Expression of high p53 levels in colorectal cancer: a favourable prognostic factor

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.

Revisiting colorectal cancer animal model - An improved metastatic model for distal rectosigmoid colon carcinoma

Colorectal cancer (CRC) is the second most frequent and fatal cancer in Western countries. Understanding its biology with different incidence along the colon and rectum, genetic profile and how these factors contribute to local/distant progression, has been hampered by the lack of a suitable CRC model. We report a reproducible model, using human CRC cell lines (CL) (WiDr, LS1034, C2BBe1) injected (1 × 10⁷ cells/animal) in RNU rats (n = 55) which underwent cecostomy and descending colostomy with mucosal-cutaneous fistula of the sigmoid colon. CL were characterized by immunohistochemistry: CK20, CDX2, P53, vimentin, Ki67, CD44, CD133, E-cadherin, β-catenin and CEA; cancer stem cells-immune system interaction was studied and tumor progression was assessed with nuclear medicine imaging (^99mTc-MIBI). Animals developed locally invasive tumors and with WiDr neural invasion was registered. Cancer stem cells were detected in WiDr (CD44 positive). All the cell lines stimulated the immune system, being WiDr the most aggressive. Imaging studies demonstrated tumor uptake. With this CRC model we can study the microenvironment role and tumor-stroma interactions. All CL developed primary disease, but only the WiDR established neural invasion which may represent a metastatic pathway. This model can help unveiling the underlying metastatic mechanisms, and ultimately test better therapeutic approaches for CRC.

Expression of the EP300, TP53 and BAX genes in colorectal cancer: Correlations with clinicopathological parameters and survival

E1A binding protein P300 (EP300), tumor protein P53 (TP53) and BCL2 associated X, apoptosis regulator (BAX) genes encode proteins which cooperate to regulate important cellular processes. The present study aimed to determine the expression levels of EP300, TP53 and BAX in colorectal cancer (CRC) and to investigate their prognostic value and association with the progression of CRC. Tumor and matched unchanged colorectal tissues were collected from 121 CRC patients. Quantitative polymerase chain reaction and immunohistochemistry were used to assess the mRNA and protein levels of the studied genes. Altered expression of the studied genes in CRC tissues was observed at both the mRNA and protein levels. The depth of invasion was associated with TP53 mRNA levels and was correlated negatively with BAX mRNA expression. Moreover, a relationship between tumor location and BAX mRNA content was noted. BAX immunoreactivity was correlated positively with the intensity of p300 immunostaining and was associated with lymph node involvement and tumor-node-metastasis (TNM) disease stage. Univariate regression analysis revealed that overexpression of p53 and BAX in CRC tissues was associated with poor patient outcome. In conclusion, dysregulation of the expression of the studied genes was found to contribute to CRC pathogenesis. The association between p300 and BAX levels suggests the existence of an interdependent regulatory mechanism of their expression. Moreover, BAX expression may be regulated alternatively, in a p53-independent manner, since the lack of correlations between expression of these factors was observed.

Biomarkers p16, Human Papillomavirus and p53 Predict Recurrence and Survival in Early Stage Squamous Cell Carcinoma of the Vulva

OBJECTIVE

Vulvar squamous cell carcinoma (VSCC) develops through 2 distinct molecular pathways, one involving high-risk human papillomavirus (HPV) infection and the other through early p53 suppressor gene mutation. We sought to evaluate the influence of p53 mutation, HPV status, and p16 expression on local recurrence and disease-specific mortality in early stage VSCC.

MATERIALS AND METHODS

We performed a retrospective chart review of all patients with stage I VSCC at the Maine Medical Center from 1998 to 2007 (n = 92). Tumor size, depth of invasion, lymphatic/vascular space invasion, and growth pattern were recorded. Paraffin-embedded tissue blocks were stained by immunohistochemistry for p16 and p53; high-risk HPV was detected by polymerase chain reaction assay. Margin distance was determined by a gynecologic pathologist. Survival analyses were conducted to examine predictors of VSCC recurrence and disease-specific mortality.

RESULTS

Age, depth of invasion, lymphatic/vascular space invasion, growth pattern, and margin status were not significant predictors of recurrence or disease-specific mortality. Tumor size of greater than 4.0 cm indicated a 4-fold increase in disease-specific mortality but did not significantly increase recurrence. p16-Positive patients were less likely to recur and had no VSCC-related deaths. Human papillomavirus-positive patients were less likely to recur and had no VSCC-related deaths. p53-positive patients were 3 times more likely to recur and nearly 7 times more likely to die from vulvar cancer.

CONCLUSIONS

Our findings suggest that HPV and the surrogate biomarker p16 indicate a less aggressive type of vulvar cancer. p53 positivity was associated with poor prognosis and significantly increased both recurrence and disease-specific mortality.

Prognostic value of p53 for colorectal cancer after surgical resection of pulmonary metastases

Background

Pulmonary metastases occur in up to 25% of colorectal cancer (CRC) patients. Many studies have reported that pulmonary metastasectomy might increase 5-year survival of these patients. The aim of this study was to describe our experience with pulmonary metastasectomy for metastatic colorectal cancer and to explore the prognostic value of p53 overexpression and other factors.

Methods

Between July 2002 and December 2013, the clinicopathological data of 88 patients with colorectal carcinoma who underwent pulmonary metastases resection were retrospectively reviewed and analyzed. Clinical, biochemical and imaging, and operative data, and expression of p53 were retrospectively collected. Immunohistochemical staining for p53 was performed on paraffin-embedded 5-μm sections using mouse anti-human tumor protein p53 monoclonal antibody (DO-7, Dako, Denmark). Overall survival (OS) was calculated from resection of pulmonary metastases to death. The prognostic effect of each variable on survival was evaluated using the Kaplan-Meier method and log-rank test. For the multivariate analysis of prognostic factors, the Cox regression model was used.

Results

There were 58 men and 30 women in this study, and their median age was 55 (range 31 to 85). Video-assisted thoracoscopic surgery (VATS) was performed in 59 cases (78%), and 29 patients (19%) underwent thoracotomy. Lung wedge resection and pulmonary lobectomy were performed in 52 (59.1%) and 36 (40.9%) patients, respectively. After a median follow-up duration of 44 months, the cumulative 5-year survival was 45.4%, and the median overall survival was 57.8 months. The expression of p53 significantly influenced survival. In patients with p53 protein overexpression, we observed a median OS of 46.1 months, whereas the median OS of patients with negative protein expression of p53 was 62.6 months (p = 0.047). However, in multivariate analysis, p53 overexpression was failed to be an independently significant prognostic factor for survival.

Conclusions

Pulmonary resection of metastatic colorectal cancer might offer a chance to prolong survival including those patients with extrapulmonary metastases. p53 protein expression was identified as a prognosis-related factor for surgery.

Nucleolar GTP-binding Protein-1 (NGP-1) Promotes G1 to S Phase Transition by Activating Cyclin-dependent Kinase Inhibitor p21 Cip1/Waf1

Nucleolar GTP-binding protein (NGP-1) is overexpressed in various cancers and proliferating cells, but the functional significance remains unknown. In this study, we show that NGP-1 promotes G1 to S phase transition of cells by enhancing CDK inhibitor p21(Cip-1/Waf1) expression through p53. In addition, our results suggest that activation of the cyclin D1-CDK4 complex by NGP-1 via maintaining the stoichiometry between cyclin D1-CDK4 complex and p21 resulted in hyperphosphorylation of retinoblastoma protein at serine 780 (p-RB(Ser-780)) followed by the up-regulation of E2F1 target genes required to promote G1 to S phase transition. Furthermore, our data suggest that ribosomal protein RPL23A interacts with NGP-1 and abolishes NGP-1-induced p53 activity by enhancing Mdm2-mediated p53 polyubiquitination. Finally, reduction of p-RB(Ser-780) levels and E2F1 target gene expression upon ectopic expression of RPL23a resulted in arrest at the G1 phase of the cell cycle. Collectively, this investigation provides evidence that NGP-1 promotes cell cycle progression through the activation of the p53/p21(Cip-1/Waf1) pathway.

Growth arrest-specific transcript 5 associated snoRNA levels are related to p53 expression and DNA damage in colorectal cancer

BACKGROUND

The growth arrest-specific transcript 5 gene (GAS5) encodes a long noncoding RNA (lncRNA) and hosts a number of small nucleolar RNAs (snoRNAs) that have recently been implicated in multiple cellular processes and cancer. Here, we investigate the relationship between DNA damage, p53, and the GAS5 snoRNAs to gain further insight into the potential role of this locus in cell survival and oncogenesis both in vivo and in vitro.

METHODS

We used quantitative techniques to analyse the effect of DNA damage on GAS5 snoRNA expression and to assess the relationship between p53 and the GAS5 snoRNAs in cancer cell lines and in normal, pre-malignant, and malignant human colorectal tissue and used biological techniques to suggest potential roles for these snoRNAs in the DNA damage response.

RESULTS

GAS5-derived snoRNA expression was induced by DNA damage in a p53-dependent manner in colorectal cancer cell lines and their levels were not affected by DICER. Furthermore, p53 levels strongly correlated with GAS5-derived snoRNA expression in colorectal tissue.

CONCLUSIONS

In aggregate, these data suggest that the GAS5-derived snoRNAs are under control of p53 and that they have an important role in mediating the p53 response to DNA damage, which may not relate to their function in the ribosome. We suggest that these snoRNAs are not processed by DICER to form smaller snoRNA-derived RNAs with microRNA (miRNA)-like functions, but their precise role requires further evaluation. Furthermore, since GAS5 host snoRNAs are often used as endogenous controls in qPCR quantifications we show that their use as housekeeping genes in DNA damage experiments can lead to inaccurate results.

Blastocystis sp. subtype 3 triggers higher proliferation of human colorectal cancer cells, HCT116

Blastocystis sp. is a commonly found intestinal microorganism and was reported to cause many nonspecific gastrointestinal symptoms. Various subtypes have been previously reported, and the pathogenicity of different subtypes of Blastocystis is unclear and remains as a controversial issue. A recent study has shown that the Blastocystis antigen isolated from an unknown subtype could facilitate the proliferation of colon cancer cells. Current study was conducted to compare the effect of solubilized antigen isolated from five different subtypes of Blastocystis on colon cancer cells, HCT116. A statistically significant proliferation of these cells was observed when exposed to 1.0 μg/ml solubilized antigen isolated from subtype 3 Blastocystis (37.22%, p < 0.05). Real-time polymerase chain reaction demonstrated the upregulation of Th2 cytokines especially transforming growth factor beta in subtype 3-treated cancer cells (p < 0.01, 3.71-fold difference). Of interest, subtype 3 Blastocystis antigen also caused a significantly higher upregulation of cathepsin B (subtypes 1 and 2, p < 0.01; subtypes 4 and 5, p < 0.001; 6.71-fold difference) which lead to the postulation that it may enhance the exacerbation of existing colon cancer cells by weakening the cellular immune response. The dysregulation of IFN-γ and p53 expression also suggest Blastocystis as a proponent of carcinogenesis. Therefore, it is very likely for subtype 3 Blastocystis to have higher pathogenic potential as it caused an increased propagation of cancer cells and substantial amount of inflammatory reaction compared to other subtypes.

Management of colorectal cancer patients after resection of liver metastases: can we offer a tailored treatment?

Surgical resection remains the only option of cure for patients with colorectal liver metastases, and no patient should be precluded from surgery. There is much controversy not only regarding the most appropriate therapeutic approach in the neoadjuvant setting but also after surgery is performed. Many patients will experience early relapses but others will be long survivors. We need to establish reliable prognostic and predictive factors to offer a tailored treatment. Several prognostic factors after metastasectomy have been identified: high C-reactive protein levels, a high neutrophil-lymphocyte ratio, elevated neutrophil count and low serum albumin are related to a worst outcome. Elevated CEA and Ki 67 levels, intrahepatic and perihepatic lymph node invasion are also some of the markers related to a worst outcome. In contrast, the administration of preoperative chemotherapy has been associated with a better prognosis after hepatectomy. The administration of adjuvant chemotherapy should be done taking in consideration these factors. Regarding predictive factors, determination of ERCC1, TS, TP and DPD and UGT1 polymorphisms assessment could be considered prior to chemotherapy administration. This would avoid treatment related toxicities and increase this population quality of life.

Genetic alterations in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer in men and the second most common cancer in women worldwide. Both genetic and epigenetic alterations are common in CRC and are the driving force of tumorigenesis. The adenoma-carcinoma sequence was proposed in the 1980s that described transformation of normal colorectal epithelium to an adenoma and ultimately to an invasive and metastatic tumor. Initial genetic changes start in an early adenoma and accumulate as it transforms to carcinoma. Chromosomal instability, microsatellite instability and CpG island methylator phenotype pathways are responsible for genetic instability in colorectal cancer. Chromosomal instability pathway consist of activation of proto-oncogenes (KRAS) and inactivation of at least three tumor suppression genes, namely loss of APC, p53 and loss of heterozogosity (LOH) of long arm of chromosome 18. Mutations of TGFBR and PIK3CA genes have also been recently described. Herein we briefly discuss the basic concepts of genetic integrity and the consequences of defects in the DNA repair relevant to CRC. Epigenetic alterations, essential in CRC tumorigenesis, are also reviewed alongside clinical information relevant to CRC.

Tumor TP53 expression status, body mass index and prognosis in colorectal cancer

Inactivation of the TP53 (p53) pathway by TP53 mutations is one of key steps in colorectal carcinogenesis. TP53 also plays an important role in cellular energy metabolism. We hypothesized that TP53-altered tumor cells might behave aggressively independent of energy balance, while progression of TP53-intact cells might depend on excess energy balance. Utilizing a database of 1,060 colon and rectal cancer patients in two prospective cohort studies, we evaluated TP53 expression by immunohistochemistry. Among 1,060 colorectal cancers, 457 (43%) tumors were positive for TP53. Cox proportional hazards model was used to compute mortality hazard ratio (HR), adjusting for clinical and tumoral features, including microsatellite instability, the CpG island methylator phenotype, LINE-1 methylation, KRAS, BRAF and PIK3CA. TP53 positivity was not significantly associated with cancer-specific survival in univariate analysis with HR of 1.16 [95% confidence interval (CI)=0.92-1.45], which became significant after stage adjustment (multivariate HR=1.30; 95% CI=1.02-1.65). Notably, we found a possible modifying effect of patient's body mass index (BMI) on tumor TP53. In non-obese patients (BMI<30 kg/m2), TP53 positivity was associated with shorter cancer-specific survival (multivariate HR=1.53; 95% CI=1.17-2.00), while TP53 positivity was not significantly associated with survival among obese patients (BMI≥30 kg/m2). Effect of TP53 positivity on cancer-specific survival significantly differed by BMI (pinteraction=0.0051). The adverse effect of obesity on patient mortality was limited to TP53-negative patients. These molecular pathological epidemiology data may support a dual role of TP53 alterations in cell-cycle deregulation and cell autonomy with respect to energy balance status.

Molecular markers to individualize adjuvant therapy for colon cancer

While many patients with early-stage colon cancer are cured with surgery alone, the standard of care remains a uniform approach to adjuvant chemotherapy based primarily on tumor stage. Recently, increasing awareness of the need for more individualized decision-making in cancer care has led to the development of several potential prognostic and predictive markers in colon cancer. While adjuvant chemotherapy with 5-fluorouracil, leucovorin and oxaliplatin is clearly beneficial to patients with stage III disease, well-validated molecular markers might help define which patients with stage II disease are likely to benefit from adjuvant therapy as well. Here, we review the data on the clinical development of molecular markers to individualize adjuvant therapy in colon cancer.

Irinotecan therapy and molecular targets in colorectal cancer: a systemic review

Irinotecan is the second line chemotherapy for advanced stage colorectal cancer (CRC) after failure of first line chemotherapy with oxaliplatin and 5-fluorouracil. The aim of this review is to analyse the data on irinotecan as second line chemotherapy for advanced CRC and the potential roles of the molecular markers, p53 and vascular endothelial growth factor (VEGF) in the management of advanced CRC. Thus, the English literature from 1980 to 2008 concerning irinotecan, p53, VEGF and CRC was reviewed. On review, Phase II and III clinical trials showed that irinotecan improves pain-free survival, quality of life, 1-year survival, progression-free survival and overall survival in advanced CRC. p53 and VEGF were expressed in CRC and had a predictive power of aggressive clinical behaviour in CRC. Irinotecan sensitizes p53 wild type, mutant and null cells to Fas-mediated cell apoptosis in CRC cells. Wild type p53 cells were more sensitive to irinotecan than mutated p53. Irinotecan has an anti-VEGF effect inhibiting endothelial cell proliferation, increasing apoptosis and reducing microvascular density which is only limited by irinotecan toxicity levels. To conclude, irinotecan improves the patient's quality of life and the survival rates of patients with advanced CRC. p53 and VEGF status of the patients' tumour is likely to affect the responsiveness of CRC to irinotecan. It is recommended that studies of the expression of these molecular markers in relation to chemo-responsiveness of irinotecan should be carried out for better management of patients with advanced CRC.

Influência da localização do tumor na expressão tecidual da proteína p53 em doentes com câncer colorretal: estudo de 100 casos

OBJETIVO: O objetivo do presente estudo foi verificar, se existem diferenças na expressão tecidual da proteína p53 segundo a localização do tumor em doentes com câncer colorretal. MÉTODO: Foram estudados 100 doentes (54 mulheres), com média de idade de 59,8 anos com adenocarcinoma colorretal. A expressão da proteína p53 foi analisada por imunoistoquímica, com anticorpo monoclonal anti-p53 pela técnica da estreptavidina-biotina-peroxidase. A expressão tecidual da proteína p53 foi relacionada às variáveis: gênero, idade, grau histológico, tipo histológico, tamanho do tumor, estadiamento TNM, profundidade de invasão da parede intestinal, comprometimento linfonodal, invasão angiolinfática, localização do tumor no intestino grosso em relação à flexura esplênica. Na avaliação estatística da relação entre expressão da proteína p53 e as variáveis consideradas empregou-se o teste qui-quadrado, estabelecendo-se nível de significância de 5% (p<0,05). RESULTADOS: A proteína p53 foi positiva em 77% dos casos. Com relação as diferentes variáveis consideradas verificou-se maior tendência de expressão da proteína mutante quando se considerava a idade (p=0,001), grau histológico (p=0,001), tipo histológico (p=0,001), estádios tardios da classificação TNM (p=0,001), maior profundidade de invasão na parede cólica (p=0,001), comprometimento linfonodal (p=0,001), invasão angiolinfática (p=0,02), localização após a flexura esplênica (p=0,001), não se encontrando relação com gênero (p=0,49) e tamanho do tumor (p=0,08). CONCLUSÃO: Os resultados do presente estudo permitem concluir que a expressão da proteína p53 mutante ocorre com maior freqüência nos tumores localizados a partir da flexura esplênica.

Colorectal carcinoma prognosis can be predicted by alterations in gene p53 exons 5 and 8

BACKGROUND AND AIMS

Gene p53 alteration is a genetic event described in the progression from adenoma to colorectal carcinoma. Most of the p53 mutations occur in exons 5 to 8 in highly preserved regions and in the three main structural domains of the p53 protein. It is possible that mutations affecting different structural regions may present different effects on the p53 protein function and, due to this, they may have different prognostic meaning.

MATERIALS AND METHODS

The study population consisted of 353 patients diagnosed with sporadic colorectal cancer. Mutations in 5-8 exons of p53 gene were detected by means of single strand conformation polymorphism (SSCP). All samples that showed different migration bands in SSCP were confirmed by sequencing.

RESULTS

A total of 69 patients (19.7%) showed alterations of the gene p53. It was observed that mutation in codon 175 in exon 5 was related to tumors located in the colon (p = 0.01) and the mutation in the codon 288 in exon 8 was related to rectal tumors (p = 0.02). In the study of overall survival, mutation in codon 175 of exon 5 conferred a better prognosis and alterations of exon 8 were related to a worse prognosis in different population subgroups: in men, in patients younger than 71 years old, in the tumors located in the proximal colon, the ones moderately differentiated, and those that are mucinous.

CONCLUSION

According to this study, mutations in different exons of p53 are related to different phenotypes in colorectal cancer. These phenotypes could mean differences in the clinical evolution of the patients.

p53 protein accumulation as a prognostic marker in sporadic colorectal cancer

BACKGROUND AND AIMS

p53 protein plays a crucial role in the pathogenesis of a large number of malignancies. In this study, our goal was to elucidate the prognostic role of p53 overexpression and its relationship to clinicopathological variables in colorectal cancer.

MATERIALS AND METHODS

Between 1999 and 2004, surgical specimens of 258 patients who received surgical treatment for colorectal cancer at the Veterans General Hospital, Taipei were collected. p53 expression in tumor tissue was evaluated by immunohistochemical analysis using the human p53-specific mouse monoclonal antibody, PAb 1801.

RESULTS

Of the 258 patients, 97 (37.6%) had overexpression of p53 in tumor tissues. The accumulation of p53 protein in tumor tissues did not correlate with age, gender, preoperative serum carcinoembryonic antigen (CEA) level, mucin content, nodal status, and tumor stage. A statistically significant correlation was found between p53 overexpression and location of the tumor in the rectum (p=0.038). Well to moderately differentiated tumors had significantly higher frequency of p53 overexpression than poorly differentiated tumors (40.0 vs 20.0%, p=0.050). Each patient was followed up for a minimum of 2 years (median 35 months). In univariate analysis, 3-year cancer-specific survival rate was significantly higher in patients with tumor p53 overexpression (88.2%) than in patients without overexpression (log rank test, p=0.037). However, in multivariate analysis, the tumour node metastasis stage remained the most significant independent prognostic factor.

CONCLUSION

The accumulation of p53 protein might have a favorable prognostic value in colorectal cancer, but it is not an independent prognostic factor.

Comparative analysis of predictive biomarkers for therapeutical strategies in colorectal cancer

BACKGROUND

Prognostic information regarding the risk of postoperative tumor recurrence defined by a profile of serological, morphological and/or molecular markers can have potential value, particularly for patients with colorectal carcinoma (CRC) of the International Union Against Cancer (UICC) stage II/III who may benefit from adjuvant chemotherapy after surgery.

METHODS

A retrospective study of 783 patients with CRC (UICC I-III) including a subgroup analysis of 116 subjects was conducted to determine preoperative serum carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 19-9, and p53 serum levels. In addition, protein and gene expression of p53, CEA, and adenomatous polyposis coli (APC) was assessed in the tumors of those patients. The values of all serological, morphological, and molecular parameters were correlated with clinicopathological characteristics for their predictive value of tumor recurrence over a mean follow-up period of 32 +/- 6.2 months.

RESULTS

Serum CEA but not CA 19-9 or p53 was a significant prognostic factor for disease-free survival, along with UICC and T/N stage. When comparing elevated CEA, CA 19-9, and p53 serum levels with expression of the markers in the tumors, their overall expression was found to be 61.3% in the serum versus 93.5% in the tumor in analyzed patients (n = 116). In particular, all patients in UICC stages I-III who demonstrated at least three elevated markers (CEA/CA 19-9/p53) in serum and/or in the tumor presented with tumor recurrence/metastases.

CONCLUSION

Overall increased p53, CEA, and CA 19-9 serum levels and their marker expression in the tumor may be used at the time of primary tumor removal for defining patients at risk for tumor recurrence.

Mutant p53 protein in the serum of patients with colorectal cancer: Correlation with the level of carcinoembryonic antigen and serum epidermal growth factor receptor

INTRODUCTION

Enzyme-linked immunosorbent assay (ELISA) was used for analysis of serum mutant p53 protein, carcinoembryonic antigen (CEA), and epidermal growth factor receptor (EGFR). Serum samples were obtained from 48 patients with colorectal cancer (CRC) and a control group of twenty healthy individuals.

RESULTS

The results demonstrated a significant increase of serum mutant p53, EGFR, and CEA levels in CRC patients compared to the control group (P<0.001 for each). Mutant p53 protein was significantly different in the different CRC grades (P=0.028). p53, CEA, and EGFR can differentiate successfully between different CRC grades and normal control (P<0.001 for each). Sensitivities of p53, CEA, and EGFR were 39.6, 31, and 71%, respectively. There was no correlation between CEA, EGFR, and p53 indicating that these variables were independent. Positive status of serum CEA and (or) p53 was found in 29 out of 48 (60%) patients. Also, positive status of serum CEA and (or) EGFR was found in 39 out of 48 (81%) patients.

CONCLUSION

Thus, the simultaneous determination of p53 or EGFR combined with the CEA may increase the sensitivity to diagnose CRC patients and may aid in disease prognosis.

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.

Have p53 gene mutations and protein expression a different biological significance in colorectal cancer?

p53 alterations are considered the most common genetic events in many types of neoplasms, including colorectal carcinoma (CRC). These alterations include mutations of the gene and/or overexpression of the protein. The aim of our study was to assess whether in 160 patients undergoing resective surgery for primary operable CRC there was an association between p53 mutations and protein overexpression and between these and other biological variables, such as cell DNA content (DNA-ploidy) and S-phase fraction (SPF), and the traditional clinicopathological variables. p53 mutations, identified by PCR-SSCP-sequencing analysis, were found in 68/160 patients (43%) and positive staining for p53 protein, detected with the monoclonal antibody DO-7, was present in 48% (77/160) of the cases, with agreement of 57% (91/160). In particular, a significant association was found between increased p53 expression and genetic alterations localized in the conserved regions of the gene or in the L3 DNA-binding domain and the specific type of mutation. Furthermore, both overexpression of p53 and mutations in the conserved areas of the gene were found more frequently in distal than in proximal CRCs, suggesting that they might be "biologically different diseases." Although p53 mutations in conserved areas were associated with flow cytometric variables, overexpression of p53 and mutations in its L3 domain were only related respectively to DNA-aneuploidy and high SPF. These data may reflect the complex involvement of p53 in the different pathways regulating cell-cycle progression. In conclusion, the combination of the mutational status and immunohistochemistry of p53, and flow cytometric data may provide an important insight into the biological features of CRCs.

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.

Mutations and allelic loss of p53 in primary tumor DNA from potentially cured patients with colorectal carcinoma

PURPOSE

To compare p53 alterations in survivors and nonsurvivors after surgery for colorectal cancer.

PATIENTS AND METHODS

Twenty-nine potentially cured patients with colorectal carcinoma, without recurrent disease for more than 6 years after their primary surgery, were selected to match a group of 41 colorectal cancer patients with early metastatic spread to the liver. All patients were screened for mutations in the p53 gene, exons 5 to 9, by denaturing gradient gel electrophoresis and subsequent sequencing.

RESULTS

The frequency of p53 mutations was significantly different in cured patients (60%) compared with patients with early relapse (41%, P <.05). A significant difference was found in the distribution of mutations, indicating that potentially cured patients had a different proportion of mutations in conserved regions of p53 (P =.02). This difference was explained by a significantly different frequency of mutations in exon 8 (40% v 15%, P =.03), which is part of the conserved region V. All mutations in region V were codon 273 mutations in cured patients, whereas three of four mutations were located in codon 273 in patients with metastatic disease. Allelic loss of p53 (loss of heterozygosity [LOH]) was demonstrated in 26% of the cured patients and in 39% of patients with metastatic disease (P =.36). The combination of mutation and LOH of p53 was the same (17%) in both groups.

CONCLUSION

A large number of p53 mutations in colorectal cancer do not promote disease progression. Some mutations, particularly within conserved regions, may even counteract negative functional effects of other p53 structural alterations. A complete loss of p53 function was not related to survival or progression after curative operation of colorectal carcinoma.

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.