Advances in managing breast cancer: a clinical update

Effect of quercetin on doxorubicin cytotoxicity in sensitive and resistant human MCF7 breast cancer cell lines

Chemoresistance is the major cause of cancer recurrence, relapse and eventual death. Doxorubicin resistance is one such challenge in breast cancer. The use of quercetin, an antioxidant, in combination with doxorubicin has been investigated for offering protection to normal cells from the toxic side effects of doxorubicin in addition to modulation of its resistance. The present study aimed to investigate the effects of quercetin in prevention of a doxorubicin-chemoresistant phenotype in both doxorubicin-sensitive and -resistant human MCF-7 breast cancer cell lines. A doxorubicin-resistant MCF-7 cell line was established. The development of resistant cells was closely monitored for changes in morphological features. Sensitivity to doxorubicin and the doxorubicin/quercetin combination was assessed using the tetrazolium assay. To determine the mechanism by which quercetin sensitizes the doxorubicin MCF-7-resistant cell line to doxorubicin, gene expression alterations in breast cancer-related genes were examined using the reverse transcription-quantitative PCR (RT-qPCR) array technology. Resistant MCF cells were successfully developed and the inhibitory concentration (IC50) value of doxorubicin increased from 0.133 to 4 µM (wild-type to resistant). The effects of the quercetin/doxorubicin combination exhibited different effects on wild-type vs. resistant cells. The IC50 of doxorubicin was reduced in wild cells, whereas resistant cells showed an increase in cell viability at lower concentrations and a potentiation of the effects of doxorubicin only at higher concentrations. Annexin V/propidium iodide staining demonstrated that quercetin drives cells into late apoptosis and necrosis, but in resistant cells, necrosis predominates. RT-qPCR results revealed that quercetin led to a reversal in doxorubicin effects via up- and downregulation of important genes such as SNAI2, PLAU and CSF1 genes. Downregulation of cell migration genes, SNAI2 (-31.23-fold) and plasminogen activator, urokinase (PLAU; -30.62-fold), and the apoptotic pathway gene, colony stimulating factor 1 (CSF1; -17.25-fold) were the most important querticin-associated events. Other gene alterations were also observed involving cell cycle arrest and DNA repair pathways. The results of the present study indicated that quercetin could lead to a reversal of doxorubicin resistance in breast cancer cells via downregulation of the expression of important genes, such as SNAI2, PLAU and CSF1. Such findings may represent a potential strategy for reversing breast cancer cell-related chemoresistance.

TRP Channels: The Neglected Culprits in Breast Cancer Chemotherapy Resistance?

Breast cancer is a major health concern worldwide, and resistance to therapies remains a significant challenge in treating this disease. In breast cancer, Transient Receptor Potential (TRP) channels are well studied and constitute key players in nearly all carcinogenesis hallmarks. Recently, they have also emerged as important actors in resistance to therapy by modulating the response to various pharmaceutical agents. Targeting TRP channels may represent a promising approach to overcome resistance to therapies in breast cancer patients.

Breast cancer resistance to chemotherapy: When should we suspect it and how can we prevent it?

Chemotherapy is an essential treatment for breast cancer, inducing cancer cell death. However, chemoresistance is a problem that limits the effectiveness of chemotherapy. Many factors influence chemoresistance, including drug inactivation, changes in drug targets, overexpression of ABC transporters, epithelial-to-mesenchymal transitions, apoptotic dysregulation, and cancer stem cells. The effectiveness of chemotherapy can be assessed clinically and pathologically. Clinical response evaluation is based on physical examination or imaging (mammography, ultrasonography, computed tomography scan, or magnetic resonance imaging) and includes tumor size changes after chemotherapy. Pathological response evaluation is a method based on tumor residues in histopathological preparations. We should be suspicious of chemoresistance if there are no significant changes clinically according to the Response Evaluation Criteria in Solid Tumors and World Health Organization criteria or pathological changes according to the Miller and Payne criteria, especially after 2–3 cycles of chemotherapy treatments. Chemoresistance is mostly detected after the administration of chemotherapy drugs. No reliable parameters or biomarkers can predict chemotherapy responses appropriately and effectively. Well-known parameters such as cancer type, grade, subtype, estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, Ki-67, and MDR-1/P-gP have been used for selecting chemotherapy regimens. Some new methods for predicting chemoresistance include chemosensitivity and chemoresistance assays, multigene expressions, and positron emission tomography assays. The latest approaches are based on evaluation of molecular processes and the metabolic activity of cancer cells. Some methods for preventing chemoresistance include using the right regimen, using some combination of chemotherapy methods, conducting adequate monitoring, and using drugs that could prevent the emergence of multidrug resistance.

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Chemotherapy is an essential treatment in the management of breast cancer.

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Chemotherapy is carried out based on the selection of regimens for the specific individual and tumor characteristics.

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Combination therapy, monitoring, and evaluation are used to prevent chemoresistance.

Desloratadine and loratadine stand out among common H1-antihistamines for association with improved breast cancer survival

BACKGROUND

As tumors maintain an inflammatory microenvironment, anti-inflammatory medication can be useful in cancer therapy. We have previously shown an association with improved survival in melanoma for use of the H₁-antihistamines desloratadine and loratadine, and here we examine use of H₁-antihistamines and breast cancer mortality.

MATERIAL AND METHODS

We investigated use of the six major H₁-antihistamines (cetirizine, clemastine, desloratadine, ebastine, fexofenadine and loratadine) and breast cancer-specific and overall mortality in a nation-wide register-based study of all 61,627 Swedish women diagnosed with breast cancer 2006-2013. Both peri- and post-diagnostic antihistamine use was analyzed using Cox regression models. Analyses were stratified for age and subgroup analyses based on estrogen receptor status and menopausal status were performed.

RESULTS

We found a consistently improved survival of desloratadine users (HR = 0.67; 95% CI 0.55-0.81, p < .001), as well as of loratadine users (HR = 0.80; 95% CI 0.67-0.95, p = .012), relative to nonusers, regardless of patient age, menopause, estrogen receptor status or stage of the tumor, or whether breast cancer-specific or overall survival was analyzed. The survival of users of other antihistamines varied relative to non-users.

CONCLUSION

Based on their safety and current use within the patient population, together with our observations, we suggest the initiation of trials of desloratadine and loratadine as treatment of breast cancer as well as studies of the mechanism behind their possible effect. Further studies on any effects of other H₁-antihistamines may also be merited, as well as of H₁-antihistamine use and survival in other malignancies.

Down Regulation of KAI1/CD82 in Lymph Node Positive and Advanced T-Stage Group in Breast Cancer Patients

BACKGROUND

Metastasis represents a deadly aspect of any cancer including breast cancer, given its high prevalence; treatment of metastatic breast cancer remains a clinically unmet need, which necessitates the exploration of metastasis suppressor genes (MSGs). KAI-1/CD82 is an important member of MSGs; the role of KAI1 has been well explored in prostate cancer, however its role in breast cancer is not fully explored and in fact the results of breast cancer studies are contentious. Thus, the present study aimed to investigate expression of KAI1 at both transcriptional and translational levels in the tissue of breast cancer patients and benign breast disease. Further, we analysed the relationship between expression levels of KAI1 and clinicopathological parameters in breast cancer patients.

MATERIALS AND METHODS

mRNA expression was studied by Real time PCR and protein expression was analyzed by both Western blot and Immunohistochemistry.

RESULTS

The results of the study indicate that KAI1 expression was remarkably decreased in breast cancer both at the gene and the protein levels (P < 0.05) compared to benign breast disease. In addition, KAI1 expression levels were strongly associated with axillary lymph node status and advanced T stage (p < 0.05), however no association was found with tumor grade, age, menopausal status and receptor status like ER, PR and Her2.

CONCLUSION

Low expression of KAI1 might be helpful for predicting the lymph node metastasis and T staging, thus predicts malignant prognosis of breast cancer.<br />.

Collective radioresistance of T47D breast carcinoma cells is mediated by a Syncytin-1 homologous protein

It is generally accepted that radiotherapy must target clonogenic cells, i.e., those cells in a tumour that have self-renewing potential. Focussing on isolated clonogenic cells, however, may lead to an underestimate or even to an outright neglect of the importance of biological mechanisms that regulate tumour cell sensitivity to radiation. We develop a new statistical and experimental approach to quantify the effects of radiation on cell populations as a whole. In our experiments, we change the proximity relationships of the cells by culturing them in wells with different shapes, and we find that the radiosensitivity of T47D human breast carcinoma cells in tight clusters is different from that of isolated cells. Molecular analyses show that T47D cells express a Syncytin-1 homologous protein (SyHP). We observe that SyHP translocates to the external surface of the plasma membrane of cells killed by radiation treatment. The data support the fundamental role of SyHP in the formation of intercellular cytoplasmic bridges and in the enhanced radioresistance of surviving cells. We conclude that complex and unexpected biological mechanisms of tumour radioresistance take place at the cell population level. These mechanisms may significantly bias our estimates of the radiosensitivity of breast carcinomas in vivo and thereby affect treatment plans, and they call for further investigations.

Suppression of Kpnβ1 expression inhibits human breast cancer cell proliferation by abrogating nuclear transport of Her2

Breast cancer (BC) is one of the most fatal diseases and poses critical health problems worldwide. However, its mechanisms remain unclear. Consequently, there is an urgency to investigate the mechanisms involved in BC initiation and progression and identify novel therapeutics for its prevention and treatment. In this study, we identified karyopherin β-1 (Kpnβ1) as a possible novel therapeutic target for BC. Western blotting was used to evaluate the expression of Kpnβ1 in four pairs of tumorous and adjacent non-tumorous tissues. The results revealed that the protein level of Kpnβ1 was higher in the cancer samples compared with those in the corresponding normal samples. Immunohistochemistry was performed on 140 BC cases and indicated that Kpnβ1 was significantly associated with clinical pathological variables. Kaplan-Meier curve revealed that high expression of Kpnβ1 was related to poor BC patient prognosis. A starvation and re-feeding assay was used to imitate the cell cycle using the SKBR-3 cell line, indicating that Kpnβ1 plays a critical role in cell proliferation. The Cell Counting Kit-8 assay revealed that SKBR-3 cells treated with Kpnβ1-siRNA (siKpnβ1) grew more slowly than the control cells, while flow cytometry revealed that low-Kpnβ1 expressing SKBR-3 cells exhibited increased BC cell apoptosis. Furthermore, the interaction between Kpnβ1 and Her2 was clearly observed by immunoprecipitation, indicating that Kpnβ1-knockdown abrogated nuclear transport of Her2. In summary, our findings revealed that Kpnβ1 is involved in the progression of BC and may be a useful therapeutic target.

The prognostic value of the tumour-stroma ratio in primary operable invasive cancer of the breast: a validation study

PURPOSE

The primary aim of the current study is to validate the prognostic relevance of the relative amount of tumour-associated stroma, the tumour-stroma ratio, in a large cohort of primary operable breast cancer patients.

METHODS

A retrospective cohort study was performed on women diagnosed and treated for primarily operable invasive breast cancer in the period from 1 January 1990 till 31 December 1999. Tumour-stroma ratio was estimated by microscopic evaluation of haematoxylin and eosin tumour slides. Two independent observers (k = 0.68) performed tumour-stroma ratio evaluation in a significant part of the cohort. The prognostic potential with respect to overall, recurrence-free and distant metastasis-free survival was evaluated.

RESULTS

A total of n = 737 women were evaluated. Median follow-up time was 11.5 years. High stromal content was an independent prognosticator for worse overall (hazard ratio 1.56, p = 0.002, 95% confidence interval 1.18-2.05), distant metastasis-free (hazard ratio 1.52, p = 0.008, 95% confidence interval 1.12-2.06) and recurrence-free survival (hazard ratio 1.35, p = 0.046, 95% confidence interval 1.01-1.81). In subgroups of hormone receptor-positive and lymph node-negative cases, high stromal content was also an independent prognosticator for worse outcome.

CONCLUSION

Tumour-stroma ratio is an independent risk factor for worse overall, distant metastasis-free and recurrence-free survival in primarily operable breast cancer. However, detailed prospective studies with respect to tumour-stroma ratio are necessary to gain more insight in its prognostic potential in clinical practice.

The implications of genetic variation for the pharmacokinetics and pharmacodynamics of aromatase inhibitors

INTRODUCTION

Breast cancer is the most common female cancer and remains a serious public health concern worldwide. Third-generation aromatase inhibitors (AIs) are widely used in postmenopausal women with estrogen receptor positive breast cancer. However, there is marked interindividual variability in terms of the efficacy and incidence of adverse events following treatment with AIs. Pharmacogenetics has the potential to predict clinical outcomes based on patients' genetic information, paving the way towards personalized treatment.

AREAS COVERED

This article reviews pharmacogenetic studies of AIs, including pharmacokinetic and pharmacodynamic aspects, highlighting those studies where the efficacy and adverse events of AIs have been examined using both candidate gene and genome-wide approaches.

EXPERT OPINION

Pharmacogenetics is a promising approach to develop personalized medicine with AIs. However, the application of pharmacogenetics to predict therapeutic efficacy and adverse events in breast cancer patients is still far from implementation in routine clinical practice. Large, comprehensive, multicenter studies that simultaneously evaluate multiple genes and pathways, including rare variants, are warranted in order to produce reliable and informative results. The ultimate aim is to develop clinically-relevant guidelines for breast cancer therapy.

Cancer prevention: state of the art and future prospects

Cancer imposes a heavy societal burden worldwide, in terms of both epidemiology and costs. The introduction of more sophisticated imaging and diagnostic techniques and advanced drugs that specifically target tumor cells is leading to increasingly expensive treatments, which may be affordable only for few patients. Prevention, and particularly primary prevention, is an effective way of addressing the challenging issue of cancer, since between a third and a half of cancers could be prevented on the basis of our current knowledge of risk factors. Moreover, prevention is cost-effective, its effects are not limited to high-risk subjects but extend to the entire population, and it is not dependent on socioeconomic status. Regulatory measures can have a broad impact, even on future generations; by empowering and educating subjects, promoting healthy behaviours and teaching self-care, they can trigger a virtuous cycle. In recent decades, oncology has shifted from being merely reactive to being proactive; this shift has led to the development of so-called "P4 medicine", where the 4 Ps stand for "preventive", "predictive", "personalized" and "participatory". Prevention programs are an important part of the effort to control cancer, as they are able to reduce both the incidence of cancer and mortality. For instance, screening for colorectal, breast and cervical cancer is reducing the burden of these common tumors. Anti-cancer vaccines, both prophylactic and therapeutic, constitute another important preventive tool. Although progress has been made in these areas, much remains to be done. With regard to screening programs, coverage could be increased by introducing new, more acceptable, less invasive tests, stratifying screening through correlation with anamnestic, clinical, radiological and genomic data (so-called "populationbased personalized cancer screening"), and exploiting new information and communication technologies, such as smartphone applications or personalized text messages (so-called "screening 2.0"). Advocacy and recommendations by physicians can also play a role, in that eligible subjects need to be able to discuss their doubts and their perceived psycho-social barriers. However, new screening initiatives should be implemented only after a careful health technology assessment has been performed within the framework of evidence-based medicine, organized screening programs have been strengthened and opportunistic or spontaneous programs have been limited.

Pharmacogenetics and breast cancer management: current status and perspectives

INTRODUCTION

Breast cancer has benefited from a number of innovative therapeutics over the last decade. Cytotoxics, hormone therapy, targeted therapies and biologics can now be given to ensure optimal management of patients. As life expectancy of breast cancer patients has been significantly stretched and that several lines of treatment are now made available, determining the best drug or drug combinations to be primarily given and the best dosing and scheduling for each patient is critical for ensuring an optimal toxicity/efficacy balance.

AREAS COVERED

Defining patient's characteristics at the tumor level (pharmacogenomics) and the constitutional level (pharmacogenetics) is a rising trend in oncology. This review covers the latest strategies based upon the search of relevant biomarkers for efficacy, resistance and toxicity to be undertaken at the bedside to shift towards precision medicine in breast cancer patients.

EXPERT OPINION

In the expanding era of bioguided medicine, identifying relevant and clinically validated biomarkers from the plethora of published material remains an uneasy task. Sorting the variety of genetic and molecular markers that have been investigated over the last decade on their level of evidence and addressing the issue of drug exposure should help to improve the management of breast cancer therapy.