Prognostic significance of p27(Kip1) expression in colorectal cancer: a clinico-pathological characterization

Amentoflavone induces caspase-dependent/-independent apoptosis and dysregulates cyclin-dependent kinase-mediated cell cycle in colorectal cancer in vitro and in vivo

Colorectal cancer (CRC) is recognized as the third most common malignancy and the second most deadly in highly developed countries. Although the treatment of CRC has improved in the past decade, the mortality rate of CRC is still increasing. Amentoflavone, one of the flavonoids detected in medical plants, is reported to possess potential anticancer properties in various cancers. However, its role in CRC has not been studied. This study aimed to investigate the role and underlying mechanism of amentoflavone on CRC in vitro and in vivo. We identified the cytotoxicity, apoptosis effect, cell cycle alteration, DNA damage induction and tumor progression inhibition of amentoflavone in HT-29 model by using MTT assay, flow cytometry, immunofluorescence (IF) staining, Western blotting and animal experiments. Amentoflavone induced cytotoxicity is caused by triggering G1 arrest, DNA damage and apoptosis in HT-29 cells. The expression of cyclin D1, CDK4 and CDK6 was decreased by amentoflavone; in contrast, the phosphorylation of ATM and CHK2 and the expression of p21 and p27 were increased. The apoptosis induction of amentoflavone in CRC is not only caspase-dependent but also increases EndoG and AIF nuclear translocation in a caspase-independent manner. Importantly, the apoptosis induction of amentoflavone is not affected by the activity of p53 in CRC. Amentoflavone suppressed the progression of CRC by initiating G1 arrest and ATM/CHK2-mediated DNA damage-responsive, caspase-dependent/independent apoptotic effects. We uncovered a novel tumor-inhibitory role of amentoflavone in CRC that is not associated with p53 activity, which may serve as a potential treatment for CRC.

Loss of p27Kip1 leads to expansion of CD4+ effector memory T cells and accelerates colitis-associated colon cancer in mice with a T cell lineage restricted deletion of Smad4

The cyclin-dependent kinase inhibitor p27^Kip1 is a tumor suppressor whose intrinsic activity in cancer cells correlates with tumor aggressiveness, invasiveness, and impaired tumor cell differentiation. Here we explore whether p27^Kip1 indirectly influences tumor progression by restricting expansion and survival of effector memory T cell (T_EM) populations in a preclinical model of spontaneous colitis-associated colorectal cancer (CAC). We show mRNA and protein expression of p27^Kip1 to be significantly decreased in the colons of mice with a T cell-restricted deletion of the TGF-β intermediate, SMAD4 (Smad4^TKO). Loss of p27^Kip1 expression in T cells correlates with the onset of spontaneous CAC in Smad4^TKO mice by 8 months of age. This phenotype is greatly accelerated by the introduction of a germline deletion of CDKN1b (the gene encoding p27^Kip1) in Smad4^TKO mice (Smad4^TKO/p27^Kip1-/-, DKO). DKO mice display colon carcinoma by 3 months of age and increased mortality compared to Smad4^TKO. Importantly, the phenotype in DKO mice is associated with a significant increase in the frequency of effector CD4 T cells expressing abundant IFN-γ and with a concomitant decrease in Foxp3⁺ regulatory T cells, both in the intestinal mucosa and in the periphery. In addition, induction of inflammatory mediators (IFN-γ, TNF-γ, IL-6, IL-1β, iNOS) and activation of Stat1, Stat3, and IκB is also observed in the colon as early as 1–2 months of age. Our data suggest that genomic alterations known to influence p27^Kip1 abundance in gastrointestinal cancers may indirectly promote epithelial malignancy by augmenting the production of inflammatory mediators from a spontaneously expanding pool of T_EM cells.

c-MYC Expression Is a Possible Keystone in the Colorectal Cancer Resistance to EGFR Inhibitors

Alterations in the transcriptional factor c-MYC could be involved in the anti-EGFR resistance in metastatic colorectal cancer (mCRC). The c-MYC expression was evaluated in 121 RAS and BRAF wild-type mCRC before treatment with anti-EGFR+Folfiri therapy and in 33 subsequent metastases collected during target therapy (TT) or in TT resistance phase. We analyzed the expression and the functional role of some c-MYC linked miRNAs (miR-31-3p, miR-143 and miR-145) in our patient group and in two CRC cell lines, also performing a c-MYC target PCR array. Patients with higher c-MYC expression (HME) showed a significant lower PFS and OS when compared to those with low c-MYC expression (LME). HME pattern was significantly more frequent in the metastases after TT and significantly associated to anti-EGFR molecular resistance alterations. We also found a significant correlation between the expression of the above-mentioned c-MYC linked miRNAs, c-MYC level and anti-EGFR resistance. Moreover, expression gene profiling pointed out the pivotal role of c-MYC in CRC-related cell-cycle, apoptosis, signal transduction and cell-growth pathways. c-MYC expression might distinguish patients with a lower PFS and OS in anti-EGFR treated mCRC. The individuation of some miRNAs involved in the c-MYC pathway regulation and the downstream c-MYC effector genes could provide a new possible target to overcome the anti-EGFR resistance in mCRC.

Delineating Crosstalk Mechanisms of the Ubiquitin Proteasome System That Regulate Apoptosis

Regulatory functions of the ubiquitin-proteasome system (UPS) are exercised mainly by the ubiquitin ligases and deubiquitinating enzymes. Degradation of apoptotic proteins by UPS is central to the maintenance of cell health, and deregulation of this process is associated with several diseases including tumors, neurodegenerative disorders, diabetes, and inflammation. Therefore, it is the view that interrogating protein turnover in cells can offer a strategy for delineating disease-causing mechanistic perturbations and facilitate identification of drug targets. In this review, we are summarizing an overview to elucidate the updated knowledge on the molecular interplay between the apoptosis and UPS pathways. We have condensed around 100 enzymes of UPS machinery from the literature that ubiquitinates or deubiquitinates the apoptotic proteins and regulates the cell fate. We have also provided a detailed insight into how the UPS proteins are able to fine-tune the intrinsic, extrinsic, and p53-mediated apoptotic pathways to regulate cell survival or cell death. This review provides a comprehensive overview of the potential of UPS players as a drug target for cancer and other human disorders.

Clinical significances of p27 in digestive tract cancers: a comprehensive analysis on immunohistochemistry staining, published literatures, microarray and RNA-seq data

In the present study, we conducted a comprehensive analysis on the clinical roles of p27 protein and p27 gene in digestive tract cancers (DTCs). First, we performed immunohistochemistry staining and found that p27 protein was down-regulated in DTCs. Then we collected 62 publications and calculated the combined hazard ratios (HRs), odds ratios (ORs) and 95% confidence intervals (95% CIs) to clarify the relationships of p27 protein expression with prognoses and clinicopathological parameters. The overall HRs indicated that the down-regulated p27 protein was an independent prognostic biomarker for overall survival (HR: 1.58, 95% CI: 1.38-1.81, P < 0.0001) but not for disease-free survival and cancer-specific survival. The combined ORs indicated that a low expression of p27 protein was positively related to lymph node metastasis (OR: 2.15, 95% CI: 1.57-2.96, P < 0.0001), distant metastasis (OR: 2.02, 95% CI: 1.12-3.63, P = 0.019) and pathology grading (OR: 2.14, 95% CI: 1.75-2.62, P < 0.0001). Additionally, 60 DTCs-related microarray and RNA-seq datasets were obtained to investigate the expression level and clinical value of p27 gene in DTCs patients. We found that the expression level of p27 gene in DTCs was similar to that in normal controls. And no significant associations of p27 gene expression with prognoses and clinicopathological factors were observed. In conclusion, according to our results, it was p27 protein, but not p27 gene, that can function as an effective biomarker to predict the clinical outcome in patients with DTCs. The down-regulation of p27 protein in DTCs may not result from the altered expression of p27 gene.

Nonmonotonic Pathway Gene Expression Analysis Reveals Oncogenic Role of p27/Kip1 at Intermediate Dose

The mechanistic basis by which the level of p27^Kip1 expression influences tumor aggressiveness and patient mortality remains unclear. To elucidate the competing tumor-suppressing and oncogenic effects of p27^Kip1 on gene expression in tumors, we analyzed the transcriptomes of squamous cell papilloma derived from Cdkn1b nullizygous, heterozygous, and wild-type mice. We developed a novel functional pathway analysis method capable of testing directional and nonmonotonic dose response. This analysis can reveal potential causal relationships that might have been missed by other nondirectional pathway analysis methods. Applying this method to capture dose-response curves in papilloma gene expression data, we show that several known cancer pathways are dominated by low-high-low gene expression responses to increasing p27 gene doses. The oncogene cyclin D1, whose expression is elevated at an intermediate p27 dose, is the most responsive gene shared by these cancer pathways. Therefore, intermediate levels of p27 may promote cellular processes favoring tumorigenesis-strikingly consistent with the dominance of heterozygous mutations in CDKN1B seen in human cancers. Our findings shed new light on regulatory mechanisms for both pro- and anti-tumorigenic roles of p27^Kip1. Functional pathway dose-response analysis provides a unique opportunity to uncover nonmonotonic patterns in biological systems.

FoxM1: Repurposing an oncogene as a biomarker

The past few decades have witnessed a tremendous progress in understanding the biology of cancer, which has led to more comprehensive approaches for global gene expression profiling and genome-wide analysis. This has helped to determine more sophisticated prognostic and predictive signature markers for the prompt diagnosis and precise screening of cancer patients. In the search for novel biomarkers, there has been increased interest in FoxM1, an extensively studied transcription factor that encompasses most of the hallmarks of malignancy. Considering the attractive potential of this multifarious oncogene, FoxM1 has emerged as an important molecule implicated in initiation, development and progression of cancer. Bolstered with the skill to maneuver the proliferation signals, FoxM1 bestows resistance to contemporary anti-cancer therapy as well. This review sheds light on the large body of literature that has accumulated in recent years that implies that FoxM1 neoplastic functions can be used as a novel predictive, prognostic and therapeutic marker for different cancers. This assessment also highlights the key features of FoxM1 that can be effectively harnessed to establish FoxM1 as a strong biomarker in diagnosis and treatment of cancer.

Immunohistochemical Markers as Predictors of Histopathologic Response and Prognosis in Rectal Cancer Treated with Preoperative Adjuvant Therapy: State of the Art

We explain the state of the art of the immunohistochemical markers of response in rectal cancers treated with neoadjuvant medical therapies and its implication with prognosis. Neoadjuvant chemoradiotherapy is widely used to improve the outcome of patients with locally advanced rectal cancer, and the evaluation of the effects of medical therapy is to date based on histomorphological examination by applying four grading systems of response to therapy (tumor regression grade (TRG)). The need to identify immunohistochemical markers that could ensure a better assessment of response and possibly provide additional prognostic information has emerged. We identified p53, p27kip1, Ki67, matrix metalloprotease-9, survivin, Ki67 proliferative index, CD133, COX2, CD44v6, thymidylate synthase, thymidine phosphorylase, and dihydropyrimidine dehydrogenase as the most common markers studied in literature to date, and we explained their prognostic potential and their implications in the evaluation of the response to preoperative therapies in rectal cancers.

Cell Cycle Protein Expression in Neuroendocrine Tumors: Association of CDK4/CDK6, CCND1, and Phosphorylated Retinoblastoma Protein With Proliferative Index

OBJECTIVES

Dysregulation of the cell cycle has been observed and implicated as an etiologic factor in a range of human malignancies, but remains relatively unstudied in neuroendocrine tumors (NETs). We evaluated expression of key proteins involved in cell cycle regulation in a large cohort of NETs.

METHODS

We evaluated immunohistochemical expression of CDKN1B, CDKN1A, CDKN2A, CDK2, CDK4, CDK6, cyclin D1, cyclin E1, and phosphorylated retinoblastoma protein (phospho-RB1) in a cohort of 267 patients with NETs. We then explored associations between cell cycle protein expression, mutational status, histologic features, and overall survival.

RESULTS

We found that high expression of CDK4, CDK6, CCND1, and phospho-RB1 was associated with higher proliferative index, as defined by MKI67. We additionally observed a trend toward shorter overall survival associated with low expression of CDKN1B. This association seemed strongest in SINETs (multivariate hazards ratio, 2.04; 95% confidence interval, 1.06-3.93; P = 0.03). We found no clear association between CDKN1B mutation and protein expression.

CONCLUSIONS

Our results suggest that dysregulation and activation of the CDK4/CDK6-CCND1-phospho-RB1 axis is associated with higher proliferative index in NETs. Investigation of the therapeutic potential of CDK4/CDK6 inhibitors in higher grade NETs is warranted.

MicroRNA-455-3p Inhibits Tumor Cell Proliferation and Induces Apoptosis in HCT116 Human Colon Cancer Cells

BACKGROUND MicroRNAs have been reported to play significant roles in pathogenesis of colorectal cancer (CRC). In the present study, we aimed to investigate the functional role of microRNA-455-3p (miR-455-3p) in CRC, as well as its underlying mechanisms. MATERIAL AND METHODS Human colon cancer cell line HCT116 cells were transfected with miR-455-3p mimics, inhibitors, or controls. After transfection, the effects of miR-455-3p mimics or inhibitors on cell proliferation were analyzed by 3-(4, 5-dimethyl-2- thiazolyl)-2, 5-diphenyl -2-H-tetrazolium bromide (MTT) assay and BrdU assay, and the effects of miR-455-3p mimics or inhibitors on cell apoptosis were determined. In addition, the underlying mechanisms of cell proliferation and apoptosis were explored by assessing the protein levels of cell cycle regulators and apoptosis-related protein. RESULTS The results showed that overexpression of miR-455-3p significantly inhibited the cell proliferation (P<0.05 or <0.01) in HCT116 cells compared with the control group, but significantly increased the apoptosis (P<0.01). On the contrary, suppression of miR-455-3p significantly increased the cell proliferation but decreased the apoptosis. Moreover, we found that overexpression of miR-455-3p significantly elevated the protein levels of p27 kinase inhibition protein (KIP) 1, Bax, pro-caspase-3, and active caspase-3, and markedly downregulated the levels of B-cell lymphoma-2 (Bcl-2). Contrary results were found by suppression of miR-455-3p. However, there were no significant differences in p21 expression. CONCLUSIONS MiRNA-455-3p functions as an anti-oncogene in HCT116 cells by inhibiting cell proliferation and inducing of apoptosis.

Pterostilbine, an active component of blueberries, sensitizes colon cancer cells to 5-fluorouracil cytotoxicity

Although colorectal cancer (CRC) treatment with 5-fluorouracil (5-FU) is the first line of therapy for this debilitating disease, treatment effectiveness is often hampered by the development of drug resistance and toxicity at high doses. ER-β can play an important role in CRC development and possibly in its response to therapy. Pterostilbene (PT) possesses antioxidant and anticancer effects that are mediated by ER-β. In the current study, we test the hypothesis that PT sensitizes colon cancer cells to 5-FU and we examine the underlying mechanism(s) by which PT exerts its cytotoxic effects in CRC cells. Our data indicate that PT exhibited a more potent cytotoxic effect in Caco-2 compared to HCT-116 cells. PT/5-FU co-treatment was more effective in Caco-2 cells. Our data indicate that ER-β is expressed at higher levels in Caco-2 cells and its levels are further boosted with PT treatment. PT significantly suppressed Akt and ERK phosphorylations, and enhanced FOXO-1 and p27^kip1 levels in Caco-2 cells. PT also induced a significant increase in Caco-2 cells at pre-G phase coupled with increased Bax/Bcl-2 ratio and PARP cleavage. These results provide a rationale for novel combination treatment strategies, especially for patients with 5-FU-resistant tumors expressing ER-β protein.

Micropapillary pattern at the invasive front and its association with unresectable colorectal carcinomas

Unresectable colorectal carcinomas (CRCs) as considered incurable even if the primary tumors and the metastatic ones can undergo resection are correlated with poor prognosis. We evaluated the association between micropapillary pattern at the invasive front and unresectable CRCs. Thirty-four out of 264 (12.9%) CRC patients with stages III and IV were unresectable cases. The patients with unresectable CRCs had significantly worse survival than those with resectable CRCs (P < 0.001). Micropapillary pattern was evident in 12 (4.5%) out of 264 cases. This pattern was observed in 6 of 34 (17.6%) unresectable CRCs and in 6 of 230 (2.6%) resectable cases (P = 0.002). Unresectable CRCs revealed more frequently deeper invasion (odds ratio (OR), 1.175; 95% confidence interval (CI), 1.113-1.241), lymph node metastasis (OR, 2.356; 95% CI, 1.132-4.905), and presence of micropapillary pattern at the invasive front (OR, 8.000; 95% CI, 2.415-26.504) as compared to resectable cases. By multivariable logistic regression analysis, only micropapillary pattern was shown to be an independent predictor of unresectable CRCs (OR, 9.451; 95% CI, 2.468-36.196; P < 0.001). In conclusion, micropapillary pattern at the invasive front is associated with unresectable CRCs, and detection of it could help identify unresectable CRC cases.

Prognostic factors and biomarkers of penile carcinoma

Penile squamous cell carcinoma (SCC) is a rare malignancy with highest incidence in underdeveloped and developing countries. Oncogenic human papilloma virus (HPV) DNA, mainly types 16 and 18, are found in ∼ 100% of patients with uterine cervix carcinoma. The incidence of this virus in SCC and its variations range from 30.5 to 80%. Despite controversies, contrary to the cervical carcinoma, in the carcinogenesis and disease progression of SCC, HPV-dependent and HPV-independent tumors need to be considered. Lymphadenectomies continue to be the gold standard treatment of lymph node metastases. Undesirable accuracy on staging system methods and high rates of lymphadenectomy complications are the principal objections to these surgical procedures; therefore, the main issue in patients with SCC is to know who should or should not undergo lymphadenectomy. The search for primary tumor anatomopathological and biomarker risk factors for lymph node metastases, such as has occurred in other tumors, may be an important tool to select lymphadenectomies candidates better. Histological subtypes, tumor grade, growth pattern, tumor thickness, lymphatic embolization by neoplasic cells and depth of infiltration have been reported as important prognostic factors for lymph node metastases. In our series, lymphatic vascular permeation, palpable lymph node after primary tumor control (cN stage), pattern of invasion, p53 and PCNA immunoreactivity are independent lymph node metastases risk factors in the multivariate model. It is strongly recommended that patients be concentrated in specialized centers or cancer hospitals and multi-centric prospective studies carried out on tumor markers in this rare disease, in order to stage better lymph node disease and avoid unnecessary surgeries with high morbidity rates.

Role of ubiquitin ligases and the proteasome in oncogenesis: novel targets for anticancer therapies

The ubiquitin proteasome system (UPS) regulates the ubiquitination, and thus degradation and turnover, of many proteins vital to cellular regulation and function. The UPS comprises a sequential series of enzymatic processes using four key enzyme families: E1 (ubiquitin-activating enzymes), E2 (ubiquitin-carrier proteins), E3 (ubiquitin-protein ligases), and E4 (ubiquitin chain assembly factors). Because the UPS is a crucial regulator of the cell cycle, and abnormal cell-cycle control can lead to oncogenesis, aberrancies within the UPS pathway can result in a malignant cellular phenotype and thus has become an attractive target for novel anticancer agents. This article will provide an overall review of the mechanics of the UPS, describe aberrancies leading to cancer, and give an overview of current drug therapies selectively targeting the UPS.

Expression of p27, COX-2, MLH1, and MSH2 in young patients with colon carcinoma and correlation with morphologic findings

Despite an overall decrease in colorectal carcinoma incidence, rates of colorectal carcinoma have increased substantially in patients aged less than 40 years. Several authors have characterized morphologic features of colorectal carcinoma in young patients, with variable results. To date, there has been 1 detailed molecular and immunohistochemical study in young patients with colorectal carcinoma. We sought to expand the data regarding young patients with colorectal carcinoma by a detailed assessment of morphologic features and by assaying expression of p27, COX-2, MLH1, and MSH2, markers with prognostic or therapeutic implications in colorectal carcinoma. We searched our pathology database from 1985 to 2009 and, after exclusion of cases with insufficient data or neoadjuvant therapy, identified a study population of 23 patients aged 40 or younger, 35 patients between 41 and 49 years of age, and a control group of 83 colorectal carcinoma patients aged 50 or older. Younger patients had higher tumor grade (P = .0085), with a trend toward mucinous differentiation and lymphovascular and perineural invasion. Loss of MSH2 was more prominent in younger patients (P = .02). Loss of p27 expression was not associated with age, but was associated with higher tumor stage (P = .0278), mucinous/signet ring differentiation (P = .0185), loss of either MLH1 or MSH2 (P = .0035), and larger tumor size (P = .0019). There was a trend toward lower COX-2 expression in younger patients, with less COX-2 expression relative to previously published data. Our findings support some prior reports regarding morphologic features in colorectal carcinoma in young patients and provide novel data on expression of several markers in this population.

Expression of cell cycle regulators p21 and p27 as predictors of disease outcome in colorectal carcinoma

BACKGROUND

Recent studies suggest that aberrations in cell cycle checkpoint controllers are a common feature in human malignancies and predict prognosis independent of stage.

OBJECTIVES

This study correlated two cell cycle regulators (p27 and p21) with clinical and pathological variables in colorectal cancer (CRC) patients to assess their role as prognostic factors.

PATIENTS AND METHODS

A series of 65 CRC patients were analyzed for p27 and p21 expression in their tumors using immunohistochemistry.

RESULTS

Forty-six percent of tumors showed positive nuclear p27 expression, whereas 72% of cases were completely p21 negative. There were no significant correlations between p27 and p21 expression and gender, age, lymph node involvement, stage, and grade. However, p27 (but not p21) expression revealed highly significant correlation with tumor location (p < 0.01), depth of invasion (p < 0.03), and lympho-vascular invasion (p < 0.02). Tumors with high p27 expression showed a higher recurrence rate than tumors with no expression (p < 0.03). In Kaplan-Meier survival analysis, there was a significant (p = 0.046) difference in disease-free survival (DFS) between p27-positive and p27-negative tumors in favor of the latter. p21 did not show any predictive value of DFS (p < 0.7). Neither p27 nor p21 did predict disease-specific survival (DSS) in Kaplan-Meier analysis, but DSS time was much shorter for p27-positive tumors. In multivariate (Cox) model, p27 lost its value as independent predictor of DFS, and none of the covariates were independent predictors of DSS.

CONCLUSION

p27 expression seems to be more powerful than p21 expression in providing useful prognostic information in CRC, particularly in predicting the patients at high risk for recurrent disease. Larger cohort and longer follow-up are needed to fully elucidate the value of p27 (and p21) as independent predictors of disease outcome.

The role of the ubiquitin-proteasome system in kidney diseases

Proteins in mammalian cells are continually being degraded and synthesized. Protein degradation via the ubiquitin-proteasome system (UPS) is the major pathway for non-lysosomal proteolysis of intracellular proteins and plays important roles in a variety of fundamental cellular processes such as regulation of cell cycle progression, differentiation, apoptosis, sodium channel function, and modulation of inflammatory responses. The central element of this system is the covalent linkage of ubiquitins to targeted proteins, which are then recognized by the 26S proteasome composed of adenosine triphosphate-dependent, multi-catalytic proteases. Damaged or misfolded proteins, as well as regulatory proteins that control many critical cellular functions, are among the targets of this degradation process. Consequently, aberration of the system leads to dysregulation of cellular homeostasis and development of many diseases. Based on the findings, it is not surprising that abnormalities of the system are also associated with the pathogenesis of kidney diseases. In this review, I discuss (1) the basic mechanism of the UPS, and (2) the association between the pathogenesis of kidney diseases and the UPS. Diverse roles of the UPS are implicated in the development of kidney diseases, and further studies on this system may reveal new strategies for overcoming kidney diseases.

Haploinsufficient and predominant expression of multiple endocrine neoplasia type 1 (MEN1)-related genes, MLL, p27Kip1 and p18Ink4C in endocrine organs

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominantly inherited syndrome characterized by parathyroid, gastro-entero-pancreatic and anterior pituitary tumors. Although the tissue selectivity of tumors in specific endocrine organs is the very essence of MEN1, the mechanisms underlying the tissue-selectivity of tumors remain unknown. The product of the Men1 gene, menin, and mixed lineage leukemia (MLL) have been found to cooperatively regulate p27(Kip1)/CDKN1B (p27) and p18(Ink4C)/CDKN2C (p18) genes. However, there are no reports on the tissue distribution of these MEN1-related genes. We investigated the expression of these genes in the endocrine and non-endocrine organs of wild-type, Men1 knockout and MLL knockout mice. Men1 mRNA was expressed at a similar level in endocrine and non-endocrine organs. However, MLL, p27 and p18 mRNAs were predominantly expressed in the endocrine organs. Notably, p27 and MLL mRNAs were expressed in the pituitary gland at levels approximately 12- and 17-fold higher than those in the liver. The heterozygotes of Men1 knockout mice the levels of MLL, p27 and p18 mRNAs did not differ from those in the wild-type mice. In contrast, heterozygotes of MLL knockout mice showed significant reductions in p27 mRNA as well as protein levels in the pituitary and p27 and p18 in the pancreatic islets, but not in the liver. This study demonstrated for the first time the predominant expression MEN1-related genes, particularly MLL and p27, in the endocrine organs, and a tissue-specific haploinsuffiency of MLL, but not menin, may lead to a decrease in levels of p27 and p18 mRNAs in endocrine organs. These findings may provide basic information for understanding the mechanisms of tissue selectivity of the tumorigenesis in patients with MEN1.

EZH2 depletion blocks the proliferation of colon cancer cells

The Enhancer of Zeste 2 (EZH2) protein has been reported to stimulate cell growth in some cancers and is therefore considered to represent an interesting new target for therapeutic intervention. Here, we investigated a possible role of EZH2 for the growth control of colon cancer cells. RNA interference (RNAi)-mediated intracellular EZH2 depletion led to cell cycle arrest of colon carcinoma cells at the G1/S transition. This was associated with a reduction of cell numbers upon transient transfection of synthetic EZH2-targeting siRNAs and with inhibition of their colony formation capacity upon stable expression of vector-borne siRNAs. We furthermore tested whether EZH2 may repress the growth-inhibitory p27 gene, as reported for pancreatic cancer. However, expression analyses of colon cancer cell lines and colon cancer biopsies did not reveal a consistent correlation between EZH2 and p27 levels. Moreover, EZH2 depletion did not re-induce p27 expression in colon cancer cells, indicating that p27 repression by EZH2 may be cell- or tissue-specific. Whole genome transcriptome analyses identified cellular genes affected by EZH2 depletion in colon cancer cell lines. They included several cancer-associated genes linked to cellular proliferation or invasion, such as Dag1, MageD1, SDC1, Timp2, and Tob1. In conclusion, our results demonstrate that EZH2 depletion blocks the growth of colon cancer cells. These findings might provide benefits for the treatment of colon cancer.

Parathyroid hormone and the regulation of cell cycle in colon adenocarcinoma cells

Parathyroid hormone (PTH) functions as a major mediator of bone remodeling and as an essential regulator of calcium homeostasis. In this study, we investigated the role of PTH in the regulation of the cell cycle in human colon adenocarcinoma Caco-2 cells. Flow cytometry analysis revealed that PTH (10(-8)M, 12-24h) treatment increases the number of cells in the G0/G1 phase and diminishes the number in both phases S and G2/M. In addition, analysis by Western blot showed that the hormone increases the expression of the inhibitory protein p27Kip1 and diminishes the expression of cyclin D1, cyclin D3 and CDK6. However, the amounts of CDK4, p21Cip1, p15INK4B and p16INK4A were not different in the absence or presence of PTH. Inhibitors of PKC (Ro-318220, bisindolylmaleimide and chelerythine), but not JNK (SP600125) and PP2A (okadaic acid and calyculin A), reversed PTH response in Caco-2 cells. Taken together, our results suggest that PTH induces G0/G1 phase arrest of Caco-2 intestinal cells and changes the expression of proteins involved in cell cycle regulation via the PKC signaling pathway.

Overexpression of phosphorylated p27 Kip1 at threonine 187 may predict outcome in aggressive B-cell lymphomas

Phosphorylation of p27(Kip1) at threonine 187 (pThr187-p27(Kip1)) occurs frequently in the development of human tumors, directing protein polyubiquitination and subsequent proteasomal degradation. We investigated the immunoexpression of p27(Kip1) and pThr187-p27(Kip1) in 126 B-cell lymphomas and their relation to proliferative activity and clinical parameters. Increased levels of p27(Kip1) and pThr187-p27(Kip1) were significantly correlated with indolent and aggressive lymphomas, respectively (p < 0.001). pThr187-p27(Kip1) expression showed a strong positive correlation with proliferation index in aggressive (p = 0.01) and indolent (p < 0.001) subgroups. Survival analysis revealed that pThr187-p27(Kip1) was an unfavorable prognostic factor for disease-free (p = 0.019) and overall survival (p = 0.003) in aggressive lymphomas. Cox regression analysis demonstrated that the prognostic value of pThr187-p27(Kip1) was independent of the international prognostic index (IPI) score, tumor stage, patient age, and serum lactate dehydrogenase (LDH) level. Overall, our results suggest that high levels of pThr187-p27(Kip1) may predict a worse clinical outcome in patients with aggressive lymphomas.

Attenuated expression of menin and p27 (Kip1) in an aggressive case of multiple endocrine neoplasia type 1 (MEN1) associated with an atypical prolactinoma and a malignant pancreatic endocrine tumor

Tumors in multiple endocrine neoplasia type 1 (MEN1) are generally benign. Since information on the pathogenesis of MEN1 in malignant cases is limited, we conducted genetic analysis and compared the expression of menin, p27(Kip1)(p27)/CDKN1B and p18(Ink4C)(p18)/CDKN2C with levels in benign cases. We describe the case of a 56 year-old male with an atypical prolactinoma and malignant pancreatic neuroenocrine tumor. At age 50, he had undergone transsphenoidal surgery to remove a prolactinoma. However, the tumor relapsed twice. Histological analysis of the recurrent prolactinoma revealed the presence of prolactin, a high MIB-1 index (32.1 %), p53-positive cells (0.2%), and an unusual association with FSH-positive cells. A few years later, he was also found to have a non-functioning pancreatic tumor with probable metastasis to the extradullar region. The metastatic region tested positive for chromogranin and CD56, and negative for prolactin, with 1.2 % of cells p53-positive. Although genetic analyses of the MEN1, p27, and p18 genes demonstrated no mutation, numbers of menin, p27 and p18 immuno-positive cells were significantly down-regulated in the recurrent prolactinoma, but that of p18 was intact in the metastatic region. Furthermore, MEN1 and p27 mRNA levels of the recurrent prolactinoma were down-regulated, particularly the MEN1 mRNA level, compared to levels in 10 cases of benign prolactinoma, while the p18 mRNA level was similar to that of normal pituitary. The tumor in this case may be a subtype of MEN1 showing more aggressive and malignant features probably induced by low levels of menin and p27.

Cyclin-dependent kinase inhibitor p27 as a prognostic biomarker and potential cancer therapeutic target

The prognosis and clinical management of patients with cancer is commonly determined by traditional clinical and pathological factors. Nevertheless, patients may present with significantly different clinical outcomes despite similar clinicopathological features. This has prompted intense research to find biological markers that may closely reflect tumor biology and thereby clinical outcome. This article presents the current knowledge on the prognostic significance of p27 expression in cancer and its potential role as a target for future therapy.

RNA-binding protein quaking, a critical regulator of colon epithelial differentiation and a suppressor of colon cancer

BACKGROUND & AIMS

Colon cancer is one of the best understood neoplasms from a genetic perspective, yet it remains the second most common cause of cancer-related death. Post-transcriptional regulation mediated by RNA-binding proteins or microRNAs coordinately targets multiple genes, holding promise involved in colon cancer initiation and development. Here we studied the role of RNA-binding protein quaking (QKI) in colon cancer.

METHODS

We observed the expression pattern of QKI in normal colon and colon cancers through reverse-transcription polymerase chain reaction and Western blot. Bisulfite sequencing and methylation-specific PCR were applied for QKI promoter methylation analysis. We used enterocyte differentiation markers and soft agar assay to test the role of QKI in colon differentiation and colon cancer development. 3' Untranslated region (UTR) reporter assay and RNA-immunoprecipitation were used to confirm the interaction between QKI and beta-catenin or p27.

RESULTS

QKI is significantly down-regulated and even absent in some colon cancers, which is at least partially because of the promoter hypermethylation. Forced expression of QKI in the colon cancer cells increased the expression of enterocyte differentiation marker intestinal alkaline phosphatase and lactase, together with the enhancement of p27Kip1 protein level, and membrane localized beta-catenin. Finally, QKI overexpression reduced the proliferation and tumorigenesis ability.

CONCLUSIONS

Our study establishes that QKI functions as a principal regulator in the differentiation of colon epithelium and a suppressor of carcinogenesis through coordinately targeting multiple genes associated with cell growth and differentiation, whose deregulation by methylation is involved in colon cancer onset and progress.

A cohort study of p27 localization in colon cancer, body mass index, and patient survival

Energy balance and the AKT pathway are important in colorectal cancer development and regulate p27 (cyclin-dependent kinase inhibitor-1B/CDKN1B/KIP1), which plays a role in preventing cell cycle progression. However, little is known on the clinical outcome or prognostic significance of p27 alterations in relation to patient body mass index (BMI). Among 630 colon cancers (stage I-IV) in two prospective cohort studies, we detected p27 alterations (cytoplasmic p27 localization or p27 loss) in 500 tumors (79%) by immunohistochemistry. The remaining 130 (21%) tumors were "p27-nuclear+." Cox proportional hazard models computed hazard ratios (HR) of deaths, adjusted for patient and tumoral characteristics, including p53, p21, cyclin D1, KRAS, BRAF, PIK3CA, cyclooxygenase-2, fatty acid synthase (FASN), beta-catenin, microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and long interspersed nucleotide element-1 (LINE-1) hypomethylation. Compared with p27-nuclear+ patients, p27-altered patients experienced low colon cancer-specific [adjusted HR, 0.63; 95% confidence interval (95% CI), 0.42-0.94] and overall mortality (adjusted HR, 0.70; 95% CI, 0.51-0.95), independent of FASN, MSI, CIMP, LINE-1 methylation, and other potential confounders. The effect of p27 alteration on overall mortality significantly differed by BMI (P(interaction) = 0.013); adjusted HR (p27-altered versus p27-nuclear+ tumors) was 0.28 (95% CI, 0.13-0.59) for BMI >or=30 kg/m(2), 0.67 (95% CI, 0.40-1.14) for BMI 25 to 29 kg/m(2), and 0.91 (95% CI, 0.57-1.46) for BMI <25 kg/m(2). Obesity was associated with inferior overall survival among p27-nuclear+ cases (adjusted HR, 3.07; 95% CI, 1.49-6.32; versus nonobese cases), but not among p27-altered cases (adjusted HR, 1.08). In conclusion, p27 alterations in colon cancer are associated with superior prognosis. Adverse prognostic effect of obesity seems limited to patients with nuclear p27 expression, suggesting a host-tumor interaction.

p27Kip1 in stage III colon cancer: implications for outcome following adjuvant chemotherapy in cancer and leukemia group B protocol 89803

BACKGROUND

In retrospective studies, loss of p27(Kip1) (p27), a cyclin-dependent kinase inhibitor, has been associated with poor prognosis following colorectal cancer treatment. In a prospective study, we validated this relationship in patients enrolled on a trial of adjuvant chemotherapy for stage III colon cancer.

METHODS

Cancer and Leukemia Group B protocol 89803 randomized 1,264 stage III colon cancer patients to receive weekly bolus 5-fluorouracil/leucovorin or weekly bolus irinotecan, 5-fluorouracil, and leucovorin (IFL). The primary endpoint was overall survival (OS); disease-free survival was a secondary endpoint. Expression of p27 and DNA mismatch repair proteins were determined by immunohistochemistry in primary tumor and normal tissue from paraffin blocks. Data were analyzed using log-rank test.

RESULTS

Of 601 tumors analyzed, 207 (34.4%) showed p27 loss, 377 (62.8%) retained p27, and 17 (2.8%) were indeterminate. Patients with p27-negative tumors showed reduced OS [5-year OS 66%: 95% confidence interval (95% CI), 0.59-0.72 versus 75%: 95% CI, 0.70-0.79; log-rank P = 0.021]. This relationship was not influenced by treatment arm. Combination of p27 status with mismatch repair status, however, identified a small subset of patients that may benefit from IFL (n = 36; 5-year disease-free survival 81%: 95% CI, 0.64-0.98 versus 47%: 95% CI, 0.21-0.72; log-rank P = 0.042; 5-year OS 81%: 95% CI, 0.64-0.98 versus 60%: 95% CI, 0.35-0.85; log-rank P = 0.128).

CONCLUSIONS

Loss of p27 is associated with reduced survival in stage III colon cancer but by itself does not indicate a significant difference in outcome between patients treated IFL or 5-fluorouracil/leucovorin.

Energy balance, physical activity, and cancer risk

This chapter posits that cancer is a complex and multifactorial process as demonstrated by the expression and production of key endocrine and steroid hormones that intermesh with lifestyle factors (physical activity, body size, and diet) in combination to heighten cancer risk. Excess weight has been associated with increased mortality from all cancers combined and for cancers of several specific sites. The prevalence of obesity has reached epidemic levels in many parts of the world; more than 1 billion adults are overweight with a body mass index (BMI) exceeding 25. Overweight and obesity are clinically defined indicators of a disease process characterized by the accumulation of body fat due to an excess of energy intake (nutritional intake) relative to energy expenditure (physical activity). When energy intake exceeds energy expenditure over a prolonged period of time, the result is a positive energy balance (PEB), which leads to the development of obesity. This physical state is ideal for intervention and can be modulated by changes in energy intake, expenditure, or both. Nutritional intake is a modifiable factor in the energy balance-cancer linkage primarily tested by caloric restriction studies in animals and the effect of energy availability. Restriction of calories by 10 to 40% has been shown to decrease cell proliferation, increasing apoptosis through anti-angiogenic processes. The potent anticancer effect of caloric restriction is clear, but caloric restriction alone is not generally considered to be a feasible strategy for cancer prevention in humans. Identification and development of preventive strategies that "mimic" the anticancer effects of low energy intake are desirable. The independent effect of energy intake on cancer risk has been difficult to estimate because body size and physical activity are strong determinants of total energy expenditure. The mechanisms that account for the inhibitory effects of physical activity on the carcinogenic process are reduction in fat stores, activity related changes in sex-hormone levels, altered immune function, effects in insulin and insulin-like growth factors, reduced free radical generation, and direct effect on the tumor. Epidemiologic evidence posits that the cascade of actions linking overweight and obesity to carcinogenesis are triggered by the endocrine and metabolic system. Perturbations to these systems result in the alterations in the levels of bioavailable growth factors, steroid hormones, and inflammatory markers. Elevated serum concentrations of insulin lead to a state of hyperinsulinemia. This physiological state causes a reduction in insulin-like growth factor-binding proteins and promotes the synthesis and biological activity of insulin-like growth factor (IGF)-I, which regulates cellular growth in response to available energy and nutrients from diet and body reserves. In vitro studies have clearly established that both insulin and IGF-I act as growth factors that promote cell proliferation and inhibit apoptosis. Insulin also affects on the synthesis and biological availability of the male and female sex steroids, including androgens, progesterone, and estrogens. Experimental and clinical evidence also indicates a central role of estrogens and progesterone in regulating cellular differentiation, proliferation, and apoptosis induction. Hyperinsulinemia is also associated with alterations in molecular systems such as endogenous hormones and adipokines that regulate inflammatory responses. Obesity-related dysregulation of adipokines has the ability to contribute to tumorigenesis and tumor invasion via metastatic potential. Given the substantial level of weight gain in industrialized countries in the last two decades, there is great interest in understanding all of the mechanisms by which obesity contributes to the carcinogenic process. Continued focus must be directed to understanding the various relationships between specific nutrients and dietary components and cancer cause and prevention. A reductionist approach is not sufficient for the basic biological mechanisms underlying the effect of diet and physical activity on cancer. The joint association between energy balance and cancer risk are hypothesized to share the same underlying mechanisms, the amplification of chemical mediators that modulate cancer risk depending on the responsiveness to those hormones to the target tissue of interest. Disentangling the connection between obesity, the insulin-IGF axis, endogenous hormones, inflammatory markers, and their molecular interaction is vital.

Expression patterns of cyclins D1, E and cyclin-dependent kinase inhibitors p21waf1/cip1, p27kip1 in colorectal carcinoma: correlation with other cell cycle regulators (pRb, p53 and Ki-67 and PCNA) and clinicopathological features

Aberrations in the cell cycle regulators are common features of many tumours and several have been shown to have prognostic significant in colorectal cancer. The expression patterns of cyclins D1 and E as well as cyclin-dependent kinase (CDK) inhibitors p21waf1/cip1 and p27kip1 and their interrelationship with other cell cycle checkpoint proteins [p53, pRb, Ki-67 and proliferative cell nuclear antigen (PCNA)] were investigated in colorectal cancer in order to ascertain coregulation and influence on tumour behaviour or survival. These molecular markers were localisated immunohistochemically using the monoclonal antibodies anticyclin D1 (DCS-6), anticyclin E (13A3), anti-p21 (4D10), anti-p27 (1B4), anti-p53 (DO7), anti-Rb (AB-5), MIB1 and PC10 in colorectal cancer tissue from 97 patients. Data were analysed statistically using the spss software program. Overexpression of cyclin D1, cyclin E and p21waf1/cip1 proteins (>5% positive neoplastic cells) was observed in 5.9%, 30% and 7.2% of the cases respectively. Increased levels of cyclin D1 (p = 0.0001) and p21waf1/cip1 protein (p = 0.03) in tumours with mucous differentiation were observed. Overexpression of cyclin D1 was correlated with tumour stage (p = 0.03), the lymph node involvement (p = 0.02), as well as p21waf1/cip1 protein expression (p < 0.0001). Cyclin E was positively correlated with p21waf1/cip1 (p = 0.014), as well as with the cell proliferation as measured by PCNA-labelling index (p = 0.011) and Ki-67 score (p = 0.007). A positive relationship of p21waf1/cip1 expression with the proliferative-associated index Ki-67 was noted (p = 0.005). Downregulation of p27kip1 was observed in 47.4% of the cases and was correlated with downregulation of pRb (p = 0.002) and PCNA score (p = 0.004). The prognostic significance of cyclins D1, E and CDK inhibitors p21waf1/cip1, p27kip1 in determining the risk of recurrence and overall survival with both univariate (long-rang test) and multivariate (Cox regression) methods of analysis showed no statistically significance differences. In conclusion, these findings suggest that, the levels of the cell cycle regulators studied, do not seems to have a prognostic value, in terms of predicting the risk of early recurrence and overall survival. In addition, the interrelationships, probably means their contribution to the regulation of cell growth, through different pathways in colorectal carcinogenesis.

The ubiquitin-proteasome system in colorectal cancer

The proteasome is a multiprotein complex that regulates the stability of hundreds of cellular proteins and thus, it is implicated in virtually all cellular functions. Most of the time, to be recognized and processed by the proteasome, a protein has to be linked to a chain of ubiquitin molecules. Cell proliferation, apoptosis, angiogenesis and motility, processes with particular importance for carcinogenesis are regulated by the ubiquitin-proteasome system (UPS). In colorectal epithelium, UPS plays a role in the regulation of the Wnt/beta-catenin/APC/TCF4 signaling which regulates proliferation of colorectal epithelial cells in the bottom of the crypts and the inhibition of this proliferation as cells move towards colon villi tips. In most colorectal cancers APC (Adenomatous Polyposis Coli) disabling mutations interfere with the ability of the proteasome to degrade beta-catenin leading to uninhibited cell proliferation. Other key molecules in colorectal carcinogenesis such as p53, Smad4 and components of the k-ras pathways are also regulated by the UPS. In this review I discuss the role of UPS in colorectal carcinogenesis and colorectal cancer prognosis and aspects of its inhibition for therapeutic purposes.

The Cdk inhibitor p27 in human cancer: prognostic potential and relevance to anticancer therapy

The cyclin-dependent kinase (Cdk) inhibitor p27 (also known as KIP1) regulates cell proliferation, cell motility and apoptosis. Interestingly, the protein can exert both positive and negative functions on these processes. Diverse post-translational modifications determine the physiological role of p27. Phosphorylation regulates p27 binding to and inhibition of cyclin-Cdk complexes, its localization and its ubiquitin-mediated proteolysis. In cancers, p27 is inactivated through impaired synthesis, accelerated degradation and by mislocalization. Moreover, studies in several tumour types indicate that p27 expression levels have both prognostic and therapeutic implications.

Can the clinical outcome in stage II colon carcinomas be predicted by determination of molecular marker expression?

BACKGROUND

Conventional staging procedures are often unable to precisely predict prognosis in colon cancer (CC). In this study, we set out to investigate the possible role of molecular/structural indicators involved in cell cycle regulation (Ki-67, p53), apoptosis (p53 and bcl-2) and tumour neoangiogenesis (anti-VIII factor) in predicting tumour behaviour and clinical outcome in stage II CC patients.

EXPERIMENTAL DESIGN

Analysis of the above indicators was performed by immunohistochemistry on 162 CC patient samples with curative intention surgery. Clinicopathological data included tumour grade, vascular and nervous invasion, production of mucin, lymphatic permeation and carcinoembryonic antigen levels.

RESULTS

p53 protein was overexpressed in 58%, bcl-2 overexpression in 21.5%, Ki-67 in 60.1% and anti-VIII factor stained positive in 40.16% of the cases. Multiple regression analysis showed that some molecular markers were correlated. A significant relationship was seen between p53 and Ki-67, and bcl-2 and p53, but there was no correlation between bcl2 and Ki- 67 overexpression. Stepwise regression selected Ki-67 and anti-VIII factor as the best combination of variables capable of predicting both disease-specific and diseasefree survival.

CONCLUSIONS

Only Ki-67 and anti-VIII factor were shown to be useful for the prediction of outcome and recurrence rate in curatively treated CC patients. In conjunction with clinical and pathological staging, they may provide a stronger indication of clinical outcome than staging alone and help better select therapeutic options in CC patients.

Survival stratification panel of colorectal carcinoma with combined expression of carcinoembryonic antigen, matrix metalloproteinases-2, and p27 kip1

PURPOSE

The prognosis varies greatly in colorectal carcinoma patients, even in the same stage. We examined the association between the expression of matrix metalloproteinases-2, carcinoembryonic antigen, p27 kip1, and clinicopathologic features in patients with colorectal carcinoma to identify a possible panel of tumor markers in predicting prognosis of colorectal carcinoma.

METHODS

The expressions of three individual markers in 127 colorectal carcinoma cases were analyzed by immunohistochemistry method. Univariate and multivariate analysis were performed to analyze the expression with the disease-free survival time in colorectal carcinoma.

RESULTS

High expression of matrix metalloproteinases-2, carcinoembryonic antigen, and low expression of p27 kip1 were related to poor prognosis in univariate analysis (P = 0.0002; P < 0.0001; P = 0.0008). The expression of matrix metalloproteinases-2, carcinoembryonic antigen, p27 kip1, and tumor differentiation were independent prognostic factors for disease-free survival by Cox regression analysis. The coexpression panel of matrix metalloproteinases-2, carcinoembryonic antigen, and p27 kip had significant prognostic value in all patients (P AB = 0.0103; P(BC) = 0.0068; P CD = 0.0117). Multivariate analysis with Cox regression reveals that coexpression of matrix metalloproteinases-2, carcinoembryonic antigen, and p27 kip1 were independent prognostic factors as tumor differentiation in colorectal carcinoma. In different stages, coexpression tumor markers functioned in Stages II and III but not in the 19 cases of Stage I. The reason might be the number of patients was too small.

CONCLUSIONS

The results of this study provided further evidence that the combination of tumor markers of matrix metalloproteinases-2, carcinoembryonic antigen, and p27 kip1 was more informative than any single tumor marker alone for the disease-free survival stratification of colorectal carcinoma. Coexpression of matrix metalloproteinases-2, carcinoembryonic antigen, and p27 kip1 might be a useful survival stratification panel for clinical management.

Loss of p27 expression and microsatellite instability in sporadic colorectal cancer

BACKGROUND

The role of the loss of p27 protein expression in the oncogenesis of colorectal cancer is still in debate. In this study, we prospectively examined the immunohistochemical expression of p27 in 108 consecutive colorectal cancers, and we analysed the relationship with the results, the clinicopathological data, microsatellite instability (MSI) and other genetic alterations of tumours.

METHODS

Unselected patients (108) who underwent curative colorectal resection for sporadic colorectal cancer in a three-year period were evaluated for MSI using 6 microsatellite markers, and for the presence of p27, p53, Fhit, Mlh1 and Msh2 proteins by means of immunostaining. The relationships between these markers were analysed. p27 protein expression was examined for association with disease recurrences and survival.

RESULTS

Lack of p27 expression was noted in 33 out of 108 (30.5%) colorectal cancer cases (P<0.05). This altered expression was significantly higher in proximal cancers (P<0.05), mucinous tumours (P<0.001), poorly differentiated histology (P<0.01), cancers with MSI (P<0.05), tumours with altered expression of Mlh1 (P<0.01), of Msh2 (P<0.05), and of Fhit (P<0.01). Overall survival was better in the patient group with altered level of phenotypic p27 expression, although the difference does not reach statistical significance (P=0.069). The analysis performed only for patients with tumour at stage II showed significantly better survival when the tumour exhibited altered p27 expression (P<0.02).

CONCLUSIONS

The results of the present study support the hypothesis that altered expression of p27 may be part of the genetic pathway involving MSI, which is responsible for the development of some colorectal cancers.

Increased expression of SKP2 and phospho-MAPK/ERK1/2 and decreased expression of p27 during tumor progression of cervical neoplasms

OBJECTIVE

The objective of this study was to investigate whether the expression of SKP2, p27 and phospho-MAPK/ERK1/2 is associated with the progression of human cervical neoplasia.

METHODS

We performed immunohistochemical detection to stain formalin-fixed paraffin-embedded cervical tissues with anti-SKP2 and anti-p27 monoclonal antibodies and anti-phospho-p42/44 MAPK antibody. The study sample included 23 normal cervical epithelium, 25 low-grade squamous intraepithelial lesion (LSIL), 19 high-grade squamous intraepithelial lesion (HSIL), and 31 squamous cell carcinomas (SCC). In addition, 14 frozen cervical biopsies, including 1 normal, 6 HSIL, 2 adenocarcinoma and 5 SCC, and a human cervical cancer cell line (HeLa), were analyzed the expression levels of mRNA and protein of SKP2 and p27 by RT-PCR and Western blot analysis, respectively.

RESULTS

The expression of SKP2, p27 and phospho-MAPK/ERK1/2 were strongly associated with cervical neoplastic progression (P<0.0001, P=0.006, P=0.003, respectively; Fisher's Exact Test). In addition, SKP2 expression was positively correlated with phospho-MAPK/ERK1/2 expression (Spearman correlation coefficient=0.480, P=0.0002). The association between SKP2 and phospho-MAPK/ERK1/2 was significant after controlling for the four histologic grades (P=0.038, Mantel-Haenszel test).

CONCLUSIONS

These results suggest that expression levels of SKP2, p27 and phospho-MAPK/ERK1/2 may serve as markers for progression in human cervical carcinoma and may also play roles in cervical carcinoma progression and cervical carcinogenesis.

In vitro differentiation of HT-29 M6 mucus-secreting colon cancer cells involves a trychostatin A and p27KIP1-inducible transcriptional program of gene expression

Tumor cell dedifferentiation-such as the loss of cell-to-cell adhesion in epithelial tumors-is associated with tumor progression. To better understand the mechanisms that maintain carcinoma cells in a differentiated state, we have dissected in vitro differentiation pathways in the mucus-secretor HT-29 M6 colon cancer cell line, which spontaneously differentiates in postconfluent cultures. By lowering the extracellular calcium concentration to levels that prevent intercellular adhesion and epithelial polarization, our results reveal that differentiation is calcium-dependent and involves: (i) a process of cell cycle exit to G(0) and (ii) the induction of a transcriptional program of differentiation gene expression (i.e., mucins MUC1 and MUC5AC, and the apical membrane peptidase DPPIV). In calcium-deprived, non-differentiated postconfluent cultures, differentiation gene promoters are repressed by a trichostatin A (TSA)-sensitive mechanism, indicating that loss of gene expression by dedifferentiation is driven by histone deacetylases (HDAC). Since TSA treatment or extracellular calcium restoration allow gene promoter activation to similar levels, we suggest that induction of differentiation is one mechanism of HDAC inhibitor antitumor action. Moreover, transcriptional de-repression can also be induced in non-differentiating culture conditions by overexpressing the cyclin-dependent kinase inhibitor p27(KIP1), which is normally induced during spontaneous differentiation. Since p27(KIP1) downregulation in colon cancer is associated with poor prognosis independently of tumor cell division rates, we propose that p27 (KIP1) may prevent tumor progression by, at least in part, enhancing the expression of some differentiation genes. Therefore, the HT-29 M6 model allows the identification of some basic mechanisms of cancer cell differentiation control, so far revealing HDAC and p27(KIP1) as key regulatory factors of differentiation gene expression.

Cytoplasmic localization of p27 (cyclin-dependent kinase inhibitor 1B/KIP1) in colorectal cancer: inverse correlations with nuclear p27 loss, microsatellite instability, and CpG island methylator phenotype

Cytoplasmic mislocalization of p27 (CDKN1B/KIP1) is caused by activated AKT1 and has been associated with poor prognosis in various cancers. CIMP in colorectal cancer is characterized by extensive promoter methylation and is associated with MSI-MSI-H and BRAF mutations. We have recently shown a positive correlation between MSI/CIMP and loss of nuclear p27. However, no study has examined cytoplasmic p27 mislocalization in relation to CIMP and MSI in colorectal cancer. Using MethyLight assays, we quantified DNA methylation in 8 CIMP-specific gene promoters (CACNA1G, CDKN2A (p16), CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1) in 853 colorectal cancer samples obtained from 2 large prospective cohorts. We assessed expressions of nuclear and cytoplasmic p27 and nuclear p53 by immunohistochemistry. Cytoplasmic p27 expression was inversely associated with loss of nuclear p27 (P < .0001), CIMP-high (P < .0001), MSI-H (P < .0001), and BRAF mutations (P < .0001). The inverse association of cytoplasmic p27 with CIMP-high (or MSI-H) was independent of MSI (or CIMP) status. In addition, the inverse association of cytoplasmic p27 with CIMP-high was independent of KRAS/BRAF status. BRAF and CDKN2A (p16) methylation were not correlated with cytoplasmic p27 after stratification by CIMP status. The inverse associations of cytoplasmic p27 with MSI-H and CIMP-high were much more pronounced in p53-negative than p53-positive tumors. In conclusion, cytoplasmic p27 expression is inversely associated with MSI-H and CIMP-high, particularly in p53-negative tumors, suggesting interplay of functional losses of p27 and p53 in the development of various molecular subtypes of colorectal cancer.

Loss of nuclear p27 (CDKN1B/KIP1) in colorectal cancer is correlated with microsatellite instability and CIMP

Downregulation of p27 (cyclin-dependent kinase inhibitor-1B, CDKN1B or KIP1) is caused by increased ubiquitin-mediated proteasomal degradation in colorectal cancer, and has been associated with poor prognosis. CpG island methylator phenotype (CIMP) is a phenotype of colorectal cancer with extensive promoter methylation, and associated with high degree of microsatellite instability (MSI-H) and BRAF mutations. We have recently shown that both CIMP and MSI-H are inversely associated with downregulation of p21 (CDKN1A or CIP1), another cyclin-dependent kinase inhibitor. However, no study to date has examined relationship between p27 and CIMP status in colorectal cancer. Using MethyLight assays, we measured DNA methylation in five CIMP-specific gene promoters {CACNA1G, CDKN2A (p16), CRABP1, MLH1 and NEUROG1} in 706 colorectal cancer samples obtained from two large prospective cohorts. Among the 706 tumors, 112 (16%) were CIMP-high tumors with >or=4/5 methylated promoters. We assessed p27 and p53 expressions by immunohistochemistry. Loss of nuclear p27 expression {observed in 231 tumors (33%)} was significantly associated with CIMP-high, MSI-H and BRAF mutations, and these associations were much more pronounced among p53-negative tumors than p53-positive tumors. When CIMP-high and non-CIMP-high tumors were stratified by MSI status (or KRAS and BRAF status), CIMP-high and MSI-H (but not BRAF mutations) were still significantly associated with nuclear p27 loss. Nuclear p27 loss did not appear to be directly related to CDKN2A (p16) methylation. We conclude that downregulation of nuclear p27 is associated with CIMP-high and MSI-H in colorectal cancer. These associations are stronger among p53 wild-type tumors, implying important interplay of p27 and p53 functions (or dysfunctions) in the development of various molecular subtypes of colorectal cancer.

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.

Cytoplasmic expression of p27kip1 is associated with a favourable prognosis in colorectal cancer patients

AIM: To evaluate the prognostic significance of p27^kip1 in colorectal cancer patients.

METHODS: Cytoplasmic and nuclear p27^kip1 expression was evaluated in 418 colorectal cancers using tissue microarrays. Data were associated with known patient and tumor variables and long-term patient outcomes, providing further insight into the mechanisms by which p27^kip1 may influence tumor development.

RESULTS: Nuclear and cytoplasmic p27^Kip1 expressions were detected in 59% and 19% of tumors respectively. Cytoplasmic p27^Kip1 was almost invariably associated with positive nuclear p27^Kip1 expression. Neither case correlated with known clinical or pathological variables, including tumor stage, grade or extramural vascular invasion. Furthermore, nuclear p27^kip1 expression had no impact on survival. However, we identified a significant correlation between expression of cytoplasmic p27^kip1 and longer disease-specific survival times. On multivariate analysis, TNM stage and extramural vascular invasion were highly significant independent prognostic factors, with positive cytoplasmic p27 expression showing a trend towards improved patient survival (P = 0.059).

CONCLUSION: These findings support the recent evidence that cytoplasmic p27^kip1 has a distinct and important biological role that can influence tumor outcome.

Testing the importance of p27 degradation by the SCFskp2 pathway in murine models of lung and colon cancer

Decreased expression of the CDK inhibitor p27kip1 in human tumors directly correlates with increased resistance to chemotherapies, increased rates of metastasis, and an overall increased rate of patient mortality. It is thought that decreased p27 expression in tumors is caused by increased proteasomal turnover, in particular activation of the pathway governed by the SCFskp2 E3 ubiquitin protein ligase. We have directly tested the importance of the SCFskp-mediated degradation of p27 in tumorigenesis by analyzing the tumor susceptibility of mice that express a form of p27 that cannot be ubiquitinated and degraded by this pathway (p27T187A). In mouse models of both lung and colon cancer down-regulation of p27 promotes tumorigenesis. However, we found that preventing p27 degradation by the SCFskp2 pathway had no impact on tumor incidence or overall survival in either tumor model. Our study unveiled a previously unrecognized role for the control of p27 mRNA abundance in the development of non-small cell lung cancers. In the colon cancer model, the frequency of intestinal adenomas was similarly unaffected by the p27T187A mutation, but, unexpectedly, we found that it inhibited progression of intestinal adenomas to carcinomas. These studies may guide the choice of clinical settings in which pharmacologic inhibitors of the Skp2 pathway might be of therapeutic value.

The clinical significance of p53, p21, and p27 expressions in rectal carcinoma

Many checkpoint proteins that are involved in the control of the cell cycle and apoptosis have been investigated, but only a few studies have evaluated the prognostic significance of multiple factors only in rectal carcinomas. The aim of this study was to determine the role of p53, p21, and p27 protein expression as a prognostic factor in rectal carcinomas. Formalin-fixed, paraffin-embedded tissue blocks from 45 rectal adenocarcinomas with appropriate clinical and prognostic data were examined. The standard streptavidin-biotin immunoperoxidase method was used for immunostaining with p53 protein, p21 WAF1/Cip1 protein, and p27 Kip1 protein. The extent of positive p53, p21, and p27 staining was graded semiquantitatively. The clinicopathologic and prognostic features were statistically analyzed. No significant association was found between p53 status and p21 or p27 protein expression (chi2 test, P=0.42 and P=0.18 respectively). There was no correlation between the expressions of p53, p21, and p27, and conventional clinicopathologic features. The mean time interval to recurrence was 25.7+/-24.7 months (range, 0-54 months). p53, p21, and p27 expression was not associated significantly with recurrence and distant metastasis. However, a significant relationship was found between the expression of p27 protein and hepatic metastasis (independent samples t-test, P=0.007). The authors concluded that p53, p27, and p21 protein expression was not related to the clinicopathologic parameters, tumor aggressiveness, metastatic potential, and survival in rectal carcinomas. Further studies are needed to evaluate the predictors of outcome in rectal cancer, considering a variety of prognosticators.

Prognostic significance of DCC and p27Kip1 in colorectal cancer

The progression of colorectal cancer is a multistage process associated with specific molecular alterations. The stepwise accumulation of these multiple genetic mutations progressively results in the acquisition of neoplastic cell behavior. The genetic abnormalities associated with the expression of metastatic phenotype, therefore, may be of prognostic significance in the clinical treatment of colorectal cancer patients. In this study, the immunohistochemical expression of the deleted in colorectal cancer gene (DCC) and p27Kip1 was assessed in 168 paraffin-embedded, formalin-fixed tumors of patients with stage II and III colorectal cancer. Kaplan-Meier survival curves and log-rank statistics were used to analyze survival times after curative primary tumor resection, and Cox proportional hazards models were used to adjust the assessment of demographic and clinical covariates. Loss of DCC or p27Kip1 expression had no influence on survival in patients with stage II or III colorectal cancer. The 5-year survival rates of DCC-positive and DCC-negative tumors were 51.8% and 35.7% (P=0.40), respectively. The 5-year survival rate of patients with p27Kip1-positive tumors was 47.9%, whereas the rate for patients with p27Kip1-negative tumors was 38.8% (P=0.68). After adjustment for all evaluated variables, neither DCC or p27Kip1 was found to be a predictor of survival (risk ratio for DCC, 0.98; 95% confidence interval, 0.66-1.56; P=0.92; risk ratio for p27Kip1, 0.87; 95% confidence interval, 0.58-1.29; P=0.49). The present study demonstrated that the expression of neither DCC nor p27Kip1 was predictive in poor survival outcome in patients with stage II or III colorectal cancer.

Determination of molecular marker expression can predict clinical outcome in colon carcinomas

PURPOSE

Conventional staging procedures are often unable to precisely predict prognosis in colorectal cancer (CRC). In this study, we set out to investigate the possible role of molecular/structural indicators involved in cell cycle regulation (p27 and p53), apoptosis (p53 and p27), and tumor neoangiogenesis [p53, vascular endothelial growth factor (VEGF), and microvessel count] in predicting tumor behavior and clinical outcome in CRC patients

EXPERIMENTAL DESIGN

Analysis of the above indicators was performed by immunohistochemistry on 104 CRC patient samples and 25 normal colon mucosa specimens.

RESULTS

Intense p27 nuclear staining was found in normal colon mucosa, with p53 nuclear staining and VEGF cytoplasmic accumulation <10%, and low microvessel count. In contrast, in CRC samples, p27 was down-regulated in 53.8%, p53 protein was overexpressed in 52%, and VEGF stained positive in 67.3% of the cases, respectively. Multiple regression analysis showed that molecular markers were strongly correlated. In patients treated with curative surgery, a significant relationship was seen between p27 down-regulation and Dukes' stage, nodal status, and the presence of distant metastases. VEGF overexpression correlated significantly with Dukes' stage, tumor (t) and metastasis (m) parameters, and left site. Stepwise regression selected p27, p53, VEGF, and Dukes' stage as the best combination of variables capable of predicting both disease-specific and disease-free survival.

CONCLUSIONS

The investigated indicators may be useful for the prediction of outcome and recurrence rate in curatively treated CRC patients. In conjunction with clinical and pathological staging, they may provide a stronger indication of clinical outcome than staging alone and help better select therapeutic options in CRC patients.

Tailored Chemotherapy for Colorectal Cancer: A New Approach to Therapy

The treatment of colorectal cancer has advanced over the past several years with the introduction of several active agents. Determining which patients to treat with chemotherapy and choosing optimal treatment would allow practioners to maximize the benefit of chemotherapy. Several prognostic and predictive markers have been identified and include oncogenes, tumor suppressor genes, genes involved in angiogenic and apoptotic pathways and cell proliferation, and those encoding targets of chemotherapy. Specifically, prognostic markers include deletion of 18q (DCC), p27 and microsatellite instability. Predictive markers are those that may determine efficacy of drugs used in colorectal cancer such as fluropyrimidines and oxaliplatin. Alterations in gene expression, protein expression and polymorphic variants in genes encoding thymidylate synthase, dihydropyrimidine dehydrogenase, and thymidine phosphorylase and excision repair cross-complementing genes (ERCC1) may be useful as markers for clinical drug response, survival and host toxicity. The integration of these prognostic and predictive markers would allow individualized treatment for patients, maximizing therapeutic effect and minimizing exposure to toxicity.

Colonic crypt changes during adenoma development in familial adenomatous polyposis: immunohistochemical evidence for expansion of the crypt base cell population

Familial adenomatous polyposis patients, who have a germline APC mutation, develop adenomas in normal-appearing colonic mucosa, and in the process usually acquire a mutation in the other APC allele as well. Nonetheless, the cellular mechanisms that link these initiating genetic changes with the earliest tissue changes (upward shift in the labeling index) in colon tumorigenesis are unclear. Based on the tenet that colorectal cancer originates from crypt stem cells (SCs) and on our kinetic modeling, we hypothesized that overpopulation of mutant colonic SCs is the missing link. Directly testing this hypothesis requires measuring changes in the size of the SC population, but specific markers for human colonic SCs are lacking. Hence, we used immunohistochemical mapping to study crypt base cells, of which SCs are a subset. Using colectomy specimens from 16 familial adenomatous polyposis and 11 control cases, we determined the topographic profiles of various cell populations along the crypt axis and the proportions of each cell type. In the formation of adenomatous crypts, the distribution of cells expressing crypt base cell markers (MSH2, Bcl-2, survivin) expanded toward the crypt surface and showed the greatest proportional increase (fivefold to eightfold). Cells expressing a marker for the upper crypt (p27(kip1)) shifted to the crypt bottom and showed the smallest increase. This suggests that: 1) during adenoma development, APC mutations cause expansion of the crypt base cell population, including crypt SCs; 2) SC overpopulation can explain the shifts in pattern of proliferative crypt cell populations in early colon tumorigenesis, and 3) mutant crypt SCs clonally expand to form colonic adenomas and carcinomas.

Prognostic value of p27, p53, and vascular endothelial growth factor in Dukes A and B colon cancer patients undergoing potentially curative surgery

PURPOSE

Early-stage colon cancer patients (Dukes A or B; pT1-T3 pNO pMO) are excluded from adjuvant chemotherapy following potentially curative surgery because they are expected to have good long-term survival. However, 20 percent to 30 percent of these patients ultimately succumb from recurrent disease. This indicates that the conventional staging procedures may be unable to precisely predict cancer prognosis.

METHODS

In 65 early-stage colon cancers, we investigated by immunohistochemistry the role of molecular markers such as p27, p53, and vascular endothelial growth factor in identifying high-risk patients who may benefit from adjuvant treatments.

RESULTS

No clinicopathologic factor, namely Dukes stage, t parameter, number of resected nodes, and vascular or lymphatic invasion, was found be an independent significant predictor of disease-specific and disease-free survival. In contrast, each molecular marker predicted survival and recurrence rates much better than the conventional Dukes staging system. The best combination of variables for prediction of long-term outcome and recurrence rate included p27, p53, and vascular endothelial growth factor. Interestingly, the greater the number of molecular alterations, the lower the five-year estimated survival function. Nearly all cancer-related deaths were observed among patients whose colon cancers expressed all three molecular alterations. Regardless of Dukes stage, the recurrence rate was found to increase with the increase in the number of molecular alterations. Early-stage colon cancers expressing p27 down-regulation and high p53 and vascular endothelial growth factor immunoreactivity showed a 100 percent actuarial four-year recurrence rate.

CONCLUSIONS

Assessment of molecular alterations may be useful to identify a higher-risk group of early-stage colon cancer patients who may benefit from adjuvant chemotherapy.

Expression of p27 in residual rectal cancer after preoperative chemoradiation predicts long-term outcome

BACKGROUND

Compared with surgery alone, preoperative radiotherapy and 5-fluorouracil-based chemotherapy (combined-modality therapy; CMT) improves outcomes in patients with locally advanced rectal cancer. Although numerous studies have focused on identifying molecular markers of prognosis in the primary rectal cancer before CMT, our aim was to identify markers of prognosis in residual rectal cancer after preoperative CMT.

METHODS

Sixty-seven patients with locally advanced (T3-4 and/or N1) rectal cancer were treated with preoperative radiotherapy (median, 5040 cGy) with or without 5-fluorouracil-based chemotherapy. Residual tumor in the resected specimen, available for 52 patients, was analyzed for tumor-node-metastasis stage, lymphovascular and/or perineural invasion, and immunohistochemical expression of p27, p21, p53, Ki-67, retinoblastoma gene, cyclin D1, and bcl-2. Recurrence-free survival (RFS) was determined by the Kaplan-Meier method and compared by the log-rank test.

RESULTS

With a median follow-up of 69 months, the overall 5-year RFS was 74%. RFS was significantly worse for patients with positive p27 expression (P = .005), T3-4 tumors (P = .02), and positive lymph nodes (P = .04) in the irradiated specimen. On multivariate analysis, positive p27 expression remained an independent negative prognostic factor for RFS (P = .04). None of the other proteins was significantly associated with RFS.

CONCLUSIONS

Our results indicate that positive p27 expression in rectal cancer after preoperative chemoradiation is an independent negative predictor of RFS. Expression of p27 in the residual rectal cancer may therefore identify patients with disease likely to be refractory to standard therapy and for whom investigational approaches should be strongly considered.

Expression profiling of colorectal carcinomas using tissue microarrays: cell cycle regulatory proteins p21, p27, and p53 as immunohistochemical prognostic markers in univariate and multivariate analysis

With the rapidly growing understanding of tumor biology, molecular staging of cancer is expected to improve prognostication. This would be particularly important for cancers amenable to adjuvant treatment, such as colorectal carcinomas. To generate data for this, the tissue microarray technique may prove useful. Tissue microarrays were constructed with triplicate cores (0.6 mm diameter) from the invasive margins of a consecutive single-institution series of 184 colorectal carcinomas. Immunostaining for p53, p21, p27, Ecadherin, and beta-catenin was scored. Tumor cell proliferation was assessed by mitotic indices and Ki-67 labeling, apoptosis by quantification of apoptotic bodies. Reduced nuclear immunostaining for p21 (<10%) and p27 (< or =50%) and reduced membranous expression of Ecadherin were significantly associated with a poorer clinical course by univariate analysis. beta-catenin immunostaining had no prognostic impact. Mitotic and apoptotic indices as well as Ki-67 labeling below the median were indicators of poor prognosis. Complete absence of p53 nuclear staining was a significant adverse prognostic factor. By Cox regression, p53 = 0%, p53 = 0%, in combination with p27 < or = 50%, the mitotic index and the combined mitotic and apoptotic index added prognostic information to UICC stage. The authors found that growth pattern, lymphohistiocytic response, lymphatic permeation, and venous spread, too, each was a strong prognosticator in addition to UICC stage. The results support that tissue microarrays are a useful tool for screening immunohistochemical markers for prognostic use. An immunopanel of p21, p27, and p53 could be useful for prognostication in colorectal carcinoma in addition to UICC stage.