槲皮素通过调控p21/cip1和p27/kip1蛋白的稳定性抑制口腔鳞状细胞癌细胞增殖

目的:探究槲皮素通过调控p21/cip1和p27/kip1蛋白的稳定性对口腔鳞状细胞癌细胞增殖的影响。方法:CCK-8试剂盒检测口腔鳞状细胞癌细胞(SCC-15)增殖情况;流式细胞术检测SCC-15细胞周期分布;Western blot检测CyclinD1/CDK复合体、p21/cip1、p27/kip1、p-GSK3β、GSK3β、p53和c-Myc蛋白表达;qRT-PCR检测SCC-15细胞p21/cip1和p27/kip1 mRNA表达;激光共聚焦显微镜检测SCC-15细胞中p21/cip1和p27/kip1蛋白亚细胞定位;放线菌酮蛋白合成抑制实验检测SCC-15细胞中p21/cip1和p27/kip1蛋白半衰期。结果:与对照组相比,槲皮素呈剂量依赖性(6.25μmol/L、12.5μmol/L、25μmol/L、50μmol/L、100μmol/L和200μmol/L)抑制SCC-15细胞增殖(P<0.05),槲皮素在48 h对SCC-15细胞的IC 50为80.07μmol/L。与对照组相比,槲皮素(40μmol/L和80μmol/L)可显著升高SCC-15细胞中G 1/G 0期细胞比例,显著降低S期和G 2/M期细胞比例(P<0.05),呈剂量依赖性抑制CyclinD1/CDK复合体、p-GSK3β和c-Myc蛋白表达(P<0.05),促进p21/cip1和p27/kip1的mRNA和蛋白表达,促进GSK3β和p53的蛋白表达(P<0.05)。与对照组相比,槲皮素(80μmol/L)促进SCC-15细胞中p21/cip1蛋白由细胞质转移至细胞核(P<0.05),显著提高p21/cip1和p27/kip1蛋白生物半衰期(P<0.05),对p27/kip1蛋白的亚细胞定位无显著影响(P>0.05)。结论:槲皮素通过调控p21/cip1和p27/kip1蛋白的稳定性抑制口腔鳞状癌细胞增殖。     

Naftopidil, a selective alpha-1 adrenoceptor antagonist, inhibits growth of human prostate cancer cells by G1 cell cycle arrest

Alpha-1 adrenoceptor antagonists are generally prescribed for benign prostate hyperplasia with lower urinary tract symptoms. Naftopidil, a selective alpha-1 adrenoceptor antagonist, is frequently used in Japan because it has fewer side effects. Here we demonstrate for the first time that naftopidil has growth inhibitory effect in androgen-sensitive and -insensitive human prostate cancer cell lines. The concentrations causing 50% inhibition (IC50) of cancer cell growth were 22.2 +/- 4.0 microM in androgen-sensitive LNCaP cells and 33.2 +/- 1.1 microM in androgen-insensitive PC-3 cells. FACS analysis revealed that cell growth inhibition by naftopidil was due to the arrest of the G1 cell cycle. Expressions of p27(kip1) and p21(cip1) were significantly increased in LNCaP cells treated with naftopidil. In PC-3 cells, naftopidil induced p21(cip1) but not p27(kip1). In vivo, oral administration of naftopidil to nude mice inhibited the growth of PC-3 tumors as compared to vehicle-treated controls. These results suggest that naftopidil may be useful in the chemoprevention of prostate cancer and the intervention of hormone refractory prostate cancer.     

Expression of p21<Superscript>waf1/cip1</Superscript>, p27<Superscript>kip1</Superscript>, p63 and Androgen Receptor in Low and High Gleason Score Prostate Cancer

The aim of this study was to investigate the expression of p21^waf1/cip1, p27^kip1, p63 and androgen receptor proteins in relation to serum prostate specific antigen levels in low and high Gleason score prostate cancers. Biopsies of patients suffering from prostate adenocarcinoma of low (3 + 3 to 3 + 4) and high (5 + 4 to 5 + 5) Gleason scores (13 cases each group) were immunostained for positive regulators of cell cycle control (p21^waf1/cip1 and p27^kip1), and essential markers of normal prostate gland ontogeny (p63) and growth (androgen receptor) to find differentially expressed markers of malignant progression. Serum prostate specific antigen levels were also monitored at the time of biopsy and following anti-androgen therapy. All cases except one in each group were androgen receptor positive. P63 and p21^waf1/cip1 proteins detected in normal basal cell nuclei were lost in all but one studied tumors respectively. P27^kip1 protein, however, was detected in all low Gleason score prostate cancers, but it was found in only 7/13 high score cases. Prostate specific antigen levels, either pre- or post-treatment, did not show strict correlation with the p27^kip1 results. The low to high grade dedifferentiation of prostate adenocarcinoma is accompanied with the down-regulation of p27^kip1 protein, which may be an important molecular sign of the lost cell cycle control.     

Cyclooxygenase-2 promotes human cholangiocarcinoma growth: evidence for cyclooxygenase-2-independent mechanism in celecoxib-mediated induction of p21waf1/cip1 and p27kip1 and cell cycle arrest

The expression of cyclooxygenase-2 (COX-2) is increased in human cholangiocarcinoma. However, the biologic function and molecular mechanisms of COX-2 in the control of cholangiocarcinoma cell growth have not been well established. This study was designed to examine the direct effect of COX-2 and its inhibitor celecoxib on the growth of human intrahepatic cholangiocarcinoma cells. Overexpression of COX-2 or treatment with prostaglandin E(2) (PGE(2)) enhanced human cholangiocarcinoma cell growth, whereas antisense depletion of COX-2 in these cells decreased PGE(2) production and inhibited growth. These findings demonstrate a direct role of COX-2-mediated PGE(2) in the growth regulation of human cholangiocarcinoma cells. Furthermore, the COX-2 inhibitor celecoxib induced a dose-dependent inhibition of cell growth, cell cycle arrest at the G(1)-S checkpoint, and induction of cyclin-dependent kinase inhibitors p21(waf1/cip1) and p27(kip1). However, the high concentration of celecoxib (50 micro M) required for inhibition of growth, the incomplete protection of celecoxib-induced inhibition of cell growth by PGE(2) or COX-2 overexpression, and the fact that overexpression or antisense depletion of COX-2 failed to alter the level of p21(waf1/cip1) and p27(kip1) indicate the existence of a COX-2-independent mechanism in celecoxib-induced inhibition of cholangiocarcinoma cell growth.     

Statin-induced depletion of geranylgeranyl pyrophosphate inhibits cell proliferation by a novel pathway of Skp2 degradation

Statins, such as lovastatin, can induce a cell cycle arrest in the G1 phase. This robust antiproliferative activity remains intact in many cancer cells that are deficient in cell cycle checkpoints and leads to an increased expression of CDK inhibitor proteins p27^Kip1 and p21^Cip1. The molecular details of this statin-induced growth arrest remains unclear. Here we present evidence that lovastatin can induce the degradation of Skp2, a subunit of the SCF^Skp2 ubiquitin ligase that targets p27^Kip1 and p21^Cip1 for proteasomal destruction.The statin-induced degradation of Skp2 is cell cycle phase independent and does not require its well characterised degradation pathway mediated by APC/C^Cdh1- or Skp2 autoubiquitination. An N-terminal domain preceding the F-box of Skp2 is both necessary and sufficient for its statin mediated degradation. The degradation of Skp2 results from statin induced depletion of geranylgeranyl isoprenoid intermediates of cholesterol biosynthesis. Inhibition of geranylgeranyl-transferase-I also promotes APC/C^Cdh1-independent degradation of Skp2, indicating that de-modification of a geranylgeranylated protein triggers this novel pathway of Skp2 degradation.     

p21cip1和p27kip1基因遗传多态与食管癌及贲门癌发病风险的关联

背景与目的：有研究表明p21^cip1和p27^kip1的基因多态性与乳腺癌、肺癌、前列腺癌等肿瘤易感性有关。本研究分析中国北方高发区人群食管鳞状细胞癌（ESCC）和贲门腺癌（GCA）与勺p21^cip1和p27^kip1基因多态性之间的关系。方法：应用聚合酶链反应-限制性片段长度多态性（PCR—RFLP）方法检测299例ESCC患者、256例GCA患者及437名健康对照人群p21^cip1 3’非翻译区和p27^kip1第109位密码子基因多态性分布情况。结果：ESCC患者组p21^cip1 T等位基因型频率（42．8％）显著高于健康对照组（36．7％）（P=0．02）,ESCC和GCA患者组p27^kip1等位基因型频率（分别为96．8％和96．1％）均显著高于健康对照组（92．9％）（P值分别为0．00和0．02）。ESCC患者组p21^cip1基因型频率分布与健康对照组相比有显著性差异（P=0．04）,与C／C和C／T基因型相比,T／T基因型可显著增加ESCC的发病风险（校正OR=1．93,95％CI=1．12～3．94）ESCC和GCA患者细p27^kip1基因型频率分布与健康对照组相比均有显著性差异（P分别为0．00和0．01）,与V／G和G／G基因型相比,V／V基因型可显著增加ESCC和GCA的发病风险（校正OR分别为2．44和2．01,95％CI分别为1．2l～4．02和1.12～3．68）。当按吸烟和上消化道肿瘤家族史状况进行分层分析时发现,与V／G和G／G基因型相比,V／V基因型可显著增加吸烟人群患ESCC和GCA（校正OR分别为2．24和2．61,95％C1分别为1.14～4．03和1．25～3．82）以及有家族史人群患ESCC的发病风险（校正OR=2．04,95%CI=1．04～3．43）．两基因联合分析显示,携带p21^cip1T／T和p27^kip1V／V基因型可显著增加患食管癌和贲门癌的发病风险（校正OR分别为3．78和2．56,95?分别为1．46～5．89和1．06～4．78）。结论：在中国北方人群中,p21^cip1基因多态性可能与食管癌的易感性有关,p27^kip1基因多态性可能与食管癌和贲门癌的易感性有关．而且这两个基因的多念性可能存食管癌和贲门癌发病中起联合作用．     

Pure seminoma: A review and update

Background

Prostate cancer (PrCa) displays resistance to radiotherapy (RT) and requires radiotherapy dose escalation which is associated with greater toxicity. This highlights a need to develop radiation sensitizers to improve the efficacy of RT in PrCa. Ionizing radiation (IR) stimulates pathways of IR-resistance and survival mediated by the protein kinase Akt but it also activates the metabolic energy sensor and tumor suppressor AMP-Activated Protein Kinase (AMPK). Here, we examined the effects of the polyphenol resveratrol (RSV) on the IR-induced inhibition of cell survival, modulation of cell cycle and molecular responses in PrCa cells.

Methods

Androgen-insensitive (PC3), sensitive (22RV1) PrCa and PNT1A normal prostate epithelial cells were treated with RSV alone (2.5-10 μM) or in combination with IR (2-8 Gy). Clonogenic assays, cell cycle analysis, microscopy and immunoblotting were performed to assess survival, cell cycle progression and molecular responses.

Results

RSV (2.5-5 μM) inhibited clonogenic survival of PC3 and 22RV1 cells but not of normal prostate PNT1A cells. RSV specifically sensitized PrCa cells to IR, induced cell cycle arrest at G1-S phase and enhanced IR-induced nuclear aberrations and apoptosis. RSV enhanced IR-induced expression of DNA damage (γH2Ax) and apoptosis (cleaved-caspase 3) markers as well as of the cell cycle regulators p53, p21^cip1 and p27^kip1. RSV enhanced IR-activation of ATM and AMPK but inhibited basal and IR-induced phosphorylation of Akt.

Conclusions

Our results suggest that RSV arrests cell cycle, promotes apoptosis and sensitizes PrCa cells to IR likely through a desirable dual action to activate the ATM-AMPK-p53-p21^cip1/p27^kip1 and inhibit the Akt signalling pathways.     

Inhibition of proteasome-dependent degradation of Wee1 in G2-arrested Hep3B cells by TGF beta 1

Transforming growth factor beta1 (TGF beta 1)-induced G2 arrest was observed when a proliferation inhibitory function of the retinoblastoma protein (Rb) was compromised, but the mechanism underlying the G2 arrest was poorly characterized compared with that of G1 arrest. In the present study, we characterized G2 arrest induced by TGF beta1 (1 ng/mL) in the Rb-negative hepatoma cell line (Hep3B) and compared with G1 arrest in the Rb-positive hepatoma cell line (Huh7). Activities of cyclin-dependent kinases (CDK) 2 and cell division cycle (CDC) 2 were markedly decreased at 24 h, the time when cell-cycle arrest became apparent in both cell lines. However, considerable amounts of inactive CDC2-cyclinB1 complexes were present in the nucleus of G2-arrested Hep3B but were not present in G1-arrested Huh7. The inhibitory phosphorylation of CDC2 on Tyr-15 was significantly elevated at 12-24 h, and its levels gradually declined during G2 arrest in Hep3B. In particular, augmentation of CDK inhibitors p21cip1 and p27kip1 and Wee1 kinase and diminution of CDC25C phosphatase coincided with induced Tyr-15 phosphorylation and inhibition of CDC2. Wee1 in Hep3B was unstable and was degraded in a proteasome-dependent manner, but it became substantially stabilized within 6 h of TGF beta 1 treatment. Moreover, a Wee1 inhibitor, PD0166285, abrogated the TGF beta 1-induced G2 arrest in Hep3B. These findings suggest that TGF beta 1 induced G2 arrest in Hep3B at least in part through stabilization of Wee1 and subsequent increase in Tyr-15 phosphorylation and inhibition of CDC2.     

Research on cell cycle retardation,apoptosis and the expression of antioncogene p57<Superscript>Kip2</Superscript> by radioactive rays in nasopharyngeal carcinoma cell line in vitro

Objective To study cell cycle retardation, apoptosis and the expression of antioncogene p57^kip2 by radioactive rays in nasopharyngeal carcinoma cells. Methods Cell cycle retardation, apoptosis and cell survival rate induced by radioactive rays were tested by the methods of flow cytometry and MTT method. The expression of antioncogene p57^kip2 was detected by immunohistochemistry and Western blot. Results After irradiation, G1 phase had no obvious retardation, S phase showed transient delay. There was a positive correlation between irradiation dosage and retardation strength in G2/M phase (P < 0.01). Peak value appeared at 24 h after 12 Gy irradiation, then decreased. There was a positive correlation between apoptosis incidence and irradiation dosage or after-irradiation time extention (P < 0.01). There was a negative correlation between cell survival rate and irradiation dosage or apoptosis incidence (P < 0.01). The expression of p57^kip2 protein was up-regulated along with the prolongation of time and dosage after irradiation (P < 0.01). Conclusion G2/M phase arrest, apoptosis and the up-regulation of the expression of p57^kip2 protein all can reflect predict the radiosensitivity of nasopharyngeal carcinoma cells.     

In vitro and in vivo studies of the anticancer action of terbinafine in human cancer cell lines: G0/G1 p53-associated cell cycle arrest

Terbinafine (TB) (Lamisil), a promising oral antifungal agent used worldwide, has been used in the treatment of superficial mycosis. In our study, we demonstrated that TB dose-dependently decreased cell number in various cultured human malignant cells. Flow cytometry analysis revealed that TB interrupts the cell cycle at the G0/G1 transition. The TB-induced cell cycle arrest in colon cancer cell line (COLO 205) occurred when the cyclin-dependent kinase (cdk) system was inhibited just as the levels of p53, p21/Cip1 and p27/Kip1 proteins were augmented. In the TB-treated COLO 205, the binding between p53 protein and p53 consensus binding site in p21/Cip1 promoter DNA probe was increased. Pretreatment of COLO 205 with p53-specific antisense oligodeoxynucleotide decreased the TB-induced elevations of p53 and p21/Cip1 proteins, which in turn led to arrest in the cell cycle at the G0/G1 phase. Moreover, in the p53 null cells, HL60, TB treatment did not induce cell cycle arrest. Taken together, these results suggest an involvement of the p53-associated signaling pathway in the TB-induced antiproliferation in COLO 205. We further examined whether administration of TB could affect the growth of tumors derived from human colon cancer cells in an in vivo setting. COLO 205 cells implanted subcutaneously in nude mice formed solid tumor; subsequent intraperitoneal injections of TB (50 mg/kg) led to obvious decline in tumor size, up to 50-60%. In these tumors, increases in the p21/Cip1, p27/Kip1 and p53 proteins and the occurrence of apoptosis were observed. Combined treatment with TB and nocodazole (ND), a clinically used anticancer agent, potentiated the apoptotic effect in COLO 205. These findings demonstrate for the first time that TB can inhibit the proliferation of tumor cells in vitro and in vivo.     

p27kip1的过表达对肾癌细胞增殖及凋亡的影响

目的:研究外源性 p27kip1 基因对肾癌细胞周期、细胞凋亡及增殖的影响。方法:将含p27cDNA的质粒在脂质体介导下在体外转染肾癌GRC 1细胞,Western Blot、FCM及MTT检测分析外源性 p27kip1 蛋白在细胞内的表达,观察其对细胞周期、凋亡及细胞增殖的影响。结果:体外转染 GRC 1 细胞 48 h 后, p27 蛋白在p27kip1转染后的 GRC 1 细胞中高表达。FCM检测表明,细胞停滞于 G1 期,实验组 G1 期细胞占66 9%,并出现亚G1 凋亡峰;而空白对照组和转染空载体组 G1 期细胞分别为 32 2% 和33 8%。MTT 法检测表明,转染 p27cDNA 后,实验组细胞增殖明显受抑。结论: p27kip1 基因在体外转染GRC 1细胞并过表达p27kip1蛋白,抑制细胞由G1 期向 S期过渡,从而抑制细胞增殖,诱导细胞凋亡。     

Antitumor activity of suberoylanilide hydroxamic acid against human oral squamous cell carcinoma cell lines in vitro and in vivo

It has been reported recently that histone deacetylase inhibitors (HDACIs) can block the growth of a variety of malignant tumor cells by reversing the silencing of the tumor suppressor genes; these will be the anticancer agents of the next generation. In this study, we evaluated the antitumor effects of the HDACI suberoylanilide hydroxamic acid (SAHA) on oral squamous cell carcinoma (OSCC) and investigated its molecular mechanism. SAHA suppressed the in vitro proliferation of OSCC cell lines in a dose- and time-dependent manner. Flow cytometric analyses showed that treatment with SAHA led to G1 phase cell-cycle arrest of OSCC cells, accompanying a decrease in the percentage of S-phase cells. Western blot analyses demonstrated that the expression of p21 protein was remarkably augmented and hyperacetylation of p53 was induced after SAHA treatment. These results suggest that administration of SAHA suppresses OSCC growth through G1 phase arrest. Additionally, we observed that the growth of xenograft SAS tumors in nude mice was significantly blocked by the administration of SAHA without major adverse effects.     

Additive effects of tamoxifen and the farnesyl transferase inhibitor FTI-277 on inhibition of MCF-7 breast cancer cell-cycle progression

The efficacy of tamoxifen in the hormonal therapy of breast cancer is well established, but therapeutic resistance is inevitable. FTIs are a new class of anticancer drugs that are in phase III clinical evaluation. Since the mechanisms of action of these 2 classes of drugs are different, we tested the combination of tamoxifen and FTI-277 on inhibiting proliferation of hormone-dependent MCF-7 human breast cancer cells. An additive effect on cell proliferation was demonstrated, accompanied by an additive G(0)/G(1) arrest. The major effect of the combination of the 2 drugs was to maintain p21(waf/cip1) at an intermediate level, higher than that observed in the presence of tamoxifen alone. This was associated with an additive effect on inactivation of cyclin E-Cdk2 complexes and decreased phosphorylation of pRb and p130 pocket proteins. These effects were accompanied by increased association of 2 CDIs, p27(kip1) and p21(waf/cip1), with cyclin E-Cdk2 complexes. These data demonstrate that the additive effect is likely predominantly due to the recruitment of p27(kip1) and, to a lesser extent, p21(waf/cip1) into the cyclin E-Cdk2 complexes. Together, these results suggest that the combination of FTI and tamoxifen may increase the antitumor effect of either drug alone in breast cancer.     

蛋白酶体抑制剂MG132诱导HL-60细胞凋亡前G2/M期阻滞及机制

背景和目的:蛋白酶体(proteasome)抑制剂能够诱导多种肿瘤细胞凋亡,是一种潜在的有应用前景的抗肿瘤剂.本研究旨在探讨蛋白酶体抑制剂MGl32(Z-Leu-Leu-Leu-CHO)诱导白血病细胞HL-60凋亡和C2/M期阻滞的机制.方法:采用荧光显微镜观察、流式细胞术和免疫印迹研究测定MG132诱导HL-60细胞凋亡和周期阻滞及机制.结果:2μmol/L的MG132能够有效地诱导HL-60细胞凋亡,用药后24 h就显现有细胞凋亡;在MG132诱导HL-60细胞凋亡出现之前有一个明显的G2/M期阻滞,加MG132后12 h时G2/M期时相百分比为63.42±2.02;24 h时加MG132组细胞凋亡为16.67±1.48,与对照组G2/M期时相百分比为7.29±3.01及细胞凋亡为0相比,两者之间有显著性差别(P＜0.01);咖啡因CAF能够减少MG132诱导HL-60细胞出现的G2/M期阻滞,同时也减少凋亡细胞的比例;细胞周期检查点的负调控因子p21waf/cip1蛋白在加MG132处理后3 h有明显的表达,但并未能检测到p53和p27蛋白.结论:MG132诱导HL-60细胞凋亡之前有一个明显的G2/M期阻滞,p21蛋白表达明显上调提示:是p21waf/cip1而不是p53或其同源蛋白参与了其中的调控.     

Paradoxical correlations of cyclin-dependent kinase inhibitors p21waf1/cip1 and p27kip1 in metastatic colorectal carcinoma.

The cyclin-dependent kinase inhibitors (CDIs) p27kip1 and p21waf1/cip1 are key cell cycle-negative regulatory enzymes. The objective of this study was to correlate expression of p27kip1 and p21waf1/cip1 with survival, chemotherapy responsiveness, and expression of the proliferation marker Ki-67 in patients with advanced colorectal cancer. Immunohistochemistry was performed with antibodies to p27kip1, p21waf1/cip1, and Ki-67 on samples from 66 patients with metastatic colorectal carcinoma. Interpretation was performed by visual inspection and automated image analysis. Patients who obtained a response to chemotherapy had greater p21waf1/cip1 tumor staining with a mean of 10.0 positive cells/high-powered field, compared with 4.5 positive cells/high-powered field for nonresponders (P = 0.03). A positive Spearman correlation was seen between Ki-67 and p27kip1 (r = 0.48; P = 0.0001), as well as between Ki-67 and p21waf1/cip1 (r = 0.48; P = 0.0001). A trend toward shorter survival was seen in patients with positive specimens (median survival of 10 months for patients with both p27kip1- and p21waf1/cip1-positive specimens, compared with 22 months for patients with neither p27kip1- nor p21waf1/cip1-positive specimens). In contrast to that previously reported in normal colonic mucosa or early-stage colorectal cancer, we observed positive correlations of Ki-67 with both p27kip1 and p21waf1/cip1, a trend toward greater CDI staining indicating worse prognosis, and greater p21waf1/cip1 staining in tumors that were chemosensitive. These findings suggest that in the metastatic setting, CDIs may show altered function, compared with their role in the normal cell cycle.