Increased P53 Expression Research Articles

Signaling Crosstalk of FHIT, p53, and p38 in etoposide-induced apoptosis in MCF-7 cells.

Fragile histidine trail (FHIT) is a tumor suppressor in response to DNA damage which has been deleted in various tumors. However, the signaling mechanisms and interactions of FHIT with regard to apoptotic proteins including p53 and p38 in the DNA damage-induced apoptosis are not well described. In the present study, we used etoposide-induced DNA damage in MCF-7 as a model to address these crosstalks. The time course study showed that the expression of FHIT, p53, and p38MAPK started after 1 hour following etoposide treatment. FHIT overexpression led to increase p53 expression, p38 activation, and augmented apoptosis following etoposide-induced DNA damage compared to wild-type cells. However, FHIT knockdown blocked p53 expression, delayed p38 activation, and completely inhibited etoposide-induced apoptosis. Inhibition of p38 activity prevented induction of p53, FHIT, and apoptosis in this model. Thus, activation of p38 upon etoposide treatment leads to increase in FHIT and p53 expression. In p53 knockdown MCF-7, the FHIT induction was hampered but p38 activation was induced in lower doses of etoposide. In p53 knockdown cells, inhibition of p38 induced FHIT expression and apoptosis. Our data demonstrated that the exposure of MCF-7 cells to etoposide increases apoptosis through a mechanism involving the activation of the p38-FHIT-p53 pathway. Moreover, our findings suggest signaling interaction for these pathways may represent a promising therapy for breast cancer.

P53 knockout mice are protected from cocaine-induced kindling behaviors via inhibiting mitochondrial oxidative burdens, mitochondrial dysfunction, and proapoptotic changes

Previously we demonstrated that p53 mediates dopaminergic neurotoxicity via inducing mitochondrial burdens and proapoptotsis. However, little is known about the role of p53 in the excitotoxicity induced by psychostimulant, such as cocaine. Cocaine-induced kindling (convulsive) behaviors significantly increased p53 expression in the brain. Cocaine-induced p53 expression was more pronounced in hippocampus than in striatum or prefrontal cortex. Genetic depletion of p53 significantly attenuated cocaine-induced convulsive behaviors, followed by c-Fos immunoreactivity, and oxidative burdens in the hippocampus of mice. The antioxidant potentials mediated by genetic depletion of p53 were more pronounced in the mitochondrial-than cytosolic-fraction. Depletion of p53 significantly attenuated the changes in mitochondrial transmembrane potential, intramitochondrial Ca2+ level, and mitochondrial oxidative burdens induced by cocaine. Consistently, depletion of p53 significantly inhibited mitochondrial p53 translocation, and cleaved-PKCδ induced by cocaine. In addition, depletion of p53 protected from cytosolic cytochrome c release, and pro-apoptotic changes induced by cocaine. Importantly, the protective/anticonvulsant potentials by genetic depletion of p53 were comparable to those by pifithrin-μ (PFT), a p53 inhibitor. Our results suggest that depletion of p53 offers anticonvulsive and neuroprotective potentials mainly via attenuating mitochondrial oxidative burdens, mitochondrial dysfunction, and pro-apoptotic signalings against cocaine-induced convulsive neurotoxicity.

Effects of shRNA-mediated silencing of PSMA7 on cell proliferation and vascular endothelial growth factor expression via the ubiquitin-proteasome pathway in cervical cancer.

This study aims to evaluate the effects of PSMA7 silencing on cervical cancer (CC) cell proliferation and vascular endothelial growth factor (VEGF) expression through the ubiquitin-proteasome pathway. CC tissues (n = 43) and normal tissues (n = 27) were first collected from patients. Human CC cell line (SiHa) and human normal cervical epithelial cells (H8) were obtained and classified into the normal, blank, negative control (NC), PSMA7-shRNA1, and PSMA7-shRNA2 groups, respectively.In situ hybridization was used to detect the expressions of wild-type and mutant p53 proteins. Immunofluorescence assay was carried out to test the activity of 20S proteasomes. Reverse transcription quantitative polymerase chain reaction and Western blot analysis were both performed to determine the expressions of PSMA7, ubiquitin, P27, P53, and VEGF in sample tissues and cells. 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to analyze cell proliferation rates, and flow cytometry was used to analyze the cell cycle and the apoptotic rate. Compared with normal tissues, CC tissues showed increased expression levels of PSMA7, ubiquitin, p53, VEGF as well as increased activity of 20S proteasomes but exhibited a decrease in p27 expression. Compared with the blank and NC groups, the PSMA7-shRNA1 and PSMA7-shRNA2 groups all had decreased expression levels of PSMA7, ubiquitin, p53, and VEGF as well as decreased cell proliferation, 20S proteasomes activity, and cell number in the S phase, increased p27 expression, cell apoptosis and cell number in the G0/G1 phase. Our study demonstrated that PSMA7 silencing can suppress CC cell proliferation and VEGF expression in addition to promoting cell apoptosis through inhibiting the UPP signaling pathway.

ER stress promotes antitumor effects in BRAFi/MEKi resistant human melanoma induced by natural compound 4-nerolidylcathecol (4-NC)

Melanoma accounts for only 4% of malignant neoplasms of the skin, but is considered the most serious because it is highly deadly. Mutations in the MAPK (Ras-Raf-MEK-ERK) pathway is closely linked to the lack of control of cell proliferation. Especially in melanoma, this pathway has become a target for the development of oncogene-targeted therapies, such as the potent inhibitors of v-Raf murine sarcoma viral oncogene homolog B (BRAFi) and mitogen-activated protein kinase kinase (MEKi). Very high rates of response have been achieved, but most patients are relapsed due to the development of resistance, justifying the constant search for new therapeutic compounds. Early results from our group indicated that 4-nerolidylcatechol (4-NC), a catechol compound extracted from Pothomorphe umbellata, induces DNA damage, ROS production, increased p53 expression culminating in apoptosis in melanoma but with no data regarding the 4-NC effects in cells resistant to BRAFi or MEKi. Therefore, here we evaluated the role of 4-NC alone or in combination with BRAFi/MEKi in resistant melanoma cells. Double-resistant cells were generated and characterized by MAPK pathway reactivation. 4-NC alone or in combination (30 μM) with MAPK inhibitors was cytotoxic, inhibited colony formation and decreased invasiveness in two and three-dimensional cell culture models of treatment-naïve, BRAFi-resistant and BRAF/MEKi double-resistant melanoma cells. Apoptosis induction was demonstrated in resistant and double-resistant melanoma cell lines after 4-NC treatments. 4-NC showed important ability to induce apoptosis via Endoplasmatic Reticulum (ER) stress and specifically BiP and CHOP that had increased protein expression in all melanoma cell lines proving to be part of the ER stress pathway activation. CHOP knockdown slightly but enough increases cellular viability following 4-NC treatment indicating that apoptosis observed is partially dependent on CHOP. In summary, we show that 4-NC is a compound with activity against cutaneous melanoma, including resistant cells to clinically approved therapies.

Long non-coding RNA DANCR promotes the progression of non-small-cell lung cancer by inhibiting p21 expression.

BackgroundLong non-coding RNAs (lncRNAs) play important roles in human cancers. However, the functional roles of lncRNAs in non-small-cell lung cancer (NSCLC) and the underlying mechanisms are not well understood.MethodsWe examined the expression of lncRNA DANCR in NSCLC by qRT-PCR and explored its biological roles in NSCLC progression by cell and molecular biology studies.ResultsDANCR expression level was increased in human NSCLC. The knockdown of DANCR inhibited NSCLC cell proliferation by inducing cell apoptosis and cell cycle arrest. In addition, DANCR knockdown suppressed NSCLC cell migration and invasion via inhibition of epithelial–mesenchymal transition (EMT). On the contrary, DANCR overexpression had the opposite effects. DANCR knockdown inhibited EZH-2-mediated epigenetic silencing of p21 promoter and increased p21 expression. Moreover, DANCR knockdown inhibited NSCLC cell proliferation, migration, and invasion in a p21-dependent manner.ConclusionDANCR plays oncogenic roles in NSCLC and may provide a novel biomarker for NSCLC diagnosis and prognosis.

A peptide mimicking the binding sites of VEGF-A and VEGF-B inhibits VEGFR-1/-2 driven angiogenesis, tumor growth and metastasis

Interfering with interactions of vascular endothelial growth factors (VEGFs) with their receptors (VEGFRs) effectively inhibits angiogenesis and tumor growth. We designed an antagonist peptide of VEGF-A and VEGF-B reproducing two discontinuous receptor binding regions of VEGF-B (loop 1 and loop3) covalently linked together by a receptor binding region of VEGF-A (loop3). The designed peptide (referred to as VGB4) was able to bind to both VEGFR1 and VEGFR2 on the Human Umbilical Vein Endothelial Cells (HUVECs) surface and inhibited VEGF-A driven proliferation, migration and tube formation in HUVECs through suppression of ERK1/2 and AKT phosphorylation. The whole-animal fluorescence imaging demonstrated that fluorescein isothiocyanate (FITC)-VGB4 accumulated in the mammary carcinoma tumors (MCTs). Administration of VGB4 led to the regression of 4T1 murine MCT growth through decreased expression of p-VEGFR1 and p-VEGFR2 and abrogation of ERK1/2 and AKT activation followed by considerable decrease of tumor cell proliferation (Ki67 expression) and angiogenesis (CD31 and CD34 expression), induction of apoptosis (increased p53 expression, TUNEL staining and decreased Bcl2 expression), and suppression of metastasis (increased E-cadherin and decreased N-cadherin, NF-κB and MMP-9 expression). These findings indicate that VGB4 may be applicable for antiangiogenic and antitumor therapy.

Protein Carbonylation Pattern Is Altered in Myelodisplastic Syndromes

* A.R. and M.L. have contributed equally. INTRODUCTIONMyelodysplastic syndrome (MDS) is a clonal disease that arises from the expansion of mutated hematopoietic stem cells. Oxidative stress could play an important role in the pathology of MDS since a correlation has been observed between high ROS levels and decreased survival in MDS patients. In addition, the oxidation of proteins leads to their aggregation, change and conformational changes that can cause the loss of their functions. Due to alteration of the proteome has been described in patients with MDS, in this study we considered the discovery of protein carbonylation to analyze its oxidation pattern. In addition, as the oxidative stress signaling pathways can regulate the cell cycle through p53, we analyzed p21, an important p53 target during the stress response. Finally, the possible benefit of treatment with Deferasirox as antioxidant therapy was studied. METHODSCarbonylation pattern was analyzed in the different cell lines (n = 14, 6 MDS, 4 reactive controls and 4 MDS + DFX) by immunohistochemistry by derivatization with 2,4-dinitrophenylhydrazine (DNPH) and detection with anti-DNP antibodies. The degree of protein carbonylation was studied, also by derivatization and detection with anti-DNP, in primary cells of erythroblasts expanded for 11 days, by one-dimensional and two-dimensional electrophoresis (n = 16; 7 MDS, 6 controls, 2 reactive controls and 1 MDS + DFX). Expression levels of p21 were analyzed by qRT-PCR (n=19; 8C, 8 MDS, 3DFX). RESULTSImmunohistochemical assays revealed a higher level of carbonylation in patients with MDS (Fig. 1a). Interestingly, Deferasirox-treated MDS patients had lower levels than non-treated patients (Fig. 1b). In addition, to evaluate the carbonylation in the erythroid precursors, the pattern of carbonylated proteins in the expanded erythroblasts was analyzed. Again, a higher level of MDS was observed compared to the control group, which was reversed after treatment with Deferasirox. Two-dimensional electrophoresis revealed that differences in carbonylation are due to a limited number of proteins or aggregates, rather than to a large spectrum of proteins. Finally, an increased p21 expression was observed in patients with myelodysplasia and, surprisingly, this effect was reversed with Deferasirox treatment. CONCLUSIONPatients with MDS showed a differential protein pattern respect to control patients, both in the myeloid and erythroid series. The increase in oxidative stress in myelodysplastic patients seems to activate signaling pathways involving p21. Treatment with Deferasirox can reverse the level of oxidation and the increase of p21 in patients with MDS. DisclosuresMartinez Lopez:Celgene: Research Funding, Speakers Bureau; Jansen: Research Funding, Speakers Bureau; BMS: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau.

Role of Enhanced Autophagy in Resistance of FLT3-ITD AML Stem Cells to FLT3 TKI Treatment

The FLT3-ITD mutation occurs in 25-30% of AML patients, and is associated with increased relapse rate and poor survival. FLT3 tyrosine kinase inhibitors (TKI) have shown encouraging results, but responses are not sustained in most patients. Therefore there is considerable interest in understanding mechanism contributing to resistance and preservation of FLT3-ITD AML stem cells after TKI treatment. Autophagy is an important cellular response that maintains cell survival under stress. Here we investigated the regulation of autophagy in FLT3-ITD+ AML cells, and its role in resistance to FLT3 TKI treatment.Expression of a FLT3-ITD construct in FLT3-ITD negative OCI-AML3 cells using lentiviral vectors resulted in increased autophagic flux compared with wild-type FLT3 or non-transduced controls. However, treatment of FLT3-ITD+ MV4-11 and Molm13 AML cells, or primary FLT3-ITD+ CD34+ cells, with the potent FLT3 TKI AC220 (Quizartinib) did not significantly alter autophagic flux. These results suggest that FLT3-ITD expression increases autophagy but in a kinase-independent manner.MV4-11 and Molm13 cells were transduced with the GFP-LC3-RFP-LC3 ΔG construct (Kaizuka T, et al,2016) to measure autophagic flux. Autophagyhigh AML cells showed lower growth rate compared with Autophagylow cells (0.65, p=0.025), and reduced sensitivity to inhibition by AC220 (0.49 vs 0.71, p=0.003). Treatment of MV4-11 and Molm13 cells with the potent autophagy inhibitor Lys05 in combination with AC220 resulted in significantly enhanced inhibition of AML cell growth (MV4-11: 0.83 vs 0.54, p<0.001; Molm13: 0.58 vs 0.43, p=0.02) and increased induction of apoptosis (MV4-11: 0.81 vs 0.54, p<0.001; Molm13: 0.73 vs 0.49, p=0.024) compared to AC220 alone. We further show that inhibition of autophagy by shRNA-mediated knockdown of the critical autophagy gene ATG5 enhanced sensitivity of AML cells to AC220 treatment (MV4-11: 0.91 vs 0.65, p=0.005; Molm13: 0.88 vs 0.64, p=0.004). Treatment with Lys05 also inhibited autophagic flux in primary FLT3-ITD+ AML CD34+ stem/progenitor cells and resulted in significantly increased inhibition of cell cycle arrest (G0 stage: 40.3% vs 61.8%), increased myeloid differentiation (CD11b: 1 vs 1.24, p=0.009; CD14: 1 vs 1.21, p=0.0024), and increased cell death when combined with AC220 (0.58% vs 0.78%, p=0.0245). These results indicate that increased autophagy in FLT3-ITD+ AML cells is associated with TKI resistance, and that autophagy inhibition enhances sensitivity of FLT3-ITD+ AML cells to TKI treatment.Induction of autophagy by starvation or mTOR inhibitor treatment in MOLM13 and MV4-11 cells was associated with reduced p53 expression, whereas autophagy inhibition by chloroquine or SAR405, a PIK3C3/Vps34 inhibitor, was associated with increased p53 expression. Starvation-mediated autophagy in FLT3-ITD+ AML cells was significantly increased upon p53 knockdown, suggesting that p53 has an inhibitory effect on autophagy. Enhanced inhibition of FLT3-ITD+ AML cell growth by autophagy inhibition in combination with AC220 treatment was prevented by shRNA-mediated knockdown of p53, suggesting that effects of autophagy inhibition on FLT3-ITD+ AML cell growth were p53 dependent.We conclude that FLT3-ITD expression enhances autophagic flux in FLT3-ITD+ AML cells in a kinase-independent manner, and that increased autophagy contributes to TKI resistance of FLT3-ITD+ AML cells. We show that autophagy inhibition can enhance sensitivity of FLT3-ITD+ AML stem cells to TKI treatment. Finally, we demonstrate important roles for autophagy in regulating p53 levels, and conversely for p53 in regulating autophagy and the effects of autophagy inhibition in FLT3-ITD+ AML cells. These studies support further development of strategies for targeting of autophagy and related pathways to enhance efficacy of TKI treatment in eliminating AML stem cells. DisclosuresNo relevant conflicts of interest to declare.

Wedelolactone suppresses cell proliferation and migration through AKT and AMPK signaling in melanoma

Purpose: Melanoma is a malignant tumor with high degree of malignancy, metastasis and high mortality. As melanoma is not sensitive to treatments, searching for new therapeutic agent is the priority. Wedelolactone (WDL) is a natural compound which has antiproliferation activities. In the current study, the effects of WDL on melanoma are evaluated and the underlying mechanisms are explored.Materials and methods: We treated melanoma cell line MV3 cells with WDL and monitored the cell proliferation, invasion and migration, the mRNA and protein levels of Bax and Bcl-2, expression of cell-cycle regulators including cyclin D, proliferating cell nuclear antigen (PCNA) and p21. We detected the effect of WDL on AKT and AMPK signaling pathways activations. Finally, we evaluated the inhibitory effect of WDL in xenograft nude mice model in vivo.Results: WDL inhibited MV3 cell proliferation, migration and invasion. WDL induced pro-apoptotic protein Bax expression but inhibited antiapoptotic protein Bcl-2 expression. WDL inhibited cyclin D expression while increased p21 expression. WDL inhibited AKT activation but induced AMPK activation. The induction of p21expression by WDL depended on AMPK signaling pathway. WDL inhibited melanoma in xenograft nude mice.Conclusion: WDL suppressed cell proliferation and regulated MV3 cell-cycle proteins through AKT and AMPK signaling in melanoma.

Utility of CD30, Ki-67, and p53 in assisting with the diagnosis of mycosis fungoides with large cell transformation.

Mycosis fungoides (MF) with large cell transformation (LCT) is an advanced stage of cutaneous lymphoma with a poor prognosis. Identification of LCT is critical and especially challenging when the number of large abnormal lymphocytes is near but below 25%. We propose that Ki-67 and p53 may be useful in making this diagnosis. We identified 17 patients with advanced stage (T3 or T4) MF without LCT and 38 patients with a biopsy-confirmed new diagnosis of MF with LCT treated at our institution's cutaneous lymphoma clinic from 2012 to 2016. Seventeen patients underwent 22 biopsies with advanced stage MF (control), and 38 patients with 46 biopsies of MF with LCT were included in this study. The MF cohort had an average CD30 expression of 4%, while the MF-LCT cohort had an average CD30 expression of 22% (P < 0.05). The MF cohort had an average Ki-67 staining of 13%, while the MF-LCT group had an average Ki-67 staining of 57% (P < 0.05). Forty-seven percent of the MF-LCT group was positive for p53; on the other hand, none of the MF control group showed increased p53 expression (P < 0.05). While CD30 shows some value in delineating large cell transformation, Ki-67 and p53 appear to be useful immunohistochemical markers in the diagnosis of LCT.

Urea transport B gene induces melanoma B16 cell death via activation of p53 and mitochondrial apoptosis.

Urea Transporter B (UT‐B) is a membrane channel protein that mediates the rapid transmembrane transport of urea and participates in urine concentration. Urea Transporter B is expressed in skin, but we found that there is little expression in human melanoma tissue. In this study, we examined the effects of UT‐B overexpression in melanoma. The results indicated that there is no UT‐B mRNA expression in B16 cells, and UT‐B overexpression repressed B16 cell proliferation and induced apoptosis in vitro. We show that UT‐B overexpression causes increased reactive oxygen species production, which may be caused by mitochondria dysfunction. The mitochondrial membrane potential (ΨΔm) was lower in UT‐B‐overexpressing B16 cells. The proteins involved in complexes I, III, IV and V of the respiratory chain were clearly downregulated in UT‐B‐overexpressing B16 cells, which would strongly reduce the activity of the electron transport chain. We found that mitochondrial release of cytochrome C into the cytoplasm also increased, indicating that apoptosis had been activated. In addition, UT‐B overexpression reduced AKT phosphorylation and MDM2 expression and increased p53 expression; p53 activation may be involved in the anticancer effects of UT‐B overexpression. Urea Transporter B overexpression also inhibited tumor growth in vivo. In conclusion, we demonstrated that UT‐B may be related to the occurrence of melanoma and play a role in tumor development.

Primate-specific miR-944 activates p53-dependent tumor suppression in human colorectal cancers

As cancers with a high incidence rate, colorectal cancers are a main cause of cancer-related death. MicroRNAs are often deregulated in cancers. The primate-specific miR-944, located in a p63 intron, is known to be highly expressed in patients exhibiting low colorectal cancer recurrence rates. However, the biological functions of miR-944 in colorectal cancers remain unclear. In this study, we found that miR-944 was downregulated in colorectal cancer tissues, and inhibited cancer cell growth in a xenograft mouse model. The overexpression of miR-944 caused G1 phase arrest and increased p53 expression in cancer cells. p53 stability was enhanced by miR-944s targeting E3 ligases COP1 and MDM2. Overexpression of COP1 and MDM2 restored cell growth inhibition caused by miR-944. Taken together, our results suggest that miR-944 acts as a potential tumor suppressor in colorectal cancers through the ubiquitin-proteasome system.

Jab1 Silencing Inhibits Proliferation and Sensitizes to Cisplatin in Biliary Tract Cancer

PurposeJab1 is a coactivator of c-Jun that enhances the transcriptional function of c-Jun. Jab1 is frequently overexpressed in various cancers and is associatedwith poor prognosis of cancer patients. Thus, Jab1 could be a potential therapeutic target in cancer. However, the role of Jab1 in biliary tract cancer (BTC) has not been studied.Materials and MethodsWe performed in vitro and in vivo experiments to evaluate the therapeutic potential ofJab1 inhibition in BTC.ResultsAmong 8 BTC cell lines, many showed higher Jab1 expression levels. In addition, Jab1 silencing by siRNA increased p27 expression levels. SNU478 and HuCCT-1 cells exhibited profound Jab1 knockdown and increased p27 expression by Jab1-specific siRNA transfection. Jab1 silencing induced anti-proliferative and anti-migratory effects and resulted in G1 cell cycle arrest in SNU478 and HuCCT-1 cells. In addition, Jab1 silencing potentiated the anti-proliferative and anti-migratory effects of cisplatin by increasing DNA damage. Interestingly,Jab1 knockdown increased PTEN protein half-life, resulting in increased PTEN expression. In the HuCCT-1 mouse xenograft model, stable knockdown of Jab1 by shRNA also showed anti-proliferative effects in vivo, with decreased Ki-67 expression and AKT phosphorylation and increased Terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling and p27 expression.ConclusionJab1 knockdown demonstrated anti-proliferative and anti-migratory effects in BTC cells by increasing DNA damage and stabilizing PTEN, resulting in G1 cell cycle arrest. In addition, Jab1 silencing potentiated the anti-proliferative effects of cisplatin. Our data suggest that Jab1 may be a potential therapeutic target in BTC that is worthy of further investigations.

Heterogeneity of the Arsenic-Bladder Cancer Relationship by Tumor p16/Rb Immunophenotype

Several studies have suggested arsenic may target important tumor-suppresser genes and disrupt cell cycle control and influence bladder cancer risk. In a large, population-based case-control study we evaluated whether there was heterogeneity in the arsenic-bladder cancer risk relationship by tumor expression of p16 and Rb. Tumor tissue from bladder cancer cases was assembled as tissue microarrays and examined for expression. Cutoff values used to define negative/positive staining were based on the distribution of the percentage of positive cells in cases. Data on cumulative arsenic from drinking water were used to evaluate the relationship between arsenic and bladder cancer by immunophenotype (p16-/p16&amp;#43;,Rb-/Rb&amp;#43;), in 424 cases and 1287 controls, using polytomous logistic regression. Our results show that the association between increasing cumulative arsenic and bladder cancer risk was only apparent among patients with p16&amp;#43; or Rb&amp;#43; tumors. We observed a strong monotonic association between risk and increasing cumulative arsenic intake (Quartile2-4 vs. Quartile1, ORp16&amp;#43; &amp;#61;1.36, 1.47, 1.85, p-trend&amp;#61;0.004 and ORRb&amp;#43; &amp;#61;1.51, 1.56, 1.94, p-trend&amp;#61;0.007). No association between cumulative arsenic and risk among patients with p16- or Rb- bladder tumors was apparent (p-heterogeneity by subtype&amp;#61;0.0325 for p16 and 0.0551 for Rb). This heterogeneity was not evident by stage or grade. Our data suggest a low frequency of homozygous deletion of CDKN2A (the gene that encodes p16), as well as inactivating mutations of RB1 in arsenic-induced bladder cancer, pointing to an alternate mechanism. Increased p16 expression may be indicative of hypermethylation of CDKN2A, an intensively studied mechanisms for arsenic-induced carcinogenesis. Our data provide additional evidence linking arsenic exposure and bladder cancer risk and point to alterations of the cell cycle as the relevant pathway, although the precise mechanisms need further evaluation in additional experimental and human studies.

Targeting the androgen receptor (AR) with AR degradation enhancer ASC-J9® led to increase docetaxel sensitivity via suppressing the p21 expression

Chemotherapy with docetaxel remains the effective therapy to suppress castration resistant prostate cancer (CRPC) in some patients. However, most chemotherapy with docetaxel eventually fails with the development of docetaxel resistance after 18-weeks of treatment. Here we found docetaxel treatment might have an adverse effect of increasing the androgen receptor (AR) protein level in the CRPC cells, and combining docetaxel with anti-AR therapy using AR-shRNA or the AR degradation enhancer ASC-J9® may increase docetaxel sensitivity to better suppress the CRPC cell growth. Mechanism dissection found docetaxel might have the adverse effect of increasing the AR protein stability via suppressing the AR ubiquitination due to the increased AR phosphorylation. The consequence of such increased AR protein may then lead to increase p21 expression via transcriptional regulation. Preclinical studies with in vitro cells lines also demonstrated that targeting AR with ASC-J9® led to suppressing the AR-increased p21 expression to improve the docetaxel sensitivity in the CRPC cells that already developed docetaxel resistance. Together, these results suggest that a combined therapy of docetaxel and ASC-J9® is a novel therapy to better suppress CRPC in patients that already developed docetaxel resistance.

Distinct phenotypes and 'bystander' effects of senescent tumour cells induced by docetaxel or immunomodulatory cytokines.

Cellular senescence is the process of the permanent proliferative arrest of cells in response to various inducers. It is accompanied by typical morphological changes, in addition to the secretion of bioactive molecules, including proinflammatory cytokines and chemokines [known as the senescence-associated secretory phenotype (SASP)]. Thus, senescent cells may affect their local environment and induce a so-called ‘bystander’ senescence through the state of SASP. The phenotypes of senescent cells are determined by the type of agent inducing cellular stress and the cell lineages. To characterise the phenotypes of senescent cancer cells, two murine cell lines were employed in the present study: TC-1 and B16F10 (B16) cells. Two distinct senescence inductors were used: Chemotherapeutic agent docetaxel (DTX) and a combination of immunomodulatory cytokines, including interferon γ (IFNγ) and tumour necrosis factor α (TNFα). It was demonstrated that DTX induced senescence in TC-1 and B16 tumour cell lines, which was demonstrated by growth arrest, positive β-galactosidase staining, increased p21Waf1 (p21) expression and the typical SASP capable of inducing a ‘bystander’ senescence. By contrast, treatment with a combination of T helper cell 1 cytokines, IFNγ and TNFα, induced proliferation arrest only in B16 cells. Despite the presence of certain characteristic features resembling senescent cells (proliferation arrest, morphological changes and increased p21 expression), these cells were able to form tumours in vivo and started to proliferate upon cytokine withdrawal. In addition, B16 cells were not able to induce a ‘bystander’ senescence. In summary, the present study described cell line- and treatment- associated differences in the phenotypes of senescent cells that may be relevant in optimization of cancer chemo- and immunotherapy.

Black Cumin Seed Oil Antidiabetogenic by Increasing Pancreatic P53 Expression

&lt;span lang="EN-US"&gt;Black cumin seed oil (BCSO) contains many thymoquinone and unsaturated fatty acids that act as antioxidants. Thymoquinone was thought to inhibit pancreatic damage and prevent hyperglycemia by involving p53. The study aim&lt;/span&gt;&lt;span lang="IN"&gt;ed&lt;/span&gt;&lt;span lang="EN-US"&gt; to determine the BCSO effect on Malondialdehyde&lt;/span&gt;&lt;span lang="IN"&gt; (MDA)&lt;/span&gt;&lt;span lang="EN-US"&gt; levels and p53 expression of pancreatic tissues in alloxan-induced Sprague Dawley (SD) rats. This study used Pre and Post Test with Control Group Design with 49 male Sprague Dawley rats aged 30 days weighing 150 - 300 gram. Rats were divided into 7 groups: Group I, the normal control group receiving standard feeding and drinking; Group II, the negative control group receiving alloxan; Group III &amp;amp; IV, the treatment groups, receiving BCSO with a dose of 6.9 mg/KgBW (BCSO6.8) and 68 mg/KgBW (BCSO68 group); Group V, the positive control 1 group receiving simvastatin 10 mg/KgBW; Group VI, the positive control 2 group receiving vitamin C 18 mg/200mgBW; Group VII, the solvent control receiving DMSO. The treatment groups received two different doses per day for 9 days orally. Blood MDA and glucose levels were determined by spectrophotometry and p53 expression of pancreas tissues were read by a pathologist. The results show that the BCSO68 group had a decreased activity of MDA and glucose but a higher expression of p53 in pancreatic tissues compared to the BCSO6.8 group. Decreased Malondialdehyde levels in the BCSO68 group were similar to those in the vitamin C group but lower than those in the simvastatin group (p&amp;lt;0.05). It can be concluded that the BCSO administration of 68 mg/KgBW per day can decrease blood Malondialdehyde and glucose levels and increase p53 expression. &lt;/span&gt;

Immunohistochemical Study of the Role of CK20, p53 and Ki-67 in Differentiation of Some Urothelial Lesions and Urothelial Carcinoma of the Urinary Bladder

AbstractBackground: Bladder cancer is the most common malig-nancy affecting the urinary tract. Distinguishing between urothelial dysplasia and carcinoma in situ based on histopatho-logical features alone is often difficult.Aim of Work: The aim of the current work is to distinguish between urothelial hyperplasia, urothelial dysplasia from urothelial carcinoma by using CK20, p53 and Ki-67 immu-nomarkers, determine the pattern and extent of their immuno-reactivity and correlate immuno-histochemical results with the clinicopathological parameters.Material and Methods: Fifty cases of urothelial carcinoma (38 cases) and some flat urothelial lesions (12 cases) were collected retrospectively. Tissue specimens were in the form of radical cystectomy (nine specimens) and transurethral resection of the tumor (TURT) (forty one specimens). They were stained by H&E, CK20, p53 and Ki-67 for immunohis-tochemical study. The relationship between their expression and the available clinicopathological features were evaluated.Results: CK20, p53 and Ki-67 expressions can signifi-cantly differentiate urothelial hyperplasia from urothelial dysplasia as the whole panel is negative in urothelial hyper-plasia and positive with scattered expression in urothelial dysplasia. Also pattern of expression of CK20, p53 and Ki-67 expression are suggesting for the diagnosis of either urothelial dysplasia or urothelial carcinoma in situ as their expressions show diffuse positivity throughout the urothelium in urothelial carcinoma in situ. These markers were statistically significant in grading of urothelial carcinoma as higher tumor grade associated with decreased CK20 expression and in-creased p53 and Ki-67 expression. CK20 expression was statistically significant in tumor stage as higher tumor stage was associated with decreased CK20 expression.Conclusions: Abnormal CK20 expression in urothelial cells plus overexpression of p53 and Ki-67 are indicators of dysplastic change in urothelial mucosa. A panel of CK20, p53 and Ki-67 can be a useful tool to confirm the diagnosis of CIS and can be helpful to distinguish it from dysplastic changes. Combined use of these markers may be helpful in assigning grade of urothelial carcinoma especially when histologic features are borderline.

Paclitaxel promotes lung cancer cell apoptosis via MEG3-P53 pathway activation

Paclitaxel (PTX) is a first-line chemotherapy drug for advanced non-small cell lung cancer (NSCLC). The long-chain non-coding RNA maternally expressed gene 3 (MEG3) is a recognized tumor suppressor. This study aimed to explore the effects of PTX on the expression of MEG3 and its anti-tumor mechanism in lung cancer cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays were performed to determine cell proliferation. Quantitative polymerase chain reaction was used to determine the levels of MEG3 expressions. Western blot and immunofluorescence were used to detect protein levels. Small interfering RNA or pCDNA-MEG3 transfection was used to downregulate or upregulate MEG3 expression. Dichlorof luorescein diacetate was used to detect intracellular reactive oxygen species. Flow cytometry was used to analyze apoptosis. PTX significantly inhibited the proliferation of NSCLC cells and increased the expressions of MEG3 and P53. The downregulation of MEG3 attenuated PTX-induced cytotoxicity, whereas upregulation of MEG3 induced cell death and increased P53 expression. The inhibition of P53 caused no effect on the upstream MEG3 expression. Our results suggest that the MEG3-P53 pathway is involved in the apoptosis of A549 cells induced by PTX.

Abstract A079: MicroRNA-139 regulates prostate cancer aggressiveness by targeting IGF1R

Abstract Background: Dysregulated microRNA (miRNA) expression has been implicated in prostate cancer progression. We previously identified a panel of five miRNAs associated with biochemical recurrence and metastasis following prostatectomy based on NGS-based whole miRNome discovery and qPCR-based validation analysis. In this analysis, we examine the effect of miR-139-5p, one of the downregulated miRNAs identified in the panel, in greater detail. Methods: Using a cohort of 585 patients treated with radical prostatectomy, we examined the prognostic significance of miR-139 (dichotomized around the median) using the Kaplan Meier method and Cox proportional hazard models. We validated these results using The Cancer Genome Atlas (TCGA) data. We created cell lines that overexpressed miR-139 for functional assays. Finally, we examined pathways through which miR-139 may function using prediction algorithms and confirmed targets by Western blotting and reporter assays. Results: MiR-139 downregulation was significantly associated with a variety of accepted prognostic factors in prostate cancer, including Gleason score, pathologic stage, margin positivity, and lymph node status. MiR-139 was associated with prognosis: the cumulative incidence of biochemical recurrence and metastasis was significantly lower among patients with high miR-139 expression (p=0.0004 and 0.038, respectively). After adjusting for known prognostic factors, patients with high miR-139 expression had significantly lower risk of recurrence (HR 0.77, 95% 0.58-1.04). Validation in the TCGA dataset showed a significant association between dichotomized miR-139 expression and biochemical recurrence (OR 0.52, 95% CI 0.33-0.82). Overexpression of miR-139 in PC3 and DU145 prostate cancer cells led to a significant reduction in cell proliferation and migration compared to control cells. IGF1R was identified as a potential target of miR-139 based on previous work in colorectal and non-small cell lung cancers. Reduced luciferase reporter activity was observed upon co-transfection of the 3′ UTR of IGF1Rβ with miR-139 mimic compared to co-transfection with control mimic. Furthermore, Western blotting of PC3 cells overexpressing miR-139 revealed reduced IGF1Rβ protein expression, as well as reduced expression of its downstream pathway proteins pAKT and pERK. Cell cycle analysis indicated a significantly increased number of cells arrested in G2/M phase in PC3 cells overexpressing miR-139. This was accompanied by an increase in β-galactosidase stained senescent cells and p21 protein expression. Conclusions: miR-139 is associated with improved prognosis in patients with localized prostate cancer. This appears to be mediated through an IGF1R pathway leading to increased p21 expression, resulting in prostate cancer cell senescence from G2 arrest. Citation Format: Yutaka Amemiya, Christopher J. Wallis, Tania Benatar, Elizabeth Kobylecky, Linda Sugar, Christopher Sherman, Robert Nam, Arun K. Seth. MicroRNA-139 regulates prostate cancer aggressiveness by targeting IGF1R [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A079.