Heterogeneity in the clinical phenotype of TP53 mutations in breast cancer patients

Obesity Associated with Prediabetes Increases the Risk of Breast Cancer Development and Progression-A Study on an Obese Rat Model with Impaired Glucose Tolerance

Patients with comorbidities of obesity and diabetes are recognized to be at high risk of breast cancer development and face worse breast cancer outcomes. Though several reports showed the reinforced link between obesity, diabetes, and prediabetes with breast cancer, the underlying molecular mechanisms are still unknown. The present study aimed to investigate the underlying molecular link between increased risks of breast cancer due to coincident diabetes or obesity using a spontaneous obese rat model with impaired glucose tolerance (WNIN/GR-Ob rat). A single dose of solubilized DMBA suspension (40 mg/kg body weight) was orally administered to the animals at the age of 60 days to induce breast tumors. The tumor incidence, latency period, tumor frequency, and tumor volume were measured. Histology, immunohistochemistry, and immunoblotting were performed to evaluate the tumor morphology and expression levels of signal molecules. The development of mammary tumors in GR-Ob rats was characterized by early onset and shorter latency periods compared to control lean rats. While 62% of obese rats developed breast tumors, tumor development in lean rats was only 21%. Overexpression of ER, PR, Ki67, and p53 markers was observed in tumor tissues of obese rats in comparison with lean rats. The levels of the hallmarks of cell proliferation and angiogenesis involved in IGF-1/PI3K/Akt/GSK3β/β-catenin signaling pathway molecules were upregulated in obese rat breast tumors compared to lean rats. Furthermore, obesity with prediabetes is associated with changes in IGF-1 signaling and acts on PI3K/Akt/GSK3β/β-catenin signaling, which results in rapid cell proliferation and development of breast tumors in obese rats than the lean rats. These results indicate that tumor onset and development were faster in spontaneous obese rat models with impaired glucose tolerance than in their lean counterparts.

Genetic landscape of pancreatic adenocarcinoma patients: a pilot study from Pakistan

BACKGROUND

Pancreatic adenocarcinoma is one of the most aggressive malignancies with extremely low survival rate. Studies have shown that the exploration of key genes can provide a basis for targeted treatment of these patients. The genomic architecture of the Pakistani pancreatic adenocarcinoma patients remains unexplored. Keeping the scenario in place, the current study aims to analyse 88 cancer related genes in Pakistani pancreatic adenocarcinoma patients in order to elucidate candidate gene(s) for targeted molecular therapy.

METHODS AND RESULTS

A total 18 patients were included in the study initially and FFPE tumor samples were obtained. After confirmation of diagnosis and appropriate tumor content, DNA was extracted. Based on the quality and quantity of the extracted DNA, six pancreatic adenocarcinoma tumor samples were selected. Following to this, all the samples were subjected to targeted sequencing (Axen Cancer Panel 1). Variant detection was done and clinical significance of identified variants was assessed using ClinVar database. Targeted sequencing of tumor samples revealed a total of 29 alterations in the coding region of various genes. Among these five pathogenic variants were found in KRAS, BRCA1, TP53 and APC genes.

CONCLUSION

This is the first study that explores genes involved in pancreatic adenocarcinoma from the Pakistani population. Results obtained from the pilot study can guide us about the key genetic players in the Pakistani pancreatic adenocarcinoma population. This can lead to our better understanding of the molecular targeted therapies for these patients and designing future researches on larger sample size.

Increased formation of reactive oxygen species during tumor growth: Ex vivo low-temperature EPR and in vivo bioluminescence analyses

Previous studies have shown that reactive oxygen species (ROS) such as superoxide or hydrogen peroxide generated at low levels can exert a tumor-promoting role via a redox-signaling mechanism. Reports also suggest that both tumorigenesis and tumor growth are associated with enhanced ROS formation. However, whether ROS levels or ROS-derived oxidative marker levels increase during tumor growth remains unknown. In this study, in vivo bioluminescence imaging with a boronate-based pro-luciferin probe was used to assess ROS formation. Additionally, probe-free cryogenic electron paramagnetic resonance was used to quantify a characteristic aconitase [3Fe4S]⁺ center that arises in the tumor tissue of mouse xenografts from the reaction of the native [4Fe4S]²⁺ cluster with superoxide. Results indicated that tumor growth is accompanied by increased ROS formation, and revealed differences in oxidant formation in the inner and outer sections of tumor tissue, respectively, demonstrating redox heterogeneity. Studies using luciferin and pro-luciferin probes enabled the assessment of tumor size, ROS formation, and bioenergetic status (e.g., ATP) in luciferase-transfected mice tumor xenografts. Probe-free ex vivo low-temperature electron paramagnetic resonance can also be translated to clinical studies.

Mutant p53 on the Path to Metastasis

Metastasis contributes to the vast majority of cancer-related mortality. Regulatory mechanisms of the multistep invasion-metastasis cascade are being unraveled. TP53 is the most frequently mutated gene across human cancers. Accumulating evidence has shown that mutations of TP53 not only lead to loss of function or dominant negative effects, but also promotes a gain of function. Specifically, gain of function mutant p53 promotes cancer cell motility, invasion, and metastasis. Here, we summarize the mechanisms and functions of mutant p53 that foster metastasis in different types of cancers. We also discuss the prognostic value of mutant p53 and current status of therapeutic strategies targeting mutant p53. Future studies will shed light on discovering novel mechanisms of mutant p53-driven cancer metastasis and developing innovative therapeutics to improve clinical outcomes in patients harboring p53 mutations.

Association between p53 Expression and Amount of Tumor-Infiltrating Lymphocytes in Triple-Negative Breast Cancer

Background

Most triple-negative breast cancers (TNBCs) have a high histologic grade, are associated with high endoplasmic stress, and possess a high frequency of TP53 mutations. TP53 missense mutations lead to the production of mutant p53 protein and usually show high levels of p53 protein expression. Tumor-infiltrating lymphocytes (TILs) accumulate as part of the anti-tumor immune response and have a strong prognostic and predictive significance in TNBC. We aimed to elucidate the association between p53 expression and the amount of TILs in TNBC.

Methods

In 678 TNBC patients, we evaluated TIL levels and expression of endoplasmic stress molecules. Immunohistochemical examination of p53 protein expression was categorized into three groups: no, low, and high expression.

Results

No, low, and high p53 expression was identified in 44.1% (n = 299), 20.1% (n = 136), and 35.8% (n = 243) of patients, respectively. Patients with high p53 expression showed high histologic grade (p < .001), high TIL levels (p = .009), and high expression of endoplasmic reticulum stress-associated molecules (p-eIF2a, p = .013; XBP1, p = .007), compared to patients with low p53 expression. There was no significant difference in disease-free (p = .406) or overall survival rates (p = .444) among the three p53 expression groups.

Conclusions

High p53 expression is associated with increased expression of endoplasmic reticulum stress molecules and TIL influx.

The Roles of p53 in Mitochondrial Dynamics and Cancer Metabolism: The Pendulum between Survival and Death in Breast Cancer?

Cancer research has been heavily geared towards genomic events in the development and progression of cancer. In contrast, metabolic regulation, such as aberrant metabolism in cancer, is poorly understood. Alteration in cellular metabolism was once regarded simply as a consequence of cancer rather than as playing a primary role in cancer promotion and maintenance. Resurgence of cancer metabolism research has identified critical metabolic reprogramming events within biosynthetic and bioenergetic pathways needed to fulfill the requirements of cancer cell growth and maintenance. The tumor suppressor protein p53 is emerging as a key regulator of metabolic processes and metabolic reprogramming in cancer cells&mdash;balancing the pendulum between cell death and survival. This review provides an overview of the classical and emerging non-classical tumor suppressor roles of p53 in regulating mitochondrial dynamics: mitochondrial engagement in cell death processes in the prevention of cancer. On the other hand, we discuss p53 as a key metabolic switch in cellular function and survival. The focus is then on the conceivable roles of p53 in breast cancer metabolism. Understanding the metabolic functions of p53 within breast cancer metabolism will, in due course, reveal critical metabolic hotspots that cancers advantageously re-engineer for sustenance. Illustration of these events will pave the way for finding novel therapeutics that target cancer metabolism and serve to overcome the breast cancer burden.

MiR-539 inhibits proliferation and migration of triple-negative breast cancer cells by down-regulating LAMA4 expression

Background

Recent studies have shown that laminin subunit alpha 4 (LAMA4) plays an important role in carcinogenesis. However, its molecular biological function in triple-negative breast cancer (TNBC) has not been entirely clarified. This study investigated the expression of LAMA4 in TNBC and its effect on cell proliferation, migration and invasion. Furthermore, we also identified the potential miRNA directly targeting LAMA4.

Methods

Western blot, Real-time quantitative PCR (qPCR) and immunohistochemical staining (IHC) were used to detect the expression of LAMA4 in TNBC. The effects of LAMA4 on TNBC cell proliferation, migration and invasion were also explored in vitro. The potential miRNA that targets LAMA4 was determined by dual luciferase reporter assay and verified by qPCR and western blot analysis.

Results

Our study showed LAMA4 mRNA (p = 0.001) and protein (p = 0.005) expression in TNBC tissue samples were elevated compared with adjacent normal tissue samples, and LAMA4 was mainly expressed in the cytoplasm of breast carcinoma cells. Knockdown of LAMA4 inhibited TNBC cell proliferation, migration and invasion in vitro. Moreover, further study revealed that LAMA4 was a putative target of miR-539, and miR-539 negatively regulated LAMA4 expression by directly targeting its 3′-UTR.

Conclusions

Our study suggested that miR-539 suppressed the expression of LAMA4. LAMA4 plays an important role in tumor progression and may be an important target in treatment of TNBC.

Alterations in expression levels of genes in p53-related pathways determined using RNA-Seq analysis in patients with breast cancer following CIK therapy

The present study aimed at investigating the underlying molecular mechanisms for patients following cytokine-induced killer (CIK) therapy, particularly involving the alterations in p53-associated signaling pathways, to elucidate whether CIK therapy serves a function in cancer treatment. Samples of blood were collected from patients with breast cancer prior to and following CIK therapy. Two group samples were used for RNA sequencing (RNA-Seq) to determine the alterations in gene expression levels following CIK therapy and one for the quantitative polymerase chain reaction (qPCR), to analyze the reliability of RNA-Seq results. The genes that may encode proteins associated with p53 pathways were selected and analyzed. The expression levels of 8 genes were analyzed, including tumor suppressor protein 53 (TP53), murine double minute homolog 2 (MDM2), ribosomal protein L11 (RPL11), ribosomal protein S23 (RPS23), sirtuin 1, histone deacetylase 1, tuberous sclerosis complex 1 (TSC1) and mechanistic target of rapamycin (mTOR), and alterations in expression levels following CIK therapy were determined. However, only RPL11 and RPS23 were identified to exhibit marked alterations in expression levels (FDR <0.05), which was considered to be due to individual distinctions. qPCR analysis revealed that the expression levels of the RPL11, TP53 and TSC1 genes were downregulated, and those of the RPS23 and MDM2 genes were upregulated following CIK therapy. Only MDM2 exhibited a marked alteration in the gene expression level following CIK therapy. Alterations in the expression levels of TP53, RPL11 and TSC1 were associated with those of MDM2, RPS23 and mTOR, respectively.

Factors Associated with (18)F-Fluorodeoxyglucose Uptake in T1 and T2 Invasive Ductal Carcinoma of the Breast

PURPOSE

The objective of this study was to investigate the relationship between diversity of (18)F-fluorodeoxyglucose ((18)F-FDG) uptake of primary tumor in positron emission tomography (PET) and various clinicopathologic factors in breast cancer of same pathologic T1, T2 stage.

METHODS

A total of 258 patients with invasive ductal breast cancer were enrolled in this study. All patients underwent (18)F-FDG PET-CT before surgery. Patients were divided into two groups according to tumor size based on the pathologic T stage, and maximum standardized uptake value (SUVmax) of 2.5, respectively.

RESULTS

On the univariate analysis, estrogen receptor (ER), tumor size, lymphovascular invasion, p53, pathologic N status (pN) and Nottingham tumor grade (NG) were associated with high SUVmax in T1 and T2 breast cancer. On the multivariate logistic regression, tumor size and NG remained significant variables dividing high and low SUVmax. In the T1 group, ER, p53 and NG were significantly associated with high SUVmax on the univariate analysis. In this group, p53 and NG remained significant variables for dividing high and low SUVmax on the multivariate logistic regression. In the T2 group, only NG was associated with high SUVmax on the univariate analysis.

CONCLUSIONS

NG showed an association with (18)F-FDG uptake in both T1 and T2 breast cancer independently; however, p53 in T1 breast cancer.

TP53 Mutational Analysis Enhances the Prognostic Accuracy of IHC4 and PAM50 Assays

IHC4 and PAM50 assays have been shown to provide additional prognostic information for patients with early breast cancer. We evaluated whether incorporating TP53 mutation analysis can further enhance their prognostic accuracy. We examined TP53 mutation and the IHC4 score in tumors of 605 patients diagnosed with stage I-III breast cancer at National Taiwan University Hospital (the NTUH cohort). We obtained information regarding TP53 mutation and PAM50 subtypes in 699 tumors from the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) cohort. We found that TP53 mutation was significantly associated with high-risk IHC4 group and with luminal B, HER2-enriched, and basal-like subtypes. Despite the strong associations, TP53 mutation independently predicted shorter relapse-free survival (hazard ratio [HR] = 1.63, P = 0.007) in the NTUH cohort and shorter breast cancer-specific survival (HR = 2.35, P = <0.001) in the METABRIC cohort. TP53 mutational analysis added significant prognostic information in addition to the IHC4 score (∆ LR-χ(2) = 8.61, P = 0.002) in the NTUH cohort and the PAM50 subtypes (∆ LR-χ(2) = 18.9, P = <0.001) in the METABRIC cohort. We conclude that incorporating TP53 mutation analysis can enhance the prognostic accuracy of the IHC4 and PAM50 assays.

Tumor-Derived Cell Lines as Molecular Models of Cancer Pharmacogenomics

Compared with normal cells, tumor cells have undergone an array of genetic and epigenetic alterations. Often, these changes underlie cancer development, progression, and drug resistance, so the utility of model systems rests on their ability to recapitulate the genomic aberrations observed in primary tumors. Tumor-derived cell lines have long been used to study the underlying biologic processes in cancer, as well as screening platforms for discovering and evaluating the efficacy of anticancer therapeutics. Multiple -omic measurements across more than a thousand cancer cell lines have been produced following advances in high-throughput technologies and multigroup collaborative projects. These data complement the large, international cancer genomic sequencing efforts to characterize patient tumors, such as The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC). Given the scope and scale of data that have been generated, researchers are now in a position to evaluate the similarities and differences that exist in genomic features between cell lines and patient samples. As pharmacogenomics models, cell lines offer the advantages of being easily grown, relatively inexpensive, and amenable to high-throughput testing of therapeutic agents. Data generated from cell lines can then be used to link cellular drug response to genomic features, where the ultimate goal is to build predictive signatures of patient outcome. This review highlights the recent work that has compared -omic profiles of cell lines with primary tumors, and discusses the advantages and disadvantages of cancer cell lines as pharmacogenomic models of anticancer therapies.

RADIA: RNA and DNA integrated analysis for somatic mutation detection

The detection of somatic single nucleotide variants is a crucial component to the characterization of the cancer genome. Mutation calling algorithms thus far have focused on comparing the normal and tumor genomes from the same individual. In recent years, it has become routine for projects like The Cancer Genome Atlas (TCGA) to also sequence the tumor RNA. Here we present RADIA (RNA and DNA Integrated Analysis), a novel computational method combining the patient-matched normal and tumor DNA with the tumor RNA to detect somatic mutations. The inclusion of the RNA increases the power to detect somatic mutations, especially at low DNA allelic frequencies. By integrating an individual's DNA and RNA, we are able to detect mutations that would otherwise be missed by traditional algorithms that examine only the DNA. We demonstrate high sensitivity (84%) and very high precision (98% and 99%) for RADIA in patient data from endometrial carcinoma and lung adenocarcinoma from TCGA. Mutations with both high DNA and RNA read support have the highest validation rate of over 99%. We also introduce a simulation package that spikes in artificial mutations to patient data, rather than simulating sequencing data from a reference genome. We evaluate sensitivity on the simulation data and demonstrate our ability to rescue back mutations at low DNA allelic frequencies by including the RNA. Finally, we highlight mutations in important cancer genes that were rescued due to the incorporation of the RNA.

Significance of immunohistochemistry in breast cancer

The biological characteristics of the tumour are used to estimate prognosis and select appropriate systemic therapy for patients with (breast) cancer. The advent of molecular technology has incorporated new biomarkers along with immunohistochemical and serum biomarkers. Immunohistochemical markers are often used to guide treatment decisions, to classify breast cancer into subtypes that are biologically distinct and behave differently, and both as prognostic and predictive factors. Steroid hormone receptors, markers of tumour proliferation, and factors involved in angiogenesis and apoptosis are of scientific interest. In this review we will provide information on the immunohistochemical markers used in the management of breast cancer patients using available data from the literature. We consider the utility of established immunohistochemical markers, and discuss the challenges involved in integrating novel molecular markers into clinical practice.

PIK3CA and TP53 gene mutations in human breast cancer tumors frequently detected by ion torrent DNA sequencing

Breast cancer is the most common malignancy and the leading cause of cancer deaths in women worldwide. While specific genetic mutations have been linked to 5-10% of breast cancer cases, other environmental and epigenetic factors influence the development and progression of the cancer. Since unique mutations patterns have been observed in individual cancer samples, identification and characterization of the distinctive breast cancer molecular profile is needed to develop more effective target therapies. Until recently, identifying genetic cancer mutations via personalized DNA sequencing was impractical and expensive. The recent technological advancements in next-generation DNA sequencing, such as the semiconductor-based Ion Torrent sequencing platform, has made DNA sequencing cost and time effective with more reliable results. Using the Ion Torrent Ampliseq Cancer Panel, we sequenced 737 loci from 45 cancer-related genes to identify genetic mutations in 105 human breast cancer samples. The sequencing analysis revealed missense mutations in PIK3CA, and TP53 genes in the breast cancer samples of various histologic types. Thus, this study demonstrates the necessity of sequencing individual human cancers in order to develop personalized drugs or combination therapies to effectively target individual, breast cancer-specific mutations.

Biological markers and response to neoadjuvant taxane-based chemotherapy in patients with locally advanced breast cancer

Introduction. Biological markers as Her2/neu, p53, and hormonal receptors (HmRs) may be reliable parameters for prognostic assessment of patients of locally advanced breast cancer (LABC). This work aims at assessing the potential value of these biological markers for the prediction of disease outcome after neoadjuvant taxane-based chemotherapy and its implication on the surgical role. Patients and Methods. From March 2006 to September 2011, 95 patients with LABC were treated by neoadjuvant taxane-based chemotherapy given at intervals of 3 weeks. Expression of Her2/neu and p53 was examined in the initial tissue biopsy by using ELISA technique. Status of HmRs was determined using a commercial enzyme immunoassay. Three weeks after the third cycle, patients underwent surgical resection followed by 3 more cycles of taxane-based chemotherapy and radiotherapy as an adjuvant therapy. Relations of Her2/neu overexpression to p53, HmRs, and conventional prognostic factors were analyzed. Results. Median followup was 61 months. The 5-year DFS and OAS rates were significantly higher in patients with positive HmRs than in those with negative HmRs, patients with Her2- than those with Her2+ breast cancer, and patients with intact p53 breast cancer than those with inactive p53. HER-2 overexpression was statistically significant associated with loss of HmR positive immunostaining (P < 0.0001), grade III breast cancer (P < 0.0001), advanced nodal status (P = 0.0039), and younger (<50 years) age (P = 0.0108). Conclusion. Her2/neu overexpression was associated with poor DFS and OAS rates, as it was significantly associated with negative HmR and high grade.

The impact of p53 in predicting clinical outcome of breast cancer patients with visceral metastasis

In the study, we analyzed role of p53 in predicting outcome in visceral metastasis breast cancer (VMBC) patients. 97 consecutive VMBC patients were studied. P53 positivity rate was 29.9%. In the p53-negative group, median disease free survival (DFS), and time from primary breast cancer diagnosis to death (OS1), time from metastases to death (OS2) were 25, 42.5, and 13.5 months, respectively. In the p53-positive group, they were 10, 22, and 8 months, respectively. Statistically significant differences in DFS and OS1 were detected between the p53-negative and p53-positive subtypes. However, p53 appears to have no influence on OS2. In Cox regression analysis, p53 expression and TNM stage were predictive factors of DFS. In the multivariate analysis, p53 expression and the duration of DFS correlated with OS1, but not for OS2. Taken together, our data indicate p53 showing predicting role in OS1 for VMBC, but not for OS2.

Mutation Analysis of TP53 Tumor Suppressor Gene in Colorectal Cancer in Patients from Iran (Kerman Province)

OBJECTIVES

P53 is an important tumor suppressor, which is mutated in later stages of many cancers and leads to resistance to chemotherapy. The aim of this study was to reveal mutations of TP53 in colorectal cancer in Kerman province.

MATERIALS AND METHODS

A total of Forty-three colon cancer specimens as paraffin block or fresh tissues, which passed stage IIIA, were selected. Three exons 5, 7 and 8 of P53 were amplified by PCR technique and sequenced directly.

RESULTS

The results showed two deletions at codon 140 and 142 in one tumor sample. GAT→AAT mutation at codon 184, and CGG→TGG mutation at codon 248 were seen in some tumor samples. Some mutations were also observed in middle of intron 7 in some tumor or normal tissues.

CONCLUSION

Some of those patients with mutation in P53 gene had metastasis in other organs. Therefore, genetic test before chemotherapy is helpful for successful treatment.

Assessing the value of CAN-gene mutations using MALDI-TOF MS

PURPOSE

To identify cancer-linked genes, Sjöblom et al. and Wood et al. performed a genome-wide mutation screening in human breast and colorectal cancers. 140 CAN-genes were found in breast cancer, which in turn contained overall 334 mutations. These mutations could prove useful for diagnostic and therapeutic purposes.

METHODS

We used a MALDI-TOF MS 40-plex assay for testing 40 loci within 21 high-ranking breast cancer CAN-genes. To confirm mutations, we performed single-plex assays and sequencing.

RESULTS

In general, the mutation rate of the analyzed loci in our sample cohort was very low. No mutation from the 40 loci analyzed could be found in the 6 cell lines. In tissue samples, a single breast cancer tissue sample showed heterozygosity at locus c.5834G>A within the ZFYVE26 gene (Zinc finger FYVE domain-containing gene 26).

CONCLUSIONS

Sjöblom et al./Wood et al. already showed that the vast majority of CAN-genes are mutated at very low frequency. Due to the fact that we only found one mutation in our cohort, we therefore assume that at the selected loci, mutations might be low-frequency events and therefore, more rarely detectable. However, further evaluation of the CAN-gene mutations in larger cohorts should be the aim of further studies.

Predictive value of pathological and immunohistochemical parameters for axillary lymph node metastasis in breast carcinoma

Background/Objective

While several prognostic factors have been identified in breast carcinoma, the clinical outcome remains hard to predict for individual patients. Better predictive markers are needed to help guide difficult treatment decisions. Axillary lymph node metastasis (ALNM) is one of the most important prognostic determinants in breast carcinoma; however, the reasons why tumors vary in their capability to result in axillary metastasis remain unclear. Identifying breast carcinoma patients at risk for ALNM would improve treatment planning. This study aimed to identify the factors associated with ALNM in breast carcinoma, with particular emphasis on basal-like phenotype.

Methods

Breast carcinoma patients (n = 210) who underwent breast conserving surgery and axillary lymph node dissection (ALND) (level I and II) or modified radical mastectomy were included in this study. Pathological and immunohistochemical data including individual receptor/gene status was collected for analysis. The basal phenotype status was ascertained using the basal cytokeratin markers CK5, CK14, CK17 and EGFR.

Results

ALNM was found in 55% (n = 116) of the patients. On univariate analysis, multicentric disease, large tumor size (>2 cm), vascular and lymphatic invasion, epithelial hyperplasia, necrosis, in situ carcinoma and perineural invasion were associated with higher risk for ALNM, whereas CK5, CK14, EGFR positivity and basal-like tumor type were associated with lower risk. On multivariate analysis, CK5 positivity (OR 0.003, 95%CI 0.000-0.23, p = 0.009) and lymphatic/vascular invasion (OR 17.94, 95%CI 4.78-67.30, p < 0.001) were found to be independent predictors.

Conclusions

Although the value of complete ALND has been questioned in invasive breast cancer patients, treatment decisions for breast carcinoma have been influenced by many parameters, including lymph node status. Since histopathologic characteristics and expression of biological markers varies among the same histologic subtypes of breast carcinoma, specific clinical and histopathologic features of the primary tumor and ALN status like sentinel node might be used to tailor the loco-regional and systemic treatment in different clinical settings.

Pathology of hereditary breast cancer

Background

Hereditary breast cancer runs in families where several members in different generations are affected. Most of these breast cancers are caused by mutations in the high penetrance genes BRCA1 and BRCA2 accounting for about 5% of all breast cancers. Other genes that include CHEK2, PTEN, TP53, ATM, STK11/LKB1, CDH1, NBS1, RAD50, BRIP1 and PALB2 have been described to be high or moderate penetrance breast cancer susceptibility genes, all contributing to the hereditary breast cancer spectrum. However, in still a part of familial hereditary breast cancers no relationship to any of these breast cancer susceptibility genes can be found. Research on new susceptibility genes is therefore ongoing.

Design

In this review we will describe the function of the today known high or moderate penetrance breast cancer susceptibility genes and the consequences of their mutated status. Furthermore, we will focus on the histology, the immunophenotype and genotype of breast cancers caused by mutations in BRCA1 and BRCA2 genes and the other high or moderate penetrance breast cancer susceptibility genes. Finally, an overview of the clinical implications of hereditary breast cancer patients will be provided.

Conclusion

This information leads to a better understanding of the morphological, immunohistochemical and molecular characteristics of different types of hereditary breast cancers. Further, these characteristics offer clues for diagnosis and new therapeutic approaches.

Comparison of DGGE and immunohistochemistry in the detection of TP53 variants in a Brazilian sample of sporadic breast tumors

The presence of TP53 gene mutations in breast cancer has been associated with worse prognosis. These mutations interfere with the ability of the p53 protein, a transcription factor, to regulate the expression of target genes. Unlike the wild-type protein, which is rapidly degraded in cells, mutated forms have increased half-life and accumulate in tumor cells. Immunohistochemistry (IHC) is widely used in Brazil in the determination of breast cancer patients' prognosis. However, this technique is not able to detect many altered forms of the p53 protein (false-negative results) and readily detects the accumulation of wild-type p53 (false-positive results) that is associated with non-tumoral processes. For these reasons, we have set out to compare the efficiency of IHC with a molecular technique that detects gene variations at the DNA level in the evaluation of Brazilian patients with sporadic breast cancer. We have used denaturing gradient gel electrophoresis (DGGE) to study the TP53 status in 45 tumors, finding 26 allelic variants, most of them located in exon 4. Comparing the two techniques, IHC showed a false-negative rate of 64% and a false-positive rate of 50%. These results confirm the inability of IHC to correctly detect TP53 status, reason because it should not be routinely used to establish prognosis of breast cancer patients in Brazilian Pathology Laboratories. We recommend the utilization of a screening method, such as DGGE, followed by sequencing of altered exonic fragments to correctly detect TP53 gene variants and establish the prognosis of breast cancer patients.

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.

High resolution melting for mutation scanning of TP53 exons 5-8

BACKGROUND

p53 is commonly inactivated by mutations in the DNA-binding domain in a wide range of cancers. As mutant p53 often influences response to therapy, effective and rapid methods to scan for mutations in TP53 are likely to be of clinical value. We therefore evaluated the use of high resolution melting (HRM) as a rapid mutation scanning tool for TP53 in tumour samples.

METHODS

We designed PCR amplicons for HRM mutation scanning of TP53 exons 5 to 8 and tested them with DNA from cell lines hemizygous or homozygous for known mutations. We assessed the sensitivity of each PCR amplicon using dilutions of cell line DNA in normal wild-type DNA. We then performed a blinded assessment on ovarian tumour DNA samples that had been previously sequenced for mutations in TP53 to assess the sensitivity and positive predictive value of the HRM technique. We also performed HRM analysis on breast tumour DNA samples with unknown TP53 mutation status.

RESULTS

One cell line mutation was not readily observed when exon 5 was amplified. As exon 5 contained multiple melting domains, we divided the exon into two amplicons for further screening. Sequence changes were also introduced into some of the primers to improve the melting characteristics of the amplicon. Aberrant HRM curves indicative of TP53 mutations were observed for each of the samples in the ovarian tumour DNA panel. Comparison of the HRM results with the sequencing results revealed that each mutation was detected by HRM in the correct exon. For the breast tumour panel, we detected seven aberrant melt profiles by HRM and subsequent sequencing confirmed the presence of these and no other mutations in the predicted exons.

CONCLUSION

HRM is an effective technique for simple and rapid scanning of TP53 mutations that can markedly reduce the amount of sequencing required in mutational studies of TP53.

Molecular subtypes of breast cancer in relation to paclitaxel response and outcomes in women with metastatic disease: results from CALGB 9342

INTRODUCTION

The response to paclitaxel varies widely in metastatic breast cancer. We analyzed data from CALGB 9342, which tested three doses of paclitaxel in women with advanced disease, to determine whether response and outcomes differed according to HER2, hormone receptor, and p53 status.

METHODS

Among 474 women randomly assigned to paclitaxel at a dose of 175, 210, or 250 mg/m2, adequate primary tumor tissue was available from 175. Immunohistochemistry with two antibodies and fluorescence in situ hybridization were performed to evaluate HER2 status; p53 status was determined by immunohistochemistry and sequencing. Hormone receptor status was obtained from pathology reports.

RESULTS

Objective response rate was not associated with HER2 or p53 status. There was a trend toward a shorter median time to treatment failure among women with HER2-positive tumors (2.3 versus 4.2 months; P = 0.067). HER2 status was not related to overall survival (OS). Hormone receptor expression was not associated with differences in response but was associated with longer OS (P = 0.003). In contrast, women with p53 over-expression had significantly shorter OS than those without p53 over-expression (11.5 versus 14.4 months; P = 0.002). In addition, triple negative tumors were more frequent in African-American than in Caucasian patients, and were associated with a significant reduction in OS (8.7 versus 12.9 months; P = 0.008).

CONCLUSION

None of the biomarkers was predictive of treatment response in women with metastatic breast cancer; however, survival differed according to hormone receptor and p53 status. Triple negative tumors were more frequent in African-American patients and were associated with a shorter survival.

Retinoblastoma pathway defects show differential ability to activate the constitutive DNA damage response in human tumorigenesis

Loss of G(1)-S control and aberrations of the p16(Ink4a)-cyclin D1/cyclin-dependent kinase (CDK) 4(6)-pRb-E2F-cyclin E/CDK2 pathway are common in human cancer. Previous studies showed that oncogene-induced aberrant proliferation, such as on cyclin E overexpression, causes DNA damage and checkpoint activation. Here, we show that, in a series of human colorectal adenomas, those with deregulation of cyclin D1 and/or p16(Ink4a) showed little evidence of constitutive DNA damage response (DDR), contrary to cyclin E-overexpressing higher-grade cases. These observations were consistent with diverse cell culture models with differential defects of retinoblastoma pathway components, as overexpression of cyclin D1 or lack of p16(Ink4a), either alone or combined, did not elicit detectable DDR. In contrast, inactivation of pRb, the key component of the pathway, activated the DDR in cultured human or mouse cells, analogous to elevated cyclin E. These results highlight differential effect of diverse oncogenic events on driving the 'cancer cell cycles' and their ability to deregulate the replication-driving CDK2 kinase and to alarm the DDR as a potential anticancer barrier in accordance with their hierarchical positions along the retinoblastoma pathway. Our data provide new insights into oncogene-evoked DDR in human tumorigenesis, with potential implications for individualized management of tumors with elevated cyclin D1 versus cyclin E, due to their distinct clinical variables and biological behavior.

p53 Alterations and protein accumulation in benign breast tissue and breast cancer risk: a cohort study

Disruption of p53 gene function seems to have a pivotal role in carcinogenesis. p53 gene changes occur before the development of breast cancer and therefore might influence breast cancer risk. We investigated the association between p53 protein accumulation and p53 mutations detected in benign breast tissue and risk of subsequent breast cancer. We conducted a case-control study nested within the cohort of 4,888 women in the Canadian National Breast Screening Study who were diagnosed with biopsy-confirmed benign breast disease during active follow-up. Cases were women with benign breast disease who subsequently developed breast cancer; five controls were matched to each case. p53 protein accumulation was assessed immunohistochemically using sections of paraffin-embedded benign breast tissue from 104 cases and 385 controls; for 82 of these cases and 327 of the controls, DNA was successfully extracted from the breast tissue for p53 gene analysis using PCR-single-strand conformation polymorphism/direct sequencing. p53 protein accumulation was associated with a 2-fold increase in risk of progression to breast cancer [adjusted odds ratio (OR), 2.16; 95% confidence interval (95% CI), 1.08-4.30], whereas p53 nucleotide changes overall were not associated with altered risk (adjusted OR, 1.22; 95% CI, 0.68-2.19); those with both p53 immunopositivity and a p53 nucleotide change had an OR (95% CI) of 3.20 (1.21-8.50). Nonpolymorphic intronic changes were associated with a 2.8-fold increase in risk (OR, 2.84; 95% CI, 1.09-7.41). The results of this study suggest that p53 protein accumulation and nonpolymorphic intronic changes in p53 are associated with increased risk of progression to breast cancer in women with benign breast disease.

Prognostic relevance of disseminated tumor cells in the bone marrow and biological factors of 265 primary breast carcinomas

Introduction

The prognostic significance of disseminated tumor cells in the bone marrow (DTC-BM) of breast cancer patients has been demonstrated in many studies. Yet, it is not clear which of the primary tumors' biological factors predict hematogenous dissemination. We therefore examined 'tissue micro arrays' (TMAs) of 265 primary breast carcinomas from patients with known bone marrow (BM) status for HER2, Topoisomerase IIα (Top IIa), Ki 67, and p53.

Methods

BM analysis was performed by cytospin preparation and immunocytochemical staining for cytokeratin (CK). TMAs were examined by immunohistochemistry (IHC) for HER2, Top IIa, Ki 67 and p53, and fluorescence in situ hybridization (FISH) for HER2.

Results

HER2 (2+/3+) was positive in 35/167 (21%) cases (FISH 24.3%), Top IIa (>10%) in 87/187 (46%), Ki 67 in 52/184 (28%) and p53 (>5%) in 61/174 cases (34%). Of 265 patients, 68 (25.7%) showed DTC-BM with a median of 2/2 × 10⁶ cells (1 to 1,500). None of the examined factors significantly predicted BM positivity. Significant correlation was seen between HER2 IHC and Top IIa (p = 0.06), Ki 67 (p = 0.031), and p53 (p < .001). Top IIa correlated with Ki 67 and p53, and Ki 67 also with p53 (p = 0.004). After a median follow-up of 60.5 months (7 to 255), the presence of DTC-BM showed prognostic relevance for overall survival (p = 0.03), whereas HER2 (IHC, p = 0.04; FISH, p = 0.03) and Ki 67 (p = 0.04) correlated with disease free survival, and HER2 with distant disease free survival (IHC, p = 0.06; FISH, p = 0.05).

Discussion

The congruence of the examined factors' expression rates indicates a causal line of suppressor, proliferation, and mitosis markers, and growth factor receptors. Hematogenous tumor cell spread seems to be an independent process. The examination of these factors on DTC-BM is the aim of ongoing research.

The p53 pathway in breast cancer

p53 mutation remains the most common genetic change identified in human neoplasia. In breast cancer, p53 mutation is associated with more aggressive disease and worse overall survival. The frequency of mutation in p53 is, however, lower in breast cancer than in other solid tumours. Changes, both genetic and epigenetic, have been identified in regulators of p53 activity and in some downstream transcriptional targets of p53 in breast cancers that express wild-type p53. Molecular pathological analysis of the structure and expression of constituents of the p53 pathway is likely to have value in diagnosis, in prognostic assessment and, ultimately, in treatment of breast cancer.