雌激素对转STGC3基因CNE2细胞系生长增殖的影响

为探讨雌激素对STGC3基因抑瘤的促进作用,将重组的pcDNA3.1( )-STGC3真核表达载体导入鼻咽癌细胞系CNE2,经G418筛选,RT-PCR及蛋白质印迹检测STGC3的表达,获得稳定高表达STGC3基因的pcDNA3.1( )/STGC3/CNE2细胞系.采用细胞计数法,检测雌二醇(β-estradiol)对体外培养pcDNA3.1( )/STGC3/CNE2细胞生长增殖的影响.将pcDNA3.1( )/STGC3/CNE2细胞接种于裸小鼠前肢背部皮下,观察分析雌性与雄性裸鼠成瘤的差别.运用RT-PCR、免疫组织化学及蛋白质印迹方法,分别从mRNA及蛋白质水平,分析STGC3基因在裸鼠移植瘤组织中的表达状况.移植瘤组织病理切片检查,观察瘤细胞形态学变化.用流式细胞仪测定移植瘤组织的细胞周期分布.研究结果表明:细胞体外培养,pcDNA3.1( )/STGC3/CNE2细胞经β-estradiol处理后,其生长速度明显减缓(P<0.05);裸鼠体内研究,接种pcDNA3.1( )/STGC3/CNE2细胞实验组的移植瘤体积和重量均小于对照组,差异有显著性意义(P<0.05);实验组中,雌性裸鼠组移植瘤体积和重量均小于雄性组,差异有显著性意义(P<0.05),雌性裸鼠组移植瘤生长最慢,而对照组中雄性与雌性裸鼠组间瘤块的差异无显著性意义(P>0.05);接种pcDNA3.1( )/STGC3/CNE2细胞的雌性裸鼠组移植瘤,阻滞于G0/G1期细胞数大于其他各组(P<0.05).上述体内外研究结果显示,雌激素可能具有增强STGC3基因对CNE2细胞系的生长抑制作用.     

Tet调控STGC3基因表达的CNE2细胞系裸鼠成瘤实验性研究

STGC3基因是一个新近克隆的肿瘤相关基因,前期的体外实验研究结果表明,STGC3基因在CNE2鼻咽癌细胞系高表达,可明显抑制CNE2的生长增殖.采用Tet/pTRE-STGC3/CNE2细胞系接种于裸鼠皮下,以强力霉素(Dox)诱导STGC3基因高表达,观测STGC3基因高表达对CNE2裸鼠体内成瘤的影响,并探讨其可能作用机制.运用RT-PCR、蛋白质印迹及免疫组织化学方法,分别从mRNA和蛋白质水平,分析瘤组织中STGC3基因的表达;用流式细胞仪检测移植瘤组织内肿瘤细胞的凋亡情况;用免疫组织化学方法,检测移植瘤组织凋亡相关蛋白Bcl-2和Bax的表达.研究结果显示,STGC3蛋白表达主要定位于细胞核内,Dox诱导STGC3基因在Tet/pTRE-STGC3/CNE2细胞系高表达,Tet/pTRE-STGC3/CNE2细胞系裸鼠体内成瘤受到明显抑制,与对照组比较,移植瘤成瘤时间晚、生长慢、肿块小、细胞凋亡率高,Bax蛋白表达增强,Bcl-2蛋白表达减少,差异有显著性意义(P<0.01).此体内实验研究结果与前期体外实验结果一致,进一步证明STGC3基因对肿瘤细胞生长具有抑制作用.     

The tumor supressor function of STGC3 and its reduced expression in nasopharyngeal carcinoma

STGC3 is a novel candidate tumor suppressor gene that was found to be associated with nasopharyngeal carcinoma (NPC) via the cDNA cloning and RACE processes. The biological function of the STGC3 protein and its expression level in nasopharyngeal carcinoma remain unknown. This study aimed to evaluate the STGC3 protein expression level in NPC and to investigate the inhibitory function of STGC3 as a candidate tumor suppressor gene. We assessed the expression of the STGC3 protein in NPC biopsies and normal control specimens via Western blot and immunohistochemical analysis. The expression of STGC3 as induced by doxycycline (Dox) via a tetracycline (Tet)-regulated system in human nasopharyngeal carcinoma cell line CNE2 was also established, and the effect of STGC3 restoration on the biological behavior of CNE2 was observed. A reduced level of STGC3 expression (0.978 ± 0.213 versus 0.324 ± 0.185, P < 0.05) was detected in NPC versus normal nasopharyngeal tissue by Western blot assay. Immunohistochemical assays for STGC3 detected positive staining in the nuclei and cytoplasm of epithelial cells, and the positive expression rate in NPC, 8 of 21 (38%), was lower than that in normal nasopharynx samples, 16 of 22 (72%). After STGC3 expression was restored, the growth capacity and clone formation potential of CNE2 cells in soft agar were significantly suppressed, and the cell percentage in G₀/G₁ phase increased, while the percentage of cells entering the S and G₂ phases decreased. This indicates that an abnormality in STGC3 expression is associated with nasopharyngeal carcinogenesis and that it may play an important role in controlling cell growth and regulating the cell cycle.     

Tet调控STGC3基因表达CNE2细胞系的建立及其功能初步研究

利用Tet-on调控系统,建立受强力霉素诱导STGC3基因表达的CNE2细胞系,为进一步研究STGC3的功能提供了一个理想的实验平台.先后将调控质粒pTet-on和反应质粒pTRE-STGC3转染入CNE2细胞,并用G418和潮霉素分别进行两轮筛选,运用RT-PCR选择对强力霉素诱导敏感的细胞克隆.用不同浓度强力霉素诱导CNE2/Tet/pTRE-STGC3细胞,RT-PCR检测STGC3的表达,确定强力霉素的最佳诱导浓度.采用此浓度的强力霉素分别诱导CNE2、CNE2/Tet/pTRE、CNE2/Tet/pTRE-STGC3三组细胞,测定细胞的生长曲线、克隆形成率和细胞周期分布.诱导STGC3基因高表达,CNE2细胞增殖速度显著减慢(P<0.05),克隆形成能力显著降低(P<0.01);流式细胞仪检测结果显示,瘤细胞群体中处于G0/G1期细胞数增加,细胞阻滞于G0/G1期.Tet调控STGC3基因表达CNE2细胞系的成功建立,为进一步研究STGC3基因的功能提供一个理想的细胞模型.     

STGC3基因缺失突变对CNE2细胞生长增殖能力的影响

为探讨鼻咽癌候选抑癌基因STGC3中层粘连蛋白G结构域(LG domain)对CNE2生长增殖能力的影响,应用基因定点突变技术将该结构域缺失,亚克隆至真核表达载体上,并将野生型及突变型STGC3稳定转染人鼻咽癌细胞系CNE2,检测其对CNE2细胞系表型的影响,包括测定稳转细胞系的生长曲线、细胞集落形成能力和细胞周期分布.研究发现,LGdomain的缺失明显降低了STGC3的肿瘤抑制活性,使受其稳定转染的细胞系恶性度显著增强,提示该结构域在STGC3发挥肿瘤抑制功能中起着重要作用.     

Epigallocatechin-3-gallate inhibits migration of human nasopharyngeal carcinoma cells by repressing MMP-2 expression

Metastasis of the cancer cells to the regional lymph nodes parts of the body remains an important cause of treatment failure in nasopharyngeal carcinoma (NPC) patients. Epigallocatechin-3-gallate (EGCG), the most important ingredient in the green tea, has been reported to possess antioxidant and anticancer activities. However, the effects of EGCG on NPC cell metastasis are still unclear. In the present study, we examined the in vitro antimetastatic properties of EGCG on human NPC cells, NPC-39, HONE-1 and NPC-BM. The results revealed that EGCG considerably inhibited the migration abilities of three NPC cells. The matrix metalloproteinases-2 (MMP-2) activity and expression were also significantly inhibited by EGCG treatment. Furthermore, EGCG suppressed the phosphorylation of the Src signaling pathway. Moreover, blocking the Src pathway also inhibits MMP-2 expression and migration in the NPC cells. In conclusion, this study revealed that EGCG could inhibit the metastatic activity of human NPC cells by downregulating the protein expression of MMP-2 through modulation of the Src signaling pathway, suggesting that EGCG may be a potential candidate for chemoprevention of NPC.     

Picropodophyllin inhibits tumor growth of human nasopharyngeal carcinoma in a mouse model

Insulin-like growth factor-1 receptor (IGF-1R) is a cell membrane receptor with tyrosine kinase activity and plays important roles in cell transformation, tumor growth, tumor invasion, and metastasis. Picropodophyllin (PPP) is a selective IGF-1R inhibitor and shows promising antitumor effects for several human cancers. However, its antitumor effects in nasopharyngeal carcinoma (NPC) remain unclear. The purpose of this study is to investigate the antitumor activity of PPP in NPC using in vitro cell culture and in vivo animal model. We found that PPP dose-dependently decreased the IGF-induced phosphorylation and activity of IGF-1R and consequently reduced the phosphorylation of Akt, one downstream target of IGF-1R. In addition, PPP inhibited NPC cell proliferation in vitro. The half maximal inhibitory concentration (IC50) of PPP for NPC cell line CNE-2 was ?1 μM at 24 h after treatment and ?0.5 μM at 48 h after treatment, respectively. Moreover, administration of PPP by intraperitoneal injection significantly suppressed the tumor growth of xenografted NPC in nude mice. Taken together, these results suggest targeting IGF-1R by PPP may represent a new strategy for treatment of NPCs with positive IGF-1R expression.     

Identification of differential proteins in nasopharyngeal carcinoma cells with p53 silence by proteome analysis

Although mutation of p53 tumor-suppressor gene is rare in nasopharyngeal carcinoma (NPC), NPC has a high frequency of overexpression of p53 protein. There seem to be complex mechanisms of inactivation and stabilization of p53 in NPC. To detect proteins associated with the function of p53 in high throughout screening, we succeeded in establishing p53 knockdown human NPC CNE2 cell line (CNE2sip53) using stable RNA interference, and compared the proteomic changes between CNE2sip53 and control cell line CNE2/pSUPER using two-dimensional gel electrophoresis. Twenty-two differentially expressed proteins between the two cell lines were identified by both matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and electrospray ionization tandem mass spectrometry, some of which are known to be associated with the p53 function (HSP27, hnRNP K, 14-3-3sigma, etc.), and others may be novel proteins associated with p53 function (eIF4B, TPT1, hnRNP H3, SFRS1 etc.). Furthermore, several differential proteins including HSP27, HSP70, GRP75 and GRP78 were verified as p53 interacting proteins in NPC by immunoprecipitation and Western blot analysis, and the suppression of HSP27 expression by HSP27 antisense oligonucleotides could decrease the p53 protein level. Our data suggest that these differential proteins may be associated with the function of p53 in NPC, and provide new clues to elucidate the mechanisms of inactivation and stabilization of p53 in NPC.     

Proteomics-based identification of proteins with altered expression induced by 12-O-tetradecanoylphorbol 13-acetate in nasopharyngeal carcinoma CNE2 cells

Nasopharyngeal carcinoma (NPC) is a malignancy with high incidence in Southern China and South-East Asia. Etiology studies indicate that chemical carcinogen promoters, such as 12-O-tetradecanoylphorbol-13-acetate (TPA), are important factors causing NPC development. However, the mechanism of the TPA effect on NPC remains unclear. In the present study, cells from a poorly differentiated squamous cell carcinoma NPC cell line, CNE2, were stimulated by TPA and proteomics technology was carried out to find protein discrepancies between control and TPA-treated cells. Results revealed that TPA treatment in CNE2 cells could upregulate the expression of ““““triosephosphate isomerase““““ and ““““14-3-3 protein sigma““““ and downregulate the expression of ““““reticulocalbin 1 precursor““““, ““““nucleophosmin““““, ““““mitochondrial matrix protein pl precursor““““, and ““““stathmin““““. The changes in the expression of these genes suggested that TPA induced CNE2 cells to antiproliferation and to apoptosis, which was confirmed by subsequent apoptosis detection. Therefore, the effects of TPA on nasopharyngeal carcinoma cells were distinct from the effects on primary epithelial cells and we suggest reasons for these differences.     

Transient overexpression of TGFBR3 induces apoptosis in human nasopharyngeal carcinoma CNE-2Z cells

NPC (nasopharyngeal carcinoma) is a common malignancy in southern China without defined aetiology. Recent studies have shown that TGFBR3 (transforming growth factor type III receptor, also known as betaglycan), exhibits anticancer activities. This study was to investigate the effects of TGFBR3 on NPC growth and the mechanisms for its actions. Effects of TGFBR3 overexpression on cell viability and apoptosis were measured by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide], AO/EB (acridine orange/ethidium bromide) staining and electron microscopy in human NPC CNE-2Z cells. The expression of apoptosis-related proteins, p-Bad, Bad, XIAP (X-linked inhibitor of apoptosis), AIF (apoptosis-inducing factor), Bax and Bcl-2, was determined by Western blot or immunofluorescence analysis. Caspase 3 activity was measured by caspase 3 activity kit and [Ca²⁺]_i (intracellular Ca²⁺ concentration) was detected by confocal microscopy. Transfection of TGFBR3 containing plasmid DNA at concentrations of 0.5 and 1 μg/ml reduced viability and induced apoptosis in CNE-2Z in concentration- and time-dependent manners. Forced expression of TGFBR3 up-regulated pro-apoptotic Bad and Bax protein, and down-regulated anti-apoptotic p-Bad, Bcl-2 and XIAP protein. Furthermore, transient overexpression of TGFBR3 also enhanced caspase 3 activity, increased [Ca²⁺]_i and facilitated AIF redistribution from the mitochondria to the nucleus in CNE-2Z cells, which is independent of the caspase 3 pathway. These events were associated with TGFBR3-regulated multiple targets involved in CNE-2Z proliferation. Therefore transient overexpression of TGFBR3 may be a novel strategy for NPC prevention and therapy.     

Two legume defense proteins suppress the mobility of nasopharyngeal carcinoma cells

A 16-kDa trypsin inhibitor was isolated from an edible legume using various chromatographic procedures. The protein was unadsorbed on Affi-gel blue gel but adsorbed on DEAE-Sepharose and Mono Q following which media the protein was subsequently subjected to gel filtration on Superdex 75 and a final 21-fold purification was achieved. This trypsin inhibitor showed remarkable pH and thermal stability. Its inhibitory activity was impaired in the presence of 1?mM dithiothreitol. The anti-proliferative and anti-mobility activities of this trypsin inhibitor and a hemagglutinin isolated from the same legume were tested on nasopharyngeal carcinoma cells. These two defense proteins demonstrated discrepant anti-proliferative efficacies that the hemagglutinin could greatly suppress the proliferation of nasopharyngeal carcinoma cells, while the trypsin inhibitor revealed a minor effect. However, these two proteins could both attenuate the mobility of nasopharyngeal carcinoma cells. The present study revealed the potential of applying plant defense proteins in cancer treatment.     

Inactivation of 14-3-3 σ by promoter methylation correlates with metastasis in nasopharyngeal carcinoma

14-3-3 σ, the downstream target of p53, is a negative regulator of cell cycle G2-M phase checkpoint in response to DNA damage. Our previous comparative proteomics study showed that 14-3-3 σ was downregulated or lost in nasopharyngeal carcinoma (NPC) tissue compared with non-cancerous nasopharyngeal epithelial tissue (NNET). In this study, we further investigated for the epigenetic mechanism of 14-3-3 σ inactivation. Methylation-specific PCR showed 14-3-3 σ promoter methylation in 100% of analyzed NPC cell lines (4/4) but not in immortalized human nasopharyngeal epithelial cell line NP69. Treatment of the four NPC cell lines with the methyltransferase inhibitor 5-aza-2′-dC resulted in the demethylation and upregulation of 14-3-3 σ. In tissues, 14-3-3 σ promoter methylation occurred at a higher frequency in NPC, 63/75 (84%), compared to adjacent NNET, 7/25 (28%), and fully methylated 14-3-3 σ promoter was detected in NPC but not in any of adjacent NNET. RT-PCR, Western blotting, and immunohistochemistry showed that 14-3-3 σ expression was downregulated or lost in NPC with methylation, and there was a negative correlation between the expression levels and methylation statuses of 14-3-3 σ gene. In addition, the patients with methylated 14-3-3 σ presented a higher frequency of lymph node and distant metastasis, and an advanced clinical stage, and overexpression of 14-3-3 σ in NPC cell line 5-8F with high metastatic potential was able to inhibit its in vitro invasive ability. Our data are the first to show that 14-3-3 σ is frequently inactivated by promoter methylation in NPC and this aberrant methylation correlates with lymph node and distant metastasis. J. Cell. Biochem. 106: 858–866, 2009. © 2009 Wiley-Liss, Inc.     

A caffeic acid phenethyl ester analog inhibits the proliferation of nasopharyngeal carcinoma cells via targeting epidermal growth factor receptor

A previous study reported that compound 5A, a caffeic acid phenethyl ester (CAPE) analog, exhibited obvious neuroprotective activity, in particular, compound 5A possessed higher stability and membrane permeability than CAPE. CAPE displays antitumour function; therefore, evaluating the antitumour effect of its analog with higher stability and membrane permeability is worthwhile. We first investigated the antitumour activity of compound 5A. We found that compound 5A significantly inhibited the proliferation of tumor cells and showed low cytotoxicity in normal cells. Furthermore, compound 5A was found to induce the cell cycle arrest and apoptosis of CNE2 cells. Through the prediction of SwissTargetPrediction and subsequent confirmation, epidermal growth factor receptor (EGFR) was identified as a target of compound 5A. Compound 5A also influenced the expression of genes downstream of EGFR in nasopharyngeal carcinoma (NPC) cells. Based on these findings, compound 5A inhibits the proliferation of NPC cells by targeting EGFR and may become a new candidate compound for NPC treatment.     

鼻咽癌相关新基因NPCEDRG表达对CNE2细胞生长的影响

为研究鼻咽癌相关新基因NPCEDRG的功能,探讨其对鼻咽癌细胞生长特性的影响,利用Tet-on调控系统,建立受强力霉素(deoxycycline,Dox)诱导NPCEDRG基因表达的CNE2细胞系.运用RT-PCR选择背景表达低、诱导活性高的细胞克隆,以不同浓度Dox诱导CNE2/Tet/TRE-NPCEDRG细胞,确定Dox的最佳诱导浓度.借助形态学观察、细胞生长曲线、软琼脂克隆形成试验和流式细胞仪分析等方法,对Dox诱导NPCEDRG高表达后CNE2细胞的生物学行为进行了检测.结果显示,NPCEDRG高表达后CNE2细胞增殖速度显著减慢(P<0.05),克隆形成能力显著降低(P<0.01),瘤细胞群体中处于G0/G1期细胞数增加,S期细胞数减少,细胞阻滞于G0/G1期.Tet调控NPCEDRG基因表达CNE2细胞系成功建立,恢复NPCEDRG表达能部分逆转CNE2的恶性表型,证明NPCEDRG是一个鼻咽癌相关的抑瘤基因.     

Long non-coding RNA MEG3 promotes autophagy and apoptosis of nasopharyngeal carcinoma cells via PTEN up-regulation by binding to microRNA-21

Long non-coding RNAs (lncRNAs) have been highlighted as attractive markers for diagnosis and prognosis as well as new therapeutic targets in multiple cancers, including nasopharyngeal carcinoma (NPC). Here, we attempted to investigate the underlying regulatory role of the lncRNA maternally expressed gene 3 (MEG3) in NPC development. As determined by RT-qPCR, MEG3 expression was down-regulated in NPC cells. Online RNA crosstalk analysis predicted the binding of miR-21 to MEG3 and PTEN, respectively. MEG3 was validated to bind to miR-21 while PTEN was identified as a target of miR-21 by dual-luciferase reporter gene assay. Exogenous transfection was done to change the levels of MEG3, miR-21 and PTEN in HK-1 cells to investigate their effects on the autophagy and apoptosis of NPC cells. The results suggested that MEG3 overexpression in HK-1 cells up-regulated PTEN and down-regulated miR-21, by which MEG3 further inhibited autophagy and apoptosis ability of NPC cells. The tumour formation ability was tested after injecting the HK-1 cells into nude, mice and tumour growth was monitored. Consistently, MEG3 overexpression inhibited the tumour formation in vivo. Collectively, MEG3 promotes the autophagy and apoptosis of NPC cells via enhancing PTEN expression by binding to miR-21.     

Quantitative proteomic analysis of differential proteins in the stroma of nasopharyngeal carcinoma and normal nasopharyngeal epithelial tissue

The importance of stromal cells and the factors that they expressed during cancer initiation and progression have been highlighted by recent literature. To identify the stromal proteins involved in nasopharyngeal carcinoma (NPC) carcinogenesis, we assessed differences in protein expression of the stroma from NPC and normal nasopharyngeal epithelium tissues (NNET) using a quantitative proteomic approach combined with laser capture microdissection (LCM). LCM was performed to purify stromal cells from the NPC and NNET, respectively. The differential proteins between the pooled microdissected tumor and normal stroma were analyzed by two‐dimensional difference gel electrophoresis (2D‐DIGE) combined with mass spectrometry (MS). Twenty differential proteins were identified, and the expression and location of two differential proteins (L ‐plastin and S100A9) were further confirmed by Western blotting and immunohistochemical analysis. Our results will be helpful to study the role of stroma in the NPC carcinogenesis, as well as discover the interaction between NPC cells and their surrounding microenvironment. J. Cell. Biochem. 106: 570–579, 2009. © 2009 Wiley‐Liss, Inc.     

Induction of apoptosis in prostate tumor PC-3 cells and inhibition of xenograft prostate tumor growth by the vanilloid capsaicin

Capsaicin, the pungent ingredient of hot chilli pepper, has been recently shown to induce apoptosis in several cell lines through a not well known mechanism. Here, we investigated the role of the vanilloid capsaicin in the death regulation of the human cancer androgen-resistant cell line PC-3. Capsaicin inhibited the growth of PC-3 with an IC₅₀ of 20 μM cells and induced cell apoptosis, as assessed by flow cytometry and nuclei staining with DAPI. Capsaicin induced apoptosis in prostate cells by a mechanism involving reactive oxygen species generation, dissipation of the mitochondrial inner transmembrane potential (ΔΨ_m) and activation of caspase 3. Capsaicin-induced apoptosis was not reduced by the antagonist capsazepine in a dose range from 0.1 μM to 20 μM, suggesting a receptor-independent mechanism. To study the in vivo effects of capsaicinoids, PC-3 cells were grown as xenografts in nude mice. Subcutaneous injection of either capsaicin or capsazepine (5 mg/kg body weight) in nude mice suppressed PC-3 tumor growth in all tumors investigated and induced apoptosis of tumor cells. Our data show a role for capsaicin against androgen-independent prostate cancer cells in vitro and in vivo and suggest that capsaicin is a promising anti-tumor agent in hormone-refractory prostate cancer, which shows resistance to many chemotherapeutic agents.     

鼻咽癌细胞ClC-3在细胞周期中的表达

用免疫荧光、激光共聚焦显微镜图像分析及膜片钳等技术研究了鼻咽癌上皮CNE-2Z细胞容积激活性氯通道候选基因C1C-3的表达及其在细胞周期中与容积激活性氯电流及细胞容积调节性回缩(regulatoryvolumedecrease,RVD)的关系.结果显示,CNE-2Z细胞表达ClC-3.ClC-3蛋白主要位于细胞内而不是在细胞膜上,其表达水平及其在细胞中的分布呈细胞周期依赖性.G1期细胞的ClC-3表达水平较低而S期则较高,M期细胞的表达水平中等.在细胞周期中,ClC-3表达水平与细胞RVD能力及容积激活性氯电流水平呈反比.上述观察结果提示,ClC-3可能参与细胞周期的调节,但CNE-2Z细胞中的ClC-3可能不是与RVD有关的氯通道.     

Nutlin-3 induces apoptosis,disrupts viral latency and inhibits expression of angiopoietin-2 in Kaposi sarcoma tumor cells

Kaposi sarcoma (KS) tumors often contain a wild-type p53. However, the function of this tumor suppressor in KS tumor cells is inhibited by both MDM2 and latent nuclear antigen (LANA) of Kaposi sarcoma-associated herpes virus (KSHV). Here, we report that MDM2 antagonist Nutlin-3 efficiently reactivates p53 in telomerase-immortalized human umbilical vein endothelial cells (TIVE) that had been malignantly transformed by KSHV as well as in KS tumor cells. Reactivation of p53 results in a G₁ cell cycle arrest, leading to inhibition of proliferation and apoptosis. Nutlin-3 inhibits the growth of “KS-like” tumors resulting from xenografted TIVE-KSHV cells in nude mice. In addition, Nutlin-3 strongly inhibits expression of the pro-angiogenic and pro-inflammatory cytokine angiopoietin-2 (Ang-2). It also disrupts viral latency by inducing expression of KSHV lytic genes. These results suggest that Nutlin-3 might serve as a novel therapy for KS.