesis and de-etiolation. For this purpose, two tomato genotypes were used: cv. Rutgers (wild-type; WT) and its corresponding mutant (7B-1) affected in its responses to blue light (BL). Using physiological and molecular approaches, we identified that the skotomorphogenesis is characterized by an endoreduplication-mediated cell expansion, which is inhibited upon BL exposure as seen by the accumulation of trancripts encoding CycD3, key regulators of the cell cycle. Our study showed for the first time that iP (isopentenyladenine) is the CK accumulated in the tomato hypocotyl upon BL exposure, suggesting its specific role in photomorphogenesis. This result was supported by physiological experiments and gene expression data. We propose a common model to explain the role and the relationship between CKs, namely iP, and endoreduplication during de-etiolation and photomorphogenesis.

Downregulated miR-195 detected in preeclamptic placenta affects trophoblast cell invasion via modulating ActRIIA expression

Background

Preeclampsia (PE) is a pregnancy-specific syndrome manifested by on-set of hypertension and proteinuria after 20 weeks of gestation. Abnormal placenta development has been generally accepted as initial cause of the disorder. Recently, miR-195 was found to be down-regulated in preeclamptic placentas compared with normal pregnant ones, indicating possible association of this small molecule with placental pathology of preeclampsia. By far the function of miR-195 in the development of placenta remains unknown.

Methodology/Principal Findings

Bioinformatic assay predicted ActRIIA as one of the targets for miR-195. By using Real-time PCR, Western blotting and Dual Luciferase Assay, we validated that ActRIIA was the direct target of miR-195 in human trophoblast cells. Transwell insert invasion assay showed that miR-195 could promote cell invasion in trophoblast cell line, HTR8/SVneo cells, and the effect could be abrogated by overexpressed ActRIIA. In preeclamptic placenta tissues, pri-miR-195 and mature miR-195 expressions were down-regulated, whereas ActRIIA level appeared to be increased when compared with that in gestational-week-matched normal placentas.

Conclusions/Significance

This is the first report on the function of miR-195 in human placental trophoblast cells which reveals an invasion-promoting effect of the small RNA via repressing ActRIIA. Aberrant expression of miR-195 may contribute to the occurrence of preeclampsia through interfering with Activin/Nodal signaling mediated by ActRIIA in human placenta.

Cyclin D3 is selectively required for proliferative expansion of germinal center B cells

The generation of robust T-cell-dependent humoral immune responses requires the formation and expansion of germinal center structures within the follicular regions of the secondary lymphoid tissues. B-cell proliferation in the germinal center drives ongoing antigen-dependent selection and the generation of high-affinity class-switched plasma and memory B cells. However, the mechanisms regulating B-cell proliferation within this microenvironment are largely unknown. Here, we report that cyclin D3 is uniquely required for germinal center progression. Ccnd3(-/-) mice exhibit a B-cell-intrinsic defect in germinal center maturation and fail to generate an affinity-matured IgG response. We determined that the defect resulted from failed proliferative expansion of GL7(+) IgD(-) PNA(+) B cells. Mechanistically, sustained expression of cyclin D3 was found to be regulated at the level of protein stability and controlled by glycogen synthase kinase 3 in a cyclic AMP-protein kinase A-dependent manner. The specific defect in proliferative expansion of GL7(+) IgD(-) PNA(+) B cells in Ccnd3(-/-) mice defines an underappreciated step in germinal center progression and solidifies a role for cyclin D3 in the immune response, and as a potential therapeutic target for germinal center-derived B-cell malignancies.

In CD28-costimulated human naïve CD4+ T cells, I-κB kinase controls the expression of cell cycle regulatory proteins via interleukin-2-independent mechanisms

Stimulation of naïve CD4(+) T cells through engagement of the T-cell receptor (TCR) and the CD28 co-receptor initiates cell proliferation which critically depends on interleukin (IL)-2 secretion and subsequent autocrine signalling via the IL-2 receptor. However, several studies indicate that in CD28-costimulated T cells additional IL-2-independent signals are also required for cell proliferation. In this study, using a neutralizing anti-human IL-2 antibody and two selective, structurally unrelated, cell-permeable I-κB kinase (IKK) inhibitors, BMS-345541 and PS-1145, we show that in human naïve CD4(+) T cells stimulated through a short engagement of the TCR and the CD28 co-receptor, IKK controls the expression of the cell cycle regulatory proteins cyclin D3, cyclin E and cyclin-dependent kinase 2 (CDK2) and the stability of the F-box protein S-phase kinase-associated protein 2 (SKP2) and its co-factor CDC28 protein kinase regulatory subunit 1B (CKS1B), through IL-2-independent mechanisms.

Role of the high mobility group A proteins in the regulation of pituitary cell cycle

Pituitary cells are particularly sensitive to alterations of the cell cycle machinery. In fact, mutations affecting expression of proteins critical for cell cycle progression, including retinoblastoma protein, cyclins D1 and D3, p16(INK4A), and p27(kip1), are frequent in human pituitary adenomas. Similarly, both targeted disruption and overexpression of either cell cycle inhibitors or activators, respectively, lead to the development of pituitary adenomas in mice. Recent evidence has added the high mobility group A (HMGA) proteins as a new class of cell cycle regulators that play significant roles in the pathways that lead to pituitary tumor evolution in both humans and experimental animal models. Here, we first review the role of the cell cycle in pituitary tumorigenesis, as witnessed by human pathology and transgenic mice; and then, we focus on HMGA proteins and their cell cycle-related role in pituitary tumorigenesis.

Transcriptional targets for pituitary tumor-transforming gene-1

Pituitary tumor-transforming gene-1 (PTTG1) is a transforming gene first discovered in rat pituitary tumor cells. It possesses transcriptional activity and also has securin functions. Chromatin immunoprecipitation-on-chip study reveals that PTTG1 is a global transcription factor, which exerts its transcriptional activity either by directly binding to DNA or by interacting with proteins including PTTG1 binding factor, p53, Sp1, and upstream stimulatory factor 1. PTTG1 has several validated transcriptional targets that are involved in different cellular processes. PTTG1 activates c-Myc in NIH 3T3 cells, suggesting a role in cell transformation. PTTG1 induces fibroblast growth factor 2 expression and promotes tumor angiogenesis.It binds to and inhibits p53 transcriptional activity. PTTG1 activates cyclin D3 and represses p21 expression, indicating a role in cell cycle regulation and cell senescence. Here, we review PTTG1 transcriptional targets and their functions.

[Effect of betulinic acid on proliferation and apoptosis in Jurkat cells and its mechanism]

OBJECTIVE

To investigate the anticancer effects of betulinic acid (BA) on Jurkat cells in vitro and its molecular mechanism.

METHODS

The effects of betulinic acid on the growth of Jurkat cells were studied by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5diphenyl-2H-tetrazolium (MTT) assay. Apoptosis was assessed by Hoechst33258 staining and annexin-V/PI double-labeled cytometry. The effect of betulinic acid on the cell cycle of Jurkat cells was studied by propidium iodide staining. RT-PCR and Western blot were used to analyze the changes of cyclin D3, bcl-xl mRNA and protein levels in Jurkat cells after treatment with betulinic acid.

RESULTS

The proliferation of Jurkat cells was decreased in betulinic acid-treated group at a 24 h IC50 value of 70.0 micromol/L. The effect of betulinic acid to induce apoptosis in Jurkat cells was in a time- and dose-dependent manner. Jurkat cells treated with betulinic acid showed an increase of G0/G1 phase and decrease of S phase. The Jurkat cells treated with 0, 20, 60, 100 micromol/L betulinic acid for 24 h, showed an increased G0/G1 phase from 31.0% to 58.8%, whereas decreased S phase from 61.5% to 35.8%, respectively. PBMC was less sensitive to the cytotoxic effect of betulinic acid than Jurkat cells. The expression of cyclin D3, bcl-xl mRNA and protein were decreased sharply in Jurkat cells treated with betulinic acid.

CONCLUSION

Betulinic acid can inhibit the proliferation of Jurkat cells by regulating the cell cycle that arrests cells at G0/G1 phase and induces apoptosis in Jurkat cells. The antitumor effects of betulinic acid may be related to down-regulation of the expression of cyclin D3 and bcl-xl.

[Clinicopathologic significance of bcl-6 gene rearrangement and expression in three molecular subgroups of diffuse large B-cell lymphoma]

OBJECTIVE

To investigate the role of bcl-6 gene rearrangement and bcl-6 expression in three molecular subgroups of diffuse large B-cell lymphoma (DLBCL) and its clinicopathological significance.

METHODS

Tissue microarray including 163 newly diagnosed DLBCL was constructed. Fluorescence in situ hybridization (FISH) was performed to detect the bcl-6 gene rearrangement and immunohistochemistry (EnVision method) was used to evaluate the expression of bcl-6, Ki-67, cyclin D3, Geminin and P27(Kip1) proteins in DLBCL. The association with clinicopathological features was analyzed.

RESULTS

One hundred and forty nine of 163 cases were further classified into three molecular subgroups: 40 cases of germinal center B-cell-like (GCB) type, 75 cases of activated non-germinal center B-cell-like (ABC) type, 34 cases of Type 3. Of these 149 cases, FISH for bcl-6 gene rearrangement was successful in 118 cases. bcl-6 gene rearrangement was observed in 33 of 118 (28.0%) cases. The bcl-6 gene rearrangement was more frequently seen in the ABC subgroup (22/62, 35.5%) than in GCB (6/31, 19.4%) and Type 3 subgroups (5/25, 20.0%, P=0.16). The correlation of bcl-6 gene rearrangement and expression of its encoded protein was further analyzed. Most of DLBCL (26/33, 78.8%) with bcl-6 gene rearrangement presented with overexpression of its encoded protein, which was higher than those without bcl-6 gene rearrangement (53/84, 62.4%, P=0.088). DLBCL with bcl-6 gene rearrangement (24/33, 72.7%) more frequently expressed cyclin D3, and had a higher proliferative activity than those without bcl-6 gene rearrangement (37/81, 45.7% , P=0.009). Twenty-nine of 33 (87.9%) cases of DLBCL with bcl-6 gene rearrangement presented with advanced stage (Ann Arbor stage III/IV), which was higher than those without bcl-6 gene rearrangement (65/85, 76.5% , P=0.167). Univariate Cox proportional hazards regression analysis showed that bcl-6 gene rearrangement was associated with an increased relative risk (at 1.842) of death in DLBCL cases compared with those without bcl-6 gene rearrangement.

CONCLUSION

Overexpression of bcl-6 protein caused by bcl-6 gene rearrangement may play some important roles in the development and/or progression of a subset of DLBCL.