Snail, a key inducer of epithelial-mesenchymal transition (EMT), plays an important role in cancer metastasis. To better understand the role of Snail in the metastasis of ovarian carcinoma, expression of Snail was knocked down by antisense-Snail in the highly metastatic ovarian cancer cell line HO8910PM. Gene array analysis revealed that blocking Snail expression suppressed the activity of matrix metalloproteinases (MMPs) and upregulated TIMP3, an MMP inhibitor. These findings suggest that Snail interacts with MMP during tumor invasion and metastasis. In addition, we examined the role of Snail in an ovarian cancer orthotopic model by using the antisense-Snail HO8910PM cell line. We found that the size of primary ovarian cancer tumor and the number of metastatic lesions were significantly reduced when Snail was knocked down. Confirming our initial findings, the activity of MMP2 was greatly inhibited in tumors from antisense-Snail cells. Furthermore, immunohistochemical analysis on ovarian cancer progression tissue array demonstrated that the expression of Snail was significantly higher in metastatic lesions, and Snail expression correlated with the stage of ovarian cancer. Interestingly, in early-stage tumors, Snail was localized in both the cytoplasm and nucleus. In late stage and metastatic lesions, the level of Snail was elevated, and Snail was localized to the nucleus. The expression level and nuclear localization of Snail were also inversely correlated with E-cadherin expression. Overall, our study indicates that Snail plays a critical role in tumor growth and metastasis of ovarian carcinoma through regulation of MMP activity.

BackgroundPhyllanthus niruri L. is a well-known hepatoprotective and antiviral medicinal herb. Recently, we identified Corilagin as a major active component with anti-tumor activity in this herbal medicine. Corilagin is a member of the tannin family that has been discovered in many medicinal plants and has been used as an anti-inflammatory agent. However, there have been few reports of the anti-tumor effects of Corilagin, and its anti-tumor mechanism has not been investigated clearly. The aim of the present study is to investigate the anticancer properties of Corilagin in ovarian cancer cells.MethodsThe ovarian cancer cell lines SKOv3ip, Hey and HO-8910PM were treated with Corilagin and analyzed by Sulforhodamine B (SRB) cell proliferation assay, flow cytometry, and reverse phase protein array (RPPA). Corilagin was delivered intraperitoneally to mice bearing SKOv3ip xenografts.ResultsCorilagin inhibited the growth of the ovarian cancer cell lines SKOv3ip and Hey, with IC50 values of less than 30 μM, while displaying low toxicity against normal ovarian surface epithelium cells, with IC50 values of approximately 160 μM. Corilagin induced cell cycle arrest at the G2/M stage and enhanced apoptosis in ovarian cancer cells. Immunoblotting assays demonstrated that Cyclin B1, Myt1, Phospho-cdc2 and Phospho-Weel were down-regulated after Corilagin treatment. Xenograft tumor growth was significantly lower in the Corilagin-treated group compared with the untreated control group (P <0.05). More interestingly, Corilagin inhibited TGF-β secretion into the culture supernatant of all tested ovarian cancer cell lines and blocked the TGF-β-induced stabilization of Snail. In contrast, a reduction of TGF-β secretion was not observed in cancer cells treated with the cytotoxic drug Paclitaxel, suggesting that Corilagin specifically targets TGF-β secretion. Corilagin blocked the activation of both the canonical Smad and non-canonical ERK/AKT pathways.ConclusionsCorilagin extracted from Phyllanthus niruri L. acts as a natural, effective therapeutic agent against the growth of ovarian cancer cells via targeted action against the TGF-β/AKT/ERK/Smad signaling pathways.

BackgroundARHI is a Ras-related imprinted gene that inhibits cancer cell growth and motility. ARHI is downregulated in the majority of breast cancers, and loss of its expression is associated with its progression from ductal carcinoma in situ (DCIS) to invasive disease. In ovarian cancer, re-expression of ARHI induces autophagy and leads to autophagic death in cell culture; however, ARHI re-expression enables ovarian cancer cells to remain dormant when they are grown in mice as xenografts. The purpose of this study is to examine whether ARHI induces autophagy in breast cancer cells and to evaluate the effects of ARHI gene re-expression in combination with paclitaxel.MethodsRe-expression of ARHI was achieved by transfection, by treatment with trichostatin A (TSA) or by a combination of TSA and 5-aza-2'-deoxycytidine (DAC) in breast cancer cell cultures and by liposomal delivery of ARHI in breast tumor xenografts.ResultsARHI re-expression induces autophagy in breast cancer cells, and ARHI is essential for the induction of autophagy. When ARHI was re-expressed in breast cancer cells treated with paclitaxel, the growth inhibitory effect of paclitaxel was enhanced in both the cell culture and the xenografts. Although paclitaxel alone did not induce autophagy in breast cancer cells, it enhanced ARHI-induced autophagy. Conversely, ARHI re-expression promoted paclitaxel-induced apoptosis and G2/M cell cycle arrest.ConclusionsARHI re-expression induces autophagic cell death in breast cancer cells and enhances the inhibitory effects of paclitaxel by promoting autophagy, apoptosis, and G2/M cell cycle arrest.

Endothelial cells (ECs) are critical for angiogenesis, and microRNA plays important roles in this process. In this study, we investigated the function and mechanism of miR-302c in the process of endothelial-mesenchymal transition (EndMT) in ECs. When miR-302c was overexpressed in HUVECs, the motility of the HUVECs was weakened; the expression levels of EndMT markers were also changed: vascular endothelial (VE)-cadherin was up-regulated, whereas β-catenin, FSP1, and α-SMA were down-regulated. Further in vivo and in vitro experiments showed that the growth of HCC was inhibited when co-cultured or co-injected with HUVECs overexpressing miR-302c. On the contrary, when miR-302c was suppressed in HUVECs, the opposite results were observed. Reporter assays showed that miR-302c inhibited metadherin (MTDH) expression through directly binding to its 3′UTR. In addition, compared to ECs isolated from normal liver tissues of HCC patients, ECs isolated from tumor tissues expressed markedly low levels of miR-302c but high levels of MTDH. These results suggest that EC-specific miR-302c suppresses tumor growth in HCC through MTDH-mediated inhibition of EndMT. MTDH and miR-302c might provide a new strategy for anti-angiogenic therapy in HCC.

RAB25 belongs to the Rab family of small GTPases and is implicated in the development of various types of human cancer. To evaluate the role of RAB25 in ovarian cancer, RAB25 was knocked down by siRNA in HEY and ES‑2 human ovarian cancer cells. Autophagy, cell growth and cell apoptosis were evaluated. The results showed that knockdown of RAB25 increased acidic vesicle organelles and GFP-microtubule-associated protein 1 light chain 3 punctate fluorescence in ovarian cancer cells. Autophagy that promoted by knockdown of RAB25 was not observed in cells where the ERK1/2 signaling pathway had been inhibited by U0126. Knockdown of RAB25 reduced cell cycle progression and cell growth. Apoptosis of ovarian cancer cells could be induced by knockdown of RAB25. These results support the tumorigenic role of RAB25 in ovarian cancer cells.