Cell Cycle Regulators P21 Research Articles

Tualang honey inhibits cell proliferation and promotes apoptosis of human lung adenocarcinoma cells via apoptosis signaling pathway

IntroductionTualang honey (TH) has been shown to have anticancer properties for breast, cervical, leukaemia, oral squamous, and bone cancers. This study was aimed at investigating the anti-proliferative and apoptosis effect of TH on human lung adenocarcinoma (ADC) cells. MethodsMTT assay was used to detect the anti-proliferative effect of TH in ADC (H23 and A549) cells. Morphological changes of cells treated with TH were observed under phase-contrast and fluorescence microscopy. Flow cytometry was carried out to evaluate cell cycle progression. Annexin V-FITC assay was performed to investigate the effects of TH on the apoptosis of ADC cells. Apoptosis protein profile was detected using Human Apoptosis Antibody Array. ResultsMTT assay indicated that TH inhibited the proliferation of ADC cells in a dose-and time-dependent manner. The ADC cells treated with TH showed typical apoptotic features such as membrane blebbing, cell shrinkage, chromatin condensation and fragmented nucleus. The cell cycle analysis revealed the accumulation of TH treated ADC cells in sub-G1 and G2/M phases. Annexin V-FITC assay provided the evidence for apoptosis induction by TH. Apoptosis profiling array indicated that TH up-regulated the expression of caspases (caspase-3 and -8), pro-apoptotic (Bid, Bax, cytochrome c, SMAC), cell-surface death receptor (Fas), cell cycle regulator (p21) and tumor suppressor (p53), as well as down-regulating the expression of 2 anti-apoptotic proteins (Bcl-2 and Bcl-w) in ADC cells. ConclusionThe present study suggests TH as a potential anti-cancer agent, following its capacity to promote the growth inhibition and apoptosis of ADC cells via apoptosis signaling pathways.

Icariin affects cell cycle progression and proliferation of human retinal pigment epithelial cells via enhancing expression of H19.

BackgroundAberrant proliferation of retinal pigment epithelial (RPE) cells under pathologic condition results in the occurrence of proliferative vitreoretinopathy (PVR). Icariin (ICA)-a flavonol glucoside-has been shown to inhibit proliferation of many cell types, but the effect on RPE cells is unknown. This study aimed to clarify the inhibitory effects of ICA on RPE cells against platelet-derived growth factor (PDGF)-BB-induced cell proliferation, and discuss the regulatory function of H19 in RPE cells.MethodsMTS assay was conducted to determine the effects of ICA on cell proliferation. Flow cytometry analysis was performed to detect cell cycle progression. Quantitative real-time PCR and western blot assay were used to measure the expression patterns of genes in RPE cells.ResultsICA significantly suppressed PDGF-BB-stimulated RPE cell proliferation in a concentration-dependent manner. Moreover, since administration of ICA induced cell cycle G0/G1 phase arrest, the anti-proliferative activity of ICA may be due to G0/G1 phase arrest in RPE cells. At molecular levels, cell cycle regulators cyclin D1, CDK4, CDK6, p21 and p53 were modulated in response to treatment with ICA. Most importantly, H19 was positively regulated by ICA and H19 depletion could reverse the inhibitory effects of ICA on cell cycle progression and proliferation in PDGF-BB-stimulated RPE cells. Further mechanical explorations showed that H19 knockdown resulted in alternative expressions levels of cyclin D1, CDK4, CDK6, p21 and p53 under ICA treatment.ConclusionsOur findings revealed that ICA was an effective inhibitor of PDGF-BB-induced RPE cell proliferation through affecting the expression levels of cell cycle-associated factors, and highlighted the potential application of ICA in PVR therapy. H19 was described as a target regulatory gene of ICA whose disruption may contribute to excessive proliferation of RPE cells, suggesting that modulation of H19 expression may be a novel therapeutic approach to treat PVR.

P16 deficiency attenuates intervertebral disc degeneration by adjusting oxidative stress and nucleus pulposus cell cycle.

The cell cycle regulator p16 is known as a biomarker and an effector of aging. However, its function in intervertebral disc degeneration (IVDD) is unclear. In this study, p16 expression levels were found to be positively correlated with the severity of human IVDD. In a mouse tail suspension (TS)-induced IVDD model, lumbar intervertebral disc height index and matrix protein expression levels were reduced significantly were largely rescued by p16 deletion. In TS mouse discs, reactive oxygen species levels, proportions of senescent cells, and the senescence-associated secretory phenotype (SASP) were all increased, cell cycling was delayed, and expression was downregulated for Sirt1, superoxide dismutase 1/2, cyclin-dependent kinases 4/6, phosphorylated retinoblastoma protein, and transcription factor E2F1/2. However, these effects were rescued by p16 deletion. Our results demonstrate that p16 plays an important role in IVDD pathogenesis and that its deletion attenuates IVDD by promoting cell cycle and inhibiting SASP, cell senescence, and oxidative stress.

Combination of Decitabine and Entinostat Synergistically Inhibits Urothelial Bladder Cancer Cells via Activation of FoxO1.

Occurrence of cisplatin-resistance in bladder cancer is frequent and results in disease progression. Thus, novel therapeutic approaches are a high medical need for patients suffering from chemotherapy failure. The purpose of this study was to test the combination of the DNA methyltransferase inhibitor decitabine (DAC) with the histone deacetylase inhibitor entinostat (ENT) in bladder cancer cells with different platinum sensitivities: J82, cisplatin-resistant J82CisR, and RT-112. Intermittent treatment of J82 cells with cisplatin resulted in the six-fold more cisplatin-resistant cell line J82CisR. Combinations of DAC and/or ENT plus cisplatin could not reverse chemoresistance. However, the combination of DAC and ENT acted cytotoxic in a highly synergistic manner as shown by Chou-Talalay analysis via induction of apoptosis and cell cycle arrest. Importantly, this effect was cancer cell-selective as no synergism was found for the combination in the non-cancerous urothelial cell line HBLAK. Expression analysis indicated that epigenetic treatment led to up-regulation of forkhead box class O1 (FoxO1) and further activated proapoptotic Bim and the cell cycle regulator p21 and reduced expression of survivin in J82CisR. In conclusion, the combination of DAC and ENT is highly synergistic and has a promising potential for therapy of bladder cancer, particularly in cases with platinum resistance.

EMT transcription factor ZEB1 alters the epigenetic landscape of colorectal cancer cells

Epigenetic deregulation remarkably triggers mechanisms associated with tumor aggressiveness like epithelial–mesenchymal transition (EMT). Since EMT is a highly complex, but also reversible event, epigenetic processes such as DNA methylation or chromatin alterations must be involved in its regulation. It was recently described that loss of the cell cycle regulator p21 was associated with a gain in EMT characteristics and an upregulation of the master EMT transcription factor ZEB1. In this study, in silico analysis was performed in combination with different in vitro and in vivo techniques to identify and verify novel epigenetic targets of ZEB1, and to proof the direct transcriptional regulation of SETD1B by ZEB1. The chorioallantoic-membrane assay served as an in vivo model to analyze the ZEB1/SETD1B interaction. Bioinformatical analysis of CRC patient data was used to examine the ZEB1/SETD1B network under clinical conditions and the ZEB1/SETD1B network was modeled under physiological and pathological conditions. Thus, we identified a self-reinforcing loop for ZEB1 expression and found that the SETD1B associated active chromatin mark H3K4me3 was enriched at the ZEB1 promoter in EMT cells. Moreover, clinical evaluation of CRC patient data showed that the simultaneous high expression of ZEB1 and SETD1B was correlated with the worst prognosis. Here we report that the expression of chromatin modifiers is remarkably dysregulated in EMT cells. SETD1B was identified as a new ZEB1 target in vitro and in vivo. Our study demonstrates a novel example of an activator role of ZEB1 for the epigenetic landscape in colorectal tumor cells.

Mouse Hepatocellular Carcinoma Sensitivity to Cisplatin and Docetaxel and Analysis of Related Proteins

Hepatocellular carcinoma (HCC) globally ranked fifth common cancer and the third-leading cause of death. This study aimed to characterize the new mouse hepatocellular carcinoma cell line (HCAM) for some of the most important proteins involved in cell cycle regulation P53, HER2/neu, and EGFR by immunocytochemistry. Also, to measure the sensitivity of the cells to some common chemotherapeutic agents such as cisplatin and docetaxel by the MTT cell viability assay. The findings of immunocytochemistry appeared that HCAM cells proven to express the p53 and EGFR positively when compared with the negative control. Furthermore, showing nuclear only low expression for the HER2/neu. For evaluation of the chemotherapeutic agent’s efficiency, the cells of hepatocellular carcinoma (HCAM) were treated for 72 hours using different concentrations for Cisplatin and Docetaxel. The IC50 values of docetaxel and cisplatin after 72 h exposure for HCAM was 12.82 and 10.74 respectively. Our in vitro results demonstrate that Docetaxel and Cisplatin are toxic to HCAM cell line in a concentration-dependent manner. In conclusion, our results showed positive expression of p53, EGFR, and weak HER2/neu. Also, HCAM cell line showing to be sensitive to docetaxel and cisplatin, which inhibit cell proliferation.

Ascleposide, a natural cardenolide, induces anticancer signaling in human castration-resistant prostatic cancer through Na+ /K+ -ATPase internalization and tubulin acetylation.

Cardiac glycosides, which inhibit Na+ /K+ -ATPase, display inotropic effects for the treatment of congestive heart failure and cardiac arrhythmia. Recent studies have suggested signaling downstream of Na+ /K+ -ATPase action in the regulation of cell proliferation and apoptosis and have revealed the anticancer activity of cardiac glycosides. The study aims to characterize the anticancer potential of ascleposide, a natural cardenolide, and to uncover its primary target and underlying mechanism against human castration-resistant prostate cancer (CRPC). Cell proliferation was examined in CRPC PC-3 and DU-145 cells using sulforhodamine B assay, carboxyfluorescein succinimidyl ester staining assay and clonogenic examination. Flow cytometric analysis was used to detect the distribution of cell cycle phase, mitochondrial membrane potential, intracellular Na+ and Ca2+ levels, and reactive oxygen species production. Protein expression was examined using Western blot analysis. Endocytosis of Na+ /K+ -ATPase was determined using confocal immunofluorescence microscopic examination. Ascleposide induced an increase of intracellular Na+ and a potent antiproliferative effect. It also induced a decrease of G1 phase distribution while an increase in both G2/M and apoptotic sub-G1 phases, and downregulated several cell cycle regulator proteins, including cyclins, Cdk, p21, and p27 Cip/Kip proteins, Rb and c-Myc. Ascleposide decreased the expression of antiapoptotic Bcl-2 members (eg, Bcl-2 and Mcl-1) but upregulated proapoptotic member (eg, Bak), leading to a significant loss of mitochondrial membrane potential and activation of both caspase-9 and caspase-3. Ascleposide also dramatically induced tubulin acetylation, leading to inhibition of the catalytic activity of Na+ /K+ -ATPase. Notably, extracellular high K+ (16 mM) significantly blunted ascleposide-mediated effects. Furthermore, ascleposide induced a p38 MAPK-dependent endocytosis of Na+ /K+ -ATPase and downregulated the protein expression of Na+ /K+ -ATPase α1 subunit. Ascleposide displays antiproliferative and apoptotic activities dependent on the inhibition of Na+ /K+ -ATPase pumping activity through p38 MAPK-mediated endocytosis of Na+ /K+ -ATPase and downregulation of α1 subunit, which in turn cause tubulin acetylation and cell cycle arrest. Cell apoptosis is ultimately triggered by the activation of caspase cascade attributed to mitochondrial damage through the downregulation of Bcl-2 and Mcl-1 protein expressions while upregulation of Bak protein levels. The data also suggest the potential of ascleposide in anti-CRPC development.

ARID5B Influences Antimetabolite Drug Sensitivity and Prognosis of Acute Lymphoblastic Leukemia.

Treatment outcomes for childhood acute lymphoblastic leukemia (ALL) have improved steadily, but a significant proportion of patients still experience relapse due to drug resistance, which is partly explained by inherited and/or somatic genetic alternations. Recently, we and others have identified genetic variants in the ARID5B gene associated with susceptibility to ALL and also with relapse. In this study, we sought to characterize the molecular pathway by which ARID5B affects antileukemic drug response in patients with ALL. We analyzed association of ARID5B expression in primary human ALL blasts with molecular subtypes and treatment outcome. Subsequent mechanistic studies were performed in ALL cell lines by manipulating ARID5B expression isogenically, in which we evaluated drug sensitivity, metabolism, and molecular signaling events. ARID5B expression varied substantially by ALL subtype, with the highest level being observed in hyperdiploid ALL. Lower ARID5B expression at diagnosis was associated with the risk of ALL relapse, and further reduction was noted at ALL relapse. In isogenic ALL cell models in vitro, ARID5B knockdown led to resistance specific to antimetabolite drugs (i.e., 6-mercaptopurine and methotrexate), without significantly affecting sensitivity to other antileukemic agents. ARID5B downregulation significantly inhibited ALL cell proliferation and caused partial cell-cycle arrest. At the molecular level, the cell-cycle checkpoint regulator p21 (encoded by CDKN1A) was most consistently modulated by ARID5B, plausibly as its direct transcription regulation target. Our data indicate that ARID5B is an important molecular determinant of antimetabolite drug sensitivity in ALL, in part, through p21-mediated effects on cell-cycle progression.

KLF8 overexpression promotes the growth of human lung cancer cells by promoting the expression of JMJD2A

BackgroundNon-small-cell lung cancer (lung cancer) has become one of the leading causes worldwide and the underlying mechanism is not fully understood. The transcriptional factor Kruppel like factor 8 (KLF8) is involved in the initiation, progression, transformation, and metastasis of diverse cancers. However, the roles of KLF8 in human non-small cell lung cancer remain unknown.MethodsCCK-8 kit and colony formation assay were performed to determine the cell growth of lung cancer cells. Flow cytometry analysis was used to evaluate apoptosis and cell cycle of lung cancer cells. Luciferase reporter assay was used to examine the activation of JMJD2A promoter by KLF8. Chromatin immunoprecipitation assay was performed to evaluate the binding of KLF8 to JMJD2A promoter. Western blot and polymerase chain reaction were applied to analyze the expression of interested genes.ResultsThe mRNA and protein levels of KLF8 in human non-small cell lung cancer tissues were overexpressed compared with the non-cancer tissues. KLF8 was knocked down with lentivirus-mediated short-hairpin RNA (shRNA) in human lung cancer cells (A549 and H1299 cells). The phenotypic results showed that KLF8 knockdown decreased the proliferation rate and colony formation of lung cancer cells. By contrast, lentivirus-mediated KLF8 overexpression promoted the growth of lung cancer cells (A549 and H1299 cells) and non-cancerous bronchial epithelial cell line BEAS-2B. Next, we showed that KLF8 regulated cell cycle at the G0 phase but not regulates cellular apoptosis of lung cancer cells. KLF8 regulated the expression of the cell cycle regulators P21 and CDK4 in a JMJD2A-dependent manner and JMJD2A knockdown significantly blocked the functions of KLF8 in regulating cell cycle and proliferation of lung cancer cells. Finally, we observed that KLF8 bound the promoter of JMJD2A and facilitated the expression of JMJD2A.ConclusionsOur evidence demonstrated that KLF8 upregulation in human lung cancer promotes the cell proliferation and colony formation of lung cancer cells. KLF8 binds to the promoter of JMJD2A and subsequently regulates the expression of P21 and CDK4, which contributes to the regulation of cell cycle by KLF8. KLF8 may serve as a target for the treatment of human lung cancer.

Role of polypyrimidine tract-binding protein 1/yin yang 2 signaling in regulating vascular smooth muscle cell proliferation and neointima hyperplasia

Abnormal proliferation of vascular smooth muscle cells (VSMCs) is a hallmark of vascular restenosis. We investigated whether polypyrimidine tract-binding protein 1 (PTBP1), a novel regulator of cell proliferation and differentiation, is implicated in VSMC proliferation and neointima hyperplasia responding to injury. C57BL/6 J mice of 10–12 weeks old were randomly divided into sham and carotid artery injury group. Primary VSMCs obtained from thoracic aortas of 10- to 12-week-old mice were treated with physiological saline and platelet derived growth factor-BB (PDGF-BB). Adenovirus expressing shCon, shPTBP1 or shYY2 were transfected into the injured common carotid artery or VSMCs. qRT-PCR and immunoblotting were used to determine the mRNA and protein expression levels, respectively. Immunohistochemical staining of H&E and Ki-67 were used to evaluate restenosis of vessels. Cell counting kit-8 assay and Ki-67 immunofluorescent staining were utilized to evaluate the rate of VSMC proliferation. The expression of PTBP1 were upregulated both in injured arteries and in PDGF-BB-treated VSMCs. PTBP1 inhibition significantly attenuated neointima hyperplasia and Ki-67 positive area induced by injury. Knockdown of PTBP1 in vitro also suppressed VSMC proliferation after PDGF-BB treatment. The effects of PTBP1 inhibition mentioned above were all abolished by knockdown of YY2. Finally, we identified four cell cycle regulators (p53, p21, Cdkn1c, Cdkn2b) that were regulated by PTBP1/YY2 axis both in vitro and in vivo. These findings demonstrated that PTBP1 is a critical regulator of VSMC proliferation and neointima hyperplasia via modulating the expression of YY2.

Peripheral antibody concentrations are associated with highly differentiated T cells and inflammatory processes in the human bone marrow

BackgroundAntigen-experienced immune cells migrate back to the bone marrow (BM), where they are maintained in BM survival niches for an extended period. The composition of T cell subpopulations in the BM changes with age, leading to an accumulation of highly differentiated T cells and a loss of naïve T cells. While innate immune cells are also affected by age, little is known about interactions between different adaptive immune cell populations maintained in the BM. In this study, the phenotype and function of innate and adaptive immune cells isolated from human BM and peripheral blood (PB) was analysed in detail using flow cytometry, to determine if the accumulation of highly differentiated T and B cells, supported by the BM niches, limits the maintenance of other immune cells, or affects their functions such as providing protective antibody concentrations.ResultsTotal T cells increase in the BM with age, as do highly differentiated CD8+ T cells which no longer express the co-stimulatory molecule CD28, while natural killer T (NKT) cells, monocytes, B cells, and naïve CD8+ T cells all decrease in the BM with age. A negative correlation of total T cells with B cells was observed in the BM. The percentage of B cells in the BM negatively correlated with highly differentiated CD8+CD28− T cells, replicative-senescent CD8+CD57+ T cells, as well as the CD8+CD28−CD57+ population. Similar correlations were seen between B cells and the frequency of highly differentiated T cells producing pro-inflammatory molecules in the BM. Interestingly, plasma concentrations of diphtheria-specific antibodies negatively correlated with highly differentiated CD8+CD57+ T cells as well as with exhausted central memory CD8+ and CD4+ T cells in the BM. A negative impact on diphtheria-specific antibodies was also observed for CD8+ T cells expressing senescence associated genes such as the cell cycle regulator p21 (CDKN1A), KLRG-1, and elevated levels of reactive oxygen species (ROS).ConclusionOur data suggest that the accumulation and maintenance of highly differentiated, senescent, and exhausted T cells in the BM, particularly in old age, may interfere with the survival of other cell populations resident in the BM such as monocytes and B cells, leading to reduced peripheral diphtheria antibody concentrations as a result. These findings further highlight the importance of the BM in the long-term maintenance of immunological memory.

Abstract 4805: Cannabinoid WIN 55,212-2 induces endoplasmic reticulum stress in prostate cancer cells through CB1and CB2receptors

Abstract Cannabinoids have demonstrated anticarcinogenic properties in a variety of malignancies, including prostate cancer. WIN 55,212-2 (WIN) is a highly potent synthetic cannabinoid that binds to cannabinoid receptors (CB1 and CB2). We have previously demonstrated that WIN significantly reduces prostate cancer cell proliferation, migration, invasion, induces apoptosis, and arrests cells in the G0/G1 phase through a cannabinoid receptor 2 dependent manner. We also determined that these effects were mediated though a pathway involving cell cycle regulators p27, Cdk4, and pRb. The current study aims to examine the role of endoplasmic reticulum (ER) stress in apoptosis and investigates whether this effect is modulated by WIN and the cannabinoid receptors. In this study, we evaluated the effect of WIN and CB receptors on ER stress induced apoptosis in established prostate cancer cells (DU145, PC3). Cells were treated with WIN, cannabinoid receptor 1 antagonist (AM251), and cannabinoid receptor 2 antagonist (AM630). Cell proliferation was determined using MTS assays. Quantitative PCR was used to examine changes in expression of ER stress related genes, including CHOP, TRIB3, and ATF4. Western blotting will be completed to determine changes in the expression of apoptotic markers after treatment with WIN and cannabinoid antagonists. Further studies are ongoing looking at the use of the ER stress inhibitor, Salubrinal, to determine whether ER stress is vital for WIN-induced apoptosis. Our results reveal that treatment with 20μM WIN resulted in a significant reduction in the proliferation of DU145 and PC3 cells after 24 h compared to control (p<0.05). In contrast, treatment with 5μM of either AM251 or AM630 did not result in any significant changes in cell proliferation. Quantitative PCR studies revealed significant upregulation of ER stress genes CHOP, TRIB3 and ATF4 in WIN treated cells (p<0.05). Expression of ER stress genes were significantly downregulated after blocking CB1 and CB2 receptors (p<0.05). Interim results suggest that WIN has significant antitumoral activity and modulates ER stress-induced apoptosis in prostate cancer cells, thus, may offer a novel therapeutic strategy in the treatment of prostate cancer. Citation Format: Domenica Roberto, Laurence H. Klotz, Vasundara Venkateswaran. Cannabinoid WIN 55,212-2 induces endoplasmic reticulum stress in prostate cancer cells through CB1and CB2receptors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4805.

Abstract 4647: Keratinocyte specific deletion of TWIST1 promotes differentiation and inhibits UVB-induced hyperproliferation

Abstract Non-melanoma skin cancers (NMSC) have one of the highest incidences in the United States with over 5 million diagnoses every year. The major risk factor for the development of NMSC is solar ultraviolet radiation consisting of both UVA and UVB. In epidermal keratinocytes, UV radiation results in DNA damage as well as deregulation of both proliferative and survival signaling pathways that contribute to tumorigenesis. The transcription factor TWIST1 has been reported to be essential for the formation and invasiveness of chemically-induced tumors in skin. TWIST1 deletion in mouse epidermis results in arrested cell cycle progression in response to treatment with the tumor promoter, TPA, which in turn prevents skin tumor growth in two-stage skin carcinogenesis assays. However, the impact of the keratinocyte specific TWIST1 deletion on skin carcinogenesis caused by UV radiation has not been clarified. In preliminary experiments, we found that primary mouse keratinocytes with TWIST1 knockout (KO) displayed an increase in the G2/M phase population after a single exposure to 20mJ/cm2 of UVB radiation. Accordingly, protein levels of cell cycle regulator p21 increased while those of pMDM2 decreased after UVB exposure. Moreover, we found that primary mouse keratinocytes with TWIST1 KO displayed an increase in apoptosis as shown by augmented Annexin V staining that corresponded with the reduction in levels of anti-apoptotic regulators Bcl-2 and Bcl-XL and concomitant upregulation of cleaved PARP and cleaved caspase-7 after UVB exposure. Furthermore, deletion of TWIST1 in skin keratinocytes in vivo (using K5-Cre x TWIST1flox/flox mice) led to a significant reduction in UVB-induced epidermal hyperproliferation compared to wild-type mice assessed by both Ki67 immunofluorescence staining as well as BrdU incorporation. Additionally, the protein level for p21 was increased while the levels of c-myc, and Cyclin B1 were reduced in the TWIST1 deficient keratinocytes in vivo. Interestingly, expression of differentiation markers such as Loricrin, Keratin-10, Sca-1, and transglutaminase-1 were also increased in the epidermis of TWIST1 deficient mice. These results from the in vivo model show that TWIST1 deletion results in an interruption of UVB-induced hyperproliferation via cell cycle arrest and induction of keratinocyte differentiation. Collectively, our findings indicate that the deficiency of TWIST1 has significant effects on the proliferation, survival and differentiation of keratinocytes; processes important for UVB skin tumor development. Future experiments will continue to assess the changes in oncogenic signaling in epidermal keratinocytes in response to UVB exposure and further investigate the impact of the deletion of TWIST1 on UV-induced skin carcinogenesis. Research supported by CPRIT 2018 Grant RP150247 and by CONACYT Fellowship 671661. Citation Format: Fernando Eguiarte-Solomon, Okkyung Rho, John DiGiovanni. Keratinocyte specific deletion of TWIST1 promotes differentiation and inhibits UVB-induced hyperproliferation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4647.

Betulin-1,4-quinone hybrids: Synthesis, anticancer activity and molecular docking study with NQO1 enzyme

Betulin-1,4-quinone hybrids were obtain by connecting two active structures with a linker. This strategy allows for obtaining compounds showing a high biological activity and better bioavailability. In this research, synthesis, anticancer activity and molecular docking study of betulin-1,4-quinone hybrids are presented. Newly synthesized compounds were characterized by 1H, 13C NMR, IR and HR-MS. Hybrids were tested in vitro against a panel of human cell lines including glioblastoma, melanoma, breast and lung cancer. They showed a high cytotoxic activity depending on the type of 1,4-quinone moiety and the applied tumor cell lines. It was found that cytotoxic activities of the studied hybrids were increasing against the cell line with higher NQO1 protein level, like melanoma (C-32), breast (MCF-7) and lung (A-549) cancer. Selected hybrids were tested on the transcriptional activity of the gene encoding a proliferation marker (H3 histone), a cell cycle regulators (p53 and p21) and an apoptosis pathway (BCL-2 and BAX). The obtained results suggested that the tested compounds caused a mitochondrial apoptosis pathway in A549 and MCF-7 cell lines. The molecular docking was used to examine the probable interaction between the hybrids and human NAD[P]H-quinone oxidoreductase (NQO1) protein. The computational studies showed that the type of the 1,4-quinone moiety affected the location of the compound in the active site of the enzyme. Moreover, it was shown that an interaction of 1,4-quinone fragment with the hydrophobic matrix of the active site near Tyr128, Phe178, Trp105 and FAD cofactor could explain the observed increase of TP53 gene expression.

MiR‑221‑3p promotes the cell growth of non‑small cell lung cancer by targeting p27.

Emerging evidence suggests the critical function of microRNAs in regulating the growth of cancer cells. In the present study, it was demonstrated that miR-221-3p was overexpressed in non-small cell lung cancer (NSCLC) tissues and cell lines compared with that noted in the normal controls. Downregulation of miR-221-3p suppressed the proliferation, colony formation and invasion of NSCLC cells. To further understand the molecular mechanisms underlying the potential oncogenic function of miR-221-3p in NSCLC, the downstream targets of miR-221-3p were predicted using bioinformatic databases. The prediction suggested the cell cycle regulator p27 as one of the targets of miR-221-3p. Molecular experiments showed that miR-221-3p was able to bind with the 3′-untranslated region (UTR) of p27 and decreased the expression of p27 in NSCLC cells. Consistent with the suppressive role of p27 in controlling cell cycle progression, overexpression of miR-221-3p decreased the expression of p27 and promoted cell cycle progression from G1 to S phase. Collectively, our findings identified miR-221-3p as a novel regulator of NSCLC cell growth via modulating the expression of p27.

SAT-568 Glutamine Metabolism Is a New Potential Therapeutic Target in Aggressive Thyroid Cancer

Thyroid cancer is the most frequent endocrine tumor. BRAF mutation is the most frequent alteration in thyroid cancer. The metabolic consequences of these mutations is unknown. Recent studies have suggested a pro-metastatic role of the metabolic processes in several solid malignancies. The aim of this study is to identify the metabolic pathways dysregulated in thyroid carcinogenesis with oncogenic mutations. BRAFV600Einduced HEK293 cells underwent a metabolomic profiling via mass spectrometry, which showed an increase in glutamine metabolism. Glutaminolysis, a dysregulated metabolic pathway is initiated by glutaminase (GLS), which converts glutamine to glutamate. Analysis of GLS expression in thyroid cancer tissue revealed an increase of GLS within the tumor compared to normal tissue. GEO dataset analysis revealed higher GLS expression in undifferentiated thyroid tumors compared to differentiated cancer and normal tissue (p=0.0001, p<0.0001). TCGA analysis further bolstered the findings and showed high GLS level in BRAF mutated tumors compared to wild-type (p<0.0001), that was associated with more aggressive clinico-pathological features (tumor size (p<0.0001) and high stage (p=0.0029)). To analyze the role of BRAFV600E in regulating GLS expression, two BRAF-mutated cell lines (8505c and BCPAP) were treated with increasing concentration (5, 10 and 15 µM) of BRAFV600E inhibitor, PLX4720 that showed a reduction of GLS and p-MEK expression. To identify the role of glutaminolysis in cancer cell growth, we carried out cell growth assay in three cancer cell lines (BCPAP and 8505c with BRAFV600E,TPC1 with BRAFwild-type) in the presence of increasing concentration of the pharmacological inhibitor of GLS CB-839 (10, 100, 500 and 2000 nM). CB-839 significantly reduced the cell growth at nanomolar concentrations. In order to test the metabolic consequences of glutaminase inhibition, the rate of mitochondrial respiration was assessed. CB-839 treated cells had significantly lower basal oxygen consumption rate and mitochondrial respiratory capacity. To further investigate the pathways mediating the effects of glutaminolysis in thyroid carcinogenesis we analyzed the expression profile of phospho-kinases and apoptosis related-proteins. Our findings showed that the treatment of BRAF mutated thyroid cancer cells with CB-839 for 48 hours reduced the phosphorylation of mTORS2448, ERK1/2T202/Y204,T185/Y187,SRCY419/FAKY397. These kinases regulate carcinogenesis and cell growth. In addition, CB-839 treatment increased the key cell cycle regulator p21,and the pro-apoptotic proteins Bad and Bcl2. Our data suggest a role of glutamine metabolism in thyroid carcinogenesis and its association with oncogenic activation. To validate our findings in vivo, CB-839 will be combined with PLX4720. This combination may be an effective strategy to inhibit thyroid cancer progression.

Survival/Adaptation of Bone Marrow-Derived Mesenchymal Stem Cells After Long-Term Starvation Through Selective Processes.

After in vivo transplantation, mesenchymal stem cells (MSC) face an ischemic microenvironment, characterized by nutrient deprivation and reduced oxygen tension, which reduces their viability and thus their therapeutic potential. Therefore, MSC response to models of in vitro ischemia is of relevance for improving their survival and therapeutic efficacy. The aim of this study was to understand the survival/adaptive response mechanism that MSC use to respond to extreme culture conditions. Specifically, the effect of a long-term starvation on human bone marrow (hBM)-derived MSC cultured in a chemically defined medium (fetal bovine serum-free [SF] and human SF), either in hypoxic or normoxic conditions. We observed that hBM-MSC that were isolated and cultured in SF medium and subjected to a complete starvation for up to 75 days transiently changed their behavior and phenotype. However, at the end of that period, hBM-MSC retained their characteristics as determined by their morphology, DNA damage resistance, proliferation kinetic, and differentiation potential. This survival mode involved a quiescent state, confirmed by increased expression of cell cycle regulators p16, p27, and p57 and decreased expression of proliferating cell nuclear antigen (PCNA), Ki-67, mTOR, and Nanog. In addition, Jak/STAT (STAT6) antiapoptotic activity selected which cells conserved stemness and that supported metabolic, bioenergetic, and scavenging requirements. We also demonstrated that hBM-MSC exploited an autophagic process which induced lipid β-oxidation as an alternative energy source. Priming MSC by concomitant starvation and culture in hypoxic conditions to induce their quiescence would be of benefit to increase MSC survival when transplanted in vivo. Stem Cells 2019;37:813-827.

CircRNA has_circ_0078710 acts as the sponge of microRNA-31 involved in hepatocellular carcinoma progression

Circular RNAs (circRNAs) as new types of endogenous non-coding RNAs have been recently identified important roles in certain types of pathological responses, and in the occurrence and progression of a variety of human malignancies. In the present study, we aimed to evaluate the role of has_circ_0078710, which is back spliced by THBS2 gene in hepatocellular carcinoma (HCC). Expression levels of has_circ_0078710 were tested in both HCC tissue samples and cells using real-time qRT-PCR. Has_circ_0078710 was significantly unregulated in HCC tissues and cells. Moreover, HCC patients with high level of has_circ_0078710 had the advance stage (TNM III–IV). Finally, we constructed an interaction network among circRNA-miRNA-mRNA and we identified miR-31 as the has_circ_0078710-associatedmiRNA. Furthermore, overexpression of has_circ_0078710 in HCC could up-regulate HDAC and CDK2 levels by sponging miR-31, simultaneously mediating the expression of cell cycle components (cyclin A, cyclin D1, CDK4) and negative cell cycle regulator p21. In vitro and in vivo functional studies showed that overexpression of has_circ_0078710 in HepG2, SMMC-7721 cell lines significantly promoted cell proliferation, migration, invasion and tumor growth by inducing the cell cycle progression. In summary, we identified Has_circ_0078710 as a potential HCC biomarker.

Retinoic acid-induced survival effects in SH-SY5Y neuroblastoma cells.

Neuroblastoma is a malignant childhood cancer arising from the embryonic sympathoadrenal lineage of the neural crest. Retinoic acid (RA) is included in the multimodal therapy of patients with high-risk neuroblastoma to eliminate minimal residual disease. However, the formation of RA-resistant cells substantially lowers 5-year overall survival rates. To examine mechanisms that lead to treatment failure, we chose human SH-SY5Y cells, which are known to tolerate incubation with RA by activating the survival kinases Akt and extracellular signal-regulated kinase 1/2. Characterization of downstream pathways showed that both kinases increased the phosphorylation of the ubiquitin ligase mouse double minute homolog 2 (Mdm2) and thereby enhanced p53 degradation. When p53 signaling was sustained by blocking complex formation with Mdm2 or enhancing c-Jun N-terminal kinase (JNK) activation, cell viability was significantly reduced. In addition, Akt-mediated phosphorylation of the cell-cycle regulator p21 stimulated complex formation with caspase-3, which also contributed to cell protection. Thus, treatment with RA augmented survival signaling and attenuated basal apoptotic pathways in SH-SY5Y cells, which increased cell viability.

Cannabinoid WIN 55,212-2 induces cell cycle arrest and apoptosis, and inhibits proliferation, migration, invasion, and tumor growth in prostate cancer in a cannabinoid-receptor 2 dependent manner.

Cannabinoids have demonstrated anticarcinogenic properties in a variety of malignancies, including in prostate cancer. In the present study, we explored the anti-cancer effects of the synthetic cannabinoid WIN 55,212-2 (WIN) in prostate cancer. Established prostate cancer cells (PC3, DU145, LNCaP) were treated with varying concentrations of WIN. Cell proliferation was determined by the MTS assay. The anti-migration and anti-invasive potential of WIN was examined by the wound healing assay and the matrigel invasion assay. Cell cycle analysis was performed by flow cytometry, and mechanistic studies were performed by Western blot. Athymic mice (n = 10) were inoculated with human PC3 cells. Once tumors reached 100 mm3 , animals were randomized into two groups: saline control and WIN (5 mg/kg), delivered by intraperitoneal injection three times per week for 3 weeks. WIN significantly reduced prostate cancer cell proliferation, migration, invasion, induced apoptosis, and arrested cells in Go/G1 phase in a dose-dependent manner. Mechanistic studies revealed these effects were mediated through a pathway involving cell cycle regulators p27, Cdk4, and pRb. Pre-treatment with a CB2 antagonist, AM630, followed by treatment with WIN resulted in a reversal of the anti-proliferation and cell cycle arrest previously seen with WIN alone. In vivo, administration of WIN resulted in a reduction in the tumor growth rate compared to control (P < 0.05). The following study provides evidence supporting the use of WIN as a novel therapeutic for prostate cancer.