Novobiocin decreases SMYD3 expression and inhibits the migration of MDA-MB-231 human breast cancer cells.

SET and MYND domain-containing protein 3 (SMYD3) is a histone methyltransferase that plays an important role in transcriptional regulation in human carcinogenesis, and heat-shock protein HSP90A has been shown to increase the activity of SMYD3. We previously reported that overexpression of SMYD3 stimulated the migration of cells. In this study, we further found that novobiocin, a HSP90 inhibitor, could decrease the expression of SMYD3 and dose dependently inhibit the proliferation and migration of MDA-MB-231 human breast cancer cells. As a control, the short hairpin RNA (shRNA) targeting SMYD3 gene also showed similar effects with novobicin. This study is the first to show that novobiocin can inhibit the migration of breast cancer cells and such event may involve the downregulation of SMYD3. These findings might throw light on the development of novel therapeutic approaches to human cancers, and lend further understanding to the potential role of SMYD3 in human carcinogenesis.

Downregulation of survivin and activation of caspase-3 through the PI3K/Akt pathway in ursolic acid-induced HepG2 cell apoptosis.

Ursolic acid (UA), a naturally occurring pentacyclic triterpene, is a potent in-vitro anticancer agent, acting through control of growth, apoptosis and differentiation. As the mechanism of its proapoptotic effects on human hepatocellular carcinoma cells has not been extensively studied, we performed an in depth evaluation of the effects of UA on apoptosis in human HepG2 cells. UA was found to inhibit the proliferation of HepG2 cells in a concentration and time-dependent manner. After treatment, cells showed evidence of activation of apoptosis, including the presence of apoptotic bodies and DNA fragmentation. UA-induced apoptosis was accompanied by a significant decrease in bcl-2 and survivin expression, with the corresponding ratio of bax/bcl-2 increased. The treatment with UA also increased the protein level and enzymatic activity of caspase-3. Z-DEVD-fmk, a specific caspase-3 inhibitor, significantly inhibited both the cytotoxic effect and the DNA fragmentation induced by UA, demonstrating the requirement for caspase-3 activity in UA-induced apoptosis. Inactivation of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway was also involved, as inhibition of PI3K by LY294002 significantly increased UA-induced apoptosis. Kinetic experiments indicated that UA downregulated PI3K/p85 subunit (PI3K/p85) and phospho-Akt, before downregulating survivin. The further results also confirmed that LY294002 not only downregulated survivin alone, but considerably enhanced the repression of survivin combined with UA. UA therefore seemed to downregulate the expression of survivin by blocking PI3K/Akt. Taken together, the data suggest that the proapoptotic effect of UA on HepG2 cells is mediated by activation of caspase-3, and is highly correlated with inactivation of PI3K/Akt/survivin pathway.

[RAPD analysis on the germplasm resources of Gastrodia elata in Guizhou].

Genetic polymorphisms of genomic DNA of 15 samples from wild and culturaled Gastrodia elata Blume in Guizhou were analyzed by RAPD method. 12 effective primers are screened from 40 primers amplified a total number of 93 loci, among which 66 are polymorphic and the percentage of polymorphic loci (PPB) is 70.97%. UPGMA dendrogram analyzed by NTSYSpc, ver. 2.2 shows that Gastrodia elata have apparent genetic variance. Geological distribution and growing environment were significant factors for the polymorphism.

Knockdown of SMYD3 by RNA interference down-regulates c-Met expression and inhibits cells migration and invasion induced by HGF.

We previously reported that over-expression of SMYD3, a histone H3-K4 specific di- and tri-methyltransferase, plays a key role in cell viability, adhesion, migration and invasion. In this study, we investigated the mechanisms underlying these phenomena and found that knocking down SMYD3 expression in tumor cells significantly reduced the biological function of HGF and inhibited carcinoma cells migration and invasion. Due to the fact that the proto-oncogene c-Met encodes the high-affinity receptor for HGF, and the HGF-c-Met signaling plays a critical role in the tumor genesis, we further identified the partial correlation between SMYD3 and c-Met. The results showed that high expression of c-Met accompanied with over-expression of SMYD3. Silencing SMYD3 expression in tumor cells by specific shRNAs down-regulated c-Met gene transcription, while over-expressing SMYD3 induced c-Met transcription. Moreover, we demonstrated here that two SMYD3 binding sites within the c-Met core promoter region were significant in the transactivation of c-Met. The present findings provide significant insights into the epigenetic regulatory mechanisms of oncogene c-Met expression, and develop the strategies that may inhibit the progression of cancer migration and invasion.

Knockdown of SMYD3 by RNA interference inhibits cervical carcinoma cell growth and invasion in vitro.

Elevated expression of SMYD3 is a frequent genetic abnormality in several malignancies. Few studies knocking down SMYD3 expression in cervical carcinoma cells have been performed to date. In this paper, we established an inducible short hairpin RNA expression system to examine its role in maintaining the malignant phenotype of HeLa cells. After being induced by doxycycline, SMYD3 mRNA and protein expression were both reduced, and significant reductions in cell proliferation, colony formation and migration/invasion activity were observed in the SMYD3-silenced HeLa cells. The percentage of cells in sub-G1 was elevated and DNA ladder formation could be detected, indicating potent induction of apoptosis by SMYD3 knockdown. These findings imply that SMYD3 plays crucial roles in HeLa cell proliferation and migration/invasion, and that it may be a useful therapeutic target in human cervical carcinomas.