p21WAF1 expression in invasive breast cancer and its association with p53, AP-2, cell proliferation, and prognosis

PD-L1 intrinsically promotes the proliferation of breast cancer cells through the SKP2-p27/p21 axis

BACKGROUND

PD-L1 intrinsically promotes tumor progression through multiple mechanisms, which potentially leads to resistance to anti-PD-1/PD-L1 therapies. The intrinsic effect of PD-L1 on breast cancer (BC) cell proliferation has not been fully elucidated.

METHODS

we used proteomics, gene expression knockdown (KD), quantitative immunofluorescence (qIF), western blots, functional assays including colony-forming assay (CFA) and real-time cell analyzer (RTCA), and in vivo data using immunohistochemistry in breast cancer patients.

RESULTS

PD-L1 promoted BC cell proliferation by accelerating cell cycle entry at the G1-to-S phase transition. Global proteomic analysis of the differentially expressed nuclear proteins indicated the involvement of several proliferation-related molecules, including p21CIP1/WAF1. Western blotting and qIF demonstrated the higher expression of SKP2 and the lower expression of p21CIP1/WAF1 and p27Kip1 in PD-L1 expressing (PD-L1pos) cells as compared to PD-L1 KD (PD-L1KD) cells. Xenograft-derived cells and the TCGA BC dataset confirmed this relationship in vivo. Functionally, CFA and RTCA demonstrated the central role of SKP2 in promoting PD-L1-mediated proliferation. Finally, immunohistochemistry in 74 breast cancer patients confirmed PD-L1 and SKP-p21/p27 axis relationship, as it showed a highly statistically significant correlation between SKP2 and PD-L1 expression (p < 0.001), and both correlated significantly with the proliferation marker Ki-67 (p < 0.001). On the other hand, there was a statistically significant inverse relationship between PD-L1 and p21CIP1/WAF1 expression (p = 0.005). Importantly, double negativity for p21CIP1/WAF1 and p27Kip1 correlated significantly with PD-L1 (p < 0.001), SKP2 (p = 0.002), and Ki-67 (p = 0.002).

CONCLUSIONS

we have demonstrated the role of the SKP2-p27/p21 axis in intrinsic PD-L1-enhanced cell cycle progression. Inhibitors of SKP2 expression can alleviate resistance to ICPIs.

Cell Cycle Checkpoints p16 and p21-Strong Predictors of Clinicopathologic Outcomes in High-Grade Osteosarcoma

PURPOSE

In this study, we used a series of immunohistochemical measurements of 2 cell cycle regulators, p16 and p21, to evaluate their prognostic value, separately and in combination, for the disease outcomes.

METHOD

A total of 101 patients with high-grade osteosarcoma were included in this study. Clinicopathologic data were collected, and immunohistochemistry for p16 and p21 was performed and interpreted by 3 independent pathologists. Statistical analysis was performed to assess the strength of each of these markers relative to disease outcome.

RESULTS

Our results indicate that more than 90% expression (high) of p16 by immunohistochemistry on the initial biopsy has a strong predictive value for good histologic response to chemotherapy. The patients are also more likely to survive the past 5 years and less likely to develop metastasis than patients with less than 90% p16 (low) expression. The results for p21, on the other hand, show a unique pattern of relationship to the clinicopathologic outcomes of the disease. Patients with less than 1% (low) or more than 50% (high) expression of p21 by immunohistochemistry show a higher chance of metastasis, poor necrotic response to chemotherapy, and an overall decreased survival rate when compared with p21 expression between 1% and 50% (moderate). Our results also showed that the expression of p16 and combined p16 and p21 demonstrates a stronger predictive relationship to 5-year survival than tumor histologic necrosis and p21 alone.

DISCUSSION

The results of this study, once proven to be reproducible by a larger number of patients, will be valuable in the initial assessment and risk stratification of the patients for treatment and possibly the clinical trials.

Circulating Cell-Free DNA Reflects the Clonal Evolution of Breast Cancer Tumors

Simple Summary

Liquid biopsy of cell-free DNA (cfDNA) is proposed as potential method for the early detection of breast cancer (BC) metastases and following the clonal evolution of BC. Though the use of liquid biopsy is widely discussed, only few studies have demonstrated such usage so far. The aim of this study was to evaluate how accurately cfDNA resembles the genetic profile of tumor DNA and how liquid biopsy reflects the clonal evolution of 18 Eastern-Finnish BC cases with locoregional or distant metastases. Although notable discordance between the sequenced cfDNA and tumor DNA was observed, our results show that liquid biopsy reflects the heterogeneity and clonal evolution of BC and may help to identify potential driver variants and therapeutic targets that are not detected with the sequencing of tumor DNA. This information may be used to detect metastatic BC earlier and to support decision-making in clinical practice.

Abstract

Liquid biopsy of cell-free DNA (cfDNA) is proposed as a potential method for the early detection of breast cancer (BC) metastases and following the clonal evolution of BC. Though the use of liquid biopsy is a widely discussed topic in the field, only a few studies have demonstrated such usage so far. We sequenced the DNA of matched primary tumor and metastatic sites together with the matched cfDNA samples from 18 Eastern Finnish BC patients and investigated how well cfDNA reflected the clonal evolution of BC interpreted from tumor DNA. On average, liquid biopsy detected 56.2 ± 7.2% of the somatic variants that were present either in the matched primary tumor or metastatic sites. Despite the high discordance observed between matched samples, liquid biopsy was found to reflect the clonal evolution of BC and identify novel driver variants and therapeutic targets absent from the tumor DNA. Tumor-specific somatic variants were detected in cfDNA at the time of diagnosis and 8.4 ± 2.4 months prior to detection of locoregional recurrence or distant metastases. Our results demonstrate that the sequencing of cfDNA may be used for the early detection of locoregional and distant BC metastases. Observed discordance between tumor DNA sequencing and liquid biopsy supports the parallel sequencing of cfDNA and tumor DNA to yield the most comprehensive overview for the genetic landscape of BC.

Knockdown of the prognostic cancer stem cell marker Musashi-1 decreases radio-resistance while enhancing apoptosis in hormone receptor-positive breast cancer cells via p21WAF1/CIP1

Purpose

While the stem cell marker Musashi-1 (MSI-1) has been identified as a key player in a wide array of malignancies, few findings exist on its prognostic relevance and relevance for cancer cell death and therapy resistance in breast cancer.

Methods

First, we determined prognostic relevance of MSI-1 in database analyses regarding multiple survival outcomes. To substantiate findings, MSI-1 was artificially downregulated in MCF-7 breast cancer cells and implications for cancer stem cell markers, cell apoptosis and apoptosis regulator p21, proliferation and radiation response were analyzed via flow cytometry and colony formation. Radiation-induced p21 expression changes were investigated using a dataset containing patient samples obtained before and after irradiation and own in vitro experiments.

Results

MSI-1 is a negative prognostic marker for disease-free and distant metastasis-free survival in breast cancer and tends to negatively influence overall survival. MSI-1 knockdown downregulated stem cell gene expression and proliferation, but increased p21 levels and apoptosis. Similar to the MSI-1 knockdown effect, p21 expression was strongly increased after irradiation and was expressed at even higher levels in MSI-1 knockdown cells after irradiation. Finally, combined use of MSI-1 silencing and irradiation reduced cancer cell survival.

Conclusion

MSI-1 is a prognostic marker in breast cancer. MSI-1 silencing downregulates proliferation while increasing apoptosis. The anti-proliferation mediator p21 was upregulated independently after both MSI-1 knockdown and irradiation and even more after both treatments combined, suggesting synergistic potential. Radio-sensitization effects after combining radiation and MSI-1 knockdown underline the potential of MSI-1 as a therapeutic target.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-021-03743-y.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

High mutation burden of circulating cell-free DNA in early-stage breast cancer patients is associated with a poor relapse-free survival

BACKGROUND

High tumor mutation burden is shown to be associated with a poor clinical outcome. As the tumor-derived fraction of circulating cell-free DNA (cfDNA) is shown to reflect the genetic spectrum of the tumor, we examined whether the mutation burden of cfDNA could be used to predict the clinical outcomes of early-stage breast cancer (BC) patients.

METHODS

We selected a set of 79 Finnish early-stage BC cases with a good prognosis based on traditional prognostic parameters but some of which still developed relapsed disease during follow-up. cfDNA was isolated from the serum collected at the time of diagnosis, sequenced, and compared to matched primary tumors, clinical parameters, and survival data.

RESULTS

High cfDNA mutation burden was associated with the poor relapse-free survival (RFS) (P = .016, HR = 2.23, 95% Cl 1.16-4.27) when patients were divided into high and low mutation burden according to the median number of somatic variants. A high discordance was observed between the matched tumor and cfDNA samples, thus highlighting the challenges related to the liquid biopsy of early-stage cancer cases. Despite the low number of detected tumor-specific variants, the presence of tumor-specific somatic variants in the cfDNA was associated with the poor RFS (P = .009, HR = 2.31, 95% Cl 1.23-4.31).

CONCLUSIONS

Our results confirm previously observed challenges about the accuracy of liquid biopsy-based genotyping of early-stage cancers and support the parallel sequencing of tumor and cfDNA while also demonstrating how the presence of tumor-specific somatic variants and the high mutation burden in the cfDNA are both associated with the poor RFS, thus indicating the prognostic potential of liquid biopsy in the context of early-stage cancers.

Class I histone deacetylase inhibitor suppresses vasculogenic mimicry by enhancing the expression of tumor suppressor and anti-angiogenesis genes in aggressive human TNBC cells

Triple-negative breast cancer (TNBC) cells form angiogenesis-independent vessel-like structures to survive, known as vasculogenic mimicry (VM), contributing to a poor prognosis for cancer patients. Nuclear localized class I histone deacetylases (HDACs) enzymes, particularly HDACs 1, 2, 3 deacetylate chromatin histones, are overexpressed in cancers and epigenetically regulate the expression of genes involved in cancer initiation and progression. The specific HDAC inhibitor, entinostat, has been shown to attenuate tumor progression and metastasis in TNBC. In this study, we hypothesized that entinostat would enhance the expression of anti-angiogenic and tumor suppressor genes and would thus suppress VM structures in TNBC cells in a 3D Matrigel cell culture preclinical model. Our data indicated that invasive triple-negative MDA-MB-231, LM2-4 and BT-549 breast cancer cells, but not poorly invasive luminal MCF-7 cells, efficiently underwent matrix-associated VM formation. Approximately 80% of TNBC cells with the stem cell phenotype potential formed vessel-like structures when mixed with Matrigel and cultured in the low attachment tissue culture plate. The molecular mechanisms of VM formation are rather complex, while angiogenesis inhibitor genes are downregulated and pro-angiogenesis genes are upregulated in VM-forming cells. Our data revealed that treatment of the TNBC VM phenotype cells with entinostat epigenetically led to the re-expression of the anti-angiogenic genes, serpin family F member 1 (SERPINF1) and thrombospondin 2 (THBS2), and to that of the tumor suppressor genes, phosphatase and tensin homolog (PTEN) and p21, and reduced VM structures. We also found that treatment of the TNBC VM phenotype cells with entinostat downregulated the expression of vascular endothelial growth factor A (VEGF-A), and that of the epithelial-mesenchymal transition (EMT)-related genes, Vimentin and β-catenin. METABIRC and TCGA breast cancer cohort mRNA expression data analysis revealed that a high expression of the anti-angiogenesis-associated genes, THBS2, SERPINF1 and serpin family B member 5 (SERPINB5), and of the tumor suppressor gene, PTEN, was associated with a better overall survival (OS) of breast cancer patients. Taken together, the findings of this study demonstrate that HDACs 1, 2, 3 partly contribute to VM formation in TNBC cells; thus, HDACs may be an important therapeutic target for TNBC.

p21Waf1/Cip1: its paradoxical effect in the regulation of breast cancer

p21^Waf1/Cip1, the cyclin-dependent kinase (CDK) inhibitor belonging to the KIP/CIP family, was initially regarded as a tumor suppressor protein because it was recognized as the chief mediator of p53-dependent cell cycle arrest elicited by DNA damage. Conversely, it has been proposed that p21^Waf1/Cip1 may also function as an oncogene because it can inhibit apoptosis. Thus, p21^Waf1/Cip1 is regarded as a protein with a dual behavior, as its expression might cause potential benefits or dangerous effects in breast cancer. Consequently, careful planning is required in targeting p21^Waf1/Cip1 expression for therapy of breast cancer patients. This review illustrates the discovery and mechanisms of induction of p21^Waf1/Cip1. Then, we focus on elucidating the paradoxical effect of p21^Waf1/Cip1 expression on human breast carcinogenesis and explaining how the subcellular localization (nuclear or cytoplasmic) of p21^Waf1/Cip1 has an impact on both determining its fate as either cell-growth inhibitor or antiapoptotic molecule and, its effect on clinicopathological factors and prognosis of breast cancer patients. Moreover, we explore how the pattern of the p21^Waf1/Cip1 could affect the responsiveness of human breast cancer to chemotherapy. Furthermore, the pharmacological approaches to target p21^Waf1/Cip1 expression for therapy of breast cancer are clarified.

Clinical Significance of the Wild Type p53-Induced Phosphatase 1 Expression in Invasive Breast Cancer

BACKGROUND

Wild type p53-induced phosphatase 1 (Wip1), encoded by the protein phosphatase magnesium dependent 1 delta (PPM1D), inhibits p53. PPM1D amplification has been reported in breast cancer. Breast cancer can sometimes develop without a tumor protein 53 (TP53) mutation. In these cases, the p53 pathway might be disrupted by alternative mechanisms, and Wip1 is reported to be a key molecule involved.

MATERIALS AND METHODS

Primary invasive ductal carcinoma specimens were obtained from 201 cases, for which archival tissue samples for immunohistochemistry were available. We evaluated Wip1 and p21 protein expression (201 cases), Wip1 mRNA expression (63 cases), PPM1D DNA copy number (71 cases) and TP53 status (36 cases) using available samples among the 201 cases, and analyzed their relationships with clinicopathological factors and prognosis.

RESULTS

The nuclear expression of Wip1 protein was positive in 21 cases (10.4%). The PPM1D DNA copy number was significantly correlated with Wip1 protein expression. All cases with PPM1D amplification by single-nucleotide polymorphism comparative genomic hybridization array showed positive nuclear Wip1 expression. Wip1 protein expression was positively correlated with p21 expression. The tumors with positive Wip1 and negative p21 expression showed the poorest prognosis among all tumor types.

CONCLUSION

The protein expression of Wip1 might be regulated by PPM1D amplification, independent of TP53 status. Positive Wip1 and negative p21 expression was associated with the poorest prognosis and suggests the loss of p53 function.

Clinical usefulness of the free web-based image analysis application ImmunoRatio for assessment of Ki-67 labelling index in breast cancer

Aims

Ki-67 is a prognostic marker in breast cancer; however, the use of the Ki-67 labelling index (LI) in clinical practice requires a consistent and easily accessible scoring method. The present study evaluated the use of the free internet-based image analysis program ImmunoRatio to score Ki-67 LI in breast cancer in comparison with manual counting.

Methods

Ki-67 immunohistochemical detection was performed in 577 breast cancer cases, and the Ki-67 LI was determined by ImmunoRatio and manual counting.

Results

The Ki-67 LI determined by ImmunoRatio correlated well with that obtained by manual counting. The concordance rate between ImmunoRatio and manual counting was excellent (κ coefficient of 0.881) at a Ki-67 LI cut-off value of 20%. Cases with high Ki-67 LI by ImmunoRatio were associated with poor overall survival, in particular in the hormone receptor positive group.

Conclusions

The web-based automated image analysis program ImmunoRatio is an attractive alternative to manual counting to determine the Ki-67 LI in breast cancer.

Increased expression of senescence markers p14(ARF) and p16(INK4a) in breast cancer is associated with an increased risk of disease recurrence and poor survival outcome

AIMS

Breast cancer is a hormonally driven disease. Cellular senescence is an age-related irreversible cell cycle arrest at the G1 phase upon induction. The aim of this study was to characterize the expression patterns of the senescence markers p14(ARF) , p16(INK4a) and p21(WAF1/Cip1) during breast cancer progression in a large patient cohort.

METHODS AND RESULTS

We conducted a retrospective study of 1080 patients with invasive ductal carcinoma, no special type, over an 11-year period. We performed immunohistochemical staining on tissue microarrays that included normal, benign hyperplasia, ductal carcinoma in situ and invasive ductal carcinoma tissue from each patient. Invasive ductal carcinomas showed higher expression of p14(ARF) and p16(INK4a) but lower expression of p21(WAF1/Cip1) than non-malignant tissues. There were significant correlations of normal, benign, preinvasive and malignant tissues with p14(ARF) , p16(INK4a) and p21(WAF1/Cip1) expression (P < 0.05). Univariate comparison showed a correlation between high p16(INK4a) expression and poor survival (P = 0.000) and an increased risk of relapse (P = 0.000), whereas high p14(ARF) expression correlated only with an increased risk of relapse (P = 0.038). Multivariate analysis showed p16(INK4a) to be an important prognostic factor for overall survival (P = 0.011) and disease-free survival (P = 0.004), with p14(ARF) also being a significant prognostic factor for disease-free survival (P = 0.043). Moreover, patients showing both high p16(INK4a) expression and and high p14(ARF) expression had an adjusted three-fold increased risk of disease recurrence (P < 0.05) and a two-fold increased risk of all-cause-related death (P < 0.05).

CONCLUSIONS

These finding suggest p16(INK4a) expression and p14(ARF) expression may play an important role in the progression of proliferative breast tissue to invasive cancer, and may be useful as prognostic factors.

Combinational effects of hexane insoluble fraction of Ficus septica Burm. F. and doxorubicin chemotherapy on T47D breast cancer cells

OBJECTIVE

To evaluate the effects of n-hexane insoluble fraction (HIF) of Ficus septica leaves in combination with doxorubicin on cytotoxicity, cell cycle and apoptosis induction of breast cancer T47D cell lines.

METHODS

The in vitro drugs-stimulated cytotoxic effects were determined using MTT assay. Analysis of cell cycle distribution was performed using flowcytometer and the data was analyzed using ModFit LT 3.0 program. Apoptosis assay was carried out by double staining method using ethydium bromide-acridin orange. The expression of cleaved-poly (ADP-ribose) polymerase (PARP) on T47D cell lines was identified using immunocytochemistry.

RESULTS

The combination exhibited higher inhibitory effect on cell growth than the single treatment of doxorubicin in T47D cells. In addition, combination of doxorubicin and HIF increased the incidence of cells undergoing apoptosis. HIF could improve doxorubicin cytotoxic effect by changing the accumulation of cell cycle phase from G2/M to G1 phase. The combination also exhibited upregulation of cleaved-PARP in T47D cells.

CONCLUSIONS

Based on this results, HIF is potential to be developed as co-chemotherapeutic agent for breast cancer by inducing apoptosis and cell cycle arrest. However, the molecular mechanism need to be explored further.

Overexpression of microRNA-200c predicts poor outcome in patients with PR-negative breast cancer

Micro-RNAs are small, noncoding RNAs that act as tumor suppressors or oncogenes. MiR-200c is a member of the miR-200 family; it is known to be dysregulated in invasive breast carcinoma. MiR-200c maintains the epithelial-mesenchymal transition and inhibits cell migration and invasion. Recent studies showed that miR-200c regulated steroid hormone receptors, estrogen receptors (ER), and progesterone receptors (PR). The present study aimed to detect miR-200c in 172 invasive breast carcinoma cases selected from a prospective cohort enrolled in Kuopio, Eastern Finland, between 1990 and 1995. MiR-200c expression was determined with relative q-PCR, and results were compared to clinicopathological variables and patient outcome. We found that PR status combined with miR-200c expression was a significant marker of outcome. High miR-200c expression was associated with reduced survival in PR-negative cases (n = 68); low miR-200c expression indicated reduced survival in PR-positive cases (n = 86) (Cox regression: P = 0.002, OR = 3.433; and P = 0.004, OR = 4.176, respectively). In PR-negative cases, high miR-200c expression was associated with shortened relapse-free survival (Cox regression: P = 0.001, OR = 3.613); increased local/distant recurrence (Logistic regression: P = 0.006, OR = 3.965); and more frequent distant metastasis (Logistic regression: P = 0.015, OR = 3.390). We also found that high grade and low stage tumors were positively correlated with high miR-200c expression (Logistic regression for high grade tumors: P = 0.002, OR = 2.791 and for high stage tumors: P = 0.035, OR = 0.285). Our results indicated that miR-200c may play a role in invasive breast carcinoma. Furthermore, miR-200c combined with PR status provided a refined predictor of outcome. In future, a larger study is required to confirm our results. This data may provide a basis for new research target-progesterone receptor-regulated microRNAs in breast cancer.

Type II transmembrane serine protease gene variants associate with breast cancer

Type II transmembrane serine proteases (TTSPs) are related to tumor growth, invasion, and metastasis in cancer. Genetic variants in these genes may alter their function, leading to cancer onset and progression, and affect patient outcome. Here, 464 breast cancer cases and 370 controls were genotyped for 82 single-nucleotide polymorphisms covering eight genes. Association of the genotypes was estimated against breast cancer risk, breast cancer-specific survival, and survival in different treatment groups, and clinicopathological variables. SNPs in TMPRSS3 (rs3814903 and rs11203200), TMPRSS7 (rs1844925), and HGF (rs5745752) associated significantly with breast cancer risk (Ptrend = 0.008-0.042). SNPs in TMPRSS1 (rs12151195 and rs12461158), TMPRSS2 (rs2276205), TMPRSS3 (rs3814903), and TMPRSS7 (rs2399403) associated with prognosis (P = 0.004-0.046). When estimating the combined effect of the variants, the risk of breast cancer was higher with 4-5 alleles present compared to 0-2 alleles (P = 0.0001; OR, 2.34; 95% CI, 1.39-3.94). Women with 6-8 survival-associating alleles had a 3.3 times higher risk of dying of breast cancer compared to women with 1-3 alleles (P = 0.001; HR, 3.30; 95% CI, 1.58-6.88). The results demonstrate the combined effect of variants in TTSPs and their related genes in breast cancer risk and patient outcome. Functional analysis of these variants will lead to further understanding of this gene family, which may improve individualized risk estimation and development of new strategies for treatment of breast cancer.

MAPK kinase 3 is a tumor suppressor with reduced copy number in breast cancer

Cancers are initiated as a result of changes that occur in the genome. Identification of gains and losses in the structure and expression of tumor-suppressor genes and oncogenes lies at the root of the understanding of cancer cell biology. Here, we show that the mitogen-activated protein kinase (MAPK) MKK3 suppresses the growth of breast cancer, in which it varies in copy number. A pervasive loss of MKK3 gene copy number in patients with breast cancer is associated with an impairment of MKK3 expression and protein level in malignant tissues. To assess the functional role of MKK3 in breast cancer, we showed in an animal model that MKK3 activity is required for suppression of tumor growth. Active MKK3 enhanced expression of the cyclin-dependent kinase inhibitors p21(Cip1/Waf1) and p27(Kip1), leading to increased cell-cycle arrest in G1 phase of the cell cycle. Our results reveal the functional significance of MKK3 as a tumor suppressor and improve understanding of the dynamic role of the MAPK pathway in tumor progression.

Γ-secretase components as predictors of breast cancer outcome

γ-secretase is a large ubiquitously expressed protease complex composed of four core subunits: presenilin, Aph1, PEN-2, and nicastrin. The function of γ-secretase in the cells is to proteolytically cleave various proteins within their transmembrane domains. Presenilin and Aph1 occur as alternative variants belonging to mutually exclusive γ-secretase complexes and providing the complexes with heterogeneous biochemical and physiological properties. γ-secretase is proposed to have a role in the development and progression of cancer and γ-secretase inhibitors are intensively studied for their probable anti-tumor effects in various types of cancer models. Here, we for the first time determined mRNA expression levels of presenilin-1, presenilin-2, Aph1a, Aph1b, PEN-2, and nicastrin in a set of breast cancer tissue samples (N = 55) by quantitative real-time PCR in order to clarify the clinical significance of the expression of different γ-secretase complex components in breast cancer. We found a high positive correlation between the subunit expression levels implying a common regulation of transcription. Our univariate Kaplan-Meier survival analyses established low expression level of γ-secretase complex as a risk factor for breast cancer specific mortality. The tumors expressing low levels of γ-secretase complex were characterized by high histopathological tumor grade, low or no expression of estrogen and progesterone receptors and consequently high probability to fall into the class of triple negative breast cancer tumors. These results may provide novel tools to further categorize breast cancer tumors, especially the highly aggressive and poorly treatable breast cancer type of triple negative cases, and suggest a significant role for γ-secretase in breast cancer.

Matriptase-2 gene (TMPRSS6) variants associate with breast cancer survival, and reduced expression is related to triple-negative breast cancer

Matriptase-2 (TMPRSS6) has been identified as a breast cancer risk factor. Here, we examined relationships between TMPRSS6 genetic variations and breast cancer risk and survival, and determined the gene and protein expressions in breast tumors and assessed their clinical importance. Thirteen TMPRSS6 polymorphisms were genotyped in 462 invasive breast cancer cases and 458 controls. Gene expression was analyzed from 83 tumors and protein expression from 370 tumors. We then assessed the statistical significance of associations among genotypes, clinicopathological characteristics and survival. The TMPRSS6 variant rs2543519 was associated with breast cancer risk (p = 0.032). Multivariate analysis showed that four variants had effects on survival-rs2543519 (p = 0.017), rs2235324 (p = 0.038), rs14213212 (p = 0.044) and rs733655 (p = 0.021)-which were used to create a group variable that was associated with poorer prognosis correlating with more alleles related to reduced survival (p = 0.006; risk ratio, 2.375; 95% confidence interval, 1.287-4.382). Low gene expression was related to triple-negative breast cancer (p = 0.0001), and lower protein expression was detected in undifferentiated (p = 0.019), large (p = 0.014) and ductal or lobular tumors (p = 0.036). These results confirm the association of TMRRSS6 variants with breast cancer risk and survival. Matriptase-2 levels decrease with tumor progression, and lower gene expression is seen in poor-prognosis-related triple-negative breast cancers. Our study is the first to show that matriptase-2 gene variants are related to breast cancer prognosis, supporting matriptase-2 involvement in tumor development.

Gene expression signatures that predict outcome of tamoxifen-treated estrogen receptor-positive, high-risk, primary breast cancer patients: a DBCG study

Background

Tamoxifen significantly improves outcome for estrogen receptor-positive (ER+) breast cancer, but the 15-year recurrence rate remains 30%. The aim of this study was to identify gene profiles that accurately predicted the outcome of ER+ breast cancer patients who received adjuvant Tamoxifen mono-therapy.

Methodology/Principal Findings

Post-menopausal breast cancer patients diagnosed no later than 2002, being ER+ as defined by >1% IHC staining and having a frozen tumor sample with >50% tumor content were included. Tumor samples from 108 patients treated with adjuvant Tamoxifen were analyzed for the expression of 59 genes using quantitative-PCR. End-point was clinically verified recurrence to distant organs or ipsilateral breast. Gene profiles were identified using a model building procedure based on conditional logistic regression and leave-one-out cross-validation, followed by a non-parametric bootstrap (1000x re-sampling). The optimal profiles were further examined in 5 previously-reported datasets containing similar patient populations that were either treated with Tamoxifen or left untreated (n = 623). Three gene signatures were identified, the strongest being a 2-gene combination of BCL2-CDKN1A, exhibiting an accuracy of 75% for prediction of outcome. Independent examination using 4 previously-reported microarray datasets of Tamoxifen-treated patient samples (n = 503) confirmed the potential of BCL2-CDKN1A. The predictive value was further determined by comparing the ability of the genes to predict recurrence in an additional, previously-published, cohort consisting of Tamoxifen-treated (n = 58, p = 0.015) and untreated patients (n = 62, p = 0.25).

Conclusions/Significance

A novel gene expression signature predictive of outcome of Tamoxifen-treated patients was identified. The validation suggests that BCL2-CDKN1A exhibit promising predictive potential.

Histone demethylase GASC1--a potential prognostic and predictive marker in invasive breast cancer

Background

The histone demethylase GASC1 (JMJD2C) is an epigenetic factor suspected of involvement in development of different cancers, including breast cancer. It is thought to be overexpressed in the more aggressive breast cancer types based on mRNA expression studies on cell lines and meta analysis of human breast cancer sets. This study aimed to evaluate the prognostic and predictive value of GASC1 for women with invasive breast cancer.

Methods

All the 355 cases were selected from a cohort enrolled in the Kuopio Breast Cancer Project between April 1990 and December 1995. The expression of GASC1 was studied by immunohistochemistry (IHC) on tissue microarrays. Additionally relative GASC1 mRNA expression was measured from available 57 cases.

Results

In our material, 56% of the cases were GASC1 negative and 44% positive in IHC staining. Women with GASC1 negative tumors had two years shorter breast cancer specific survival and time to relapse than the women with GASC1 positive tumors (p=0.017 and p=0.034 respectively). The majority of GASC1 negative tumors were ductal cases (72%) of higher histological grade (84% of grade II and III altogether). When we evaluated estrogen receptor negative and progesterone receptor negative cases separately, there was 2 times more GASC1 negative than GASC1 positive tumors in each group (chi2, p= 0.033 and 0.001 respectively). In the HER2 positive cases, there was 3 times more GASC1 negative cases than GASC1 positives (chi2, p= 0.029). Patients treated with radiotherapy (n=206) and hormonal treatment (n=62) had better breast cancer specific survival, when they were GASC1 positive (Cox regression: HR=0.49, p=0.007 and HR=0.33, p=0.015, respectively). The expression of GASC1 mRNA was in agreement with the protein analysis.

Conclusions

This study indicates that the GASC1 is both a prognostic and a predictive factor for women with invasive breast cancer. GASC1 negativity is associated with tumors of more aggressive histopathological types (ductal type, grade II and III, ER negative, PR negative). Patients with GASC1 positive tumors have better breast cancer specific survival and respond better to radiotherapy and hormonal treatment.

Ki-67: level of evidence and methodological considerations for its role in the clinical management of breast cancer: analytical and critical review

Clinicians can use biomarkers to guide therapeutic decisions in estrogen receptor positive (ER+) breast cancer. One such biomarker is cellular proliferation as evaluated by Ki-67. This biomarker has been extensively studied and is easily assayed by histopathologists but it is not currently accepted as a standard. This review focuses on its prognostic and predictive value, and on methodological considerations for its measurement and the cut-points used for treatment decision. Data describing study design, patients’ characteristics, methods used and results were extracted from papers published between January 1990 and July 2010. In addition, the studies were assessed using the REMARK tool. Ki-67 is an independent prognostic factor for disease-free survival (HR 1.05–1.72) in multivariate analyses studies using samples from randomized clinical trials with secondary central analysis of the biomarker. The level of evidence (LOE) was judged to be I-B with the recently revised definition of Simon. However, standardization of the techniques and scoring methods are needed for the integration of this biomarker in everyday practice. Ki-67 was not found to be predictive for long-term follow-up after chemotherapy. Nevertheless, high KI-67 was found to be associated with immediate pathological complete response in the neoadjuvant setting, with an LOE of II-B. The REMARK score improved over time (with a range of 6–13/20 vs. 10–18/20, before and after 2005, respectively). KI-67 could be considered as a prognostic biomarker for therapeutic decision. It is assessed with a simple assay that could be standardized. However, international guidelines are needed for routine clinical use.

The relationship between transcription initiation RNAs and CCCTC-binding factor (CTCF) localization

BACKGROUND

Transcription initiation RNAs (tiRNAs) are nuclear localized 18 nucleotide RNAs derived from sequences immediately downstream of RNA polymerase II (RNAPII) transcription start sites. Previous reports have shown that tiRNAs are intimately correlated with gene expression, RNA polymerase II binding and behaviors, and epigenetic marks associated with transcription initiation, but not elongation.

RESULTS

In the present work, we show that tiRNAs are commonly found at genomic CCCTC-binding factor (CTCF) binding sites in human and mouse, and that CTCF sites that colocalize with RNAPII are highly enriched for tiRNAs. To directly investigate the relationship between tiRNAs and CTCF we examined tiRNAs originating near the intronic CTCF binding site in the human tumor suppressor gene, p21 (cyclin-dependent kinase inhibitor 1A gene, also known as CDKN1A). Inhibition of CTCF-proximal tiRNAs resulted in increased CTCF localization and increased p21 expression, while overexpression of CTCF-proximal tiRNA mimics decreased CTCF localization and p21 expression. We also found that tiRNA-regulated CTCF binding influences the levels of trimethylated H3K27 at the alternate upstream p21 promoter, and affects the levels of alternate p21 (p21alt) transcripts. Extending these studies to another randomly selected locus with conserved CTCF binding we found that depletion of tiRNA alters nucleosome density proximal to sites of tiRNA biogenesis.

CONCLUSIONS

Taken together, these data suggest that tiRNAs modulate local epigenetic structure, which in turn regulates CTCF localization.

ST14 gene variant and decreased matriptase protein expression predict poor breast cancer survival

BACKGROUND

Matriptase plays a role in carcinogenesis, but the role of its genetic variation or that of the hepatocyte growth factor activator inhibitor-1 (HAI-1) has not been evaluated. This study aimed to examine the genetic variation of matriptase (ST14 gene) and HAI-1 (SPINT1 gene) in breast cancer risk and prognosis, to assess matriptase and HAI-1 gene and protein expression in breast tumors, and to identify their clinicopathologic correlations and prognostic significance.

METHODS

Five single nucleotide polymorphisms in ST14 and three in SPINT1 were genotyped in 470 invasive breast cancer cases and 446 healthy controls. Gene expression analysis was done for 40 breast cancer samples. Protein expression was assessed by immunohistochemical analyses in 377 invasive breast tumors. The statistical significance of the associations among genotypes, clinicopathologic variables, and prognosis was assessed.

RESULTS

The ST14 single nucleotide polymorphism rs704624 independently predicted breast cancer survival, a poor outcome associated with the minor allele (P = 0.001; risk ratio, 2.221; 95% confidence interval, 1.382-3.568). Moreover, ST14 gene expression levels were lower among the minor allele carriers (P = 0.009), and negative/low matriptase protein expression was independently predictive of poorer survival (P = 0.046; risk ratio, 1.554; 95% confidence interval, 1.008-2.396).

CONCLUSIONS

The ST14 variant rs704624 and protein expression of matriptase have prognostic significance in breast cancer. This study adds to the evidence for the role of matriptase in breast cancer and has found new evidence for the genotypes having an impact in breast cancer.

IMPACT

This is the first study showing that genetic variation in matriptase has clinical importance. The results encourage further study on the genetic variation affecting protein levels and function in type II transmembrane serine proteases.

Essential role of cell cycle regulatory genes p21 and p27 expression in inhibition of breast cancer cells by arsenic trioxide

Arsenic trioxide (As2O3), a component of traditional Chinese medicine, has been used successfully for the treatment of acute promyelocytic leukemia (APL), and As2O3 is of potential therapeutic value for the treatment of other promyelocytic malignancies and some solid tumors including breast cancer. However, the precise molecular mechanisms through which As2O3 induces cell cycle arrest and apoptosis in solid tumors have not been clearly understood. The goal of our study is to gain insight into the general biological processes and molecular functions that are altered by As2O3 treatment in MCF-7 breast cancer cells and to identify the key signaling processes that are involved in the regulation of these physiological effects. In the present study, MCF-7 cells were treated with 5 μM As2O3, and the differential gene expression was then analyzed by DNA microarray. The results showed that As2O3 treatment changed the expression level of several genes that involved in cell cycle regulation, signal transduction, and apoptosis. Notably, As2O3 treatment increased the mRNA and protein levels of the cell cycle inhibitory proteins, p21 and p27. Interestingly, knocking down p21 or p27 individually did not alter As2O3-induced apoptosis and cell cycle arrest; however, the simultaneous down-regulation of both p21 and p27 resulted in attenuating of G1, G2/M arrest and reduction in apoptosis, thus indicating that p21 and p27 as the primary molecular targets of As2O3 against breast cancer. Overall, our results provide new insights into As2O3-related signaling activities, which may facilitate the development of As2O3-based anticancer strategies and/or combination therapies against solid tumors.

Interference with activator protein-2 transcription factors leads to induction of apoptosis and an increase in chemo- and radiation-sensitivity in breast cancer cells

Background

Activator Protein-2 (AP-2) transcription factors are critically involved in a variety of fundamental cellular processes such as proliferation, differentiation and apoptosis and have also been implicated in carcinogenesis. Expression of the family members AP-2α and AP-2γ is particularly well documented in malignancies of the female breast. Despite increasing evaluation of single AP-2 isoforms in mammary tumors the functional role of concerted expression of multiple AP-2 isoforms in breast cancer remains to be elucidated. AP-2 proteins can form homo- or heterodimers, and there is growing evidence that the net effect whether a cell will proliferate, undergo apoptosis or differentiate is partly dependent on the balance between different AP-2 isoforms.

Methods

We simultaneously interfered with all AP-2 isoforms expressed in ErbB-2-positive murine N202.1A breast cancer cells by conditionally over-expressing a dominant-negative AP-2 mutant.

Results

We show that interference with AP-2 protein function lead to reduced cell number, induced apoptosis and increased chemo- and radiation-sensitivity. Analysis of global gene expression changes upon interference with AP-2 proteins identified 139 modulated genes (90 up-regulated, 49 down-regulated) compared with control cells. Gene Ontology (GO) investigations for these genes revealed Cell Death and Cell Adhesion and Migration as the main functional categories including 25 and 12 genes, respectively. By using information obtained from Ingenuity Pathway Analysis Systems we were able to present proven or potential connections between AP-2 regulated genes involved in cell death and response to chemo- and radiation therapy, (i.e. Ctgf, Nrp1, Tnfaip3, Gsta3) and AP-2 and other main apoptosis players and to create a unique network.

Conclusions

Expression of AP-2 transcription factors in breast cancer cells supports proliferation and contributes to chemo- and radiation-resistance of tumor cells by impairing the ability to induce apoptosis. Therefore, interference with AP-2 function could increase the sensitivity of tumor cells towards therapeutic intervention.

Tumour markers predictive of successful treatment of breast cancer with primary endocrine therapy in patients over 70 years old: a prospective study

We report a prospective study of women over 70 years of age with early breast cancer who had primary endocrine treatment. Core biopsies of the cancer were taken at diagnosis and assessed using immunohistochemistry for oestrogen receptor (ER), progesterone receptor (PgR), epidermal growth factor receptor (EGFR), pS2, cyclin D1, p21, p53, HER2 and MIB1 (Ki67). Outcome analysis was performed at a median follow-up of 70 months. Correlation was sought between tumour marker measurements and disease control. When all patients were considered, a significant relationship was found between the absence of ER and PgR, the presence of p53 and EGFR, and high MIB1 and treatment failure. However, for the ER positive cancers, no other marker predicted treatment failure or relapse. There remains an important clinical need to identify those ER positive breast cancers that will not respond to endocrine treatment, and those in which the response will be short-lived.

FOXP3 up-regulates p21 expression by site-specific inhibition of histone deacetylase 2/histone deacetylase 4 association to the locus

p21 loss has been implicated in conferring oncogenic activity to known tumor suppressor gene KLF4 and cancer drug tamoxifen. Regulators of p21, therefore, play critical roles in tumorigenesis. Here, we report that X-linked tumor suppressor FOXP3 is essential for p21 expression in normal epithelia and that lack of FOXP3 is associated with p21 down-regulation in breast cancer samples. A specific FOXP3 binding site in the intron 1 is essential for p21 induction by FOXP3. FOXP3 specifically inhibited binding of histone deacetylase 2 (HDAC2) and HDAC4 to the site and increased local histone H3 acetylation. Short hairpin RNA silencing of either HDAC2 or HDAC4 is sufficient to induce p21 expression. Our data provides a novel mechanism for transcription activation by FOXP3 and a genetic mechanism for lack of p21 in a large proportion of breast cancer.

Cell cycle machinery: links with genesis and treatment of breast cancer

Loss of normal growth control is a hallmark of cancer. Thus, understanding the mechanisms of tissue-specific, normal growth regulation and the changes that occur during tumorigenesis may provide insights of both diagnostic and therapeutic importance. Control of cell proliferation in the normal mammary gland is steroid hormone (estrogen and progestin)-dependent, involves complex interactions with other hormones, growth factors and cytokines and ultimately converges on activation of three proto-oncogenes (c-Myc, cyclin D1 and cyclin E1) that are rate limiting for the G1 to S phase transition during normal cell cycle progression. Mammary epithelial cell-specific overexpression of these genes induces mammary carcinoma in mice, while cyclin D1 null mice have arrested mammary gland development and are resistant to carcinoma induced by the neu/erbB2 and ras oncogenes. Furthermore, c-Myc, cyclins D1, E1 and E2 are commonly overexpressed in primary breast cancer where elevated expression is often associated with a more aggressive disease phenotype and an adverse patient outcome. This may be due in part to overexpression of these genes conferring resistance to endocrine therapies since in vitro studies provide compelling evidence that overexpression of c-Myc and to a lesser extent cyclin D1 and cyclin E1, attenuate the growth inhibitory effects of SERMS, antiestrogens and progestins in breast cancer cells. Thus, abnormal regulation of the expression of cell cycle molecules, involved in the steroidal control of cell proliferation in the mammary gland, are likely to be directly involved in the development, progression and therapeutic responsiveness of breast cancer. Furthermore, a more detailed understanding of these pathways may identify new targets for therapeutic intervention particularly in endocrine-unresponsive and endocrine-resistant disease.

Ki-67 as prognostic marker in early breast cancer: a meta-analysis of published studies involving 12,155 patients

The Ki-67 antigen is used to evaluate the proliferative activity of breast cancer (BC); however, Ki-67's role as a prognostic marker in BC is still undefined. In order to better define the prognostic value of Ki-67/MIB-1, we performed a meta-analysis of studies that evaluated the impact of Ki-67/MIB-1 on disease-free survival (DFS) and/or on overall survival (OS) in early BC. Sixty-eight studies were identified and 46 studies including 12 155 patients were evaluable for our meta-analysis; 38 studies were evaluable for the aggregation of results for DFS, and 35 studies for OS. Patients were considered to present positive tumours for the expression of Ki-67/MIB-1 according to the cut-off points defined by the authors. Ki-67/MIB-1 positivity is associated with higher probability of relapse in all patients (HR=1.93 (95% confidence interval (CI): 1.74–2.14); P<0.001), in node-negative patients (HR=2.31 (95% CI: 1.83–2.92); P<0.001) and in node-positive patients (HR=1.59 (95% CI: 1.35–1.87); P<0.001). Furthermore, Ki-67/MIB-1 positivity is associated with worse survival in all patients (HR=1.95 (95% CI: 1.70–2.24; P<0.001)), node-negative patients (HR=2.54 (95% CI: 1.65–3.91); P<0.001) and node-positive patients (HR=2.33 (95% CI: 1.83–2.95); P<0.001). Our meta-analysis suggests that Ki-67/MIB-1 positivity confers a higher risk of relapse and a worse survival in patients with early BC.

Activator protein-2 in carcinogenesis with a special reference to breast cancer-A mini review

Activator protein-2 (AP-2) transcription factors are involved in the regulation of cell proliferation, differentiation, apoptosis and carcinogenesis. AP-2alpha has been suggested to function as a tumor suppressor in many cancers and AP-2gamma to be a marker of testicular and germ cell malignancies. At least 3 of the 5 AP-2 family members identified to date, AP-2alpha, AP-2beta and AP-2gamma, are known to be expressed in breast tissue and thought to coordinate the growth and development of the breast via regulation of several breast-related genes such as human epidermal growth factor receptor-2 (HER2) and estrogen receptor (ER). The function of AP-2alpha seems to be tumor suppressive in breast tissue, whereas the role of the other AP-2 family members is less well known. In this review, we summarize the current knowledge of AP-2 in carcinogenesis, especially in breast cancer.

Expression of p21WAF in salivary gland mucoepidermoid carcinoma and its relation to histologic grade

The biologic behavior and factors influencing the development of salivary gland mucoepidermoid carcinoma are not fully understood. Alteration of the cyclin-dependant kinase inhibitor p21(WAF) could cause uncontrolled proliferation leading to cancer. Thirty-five mucoepidermoid carcinomas were graded and immunohistochemically stained for p21(WAF). The percentage of positive tumor cells was determined using an eyepiece graticule and a computer-assisted image analyzer, which revealed 8.6% and 22.9% of the cases to be positive for p21(WAF), respectively. A statistically significant correlation was not observed between p21(WAF) and grading. Considering the absence of p21(WAF) expression in most mucoepidermoid carcinomas, it appears that the inhibitory effect of p21(WAF) on cell growth is removed in most cases. Given the lack of correlation with tumor grade, it is possible that the impact of p21(WAF) is in the earlier stages of tumorigenesis. A p53-independent pathway of p21(WAF) induction may exist for the small proportion of tumors that showed positivity.

Loss of AP-2alpha results in deregulation of E-cadherin and MMP-9 and an increase in tumorigenicity of colon cancer cells in vivo

Activator protein-2 (AP-2) is a transcription factor that regulates proliferation and differentiation in mammalian cells and has been implicated in the acquisition of the metastatic phenotype in several types of cancer. Herein, we examine the role of AP-2alpha in colon cancer progression. We provide evidence for the lack of AP-2alpha expression in the late stages of colon cancer cells. Re-expression of the AP-2alpha gene in the AP-2alpha-negative SW480 colon cancer cells suppressed their tumorigenicity following orthotopic injection into the cecal wall of nude mice. The inhibition of tumor growth could be attributed to the increased expression of E-cadherin and decreased expression and activity of matrix-metalloproteinase-9 (MMP-9) in the transfected cells, as well as a substantial loss of their in vitro invasive properties. Conversely, targeting constitutive expression of AP-2alpha in AP-2-positive KM12C colon cancer cells with small interfering RNA resulted in an increase in their invasive potential, downregulation of E-cadherin and increased expression of MMP-9. In SW480 cells, re-expression of AP-2alpha resulted in a fourfold increase in the activity of E-cadherin promoter, and a 5-14-fold decrease in the activity of MMP-9 promoter, indicating transcriptional regulation of these genes by AP-2alpha. Chromatin immunoprecipitation assay showed that re-expressed AP-2alpha directly binds to the promoter of E-cadherin, where it has been previously reported to act as a transcriptional activator. Furthermore, chromatin immunoprecipitation assay revealed AP-2alpha binding to the MMP-9 promoter, which ensued by decreased binding of transcription factor Sp-1 and changes in the recruitment of transcription factors to a distal AP-1 element, thus, contributing to the overall downregulation of MMP-9 promoter activity. Collectively, our data provide evidence that AP-2alpha acts as a tumor suppressor gene in colon cancer..

p21 as a prognostic factor in non-small cell lung carcinomas

Few studies have focused on the correlation between p21 expression and survival for patients with non-small cell lung carcinoma (NSCLC), and the results are not consistent. We investigated the expression of p21 in 90 cases of NSCLC to evaluate the correlation between the p21 expression level and the clinicopathologic characteristics with patient survival. p21 was expressed in the nuclei of all the NSCLCs. The percentage of immunoreactive cells varied from 1% to 70%. All the patients were subdivided into a high and a low p21 expression group on the basis of the median percentage (17.05). There was no significant correlation between the p21 expression level and age, gender, histologic type, histologic grade, or stage. Using uni- and multivariate analyses, survival was significantly associated with gender, stage, and the p21 expression level. The survival rate for the high p21 expression group was higher than that for the low p21 expression group in the entire patient group, and especially for stage II and III patients, males, adenocarcinomas, or p53-positive tumors. Our findings showed that high p21 expression was an independent prognostic factor for NSCLC. p21 may be useful for determining the candidates for adjuvant therapies and also for selecting the appropriate chemotherapeutic agents.

Cell cycle related proteins in hyperplasia of usual type in breast specimens of patients with and without breast cancer

BACKGROUND

Hyperplasia of usual type (HUT) is a common proliferative lesion associated with a slight elevated risk for subsequent development of breast cancer. Cell cycle-related proteins would be helpful to determine the putative role of these markers in the process of mammary carcinogenesis. The aim of this study was to analyze the expression of cell cycle related proteins in HUT of breast specimens of patients with and without breast cancer, and compare this expression with areas of invasive carcinomas.

RESULTS

Immunohistochemical evaluation was performed using antibodies against cell cycle related proteins ER, PR, p53, p21, p63, and Ki-67 in hyperplasia of usual type (HUT) in specimens of aesthetic reduction mammaplasty (ARM), in specimens of mammaplasty contralateral to breast cancer (MCC), and in specimens of invasive mammary carcinomas (IMC) presenting HUT in the adjacent parenchyma. The results showed that the immunoexpression of ER, PR, p21, p53, p63, and KI-67 was similar in HUT from the three different groups. The p63 expression in myoepithelial cells showed discontinuous pattern in the majority of HUT, different from continuous expression in normal lobules. Nuclear expression of p53 and p21 was frequently higher expressed in IMC and very rare in HUT. We also found cytoplasmic expression of p21 in benign hyperplastic lesions and in neoplastic cells of IMC.

CONCLUSION

Our data failed to demonstrate different expression of cell cycle related proteins in HUT from patients with and without breast cancer. However, we found discontinuous expression of p63 in myoepithelial cells around HUT adjacent to carcinomas and cytoplasmic expression of p21 in epithelial cells of hyperplastic foci. Further studies are needed to determine how these subgroups relate to molecular abnormalities and cancer risk.

Prognostic implications of p21 (Waf1/Cip1) immunolocalization in multiple myeloma

Protein p21 (Waf1/Cip1) plays a critical role in controlling the cell cycle especially as a check point of G1 and is intimately associated with important cellular activities including differentiation, senescence, tumorigenesis, and apoptosis. In the present study, we examined the expression of p21 in multiple myeloma (MM) cells for prognostic evaluation. The immunocytochemical localization of p21 could be categorized into nuclear and cytoplasmic types. The nuclear-type p21 localization was correlated with the severity of MM and the expression of proliferating cell nuclear antigen and p53. Patients with the nuclear-type p21 localization survived significantly shorter than those with the cytoplasmic-type localization. Thus, the present study suggests that p21-immunolocalization can be a useful prognostic marker of MM.

AP2alpha alters the transcriptional activity and stability of p53

AP2alpha and p53 form nuclear complexes that establish a functional partnership, which regulates the expression of certain genes involved in cell growth and metastasis. The growth effects of AP2alpha are mediated through p21WAF1/CIP1 and the ability for AP2alpha to coactivate p21 requires p53. Herein, we have localized the AP2-binding region of p53 to amino acids 305-375. Analysis of 26 distinct p53 alleles established a correlation between AP2alpha binding and transcriptional coactivation. The L350P point mutation was the only nonbinding allele that retained normal transcriptional activity by reporter assay. Although both wild-type and L350P alleles facilitated binding of AP2alpha to the p21 promoter, the L350P allele was significantly reduced in its ability to induce the endogenous p21 gene, demonstrating a striking difference in activity comparing reporter assays with activation of endogenous p53 target genes. Interestingly, expression of AP2 in the absence of radiation repressed p53-mediated induction of p21 and this effect was explained by a reduction in p53 stability induced by AP2alpha overexpression. We conclude that AP2alpha has competing effects on p53 activity through coactivation and decreased stability. These findings may provide a mechanism to account for the discrepancies reported for the association between AP2 and p21 expression in tumor tissue.

CpG island methylation and histone modifications: biology and clinical significance

The discovery that drastic changes in DNA methylation and histone modifications are common in human tumors has inspired various laboratories and pharmaceutical companies to develop and study epigenetic drugs. One of the most promising groups of agents is the inhibitors of histone deacetylases (HDACs), which have different biochemical and biologic properties but have a single common activity: induction of acetylation in histones, the key proteins in nucleosome and chromatin structure. HDAC inhibitors may act through the transcriptional reactivation of dormant tumor-suppressor genes. However, their pleiotropic nature leaves open the possibility that their well-known differentiation, cell-cycle arrest, and apoptotic properties are also involved in other functions associated with HDAC inhibition. Many phase I clinical trials indicate that HDAC inhibitors appear to be well-tolerated drugs. Thus, the field is ready for rigorous biologic and clinical scrutiny to validate the therapeutic potential of these drugs. HDAC inhibitors, probably in association with classical chemotherapy drugs or in combination with DNA-demethylating agents, could be promising drugs for cancer patients.

Proliferative markers as prognostic and predictive tools in early breast cancer: where are we now?

In the last few decades, proliferative markers have been broadly evaluated as prognostic and predictive factors for early stage breast cancer patients. Several papers evaluating one or more markers have been published, often with contradictory results. As a consequence, there is still uncertainty about the role of these proliferative markers. The present paper critically reviews the current knowledge about the following markers: thymidine labeling index, S phase fraction/flow cytometry, Ki 67, thymidine kinase (TK), cyclins E, cyclin D, the cyclin inhibitors p27 and p21, and topoisomerase IIalpha. For each marker, the prognostic and predictive role was separately analyzed. Only papers published in English in peer-reviewed journals before June 2004 that include at least 100 evaluable patients were selected. In addition, the prognostic and predictive role of the proliferative markers had to be assessed through multivariate analyses. One hundred and thirty-two papers fulfilled these criteria and 159 516 patients were analyzed. Unfortunately, several methodological problems in the research to date prevent us from including any one of these proliferative markers among the standard prognostic and predictive factors. Early incorporation of translational research and new technologies with clinical trials are needed to prospectively validate biological markers and allow their use in clinical practice.

Phosphorylation/cytoplasmic localization of p21Cip1/WAF1 is associated with HER2/neu overexpression and provides a novel combination predictor for poor prognosis in breast cancer patients

PURPOSE

The diversity of biological functions makes p21(Cip1/WAF1) (p21) a controversial marker in predicting the prognosis of breast cancer patients. Recent laboratory studies revealed that the regulation of p21 function could be related to different subcellular localizations of p21 by Akt-induced phosphorylation at threonine 145 in HER2/neu-overexpressing breast cancer cells. The purpose of this study was to verify these findings in clinical settings.

EXPERIMENTAL DESIGN

The expression status of the key biological markers in the HER2/neu-Akt-p21 pathway in 130 breast cancer specimens was evaluated by immunohistochemical staining and correlated with patients' clinical parameters and survival. In addition, an antibody against phospho-p21 at threonine 145 [phospho-p21 (T145)] was also used for better validation of these findings.

RESULTS

Cytoplasmic localization of p21 is highly correlated with overexpression of phospho-p21 (T145). Both cytoplasmic p21 and overexpression of phospho-p21 (T145) are associated with high expression of HER2/neu and phospho-Akt. Cytoplasmic localization of p21 and overexpression of phospho-p21 (T145), HER2/neu, and phospho-Akt are all associated with worse overall survival. Multivariate analysis of the Cox proportional hazard regression model revealed that cytoplasmic p21 and overexpression of HER2/neu are independently associated with increased risk of death. Combining these two factors stratified patients' survival into four distinct groups, with a 5-year survival rate of 79% in low HER2/neu and negative/nuclear p21 patients, 60% in high HER2/neu and negative/nuclear p21 patients, 29% in low HER2/neu and cytoplasmic p21 patients, and 16% in high HER2/neu and cytoplasmic p21 patients.

CONCLUSIONS

The present study, in addition to supporting the mechanisms of p21 regulation derived from laboratory investigation, demonstrates the prognostic importance of phospho-p21 (T145) for the first time and also provides a novel combination of p21 and HER2/neu for better stratification of patients' survival than any single clinicopathological or biological marker that may play important diagnostic and therapeutic roles for breast cancer patients.

Cyclin D1, cyclin E, and p21 have no apparent prognostic value in anal carcinomas treated by radiotherapy with or without chemotherapy

The purpose of this study was to assess the potential prognostic and/or predictive value of the expression of cyclin D1, cyclin E, and p21 protein in a series of 98 anal carcinomas (T1–4, N0–3) treated by radiotherapy with (51) or without (47) chemotherapy in one institution. Correlation with Mib1 index and p53 expression was also investigated. Median follow-up for surviving patients was 124 months (range: 30–266). Immunohistochemical staining was performed on pretreatment biopsies, applying a standard ABC technique for cyclin D1 (clone DSC6, DAKO, 1 : 300), cyclin E (clone 13A3, Novocastra, 1 : 100), p21^WAF/CIP1 (clone SX118, DAKO, 1 : 50), p53 (clone DO7, DAKO, 1 : 200), and Mib1 (Ki-67, Dianova, 1 : 20). Tumours were classified into low- or high-expression groups according to the expression level of the protein considered. High expression was found in 51% of tumours for cyclin E, in 33.7% for cyclin D1, and in 65% for p21. None of those factors were significantly associated with clinical variables such as advanced T or N categories. In a monovariate analysis, advanced T and N categories and longer overall treatment time were the only variables that correlated significantly with low rate of local control (LC) and disease-free survival. However, in a subgroup analysis, high p21 expression correlated with a trend for significantly higher 5-year LC (87 vs 68%, P=0.07) in the N0 patients. The results of this study suggest that the cell-cycle proteins investigated are unlikely to be clinically useful in predicting treatment response or prognosis in patients with anal carcinomas.

Histone deacetylase inhibitors: understanding a new wave of anticancer agents

Cancer is as much an epigenetic disease as it is a genetic and cytogenetic disease. The discovery that drastic changes in DNA methylation and histone modifications are commonly found in human tumors has inspired various laboratories and pharmaceutical companies to develop and study epigenetic drugs. One of the most promising groups of agents is the inhibitors of histone deacetylases (HDACs), which have different biochemical and biologic properties but have a single common activity: induction of acetylation in histones, the key proteins in nucleosome and chromatin structure. One of the main mechanisms of action of HDAC inhibitors is the transcriptional reactivation of dormant tumor-suppressor genes, such as p21WAF1. However, their pleiotropic nature leaves open the possibility that their well-known differentiation, cell-cycle arrest and apoptotic properties are also involved in other functions associated with HDAC inhibition. Many phase I clinical trials indicate that HDAC inhibitors appear to be well-tolerated drugs. Thus, the field is ready for rigorous biologic and clinical scrutiny to validate the therapeutic potential of these drugs. Our current data indicate that the use of HDAC inhibitors, probably in association with classical chemotherapy drugs or in combination with DNA-demethylating agents, could be promising for cancer patients.

Expression of HER2 and its association with AP-2 in breast cancer

The aim of the study was to investigate the relationship between the expression of human epidermal growth factor receptor 2 (HER2) and activator protein 2 (AP-2), as well as the prognostic significance of HER2 in breast cancer. HER2 and AP-2 expressions were immunohistochemically (IHC) analysed in a large prospective, consecutive series of 425 breast cancer patients diagnosed and treated between 1990 and 1995 at the Kuopio University Hospital, Kuopio, Finland. In a subset of patients (n = 71), the gene amplification status was examined by using a chromogenic in situ hybridisation (CISH) analysis. Expression of HER2 was studied in relation to AP-2, clinicopathological parameters and patients' survival. Pathological membranous overexpression of the HER2 receptor was seen in 13% of the carcinomas, which was related both to gene amplification (78% of the cases) and high nuclear expression of AP-2 (67%, P = 0.007). HER2-positivity was most often seen in carcinomas having both high nuclear and high cytoplasmic AP-2 expression (P < 0.001). In the univariate survival analyses HER2-positivity predicted a shorter recurrence-free survival (RFS) (P < 0.0001) and a shorter breast cancer-related survival (BCRS) (P = 0.0063) in the whole patient group, as well as in the subgroup of node-negative patients. In the node-positive patients, HER2-positivity predicted only a shorter RFS. Combined expression of HER2 and nuclear AP-2 resulted in the separation of four groups with different prognoses, the best prognosis being for patients in the HER2-/AP-2+ group and the worse prognosis for those in the HER2+/AP-2- group. In the multivariate survival analyses, HER2-positivity independently predicted a shorter RFS in the whole patient group (P = 0.0067), as well as in the subgroup of node-positive patients (P = 0.0209). In conclusion, pathological membranous overexpression of the HER2 receptor in breast cancer is related both to gene amplification and a high AP-2 expression. Combining HER2 and AP-2 expressions may provide valuable information on the prognosis of breast cancer patients.

Stat5a is tyrosine phosphorylated and nuclear localized in a high proportion of human breast cancers

Signal transducers and activators of transcription (STATs) are latent cytoplasmic transcription factors that are activated and translocated into the nucleus after phosphorylation at a conserved tyrosine residue. Mouse model studies have demonstrated that activated Stat5a acts as a critical survival factor for normal, preneoplastic and malignant mammary epithelial cells. Very limited information is available, however, on the expression, tyrosine phosphorylation status and nuclear localization of Stat5a in human breast cancers. In our study, the pattern of Stat5a cellular localization was analyzed by immunohistochemistry in a series of 83 randomly selected primary human breast adenocarcinomas. Immunoprecipitation/Western blotting and immunohistochemistry assays employing different phospho-specific antibodies verified Stat5a tyrosine phosphorylation status. Stat5a was nuclear localized and tyrosine phosphorylated in 59 of 78 (76%) breast cancers examined; 38 of 78 (49%) demonstrated Stat5a nuclear localization in more than 25% of the breast cancer cells within the adenocarcinomas. Nuclear localized Stat5a was associated positively with increased levels of histologic differentiation (p = 0.03). A statistically significant positive association with p27 nuclear localization also was identified (p = 0.05). No relationship was found between nuclear localized Stat5a and menopausal status, tumor size, ploidy, percentage of cells in S-phase, lymph node metastases, ER, ErbB2, nuclear localized p21 or nuclear localized Stat5b/Stat3. As its role in human breast cancer progression and response to therapy is defined, Stat5a could become a new molecular target for breast cancer therapy.

Cytoplasmic p21WAF1/CIP1 expression is correlated with HER-2/ neu in breast cancer and is an independent predictor of prognosis

BACKGROUND

HER-2 (c-erbB2/Neu) predicts the prognosis of and may influence treatment responses in breast cancer. HER-2 activity induces the cytoplasmic location of p21WAFI/CIPI in cell culture, accompanied by resistance to apoptosis. p21WAFI/CIPI is a cyclin-dependent kinase inhibitor activated by p53 to produce cell cycle arrest in association with nuclear localisation of p21WAFI/CIPI. We previously showed that higher levels of cytoplasmic p21WAFI/CIPI in breast cancers predicted reduced survival at 5 years. The present study examined HER-2 and p21WAFI/CIPI expression in a series of breast cancers with up to 9 years of follow-up, to evaluate whether in vitro findings were related to clinical data and the effect on outcome.

METHODS

The CB11 anti-HER2 monoclonal antibody and the DAKO Envision Plus system were used to evaluate HER-2 expression in 73 patients. p21WAFI/CIPI staining was performed as described previously using the mouse monoclonal antibody Ab-1 (Calbiochem, Cambridge, MA, USA).

RESULTS

HER-2 was evaluable in 67 patients and was expressed in 19% of cases, predicting reduced overall survival (P = 0.02) and reduced relapse-free survival (P = 0.004; Cox regression model). HER-2-positive tumours showed proportionately higher cytoplasmic p21WAFI/CIPI staining using an intensity distribution score (median, 95) compared with HER-2-negative cancers (median, 47) (P = 0.005). There was a much weaker association between nuclear p21WAFI/CIPI and HER-2 expression (P = 0.05), suggesting an inverse relationship between nuclear p21WAF1/CIP1 and HER-2.

CONCLUSION

This study highlights a new pathway by which HER-2 may modify cancer behaviour. HER-2 as a predictor of poor prognosis may partly relate to its ability to influence the relocalisation of p21WAFI/CIPI from the nucleus to the cytoplasm, resulting in a loss of p21WAFI/CIPItumour suppressor functions. Cytoplasmic p21WAFI/CIPI may be a surrogate marker of functional HER-2 in vivo.

Differential effects of cell cycle regulatory protein p21(WAF1/Cip1) on apoptosis and sensitivity to cancer chemotherapy

p21(WAF1/Cip1) was initially identified as a cell cycle regulatory protein that can cause cell cycle arrest. It is induced by both p53-dependent and p53-independent mechanisms. This mini-review briefly discusses its currently known functions in apoptosis and drug sensitivity. As an inhibitor of cell proliferation, p21(WAF1/Cip1) plays an important role in drug-induced tumor suppression. Nevertheless, a number of recent studies have shown that p21(WAF1/Cip1) can assume both pro- or anti-apoptotic functions in response to anti-tumor agents depending on cell type and cellular context. This dual role of p21(WAF1/Cip1) in cancer cells complicates using p21(WAF1/Cip1) status to predict response to anti-tumor agents. However, it is possible to develop p21(WAF1/Cip1)-targeted reagents or p21(WAF1/Cip1) gene transfer techniques to have a beneficial effect within a well-defined therapeutic context. Better understanding of the roles of p21(WAF1/Cip1) in tumors should enable a more rational approach to anti-tumor drug design and therapy.