Hypoxia promotes the growth and invasiveness of prostate cancer cells by down-regulating miR-132 in vitro / 中华男科学杂志

<p><b>Objective</b>To explore the expression of miR-132 in prostate cancer and its effects on the growth and invasiveness of prostate cancer cells and the influence of hypoxia on the level of miR-132 and biological behavior of prostate cancer cells.</p><p><b>METHODS</b>Real time PCR was used to measure the expression level of miR-132 in the prostate cancer tissue, analyze its relationship with the clinical stage and Gleason score of prostate cancer, and determine the influence of hypoxia on the miR-132 level in the human prostate cancer PC3 cell line in vitro. Sulfor-hodamine B chromatometry and Matrigel invasion assay were employed to detect the effects of hypoxia and miR-132 mimic plasmid transfection on the viability and invasiveness of PC3 cells in vitro.</p><p><b>RESULTS</b>The miR-132 level in the prostate cancer was significantly declined to 52.38% (in T1－T2 stages) and 21.59% (in T3－T4 stages) of that in the cancer-adjacent tissue (both P<0.01). In hypoxia, the expression of miR-132 was significantly decreased in the PC3 cells (P<0.01). After 48 and 72 hours of transfection with miR-132 mimic plasmid, the viability of the PC3 cells was markedly reduced (P<0.05 or P<0.01), and their invasiveness decreased by 57.5% after 48 hours (P<0.01). However, there was no significant difference in the viability or invasiveness of the PC3 cells transfected with miR-132 mimic plasmid between normoxia and hypoxia.</p><p><b>CONCLUSIONS</b>The reduced expression of miR-132 is closely related to the clinical stage and Gleason score of prostate cancer. Hypoxia increases the viability and invasiveness of prostate cancer cells in vitro by down-regulating the expression of miR-132 and consequently may promote the growth and metastasis of prostate cancer.</p>

Downregulation of PAR expression induces the apoptosis of human prostate cancer PC3 cells and increases the Bcl-2/Bax ratio / 中华男科学杂志

<p><b>OBJECTIVE</b>To investigate the effects of the downregulated expression of the prostate androgen regulated (PAR) gene on the cell cycle and apoptosis of PC3 cells as well as on the expression level of Bcl-2/Bax.</p><p><b>METHODS</b>After transfecting PC3 cells with small interfering RNA (siRNA) targeting PAR, we detected the inhibitory effect of PAR depletion on the proliferation of the PC3 cells by MTT assay, determined their apoptosis by flow cytometry, and measured the expression levels of Bcl-2 and Bax by Western blot.</p><p><b>RESULTS</b>The expression of PAR was suppressed by siRNA, the G2-M phase PC3 cells were increased to (29.95 +/- 3.25)%, and the apoptosis of the cells was enhanced to (20.61 +/- 2.73)%, with statistically significant difference from the control group (P < 0.01). Western blot showed a decreased expression of Bcl-2, an increased expression of Bax, and an elevated ratio of Bax to Bcl-2.</p><p><b>CONCLUSION</b>Downregulation of the PAR expression increases the Bax/Bcl-2 ratio and Bax expression, and thus induces the G2-M phase arrest and apoptosis of PC3 cells.</p>

The deletion of La protein binding site in HBV RNA leads to instability of S gene mRNA / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the effect of deletion of the La protein binding site of HBV RNA, caused by its mutation, on the HBV S-mRNA stability of S gene, to study the role of the site in hepatitis B virus life cycle, and to try to find a new anti-HBV target in the future.</p><p><b>METHODS</b>A HBV vector with mutation related to the La protein binding site was constructed using molecular cloning and PCR based site directed mutagenesis, and the vector was named pHBV-mLa. The HBV RNA secondary structure of the site was calculated using a computer. Normal HBV vectors and mutant vectors were respectively transfected into HepG2 cells by Lipofectamine 2000. HBV S-mRNA levels in the two groups were analyzed using semi-quantitative RT-PCR, and HBsAg secretion into the culture media was tested using ELISA.</p><p><b>RESULTS</b>A HBV vector with mutation related to the La protein binding site was successfully constructed, and it was identified and confirmed using restriction analysis and sequencing. The HBV RNA secondary structure of the mutant vector was completely different to the stem-loop structure of the normal HBV vector. Semi-quantitative RT-PCR and ELISA analyses showed that the level of HBV S-mRNA in the mutant vector group was significantly lower than that in the normal HBV vector group (t'=12.703, P<0.05), and the expression efficacy of HBsAg was reduced in the mutant vector group (t= 44.648, P<0.01).</p><p><b>CONCLUSIONS</b>The change of La protein binding site in the HBV RNA caused by the mutation in HBV DNA disorganizes the stem-loop structure in the HBV RNA site. With the structural change, the La protein cannot bind the site and stabilize the HBV RNA (HBV S-mRNA), as the cleavage site in the upstream of the stem-loop structure is exposed to endoribonuclease. This results in HBV S-mRNA decay and affects the expression of the S gene. This study shows that only the sequence of this site in the HBV DNA is reserved, then the stem-loop structure in the La protein binding site will remain intact, and the disorganization of the stem-loop structure affects the stability of the transcripted HBV RNA. The La protein binding site in HBV RNA and the special secondary structure of the site are crucial to the life cycle of the hepatitis B virus.</p>

The relationship between the plasma homocysteine level and the polymorphism of MTHFR gene C667T in liver cirrhosis / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To study the relationship between the plasma homocysteine (HCY) level and the polymorphism of N(5), N(10)-methylenetetrahydrofolate reductase (MTHFR) gene C667T in liver cirrhosis.</p><p><b>METHODS</b>112 normal subjects and 87 liver cirrhosis patients were recruited in the study. Their plasma HCY levels were measured using high performance liquid chromatography with fluorescence detection and polymorphisms of their MTHFR gene were analyzed using PCR-RFLP.</p><p><b>RESULTS</b>The mean level of plasma HCY was significantly higher in patients with liver cirrhosis (21.71+/-4.86) micromol/L than that in healthy individuals (8.34+/-3.59) micromol/L. There were three kinds of MTHFR genotypes: +/+ (TT, homozygous mutation), +/- (CT, heterozygous mutation) and -/- (CC, wild type). The frequencies of the three genotypes were as follows: +/+, 29.9%; +/-, 52.9%; -/-, 17.2% in cirrhosis patients and +/+, 19.6%; +/-, 33.9%; -/-, 46.4% in normal subjects. The frequency of homozygous or heterozygous mutation was significantly higher in cirrhosis patients than that in the normal control. Moreover, plasma homocysteine level was markedly higher in patients with MTHFR genetic mutation than those without mutation.</p><p><b>CONCLUSIONS</b>Hyperhomocysteinemia may be an independent risk factor for liver cirrhosis. MTHFR is the main enzyme related to homocysteine metabolism. The genetic mutation of MTHFR C667T is possibly an important mechanism of hyperhomocysteinemia in liver cirrhosis. The level of plasma homocysteine may be an early indicator for liver cirrhosis.</p>