Troglitazone Induces G1 Arrest by p27Kip1 Induction That Is Mediated by Inhibition of Proteasome in Human Gastric Cancer Cells

We examined in the present study whether human gastric cancer cells express peroxisome proliferator-activated receptor γ (PPARγ), the effect of PPARy activation by troglitazone, a selective ligand, on cellular growth, and the mechanism of the growth arrest by troglitazone in gastric cancer cells. RT-PCR, northern blot and western blot analysis demonstrated that all four tested human gastric cancer cell lines, MKN–28, MKN–45, MKN–74 and KATO-III, expressed PPARγ mRNA and protein. WST–1 assay and flow cytometric analysis revealed that troglitazone inhibited the growth and induced G1 arrest in all four gastric cancer cell lines. To examine the role of p27^Kip1, a cyclin-dependent kinase inhibitor, in the G1 arrest by troglitazone, we determined p27^Kip1 protein expression by western blot analysis in gastric cancer cells that had been treated with troglitazone. Troglitazone increased p27^Kip1 in all four gastric cancer cell lines. Since it has been reported that the ubiquitin-proteasome system plays a vital role in the degradation of p27^Kip1 protein, we evaluated the hypothesis that inhibition of proteasome mediates the troglitazone-induced p27^Kip1 accumulation. Lactacystin, a proteasome inhibitor, inhibited cell growth and increased p27^Kilp1 expression in MKN–74 cells. It was further demonstrated that troglitazone inhibited proteasome activity in a dose-dependent manner in MKN–74 cells. All these results suggest that troglitazone inhibited proteasome activity, followed by induction of p27^Kipl, which arrests cells at the Gl phase of the cell cycle in gastric cancer cells. The troglitazone-mediated inhibition of the proteasome suggests a novel mechanism for the anti-proliferative effect of this agent in cancer cells.     

cyclin D 1 表达对cN2 口腔鳞癌患者TPF 诱导化疗的预测性研究*

目的:探讨cyclinD1 在局部晚期口腔鳞癌患者中预后价值以及能否作为多西他赛联合顺铂、5- 氟尿嘧啶（TPF）诱导化疗的预测生物标志物。方法:2008年3 月至2010年12月上海交通大学医学院附属第九人民医院局部晚期口腔鳞状细胞癌患者256 例行TPF 诱导化疗的前瞻性随机临床试验为研究对象。随机分为试验组（术前TPF 诱导化疗+ 手术+ 术后放疗）和对照组（手术+ 术后放疗）。 采用免疫组织化学法检测患者活检标本中cyclinD1 蛋白的表达情况,分析cyclinD1 表达与行TPF 诱导化疗患者预后的关系。结果:256 例患者中232 例符合cyclinD1 检测条件,其中cyclinD1 低表达者比高表达者有较高的总生存率（P =0.001）、无病生存率（P = 0.003）、无局部复发生存率（P = 0.004）和无远处转移生存率（P = 0.001）。 试验组和对照组之间的患者预后无差异,cyclinD1 表达水平与患者行TPF 诱导化疗后的疗效无显著相关性,但cN2 患者中cyclinD1 高表达者可从TPF 诱导化疗在总生存率（P = 0.024）和无远处转移生存率（P = 0.024）中获益。结论:cyclinD1 可作为局部晚期口腔鳞癌患者的预后生物标志物,cyclinD1 高表达的cN2 口腔鳞癌患者可从TPF 诱导化疗中获益。      

滑膜肉瘤组织中p27和cyclin E的表达及其临床意义

目的：探讨滑膜肉瘤组织中p27蛋白和cyclin E表达与临床病理指标的关系及判断预后的价值。方法：为46例滑膜肉瘤标本及10例正常滑膜组织的存档蜡块．应用免疫组化法观察p27蛋白和eyclin E的表达情况，并进行对比分析和相关性研究。结果：46例滑膜肉瘤组织中p27蛋白的阳性率为19．6％（9／46），正常滑膜组织中为90％（9／10），两者差异有统计学意义，P=0．01。p27蛋白表达与组织学分级有关，P=0．01；与性别、临床分期和组织学类型无关，P〉0．05。p27蛋白低表达者的5年生存率明显低于高表达者．P=0．01。eyclin E在滑膜肉瘤和正常滑膜组织中的表达差异有统计学意义，P=0．00；cyclin E的过表达在滑膜肉瘤的5年生存率组间差异有统计学意义，P=0．00。结论：p27低表达和cyclin E过表达与滑膜肉瘤的发生有关，是其预后差的有意义指标。联合检测p27和cyclin E表达对判断滑膜肉瘤的预后更有价值。     

鼻咽癌椎前间隙受侵的MRI评价及预后价值

目的 应用MRI评价鼻咽癌椎前间隙受侵对放、化疗预后的影响。方法 回顾分析2005—2007年间经病理证实的初治及无远处转移鼻咽癌患者333例临床资料。所有病例行鼻咽部和颈部MRI扫描并经二维、三维放疗或加化疗。Kaplan-Meier 法计算生存率并Logrank法检验,Cox法多因素预后分析。结果 随访率95.2%。鼻咽癌椎前间隙受侵139例(41.7%),椎前间隙受侵组较未受侵组T分期、临床分期明显增加(χ²=90.41、54.03,P=0.000、0.000)。鼻咽癌椎前间隙受侵组与未侵犯组5年总生存率(OS)、无远处转移生存率(DMFS)及无局部区域复发生存率(LRFS)分别为58.8%与77.5%(χ²=11.95,P=0.000),77.8%与85.0%(χ²=2.56,P=0.110)及88.3%与91.8%(χ²=1.51,P=0.220)。经N分期调整后两组5年OS差异仍有统计学意义(χ²=9.93,P=0.002)。多因素分析显示椎前间隙受侵不是影响鼻咽癌OS、DMFS、LRFS的预后因素(χ²=0.43、0.08、0.00,P=0.512、0.783、0.971)。结论 鼻咽癌椎前间隙受侵发生率较高且比未受侵者的OS低,但椎前间隙受侵不是影响鼻咽癌患者预后的因素。     

Protein Expression of Cell Cycle Regulator, p27Kip1, Correlates with Histopathological Grade of Non-Hodgkin's Lymphoma

The protein p27^Kp1 is one of the cyclin-dependent kinase inhibitors that are known to play important roles in the regulation of cell-cycle progression. Low levels of p27 expression in malignant cells are associated with poor prognosis in patients with breast, lung, colorectal and gastric cancers. To determine the relation of cyclin-dependent kinase inhibitors to histopathological grades of B-cell non-Hodgkin's lymphomas, the expression of p27, cyclin D1 and cyclin E in lymph node tissues was investigated in 56 patients with B-cell non-Hodgkin's lymphomas by western blotting and immunohistochemical techniques. High levels of p27 expression were observed in most lymph node tissue samples (93%) obtained from patients with low grade B-cell non-Hodgkin's lymphomas, while expression was low in lymph node tissue taken from all patients with intermediate and high grade B-cell non-Hodgkin's lymphomas. The difference in p27 expression in lymphoma tissues was significant among the different histopathological grades of B-cell non-Hodgkin's lymphomas ( P <0.01). The analysis of the survival time of patients showed that the reduction of p27 expression correlated with poor prognosis. Cyclin D1, showed a high level of expression in mantle cell lymphomas and high grade B-cell non-Hodgkin's lymphomas. Cyclin E showed limited expression in 18 of 31 lymphoma tissues. Both cyclin D1 and E protein expression were not significantly different among the grades of B-cell non-Hodgkin's lymphomas. These results demonstrate that the level of p27 expression in lymphoma tissue is an important parameter in the classification of B-cell non-Hodgkin's lymphomas and in the prediction of prognosis.     

Prognostic implication of cyclin E expression and its relationship with cyclin D1 and p27Kip1 expression on tissue microarrays of node negative breast cancer

BACKGROUND AND OBJECTIVES: Altered expression of cell-cycle regulators is prevalent in clinical breast cancer. This study was performed to analyze the impact of cyclin E expression to the outcome of breast cancer together with cyclin D1 and p27Kip1. METHODS: The correlation between cyclin D1/E and p27Kip1 expression was analyzed in tissue arrays of 175 node-negative breast cancers treated by the same chemotherapy composed of fluorouracil, cyclophosphamide, and methotrexate. Data from the immunohistochemical assays of three molecules were correlated and were analyzed with clinical outcome of the patients. RESULTS: Cyclin E expression was observed in 48 (27.4%) of 175 breast carcinomas. Cyclin E expression was significantly increased in young age patients and poorly differentiate tumors. Expression of cyclin E was significantly increased in cyclin D1 expressing tumors (P = 0.034). p27Kip1 expression was preserved above the 50% level in 87 tumors (49.7%) and was inversely correlated with cyclin E expression (P = 0.042). Ki67 labeling index was significantly increased in cyclin E-expressing tumors (P = 0.033) and was inversely related with p27Kip1 expression. In multivariate survival analysis, cyclin E expression was significant for the prediction of poor survival of the patients. CONCLUSIONS: Cyclin E expression was associated with poor prognosis and intimately correlated with the expression of cyclin D1 and p27Kip1. Integration of TMA technology allowed a high-throughput analysis for correlating molecular in situ findings with clinico-pathologic information.     

High cyclin E and low p27/Kip1 expressions are potentially poor prognostic factors in lung adenocarcinoma patients

Cyclin E is an important regulator of entry into the S phase of the cell cycle. p27/Kip1 (p27) binds to cyclin E/Cdk2 complex and negatively regulates cell proliferation. We immunohistochemically examined the expression of cyclin E and p27 in 98 cases of resected lung adenocarcinoma to evaluate the prognostic significance of cyclin E and p27. Cyclin E was expressed in 16 cases (16%), and p27 was expressed in 41 cases (42%). Using Kaplan-Meier survival analysis, patients with cyclin E positive (P=0.0017) and p27 negative (P=0.011), both individually and in combination (P<0.0001), had a worse prognosis. We also analyzed the relationship of these findings to clinicopathological parameters, which revealed that cyclin E-positive, p27-negative cases had a higher Ki67 expression (P=0.012) and a higher rate of lymph node metastasis (P=0.0078) than other groups. Our results suggested that cyclin E over expression, in association with p27 reduction in particular, may potentially be a poor prognostic factor in lung adenocarcinoma patients. However, to verify the prognostic significance of these factors, a multivariate analysis of a larger number of patients should be undertaken.     

RAF may induce cell proliferation through hypermethylation of tumor suppressor gene promoter in gastric epithelial cells

The extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK-MAPK) is critical in human malignancies. It remained to be established whether DNA methyltransferases (Dnmt) and proliferating cell nuclear antigen (PCNA) involved in DNA methylation during RAF-transformed cell proliferation. The plasmid of constitutively active RAF was used to transfect gastric cell GES-1 and cancer cell AGS. RAF promoted cell proliferation, growth in soft agar and induced cell cycle progress faster than empty plasmid by accelerating G1/S transition in both cell lines, a massive induction of cyclin D1 and PCNA expression was observed, along with reduced expression of p16^INK4A , p21^WAF1 and p27^KIP1. Methylation-specific polymerase chain reaction and bisulfite sequencing showed that the promoter of p16^INK4A was methylated in RAF-transformed cells, treatment with 5-aza-dC or PD98059 restored the expression of p16^INK4A, increased p21^WAF1 and p27^KIP1 partially, associated with upregulation of the activity of Dnmt in RAF-transformed cell GES-1, and also decreased the hypermethylation status of p16^INK4A , but not all CpG islands of p21^WAF1 and p27^KIP1 . These data suggest that RAF may induce cell proliferation through hypermethylation of tumor suppressor gene p16^INK4A , while the epigenetic inactivation of p21^WAF1 and p27^KIP1 may be not a key factor in RAF-transformed cells. ( Cancer Sci 2009; 100: 117–125)     

Low expression of p27(Kip1) is associated with tumor size and poor prognosis in patients with renal cell carcinoma

BACKGROUND: Proliferative activity in tumors depends on regulation of the cell cycle. p27(Kip1) (p27) plays a pivotal role as a negative regulator of the cell cycle. A decrease in p27 expression has been reported in many kinds of tumors, but little is known regarding p27 in patients with renal cell carcinoma (RCC). METHODS: Expression of p27 and the related cyclins (cyclin A, cyclin E, and cyclin D1) was examined immunohistochemically in 67 patients with of clear cell RCC. The Ki-67 labeling index (MIB-1 LI) and clinicopathologic parameters related to a poor prognosis also were analyzed. To determine their prognostic significance, univariate and multivariate survival analyses were performed. RESULTS: In tumors, there was considerable immunoreactivity for cyclin A, cyclin D1, and MIB-1, and the mean values for each were 1.08%, 16.1%, and 1.5%, respectively. Cyclin E expression was rare. The expression of p27 was correlated strongly with the expression of cyclin A (correlation coefficient, 0.432; P < 0.0004) and cyclin D1 (correlation coefficient, 0.476; P < 0.0004). Also, an inverse correlation was present between p27 expression and tumor size (P = 0.0377). In univariate analysis, the unfavorable prognostic factors were high TNM stage (P < 0.0001), large tumor size (P = 0.0016), high histologic grade (P = 0.0104), and low p27 expression (P < 0.0001). In multivariate analysis, high TNM stage (P = 0.0035) and low p27 expression (P = 0.0235) were independent prognostic factors for disease specific survival in patients with RCC. CONCLUSIONS: The results of this study suggest that low p27 expression may be a significant and independent, unfavorable prognostic factor in patients with renal cell carcinoma.     

非小细胞肺癌组织中PTEN/p27kip1的表达及其意义

目的检测PTEN、p27kip1、cyclin 3种蛋白在非小细胞肺癌组织的表达及与临床病理特征的关系.方法在60例非小细胞肺癌原发灶(包括37例鳞癌和23例腺癌)中应用免疫组织化学S-P法检测3种蛋白的表达.结果 60例肺癌原发灶中PTEN、p27kip1、cyclin 3种蛋白表达阳性率分别为:48.3%;41.7%;73.3%.PTEN与淋巴结转移显著相关(<0.05)p27kip1、cyclin 与淋巴结转移无关(>0.05)这3种蛋白表达均与肿瘤细胞分化程度显著相关(<0.05)与组织学类型无关(>0.05)60例非小细胞肺癌组织中,PTEN的表达与p27kip1呈显著正相关(P<0.01),而与cyclin 无明显相关(>0.05)p27kip1与cyclin 的表达之间呈显著负相关(P<0.01).结论 PTEN明显地抑制了非小细胞肺癌的浸润和转移,p27kip1表达缺失与肺癌细胞的分化有关,PTEN/p27kip1衰老诱导途径在非小细胞肺癌的恶性进展中起着很重要的作用.     

Expression of cell-cycle regulators, cyclin E and p21WAF1/CIP1, potential prognostic markers for gastric cancer.

AIMS: The deregulation of cyclin, cyclin-dependent kinases (CDKs) and their inhibitors could have a crucial role in the development of diverse human cancers. METHODS: In this study, we analysed the expression of cyclin D1, cyclin E, p21WAF1/CIP1 and p27KIP1 in 84 surgically resected gastric cancers by immunohistochemistry with long-term follow-up (median 38 months). We also evaluated the relation between each cell cycle regulator and various clinicopathological findings, including age, sex, histological grade, tumour location, tumour type and stage and lymph-node metastasis. RESULTS: Overexpression of cyclin D1 and E was detected in 21/84 (25%) and 34/84 (40.5%) patients, respectively. Normal gastric epithelium showed consistently positive immunostain for p21WAF1/CIP1 and p27KIP1 in more than 50% of nuclei. Loss of p21WAF1/CIP1 and p27KIP1 expression was noted in 45/84 (53.6%) and 44/84 (52.4%) patients, respectively. Among the various clinicopathological findings, overexpression of cyclin E was associated with lymph-node metastasis (P=0.003) and recurrence (P=0.043). Loss of p21WAF1/CIP1 expression was more frequent in diffuse type cancers (P=0.005) and was correlated with recurrence (P=0.002) and death (P=0.002). Overexpression of cyclin E and loss of p21WAF1/CIP1 expression were significantly correlated with decreased disease-free (P=0.037; P= 0.001) and overall (P=0.031; P=0.001) survival. CONCLUSIONS: These results suggest that immunohistochemical analysis for cell cycle regulators, especially cyclin E and p21WAF1/CIP1, might be a useful prognostic indicator in gastric cancer.     

Cyclin D1, p53, and p21Waf1/Cip1 expression is predictive of poor clinical outcome in serous epithelial ovarian cancer.

PURPOSE: Dysregulation of cell cycle control, in particular G(1)-S-phase transition, is implicated in the pathogenesis of most human cancers, including epithelial ovarian cancer (EOC). However, the prognostic significance of aberrant cell cycle gene expression in EOC remains unclear. EXPERIMENTAL DESIGN: The expression of selected genes from the pRb pathway that regulates G(1)-S-phase progression, including cyclin D1, p16(Ink4a), cyclin E, p27(Kip1), p21(Waf1/Cip1), and p53, was examined in a consecutive series of 134 serous EOC using immunohistochemistry and the results correlated to disease outcome. RESULTS: Molecular markers predictive of reduced overall survival in univariate analysis were overexpression of cyclin D1 (P = 0.03) and p53 (P = 0.03) and reduced expression of p27(Kip1) (P = 0.05) and p21(Waf1/Cip1) (P = 0.02), with the latter three also being prognostic for a shorter progression-free interval. In addition, patients displaying overexpression of p53 with concurrent loss of p21(Waf1/Cip1) had a significantly shorter overall (P = 0.0008) and progression-free survival (P = 0.0001). On multivariate analysis, overexpression of cyclin D1 and combined loss of p21(Waf1/Cip1) in the presence of p53 overexpression were independent predictors of overall survival. Similarly, the combination of p21(Waf1/Cip1) loss and p53 overexpression was independently predictive of a shorter progression-free interval. Overexpression of p53 and cyclin E and reduced expression of p27(Kip1) and p21(Waf1/Cip1) were significantly associated with increasing tumor grade. CONCLUSIONS: This study confirms that dysregulation of cell cycle genes is common in EOC, and that aberrant expression of critical cell cycle regulatory proteins can predict patient outcome in serous EOC.     

Reduced Expression of Cyclin–dependent Kinase Inhibitor p27Kipl Is Associated with Advanced Stage and Invasiveness of Gastric Carcinomas

Reduced expression of a cyclin–dependent kinase inhibitor p27^Kipl has recently been shown to predict poor survival of patients with breast and colorectal cancers. We studied the expression of p27^Kipl in gastric carcinomas by northern blotting, western blotting and immunohistochemistry to determine whether lack of p27 has implications for aggressiveness of gastric cancer. Reduced expression of p27 was detected in 40% of the gastric carcinomas at the mRNA level, while it was detected in 57% at the protein level. No gross alterations of the p27 gene were observed in any of the cases examined by Southern blot analysis. Inimunohistochemical studies revealed that the expression of p27 was well preserved in most of the gastric adenomas, whereas it was so in only 26% of the gastric carcinomas. Fifty–six percent of the carcinomas showed almost no p27–positive cells. Decrease of p27–positive cells significantly correlated with advanced stage, depth of tumor invasion and lymph node metastasis. The expression of p27 showed an inverse correlation with the expression of cyclin E. These findings suggest that reduction of p27^Klpl protein may reflect the progression of gastric carcinomas and may be an indicator of high–grade malignancy.     

Cyclin E expression in breast cancer: predicting germline BRCA1 mutations, prognosis and response to treatment.

BACKGROUND: Elevated levels of the cell cycle protein cyclin E, and low levels of its inhibitor, p27(Kip1), have been associated with a poor prognosis following breast cancer. Some studies have found that germline mutations in the breast cancer susceptibility gene, BRCA1, are also associated with an inferior survival rate. The relationship between cyclin E/p27(Kip1) levels, BRCA1 status and outcome has not been studied in detail. PATIENTS AND METHODS: We analyzed a historical cohort of 288 Ashkenazi Jewish women who were diagnosed with breast cancer between 1980 and 1995 and were previously tested for BRCA1/2 mutations. Protein levels of cyclin E and p27(Kip1) were assessed by immunohistochemistry. Breast cancer-specific survival (BCSS) was the main outcome measured. RESULTS: The median follow-up was 8 years. Thirty tumors carried germline BRCA1 mutations. These tumors were more likely to have high cyclin E protein levels [odds ratio (OR) 9.5; P <0.001] and low p27(Kip1) protein levels (OR 2.8; P=0.03) than tumors from patients without BRCA1/2 mutations. High cyclin E expression level was the strongest predictor of BRCA1 germline mutations (multivariate OR 4.7; P=0.004). On univariate analysis, high cyclin E protein levels [relative risk (RR) 2.6; P <0.001] and low p27(Kip1) protein levels (RR 2.3; P=0.006) were significant prognostic factors for a poorer BCSS. In Cox multivariate models, high cyclin E levels remained an independent indicator of poor outcome only in the subgroup of patients who did not receive chemotherapy (P=0.002). CONCLUSIONS: In this ethnically restricted cohort, a high level of cyclin E is a characteristic of BRCA1-related breast cancer, and is a marker of poor prognosis following breast cancer, particularly in the absence of adjuvant chemotherapy.     

pT1-2N0期乳腺癌保乳术加放疗疗效优于改良根治术：倾向性评分分析研究

目的 研究pT1-2N0乳腺癌保乳术+放疗和改良根治术的疗效差异。方法 回顾分析1999-2014年治疗的6137例pT1-2N0期的乳腺癌患者资料,其中1296例患者接受保乳术+放疗(保乳术组),4841例患者接受改良根治术但未做放疗(改良根治组)。采用Kaplan-Meier法生存分析,Logrank检验和单因素分析,采用Cox模型多因素分析,最后采用倾向性评分比较进一步确认。     

Decreasing of p27(Kip1)and cyclin E protein levels is associated with progression from superficial into invasive bladder cancer

The p27(Kip1)(p27) protein is a cyclin-dependent kinase inhibitor of the transition from G1 to S phase. It has been reported that decreased p27 protein level is a negative prognostic indicator in human tumours including bladder cancer. We studied the relationship between protein levels of p27, cyclin E and Ki-67 and clinicopathological features of 145 consecutive Japanese patients with transitional cell carcinoma of the bladder using immunohistochemical staining. Low protein levels of p27 were associated with low staining of cyclin E (P = 0.0302), high Ki-67 index (P = 0.0306), poorly differentiated grade (P = 0.0006), muscle invasion (P = 0.0019) and lymph node metastsis (P = 0.0002). Low staining of cyclin E and high Ki-67 index correlated with poorly differentiated grade, muscle invasion and lymph node metastsis. Cyclin E protein levels was inversely related with Ki-67 index (P = 0.0002). Kaplan-Meier plots of survival rate in patients with low versus high p27 staining showed that low protein levels of p27 were associated with a shortened disease-free and overall survival (P< 0.0001 and P< 0.0001, respectively). Similarly, low staining of cyclin E and high Ki-67 index correlated with a shortened disease-free and overall survival. On multivariate analysis using Cox proportional hazards model, low protein levels of p27 and high Ki-67 index were independent predictors of shortened disease-free (P< 0.0001, P = 0.0031, respectively), and low protein levels of p27, low staining of cyclin E and high Ki-67 index of overall survival (P = 0.0017, P = 0.0009, P = 0.0003, respectively). In superficial bladder tumours (Ta, T1; 86 patients), significant correlations were observed between low p27 staining and high Ki-67 index and early recurrence (P = 0.0048, P = 0.0178, respectively). Among the recurrenced superficial tumours (35 patients), the tumours which remained at a low stage showed high protein levels of p27 and cyclin E, and the tumours which progressed to invasive disease showed a gradual decrease in p27 and cyclin E protein levels over time. Our findings suggest that decreased protein levels of p27 and cyclin E play a role in the progression of bladder cancer and to evaluate these protein levels may be useful in management of the diseases.     

Immunoreactivity for p27(KIP1) and cyclin E is an independent predictor of survival in primary gastric non-Hodgkin's lymphoma.

Our aim was to assess the prognostic implications of the expression of p27(KIP1) and cyclin E in gastric lymphoma. We investigated the prognostic value of the immunoreactivity of these molecules in 92 cases of primary gastric lymphoma: 34 LGMLs, 24 DLCLMLs and 34 DLCLs. p27 was positive in 88% of LGMLs, 71% of DLCLMLs and 32% of DLCLs (p = 0.004); cyclin E was positive in 9%, 33% and 59% of cases, respectively (p < 0.00001). p27/cyclin E immunoreactivity significantly correlated with histologic category, stage and LDH serum level. p27 immunoreactivity was significantly associated with better survival, whereas cyclin E reactivity was significantly related to worse outcome. Five-year CSS was 94% for patients with p27(+)/cyclin E(-) phenotype (n = 42), 79% for p27(+)/cyclin E(+) (n = 14) or p27(-)/cyclin E(-) (n = 16) phenotype and 60% for p27(-)/cyclin E(+) phenotype (n = 16) (p = 0.02). The prognostic role of p27/cyclin E expression was confirmed when analyzed separately within LGMLs and large-cell lymphomas. Immunoreactivity for p27 and cyclin E is an independent predictor of survival in PGLs that may be an adjunctive tool in identifying high-risk patients. It correlates with histologic category, stage and LDH serum level. p27(-)/cyclin E(+) phenotype is associated with worse survival, probably due to a synergistic effect of both cell-cycle defects. The predictive role of these molecules within each histologic group of PGLs deserves to be confirmed in larger series.     

Reactive oxygen species-mediated cyclin D1 degradation mediates tumor growth retardation in hypoxia, independently of p21cip1 and hypoxia-inducible factor

Cell growth arrest is an adaptation process for tumor survival in hypoxic environments. As proliferation is a very complicated and dynamic process, hypoxic growth arrest is not considered to be simply determined by a few molecules. Recently, several research groups have demonstrated that hypoxia-inducible factor (HIF)-1α plays a crucial role in hypoxia-induced cell-cycle arrest by inhibiting c-Myc and subsequently inducing p21^cip1 expression. However, we found that hypoxic growth arrest could occur even in p21-null cancer cells, and addressed the p21-independent process of cell-cycle arrest. We show that cyclin D1 was downregulated in various cancer cell lines under hypoxic conditions, which was independent of p21 and HIF-1 and -2α expression. It was also found that cyclin D1 was destabilized by the ubiquitin–proteasome system and this degradation process was highly activated by hypoxia. Moreover, antioxidants prevented the hypoxic degradation of cyclin D1 and hydrogen peroxide destabilized cyclin D1 in normoxia. Finally, we demonstrated that ectopic expression of cyclin D1 rescued hypoxic growth arrest in both p21^+/+ and p21^−/– HCT116 cells. Given the results, we here propose that reactive oxygen species-mediated cyclin D1 degradation contributes to tumor growth retardation in hypoxic environments. ( Cancer Sci 2008; 99: 1798–1805)