CXCL12 expression by healthy and malignant ovarian epithelial cells

Background

Exosomes consist of membrane vesicles that are secreted by several cell types, including tumors and have been found in biological fluids. Exosomes interact with other cells and may serve as vehicles for the transfer of protein and RNA among cells.

Methods

SKOV3 exosomes were labelled with carboxyfluoresceine diacetate succinimidyl-ester and collected by ultracentrifugation. Uptake of these vesicles, under different conditions, by the same cells from where they originated was monitored by immunofluorescence microscopy and flow cytometry analysis. Lectin analysis was performed to investigate the glycosylation properties of proteins from exosomes and cellular extracts.

Results

In this work, the ovarian carcinoma SKOV3 cell line has been shown to internalize exosomes from the same cells via several endocytic pathways that were strongly inhibited at 4°C, indicating their energy dependence. Partial colocalization with the endosome marker EEA1 and inhibition by chlorpromazine suggested the involvement of clathrin-dependent endocytosis. Furthermore, uptake inhibition in the presence of 5-ethyl-N-isopropyl amiloride, cytochalasin D and methyl-beta-cyclodextrin suggested the involvement of additional endocytic pathways. The uptake required proteins from the exosomes and from the cells since it was inhibited after proteinase K treatments. The exosomes were found to be enriched in specific mannose- and sialic acid-containing glycoproteins. Sialic acid removal caused a small but non-significant increase in uptake. Furthermore, the monosaccharides D-galactose, α-L-fucose, α-D-mannose, D-N-acetylglucosamine and the disaccharide β-lactose reduced exosomes uptake to a comparable extent as the control D-glucose.

Conclusions

In conclusion, exosomes are internalized by ovarian tumor cells via various endocytic pathways and proteins from exosomes and cells are required for uptake. On the other hand, exosomes are enriched in specific glycoproteins that may constitute exosome markers. This work contributes to the knowledge about the properties and dynamics of exosomes in cancer.     

Chemokine axes CXCL12/CXCR4 and CXCL16/CXCR6 correlate with lymph node metastasis in epithelial ovarian carcinoma

Recent evidence suggests that the chemokine axis of CXC chemokine ligand-12 and its receptor CXC chemokine receptor-4(CXCL12/CXCR4) is highly expressed in gynecological tumors and the axis of CXC chemokine ligand-16 and CXC chemokine receptor-6(CXCL16/CXCR6) is overexpressed in inflammation-associated tumors.This study aimed to determine the relationship between CXCL12/CXCR4,CXCL16/CXCR6 and ovarian carcinoma's clinicopathologic features and prognosis.Accordingly,the expression of these proteins in ovarian ...     

Silencing NKD2 by promoter region hypermethylation promotes gastric cancer invasion and metastasis by up-regulating SOX18 in human gastric cancer

Naked cuticle homolog2 (NKD2) is located in chromosome 5p15.3, which is frequently loss of heterozygosity in human colorectal and gastric cancers. In order to understand the mechanism of NKD2 in gastric cancer development, 6 gastric cancer cell lines and 196 cases of human primary gastric cancer samples were involved. Methylation specific PCR (MSP), gene expression array, flow cytometry, transwell assay and xenograft mice model were employed in this study. The expression of NKD1 and NKD2 was silenced by promoter region hypermethylation. NKD1 and NKD2 were methylated in 11.7% (23/196) and 53.1% (104/196) in human primary gastric cancer samples. NKD2 methylation is associated with cell differentiation, TNM stage and distant metastasis significantly (all P < 0.05), and the overall survival time is longer in NKD2 unmethylated group compared to NKD2 methylated group (P < 0.05). Restoration of NKD2 expression suppressed cell proliferation, colony formation, cell invasion and migration, induced G2/M phase arrest, and sensitized cancer cells to docetaxel. NKD2 inhibits SOX18 and MMP-2,7,9 expression and suppresses BGC823 cell xenograft growth. In conclusion, NKD2 methylation may serve as a poor prognostic and chemo-sensitive marker in human gastric cancer. NKD2 impedes gastric cancer metastasis by inhibiting SOX18.     

DNA methyltransferase expression and DNA hypermethylation in human hepatocellular carcinoma

Aberrant DNA methylation and increased expression of DNA methyltransferases (DNMTs) are features of tumor cells. To investigate roles for DNMTs during hepatocarcinogenesis, we examined DNMT expression at both the mRNA and protein level in hepatocellular carcinomas (HCCs) and paired non-neoplastic liver tissues, along with measuring the DNA methylation status of five tumor suppressor genes. Expression of DNMT1, DNMT3a and DNMT3b mRNA was detected in 33.3, 59.3, and 55.6% of HCCs and 40.7, 22.2, and 0% of non-neoplastic liver tissues, respectively. DNMT1 and DNMT3a were immunoreactive in 100 and 48% of HCCs and 52 and 0% of non-neoplastic liver tissues. The DNMT3a mRNA expression profile showed significant correlation with its immunoreactivity (P=0.022). DNA methylation status of five tumor suppressor genes, HIC-1, p16, RASSF1A, p53, and RB1 was detected in 85.2, 48.1, 44.4, 22.2, and 0% of HCCs, respectively. There was no significant correlation between DNMT mRNA expression and DNA methylation (P>0.05). DNMT immunoreactivity was also not associated with DNA methylation except HIC-1 (P=0.036) and p53 methylation (P=0.009). Despite the lack of correlation between DNA methylation status and DNMT expression, the frequency of hypermethylation of tumor suppressor genes remained relatively high in HCCs, suggesting that regional DNA hypermethylation is involved in hepatocarcinogenesis and that there may be other mechanisms for increasing DNA methylation.     

CXCL12-CXCR4 axis promotes the natural selection of breast cancer cell metastasis

CXCR4 and its ligand CXCL12 can promote the proliferation, survival, and invasion of cancer cells. They have been shown to play an important role in regulating metastasis of breast cancer to specific organs. High CXCR4 expression was also correlated to poor clinical outcome. Previous study also showed that tumor cells express a high level of CXCR4 and that tumor metastasis target tissues (lung, liver, and bone) express high levels of the ligand CXCL12, allowing tumor cells to directionally migrate to target organs via a CXCL12-CXCR4 chemotactic gradient. However, the exact mechanisms of how CXCR4 and CXCL12 enhance metastasis and/or tumor growth and their full implications on breast cancer progression are unknown. Yet it is likely that chemokine receptor signaling may provide more than just a migrational advantage by also helping the metastasized cells establish and survive in secondary environments. In this study, we investigated CXCR4 and CXCL12 expression in breast cancer and analyzed its association with clinicopathological factors by immunohistochemistry first. Then, we detected the mRNA and protein expression of CXCR4 and CXCL12 in breast cancer cell lines by Western blot and RT-PCR. The MDA-MB-231 has CXCR4 expression and very weak CXCL12 expression. So, we constructed the functional CXCL12 expression in MDA-MB-231 using a gene transfection technique. Further experiments were conducted to evaluate the effect of CXCL12 transfection on the biological behaviors of MDA-MB-231. The cell proliferation of MDA-MB-231–CXCL12 was accessed by MTT assay; the apoptosis was analyzed by an AnnexinV-FITC/propidium iodide double staining of flow cytometry method; and the cell invasive ability was examined by Matrigel invasion assay. Immunohistochemical analysis showed the co-expression of CXCR4 and CXCL12 correlated with lymph node metastasis and TNM stage (p?CXCL12 and its sole ligand CXCR4 play important role in the malignance of breast cancer. To gain a deeper insight into it, we picked CXCR4-expressing cells MDA-MB-231 to be transfected with CXCL12 stably. The decreased cellular proliferation, increased apoptosis, and invasive ability were found in MDA-MB-231 with successful CXCL12 transfection (p?CXCL12-CXCR4 axis correlated tightly with breast cancer metastasis. CXCL12-CXCR4 axis can increase the invasion and apoptosis of MDA-MB-231 simultaneously. These data strongly support the hypothesis that CXCL12-CXCR4 axis promotes the natural selection of breast cancer cell metastasis. Our findings could have significant implications in terms of breast cancer aggressiveness and the effectiveness of targeting the receptors and downstream signaling pathways for the treatment of breast cancer.     

Decreased expression of GRIM-19 by DNA hypermethylation promotes aerobic glycolysis and cell proliferation in head and neck squamous cell carcinoma

To identify novel tumor suppressor genes that are down-regulated by promoter hypermethylation in head and neck squamous cell carcinoma (HNSCC), genome-wide methylation profiling was performed using a methylated DNA immunoprecipitation (MeDIP) array in HNSCC and normal mucosa tissue samples. Promoter hypermethylation of the candidate gene, gene associated with retinoid-interferon induced mortality-19 (GRIM-19), was confirmed in HNSCC cell lines. Multivariate regression analysis determined that GRIM-19 hypermethylation was an independent significant factor for HNSCC diagnosis (OR:125.562; P < 0.001). HNSCC patients with lower ratio of GRIM-19/ACTB hypermethylation had increased overall and disease free survival. Furthermore, the optimal cutoff provided 90% sensitivity and 77% specificity of GRIM-19 hypermethylation as a diagnostic marker for HNSCC. Ectopic expression of GRIM-19 in HNSCC cells led to increased oxygen consumption, reduced glycolysis and decreased cell proliferation. HNSCC cells ectopically expressing GRIM-19 displayed increased p53 activity as well as decreased Stat3 and HIF-1α activities. Moreover, GRIM-19 knockdown not only resulted in decreased oxygen consumption and increased aerobic glycolysis but also promoted cell proliferation and tumorigenic capacity in HNSCC cells. Our data indicate that decreased GRIM-19 expression due to promoter hypermethylation may be important in head and neck carcinogenesis by promoting cell proliferation and regulating metabolic activity.     

Reduced tenascin expression in colonic carcinoma with lymphogenous metastasis.

We have studied expression of tenascin (TN) in colonic carcinoma cells from 81 patients with colonic carcinoma without (20) and with (61) lymphogenous metastases, in order to assess whether TN plays a role in local invasiveness and metastasis of tumors. In metastatic colonic carcinoma tissues from 52 cases, moderate, partial expression of TN was observed in the primary foci but no TN expression was observed in tissues from 9 others. However, in every case of nonmetastatic colonic carcinoma, very strong TN expression was observed in the tissues. Furthermore, the presence of dense TN accumulation correlated well with the prognoses (1-year survival) of colonic cancer patients (p less than 0.01). Weak TN expression was observed in 24/61 of the metastatic lymph nodes examined. In 2 patients with metastatic colonic carcinoma, the colonic cancer cells produced TN. TN may, therefore, play a role in limiting or preventing local tumor invasion rather than preventing metastasis and is a useful marker for predicting the prognoses of patients with colonic cancer.     

Silencing of miR-1-1 and miR-133a-2 cluster expression by DNA hypermethylation in colorectal cancer

MicroRNAs are small non-coding RNA molecules that play important roles in the multistep process of colorectal carcinoma (CRC) development. The present study evaluated the relationship between miR-1-1 and miR-133a-2 expression and DNA methylation, and its putative biological role in CRC. The results indicated that DNA methylation regulated the expression of the miR-1-1 and miR-133a-2 cluster in CRC cell lines. Expression of miR-1 and miR-133a was further evaluated in 64 paired tissue samples (CRC tumor and adjacent normal mucosa) using the stem-loop real-time polymerase chain reaction. The miR-1-133a cluster displayed significantly lower expression in CRC tissue compared to adjacent normal mucosa (P<0.001). The results also indicated frequent hypermethylation of the CpG islands upstream of miR-1-133a (54.6%). Liver metastatic tissues exhibited significantly lower miR-1 (P<0.001) and miR-133a (P<0.001) expression compared to adjacent normal mucosa. Expression of the miR-1-133a cluster inversely correlated with TAGLN2 in the tumor specimens. In conclusion, epigenetic repression of the miR-1-133a cluster may play a critical role in colorectal cancer metastasis by silencing TAGLN2.     

CXCL10 promotes osteolytic bone metastasis by enhancing cancer outgrowth and osteoclastogenesis

Amplification of the chemokines CXCL10 and RANKL has been suggested to promote osteoclast differentiation and osteolytic bone metastasis, but a function for endogenous CXCL10 in these processes is not well established. In this study, we show that endogenous CXCL10 is critical to recruit cancer cells to bone, support osteoclast differentiation and promote for the formation of osteolytic bone metastases. Neutralizing CXCL10 antibody reduced migration of cancer cells expressing the CXCL10 receptor CXCR3, and loss of CXCR3 or CXCL10 decreased bone tumor burden in vivo. Bone colonization augmented host production of CXCL10, which was required for cancer growth and subsequent osteolysis. Direct interactions between cancer cells and macrophages further stimulated CXCL10 production from macrophages. Growth of bone metastases required CXCL10-stimulated adhesion of cancer cells to type I collagen as well as RANKL-mediated osteoclast formation. Together, our findings show that CXCL10 facilitates trafficking of CXCR3-expressing cancer cells to bone, which augments its own production and promotes osteoclastic differentiation. CXCL10 therefore may represent a therapeutic target for osteolytic bone metastasis.     

CXCL12 expression in intrahepatic cholangiocarcinoma is associated with metastasis and poor prognosis

Intrahepatic cholangiocarcinoma is a rare malignant biliary neoplasm that causes a poor prognosis even after curative hepatectomy. Liver metastasis is the major recurrence pattern of intrahepatic cholangiocarcinoma; therefore, the prevention of liver metastasis is a desirable objective. The aim of this study is to identify gene(s) related to liver metastasis of intrahepatic cholangiocarcinoma and to examine the inhibitory effects on metastasis of intrahepatic cholangiocarcinoma by controlling such gene(s). We collected 3 pairs of intrahepatic cholangiocarcinoma frozen samples, and 36 pairs (primary and metastatic lesions) of intrahepatic cholangiocarcinoma formalin‐fixed paraffin‐embedded samples, from patients who underwent surgical resection at hospitals related to the Kyushu Study Group of Liver Surgery between 2002 and 2016. We carried out cDNA microarray analyses and immunohistochemistry to identify candidate genes, and evaluated one of them as a therapeutic target using human cholangiocarcinoma cell lines. We identified 4 genes related to liver metastasis using cDNA microarray, and found that CXCL12 was the only gene whose expression was significantly higher in liver metastasis than in primary intrahepatic cholangiocarcinoma by immunohistochemistry (P = .003). In prognosis, patients in the high CXCL12 group showed a significantly poor prognosis in disease‐free (P < .0001) and overall survival (P = .0004). By knockdown of CXCL12, we could significantly suppress the invasive and migratory capabilities of 2 human cholangiocarcinoma cell lines. Therefore, CXCL12 might be associated with metastasis and poor prognosis in intrahepatic cholangiocarcinoma.     

Silencing of the retinoid response gene TIG1 by promoter hypermethylation in nasopharyngeal carcinoma

Tazarotene-induced gene 1 (TIG1) and Tazarotene-induced gene 3 (TIG3) are retinoid acid (RA) target genes as well as candidate tumor suppressor genes in human cancers. In our study, we have investigated the expression of TIG1 and TIG3 in nasopharyngeal carcinoma (NPC). Loss of TIG1 expression was found in 80% of NPC cell lines and 33% of xenografts, whereas TIG3 was expressed in all NPC samples and immortalized nasopharyngeal epithelial cells. In order to elucidate the epigenetic silencing of TIG1 in NPC, the methylation status of TIG1 promoter was examined by genomic bisulfite sequencing and methylation-specific PCR (MSP). We have detected dense methylation of TIG1 5'CpG island in the 5 TIG1-negative NPC cell lines and xenograft (C666-1, CNE1, CNE2, HONE1 and X666). Partial methylation was observed in 1 NPC cell line HK1 showing dramatic decreased in TIG1 expression. Promoter methylation was absent in 2 TIG1-expressed NPC xenografts and the normal epithelial cells. Restoration of TIG1 expression and unmethylated alleles were observed in NPC cell lines after 5-aza-2'-deoxycytidine treatment. Moreover, the methylated TIG1 sequence was detected in 39 of 43 (90.7%) primary NPC tumors by MSP. In conclusion, our results showed that TIG1 expression is lost in the majority of NPC cell lines and xenografts, while promoter hypermethylation is the major mechanism for TIG1 silencing. Furthermore, the frequent epigenetic inactivation of TIG1 in primary NPC tumors implied that it may play an important role in NPC tumorigenesis.     

CXCL12-CXCR4生物学轴与肿瘤转移关系的研究

趋化因子CXCL12与其特异性受体CXCR4构成的CXCL12-CXCR4生物学轴在肿瘤细胞的选择性转移中起到重要的作用,并有可能参与了肿瘤的种植转移过程.对这一特殊生物学轴的研究可以为肿瘤的防治提供新的思路.     

Pygopus-2 promotes invasion and metastasis of hepatic carcinoma cell by decreasing E-cadherin expression

Pygopus-2 over-expression has been reported in several malignancies, such as ovarian, breast, lung and liver cancers. Here we demonstrated that down-regulation of Pygopus-2 by shRNA inhibited hepatic carcinoma cell invasion in vitro and metastasis in xenograft tumor models, which were promoted when Pygopus-2 was over-expressed. Pygopus-2 increased hepatic carcinoma cell invasion and metastasis, by decreasing E-cadherin. Pygopus-2 could bind to the E-cadherin promoter, increasing its methylation, and also indirectly decreased zeb2 expression. In turn these effects caused down-regulation of E-cadherin, potentiating invasion and metastasis. We suggest that targeting Pygopus-2 may potentially inhibit metastasis of hepatic carcinoma.     

Reduction of RKIP expression promotes nasopharyngeal carcinoma invasion and metastasis by activating Stat3 signaling

The role and underlying mechanism of Raf kinase inhibitory protein (RKIP) in nasopharyngeal carcinoma (NPC) metastasis remain unclear. Here, we showed that RKIP was downregulated in the NPC with high metastatic potentials, and its decrement correlated with NPC metastasis and poor patient survival, and was an independent predictor for reduced overall survival. With a combination of loss-of-function and gain-of-function approaches, we observed that high expression of RKIP reduced invasion, metastasis and epithelial to mesenchymal transition (EMT) marker alternations of NPC cells. We further showed that RKIP overexpression attenuated while RKIP knockdown enhanced Stat3 phosphorylation and activation in NPC cells; RKIP reduced Stat3 phosphorylation through interacting with Stat3; Stattic attenuated NPC cell migration, invasion and EMT marker alternations induced by RKIP knockdown, whereas Stat3 overexpression restored NPC cell migration, invasion and EMT marker alternations reduced by RKIP overexpression. In addition, there was an inverse correlation between RKIP and phospho-Stat3 expression in the NPC tissues and xenograft metastases. Our data demonstrate that RKIP is a metastatic suppressor and predictor for metastasis and prognosis in NPC, and RKIP downregulation promotes NPC invasion, metastasis and EMT by activating Stat3 signaling, suggesting that RKIP/Stat3 signaling could be used as a therapeutic target for NPC metastasis.     

CXCL12-CXCR4生物学轴与肿瘤转移

趋化因子CXCL12与其特异性受体CXCR4所构成的CXCL12-CXCR4生物学轴在肿瘤细胞选择性和非随意转移过程中发挥重要作用,对这一特殊生物学轴的研究可能为肿瘤转移防治找到新的突破口,现就其研究进展情况作一综述.     

Nuclear expression of Twist promotes lymphatic metastasis in esophageal squamous cell carcinoma

Twist-1 protein (also called Twist) has been suggested to be involved in tumor epithelial-mesenchymal transition (EMT) related progression, however, the mechanism by which twist promotes lymph node metastasis is not fully understood. In the present study, we found that nuclear twist expression is clearly correlated with lymph node (LN) metastasis as determined by immunohistochemistry (IHC). A highly invasive EC109 cell subline, EC109-P, was established by repeated in vitro transwell isolations for the cell model. Immunofluorescence (IF) assay demonstrated that nuclear twist expression was markedly higher in the highly invasive EC109-P cell line when compared with EC109 and EC9706 cells. Based on our cell model, the function and mechanism by which twist regulates LN metastasis in ESCC was investigated. The results showed that the overexpression of Twist could significantly increase the invasion and VEGF-C expression of EC9706 cells, whereas the knockdown of twist expression results in the opposite effects. This finding was further strengthened by the results of the analysis of co-expression of twist and VEGF-C by IHC in ESCC clinical samples. In summary, our study indicates that nuclear twist plays an important role in ESCC lymphatic metastasis by increasing the expression of VEGF-C. The combination of twist and VEGF-C detection could be a reliable prediction of LN metastasis in ESCC.     

12-O-Tetradecanoylphorbol-13-acetate stimulation of DNA synthesis in cultured preneoplastic familial polyposis colonic epithelial cells but not in normal colonic epithelial cells

We have developed a method for the routine primary culture of human colonic epithelial cells. Cultured cells exhibited characteristic epithelial structures, including a brush border and junctional complexes. Flask-like goblet cells containing mucus were also seen within the epithelial monolayer. [3H]Thymidine labeling indices were used to distinguish between cultured cells from familial polyposis patients, other patients at high risk to develop colon cancer, and low-risk control subjects. 12-O-Tetradecanoylphorbol-13-acetate (TPA) at 10 ng/ml enhanced DNA synthesis an average of 8-fold when assayed by labeling index in colonic epithelial cells from five of six familial polyposis patients. No such stimulation by TPA was seen in cells from 13 high-risk patients without familial polyposis or in cells from five low-risk subjects. Hundreds of benign polyps can be found in the colons of familial polyposis patients. One such benign tubular adenoma exhibited the same enhancement of DNA synthesis by TPA as normal-appearing epithelial cells from a biopsy adjacent to that polyp. Mitogenic response to TPA had been seen earlier in cells from each of four tubular adenomas (Friedman, E. Cancer Res., 41: 4588-4599, 1981). Both familial polyposis epithelial cells and adenoma cells are considered preneoplastic, but they are not identical because their patterns of actin cytoskeletal organization differ. These results imply that familial polyposis epithelial cells are precursors of tubular adenoma cells, and their transition to the more advanced preneoplastic cells of this benign tumor is influenced by endogeneous tumor promoters.     

肝再生磷酸转移酶-3的表达与上皮性卵巢癌转移相关性

目的检测肝再生磷酸酶-3（PRL-3）mRNA在上皮性卵巢癌及其转移灶中的表达,探讨其与上皮性卵巢癌发生、发展以及侵袭转移的生物学行为之间的关系。方法以22例正常卵巢组织为对照,通过半定量PCR测定84例上皮性卵巢癌原发灶及58例大网膜转移灶PRL-3 mRNA相对表达水平,并分析其表达水平与临床病理学指标的关系。结果 84例卵巢癌组织中PRL-3基因表达量显著高于正常卵巢组织。58例转移灶PRL-3基因表达量（2.24＋0.52）显著高于原发肿瘤（1.50＋0.47）（P〈0.05）。PRL-3基因表达水平与肿瘤远处转移有相关性（P〈0.05）,而与临床分期、肿瘤病理类型、分化程度及年龄均无关（P〉0.05）,与3年生存率有关（P〈0.01）。结论 PRL-3基因在上皮性卵巢癌的发生、发展和侵袭转移中起重要作用,PRL-3可能成为判断上皮性卵巢癌转移高危因素的一个生物标志物。