Mutations in p53, p53 protein overexpression and breast cancer survival

Prognostic impact of tumor-associated neutrophils in breast cancer

OBJECTIVES

Neutrophils are the most common type of leukocyte in mammals and play an essential role in the innate immune system and anti-cancer responses. However, recent studies identified the presence of tumor-associated neutrophils (TANs) as a poor prognostic factor. The present study investigated whether relationships exist between TANs and the clinicopathological factors and genetic status of breast cancer.

METHODS

A total of 196 breast cancer patients with sufficient biopsy, breast-conserving surgery, or mastectomy specimens between 2014 and 2021 in Hokuto Hospital were included.

RESULTS

TANs were individually counted in the tumor stroma (TS) and tumor nest (TN). A higher density of TANs in both TS and TN correlated with tumor size (TS P = 0.010; TN P = 0.001), a high histological grade (TS P < 0.001; TN P < 0.001), the histological type (TS P = 0.009; TN P = 0.034), a high ratio of lymph node metastasis (TS P < 0.001; TN P < 0.001), an advanced stage of cancer (TS P < 0.001; TN P = 0.002), intrinsic subtypes (TS P < 0.001; TN P < 0.001), ERBB2 (TS P < 0.001; TN P < 0.001), MAP3K1 (TS P = 0.002; TN P = 0.023), and TP53 (TS P < 0.001; TN P < 0.001). A higher density of TANs in TS and TN also correlated with shorter disease-free survival and overall survival (P < 0.001).

CONCLUSION

The present results suggest that a higher density of TANs correlates with unfavorable prognostic factors in breast cancer. Further research on clinicopathological and genetic factors associated with TANs in breast cancer is needed.

Inducing ferroptosis has the potential to overcome therapy resistance in breast cancer

Breast cancer is the most common type of malignancy among women. Due to the iron-dependent character of breast cancer cells, they are more sensitive to ferroptosis compared to normal cells. It is possible to reverse tumor resistance by inducing ferroptosis in breast cancer cells, thereby improving tumor treatment outcomes. Ferroptosis is highly dependent on the balance of oxidative and antioxidant status. When ferroptosis occurs, intracellular iron levels are significantly increased, leading to increased membrane lipid peroxidation and ultimately triggering ferroptosis. Ferroptotic death is a form of autophagy-associated cell death. Synergistic use of nanoparticle-loaded ferroptosis-inducer with radiotherapy and chemotherapy achieves more significant tumor suppression and inhibits the growth of breast cancer by targeting cancer tissues, enhancing the sensitivity of cells to drugs, reducing the drug resistance of cancer cells and the toxicity of drugs. In this review, we present the current status of breast cancer and the mechanisms of ferroptosis. It is hopeful for us to realize effective treatment of breast cancer through targeted ferroptosis.

Immunometabolism characteristics and a potential prognostic risk model associated with TP53 mutations in breast cancer

TP53, a gene with high-frequency mutations, plays an important role in breast cancer (BC) development through metabolic regulation, but the relationship between TP53 mutation and metabolism in BC remains to be explored. Our study included 1,066 BC samples from The Cancer Genome Atlas (TCGA) database, 415 BC cases from the Gene Expression Omnibus (GEO) database, and two immunotherapy cohorts. We identified 92 metabolic genes associated with TP53 mutations by differential expression analysis between TP53 mutant and wild-type groups. Univariate Cox analysis was performed to evaluate the prognostic effects of 24 TP53 mutation-related metabolic genes. By unsupervised clustering and other bioinformatics methods, the survival differences and immunometabolism characteristics of the distinct clusters were illustrated. In a training set from TCGA cohort, we employed the least absolute shrinkage and selection operator (LASSO) regression method to construct a metabolic gene prognostic model associated with TP53 mutations, and the GEO cohort served as an external validation set. Based on bioinformatics, the connections between risk score and survival prognosis, tumor microenvironment (TME), immunotherapy response, metabolic activity, clinical characteristics, and gene characteristics were further analyzed. It is imperative to note that our model is a powerful and robust prognosis factor in comparison to other traditional clinical features and also has high accuracy and clinical usefulness validated by receiver operating characteristic (ROC) and decision curve analysis (DCA). Our findings deepen our understanding of the immune and metabolic characteristics underlying the TP53 mutant metabolic gene profile in BC, laying a foundation for the exploration of potential therapies targeting metabolic pathways. In addition, our model has promising predictive value in the prognosis of BC.

Prognostic significance of RNA-based TP53 pathway function among estrogen receptor positive and negative breast cancer cases

TP53 and estrogen receptor (ER) are essential in breast cancer development and progression, but TP53 status (by DNA sequencing or protein expression) has been inconsistently associated with survival. We evaluated whether RNA-based TP53 classifiers are related to survival. Participants included 3213 women in the Carolina Breast Cancer Study (CBCS) with invasive breast cancer (stages I-III). Tumors were classified for TP53 status (mutant-like/wildtype-like) using an RNA signature. We used Cox proportional hazards models to estimate covariate-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for breast cancer-specific survival (BCSS) among ER- and TP53-defined subtypes. RNA-based results were compared to DNA- and IHC-based TP53 classification, as well as Basal-like versus non-Basal-like subtype. Findings from the diverse (50% Black), population-based CBCS were compared to those from the largely white METABRIC study. RNA-based TP53 mutant-like was associated with BCSS among both ER-negatives and ER-positives (HR (95% CI) = 5.38 (1.84-15.78) and 4.66 (1.79-12.15), respectively). Associations were attenuated when using DNA- or IHC-based TP53 classification. In METABRIC, few ER-negative tumors were TP53-wildtype-like, but TP53 status was a strong predictor of BCSS among ER-positives. In both populations, the effect of TP53 mutant-like status was similar to that for Basal-like subtype. RNA-based measures of TP53 status are strongly associated with BCSS and may have value among ER-negative cancers where few prognostic markers have been robustly validated. Given the role of TP53 in chemotherapeutic response, RNA-based TP53 as a prognostic biomarker could address an unmet need in 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.

TP53 mutations determined by targeted NGS in breast cancer: a case-control study

Background: Tumor protein 53 (TP53) gene mutations are identified in up to 37% of breast tumors especially in HER-2 positive and basal-like subtype. Previous studies have indicated TP53 mutations as a prognostic biomarker in breast cancer. However, most of these studies performed immunohistochemistry (IHC) for the detection of TP53 mutations.

Aim: The purpose of our study is to evaluate the role of TP53 somatic mutations detected via next-generation sequencing (NGS) as a potential prognostic marker in patients with breast cancer.

Materials and Methods: 82 female patients with Stage I–III breast cancer underwent NGS in paraffin blocks and blood samples during the period 25/09/2019 through 25/05/2021. 23 cases of somatic TP53 mutations and 23 cases of healthy controls were matched on age at diagnosis, menopausal status, histological subtype, histological grade, ki67 expression and disease stage.

Results: Mean age at diagnosis was 52.35 (SD; 11.47) years. The somatic TP53 mutation NM_000546.5:c.824G>A p.(Cys275Tyr) was most frequently detected. Co-existence of PIK3CA mutation was a common finding in somatic TP53-mutant tumors (4/23; 17.4%). Disease-free survival was shorter in TP53-mutated cases (16.3 months vs. 62.9 months). TP53 pathogenic somatic mutations were associated with a 8-fold risk of recurrence in the univariate Cox regression analysis (OR = 8.530, 95% CI: 1.81–40.117; p = 0.007).

Conclusions: Our case-control study suggests that TP53 somatic mutations detected by next-generation sequencing (NGS) are associated with an adverse prognosis in breast cancer.

PAM50- and immunohistochemistry-based subtypes of breast cancer and their relationship with breast cancer mortality in a population-based study

PURPOSE

We evaluated the prognostic ability of immunohistochemistry (IHC)-based vs. PAM50-based subtypes for breast cancer mortality in a population-based study of breast cancer.

METHODS

We included a total of 463 breast cancer cases from the population-based Long Island Breast Cancer Study Project (LIBCSP). IHC-based markers were abstracted from the medical records, while the PAM50-based intrinsic subtypes were assessed from tumor tissues using NanoString nCounter^® Analysis System. Cox proportional hazards models were used to estimate hazards ratios (HRs) for breast cancer-specific mortality associated with subtypes.

RESULTS

For IHC-based hormone receptor-positive (HR+) tumors (n = 361), 68.7% were classified as luminal subtypes by PAM50; for HR- tumors (n = 102), 95.1% were classified as non-luminal subtypes. Compared to HR+/HER2- subtype, HR- patients had significantly higher breast cancer mortality (HR-/HER2+: HR = 2.84, 95% CI = 1.58-5.11; triple-negative breast cancer: HR = 2.42, 95% CI = 1.44-4.06). Compared to luminal A, a higher mortality rate was observed for all other PAM50-based subtypes: luminal B (HR = 4.03, 95% CI = 1.97-8.22), HER2-enriched (HR = 6.82, 95% CI = 3.29-14.14) and basal-like (HR = 4.71, 95% CI = 2.24-9.93). Additional subtyping of HR+ patients by PAM50 provided future risk stratification where luminal B patients in this group had significant higher mortality than luminal A patients (HR = 3.93, 95% CI = 1.92-8.03). Similar results were also observed among 291 HR+/HER2- patients, but not among the HR- patients.

CONCLUSIONS

Our study suggests that for HR+ patients, especially HR+/HER2- patients, additional PAM50-based subtyping would provide better prognostic stratification and improve disease management.

Prognostic value of p53 expression in hormone receptor-positive and human epidermal growth factor receptor 2-negative breast cancer patients receiving neoadjuvant chemotherapy

PURPOSE

The aim of this study was to determine whether the outcome to neoadjuvant chemotherapy (NAC) can be predicted by analyzing p53 expression in hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer patients.

METHODS

We retrospectively reviewed 594 patients diagnosed with stage I-III HR-positive, HER2-negative breast cancer, and treated with NAC at the Asan Medical Center between 2008 and 2014. Expression of p53 was assessed, and overall survival (OS) and breast cancer-specific survival (BCSS) were investigated and compared between groups.

RESULTS

At a median follow-up period of 69.8 months, OS and BCSS were higher in the p53-negative (p53(-)) group than in the p53-positive (p53(+)) group. Five-year OS was 95.4% in the p53(-) and 92.1% in the p53(+) group (p = 0.005). BCSS was 96.2% in the p53(-) group and 93% in the p53(+) group (p = 0.008).

CONCLUSION

High expression of immunohistochemically detected p53 was strongly and significantly associated with decreased OS and BCSS than low p53 expression, suggesting that p53 may be a powerful prognostic factor in HR-positive, HER2-negative breast cancer patients receiving NAC.

Mechanisms of Resistance to Conventional Therapies for Osteosarcoma

Osteosarcoma (OS) is the most common primary bone tumor, mainly occurring in children and adolescents. Current standard therapy includes tumor resection associated with multidrug chemotherapy. However, patient survival has not evolved for the past decades. Since the 1970s, the 5-year survival rate is around 75% for patients with localized OS but dramatically drops to 20% for bad responders to chemotherapy or patients with metastases. Resistance is one of the biological processes at the origin of therapeutic failure. Therefore, it is necessary to better understand and decipher molecular mechanisms of resistance to conventional chemotherapy in order to develop new strategies and to adapt treatments for patients, thus improving the survival rate. This review will describe most of the molecular mechanisms involved in OS chemoresistance, such as a decrease in intracellular accumulation of drugs, inactivation of drugs, improved DNA repair, modulations of signaling pathways, resistance linked to autophagy, disruption in genes expression linked to the cell cycle, or even implication of the micro-environment. We will also give an overview of potential therapeutic strategies to circumvent resistance development.

Targeting Molecular Mechanisms Underlying Treatment Efficacy and Resistance in Osteosarcoma: A Review of Current and Future Strategies

Osteosarcoma is the most common primary malignant bone tumour in children and adolescents. Due to micrometastatic spread, radical surgery alone rarely results in cure. Introduction of combination chemotherapy in the 1970s, however, dramatically increased overall survival rates from 20% to approximately 70%. Unfortunately, large clinical trials aiming to intensify treatment in the past decades have failed to achieve higher cure rates. In this review, we revisit how the heterogenous nature of osteosarcoma as well as acquired and intrinsic resistance to chemotherapy can account for stagnation in therapy improvement. We summarise current osteosarcoma treatment strategies focusing on molecular determinants of treatment susceptibility and resistance. Understanding therapy susceptibility and resistance provides a basis for rational therapy betterment for both identifying patients that might be cured with less toxic interventions and targeting resistance mechanisms to sensitise resistant osteosarcoma to conventional therapies.

TP53 Mutations and Outcomes in Breast Cancer: Reading beyond the Headlines

TP53 is the most frequently mutated gene in breast cancer, but its role in survival is confounded by different studies concluding that TP53 mutations are associated with negative, neutral, or positive outcomes. Closer examination showed that many studies were limited by factors such as imprecise methods to detect TP53 mutations and small cohorts that combined patients treated with drugs having very different mechanisms of action. When only studies of patients receiving the same treatment(s) were compared, they tended to agree. These analyses reveal a role for TP53 in response to different treatments as complex as its different biological activities. We discuss studies that have assessed the role of TP53 mutations in breast cancer treatment and limitations in interpreting reported results.

Reproductive characteristics are associated with gene-specific promoter methylation status in breast cancer

BACKGROUND

Reproductive characteristics are well-established risk factors for breast cancer, but the underlying mechanisms are not fully resolved. We hypothesized that altered DNA methylation, measured in tumor tissue, could act in concert with reproductive factors to impact breast carcinogenesis.

METHODS

Among a population-based sample of women newly diagnosed with first primary breast cancer, reproductive history was assessed using a life-course calendar approach in an interviewer-administered questionnaire. Methylation-specific polymerase chain reaction and Methyl Light assays were used to assess gene promotor methylation status (methylated vs. unmethylated) for 13 breast cancer-related genes in archived breast tumor tissue. We used case-case unconditional logistic regression to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for associations with age at menarche and parity (among 855 women), and age at first birth and lactation (among a subset of 736 parous women) in association with methylation status.

RESULTS

Age at first birth > 27 years, compared with < 23 years, was associated with lower odds of methylation of CDH1 (OR = 0.44, 95% CI = 0.20-0.99) and TWIST1 (OR = 0.48, 95% CI = 0.28-0.82), and higher odds of methylation of BRCA1 (OR = 1.63, 95% CI = 1.14-2.35). Any vs. no lactation was associated with higher odds of methylation of the PGR gene promoter (OR = 1.59, 95% CI = 1.01-2.49). No associations were noted for parity and methylation in any of the genes assayed.

CONCLUSIONS

Our findings indicate that age at first birth, lactation and, perhaps age at menarche, are associated with gene promoter methylation in breast cancer, and should be confirmed in larger studies with robust gene coverage.

Novel Predictors of Breast Cancer Survival Derived from miRNA Activity Analysis

Purpose: Breast cancer is among the leading causes of cancer-related death; discovery of novel prognostic markers is needed to improve outcomes. Combining systems biology and epidemiology, we investigated miRNA-associated genes and breast cancer survival in a well-characterized population-based study.Experimental Design: A recently developed algorithm, ActMiR, was used to identify key miRNA "activities" corresponding to target gene degradation, which were predictive of breast cancer mortality in published databases. We profiled miRNA-associated genes in tumors from our well-characterized population-based cohort of 606 women with first primary breast cancer. Cox proportional hazards models were used to estimate HRs and 95% confidence intervals (CI), after 15+ years of follow-up with 119 breast cancer-specific deaths.Results: miR-500a activity was identified as a key miRNA for estrogen receptor-positive breast cancer mortality using public databases. From a panel of 161 miR-500a-associated genes profiled, 73 were significantly associated with breast cancer-specific mortality (FDR < 0.05) in our population, among which two clusters were observed to have opposing directions of association. For example, high level of SUSD3 was associated with reduced breast cancer-specific mortality (HR = 0.3; 95% CI, 0.2-0.4), whereas the opposite was observed for TPX2 (HR = 2.7; 95% CI, 1.8-3.9). Most importantly, we identified set of genes for which associations with breast cancer-specific mortality were independent of known prognostic factors, including hormone receptor status and PAM50-derived risk-of-recurrence scores. These results are validated in independent datasets.Conclusions: We identified novel markers that may improve prognostic efficiency while shedding light on molecular mechanisms of breast cancer progression. Clin Cancer Res; 24(3); 581-91. ©2017 AACR.

Analysis of Paired Primary-Metastatic Hormone-Receptor Positive Breast Tumors (HRPBC) Uncovers Potential Novel Drivers of Hormonal Resistance

We sought to identify genetic variants associated with disease relapse and failure to hormonal treatment in hormone-receptor positive breast cancer (HRPBC). We analyzed a series of HRPBC with distant relapse, by sequencing pairs (n = 11) of tumors (primary and metastases) at >800X. Comparative genomic hybridization was performed as well. Top hits, based on the frequency of alteration and severity of the changes, were tested in the TCGA series. Genes determining the most parsimonious prognostic signature were studied for their functional role in vitro, by performing cell growth assays in hormonal-deprivation conditions, a setting that mimics treatment with aromatase inhibitors. Severe alterations were recurrently found in 18 genes in the pairs. However, only MYC, DNAH5, CSFR1, EPHA7, ARID1B, and KMT2C preserved an independent prognosis impact and/or showed a significantly different incidence of alterations between relapsed and non-relapsed cases in the TCGA series. The signature composed of MYC, KMT2C, and EPHA7 best discriminated the clinical course, (overall survival 90,7 vs. 144,5 months; p = 0.0001). Having an alteration in any of the genes of the signature implied a hazard ratio of death of 3.25 (p<0.0001), and early relapse during the adjuvant hormonal treatment. The presence of the D348N mutation in KMT2C and/or the T666I mutation in the kinase domain of EPHA7 conferred hormonal resistance in vitro. Novel inactivating mutations in KMT2C and EPHA7, which confer hormonal resistance, are linked to adverse clinical course in HRPBC.

Vehicular Traffic-Related Polycyclic Aromatic Hydrocarbon Exposure and Breast Cancer Incidence: The Long Island Breast Cancer Study Project (LIBCSP)

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants, known human lung carcinogens, and potent mammary carcinogens in laboratory animals. However, the association between PAHs and breast cancer in women is unclear. Vehicular traffic is a major ambient source of PAH exposure.

OBJECTIVES

Our study aim was to evaluate the association between residential exposure to vehicular traffic and breast cancer incidence.

METHODS

Residential histories of 1,508 participants with breast cancer (case participants) and 1,556 particpants with no breast cancer (control participants) were assessed in a population-based investigation conducted in 1996-1997. Traffic exposure estimates of benzo[a]pyrene (B[a]P), as a proxy for traffic-related PAHs, for the years 1960-1995 were reconstructed using a model previously shown to generate estimates consistent with measured soil PAHs, PAH-DNA adducts, and CO readings. Associations between vehicular traffic exposure estimates and breast cancer incidence were evaluated using unconditional logistic regression.

RESULTS

The odds ratio (95% CI) was modestly elevated by 1.44 (0.78, 2.68) for the association between breast cancer and long-term 1960-1990 vehicular traffic estimates in the top 5%, compared with below the median. The association with recent 1995 traffic exposure was elevated by 1.14 (0.80, 1.64) for the top 5%, compared with below the median, which was stronger among women with low fruit/vegetable intake [1.46 (0.89, 2.40)], but not among those with high fruit/vegetable intake [0.92 (0.53, 1.60)]. Among the subset of women with information regarding traffic exposure and tumor hormone receptor subtype, the traffic-breast cancer association was higher for those with estrogen/progesterone-negative tumors [1.67 (0.91, 3.05) relative to control participants], but lower among all other tumor subtypes [0.80 (0.50, 1.27) compared with control participants].

CONCLUSIONS

In our population-based study, we observed positive associations between vehicular traffic-related B[a]P exposure and breast cancer incidence among women with comparatively high long-term traffic B[a]P exposures, although effect estimates were imprecise.

CITATION

Mordukhovich I, Beyea J, Herring AH, Hatch M, Stellman SD, Teitelbaum SL, Richardson DB, Millikan RC, Engel LS, Shantakumar S, Steck SE, Neugut AI, Rossner P Jr., Santella RM, Gammon MD. 2016. Vehicular traffic-related polycyclic aromatic hydrocarbon exposure and breast cancer incidence: the Long Island Breast Cancer Study Project (LIBCSP). Environ Health Perspect 124:30-38; http://dx.doi.org/10.1289/ehp.1307736.

Gene-Specific Promoter Methylation Status in Hormone-Receptor-Positive Breast Cancer Associates with Postmenopausal Body Size and Recreational Physical Activity

INTRODUCTION

Breast cancer, the leading cancer diagnosis among American women, is positively associated with postmenopausal obesity and little or no recreational physical activity (RPA). However, the underlying mechanisms of these associations remain unresolved. Aberrant changes in DNA methylation may represent an early event in carcinogenesis, but few studies have investigated associations between obesity/RPA and gene methylation, particularly in postmenopausal breast tumors where these lifestyle factors are most relevant.

METHODS

We used case-case unconditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CI) for the associations between body mass index (BMI=weight [kg]/height [m²]) in the year prior to diagnosis, or RPA (average hours/week), and methylation status (methylated vs. unmethylated) of 13 breast cancer-related genes in 532 postmenopausal breast tumor samples from the Long Island Breast Cancer Study Project. We also explored whether the association between BMI/RPA and estrogen/progesterone-receptor status (ER+PR+ vs. all others) was differential with respect to gene methylation status. Methylation-specific PCR and the MethyLight assay were used to assess gene methylation.

RESULTS

BMI 25-29.9kg/m², and perhaps BMI≥30kg/m², was associated with methylated HIN1 in breast tumor tissue. Cases with BMI≥30kg/m² were more likely to have ER+PR+ breast tumors in the presence of unmethylated ESR1 (OR=2.63, 95% CI 1.32-5.25) and women with high RPA were more likely to have ER+PR+ breast tumors with methylated GSTP1 (OR=2.33, 95% CI 0.79-6.84).

DISCUSSION

While biologically plausible, our findings that BMI is associated with methylated HIN1 and BMI/RPA are associated with ER+PR+ breast tumors in the presence of unmethylated ESR1 and methylated GSTP1, respectively, warrant further investigation. Future studies would benefit from enrolling greater numbers of postmenopausal women and examining a larger panel of breast cancer-related genes.

Cytogenetic significance of chromosome 17 aberrations and P53 gene mutations as prognostic markers in oral squamous cell carcinoma

BACKGROUND

Cytogenetic analysis has detected an accumulation of genetic lesions in oral cancers. Numerical changes in chromosome 17 might be associated with an up-regulation of p53 gene, and could contribute to critical events in carcinogenesis. The aim of this study was to reveal possible correlations between the numerical aberrations of chromosome 17, deletion or amplification of the P53 gene and histological grading in patients with oral squamous cell carcinoma (OSCC).

METHODS

This study was performed retrospectively on anonymous forty paraffin embedded specimens diagnosed with a primary OSCC. Sections were prepared for p53 immunohistochemical staining and FISH technique evaluation.

RESULTS

All studied cases showed a positive nuclear staining with different indices for the p53 protein. Furthermore, statistical analysis showed a significant difference between all histological types of OSCC. In term of P53 immunoreactivity well differentiated OSCC showed the highest, whereas poorly differentiated showed weakest. Regarding chromosome 17 aberrations and p53 gene mutations, Spearman correlation test revealed a statistical significant positive correlation between chromosome 17 abnormalities and p53 gene mutations as well as with the immunohistochemical expression of p53 proteins. Moreover, the positive association between p53 gene mutations and the expression of p53 protein was statistically significant.

CONCLUSION

In the light of the previous findings, we concluded that numerical aberrations of chromosome 17 and p53 gene mutations as well as expression of p53 protein have enormous influence on various cellular processes including differentiation and carcinogenesis. Such knowledge provides an easy and simplified approach to prognosis predilection for OSCC.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2015_232 .

Indoor air pollution exposure from use of indoor stoves and fireplaces in association with breast cancer: a case-control study

BACKGROUND

Previous studies suggest that polycyclic aromatic hydrocarbons (PAHs) may adversely affect breast cancer risk. Indoor air pollution from use of indoor stoves and/or fireplaces is an important source of ambient PAH exposure. However, the association between indoor stove/fireplace use and breast cancer risk is unknown. We hypothesized that indoor stove/fireplace use in a Long Island, New York study population would be positively associated with breast cancer and differ by material burned, and the duration and timing of exposure. We also hypothesized that the association would vary by breast cancer subtype defined by p53 mutation status, and interact with glutathione S-transferases GSTM1, T1, A1 and P1 polymorphisms.

METHODS

Population-based, case-control resources (1,508 cases/1,556 controls) were used to conduct unconditional logistic regression to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Breast cancer risk was increased among women reporting ever burning synthetic logs (which may also contain wood) in their homes (OR = 1.42, 95% CI 1.11, 1.84), but not for ever burning wood alone (OR = 0.93, 95% CI 0.77, 1.12). For synthetic log use, longer duration >7 years, older age at exposure (>20 years; OR = 1.65, 95% CI 1.02, 2.67) and 2 or more variants in GSTM1, T1, A1 or P1 (OR = 1.71, 95% CI 1.09, 2.69) were associated with increased risk.

CONCLUSIONS

Burning wood or synthetic logs are both indoor PAH exposure sources; however, positive associations were only observed for burning synthetic logs, which was stronger for longer exposures, adult exposures, and those with multiple GST variant genotypes. Therefore, our results should be interpreted with care and require replication.

TP53 mutation spectrum in breast cancer is subtype specific and has distinct prognostic relevance

PURPOSE

In breast cancer, the TP53 gene is frequently mutated and the mutations have been associated with poor prognosis. The prognostic impact of the different types of TP53 mutations across the different molecular subtypes is still poorly understood. Here, we characterize the spectrum and prognostic significance of TP53 mutations with respect to the PAM50 subtypes and integrative clusters (IC).

EXPERIMENTAL DESIGN

TP53 mutation status was obtained for 1,420 tumor samples from the METABRIC cohort by sequencing all coding exons using the Sanger method.

RESULTS

TP53 mutations were found in 28.3% of the tumors, conferring a worse overall and breast cancer-specific survival [HR = 2.03; 95% confidence interval (CI), 1.65-2.48, P < 0.001], and were also found to be an independent marker of poor prognosis in estrogen receptor-positive cases (HR = 1.86; 95% CI, 1.39-2.49, P < 0.001). The mutation spectrum of TP53 varied between the breast cancer subtypes, and individual alterations showed subtype-specific association. TP53 mutations were associated with increased mortality in patients with luminal B, HER2-enriched, and normal-like tumors, but not in patients with luminal A and basal-like tumors. Similar observations were made in ICs, where mutation associated with poorer outcome in IC1, IC4, and IC5. The combined effect of TP53 mutation, TP53 LOH, and MDM2 amplification on mortality was additive.

CONCLUSION

This study reveals that TP53 mutations have different clinical relevance in molecular subtypes of breast cancer, and suggests diverse roles for TP53 in the biology underlying breast cancer development.

A single nucleotide polymorphism in PIK3CA gene is inversely associated with P53 protein expression in breast cancer

Single nucleotide polymorphism (SNP) rs17849071 was recently reported to be inversely associated with PIK3CA amplification in follicular thyroid cancer, but the main function of this SNP remains unclear. In this study, by using PCR and sequencing method, we explored whether this SNP was associated with P53 expression status and other clinicopathological characteristics in 62 Chinese breast cancer (BCa) patients. In our results, P53 protein accumulation was significantly associated with HER2 overexpression (P = 0.013) and Ki-67 expression (P = 0.007), which were in accord with previous studies. Besides, there was a significantly inverse relationship between P53 protein expression and rs17849071 GT+GG genotype in Chinese BCa patients (P = 0.044). The SNP was not related to other important BCa markers such as estrogen receptor, progestin receptor, and HER2. Among different BCa intrinsic subtypes, no significant differences were found on P53 expression status (P = 0.356) or rs17849071 polymorphism (T>G) (P = 0.813). In conclusion, SNP rs17849071 GT+GG genotype was inversely associated with P53 protein accumulation in BCa samples. Studies with larger sample size focusing on exploring the relationship of rs17849071 polymorphisms, P53 accumulation, P53 mutations, and PIK3CA amplification might be needed.

Comparison of the clinicopathological features of invasive ductal, invasive lobular, and mixed (invasive ductal + invasive lobular) carcinoma of the breast

BACKGROUND

In this retrospective analysis, the clinicopathological features and pattern of metastatic spread of invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), and mixed ductal/lobular carcinoma (MDLC), together with the type and outcome of surgical intervention, were comparatively evaluated.

METHODS

A total of 633 breast cancer patients with histopathological subtype IDC, ILC or MDLC were included in the study. The mean age was 52.6 ± 12.7 years. Follow-up period ranged between 0 and 33 (median 6.0) years. The groups were compared with respect to age, tumor size, nodal involvement, stage, hormonal therapy, multicentricity, multifocality, bilaterality, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2)/neu, p53, and Ki67 expression, disease-free survival (DFS) and overall survival (OS) rates, and surgical approach.

RESULTS

The distribution of patients was as follows: IDC 508 (80.3 %), ILC 78 (12.3 %), MDLC 47 (7.4 %). Among the parameters evaluated, statistically significant differences were observed in mean tumor size (IDC 2.5 ± 1.98 cm, ILC 3.0 ± 1.8 cm, MDLC 3.2 ± 2.4 cm), advanced T stage (T3 + T4) at diagnosis (IDC 14.7 %, ILC 21.4 %, MDLC 25.6 %), N stage (N0 was dominant in IDC and ILC; N3 was dominant in MDLC), tumor-node-metastasis (TNM) stage (stage II was dominant in IDC and ILC; stage III was dominant in MDLC), HER2/neu expression (IDC 23.8 %, ILC 11.8 %, MDLC 21.4 %), and frequency of bone metastasis (IDC 14.3 %, ILC 17.9 %, MDLC 25.5 %).

CONCLUSIONS

MDLC-type tumors have different histopathological characteristics and are often diagnosed at advanced stage. However, their survival outcomes do not vary significantly from ILC and IDC.

Comparative study and meta-analysis of meta-analysis studies for the correlation of genomic markers with early cancer detection

A large number of common disorders, including cancer, have complex genetic traits, with multiple genetic and environmental components contributing to susceptibility. A literature search revealed that even among several meta-analyses, there were ambiguous results and conclusions. In the current study, we conducted a thorough meta-analysis gathering the published meta-analysis studies previously reported to correlate any random effect or predictive value of genome variations in certain genes for various types of cancer. The overall analysis was initially aimed to result in associations (1) among genes which when mutated lead to different types of cancer (e.g. common metabolic pathways) and (2) between groups of genes and types of cancer. We have meta-analysed 150 meta-analysis articles which included 4,474 studies, 2,452,510 cases and 3,091,626 controls (5,544,136 individuals in total) including various racial groups and other population groups (native Americans, Latinos, Aborigines, etc.). Our results were not only consistent with previously published literature but also depicted novel correlations of genes with new cancer types. Our analysis revealed a total of 17 gene-disease pairs that are affected and generated gene/disease clusters, many of which proved to be independent of the criteria used, which suggests that these clusters are biologically meaningful.

Age-specific gene expression signatures for breast tumors and cross-species conserved potential cancer progression markers in young women

Breast cancer in young women is more aggressive with a poorer prognosis and overall survival compared to older women diagnosed with the disease. Despite recent research, the underlying biology and molecular alterations that drive the aggressive nature of breast tumors associated with breast cancer in young women have yet to be elucidated. In this study, we performed transcriptomic profile and network analyses of breast tumors arising in Middle Eastern women to identify age-specific gene signatures. Moreover, we studied molecular alterations associated with cancer progression in young women using cross-species comparative genomics approach coupled with copy number alterations (CNA) associated with breast cancers from independent studies. We identified 63 genes specific to tumors in young women that showed alterations distinct from two age cohorts of older women. The network analyses revealed potential critical regulatory roles for Myc, PI3K/Akt, NF-κB, and IL-1 in disease characteristics of breast tumors arising in young women. Cross-species comparative genomics analysis of progression from pre-invasive ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) revealed 16 genes with concomitant genomic alterations, CCNB2, UBE2C, TOP2A, CEP55, TPX2, BIRC5, KIAA0101, SHCBP1, UBE2T, PTTG1, NUSAP1, DEPDC1, HELLS, CCNB1, KIF4A, and RRM2, that may be involved in tumorigenesis and in the processes of invasion and progression of disease. Array findings were validated using qRT-PCR, immunohistochemistry, and extensive in silico analyses of independently performed microarray datasets. To our knowledge, this study provides the first comprehensive genomic analysis of breast cancer in Middle Eastern women in age-specific cohorts and potential markers for cancer progression in young women. Our data demonstrate that cancer appearing in young women contain distinct biological characteristics and deregulated signaling pathways. Moreover, our integrative genomic and cross-species analysis may provide robust biomarkers for the detection of disease progression in young women, and lead to more effective treatment strategies.

Mortality risk of black women and white women with invasive breast cancer by hormone receptors, HER2, and p53 status

Background

Black women are more likely than white women to have an aggressive subtype of breast cancer that is associated with higher mortality and this may contribute to the observed black-white difference in mortality. However, few studies have investigated the black-white disparity in mortality risk stratified by breast cancer subtype, defined by estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) status. Furthermore, it is not known whether additional consideration of p53 protein status influences black-white differences in mortality risk observed when considering subtypes defined by ER, PR and HER2 status.

Methods

Four biomarkers were assessed by immunohistochemistry in paraffin-embedded breast tumor tissue from 1,204 (523 black, 681 white) women with invasive breast cancer, aged 35–64 years at diagnosis, who accrued a median of 10 years’ follow-up. Multivariable Cox proportional hazards regression models were fit to assess subtype-specific black-white differences in mortality risk.

Results

No black-white differences in mortality risk were observed for women with triple negative (ER-negative [ER-], PR-, and HER2-) subtype. However, older (50–64 years) black women had greater overall mortality risk than older white women if they had been diagnosed with luminal A (ER-positive [ER+] or PR+ plus HER2-) breast cancer (all-cause hazard ratio, HR, 1.88; 95% confidence interval, CI, 1.18 to 2.99; breast cancer-specific HR, 1.51; 95% CI, 0.83 to 2.74). This black-white difference among older women was further confined to those with luminal A/p53- tumors (all-cause HR, 2.22; 95% CI, 1.30 to 3.79; breast cancer-specific HR, 1.89; 95% CI, 0.93 to 3.86). Tests for homogeneity of race-specific HRs comparing luminal A to triple negative subtype and luminal A/p53- to luminal A/p53+ subtype did not achieve statistical significance, although statistical power was limited.

Conclusions

Our findings suggest that the subtype-specific black-white difference in mortality risk occurs mainly among older women diagnosed with luminal A/p53- breast cancer, which is most likely treatable. These results further suggest that factors other than subtype may be relatively more important in explaining the increased mortality risk seen in older black women.

Cellular mechanisms of zinc dysregulation: a perspective on zinc homeostasis as an etiological factor in the development and progression of breast cancer

Worldwide, breast cancer is the most commonly diagnosed cancer among women and is the leading cause of female cancer deaths. Zinc (Zn) functions as an antioxidant and plays a role in maintaining genomic stability. Zn deficiency results in oxidative DNA damage and increased cancer risk. Studies suggest an inverse association between dietary and plasma Zn levels and the risk for developing breast cancer. In contrast, breast tumor biopsies display significantly higher Zn levels compared with normal tissue. Zn accumulation in tumor tissue also correlates with increased levels of Zn importing proteins. Further, aberrant expression of Zn transporters in tumors correlates with malignancy, suggesting that altered metal homeostasis in the breast could contribute to malignant transformation and the severity of cancer. However, studies have yet to link dysregulated Zn transport and abnormal Zn-dependent functions in breast cancer development. Herein, we summarize studies that address the multi-modal role of Zn dyshomeostasis in breast cancer with respect to the role of Zn in modulating oxidative stress, DNA damage response/repair pathways and cell proliferation/apoptosis, and the relationship to aberrant regulation of Zn transporters. We also compare Zn dysregulation in breast tissue to that of prostate, pancreatic and ovarian cancer where possible.

Gene expression in extratumoral microenvironment predicts clinical outcome in breast cancer patients

Introduction

A gene expression signature indicative of activated wound responses is common to more than 90% of non-neoplastic tissues adjacent to breast cancer, but these tissues also exhibit substantial heterogeneity. We hypothesized that gene expression subtypes of breast cancer microenvironment can be defined and that these microenvironment subtypes have clinical relevance.

Methods

Gene expression was evaluated in 72 patient-derived breast tissue samples adjacent to invasive breast cancer or ductal carcinoma in situ. Unsupervised clustering identified two distinct gene expression subgroups that differed in expression of genes involved in activation of fibrosis, cellular movement, cell adhesion and cell-cell contact. We evaluated the prognostic relevance of extratumoral subtype (comparing the Active group, defined by high expression of fibrosis and cellular movement genes, to the Inactive group, defined by high expression of claudins and other cellular adhesion and cell-cell contact genes) using clinical data. To establish the biological characteristics of these subtypes, gene expression profiles were compared against published and novel tumor and tumor stroma-derived signatures (Twist-related protein 1 (TWIST1) overexpression, transforming growth factor beta (TGF-β)-induced fibroblast activation, breast fibrosis, claudin-low tumor subtype and estrogen response). Histological and immunohistochemical analyses of tissues representing each microenvironment subtype were performed to evaluate protein expression and compositional differences between microenvironment subtypes.

Results

Extratumoral Active versus Inactive subtypes were not significantly associated with overall survival among all patients (hazard ratio (HR) = 1.4, 95% CI 0.6 to 2.8, P = 0.337), but there was a strong association with overall survival among estrogen receptor (ER) positive patients (HR = 2.5, 95% CI 0.9 to 6.7, P = 0.062) and hormone-treated patients (HR = 2.6, 95% CI 1.0 to 7.0, P = 0.045). The Active subtype of breast microenvironment is correlated with TWIST-overexpression signatures and shares features of claudin-low breast cancers. The Active subtype was also associated with expression of TGF-β induced fibroblast activation signatures, but there was no significant association between Active/Inactive microenvironment and desmoid type fibrosis or estrogen response gene expression signatures. Consistent with the RNA expression profiles, Active cancer-adjacent tissues exhibited higher density of TWIST nuclear staining, predominantly in epithelium, and no evidence of increased fibrosis.

Conclusions

These results document the presence of two distinct subtypes of microenvironment, with Active versus Inactive cancer-adjacent extratumoral microenvironment influencing the aggressiveness and outcome of ER-positive human breast cancers.

p53 mutations in classic and pleomorphic invasive lobular carcinoma of the breast

Background

p53 is a tumor suppressor that is frequently mutated in human cancers. Although alterations in p53 are common in breast cancer, few studies have specifically investigated TP53 mutations in the breast cancer subtype invasive lobular carcinoma (ILC). Recently reported conditional mouse models have indicated that functional p53 inactivation may play a role in ILC development and progression. Since reports on the detection of TP53 mutations in the relatively favorable classic and more aggressive pleomorphic variants of ILC (PILC) are rare and ambiguous, we performed a comprehensive analysis to determine the mutation status of TP53 in these breast cancer subtypes.

Methods

To increase our understanding of p53-mediated pathways and the roles they may play in the etiology of classic ILC and PILC, we investigated TP53 mutations and p53 accumulation in a cohort of 22 cases of classic and 19 cases of PILC by direct DNA sequencing and immunohistochemistry.

Results

We observed 11 potentially pathogenic TP53 mutations, of which three were detected in classic ILC (13.6%) and 8 in PILC (42.1%; p = 0.04). While p53 protein accumulation was not significantly different between classic and pleomorphic ILC, mutations that affected structure and protein function were significantly associated with p53 protein levels.

Conclusion

TP53 mutations occur more frequently in PILC than classic ILC.

MET-dependent cancer invasion may be preprogrammed by early alterations of p53-regulated feedforward loop and triggered by stromal cell-derived HGF

MET, a receptor protein tyrosine kinase activated by hepatocyte growth factor (HGF), is a crucial determinant of metastatic progression. Recently, we have identified p53 as an important regulator of MET-dependent cell motility and invasion. This regulation occurs via feedforward loop suppressing MET expression by miR-34-dependent and -independent mechanisms. Here, by using Dicer conditional knockout, we provide further evidence for microRNA-independent MET regulation by p53. Furthermore, we show that while MET levels increase immediately after p53 inactivation, mutant cells do not contain active phosphorylated MET and remain non-invasive for a long latency period at contrary to cell culture observations. Evaluation of mouse models of ovarian and prostate carcinogenesis indicates that formation of desmoplastic stroma, associated production of HGF by stromal cells and coinciding MET phosphorylation precede cancer invasion. Thus, initiation mutation of p53 is sufficient for preprogramming motile and invasive properties of epithelial cells, but the stromal reaction may represent a critical step for their manifestation during cancer progression.

The influence of one-carbon metabolism on gene promoter methylation in a population-based breast cancer study

Abnormal methylation in gene promoters is a hallmark of the cancer genome; however, factors that may influence promoter methylation have not been well elucidated. As the one-carbon metabolism pathway provides the universal methyl donor for methylation reactions, perturbation of this pathway might influence DNA methylation and, ultimately, affect gene functions. Utilizing approximately 800 breast cancer tumor tissues from a large population-based study, we investigated the relationships between dietary and genetic factors involved in the one-carbon metabolism pathway and promoter methylation of a panel of 13 breast cancer-related genes. We found that CCND2, HIN1 and CHD1 were the most "dietary sensitive" genes, as methylation of their promoters was associated with intakes of at least two out of the eight dietary methyl factors examined. On the other hand, some micronutrients (i.e., B 2 and B 6) were more "epigenetically active" as their intake levels correlated with promoter methylation status in 3 out of the 13 breast cancer genes evaluated. Both positive (hypermethylation) and inverse (hypomethylation) associations with high micronutrient intake were observed. Unlike what we saw for dietary factors, we did not observe any clear patterns between one-carbon genetic polymorphisms and the promoter methylation status of the genes examined. Our results provide preliminary evidence that one-carbon metabolism may have the capacity to influence the breast cancer epigenome. Given that epigenetic alterations are thought to occur early in cancer development and are potentially reversible, dietary modifications may offer promising venues for cancer intervention and prevention.

Promoter methylation status and expression of estrogen receptor alpha in familial breast cancer patients

The hypermethylation of estrogen receptor alpha (ERα) promoter is a common molecular alteration in sporadic breast cancer (BC), but its involvement in familial BC remains largely unknown. In the present study, we analyzed the methylation statuses of four regions (ER1, ER3, ER4, and ER5) of the ERα promoter and the ERα expression levels of 113 familial BC patients in a Han Chinese Population from northeastern China and evaluated the association between major clinicopathological features and the hypermethylation statuses of the ERα gene. Tumor samples were analyzed for ERα methylation status by the methylation-specific polymerase chain reaction for ERα, PR, p53, BRCA-1, and BRCA-2 by immunohistochemical (IHC) staining and for Her-2 status by IHC and fluorescence in situ hybridization (FISH). ERα methylation was observed in tumor tissues in 47/113 (41.6%) familial BC patients. There were no significant differences in the methylation statuses among ER1 (20.4%), ER3 (18.6%), ER4 (17.7%), and ER5 (19.5%; χ (2) = 3.89, p > 0.05). An association between ERα expression level and its promoter methylation level was found. In addition, ERα methylation was significantly correlated with tumor size, PR expression, p53 nuclear accumulation, and BRCA-1 and BRCA-2 statuses. In conclusion, in familial BC patients, the level of ERα gene promoter methylation correlates with ERα expression, PR, p53 nuclear accumulation, and BRCA-1 and BRCA-2 statuses. Epigenetic alteration of ERα gene may play an important role in the pathogenesis of familial BC.

Prognostic significance of gene-specific promoter hypermethylation in breast cancer patients

The association between promoter methylation status and survival was investigated in a large cohort of women with breast cancer, participants in the Long Island Breast Cancer Study Project. Archived tumor tissues (n = 839) were collected from women diagnosed with a first primary invasive or in situ breast cancer in 1996-1997. Vital status was followed through the end of 2005 with a mean follow-up time of 8 years. Promoter methylation of eight breast cancer-related genes was assessed by MethyLight. The frequencies of methylation for HIN1, RASSF1A, DAPK1, GSTP1, CyclinD2, TWIST, CDH1 and RARβ were 62.9, 85.2, 14.1, 27.8, 19.6, 15.3, 5.8 and 27.6%, respectively. Since survival rates of in situ and invasive breast cancers are substantially different, survival analyses were conducted within 670 invasive cases with complete data on all genes. Age-adjusted Cox proportional hazards models revealed that GSTP1, TWIST and RARβ methylation was significantly associated with higher breast cancer-specific mortality. Methylation of GSTP1 and RARβ was significantly associated with higher all-cause mortality. To investigate the relationship between the number of methylated genes and breast cancer-specific mortality, we included previously published MethyLight data on p16 and APC methylation status. Breast cancer-specific mortality increased in a dose-dependent manner with increasing number of methylated genes (P (trend) = 0.002), although confidence intervals were wide. Our results suggest that promoter methylation, particularly for a panel of genes, has the potential to be used as a biomarker for predicting prognosis in breast cancer.

High expression of miR-21 in tumor stroma correlates with increased cancer cell proliferation in human breast cancer

Low-risk and high-risk breast cancer patients are stratified primarily according to their lymph node (LN) status and grading. However, some low-risk patients relapse, and some high-risk patients have a favorable clinical outcome, implying a need for better prognostic and predictive tests. Micro RNAs are often aberrantly expressed in cancer and microRNA-21 is upregulated in a variety of cancers, including breast cancer. High miR-21 levels have been associated with poor prognosis. To determine the cellular localization of miR-21 and to compare its expression levels with histopathological features, we performed in situ hybridization and semi-quantitative assessment of the miR-21 signal on 12 LN negative grade I (assumed low risk), and 12 LN positive grade II (high risk) breast cancers. miR-21 was predominantly seen in cancer associated fibroblast-like cells, with no difference in expression levels between grade I and grade II carcinomas. Immunohistochemical scoring of the prognostic proliferation marker Ki-67 and tumor suppressor p53 showed that the miR-21 expression levels significantly correlated with the Ki-67 score (p = 0.043), whereas no correlation between p53 and miR-21 was found. Our results indicate that miR-21 may contribute to improve clinical stratification according to growth rate and facilitate tailored treatment of breast cancer patients.

PPM1D gene amplification and overexpression in breast cancer: a qRT-PCR and chromogenic in situ hybridization study

PPM1D (protein phosphatase magnesium-dependent 1δ) maps to the 17q23.2 amplicon and is amplified in ∼8% of breast cancers. The PPM1D gene encodes a serine threonine phosphatase, which is involved in the regulation of several tumour suppressor pathways, including the p53 pathway. Along with others, we have recently shown that PPM1D is one of the drivers of the 17q23.2 amplicon and a promising therapeutic target. Here we investigate whether PPM1D is overexpressed when amplified in breast cancers and the correlations between PPM1D overexpression and amplification with clinicopathological features and survival of breast cancer patients from a cohort of 245 patients with invasive breast cancer treated with therapeutic surgery followed by adjuvant anthracycline-based chemotherapy. mRNA was extracted from representative sections of tumours containing >50% of tumour cells and subjected to TaqMan quantitative real-time PCR using primers for PPM1D and for two housekeeping genes. PPM1D overexpression was defined as the top quartile of expression levels. Chromogenic in situ hybridization with in-house-generated probes for PPM1D was performed. Amplification was defined as >50% of cancer cells with >5 signals per nucleus/large gene clusters. PPM1D overexpression and amplification were found in 25 and 6% of breast cancers, respectively. All cases harbouring PPM1D amplification displayed PPM1D overexpression. PPM1D overexpression was inversely correlated with expression of TOP2A, EGFR and cytokeratins 5/6 and 17. PPM1D amplification was significantly associated with HER2 overexpression, and HER2, TOP2A and CCND1 amplification. No association between PPM1D gene amplification and PPM1D mRNA overexpression with survival was observed. In conclusion, PPM1D is consistently overexpressed when amplified; however, PPM1D overexpression is more pervasive than gene amplification. PPM1D overexpression and amplification are associated with tumours displaying luminal or HER2 phenotypes. Co-amplification of PPM1D and HER2/TOP2A and CCND1 are not random events and may suggest the presence of a 'firestorm' genetic profile.

p53 nuclear accumulation and ERalpha expression in ductal hyperplasia of breast in a cohort of 215 Chinese women

Introduction

Women with ductal hyperplasia including usual ductal hyperplasia (UDH) and atypical ductal hyperplasia (ADH) have an increased risk of developing invasive ductal carcinoma (IDC) of breast. The importance of several molecular markers in breast cancer has been of considerable interest during recent years such as p53 and estrogen receptor alpha (ERα). However, p53 nuclear accumulation and ERα expression have not been assessed in ductal hyperplasia co-existing with ductal carcinoma in situ (DCIS) or IDC versus pure ductal hyperplasia without DCIS or IDC.

Materials and methods

We investigated p53 nuclear accumulation and ERα expression in breast ductal hyperplasia in a cohort of 215 Chinese women by immunohistochemistry (IHC), which included 129 cases of pure ductal hyperplasia, 86 cases of ductal hyperplasia co-existing with DCIS (41 cases) or IDC (45 cases).

Results

Nuclear p53 accumulation was identified in 22.8% of ADH (31/136), 41.5% of DCIS (17/41) and 42.2% of IDC (19/45), and no case of UDH (0/79). No difference in nuclear p53 accumulation was observed between pure ADH and ADH co-existing with DCIS (ADH/DCIS) or IDC (ADH/IDC) (P > 0.05). The positive rate of ERα expression was lower in ADH (118/136, 86.8%) than that in UDH (79/79, 100%) (P < 0.001), but higher than that in DCIS (28/41, 68.3%) or IDC (26/45, 57.8%) respectively (P < 0.001). The frequency of ERα expression was lower in ADH/DCIS (23/29, 79.31%) and ADH/IDC (23/30, 76.67%) than that in pure ADH (72/77, 93.51%) respectively (P < 0.05). There was a negative weak correlation between p53 nuclear accumulation and ERα expression as for ADH (coefficient correlation -0.51; P < 0.001).

Conclusions

Different pathological types of ductal hyperplasia of breast are accompanied by diversity in patterns of nuclear p53 accumulation and ERα expression. At least some pure ADH is molecularly distinct from ADH/CIS or ADH/IDC which indicated the two types of ADH are molecularly distinct entities although they have the same morphological appearance.