Nutrient-Dependent Endocycling in Steroidogenic Tissue Dictates Timing of Metamorphosis in Drosophila melanogaster

Many animals have an intrinsic growth checkpoint during juvenile development, after which an irreversible decision is made to upregulate steroidogenesis, triggering the metamorphic juvenile-to-adult transition. However, a molecular process underlying such a critical developmental decision remains obscure. Here we show that nutrient-dependent endocycling in steroidogenic cells provides the machinery necessary for irreversible activation of metamorphosis in Drosophila melanogaster. Endocycle progression in cells of the prothoracic gland (PG) is tightly coupled with the growth checkpoint, and block of endocycle in PG cells causes larval developmental arrest due to reduction in biosynthesis of the steroid hormone ecdysone. Moreover, inhibition of the nutrient sensor target of rapamycin (TOR) in the PG during the checkpoint period causes endocycle inhibition and developmental arrest, which can be rescued by inducing additional rounds of endocycles by Cyclin E. We propose that a TOR-mediated cell cycle checkpoint in steroidogenic tissue provides a systemic growth checkpoint for reproductive maturation.

Onset of sexual maturation constitutes a point of no return in animals; once this life-changing decision is made, upregulation of steroidogenesis leads to irreversible juvenile-to-adult transition in humans and insects alike. While nutrient signals contributing to this decision-making process have been well studied, molecular events that ultimately determine its precise timing remain a mystery. We report here that nutrient-dependent endoreplication, the replication of genomic DNA without cell division, in steroidogenic cells functions as an intrinsic timer, whereby degree of polyploidy sets the timing of reproductive maturation (i.e. metamorphosis) in fruit flies. The cumulative and irreversible nature of endoreplication thus provides an intrinsic molecular machinery underlying the irreversible decision-making process, which may be widely leveraged as a fundamental developmental timing mechanism.

Analysis of expression of cyclin E, p27kip1 and Ki67 protein in colorectal cancer tissues and its value for diagnosis, treatment and prognosis of disease

OBJECTIVE

We conducted this study is to investigate the clinical application value of Cyclin E, p27kip1 and Ki67 protein expression in colorectal cancer tissues for diagnosis, treatment, and prognosis of this disease.

PATIENTS AND METHODS

The positive expression of Cyclin E, p27kip1 and Ki-67 in tissues of 200 patients with colorectal cancer and 200 patients with benign colorectal tumor or inflammation were detected by immunohistochemistry PowerVision two-step method. RT-PCR was used to detect the expression level of the corresponding mRNA, as well as to analyze the association with TNM staging, pathology type, free progression survival and median survival. The sensitivity, specificity, and accuracy of diagnosis were analyzed by ROC.

RESULTS

The positive expression rate and positive degree of Cyclin E and Ki-67 of observation group were higher than those of the control group, while positive expression rate and positive degree of p27kipl was lower than that of the control group; the differences were statistically significant (p<0.05). The quantitative expression levels of Cyclin E and Ki-67 mRNA of observation group were distinctly higher than those of the control group, while p27kipl was evidently lower than that of the control group; the differences were statistically significant (p<0.05). With the increase of TNM staging, the positive expression of Cyclin E and Ki-67 increased, p27kipl decreased, and the difference was statistically significant (p<0.05). With the decrease of differentiation degree, the positive expression of Cyclin E and Ki-67 increased, p27kipl decreased, and the difference was statistically significant (p<0.05). The free progression survival and median survival of positive expression and negative expression of Cyclin E and Ki-67 were shortened, p27kipl extended, and the difference was statistically significant (p<0.05). The diagnostic sensitivity of Cyclin E mRNA was 89.6%, specificity 84.5%, accuracy 0.823 and the critical value was 0.3562; The diagnostic sensitivity of p27kipl mRNA was 80.5%, specificity 76.5%, accuracy 0.802 and the critical value was 0.3023. The diagnostic sensitivity of Ki-67 mRNA was 86.5%, specificity 82.9%, accuracy 0.814 and the critical value was 0.3243.

CONCLUSIONS

We discovered that Cyclin E and Ki67 protein expression of colorectal cancer tissues was upregulated and p27kipl protein expression was downregulated, which were closely related to the TNM and pathological differentiation degree. These values were also closely associated with free progression survival and median survival of prognosis. Therefore, the above indexes can be used as highly sensitive, specific and accurate markers for the diagnosis of colorectal cancer.

Altered regulation of the Spry2/Dyrk1A/PP2A triad by homocysteine impairs neural progenitor cell proliferation

Hyperhomocysteinemia reduces neurogenesis in the adult mouse brain. Homocysteine (Hcy) inhibits postnatal neural progenitor cell (NPC) proliferation by specifically impairing the fibroblast growth factor receptor (FGFR)-Erk1/2-cyclin E signaling pathway. We demonstrate herein that the inhibition of FGFR-dependent NPC proliferation induced by Hcy is mediated by its capacity to alter the cellular methylation potential. Our results show that this alteration modified the expression pattern and activity of Sprouty2 (Spry2), a negative regulator of the above mentioned pathway. Both elevated concentrations of Hcy and methyltransferase activity inhibition induced Spry2 promoter demethylation in NPC cultures leading to a sustained upregulation of the expression of Spry2 mRNA and protein. In addition, protein levels of two kinases responsible for Spry2 activation/deactivation were altered by Hcy: Spry2 kinase Dyrk1A levels diminished while Spry2 phosphatase PP2A increased, leading to changes in the phosphorylation pattern, activity and stability of Spry2. In conclusion, Hcy inhibits NPC proliferation by indirect mechanisms involving alterations in DNA methylation, gene expression, and Spry2 function, causing FGFR signaling impairment.

Bisdemethoxycurcumin-induced S phase arrest through the inhibition of cyclin A and E and induction of apoptosis via endoplasmic reticulum stress and mitochondria-dependent pathways in human lung cancer NCI H460 cells

Curcuminoids are the major natural phenolic compounds found in the rhizome of many Curcuma species. Curcuminoids consist of a mixture of curcumin, demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC). Although numerous studies have shown that curcumin induced cell apoptosis in many human cancer cells, however, mechanisms of BDMC-inhibited cell growth and -induced apoptosis in human lung cancer cells still remain unclear. Herein, we investigated the effect of BDMC on the cell death via the cell cycle arrest and induction of apoptosis in NCI H460 human lung cancer cells. Flow cytometry assay was used to measure viable cells, cell cycle distribution, the productions of reactive oxygen species (ROS) and Ca²⁺ , mitochondrial membrane potential (ΔΨ_m ) and caspase-3, -8 and -9 activity. DNA damage and condension were assayed by Comet assay and DAPI staining, respectively. Western blotting was used to measure the changes of cell cycle and apoptosis associated protein expressions. Results indicated that BDMC significantly induced cell death through induced S phase arrest and induced apoptosis. Moreover, DMC induced DNA damage and condension, increased ROS and Ca²⁺ productions and decreased the levels of ΔΨ_m and promoted activities caspase-3, -8, and -9. Western blotting results showed that BDMC inhibited Cdc25A, cyclin A and E for causing S phase arrest, furthermore, promoted the expression of AIF, Endo G and PARP and the levels of Fas ligand (Fas L) and Fas were also up-regulated. Results also indicated that BDMC increased ER stress associated protein expression such as GRP78, GADD153, IRE1α, IRE1β, ATF-6α, ATF-6β, and caspase-4. Taken together, we suggest that BDMC induced cell apoptosis through multiple signal pathways such as extrinsic, intrinsic and ES tress pathway. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1899-1908, 2016.

Proteomic Landscape of Tissue-Specific Cyclin E Functions in Vivo

E-type cyclins (cyclins E1 and E2) are components of the cell cycle machinery that has been conserved from yeast to humans. The major function of E-type cyclins is to drive cell division. It is unknown whether in addition to their 'core' cell cycle functions, E-type cyclins also perform unique tissue-specific roles. Here, we applied high-throughput mass spectrometric analyses of mouse organs to define the repertoire of cyclin E protein partners in vivo. We found that cyclin E interacts with distinct sets of proteins in different compartments. These cyclin E interactors are highly enriched for phosphorylation targets of cyclin E and its catalytic partner, the cyclin-dependent kinase 2 (Cdk2). Among cyclin E interactors we identified several novel tissue-specific substrates of cyclin E-Cdk2 kinase. In proliferating compartments, cyclin E-Cdk2 phosphorylates Lin proteins within the DREAM complex. In the testes, cyclin E-Cdk2 phosphorylates Mybl1 and Dmrtc2, two meiotic transcription factors that represent key regulators of spermatogenesis. In embryonic and adult brains cyclin E interacts with proteins involved in neurogenesis, while in adult brains also with proteins regulating microtubule-based processes and microtubule cytoskeleton. We also used quantitative proteomics to demonstrate re-wiring of the cyclin E interactome upon ablation of Cdk2. This approach can be used to study how protein interactome changes during development or in any pathological state such as aging or cancer.

MiR-639 promoted cell proliferation and cell cycle in human thyroid cancer by suppressing CDKN1A expression

Accumulating evidence has indicated that aberrantly expressed microRNAs (miRs) are extensively involved in cancer development and progression. MiR-639 has been reported to act as tumor promoter in various types of cancer. However, the biological function and underlying molecular mechanism of miR-639 in thyroid carcinoma (TC) have not been intensively investigated. Herein the present study aimed to investigate the functional role of miR-639 in TC. We found that miR-639 expression was upregulated in TC cells and clinical tissues. Overexpression of miR-639 promoted TC cell proliferation and cell cycle, with increased expression of CyclinE and c-myc, whereas miR-639-in reverses the function. Using prediction software and luciferase reporter assay, we found that CDKN1A was a target of miR-639. CDKN1A small interfering RNA (siRNA) abrogated the role of miR-639-in on cell proliferation of TC. In summary, our data demonstrated that miR-639 upregulation was associated with development of TC, miR-639 promoted cell proliferation and cell cycle by targeting CDKN1A in TC.

TIMELESS Suppresses the Accumulation of Aberrant CDC45·MCM2-7·GINS Replicative Helicase Complexes on Human Chromatin

The replication licensing factor CDC6 recruits the MCM2-7 replicative helicase to the replication origin, where MCM2-7 is activated to initiate DNA replication. MCM2-7 is activated by both the CDC7-Dbf4 kinase and cyclin-dependent kinase and via interactions with CDC45 and go-ichi-ni-san complex (GINS) to form the CDC45·MCM2-7·GINS (CMG) helicase complex. TIMELESS (TIM) is important for the subsequent coupling of CMG activity to DNA polymerases for efficient DNA synthesis. However, the mechanism by which TIM regulates CMG activity for proper replication fork progression remains unclear. Here we show that TIM interacts with MCM2-7 prior to the initiation of DNA replication. TIM depletion in various human cell lines results in the accumulation of aberrant CMG helicase complexes on chromatin. Importantly, the presence of these abnormal CMG helicase complexes is not restricted to cells undergoing DNA synthesis. Furthermore, even though these aberrant CMG complexes interact with the DNA polymerases on human chromatin, these complexes are not phosphorylated properly by cyclin-dependent kinase/CDC7-Dbf4 kinase and exhibit reduced DNA unwinding activity. This phenomenon coincides with a significant accumulation of the p27 and p21 replication inhibitors, reduced chromatin association of CDC6 and cyclin E, and a delay in S phase entry. Our results provide the first evidence that TIM is required for the correct chromatin association of the CMG complex to allow efficient DNA replication.

Relationship between cancer mutations and parameter sensitivity in Rb pathway

It has long been known that formation of all sorts of tumors is largely owing to the genomic variations. Oncogenic mutations are often found focused on one or more important pathways which indicate that it is meaningful to investigate oncogenic mutations and oncogenic mechanisms from the point of view of biological network. Recently, we found that in apoptosis pathway of mammalian cell, mutations that cause large variations on the bifurcation point are more probably oncogenic mutations. Here, we used the Rb-E2F pathway in mammalian cell in response to growth factor as another example to verify this correlation. To conduct this study, nonlinear dynamics equations that describe the behavior of the Rb-E2F pathway was first constructed. Then we identified sensitive parameters which have a great influence on the system's bifurcation point. And we found that the sensitive parameters are highly related to high-frequency oncogenic mutations after comparing the results of parameter sensitivity analysis with profile of known cancer mutations. Moreover, the position of bifurcation point rather than concentration of a certain protein is a better measurement to determine biological network's function. Our results further confirm that nonlinear dynamics analysis of biological networks is an important way to understand oncogenesis. And the analysis method can become a powerful tool to understand and analyze the function of biological network.

Role of mesothelin in carbon nanotube-induced carcinogenic transformation of human bronchial epithelial cells

Carbon nanotubes (CNTs) have been likened to asbestos in terms of morphology and toxicity. CNT exposure can lead to pulmonary fibrosis and promotion of tumorigenesis. However, the mechanisms underlying CNT-induced carcinogenesis are not well defined. Mesothelin (MSLN) is overexpressed in many human tumors, including mesotheliomas and pancreatic and ovarian carcinomas. In this study, the role of MSLN in the carcinogenic transformation of human bronchial epithelial cells chronically exposed to single-walled CNT (BSW) was investigated. MSLN overexpression was found in human lung tumors, lung cancer cell lines, and BSW cells. The functional role of MSLN in the BSW cells was then investigated by using stably transfected MSLN knockdown (BSW shMSLN) cells. MSLN knockdown resulted in significantly decreased invasion, migration, colonies on soft agar, and tumor sphere formation. In vivo, BSW shMSLN cells formed smaller primary tumors and less metastases. The mechanism by which MSLN contributes to these more aggressive behaviors was investigated by using ingenuity pathway analysis, which predicted that increased MSLN could induce cyclin E expression. We found that BSW shMSLN cells had decreased cyclin E, and their proliferation rate was reverted to nearly that of untransformed cells. Cell cycle analysis showed that the BSW shMSLN cells had an increased G2 population and a decreased S phase population, which is consistent with the decreased rate of proliferation. Together, our results indicate a novel role of MSLN in the malignant transformation of bronchial epithelial cells following CNT exposure, suggesting its utility as a potential biomarker and drug target for CNT-induced malignancies.

Effects of starvation and hormones on DNA synthesis in silk gland cells of the silkworm, Bombyx mori

Silk gland cells of silkworm larvae undergo multiple cycles of endomitosis for the synthesis of silk proteins during the spinning phase. In this paper, we analyzed the endomitotic DNA synthesis of silk gland cells during larval development, and found that it was a periodic fluctuation, increasing during the vigorous feeding phase and being gradually inhibited in the next molting phase. That means it might be activated by a self-regulating process after molting. The expression levels of cyclin E, cdt1 and pcna were consistent with these developmental changes. Moreover, we further examined whether these changes in endomitotic DNA synthesis resulted from feeding or hormonal stimulation. The results showed that DNA synthesis could be inhibited by starvation and re-activated by re-feeding, and therefore appears to be dependent on nutrition. DNA synthesis was suppressed by in vivo treatment with 20-hydroxyecdysone (20E). However, there was no effect on DNA synthesis by in vitro 20E treatment or by either in vivo or in vitro juvenile hormone treatment. The levels of Akt and 4E-BP phosphorylation in the silk glands were also reduced by starvation and in vivo treatment with 20E. These results indicate that the activation of endomitotic DNA synthesis during the intermolt stages is related to feeding and DNA synthesis is inhibited indirectly by 20E.

Tubeimoside-1 induces oxidative stress-mediated apoptosis and G0/G1 phase arrest in human prostate carcinoma cells in vitro

AIM

Tubeimoside-1 (TBMS1), a triterpenoid saponin extracted from the Chinese herbal medicine Bolbostemma paniculatum (Maxim) Franquet (Cucurbitaceae), has shown anticancer activities in various cancer cell lines. The aim of this study was to investigate the anticancer activity and molecular targets of TBMS1 in human prostate cancer cells in vitro.

METHODS

DU145 and P3 human prostate cancer cells were treated with TBMS1. Cell viability and apoptosis were detected. ROS generation, mitochondrial membrane potential and cell cycle profile were examined. Western blotting was used to measure the expression of relevant proteins in the cells.

RESULTS

TBMS1 (5-100 μmol/L) significantly suppressed the viability of DU145 and P3 cells with IC50 values of approximately 10 and 20 μmol/L, respectively. Furthermore, TBMS1 dose-dependently induced apoptosis and cell cycle arrest at G0/G1 phase in DU145 and P3 cells. In DU145 cells, TBMS1 induced mitochondrial apoptosis, evidenced by ROS generation, mitochondrial dysfunction, endoplasmic reticulum stress, modulated Bcl-2 family protein and cleaved caspase-3, and activated ASK-1 and its downstream targets p38 and JNK. The G0/G1 phase arrest was linked to increased expression of p53 and p21 and decreased expression of cyclin E and cdk2. Co-treatment with Z-VAD-FMK (pan-caspase inhibitor) could attenuate TBMS1-induced apoptosis but did not prevent G0/G1 arrest. Moreover, co-treatment with NAC (ROS scavenger), SB203580 (p38 inhibitor), SP600125 (JNK inhibitor) or salubrinal (ER stress inhibitor) significantly attenuated TBMS1-induced apoptosis.

CONCLUSION

TBMS1 induces oxidative stress-mediated apoptosis in DU145 human prostate cancer cells in vitro via the mitochondrial pathway.

[Insulin combined with selenium inhibit p38MAPK/CBP pathway and suppresses cardiomyocyte apoptosis in rats with diabetic cardiomyopathy]

Objective To investigate the effect of insulin in combination with selenium on p38-mitogen-activated protein kinase/CREB-binding protein (p38MAPK/CBP) pathway in rats with diabetic cardiomyopathy. Methods Fifty SD rats were randomly grouped into control group, diabetic cardiomyopathy (DCM) group, diabetic cardiomyopathy with insulin treatment (DCM-In) group, diabetic cardiomyopathy with selenium treatment (DCM-Se) group, and diabetic cardiomyopathy with insulin and selenium combination treatment (DCM-In-Se) group. Flow cytometry was used to analyze cell cycle. TUNEL staining was used to detect cardiomyocyte apoptosis. Western blotting was used to examine the levels of cyclin D1, cyclin E, Bax, Bcl-2, p38MAPK, p-p38MAPK, CBP and Ku70. Co-immunoprecipitation was used to examine the acetylation status of Ku70. Results Insulin in combination with selenium significantly inhibited cardiomyocyte apoptosis, increased Bcl-2 levels and decreased Bax, cyclin D1, cyclin E, p38MAPK, p-p38MAPK, CBP, Ku70 and acetylated Ku70 levels. Conclusion The combined treatment of insulin and selenium suppresses cardiomyocyte apoptosis by inhibiting p38MAPK/CBP pathway.

Three components of cigarette smoke altered the growth and apoptosis of metastatic colon cancer cells via inducing the synthesis of reactive oxygen species and endoplasmic reticulum stress

Cigarette smoke (CS) is a well-known risk factor for carcinogenesis and has been found to be related to the occurrence and development of colon cancer. In this study, the effect of formaldehyde (FA), benzene (Bz), and isoprene (IP), which are included in main components of CS, on cell viability and apoptosis of SW620 colorectal cancer cells was examined to identify the connection between CS components and colon cancer. In cell viability assay, FA, Bz, and IP decreased cell viability of SW620 cells in a dose dependent manner. In Western blot assay, the protein expression of cell cycle related genes, cyclin D1 & E1, was decreased by FA, Bz, and IP, which corresponded to their inhibitory effect on cell viability. In addition, FA, Bz, and IP increased the protein expression of pro-apoptotic genes, C/EBP homologous protein (CHOP) and Bax, and reduced the protein expression of anti-apoptotic gene, Bcl-2. In reactive oxygen species (ROS) assay using dichlorofluorescin diacetate (DCFH-DA), FA, Bz, and IP increased the ROS production in SW620 cells. In the measurement of apoptotic cells, the numbers of apoptotic cells were increased by the treatment of FA, Bz, and IP. As CHOP is an endoplasmic reticulum (ER)-stress related apoptosis marker of which production is induced by ROS, it was considered that these CS components induce apoptosis of SW620 cells by increasing ROS synthesis and ER-stress. Taken together, these results showed that CS components, i.e., FA, Bz, and IP, inhibited the cell viability of SW620 cells by down-regulating the protein expression of cyclin D1 & E1 and induced apoptosis of SW620 cells by increasing ROS production and simultaneously activating ER-stress.

Control of Neural Daughter Cell Proliferation by Multi-level Notch/Su(H)/E(spl)-HLH Signaling

The Notch pathway controls proliferation during development and in adulthood, and is frequently affected in many disorders. However, the genetic sensitivity and multi-layered transcriptional properties of the Notch pathway has made its molecular decoding challenging. Here, we address the complexity of Notch signaling with respect to proliferation, using the developing Drosophila CNS as model. We find that a Notch/Su(H)/E(spl)-HLH cascade specifically controls daughter, but not progenitor proliferation. Additionally, we find that different E(spl)-HLH genes are required in different neuroblast lineages. The Notch/Su(H)/E(spl)-HLH cascade alters daughter proliferation by regulating four key cell cycle factors: Cyclin E, String/Cdc25, E2f and Dacapo (mammalian p21CIP1/p27KIP1/p57Kip2). ChIP and DamID analysis of Su(H) and E(spl)-HLH indicates direct transcriptional regulation of the cell cycle genes, and of the Notch pathway itself. These results point to a multi-level signaling model and may help shed light on the dichotomous proliferative role of Notch signaling in many other systems.

Cell-Autonomous and Non-cell-autonomous Function of Hox Genes Specify Segmental Neuroblast Identity in the Gnathal Region of the Embryonic CNS in Drosophila

During central nervous system (CNS) development neural stem cells (Neuroblasts, NBs) have to acquire an identity appropriate to their location. In thoracic and abdominal segments of Drosophila, the expression pattern of Bithorax-Complex Hox genes is known to specify the segmental identity of NBs prior to their delamination from the neuroectoderm. Compared to the thoracic, ground state segmental units in the head region are derived to different degrees, and the precise mechanism of segmental specification of NBs in this region is still unclear. We identified and characterized a set of serially homologous NB-lineages in the gnathal segments and used one of them (NB6-4 lineage) as a model to investigate the mechanism conferring segment-specific identities to gnathal NBs. We show that NB6-4 is primarily determined by the cell-autonomous function of the Hox gene Deformed (Dfd). Interestingly, however, it also requires a non-cell-autonomous function of labial and Antennapedia that are expressed in adjacent anterior or posterior compartments. We identify the secreted molecule Amalgam (Ama) as a downstream target of the Antennapedia-Complex Hox genes labial, Dfd, Sex combs reduced and Antennapedia. In conjunction with its receptor Neurotactin (Nrt) and the effector kinase Abelson tyrosine kinase (Abl), Ama is necessary in parallel to the cell-autonomous Dfd pathway for the correct specification of the maxillary identity of NB6-4. Both pathways repress CyclinE (CycE) and loss of function of either of these pathways leads to a partial transformation (40%), whereas simultaneous mutation of both pathways leads to a complete transformation (100%) of NB6-4 segmental identity. Finally, we provide genetic evidences, that the Ama-Nrt-Abl-pathway regulates CycE expression by altering the function of the Hippo effector Yorkie in embryonic NBs. The disclosure of a non-cell-autonomous influence of Hox genes on neural stem cells provides new insight into the process of segmental patterning in the developing CNS.

The central nervous system (CNS) needs to be subdivided into functionally specified regions. In the developing CNS of Drosophila, each neural stem cell, called neuroblasts (NB), acquires a unique identity according to its anterior-posterior and dorso-ventral position to generate a specific cell lineage. Along the anterior-posterior body axis, Hox genes of the Bithorax-Complex convey segmental identities to NBs in the trunk segments. In the derived gnathal and brain segments, the mechanisms specifying segmental NB identities are largely unknown. We investigated the role of Hox genes of the Antennapedia-Complex in the gnathal CNS. In addition to cell-autonomous Hox gene function, we unexpectedly uncovered a parallel non-cell-autonomous pathway in mediating segmental specification of embryonic NBs in gnathal segments. Both pathways restrict the expression of the cell cycle gene CyclinE, ensuring the proper specification of a glial cell lineage. Whereas the Hox gene Deformed mediates this cell-autonomously, labial and Antennapedia influence the identity via transcriptional regulation of the secreted molecule Amalgam (and its downstream pathway) in a non-cell-autonomous manner. These findings shed new light on the role of the highly conserved Hox genes during segmental patterning of neural stem cells in the CNS.

Inhibition of succinate dehydrogenase sensitizes cyclin E-driven ovarian cancer to CDK inhibition

AIM

High-grade serous ovarian cancer (HGS-OvCa) is characterized by widespread CCNE1 amplification. Current treatments lack specificity to target Cyclin E-driven OvCa.

METHODS

By in silico analysis of the TCGA OvCa dataset we searched association between genes involved in glucose metabolism and cell cycle control. Metabolic shift was studied in Cyclin E-driven OvCa cells treated with CDK inhibition (CDKi). Genetic and pharmaceutical inhibition of succinate dehydrogenase (SDH) was tested in combination with CDKi.

RESULTS

OvCa patients with CCNE1 amplification could be divided by concomitant SDHA amplification. A2780 OvCa cells were similar to the Cyclin E-driven and SDHA neutral genotype. CDKi in A2780 cells using Dinaciclib resulted in compensatory enhancement of tricarboxylicacid cycle (TCA) cycle activity. Combined blockade of CDK and SDH, both genetically and pharmaceutically, showed synergy and resulted in inhibited proliferation, migration, invasion and migration in A2780 cells. The combined inhibition did not further alter cell cycle population, but induced apoptosis of A2780 cells.

CONCLUSION

Cyclin E-driven OvCa cells appeared addicted to glucose metabolism via TCA. Combined CDKi with modalities targeting TCA, like SDHA inhibition showed promising effects for this genotype.

Aberrant TGFβ Signaling Contributes to Altered Trophoblast Differentiation in Preeclampsia

TGFβ has been implicated in preeclampsia, but its intracellular signaling via phosphorylated mothers against decapentaplegic (SMADs) and SMAD-independent proteins in the placenta remains elusive. Here we show that TGFβ receptor-regulated SMAD2 was activated (Ser(465/467) phosphorylation) in syncytiotrophoblast and proliferating extravillous trophoblast cells of first-trimester placenta, whereas inhibitory SMAD7 located primarily to cytotrophoblast cells. SMAD2 phosphorylation decreased with advancing gestation, whereas SMAD7 expression increased and shifted to syncytiotrophoblasts toward term. Additionally, we found that the TGFβ SMAD-independent signaling via partitioning defective protein 6 (PARD6)/Smad ubiquitylation regulatory factor was activated at approximately 10-12 weeks of gestation in cytotrophoblast and extravillous trophoblast cells comprising the anchoring column. Placentae from early-onset, but not late-onset, preeclampsia exhibited elevated SMAD2 phosphorylation and SMAD7 levels. Whereas PARD6 expression increased and SMURF1 levels decreased in preeclamptic placentae, their association increased. SMAD2 phosphorylation by TGFβ in villous explants and BeWo cells resulted in a reduction of Glial cell missing-1 (GCM1) and fusogenic protein syncytin-1 while increasing cell cycle regulators cyclin E-1 (CCNE1) and cyclin-dependent kinase 4. SMAD7 abrogated the proliferative effects of TGFβ. CCNE1 levels were increased in preeclamptic placentae, whereas GCM1 was markedly reduced. In addition, TGFβ treatment increased the association of PARD6 and SMURF1 and down-regulated Ras homolog gene family, member A (RHOA) GTPase in JEG3 cells. In a wound assay, TGFβ treatment increased the association of PARD6 and SMURF1 and triggered JEG3 cell migration through increased cellular protrusions. Taken together, our data indicate that TGFβ signaling via both SMAD2/7 and PARD6/SMURF1 pathways plays a role in trophoblast growth and differentiation. Altered SMAD regulation of GCM1 and CCNE1 and aberrant expression/activation of PARD6/SMURF1 may contribute to the pathogenesis of preeclampsia by affecting cellular pathways associated with this disorder.

Anti-Tumor and Immune Enhancing Activities of Rice Bran Gramisterol on Acute Myelogenous Leukemia

Background

Acute myelogenous leukemia (AML) is a cancer of the blood that most commonly affects human adults. The specific cause of AML is unclear, but it induces abnormality of white blood cells that grow rapidly and accumulate in bone marrow interfering with the production and functions of the normal blood cells. AML patients face poor prognosis and low quality of life during chemotherapy or transplantation of hematopoietic stem cells due to the progressive impairment of their immune system. The goal of this study is to find natural products that have the potential to delay growth or eliminate the abnormal leukemic cells but cause less harmful effect to the body’s immune system.

Methods and Findings

The unsaponified fraction of Riceberry rice bran (RBDS) and the main pure compound, gramisterol, were studied for cytotoxicity and biological activities in WEHI-3 cells and in the leukemic mouse model induced by transplantation of WEHI-3 cells intraperitoneally. In the in vitro assay, RBDS and gramisterol exerted sub-G1 phase cell cycle arrest with a potent induction of apoptosis. Both of them effectively decreased cell cycle controlling proteins (cyclin D1 and cyclin E), suppressed cellular DNA synthesis and mitotic division, and reduced anti-apoptosis Bcl-2 protein, but increased apoptotic proteins (p53 and Bax) and activated caspase-3 enzyme in the intrinsic cell death stimulation pathway. In leukemic mice, daily feeding of RBDS significantly increased the amount of immune function-related cells including CD3⁺, CD19⁺, and CD11b⁺, and elevated the serum levels of IFN-γ, TNF-α, IL-2, and IL-12β cytokines, but suppressed IL-10 level. At the tumor sites, CD11b⁺ cells were polarized and became active phagocytotic cells. Treatment of mice normal immune cells with gramisterol alone or a combination of gramisterol with cytokines released from RBDS-treated leukemic mice splenocytes culture synergistically increased pSTAT1 transcriptional factor that up-regulated the genes controlling cell survival and function. Phosphorylation of STAT1 was absent in WEHI-3. Instead, similar treatments significantly decreased pSTAT3 signaling that regulates transcription of genes controlling tumor growth and proliferation.

Conclusions

Rice bran gramisterol possesses a promising anti-cancer effect against a tumor of white blood cells and induces the production of anti-cancer immune-related cytokines. Gramisterol induces cell cycle arrest and apoptosis via suppression of pSTAT3 signaling control of tumor cells’ growth and progression. Gramisterol increased IFN-γ production and prevented the dysfunctional immune system of leukemic mice by enhancing pSTAT1 transcription signal controlling proliferation and functions of hematopoietic cells in the spleen. Together with IFN-γ, gramisterol efficiently facilitates leukemic mice immune system modulation leading to improvement of the AML condition. Administration of RBDS containing gramisterol potentiates immune recovery of leukemic mice and extends their survival. This finding encourages the medicinal application of rice bran gramisterol as a palliative treatment or an alternative agent for future drug development against AML.

The prognostic significance of p53, Bax, Bcl-2 and cyclin E protein overexpression in colon cancer - an immunohistochemical study using the tissue microarray technique

In colon cancer, biological markers continue to have a limited prognostic value, the results being controversial. Studies of cell-cycle regulatory proteins and anti-apoptotic proteins aim to identify groups of patients that develop more aggressive tumors and might benefit from an individualized therapy management. The present study evaluates the prognostic role of the p53, Bax, Bcl-2 and cyclin E immunoexpression in colon cancer, using the tissue microarray (TMA) method. Tissue samples were obtained from 31 patients operated for colon cancer, embedded in TMA paraffin blocks and immunohistochemically stained for p53, Bax, Bcl-2 and cyclin E. We evaluated the relationship between the overexpression of these proteins and the clinico-pathological parameters, as well as the effect of these molecular markers on the survival rate. 65.22% of the patients were p53 positive, 39.13% Bcl-2 positive, 78.26% Bax positive and 34.78% cyclin E positive. Bcl-2(+) patients had significantly better differentiated tumors (p=0.043). Significantly poorly differentiated tumors were: Bax(+) patients (p=0.031), Bcl-2(-)÷p53(-) patients (p=0.042), Bcl-2(-)÷Bax(+) patients (p=0.029), and Bcl-2(-)÷p53(-)÷Bax(+) patients (p=0.016). The individual expression of the studied proteins did not influence the survival rate. A significantly lower survival rate was found in the following groups of patients: Bcl-2(-)÷p53(-) (40% vs. 83.3%, p=0.027), p53(-)÷Bax(+) (40% vs. 83.3%, p=0.027), Bcl-2(-)÷p53(-)÷Bax(+) (25% vs. 84.2%, p=0.003). The current study identified groups of patients with a significantly lower survival rate, which consequently are at an increased risk to develop tumors with a more aggressive biological behavior.

Enhanced Expression of miR-199b-5p Promotes Proliferation of Pancreatic β-Cells by Down-Regulation of MLK3

BACKGROUND

The initiation of β-cell proliferation to recover reduced β-cell mass is considered as one of the attractive therapeutic approaches for type 1 and 2 diabetes. In this study, we investigated the involvement of miRNAs in β-cell proliferation.

METHODS

Global miRNA array analysis of pancreas tissue was carried out using a 60% partial pancreatectomy (PPx) rodent model, which is a well-characterized model for pancreatic regeneration with accelerated proliferation of β-cells. To explore miRNAs with mitogenic activity on β-cells, precursors and antisense oligonucleotides (ASOs) for miRNAs were transfected into a primary islet monolayer cell cultures isolated from adult rats in order to modify their expression and proliferation of β-cells.

RESULTS

We found that miR-199b-5p, which was up-regulated 2.6 times in the pancreas of the PPx treated group, significantly enhanced the proliferation of β-cells when its precursor was over-expressed. Target genes of miR-199b-5p were investigated and Mixed lineage kinase-3 (MLK3) was identified as one of the candidates since its expression was down-regulated through an interaction with miR-199b-5p and siRNA treatment for MLK3 enhanced the proliferation of β-cells.

CONCLUSION

Our data suggest that the up-regulation of miR-199b-5p enhances proliferation of β-cells at least in part through down-regulation of MLK3.

CD126 and Targeted Therapy with Tocilizumab in Chronic Lymphocytic Leukemia

PURPOSE

IL6 promotes tumor growth and signal transduction via both its membrane-bound (CD126) and soluble receptors (sCD126). We aimed to study whether the levels of CD126 expression in chronic lymphocytic leukemic (CLL) cells can predict in vitro and in vivo treatment response.

EXPERIMENTAL DESIGN

The levels of membrane-bound CD126 expression were determined on freshly isolated CLL B cells (n = 58) using flow cytometry. These CLL cells were treated with chlorambucil or fludarabine with or without anti-CD126 antibody tocilizumab for 24 hours and IL6-mediated STAT3 transcriptional activity and cell-cycle alteration were evaluated.

RESULTS

CD126 surface expression was found in all cases and positively correlated with the levels of in vivo constitutive STAT3 activity. The levels of CD126 expression were significantly and positively correlated with the resistance of CLL cells to in vitro treatment with chlorambucil or fludarabine and poor in vivo treatment response of CLL patients. Blocking IL6 signaling with the anti-CD126 antibody, tocilizumab, had profound effects on STAT3-mediated survival and growth signals: decreased Mcl-1 and Bcl-xL, favoring an apoptotic profile; and decreased p27 with increased cyclin E and CDK2 expression, leading to cell-cycle shift from G0-G1 These tocilizumab-mediated changes induced chemosensitization in resistant CLL cells, with the greatest effect seen in cells with higher CD126 expression (P < 0.001).

CONCLUSIONS

CLL cells with higher CD126 expression are more resistant to treatment in vivo and in vitro via IL6-CD126-STAT3 axis. Blocking CD126 using tocilizumab sensitizes CLL cells to chemotherapy. Clin Cancer Res; 22(10); 2462-9. ©2015 AACR.

Urotensin-II-Mediated Reactive Oxygen Species Generation via NADPH Oxidase Pathway Contributes to Hepatic Oval Cell Proliferation

Urotensin II (UII), a somatostatin-like cyclic peptide, is involved in tumor progression due to its mitogenic effect. Our previous study demonstrated that UII and its receptor UT were up-regulated in human hepatocellular carcinoma (HCC), and exogenous UII promoted proliferation of human hepatoma cell line BEL-7402. Hepatic progenitor cell (HPCs) are considered to be one of the origins of liver cancer cells, but their relationship with UII remains unclear. In this work, we aimed to investigate the effect of UII on ROS generation in HPCs and the mechanisms of UII-induced ROS in promoting cell proliferation. Human HCC samples were used to examine ROS level and expression of NADPH oxidase. Hepatic oval cell line WB-F344 was utilized to investigate the underlying mechanisms. ROS level was detected by dihydroethidium (DHE) or 2’, 7’-dichlorofluorescein diacetate (DCF-DA) fluorescent probe. For HCC samples, ROS level and expression of NADPH oxidase were significantly up-regulated. In vitro, UII also increased ROS generation and expression of NADPH oxidase in WB-F344 cells. NADPH oxidase inhibitor apocynin pretreatment partially abolished UII-increased phosphorylation of PI3K/Akt and ERK, expression of cyclin E/cyclin-dependent kinase 2. Cell cycle was then analyzed by flow cytometry and UII-elevated S phase proportion was inhibited by apocynin pretreatment. Finally, bromodeoxyuridine (Brdu) incorporation assay showed that apocynin partially abolished UII induced cell proliferation. In conclusion, this study indicates that UII-increased ROS production via the NADPH oxidase pathway is partially associated with activation of the PI3K/Akt and ERK cascades, accelerates G1/S transition, and contributes to cell proliferation. These results showed that UII plays an important role in growth of HPCs, which provides novel evidence for the involvement of HPCs in the formation and pathogenesis of HCC.

Induction of cell cycle arrest via the p21, p27-cyclin E,A/Cdk2 pathway in SMMC-7721 hepatoma cells by clioquinol

Clioquinol has been shown to have anticancer activity in several carcinoma cells. In this study, we preliminarily examined the effect of clioquinol in human SMMC-7721 hepatoma and QSG-7701 normal hepatic cells. Our results indicated that clioquinol did not significantly affect survival of QSG-7701 cells, whereas it reduced cell viability in a concentration- and time-dependent manner in SMMC-7721 cells. Clioquinol did not trigger autophagy and apoptosis, while it induced cell cycle arrest in the S-phase in SMMC- 7721 cells. Additionally, down-regulation of cyclin D1, A2, E1, Cdk2 and up-regulation of p21, p27 were detected after the treatment with clioquinol. The results demonstrated for the first time that clioquinol suppressed cell cycle progression in the S-phase in SMMC-7721 cells via the p21, p27-cyclin E,A/Cdk2 pathway. This suggests that clioquinol may have a therapeutic potential as an anticancer drug for certain malignances.

Significant lethality following liver resection in A20 heterozygous knockout mice uncovers a key role for A20 in liver regeneration

Hepatic expression of A20, including in hepatocytes, increases in response to injury, inflammation and resection. This increase likely serves a hepatoprotective purpose. The characteristic unfettered liver inflammation and necrosis in A20 knockout mice established physiologic upregulation of A20 as integral to the anti-inflammatory and anti-apoptotic armamentarium of hepatocytes. However, the implication of physiologic upregulation of A20 in modulating hepatocytes' proliferative responses following liver resection remains controversial. To resolve the impact of A20 on hepatocyte proliferation and the liver's regenerative capacity, we examined whether decreased A20 expression, as in A20 heterozygous knockout mice, affects outcome following two-third partial hepatectomy. A20 heterozygous mice do not demonstrate a striking liver phenotype, indicating that their A20 expression levels are still sufficient to contain inflammation and cell death at baseline. However, usually benign partial hepatectomy provoked a staggering lethality (>40%) in these mice, uncovering an unsuspected phenotype. Heightened lethality in A20 heterozygous mice following partial hepatectomy resulted from impaired hepatocyte proliferation due to heightened levels of cyclin-dependent kinase inhibitor, p21, and deficient upregulation of cyclins D1, E and A, in the context of worsened liver steatosis. A20 heterozygous knockout minimally affected baseline liver transcriptome, mostly circadian rhythm genes. Nevertheless, this caused differential expression of >1000 genes post hepatectomy, hindering lipid metabolism, bile acid biosynthesis, insulin signaling and cell cycle, all critical cellular processes for liver regeneration. These results demonstrate that mere reduction of A20 levels causes worse outcome post hepatectomy than full knockout of bona fide liver pro-regenerative players such as IL-6, clearly ascertaining A20's primordial role in enabling liver regeneration. Clinical implications of these data are of utmost importance as they caution safety of extensive hepatectomy for donation or tumor in carriers of A20/TNFAIP3 single nucleotide polymorphisms alleles that decrease A20 expression or function, and prompt the development of A20-based liver pro-regenerative therapies.

High-Throughput Amplicon-Based Copy Number Detection of 11 Genes in Formalin-Fixed Paraffin-Embedded Ovarian Tumour Samples by MLPA-Seq

Whilst next generation sequencing can report point mutations in fixed tissue tumour samples reliably, the accurate determination of copy number is more challenging. The conventional Multiplex Ligation-dependent Probe Amplification (MLPA) assay is an effective tool for measurement of gene dosage, but is restricted to around 50 targets due to size resolution of the MLPA probes. By switching from a size-resolved format, to a sequence-resolved format we developed a scalable, high-throughput, quantitative assay. MLPA-seq is capable of detecting deletions, duplications, and amplifications in as little as 5ng of genomic DNA, including from formalin-fixed paraffin-embedded (FFPE) tumour samples. We show that this method can detect BRCA1, BRCA2, ERBB2 and CCNE1 copy number changes in DNA extracted from snap-frozen and FFPE tumour tissue, with 100% sensitivity and >99.5% specificity.