ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of tea polyphenols on the proliferation of human prostate cancer cells and its possible mechanism.</p><p><b>METHODS</b>We cultured androgen-independent prostate cancer DU145 cells in the medium with different concentrations (50, 100, 250 and 500 microg/ml) of tea polyphenols, and those in the normal medium as the control. After 48 hours of culture, we detected the survival rate of the cells by MTT assay and determined the expression of survivin by Western blot and quantitative RT-PCR.</p><p><b>RESULTS</b>At 48 hours, the survival rates of the prostate cancer DU145 cells were 0.97 +/- 0.12, 0.71 +/- 0.07, 0.20 +/- 0.03 and 0.08 +/- 0.01 in the 50, 100, 250 and 500 microg/ml tea polyphenols treatment groups, all significantly reduced as compared with the control group (P < 0.01) except that of the 50 microg/ml group (P = 0.42). Furthermore, the survival rate continued to decrease with the prolonging of time, dropping below 5% at 96 hours except in the 50 microg/ml group. The grey values of the survivin expression in the 100, 250 and 500 microg/ml tea polyphenols groups were 13 425 +/- 34, 2 017 +/- 24 and 1 274 +/- 22, respectively, at 48 hours, significantly lower than 15 075 +/- 48 in the control group (P < 0.01). Moreover, the content of survivin mRNA at 48 hours was markedly lower in the 50, 100, 250 and 500 microg/ml treatment groups (0.74 +/- 0.03, 0.64 +/- 0.02, 0.52 +/- 0.01 and 0.21 +/- 0.02) than in the control (P < 0.01).</p><p><b>CONCLUSION</b>Tea polyphenols can inhibit the proliferation of human prostate cancer DU145 cells, which may be associated with the decreased expression of the survivin gene.</p>
Subject(s)
Humans , Male , Cell Line, Tumor , Cell Proliferation , Inhibitor of Apoptosis Proteins , Metabolism , Polyphenols , Pharmacology , Prostatic Neoplasms , Pathology , Tea , ChemistryABSTRACT
Akt1 is a serine-threonine protein kinase that has been implicated in the control of cellular metabolism,survival and growth.Elevated expression of Akt1 has been noted in a significant percentage of human tumors,promoting cellular metastasis.Conversely,some studies have revealed hyperactivated Akt1 inhibited the invasiveness and metastasis of breast cancer cells.To clarify the definite effect of Akt1 on tumorigenesis and development,Akt1 was silenced by RNAi in the highly metastatic murine breast cancer 4T1 cells.Akt1 silencing didn't affect the proliferation of breast cancer cells in MTT assay,while reduced the migration in Transwell assay.Consistent with the above results,Akt1 silencing didn't change the primary tumor weight,but significantly suppressed lung metastasis of 4T1 cells.These observations indicated Akt1 plays an important role in murine breast cancer metastasis,and suggested that Akt1 might be a therapeutic target for breast cancer metastasis.
ABSTRACT
Previous studies have revealed Twist,a basic helix-loop-helix transcription factor,plays an important role in breast cancer metastasis.To clarify the molecular mechanism of its involvement in cancer metastasis,Twist was silenced by RNAi in highly metastatic 4T1 cells.Then microarray chips were used to investigate the gene-expression pattern of the Twist-knockdown 4T1 cells and the normal 4T1 cells.The results indicated that silencing of Twist significantly suppressesed lung metastasis of 4T1 cells in vivo.Direct comparison of gene-expression profiles showed that 167 genes in Twist-knockdown cells differed dramatically in expression levels from those in control cells.Among the 167 genes,26 well-known tumor-associated genes,including 15 up-regulated and 11 down-regulated genes were found.These genes appear to be regulated by Twist during breast tumorigenesis.The findings provide new insights into the mechanism by which Twist is involved in tumorigenesis.
ABSTRACT
It is well documented that altered biosynthesis of cell surface N-linked oligosaccharides is associated with the transformed cells and tumors.N-acetylglucosaminyltransferase Ⅱ(GnT-II;EC 2.4.1.143)is a medial Golgi enzyme that catalyses the incorporation of a GlcNAc residue in ?-1,2 linkage to the Man-?-1,6 arm of the N-glycan core.This is an essential step in the biosynthetic pathway leading from hybrid to complex N-glycans.Because functional GnT-Ⅱ is an prerequisite of N-Acetylglucosaminyltransferase V performance,It was speculated that GnT-Ⅱ was involved in cancer development and progression.The expression of GnT-Ⅱ in mouse breast cancer cells 67NR and 4T1 which have different behavior of metastasis was analysed using RT-PCR.The amounts of GnT-Ⅱ in the highly metastatic cell 4T1 increased to 1.53 times of the lowly metastatic cell 67NR.To determine the association of GnT-Ⅱ with tumor progression,the GnT-Ⅱ encoding gene was amplified with RT-PCR and cloned into retrovirus vector pMSCV,resulting in pMSCV-GnT-Ⅱ.The recombinant plasmid was transfected into 4T1 and the transfected cells were selected in the medium containing puromycin,which were harvested to detect the adhesion ability to fibronection and the migration potential by transwell system.The cell adhesion to fibronectin was weakened by 67% and migration potential was increased by 82%.The data indicates that GnT-Ⅱ mediates cell adhesion and migration,thus may play an important role in cancer metastasis.