Hydronephrotic Urine in the Obstructed Kidney Promotes Urothelial Carcinoma Cell Proliferation,Migration, Invasion through the Activation of mTORC2-AKT and ERK Signaling Pathways

Obstructive nephropathy is the most common presentation of urothelial carcinoma. The role of the urine in the obstructed kidney namely “hydronephrotic urine” in urothelial carcinoma has not been extensively explored. This study aims to evaluate whether hydronephrotic urine in the obstructed kidney could promote urothelial carcinoma. The hydronephrotic urine was collected from the obstructed kidneys of Sprague-Dawley rats induced by different periods of unilateral ureteral obstruction (UUO). By the inhibition of LY294002 and PD184352, we confirm that hydronephrotic urine promotes urothelial carcinoma cell (T24) and immortalized normal urothelial cells (E6) proliferation, migration and invasion in a dose-dependent manner through the activation of the mTORC2-AKT and ERK signaling pathways. Hydronephrotic urine also increases the expression of cyclin-D2, cyclin-B and CDK2. It also decreases the expression of p27 and p21 in both urothelial carcinoma cells and normal urothelial cells. By the protein array study, we demonstrate that many growth factors which promote tumor cell survival and metastasis are over-expressed in a time-dependent manner in the hydronephrotic urine, including beta-FGF, IFN-γ, PDGF-BB, PIGF, TGF-β, VEGF-A, VEGF-D and EGF. These results suggest that hydronephrotic urine promotes normal and malignant urothelial cells proliferation, migration and invasion, through the activation of the mTORC2-AKT and ERK signaling pathways. Further investigation using live animal models of tumor growth may be needed to clarify aspects of these statements.     

PPARgamma ligands suppress proliferation of human urothelial basal cells in vitro

Expression of peroxisome proliferator-activated receptor (PPAR) gamma in the human urinary tract through embryonic development suggests its possible roles in the development, proliferation, and differentiation of uroepithelium. Little is known, however, about physiological roles of PPARgamma in the urinary tract. We investigated effects of PPARgamma ligands on the proliferation of normal human urothelial cells and stromal cells cultivated from surgical specimens. Active proliferation in vitro as well as high molecular weight cytokeratin expression indicated that cultured urothelial cells possess basal cell phenotype. PPARgamma protein, expressed predominantly in the epithelial layer of the normal human urinary tract in vivo, was abundantly expressed in urothelial cells but barely detectable in stromal cells in vitro. Natural ligand for PPARgamma, 15-deoxy-Delta(12,14) prostaglandin J(2) (15d-PGJ(2)), as well as synthetic ones, troglitazone and pioglitazone, suppressed proliferation of the urothelial cells dose-dependently. These effects were PPARgamma specific because clofibrate or PGF(2alpha) did not affect proliferation of urothelial cells. Neither 9-cis retinoic acid or all-trans retinoic acid (ATRA) at 1 microM showed any synergism on the antiproliferative effects of PPARgamma ligands. Urothelial cells treated with PPARgamma ligands showed drastic morphologic changes and cell cycle arrest at G0/G1 phase accompanied with increased mRNA level of a cyclin-dependent kinase inhibitor p21(WAF1/CIP1). Since 15d-PGJ(2) is present in vivo during the resolution phase of inflammation, these results indicated that PPARgamma might be involved in the terminal phase of urothelial re-epithelialization processes.     

Ⅰ型磷酸酶抑制亚基-1对人宫颈癌HeLa细胞增殖的抑制作用

PPI1(Inhibitor-1 ofprotein phosphatase 1)是I型磷酸酶的抑制亚基之一,其活化依赖于35位苏氨酸蛋白激酶(PKA)的磷酸化而发挥抑制作用.本研究目的在于探讨PPIl持续活化型突变体的表达对人宫颈癌细胞株增殖的影响及其可能的作用机制.利用PPI1野生型和活化型突变体表达质粒分别转染HeLa细胞,首先通过H~3TdR掺入实验、迁移实验观察PPI1基因对HeLa细胞增殖能力的影响,研究结果表明:在活化型突变体表达的HeLa细胞株中,细胞~3H掺入量和迁移能力明显受抑.其次通过流式细胞术、Giemsa染色法分析PPIl对HeLa细胞的细胞周期的影响;FACS分析表明HeLa细胞G2/M期比例明显升高;经脱氧胸苷同步化后,该组细胞进入有丝分裂期明显滞后.最后利用Western blot分析PPI1对MAPK信号转导通路的影响,Western blot分析显示该组细胞的ERK磷酸化水平明显下降.研究表明PPI1活化型突变体的表达可抑制人宫颈癌细胞株的增殖,这与其诱导HeLa细胞G2/M期停滞、有丝分裂的进入延缓有关,其中涉及到MAPK信号转导通路的活化受抑制.     

Induction of endoreduplication by a JNK inhibitor SP600125 in human lung carcinoma A 549 cells

The effect of the pan c-Jun N-terminal kinase (JNK) inhibitor SP600125 on the proliferation of human lung carcinoma A549 cells has been evaluated. We have shown that SP600125 completely inhibited the proliferation of A549 cells, the cycle arrest being in G2/M phase. When cells were treated with SP600125 for >12h, a cell population with DNA content of 4n to 8n was detected. Moreover, the effect of SP600125 on the expression of cell cycle related proteins was an upregulation of p53 protein accompanied by an increase in its molecular mass. Prolonged SP600125 treatment downregulated p21, Bax and Mdm2 expression, but increased the level of the cellular p53-Mdm2 complex. Taken together, we show that SP600125 could induce G2/M cell cycle arrest and endoreduplication in a p21 independent manner, and that SP600125 could also post-translationally modify p53 to modify its function. Our data show that basic JNK activity plays an important role in the progression of the cell cycle at G2/M cell phase.     

Knockdown of long noncoding RNA urothelial carcinoma associated 1 inhibits colorectal cancer cell proliferation and promotes apoptosis via modulating autophagy

Long noncoding RNA urothelial carcinoma associated 1 (UCA1) has been implicated in the growth and metastasis of colorectal cancer (CRC), and autophagy contributes to tumorigenesis and cancer cell survival. However, the regulatory role of UCA1 in CRC cell viability by modulating autophagy remains unclear. In the present study, a significant positive correlation was observed between UCA1 and microtubule-associated protein 1 light chain 3 (LC3) levels, and the elevated UCA1 was negatively correlated with the PKB/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway in 293T cells. Downregulation of UCA1 inhibited autophagy activation and cell proliferation, whereas the apoptosis was increased and the cell cycle was arrested in G2 stage. The next results showed that UCA1 was markedly upregulated in Caco-2 cells. Knockdown of UCA1 significantly decreased the LC3-II and autophagy-related gene 5 (ATG5) protein levels and resulted in an increase in p62 expression. Conversely, the autophagy activator rapamycin (RAPA) reversed the effects. Furthermore, downregulated UCA1 decreased Caco-2 cells population in the G1 phase and increased the cells number in G2 phage. The cell proliferation was inhibited, and apoptosis rate was promoted. More important, RAPA could also abrogate the changes induced by knockdown of UCA1. Collectively, these data demonstrated that downregulated UCA1 induced autophagy inhibition, resulting in suppressing cell proliferation and promoting apoptosis, which suggested that UCA1 might serve as a potential new oncogene to regulate CRC cells viability by modulating autophagy.     

Protein tyrosine kinase inhibitors modulate radiosensitivity and radiation-induced apoptosis in K562 cells.

We studied the modulating effect of protein tyrosine kinase inhibitors on the response of cells of the human chronic myelogenous leukemia cell line K562 to radiation. The radiosensitivity of the cells was increased by treatment with herbimycin A and decreased by treatment with genistein. This modulating effect of protein tyrosine kinase inhibitors on radiation sensitivity was associated with the alteration of the mode of radiation-induced cell death. After X irradiation, the cells arrested in the G(2) phase of the cell cycle, but these TP53(-/-) cells were unable to sustain cell cycle arrest. This G(2)-phase checkpoint deficit caused cell death. The morphological pattern of cell death was characterized by swelling of the cytoplasmic compartments, cytosolic vacuolation, disruption of the plasma membrane, less evident nuclear condensation, and faint DNA fragmentation, all of which were consistent with oncosis or cytoplasmic apoptosis. The nonreceptor protein tyrosine kinase inhibitor herbimycin A accelerated the induction of typical apoptosis by X irradiation, which was demonstrated by morphological assessments using nuclear staining and electron microscopy as well as oligonucleosomal fragmentation and caspase 3 activity. Herbimycin A is known to be a selective antagonist of the BCR/ABL kinase of Philadelphia chromosome-positive K562 cells; this kinase blocks the induction of apoptosis after X irradiation. Our results showed that the inhibition of protein tyrosine kinase by herbimycin A enhanced radiation-induced apoptosis in K562 cells. This effect was associated with the activation of caspase 3 and rapid abrogation of the G(2)-phase checkpoint with progression out of G(2) into G(1) phase. In contrast, the receptor-type protein tyrosine kinase inhibitor genistein protected K562 cells from all types of radiation-induced cell death through the inhibition of caspase 3 activity and prolonged maintenance of G(2)-phase arrest. Further investigations using this model may give valuable information about the mechanisms of radiation-induced apoptosis and about the radiosensitivity and radioresistance of chronic myelogenous leukemia cells having the Philadelphia chromosome.     

TACC3 is an independent prognostic marker,and knockdown of TACC3 enhances the efficacy of CDK1 inhibitor RO3306 in liver cancer cells

The drug resistance of single-target therapy has gradually become an intractable clinical problem. Combination therapy may be an effective treatment to overcome or postpone drug resistance in cancer. Herein, we discussed the synergistic effect of transforming acidic coiled-coil containing protein 3 (TACC3) suppression and cyclin-dependent kinase 1 (CDK1) in hepatocellular carcinoma (HCC). The Cancer Genome Atlas database and bioinformatics methods were implemented to analyze the expression of CDK1 and TACC3, and predict the biological function of TACC3-related genes in HCC. In addition, in vitro experiments, including cell counting kit 8, transwell and flow cytometry were utilized to evaluate cell proliferation, migration, invasion, cell cycle arrest and apoptosis of HCC cells. Our results demonstrated that TACC3 is an unfavorable and independent prognostic factor to predict poor overall survival (OS) in HCC patients. Genetic inhibition of TACC3 exhibited a remarkable antineoplastic activity of HCC cell lines. Bioinformatic prediction proposed that CDK1 may be the main regulator of TACC3-related genes in HCC. In vitro experimental measurements suggested that a combination of si-TACC3 and CDK1 inhibitor synergistically inhibited cell proliferation and migration, and induced G2 cell cycle arrest and apoptosis of HepG2 or MHCC97H cells. In conclusion, our results revealed a prospective dual-target, TACC3 and CDK1, therapeutic strategy to improve the treatment of HCC.     

The activation of MEK/ERK signaling pathway by bone morphogenetic protein 4 to increase hepatocellular carcinoma cell proliferation and migration

Hepatocellular carcinoma (HCC) is one of the most common visceral malignancies worldwide, with a very high incidence and poor prognosis. Bone morphogenesis protein 4 (BMP4), which belongs to the TGF-β superfamily of proteins, is a multifunctional cytokine, which exerts its biologic effects through SMAD- and non-SMAD-dependent pathways, and is also known to be involved in human carcinogenesis. However, the effects of the BMP4 signaling in liver carcinogenesis are not yet clearly defined. Here, we first show that BMP4 and its receptor, BMPR1A, are overexpressed in a majority of primary HCCs and that it promotes the growth and migration of HCC cell lines in vitro. We also establish that BMP4 can induce HCC cyclin-dependent kinase (CDK)1 and cyclin B1 upregulation to accelerate cell-cycle progression. Our study indicates that the induction of HCC cell proliferation is independent of the SMAD signaling pathway, as Smad4 knockdown of HCC cell lines still leads to the upregulation of CDK1 and cyclin B1 expression after BMP4 treatment. Using mitogen-activated protein/extracellular signal-regulated kinase (MEK) selective inhibitors, the induction of CDK1, cyclin B1 mRNA and protein were shown to be dependent on the activation of MEK/extracellular signal-regulated kinase (ERK) signaling. In vivo xenograft studies confirmed that the BMPR1A-knockdown cells were significantly less tumorigenic than the control groups. Our findings show that the upregulation of BMP4 and BMPR1A in HCC promotes the proliferation and metastasis of HCC cells and that CDK1 and cyclin B1 are important SMAD-independent molecular targets in BMP4 signaling pathways, during the HCC tumorigenesis. It is proposed that BMP4 signaling pathways may have potential as new therapeutic targets in HCC treatment.     

Effects of stable knockdown of Aurora kinase A on proliferation, migration, chromosomal instability, and expression of focal adhesion kinase and matrix metalloproteinase-2 in HEp-2 cells

Overexpression of Aurora kinase A (AURKA) is frequently observed in various cancers, including laryngeal squamous cell carcinoma (LSCC). We investigated the effects of knockdown of AURKA on laryngeal cancer HEp-2 cells both in vitro and in vivo. A plasmid containing short hairpin (sh)RNA against AURKA was constructed and transfected into HEp-2. Measurements included the CCK-8 assay for viability and proliferation, flow cytometry for apoptosis and effects on the mitotic checkpoint, a trans-well assay for migration, immunofluorescence for assessment of genomic instability, and western blotting for protein expression. AURKA knockdown inhibited proliferation, migration, and colony formation in vitro and tumorigenicity in vivo. The knockdown induced the accumulation of cells in G2-M phase and eventual apoptosis. Knockdown of AURKA caused delayed entry into mitosis after treatment with nocodazole, reduced chromosomal instability, and decreased expression of focal adhesion kinase (FAK), phosphorylated FAK, and matrix metalloproteinase-2 (MMP-2), key regulators in cell adhesion and invasion. Knockdown of AURKA inhibits the growth and invasiveness of this LSCC cell line both in vitro and in vivo. These effects may partially result from the reduced expression of FAK and MMP-2. Knockdown of AURKA expression may represent a promising therapeutic strategy for the treatment of LSCC.     

Leukotriene D4 mediates survival and proliferation via separate but parallel pathways in the human intestinal epithelial cell line Int 407

We demonstrated previously that leukotriene D4 (LTD4) regulates proliferation of intestinal epithelial cells through a CysLT receptor by protein kinase C (PKC)epsilon-dependent stimulation of the mitogen-activated protein kinase ERK1/2. Our current study provides the first evidence that LTD4 can activate 90-kDa ribosomal S6 kinase (p90RSK) and cAMP-responsive element-binding protein (CREB) via pertussis-toxin-sensitive Gi protein pathways. Transfection and inhibitor experiments revealed that activation of p90RSK, but not CREB, is a PKCepsilon/Raf-1/ERK1/2-dependent process. LTD4-mediated CREB activation was not affected by expression of kinase-dead p90RSK but was abolished by transfection with the regulatory domain of PKCalpha (a specific dominant-inhibitor of PKCalpha). Kinase-negative mutants of p90RSK and CREB (K-p90RSK and K-CREB) blocked the LTD4-induced increase in cell number and DNA synthesis (thymidine incorporation). Compatible with these results, flow cytometry showed that LTD4 caused transition from the G0/G1 to the S+G2/M cell cycle phase, indicating increased proliferation. Similar treatment of cells transfected with K-p90RSK resulted in cell cycle arrest in the G0/G1 phase, consistent with a role of p90RSK in LTD4-induced proliferation. On the other hand, expression of K-CREB caused a substantial buildup in the sub-G0/G1 phase, suggesting a role for CREB in mediating LTD4-mediated survival in intestinal epithelial cells. Our results show that LTD4 regulates proliferation and survival via distinct intracellular signaling pathways in intestinal epithelial cells.     

Thrombin-mediated hepatocellular carcinoma cell migration: cooperative action via proteinase-activated receptors 1 and 4

Proteinase-activated receptor-1 (PAR(1)), a thrombin receptor and the prototype of a newly discovered G-protein-coupled receptor subfamily, plays an important role in tumor development and progression. In this study, we documented the expression of the thrombin receptors PAR(1), PAR(3), and PAR(4) in permanent hepatocellular carcinoma (HCC) cell lines and primary HCC cell cultures. Stimulation of HCC cells with thrombin and the PAR(1)-selective activating peptide, TFLLRN-NH(2), increased transmembrane migration across a collagen barrier. This effect was blocked by the PAR(1) antagonist SCH 79797, confirming that the PAR(1) thrombin receptor subtype is involved in regulating hepatoma cell migration. In addition, the PAR(4)-selective agonist, AYPGKF-NH(2), also stimulated HCC cell migration whilst the PAR(4) antagonist, trans-cinnamoyl-YPGKF-NH(2), attenuated the effect of thrombin on HCC cell migration. PAR(1)- and PAR(4)-triggered HCC cell migration was blocked by inhibiting a number of key mediators of signal transduction, including G proteins of the G(i)/G(o) family, matrix metalloproteinases, ERK/MAPKinase, cyclic AMP-dependent protein kinase, Src tyrosine kinase, and the EGF receptor kinase. Our data point to a cooperative PAR(1)/PAR(4) signaling network that contributes to thrombin-mediated tumor cell migration. We suggest that a combined inhibition of coagulation cascade serine proteinases, the two PARs and their complex signaling pathways may provide a new strategy for treating hepatocellular carcinoma.     

Silencing of the integrin-linked kinase gene suppresses the proliferation, migration and invasion of pancreatic cancer cells (Panc-1)

Integrin-linked kinase (ILK) is an ankyrin repeat-containing serine-threonine protein kinase that is involved in the regulation of integrin-mediated processes such as cancer cell proliferation, migration and invasion. In this study, we examined the effect of a lentivirus-mediated knockdown of ILK on the proliferation, migration and invasion of pancreatic cancer (Panc-1) cells. Immunohistochemical staining showed that ILK expression was enhanced in pancreatic cancer tissue. The silencing of ILK in human Panc-1 cells led to cell cycle arrest in the G0/G1 phase and delayed cell proliferation, in addition to down-regulating cell migration and invasion. The latter effects were mediated by up-regulating the expression of E-cadherin, a key protein in cell adhesion. These findings indicate that ILK may be a new diagnostic marker for pancreatic cancer and that silencing ILK could be a potentially useful therapeutic approach for treating pancreatic cancer.     

Inhibition of G1 cyclin-dependent kinase activity during growth arrest of human breast carcinoma cells by prostaglandin A2.

Prostaglandin A2 (PGA2) potently inhibits cell proliferation and suppresses tumor growth in vivo, but little is known regarding the molecular mechanisms mediating these effects. Here we demonstrate that treatment of breast carcinoma MCF-7 cells with PGA2 leads to G1 arrest associated with a dramatic decrease in the levels of cyclin D1 and cyclin-dependent kinase 4 (cdk4) and accompanied by an increase in the expression of p21. We further show that these effects occur independent of cellular p53 status. The decline in cyclin D and cdk4 protein levels is correlated with loss in cdk4 kinase activity, cdk2 activity is also significantly inhibited in PGA2-treated cells, an effect closely associated with the upregulation of p21. Immunoprecipitation experiments verified that p21 was indeed complexed with cdk2 in PGA2-treated cells. Additional experiments with synchronized MCF-7 cultures stimulated with serum revealed that treatment with PGA2 prevents the progression of cells from G1 to S. Accordingly, the kinase activity associated with cdk4, cyclin E, and cdk2 immunocomplexes, which normally increases following serum addition, was unchanged in PGA2-treated cells. Furthermore, the retinoblastoma protein (Rb), a substrate of cdk4 and cdk2 whose phosphorylation is necessary for cell cycle progression, remains underphosphorylated in PGA2-treated serum-stimulated cells. These findings indicate that PGA2 exerts its growth-inhibitory effects through modulation of the expression and/or activity of several key G1 regulatory proteins. Our results highlight the chemotherapeutic potential of PGA2, particularly for suppressing growth of tumors lacking p53 function.     

Highly Selective Anti-Cancer Activity of Cholesterol-Interacting Agents Methyl-β-Cyclodextrin and Ostreolysin A/Pleurotolysin B Protein Complex on Urothelial Cancer Cells

Cholesterol content can vary distinctly between normal and cancer cells, with elevated levels in cancer cells. Here, we investigated cholesterol sequestration with methyl-β-cyclodextrin (MCD), and pore-formation with the ostreolysin A/pleurotolysin B (OlyA/PlyB) protein complex that binds to cholesterol/sphingomyelin-rich membrane domains. We evaluated the effects on viability of T24 invasive and RT4 noninvasive human urothelial cancer cells and normal porcine urothelial (NPU) cells. Cholesterol content strongly correlated with cancerous transformation, as highest in the T24 high-grade invasive urothelial cancer cells, and lowest in NPU cells. MCD treatment induced prominent cell death of T24 cells, whereas OlyA/PlyB treatment resulted in greatly decreased viability of the RT4 low-grade noninvasive carcinoma cells. Biochemical and transmission electron microscopy analyses revealed that MCD and OlyA/PlyB induce necrotic cell death in these cancer cells, while viability of NPU cells was not significantly affected by either treatment. We conclude that MCD is more toxic for T24 high-grade invasive urothelial cancer cells, and OlyA/PlyB for RT4 low-grade noninvasive urothelial cancer cells, and neither is toxic for NPU cells. The cholesterol and cholesterol/sphingomyelin-rich membrane domains in urothelial cancer cells thus constitute a selective therapeutic target for elimination of urothelial cancer cells.     

Role of c-Jun N-terminal kinase in the PDGF-induced proliferation and migration of human adipose tissue-derived mesenchymal stem cells

Platelet-derived growth factor (PDGF) is a critical regulator of proliferation and migration for mesenchymal type cells. In this study, we examined the role of mitogen-activated protein (MAP) kinases in the PDGF-BB-induced proliferation and migration of human adipose tissue-derived mesenchymal stem cells (hATSCs). The PDGF-induced proliferation was prevented by a pretreatment with the c-Jun N-terminal kinase (JNK) inhibitor, SP600125. However, it was not prevented by a pretreatment with a p38 MAP kinase inhibitor, SB202190, and a specific inhibitor of the upstream kinase of extracellular signal-regulated kinase (ERK1/2), U0126. Treatment with PDGF induced the activation of JNK and ERK in hATSCs, and pretreatment with SP600125 specifically inhibited the PDGF-induced activation of JNK. Treatment with PDGF induced the cell cycle transition from the G0/G1 phase to the S phase, the elevated expression of cyclin D1, and the phosphorylation of Rb, which were prevented by a pretreatment with SP600125. In addition, the PDGF-induced migration of hATSCs was completely blocked by a pretreatment with SP600125, but not with U0126 and SB202190. These results suggest that JNK protein kinase plays a key role in the PDGF-induced proliferation and migration of mesenchymal stem cells.     

Netrin-1-independent adenosine A2b receptor activation regulates the response of axons to netrin-1 by controlling cell surface levels of UNC5A receptors

Growth cone response to the bifunctional guidance cue netrin-1 is regulated by the activity of intracellular signaling intermediates such as protein kinase C-alpha (PKCα) and adenylyl cyclase. Among the diverse cellular events these enzymes regulate is receptor trafficking. Netrin-1, itself, may govern the activity of these signaling intermediates, thereby regulating axonal responses to itself. Alternatively, other ligands, such as activators of G protein-coupled receptors, may regulate responses to netrin-1 by governing these signaling intermediates. Here, we investigate the mechanisms controlling activation of PKCα and the subsequent downstream regulation of cell surface UNC5A receptors. We report that activation of adenosine receptors by adenosine analogs, or activation of the putative netrin-1 receptor, the G protein-coupled receptor adenosine A2b receptor (A2bR) results in PKCα-dependent removal of UNC5A from the cell surface. This decrease in cell surface UNC5A reduces the number of growth cones that collapse in response to netrin-1 and converts repulsion to attraction. We show these A2bR-mediated alterations in axonal response are not because of netrin-1 because netrin-1 neither binds A2bR, as assayed by protein overlay, nor stimulates PKCα-dependent UNC5A surface loss. Our results demonstrate that netrin-1-independent A2bR signaling governs the responsiveness of a neuron to netrin-1 by regulating the levels of cell surface UNC5A receptor.