Prostaglandin E2 induces vascular endothelial growth factor secretion in prostate cancer cells through EP2 receptor-mediated cAMP pathway

Prostaglandin E2 (PGE2) has been shown to induce expression of vascular endothelial growth factor (VEGF) and other signaling molecules in several cancers. PGE2 elicits its functions though four G-protein coupled membrane receptors (EP1-4). In this study, we investigated the role of EP receptors in PGE2-induced molecular events in prostate cancer cells. qRT-PCR analysis revealed that PC-3 cells express a substantially higher level of EP2 and moderately higher EP4 than DU145 and LNCaP cells. LNCaP cells had virtually no detectable EP2 mRNA. EP1 and EP3 mRNAs were not detected in these cells. Treatment of prostate cancer cells with PGE2 (1 nM-10 microM) increased both VEGF secretion and cyclic adenosine monophosphate (cAMP) production. Levels of induction in PC-3 cells were greater than in DU145 and LNCaP cells. The selective EP2 agonist CAY10399 also significantly increased VEGF secretion and cAMP production in PC-3 cells, but not in DU145 and LNCaP cells. Moreover, PGE2 and CAY10399 increased mitogen activated protein kinase/extracellular signal regulated kinase (MAPK/Erk) and Akt phosphorylation in PC-3 and DU145 cells, but not in LNCaP cells. However, neither the MAPK/Erk inhibitor U0126 nor the PI3K/Akt inhibitor LY294002 abolished PGE2-induced VEGF secretion in PC-3 cells. We further demonstrated that the adenylate cyclase activator forskolin and the cAMP anologue 8-bromo-cAMP mimicked the effects of PGE2 on VEGF secretion in PC-3 cells. Meanwhile, the adenylate cyclase inhibitor 2'5'-dideoxyadenosine, at concentrations that inhibited PGE2-induced cAMP, significantly blocked PGE2-induced VEGF secretion in PC-3 cells. We conclude that PGE2-induced VEGF secretion in prostate cancer cells is mediated through EP2-, and possibly EP4-, dependent cAMP signaling pathways.     

PYK-2在PGE_2诱导大肠癌细胞侵袭转移中的作用

目的 研究富含脯氨酸的酪氨酸激酶 2(proline rich tyrosine kinase 2,PYK 2)在前列腺素E2(PGE2)诱导大肠癌SW480细胞侵袭转移中的作用。方法 实验分为A、B、C、D四组,分别为未处理组,PGE2组,PGE2+SC19220(EP1抑制剂)组,PGE2+BAPTA AM(胞内Ca2+螯合剂)组。通过 RT PCR检测SW480中PGE2四种EP(EP1,EP2,EP3,EP4)受体的表达,应用Western blotting检测SW480细胞中PYK 2蛋白的表达,应用Transwell实验观察各组SW480细胞侵袭转移能力的改变。结果SW480表达PGE2的三种EP受体,EP1,EP2和EP4,PGE2可促进EP1的表达;经PGE2作用后,10分钟内PYK 2磷酸化水平逐渐增加,0分钟、5分钟、10分钟检测结果相比差异均有统计学意义(P<0.05),30分钟与0分钟检测结果相比差异无统计学意义(P>0.05);C组、D组与B组相比PYK 2磷酸化水平明显下降(P<0.05),大肠癌细胞侵袭转移能力显著降低(P<0.05)。结论 PGE2可能通过Ca2+,EP1促进PYK 2的磷酸化,从而进一步诱导大肠癌细胞的侵袭转移过程。     

MicroRNA-1246 expression associated with CCNG2-mediated chemoresistance and stemness in pancreatic cancer

Background:

Pancreatic cancer has a poor prognosis because of its high refractoriness to chemotherapy and tumour recurrence, and these properties have been attributed to cancer stem cells (CSCs). MicroRNA (miRNA) regulates various molecular mechanisms of cancer progression associated with CSCs. This study aimed to identify the candidate miRNA and to characterise the clinical significance.

Methods:

We established gemcitabine-resistant Panc1 cells, and induced CSC-like properties through sphere formation. Candidate miRNAs were selected through microarray analysis. The overexpression and knockdown experiments were performed by evaluating the in vitro cell growth and in vivo tumourigenicity. The expression was studied in 24 pancreatic cancer samples after laser captured microdissection and by immunohistochemical staining.

Results:

The in vitro drug sensitivity of pancreatic cancer cells was altered according to the miR-1246 expression via CCNG2. In vivo, we found that miR-1246 could increase tumour-initiating potential and induced drug resistance. A high expression level of miR-1246 was correlated with a worse prognosis and CCNG2 expression was significantly lower in those patients.

Conclusions:

miR-1246 expression was associated with chemoresistance and CSC-like properties via CCNG2, and could predict worse prognosis in pancreatic cancer patients.     

Chemoresistance of lung cancer stemlike cells depends on activation of Hsp27

BACKGROUND:

In the current study, the authors sought to identify the molecular mechanisms underlying the chemoresistance of lung cancer stem or initiation cells (cancer stem cells).

METHODS:

A549 lung cancer cells before and after selective enrichment of a subpopulation of cancer stem cells were treated with superoxide and traditional chemotherapeutics to determine their sensitivity or resistance to these cytotoxic agents. Apoptotic activity was measured using a variety of fluorescence‐based and biochemical techniques. Specific pathways involved in the chemoresistance of cancer stem cell‐enriched lung cancer cells were analyzed with Western blotting and pharmacologic targeting therapy in a xenograft model.

RESULTS:

Lung cancer stem cells exhibited significantly decreased apoptotic response to treatment with superoxide, cisplatin, gemcitabine, or a combination of cisplatin and gemcitabine compared with control A549 cells. Apoptotic resistance was mediated through the inactivation of caspase‐9 and caspase‐3. Increased activation of p38MAPK, MAPKAPK2, and Hsp27 was observed in lung cancer stem cells compared with control A549 cells both before and after exposure to superoxide and chemotoxic agents. In a mouse model of lung cancer, chemotherapy‐induced cells increased in the antiapoptosis pathway, and quercetin, an inhibitor of Hsp27, combined with traditional chemotherapy was effective in blocking the pathway and in the treatment of lung tumors in vivo.

CONCLUSIONS:

The authors' data demonstrate that lung cancer stem cells have elevated levels of activated Hsp27 upon treatment with superoxide and traditional chemotherapy. When combined with chemotoxic agents, blockage of Hsp27 decreased the survival of lung cancer stem cells, which otherwise were resistant to traditional chemotherapy. Cancer 2011. © 2010 American Cancer Society.     

化疗后残余胃癌细胞发生上皮间质转化的体外研究

  目的  观察体外化疗能否诱导胃癌细胞发生上皮间质转化（epithelial mesenchymal transition,EMT）。   方法  使用5-Fu（30 μg/mL）对胃癌细胞株SGC7901进行4个疗程的体外化疗,残余细胞继续培养,得到能稳定传代的细胞SGC7901/Fu。比较SGC7901及SGC7901/Fu在细胞形态、EMT标记物、化疗耐药性、侵袭能力、肿瘤干细胞特性等方面的差异。   结果   与SGC7901比较,SGC7901/Fu呈间质细胞形态、上皮表型标记物表达下调、间质表型标记物表达上调。在SGC7901细胞及SGC7901/Fu细胞中,5-Fu的中效浓度（IC₅₀）分别为（43.8±7.2）μg/mL及（64.6±5.5）μg/mL,穿过Transwell小室基底膜的细胞数分别为（51.4±8.7）个及（93.2±9.5）个,克隆形成率分别为5.2%±1.0%及13.2%±2.2%,CD44+/CD24-细胞亚群所占比例分别为4.13%±0.81%及7.97%± 0.50%,两者间的差异均具有统计学意义（P<0.05）。   结论  体外化疗后残余的胃癌细胞发生EMT,同时细胞侵袭能力增强、化疗耐药性升高,并获得了肿瘤干细胞特性。      

Prostaglandin receptors EP1-4 as a potential marker for clinical outcome in urothelial bladder cancer

Prostaglandins, especially prostaglandin E₂ (PGE₂), and COX-2 play an important role in carcinogenesis of many tumors including bladder cancer (BCA). The PGE₂ receptors EP1-4 regulate tumor cell growth, invasion and migration in different tumor entities but EP expression in BCA remains to be determined. In the present study we examined the expression of EP1-4 in non-muscle invasive bladder cancer (NMIBC), muscle invasive bladder cancer (MIBC) and normal urothelial tissue (NU) using immunohistochemistry. Nuclear and cytoplasmic EP1-4 expression was correlated with clinicopathological parameters and survival of BCA patients. EP1, EP2 and EP3 were significantly less expressed in the cytoplasm und nucleus of NMIBC and MIBC than in NU; EP4 cytoplasmic staining in MIBC was significantly higher compared to NU. The cytoplasmic staining was significantly more abundant in MIBC than in NMIBC in all investigated receptors except EP2. The level of EP staining in NMIBC was correlated with staging and grading, especially cytoplasmic EP1. Nuclear staining of EP1 was an independent predictor of BCA recurrence-free survival in NMIBC patients. EP receptors are dysregulated in BCA. The increase of EP1 may be used as prognostic parameter in NMIBC patients and its dysregulation could be targeted by specific EP1 inhibitors.     

Sox2对膀胱癌细胞化疗耐药的影响及其分子机制的探讨

摘 要：［目的］ 探讨Sox2对膀胱癌细胞化疗耐药的影响及其分子机制。［方法］ 选用T24人膀胱癌细胞系,采用浓度递增方式建立顺铂耐药细胞系T24/DDP,慢病毒载体转染对应细胞,进行Sox2基因过表达或敲除,得到T24-Sox2细胞和T24/DDP-shSox2细胞系。qRT-PCR和Western blot检测各组细胞中Sox2与多药耐药相关蛋白（MRP）表达水平。MTT实验检测各组细胞在不同浓度顺铂作用下的吸光度值并计算IC50,绘制耐药曲线。流式细胞术检测各组细胞凋亡率,并使用qRT-PCR和Western blot检测凋亡相关蛋白的表达水平。［结果］ qRT-PCR和Western blot结果证实Sox2和MRP在膀胱癌顺铂耐药细胞系中高表达,耐药曲线提示Sox2与膀胱癌的顺铂耐药存在一定关联,耐药细胞系的IC50为(15.24±1.12)μg/ml,而非耐药细胞系的IC50为(4.88±0.72) μg/ml,P<0.05。Sox2表达上调能够抑制膀胱癌细胞凋亡,凋亡率从74.62%下降到25.84%,P<0.05。Bax和Caspase-3在Sox2高表达的细胞中呈低表达,而Bcl-2则呈高表达。［结论］ Sox2基因在顺铂耐药膀胱癌细胞系中表达水平显著高于正常非耐药膀胱癌细胞,且Sox2可能是通过抑制细胞凋亡来实现对化疗敏感性的调控。     

口腔鳞状细胞癌组织前列腺素E2受体EP3的表达及临床意义

目的 前列腺素E2 (prostaglandin E2,PGE2)可以通过促进癌细胞的增殖、抑制癌细胞的凋亡、促进癌细胞的转移等方式促进口腔鳞癌的发生发展,但关于其具体作用机制罕见报道.因此,本研究旨在检测口腔鳞状细胞癌组织和相应癌旁组织中花生四烯酸(arachidonic acid,AA)及前列腺素E2受体3亚型(E-prostanoid 3,EP3)的表达.方法 选取南方医科大学南方医院2013-05-01-2015-05-01行手术治疗的口腔鳞癌患者40例,将口腔鳞状细胞癌组织作为观察组(40例),相应癌旁组织作为对照组(40例).ELISA方法检测AA的表达,Real-time PCR方法检测EP3受体mRNA的表达,免疫组织化学染色方法检测EP3受体蛋白的表达.结果 与癌旁组织相比,AA在口腔鳞状细胞癌组织中的表达明显升高.40例口腔鳞癌组织中AA的平均质量分数为(477.4±39.84) pg/g,40例癌旁组织中AA的平均质量分数为(38.4±4.92) pg/g,差异有统计学意义,t=3.146,P=0.001.与癌旁组织相比,鳞癌组织中EP3受体mRNA的表达明显降低.40例鳞癌组织EP3受体mRNA的相对平均表达量为0.43±0.15,差异有统计学意义,t=2.365,P=0.011.与癌旁组织相比,鳞癌组织中EP3受体蛋白的表达明显降低,20例癌旁组织呈阳性表达,而18例鳞癌组织呈弱阳性表达,差异有统计学意义,T=-114,P=0.016.结论 口腔鳞状细胞癌组织中,AA表达量的显著上调,EP3受体表达量的显著下调,可能在口腔鳞状细胞癌的发生发展过程中发挥了重要作用.     

Head neck squamous cell carcinoma c-Met⁺ cells display cancer stem cell properties and are responsible for cisplatin-resistance and metastasis

c-Met, the tyrosine kinase receptor for hepatocyte growth factor, is overexpressed in a variety of tumors in which it plays a central role in malignant transformation. Although c-Met has also been determined to be a critical signaling molecule in normal stem cell function, the potential role of c-Met as a single marker for cancer stem cells (CSCs) has not been previously examined. In our study, we reported that human head neck squamous cell carcinoma (HNSCC) cells expressing c-Met were capable of self-renewal and of generating tumors that recapitulate the heterogeneity of the parental tumors, and isolation of HNSCC cells using a second marker CD44 could further enhance upon the in-vivo tumorigenicity. We also reported that c-Met(+) HNSCC cells could readily make spherical colonies in nonadherent culture conditions, in contrast, c-Met(-) population did not; these spherical colonies could be passaged multiple times without loss of colony-forming capability. Furthermore, we showed that c-Met(+) HNSCC cells have increased expression of self-renewal pathways are spared by cisplatin treatment and are responsible for mediating metastasis. These results indicated that c-Met could serve as a novel marker for CSCs at least in HNSCC, and the highly chemoresistant and metastatic capabilities of c-Met(+) HNSCC population make them an important cell type to better define and understand their function.