Prognostic significance of p53 overexpression and mutation in colorectal adenocarcinomas

NO news: S-(de)nitrosylation of cathepsins and their relationship with cancer

Tumor formation and progression have been much of a study over the last two centuries. Recent studies have seen different developments for the early diagnosis and treatment of the disease; some of which even promise survival of the patient. Cysteine proteases, mainly cathepsins have been unequivocally identified as putative worthy players of redox imbalance that contribute to the premonition and further progression of cancer by interfering in the normal extracellular and intracellular proteolysis and initiating a proteolytic cascade. The present review article focuses on the study of cancer so far, while establishing facts on how future studies focused on the cellular interrelation between nitric oxide (NO) and cancer, can direct their focus on cathepsins. For a tumor cell to thrive and synergize a cancerous environment, different mutations in the proteolytic and signaling pathways and the proto-oncogenes, oncogenes, and the tumor suppressor genes are made possible through cellular biochemistry and some cancer-stimulating environmental factors. The accumulated findings show that S-nitrosylation of cathepsins under the influence of NO-donors can prevent the invasion of cancer and cause cancer cell death by blocking the activity of cathepsins as well as the major denitrosylase systems using a multi-way approach. Faced with a conundrum of how to fill the gap between the dodging of established cancer hallmarks with cathepsin activity and gaining appropriate research/clinical accreditation using our hypothesis, the scope of this review also explores the interplay and crosstalk between S-nitrosylation and S-(de)nitrosylation of this protease and highlights the utility of charging thioredoxin (Trx) reductase inhibitors, low-molecular-weight dithiols, and Trx mimetics using efficient drug delivery system to prevent the denitrosylation or regaining of cathepsin activity in vivo. In foresight, this raises the prospect that drugs or novel compounds that target cathepsins taking all these factors into consideration could be deployed as alternative or even better treatments for cancer, though further research is needed to ascertain the safety, efficiency and effectiveness of this approach.

Making Connections: p53 and the Cathepsin Proteases as Co-Regulators of Cancer and Apoptosis

Simple Summary

This article describes an emerging area of significant interest in cancer and cell death and the relationships shared by these through the p53 and cathepsin proteins. While it has been demonstrated that the p53 protein can directly induce the leakage of cathepsin proteases from the lysosome, directly triggering cell death, little is known about what factors set the threshold at which the lysosome can become permeabilized. It appears that the expression levels of cathepsin proteases may be central to this process, with some of them being transcriptionally regulated by p53. The consequences of such a mechanism have serious implications for lysosomal-mediated apoptosis and have significant input into the design of therapeutics and their strategic use. In this review, we highlight the importance of extending such findings to other cathepsin family members and the need to assess the roles of p53 isoforms and mutants in furthering this mechanism.

Abstract

While viewed as the “guardian of the genome”, the importance of the tumor suppressor p53 protein has increasingly gained ever more recognition in modulating additional modes of action related to cell death. Slowly but surely, its importance has evolved from a mutated genetic locus heavily implicated in a wide array of cancer types to modulating lysosomal-mediated cell death either directly or indirectly through the transcriptional regulation of the key signal transduction pathway intermediates involved in this. As an important step in determining the fate of cells in response to cytotoxicity or during stress response, lysosomal-mediated cell death has also become strongly interwoven with the key components that give the lysosome functionality in the form of the cathepsin proteases. While a number of articles have been published highlighting the independent input of p53 or cathepsins to cellular homeostasis and disease progression, one key area that warrants further focus is the regulatory relationship that p53 and its isoforms share with such proteases in regulating lysosomal-mediated cell death. Herein, we review recent developments that have shaped this relationship and highlight key areas that need further exploration to aid novel therapeutic design and intervention strategies.

Overexpression of TP53 protein is associated with the lack of adjuvant chemotherapy benefit in patients with stage III colorectal cancer

TP53 mutations drive colorectal cancer development, with missense mutations frequently leading to accumulation of abnormal TP53 protein. TP53 alterations have been associated with poor prognosis and chemotherapy resistance, but data remain controversial. Here, we examined the predictive utility of TP53 overexpression in the context of current adjuvant treatment practice for patients with stage III colorectal cancer. A prospective cohort of 264 stage III patients was tested for association of TP53 expression with 5-year disease-free survival, grouped by adjuvant treatment. Findings were validated in an independent retrospective cohort of 274 stage III patients. Overexpression of TP53 protein (TP53+) was found in 53% and 52% of cases from the prospective and retrospective cohorts, respectively. Among patients receiving adjuvant chemotherapy, TP53+ status was associated with shorter disease-free survival (p ≤ 0.026 for both cohorts), while no difference in outcomes between TP53+ and TP53- cases was observed for patients treated with surgery alone. Considering patients with TP53- tumors, those receiving adjuvant treatment had better outcomes compared with those treated with surgery alone (p ≤ 0.018 for both cohorts), while no treatment benefit was apparent for patients with TP53+ tumors. Combined cohort-stratified analysis adjusted for clinicopathological variables and DNA mismatch repair status confirmed a significant interaction between TP53 expression and adjuvant treatment for disease-free survival (p_interaction = 0.030). For the combined cohort, the multivariate hazard ratio for TP53 overexpression among patients receiving adjuvant chemotherapy was 2.03 (95% confidence interval 1.41-2.95, p < 0.001), while the hazard ratio for adjuvant treatment among patients with TP53- tumors was 0.42 (95% confidence interval 0.24-0.71, p = 0.001). Findings were maintained irrespective of tumor location or when restricted to mismatch repair-proficient tumors. Our data suggest that adjuvant chemotherapy benefit in stage III colorectal cancer is restricted to cases with low-level TP53 protein expression. Identifying TP53+ tumors could highlight patients that may benefit from more aggressive treatment or follow-up.

High Expression of Methylenetetrahydrofolate Dehydrogenase 2 (MTHFD2) in Esophageal Squamous Cell Carcinoma and its Clinical Prognostic Significance

Background

Recently, targeted therapy for malignant tumors has developed rapidly, but there is still no effective targeted therapy for advanced esophageal squamous cell carcinoma (ESCC). Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) is a key enzyme involved in folate metabolism and is closely related to the proliferation in many cancers. However, few studies have explored the expression of MTHFD2 in ESCC and its prognostic significance.

Material/Methods

The expressions of MTHFD2, ki67, and p53 in ESCC tissues were detected by immunohistochemistry. Further, MTHFD2 expression level in ESCC and its correlations with patients’ clinicopathological characteristics and survival prognosis were investigated.

Results

The enhanced expression of MTHFD2 was observed in ESCC specimens compared with adjacent normal tissue. The increased expression of MTHFD2 was closely related to pathological grading (P=0.020) and tumor TNM stage (P=0.019). In addition, patients with high expression of MTHFD2 had worse survival than those with low MTHFD2 expression (P<0.05). High expression of MTHFD2 in ESCC tissues was often associated with high expression of ki67 and p53 (P<0.05).

Conclusions

MTHFD2 had significantly enhanced expression in ESCC tissues and was associated with pathological grading and TNM stage. Taken together, high expression of MTHFD2 was an independent unfavorable prognostic parameter for overall survival (OS) of ESCC patients, suggesting that MTHFD2 might be a potential therapeutic target for ESCC in the future.

Mechanism of Apoptosis Induced by Curcumin in Colorectal Cancer

Colorectal cancer (CRC) is among the top three cancer with higher incident and mortality rate worldwide. It is estimated that about over than 1.1 million of death and 2.2 million new cases by the year 2030. The current treatment modalities with the usage of chemo drugs such as FOLFOX and FOLFIRI, surgery and radiotherapy, which are usually accompanied with major side effects, are rarely cured along with poor survival rate and at higher recurrence outcome. This trigger the needs of exploring new natural compounds with anti-cancer properties which possess fewer side effects. Curcumin, a common spice used in ancient medicine was found to induce apoptosis by targeting various molecules and signaling pathways involved in CRC. Disruption of the homeostatic balance between cell proliferation and apoptosis could be one of the promoting factors in colorectal cancer progression. In this review, we describe the current knowledge of apoptosis regulation by curcumin in CRC with regard to molecular targets and associated signaling pathways.

The expression of multiple proteins as prognostic factors in colorectal cancer: cathepsin D, p53, COX-2, epidermal growth factor receptor, C-erbB-2, and Ki-67

BACKGROUND/AIMS

A single gene mutation alone cannot explain the poor prognosis of colorectal cancer. This study aimed to establish a correlation between the expression of six proteins and the prognosis of colorectal cancer patients.

METHODS

Tissue samples were collected from 266 patients who underwent surgery for colorectal cancer at our institution from January 2006 to December 2007. The expression of six proteins were determined using immunohistochemical staining of specimens.

RESULTS

Cathepsin D, p53, COX-2, epidermal growth factor receptor, c-erbB-2, and Ki-67 expression were detected in 38.7%, 60.9%, 37.6%, 35.7%, 30.1%, and 74.4% of the samples, respectively. The expression of cathepsin D was significantly correlated with reduced cancer-free survival (p=0.036) and colorectal cancer-specific survival (p=0.003), but the other expression levels were not. In a multivariate analysis, cathepsin D expression was found to be an independent prognostic factor for poorer colorectal cancer-specific survival (hazard ratio, 8.55; 95% confidence interval, 1.07 to 68.49). Furthermore, patients with tumors expressing four or more of the proteins had a significantly decreased cancer-free survival rate (p=0.006) and colorectal cancer-specific survival rate (p=0.002).

CONCLUSIONS

Patients with cathepsin D positivity had a poorer outcome than patients who were cathepsin D-negative. Thus, cathepsin D may provide an indicator for appropriate intensive follow-up and adjuvant chemotherapy.

Mdm2 inhibition induces apoptosis in p53 deficient human colon cancer cells by activating p73- and E2F1-mediated expression of PUMA and Siva-1

Camptothecin (CPT) and Nutlin-3 caused apoptosis by increasing p53 protein and its activation in intestinal epithelial cells (IEC-6). We studied the effectiveness of these inducers on apoptosis in human colon cancer cells (Caco2) lacking p53 expression. CPT failed to activate caspase-3 and cause apoptosis in these cells. The absence of p53 expression, higher basal Bcl-xL and lower Bax proteins prevented CPT-induced apoptosis. However, the Mdm2 antagonist Nutlin-3 induced apoptosis in a dose dependent manner by activating caspases-9 and -3. Nutlin-3 prevented the activation of AKT via PTEN-mediated inhibition of the PI3K pathway. Nutlin-3 increased the phosphorylation of retinoblastoma protein causing E2F1 release leading to induction of Siva-1. Nutlin-3-mediated degradation of Mdm2 caused the accumulation of p73, which induced the expression of p53 up-regulated modulator of apoptosis (PUMA). E2F1 and p73 knockdown decreased the expression of Siva and PUMA, respectively and abolished Nutlin-3-induced caspase-3 activation. Cycloheximide (CHX) inhibited Nutlin-3-induced Siva, Noxa, and PUMA expression and inhibited apoptosis in IEC-6 and Caco2 cells. These results indicate that translation of mRNAs induced by Nutlin-3 is critical for apoptosis. In summary, apoptosis in Caco2 cells lacking functional p53 occurred following the disruption of Mdm2 binding with p73 and Rb leading to the expression of pro-apoptotic proteins, PUMA, Noxa, and Siva-1.

Prognostic significance of p53-expression in colorectal carcinoma as measured by a luminometric immunoassay

Background: Mutations of the TP53 gene induce the production of abnormal p53-protein with a prolonged half-life allowing its detection by monoclonal antibodies. In the following study we examined if elevated levels of p53 correlate with worse prognosis in colorectal cancer.

Methods: We have quantified the protein, using an immunoluminometric assay, in 144 cytosols of primary sporadic colorectal cancer tissues and in 96 specimen of normal mucosa.

Results: In 112 samples (77.8%) the p53-expression was higher than the cut-off-value of 0.15 ng p53 per mg total protein. Luminometric immunoassay did not correlate with various clinicopathological parameters. Follow-up ranged from 2.4 to 54.3 (mean 25.3) months. During this period, 61 patients developed recurrences of whom 39 died of the underlying disease. Neither univariate nor multivariate analysis showed any statistically significant differences in prognosis between high and low p53 expression.

Conclusion: Our investigation revealed that p53-overexpression as measured by a luminometric immunoassay, is not a useful predictor of prognosis in patients with colorectal adenocarcinoma. Overcoming the limit of semiquantitative immunohistochemistry for p53-protein quantitative immunoluminometry may be useful elucidating the relation between serum p53-antibodies and p53 in cytosols.

The predictive value of p53 and p33(ING1b) in patients with Dukes'C colorectal cancer

OBJECTIVE

Identification of biological markers that may predict response to chemotherapy would allow the individualization of treatment by enabling selection of patients most likely to benefit from chemotherapy. The aims of this study were to determine whether p53 mutation status and p53 and p33(ING1b) protein expression can predict which patients with Dukes' C colorectal cancer following curative surgical resection respond to adjuvant chemotherapy with 5-fluorouracil (5-FU).

METHOD

Patients with Dukes'C colorectal cancer (n = 41) were studied. DNA was extracted and analysed for p53 mutation using PCR-based direct DNA sequencing. Tumours were analysed for p53 protein expression by immunohistochemistry using DO-7 monoclonal antibody and for p33(ING1b) protein expression using GN1 monoclonal antibody.

RESULTS

There was a significant association between p53 mutation status analysed by gene sequencing and overall and metastasis-free survival (P = 0.03 and 0.004, respectively, log-rank test). By contrast, no significant correlation was found between p53 and p33(ING1b) protein expression and overall or metastasis-free survival.

CONCLUSION

In patients with Dukes'C colorectal cancer who underwent curative surgical resection of the primary tumour, followed by 5-FU-based adjuvant chemotherapy, p53 mutation status as assessed by gene sequencing is a significant predictor of overall and metastasis-free survival.

Relationship between VEGF and p53 expression and tumor cell proliferation in human gastrointestinal carcinomas

PURPOSE

The vascular endothelial growth factor (VEGF) and p53 play important roles in the growth of tumor. However, the relationship between the expression of VEGF and p53 and tumor cell proliferation in human gastrointestinal cancer remains unknown. In the present study, therefore, we have examined the relationship between VEGF and p53 expression and tumor cell proliferation in gastrointestinal carcinoma (GITC), as well as the association between these biomarkers and clinicopathological factors.

METHODS

Surgical specimens from 30 patients with GITC were examined for VEGF, p53, and proliferating cell nuclear antigen (PCNA) expression by immunohistochemical staining.

RESULTS

We found a predominant VEGF expression of moderate intensity in 16(54.84%) of 30 GITC cases, while p53 expression was mainly high in 13(45.16%) of 30 GITC cases. PCNA expression was high in 20(64.52%) of 30 GITC cases. Tumor size, infiltration, vascular invasion, and gastritis were significantly correlated with VEGF, p53, and PCNA expression. There was a significant correlation between VEGF and p53 expression (P = 0.0001), VEGF and PCNA expression (P = 0.00004), and between p53 expression and PCNA expression (P = 0.0016). When the VEGF and p53 expression, and PCNA expression were considered together, both VEGF and p53 expression were not significantly associated with PCNA. A significant correlation between the PCNA expression and the mitotic index (P = 0.0016) was also found.

CONCLUSION

These results demonstrate that VEGF and p53 expression are significantly correlated as independent prognostic factors with tumor cell proliferation, and might be associated with relevant events involved in gastrointestinal tumor biology.

Molecular pathological subclassification of mucinous adenocarcinoma of the colorectum

The purpose of the present report was to examine the possibility of molecular pathological subtyping of mucinous adenocarcinomas (MAC) of the colorectum. Thirty-five formalin-fixed and paraffin-embedded MAC specimens of the colorectum were analyzed. Genetic alterations of p53 gene and microsatellite instability (MSI) as well as immunohistochemical analysis of mucin subtypes (human gastric mucin (HGM), anti-mucin monoclonal antibody recognizing gastric gland mucous cells-1, MUC2, CD10) and expression levels of human mutL homolog 1 (hMLH1), p53 and Ki-67 were performed. According to MSI and p53 status, these tumors were subclassified into three groups: mutator-type tumors with a high frequency of MSI (20%), suppressor/p53-type tumors with p53 mutation, p53 overexpression or loss of heterozygosity of D17S250 (an adjacent locus to p53; 40%) and the unclassified tumors (40%). The suppressor/p53-type tumors had a significant association with distal colon location (P = 0.019), venous invasion (P = 0.002), extent of lymph node metastasis (P = 0.007) and higher tumor stage (P = 0.018). In contrast, mutator-type tumors had frequent expression of HGM (P = 0.005) and prominent lymphocytic infiltration at the advancing front of the tumor (P = 0.005). These results indicate that MAC of the colorectum could be subclassified according to molecular pathological background, reflecting distinct clinicopathological and phenotypic characteristics.

Determination of TP53 Mutation Is More Relevant Than Microsatellite Instability Status for the Prediction of Disease-Free Survival in Adjuvant-Treated Stage III Colon Cancer Patients

Purpose

Microsatellite instability (MSI), TP53 mutation, and KRAS mutation status have been reported as prognostic factors in colon cancer. Most studies, however, have included heterogeneous groups of patients with respect to cancer stage. We determined the prognostic relevance of high-frequency MSI (MSI-H), TP53 mutations, and KRAS mutations in a well-defined group of patients with stage III colon cancer (N = 391), randomly assigned for adjuvant treatment with fluorouracil-based chemotherapy.

Methods

Three hundred ninety-one tumor specimens were available. MSI was determined in 273 specimens, and mutation analyses of TP53 and KRAS were performed in 220 and 205 specimens, respectively.

Results

In a univariate analysis, MSI-H (44 of 273; 16%) was associated with a longer disease-free survival (DFS; P = .038), but in a multivariate model adjusting for nodal involvement, histology, invasion, and grade of tumor, the association of MSI status with DFS did no longer reach statistical significance, though the risk estimate for microsatellite stability versus MSI-H tumors did not change much. Mutant TP53, found in 116 (53%) of 220 tumors, was associated with a shorter DFS, both in univariate (P = .009) and multivariate analyses (P = .018), whereas KRAS mutations (58 of 205; 28%) did not show any prognostic significance.

Conclusion

Both mutant TP53 and MSI-H seem to be prognostic indicators for disease-free survival, but only TP53 retains statistical significance after adjusting for clinical heterogeneity. Thus, in adjuvantly treated patients with stage III colon cancer, presence or absence of a TP53 mutation should be considered as a better predictor for DFS than MSI status.

p53 alterations in colon tumors: a comparison of SSCP/sequencing and immunohistochemistry

This study compares single-strand conformation polymorphism (SSCP)/sequencing and immunohistochemistry (IHC) in a population-based colon cancer study to determine the best methods to evaluate p 53 alterations in tumors. Epidemiologic data collected from the Utah portion of a multicenter case-control study of colon cancer (n = 268) was used to compare somatic p53 mutations detected using SSCP/sequencing of exons 5 through 8 with those with p53 protein overexpression detected by IHC. A total of 136 tumors (51%) had p 53 mutations identified using SSCP/sequencing. IHC detected 164 tumors (61%) with protein overexpression (using a cut point of > or =20% positive cells) and 142 tumors (53%) when > or =50% positive cells were used. Sensitivity of IHC (> or =20% level) using SSCP/sequencing as the reference method was 85%. Specificity of IHC (> or =20% level) using SSCP/sequencing as reference was 63%. When > or =50% positive cells were used, specificity increased to 77%. Associations with age, gender, tumor site, stage, and Ki-ras were similar for both methods. An inverse relationship between microsatellite instability and p 53 was detected with the higher threshold for IHC positivity and SSCP/sequencing. SSCP/sequencing was able to discriminate between mutated p 53 and wild-type p 53 when evaluating dietary associations whereas IHC was not able to discriminate between these tumor types. Using a level of 50% or more positive cells increases specificity relative to sensitivity in comparison with lower staining levels, and is comparable with sequencing in its ability to detect an inverse relationship with the MSI. Advantages gained by sequencing are its ability to examine specific mutations and the improved ability to discriminate between cases with p 53 mutation and wild type when evaluating associations.

Thrombospondin-1 expression in relation to p53 status and VEGF expression in human breast cancers

The aim of the present study was to study the expression and relationship of potential angiogenic factors. Paraffin-embedded tumour sections from 261 breast cancer patients were stained immunohistochemically for thrombospondin (TSP-1) expression. p53 status was previously determined by cDNA-based sequencing, and vascular endothelial growth factor (VEGF) protein expression had been previously analysed using an immunoassay. 241 cancers (92%) had detectable levels of TSP-1. No associations between TSP-1 and p53 status or VEGF were found. No correlations between TSP-1 and relapse-free (P=0.3), breast cancer-corrected (P=0.2) or overall survival (P=0.5) were found. A correlation was found for patients with p53 mutations, but negative p53 expression, with higher VEGF levels (P=0.009), but there was no correlation between this p53 group and those with low TSP-1 levels (P=0.2). In conclusion, TSP-1 expression was not prognostic and was not associated with neither p53-status or VEGF expression.

Genetic Alterations in Locally Advanced Stage II/III Colon Cancer: A Search for Prognostic Markers

Heterogeneity in advanced colon cancer leads to different results from adjuvant chemotherapy. To identify groups of patients who may need adjuvant treatment, molecular staging and correlation with clinical data may be helpful in classifying histologically similar tumors. Colon cancer develops through a multistep process with an accumulation of multiple genetic alterations that are often the cause of a form of genomic instability. The 2 best known mechanisms of genomic instability are chromosomal instability (CIN) and microsatellite instability (MSI). The CIN phenotype is found in approximately 85% of sporadic colon cancers and is characterized by aneuploidy, multiple chromosomal rearrangements, and an accumulation of somatic mutations in oncogenes such as K-ras and tumor suppressor genes such as TP53 and APC. The MSI phenotype is associated with small insertions and deletions mainly in repetitive sequences (microsatellites) and is found in approximately 15% of cases. This instability, often referred to as high-frequency MSI (MSI-H), is caused by defects of the mismatch repair system, which is involved in repairing DNA errors that arise during DNA replication. Clear-cut correlations between the somatic genetic alterations in tumors and the clinical behavior of the tumor are rare. Only a few markers, such as MSI-H and TP53, seem to have a prognostic value. Mutations in the TP53 gene are associated with an aggressive tumor growth and subsequent reduced survival, whereas MSI-H seems to be correlated with a favorable outcome. In general, predicting biologic behavior of in particular stage III colon cancers is difficult and remains a great clinical problem.

Systematic review of genetic influences on the prognosis of colorectal cancer

Background

In terms of genetics, colorectal cancer is one of the best understood of all malignant diseases. Genetic influences on prognosis may have far-reaching implications, especially for the design of surgical and chemoradiotherapeutic regimens. However, their significance in determining prognosis remains unclear. This study aimed to review the literature on the specific role of key genes in determining the survival of patients with colorectal cancer.

Methods

A Medline search was carried out to identify all original scientific papers relating colorectal cancer genetics to patient survival, up to December 2002. Cochrane and Embase databases were also searched. Identified articles were retrieved and searched carefully for additional information. This review includes K-ras, p53, DCC, NM23 and DNA mismatch repair genes.

Results and conclusion

Conflicting evidence exists as to the prognostic significance of genes commonly implicated in the pathogenesis of colorectal carcinoma. Possible causes for such discrepancy include differences in study methods and laboratory techniques, variable duration of follow-up, statistical differences in study power, and heterogeneity in study populations. Future studies should adopt standardized protocols to define clinically relevant genetic observations.

Effects of tumor suppressor gene NGX6 on growth of human colon cancer cell line HT-29

AIM: NGX6 is a novel tumor suppressor gene candidate, and the expression of NGX6 decreased in colon cancer specimen, which suggested that the down-regulation of NGX6 was closely related to tumorigenesis of colon cancer. This study was designed to explore effects of NGX6 on the cytobiological characteristics of human colon cancer cell line HT-29 and to elucidate the role of NGX6 in the colon cancer.

METHODS: The mammal expression vector of pcDNA3.1(+)/NGX6 was transfected into human colon cancer cell line HT-29 cells by liposome.The integration of the exogenous vector DNA and the expression of NGX6 were detected by dot blot and RT-PCR. Finally, the cytobiological characteristics of positive clone were analyzed by growth curves of cells, MTT, soft agar assay, FCM and xenograft.

RESULTS: pcDNA3.1(+)/NGX6/HT-29 cells grew slower than pcDNA3.1(+)/HT-29 and HT-29 cells (P < 0.05), and the PDT of pcDNA3.1(+)/NGX6/HT-29 cell was 34.5 hours, which was significantly longer than that of pcDNA3.1(+)/HT-29 cells (27.1 h) and HT-29 cells (23.0 h). FCM data showed that the overexpression of NGX6 blocked the progression of G1→S phase in cell cycle, and it also presented decreased clonogenicity in soft agar assay and tumor formation in nude mice.

CONCLUSION: The re-expression of NGX6 can reverse the malignant phenotype of human colon cancer cell line HT-29. Therefore, NGX6 gene may be a good candidate of tumor suppressor gene associated with colon cancer.

Relationship between expression of VEGF, Flt1, bFGF and P53and outcome in patients with gastric carcinoma

AIM: To investigate the relationship between the expression of VEGF, Flt1, bFGF and P⁵³, the clinicopathological characteristics and outcome in patients with gastric carcinoma.

METHODS: The relationship between VEGF, Flt1, bFGF, P⁵³ expression and clinicopathological characteristics and outcome in the patient was assessed by streptoavidin-biotin method of immunohistochemistry with polyclonal antibodies against VEGF, Flt1, bFGF, and P⁵³ protein. The survival curves were formulated using Kaplan-Meier method and analyzed by the log-rank test, and the influence of each variable on suvival was assessed by the Cox' s proportional hazard model.

RESULTS: VEGF expression was closely correlated with serosal invasion (Se, Sei invasion vs Pm, SS and M, SM invasion, P < 0.01). Expression of P⁵³ was obviously higher in the patients with lymph node metastasis than those without (lymph node metastasis vs non-lymph node metastasis, P < 0.05). There was a positive correlation between VEGF and Flt1 expression (VEGF expression in Flt1 positive group vs Flt1 negative group, P < 0.01). The factors that affected the prognosis in patients with gastric carcinoma were PTNM stage, VEGF expression, serosal invasion, and surgical curability. Flt1, bFGF, and P⁵³ expression had no influence on the prognosis of patients with gastric carcinoma (P > 0.05).

CONCLUSION: P⁵³ expression has significant relationship with lymph node metastasis in gastric carcinoma. VEGF expression is correlated with serosal invasion and the prognosis and may be a good prognostic indicator in gastric carcinoma.

Molecular lesions in colorectal cancer: impact on prognosis? Original data and review of the literature

BACKGROUND

In the Dukes' B and C stages of colorectal carcinoma there are considerable variations in the observed courses of the disease. Since post-operative chemotherapy in patients with Dukes' C (node-positive) colon carcinoma has been demonstrated to be effective in improving overall-survival, a more exact prognosis assessment gains additional significance and therapeutic relevance.

DISCUSSION

One also hopes to derive improved prognostic factors from the clarification of the molecular pathogenesis. Because of its frequency and the accessibility and recognizability of its developmental stages colorectal carcinoma is among the best investigated of all solid tumors. Despite a multitude of suggested molecular candidate markers none of these changes has yet been able enter the everyday life of the clinic. However, it is to be expected that some of the molecular alterations presently discussed will gain importance before long in the clinical treatment of patients with colorectal carcinoma.

CONCLUSION

Considering also our own findings, this review presents the latest developments in the scientific discussion of the tumor suppressor/oncogenes p53, k-ras, and DCC, biochemical determinants of the 5-fluorouracil metabolism, and defects of the DNA repair system.

Colon cancer: prevalence, screening, gene expression and mutation, and risk factors and assessment

Colon cancer detection at an early stage and identifying susceptible individuals can result in reduced mortality from this prevalent cancer. Genetic events leading to the development of this cancer involve a multistage progression of adenoma polyps to invasive metastatic carcinomas. Currently, there is no satisfactory screening method that is highly specific, sensitive, or reliable. Dietary patterns associated with the greatest increase in colon cancer risk are the ones that typify a diet rich in fat and calories, and low in vegetable, fruits, and fibers. Genetic susceptibility to environmental carcinogenesis must be factored into the risk assessment for this cancer. Many genes have been shown to be associated with increased expression and mutations in colorectal cancer patients. These genes have been reviewed; it is hoped that by carefully selecting a number of them, a molecular approach that is suitable for arriving at a tumorigenic expression index is developed, which will reliably detect this cancer at an early stage (i.e., before it metastasizes), especially in exfoliated samples (e.g., stool and blood), so that appropriate intervention strategies can be implemented. Illustrated herein is the utility of employing real-time reverse transcriptase polymerase chain reaction (RT-PCR) to quantitatively measure gene expression, and develop an index that is specific for this cancer, which if perfected may result in a reliable and sensitive screening technique for colorectal cancer detection.

Overexpression of p53 is correlated with stromal invasion in extramammary Paget’s disease of the vulva

Molecular alterations that are associated with clinicopathological features of extramammary Paget's disease of the vulva (PDV) are poorly understood. Consequently, we have investigated whether a correlation exists between overexpression of p53 protein and various clinicopathologic features of PDV. Our study group comprises 10 primary noninvasive PDVs, 3 primary PDVs with minimal invasion, and 1 primary PDV with frank invasion. Recurrence in the form of noninvasive PDV was seen in 4 patients with previously noninvasive PDVs and in 1 patient who previously had PDV with minimal invasion. Metastases to the inguinal lymph nodes were associated with the 1 PDV with frank invasion and 1 of the PDVs with minimal invasion. An immunohistochemical study of p53 expression was performed on paraffin-embedded tissue. Negative p53 immunostaining was seen in all of the primary noninvasive PDVs as well as their recurrences. Positive p53 immunostaining was observed in the invasive as well as the intraepidermal components of all of the primary PDVs with invasion, the metastatic tumors in the inguinal lymph nodes, and the recurrent PDV associated with prior invasion, indicating a possible role of p53 in the progression of PDV. To our knowledge, our observation of p53 overexpression in the intraepidermal component of PDVs associated with invasion is the first to be reported in the literature. This observation may prove helpful in identifying stromal invasion in small biopsies. We also report for the first time an association between high nuclear grade in PDV and the propensity for inguinal lymph node metastasis.

TP53 mutation in colorectal cancer

Approximately half of all colorectal cancers show p53 (TP53) gene mutations, with higher frequencies observed in distal colon and rectal tumors and lower frequencies in proximal tumors and those with the microsatellite instability or methylator phenotypes. Alterations to this gene appear to have little or no prognostic value for colorectal cancer patients treated by surgery alone, but are associated with worse survival for patients treated with chemotherapy. There is some evidence that different p53 mutations are associated with different clinical features including prognosis and response to therapy, although further large studies are required to confirm this. Several in vitro, animal and clinical studies have shown that normal p53 is required for the response of colorectal cancers to 5-fluorouracil-based chemotherapy. This should be confirmed by additional retrospective cohort studies and by the incorporation of P53 status in ongoing and future clinical trials. The evaluation of p53 overexpression, using a standardized immunohistochemical (IHC) procedure, could be a clinically useful marker for the identification of colorectal cancer patients likely to benefit from the standard chemotherapy regime currently used for this disease.

High incidence of protein-truncating mutations of the p53 gene in liver metastases of colorectal carcinomas

To clarify the significance of p53 mutations in liver metastasis of colorectal carcinogenesis, the characteristics of p53 mutations from 51 liver metastases and 76 primary invasive carcinomas without liver metastasis (Dukes' A, B and C) were compared. The frequency of tumors with p53 mutations was 61% (31 out of 51) in the liver metastases, and 51% (39 out of 76) in the primary carcinomas without liver metastasis. Approximately 90% of the informative cases having p53 mutation showed 17pLOH. Mutations detected within exons 4-10 of the p53 gene included missense, nonsense, frameshift, inframe deletion, and inframe insertion mutations. Out of the tumors with p53 mutations, we found that the percentage of tumors with protein-truncating mutations (nonsense and frameshift mutations) was extremely higher in liver metastases (16 out of 31, 52%) than in primary carcinomas without liver metastasis (5 out of 39, 13%) (P=0.0005). The present results suggest that protein-truncating mutations of the p53 gene are more relevant than missense mutations as one of the prognostic factors in liver metastasis of colorectal carcinomas.

P21 (WAF1) expression in colorectal cancer: correlation with P53 and cyclin D1 expression, clinicopathological parameters and prognosis

P21 (WAF1), P53 and cyclin D1 belong to the cell cycle-regulating family of proteins, and the loss of activity of proteins P53 and P21 (WAF1) seems to be one of the most important regulatory mechanisms of carcinogenesis in colorectal cancer. The purpose of this study was to assess the relationship between P21 (WAF1), P53 and cyclin D1 immunoreactivity, and to evaluate the prognostic significance of their expression. Tissue sections from 122 paraffin-embedded colorectal carcinomas were immunostained with monoclonal antibodies. Positivity for P21 (WAF1) was found in 48 cases (39%), positivity for P53 in 96 cases (70%) and positivity for cyclin D1 in all the cases (100%). Statistical analyses revealed a statistically significant inverse correlation between P53 and P21 (WAF1)-immunopositivity and between P21 (WAF1)-immunopositivity and the degree of cyclin D1-immunopositivity, as well as an inverse correlation between P21 (WAF1) expression and clinical stage. In univariate analysis, down-regulation of P21 (WAFI) expression was associated with poor prognosis, but multivariate analysis did not confirm its independent prognostic significance. In Cox's analysis only regional lymph node invasion and hepatic metastases were proven as independent prognostic parameters. Our investigation results suggest that in colorectal cancer, the induction of P21 (WAF1) may occur mostly in a P53-dependent pathway. P21 (WAF1), as the main cyclin-dependent kinase (CDK)-inhibitor, may also inhibit the activity of cyclins such as cyclin D1.

P53 overexpression predicts poor chemosensitivity to high-dose 5-fluorouracil plus leucovorin chemotherapy for stage IV colorectal cancers after palliative bowel resection

Our study aims to further clarify the prognostic significance of p53 overexpression in stage IV colorectal cancer. Between January 1994 and June 1997, we recruited 144 patients with stage IV colorectal cancers for our study, based on appropriate eligibility criteria. The patients were nonrandomly allocated to 2 treatment groups of either with or without high-dose 5-fluorouracil plus leucovorin chemotherapy (HDFL: 5-Fu: 2,600 mg/m(2) leucovorin 300 mg/m maximum 500 mg). Each treatment group was further divided into 2 subgroups according to the status of p53 overexpression. Therefore, 4 subgroups were allocated in our study and were designated as p53 (overexpression) HDFL (+), n = 65; p53 (normal) HDFL (+), n = 37; p53 (overexpression) HDFL (-), n = 27; and p53 (normal) HDFL (-), n = 15, respectively. All patients were prospectively followed until April 2001. There was no significant difference of the background clinicopathologic data of these 4 allocated subgroups of patients (p > 0.05). Multivariate analysis of various clinicopathologic factors of the whole group of patients indicated that age > or = 60 years, poor differentiation, mucin production, CEA > 100 ng/ml, p53 overexpression and without chemotherapy were the significant independent poor prognostic factors (p < 0.05). Survival analyses indicated that the patients of subgroup p53 (normal) HDFL (+) survived significantly longer than those of subgroup p53 (overexpression) HDFL (+), with mean survival time (95% confidence interval [CI]) of 20.24 (16.24-24.25) and 13.29 (10.98-15.60) months, respectively (p = 0.0043, log-rank test). In contrast, in patients without chemotherapy, the prognosis was poor regardless of their p53 status, with mean survival time (95% CI) of 6.85 (5.47-8.23) and 5.87 (4.48-7.26) months in p53 (overexpression) HDFL (-) and p53 (normal) HDFL (-) subgroups of patients, respectively (p = 0.2820, log-rank test). Cancers of normal p53 expression responded significantly better to HDFL (p < 0.05), with mean response rate (95% CI) being 65.57% (52.18-82.96%) in subgroup p53 (normal) HDFL (+) as compared to 35.38% (23.52-47.24%) in subgroup p53 (overexpression) HDFL (+). The toxicity to HDFL was similarly minimal between p53-normal and p53-overexpression patients (p > 0.05). We thus concluded that the poorer prognosis of stage IV colorectal cancers with p53 overexpression was associated with their poorer chemosensitivity rather than the more biologic aggressiveness.

Comparison of microsatellite instability and chromosomal instability in predicting survival of patients with T3N0 colorectal cancer

BACKGROUND

At least 2 apparently independent mechanisms, microsatellite instability (MSI) and chromosomal instability, are implicated in colorectal tumorigenesis. Their respective roles in predicting clinical outcomes of patients with T3N0 colorectal cancer remain unknown.

METHODS

Eighty-eight patients with a sporadic T3N0 colon or rectal adenocarcinoma were followed up for a median of 67 months. For chromosomal instability analysis, Ki-ras mutations were determined by single-strand polymerase chain reaction, and p53 protein staining was studied by immunohistochemistry. For MSI analysis, DNA was amplified by polymerase chain reaction at 7 microsatellite targets (BAT25, BAT26, D17S250, D2S123, D5S346, transforming growth factor receptor II, and BAX).

RESULTS

Overall 5-year survival rate was 72%. p53 protein nuclear staining was detected in 39 patients (44%), and MSI was detected in 21 patients (24%). MSI correlated with proximal location (P <.001) and mucinous content (P <.001). In a multivariate analysis, p53 protein expression carried a significant risk of death (relative risk = 4.0, 95% CI = 1.6 to 10.1, P =.004). By comparison, MSI was not a statistically significant prognostic factor for survival in this group (relative risk = 2.2, 95% CI = 0.6 to 7.3, P =.21).

CONCLUSIONS

p53 protein overexpression provides better prognostic discrimination than MSI in predicting survival of patients with T3N0 colorectal cancer. Although MSI is associated with specific clinicopathologic parameters, it did not predict overall survival in this group. Assessment of p53 protein expression by immunocytochemistry provides a simple means to identify a subset of T3N0 patients with a 4-times increased risk for death.

p53 nuclear accumulation and multiploidy are adverse prognostic factors in surgically resected stage II colorectal cancers independent of fluorouracil-based adjuvant therapy

To identify the prognostically highest risk patients, DNA content and p53 nuclear or cytoplasmic accumulation, evaluated by monoclonal antibody DO7 and polyclonal antibody CM1, were determined in 94 surgically resected stage II (Dukes B2) colorectal cancers, treated or not with adjuvant 5-fluorouracil-based chemotherapy. Sixty-one (65%) of the tumors were aneuploid, 16 (17%) of which had a multiploid DNA content; 50 (53%) displayed DO7 nuclear p53 accumulation, and 44 (47%) showed cytoplasmic CM1 positivity. In multivariate analysis, only multiploidy and p53 nuclear positivity emerged as independent prognostic indicators of a poorer outcome. Positivity for p53 was associated with shorter survival in 5-fluorouracil-treated and untreated patients. Therefore, in patients with Dukes B2 colorectal cancer, a biologic profile based on the combined evaluation of DNA multiploidy and p53 status can provide valuable prognostic information, identifying patients to be enrolled in alternative, more aggressive therapeutic trials.

Intratumor genetic heterogeneity in advanced human colorectal adenocarcinoma

Colorectal carcinogenesis is widely accepted as one of the best-characterized examples of stepwise progression. The existing colorectal carcinogenesis model assumes genetic homogeneity of individual tumors for the main known genetic alterations: K-ras and p53 genes point mutations and loss of heterozygosity (LOH) of chromosome 5q and 18q. The object of the present study was to demonstrate the existence of an intratumor genetic heterogeneity in advanced sporadic colorectal carcinoma for these genetic alterations. Using improved tissue microdissection and DNA extraction, for each tumor, amplifiable DNA was obtained from 15 to 20 areas, of which 1 to 2 concerned lymph node metastases (LNM). This study revealed that 10 of 15 (67%) analyzed tumors were heterogeneous for at least 1 genetic alteration, with between 2 and 6 genotypically different clones detected per tumor. No correlation was observed between the genotype of these subclones and histological differentiation or invasive propensity. Intratumor heterogeneity was more frequently observed for LOH than for point mutations, 67% and 58% for LOH at APC and DCC locus, and 20% for mutation of either the K-ras or p53 gene. In 5 of the 9 (56%) heterogeneous cases with available LNM, the genotype observed in the LNM was different from that of the main clone in the primary tumor, and moreover, 2 of the LNM displayed a genotype undetected in the primary tumor. In conclusion, intratumor genetic heterogeneity was demonstrated in advanced sporadic colorectal carcinoma and was represented as topographically distinct genotypic subclones. Taking into account such a significant genetic heterogeneity of colorectal tumors, the use of genetic markers for prognosis management should be reconsidered.

What we could do now: molecular pathology of colorectal cancer

The contribution of molecular genetics to colorectal cancer has been largely restricted to relatively rare inherited tumours and to the detection of germ line mutations predisposing to these cancers. However, much is now known about the somatic events leading to colorectal cancer in general. Several studies have examined the relation between genetic features and prognosis. The purpose of this article is to review these studies and summarise the current state of this subject. Although many of the published studies are small and inconclusive, it is clear that several different pathways exist for the development of this cancer, and some molecular characteristics seem to correlate with clinicopathological features. At present, studies are confined to evaluating a small number of molecular markers; however, with the advent of methods for the rapid genetic profiling of large numbers of colorectal cancers, it will be possible to evaluate fully the clinical usefulness of a range of colorectal cancer genotypes.

p53 protein accumulation and p53 gene mutation in colorectal cancer

Comparison of immunohistochemical methods for detection of protein p53 accumulation and molecular techniques for analysis p53 gene mutation in colorectal cancer is presented. Thirty eight patients were included: all underwent surgery without preoperative treatment. Sex of patients, tumor localisation, macro and microscopic type of cancer and staging according to Astler-Coller and Jass classifications were evaluated. Protein p53 accumulation was detected by the streptavidin-biotin method using DO-7 (Dako) antibody. The number of cells stained were classified semiquanititatively according to a scoring system: (-)no positive cells, (+) : 10-30% positive cells, (++) : 40-70% positive cells, (+++) : >70% positive cells. For all cancer samples, exons 5 to 9 of p53 gene were amplified from isolated genomic DNA. PCR products were subjected to single standed conformational polymorphism analysis. All product were also directly sequenced on ABI PRISM 377 apparatus using fluorescent dideoxyterminators chemistry. The protein p53 accumulation was detected in 53% (20/38), whereas p53 gene mutation was seen in 55% (21/38). Among them, 15 patients (39%) with overexpression showed mutation in exon 5-8 gene p53. Discrepancies between results were noted in 29%. In conclusion, the necessity of both methods immunohistochemical and molecular is indicated for the objective evaluation of functional and structural status of p53 gene and protein.

Diagnostic and prognostic tumor markers in the gastrointestinal tract

The gastrointestinal tract is the most common site of malignancies of any anatomic system in the body. An early detection of primary tumors of the bowel, pancreas, liver, stomach, and esophagus is often difficult in asymptomatic patients and for this reason these tumors are often detected at a relatively advanced stage, when symptoms lead to a diagnostic evaluation. Furthermore, gastrointestinal tract tumors have an extremely variable prognosis; thus, the identification of new prognostic parameters may be useful for selecting patients to more tailored therapies. In this work, the main molecular, genetic, tissular, and circulating tumor markers proposed for diagnosis and prognosis of gastrointestinal malignancies are reviewed and discussed.

The results of colorectal cancer treatment by p53 status: treatment-specific overview

PURPOSE

Both negative and positive influences of mutant p53 on treatment outcome have been reported, and we present here a meta-analysis of published studies where outcome was reported for defined treatment groups.

METHODS

We identified articles on the effect of p53 status by treatment modality, excluding those not stratified by method of treatment. A common hazard ratio was estimated from studies that reported a multivariate analysis. We also estimated the numbers of patients expressing the endpoint at the mean or median follow-up time and calculated a pooled odds ratio.

RESULTS

Twenty-eight articles were evaluable (23 using immunohistochemistry to detect overexpression of p53 and 8 using DNA sequencing), for a total of 4,416 patients. For patients treated with surgery only, the immunohistochemistry studies showed a significant influence of p53 status on disease-free survival and a marginally significant influence on overall survival. In the studies using DNA sequencing, by contrast, there was a significant influence of p53 mutations on overall survival, but not disease-free survival. For patients treated with surgery and radiotherapy, the influence of p53 status on disease-free survival was either insignificant or marginally significant, depending on test used; there was no influence on overall survival.

CONCLUSIONS

Although this pooled analysis of published studies where treatment was accounted for shows that there is a borderline significant hazard associated with p53 overexpression or mutation vs. p53 wild-type, it is unlikely that p53 can be applied in a routine clinical setting alongside factors such as T stage, nodal status, and residual tumor, whose prognostic value is much stronger.

Prognostic significance of K-ras and TP53 mutations in the role of adjuvant chemotherapy on survival in patients with Dukes C colon cancer

PURPOSE

Mutations in K-ras and TP53 genes are common in colorectal cancer. They affect biologic behavior and might influence chemotherapy susceptibility in these tumors. We investigated whether the survival of patients with Dukes C colon cancer treated with adjuvant chemotherapy is influenced by K-ras and TP53 mutations.

METHODS

Mutation screening of the hot spots of the K-ras gene and of the evolutionarily conserved regions of the TP53 gene was performed by denaturing gradient gel electrophoresis technique in formalin-fixed paraffin-embedded specimens of 55 consecutive patients with Dukes C colon cancer treated with adjuvant 5-fluorouracil-based chemotherapy. The median follow-up was 47 (range, 32-66) months.

RESULTS

Alterations in the mutation hot spots of K-ras were found at codon 12 (n = 11) and 13 (n = 4) in 15 of the 55 carcinomas (27 percent). No mutation was found at codon 61. Mutations of a probably causative nature in the evolutionarily conserved regions (exons 5-8) of the TP53 gene were found in 24 tumors (44 percent). K-ras and TP53 mutations were found equally in the group with recurrent disease (7/26 (26 percent) and 12/27 (44 percent), respectively) and in the group without recurrences (8/28 (24 percent) and 12/28 (43 percent), respectively). Cancer-specific survival did not differ significantly between patients with K-ras or TP53 or both mutated and nonmutated tumors, respectively (log-rank test: K-ras, P = 0.72 and TP53, P = 0.77; K-ras and TP53, P = 0.8). Also, potentially aggressive K-ras codon 12 and 13 mutations had the same survival as tumors without these mutations (log-rank test; P = 0.73).

CONCLUSIONS

Patients with K-ras or TP53 or both mutated Dukes C colon tumors have the same survival as nonmutated tumors when treated with adjuvant chemotherapy. These data suggest that mutations in K-ras or TP53 alone are not prognostic indicators in patients with Dukes C colon cancer receiving adjuvant 5-Fluorouracil-based therapy.

Prostate tumours from an Asian population: examination of bax, bcl-2, p53 and ras and identification of bax as a prognostic marker

Molecular studies have suggested that ethnicity may play a significant role in prostate tumorigenesis, but no information exists for groups other than Caucasian or Japanese patients. We examined 62 archival samples of prostate tumours from Asians of non-Japanese origin for the over-expression of p53, for the possible presence of mutated ras genes, for the overexpression of the bcl-2 and bax proteins, as well as directly for the presence of apoptotic cells by the TUNEL methodology. Gene lesions of both ras (0%) and p53 (3%) were rare. While bcl-2 expression was not observed in any sample, bax expression was noted in 76% of samples and was associated with a significantly worse patient prognosis both overall (P< 0.005) and specifically in Chinese patients (P< 0.02). Apoptotic cells were found in 61% of samples, and were significantly associated with the presence of bax expression (P = 0.002), but not patient survival. These results suggest that prostate tumours from non-Japanese Asians are genetically distinct from prostate tumour found in both Japanese and Caucasian patients, and that treatment modalities may need to be tailored for specific population groups.

Prognostic factors in colorectal cancer. College of American Pathologists Consensus Statement 1999

BACKGROUND

Under the auspices of the College of American Pathologists, the current state of knowledge regarding pathologic prognostic factors (factors linked to outcome) and predictive factors (factors predicting response to therapy) in colorectal carcinoma was evaluated. A multidisciplinary group of clinical (including the disciplines of medical oncology, surgical oncology, and radiation oncology), pathologic, and statistical experts in colorectal cancer reviewed all relevant medical literature and stratified the reported prognostic factors into categories that reflected the strength of the published evidence demonstrating their prognostic value. Accordingly, the following categories of prognostic factors were defined. Category I includes factors definitively proven to be of prognostic import based on evidence from multiple statistically robust published trials and generally used in patient management. Category IIA includes factors extensively studied biologically and/or clinically and repeatedly shown to have prognostic value for outcome and/or predictive value for therapy that is of sufficient import to be included in the pathology report but that remains to be validated in statistically robust studies. Category IIB includes factors shown to be promising in multiple studies but lacking sufficient data for inclusion in category I or IIA. Category III includes factors not yet sufficiently studied to determine their prognostic value. Category IV includes factors well studied and shown to have no prognostic significance.

MATERIALS AND METHODS

The medical literature was critically reviewed, and the analysis revealed specific points of variability in approach that prevented direct comparisons among published studies and compromised the quality of the collective data. Categories of variability recognized included the following: (1) methods of analysis, (2) interpretation of findings, (3) reporting of data, and (4) statistical evaluation. Additional points of variability within these categories were defined from the collective experience of the group. Reasons for the assignment of an individual prognostic factor to category I, II, III, or IV (categories defined by the level of scientific validation) were outlined with reference to the specific types of variability associated with the supportive data. For each factor and category of variability related to that factor, detailed recommendations for improvement were made. The recommendations were based on the following aims: (1) to increase the uniformity and completeness of pathologic evaluation of tumor specimens, (2) to enhance the quality of the data needed for definitive evaluation of the prognostic value of individual prognostic factors, and (3) ultimately, to improve patient care.

RESULTS AND CONCLUSIONS

Factors that were determined to merit inclusion in category I were as follows: the local extent of tumor assessed pathologically (the pT category of the TNM staging system of the American Joint Committee on Cancer and the Union Internationale Contre le Cancer [AJCC/UICC]); regional lymph node metastasis (the pN category of the TNM staging system); blood or lymphatic vessel invasion; residual tumor following surgery with curative intent (the R classification of the AJCC/UICC staging system), especially as it relates to positive surgical margins; and preoperative elevation of carcinoembryonic antigen elevation (a factor established by laboratory medicine methods rather than anatomic pathology). Factors in category IIA included the following: tumor grade, radial margin status (for resection specimens with nonperitonealized surfaces), and residual tumor in the resection specimen following neoadjuvant therapy (the ypTNM category of the TNM staging system of the AJCC/UICC). (ABSTRACT TRUNCATED)

The p53 tumor suppressor gene: from molecular biology to clinical investigation

The tumor suppressor p53 is a phosphoprotein barely detectable in the nucleus of normal cells. Upon cellular stress, particularly that induced by DNA damage, p53 can arrest cell cycle progression, thus allowing the DNA to be repaired; or it can lead to apoptosis. These functions are achieved, in part, by the transactivational properties of p53, which activate a series of genes involved in cell cycle regulation. In cancer cells bearing a mutant p53, this protein is no longer able to control cell proliferation, resulting in inefficient DNA repair and the emergence of genetically unstable cells. The most common changes of p53 in human cancers are point missense mutations within the coding sequences of the gene. Such mutations are found in all major histogenetic groups, including cancers of the colon (60%), stomach (60%), breast (20%), lung (70%), brain (40%), and esophagus (60%). It is estimated that p53 mutations are the most frequent genetic event in human cancers, accounting for more than 50% of cases. One of the most striking features of the inactive mutant p53 protein is its increased stability (half-life of several hours, compared to 20 min for wild-type p53) and its accumulation in the nucleus of neoplastic cells. Therefore, positive immunostaining is indicative of abnormalities of the p53 gene and its product. Several studies have shown that p53 mutations are associated with short survival in colorectal cancer, but the use of p53 as a tumoral marker is still a matter of debate.

American Joint Committee on Cancer Prognostic Factors Consensus Conference: Colorectal Working Group

BACKGROUND

The American Joint Committee on Cancer (AJCC), which regularly reviews TNM staging systems, established a working party to develop recommendations for colorectal carcinoma.

METHODS

A multidisciplinary consensus conference using published literature developed an arbitrary classification system of prognostic marker value (Category I, IIA, IIB, III, and IV), which forms the framework for this report.

RESULTS

The working party concluded that several T categories should be subdivided: pTis into intraepithelial carcinoma (pTie) and intramucosal carcinoma (pTim); pT1 into pT1a and pT1b corresponding to the absence or presence of blood or lymphatic vessel invasion, respectively; and pT4 into pT4a and pT4b according to the absence or presence of tumor involving the surface of the specimen, respectively. The working party also recommended that TNM groups be stratified based on the presence or absence of elevated serum levels of carcinoembryonic antigen (CEA) (>/= 5 ng/mL) on preoperative clinical examination. In addition, the working party also concluded that carcinoma of the appendix should be excluded from the colorectal carcinoma staging system because of fundamental differences in natural history.

CONCLUSIONS

The TNM categories and stage groupings for colorectal carcinoma published in the current AJCC manual have clinical and academic value. However, a few categories require subdivision to provide increasing discrimination for individual patients. The serum marker CEA should be added to the staging system, whereas multiple other factors should be recorded as part of good clinical practice. Although many molecular and oncogenic markers show promise to supplement or modify the current staging systems eventually, to the authors' knowledge none have yet been evaluated sufficiently to recommend their inclusion in the TNM system.

Apoptosis occurs after cerebral contusions in humans

OBJECTIVE

Animal model systems have shown that head trauma can induce cell death in regions of the brain away from the site of the impact via a process of apoptosis. We sought to determine whether there was evidence of cellular apoptosis in clinically collected materials from human head trauma patients, as well as to attempt to determine the pathway by which it may occur.

METHODS

Thirty-one sequential specimens of brain tissue excised during emergency craniotomy for evacuation of cerebral contusions with mass effect were examined. Non-necrotic pericontusional tissues were detected in 11 samples. These were examined for the presence of apoptotic cells by the terminal deoxynucleotide transferase-mediated nick end labeling method as well as by immunohistochemistry to detect possible expression of the apoptosis-related genes p53, bcl-2, and bax.

RESULTS

Bax expression was detected in all patients, whereas bcl-2 expression was noted in six patients. Terminal deoxynucleotide transferase-mediated nick end labeling-positive cells were noted in eight patients. One instance of p53-positive immunostaining was observed. Patients with bcl-2 expression had a better survival rate than patients in whom no bcl-2 expression was noted (P = 0.01).

CONCLUSION

Although necrosis seemed to be the main finding in cerebral contusions, these results support the hypothesis that apoptosis does occur in patients after traumatic brain injury, and this may contribute to the secondary injury processes that are seen with head injury. Patients in whom anti-apoptotic bcl-2 is induced seem to have a better prognosis. This may have important clinical significance in the development of bcl-2 homologs or bax inhibitors to prevent apoptosis.

Thymidilate synthase and p53 primary tumour expression as predictive factors for advanced colorectal cancer patients

The purpose of this work was to analyse the ability of p53 and thymidilate synthase (TS) primary tumour expression to retrospectively predict clinical response to chemotherapy and long-term prognosis in patients with advanced colorectal cancers homogeneously treated by methotrexate (MTX)-modulated-5-fluorouracil (5-FU-FA). A total of 108 advanced colorectal cancer patients entered the present retrospective study. Immunohistochemical p53 (pAb 1801 mAb) and TS (TS106 mAb) expression on formalin-fixed paraffin-embedded primary tumour specimens was related to probability of clinical response to chemotherapy, time to progression and overall survival. p53 was expressed in 53/108 (49%) tumours, while 54/108 (50%) showed TS immunostaining. No relationship was demonstrated between p53 positivity and clinical response to chemotherapy (objective response (OR): 20% vs 23%, in p53+ and p53- cases respectively) or overall survival. Percent of OR was significantly higher in TS-negative with respect to TS-positive tumours (30% vs 15% respectively; P < 0.04); simultaneous analysis of TS and p53 indicated 7% OR for p53-positive/TS-positive tumours vs 46% for p53-positive/TS-negative tumours (P < 0.03). Logistic regression analysis confirmed a significant association between TS tumour status and clinical response to chemotherapy (hazard ratio (HR): 2.91; 95% confidence interval (CI) 8.34-1.01; two-sided P < 0.05). A multivariate analysis of overall survival showed that only a small number of metastatic sites was statistically relevant (HR 1.89; 95% CI 2.85-1.26; two-sided P < 0.03). Our study suggests that immunohistochemical expression of p53 and TS could assist the clinician in predicting response of colorectal cancer patients to modulated MTX-5-FU therapy.

p53 and Bcl-2 as significant predictors of recurrence and survival in rectal cancer

The aim of this study was to evaluate the prognostic value of p53 nuclear accumulation and Bcl-2 expression after curative surgery for rectal cancer. Immunohistochemistry was performed using monoclonal antibodies (MAb) (DO-1 for p53; anti-human Bcl-2 MAb, clone 124, for Bcl-2) on formalin-fixed, paraffin-embedded tissues of 160 rectal carcinomas (UICC stages I-III), and results were compared with data from the prospective registry of rectal cancer by univariate and multivariate logistic regression model focusing specifically on recurrence. Survival was calculated by the Kaplan-Meier method and proportional hazards model. p53 nuclear accumulation was documented in 39% (n=63) of tumours and was associated with a higher incidence of tumour progression (local or distant recurrence) and poorer disease-free survival (P<0.0001). Bcl-2 expression was detected in 29% (n=47), and was associated with longer disease-free survival and lower incidence of recurrence (P<0.0086). Multivariate logistic regression analysis demonstrated that gender (P=0.0136), UICC stage (P=0.0002), p53 expression (P=0.0002) and Bcl-2 expression (P=0. 0243) were independent factors predictive of recurrence. The proportional hazards model identified p53 (P=0.0009), UICC stage (P=0.0480), gender (P=0.0049), but not Bcl-2 (P=0.1503), as independently related to disease-free survival. Looking at the p53/Bcl-2 subgroups, the poorest prognosis was observed in the p53+/Bcl-2- subgroup, whereas patients whose tumours were p53-/Bcl-2+ had the best prognosis (P<0.0001). Immunohistochemical assessment of both p53 and Bcl-2 status may be valuable in predicting recurrence and survival after curative surgery for rectal cancer. Therefore, they play a role as prognostic factors in rectal cancer. p53 is a stronger predictor of prognosis than Bcl-2.

Microsatellite instability and 8p allelic imbalance in stage B2 and C colorectal cancers

BACKGROUND

Microsatellite instability (MSI) and allelic imbalance involving chromosome arms 5q, 8p, 17p, and 18q are genetic alterations commonly found in colorectal cancer. We investigated whether the presence or absence of these genetic alterations would allow stratification of patients with Astler-Coller stage B2 or C colorectal cancer into favorable and unfavorable prognostic groups.

METHODS

Tumors from 508 patients were evaluated for MSI and allelic imbalance by use of 11 microsatellite markers located on chromosome arms 5q, 8p, 15q, 17p, and 18q. Genetic alterations involving each of these markers were examined for associations with survival and disease recurrence. All P values are two-sided.

RESULTS

In univariate analyses, high MSI (MSI-H), i.e., MSI at 30% or more of the loci examined, was associated with improved survival (P =.02) and time to recurrence (P =.01). The group of patients whose tumors exhibited allelic imbalance at chromosome 8p had decreased survival (P =.02) and time to recurrence (P =.004). No statistically significant associations with survival or time to recurrence were observed for markers on chromosome arms 5q, 15q, 17p, or 18q. In multivariate analyses, MSI-H was an independent predictor of improved survival (hazard ratio [HR] = 0.51; 95% confidence interval [CI] = 0.31-0.82; P =.006) and time to recurrence (HR = 0.42; 95% CI = 0.24-0.74; P =.003), and 8p allelic imbalance was an independent predictor of decreased survival (HR = 1.89; 95% CI = 1.25-2.83; P =. 002) and time to recurrence (HR = 2.07; 95% CI = 1.32-3.25; P =.002).

CONCLUSIONS

Patients whose tumors exhibited MSI-H had a favorable prognosis, whereas those with 8p allelic imbalance had a poor prognosis; both alterations served as independent prognostic factors. To our knowledge, this is the first report of an association between 8p allelic imbalance and survival in patients with colorectal cancer.