5-Azacytidine promotes invadopodia formation and tumor metastasis through the upregulation of PI3K in ovarian cancer cells

5-Azacytidine promotes HCC cell metastasis by up-regulating RDH16 expression

The level of DNA methylation could affect the expression of tumor promoting and tumor suppressor genes. DNA methyltransferase inhibitors could reduce high methylation levels in cancer and inhibit the progression of a variety of cancers, including HCC. However, the pro-metastatic effect of DNA methyltransferase inhibitors in some cancers suggest the potential risk of their use. Whether DNA methyltransferase inhibitors also promote metastasis in HCC remains unclear. Our study will explore the effect of DNA methyltransferase inhibitor 5-Azacytidine on HCC metastasis. Our study found that 5-Azacytidine inhibited the proliferation of HCC cells while promoting in vitro and in vivo metastasis of HCC. Mechanistically, our study showed that 5-Azacytidine increased the expression of RDH16 by decreasing the methylation of RDH16 gene promoter. RDH16 is a highly methylated gene and its expression is very low in hepatocellular carcinoma. 5-Azacytidine promoted the migration of hepatocellular carcinoma cells by increasing the expression of RDH16. Our results suggest that 5-Azacytidine up-regulates the expression of RDH16 by decreasing the methylation level of RDH16, and then promoting HCC metastasis. These findings suggest that 5-Azacytidine and even other DNA methyltransferase inhibitors may have the risk of promoting metastasis in HCC treatment. RDH16 could be used as a pro-metastasis biomarker in the treatment of HCC with DNA methyltransferase inhibitors.

Spontaneous Formation of 3D Breast Cancer Tissues on Electrospun Chitosan/Poly(ethylene oxide) Nanofibrous Scaffolds

Three-dimensional (3D) tissue culture has attracted a great deal of attention as a result of the need to replace the conventional two-dimensional cell cultures with more meaningful methods, especially for understanding the sophisticated nature of native tumor microenvironments. However, most techniques for 3D tissue culture are laborious, expensive, and limited to spheroid formation. In this study, a low-cost and highly effective nanofibrous scaffold is presented for spontaneous formation of reproducible 3D breast cancer microtissues. Experimentally, aligned and non-aligned chitosan/poly(ethylene oxide) nanofibrous scaffolds were prepared at one of two chitosan concentrations (2 and 4 wt %) and various electrospinning parameters. The resulting fabricated scaffolds (C2P1 and C4P1) were structurally and morphologically characterized, as well as analyzed in silico. The obtained data suggest that the fiber diameter, surface roughness, and scaffold wettability are tunable and can be influenced based on the chitosan concentration, electrospinning conditions, and alignment mode. To test the usefulness of the fabricated scaffolds for 3D cell culture, a breast cancer cell line (MCF-7) was cultured on their surfaces and evaluated morphologically and biochemically. The obtained data showed a higher proliferation rate for cells grown on scaffolds compared to cells grown on two-dimensional adherent plates (tissue culture plate). The MTT assay revealed that the rate of cell proliferation on nanofibrous scaffolds is statistically significantly higher compared to tissue culture plate (P ≤ 0.001) after 14 days of culture. The formation of spheroids within the first few days of culture shows that the scaffolds effectively support 3D tissue culture from the outset of the experiment. Furthermore, 3D breast cancer tissues were spontaneously formed within 10 days of culture on aligned and non-aligned nanofibrous scaffolds, which suggests that the scaffolds imitate the in vivo extracellular matrix in the tumor microenvironment. Detailed mechanisms for the spontaneous formation of the 3D microtissues have been proposed. Our results suggest that scaffold surface topography significantly influences tissue formation and behavior of the cells.

Preconditioning the rat heart with 5-azacytidine attenuates myocardial ischemia/reperfusion injury via PI3K/GSK3β and mitochondrial KATP signaling axis

5-Azacytidine is well known for its clinical usage in cancer treatments. The present study investigates the role of 5-azacytidine as a cardioprotective agent to ameliorate ischemia/reperfusion (I/R) injury. The cardioprotective effect of 5-azacytidine was evaluated in three experimental models: in vitro, ex vivo, and in vivo. The cardioprotective effect was evaluated via cell viability, hemodynamic indices, infarct size measurement, and assessment of histopathology, oxidative stress, and mitochondrial function. The experiments were repeated in the presence of PI3K/GSK3β and mitochondrial K_ATP (mtK_ATP ) cardioprotective signaling pathway inhibitors to understand the underlying mechanism. 5-Azacytidine improved the cell viability by 29% in I/R-challenged H9C2 cells. Both isolated rat heart and LAD ligation model confirmed the infarct sparing effect of 5-azacytidine against I/R. It also provided a beneficial effect by normalizing the altered hemodynamics, reducing the infarct size and cardiac injury markers, reversing the perturbation of mitochondria, reduced oxidative stress, and improved the pPI3K and pAKT protein expression from I/R. In addition, it also augmented the activation of PI3K/AKT and mtK_ATP signaling pathway, confirmed by using wortmannin (PI3K inhibitor), SB216763 (GSK3β inhibitor), and glibenclamide (mtK_ATP channel closer). The effectiveness of 5-azacytidine as a cardioprotective agent is attributed to its activation of the PI3K/GSK3β and mtK_ATP channel signaling axis, thereby preserving mitochondrial function and reducing oxidative stress.

Arg kinase mediates CXCL12/CXCR4-induced invadopodia formation and invasion of glioma cells

Compared with noninvasive tumor cells, glioma cells overexpress chemokine receptor type 4 (CXCR4), which exhibits significantly greater expression in invasive tumor cells than in noninvasive tumor cells. C-X-C motif chemokine ligand 12 (CXCL12, also known as stromal derived factor-1, SDF-1) and its cell surface receptor CXCR4 activate a signaling axis that induces the expression of membrane type-2 matrix metalloproteinase (MT2-MMP), which plays a pivotal role in the invasion and migration of various cancer cells; however, the specific mechanism involved in this is unclear. Recently, studies have shown that invadopodia can recruit and secrete related enzymes, such as matrix metalloproteinases (MMPs), to degrade the surrounding extracellular matrix (ECM), promoting the invasion and migration of tumor cells. Phosphorylated cortactin (pY421-cortactin) is required for the formation and maturation of invadopodia, but the upstream regulatory factors and kinases involved in phosphorylation have not been elucidated. In this study, we found that CXCL12/CXCR4 was capable of inducing glioma cell invadopodia formation, probably by regulating cortactin phosphorylation. The interaction of cortactin and Arg (also known as Abl-related nonreceptor tyrosine kinase, ABL2) in glioma cells was demonstrated. The silencing of Arg inhibited glioma cell invadopodia formation and invasion by blocking cortactin phosphorylation. Moreover, CXCL12 could not induce glioma cell invasion in Arg-knockdown glioma cells. Based on these results, it can be concluded that Arg mediates CXCL12/CXCR4-induced glioma cell invasion, and CXCL12/CXCR4 regulates invadopodia maturation through the Arg-cortactin pathway, which indicates that Arg could be a candidate therapeutic target to inhibit glioma cell invasion.

Downregulation of DACT-2 by Promoter Methylation and its Clinicopathological Significance in Prostate Cancer

Backgrounds: Dapper homolog (DACT) 2, a member of DACT gene family, is frequently down-regulated in various malignancies and linked to tumor progression. However, the regulatory mechanism of DACT-2 expression and its biological role in human prostate cancer (PCa) remains elusive. Here, we investigated the expression and an epigenetic change of DACT-2 in prostate cancer, and determined if these findings were correlated with clinicopathologic characteristics of PCa.

Methods: The expression profile of DACT-2 of was detected by qRT-PCR, Western blotting, and immunohistochemistry in four prostate cell lines (RWPE-1, LNCaP, PC-3 and DU145), 56 cases of frozen prostate tissues (forty-seven primary prostate carcinomas, nine paired noncancerous and cancerous prostate tissues) and a tissue microarray sets including 100 paraffin-embedded prostate samples (3 normal tissues, 2 cases of adjacent tissues and 95 cases of cancer). Subsequently, the regulatory mechanism of DACT-2 down-regulation was investigated through methylation-specific PCR (MSP) and bisulfite sequencing (BSP). The role of DACT-2 in prostate cancer cell migration and invasion was respectively examined by wound healing and transwell assay. After 5-aza-2'-deoxycytidine treatment of prostate cancer cells, qRT-PCR was used to detect whether the expression of DACT-2 gene mRNA in the cells recovered.

Results: Immunohistochemical results shown that the DACT-2 protein was strongly (3+) expressed in the cytoplasm of all 5 noncancerous tissues and 12.7% (12/95) prostate cancer (PCa) tissues. Whereas 68.4% (65/95) PCa samples and 18.9% (18/95) PCa tissues respectively displayed weakly (1+) expressed and moderately (2+) expressed. In addition, DACT-2 expression was negatively associated with Gleason score in tumor specimens (p=0.029). What's more, down-regulation and promoter methylation of DACT-2 were observed in 68.1% (32/47) frozen PCa tissues and all three prostate cancer cell lines. And, the expression of DACT-2 mRNA was restored by the treatment of demethylated drug 5-aza-2'-deoxycytidine in all prostate cancer lines. Prostate cancer cells invasion and migration were significantly suppressed by ectopic expression of DACT-2 in vitro.

Conclusions: Our study provides evidence that DACT-2 may be a useful biomarker for distinguishing prostate tumor tissues from non-cancerous samples and a potential target for epigenetic silencing in primary prostate Cancer.

Knockdown of ARK5 expression suppresses invasion of ovarian cancer cells

The aim of the current study was to investigate the effects and the molecular mechanisms of ARK5 in ovarian cancer cell invasion. The plasmid pGCsilencerU6/GFP/Neo‑RNAi‑ARK5 and the control vector with a scramble sequence were transfected into SKOV3 cells to establish ARK5‑deficient SKOV3 cells (siARK5/SKOV3) and a control cell line (Scr/SKOV3), respectively. Reverse transcription‑polymerase chain reaction (RT‑PCR) and Western blot analysis were used to determine the mRNA and protein expression levels of ARK5. Migration and invasion abilities of SKOV3 cells were determined in chemotaxis and invasion assays, respectively. The epidermal growth factor‑1 (EGF‑1)‑induced expression of matrix metallopeptidase (MMP)‑2 and MMP‑9, epithelial‑mesenchymal transition (EMT) and phosphorylation of mechanistic target of rapamycin kinase (mTOR) in siARK5/SKOV3 and Scr/SKOV3 cells were detected by western blot. RT‑PCR and western blot analyses demonstrated that the expression of ARK5 was significantly downregulated in siARK5/SKOV3 cells at the mRNA and protein levels (P<0.01). The migration and invasion abilities of siARK5/SKOV3 cells were markedly decreased compared with Scr/SKOV3 cells (P<0.01). In addition, the results demonstrated that EGF‑1‑induced expression of MMP‑2 and MMP‑9, EMT and phosphorylation of mTOR were suppressed in siARK5/SKOV3 cells as compared with Scr/SKOV3 cells (P<0.01). The current study demonstrated that ARK5 is a critical factor involved in SKOV3 cell invasion and ARK5 increases invasive potential by promoting EMT and activating the Akt‑mTOR‑MMPs pathway.