4-Hydroxynonenal modulation of p53 family gene expression in the SK-N-BE neuroblastoma cell line

4-Hydroxynonenal (HNE), a product of lipid peroxidation, inhibits proliferation of several tumor cells. The p53 tumor suppressor protein plays a critical role in cell cycle control, by inducing p21 expression, and in apoptosis, by inducing bax expression. Recently, two other proteins with many p53-like properties, TAp73 (p73) and TAp63 (p63), have been discovered. SK-N-BE human neuroblastoma cells express the three p53 family proteins and can be used for the study of their induction. We investigated HNE action in the control of proliferation, differentiation, and apoptosis in SK-N-BE cells and the HNE effect on the expression of p53, p63, p73, p21, bax, and G1 cyclins. Retinoic acid (RA) was used as a positive control. HNE inhibited cell proliferation without inducing differentiation; it decreased S-phase cells and increased the number of apoptotic cells. RA reduced the proportion of S-phase cells and did not induce apoptosis. HNE increased p53, p73, p63, p21, and bax expression at different time points. HNE reduced cyclin D2 expression and the phosphorylation of pRb protein. Our results demonstrated that HNE inhibits SK-N-BE cell proliferation by increasing the expression of p53 family proteins and p53 target proteins which modulate cell cycle progression and apoptosis.     

Tumor suppressor miR-139-5p targets Tspan3 and regulates the progression of acute myeloid leukemia through the PI3K/Akt pathway

Dysregulation of microRNAs is closely implicated in the initiation and progression of human cancers including acute myeloid leukemia (AML). Though miR-139-5p was reported to be a potent tumor suppressor in adult AML, its underlying molecular mechanism in AML remains to be further defined. Herein, quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analysis were conducted to determine the expressions of miR-139-5p and tetraspanin3 (Tspan3) in AML patients and cells. Luciferase reporter assay, qRT-PCR, and Western blot analysis were carried out to detect the interaction between miR-139-5p and Tspan3. Cell proliferation, cell cycle distribution, invasion, and migration were evaluated by cell counting kit-8, flow cytometry, transwell invasion, and migration assays, respectively. Western blot analysis was conducted to determine phosphorylated-protein kinase B (Akt) and Akt levels. We found that a significant reduction in miR-139-5p expression and a prominent increase in Tspan3 expression were observed in AML patients and cells. Tspan3 was confirmed as a direct target of miR-139-5p and was negatively modulated by miR-139-5p. Rescue experiments showed that overexpression of miR-139-5p constrained cell proliferation, invasion and migration capabilities, and induced cell cycle arrest at the S phase in AML cells, which were partially reversed by Tspan3 overexpression. In addition, we found that miR-139-5p suppressed the phosphoinositide 3-kinase (PI3K)/Akt pathway in AML cells by targeting Tspan3. In conclusion, our study concluded that miR-139-5p suppressed the leukemogenesis in AML cells by targeting Tspan3 through inactivation of the PI3K/Akt pathway, providing a better understanding of AML progression.     

LukS-PV induces cell cycle arrest and apoptosis through p38/ERK MAPK signaling pathway in NSCLC cells

Non-small-cell lung cancer (NSCLC) accounts for nearly 85% of lung cancer cases. LukS-PV, one of the two components of Panton-Valentine leucocidin (PVL), is produced by Staphylococcus aureus. The present study showed that LukS-PV can induce apoptosis in human acute myeloid leukemia (AML) lines (THP-1 and HL-60). However, the role of LukS-PV in NSCLC is unclear. In this study, we treated NSCLC cell lines A549 and H460 and a normal lung cell line, 16HBE, with LukS-PV and investigated the biological roles of LukS-PV in NSCLC. Cells were treated with varying concentrations of LukS-PV and cell viability was evaluated by CCK8 and EdU assay. Flow cytometry was used to detect cell apoptosis and analyze the cell cycle, and the expression of apoptosis and cell cycle-associated proteins and genes were identified by western blotting analysis and qRT-polymerase chain reaction, respectively. We found that LukS-PV inhibited the proliferation of NSCLC cells but had little cytotoxicity in normal lung cells. LukS-PV induced NSCLC cell apoptosis and increased the BAX/BCL-2 ratio, triggering S-phase arrest in A549 and H460 cells while increasing P21 expression and decreasing CDK2, cyclin D1, and cyclin A2 expression. We also observed increased P-p38 and P-ERK in NSCLC cells treated with LukS-PV. Treatment of NSCLC with LukS-PV combined with p38 and ERK inhibitors reversed the pro-apoptotic and pro-cell cycle arrest effects of LukS-PV. Overall, these findings indicate that LukS-PV has anti-tumor effects in NSCLC and may contribute to the development of anti-cancer agents.     

Human Surfactant Protein D Alters Oxidative Stress and HMGA1 Expression to Induce p53 Apoptotic Pathway in Eosinophil Leukemic Cell Line

Surfactant protein D (SP-D), an innate immune molecule, has an indispensable role in host defense and regulation of inflammation. Immune related functions regulated by SP-D include agglutination of pathogens, phagocytosis, oxidative burst, antigen presentation, T lymphocyte proliferation, cytokine secretion, induction of apoptosis and clearance of apoptotic cells. The present study unravels a novel ability of SP-D to reduce the viability of leukemic cells (eosinophilic leukemic cell line, AML14.3D10; acute myeloid leukemia cell line, THP-1; acute lymphoid leukemia cell lines, Jurkat, Raji; and human breast epithelial cell line, MCF-7), and explains the underlying mechanisms. SP-D and a recombinant fragment of human SP-D (rhSP-D) induced G2/M phase cell cycle arrest, and dose and time-dependent apoptosis in the AML14.3D10 eosinophilic leukemia cell line. Levels of various apoptotic markers viz. activated p53, cleaved caspase-9 and PARP, along with G2/M checkpoints (p21 and Tyr15 phosphorylation of cdc2) showed significant increase in these cells. We further attempted to elucidate the underlying mechanisms of rhSP-D induced apoptosis using proteomic analysis. This approach identified large scale molecular changes initiated by SP-D in a human cell for the first time. Among others, the proteomics analysis highlighted a decreased expression of survival related proteins such as HMGA1, overexpression of proteins to protect the cells from oxidative burst, while a drastic decrease in mitochondrial antioxidant defense system. rhSP-D mediated enhanced oxidative burst in AML14.3D10 cells was confirmed, while antioxidant, N-acetyl-L-cysteine, abrogated the rhSP-D induced apoptosis. The rhSP-D mediated reduced viability was specific to the cancer cell lines and viability of human PBMCs from healthy controls was not affected. The study suggests involvement of SP-D in host’s immunosurveillance and therapeutic potential of rhSP-D in the eosinophilic leukemia and cancers of other origins.     

Overexpression miR-520a-3p inhibits acute myeloid leukemia progression via targeting MUC1

BackgroundAcute myeloid leukemia (AML) is one of the familiar malignant tumors in the hematological system. miR-520a-3p is reported to be involved in several cancers’ progression. However, miR-520a-3p role in AML remains unclear. In this study, we aimed to clarify the role and potential mechanism of miR-520a-3p in AML.MethodsCell viability, proliferation, cycle and apoptosis were detected by MTT assay, colony formation assay, flow cytometry, respectively. The levels of PNCA, Bcl-2, Cleaved caspase 3, Cleaved caspase 9 and β-catenin protein were detected by Western blot. Dual-luciferase reported assay was performed to detect the regulation between miR-520a-3p and MUC1. To verify the effect of miR-520a-3p on tumor proliferation in vivo, a non-homogenous transplant model of tumors was established.ResultsmiR-520a-3p expression was down-regulated, and MUC1 expression was up-regulated in AML patients. miR-520a-3p overexpression suppressed THP-1 cell proliferation, induced cell cycle G0/G1 inhibition and promoted apoptosis. miR-520a-3p targeted MUC1 and negatively regulated its expression. MUC1 knockdown inhibited THP-1 cell proliferation and promoted apoptosis. miR-520a-3p overexpression inhibited AML tumors growth.ConclusionOverexpression miR-520a-3p inhibited AML cell proliferation, and promoted apoptosis via inhibiting MUC1 expression and repressing Wnt/β-catenin pathway activation.     

Musashi-2 Silencing Exerts Potent Activity against Acute Myeloid Leukemia and Enhances Chemosensitivity to Daunorubicin

RNA-binding protein Musashi-2 (Msi2) is known to play a critical role in leukemogenesis and contributes to poor clinical prognosis in acute myeloid leukemia (AML). However, the effect of Msi2 silencing on treatment for AML still remains poorly understood. In this study, we used lentivirus-mediated RNA interference targeting Msi2 to investigate the resulting changes in cellular processes and the underlying mechanisms in AML cell lines as well as primary AML cells isolated from AML patients. We found that Msi2 was highly expressed in AML cells, and its depletion inhibited Ki-67 expression and resulted in decreased in vitro and in vivo proliferation. Msi2 silencing induced cell cycle arrest in G0/G1 phase, with decreased Cyclin D1 and increased p21 expression. Msi2 silencing induced apoptosis through down-regulation of Bcl-2 expression and up-regulation of Bax expression. Suppression of Akt, Erk1/2 and p38 phosphorylation also contributed to apoptosis mediated by Msi2 silencing. Finally, Msi2 silencing in AML cells also enhanced their chemosensitivity to daunorubicin. Conclusively, our data suggest that Msi2 is a promising target for gene therapy to optimize conventional chemotherapeutics in AML treatment.     

miR-345-5p regulates proliferation,cell cycle,and apoptosis of acute myeloid leukemia cells by targeting AKT2

Acute myeloid leukemia (AML) is a malignant clonal hematopoietic disease, which is caused by hematopoietic stem cell abnormalities. Epigenetic regulation, especially of microRNAs (miRNAs), mostly results from external or environmental effects and is critical to AML. In this study, for the first time, we report that decreased expression of miR-345-5p facilitates the proliferation of leukemia cells in AML. Further study demonstrated that AKT1/2 was the target of miR-345-5p and was responsible for the dysregulation of leukemia cell proliferation and apoptosis. Inhibition of AKT1/2 ameliorated this malignant effect, which provides new insight into AML diagnosis, treatment, prognosis, and next-step translational investigations.     

Nox2 regulates endothelial cell cycle arrest and apoptosis via p21cip1 and p53

Endothelial cells (EC) express constitutively two major isoforms (Nox2 and Nox4) of the catalytic subunit of NADPH oxidase, which is a major source of endothelial reactive oxygen species. However, the individual roles of these Noxes in endothelial function remain unclear. We have investigated the role of Nox2 in nutrient deprivation-induced cell cycle arrest and apoptosis. In proliferating human dermal microvascular EC, Nox2 mRNA expression was low relative to Nox4 (Nox2:Nox4 approximately 1:13), but was upregulated 24 h after starvation and increased to 8+/-3.5-fold at 36 h of starvation. Accompanying the upregulation of Nox2, there was a 2.28+/-0.18-fold increase in O2.- production, a dramatic induction of p21cip1 and p53, cell cycle arrest, and the onset of apoptosis (all p<0.05). All these changes were inhibited significantly by in vitro deletion of Nox2 expression and in coronary microvascular EC isolated from Nox2 knockout mice. In Nox2 knockout cells, although there was a 3.8+/-0.5-fold increase in Nox4 mRNA expression after 36 h of starvation (p<0.01), neither O2.- production nor the p21cip1 or p53 expression was increased significantly and only 0.46% of cells were apoptotic. In conclusion, Nox2-derived O2.-, through the modulation of p21cip1 and p53 expression, participates in endothelial cell cycle regulation and apoptosis.     

Silencing of lncRNA UCA1 curbs proliferation and accelerates apoptosis by repressing SIRT1 signals by targeting miR‐204 in pediatric AML

The long noncoding RNA urothelial carcinoma‐associated 1 (UCA1) has been reported to sustain the proliferation of acute myeloid leukemia (AML) cells through downregulating cell cycle regulators p27^kip1. Yet, the foundational mechanism of UCA1 in AML pathologies remains unclear. Herein, we found an escalation of UCA1 expression and suppression of miR‐204 expression in pediatric AML patients and cells. UCA1 silencing suppressed cell proliferative abilities, promoted apoptotic rates, decreased Ki67, and increased cleaved caspase‐3 in AML cells. Moreover, UCA1 sponged miR‐204 and suppressed its expression. UCA1 overexpression inversed the miR‐204 suppressed proliferation and promoted apoptosis. UCA1 also boosted the expression of SIRT1, a miR‐204 target, via the sponging interaction. Furthermore, miR‐204 inhibited inducible nitric oxide synthase and cyclooxygenase‐2 expression, while UCA1 overexpression inversed the inhibitory effects in AML cells. Our findings concluded that UCA1 downregulation repressed cell proliferation and promoted apoptosis through inactivating SIRT1 signals by upregulating miR‐204 in pediatric AML.     

lncRNA SNHG3 facilitates acute myeloid leukemia cell growth via the regulation of miR-758-3p/SRGN axis

Small nucleolar RNA host gene 3 (SNHG3) is a newly identified long non-coding RNA whose dysregulation has been reported in several cancers. However, the details about clinical significances and biological functions of SNHG3 on acute myeloid leukemia (AML) remain covered. In this study, we revealed increased SNHG3 expression in AML samples and cells and its high potential as a prognostic biomarker for AML patients. Likewise, serglycin (SRGN), which plays an important role in granule-mediated apoptosis, was previously verified to be upregulated in AML and confirmed again by the present study, and its upregulation predicted poor outcomes in AML. Furthermore, knockdown of SNHG3 or SRGN inhibited cell proliferation and induced cell apoptosis. Besides, silencing SNHG3 noticeably decreased the expression of SRGN in AML cells. Moreover, we uncovered that SNHG3 modulated SRGN expression by competitively binding with miR-758-3p. Importantly, both miR-758-3p suppression and SRGN overexpression could mitigate the inhibitory effects of SNHG3 depletion on AML cell growth. Intriguingly, the higher SRGN expression in AML samples with a higher SNHG3 level exhibited an enhanced Ki67 level but a reduced caspase 3 level. To sum up, SNHG3 elicits a growth-promoting function in AML via sponging miR-758-3p to regulate SRGN expression, providing a new therapeutic road for AML patients.     

Overexpression of p73 causes apoptosis in vascular smooth muscle cells

Abnormal vascular smooth muscle (VSM) cell proliferation contributes to the development of atherosclerosis and its associated disorders, including angioplasty restenosis. The tumor-suppressor protein p53 has been linked to the development of atherosclerotic lesions, and its homolog, p73, is proving to have contrasting functions in a variety of tissues. As an outgrowth of our previous finding that p73 is increased in serum-stimulated VSM cells and human atherosclerotic tissue, we examined p73 overexpression in VSM cells to elucidate causality of p73 expression with growth response. Overexpression of p73 results in decreased cell cycle transit and is accompanied by apoptosis. The apoptotic changes in p73 overexpressing VSM cells are independent of p53 and are associated with a decrease in levels of p21(waf1/cip1). In conjunction with our previous data finding that p73 is increased in serum-stimulated VSM cells, this work suggests a role for p73 in vascular proliferative diseases.     

Phytometabolite Dehydroleucodine Induces Cell Cycle Arrest,Apoptosis, and DNA Damage in Human Astrocytoma Cells through p73/p53 Regulation

Accumulating evidence supports the idea that secondary metabolites obtained from medicinal plants (phytometabolites) may be important contributors in the development of new chemotherapeutic agents to reduce the occurrence or recurrence of cancer. Our study focused on Dehydroleucodine (DhL), a sesquiterpene found in the provinces of Loja and Zamora-Chinchipe. In this study, we showed that DhL displayed cytostatic and cytotoxic activities on the human cerebral astrocytoma D384 cell line. With lactone isolated from Gynoxys verrucosa Wedd, a medicinal plant from Ecuador, we found that DhL induced cell death in D384 cells by triggering cell cycle arrest and inducing apoptosis and DNA damage. We further found that the cell death resulted in the increased expression of CDKN1A and BAX proteins. A marked induction of the levels of total TP73 and phosphorylated TP53, TP73, and γ-H2AX proteins was observed in D384 cells exposed to DhL, but no increase in total TP53 levels was detected. Overall these studies demonstrated the marked effect of DhL on the diminished survival of human astrocytoma cells through the induced expression of TP73 and phosphorylation of TP73 and TP53, suggesting their key roles in the tumor cell response to DhL treatment.     

The antiproliferative activity of aloe-emodin is through p53-dependent and p21-dependent apoptotic pathway in human hepatoma cell lines

The aim of this study is to investigate the anticancer effect of aloe-emodin in two human liver cancer cell lines, Hep G2 and Hep 3B. We observed that aloe-emodin inhibited cell proliferation and induced apoptosis in both examined cell lines, but with different the antiproliferative mechanisms. In Hep G2 cells, aloe-emodin induced p53 expression and was accompanied by induction of p21 expression that was associated with a cell cycle arrest in G1 phase. In addition, aloe-emodin had a marked increase in Fas/APO1 receptor and Bax expression. In contrast, with p53-deficient Hep 3B cells, the inhibition of cell proliferation of aloe-emodin was mediated through a p21-dependent manner that did not cause cell cycle arrest or increase the level of Fas/APO1 receptor, but rather promoted aloe-emodin induced apoptosis by enhancing expression of Bax. These findings suggest that aloe-emodin may be useful in liver cancer prevention.     

DACH1 regulates cell cycle progression of myeloid cells through the control of cyclin D, Cdk 4/6 and p21Cip1

The cell-fate determination factor Dachshund, a component of the Retinal Determination Gene Network (RDGN), has a role in breast tumor proliferation through the repression of cyclin D1 and several key regulators of embryonic stem cell function, such as Nanog and Sox2. However, little is known about the role of DACH1 in a myeloid lineage as a cell cycle regulator. Here, we identified the differential expression levels of extensive cell cycle regulators controlled by DACH1 in myeloid progenitor cells. The forced expression of DACH1 induced p27(Kip1) and repressed p21(Cip1), which is a pivotal characteristic of the myeloid progenitor. Furthermore, DACH1 significantly increased the expression of cyclin D1, D3, F, and Cdk 1, 4, and 6 in myeloid progenitor cells. The knockdown of DACH1 blocked the cell cycle progression of HL-60 promyeloblastic cells through the decrease of cyclin D1, D3, F, and Cdk 1, 4, and 6 and increase in p21(Cip1), which in turn decreased the phosphorylation of the Rb protein. The expression of Sox2, Oct4, and Klf4 was significantly up-regulated by the forced expression of DACH1 in mouse myeloid progenitor cells.