Long noncoding RNA DANCR promotes invasion of prostate cancer through epigenetically silencing expression of TIMP2/3.

LncRNA DANCR suppresses differentiation of epithelial cells, however, its function in prostate cancer development is still unknown. In the present study, we found the expression of DANCR increases in prostate cancer tissues and cells compared to normal prostate tissues and cells, moreover, DANCR promotes invasion and migration of prostate cancer cells in vitro and metastasis of tumor xenografts in nude mice. Mechanistically, we found that TIMP2/3, which are critical metastasis inhibitor of prostate cancer, were down-regulated by DANCR synergistically with EZH2 through epigenetically silencing their promoter by chromatin immunoprecipitation assay. In addition, we further investigated whether DANCR is regulated by the differentiation-promoting androgen-androgen receptor (AR) pathway and found that DANCR expression is repressed by androgen-AR; furthermore, DANCR impedes the upregulation of TIMP2/3 and the suppression of invasion and migration by androgen-AR. On the other hand, interestingly, we found that in prostate cancer cells DANCR knockdown decreased the promotion of invasion and migration by the treatment of enzalutamide, which is an AR inhibitor. In summary, our results indicate that DANCR promotes prostate cancer invasion and metastasis through repressing the expression of TIMP2/3, and suggest that DANCR could be a potential target for preventing prostate cancer metastasis, and knockdown DANCR may lessen the potential side effect of AR inhibitor.

Krüppel-like factor 5 promotes apoptosis triggered by tumor necrosis factor α in LNCaP prostate cancer cells via up-regulation of mitogen-activated protein kinase kinase 7.

OBJECTIVES: Krüppel-like factor 5 (KLF5) modulates multiple cell processes in different cancers. It is frequently deleted and inactivated in prostate cancer and may exert a tumor suppressor function. However, how KLF5 inhibits the progression of prostate cancer is still not clear. In the present study, we identified how KLF5 and tumor necrosis factor α (TNFα) pathway, which can induce apoptosis in cancer, regulate each other in LNCaP prostate cancer cells. MATERIAL AND METHODS: The expression of messenger RNA and protein was detected by real-time polymerase chain reaction assay and western blot analysis, respectively. To identify whether KLF5 regulates the activity of TNFα downstream pathway, we constructed a stable KLF5 knockdown or KLF5 overexpressing cell line with lentivirus-containing short hairpin RNA targeting KLF5 or full-length KLF5 in LNCaP cells. Cell apoptosis was determined through flow cytometry assay. In addition, the regulation of KLF5 on target gene transcription was detected by reporter luciferase activity assay, and the binding of KLF5 on target promoter was detected through oligonucleotides pull-down analysis. RESULTS: We found that TNFα induced the expression of KLF5 at both messenger RNA and protein levels; moreover, TNFα up-regulated KLF5 through TNF receptor 1 but not through TNF receptor 2 in LNCaP cells. Knockdown of KLF5 decreased apoptosis induced by TNFα, whereas cell apoptosis was increased by KLF5 overexpression. Consistently, expression of cleaved PARP and caspase-3 induced by TNFα was decreased by KLF5 knockdown, whereas it was increased by overexpressed KLF5. JNK activity is essential for the apoptosis induced by TNFα. We found that knockdown of KLF5 not only decreased the phosphorylation of JNK induced by TNFα, but also down-regulated the transcription of mitogen-activated protein kinase kinase 7 (MKK7), an upstream kinase of JNK, by binding to the MKK7 promoter. CONCLUSIONS: Our results indicate that KLF5 is an essential transcription regulator of MKK7 kinase and promotes the apoptosis induced by TNFα in LNCaP cells. Loss of KLF5 in prostate cancer may decrease cell response to TNFα-inducing apoptosis and facilitate cancer initiation and progression; moreover, KLF5 could be a potential molecular marker for predicting the effect of high-dose TNFα on tumor growth inhibition in prostate cancer.

Tetrandrine suppresses proliferation, induces apoptosis, and inhibits migration and invasion in human prostate cancer cells.

Tetrandrine (TET), a traditional Chinese medicine, exerts remarkable anticancer activity on various cancer cells. However, little is known about the effect of TET on human prostate cancer cells, and the mechanism of function of TET on prostate cancer has not yet been elucidated. To investigate the effects of TET on the suppression of proliferation, induction of apoptosis, and inhibition of migration and invasion in human prostate cancer cell lines, DU145 and PC-3. Inhibition of growth was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and clone formation assay, and flow cytometry analysis was performed to detect the induction of apoptosis. Activation of poly (ADP-ribose) polymerase, caspase-3, Akt, phospho-Akt, Bcl-2, and Bax was analyzed by Western blotting. Wound healing assay and transwell migration assay were used to evaluate the effect of TET on migration and invasion of cancer cells. TET inhibited the growth of DU145 and PC-3 cells in a dose- and time-dependent manner. Cell cloning was inhibited in the presence of TET in DU145 and PC-3 cells. TET suppressed the migration of DU145 and PC-3 cells. Transwell invasion assay showed that TET significantly weakened invasion capacity of DU145 and PC-3 cells. TET exhibited strong inhibitory effect on proliferation, migration, and invasion of prostate cancer cells. In addition, TET induced apoptosis in a dose-dependent manner by activating the caspase cascade and inhibiting phosphoinositide 3-kinase-Akt signal pathway. The accumulating evidence suggests that TET could be a potential therapeutic candidate against prostate cancer in a clinical setting.

Chemiluminescence determination of melamine with Luminol-K3Fe(CN)6 system.

A sensitive chemiluminescence (CL) method was developed for determining melamine in urine and plasma samples based on the fact that melamine can remarkably enhance the chemiluminescence of Luminol-K3 Fe(CN)6 system in alkaline medium. The determination conditions were optimized. Under optimum conditions, the chemiluminescence intensity had a good linear relationship with melamine in the range of 9.0 × 10-9 - 7.0 × 10-6 g/mL with a correlation coefficient of 0.9992. The detection limits (3σ) were 3.54 ng/mL for urine sample and 6.58 ng/mL for plasma sample. The average recoveries of melamine were 102.6% for urine sample and 95.1% for plasma sample. Melamine in samples was extracted with liquid-liquid extraction procedures and the assay results coincided very well with that determined with flow injection chemiluminescence method. The method provides a reproducible and stable approach for sensitive detection and quantification of melamine in urine and plasma samples.