[Show abstract][Hide abstract] ABSTRACT: Tetramethylpyrazine (TMPZ) is one of the active compounds extracted from the traditional Chinese medicinal herb Chuanxiong and several studies have shown it to possess anticancer properties. However, its effectiveness in gastric cancer and its cellular mechanisms are relatively unknown. The present study aimed to investigate the effect of TMPZ on SGC7901 cells, and it was demonstrated that a high dose of TMPZ inhibited cell viability and induced apoptosis by stimulating AMP-activated protein kinase (AMPK) through the generation of reactive oxygen species (ROS). Furthermore, TMPZ-induced apoptosis resulted in the sequential events beginning with the translocation of Bax, the collapse of mitochondrial membrane potential (ΔΨm), the release of cytochrome c and the activation of caspase-9 and -3. Each of these events was inhibited by compound C, a pharmacological inhibitor of AMPK. To the best of our knowledge, these results demonstrate for the first time that the induction of apoptosis by TMPZ in gastric cancer cells is associated with the activation of the ROS/AMPK pathway. AMPK activation induces apoptosis through the mitochondrial apoptotic pathway. In addition, these results raise the possibility that TMPZ may have a future therapeutic role in gastric cancer.
[Show abstract][Hide abstract] ABSTRACT: Rho-associated coiled-coil containing protein kinase 2 (Rock2) belongs to a family of serine/threonine kinases which are actived via interaction with Rho GTPases. Recently, overexpression of Rock2 has been demonstrated in human hepatocellular carcinoma (HCC), but the potential role of Rock2 in tumorigenesis remains unclear. Cdc25A acts as a key checkpoint during the G1/S phase and has also been found to be overexpressed in HCC. Here, we report that Rock2 regulates cell cycle progression via ubiquitination of Cdc25A in HCC. In HCC tissues, Rock2 and Cdc25A were aberrantly upregulated and revealed a significantly positive correlation. Knockdown of Rock2 inhibited HCC cell growth and promoted cell-cycle arrest at the G1/S phase via regulation of Cdc25A. When cells were exposed to DNA damage, Rock2 increased cell survival by regulating Cdc25A. Co-immunoprecipitation and immunofluorescence analyses indicated that Rock2 regulated Cdc25A via direct binding. Furthermore, knockdown of Rock2 activated Cdc25A ubiquitination and promoted its degradation. Our results defined a role for Rock2 in modulation of Cdc25A ubiquitination, indicating a novel mechanism of Cdc25A regulation and a potential function for Rock2 in the development of HCC.
Experimental Cell Research 06/2012; 318(16):1994-2003. · 3.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: FAT10 is known to execute its functions mainly through conjugation to different substrates, and these known functions include cytokine responses, apoptosis, mitosis, and tumorigenesis. Nonetheless, the known binding proteins of FAT10 cannot explain all its known functions. As such, the aim of this study was to identify unidentified conjugation proteins of FAT10.
The yeast two-hybrid system was employed in this study. FAT10 was used as the bait protein for screening of a cDNA library from a human hepatocellular carcinoma cell line, Hep3B. Protein interactions were confirmed based on localization studies and co-immunoprecipitation assays. The expression of mRNA and protein was determined using real-time polymerase chain reaction and western blot analyses, respectively.
In this study, we identified eukaryotic elongation factor 1A1 (eEF1A1) as a FAT10-specific binding protein. The binding between FAT10 and eEF1A1 was confirmed both in vivo and in vitro. We also found that, when the expression of FAT10 was reduced by siRNA knockdown, this resulted in downregulation of eEF1A1 expression at both the mRNA and protein levels in human hepatocellular carcinoma cells.
We propose a model in which eEF1A1 serves as a substrate of FAT10 to accomplish, in part, its functions in regulating the biological behavior of tumor cells. Since both eEF1A1 and FAT10 are important for tumorigenesis and development, comprehending the mechanisms of this interaction can provide clues for identification of novel strategic targets for drug screening and molecular typing, and possibly in the development of new effective therapeutic strategies against hepatocellular carcinoma.
Digestive Diseases and Sciences 05/2012; 57(9):2347-54. · 2.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study examined whether variation in exonic and flanking sequences of the human HLA-F adjacent transcript 10 (FAT10) gene might be associated with susceptibility and clinicopathological development of hapatocellular carcinoma (HCC).
A total of 522 subjects, including 268 healthy controls and 254 patients with HCC, were recruited. Genotyping was accomplished using DNA sequencing. Haplotypes were determined through genotypic and disequilibrium analysis of identified single nucleotide polymorphisms (SNPs).
Ten SNPs in FAT10 were identified, namely -143 A/G (rs362535), -121 A/G (rs2272991), +3446 C/T, +3476 T/C (rs2076484), +3527 T/C (rs2076485), +3607 T/C (rs2076486), +3620 C/G (rs2076487), +3803 C/G (rs8337), +3809 G/T (rs7757931), +3833 G/C (rs444013). +3446 C/T is a novel polymorphism. The -143 A/G, -121 A/G, +3476 T/C, +3607 T/C, +3620 C/G and +3809 G/T genotypes were associated with a decreased risk for HCC (all P-values <0.05). No SNPs were associated with disease clinicopathology (all P-values>0.05). Furthermore, under the analysis of haplotype, GGCTCGT and AGCTCGT were related to reduced HCC risk (OR=0.41, 95%CI=0.24, 0.70, P<0.05 and OR=0.43, 95% CI=0.22, 0.983, P<0.05, respectively), while AATTTCG was associated with an increased risk (OR=1.64, 95% CI=1.24-2.17, P<0.05). 10-million permutation testing also indicated the AATTTCG and GGCTCGT haplotypes to be associated with HCC susceptibility (both P-values<0.05). Patients carrying AATTTCG were in higher tumor and clinical stages (P<0.05), while GGCTCGT appeared protective in this context (P<0.05).
This study provides first evidence that FAT10 gene genetic variants may be involved in the susceptibility and clinicopathological development of HCC in the Chinese Han population.
Asian Pacific journal of cancer prevention: APJCP 01/2011; 12(8):2117-22. · 1.50 Impact Factor