Prognostic role of p27Kip1 deregulation in colorectal cancer

p27Kip1, an inhibitor of cyclin-dependent kinases, is a negative cell cycle regulator that plays an important role in tumor suppression. Deregulation of p27 is commonly observed in many human cancers secondary to enhanced ubiquitin-mediated degradation, mediated and rate-limited by its specific ubiquitin ligase subunits Skp2 and Cks1. In the present study the prognostic implications of p27 and the mechanisms that down-regulate its expression in colorectal cancer (CRC) are reviewed. A review and analysis of the English literature was conducted. Loss of p27 was strongly associated with aggressive tumor behavior and poor clinical outcome in CRC. Overexpression of Skp2 and Cks1 was observed in aggressive CRC and is responsible for down-regulation of p27 levels. Both Skp2 and Cks1 were found to be independent prognostic markers for survival and provide predictive information additional to that provided by p27 alone. Deregulation of p27 has a profound effect on tumor progression in CRC and was found to be an accurate and independent prognostic marker. Thus, determination of levels of p27 and of its ubiquitin ligase subunits by readily available immunohistochemical studies may be a useful tool in the assessment of prognosis, especially in patients with intermediate disease, and may potentially assist in the planning of adjuvant therapy and development of novel interventional therapy.     

Prognostic significance of localized p27Kip1 and potential role of Jab1/CSN5 in pancreatic cancer

p27Kip1 belongs to the family of small polypeptides collectively termed cyclin-dependent kinase inhibitors, which negatively regulate the cell cycle progression. In various human cancers, the reduced p27Kip1 expression correlates well with poor prognosis. Recently, Jab1/CSN5, the fifth component of the COP9 signalosome complex, was found to specifically translocate p27Kip1 from the nucleus to the cytoplasm, and reduce the protein level of p27Kip1 by accelerating its degradation. In this study, we investigated the expression of p27Kip1 and Jab1 in 61 cases with pancreatic ductal adenocarcinoma. The p27Kip1 expression was positive in 41% (25/61) of the tumors. Of the 25 positive tumors, 12 cases had p27Kip1 positive expression mainly in the nucleus of the tumor cells, while 13 cases had p27Kip1 in the cytoplasm as well as in the nucleus. Among a variety of clinicopathological factors, only tumor status was inversely correlated with p27Kip1 expression (p=0.019). The Jab1 expression was detected both in the nucleus and the cytoplasm in almost all pancreatic cancer cells. The intensity of Jab1 expression in tumor cells, especially in the cytoplasm, was much stronger than in normal pancreatic ductal epithelial cells. The patients with positive p27Kip1 expression had significantly better prognosis than ones with negative p27Kip1 expression (p=0.008). Furthermore, 12 patients with exclusively nuclear p27Kip1 expression, but not 13 patients with both nuclear and cytoplasmic p27Kip1 expression, had significantly better prognosis than 36 patients with negative p27Kip1 expression (p=0.009). In multivariate survival analysis, localized p27Kip1 expression was an independent prognostic factor (p=0.016). The results of our study suggested that the mislocalization as well as the downregulation of p27Kip1 had significant prognostic value in pancreatic cancer and that Jab1 might play an important role in carcinogenesis of pancreatic cancer. Cell cycle control targeting p27Kip1 might be a promising future therapeutic modality against pancreatic cancer.     

Prognostic value of p27(Kip1) and CyclinD1 expression in esophageal cancer

It has recently been reported that the reduced expression of p27(Kip1) is a negative prognostic marker in several carcinomas. In this study, we examined the expression of p27(Kip1) in esophageal squamous cell carcinomas in order to understand its prognostic role. We also examined the expression of cyclinD1, which is believed to be correlated with the prognosis. Of the 128 cases, 64 cases (50.0%) showed low grade p27(Kip1) immunostaining and 64 cases (50.0%) high grade immunostaining; there was no significant difference in survival (p = 0.0915) between the two groups. On the other hand, 51 of the 156 cases (32.7%) were classified as the high cyclinD1 group, and 105 of the 156 cases (67.3%) as the low group, thus representing prognostic significance with regard to survival (p = 0.0161). Multivariate analysis indicated that gender, lymph node metastasis and positive cyclinD1 were independent prognostic factors. Our results revealed that cyclinD1 was a significant prognostic predictor of esophageal squamous cell carcinomas, whereas p27(Kip1) was not a significant prognostic factor. Copyright Copyright 1999 S. Karger AG, Basel     

Prognostic impact of Skp2 and p27 in human breast cancer

SummaryPurpose The cell cycle is controlled by cyclin-dependent kinases and one of the key players is the cyclin-dependent kinase inhibitor p27. The F-box protein Skp2 is a regulator of G1-S transition and promotes specifically the ubiquitin-mediated proteolysis of p27 via the proteasome pathway. In breast carcinomas, overexpression of Skp2 has been implicated in cell transformation and oncogenesis, but no data are available on the association of Skp2 and p27. The purpose was to evaluate the prevalence of Skp2 and p27 expression and determine whether a combined index has prognostic power in breast carcinomas.Experimental design Three hundred and thirty-eight breast cancer specimens were analyzed for Skp2 and p27 expression by immunohistochemistry. Results were compared with classical histopathological criteria as well as other prognostic markers (ER, PR, HER2, p53, Ki-67) and correlated with the clinical outcome.Results Thirty-four percent of breast cancers analyzed showed both a high expression for Skp2 and a low expression for p27. In univariate Kaplan–Meier analysis, this combination was found to be significantly associated with a worse clinical course (p<0.0001). Including staging, grading and the other tested marker, the Skp2/p27 index proved to be of prognostic relevance in multivariate analysis.Conclusions The combined assessment of Skp2 and p27 identifies aggressive breast cancer. In long-term follow-up, high Skp2 and low p27 indicate an unfavorable course. Beyond the prognostic importance of the Skp2/p27 index, it could serve as a predictive marker for new molecular targeted therapies aiming at Skp2.     

Involvement of retinoblastoma protein in p27Kip1-induced apoptosis

p27Kip1, a cyclin-dependent kinase (CDK) inhibitor, plays a critical role in cell cycle regulation. Expression of p27Kip1 is shown to increase during apoptosis in mammalian cells. Here, to directly address the role of p27Kip1 in apoptosis, p27Kip1 is overexpressed in human SK-Hep1 hepatoma cells. This leads to apoptotic cell death and this reduces protein, but not mRNA, levels of the retinoblastoma (Rb). Consistently, accumulation of Rb protein blocks p27Kip1-mediated apoptosis. These studies demonstrate an involvement of Rb in the apoptotic cell death which is induced by overexpression of p27Kip1.     

Prognostic role of p27(Kip1) expression in oral squamous cell carcinoma in Taiwan

The cyclin-dependent kinase inhibitor p27(Kip1) can inhibit the G1 to S transition of the cell cycle and is a putative tumor suppressor. Decreased expression of p27(Kip1) protein has been correlated with poor prognosis in a variety of human tumors. We examined the expression of p27(Kip1) in oral squamous cell carcinoma (SCC), epithelial dysplasia (ED) and normal oral mucosa (NOM) using antibodies to p27(Kip1). Positive p27(Kip1) nuclear staining was detected in all the specimems from ED and NOM, whereas positive p27(Kip1) staining was observed in 16 of the 63 (25%) cases of oral SCC. The labeling index for p27(Kip1) protein was significantly reduced from NOM through ED to oral SCCs, indicating that changes of p27(Kip1) protein expression may be an early event in oral carcinogenesis in Taiwan. The Kaplan-Meier analysis showed patients with p27(Kip1)-positive tumors had significantly higher overall survival than those with p27(Kip1)-negative tumors in a total of 63 patients (P=0.015) and 47 patients with areca quid chewing habit (P=0.026). Multivariate analysis showed decreased p27(Kip1) protein expression was an independent significant predictor of poor overall survival in the patients with oral SCCs. These results indicate that p27(Kip1) protein expression may serve as a putative new adjuvant prognostic marker for routine assessment of oral SCC patients.     

Differential modulation of paclitaxel-mediated apoptosis by p21Waf1 and p27Kip1

The impact of the cyclin dependent kinase (CDK) inhibitors p21Waf1 and p27Kip1 on paclitaxel-mediated cytotoxicity was investigated in RKO human colon adenocarcinoma cells with the ecdysone-inducible expression of p21Waf1 or p27Kip1. Ectopic expression of p27Kip1 arrested cells at G1 phase, whereas p21Waf1 expression arrested cells at G1 and G2. Expression of p21Waf1 after paclitaxel treatment produced much greater resistance to paclitaxel than did expression of p27Kip1. We attributed this difference to the additional block at G2 induced by p21Waf1, which prevented cells from entering M phase and becoming paclitaxel susceptible. Expression of p21Waf1 inhibited p34cdc2 activity and markedly reduced paclitaxel-mediated mitotic arrest, from 87.5 to 23%. In contrast, p27Kip1 expression also inhibited p34cdc2 but reduced mitotic arrest only slightly, from 87. 4 to 74.5%. We concluded that the G2 block produced by p21Waf1, but not by p27Kip1, contributed to their unequal modulation of sensitivity to paclitaxel-mediated apoptosis in RKO cells, and there is no causal relationship between paclitaxel-mediated cytotoxicity and elevation of p34cdc2 activity.     

IFNalpha 2b induces apoptosis and proteasome-mediated degradation of p27Kip1 in a human lung cancer cell line

IFNs are a family of cytokines involved in antiviral defense, cell growth regulation and immune activation. IFNs either inhibit cell proliferation or control apoptosis depending on factors such as cell type and state of cell differentiation. It is important to determine how IFN-induced gene products interact with other cellular proteins to produce these responses. We have investigated the effect of IFNalpha 2b on a human small cell lung carcinoma (SCLC) cell line H82. We have found that IFNalpha efficiently induces apoptosis in H82 cells. The induction of apoptosis by IFNalpha 2b is accompanied by decreased levels of c-myc and Cdk2. We have also observed that in H82 cells IFNalpha induces downregulation of p27 and this is in contrast to the upregulation of p27 observed in other cell types where IFNs induce cell cycle arrest. IFNalpha-induced downregulation of p27 is due to protein destabilization and can be prevented by the proteasome inhibitor LLnL. The data suggest that in H82 cells, IFNalpha 2b induces degradation of p27Kip1 independently of CDK2 kinase activity and through a ubiquitin or ubiquitin-related pathway and that the degradation of p27Kip1 could be a molecular event of importance for IFN-induced apoptosis in cancer cells.     

乳腺癌表达细胞周期蛋白依赖性激酶抑制物p27kip1的预后意义

研究ｐ２７＾ｋｉｐｌ在乳腺癌组织中的表达水平,及其与生物学行为的关系和对预后的作用。方法以免疫组化法检测１８１例乳腺癌组织ｐ２７＾ｋｉｐｌ蛋白表达水平,其中９１例进行了凋亡指数、凋亡相关蛋白ｂｃｌ－２、ｂａｘ的测定,另有１０６例检测了ｐ２１＾ＷＡＦ１／ＣＩＰＩ、ｐ５３、ｍｄｍ２蛋白表达水平。结果本组１８１例中,ｐ２７＾ｋｉｐｌ蛋白阳性１２５例,占６９．１％;低表达者１２１例,占６６．９％;高表达者     

Prognostic value of p27Kip1 and p21WAF/Cip protein expression in muscle invasive bladder cancer

Two genes, namely p27Kip1 and p21WAF/Cip1 that reveal distinct structural homology, have been identified as inductors of cell cycle arrest at the G1-checkpoint to prevent entry of somatic cells into the S phase of the cell cycle when substantial DNA damage has occurred. It was demonstrated that the p21WAF/Cip1 gene is induced by pathways dependent and independent from a functionally intact p53 tumour suppressor protein. It has been suggested that decreased expression both of the p21WAF/Cip1 and p27Kip1 protein may contribute to the development of human malignancies due to loss of critical antiproliferative mechanisms. So far, the role of altered p21WAF/Cip1 and mainly of a decreased p27Kip1 protein expression in patients with muscle invasive bladder cancer has not been investigated. In the present study, 50 tumour specimens from 50 patients undergoing radical cystectomy (T2-T4) were investigated for different biological and clinical characteristics as possible prognostic factors: age, depth of tumour infiltration (T-stage), histological grading (G), lymph node status as well as immunohistochemical staining for the p21WAF/Cip1 and p27Kip1 proteins. The median recurrence-free survival for patients with and without retained p21WAF/Cip1 protein expression was 54 months (3-86 months) and 13 months (1-40 months), respectively (p=0.07). During univariate analysis, loss of p21WAF/Cip1 protein expression (p=0.02), T-stage (p=0.02) and histological grading (p=0.03) were significant prognostic factors for survival, among which a negative reaction for the p21WAF/Cip1 protein (p=0.02) as well as T-stage (p=0.005) remained independent significant predictors during multivariate analysis. Loss of p27Kip1 protein expression was not correlated with the recurrence-free or the overall survival of the patients. Prospective studies are needed to confirm the independent prognostic potential of cell-cycle associated proteins such as p21WAF/Cip1 in patients with muscle invasive bladder cancer. The availability of more refined prognostic factors should assist decision making regarding the value of more aggressive treatment options, such as adjuvant or neoadjuvant chemotherapy, for defined subgroups of patients.     

p27(Kip1) induces quiescence and growth factor insensitivity in tamoxifen-treated breast cancer cells

Tamoxifen, a selective estrogen-receptor modulator, is effective in the treatment and prevention of breast cancer, but therapeutic resistance is common. Pure steroidal antiestrogens are efficacious in tamoxifen-resistant disease and, unlike tamoxifen, arrest cells in a state of quiescence from which they cannot reenter the cell cycle after growth factor stimulation. We now show that in hydroxytamoxifen-treated cells, transduction of the cell cycle inhibitor p27(Kip1) induces quiescence and insensitivity to growth stimulation by insulin/insulin-like growth factor I and epidermal growth factor/transforming growth factor alpha. Furthermore, reinitiation of cell cycle progression by insulin/insulin-like growth factor I in hydroxytamoxifen-arrested cells involves dissociation of the corepressors nuclear receptor corepressor (N-CoR) and silencing mediator for retinoid and thyroid hormone receptor (SMRT) from nuclear estrogen receptor alpha and redistribution to the cytoplasm, a process that is inhibited by mitogen-activated protein/extracellular signal-regulated kinase, but not phosphatidylinositol 3'-kinase, inhibitors. These data suggest that agents that up-regulate p27(Kip1) or inhibit growth factor signaling via the extracellular signal-regulated kinases should be tested as therapeutic strategies in tamoxifen-resistant breast cancer.     

Prognostic impact of cyclin-dependent kinase inhibitor p27kip1 in node-positive breast cancer

BACKGROUND AND OBJECTIVES: p27kip1 (p27) plays an important role as a negative regulator of cell cycle-dependent kinase activity during progression of the cell cycle. The most important prognosticator of breast cancer is nodal status, and the aim of this study was to determine the prognostic implication of p27 in breast cancer patients with lymph node metastases. METHODS: Immunohistochemical staining for p27 was performed on tissues from 102 patients with node-positive breast cancer. RESULTS: A nuclear staining over 50% was defined as high expression. High expression of p27 was shown in 59 patients (57.8%). A significant correlation was found between high p27 and positive estrogen receptor status, but there was no correlation between p27 staining and age, menopausal status, nodal status, or tumor size. Low expression of p27 was significantly associated with shorter survival. A multivariate analysis also showed that the only independent variable was p27. CONCLUSIONS: The results indicated that low expression of p27 was an independent factor associated with poor prognosis. Therefore, p27 can be an important tool in making therapeutic decisions.     

丁酸钠对人乳腺癌细胞株MCF-7细胞增殖及p27Kip1蛋白表达影响的研究

目的:通过观察组蛋白去乙酰化酶抑制剂(histon-deacetylase inhibitors,HDACIs)丁酸钠(sodium butyrate,NaB)对人乳腺癌细胞株MCF-7细胞的增殖影响以及p27Kip1蛋白表达改变,探讨NaB调控乳腺癌细胞增殖的分子机制.方法:乳腺癌MCF-7细胞经不同浓度NaB作用后,相差显微镜观察细胞形态变化和细胞增殖情况,流式细胞仪分析细胞周期分布,免疫组化检测p27Kip1蛋白表达.结果:NaB对MCF-7细胞有显著的增殖抑制作用,呈时间剂量依赖性,处理后的MCF-7细胞出现凋亡形态变化;细胞周期阻滞于G0/G1期,NaB 2 mmol/L组G0/G1期达(62.2±2.2)%,4 mmol/L组G0/G1期达(78.1±3.8)%,空白组G0/G1期达(53.1±2.4)%,P<0.05;p27蛋白表达水平上调.结论:NaB可抑制乳腺癌细胞的生长,该作用可能与p27蛋白表达增加有关.     

Prognostic implications of expression of the cell cycle inhibitor protein p27Kip1

Mitogenic and growth inhibitory signals influence the activity of a family of cyclin dependent kinases (cdks). p27 is an important cdk inhibitor, acting in G1 to inhibit cyclin-cdks. As negative growth regulators, the cdk inhibitors may function as tumor suppressors. While the p16 gene plays a tumor suppressor role in cancers, p27 gene mutations have been identified only rarely. While high levels of p27 protein are expressed in normal human mammary epithelium, loss of p27 is frequent and is of independent prognostic significance in breast cancers. Low p27 is also a poor prognostic factor in colon, gastric, esophageal, lung, and prostate carcinomas, and enhanced proteasomal degradation may underlie loss of p27 in tumor cells. Loss of p27 has not been significantly correlated with tumor proliferation in a number of studies and may reflect alterations in differentiation and adhesion-dependent growth regulation germane to oncogenesis and tumor progression. Efforts to confirm the prognostic value of p27 are under way in a number of large breast cancer studies. These studies may also indicate whether loss of p27 in association with other traditional or novel markers has greater prognostic potential than each factor alone. p27 immunostaining is inexpensive and reliable and may become part of the routine histopathologic processing of tumors in the near future. Widespread application of p27 in prognostic testing will require greater uniformity in scoring techniques and determination of the cut off levels which distinguish individuals at high and low risk of cancer recurrence and death. Finally, the greatest utility of p27 may lie in the information it sheds on the biology of aberrant growth regulation in breast cancer and the potential to use this in the generation of novel therapeutic strategies.     

Polyamine-depletion induces p27Kip1 and enhances dexamethasone-induced G1 arrest and apoptosis in human T lymphoblastic leukemia cells

Glucocorticoid-induced apoptosis is preceded by G1 arrest and supposed to be up-regulated by polyamine-depletion, which also induces G1, arrest. In CEM leukemia cells, dexamethasone showed an antileukemic effect by inducing G1 arrest and apoptosis. DFMO, which depleted cellular polyamines by inhibiting ornithine decarboxylase, induced G1 arrest but without apoptosis, though it enhanced dexamethasone-induced G1 arrest and apoptosis. The G1 arrest was associated with hypophosphorylation of pRb. Dexamethasone inhibited the increase of mutated p53 expression but had little effect on p2Wafl/Cip1 expression. The p27Kip1, level was increased by dexamethasone or and DFMO in line with the kinetics of G1 arrest. Therefore, the up-regulation of dexamethasone-induced apoptosis by polyamine-depletion may be associated with additive down-regulation of G1 progression via the p27Kip1-pRb pathtway.     

ERK-1和p27在三阴乳腺癌中的表达及意义

目的：检测三阴乳腺癌（TNBC）组织中ERK-1和p27的表达并探讨其意义.方法：采用免疫组织化学SP法检测56例TNBC组织和30例癌旁正常乳腺组织ERK-1和p27的表达情况.结果：TNBC组织中ERK-1和p27表达定位于细胞核,其表达率分别为55.36％ （31/56）和30.36％ （17/56）,分别高于和低于癌旁正常组织（P ＜0.05）;56例TNBC组织中,ERK-1和p27蛋白在组织学分级G3级表达率高于G1＋G2级（P＜0.05）,ERK-1的病理分期Ⅲ期的表达率高于Ⅰ-Ⅱ期（P＜0.05）,ERK-1的表达与淋巴结转移、病理组织类型无关（P＞0.05）,而p27与淋巴结转移有关（P＜0.05）.相关性分析显示,二者之间呈负相关（P＜0.05）.结论：ERK-1和p27在TNBC中分别呈高表达和低表达,提示ERK-1、p27与TNBC的发生、发展和转移密切相关.     

Overexpression of p27(Kip1) induces growth arrest and apoptosis in an oral cancer cell line

p27(Kip1) is a cyclin-dependent kinase inhibitor which regulates progression of cells from G1 into S phase in a cell cycle. Loss of p27(Kip1) has been associated with disease progression and an unfavorable outcome in several malignancies. In the present study, we conducted to examine whether up-regulation or down-regulation of p27(KiP1) can affect the growth of oral cancer cell (B88 cell) in vitro and in vivo. We constructed an expression vector containing sense- or antisense-oriented human p27(Kip1) cDNA with pcDNA3.1(Invitrogen). We transfected B88 cells with the sense or antisense expression vector to regulate the expression of p27(Kip1) gene in each transfectant. The expression of p27(Kip1) protein was up-regulated in the sense transfectants and down-regulated in the antisense transfectants. Moreover, up-regulation of p27(Kip1) protein exerted the growth inhibitory effect, and down-regulation of p27(Kip1) protein enhanced the growth of B88 cells in vitro and in vivo. Furthermore, we detected the G1 arrest and sub-G1 peak in the sense transfectants by flow cytometry analysis. These results suggest that up-regulation of p27(Kip1) protein may exert the growth inhibitory effects through induction of G1 arrest and apoptosis on oral cancer cell line.     

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.