Down-regulation of p27 is associated with development of colorectal adenocarcinoma metastases

UBAC2 promotes bladder cancer proliferation through BCRC-3/miRNA-182-5p/p27 axis

Emerging evidences have demonstrated that ubiquitin-associated domain-containing protein 2 (UBAC2) is closely related to the occurrence and development of malignant tumors. However, the functions and underlying molecular mechanisms of UBAC2 in bladder cancer (BC) development have not been defined. In this study, we found that both UBAC2 mRNA and protein levels were upregulated in BC tissues and cell lines, and knockdown of UBAC2 inhibited BC cells proliferation both in vitro and in vivo. Meanwhile, Kaplan-Meier survival plots of 406 BC cases from TCGA database showed that higher expression of UBAC2 in BC patients was associated with lower survival rate. Mechanistic studies revealed that knockdown of UBAC2 increased the expression of p27 by posttranscriptional regulation. Our previous study indicated that circular RNA BCRC-3 (BCRC-3) promoted the expression of p27 through interacting with miR-182-5p, and reversed miR-182-5p-induced inhibition of p27 3'UTR activity. In the present study, we found that UBAC2 could bind to BCRC-3, and subsequently affected the interaction of BCRC-3 with miR-182-5p to inhibit the expression of p27. Furthermore, knockdown of BCRC-3 partly reversed the upregulation of p27 expression induced by knockdown of UBAC2. Our findings highlight a novel mechanism of UBAC2 in regulating p27 through affecting the function of BCRC-3, and provide a research basis for the diagnostic and therapeutic application of BC.

Hepatic metastasis from colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers in the world. About two third of patients with CRC will develop distant recurrence at some point in time. Liver is the most common site where distant metastasis takes place. While the overall survival (OS) of patients with metastatic CRC was poor about 3 decades ago, there has been tremendous improvement in this area in the recent years. With the advent of effective systemic chemotherapy and biologic agents and better understanding of the biological behaviour of the tumour, aggressive treatment strategies such as metastatectomy of the liver metastases (or lung metastases) are now acceptable. More importantly, it has transformed the way how stage IV CRCs are being managed. From predominantly palliative as the primary aim, a comprehensive multidisciplinary approach is now the mainstay of treatment with very successful outcomes. Combination of systemic therapies with liver resection has been shown to be effective in providing promising survival benefits. In addition, other adjunctive modalities in targeting the liver metastases such as ablation, combining resection and ablation, transarterial chemoembolization, stereotactic body radiotherapy (SBRT), hepatic artery perfusion, etc. have also been demonstrated variable outcome in treating colorectal liver metastasis (CRLM). Very recently, transplant oncologists have also explored using liver transplantation as a treatment modality for unresectable CRLM, which has demonstrated very good long-term survival in well selected cases. The new paradigm in the treatment of metastatic CRC has dawned.

Helioxanthin suppresses the cross talk of COX-2/PGE2 and EGFR/ERK pathway to inhibit Arecoline-induced Oral Cancer Cell (T28) proliferation and blocks tumor growth in xenografted nude mice

Helioxanthin, an active compound from Taiwania cryptomerioides Hayata, has been shown to have various biological activities. However, their anticancer effect in oral squamous cell carcinoma has not been well established yet. Helioxanthin inhibited the proliferation of oral squamous cell carcinoma cells in a dose-dependent manner by inducing G2/M phase arrest. Similarly, helioxanthin inhibited cyclooxygenase-2, (COX-2), phosphorylated EGFR, and extracellular-signal-regulated kinases (ERK) protein level and further reduced the nuclear accumulation of phosphorylated epidermal growth factor receptor (pEGFR) and activator protein-1(AP-1) family protein, c-fos. Moreover, helioxanthin at the dose of 20 and 30 mg kg^-1 for 15 days reduced the tumor growth in animal model. This study demonstrated that Helioxanthin exerts its anticancer activity against oral cancer cells by downregulating EGFR/ERK/c-fos signaling pathway to inhibit COX-2 level and by activating cyclin-dependent kinase inhibitor (p27) to further induce G2/M cell cycle arrest. This helioxanthin may serve as a novel candidate for oral cancer prevention. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 2045-2056, 2016.

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.

PI3K/AKT pathway-mediated regulation of p27(Kip1) is associated with cell cycle arrest and apoptosis in cervical cancer

BACKGROUND

The cyclin-dependent kinase inhibitor p27(Kip1) is known to act as a putative tumor suppressor in several human cancers, including cervical cancer. Down-regulation of p27(Kip1) may occur either through transcription inhibition or through phosphorylation-dependent proteolytic degradation. As yet, the mechanism underlying p27(Kip1) down-regulation and its putative downstream effects on cervical cancer development are poorly understood. Here we assessed the expression and sub-cellular localization of p27(Kip1) and its effects on proliferation, cell cycle progression and (inhibition of) apoptosis in cervical cancer cells.

METHODS

Primary cervical cancer samples (n = 70), normal cervical tissue samples (n = 30) and cervical cancer-derived cell lines (n = 8) were used to assess the expression of p27(Kip1) and AKT1 by RT-PCR, Western blotting and immunohistochemistry, respectively. The effects of the PI3K inhibitor LY294004 and the proteasome inhibitor MG132 on cervical cancer cell proliferation were investigated using a MTT assay. Apoptosis and cell cycle analyses were carried out using flow cytometry, and sub-cellular p27(Kip1) localization analyses were carried out using immunofluorescence assays.

RESULTS

We observed p27(Kip1) down-regulation (p = 0.045) and AKT1 up-regulation (p = 0.046) in both the primary cervical cancer samples and the cervical cancer-derived cell lines, compared to the normal cervical tissue samples tested. Treatment of cervical cancer-derived cell lines with the PI3K inhibitor LY294002 resulted in a reduced AKT1 activity. We also observed a dose-dependent inhibition of cell viability after treatment of these cell lines with the proteasome inhibitor MG132. Treatment of the cells with LY294002 resulted in a G1 cell cycle arrest, a nuclear expression of p27(Kip1), and a cytoplasmic p27(Kip1) accumulation after subsequent treatment with MG132. Additionally, we found that the synergistic effect of MG132 and LY294002 resulted in a sub-G1 cell cycle arrest and apoptosis induction through poly (ADP-ribose) polymerase (PARP) cleavage.

CONCLUSION

Our data suggest that p27(Kip1) down-regulation in cervical cancer cells is primarily regulated through PI3K/AKT-mediated proteasomal degradation. The observed synergistic effect of the MG132 and LY294002 inhibitors may form a basis for the design of novel cervical cancer therapies.

Involvement of ERK1/2, p38 MAPK, and PI3K/Akt signaling pathways in the regulation of cell cycle progression by PTHrP in colon adenocarcinoma cells

Parathyroid hormone-related peptide (PTHrP) is distributed in most fetal and adult tissues, and its expression correlates with the severity of colon carcinoma. Recently we obtained evidence that in Caco-2 cells, a cell line from human colorectal adenocarcinoma, exogenous PTHrP increases the number of live cells, via ERK1/2, p38 MAPK, and PI3-kinase and induces the expression of cyclin D1, a cell cycle regulatory protein. In this study, we further investigated the role of PTHrP in the regulation of the cell cycle progression in these intestinal cells. Flow cytometry analysis revealed that PTHrP treatment diminishes the number of cells in the G0/G1 phase and increases the number in both S and G2/M phases. The hormone increases the expression of CDK6 and diminishes the amount of negative cell cycle regulators p27Kip1, p15INK4B, and p53. However, PTHrP does not modify the expression of cyclin D3, CDK4, and p16INK4A. In addition, inhibitors of ERK1/2 (PD98059), p38 MAPK (SB203580), and PI3Kinase (LY294002) reversed PTHrP response in Caco-2 cells. Taken together, our results suggest that PTHrP positively modulates cell cycle progression and changes the expression of proteins involved in cell cycle regulation via ERK1/2, p38 MAPK, and PI3K signaling pathways in Caco-2 cells.

Loss of p27 upregulates MnSOD in a STAT3-dependent manner, disrupts intracellular redox activity and enhances cell migration

Cell migration is a dynamic process that is central to a variety of physiological functions as well as disease pathogenesis. The modulation of cell migration by p27 (officially known as CDKN1B) has been reported, but the exact mechanism(s) whereby p27 interacts with downstream effectors that control cell migration have not been elucidated. By systematically comparing p27(+/+) mouse embryonic fibroblasts (MEFs) with genetically ablated p27(-/-) MEFs using wound-healing, transwell and time-lapse microscopic analyses, we provide direct evidence that p27 inhibits both directional and random cell migration. Identical results were obtained with normal and cancer epithelial cells using complementary knockdown and overexpression approaches. Additional studies revealed that overexpression of manganese superoxide dismutase (MnSOD, officially known as SOD2) and reduced intracellular oxidation played a key role in increased cell migration in p27-deficient cells. Furthermore, we identified signal transducer and activator of transcription 3 (STAT3) as the transcription factor responsible for p27-regulated MnSOD expression, which was further mediated by ERK- and ATF1-dependent transactivation of the cAMP response element (CRE) within the Stat3 promoter. Collectively, our data strongly indicate that p27 plays a crucial negative role in cell migration by inhibiting MnSOD expression in a STAT3-dependent manner.

The tumour biology of synchronous and metachronous colorectal liver metastases: a systematic review

Forty to fifty percent of colorectal cancer (CRC) patients develop colorectal liver metastases (CLM) that are either synchronous or metachronous in presentation. Clarifying whether there is a biological difference between the two groups of liver metastases or their primaries could have important clinical implications. A systematic review was performed using the following resources: MEDLINE from PubMed (1950 to present), Embase, Cochrane and the Web of Knowledge. Thirty-one articles met the inclusion criteria. The review demonstrated that the majority of studies found differences in molecular marker expression between colorectal liver metastases and their respective primaries in both the synchronous and metachronous groups. Studies investigating genetic aberrations demonstrated that the majority of changes in the primary tumour were 'maintained' in the colorectal liver metastases. A limited number of studies compared the primary tumours of the synchronous and metachronous groups and generally demonstrated no differences in marker expression. Although there were conflicting results, the colorectal liver metastases in the synchronous and metachronous groups demonstrated some differences in keeping with a more aggressive tumour subtype in the synchronous group. This review suggests that biological differences may exist between the liver metastases of the synchronous and metachronous groups. Whether there are biological differences between the primaries of the synchronous and metachronous groups remains undetermined due to the limited number of studies available. Future research is required to determine whether differences exist between the two groups and should include comparisons of the primary tumours.

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.

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.

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.

Dysregulation of the cell cycle and chromosomal imbalances in juxtaglomerular cell tumors - a comparative study with endocrine tumors of the pancreas

Two juxtaglomerular cell tumors (JGCTs) were investigated in comparison with 14 endocrine tumors of the pancreas (ETPs), focusing on the cell cycle, apoptosis, and cytogenetic changes. JGCTs revealed nuclear accumulation of Cyclin D(1), together with the cyclin-dependent kinase inhibitors p21(Cip1/Waf1) and p27(Kip1). In contrast, no accumulation of Cyclin D(3), p53, p16(INK4a), or Mdm-2 was seen. Bcl-2 protein was intensively, but Rb only moderately, expressed. This immunoreactive profile was not found in the ETPs, which were negative for Bcl-2, p27(Kip1), p21(Cip1/Waf1), and - with one exception - for Cyclin D(1) (1/14) but expressed Cyclin D(3) in 7/14 cases. JGCTs displayed characteristic genetic alterations with combined losses of chromosomes 9, 11, 15, and 21 and gains of chromosome 18. In contrast, no characteristic pattern of genetic alterations was found in ETPs. In both, the amount of chromosomal aberrations correlated with tumor size. In small ETPs and JGCTs, genetic losses dominated over gains of chromosomes, whereas in large/malignant ETPs, gains and losses were equally affected. Thus, JGCTs represent a special type of renal endocrine neoplasm characterized by deregulation of cell cycle components and a typical profile of chromosomal aberrations. Since only two JCTs were investigated, further studies for validation of these results are, however, necessary.

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.

Do young patients with colorectal cancer have a poorer prognosis than old patients?

BACKGROUND

Colorectal cancer (CRC) is generally a disease of the older population. The prognosis and clinicopathologic features of CRC in the young, compared with those in older patients, continue to be debated. The aim of this study was to compare the survival, clinicopathologic features, and tumor markers of CRC in patients aged 40 y or younger and older patients.

METHODS

A total of 230 patients with CRC of stage I-III were assessed retrospectively, with an endpoint of recurrence or metastasis after curative operation. The markers CEA, MMP-2, and p27(kip1) were studied by immunohistochemistry in all patients.

RESULTS

The young group comprised 28 (12.2%) patients aged 40 y or younger with a median age of 36 y. The remaining 202 patients (87.8%) comprised the old group, with a median age of 61 y. There were no statistical differences in gender distribution, tumor sites, tumor size, or gross type between the young and old groups. The young group had a higher incidence of mucinous adenocarcinoma (17.9%) than the old group (6.4%) (P = 0.035). The distribution of stage, differentiation grade, and extent of venous invasion were similar. The median disease-free survival time was 60 mo for the young group and 49 mo for the old. Univariate analysis revealed that this difference was not significant (P = 0.1158). Multivariate Cox regression analysis also demonstrated that the age of the patient was not an independent factor for the prognosis of CRC. There were no statistical differences between the young and old groups in the expression of CEA, MMP-2, or p27(kip1).

CONCLUSIONS

The results of this study indicated that there was a subtle difference in the incidence of mucinous adenocarcinoma between young and old patients with CRC. However, stage I-III young patients had a similar disease-free survival period as the older patients. Other clinicopathologic characteristics, and tumor markers such as CEA, MMP-2, and p27(kip1), were also similar between young and old CRC patients.

Colorectal Cancer Liver Metastases – Understanding the Differences in the Management of Synchronous and Metachronous Disease

Introduction: Metastatic disease to the liver in colorectal cancer is a common entity that may present synchronously or metachronously. While increasing surgical experience has improved survival outcomes, some evidence suggest that synchronous lesions should be managed differently. This review aims to update current literature on differences between the outcomes and management of synchronous and metachronous disease. Materials and Methods: Systematic review of MEDLINE database up till November 2008. Results: Discrete differences in tumour biology have been identified in separate studies. Twenty-one articles comparing outcomes were reviewed. Definitions of metachronicity varied from anytime after primary tumour evaluation to 1 year after surgery for primary tumour. Most studies reported that synchronous lesions were associated with poorer survival rates (8% to 16% reduction over 5 years). Sixteen articles comparing combined vs staged resections for synchronous tumour showed comparable morbidity and mortality. Benefits over staged resections included shorter hospital stays and earlier initiation of chemotherapy. Suitability for combined resection depended on patient age and constitution, primary tumour characteristics, size and the number of liver metastases, and the extent of liver involvement. Conclusions: Surgery remains the only treatment option that offers a chance of long-term survival for patients amenable to curative resection. Synchronicity suggests more aggressive disease although a unifying theory for biological differences explaining the disparity in tumour behaviour has not been found. Combined resection of primary tumour and synchronous metastases is a viable option pending careful patient selection and institutional experience. Given the current evidence, management of synchronous and metachronous colorectal liver metastases needs to be individualised to the needs of each patient. Key words: Colorectal neoplasms, Liver neoplasms, Neoplasm metastasis, Synchronous Cancer, Metachronous cancer

Additive inhibition of colorectal cancer cell lines by aspirin and bortezomib

PURPOSE

To investigate the effect of cyclooxygenase-2 (Cox-2) inhibitor aspirin (acetylsalicylic acid, ASA) and proteasome inhibitor bortezomib in the proliferation and apoptosis of colorectal cancer cell lines.

METHODS

MTT assay, trypan blue exclusion and DNA fragmentation have been used to investigate cell proliferation and apoptosis in the presence of drugs. For the determination of Cox activity a colorimetric method was used. Western blotting was used for the measurement of the effect of the drugs in different proteins expression.

RESULTS

Bortezomib together with aspirin inhibit the growth of colorectal cancer cell lines HCT116, HT-29, and CaCo2 more than each drug alone. In the first two cell lines ASA inhibitory effects are Cox-2 independent because HCT116 cells do not express the enzyme while in HT-29 cells, Cox-2 has no activity as shown by a Cox activity assay. In CaCo2 cells that express enzymatically active Cox-2 this activity is inhibited by ASA. ASA is also able to suppress the increase in Cox-2 activity induced by bortezomib in these cells. Cell cycle inhibitors p21 and p27 are induced in the three cell lines by bortezomib and the combination treatment. Akt1 kinase is down-regulated in all three lines by the same treatments. Transcription factor NF-kappaB is retained in the cytoplasm by drug treatment in cell lines HCT116 and HT-29, a fact that may play a role in their pro-apoptotic activity. Pro-apoptotic bcl-2 family member, bad is down-regulated in cell lines HCT116 and CaCo2 by bortezomib treatment, a neoplasia-promoting event that is reversed by combination treatment.

CONCLUSION

The combination of bortezomib and ASA cooperates to decrease proliferation and induce apoptosis in three human colorectal cell lines with different genetic lesions. These effects are at least in some cases Cox-2 independent and involve common and diverse mechanisms in the three lines.

Slow proliferation as a biological feature of colorectal cancer metastasis

Background:

We have recently reported an inverse relationship between colon cancer progression and tumour proliferative activity. Here, we extend our findings by evaluating the proliferative activity of liver metastatic lesions and primary colorectal cancers (CRC) that differ in their metastatic potential.

Methods:

Using an earlier established multi-gene proliferation signature (GPS), proliferative levels were analysed in 73 primary CRCs and 27 liver metastases.

Results:

Compared with primary CRCs, we observed a significantly lower expression of the GPS in liver metastases and confirmed their lower proliferative levels by quantitative RT–PCR and Ki-67 immunostaining. No difference could be detected in apoptotic indices as assessed by M30 immunostaining, indicating that the net growth rate is lower in metastases relative to primary tumours. Notably, relapsed primaries or those with established metastases had significantly lower proliferative activity than CRCs that were non-metastatic and did not relapse.

Conclusion:

Our results suggest that slow proliferation is a biological characteristic of both liver metastases and those primary tumours with the ability to metastasise. The delineation of the mechanisms underlying the inverse association between proliferation and CRC aggressiveness may be important for the development of new therapeutic strategies.

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.

Cyclin D1 and p27 expression as prognostic factor in papillary carcinoma of thyroid: association with clinicopathological parameters

AIM

To determine the prognostic value of cell cycle regulators cyclin D1 and p27 for papillary thyroid carcinomas.

METHODS

Analysis included 180 patients with papillary thyroid carcinoma who underwent surgery at Split University Hospital Center between 1999 and 2001. Clinical data were obtained from clinical charts and histopathology reports. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissue by antibody p27 and cyclin D1. Quantification was based on the intensity and distribution of nuclear staining.

RESULTS

Univariate analysis showed that sex (P=0.019) and capsular invasion (P=0.010) were significant predictors of lymph node metastases, whereas age (P=0.96), histopathological variant (P=0.075), size (P=0.556) and multifocality (P=0.131) were not. Univariate analysis also showed that overexpression of cyclin D1 (P<0.001) and underexpression of p27 (P<0.001) predicted lymph node metastases in papillary thyroid carcinomas. There was a significant correlation between cyclin D1 (P=0.024) and p27 (P=0.029) expression in two prognostic groups of low and high risk. Low risk group was cyclin D1 negative and p27 positive, while high risk group was cyclin D1 positive and p27 negative. Multivariate analysis confirmed that sex (P=0.041), capsular invasion (P=0.027), and p27 (P<0.001) were strong independent predictors of lymph node metastases in the high-risk group.

CONCLUSIONS

Immunohistochemical analysis of p27 expression may be a valuable tool for identifying risk of lymph node metastases and more aggressive behavior of papillary thyroid carcinoma.

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.

Genetic deficiency of decorin causes intestinal tumor formation through disruption of intestinal cell maturation

Decorin is a member of the small leucine-rich proteoglycan gene family and plays an important role in suppressing cancer cell growth and metastasis. To elucidate the importance of decorin in intestinal carcinogenesis, a decorin-deficient (Dcn(-/-)) mouse model was employed. We found that targeted inactivation of decorin was sufficient to cause intestinal tumor formation with 30% of the Dcn(-/-) mice developing intestinal tumors with no other chemical or genetic initiation. Moreover, a high-risk diet amplified and accelerated the tumors initiated by decorin deficiency. Further, tumorigenesis in Dcn(-/-) mice was associated with disruption of intestinal maturation, including decreased cell differentiation and increased proliferation, which were linked to the downregulation of p21(WAF1/cip1), p27(kip1), intestinal trefoil factor and E-cadherin and to the upregulation of beta-catenin signaling. In addition, we found that decorin was highly expressed in the differentiated area of human normal colonic mucosa, but was dramatically reduced in paired colorectal cancer tissues. Taken together, our data demonstrate that decorin acts as a tumor suppressor gene and plays an important role in the maintenance of cell maturation and therefore homeostasis in the intestinal tract.

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.

p27kip1 deficiency impairs G2/M arrest in response to DNA damage, leading to an increase in genetic instability

p27(kip1) is a cyclin-dependent kinase inhibitor and a tumor suppressor. In some tumors, p27 suppresses tumor growth by inhibition of cell proliferation. However, this is not universally observed, implying additional mechanisms of tumor suppression by p27. p27-deficient mice are particularly susceptibility to genotoxin-induced tumors, suggesting a role for p27 in the DNA damage response. To test this hypothesis, we measured genotoxin-induced mutations and chromosome damage in p27-deficient mice. Both p27(+/-) and p27(-/-) mice displayed a higher N-ethyl-N-nitrosourea-induced mutation frequency in the colon than p27(+/+) littermates. Furthermore, cells from irradiated p27-deficient mice exhibited a higher number of chromatid breaks and showed modestly increased micronucleus formation compared to cells from wild-type littermates. To determine if this mutator phenotype was related to the cell cycle-inhibitory function of p27, we measured cell cycle arrest in response to DNA damage. Both normal and tumor cells from p27-deficient mice showed impaired G(2)/M arrest following low doses of ionizing radiation. Thus, p27 may inhibit tumor development through two mechanisms. The first is by reducing the proliferation of cells that have already sustained an oncogenic lesion. The second is by transient inhibition of cell cycle progression following genotoxic insult, thereby minimizing chromosome damage and fixation of mutations.

Pathogenesis of colorectal carcinoma and therapeutic implications: the roles of the ubiquitin-proteasome system and Cox-2

Pathways of the molecular pathogenesis of colorectal carcinoma have been extensively studied and molecular lesions during the development of the disease have been revealed. High up in the list of colorectal cancer lesions are APC (adenomatous polyposis coli), K-ras, Smad4 (or DPC4-deleted in pancreatic cancer 4) and p53 genes. All these molecules are part of important pathways for the regulation of cell proliferation and apoptosis and as a result perturbation of these processes lead to carcinogenesis. The ubiquitin-proteasome system (UPS) is comprised of a multi-unit cellular protease system that regulates several dozens of cell proteins after their ligation with the protein ubiquitin. Given that among these proteins are regulators of the cell cycle, apoptosis, angiogenesis, adhesion and cell signalling, this system plays a significant role in cell fate and carcinogenesis. UPS inhibition has been found to be a pre-requisite for apoptosis and is already clinically exploited with the proteasome inhibitor bortezomib in multiple myeloma. Cyclooxygenase-2 (Cox-2) is the inducible form of the enzyme that metabolizes the lipid arachidonic acid to prostaglandin H2, the first step of prostaglandins production. This enzyme is up-regulated in colorectal cancer and in several other cancers. Inhibition of Cox-2 by aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) has been found to inhibit proliferation of colorectal cancer cells and in epidemiologic studies has been shown to reduce colon polyp formation in genetically predisposed populations and in the general population. NSAIDs have also Cox-independent anti-proliferative effects. Targeted therapies, the result of increasingly understanding carcinogenesis in the molecular level, have entered the field of anti-neoplastic treatment and are used by themselves and in combination with chemotherapy drugs. Combinations of targeted drugs have started also to be investigated. This article reviews the molecular pathogenesis of colorectal cancer, the roles of UPS and Cox-2 in it and puts forward a rational for their combined inhibition in colorectal cancer treatment.

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.

Downregulation of the Cyclin-Dependent Kinase Inhibitor p27kip1 Might Correlate with Poor Disease-Free and Overall Survival in Inflammatory Breast Cancer

PURPOSE

The objective of this study was to evaluate whether p27kip1 downregulation is a prognostic factor in patients with inflammatory breast carcinoma (IBC).

PATIENTS AND METHODS

Fifty-eight patients with IBC were treated between January 1994 and July 2002. Median age was 49 years. Thirty-eight patients had baseline biopsy specimens. Patients received preoperative chemotherapy with FAC (5-fluorouracil/doxorubicin/cyclophosphamide; 34%) or FAC followed by a taxane (66%). All patients underwent mastectomies. All patients received radiation therapy and hormonal treatment when indicated. Expression level of p27kip1 was evaluated by indirect immunoperoxidase procedure. The p27kip1 was considered downregulated if nuclear staining was present in < 50% of the neoplastic cells.

RESULTS

Thirty-two patients (84%) had p27kip1-downregulated tumors, and 6 patients (17%) had p27kip1-normal tumors. Six patients (16%) exhibited a pathologic complete response. At a median follow-up of 43 months, 25 recurrences (66%) and 27 deaths (71%) occurred. Patients with p27kip1-downregulated tumors had fewer pathologic complete responses (9% vs. 50%; P = 0.03) and had lower 4-year recurrence-free survival (23% vs. 83%; P = 0.03) and overall survival rates (36% vs. 83%; P = 0.01).

CONCLUSION

The p27kip1 deregulation manifested by low protein cellular concentration might represent an adverse prognostic marker in IBC and could provide a valuable tool for selecting treatment for this aggressive disease.

p27 downregulation and metallothionein overexpression in gastric cancer patients are associated with a poor survival rate

BACKGROUND AND OBJECTIVES

As a significant number of curatively treated gastric cancer patients will ultimately relapse, there is an urgent need to investigate new prognostic markers for identification of high-risk patients. In this study, we investigated the possible role of molecular markers involved in cell cycle regulation (B1 and D3 cyclins, and p27) and cell protection (metallothionein, MT) in predicting tumor behavior and clinical outcome in gastric cancer patients.

METHODS

Analysis of the above indicators was performed by immunohistochemistry on 73 gastric cancer patient samples and 25 normal gastric mucosa specimens.

RESULTS

Normal gastric mucosa cells displayed low expressions of B1 and D3 cyclins and MT, and intense p27 staining. Conversely, gastric tumor cells showed higher cyclin D3 and MT, and lower p27 expressions. B1 cyclin expressions were not different between normal and tumor tissue. p27 and MT expressions were altered in almost all cancer samples, and were strongly correlated with tumor progression. Advanced extent of the primary tumor, nodal metastasis, low p27, and high MT expressions were the best combination of variables for prediction of poor clinical outcome. Each marker predicted outcome better than staging based on tumor-node (TNM) system. Survival and recurrence rates decreased as molecular alterations increased. Finally, molecular profile determination correctly predicted the prognosis in patients with same TNM stage.

CONCLUSIONS

p27 and MT expressions strongly correlated with clinical outcome allowing to identify an unfavorable group of patients that may benefit from tailored treatments. The role of B1 and D3 cyclins in gastric cancer remains to be elucidated.

Proliferation and Cdk4 expression in microsatellite unstable colon cancers with TGFBR2 mutations

Approximately 15% of human colon cancers have microsatellite instability (MSI) and carry frameshift mutations in a polyadenine tract (BAT-RII) in the type II transforming growth factor beta (TGF-beta) receptor (TGFBR2), a required component of the TGF-beta receptor. The BAT-RII mutations in MSI colon cancers make the tumors resistant to the effects of TGF-beta. In cultured epithelial cells, TGF-beta can inhibit cell proliferation and induce apoptosis, and in vitro it can regulate the expression of a variety of cyclins, cyclin-dependent kinases (cdks) and cdk inhibitors. These effects are context- and tissue type-dependent, raising questions about which of these in vitro effects of TGF-beta signaling inactivation contribute to the formation of primary colon cancer. Thus, this study sought to determine the pathogenetically relevant effects of TGFBR2 inactivation in primary MSI colon cancers with mutant BAT-RII. Colon cancers with mutant BAT-RII were found to have increased proliferation compared to cancers with wild-type BAT-RII. Assessment of cdk4, cyclin D1 and p27(kip1) expression revealed that only cdk4 expression was increased in the cancers with mutant BAT-RII. In order to determine if TGFBR2 inactivation was the cause of these changes, TGFBR2 was reconstituted in an MSI colon cancer cell line, resulting in decreased proliferation and decreased cdk4 expression and kinase activity. These results suggest that TGFBR2 mutations in primary colon cancers may be responsible for the increased proliferation and cdk4 expression in these tumors and provide evidence that deregulation of cdk4 is a pathogenic in vivo consequence of TGFBR2 inactivation in primary colon cancer.

p27kip1 in intestinal tumorigenesis and chemoprevention in the mouse

Targeted inactivation of p27(kip1) was sufficient for intestinal tumor formation in mice, but this was strictly a function of diet: tumors formed in p27(+/-) or p27(-/-) mice fed control AIN-76A diet and were increased by a western-style diet but did not develop in mice fed standard chow diet. When crossed with the Apc1638N(+/-) mouse, Apc(+/-),p27(+/-) or Apc(+/-),p27(-/-) mice not only formed twice as many tumors than the sum of the tumors from mutation at either locus alone, but on AIN76A diet also developed intestinal intussusception, a tumor-associated pathology in patients leading to intestinal blockage that has not been reported for intestinal cancer in mouse models. Moreover, the frequency of intussusception was increased when the compound mutant mice were maintained on the western diet, leading to early death. Despite this more aggressive tumor phenotype generated by inactivation of p27 than by inactivation of another cyclin-dependent kinase inhibitor, p21(WAF1/cip1), the nonsteroidal anti-inflammatory drug sulindac was still effective in inhibiting intestinal tumor formation in Apc(+/-),p27(+/-) or Apc(+/-),p27(-/-) mice, which contrasts with the abrogation of the effects of sulindac in Apc(+/-),p21(+/-) or Apc(+/-),p21(-/-) mice, indicating that p27 is not necessary for tumor inhibition by sulindac. Furthermore, tumor inhibition by sulindac was linked to the induction of p21 expression by the drug, regardless of p27 status, leading to suppression of cell proliferation and promotion of cell differentiation and apoptosis in the intestinal mucosa.

The tumor suppressors Ink4c and p53 collaborate independently with Patched to suppress medulloblastoma formation

Recurrent genetic alterations in human medulloblastoma (MB) include mutations in the sonic hedgehog (SHH) signaling pathway and TP53 inactivation (approximately 25% and 10% of cases, respectively). However, mouse models of MB, regardless of their initiating lesions, generally depend upon p53 inactivation for rapid onset and high penetrance. The gene encoding the cyclin-dependent kinase inhibitor p18(Ink4c) is transiently expressed in mouse cerebellar granule neuronal precursor cells (GNPs) as they exit the cell division cycle and differentiate. Coinactivation of Ink4c and p53 provided cultured GNPs with an additive proliferative advantage, either in the presence or absence of Shh, and induced MB with low penetrance but with greatly increased incidence following postnatal irradiation. In contrast, mice lacking one or two functional Ink4c alleles and one copy of Patched (Ptc1) encoding the Shh receptor rapidly developed MBs that retained wild-type p53. In tumor cells purified from double heterozygotes, the wild-type Ptc1 allele, but not Ink4c, was inactivated. Therefore, when combined with Ptc1 mutation, Ink4c is haploinsufficient for tumor suppression. Methylation of INK4C (CDKN2C) was observed in four of 23 human MBs, and p18(INK4C) protein expression was extinguished in 14 of 73 cases. Hence, p18(INK4C) loss may contribute to MB formation in children.

Molecular analysis of the p27/kip1 gene in breast cancer

BACKGROUND

Genetic polymorphisms and mutations of the genes involved in tumorigenesis may determine individual susceptibility for cancer. The p27/Kip1 protein belongs to the family of cyclin-dependent kinase-inhibitory proteins, which are negative regulators of cell-cycle progression. Reduced protein levels of p27/Kip1 have been reported in numerous human cancers including breast cancer.

METHODS AND RESULTS

p27 gene mutations and the codon 109 polymorphism were investigated in breast cancer patients by single strand conformation polymorphism analysis, PCR-restriction fragment length polymorphism analysis and DNA sequencing. Mutations were identified in 2 of 24 breast tumor samples. One G-->A transition resulting in a silent mutation and a single base deletion resulting in a nonsense mutation were detected in one patient. Another breast cancer sample harbored a T-->A transition at codon 159. An association between the codon 109 B allele and breast cancer was observed.

CONCLUSION

Our study indicates that mutational alterations in the p27 gene are rare in human breast cancer. The codon 109 B allele is associated with high-grade tumors.

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.

Cyclin-dependent kinase (cdk6) and p16 in pancreatic endocrine neoplasms

AIMS

p16 and p27, the inhibitors of cyclin-dependent kinases, have been reportedly decreased in certain human tumours, including a few endocrine tumours. The current study used immunocytochemical staining to compare the staining intensity of cdk6 and its inhibitor, p16, in pancreatic endocrine neoplasms with normal pancreatic islets.

METHODS

Twenty-four primary pancreatic endocrine neoplasms, consisting of 12 insulinomas, one glucagomoma, three pancreatic polypeptide (PP)-omas, five gastgrinomas and three non-fuctioning tumours, were immunocytochemically studied for cdk6 and p16 compared with the adjacent non-neoplastic islets.

RESULTS

In the normal islets, cdk6 staining was strongly positive for islet cell nuclei and cytoplasms, whereas p16 was strongly positively stained for islet cell cytoplasms. Insulinomas, glucagonoma, PP-omas and non-functioning tumours were weakly stained for cdk6 and p16. Among five gastrinomas, three tumours were moderately stained and two tumours were more weakly stained for cdk6 and p16. Thus, tumour cells were weaker stained for cdk6 and p16 compared with the strong staining of normal islet cells. No distinct immunostaining difference was observed among five kinds of pancreatic endocrine neoplasms.

CONCLUSIONS

The decreased immunocytochemical staining for cdk6 and p16 is consistently observed in five kinds of pancreatic endocrine neoplasms. This decreased cdk6 and p16 in pancreatic endocrine neoplasms may be a part of the cell cycle event in tumour transformation and progression, and the same process may involve other endocrine tumours.

Altered expression of cyclins and cell cycle inhibitors in papillary thyroid cancer: prognostic implications

Currently we lack biochemical or molecular markers that predict recurrence and metastases in thyroid cancer. Recent studies in a number of other human malignancies indicate that expression and/or subcellular localization of certain cell cycle regulators has prognostic utility. We have investigated the expression of cyclins D1 and E and of cyclin-dependent kinase inhibitor's p21 and p27 in papillary thyroid cancer (PTC) and correlated this with clinical/histological stage at diagnosis and with clinical outcome. PTCs were compared to normal thyroid, adenomas, and undifferentiated thyroid cancers (UTCs). Our studies indicate that PTCs and UTCs demonstrate low nuclear expression of cyclin E and p27, allowing a clear distinction between adenomas and these carcinomas (p < 0.004). A pattern of low nuclear expression of all four markers was observed in stage IV PTCs and UTCs, while stage I PTCs had low D1 and E accompanied by high p21 or p27. Expression of cytoplasmic cyclin D1 was significantly lower in stage IV PTCs and UTCs than in stage I-III PTC's (p </= 0.020), and appeared to correlate inversely with poor outcome in PTCs (p = 0.010). These studies suggest that evaluation of a panel of these markers and attention to their subcellular localization may be a useful adjunct in differentiating benign from malignant thyroid neoplasms and in predicting tumor behavior.

Clinico-prognostic value of D-type cyclins and p27 in laryngeal cancer patients: a review

Despite recent improvements in surgical and radiation therapy, failures still occur in patients with laryngeal squamous cell carcinomas, which may have a very different clinical outcome even when their clinical and histopathological characteristics are similar. The apparent inadequacy of "traditional" prognostic factors in predicting the clinical evolution of laryngeal squamous cell carcinomas has led to attempts to develop additional markers capable of distinguishing patients with a good prognosis from those who are more likely to relapse. A number of studies have demonstrated a relationship between tumourigenesis and alterations in the expression of cyclins, cyclin-dependent kinases and cyclin-dependent kinase inhibitors, but the data regarding laryngeal squamous cell carcinomas are somewhat conflicting. Herein a review is made of the published literature concerning the clinico-prognostic role of cyclin D1, D3 and p27, and personal data are described concerning laryngeal squamous cell carcinoma patients who underwent surgical resection at the ENT Department of the University of Milan. The results of our multivariate analyses demonstrated that cyclin D1, p27 and cyclin D3 overexpression are statistically significant predictors of disease-free survival (p = 0.0238, p = 0.0001 and p = 0.0217, respectively); the statistical correlation with overall survival was significant in the case of p27 (p = 0.0009) and cyclin D3 (p = 0.0189), and borderline in the case of cyclin D1 (p = 0.0622). In relation to cyclin D1/p27 coexpression, the patients with a cyclin D1-/p27+ phenotype showed the best prognosis, those with a cyclin D1/p27+ or cyclin D1-/p27- phenotype, an intermediate prognosis, and those with a cyclin D1+/p27- phenotype, the poorest prognosis (p = 0.0001 and p = 0.0001 for trend for disease-free survival; p = 0.0015 and p = 0.0008 for trend for overall survival). In the case of cyclin D1/cyclin D3 coexpression, the patients with cyclin D1+/cyclin D3+ tumours had the poorest overall survival, those with cyclin D1/cyclin D3+or cyclin D1+/cyclin D3- tumours showed intermediate course, and those with cyclin D1 /cyclin D3- tumours had the most favourable outcome (p = 0.0002). The findings of this review indicate that both types of cyclin D and p27 are involved in the genesis of laryngeal squamous cell carcinomas, and that immunohistochemical evaluations of biopsy samples may provide useful additional markers capable of identifying subgroups of patients with a poor prognosis who can be treated by means of more aggressive surgery, adjuvant radiotherapy and chemotherapy, as well as those requiring a closer and more prolonged follow-up. Finally, preliminary results suggest that the administration of new molecular therapies that exert their antitumoural activities by functionally subverting the pathways regulated by D-type cyclins and their cyclin-dependent kinase counterparts may represent a further therapeutic modality for patients with refractory head and neck squamous cell carcinomas [corrected]

Skp2 and p27kip1 expression in melanocytic nevi and melanoma: an inverse relationship

BACKGROUND

S-phase kinase associated protein-2 (Skp2) ubiquitin ligase p45(SKP2) is important in the degradation of p27kip1 (a cyclin dependent kinase inhibitor) and progression through the G1-S cell-cycle checkpoint. Low levels of p27 and high levels of Skp2 are related to poor prognosis in some cancers.

METHODS

Clinicopathologic features and immunohistochemical expression of Skp2 and p27kip1 were investigated in 198 melanocytic proliferations: 21 melanocytic nevi, 23 melanoma in situ, 119 primary melanoma, and 35 metastatic melanoma samples. Comparative and survival analyses were performed.

RESULTS

Progressive and significant increases and decreases in the nuclear expression of Skp2 and p27kip1, respectively, was identified moving from melanocytic nevi (0.05 +/- 0.2/85 +/- 15) to melanoma in situ (3 +/- 2/45 +/- 20) to primary cutaneous melanoma (12 +/- 9/30 +/- 25) to metastatic melanoma (25 +/- 15/15 +/- 20) (p < or = 0.006). Expression of these proteins also significantly correlated with increasing American Joint Committee on Cancer (AJCC) T (tumor) classification and AJCC stage (p < or = 0.01). Moreover, the level of these two proteins exhibited a significant inverse relationship (r = -0.4, p = 0.0001). Skp2 cytoplasmic labeling index of >20% predicted worse 10-year overall survival (38% vs. 86%, p = 0.04) in primary melanoma. Neither p27 nor Skp2 nuclear expression impacted significantly on prognosis.

CONCLUSIONS

Gain of Skp2 and loss of p27kip1 protein expression are implicated in melanoma progression where the level of p27kip1 may be regulated by targeted proteolysis via Skp2. Cytoplasmic expression of Skp2 defines a subset of aggressive melanomas and could represent another pathway of deregulation of the cell cycle.

Overexpression of cyclin D1 and interaction between p27Kip1 and tumour thickness predict lymph node metastases occurrence in lower lip squamous cell carcinoma

We have attempted to identify those subgroups of patients most likely to develop lymph node metastases from squamous cell carcinoma of the lower lip (LLSSC). A total of 97 subjects, who did not undergo elective neck dissection, were recruited into the 60-month disease-free survival study. After univariate analysis, tumour size, histological grading, maximal thickness, perineural invasion and immunoreactivity to cyclin D1 and p27Kip1 proteins proved to be significant factors. Tests of the effect of interaction between p27Kip1 LI and tumour thickness yielded that the impact of tumour thickness on the risk of lymph node metastases was modified by the percentage of p27Kip1 positive cells. Subsequent to models of multivariate analysis, tumour size, positive cyclin D1 protein expression, maximal thickness (> 5 mm), p27Kip1 LI (%) and the interaction term between p27Kip1 LI and tumour thickness retained strong independent predictive values for lymph node metastases. We suggest that immunohistochemistry for cyclin D1 and p27Kip1 may prove to be valuable ancillary tests for identifying LLSSC with metastatic potential.

p27(Kip1)-stathmin interaction influences sarcoma cell migration and invasion

Emerging evidences suggest that cyclin-dependent kinase inhibitors (CKIs) can regulate cellular functions other than cell cycle progression, such as differentiation and migration. Here, we report that cytoplasmic expression of p27(kip1) affects microtubule (MT) stability following cell adhesion on extracellular matrix (ECM) constituents. This p27(kip1) activity is due to its ability to bind and impair the function of the MT-destabilizing protein stathmin. Accordingly, upregulation of p27(kip1) or downregulation of stathmin expression results in the inhibition of mesenchymal cell motility. Moreover, high stathmin and low cytoplasmic p27(kip1) expression correlate with the metastatic phenotype of human sarcomas in vivo. This study provides a functional link between proliferation and invasion of tumor cells based on diverse activities of p27(kip1) in different subcellular compartments.

Orthotopic implantation of human hepatocellular carcinoma in mice: analysis of tumor progression and establishment of the BCLC-9 cell line

PURPOSE

To allow the longitudinal investigation of molecular events associated with the progression of human hepatocellular carcinoma (HCC), we sought to develop a murine model by orthotopic implantation of tumor fragments obtained from patients diagnosed at early stage.

EXPERIMENTAL DESIGN

Tumor pieces (2 x 2 mm) were implanted on the liver surface of nu/nu mice. After xenograft growing, subsequent passages were performed to achieve long-term implant viability. Isolation of tumoral hepatocytes was done to establish new cell lines. HCC characteristics, proliferation rate, apoptotic index (terminal deoxynucleotidyl transferase-mediated nick end labeling), and expression of cell-cycle regulators (cyclins E and A, p21(Cip1), p27(Kip1), p16(INK4a), pRb, and p53) were assessed by Western Blot and immunohistochemistry, to correlate them with tumor progression.

RESULTS

Five (50%) of the 10 primary HCCs resulted in small slow-growing liver implants. Three of them are viable after 48 months, whereas the remaining two survived for 15 and 13 months. Xenografts throughout passages exhibited a more aggressive phenotype with a poorer degree of differentiation, intense proliferation, moderate apoptosis, cell-cycle deregulation, p53 alterations, microvascular invasion, and dissemination. In one single passage, we observed critical growth delay, which was associated with significant p27(kip1) overexpression. We established the anchor-free growing BCLC-9 cell line from one xenograft. This has gains of chromosomes 7, 5p, 6q, and 9q, is hepatitis B virus-DNA positive, does not secrete alpha-fetoprotein, and has TP53 missense mutations in codons 192 and 242.

CONCLUSIONS

The orthotopic implantation of early HCC fragments in nude mice provides a useful model to investigate the mechanisms of human HCC evolution and to establish new cell lines.