Mutations in residues of TP53 that directly contact DNA predict poor outcome in human primary breast cancer

Potential of antiviral drug oseltamivir for the treatment of liver cancer

Liver cancer is a leading cause of cancer‑related mortality globally. Since hepatitis virus infections have been strongly associated with the incidence of liver cancer, studies concerning the effects of antiviral drugs on liver cancer have attracted great attention in recent years. The present study investigated the effects of two anti‑hepatitis virus drugs, lamivudine and ribavirin, and one anti‑influenza virus drug, oseltamivir, on liver cancer cells to assess alternative methods for treating liver cancer. MTT assays, wound healing assays, Τranswell assays, flow cytometry, immunoblotting, ELISA, immunofluorescence staining and a xenograft animal model were adopted to verify the effects of lamivudine, ribavirin and oseltamivir on liver cancer cells. Treatment with ribavirin and oseltamivir for 24 and 48 h significantly decreased the viability of both Huh-7 and HepG2 cells compared with that of THLE‑3 cells in a dose‑dependent manner. The subsequent investigations focused on oseltamivir, considering the more serious clinical adverse effects of ribavirin than those of oseltamivir. Significantly decreased migration and invasion were observed in both Huh-7 and HepG2 cells that were treated with oseltamivir for 24 and 48 h. In addition, oseltamivir significantly increased autophagy in Huh‑7 cells, as revealed by the significantly higher ratios of LC3‑II/LC3‑I, increased expression of Beclin‑1, and decreased expression of p62, whereas no significant increases in the expression of apoptosis‑related proteins, including Apaf‑1, cleaved caspase‑3, and cleaved PARP‑1, were detected. Notably, apoptosis and autophagy were significantly increased in HepG2 cells in the presence of oseltamivir, as revealed by the significant increases in the expression of Apaf‑1, cleaved caspase‑3, and cleaved PARP‑1, the higher ratios of LC3‑II/LC3‑I, the increased expression of Beclin‑1, and the decreased expression of p62. Additionally, significant inhibitory effects of oseltamivir on xenografted Huh‑7 cells in athymic nude mice were observed. The present study, for the first time to the best of our knowledge, reported the differential effects of oseltamivir on inducing liver cancer cell death both in vitro and in vivo and may provide an alternative approach for treating liver cancer.

Survival in males with glioma and gastric adenocarcinoma correlates with mutant p53 residual transcriptional activity

BACKGROUND

There is currently no clinical distinction between different TP53 mutations, despite increasing evidence that not all mutations have equally deleterious effects on the activity of the encoded tumor suppressor protein p53. The objective of this study was to determine whether these biological differences have clinical significance.

METHODS

This retrospective cohort analysis included 2,074 patients with sporadic TP53 mutations (403 unique mutations) and 1,049 germline TP53 mutation carriers (188 unique mutations). Survival was projected by stratifying patients according to their p53 mutant-specific residual transcriptional activity scores.

RESULTS

Pan-cancer survival analyses revealed a strong association between increased mutant p53 residual activity and improved survival in males with glioma and gastric adenocarcinoma (P = 0.002 and P = 0.02) that was not present in the female cohorts (P = 0.16 and P = 0.50). Male glioma and gastric cancer patients with TP53 mutations resulting in >5% transcriptional activity had 3.1-fold (95% CI, 2.4-3.8; P = 0.002; multivariate analysis hazard ratio [HR]) and 4.6-fold (95% CI, 3.7-5.6; P = 0.001; multivariate analysis HR) lower risk of death as compared with patients harboring inactive (0% activity) p53 mutants. The correlation between mutant p53 residual activity with survival was recapitulated in the dataset of germline TP53 mutation carriers (HR = 3.0, 95% CI, 2.7-3.4, P < 0.001 [females]; HR = 2.2, 95% CI, 1.8-2.6, P < 0.001 [males]), where brain and gastric tumors were more common among males (P < 0.001 and P = 0.001, respectively).

CONCLUSION

The retention of mutant p53 transcriptional activity prognosticates superior survival for men with glioma and gastric adenocarcinoma harboring sporadic TP53 mutations. Among germline TP53 mutation carriers, increased residual transcriptional activity is correlated with prolonged lifetime cancer survival and delayed tumor onset, and males are more prone to develop brain and gastric tumors.

FUNDING

Canadian Institutes of Health Research (no. 148556).

Elucidating therapeutic molecular targets in premenopausal Asian women with recurrent breast cancers

Breast cancer is an increasing problem in Asia, with a higher proportion of premenopausal patients who are at higher risk of recurrence. Targeted sequencing was performed on DNA extracted from primary tumor specimens of 63 premenopausal Asian patients who relapsed after initial diagnosis of non-metastatic breast cancer. The most prevalent alterations included: TP53 (65%); PIK3CA (32%); GATA3 (29%); ERBB2 (27%); MYC (25%); KMT2C (21%); MCL1 (17%); PRKDC, TPR, BRIP1 (14%); MDM4, PCDH15, PRKAR1A, CDKN1B (13%); CCND1, KMT2D, STK11, and MLH1 (11%). Sixty of the 63 patients (95%) had at least one genetic alteration in a signaling pathway related to cell cycle or p53 signaling. The presence of MCL1 amplification, HIF-1-alpha transcription factor network pathway alterations, and direct p53 effectors pathway alterations were independent predictors of inferior overall survival from initial diagnosis. Comparison with non-Asian premenopausal tumors in The Cancer Genome Atlas (TCGA) revealed a higher prevalence of TP53 mutations among HER2-positive cancers, and more frequent TP53, TET2, and CDK12 mutations among hormone receptor-positive HER2-negative cancers in our cohort. Given the limited number of non-Asian premenopausal breast cancers that had relapsed in TCGA, we compared the frequency of mutations in our cohort with 43 premenopausal specimens from both TCGA and International Cancer Genome Consortium that had relapsed. There was a trend toward higher prevalence of TP53 mutations in our cohort. Certain genomic aberrations may be enriched in tumors of poor-prognosis premenopausal Asian breast cancers. The development of novel therapies targeting these aberrations merit further research.

Younger women in Asia with recurrent breast cancer seem to have a higher rate of mutations in the tumor suppressor gene TP53 than do women elsewhere—a finding that could guide drug development in Asia. Yoon-Sim Yap from the
 National Cancer Centre Singapore and coworkers sequenced DNA extracted from the tumor samples of 63 premenopausal women from Singapore and South Korea who relapsed following treatment for non-metastatic breast cancer. The researchers analyzed hundreds of cancer-related genes, and found that the vast majority of women harbored mutations in at least one gene linked to regulating the cell cycle of TP53 signaling. The prevalence of mutations in certain genes, including TP53 itself, was higher than observed previously in non-Asian cohorts, highlighting the need to consider ethnic diversity in genomic studies of breast cancer and in drug development.

TP53 mutations and protein immunopositivity may predict for poor outcome but also for trastuzumab benefit in patients with early breast cancer treated in the adjuvant setting

BACKGROUND

We investigated the impact of PIK3CA and TP53 mutations and p53 protein status on the outcome of patients who had been treated with adjuvant anthracycline-taxane chemotherapy within clinical trials in the pre- and post-trastuzumab era.

RESULTS

TP53 and PIK3CA mutations were found in 380 (21.5%) and 458 (25.9%) cases, respectively, including 104 (5.9%) co-mutated tumors; p53 immunopositivity was observed in 848 tumors (53.5%). TP53 mutations (p < 0.001) and p53 protein positivity (p = 0.001) were more frequent in HER2-positive and triple negative (TNBC) tumors, while PIK3CA mutations were more frequent in Luminal A/B tumors (p < 0.001). TP53 mutation status and p53 protein expression but not PIK3CA mutation status interacted with trastuzumab treatment for disease-free survival; patients with tumors bearing TP53 mutations or immunopositive for p53 protein fared better when treated with trastuzumab, while among patients treated with trastuzumab those with the above characteristics fared best (interaction p = 0.017 for mutations; p = 0.015 for IHC). Upon multivariate analysis the above interactions remained significant in HER2-positive patients; in the entire cohort, TP53 mutations were unfavorable in patients with Luminal A/B (p = 0.003) and TNBC (p = 0.025); p53 immunopositivity was strongly favorable in patients treated with trastuzumab (p = 0.009).

MATERIALS AND METHODS

TP53 and PIK3CA mutation status was examined in 1766 paraffin tumor DNA samples with informative semiconductor sequencing results. Among these, 1585 cases were also informative for p53 protein status assessed by immunohistochemistry (IHC; 10% positivity cut-off).

CONCLUSIONS

TP53 mutations confer unfavorable prognosis in patients with Luminal A/B and TNBC tumors, while p53 immunopositivity may predict for trastuzumab benefit in the adjuvant setting.

Somatic and Germline TP53 Alterations in Second Malignant Neoplasms from Pediatric Cancer Survivors

Purpose: Second malignant neoplasms (SMNs) are severe late complications that occur in pediatric cancer survivors exposed to radiotherapy and other genotoxic treatments. To characterize the mutational landscape of treatment-induced sarcomas and to identify candidate SMN-predisposing variants, we analyzed germline and SMN samples from pediatric cancer survivors.Experimental Design: We performed whole-exome sequencing (WES) and RNA sequencing on radiation-induced sarcomas arising from two pediatric cancer survivors. To assess the frequency of germline TP53 variants in SMNs, Sanger sequencing was performed to analyze germline TP53 in 37 pediatric cancer survivors from the Childhood Cancer Survivor Study (CCSS) without any history of a familial cancer predisposition syndrome but known to have developed SMNs.Results: WES revealed TP53 mutations involving p53's DNA-binding domain in both index cases, one of which was also present in the germline. The germline and somatic TP53-mutant variants were enriched in the transcriptomes for both sarcomas. Analysis of TP53-coding exons in germline specimens from the CCSS survivor cohort identified a G215C variant encoding an R72P amino acid substitution in 6 patients and a synonymous SNP A639G in 4 others, resulting in 10 of 37 evaluable patients (27%) harboring a germline TP53 variant.Conclusions: Currently, germline TP53 is not routinely assessed in patients with pediatric cancer. These data support the concept that identifying germline TP53 variants at the time a primary cancer is diagnosed may identify patients at high risk for SMN development, who could benefit from modified therapeutic strategies and/or intensive posttreatment monitoring. Clin Cancer Res; 23(7); 1852-61. ©2016 AACR.

The downregulation of ΔNp63 in p53-deficient mouse epidermal tumors favors metastatic behavior

The TP63 gene codes for two major isoform types, TAp63 and ΔNp63, with probable opposite roles in tumorigenesis. The ΔNp63α protein is frequently amplified and overexpressed in different epithelial tumors. Accordingly, it has been considered a potential oncogene. Nonetheless, a possible metastatic suppressor activity has also been suggested based on the experimental observation that its expression is reduced or even absent in advanced invasive tumors. Such metastatic suppressor activities are often related to tumors bearing point mutated TP53 gene. However, its potential roles in TP53-deficient tumors are poorly characterized. Here we show that in spontaneous tumors, induced by the epidermal-specific Trp53 ablation, the reduction of ΔNp63 expression is an early event, whereas it is re-expressed in the lung metastatic lesions. Using knock down and ectopic expression approaches, we show that ΔNp63 expression opposes the epithelial-mesenchymal transition and reduces the metastatic potential of the cells. This process occurs through the modulation of ΔNp63-dependent downstream targets (including transcription factors and microRNAs) likely to play metastatic roles. Further, ΔNp63 also favors the expression of factors involved in iPS reprogramming, thus suggesting that it can also modulate specific stem cell traits in mouse epidermal tumor cells. Overall, our data assign antimetastatic roles to ΔNp63 in the context of p53 deficiency and epidermis.

Rapid detection of genetic mutations in individual breast cancer patients by next-generation DNA sequencing

Breast cancer is the most common malignancy in women and the leading cause of cancer deaths in women worldwide. Breast cancers are heterogenous and exist in many different subtypes (luminal A, luminal B, triple negative, and human epidermal growth factor receptor 2 (HER2) overexpressing), and each subtype displays distinct characteristics, responses to treatment, and patient outcomes. In addition to varying immunohistochemical properties, each subtype contains a distinct gene mutation profile which has yet to be fully defined. Patient treatment is currently guided by hormone receptor status and HER2 expression, but accumulating evidence suggests that genetic mutations also influence drug responses and patient survival. Thus, identifying the unique gene mutation pattern in each breast cancer subtype will further improve personalized treatment and outcomes for breast cancer patients. In this study, we used the Ion Personal Genome Machine (PGM) and Ion Torrent AmpliSeq Cancer Panel to sequence 737 mutational hotspot regions from 45 cancer-related genes to identify genetic mutations in 80 breast cancer samples of various subtypes from Chinese patients. Analysis revealed frequent missense and combination mutations in PIK3CA and TP53, infrequent mutations in PTEN, and uncommon combination mutations in luminal-type cancers in other genes including BRAF, GNAS, IDH1, and KRAS. This study demonstrates the feasibility of using Ion Torrent sequencing technology to reliably detect gene mutations in a clinical setting in order to guide personalized drug treatments or combination therapies to ultimately target individual, breast cancer-specific mutations.

Patterns and Biologic Features of p53 Mutation Types in Korean Breast Cancer Patients

PURPOSE

The p53 gene is one of the most frequently mutated genes in breast cancer. We investigated the patterns and biologic features of p53 gene mutation and evaluated their clinical significance in Korean breast cancer patients.

METHODS

Patients who underwent p53 gene sequencing were included. Mutational analysis of exon 5 to exon 9 of the p53 gene was carried out using polymerase chain reaction-denaturing high performance liquid chromatography and direct sequencing.

RESULTS

A total of 497 patients were eligible for the present study and p53 gene mutations were detected in 71 cases (14.3%). Mutation of p53 was significantly associated with histologic grading (p<0.001), estrogen receptor and progesterone receptor status (p<0.001), HER2 status (p<0.001), Ki-67 (p=0.028), and tumor size (p=0.004). The most frequent location of p53 mutations was exon 7 and missense mutation was the most common type of mutation. Compared with patients without mutation, there was a statistically significant difference in relapse-free survival of patients with p53 gene mutation and missense mutation (p=0.020, p=0.006, respectively). Only p53 missense mutation was an independent prognostic factor for relapse-free survival in multivariate analysis, with an adjusted hazard ratio of 2.29 (95% confidence interval, 1.08-4.89, p=0.031).

CONCLUSION

Mutation of the p53 gene was associated with more aggressive clinicopathologic characteristics and p53 missense mutation was an independent negative prognostic factor in Korean breast cancer patients.

Metaplastic breast cancer: histologic characteristics, prognostic factors and systemic treatment strategies

Metaplastic breast cancer (MBC) is a rare subtype of invasive breast cancer that tends to have an aggressive clinical presentation as well as a variety of distinct histologic designations. Few systemic treatment options are available for MBC, as it has consistently shown a suboptimal response to standard chemotherapy regimens. These characteristics result in a worse overall prognosis for patients with MBC compared to those with standard invasive breast cancer. Due to its rarity, data focusing on MBC is limited. This review will discuss the clinical presentation, breast imaging findings, histologic and molecular characteristics of MBC as well as potential future research directions.

The code structure of the p53 DNA-binding domain and the prognosis of breast cancer patients

MOTIVATION

The tumor-suppressor gene TP53 mutations are diverse in the central region encoding the DNA-binding domain. It has not been clear whether the prognostic significance for survival in breast cancer patients is the same for all types of mutations. Are there specific types of mutations carrying a worse prognosis? To understand the correlation between the mutations in the gene encoding the DNA-binding domain and the prognosis of breast cancer, we studied the code structure of the DNA-binding domain of breast cancer patients by using various artificial codes in information transmission.

RESULTS

We indicated that the prognostic significance of all types of mutations in the DNA-binding domain is not the same, and that the DNA-binding domain having a certain code structure is important for estimating the prognosis of breast cancer patients.

CONTACT

keiko@is.noda.tus.ac.jp or hara@is.noda.tus.ac.jp.

Only missense mutations affecting the DNA binding domain of p53 influence outcomes in patients with breast carcinoma

The presence of a TP53 gene mutation can influence tumour response to some treatments, especially in breast cancer. In this study, we analysed p53 mRNA expression, LOH at 17p13 and TP53 mutations from exons 2 to 11 in 206 patients with breast carcinoma and correlated the results with disease-free and overall survival. The observed mutations were classified according to their type and location in the three protein domains (transactivation domain, DNA binding domain, oligomerization domain) and correlated with disease-free and overall survival. In our population, neither p53 mRNA expression nor LOH correlated with outcome. Concerning TP53 mutations, 27% of tumours were mutated (53/197) and the presence of a mutation in the TP53 gene was associated with worse overall survival (p = 0.0026) but not with disease-free survival (p = 0.0697), with median survival of 80 months and 78 months, respectively. When alterations were segregated into mutation categories and locations, and related to survival, tumours harbouring mutations other than missense mutations in the DNA binding domain of P53 had the same survival profiles as wild-type tumours. Concerning missense mutations in the DNA binding domain, median disease-free and overall survival was 23 months and 35 months, respectively (p = 0.0021 and p<0.0001, respectively), compared with 78 and 80 months in mutated tumours overall. This work shows that disease-free and overall survival in patients with a frameshift mutation of TP53 or missense mutation in the oligomerization domain are the same as those in wild-type TP53 patients.

Missense mutations located in structural p53 DNA-binding motifs are associated with extremely poor survival in chronic lymphocytic leukemia

PURPOSE

There is a distinct connection between TP53 defects and poor prognosis in chronic lymphocytic leukemia (CLL). It remains unclear whether patients harboring TP53 mutations represent a homogenous prognostic group.

PATIENTS AND METHODS

We evaluated the survival of patients with CLL and p53 defects identified at our institution by p53 yeast functional assay and complementary interphase fluorescence in situ hybridization analysis detecting del(17p) from 2003 to 2010.

RESULTS

A defect of the TP53 gene was identified in 100 of 550 patients. p53 mutations were strongly associated with the deletion of 17p and the unmutated IgVH locus (both P < .001). Survival assessed from the time of abnormality detection was significantly reduced in patients with both missense (P < .001) and nonmissense p53 mutations (P = .004). In addition, patients harboring missense mutation located in p53 DNA-binding motifs (DBMs), structurally well-defined parts of the DNA-binding domain, manifested a clearly shorter median survival (12 months) compared with patients having missense mutations outside DBMs (41 months; P = .002) or nonmissense alterations (36 months; P = .005). The difference in survival was similar in the analysis limited to patients harboring mutation accompanied by del(17p) and was also confirmed in a subgroup harboring TP53 defect at diagnosis. The patients with p53 DBMs mutation (at diagnosis) also manifested a short median time to first therapy (TTFT; 1 month).

CONCLUSION

The substantially worse survival and the short TTFT suggest a strong mutated p53 gain-of-function phenotype in patients with CLL with DBMs mutations. The impact of p53 DBMs mutations on prognosis and response to therapy should be analyzed in investigative clinical trials.

Association between the p53 polymorphisms and breast cancer risk: meta-analysis based on case-control study

p53 is a tumor suppressor gene and plays an important role in the etiology of breast cancer. However, studies on the association between p53 polymorphisms and breast cancer risk have yielded conflicting results. We performed a meta-analysis to investigate the association between breast cancer and the p53 polymorphisms codon 72 (27,046 cases and 30,998 controls), IVS3 16 bp (3,332 cases and 3,700 controls) and IVS6+62A>G (8,787 cases and 9,869 controls) in different inheritance models. When all the eligible studies of codon 72 polymorphism were pooled into this meta-analysis, there was no evidence of significant association between breast cancer risk and p53 codon 72 polymorphism in any genetic model. However, in the stratified analysis for Indian population, significantly association was observed in additive model (OR = 0.62, 95% CI = 0.46-0.82, P value of heterogeneity test [P (h)] = 0.153) and recessive model (OR = 0.70, 95% CI = 0.50-0.92, P (h) = 0.463). IVS3 16 bp was significantly associated with breast cancer risk in a pooled 15 studies dataset (dominant model: OR = 1.14, 95% CI = 1.02-1.27, P (h) = 0.30; recessive model: OR = 1.61, 95% CI = 1.21-2.25, P(h) = 0.25; additive model: OR = 1.66, 95% CI = 1.24-2.21, P (h) = 0.28). No significant association was found between IVS6+62A>G polymorphism and breast cancer risk in a total of 14 studies. In summary, these results indicate that IVS3 16 bp is likely an important genetic marker contributing to susceptibility of breast cancer, and codon 72 homozygous mutants may be associated with decreased breast cancer risk in Indian population.

Molecular testing of solid tumors

CONTEXT

Molecular testing of solid tumors is steadily becoming a vital component of the contemporary anatomic pathologist's armamentarium. These sensitive and specific ancillary tools are useful for confirming ambiguous diagnoses suspected by light microscopy and for guiding therapeutic decisions, assessing prognosis, and monitoring patients for residual neoplastic disease after therapy.

OBJECTIVE

To review current molecular biomarkers and tumor-specific assays most useful in solid tumor testing, specifically of breast, colon, lung, thyroid, and soft tissue tumors, malignant melanoma, and tumors of unknown origin. A few upcoming molecular diagnostic assays that may become standard of care in the near future will also be discussed.

DATA SOURCES

Original research articles, review articles, and the authors' personal practice experience.

CONCLUSIONS

Molecular testing in anatomic pathology is firmly established and will continue to gain ground as the need for more specific diagnoses and new targeted therapies evolve. Knowledge of the more common and clinically relevant molecular tests available for solid tumor diagnosis and management, and their indications and limitations, is necessary if anatomic pathologists are to optimally use these tests and act as consultants for fellow clinicians directly involved in patient care.

No significant association between the TP53 codon 72 polymorphism and breast cancer risk: a meta-analysis of 21 studies involving 24,063 subjects

Conflicting data have been published as to the possible association between polymorphism in codon 72 of the TP53 tumor suppressor gene and the risk of developing breast cancer. In order to address this question, we carried out a meta-analysis of 21 studies of and this polymorphism and breast cancer risk, which collectively included 12,601 cases and 11,462 controls. Studies were identified by searching the Medline, PubMed, Embase, and ISI Web of Knowledge databases. The strength of association between the TP53 codon 72 polymorphism and breast cancer risk was assessed by calculating crude OR values with 95% CIs, with pooled OR values calculated separately for three genetic inheritance models. We found no significant association between TP53 codon 72 polymorphism and breast cancer risk for either the codominant inheritance model (Pro/Arg vs. Pro/Pro: OR = 1.063, 95% CI = 0.967-1.169; Arg/Arg vs. Pro/Pro: OR = 1.245, 95% CI = 0.997-1.554), the dominant model (OR = 1.146, 95% CI = 0.979-1.340), or the recessive model (OR = 1.179, 95% CI = 1.020-1.362). Stratified analysis by ethnicity and source of controls similarly revealed no significant association for any of the genetic models. In summary, this meta-analysis provides strong evidence that the TP53 codon 72 polymorphism is not associated with the risk of developing breast cancer.

Classical and Novel Prognostic Markers for Breast Cancer and their Clinical Significance

The use of biomarkers ensures breast cancer patients receive optimal treatment. Established biomarkers such as estrogen receptor (ER) and progesterone receptor (PR) have been playing significant roles in the selection and management of patients for endocrine therapy. HER2 is a strong predictor of response to trastuzumab. Recently, the roles of ER as a negative and HER2 as a positive indicator for chemotherapy have been established. Ki67 has traditionally been recognized as a poor prognostic factor, but recent studies suggest that measurement of Ki67-positive cells during treatment will more effectively predict treatment efficacy for both anti-hormonal and chemotherapy. p53 mutations are found in 20–35% of human breast cancers and are associated with aggressive disease with poor clinical outcome when the DNA-binding domain is mutated. The utility of cyclin D1 as a predictor of breast cancer prognosis is controversial, but cyclin D1b overexpression is associated with poor prognosis. Likewise, overexpression of the low molecular weight form of cyclin E1 protein predicts poor prognosis. Breast cancers from BRCA1/2 carriers often show high nuclear grades, negativity to ER/PR/HER2, and p53 mutations, and thus, are associated with poor prognosis. The prognostic values of other molecular markers, such as p14^ARF, TBX2/3, VEGF in breast cancer are also discussed. Careful evaluation of these biomarkers with current treatment modality is required to determine whether their measurement or monitoring offer significant clinical benefits.

CHEK2 mutations affecting kinase activity together with mutations in TP53 indicate a functional pathway associated with resistance to epirubicin in primary breast cancer

Background

Chemoresistance is the main obstacle to cure in most malignant diseases. Anthracyclines are among the main drugs used for breast cancer therapy and in many other malignant conditions. Single parameter analysis or global gene expression profiles have failed to identify mechanisms causing in vivo resistance to anthracyclines. While we previously found TP53 mutations in the L2/L3 domains to be associated with drug resistance, some tumors harboring wild-type TP53 were also therapy resistant. The aim of this study was; 1) To explore alterations in the TP53 gene with respect to resistance to a regular dose epirubicin regimen (90 mg/m² every 3 week) in patients with primary, locally advanced breast cancer; 2) Identify critical mechanisms activating p53 in response to DNA damage in breast cancer; 3) Evaluate in vitro function of Chk2 and p14 proteins corresponding to identified mutations in the CHEK2 and p14^(ARF) genes; and 4) Explore potential CHEK2 or p14^(ARF) germline mutations with respect to family cancer incidence.

Methods and Findings

Snap-frozen biopsies from 109 patients collected prior to epirubicin (as preoperative therapy were investigated for TP53, CHEK2 and p14^(ARF) mutations by sequencing the coding region and p14^(ARF) promoter methylations. TP53 mutastions were associated with chemoresistance, defined as progressive disease on therapy (p = 0.0358; p = 0.0136 for mutations affecting p53 loop domains L2/L3). Germline CHEK2 mutations (n = 3) were associated with therapy resistance (p = 0.0226). Combined, mutations affecting either CHEK2 or TP53 strongly predicted therapy resistance (p = 0.0101; TP53 mutations restricted to the L2/L3 domains: p = 0.0032). Two patients progressing on therapy harbored the CHEK2 mutation, Arg95Ter, completely abrogating Chk2 protein dimerization and kinase activity. One patient (Epi132) revealed family cancer occurrence resembling families harboring CHEK2 mutations in general, the other patient (epi203) was non-conclusive. No mutation or promoter hypermethylation in p14^(ARF) were detected.

Conclusion

This study is the first reporting an association between CHEK2 mutations and therapy resistance in human cancers and to document mutations in two genes acting direct up/down-stream to each other to cause therapy failure, emphasizing the need to investigate functional cascades in future studies.

p53 and disease: when the guardian angel fails

The p53 tumor suppressor gene (TP53) is mutated more often in human cancers than any other gene yet reported. Of importance, it is mutated frequently in the common human malignancies of the breast and colorectum and also, but less frequently, in other significant human cancers such as glioblastomas. There is also one inherited cancer predisposing syndrome called Li-Fraumeni that is caused by TP53 mutations. In this review, we discuss the significance of p53 mutations in some of the above tumors with a view to outlining how p53 contributes to malignant progression. We also discuss the usefulness of TP53 status as a prognostic marker and its role as a predictor of response to therapy. Finally, we outline some evidence that abnormalities in p53 function contribute to the etiology of other non-neoplastic diseases.

Polymorphism of TP53 codon 72 showed no association with breast cancer in Iranian women

Breast cancer is the most common female malignancy worldwide. Despite the high incidence of sporadic cases, the rate of familial breast cancer is low. The tumor suppressor gene TP53 (alias p53), located on chromosome 17, has been involved in various malignancies. Mutations in codon 72 of TP53 have been studied in breast cancer and most solid tumors. For study of polymorphisms and allele frequency, 221 female patients with sporadic breast cancer and 205 healthy blood donors as control group were recruited. DNA from peripheral blood mononuclear cells was extracted and amplified using allele-specific polymerase chain reaction. Frequency of homozygotic arginine at codon 72 was 37.6% in patients and 36.6% in controls, for homozygotic proline it was 13.1 and 19.5%, and for heterozygotic Arg/Pro it was 49.3 and 43.9%, respectively. No significant difference was found between patients and controls regarding allele frequencies. Mutation in codon 72 of TP53 gene was not associated with breast cancer in Iranian patients.

Breast cancer prognostication and prediction in the postgenomic era

Expanding knowledge, together with implementation of new techniques, has fuelled the area of translational medical research aiming at improving prognostication as well as prediction in cancer therapy. At the same time, new discoveries have revealed a biological complexity we were unaware of only a decade ago. Thus, we are faced with novel challenges with respect to how we may explore issues such as prognostication and predict drug resistance in vivo. While microarray analysis exploring expression of thousands of genes in concert represents a major methodological advancement, discoveries such as the finding of different mechanisms of epigenetic silencing, intronic mutations, that most gene transcripts in the human genome are subject to alternative splicing and that hypersplicing seems to be a tumour-related phenomenon, exemplifies a complex pathology that may not be explored with use of single analytical methods only. This paper discusses clinical settings for studying drug resistance in vivo together with a discussion of contemporary biology in this field. Notably, each individual parameter which has been found correlated to drug resistance in vivo so far represents either a direct drug target or a factor involved in DNA repair or apoptosis. On the basis of these findings, we suggest drug resistance may be explored on the basis of upfront biological hypotheses.

Type of TP53 mutation and ERBB2 amplification affects survival in node-negative breast cancer

Alterations of TP53 and ERBB2 have been shown to play important roles in the prognosis of breast cancer. The primary objective of this study is to characterize TP53 mutation types in node negative breast cancer and investigate their prognostic value, alone and in combination with ERBB2 amplification status. TP53 mutational status (exons 2-10) and ERBB2 amplification status were determined in tumor specimens from a prospective cohort of 543 women with node-negative breast cancer. During a median follow-up of 120 months, there were 111 disease recurrences, and 81 disease-related deaths (3 with cancer; 78 from cancer). Of 543 women, 133 (24.5%) carried mutations in exons 4-9 of the TP53 gene. Seventy-one (53.4%) of these mutations were missense; whereas 62 (46.6%) were protein-truncating mutations. Women whose tumors had missense TP53 mutations were found to be at significantly higher risk of recurrence and death compared to those with wild type TP53, and they also tended to have worse prognosis compared to those with truncating mutations. Those with short truncated proteins tended to have good prognosis compared to those with long truncated proteins, but the risk of recurrence and death did not differ between those whose tumors exhibited conserved versus non-conserved mutations. Missense mutations, in combination with ERBB2 amplification, were observed in 4.6% of the tumors and dramatically affected the disease-specific survival (DSS) and disease-free survival (DFS) of the breast cancer patients. Our study suggests that the type of TP53 mutation, especially missense mutation, is a strong prognostic indicator for DFS and DSS in node-negative breast cancer, particularly in combination with ERBB2 amplification.

A nonreplicating adenoviral vector that contains the wild-type p53 transgene combined with chemotherapy for primary breast cancer: safety, efficacy, and biologic activity of a novel gene-therapy approach

BACKGROUND

: Primary systemic therapy (PST) is the standard approach to the management of patients with locally advanced breast cancer (LABC). The authors hypothesized that the intratumoral administration of a nonreplicating adenoviral vector (Ad5) that contains the human wild-type p53, AdCMV-p53, combined with chemotherapy, could increase the efficacy of PST as measured by pathologic complete response.

METHODS

: In a prospective, open-label, Phase II trial, 13 patients with LABC were treated with 6 3-week cycles of PST, which consisted of intratumoral injections of Ad5CMV-p53 for 2 consecutive days plus docetaxel and doxorubicin followed by surgery. p53 status was determined at baseline and was assessed immediately after the first injection (up to 48 hours). Clinical response was assessed by clinical and radiologic methods.

RESULTS

: The trial was terminated early, because none of the patients achieved a pathologic complete response. The median age was 56 years (range, 39-71 years), and the median tumor size was 8 cm (range, 5-11 cm). Eight patients (73%) had a p53 mutation. Serial biopsies showed an increase in p53 messenger RNA (mRNA) and p21(WAF1/Cip1) mRNA. All 12 evaluable patients achieved an objective clinical response. The surgical specimens revealed scattered tumor cells with extensive tumor-infiltrate leukocytes (predominantly T-lymphocytes). At a median follow-up of 37 months (range, 30-41 months), 4 patients (30%) developed systemic recurrence, and 2 patients died. The estimate breast cancer-specific survival rate at 3 years was 84% (95% confidence interval, 65.7-100%). There was no increase in systemic toxicity.

CONCLUSIONS

: Ad5CMV-p53 combined with PST is safe, active, and associated with local immunomodulatory effects. The promising clinical activity of this combination deserves further investigation in randomized studies.

Functional categories of TP53 mutation in colorectal cancer: results of an International Collaborative Study

BACKGROUND

Loss of TP53 function through gene mutation is a critical event in the development and progression of many tumour types including colorectal cancer (CRC). In vitro studies have found considerable heterogeneity amongst different TP53 mutants in terms of their transactivating abilities. The aim of this work was to evaluate whether TP53 mutations classified as functionally inactive (< or=20% of wildtype transactivation ability) had different prognostic and predictive values in CRC compared with mutations that retained significant activity.

MATERIALS AND METHODS

TP53 mutations within a large, international database of CRC (n = 3583) were classified according to functional status for transactivation.

RESULTS

Inactive TP53 mutations were found in 29% of all CRCs and were more frequent in rectal (32%) than proximal colon (22%) tumours (P < 0.001). Higher frequencies of inactive TP53 mutations were also seen in advanced stage tumours (P = 0.0003) and in tumours with the poor prognostic features of vascular (P = 0.006) and lymphatic invasion (P = 0.002). Inactive TP53 mutations were associated with significantly worse outcome only in patients with Dukes' stage D tumours (RR = 1.71, 95%CI 1.25-2.33, P < 0.001). Patients with Dukes' C stage tumours appeared to gain a survival benefit from 5-fluorouracil-based chemotherapy regardless of TP53 functional status for transactivation ability.

CONCLUSIONS

Mutations that inactivate the transactivational ability of TP53 are more frequent in advanced CRC and are associated with worse prognosis in this stage of disease.

Testing of Functional Integrity of p53 Protein in Primary Breast Cancer by a Rapid Quantitative p53-p21^WAF1 Double Assay May Improve the Clinical Value of p53

We hypothesized that inclusion of p21(WAF1), an indicator of biological function, into the p53 assay might improve the clinical value of p53 in breast cancer diagnosis. In primary breast carcinomas (n = 146) and healthy/benign controls (n = 40), the p53 protein was quantified by luminescence immunoassay. The p21 protein was simultaneously measured by quantitative ELISA in a representative subgroup of breast cancers (n = 52) and controls (n = 17). In controls, p53 but not p21 was detectable. In almost all cancer tissues, p53 and p21 expression could be quantified. There was no correlation between the concentrations of both proteins. However, if p53 exceeded a threshold of 1.0 ng/mg protein, p21 expression was significantly reduced compared with samples with p53 below threshold. p21 was normally distributed in the low-p53 subpopulation, but not in the high-p53 group. The histologic parameter 'grade III' was more often found (p = 0.002) in tumors with p53 >1.0 ng/mg protein than in those with p53 below the threshold. Histological criteria of high tumor malignancy were found more often in cases with high p53 but low p21. Consequently, in clinical routine, a quantitative double assay of p53 and p21(WAF1) might help to discriminate breast cancers with preserved or impaired/lost p53 function.

The UMD TP53 database and website: update and revisions

Mutation of the p53 gene is the most frequent genetic alteration found in human cancer, but it is also the most frequently reported with more than 22,000 mutations published in 2,000 papers. In 1991, we developed a database and software to handle and analyze all this information. The database has been widely used for clinical analysis and molecular epidemiology. We have expanded the scope of the database by integrating structural, phylogenetic and biological information on wild-type (wt) and mutant TP53. Integration of the TP53 mutant activity database provides unique information that will be useful to both clinicians and scientists. All of this information is available from a new website (www.umd.be:2072/) that will generate a detailed informative page for every TP53 mutant in the database. New tools to check TP53 mutations and minimize errors found in the literature are also available.

Proteomic identification of heat shock protein 90 as a candidate target for p53 mutation reactivation by PRIMA-1 in breast cancer cells

Introduction

A loss of p53 function resulting from mutation is prevalent in human cancers. Thus, restoration of p53 function to mutant p53 using small compounds has been extensively studied for cancer therapy. We previously reported that PRIMA-1 (for 'p53 reactivation and induction of massive apoptosis') restored the transcriptional activity of p53 target genes in breast cancer cells with a p53 mutation. By using functional proteomics approach, we sought to identify molecular targets that are involved in the restoration of normal function to mutant p53.

Methods

PRIMA-1 treated cell lysates were subjected to immunoprecipitation with DO-1 primary antibody against p53 protein, and proteins bound to p53 were separated on a denaturing gel. Bands expressed differentially between control and PRIMA-1-treated cells were then identified by matrix-assisted laser desorption ionization-time-of-flight spectrometry. Protein expression in whole cell lysates and nuclear extracts were confirmed by Western blotting. The effect of combined treatment of PRIMA-1 and adriamycin in breast cancer cells was determined with a cytotoxicity assay in vitro.

Results

PRIMA-1 treated cells distinctly expressed a protein band of 90 kDa that was identified as heat shock protein 90 (Hsp90) by the analysis of the 90 kDa band tryptic digest. Immunoblotting with isoform-specific antibodies against Hsp90 identified this band as the α isoform of Hsp90 (Hsp90α). Co-immunoprecipitation with anti-Hsp90α antibody followed by immunoblotting with DO-1 confirmed that p53 and Hsp90α were interacting proteins. PRIMA-1 treatment also resulted in the translocation of Hsp90α to the nucleus by 8 hours. Treatment of cells with PRIMA-1 alone or in combination with adriamycin, a DNA-targeted agent, resulted in increased sensitivity of tumor cells.

Conclusion

The studies demonstrate that PRIMA-1 restores the p53-Hsp90α interaction, enhances the translocation of the p53-Hsp90α complex and reactivates p53 transcriptional activity. Our preliminary evidence also suggests that PRIMA-1 could be considered in combination therapy with DNA-targeted agents for the treatment of breast cancer, especially for tumors with aberrant p53 function.

p53 mutation heterogeneity in cancer

The p53 gene is inactivated in about 50% of human cancers and the p53 protein is an essential component of the cell response induced by genotoxic stresses such as those generated by radiotherapy or chemotherapy. It is therefore highly likely that these alterations are an important component in tumor resistance to therapy. The particular characteristics of these alterations, 80% of which are missense mutations leading to functionally heterogeneous proteins, make p53 a unique gene in the class of tumor suppressor genes. A considerable number of mutant p53 proteins probably have an oncogenic activity per se and therefore actively participate in cell transformation. The fact that the apoptotic and antiproliferative functions of p53 can be dissociated in certain mutants also suggests another level of complexity in the relationships between p53 inactivation and neoplasia.

The tumor suppressor gene TP53: implications for cancer management and therapy

The p53 protein is an inducible transcription factor with multiple anti-proliferative roles in response to genotoxic damage; unprogrammed proliferative stimuli; and deprivation of oxygen, nutrients, or ribonucleotides. Inactivation of the TP53 gene by mutation or deletion is the most common event in human cancer. Loss of p53 function compromises genetic homeostasis in cells exposed to mutagens and prevents normal cytotoxic responses to cancer therapies. Genetic and pharmacological approaches are being developed with the ultimate goal of restoring or controlling p53 functions in cancer patients. Genetic interventions aiming at expressing wild-type TP53 in cancer cells, either by retroviral or adenoviral transfer, have met limited clinical success. However, recently, the use of a defective adenovirus (ONYX-015) that selectively kills p53-incompetent cells has shown promising effects in pre-clinical and clinical studies. Pharmacological methods are under development to either stimulate wild-type p53 protein function or induce p53 mutant proteins to resume wild-type functions. These methods are based on small chemicals (CP-31388, PRIMA-1), peptides (CDB3), or single-chain Fv antibody fragments corresponding to defined p53 domains. In addition, detection of mutant TP53 may also serve as a marker for early cancer detection, prediction, and prognosis. In this review, we discuss the mechanisms underlying these approaches and their perspectives for cancer therapy.

Spectrum of p53 tumor suppressor gene mutations and breast cancer survival

CONTEXT

p53 mutation is associated with poor prognosis in breast cancer patients. Mutations in different structural and functional domains of p53 have different effects on its biological activities. Nevertheless, few studies have examined the full spectrum of p53 gene mutations in relation to breast cancer survival.

OBJECTIVE

To evaluate the prognostic significance of the types, localizations, and multiplicity of p53 gene mutations in breast cancer patients.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study of a consecutive series of 271 women with histologically confirmed primary breast cancer who underwent breast resection at the Jackson Memorial Hospital, Miami, FL, between 1984 and 1986. Main outcome measures. Ten year overall and breast-cancer-specific deaths.

RESULTS

After adjustment for tumor stage, treatment regimen, and the number of mutations, patients with p53 mutations had significantly greater breast-cancer-specific mortality than did patients without p53 mutations (hazard ratio = 2.86; 95% confidence interval: 1.15-7.11). Further analysis of mutation characteristics showed that patients with the following mutations had significantly poorer breast cancer disease-free survival: silent/missense mixed mutations (7.95; 1.28-49.62), nonsense mutations (9.43; 1.29-69.12), transitions (3.79; 1.46-9.88), mutations in which guanine changed (3.32; 1.01-10.35), and mutations on exon 7 (6.46; 1.78-23.45).

CONCLUSIONS

Breast-cancer-specific and all-cause mortality are increased in female breast cancer patients with the following p53 mutation characteristics: silent and missense mixed mutations, transitional mutations, mutations in which guanine changed, mutations on exon 7, or multiple mutations occurring within 60 codons. These findings indicate that not just p53 mutation per se but the full spectrum (i.e., different types, locations, and numbers) of p53 mutation needs to be examined when it is used as a prognostic marker of survival in breast cancer patients.

Prognostic value of p53 molecular status in high-risk primary breast cancer

BACKGROUND

Mutations in the p53 gene are the most common genetic alterations in human primary breast carcinoma and these mutations are often associated with worse prognosis and chemo/radioresistance.

PATIENTS AND METHODS

The analysis of the p53 gene was performed by fluorescence-assisted mismatch analysis in 13 consecutive high-risk primary breast cancer (HR-BC) patients with 10 or more involved axillary nodes to evaluate its prognostic value.

RESULTS

Three p53 mutations (23%) and four allelic variants were detected. After a median follow-up of 52 months the HR-BC disease-free survival (DFS) was 51% and overall survival 79%. All patients harboring a p53 mutation (p53(mut)) relapsed within 10 months of the median DFS while 67% of those showing a wild-type p53 status (p53(wt)) survive disease-free at a median follow-up of 43 months. One p53(mut) patient is still alive while all the p53(wt) patients survive at 56 months median follow-up. Two out of the four p53(wt) relapsing breast cancer patients showed the Arg72Pro allelic variant; one of these died at 75 months.

CONCLUSIONS

p53 mutations may help identify a subset of very high risk breast cancer patients (vHR-BC) with worse prognosis.

TP53 and breast cancer

The TP53 gene (p53) is found altered in breast carcinomas in approximately 20-40% of all cases depending on tumor size and stage of the disease. It seems to be an early event in breast tumorigenesis. Several polymorphisms in the TP53 gene have been detected and their possible roles in breast cancer risk and association to type of cancer developed are discussed. The different mutation spectra seen in geographical and ethnic populations may be used to identify environmental exposure contributing to breast cancer development. The role of TP53 mutation as a prognostic marker is reviewed as well as its role as a predictor for therapy response. All data available on TP53 mutation analyses of human breast carcinomas, as well data from transgenic animal studies and experimental cell studies, support an important role for TP53 in mammary carcinogenesis.

Specific p53 mutations predict poor prognosis in oral squamous cell carcinoma

In this study, we focused on p53 mutations in specific regions, including DNA-binding surface regions, to clarify the correlation between mutations within the specific regions of p53 and clinical outcomes of patients with oral cancers. We analyzed p53 mutations in 121 fresh primary oral squamous cell carcinomas (SCCs) by polymerase chain reaction-single-strand conformation polymorphism or a yeast functional assay. p53 mutations were detected in 51/121 (42%) cases. Mutation of p53 was not associated with any clinicopathological parameters; however, tumors containing specific p53 mutations, e.g. DNA-binding surface regions (L2, L3 and the LSH motif) and conserved regions (II-V), had significantly poorer prognoses than tumors with mutations outside of those regions. Moreover, locoregional failure, lymph node metastasis and the occurrence of subsequent distant metastasis were also significantly associated with mutations within DNA-binding surface regions. These data indicate that specific mutations of p53 could be important prognostic factors in oral SCCs.

Correlations of Breast Carcinoma Biomarkers and p53 Tested by FASAY and Immunohistochemistry

p53 status is an important predictive factor in breast cancer, but the results of many studies are ambiguous. We tested p53 by functional analysis of separated alleles in yeast (FASAY) as well as by immunohistochemistry (IHC) and evaluated correlations with main prognostic factors, proliferation, and Bcl-2. Thirty-two tumors were tested with antibodies BP53-12, DO1, DO11, DO12, and by FASAY. Spearman rank correlations were tested separately with age, tumor type, pT, grade, pN, NPI, Ki-67, S-phase, proliferation index, Bcl-2, and steroid receptor status determined by ER, PR, and pS2. FASAY showed significant correlations with ductal type, grade and proliferation, and an inverse correlation with functional estrogen receptor and Bcl-2. FASAY provided better correlations compared to p53 IHC. We conclude that FASAY shows significant correlations with main prognostic/predictive factors and provides more reliable biological information compared to p53 IHC. Apoptosis is positively linked to proliferation and is not under the control of p53, which is frequently mutated in highly proliferating carcinomas. FASAY seems to be very important in assessing the predictive significance of p53 for a specific therapy of breast cancer.

Frequent phosphorylation at serine 392 in overexpressed p53 protein due to missense mutation in carcinoma of the urinary tract

Post-transcriptional modification of p53 by phosphorylation has been proposed to be an important mechanism of p53 stabilization and functional regulation. Phosphorylation of p53 Ser392, in particular, activates specific DNA binding functions by stabilizing p53 tetramer formation. This study evaluated the relationship between p53 Ser392 phosphorylation and various types of p53 missense mutation detected in urothelial transitional cell carcinomas (TCCs), with stratification of the mutations according to the functional domains elucidated by the crystal structure of the p53 protein. Of 41 TCCs with missense mutations, 26 (63.4%) exhibited immunopositivity with Ser392 phospho-specific p53 antibody. In comparison to structural mutations, the missense mutations at exon 7 (p=0.0307) or located in regions that affect direct DNA binding ability (p = 0.0273) were significantly associated with Ser392 immunopositivity. No statistically significant relationship was found between Ser392 immunoreactivity and other different types of p53 mutation. The prevalence of cases exhibiting Ser392-positive immunostaining was higher for high-grade (p <0.0001) and advanced-stage TCCs (p =0.0119) than for TCCs with wild-type p53. No significant relationship was found between Ser392 immunoreactivity and apoptotic index in urothelial TCCs. These in vivo findings indicate that Ser392 phosphorylation frequently occurs in mutant form p53 in TCCs. Because mutant form p53 can act dominant-negatively by heterooligomerization with wild-type p53, these findings also suggest that Ser392 phosphorylation might activate tetramer formation to promote the dominant-negative effects of mutant form p53, and thereby contribute to proliferation of aggressive TCCs.

Assessing TP53 status in human tumours to evaluate clinical outcome

TP53 is probably the most extensively studied tumour-suppressor gene, and patients with TP53 mutations are known to have a poor outcome. However, inconsistencies in the analysis of TP53 status, and failure to realize that different mutations behave in different ways, prevent us from effectively applying our vast knowledge of this protein in clinical practice. What simple steps can be taken to ensure that patients benefit from our understanding of TP53?

TP53 mutation patterns in breast cancers: searching for clues of environmental carcinogenesis

Mutations in the tumour suppressor gene TP53 occur in about 30% of breast cancers. We have used the IARC TP53 mutation database to analyse the pattern of mutations in breast cancers (1392 mutations). The global pattern of mutations is similar to the one of most other cancers, but there is an excess of transversions on G bases in tumours from Western (USA and Europe) as compared to Eastern (Japan) countries. Moreover, the patterns of inherited TP53 mutations associated with breast cancer, differ from those of somatic mutations. These differences support the hypothesis that a fraction of breast cancer mutations occur as a consequence of environmental exposures.

Molecular profiles of BRCA1-mutated and matched sporadic breast tumours: relation with clinico-pathological features

About 5-10% of breast cancers are hereditary; a genetically and clinically heterogeneous disease in which several susceptibility genes, including BRCA1, have been identified. While distinct tumour features can be used to estimate the likelihood that a breast tumour is caused by a BRCA1 germline mutation it is not yet possible to categorize a BRCA1 mutated tumour. The aim of the present study is to molecularly classify BRCA1 mutated breast cancers by resolving gene expression patterns of BRCA1 and matched sporadic surgical breast tumour specimens. The expression profiles of 6 frozen breast tumour tissues with a proven BRCA1 gene mutation were weighed against those from 12 patients without a known family history but who had similar clinico-pathological characteristics. In addition two fibroblast cultures, the breast cancer cell-line HCC1937 and its corresponding B-lymphoblastoid cell line (heterozygous for mutation BRCA1 5382insC) and an epithelial ovarian cancer cell line (A2780) were studied. Using a high density membrane based array for screening of RNA isolated from these samples and standard algorithms and software, we were able to distinguish subgroups of sporadic cases and a group consisting mainly of BRCA1-mutated breast tumours. Furthermore this pilot analysis revealed a gene cluster that differentially expressed genes related to cell substrate formation, adhesion, migration and cell organization in BRCA1-mutated tumours compared to sporadic breast tumours.

Correlation of p53 mutations in ThinPrep-processed fine needle breast aspirates with surgically resected breast cancers

Mutations of the p53 gene are one of the most common genetic changes found in cancer; their presence may be prognostic and even influence treatment for breast cancer. In this study, we investigated whether DNA could be extracted from the residual cells left in ThinPrep-processed breast fine-needle aspirates and whether p53 gene changes could be detected in the DNA. The results were then correlated with DNA extracted from the matched formalin-fixed, paraffin-embedded, surgically resected breast cancer when available. DNA was successfully extracted from 54 of 62 aspirates and all 31 surgical specimens. p53 gene mutations were detected in 10 of the 54 cytology specimens (18.5%) and consisted of base pair substitutions or deletions. Silent or intronic p53 changes were found in five additional aspirates. One of the aspirates had two gene alterations, resulting in a total of six gene changes. Five of these changes were located in introns 6 or 9 and the sixth was a silent (no amino acid change) change in exon 6. p53 Polymorphisms were detected in nine aspirates (16.3%) and were located in codon 47 (one aspirate), codon 72 (six aspirates), and codon 213 (two aspirates). All cases with surgical material available showed identical p53 mutations, alterations, and polymorphisms in the resected tumors compared with those detected in the corresponding aspirates. The results of this study show that DNA suitable for analysis of p53 gene sequence changes can be successfully extracted from ThinPrep-processed breast fine-needle aspirates, and that identical alterations are detected in both the cytology and surgical specimens.

TP53 mutation is an independent prognostic marker for poor outcome in both node-negative and node-positive breast cancer

TP53 gene-mutation and protein expression of p53 are described as being of prognostic importance for the outcome of breast cancer. The present study was therefore carried out to evaluate whether TP53 mutation would be a feasible prognostic marker in the routine diagnostic evaluation of breast cancer, and, in particular, to analyse the relationship between TP53 mutation and nodal status. Tumour material was obtained from women with sporadic early breast cancer. Gene mutations in exon 2-11 were identified using denaturing gradient gel electrophoresis (DGGE) as the initial scanning procedure and characterized by sequencing. All patients were treated according to the guidelines of the Danish Breast Cancer Cooperative Group for the DBCG 89 protocols. The results were correlated with clinico-pathological parameters and the prognosis evaluated by uni- and multivariate analysis using local control, freedom from distant metastasis, disease-free survival, and overall survival as endpoints. The study included 294 patients. TP53 mutations were found in 23% of cases. Mutations were significantly more frequent in tumours from patients who were node-positive and with tumours characterized as being ductal, large of size, with a high degree of anaplasia, and oestrogen receptor negative. Using univariate analysis, it was found that distant metastasis, disease-free, and overall survival were correlated to tumour size, nodal status, degree of anaplasia, oestrogen receptor status, and TP53 mutation. In addition, overall survival was also correlated to age and menopausal status. When analysed according to nodal status, TP53 mutation was found to have a significantly poor survival probability in each of the subgroups. A Cox proportional hazard analysis, including all 294 patients, demonstrated that positive nodal status and TP53 mutation were the only parameters that had an independent poor influence on the risk of developing distant metastasis and reduced recurrence-free survival. The same factors together with postmenopausal status were found to be significantly associated with increased risk of death. TP53 mutation is a strong marker for the prediction of overall and disease-free survival in breast cancer, irrespective of nodal status. A better understanding of the role of the p53 pathway, including analysis of different types of TP53 mutations, is required in order further to investigate the prognostic potential of this marker.

Effect of mutation and conformation on the function of p53 in colorectal cancer

In vitro studies have shown that immunoprecipitation with conformation-specific antibodies allows discrimination between different forms of p53; however, the significance of this has not been determined for human tumours. This study therefore examined p53 conformation in colorectal tumours and correlated this with mutational status and evidence of in vivo p53 downstream activity. Moreover, it was shown that for in vitro cell lines, DNA-damaging agents induce wild-type p53 to form a mutant conformation (PAb240+), with a concomitant rise in p21(WAF-1) expression. Induction of p53-mediated apoptosis, on the other hand, is associated with a wild-type conformation (PAb1620+). These results were confirmed for wild-type p53 in colorectal tumours. A range of p53 point mutations were found in exons 5-8 in colorectal tumours. Mutants with a wild-type conformation gave weak immunohistochemical staining, whereas mutations with flexible conformation (240+/1620+) gave intense positivity. Interestingly, this latter group of flexible mutants was also associated with features of poor prognosis. These studies show that not all p53 mutants are equal; thus, knowledge of the p53 status of a tumour may be required for a more precise prediction of prognosis and response to treatment for cancer patients.

p53 and P-glycoprotein expression are significant prognostic markers in advanced head and neck cancer treated with chemo/radiotherapy

The development of biological markers of response to chemo- and radiotherapy to judge benefit to risk ratios for toxic treatments is still at an experimental stage. Tumour cell death is largely by apoptosis and the p53 gene has a major influence on this. P-glycoprotein (P-gp) accumulation has been correlated with treatment failure in several types of cancer. p53 and P-gp expression were studied in 111 advanced head and neck cancers treated with radiotherapy and up to four courses of synchronous or sequential chemotherapy. The probability of survival at 5 years for patients in the trial as a whole was 27.7%, while the cohort used for this marker project was 29.4%. Among the subjects used for the marker study at the time of analysis, 13 remained disease-free and 18 were alive. Immunohistochemistry was used to assess p53 and P-gp expression; 27/111 (24%) head and neck cancers demonstrated p53/P-gp expression and 33/111 (30%) were both p53- and P-gp- negative. In univariate analysis, both p53 and P-gp expression were associated with reduced disease-free and overall survival. Multivariate analysis revealed tumour size, p53, and P-gp expression as the most powerful pretreatment prognosticators in the study cohort. Long-term follow-up results suggest that p53 and P-gp co-expression predicts the biological behaviour or the outcome following chemo/radiotherapy in advanced head and neck cancer.

Mutations in zinc-binding domains of p53 as a prognostic marker of esophageal-cancer patients

Some investigators have suggested that mutations of the p53 gene may be molecular markers for poor prognosis of cancer patients, although others have reported conflicting results. We examined esophageal cancers from 138 patients to investigate whether mutational status of p53 could be correlated either with prognosis or with response to chemotherapy or radiation. We detected p53 mutations in the tumors of 78 (56.5%) patients. Kaplan-Meier analysis showed that these 78 patients tended to have shorter survival times and greater resistance to either form of therapy than patients whose tumors carried two wild-type p53 alleles. The difference became more evident when we focused on mutations in zinc-binding domains of p53 (L2 and L3); the prognosis was significantly poorer among the 29 patients with tumors in this category than among patients whose tumors had no p53 mutations, or p53 mutations outside L2 or L3 (P=0.0060). Moreover, those tumors as a group were more resistant to chemotherapy or radiation than the others (P=0.0105). Our results underscore the importance of the zinc-binding domains of p53 with respect to clinical prognosis for patients with esophageal carcinomas.

A prospective trial of midwest breast cancer patients: a p53 gene mutation is the most important predictor of adverse outcome

Several retrospective studies have suggested p53 gene mutation as an adverse prognostic indicator in breast cancer patients, based on a selective growth advantage of p53 mutant cancer cells and their presumed resistance to current adjuvant therapy regimens. A cohort of 90 Caucasian midwestern breast cancer patients was analyzed prospectively (60 months of follow-up) with a rigorous mutation detection methodology. The presence of a p53 gene mutation was the single most adverse prognostic indicator for recurrence (p = 0.0032) and death (p = 0.0001), and was associated with poor response to both adjuvant (p = 0.0001) and palliative (p = 0.006) therapy. Analysis of the p53 gene with appropriate mutation detection methodology markedly improves the prediction of early recurrence, treatment failure, and death in breast cancer patients.