Prognostic value of p53 genetic changes in colorectal cancer

The pattern-based interpretation of p53 immunohistochemical expression as a surrogate marker for TP53 mutations in colorectal cancer

Mutations in the TP53 gene, most commonly observed in colorectal cancer (CRC), play an essential role in colorectal carcinogenesis. Although p53 immunohistochemical (IHC) expression patterns have been argued to serve as an excellent surrogate marker for TP53 mutations, its performance has not been confirmed in CRC. We aimed to determine whether p53 IHC expression patterns accurately predict TP53 mutation status as examined by next-generation sequencing (NGS). We performed p53 IHC and sequencing of TP53 by NGS in 92 CRC cases with a microsatellite stable phenotype to investigate the correlation between TP53 mutation status and p53 IHC expression. The concordance between p53 IHC and TP53 mutation was 84/92 (91.3%) overall. However, 6 mutant cases were found in 39 cases with a wild-type IHC pattern. Additionally, there were two discordant cases in which an abnormal p53 IHC pattern (overexpression or cytoplasmic pattern) was found, while NGS detected wild-type p53. Therefore, the optimized p53 IHC performs well and serves as a surrogate test for TP53 mutation in CRC cases. Furthermore, it demonstrates excellent reproducibility between two independent experienced pathologists and may have novel clinical utility for molecular classification algorithms in CRC. We suggest that the four-tier classification of p53 IHC patterns is helpful to evaluate molecular colorectal carcinogenesis.

Rise of the natural red pigment 'prodigiosin' as an immunomodulator in cancer

Cancer is a heterogeneous disease with multifaceted drug resistance mechanisms (e.g., tumour microenvironment [TME], tumour heterogeneity, and immune evasion). Natural products are interesting repository of bioactive molecules, especially those with anticancer activities. Prodigiosin, a red pigment produced by Serratia marcescens, possesses inherent anticancer characteristics, showing interesting antitumour activities in different cancers (e.g., breast, gastric) with low or without harmful effects on normal cells. The present review discusses the potential role of prodigiosin in modulating and reprogramming the metabolism of the various immune cells in the TME, such as T and B lymphocytes, tumour-associated macrophages (TAMs), natural killer (NK) cells, and tumour-associated dendritic cells (TADCs), and myeloid-derived suppressor cells (MDSCs) which in turn might introduce as an immunomodulator in cancer therapy.

Isotypic analysis of anti-p53 serum autoantibodies and p53 protein tissue phenotypes in colorectal cancer

The presence of IgA- and IgM-specific autoantibody (AAb) isotypes and their relationship to p53 tissue expression patterns are not well understood. This study aims to investigate the clinical utility of the anti-p53 AAb isotypes and tissue positivity in colorectal cancer (CRC). We analysed anti-p53 IgG, IgM, and IgA AAbs in sera of 99 CRC patients and 99 non-cancer control subjects. Corresponding tissue expression of the p53 protein was evaluated by immunohistochemistry (IHC). Anti-p53 AAbs of the IgG isotype were present in the sera of 21 out of 99 patients (21%), while IgM AAbs were observed in 9 (9%) and IgA in 2 (2%) CRC patients. Anti-p53 AAbs of all three isotypes were generally associated with IHC staining indicative of mutated TP53. Seropositive anti-p53 IgM cases in the absence of anti-p53 IgG were linked to wild-type p53. Anti-p53 IgA in the absence of IgG AAbs was detected in two non-cancer controls indicating a potential p53 epitope mimicry. Although seropositivity was not associated with patient survival (P = 0.650), mutant-pattern p53 tissue expression was associated with reduced 5-year overall survival (P = 0.032), however, it was not an independent prognostic marker (Multivariate Cox regression, P = 0.193). In conclusion, immunoglobulin isotyping revealed that anti-p53 IgM and IgA AAbs were predominantly concurrent with anti-p53 serum IgG and the mutant-pattern p53 tissue phenotype. IgM and IgA seropositive cases in absence of anti-p53 IgG were linked to wild-type p53 tissue phenotype indicating early anti-p53 immune responses preceding isotype class-switch (IgM) or p53 antigen mimicry (IgA).

Prognostic Value of Immunohistochemical Markers for Locally Advanced Rectal Cancer

The aim of this study is to reveal the potential roles of apoptosis markers (Bcl2 and p53), proliferation markers (Ki-67 and CyclD1), and the neuroendocrine marker Chromogranin A as markers for the radioresistance of rectal cancer. Statistically significant differences were found in the expression of p53, Ki-67, and Chromogranin A in groups of patients with and without a favorable prognosis after radiotherapy. The survival analysis revealed that the marker of neuroendocrine differentiation, Chromogranin A, also demonstrated a high prognostic significance, indicating a poor prognosis. Markers of proliferation and apoptosis had no prognostic value for patients who received preoperative radiotherapy. Higher Chromogranin A values were predictors of poor prognosis. The results obtained from studying the Chromogranin A expression suggest that the secretion of biologically active substances by neuroendocrine cells causes an increase in tumor aggressiveness.

The Role of p53 Expression in Patients with RAS/BRAF Wild-Type Metastatic Colorectal Cancer Receiving Irinotecan and Cetuximab as Later Line Treatment

Background

Preclinical and clinical data indicate that p53 expression might modulate the activity of the epidermal growth factor receptor (EGFR), influencing response/resistance to anti-EGFR monoclonal antibodies. However, the association between p53 status and clinical outcome has not been clarified yet.

Objective

In our study, we evaluated the role of p53 expression in patients with RAS/BRAF wild-type metastatic colorectal cancer (mCRC) receiving irinotecan/cetuximab in an exploratory and a validation cohort.

Patients and Methods

p53 expression was analysed in patients with RAS/BRAF wild-type mCRC receiving second-line or third-line irinotecan/cetuximab. Survival distribution was assessed by the Kaplan–Meier method, while the log-rank test was used for survival comparison.

Results

Among 120 patients with RAS/BRAF wild-type mCRC included in our analysis, 52 (59%) and 19 (59%) patients showed p53 overexpression in the exploratory and validation cohort, respectively. In the exploratory cohort, low p53 expression was correlated with better median progression-free survival (hazard ratio 0.39; p < 0.0001), median overall survival (hazard ratio: 0.23; p < 0.0001) and response rate (p < 0.0001). These results were confirmed by data of the validation cohort where we observed better median progression-free survival (hazard ratio: 0.48; p = 0.0399), median overall survival (hazard ratio: 0.26; p = 0.0027) and response rate (p =0.0007) in patients with p53 normal expression mCRC.

Conclusions

In our study, p53 overexpression was associated with anti-EGFR treatment resistance in patients with RAS/BRAF WT mCRC, as confirmed in a validation cohort. Larger studies are needed to validate the role of p53 and investigate EGFR cross-talk in these patients.

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.

Significance of Serum p53 Antibody as a Tumor Marker in Colorectal Cancer

Objective

We examined serum anti-p53 antibodies (S-p53Ab) in colorectal cancer. Specifically, we retrospectively investigated the use of S-p53Ab as a prognostic marker after surgery for colorectal cancer.

Materials and Methods

The levels of S-p53Ab, carcinoembryonic antigen (CEA), and carbohydrate antigen 19-9 (CA19-9) were measured in 160 colorectal cancer patients who underwent surgical treatment. The rate of postoperative change (RPC) in the S-p53Ab titer was calculated as [subsequent antibody titer-lowest titer]/lowest titer.

Results

A relationship between recurrence and RPC in the S-p53Ab titer was not observed in patients who tested negative for S-p53Ab preoperatively. In addition, no patients, who tested negative for S-p53Ab preoperatively, tested positive for S-p53Ab at the follow-up after surgery. Of the patients who tested positive for S-p53Ab preoperatively, those recurrences had a significantly higher RPC compared with those who did not (p < 0.001).

Conclusions

Although S-p53Ab is not a significant tumor marker in patients who test negative preoperatively, increases in the S-p53Ab titer should be continuously monitored and measured in patients who are positive for this antibody preoperatively, regardless of whether they later test negative.

TP53 is not a prognostic marker-clinical consequences of a generally disregarded fact

Technological progress within the last 15-20 years has significantly increased our knowledge about the molecular basis of cancer development, tumor progression, and treatment response. As a consequence, a vast number of biomarkers have been proposed, but only a small fraction of them have found their way into clinical use. The aim of this paper is to describe the specific demands a clinically relevant biomarker should meet and how biomarkers can be tested stepwise. We name this procedure the "triple-R principle": robustness, reproducibility, and relevance. The usefulness of this principle is illustrated with the marker TP53. Since it is mutated in a broad spectrum of cancer entities, TP53 can be considered a very promising marker. Thus, TP53 has been studied in detail but there is still no explicit consensus about its clinical value. By considering our own experience and reviewing the literature, we demonstrate that a major problem of current biomarker research is disregard of whether the biomarker is prognostic or predictive. As an example, it is demonstrated that TP53 is not a prognostic marker, but rather a purely predictive marker, and that disregard of this fact has made this otherwise strong biomarker appear as not being clinically useful so far.

Current Tissue Molecular Markers in Colorectal Cancer: A Literature Review

BACKGROUND

Colorectal cancer (CRC) is one of the most spread neoplasia types all around the world, especially in western areas. It evolves from precancerous lesions and adenomatous polyps, through successive genetic and epigenetic mutations. Numerous risk factors intervene in its development and they are either environmental or genetic.

AIM OF THE REVIEW

Alongside common screening techniques, such as fecal screening tests, endoscopic evaluation, and CT-colonography, we have identified the most important and useful biomarkers and we have analyzed their role in the diagnosis, prevention, and prognosis of CRC.

CONCLUSION

Biomarkers can become an important tool in the diagnostic and therapeutic process for CRC. But further studies are needed to identify a noninvasive, cost-effective, and highly sensible and specific screening test for their detection and to standardize their use in clinical practice.

Correlation of p53 Overexpression with the Clinicopathological Prognostic Factors in Colorectal Adenocarcinoma

INTRODUCTION

Mutation in p53 gene and accumulation of p53 protein is a common genetic event in colorectal carcinomas. p53 mutation can be detected by various techniques such as DNA sequencing, polymerase chain reaction and immunohistochemistry (IHC). However, IHC is simple and is consistent with other techniques.

AIM

To establish a correlation between overexpression of p53 with the clinical features, tumour histopathology and stage of Colorectal Carcinoma (CRC).

MATERIALS AND METHODS

This prospective and retrospective study of clinical, histopathological and IHC features of CRC was conducted on colectomy and abdomino-perineal resection specimens received from January 2008 to June 2013. For each case, the clinical features, tumour morphology and p53 status (by IHC) were evaluated.

RESULTS

The most common histologic type of CRC was Non-Specific Type (NST) and grade II tumours were seen predominantly (60%). Overall, 67.5% of CRCs showed p53 positivity on IHC. Intense p53 positivity was observed in 37.5% of CRCs of NST type and 33.3% of mucinous adenocarcinomas showed moderate positivity. Grade III tumours showed variable p53 positivity and those with lymph node metastasis showed moderate (55.6%) or intense positivity (53.8%). But there was no statistically significant correlation of p53 status and various clinicopathological prognostic factors.

CONCLUSION

As p53 protein overexpression is seen in a relatively high percentage of CRCs, it seems that p53 mutation plays an important role in development of CRC. However, no direct correlation could be established between p53 results and the patients' age, sex, tumour site, size, histological type, grade, lymph node status, or TNM stage. A prolonged follow up is necessary to conclude whether p53 status has any influence on the long, term prognosis and patient survival.

Predictive and prognostic biomarkers in colorectal cancer: A systematic review of recent advances and challenges

BACKGROUND

Colorectal cancer (CRC) is one of the leading cause of cancer deaths worldwide. Since CRC is largely asymptomatic until alarm features develop to advanced stages, the implementation of the screening programme is very much essential to reduce cancer incidence and mortality rates. CRC occurs predominantly from accumulation of genetic and epigenetic changes in colon epithelial cells, which later gets transformed into adenocarcinomas.

SCOPE OF REVIEW

The current challenges of screening paradigm and diagnostic ranges are from semi-invasive methods like colonoscopy to non-invasive stool-based test, have resulted in over-diagnosis and over-treatment of CRC. Hence, new screening initiatives and deep studies are required for early diagnosis of CRC. In this regard, we not only summarise current predictive and prognostic biomarkers with their potential for diagnostic and therapeutic applications, but also describe current limitations, future perspectives and challenges associated with the progression of CRC.

MAJOR CONCLUSIONS

Currently many potential biomarkers have already been successfully translated into clinical practice eg. Fecal haemoglobin, Carcinoembryonic antigen (CEA) and CA19.9, although these are not highly promising diagnostic target for personalized medicine. So there is a critical need for reliable, minimally invasive, highly sensitive and specific genetic markers of an individualised and optimised patient treatment at the earliest disease stage possible.

GENERAL SIGNIFICANCE

Identification of a new biomarker, or a set of biomarkers to the development of a valid, and clinical sensible assay that can be served as an alternative tool for early diagnosis of CRC and open up promising new targets in therapeutic intervention strategies.

Impact of EGFR and p53 expressions on survival and quality of life in locally advanced oral squamous cell carcinoma patients treated with chemoradiation

EGFR and p53 are molecular markers which play important role in tumor progression and development. The objective of this study was to assess the association between EGFR and p53 expression and survival, and to determine whether EGFR and p53 expression levels were associated with differences quality of life in OSCC patients undergoing chemoradiation. A total of 120 OSCC patients aged 20-67 y and stage III/IV were recruited. Treatment response was assessed according to W.H.O. (1979). EGFR and p53 expression in tumor tissue was estimated by immunohistochemical (IHC) method and quantified as percentage positive nuclei. Molecular marker expressions of both EGFR and p53 were found significantly (P < 0.01 or P < 0.001) associated with overall response, survivals and quality of life. Neither EGFR nor p53 expression was associated with hematologic or non-hematologic toxicity. EGFR and p53 molecular marker expressions may have significant association with survival and QOL in OSCC patients undergoing chemoradiation.

MEK plus PI3K/mTORC1/2 Therapeutic Efficacy Is Impacted by TP53 Mutation in Preclinical Models of Colorectal Cancer

PURPOSE

PI3K pathway activation occurs in concomitance with RAS/BRAF mutations in colorectal cancer, limiting the sensitivity to targeted therapies. Several clinical studies are being conducted to test the tolerability and clinical activity of dual MEK and PI3K pathway blockade in solid tumors.

EXPERIMENTAL DESIGN

In the present study, we explored the efficacy of dual pathway blockade in colorectal cancer preclinical models harboring concomitant activation of the ERK and PI3K pathways. Moreover, we investigated if TP53 mutation affects the response to this therapy.

RESULTS

Dual MEK and mTORC1/2 blockade resulted in synergistic antiproliferative effects in cell lines bearing alterations in KRAS/BRAF and PIK3CA/PTEN. Although the on-treatment cell-cycle effects were not affected by the TP53 status, a marked proapoptotic response to therapy was observed exclusively in wild-type TP53 colorectal cancer models. We further interrogated two independent panels of KRAS/BRAF- and PIK3CA/PTEN-altered cell line- and patient-derived tumor xenografts for the antitumor response toward this combination of agents. A combination response that resulted in substantial antitumor activity was exclusively observed among the wild-type TP53 models (two out of five, 40%), but there was no such response across the eight mutant TP53 models (0%). Interestingly, within a cohort of 14 patients with colorectal cancer treated with these agents for their metastatic disease, two patients with long-lasting responses (32 weeks) had TP53 wild-type tumors.

CONCLUSIONS

Our data support that, in wild-type TP53 colorectal cancer cells with ERK and PI3K pathway alterations, MEK blockade results in potent p21 induction, preventing apoptosis to occur. In turn, mTORC1/2 inhibition blocks MEK inhibitor-mediated p21 induction, unleashing apoptosis. Clin Cancer Res; 21(24); 5499-510. ©2015 AACR.

Serum anti-p53 antibody as a tumour marker for colorectal cancer screening

A 60-year-old Japanese man presented to our hospital for further investigation of an elevated serum anti-p53 antibody level. He was diagnosed with colon cancer and the tumour was surgically resected. Histological diagnosis of advanced colon cancer without lymph node involvement or distant metastasis was made. It was noteworthy that both serum carcinoembryonic antigen (CEA) and a fecal occult blood test that were performed preoperatively were non-diagnostic. This case highlights the potential usefulness of serum anti-p53 antibody tests for detection of colorectal cancers. Moreover, sequential changes in the anti-p53 antibody levels after curative resection were observed.

Durable clinical benefit to trastuzumab and chemotherapy in a patient with metastatic colon adenocarcinoma harboring ERBB2 amplification

Somatic ERBB2 amplification or activating mutations occur in approximately 2-5% of metastatic colorectal adenocarcinomas and are presumed to be oncogenic drivers, but limited evidence exists to suggest these lesions are sensitive to targeted monotherapy in patients. Here we present the case of a patient with advanced CRC with pulmonary metastases, who had progressed on both standard of care cytotoxic chemotherapy and anti-EGFR targeted therapy. Comprehensive genomic profiling (FoundationOne(®)) identified amplification of ERBB2 and a TP53 mutation in the metastatic lesion. Treatment with trastuzumab with a chemotherapy backbone elicited stable disease/minor response in the patient over a one year course of therapy, reducing tumor burden and significantly improving quality of life. This report demonstrates the application of personalized targeted therapy guided by comprehensive genomic profiling in metastatic colorectal adenocarcinoma.

Correlation between expressions of Cyclin-D1, EGFR and p53 with chemoradiation response in patients of locally advanced oral squamous cell carcinoma

Introduction

Cyclin-D1, p53 and EGFR are molecular markers that regulate the cell cycle and play an important role in tumor progression and development. The present study evaluates the prognostic significance of these markers with chemoradiation response in patients of locally advanced oral squamous cell carcinoma (OSCC).

Material and method

A total of 97 OSCC patients (females = 19 and males = 78), aged 20–67 years and stage III/IV were recruited. Treatment response was assessed according to WHO criteria. Cyclin-D1, p53 and EGFR expressions in tumor tissue was estimated by immunohistochemical (IHC) method and quantified as percentage positive nuclei.

Results

The positive expression rates of molecular markers were 86.6% for Cyclin-D1, 92.8% for EGFR and 85.6% for p53. The strong positive expressions of both Cyclin-D1 and p53 showed significant association with poor response. The Cox multivariate regression analysis showed coexpressions of Cyclin-D1 and p53 a significant and independent predictor of overall survival (OR = 1.90, 95% CI = 1.45–4.82, p = 0.046) after adjusting the demographic, clinicopathological and radiological response. The strong positive expressions of Cyclin-D1 and p53 and coexpressions of Cyclin-D1, EGFR and p53 showed significant (p < 0.05 or p < 0.01 or p < 0.001) and lower survival as compared to negative or moderate positive expressions and coexpressions, respectively.

Conclusion

Expressions and coexpressions of Cyclin-D1 and p53 may serve as a prognostic marker in OSCC patients.

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Cyclin-D1, p53 and EGFR are molecular markers that regulate the cell cycle.

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Coexpressions of Cyclin-D1, EGFR & p53 serve as prognostic marker in advanced OSCC.

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p53 alone may serve as prognostic marker in patients of locally advanced OSCC.

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.

Prodigiosin rescues deficient p53 signaling and antitumor effects via upregulating p73 and disrupting its interaction with mutant p53

p53 reactivation offers a broad-based strategy for cancer therapy. In this study, we report the identification of prodigiosin that can reactivate p53 family-dependent transcriptional activity in p53-deficient human colon cancer cells. Prodigiosin and its structural analogue (compound R) induced the expression of p53 target genes accompanied by cell-cycle arrest and apoptosis in p53-deficient cancer cells. Prodigiosin restored p53 signaling in cancer cells harboring hotspot TP53 mutations, with little to no detectable cytotoxicity in normal human fibroblasts and with no genotoxicity. Prodigiosin induced the expression of p73 and disrupted its interaction with mutant p53, thereby rescuing p53 pathway deficiency and promoting antitumor effects. The disruption of mutant p53/p73 interaction was specific to prodigiosin and not related to mTOR inhibition. Our findings suggest that mutant p53 needs to be targeted in the context of p73 stimulation to allow efficient restoration of the p53 pathway. In exhibiting this capability, prodigiosin and its analogue provide lead compounds to rescue deficiencies in the p53 pathway in cancer cells by upregulating p73 and targeting mutant p53/p73 interaction there.

Molecular genetics of adult grade II gliomas: towards a comprehensive tumor classification system

Adult grade II low-grade gliomas (LGG) are classified according to the WHO as astrocytomas, oligodendrogliomas or mixed gliomas. TP53 mutations and 1p19q codeletion are the main molecular abnormalities recorded, respectively, in astrocytomas and oligodendrogliomas and in mixed gliomas. Although IDH mutations (IDH1 or IDH2) are recorded in up to 85 % of low-grade gliomas, IDH negative gliomas do occur. We have searched for p53 expression, 1p19q codeletion and IDH status (immunohistochemical detection of the common R132H IDH1 mutation and IDH direct sequencing). Internexin alpha (INA) expression previously recorded to be associated with 1p19q codeletion (1p19q+) gliomas was also analysed. Low-grade gliomas were accurately classified into four groups: group 1, IDH+/p53-/1p19q-; group 2, IDH+/p53-/1p19q+; group 3, IDH+/p53+/1p19q-; and group 4, triple negative gliomas. In contrast to the WHO classification, this molecular classification predicts overall survival on uni- and multivariate analysis (P = 0.001 and P = 0.007, respectively). Group 4 carries the worst prognosis and group 2 the best. Interestingly, p53 +/INA- expression predicts lack of 1p19q codeletion (specificity 100 %, VPP 100 %). The combined use of these three molecular markers allow for an accurate prediction of survival in LGG. These findings could significantly modify LGG classification and may represent a new tool to guide patient-tailored therapy. Moreover, immunohistochemical detection of p53, INA and mR132H IDH1 expression could represent an interesting prescreening test to be performed before 1p19q codeletion, IDH1 minor mutation and IDH2 mutation detection.

Prognostic significance and gene expression profiles of p53 mutations in microsatellite-stable stage III colorectal adenocarcinomas

Although the prognostic value of p53 abnormalities in Stage III microsatellite stable (MSS) colorectal cancers (CRCs) is known, the gene expression profiles specific to the p53 status in the MSS background are not known. Therefore, the current investigation has focused on identification and validation of the gene expression profiles associated with p53 mutant phenotypes in MSS Stage III CRCs. Genomic DNA extracted from 135 formalin-fixed paraffin-embedded tissues, was analyzed for microsatellite instability (MSI) and p53 mutations. Further, mRNA samples extracted from five p53-mutant and five p53-wild-type MSS-CRC snap-frozen tissues were profiled for differential gene expression by Affymetrix Human Genome U133 Plus 2.0 arrays. Differentially expressed genes were further validated by the high-throughput quantitative nuclease protection assay (qNPA), and confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) and by immunohistochemistry (IHC). Survival rates were estimated by Kaplan-Meier and Cox regression analyses. A higher incidence of p53 mutations was found in MSS (58%) than in MSI (30%) phenotypes. Both univariate (log-rank, P = 0.025) and multivariate (hazard ratio, 2.52; 95% confidence interval, 1.25-5.08) analyses have demonstrated that patients with MSS-p53 mutant phenotypes had poor CRC-specific survival when compared to MSS-p53 wild-type phenotypes. Gene expression analyses identified 84 differentially expressed genes. Of 49 down-regulated genes, LPAR6, PDLIM3, and PLAT, and, of 35 up-regulated genes, TRIM29, FUT3, IQGAP3, and SLC6A8 were confirmed by qNPA, qRT-PCR, and IHC platforms. p53 mutations are associated with poor survival of patients with Stage III MSS CRCs and p53-mutant and wild-type phenotypes have distinct gene expression profiles that might be helpful in identifying aggressive subsets.

Impact of codon 72 Arg > Pro single nucleotide polymorphism in TP53 gene in the risk of kangri cancer: a case control study in Kashmir

Kangri cancer found only in Kashmir (north India) is a unique thermally induced squamous cell carcinoma of the skin that develops because of chronic and persistent irritation due to the use of a kangri (a brazier) by the Kashmiri people to combat the chilling cold temperature during winter. Being unique to this region, the molecular etiology of the invasive kangri cancer is not known fully. The TP53 gene, codon 72 polymorphism (Arg72Pro), has been found to be associated with cancer susceptibility but has not been investigated in kangri cancer risk. A case control study was conducted to find the genotype distribution of TP53 Arg72Pro SNP and to elucidate the possible role of this SNP as risk factor in kangri cancer development. Using the polymerase chain reaction-restriction fragment length polymorphism approach, we tested the genotype distribution of 106 kangri cancer patients in comparison with 200 cancer-free controls from the same geographical region. A significant difference was observed between the control and kangri cancer patients with odds ratio = 2.02 and 95% confidence interval = 1.2-3.3 (p = 0.01). Interestingly, the proline form was abundantly observed in advanced-grade tumors (p < 0.05). We also found a significant association of the variant allele (GC + CC) with male subjects and patients >45 years of age (p < 0.05). Thus, it is evident from our study that Arg72Pro SNP is implicated in kangri cancer and that the rare, proline-related allele is connected with higher susceptibility to kangri cancer.

Locally advanced rectal cancer: from molecular profiling to clinical practice. A literature review: Part 2

Colorectal cancer is the third most common cause of cancer deaths worldwide. The management of rectal cancer has undergone, and continues to undergo, significant evolutions. In the last two decades, new multimodality strategies have been developed. The ability to predict tumor response before treatment could significantly impact the selection of patients for preoperative combined-modality therapy, as well as potentially modify postoperative treatment plans. The present review analyzes the new molecular targets that could be involved in predicting response and prognosis.

Relationship of p53 overexpression on cancers and recognition by anti-p53 T cell receptor-transduced T cells

Tumor suppressor p53 is reported to be an attractive immunotherapy target because it is mutated in approximately half of human cancers, resulting in inactivation and often an accumulation of the protein in the tumor cells. Only low amounts of protein are detectable in normal tissues. The differential display of antigen in normal versus tumor tissues has been reported to create an opportunity to target p53 by immunotherapy. We sought to determine the relationship between p53 expression and its recognition by cognate T cells in human tumors including common epithelial malignancies. Inasmuch as nonsense or missense p53 mutations may disrupt processing and presentation, we studied tumors with either identified wild-type or mutated p53, based on our gene-sequencing studies or published data. T cells transduced with a high-affinity, p53(264-272)-reactive T cell receptor (TCR) derived from HLA-A2.1 transgenic mice recognized a wide panel of human tumor lines. There was no significant correlation between p53 expression in tumors and recognition by the anti-p53 TCR-transduced T cells. This conclusion was based on the study of 48 cell lines and is in contrast to several prior studies that used only a limited number of selected cell lines. A panel of normal cells was evaluated for recognition, and some of these populations were capable of stimulating anti-p53 T cells, albeit at low levels. These studies raise doubts concerning the suitability of targeting p53 in the immunotherapy of cancer patients.

Prognostic significance of p53 codon 72 polymorphism differs with race in colorectal adenocarcinoma

PURPOSE

Several studies have examined the prognostic value of the codon 72 polymorphism of the p53 gene in colorectal adenocarcinoma, but none have addressed patient race/ethnicity. Therefore, this study assessed the prognostic value of this polymorphism in African American and Caucasian colorectal adenocarcinoma patients separately.

EXPERIMENTAL DESIGN

Colorectal adenocarcinomas from 137 African Americans and 236 non-Hispanic Caucasians were assessed for p53 mutations and genotyped for the codon 72 polymorphism. The phenotypes were correlated with p53 mutational status, clinicopathologic features, and patient survival using the chi(2) test and Kaplan-Meier and Cox regression models.

RESULTS

The incidence of p53 mutations was similar in African American and Caucasian patients (50% versus 54%, respectively); however, the homozygous Pro72 allele frequency was higher in African Americans (17%) as compared with Caucasians (7%). In contrast, the homozygous Arg72 allele frequency was higher in Caucasians (36%) than in African Americans (19%). In African Americans but not Caucasians, the Pro/Pro phenotype significantly correlated with a higher incidence of missense p53 mutations and with nodal metastasis. African Americans, but not Caucasians, with the Pro/Pro phenotype had significantly higher mortality (log-rank P = 0.005 versus. P = 0.886) and risk of death due to colorectal adenocarcinoma (hazard ratio, 2.15; 95% confidence interval, 1.02-4.53 versus hazard ratio, 1.60; 95% confidence interval, 0.69-3.18) than those with the phenotype Arg/Arg or Arg/Pro.

CONCLUSIONS

The higher frequency of the Pro/Pro phenotype of p53 in African American patients with colorectal adenocarcinoma is associated with an increased incidence of p53 mutations, with advanced tumor stage, and with short survival.

Molecular gate keepers succumb to gene aberrations in colorectal cancer in Kashmiri population, revealing a high incidence area

BACKGROUND/AIM

Colorectal cancer (CRC) is one of the leading malignancies worldwide and has been reported to show geographical variation in its incidence, even within areas of ethnic homogeneity. The aim of this study was to identify p53 and K-ras gene mutations in CRC patients in a Kashmiri population, and to assess whether these mutations are linked with clinicopathological parameters.

MATERIALS AND METHODS

Paired tumor and normal tissue samples from a consecutive series of 53 patients undergoing resective surgery for CRC were prospectively studied for p53 and K-ras gene mutations by PCR/single strand conformation polymorphism (SSCP).

RESULTS

Less than half (45%, 19/42) of the patients presented mutations in the p53 gene. Twenty eight mutations were found in the p53 gene, which comprised of 23 substitutions (17 transitions + 6 transversions), and five insertions. The 23 substitutions constituted 18 missense mutations, two nonsense mutations, and three silent mutations. Of the 28 mutations (7.14%) observed in this study, 2 were not previously reported for CRC samples and were identified as novel p53 mutations. A few patients (22.64%, 12/53) presented with mutations in K-ras, constituting 13 missense mutations, out of which 11 were G-->A transitions, one was a G-->C transversion, and one a G-->T transversion. More than half (61.5%) of the mutations occurred in codon 12 whereas a few (38.5%) occurred in codon 13. One tumor contained missense mutations in both codons. Comparison of the mutation profiles of our patients with those of other ethnic populations and regions reflected both differences and similarities, indicating co-exposure to a unique set of risk factors.

CONCLUSION

Mutations of the p53 and K-ras genes are some of the most common genetic changes in the development of human CRC. The high frequency of p53 gene mutations implicates p53 as a predominant factor for CRC in the high-risk ethnic Kashmiri population.

Distinct pattern of mutations of conserved regions of TP53 in colorectal cancer patients in the Kashmir population: an emerging high-risk area

Background:

Colorectal cancer (CRC) is one of the leading causes of mortality and morbidity. The Kashmir valley, in Northern India, has been described as a high-risk area for colorectal cancer.

Aim:

The aim was to make a preliminary attempt to study mutations in exons 5–8 (the DNA binding domain) of the tumour suppressor gene TP53 in 42 CRC patients from Kashmir.

Materials and methods:

The study population consisted of 42 patients diagnosed with colorectal cancer. Mutations in exons 5–8 of the TP53 gene were detected by means of single-strand conformation polymorphism (SSCP). All samples that showed different band migration patterns in the SSCP were confirmed by sequencing.

Results:

The 28 mutations were found in the TP53 gene in 19 patients, comprised 23 substitutions (17 transitions + six transversions), and five insertions. The 23 substitutions represent 18 missense mutations, leading to amino acid substitutions, two nonsense mutations, leading to stop codons, while the remaining three were silent mutations. The five insertions represented frameshifts. Two of 28 mutations (7.14%) have not been previously reported in colon cancer samples and were identified as novel TP53 mutations. Comparison of the mutation profile with other ethnic populations and regions reflected both differences and similarities indicating co-exposure to a unique set of risk factors.

Conclusions:

Mutation of the TP53 gene is one of the commonest genetic changes in the development of human colorectal cancer. The high frequency of TP53 gene mutations implicates TP53 as a predominant factor for colorectal cancer in the high-risk ethnic Kashmir population.

Evaluation of the immunoexpression of COX-1, COX-2 and p53 in Crohn's disease

BACKGROUND: Crohn's disease accompanied by nonspecific or idiopathic ulcerative proctocolitis corresponds to a condition called intestinal inflammatory disease. The immunoexpression of cyclooxygenase 2 (COX-2) in Crohn's disease becomes more marked with progression of the disease and the presence of wild-type p53 suppresses the transcription of COX-2. AIMS: To investigate the immunoexpression of cyclooxygenase 1 (COX-1), COX-2 and p53 in Crohn's ileocolitis and to correlated this expression with clinical and histopathological parameters. METHODS: Forty-five cases of Crohn's disease, 16 cases of actinic colitis (diseased-control group) and 11 cases without a history of intestinal disease (normal control group) were studied. Hematoxylin-eosin-stained sections were submitted to histopathological analysis and the immunohistochemical expression of COX-1, COX-2 and p53 was evaluated by the streptavidin-biotin-peroxidase method. RESULTS: Sixty percent of the Crohn's disease patients were women and 40% were men, with 75.5% whites and 25.5% non-whites. The disease involved the terminal ileum in 44.5% of cases, ileum in 33.3%, colon in 20% and duodenum-ileum in 2.2%. A significant association was observed between COX-2 immunoreactivity and age <40 years. Histopathological analysis of Crohn's disease samples showed mild or moderate crypt distortion (57.8% and 35.6% of cases), atrophy (6.6%), mild, moderate and marked chronic inflammation (46.7%, 26.7% and 20%), acute inflammatory activity (93.3%), ulceration (24.4%), mucin depletion (37.8%), Paneth's cells (24.4%), intraepithelial lymphocytes (93.3%), and subepithelial collagen (6.7%). In the CD group, COX-1 immunoreactivity in epithelial and inflammatory cells was observed in 26.7% and 22.2% of cases, respectively. COX-2 immunoreactivity was detected in epithelial cells in 68.9% of cases and in inflammatory cells in 46.7%. A marginal difference in COX-2 reactivity was observed between epithelial and inflammatory cells in association with acute inflammatory activity and increase in intraepithelial lymphocytes. Comparison of the date among the threes groups (Crohn's disease, actinic colitis and normal controls) showed a higher proportion of cases presenting COX-2 immunoreactivity in inflammatory cells in the Crohn's disease group. No p53 reactivity was observed in all cases. CONCLUSIONS: COX-2 immunoexpression is high in Crohn's disease, which suggest a possible role of the protein in the pathogenesis of the inflammation. The absence of epithelial dysplasia in all Crohn's disease samples was correlated with the lack of expression of p53.

Poorer outcome in stromal HIF-2 alpha- and CA9-positive colorectal adenocarcinomas is associated with wild-type TP53 but not with BNIP3 promoter hypermethylation or apoptosis

Stromal expression of hypoxia inducible factor 2α (HIF-2α) and carbonic anhydrase 9 (CA9) are associated with a poorer prognosis in colorectal cancer (CRC). Tumour cell death, regulated by a hypoxic stromal microenvironment, could be of importance in this respect. Therefore, we correlated apoptosis, TP53 mutational status and BNIP3 promoter hypermethylation of CRC cells with HIF-2α- and CA9-related poor outcome. In a series of 195 CRCs, TP53 mutations in exons 5–8 were analysed by direct sequencing, and promoter hypermethylation of BNIP3 was determined by methylation-specific PCR. Expressions of HIF-2α, CA9, p53, BNIP3 and M30 were analysed immunohistochemically. Poorer survival of HIF-2α and CA9 stromal-positive CRCs was associated with wild-type TP53 (P=0.001 and P=0.0391), but not with BNIP3 methylation. Furthermore, apoptotic levels were independent of the TP53 status, but lower in unmethylated BNIP3 CRCs (P=0.004). It appears that wild-type TP53 in CRC cells favours the progression of tumours expressing markers for hypoxia in their stroma, rather than in the epithelial compartment. Preserved BNIP3 function in CRC cells lowers apoptosis, and may thus be involved in alternative cell death pathways, such as autophagic cell death. However, BNIP3 silencing in tumour cells does not impact on hypoxia-driven poorer prognosis.

These results suggest that the biology of CRC cells can be modified by alterations in the tumour microenvironment under conditions of tumour hypoxia.

Expression of P53, P27 and KI-67 in colorectal cancer patients of various ethnic origins: clinical and tissue microarray based analysis

BACKGROUND

This study was conducted to determine survival according to the expression of molecular markers in colorectal cancer (CRC) patients of various ethnic origins.

METHODS

Resection of primary tumor was conducted on 171 patients with CRC. Corresponding archived paraffin-embedded blocks were retrieved and tissue microarray (TMA) constructed. Immunohistochemical staining of the TMA for p53, p27 and Ki-67 was quantified by two independent pathologists. Survival was analyzed using the Kaplan-Meier product limit method.

RESULTS

With a median follow-up of 65 months, 56 patients (32.7%) died of disease. AJCC stage correlated with disease-free (DFS, P < 0.0001) and overall survival (OS, P < 0.0001). IHC staining was positive for Ki-67 in 77.4%, p53 in 55.8% and p27 in 54.2% of patients. Primary tumor marker expression did not correlate with DFS or OS. The 5-year DFS for Ashkenazi Jews was 75%, significantly higher than Sephardic Jews (SJ) 64% and Palestinian Arabs (PA) 38%, P = 0.001.

CONCLUSIONS

Ethnicity among Ashkenazi and SJ and PA appears to have a significant impact on disease outcome in patients with CRC patients, while primary tumor expression of p53, p27 and Ki-67 was unrelated to disease outcome.

Anti-p53 autoantibody in colorectal cancer: prognostic significance in long-term follow-up

BACKGROUND

The prognostic significance of anti-53 autoantibody in colorectal cancer (CRC) patients is unclear due to measurement of overall rather than disease-specific survival and generally short follow-up periods in many studies. We aim to investigate prognostic significance of anti-p53 auto-antibodies in a study with long-term follow-up (minimum 5 years).

METHODS

ELISA for anti-p53 autoantibody was assayed in serum from 92 patients with CRC and 28 controls.

RESULTS

Anti-p53 autoantibody was found in 20 patients (21.7%) and none of the controls. No difference in Dukes' (A/B vs. C/D), Stage (I/II vs. III/IV), T1/2 vs. T3/4, N0 vs. N1/2, M0 vs. M1, poor vs. well/moderate differentiation and proximal vs. distal CRC was observed. Median overall survival was 62 months and median disease-specific survival was 73 months. Dukes' C/D, Stage III/IV, N1/2 and M1 were associated with poor disease-specific survival in univariate analysis. Stage III/IV was an independent prognostic factor in overall and disease-free survival in multivariate analysis. Anti-p53 autoantibody sero-positivity did not influence overall (p = 0.980) or disease-specific survival (p = 0.874). Median overall survival in anti-p53 autoantibody positive patients was 62 months vs. 60 months in anti-53 autoantibody negative patients. Median disease-specific survival in anti-p53 autoantibody positive patients was 73 months vs. 82 months.

CONCLUSION

Anti-p53 autoantibody is not related to clinical parameters of CRC and has no prognostic significance in long-term follow-up.

Specific TP53 and/or Ki-ras mutations as independent predictors of clinical outcome in sporadic colorectal adenocarcinomas: results of a 5-year Gruppo Oncologico dell'Italia Meridionale (GOIM) prospective study

BACKGROUND

Although Ki-ras and TP53 mutations have probably been the genetic abnormalities most exhaustively implicated and studied in colorectal cancer (CRC) progression, their significance in terms of disease relapse and overall survival has not yet clearly been established.

PATIENTS AND METHODS

A prospective study was carried out on paired tumor and normal colon tissue samples from a consecutive series of 160 previously-untreated patients, undergoing resective surgery for primary operable sporadic CRC. Mutations within the TP53 (exons 5-8) and Ki-ras (exon 2) genes were detected by PCR-SSCP analyses following sequencing.

RESULTS

Mutation analyses of exons 5 to 8 of the TP53 gene showed mutations in 43% (68/160) of the cases, while mutation analyses of exon 2 of the Ki-ras gene showed mutations in 46% (74/160) of the cases. Multivariate analyses showed that clinical outcome were strongly associated with the presence of specific TP53 mutations in L3 domain alone (only in DFS) or in combination with specific Ki-ras mutations at codon 13.

CONCLUSION

Specific TP53 mutations in L3 domain alone (only in DFS) or in combination with specific Ki-ras mutations at codon 13 are associated with a worse prognosis in sporadic CRC.

From the genome to the proteome--biomarkers in colorectal cancer

BACKGROUND AND AIMS

Colorectal cancer is the second leading cause of cancer-related death. Current clinical practice in colorectal cancer screening (fecal occult blood test, FOBT; colonoscopy) has contributed to a reduction of mortality. However, despite these screening programs, about 70% of carcinomas are detected at advanced tumor stages (UICC III/IV) presenting poor patient prognosis. Thus, innovative tools and methodologies for early cancer detection can directly result in improving patient survival rates.

PATIENTS/METHODS

Biomedical research has advanced rapidly in recent years with the availability of technologies such as global gene and protein expression profiling. Comprehensive tumor profiling has become a field of intensive research aiming at identifying biomarkers relevant for improved diagnostics and therapeutics.

RESULTS

In this paper, we report a comprehensive review of genomic, transcriptomic, and proteomic approaches for biomarker identification in tissue and blood with a main emphasis on two-dimensional gel-electrophoresis (2-DE) and mass spectrometry analyses.

CONCLUSION

Proteomics-based technologies enable to distinguish the healthy patient from the tumor patient with high sensitivity and specificity and could greatly improve common classification systems and diagnostics. However, this progress has not yet been transferred from bench to bedside but could open the door to a more accurate and target specific personalized medicine with improved patient survival.

The surgeon's role in cancer prevention. The model in colorectal carcinoma

Cancer Prevention is an emerging field, capturing the old traditional concept of anticipating the development of a major disease and preventing its full impact by early detection, treatment, or aborting the tumorigenic process by a "molecular vaccine" and alleviating the full impact of the disease. Surgeons are important clinician scientists who can carry this discipline forward and develop its full potential in the clinics and in the community. Advances in molecular biology, genetics, and other technologies have permitted seminal understanding of the carcinogenic pathways and identification of targets and intermediate end points in neoplasia. In this review, we will see that we have the means of preventing significant numbers of colorectal carcinomas (CRC).

EP1-4 subtype, COX and PPAR gamma receptor expression in colorectal cancer in prediction of disease-specific mortality

The importance of prostaglandins in tumor growth and progression is well recognized, including antineoplastic activities by cyclooxygenase (COX) inhibitors. Variation in treatment response to COX inhibition has questioned differences in expression of cell surface and nuclear membrane receptors among tumors with different disease progression. The purpose of this study was to evaluate whether EP(1-4) subtype, PPAR gamma receptor and COX-1/COX-2 expression in colorectal cancer are related to tumor-specific mortality. Reverse transcription-polymerase chain reaction and immunohistochemistry were used to demonstrate expression and protein appearance in tumor tissue compared with normal colon tissue. EP(1) and EP(2) subtype receptor protein was highly present in tumor cells, EP(3) occurred occasionally and EP(4) was not visible. PPAR gamma, EP(2) and EP(4) mRNA were significantly higher in normal colon tissue compared with tumor tissue, without any distinct relationship to Dukes A-D tumor stage. Multivariate analyses indicated that increased tumor tissue EP(2) and COX-2 expression predicted poor survival (p<0.001). COX-1 expression was significantly higher than COX-2 expression in normal colon tissue. Average COX-2 mRNA was not increased in tumor tissue compared with normal colon. However, most tumor cells stained positive for COX-2 protein, which was low or undetectable in normal mucosa cells. COX-1 protein was preferentially visible in stroma. EP(1-4) subtype receptor mRNAs were generally positively correlated to both COX-1 and COX-2 in tumor tissue, but not in normal colon. Our results imply that both prostaglandin production (COX-2) and signaling via EP(1-4) subtype receptors, particularly EP(2), predict disease-specific mortality in colorectal cancer.

Changes in the status of p53 affect drug sensitivity to thymidylate synthase (TS) inhibitors by altering TS levels

Colorectal cancer (CRC) resistance to fluoropyrimidines and other inhibitors of thymidylate synthase (TS) is a serious clinical problem often associated with increased intracellular levels of TS. Since the tumour suppressor gene p53, which is mutated in 50% of CRC, regulates the expression of several genes, it may modulate TS activity, and changes in the status of p53 might be responsible for chemoresistance. Therefore, this study was aimed to investigate TS levels and sensitivity to TS inhibitors in wild-type (wt) and mutant (mt) p53 CRC cells, Lovo and WiDr, respectively, transfected with mt and wt p53. Lovo 175X2 cells (transfected with mt p53) were more resistant to 5-fluorouracil (5-FU; 2-fold), nolatrexed (3-fold), raltitrexed (3-fold) and pemetrexed (10-fold) in comparison with the wt p53 parental cells Lovo 92. Resistance was associated with an increase in TS protein expression and catalytic activity, which might be caused by the loss of the inhibitory effect on the activity of TS promoter or by the lack of TS mRNA degradation, as suggested by the reversal of TS expression to the levels of Lovo 92 cells by adding actinomycin. In contrast, Lovo li cells, characterized by functionally inactive p53, were 3-13-fold more sensitive to nolatrexed, raltitrexed and pemetrexed, and had a lower TS mRNA, protein expression and catalytic activity than Lovo 92. However, MDM-2 expression was significantly higher in Lovo li, while no significant differences were observed in Lovo 175X2 cells with respect to Lovo 92. Finally, mt p53 WiDr transfected with wt p53 were not significantly different from mt p53 WiDr cells with respect to sensitivity to TS inhibitors or TS levels. Altogether, these results indicate that changes in the status of p53, can differently alter sensitivity to TS inhibitors by affecting TS levels, depending on activity or cell line, and might explain the lack of clear correlation between mutations in p53 and clinical outcome after chemotherapy with TS inhibitors.

Expression of DNA mismatch repair proteins in transformed non-Hodgkin's lymphoma: relationship to smoking

It has been hypothesized that defects in DNA-mismatch repair are associated with smoking in certain types of transformed non-Hodgkin lymphoma (NHL). We have analyzed biopsy samples from two indolent B-cell lymphomas, follicular lymphoma (FL) and chronic lymphocytic leukemia/small lymphocytic leukemia (CLL/SLL), that have transformed to diffuse-large B-cell lymphoma (DLBCL). We correlated the presence or absence of DNA-mismatch repair enzymes by immunostaining as well as the p53 status to smoking history. Of all patients (n = 30), 37% showed negative immunostaining of MLH1, 16% showed negative immunostaining of MSH2 and 63% had p53 mutations and/or protein expression. Eighteen out of 20 transformed follicular lymphomas and seven out of 10 CLL/SLL that have transformed to DLBCL (Richter's syndrome) were informative for smoking histories. We found that the relative risk of negative immunostaining for either MLH1 or MSH2 was 2.2 times higher in smokers than non-smokers (relative risk = 2.2041, 95% confidence interval: 0.89714, 5.41491). No direct correlation was found between smoking and the mutations in the p53 gene. These results suggest that cigarette smoking may play a role in the development of transformed lymphomas through defective mismatch repair.

Novel P53 mutations detected by FAMA in colorectal cancers

BACKGROUND

The aim of the study was to identify p53 gene mutations by FAMA (fluorescence-assisted mismatch analysis) in colorectal cancers.

PATIENTS AND METHODS

Analytical scanning of the p53 gene (exons 5-9) was performed in colon cancer samples from 44 consecutive patients by FAMA. FAMA is a semiautomatic scanning approach based on the chemical cleavage of the mismatch in fluorescently labeled heteroduplex DNA, obtained from the combination of a normal and a mutated allele. FAMA has already shown optimal levels of diagnostic accuracy and sensitivity in detecting gene mutations (nucleotide substitutions, insertions/deletions) both at the germline and somatic level. The peculiar feature of FAMA is its ability to detect and localize mutations, by a redundant pattern of signals due to fluorescent DNA fragments generated by chemical cleavage. Moreover, previous data have demonstrated that normal contaminating DNA from stromal cells in the sample does not affect the sensitivity of the procedure, leading to the identification of the mutation even when the ratio mutant/normal allele is 10%.

RESULTS

Eighteen mutations (12 missense, one nonsense, two deletions, three nucleotide substitutions at the level of the splice-junctions) and two polymorphisms were detected by FAMA in 17 patients (39%) and then confirmed by automated sequence analysis. Six of 18 mutations (33%) were not previously reported for colon cancer samples and two of 18 lesions (11%) were identified as novel p53 mutations.

CONCLUSIONS

Analytical scanning of the p53 gene by FAMA in DNA from colon cancer samples provides a sensitive, accurate and specific diagnostic procedure for routine clinical application.

Expression of the p53 protein and clinical and pathologic correlation in adenocarcinoma of the rectum

BACKGROUND

p53 is a tumor suppressor gene that has been implicated in the pathogenesis of a wide range of tumors, including colorectal cancer.

AIM

To evaluate the prognostic significance of p53 protein expression, and to correlate with clinical and pathologic variables as well as survival.

PATIENTS AND METHODS

Immunohistochemical staining for p53 protein was performed in a series of 83 patients with rectal cancer with a follow-up of at least 5 years.

RESULTS

Expression of nuclear protein was positive in 36 (43.4%) of the tumors. We found association between positive p53 and death, local recurrence, distant metastasis and overall recurrence and we also found association between p53 and death, local recurrence, metastasis and overall recurrence when analysis was adjusted to Astler-Coller stage and grade of differentiation.

CONCLUSION

p53 immunoexpression has shown to be an independent prognostic factor in these series.

Association of p53 mutations and a codon 72 single nucleotide polymorphism with lower overall survival and responsiveness to adjuvant radiotherapy in endometrioid endometrial carcinomas

p53 Genetic alterations are associated with advanced stage and aggressive tumors in a variety of human malignancies. The aim of this study was to examine p53 for genetic alterations and to evaluate the association of these alterations with clinical outcome and response to adjuvant radiotherapy in endometrioid endometrial carcinomas. p53 mutations in exons 2-11 were assessed in 59 endometrioid carcinomas by polymerase chain reaction-single-strand conformational polymorphism and sequence analysis. Twelve mutations (20.3%) and nine polymorphisms were identified. Seven of the nine polymorphisms were codon 72 single nucleotide polymorphisms (SNP) with an Arg/Pro allelotype. Women harboring either a mutation or an Arg/Pro allelotype at codon 72 had a lower overall survival rate than women whose tumors lacked alterations in the p53 gene (P= 0.0029). Women were stratified based on p53 genetic alterations (p53 mutation or p53 codon 72 SNP) and whether or not they received adjuvant radiation therapy. Women with p53 genetic alterations who did not receive adjuvant radiotherapy had the lowest survival rate (P= 0.0005). Treated women with p53 genetic alterations and untreated women with no p53 alteration had similar rates of survival. Among women with p53 alterations, adjuvant radiotherapy substantially increased survival (P= 0.035). In multivariate analyses, the group of women with p53 genetic alterations who did not receive adjuvant radiation therapy had a 5.9-fold increased risk of death (95% confidence interval: 1.5-22.7) compared to women whose tumors lacked p53 alterations and did not receive adjuvant radiation therapy.

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.

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.