人参、三七、川芎提取物对血管平滑肌细胞衰老相关β半乳糖苷酶及p16-cyclinD/CDK-Rb通路的影响

目的：观察人参、三七、川芎提取物延缓自发性高血压大鼠（spontaneously hypertensive rat,SHR）血管平滑肌细胞（vascular smooth muscle cell,VSMC）衰老的作用及其可能的细胞周期调控机制。方法：取大鼠胸主动脉用于分离VMSC,采用原代细胞培养的方法建立SHR大鼠VMSC模型,实验分为Wistar-Kyoto（WKY）大鼠对照组、SHR模型组、缬沙坦组、中药低剂量组和中药高剂量组。采用衰老相关β半乳糖苷酶（senescence-associatedβ-galactosidase,SA-β-gal）染色法观察细胞衰老情况,流式细胞仪分析细胞周期分布,逆转录聚合酶链式反应和蛋白质印迹法检测各组细胞p16、细胞周期蛋白D1（cyclin D1）、细胞周期蛋白依赖性激酶4（cyclin-dependent kinase4,CDK4）和成视网膜母细胞瘤蛋白（retinoblastoma protein,Rb）的表达。结果：SA-β-gal染色显示,与WKY组比较,SHR组SA-β-gal阳性细胞数明显增多（P〈0.01）,人参、三七、川芎提取物可使SHR VSMC SA-β-gal阳性细胞数明显减少（P〈0.01）;流式细胞仪检测显示,与WKY组比较,SHR组VSMC在G1期明显减少,S期细胞明显增加,中药干预后SHR的VSMC G1期细胞明显增多,S期细胞明显减少（P〈0.05）;实时荧光定量聚合酶链式反应检测显示,与WKY组比较,SHR组VSMC的p16和Rb mRNA表达量明显减少,cyclin D1和CDK4mRNA表达增加;人参、三七、川芎提取物干预后SHR VSMC p16和Rb mRNA表达量增加,cyclin D1和CDK4mRNA减少。蛋白质印迹法显示,与WKY组比较,SHR组VSMC的p16蛋白表达量明显减少,cyclin D1、CDK4和磷酸化Rb蛋白表达量明显增加（P〈0.05）;中药干预后SHR VSMC p16蛋白表达增加,cyclin D1、CDK4和磷酸化Rb蛋白表达量减少（P〈0.05）。结论：人参、三七、川芎提取物通过改变p16-cyclin D/CDK-Rb通路因子的表达而发挥延缓SHR VSMC衰老的作用。     

Triptolide inhibits rat vascular smooth muscle cell proliferation and cell cycle progression via attenuation of ERK1/2 and Rb phosphorylation

Background

Drug-eluting stents have demonstrated a substantial reduction of restenosis and currently are gaining a leading position in the intervention field. Triptolide, a purified extract from Chinese herb medicine Tripterygium wilfordii hook F, exhibits antiproliferative and pro-apoptotic function in vitro and in vivo. In the present study, we investigated effects of triptolide on in-stent restenosis in vivo and in vitro, and study the biological mechanism of this drug.

Methods

Rat aortic smooth muscle cells were cultured and treated with different concentration of triptolide (0, 1, 10, and 50 nM). For cell viability, we used trypan blue exclusion (TBE) survival assay. Flow cytometry was used to study the influence of triptolide on VSMCs cell cycle. Signal proteins were detected by western blotting analysis. Triptolide coated stents had been implanted in the iliac arteries of New Zealand rabbits. After 4 weeks, the stented iliac artery segments were processed for embedding, staining and histomorphometric analysis.

Results

Triptolide of concentration 10 nM, 50 nM significantly inhibited fetal calf serum-induced VSMC proliferation (p < 0.05). The accumulation of triptolide-treated cells at the G1/S-interphase was dose dependent. Triptolide completely blocked the cell cycle progression at 50 nM. Western blotting analysis showed decreased ERK1/2 MAP kinase phosphorylation level, significantly increased p21^cip1 expression and reduced retinoblastoma protein (pRb) phosphorylation after 24 h of triptolide treatment. 4 weeks after the surgery, the arterial wall morphology was shown that triptolide-coated stent has less neointimal vs bare metal stent.

Conclusions

Our study indicates that triptolide exert inhibitory effect on VSMC proliferation, inactivation of MAPK pathway and modulation of cell cycle proteins p21^cip1 and Rb are relating mechanisms. Triptolide drug-eluting stents attenuated neointimal formation after stent implantation in rabbit vessel. We believe that triptolide may potentially be useful in treating cardiovascular restenosis after PCI.     

Detection of mosaic RB1 mutations in families with retinoblastoma

The RB1 gene mutation detection rate in 1,020 retinoblastoma families was increased by the use of highly sensitive allele specific‐PCR (AS‐PCR) to detect low‐level mosaicism for 11 recurrent RB1 CGA>TGA nonsense mutations. For bilaterally affected probands, AS‐PCR increased the RB1 mutation detection sensitivity from 92.6% to 94.8%. Both RB1 oncogenic changes were detected in 92.7% of sporadic unilateral tumors (357/385); 14.6% (52/357) of unilateral probands with both tumor mutations identified carried one of the tumor mutations in blood. Mosaicism was evident in 5.5% of bilateral probands (23 of 421), in 3.8% of unilateral probands (22 of 572), and in one unaffected mother of a unilateral proband. Half of the mosaic mutations were only detectable by AS‐PCR for the 11 recurrent CGA>TGA mutations, and not by standard sequencing. This suggests that significant numbers of low‐level mosaics with other classes of RB1 mutations remain unidentified by current technology. We show that the use of linkage analysis in a two‐generation retinoblastoma family resulted in the erroneous conclusion that a child carried the parental mutation, because the founder parent was mosaic for the RB1 mutation. Of 142 unaffected parental pairs tested, only one unaffected parent of a proband (0.7%) showed somatic mosaicism for the proband's mutation, in contrast to an overall 4.5% somatic mosaicism rate for retinoblastoma probands, suggesting that mosaicism for an RB1 mutation is highly likely to manifest as retinoblastoma. Hum Mutat 0, 1–10, 2009. © 2009 Wiley‐Liss, Inc.     

Effects of carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone on the growth inhibition in human pulmonary adenocarcinoma Calu-6 cells

Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) is an uncoupler of mitochondrial oxidative phosphorylation in eukaryotic cells. Here, we evaluated the in vitro effects of FCCP on the growth of Calu-6 lung cancer cells. FCCP inhibited the growth of Calu-6 cells with an IC₅₀ of approximately 6.64 ± 1.84 μM at 72 h, as shown by MTT. DNA flow cytometric analysis indicated that FCCP induced G1 phase arrest below 20 μM of FCCP. Treatment with FCCP decreased the level of CDKs and cyclines in relation to G1 phase. In addition, FCCP not only increased the p27 level but also enhanced its binding with CDK4, which was associated with hypophosphorylation of Rb protein. While transfection of p27 siRNA inhibited G1 phase arrest in FCCP-treated cells, it did not enhance Rb phosphorylation. FCCP also efficiently induced apoptosis. The apoptotic process was accompanied with an increase in sub-G1 cells, annexin V staining cells, mitochondria membrane potential (MMP) loss and cleavage of PARP protein. All of the caspase inhibitors (caspase-3, -8, -9 and pan-caspase inhibitor) markedly rescued the Calu-6 cells from FCCP-induced cell death. However, knock down of p27 protein intensified FCCP-induced cell death. Moreover, FCCP induced the depletion of GSH content in Calu-6 cells, which was prevented by all of the caspase inhibitors. In summary, our results demonstrated that FCCP inhibits the growth of Calu-6 cells in vitro. The growth inhibitory effect of FCCP might be mediated by cell cycle arrest and apoptosis via decrease of CDKs and caspase activation, respectively. These findings now provide a better elucidation of the mechanisms involved in FCCP-induced growth inhibition in lung cancer.     

6-OHDA induces cycle reentry and apoptosis of PC12 cells through activation of ERK1/2 signaling pathway

This study investigated the effect and mechanism of cell cycle reentry induced by 6-hydrodopamine （6-OHDA） in PC12 cells. By using neural differentiated PC12 cells treated with 6-OHDA, the apoptosis model of dopaminergic neurons was established. Cell viability was measured by MTT. Cell apoptosis and the distribution of cell cycle were assessed by flow cytometry. Western blot was used to detect the activation of extracellular regulator kinasel/2 （ERK1/2） pathway and the phosphorylation of retinoblastoma protein （RB）. Our results showed that after PC12 cells were treated wtih 6-OHDA, the viability of PC12 cells was declined in a concentration-dependent manner. Flow cytornetry revealed that 6-OHDA could increase the apoptosis ratio of PC12 cells in a time-dependent manner. The percentage of ceils in G0/G1 phase of cell cycle was decreased and that in S phase and G2/M phase increased. Simultaneously, ERK1/2 pathway was activated and phosphorylated RB increased. It was concluded that 6-OHDA could induce cell cycle reentry of dopaminergic neurons through the activation of ERK1/2 pathway and RB phosphorylation. The aberrant cell cycle reentry contributes to the apoptosis of dopaminergic neurons.     

Predictive value of p53 and pRb expression in superficial bladder cancer patients treated with BCG and interferon-alpha

BACKGROUND: Nuclear p53 and retinoblastoma protein (pRb) were reported to be poor prognostic indicators for transitional cell carcinoma of the bladder. The authors sought to determine the prognostic value of nuclear p53 and pRb in superficial bladder transitional cell carcinoma patients who were treated with intravesical bacille Calmette-Guerin (BCG) or BCG with interferon-alpha (IFN-alpha). METHODS: A prospective histological review was performed for 80 superficial bladder transitional cell carcinoma patients who underwent postresection intravesical regimes of BCG (81 mg, n = 33 or 27 mg, n = 20) or BCG (27 mg) with IFN-alpha (n = 27), and followed for a mean of 4.5 years. Hematoxylin and eosin (H & E) and immunoperoxidase staining were performed on tissue sections. Nuclear p53 and pRb immunoreactivity were assessed semiquantitatively, by using a combination of staining extent and intensity, to categorize overexpression or underexpression. Data were analyzed by using chi-square analysis, multiple logistic regression, and Kaplan-Meier curves. RESULTS: pRb expression was not associated with patient outcome after BCG-alone therapy, but pRb underexpression was significantly associated with BCG nonresponse and tumor recurrence (P = .047) after BCG and IFN-alpha (BCG + IFN-alpha) therapy. Low-grade tumors were associated with pRb overexpression, with or without nuclear p53 underexpression (P = .019; P = .043, respectively). p53 expression alone or in combination with pRb expression had no significant relation with tumor response to BCG alone or BCG + IFN-alpha with respect to recurrence, progression, or cancer-specific death. CONCLUSIONS: Nuclear pRb underexpression may be predictive of nonresponse and cancer recurrence after intravesical BCG + IFN-alpha therapy. Nuclear p53 expression or its combination with pRb expression is not associated with post-BCG clinical outcome, so p53 expression or p53 with pRb expression should not be used to influence decisions concerning BCG-alone or BCG + IFN-alpha therapy.     

Curcumin induces the degradation of cyclin E expression through ubiquitin-dependent pathway and up-regulates cyclin-dependent kinase inhibitors p21 and p27 in multiple human tumor cell lines

Curcumin, a well-known chemopreventive agent, has been shown to suppress the proliferation of a wide variety of tumor cells through a mechanism that is not fully understood. Cyclin E, a proto-oncogene that is overexpressed in many human cancers, mediates the G(1) to S transition, is a potential target of curcumin. We demonstrate in this report a dose- and time-dependent down-regulation of expression of cyclin E by curcumin that correlates with the decrease in the proliferation of human prostate and breast cancer cells. The suppression of cyclin E expression was not cell type dependent as down-regulation occurred in estrogen-positive and -negative breast cancer cells, androgen-dependent and -independent prostate cancer cells, leukemia and lymphoma cells, head and neck carcinoma cells, and lung cancer cells. Curcumin-induced down-regulation of cyclin E was reversed by proteasome inhibitors, lactacystin and N-acetyl-L-leucyl-L-leucyl-L-norleucinal, suggesting the role of ubiquitin-dependent proteasomal pathway. We found that curcumin enhanced the expression of tumor cyclin-dependent kinase (CDK) inhibitors p21 and p27 as well as tumor suppressor protein p53 but suppressed the expression of retinoblastoma protein. Curcumin also induced the accumulation of the cells in G1 phase of the cell cycle. Overall, our results suggest that proteasome-mediated down-regulation of cyclin E and up-regulation of CDK inhibitors may contribute to the antiproliferative effects of curcumin against various tumors.     

Surgical repair of rhegmatogenous retinal detachment in eyes harboring active retinoblastoma

Background: Intraocular surgeries are classically contraindicated for patients with active Retinoblastoma (RB) due to the risk of tumor dissemination. Unfortunately, RB treatment may be complicated by rhegmatogenous retinal detachment (RD) that necessitates surgical repair especially in a child who is monocular from enucleation of the contralateral eye.

Objective: To assess the outcome of surgical repair of rhegmatogenous RD in children with RB using non-drainage scleral buckling.

Results: Rhegmatogenous RD was diagnosed in three eyes of three children during treatment of RB; one of which had associated tractional RD. All patients received systemic chemotherapy, cryotherapy, and thermal therapy. RD was present at the site of the most recent cryotherapy in all of the three eyes. RD was repaired externally with a scleral buckling procedure without subretinal fluid drainage in each of the three eyes. The retina reattached completely after surgery in two eyes and only partially in one eye. In one eye, which had the tractional component, complete retinal attachment was not achieved and thus enucleation was performed. Orbital or metastatic retinoblastoma was detected in none of the cases on follow-up at 6–36 months.

Conclusions: Scleral buckling without subretinal fluid drainage is a useful technique for repairing rhegmatogenous RD in eyes with RB mainly in the absence of a tractional component.     

Predictive value of cell cycle biomarkers in nonmuscle invasive bladder transitional cell carcinoma

PURPOSE: We determined whether the combined expression of p53, p21, p27 and pRB is associated with outcomes of patients with nonmuscle invasive bladder transitional cell carcinoma. MATERIALS AND METHODS: Immunohistochemical staining for p53, p21, p27 and pRB was performed on archival bladder specimens from 9 normal controls and 74 patients who underwent transurethral bladder tumor resection for Ta, Tis and/or T1 transitional cell carcinoma. RESULTS: Normal urothelium had wild type status of p53, pRB, p21 and p27. p53 expression was altered in 34% of patients with transitional cell carcinoma, pRB in 39%, p21 in 35% and p27 in 47%. When analyzed separately, p53, pRB and p21 were each independently associated with tumor progression. Combination of biomarkers stratified patients into statistically significantly different risk groups for disease recurrence and progression. When tumor stage and grade were modeled with all 4 biomarkers, p53 and p27 were the sole independent predictors of disease recurrence and progression. After controlling for the effects of tumor grade and stage, the incremental number of altered biomarkers was associated with an increased risk of bladder cancer recurrence (p for trend = 0.011) and progression (p for trend = 0.005). The risk ratio for disease recurrence and progression increased incrementally with the number of biomarkers altered. CONCLUSIONS: Combinations of p53, pRB, p21 and p27 had cooperative/synergistic effects stratifying patients into different risk groups. Higher total numbers of altered biomarkers were independently associated with an increased risk of disease progression and death. Prospective trials are necessary to usher bladder cancer management into the age of molecular biomarkers.