P27 Kip1 Expression Research Articles

Deficiency of heat shock factor 4 promotes lens epithelial cell senescence through upregulating p21cip1 expression

Genetic mutations in heat shock factor 4 (Hsf4) is associated with both congenital and age-related cataracts. Hsf4 regulates lens development through its ability to both activate and inhibit transcription. Previous studies suggested Hsf4 is involved in modulating cellular senescence depending on p21cip1 and p27 kip1 expression in MEF cells. Here, we found that Hsf4 acts as a suppressor of p21cip1 expression and plays an anti-senescence role during lens development. Knocking out Hsf4 facilitated UVB-induced cellular senescence in mouse lens epithelial cells (mLECs). p21cip1 was upregulated at both the mRNA and protein levels in HSF4−/− mLECs under control and UVB-treated conditions, and knockdown of p21cip1 by siRNA alleviated UVB-induced cellular senescence. HSF4 directly bound to the p21cip1 promoter and increased H3K27m3 levels at the p21cip1 proximal promoter region by recruiting the methyltransferase EZH2. In animal models, p21cip1 was gradually upregulated in wild-type mouse lenses with increasing age, while Hsf4 levels decreased. We generated a Hsf4 mutant mice line (Hsf4del-42) which displayed obvious congenital cataract phenotype. The expression of p21cip1 and senescence-associated cytokines were induced in the cataractous lenses of Hsf4del-42 mice. H3K27m3 and EZH2 levels decreased in p21cip1 promoters in the lenses of Hsf4del-42 mice. The SA-β-Gal activities were positive in lens epithelia of aged Hsf4null zebrafish compared to wild-type lenses. p21cip1 and senescence-associated cytokines levels were also upregulated in lenses of Hsf4null zebrafish. Accordingly, we propose that HSF4 plays a protective role in lens epithelial cells against cellular senescence during lens development and aging, partly by fine-tuning p21cip1 expression.

Resveratrol Attenuates the Proliferation of Prostatic Stromal Cells in Benign Prostatic Hyperplasia by Regulating Cell Cycle Progression, Apoptosis, Signaling Pathways, BPH Markers, and NF- κB Activity.

Resveratrol can inhibit cell proliferation and metastasis and induce apoptosis. However, the mechanisms of action through which resveratrol inhibits the abnormal proliferation of prostate stromal cells, causing prostatic hyperplasia, have not been fully elucidated. Here, we evaluated the inhibitory effects of resveratrol on cell proliferation associated with prostatic hyperplasia using WPMY-1 cells. Our results showed that resveratrol inhibited the proliferation of WPMY-1 cells via the induction of G0/G1-phase cell cycle arrest, which was caused by downregulated expression of cyclins and cyclin-dependent kinases regulated by increased p21WAF1 and p27KIP1 expression level. In addition, resveratrol treatment suppressed the phosphorylation of phosphatidylinositol 3-kinase/AKT and extracellular signal-regulated kinase 1/2. The expression levels of molecular markers affecting prostate development were also reduced by treatment with resveratrol. Finally, resveratrol attenuated the binding activity of the transcription factor nuclear factor-κB in WPMY-1 cells, and accelerated apoptotic cell death via intrinsic cascade pathway. These results indicate that resveratrol may be useful for the prevention or treatment of prostatic hyperplasia.

Complementary role of p57kip2 immunostaining in diagnosing hydatidiform mole subtypes.

Gestational trophoblastic disease comprises of a spectrum of pregnancy-related tumours which includes complete (CHM) and partial hydatidiform moles (PHM). Accurate diagnosis and subclassification of HM subtypes are crucial as prognosis differs. Histopathological examination using haemotoxylin and eosin (H&E) staining remains the basis for diagnosing HM, with only 80% accuracy. p57kip2 is a cyclin-dependent kinase inhibitor (CDKI) protein and is strongly paternally imprinted, being expressed from maternal allele. Therefore, complete mole (CHM) with only paternal genome has nearly absent expression of p57kip2 compared to partial mole (PHM) having both paternal and maternal genomes. This study is aimed to determine usefulness of p57kip2 immunohistochemistry (IHC) analysis in the diagnosis of HM subtypes. A total of 82 archived paraffin embedded HM tissues with subtypes classified based on H&E staining- 39 (47.5%) CHM, 41 (50.0%) PHM and two (2.43%) unclassified molar pregnancy were retrieved. All tissue samples were subjected for p57kip2 IHC analysis and HM subtypes were then reclassified. A total of 66 cases (80.5%) were re-classified as CHM, 14 cases (17.1%) as PHM and two cases (2.4%) were decidual and cystic tissues. Analysis using p57kip2 immunostaining showed a diagnostic discrepancy of 33.0% from routine H&E staining and helps to improve the characterisation of the HM subtypes specifically at early gestations which have less distinctive morphologies. IHC using p57kip2 monoclonal antibody should be considered as a routine ancillary test to H&E in improving the diagnosis of HM subtypes particularly in developing countries with limited resources.

Oncogenic and tumor suppressor pathways in subchronic aflatoxicosis in rats: Association with serum and urinary aflatoxin exposure biomarkers

In this study, the changes in oncogenic and tumor suppressor signaling pathways in liver and their association with serum and urinary biomarkers of aflatoxin exposure were evaluated in Wistar rats fed diets containing aflatoxin B1 (AFB1) for 90 days. Rats were divided into four groups (n = 15 per group) and assigned to dietary treatments containing 0 (control), 50 (AFB50), 100 (AFB100) and 200 μg AFB1 kg−1 diet (AFB200). Multiple preneoplastic foci of hepatocytes marked with glutathione-S-transferase-placental form (GST-P) were identified in AFB100 and AFB200 groups. Hepatocellular damage induced by AFB1 resulted in overexpression of cyclin D1 and β-catenin. The liver expression of retinoblastoma (Rb) and p27Kip1 decreased in AFB100 and AFB200 groups, confirming the favorable conditions for neoplastic progression to hepatocellular carcinoma. All samples from rats fed AFB1-contaminated diets had quantifiable AFB1-lysine in serum or urinary AFM1 and AFB1-N7-guanine, with mean levels of 20.42–50.34 ng mL−1, 5.31–37.68 and 39.15–126.37 ng mg−1 creatinine, respectively. Positive correlations were found between AFB1-lysine, AFM1 or AFB1-N7-guanine and GST-P+, β-catenin+ and cyclin D1+ hepatocytes, while Rb + cells negatively correlated with those AFB1 exposure biomarkers. The pathways evaluated are critical molecular mechanisms of AFB1-induced hepatocarcinogenesis in rats.

PDGF-BB-mediated activation of CREB in vascular smooth muscle cells alters cell cycling via Rb, FoxO1 and p27kip1

Introduction & AimThe vascular response to injury leads to the secretion of several factors, including platelet-derived growth factor (PDGF-BB). PDGF-BB stimulates smooth muscle cell (SMC) conversion to the synthetic phenotype, thereby enhancing proliferation and migration, and contributing to neointimal hyperplasia. Likewise, the cAMP response element binding protein (CREB) transcription factor has been shown to mediate SMC proliferation in response to various mitogens. We therefore investigated the contribution of CREB to PDGF-BB-dependent proliferation of SMCs with the intention of identifying signaling pathways involved both up and downstream of CREB activation. Methods & ResultsTreatments were performed on vascular SMCs from a porcine coronary artery explant model. The role of CREB was examined via adenoviral expression of a dominant-negative CREB mutant (kCREB) as well as inhibition of CREB binding protein (CBP). Involvement of the p27kip1 pathway was determined using a constitutively expressing p27kip1 adenoviral vector. PDGF-BB stimulated transient CREB phosphorylation on Ser-133 via ERK1/2-, PI3-kinase- and Src-dependent pathways. Expression of kCREB decreased PDGF-BB-dependent cell proliferation. PCNA expression and Rb phosphorylation were also inhibited by kCREB. These cell cycle proteins are controlled via p27kip1 expression in response to CREB-dependent post-translational modification of FoxO1. kCREB had no effect on Cyclin D1 expression, but did prevent PDGF-BB-induced Cyclin D1 nuclear translocation. An interaction inhibitor of CBP confirmed that Cyclin D1 is downstream of PDGF-BB and CREB. ConclusionCREB phosphorylation is required for SMC proliferation in response to PDGF-BB. This phenotypic change requires CBP and is mediated by Cyclin D1 and p27kip as a result of changes in FoxO1 activity.

ANO1 Expression Orchestrates p27Kip1/MCL1-Mediated Signaling in Head and Neck Squamous Cell Carcinoma.

Simple SummaryOur aim was to elucidate the molecular mechanisms of how ANO1 contributes to oncogenic processes in squamous cell carcinoma of the head and neck (HNSCC). We explored transcriptional programs influenced by ANO1 knockdown in patient-derived UT-SCC cell lines with 11q13 amplification and ANO1 overexpression. ANO1 depletion led to downregulation of broad pro-survival BCL2 family protein members, including MCL1, and simultaneously induced upregulation of the cell cycle inhibitor p27Kip1 and its redistribution from the cytoplasm into the nucleus in the studied HNSCC cells. Gene set enrichment analysis highlighted pathways associated with perturbed cell cycle and apoptosis in the ANO1-depleted samples. Silencing of ANO1 and application of an ANO1-targeting small-molecule inhibitor led to ANO1 degradation and reduction of cell viability. These findings suggest that ANO1 has drug target potential that deserves further evaluation in preclinical in vivo models.Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of tumors that derive from the mucosal epithelium of the upper aerodigestive tract and present high mortality rate. Lack of efficient targeted-therapies and biomarkers towards patients’ stratification are caveats in the disease treatment. Anoctamin 1 (ANO1) gene is amplified in 30% of HNSCC cases. Evidence suggests involvement of ANO1 in proliferation, migration, and evasion of apoptosis; however, the exact mechanisms remain elusive. Aim of this study was to unravel the ANO1-dependent transcriptional programs and expand the existing knowledge of ANO1 contribution to oncogenesis and drug response in HNSCC. We cultured two HNSCC cell lines established from primary tumors harboring amplification and high expression of ANO1 in three-dimensional collagen. Differential expression analysis of ANO1-depleted HNSCC cells demonstrated downregulation of MCL1 and simultaneous upregulation of p27Kip1 expression. Suppressing ANO1 expression led to redistribution of p27Kip1 from the cytoplasm to the nucleus and associated with a cell cycle arrested phenotype. ANO1 silencing or pharmacological inhibition resulted in reduction of cell viability and ANO1 protein levels, as well as suppression of pro-survival BCL2 family proteins. Collectively, these data provide insights of ANO1 involvement in HNSCC carcinogenesis and support the rationale that ANO1 is an actionable drug target.

Appropriate expression of P57kip2 drives trophoblast fusion via cell cycle arrest.

The syncytiotrophoblast, derived from cytotrophoblast fusion, is responsible for maternal-fetal exchanges, secretion of pregnancy-related hormones, and fetal defense against pathogens. Inadequate cytotrophoblast fusion can lead to pregnancy disorders, such as preeclampsia and fetal growth restriction. However, little is known about the mechanism of cytotrophoblast fusion in both physiological and pathological pregnancy conditions. In this study, P57kip2 (P57), a cell cycle-dependent kinase inhibitor that negatively regulates the cell cycle, was found to be up-regulated during the process of syncytialization in both primary trophoblast cells and BeWo cells. Co-immunofluorescence with proliferation markers Ki67 and Cyclin-CDK factors further showed that P57 specifically localizes in the post-mitotic cytotrophoblast subtype of the early pregnancy villi. Overexpression of P57 promoted trophoblast syncytialization by arresting the cell cycle at the G1/G0 phase and inhibiting proliferation. Blocking of the cell cycle through a serum starvation culture resulted in an enhancement of cytotrophoblast fusion and the up-regulation of P57. In both spontaneous cytotrophoblast fusion and forskolin-induced BeWo cell fusion models, an initial up-regulation of P57 was observed followed by a subsequent down-regulation. These findings indicate that proper expression of P57 at cytotrophoblast differentiation nodes plays an important role in trophoblast syncytialization.

AKT3 Expression in Mesenchymal Colorectal Cancer Cells Drives Growth and Is Associated with Epithelial-Mesenchymal Transition.

Simple SummaryColorectal cancer can be subdivided into four distinct subtypes that are characterised by different clinical features and responses to therapies currently used in the clinic to treat this disease. One of those subtypes, called CMS4, is associated with a worse prognosis and poor response to therapies compared to other subtypes. We therefore set out to explore what proteins are differentially expressed and used in CMS4 to find potential new targets for therapy. We found that protein AKT3 is highly expressed in CMS4, and that active AKT3 inhibits a protein that stalls growth of cancer cells (p27KIP1). We can target AKT3 with inhibitors which leads to strongly reduced growth of cancer cell lines that are categorised as CMS4. Furthermore, our data suggests that high AKT3 expression in tumour cells may be used to identify poor prognosis colorectal cancer patients. Future research should point out if high AKT3 expression can be used to select colorectal cancer patients that have a poor prognosis but that could benefit from AKT3-targeted treatment.Colorectal cancer (CRC) is a heterogeneous disease that can currently be subdivided into four distinct consensus molecular subtypes (CMS) based on gene expression profiling. The CMS4 subtype is marked by high expression of mesenchymal genes and is associated with a worse overall prognosis compared to other CMSs. Importantly, this subtype responds poorly to the standard therapies currently used to treat CRC. We set out to explore what regulatory signalling networks underlie the CMS4 phenotype of cancer cells, specifically, by analysing which kinases were more highly expressed in this subtype compared to others. We found AKT3 to be expressed in the cancer cell epithelium of CRC specimens, patient derived xenograft (PDX) models and in (primary) cell cultures representing CMS4. Importantly, chemical inhibition or knockout of this gene hampers outgrowth of this subtype, as AKT3 controls expression of the cell cycle regulator p27KIP1. Furthermore, high AKT3 expression was associated with high expression of epithelial-mesenchymal transition (EMT) genes, and this observation could be expanded to cell lines representing other carcinoma types. More importantly, this association allowed for the identification of CRC patients with a high propensity to metastasise and an associated poor prognosis. High AKT3 expression in the tumour epithelial compartment may thus be used as a surrogate marker for EMT and may allow for a selection of CRC patients that could benefit from AKT3-targeted therapy.

Mitogen-activated protein kinase inhibition-induced modulation of epidermal growth factor receptor signaling in human head and neck squamous cell carcinoma.

Epidermal growth factor receptor (EGFR) overexpression is one of the most notable characteristics in head and neck squamous cell carcinoma (HNSCC). The MAPK kinase (MEK) inhibitor trametinib has shown efficacy to treat HNSCC; however, the molecular mechanism remains unclear. HNSCC lines, mouse models, Western blot, and flow cytometry were employed to analyze the anticancer effects of trametinib. The JHU-011, JHU-022, and JHU-029 HNSCC cells with different genetic alterations were highly susceptible to trametinib. Trametinib effectively reduced EGFR expression, which was accompanied by the reduction of pro-survival protein MYC, and the increased expression of a MYC-targeted cyclin-dependent kinase inhibitor p27kip1 and pro-apoptotic protein BIM. Trametinib resulted in G1 arrest of the cells, markedly reduced cell numbers in S phase, and significantly increased apoptosis. In mouse models, trametinib strongly inhibited tumors growth. The MAPK-ERK signaling inhibition by trametinib may target EGFR and the downstream proteins against HNSCC.

A New CYP2E1 Inhibitor, 12-Imidazolyl-1-dodecanol, Represents a Potential Treatment for Hepatocellular Carcinoma.

Cytochrome P450 2E1 (CYP2E1) is a key target protein in the development of alcoholic and nonalcoholic fatty liver disease (FLD). The pathophysiological correlate is the massive production of reactive oxygen species. The role of CYP2E1 in the development of hepatocellular carcinoma (HCC), the final complication of FLD, remains controversial. Specifically, CYP2E1 has not yet been defined as a molecular target for HCC therapy. In addition, a CYP2E1-specific drug has not been developed. We have already shown that our newly developed CYP2E1 inhibitor 12-imidazolyl-1-dodecanol (I-ol) was therapeutically effective against alcoholic and nonalcoholic steatohepatitis. In this study, we investigated the effect of I-ol on HCC tumorigenesis and whether I-ol could serve as a possible treatment option for terminal-stage FLD. I-ol exerted a very highly significant antitumour effect against hepatocellular HepG2 cells. Cell viability was reduced in a dose-dependent manner, with only the highest doses causing a cytotoxic effect associated with caspase 3/7 activation. Comparable results were obtained for the model colorectal adenocarcinoma cell line, DLD-1, whose tumorigenesis is also associated with CYP2E1. Transcriptome analyses showed a clear effect of I-ol on apoptosis and cell-cycle regulation, with the increased expression of p27Kip1 being particularly noticeable. These observations were confirmed at the protein level for HepG2 and DLD-1 cells grafted on a chorioallantoic membrane. Cell-cycle analysis showed a complete loss of proliferating cells with a simultaneous increase in S-phase arrest beginning at a threshold dose of 30 μM. I-ol also reduced xenograft tumour growth in nude mice. This antitumour effect was not associated with tumour cachexia. I-ol was not toxic to healthy tissues or organs. This study demonstrates for the first time the therapeutic effect of the specific CYP2E1 inhibitor I-ol on the tumorigenesis of HCC. Our findings imply that I-ol can potentially be applied therapeutically on patients at the final stage of FLD.

Deficiency of Rbpj Leads to Defective Stress-Induced Hematopoietic Stem Cell Functions and Hif Mediated Activation of Non-canonical Notch Signaling Pathways.

Deregulated notch signaling has been associated with human pathobiology. However, functions of notch pathways in hematopoiesis remain incompletely understood. Here, we ablated canonical notch pathways, through genetic deletion of Rbpj, in hematopoietic stem cells (HSCs). Our data identified that loss of canonical notch results in normal adult HSC pool, at steady state conditions. However, HSC maintenance and functions in response to radiation-, chemotherapy-, and cytokine- induced stress were compromised in the absence of canonical notch. Rbpj deficient HSCs exhibit decreased proliferation rates and elevated expression of p57Kip2. Surprisingly, loss of Rbpj resulted in upregulation of key notch target genes and augmented binding of Hes1 to p57 and Gata2 promoters. Further molecular analyses identified an increase in notch activity, elevated expression and nuclear translocation of Hif proteins, and augmented binding of Hif1α to Hes1 promoter in the absence of Rbpj. These studies, for the first time, identify a previously unknown role for non-canonical notch signaling and establish a functional link between Hif and Notch pathways in hematopoiesis.

Obesity and the risk of Multiple Sclerosis. The role of Leptin

ObjectiveTo investigate the effects of leptin on different T‐cell populations, in order to gain more insight into the link between leptin and obesity.MethodsThree hundred and nine RRMS patients and 322 controls participated in a cross‐sectional survey, to confirm whether excess weight/obesity in adolescence or early adulthood increased the risk of MS. Serum leptin levels were determined by ELISA. MBP83–102, and MOG63–87 peptide‐specific T cells lines were expanded from peripheral blood mononuclear cells. Leptin receptor expression was measured by RT‐PCR and flow cytometry. Bcl‐2, p‐STAT3, pERK1/2, and p27kip1 expression were assayed using ELISA, and apoptosis induction was determined by Annexin V detection. Cytokines were assessed by ELISPOT and ELISA, and regulatory T cells (Tregs) by flow cytometry.ResultsLogistic regression analysis, showed excess weight at age 15, and obesity at 20 years of age increased MS risk (OR = 2.16, P = 0.01 and OR = 3.9, P = 0.01). Leptin levels correlated with BMI in both groups. The addition of Leptin increased autoreactive T‐cell proliferation, reduced apoptosis induction, and promoted proinflammatory cytokine secretion. Obese patients produced more proinflammatory cytokines compared to overweight/normal/underweight subjects. Inverse correlation was found between leptin levels and circulating Treg cells (r = −0.97, P < 0.0001). Leptin inhibited Treg proliferation. Effects of leptin on CD4+CD25− effector T cells were mediated by increased STAT3 and ERK1/2 phosphorylation, and down modulation of the cell cycle inhibitor P27kip1. In contrast, leptin effects on Tregs resulted from decreased phosphorylation of ERK1/2 and upregulation of p27kip1.InterpretationLeptin promotes autoreactive T‐cell proliferation and proinflammatory cytokine secretion, but inhibits Treg‐cell proliferation.

Up-regulation of cofilin-1 in cell senescence associates with morphological change and p27kip1 -mediated growth delay.

Morphological change is an explicit characteristic of cell senescence, but the underlying mechanisms remains to be addressed. Here, we demonstrated, after a survey of various actin‐binding proteins, that the post‐translational up‐regulation of cofilin‐1 was essential for the reduced rate of actin depolymerization morphological enlargement in senescent cells. Additionally, up‐regulated cofilin‐1 mainly existed in the serine‐3 phosphorylated form, according to the 2D gel immunoblotting assay. The up‐regulation of cofilin‐1 was also detected in aged mammalian tissues. The over‐expression of wild‐type cofilin‐1 and constitutively phosphorylated cofilin‐1 promoted cell senescence with an increased cell size. Additionally, senescent phenotypes were also reduced by knockdown of total cofilin‐1, which led to a decrease in phosphorylated cofilin‐1. The senescence induced by the over‐expression of cofilin‐1 was dependent on p27Kip1, but not on the p53 and p16INK4 expressions. The knockdown of p27Kip1 alleviated cell senescence induced by oxidative stress or replicative stress. We also found that the over‐expression of cofilin‐1 induced the expression of p27Kip1 through transcriptional suppression of the transcriptional enhancer factors domain 1 (TEAD1) transcription factor. The TEAD1 transcription factor played a transrepressive role in the p27Kip1 gene promoter, as determined by the promoter deletion reporter gene assay. Interestingly, the down‐regulation of TEAD1 was accompanied by the up‐regulation of cofilin‐1 in senescence. The knockdown and restoration of TEAD1 in young cells and old cells could induce and inhibit p27Kip1 and senescent phenotypes, respectively. Taken together, the current data suggest that cofilin‐1/TEAD1/p27Kip1 signaling is involved in senescence‐related morphological change and growth arrest.

Significance of cyclin D1 overexpression for the diagnosis of mantle cell lymphoma: a clinicopathologic comparison of cyclin D1-positive MCL and cyclin D1-negative MCL-like B-cell lymphoma

AbstractMantle cell lymphoma (MCL) is a distinct clinicopathologic entity of non-Hodgkin’s lymphoma, characterized by a monotonous proliferation of small to medium-sized lymphocytes with co-expression of CD5 and CD20, an aggressive and incurable clinical course, and frequent t(11;14)(q13;q32) translocation. We examined 151 cases of lymphoma with MCL morphology from a viewpoint of cyclin D1 overexpression, which is now easily detectable by immunohistochemistry. 128 cases (85%) showed positive nuclear staining for cyclin D1, while the remaining 23 (15%) were negative. Except for cyclin D1 immunohistochemistry, current diagnostic methods, including morphological and phenotypical examinations, could not make this distinction. Although both the cyclin D1-positive and -negative groups were characterized by male predominance, advanced stages of the disease, frequent extranodal involvement, and low CD23 reactivity, the cyclin D1-positive group showed a higher age distribution (P = .04), larger cell size (P = .02), higher mitotic index (P = .01), more frequent gastrointestinal involvement (P = .05), higher international prognostic index score (P = .05), and lower p27KIP1 expression (P < .0001). Of particular interest is that cyclin D1-positive MCL showed significantly worse survival than cyclin D1-negative lymphoma (5-year survival: 30% versus 86%, P = .0002), which was confirmed by multivariate analysis to be independent of other risk factors. These data suggest that cyclin D1-positive and -negative groups may represent different entities and that the former closely fits the characteristics of classical, typical MCL. We therefore propose that cyclin D1-positivity should be included as one of the standard criteria for MCL, and that innovative therapies for this incurable disease should be explored on the basis of the new criteria. (Blood. 2000;95:2253-2261

Expression of p57KIP2 reduces growth and invasion, and induces syncytialization in a human placental choriocarcinoma cell line, BeWo

IntroductionSyncytiotrophoblasts are the major components of the human placenta involved in fetal maternal exchange and hormone secretion. The syncytiotrophoblasts arise from the fusion of villous cytotrophoblasts. The cell cycle suppressor p57KIP2 is known to be an essential molecule for proper trophoblast differentiation during placental formation. MethodsWe generated p57KIP2-expressing BeWo transfectant cells. Proliferation assay and matrigel invasion assay were used to characterize p57KIP2-expressing BeWo transfectant cells. To reveal the role of p57KIP2 in syncytialization, we proceeded syncytium formation analysis and qRT-PCR for detection of the expression levels Syncytin-1, Syncytin-2 and their receptors. ResultsThe human choriocarcinoma cell line, BeWo has undetectable levels of p57KIP2 expression. Expression of p57KIP2 reduced cell proliferation rate and extracellular matrix invasion activity. p57KIP2 expressing cells displayed multinucleated cells associated with syncytiotrophoblast differentiation. In the syncytialization event, p57KIP2 was found to potentiate forskolin-induced upregulation of Syncytin-2 in a cAMP-independent manner. DiscussionThese results indicate that the expression of p57KIP2 may act on the proliferation/invasion inhibitory factor and enhance the expression of Syncytin-2, which are associated with syncytialization in cytotrophoblasts.

Administration of H2S improves erectile dysfunction by inhibiting phenotypic modulation of corpus cavernosum smooth muscle in bilateral cavernous nerve injury rats

Phenotypic modulation of Corpus Cavernosum Smooth Muscle Cells (CCSMCs) is an important step in the development and progression of bilateral cavernous nerve injury induced erectile dysfunction (BCNI-ED). To investigate the effect of exogenous hydrogen sulfide (H2S) on the phenotypic modulation of CCSMCs in BCNI-ED rats, a total of 18 male Sprague-Dawley rats were equally divided into 3 groups, including sham-operated (Sham) group, BCNI group and BCNI treated with NaHS (BCNI + NaHS) group. The treated group received intraperitoneal injection of NaHS (100 μmol kg−1day−1) for 4 weeks starting day 1 postoperatively. Erectile function was measured by the ratio of intracavernous pressure (ICP)/mean arterial pressure (MAP), and relevant tissues were harvested for Immunohistochemistry, Hematoxylin and eosin (H&E), Masson's trichrome staining, H2S fluorescent probe WSP-1 and Western blot. The primary CCSMCs were isolated and pretreatment with NaHS before exposed to PDGF-BB (platelet-derived growth factor). Relative expression mRNA and protein of phenotypic biomarkers, RhoA, ROCK-1 and cell cycle proteins were detected. Cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE), 3-mercaptopyruvate sulfurtransferase (3-MST) and H2S levels in penile tissue was significantly decreased in the BCNI group compared with the Sham group. Compared with the BCNI group, administration of NaHS significantly increased the ratio of ICP/MAP, ratio of smooth muscle to collagen, expressions of a-SMA, calponin and decreased the expression of OPN, collagen-I, RhoA, ROCK1 in the penile tissue. PDGF-BB-treated CCSMCs exhibited higher expression of OPN, RhoA, ROCK1, and lower α-SMA, calponin, which were attenuated by NaHS pretreatment. NaHS suppressed RhoA/ROCK activity and decreased the expression of CDK2, Cyclin E1, while increased the expression of P27kip1 induced by PDGF-BB in CCSMCs. Taken together, this study indicated that exogenous H2S inhibited the phenotypic modulation of CCSMCs by suppressing RhoA/ROCK1 signaling and affecting its downstream factor, CDK2, Cyclin E1, P27kip1, thereby improved BCNI rat erectile function.

FABP7 is a potential biomarker to predict response to neoadjuvant chemotherapy for breast cancer

BackgroundEarly prediction of response to neoadjuvant chemotherapy (NAC) is critical in choosing appropriate chemotherapeutic regimen for patients with locally advanced breast cancer. Herein, we sought to identify potential biomarkers to predict the response to neoadjuvant chemotherapy for breast cancer patients.MethodsThree genomic profiles acquired by microarray analysis from subjects with or without residual tumors after NAC downloaded from the GEO database were used to screen the differentially expressed genes (DEGs). An array of public databases, including ONCOMINE, cBioportal, Breast Cancer Gene Expression Miner v4.0, and the Kaplan Meir-plotter, etc., were used to evaluate the potential functions, related signaling pathway, as well as prognostic values of FABP7 in breast cancer. Anti-cancer drug sensitivity assay, real-time PCR, flow cytometry and western-blotting assays were used to investigate the function of FABP7 in breast cancer cells and examine the relevant mechanism.ResultsTwo differentially expressed genes, including FABP7 and ESR1, were identified to be potential indicators of response to anthracycline and taxanes for breast cancer. FABP7 was associated with better chemotherapeutic response, while ESR1 was associated with poorer chemotherapeutic effectiveness. Generally, the expression of FABP7 was significantly lower in breast cancer than normal tissue samples. FABP7 mainly high expressed in ER-negative breast tumor and might regulate cell cycle to enhance chemosensitivity. Moreover, elevated FABP7 expression increased the percentage of cells at both S and G2/M phase in MDA-MB-231-ADR cells, and decreased the percentage of cells at G0/G1 phase, as compared to control group. Western-blotting results showed that elevated FABP7 expression could increase Skp2 expression, while decrease Cdh1 and p27kip1 expression in MDA-MB-231-ADR cells. In addition, FABP7 was correlated to longer recurrence-free survival (RFS) in BC patients with ER-negative subtype of BC treated with chemotherapy.ConclusionFABP7 is a potential favorable biomarker and predicts better response to NAC in breast cancer patients. Future study on the predictive value and detail molecular mechanisms of FABP7 in contribution to chemosensitivity in breast cancer is warranted.

Active notch protects MAPK activated melanoma cell lines from MEK inhibitor cobimetinib

The crosstalk between Notch and MAPK pathway plays a role in MEK inhibitor resistance in BRAFV600E metastatic melanoma (MM) and promotes migration in GNAQQ209L uveal melanoma (UM) cells. We determined the cytotoxicity of combinatorial inhibition of MEK and Notch by cobimetinib and γ-secretase inhibitor (GSI) nirogacestat, in BRAFV600E and BRAF wt MM and GNAQQ209L UM cells displaying different Erk1/2 and Notch activation status, with the aim to elucidate the impact of Notch signaling in the response to MEK inhibitor. Overall the combination was synergic in BRAFV600E MM and GNAQQ209L UM cells and antagonistic in BRAF wt one. Focusing on UM cells, we found that cobimetinib resulted in G0/G1 phase arrest and apoptosis induction, whereas the combination with GSI increased treatment efficacy by inducing a senescent-like state of cells and by blocking migration towards liver cancer cells. Mechanistically, this was reflected in a strong reduction of cyclin D1, in the inactivation of retinoblastoma protein and in the increase of p27KIP1 expression levels. Of note, each drug alone prevented Notch signaling activation resulting in inhibition of c-jun(Ser63) and Hes-1 expression. The combination achieved the strongest inhibition on Notch signaling and on both c-jun(Ser63) and Erk1/2 activation level. In conclusion we unveiled a coordinate action of MAPK and Notch signaling in promoting proliferation of BRAFV600E MM and GNAQQ209L UM cells. Remarkably, the simultaneous inhibition of MEK and Notch signaling highlighted a role for the second pathway in protecting cells against senescence in GNAQQ209L UM cells treated with the MEK inhibitor.

Interplay between PI3K/mTOR Signaling and IRE1a-XBP1 Promotes Survival of Pre-B NRASG12D all Cells Providing a Therapeutic Vulnerability for the “Undruggable” Driver RAS

Background Activating RAS mutations drive around 30% of pre-B cell acute lymphoblastic leukemias (pre-B ALL) and are particularly common in relapsed ALL with a consecutively poor outcome. Recently published data demonstrated the critical role of the unfolded protein response (UPR) network, namely its IRE1α-XBP1 axis, for the survival of pre-B ALL cells: High expression of XBP1 confers a poor prognosis in pre B-ALL. However, the mechanism of XBP1 activation has not yet been elucidated in RAS mutated pre-B ALL. In this study, we aimed at identifying the molecular mechanism underlying pro-survival IRE1α-XBP1 signaling in RAS mutated pre-B ALL. Methods For a TET-ON inducible NRASG12D model in conditional Xbp1 knockout mice, we used interleukin 7 (IL-7)-dependent murine Mx1-Cre;Xbp1fl/fl pre-B cells transduced with a TET-ON inducible NRASG12D. We performed in vitro cell cycle and apoptosis assays with propidium iodide (PI) and annexin-V/PI. Furthermore, Western Blot and RT-qPCR were applied to analyze target gene expression. In a second approach, we focused on the signaling events following the blockade of RAS downstream targets using the MEK inhibitor PD0325901 and the dual PI3K/mTOR inhibitor BEZ235. We then assessed the efficacy of small molecule inhibition of IRE1α by MKC-8866 on XBP1 inactivation in RAS-mutated pre-B ALL cells either as a single treatment and in combination with the above mentioned drugs. Results We found the expression of Xbp1 significantly increased at the mRNA level with induction of NRASG12D. To determine the significance of Xbp1 in NRASG12D-driven pre-B ALL, we genetically deleted the IRE1α target Xbp1 using Cre-mediated deletion of Xbp1fl/fl in our mouse model of pre-B ALL. Genetic loss of Xbp1 significantly induced apoptosis (2.0-fold, p&amp;lt;0.0001) and caused cell cycle arrest (induction of G0/1, 1.7-fold, p=0.0003) along with an increase in the expression of CDK inhibitors, p21CIP1 and p27KIP1 at the protein level. Genetic ablation of Xbp1 abrogated IL-7 receptor (IL-7R) signaling by reducing the phosphorylation levels of STAT5-Y694 and JAK1-Y1022/Y1023. In an additional approach, we revealed that IL-7-deprived pre-B ALL cells reduce the mRNA expression of Xbp1s, indicating that Xbp1 acts as a downstream linchpin of the IL-7 receptor signaling pathway. Both IL-7-deprivation and genetic loss of Xbp1 increased the phosphorylation levels of ERK1/2-T202/Y204, AKT-S473 and the protein levels of NRASG12D and MAPK negative regulator DUSP6. Pharmacological inhibition of XBP1 activation using MKC-8866 resulted in similar effects on the expression of RAS downstream targets. We therefore tested MKC-8866 in combination with MEK inhibition by PD0325901 as a potential therapeutic strategy against pre-B ALL, which proved non-efficient. As a second option with therapeutic implications, we focused on the PI3K pathway which acts downstream of both the IL-7R and RAS signaling pathways. Strikingly, we observed that genetic ablation of Xbp1 (viable cells after 72 h, BEZ: 71.9 ± 9.0 vs BEZ+ Mx1-Cre;Xbp1fl/f: 10.0 ± 4.9) or pharmacological inhibition of its production with MKC-8866 (viable cells after five days, BEZ: 58.0 ± 6.8 vs BEZ+ MKC-8866: 13.3 ± 7.4) sensitizes pre-B ALL to dual inhibition of PI3K/mTOR with BEZ235. By applying the Bliss formula, we were able to show that BEZ235 in combination with MKC-8866 synergistically reduces the viability of RAS-mutated pre-B ALL cells. Gene expression analysis indicated that BEZ235 in combination with MKC-8866 fully blocked IL-7R signaling and caused an aberrant activation of Ras-Erk signaling. Targeting PI3K/mTOR signaling along with XBP1 inactivation increased expression of NRASG12D and its target DUSP6. In addition, we showed that combined therapy increased expression levels of p19Arf in RAS-mutated pre-B ALL, implicating cell senescence mediated by activated RAS signaling. Conclusion Our work strongly supports the hypothesis that XBP1 induces its positive effects on progression of pre-B ALL cells through the IL-7R signaling pathway. IL-7R signaling through its downstream effector XBP1 counteracts the RAS signaling pathway to promote leukemogenesis in pre-B ALL cells. Active XBP1 prevents the cytotoxic effects of BEZ235 in pre-B ALL cells, and hence targeting XBP1 in combination with dual PI3K/mTOR inhibition by BEZ235 appears as a promising targeted strategy against the "undruggable" driver RAS in NRASG12D-mutated pre-B ALL. Disclosures Brümmendorf: Janssen: Consultancy; Merck: Consultancy; Novartis: Consultancy, Other: travel, accommodation, expenses, Research Funding; Takeda: Consultancy; Pfizer: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding.

Rationale for and Results of a Phase I Study of the TGF-β 1/3 Inhibitor AVID200 in Subjects with Myelofibrosis: MPN-RC 118 Trial

Rationale for and Results of a Phase I Study of the TGF-β 1/3 Inhibitor AVID200 in Subjects with Myelofibrosis: MPN-RC 118 Trial